WorldWideScience

Sample records for cerium 124

  1. 1,2,4-Diazaphospholide complexes of lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii): synthesis, X-ray structural characterization, and magnetic susceptibility studies.

    Science.gov (United States)

    Zhao, Minggang; Wang, Lixia; Li, Pangpang; Ma, Jianping; Zheng, Wenjun

    2016-07-01

    A few heteroleptic, charge-separated heterobimetallic, and polymeric alkali metalate complexes of 1,2,4-diazaphospholide lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii) were simply prepared via the metathesis reaction of MCl3 (THF)m (m = 1-2) and K[3,5-R2dp] ([3,5-R2dp](-) = 3,5-di-substituent-1,2,4-diazaphospholide; R = tBu, Ph) in a varied ratio (1 : 3, 1 : 4, and 1 : 5, respectively) at room temperature in tetrahydrofuran. All the complexes were fully characterized by (1)H, (13)C{(1)H}, (31)P{(1)H}, IR, and X-ray single crystal diffraction analysis despite their paramagnetism (excluding La(iii) complexes). The structures of the complexes were found to feature varied coordination modes. The magnetic properties of several compounds were studied by magnetic susceptibility, and the complexes presented the magnetic moments close to or lower than the theoretical values for the free ions in the trivalent oxidation states (Pr(3+), Nd(3+)).

  2. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  3. Probing the cerium/cerium hydride interface using nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Brierley, Martin, E-mail: martin.brierley@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom); University of Manchester, Manchester M13 9PL (United Kingdom); Knowles, John, E-mail: john.knowles@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom)

    2015-10-05

    Highlights: • A disparity exists between the minimum energy and actual shape of a cerium hydride. • Cerium hydride is found to be harder than cerium metal by a ratio of 1.7:1. • A zone of material under compressive stress was identified surrounding the hydride. • No distribution of hardness was apparent within the hydride. - Abstract: A cerium hydride site was sectioned and the mechanical properties of the exposed phases (cerium metal, cerium hydride, oxidised cerium hydride) were measured using nanoindentation. An interfacial region under compressive stress was observed in the cerium metal surrounding a surface hydride that formed as a consequence of strain energy generated by the volume expansion associated with precipitation of the hydride phase.

  4. Splitting a C-O bond in dialkylethers with bis(1,2,4-tri-t-butylcyclopentadienyl) cerium-hydride does not occur by a sigma-bond metathesis pathway: a combined experimental and DFT computational study

    Energy Technology Data Exchange (ETDEWEB)

    Werkema, Evan; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile; Andersen, Richard

    2010-04-06

    Addition of diethylether to [1,2,4(Me3C)3C5H2]2CeH, abbreviated Cp'2CeH, gives Cp'2CeOEt and ethane. Similarly, di-n-propyl- or di-n-butylether gives Cp'2Ce(O-n-Pr) and propane or Cp'2Ce(O-n-Bu) and butane, respectively. Using Cp'2CeD, the propane and butane contain deuterium predominantly in their methyl groups. Mechanisms, formulated on the basis of DFT computational studies, show that the reactions begin by an alpha or beta-CH activation with comparable activation barriers but only the beta-CH activation intermediate evolves into the alkoxide product and an olefin. The olefin then inserts into the Ce-H bond forming the alkyl derivative, Cp'2CeR, that eliminates alkane. The alpha-CH activation intermediate is in equilibrium with the starting reagents, Cp'2CeH and the ether, which accounts for the deuterium label in the methyl groups of the alkane. The one-step sigma-bond metathesis mechanism has a much higher activation barrier than either of the two-step mechanisms.

  5. Mechanochemical synthesis of cerium orthophosphate

    Institute of Scientific and Technical Information of China (English)

    A.Matraszek; I.Szczygiei; L.Macalik; J.Hanuza

    2009-01-01

    A facile,simple and rapid preparation method of cerium orthophosphate was presented.The synthesis of low-crystalline CePO4 occurred upon mixing of cerium (Ⅲ) nitrate and sodium phosphate,and was an exchange-type reaction.The phase composition of the obtained powder was checked by the XRD and FTIR methods,indicating the presence of cerium phosphate.Further investigations on thermal behavior of the synthesized cerium salt had shown that the obtained onhophosphate crystallized at first in rhabdophane-type structure.It convetted to monazite (monoclinic symmetry) during heating at the temperatures of above 600 ℃.Oxidation of Ce3+ to Ce4+ was avoided during the syntheses,as confirmed by the XPS experiments.

  6. PLUTONIUM-CERIUM-COBALT AND PLUTONIUM-CERIUM-NICKEL ALLOYS

    Science.gov (United States)

    Coffinberry, A.S.

    1959-08-25

    >New plutonium-base teroary alloys useful as liquid reactor fuels are described. The alloys consist of 10 to 20 atomic percent cobalt with the remainder plutonium and cerium in any desired proportion, with the plutonium not in excess of 88 atomic percent; or, of from 10 to 25 atomic percent nickel (or mixture of nickel and cobalt) with the remainder plutonium and cerium in any desired proportion, with the plutonium not in excess of 86 atomic percent. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are a lower melting point and a wide range of permissible plutonium dilution.

  7. Dissolution properties of cerium dibutylphosphate corrosion inhibitors

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The corrosion inhibitor cerium dibutylphosphate, Ce(dbp)3, prevents corrosion by cerium and dbp deposition at the alkaline cathode and acidic anode respectively. The pH dependent Ce(dbp)3 solubility seems to play an essential role in the inhibition degree. We found that Ce(dbp) 3 scarcely dissolves

  8. Cerium extraction by metallothermic reduction using cerium oxide powder injection

    Institute of Scientific and Technical Information of China (English)

    J.S. Luna A; A. Flores V; R. Mu(n)iz V; A.F. Fuentes; J. Torres; N. Rodríuez R; J.C. Ortiz; P.Orozco

    2011-01-01

    This work presented the feasibility of cerium recovery by Al-Mg alloy through the metallothermic reduction of CeO2 to obtain a master alloy Al-4%Ce. The master alloy obtained in this investigation was for the grain refinement and modification of Al-Si alloys. The reagent was incorporated into a molten alloy using the submerged powder injection technique, and metallic samples were obtained during injection. Chemical and microstructural analyses (by inductively coupled plasma (ICP) and scanning electron microscopy (SEM), respectively) confirmed the possibility of Ce uptake in the bath (0 to 4 wt.%), as CeO2 was reduced through metallothermic reactions in the molten alloys.Based on the characterization of reaction products, the sequence of the reaction was proposed.

  9. Some Environmentally Relevant Reactions of Cerium Oxide

    Directory of Open Access Journals (Sweden)

    Janoš Pavel

    2014-12-01

    Full Text Available Reactive forms of cerium oxide were prepared by a thermal decomposition of various precursors, namely carbonates, oxalates and citrates, commercially available nanocrystalline cerium oxide (nanoceria was involved in the study for comparison. Scanning electron microscopy (SEM and x-ray diffraction analysis (XRD were used to examine the morphology and crystallinity of the samples, respectively, whereas the Brunauer-Emmett-Teller (BET method of nitrogen adsorption was used to determine surface areas. Interactions of cerium oxide with some phosphorus-containing compounds were investigated. Some of the examined samples, especially those prepared by annealing from carbonate precursors, exhibited an outstanding ability to destroy highly toxic organophosphates, such as pesticides (parathion methyl, or nerve agents (soman, VX. There were identified some relations between the degradation efficiency of cerium oxides and their crystallinity. It was also shown that cerium oxide is able to destroy one of widely used flame retardants - triphenyl phosphate. A phosphatase-mimetic activity of various cerium oxides was examined with the aid of a standardized phosphatase test.

  10. Pharmacological potential of cerium oxidenanoparticles

    Science.gov (United States)

    Celardo, Ivana; Pedersen, Jens Z.; Traversa, Enrico; Ghibelli, Lina

    2011-04-01

    Nanotechnology promises a revolution in pharmacology to improve or create ex novo therapies. Cerium oxidenanoparticles (nanoceria), well-known as catalysts, possess an astonishing pharmacological potential due to their antioxidant properties, deriving from a fraction of Ce3+ ions present in CeO2. These defects, compensated by oxygen vacancies, are enriched at the surface and therefore in nanosized particles. Reactions involving redox cycles between the Ce3+ and Ce4+oxidation states allow nanoceria to react catalytically with superoxide and hydrogen peroxide, mimicking the behavior of two key antioxidant enzymes, superoxide dismutase and catalase, potentially abating all noxious intracellularreactive oxygen species (ROS) via a self-regenerating mechanism. Hence nanoceria, apparently well tolerated by the organism, might fight chronic inflammation and the pathologies associated with oxidative stress, which include cancer and neurodegeneration. Here we review the biological effects of nanoceria as they emerge from in vitro and in vivo studies, considering biocompatibility and the peculiar antioxidant mechanisms.

  11. Nanocrystalline cerium oxide materials for solid fuel cell systems

    Science.gov (United States)

    Brinkman, Kyle S

    2015-05-05

    Disclosed are solid fuel cells, including solid oxide fuel cells and PEM fuel cells that include nanocrystalline cerium oxide materials as a component of the fuel cells. A solid oxide fuel cell can include nanocrystalline cerium oxide as a cathode component and microcrystalline cerium oxide as an electrolyte component, which can prevent mechanical failure and interdiffusion common in other fuel cells. A solid oxide fuel cell can also include nanocrystalline cerium oxide in the anode. A PEM fuel cell can include cerium oxide as a catalyst support in the cathode and optionally also in the anode.

  12. CHEMICAL BEHAVIOR OF CERIUM ELEMENT IN ROCK WEATHERING SYSTEM

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A study on existing valence state and chemical behavior of cerium element in two categories of rock weathering system in China has been carried out. In the granitoid weathering crust of Southern China,cerium as tetravalent hydroxide absorbed on clay minerals occupies 62.58 % of total amount of cerium and the cerium partitioning in the phase is 69.58 %. The depositing cerium stops its mobility downward, resulting in rare earth partitioning variation, the light rare earth partitioning is high at upper layer of weathering crust, the heavy rare earth partitioning is high at bottom layer of weathering crust, and the extracted product exists cerium lose effect. For Mn2+ as reducing agent existing in black weathering earth of Maoniuping rare earth ore,cerium is trivalent and absorbed on Mn-Fe oxide as colloid phase sediment. Colloid sediment phase can be divided into Mn-Fe combined phase and hydroxide sediment phase with cerium contents of 19.77% and 48.30%, and their cerium partitionings are 80.72% and 37.38% respectively. The Mn-Fe combined phase can selectively absorb cerium.

  13. Uptake and accumulation of bulk and nanosized cerium oxide particles and ionic cerium by radish (Raphanus sativus L.).

    Science.gov (United States)

    Zhang, Weilan; Ebbs, Stephen D; Musante, Craig; White, Jason C; Gao, Cunmei; Ma, Xingmao

    2015-01-21

    The potential toxicity and accumulation of engineered nanomaterials (ENMs) in agricultural crops has become an area of great concern and intense investigation. Interestingly, although below-ground vegetables are most likely to accumulate the highest concentrations of ENMs, little work has been done investigating the potential uptake and accumulation of ENMs for this plant group. The overall objective of this study was to evaluate how different forms of cerium (bulk cerium oxide, cerium oxide nanoparticles, and the cerium ion) affected the growth of radish (Raphanus sativus L.) and accumulation of cerium in radish tissues. Ionic cerium (Ce(3+)) had a negative effect on radish growth at 10 mg CeCl3/L, whereas bulk cerium oxide (CeO2) enhanced plant biomass at the same concentration. Treatment with 10 mg/L cerium oxide nanoparticles (CeO2 NPs) had no significant effect on radish growth. Exposure to all forms of cerium resulted in the accumulation of this element in radish tissues, including the edible storage root. However, the accumulation patterns and their effect on plant growth and physiological processes varied with the characteristics of cerium. This study provides a critical frame of reference on the effects of CeO2 NPs versus their bulk and ionic counterparts on radish growth.

  14. Synthesis of Cerium-Doped Titania Nanoparticles and Nanotubes.

    Science.gov (United States)

    Cao, Wei; Suzuki, Takuya; Elsayed-Ali, Hani E; Abdel-Fattah, Tarek M

    2015-03-01

    Cerium-doped titania nanoparticles and nanotubes were synthesized via hydrothermal processes. X-Ray Diffraction revealed that cerium-doped titania nanoparticles have an anatase crystal structure, while cerium-doped titania nanotubes have an H2Ti3O7-type structure. Scanning electron microscopy and high resolution transmission electron microscopy showed that both types of titania are well crystallized with relatively uniform size distribution. The photocatalytic degradation of methylthioninium chloride known as methylene blue dye was tested and both cerium-doped titania nanoparticles and nanotubes. The preliminary photocatalytic degradation of Methylene Blue data showed significantly improved visible light photocatalytic activities as compared to commercial titania powders.

  15. Cerium and jojoba in engines?; Cerium et jojoba dans les moteurs?

    Energy Technology Data Exchange (ETDEWEB)

    Massy-Delhotel, E.

    1996-10-01

    The Belgium company CreaTel proposes a new system, called Forac, which can lead to a 10% reduction of fuel consumption in thermal engines together with a quasi-complete reduction of CO, HC, NOx pollutants and CO{sub 2} particulates emission. The system comprises a steam production device and an admission pipe with a cerium alloy whorl inside. The steam produced is mixed with the admission air and tears cerium particles from the inside of the admission pipe to the combustion chamber. The cerium particles act as a catalyst which favours the complete combustion of the fuel. The same company proposes also lubricant additives made from liquid jojoba wax which allow the reduction of pollutant emissions, fuel consumption and noise emissions of diesel engines. (J.S.)

  16. Thermodynamics of congruently subliming cerium-antimony

    Energy Technology Data Exchange (ETDEWEB)

    Schiffman, R.A.; Franzen, H.F.

    1982-01-01

    Congruently vaporizing cerium-antimony has been investigated by vapor pressure measurementa using a simultaneous weight-loss mass-spectrometric Knudsen effusion technique. The melting point of the 1:1 stoichiometry was determined to be 2179 +/- 10 K. The heat of formation at 298 K of CeSb was found to be -128.9 kJ/g-at from thermodynamic measurements in the temperature range 1985-2172 K.

  17. Environmental Geochemistry of Cerium: Applications and Toxicology of Cerium Oxide Nanoparticles

    OpenAIRE

    2015-01-01

    Cerium is the most abundant of rare-earth metals found in the Earth’s crust. Several Ce-carbonate, -phosphate, -silicate, and -(hydr)oxide minerals have been historically mined and processed for pharmaceutical uses and industrial applications. Of all Ce minerals, cerium dioxide has received much attention in the global nanotechnology market due to their useful applications for catalysts, fuel cells, and fuel additives. A recent mass flow modeling study predicted that a major source of CeO2 na...

  18. Structural, optical, morphological and dielectric properties of cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Prabaharan, Devadoss Mangalam Durai Manoharadoss [Department of Physics, NPR College of Engineering and Technology, Natham, Dindigul, Tamil Nadu (India); Sadaiyandi, Karuppasamy [Department of Physics, Alagappa Government Arts College, Karaikudi, Sivaganga, Tamil Nadu (India); Mahendran, Manickam [Department of Physics, Thiagarajar College of Engineering, Madurai, Tamil Nadu (India); Sagadevan, Suresh, E-mail: duraiphysics2011@gmail.com [Department of Physics, AMET University (India)

    2016-03-15

    Cerium oxide (CeO{sub 2}) nanoparticles were prepared by the precipitation method. The average crystallite size of cerium oxide nanoparticles was calculated from the X-ray diffraction (XRD) pattern and found to be 11 nm. The FT-IR spectrum clearly indicated the strong presence of cerium oxide nanoparticles. Raman spectrum confirmed the cubic nature of the cerium oxide nanoparticles. The Scanning Electron Microscopy (SEM) analysis showed that the nanoparticles agglomerated forming spherical-shaped particles. The Transmission Electron Microscopic (TEM) analysis confirmed the prepared cerium oxide nanoparticles with the particle size being found to be 16 nm. The optical absorption spectrum showed a blue shift by the cerium oxide nanoparticles due to the quantum confinement effect. The dielectric properties of cerium oxide nanoparticles were studied for different frequencies at different temperatures. The dielectric constant and the dielectric loss of the cerium oxide nanoparticles decreased with increase in frequency. The AC electrical conductivity study revealed that the conduction depended on both the frequency and the temperature. (author)

  19. Study of the cerium(IV)-picrate system in acetonitrile.

    Science.gov (United States)

    Kratochvil, B; Tipler, M; McKay, B

    1966-07-01

    A potentiometric and spectrophotometric study has been made of the reaction between hexanitratocerate and picrate in dry acetonitrile. Several cerium(IV)-picrate complexes are formed; the formation constant for the first is estimated to be 4 from spectrophotometric measurements. The catalytic effect of picrate on hydroquinone oxidation by nitratocerate is postulated to be due to more rapid electron transfer by cerium picrate complexes.

  20. Formation and characterization of cerium conversion coatings on magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    LI Lingjie; LEI Jinglei; YU Shenghai; TIAN Yujing; JIANG Qiquan; PAN Fusheng

    2008-01-01

    Chemical conversion treatment by rare earth metal salt solution was considered as an alternative to chromium chemical conversion treatment to improve the corrosion resistance of magnesium alloys. In this study, cerium conversion coatings formed on AZ31 magnesium alloy were characterized and the formation mechanism was discussed. X-ray photoelectron spectroscopy (XPS) analysis showed that cerium conversion coating consisted of cerium hydroxides/oxides, in which both tetravalent cerium Ce(IV) and trivalent cerium Ce(III) species co-existed. Cerium conversion coating was a two-layer structure. Atomic force microscopy (AFM) images revealed that the morphology of the inside layer was different from that of the outside one, which was responsible for the inherent adhesive weakness of the coating. Corrosion potential (Ecorr) measurements indicated that poor adhesion limited the improvement of the corrosion resistance of the coating. During the treating process, the increased pH value of the cerium salt solution led to the precipitation of cerium hydroxides/oxides. The formation kinetics of the coating followed a parabolic curve.

  1. Ultrathin, epitaxial cerium dioxide on silicon

    Science.gov (United States)

    Flege, Jan Ingo; Kaemena, Björn; Höcker, Jan; Bertram, Florian; Wollschläger, Joachim; Schmidt, Thomas; Falta, Jens

    2014-03-01

    It is shown that ultrathin, highly ordered, continuous films of cerium dioxide may be prepared on silicon following substrate prepassivation using an atomic layer of chlorine. The as-deposited, few-nanometer-thin Ce2O3 film may very effectively be converted at room temperature to almost fully oxidized CeO2 by simple exposure to air, as demonstrated by hard X-ray photoemission spectroscopy and X-ray diffraction. This post-oxidation process essentially results in a negligible loss in film crystallinity and interface abruptness.

  2. Cerium-tannic acid passivation treatment on galvamzed steel

    Institute of Scientific and Technical Information of China (English)

    LIU Guangming; YU Fei; YANG Liu; TIAN Jihong; DU Nan

    2009-01-01

    A novel cerium-tannic acid passivation treatment was performed on galvanized steel. The corrosion resistance of cerium-tannic passivated samples was tested by dropping test with 0.5 wt.% CuSO4 aqueous solution. The mass loss per unit area of passivated samples was measured after the corrosion in 0.5 mol/L NaCl + 0.005 mol/L H2SO4 at room temperature for 96 h. The electrochemical behaviors of cerium, tannic acid, and cerium-tannic acid passivated samples on galvanized steel in 0.5 mol/L NaCI solution were investigated by polarization curves and electrochemical impendence spectra. The corrosion equivalent circuit was established according to the impedance characteristics. The results show that cerium-tannic acid treated samples exhibit better corrosion resistance than the sole cerium or tannic acid treated samples under the same condition. The mechanism of synergistic effect for cerium-tannic acid passivation on galvanized steel was discussed.

  3. Atomic Transition Probabilities for Neutral Cerium

    Science.gov (United States)

    Chisholm, John; Nitz, D.; Sobeck, J.; Den Hartog, E. A.; Wood, M. P.; Lawler, J. E.

    2010-01-01

    Among the rare earth species, the spectra of neutral cerium (Ce I) and singly ionized cerium (Ce II) are some of the most complex. Like other rare earth species, Ce has many lines in the visible which are suitable for elemental abundance studies. Recent work on Ce II transition probabilities [1] is now being augmented with similar work on Ce I for future studies using such lines from astrophysical sources. Radiative lifetimes from laser induced fluorescence measurements [2] on neutral Ce are being combined with emission branching fractions from spectra recorded using a Fourier transform spectrometer. A total of 14 high resolution spectra are being analyzed to determine branching fractions for 2500 to 3000 lines from 153 upper levels in neutral Ce. Representative data samples and progress to date will be presented. This work was supported by the National Science Foundation's REU program and the Department of Defense's ASSURE program through NSF Award AST-0453442 and NSF Grant CTS0613277. [1] J. E. Lawler, C. Sneden, J. J. Cowan, I. I. Ivans, and E. A. Den Hartog, Astrophys. J. Suppl. Ser. 182, 51-79 (2009). [2] E. A. Den Hartog, K. P. Buettner, and J. E. Lawler, J. Phys. B: Atomic, Molecular & Optical Physics 42, 085006 (7pp) (2009).

  4. Photodissociation of Cerium Oxide Nanocluster Cations.

    Science.gov (United States)

    Akin, S T; Ard, S G; Dye, B E; Schaefer, H F; Duncan, M A

    2016-04-21

    Cerium oxide cluster cations, CexOy(+), are produced via laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum displays a strongly preferred oxide stoichiometry for each cluster with a specific number of metal atoms x, with x ≤ y. Specifically, the most prominent clusters correspond to the formula CeO(CeO2)n(+). The cluster cations are mass selected and photodissociated with a Nd:YAG laser at either 532 or 355 nm. The prominent clusters dissociate to produce smaller species also having a similar CeO(CeO2)n(+) formula, always with apparent leaving groups of (CeO2). The production of CeO(CeO2)n(+) from the dissociation of many cluster sizes establishes the relative stability of these clusters. Furthermore, the consistent loss of neutral CeO2 shows that the smallest neutral clusters adopt the same oxidation state (IV) as the most common form of bulk cerium oxide. Clusters with higher oxygen content than the CeO(CeO2)n(+) masses are present with much lower abundance. These species dissociate by the loss of O2, leaving surviving clusters with the CeO(CeO2)n(+) formula. Density functional theory calculations on these clusters suggest structures composed of stable CeO(CeO2)n(+) cores with excess oxygen bound to the surface as a superoxide unit (O2(-)).

  5. Fire retardancy of emulsion polymerized poly (methyl methacrylate)/cerium(IV) dioxide and polystyrene/cerium(IV) dioxide nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Guipeng [Department of Chemistry and Fire Retardant Research Facility, Marquette University, PO Box 1881, Milwaukee, WI 53201 (United States); Lu, Hongdian [Department of Chemical and Materials Engineering, Hefei University, Hefei, Anhui 230022 (China); Zhou, You; Hao, Jianwei [School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Wilkie, Charles A., E-mail: charles.wilkie@marquette.edu [Department of Chemistry and Fire Retardant Research Facility, Marquette University, PO Box 1881, Milwaukee, WI 53201 (United States)

    2012-12-10

    Highlights: Black-Right-Pointing-Pointer We prepare PMMA and PS containing ceria. Black-Right-Pointing-Pointer Characterization by XRD and TEM shows that some of the ceria is well-dispersed in the polymers. Black-Right-Pointing-Pointer The addition of ceria to both polymers leads to reduced thermal stability. Black-Right-Pointing-Pointer In PMMA, the fire retardancy is enhanced but there is little effect in PS. - Abstract: In situ emulsion polymerization was employed to obtain poly (methyl methacrylate) (PMMA)/cerium(IV) dioxide and polystyrene (PS)/cerium(IV) dioxide nanocomposites at two different cerium(IV) dioxide loadings (2.3 wt% and 4.6 wt%). Transmission electron microscope results indicated uniform dispersion of cerium (IV) dioxide in the polymer matrix. Both PMMA and PS nanocomposites exhibit lower thermal stability than the pristine polymers. Microscale combustion calorimeter (MCC) and cone calorimetry are used to evaluate the fire retardancy of the polymer nanocomposites. PMMA/cerium(IV) dioxide showed significant heat release rate (HRR) reduction at low loadings (<5 wt%), while PS/cerium(IV) dioxide exhibits less HRR reduction at the same loadings. An explanation of the role of cerium (IV) dioxide in fire retardancy of polymer/ceria nanocomposites based on XPS results is suggested.

  6. Improvement in corrosion resistance of magnesium coating with cerium treatment

    Institute of Scientific and Technical Information of China (English)

    Samia Ben Hassen; Latifa Bousselmi; Patricc Bercot; El Mustafa Rezrazi; Ezzeddine Triki

    2009-01-01

    Corrosion protection afforded by a magnesium coating treated in cerium salt solution on steel substrate was investigated using open circuit potential, polarization curves, and electrochemical impedance spectroscopy (EIS) in 0.005 M sodium chloride solution (NaCl). The morphology of the surface was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The cerium treated coating was obtained by immersion in CeCl3 solution. The results showed that the corrosion resistance of the treated magnesium coating was improved. The corrosion potential of the treated coating was found to be nobler than that of the untreated magnesium coating and the corrosion current decreased significantly. Impedance results showed that the cerium treatment increased corrosion protection. The improvement of anti-corrosion properties was ataibuted to the formation of cerium oxides and hydroxides that gave to a physical barrier effect.

  7. Heteroaggregation of cerium oxide nanoparticles and nanoparticles of pyrolyzed biomass

    Science.gov (United States)

    Heteroaggregation with indigenous particles is an important process controlling the mobility of engineered nanomaterials in the environment. We studied heteroaggregation of cerium oxide nanoparticles (n-CeO2), which are widely used commercially, with nanoparticles of pyrogenic carbonaceous material ...

  8. Preparing Process of Cerium Acetate and Rare Earth Acetate

    Institute of Scientific and Technical Information of China (English)

    Qiao Jun; Ma Ying; Xu Yanhui; Zhang Jun; Chang Shu; Hao Xianku

    2004-01-01

    Preparing process was presented and the influences of concentration of acetic acid, reaction temperature, the ratio of cerium carbonate and acetic acid, heat preservation time to the yield of cerium acetate were discussed.The crystalline cerium acetate and rare earth acetate such as ( La, Ce, Pr, Nd) (Ac) 3, ( Ce, Pr, Nd) (Ac) 3, ( Pr, Nd, Er,Y) (Ac) 3 and yttrium acetate were prepared under this condition.The shape, structure and composition of the crystals were determined by the methods of SEM, TG-DTA, X-ray diffraction and chemical analysis.The optimum prepared conditions of cerium acetate were described.This prepared process has characteristics such as simple process route, low cost, high yield, good quality, no pollution to environment, etc.

  9. I-124 Imaging and Dosimetry

    Directory of Open Access Journals (Sweden)

    Russ Kuker

    2017-02-01

    Full Text Available Although radioactive iodine imaging and therapy are one of the earliest applications of theranostics, there still remain a number of unresolved clinical questions as to the optimization of diagnostic techniques and dosimetry protocols. I-124 as a positron emission tomography (PET radiotracer has the potential to improve the current clinical practice in the diagnosis and treatment of differentiated thyroid cancer. The higher sensitivity and spatial resolution of PET/computed tomography (CT compared to standard gamma scintigraphy can aid in the detection of recurrent or metastatic disease and provide more accurate measurements of metabolic tumor volumes. However the complex decay schema of I-124 poses challenges to quantitative PET imaging. More prospective studies are needed to define optimal dosimetry protocols and to improve patient-specific treatment planning strategies, taking into account not only the absorbed dose to tumors but also methods to avoid toxicity to normal organs. A historical perspective of I-124 imaging and dosimetry as well as future concepts are discussed.

  10. 47 CFR 69.124 - Interconnection charge.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Interconnection charge. 69.124 Section 69.124... Computation of Charges § 69.124 Interconnection charge. (a) Until December 31, 2001, local exchange carriers not subject to price cap regulation shall assess an interconnection charge expressed in dollars...

  11. 42 CFR 124.8 - Grantee accountability.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Grantee accountability. 124.8 Section 124.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES HEALTH RESOURCES DEVELOPMENT... and Modernization § 124.8 Grantee accountability. (a) Records requirements. (1) Applicants who...

  12. 19 CFR 12.4 - Exportation.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Exportation. 12.4 Section 12.4 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY SPECIAL CLASSES... Caustic Or Corrosive Substances § 12.4 Exportation. The exportation of merchandise, the subject of §...

  13. 36 CFR 13.124 - Emergency use.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Emergency use. 13.124 Section 13.124 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Cabins General Provisions § 13.124 Emergency use. During an...

  14. 21 CFR 163.124 - White chocolate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false White chocolate. 163.124 Section 163.124 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION CACAO PRODUCTS Requirements for Specific Standardized Cacao Products § 163.124 White chocolate. (a) Description. (1) White chocolate...

  15. 24 CFR 882.124 - Audit.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Audit. 882.124 Section 882.124...) SECTION 8 MODERATE REHABILITATION PROGRAMS Applicability, Scope and Basic Policies § 882.124 Audit. PHAs receiving financial assistance under this part are subject to audit requirements in 24 CFR part 44....

  16. 24 CFR 884.124 - Audit.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false Audit. 884.124 Section 884.124... HOUSING PROJECTS Applicability, Scope and Basic Policies § 884.124 Audit. (a) Where a State or local..., receiving financial assistance under this part, the audit requirements in 24 CFR part 44 shall apply....

  17. 18 CFR 401.124 - Construction.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Construction. 401.124 Section 401.124 Conservation of Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL RULES OF PRACTICE AND PROCEDURE General Provisions § 401.124 Construction. This part...

  18. Cerium intermetallics CeTX. Review III

    Energy Technology Data Exchange (ETDEWEB)

    Poettgen, Rainer; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ., Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux

    2016-05-01

    The structure-property relationships of CeTX intermetallics with structures other than the ZrNiAl and TiNiSi type are systematically reviewed. These CeTX phases form with electron-poor and electron-rich transition metals (T) and X = Mg, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb, and Bi. The review focusses on the crystal chemistry, the chemical bonding peculiarities, and the magnetic and transport properties. Furthermore {sup 119}Sn Moessbauer spectroscopic data, high-pressure studies, hydrogenation reactions and the formation of solid solutions are reviewed. This paper is the third of a series of four reviews on equiatomic intermetallic cerium compound [Part I: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 289; Part II: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 695].

  19. Exraction and separation of CERIUM(IV)/FLUORINE in fluoride-bearing cerium sulfate solution with fluoride coordination agent

    OpenAIRE

    Li, Y; J. G. He; X. X. Xue; Ru, H. Q.; X. W. Huang; Yang, H.

    2014-01-01

    In this paper the extraction and separation of cerium/fluorine in fluoride-bearing cerium sulfate solution with fluoride coordination agent has been studied. The UV-vis spectra suggest that Zr6+ and Al3+ can scrub the F- from [CeF2] 2+ complex. The separation and conductivity studies show that aluminum salt is the most suitable fluoride coordination agent, and an ion-exchange reaction is involved between Ce4+/ [CeF2] 2+ and hydrogen ion.

  20. Molecular and physiological responses to titanium dioxide and cerium oxide nanoparticles in arabidopsis

    Science.gov (United States)

    - Changes in tissue transcriptomes and productivity of Arabidopsis thaliana were investigated during exposure of plants to two widely-used engineered metal oxide nanoparticles, titanium dioxide (nano-titanium) and cerium dioxide (nano-cerium). Microarray analyses confirmed that e...

  1. Inhibition of pH fronts in corrosion cells due to the formation of cerium hydroxide

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The effect of cerium-based corrosion inhibitors on the pH front between the alkaline cathode and acidic anode in corrosion cells has been studied. The cerium component of these inhibitors can affect the pH front since it precipitates in an alkaline environment as cerium hydroxide, which is important

  2. Potential for recovery of cerium contained in automotive catalytic converters

    Science.gov (United States)

    Bleiwas, Donald I.

    2013-01-01

    Catalytic converters (CATCONs) are required by Federal law to be installed in nearly all gasoline- and diesel-fueled onroad vehicles used in the United States. About 85 percent of the light-duty vehicles and trucks manufactured worldwide are equipped with CATCONs. Portions of the CATCONs (called monoliths) are recycled for their platinum-group metal (PGM) content and for the value of the stainless steel they contain. The cerium contained in the monoliths, however, is disposed of along with the slag produced from the recycling process. Although there is some smelter capacity in the United States to treat the monoliths in order to recover the PGMs, a great percentage of monoliths is exported to Europe and South Africa for recycling, and a lesser amount is exported to Japan. There is presently no commercial-scale capacity in place domestically to recover cerium from the monoliths. Recycling of cerium or cerium compounds from the monoliths could help ensure against possible global supply shortages by increasing the amount that is available in the supply chain as well as the number and geographic distribution of the suppliers. It could also reduce the amount of material that goes into landfills. Also, the additional supply could lower the price of the commodity. This report analyzes how much cerium oxide is contained in CATCONs and how much could be recovered from used CATCONs.

  3. Electrodeposited cerium film as chromate replacement for tinplate

    Energy Technology Data Exchange (ETDEWEB)

    Huang Xingqiao [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Li Ning [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: lining@hit.edu.cn; Wang Huiyong; Sun Hanxiao; Sun Shanshan; Zheng Jian [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)

    2008-01-30

    The cerium film was prepared on tinplate by electrodeposition method. Sulfide-stain resistance of the Ce-passivated, unpassivated and Cr-passivated tinplates was evaluated using a cysteine tarnish test. Corrosion behavior of these tinplates in contact with 3.5% NaCl solution and 0.1 M citric-citrate buffer solution was investigated using Tafel measurement and electrochemical impedance spectroscopy measurement, respectively. The adhesion of epoxyphenolic lacquer to the Ce-passivated tinplate was checked using a cross hatch cutter. The morphology, composition and thickness of the cerium film were studied by atomic force microscopy, X-ray photoelectron spectroscopy and X-ray fluorescence spectrometry. According to the results, the Ce-passivated tinplate shows the best sulfide-stain resistance and the best corrosion protection property compared with the unpassivated and Cr-passivated tinplates. The adhesion of epoxyphenolic lacquer to the Ce-passivated tinplate is good. The cerium film is composed of the closely packed particles of about 50-200 nm in diameter. The film mainly consists of cerium and oxygen, which mainly exist as CeO{sub 2}, Ce{sub 2}O{sub 3} and their hydrates such as Ce(OH){sub 4}, Ce(OH){sub 3}. The total cerium amount of the film is about 0.110 g/m{sup 2}.

  4. Cerium, manganese and cerium/manganese ceramic monolithic catalysts. Study of VOCs and PM removal

    Institute of Scientific and Technical Information of China (English)

    COLMAN-LERNER Esteban; PELUSO Miguel Andrs; SAMBETH Jorge; THOMAS Horacio

    2016-01-01

    Ceramic supported cerium, manganese and cerium-manganese catalysts were prepared by direct impregnation of aqueous precursor, and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET), temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) acidity measurements and electrical conductivity. The catalytic activity was evaluated for volatile organic compounds (VOC) (ethanol, methyl ethyl ketone and toluene) oxidation. Additionally, catalysts were tested in particulate matter (PM) combustion. The characterization results indicated that Ce was in the form of Ce4+ and Ce3+, and Mn existed in the form of Mn4+and Mn3+on the surface of the Mn/AC sample and in the form of Mn4+ in the Ce/Mn/AC monolith. VOC oxidation results revealed that the Ce/Mn/AC sample showed an excellent performance compared with ceramic supported CeO2 (Ce/AC) and MnOx (Mn/AC) samples. The PM combustion was also higher on Ce/Mn/AC monoliths. The enhanced catalytic activity was mainly attributed to the Ce and Mn interaction which enhanced the acidity, conductiv-ity and the reducibility of the oxides.

  5. Environmental geochemistry of cerium: applications and toxicology of cerium oxide nanoparticles.

    Science.gov (United States)

    Dahle, Jessica T; Arai, Yuji

    2015-01-23

    Cerium is the most abundant of rare-earth metals found in the Earth's crust. Several Ce-carbonate, -phosphate, -silicate, and -(hydr)oxide minerals have been historically mined and processed for pharmaceutical uses and industrial applications. Of all Ce minerals, cerium dioxide has received much attention in the global nanotechnology market due to their useful applications for catalysts, fuel cells, and fuel additives. A recent mass flow modeling study predicted that a major source of CeO2 nanoparticles from industrial processing plants (e.g., electronics and optics manufactures) is likely to reach the terrestrial environment such as landfills and soils. The environmental fate of CeO2 nanoparticles is highly dependent on its physcochemical properties in low temperature geochemical environment. Though there are needs in improving the analytical method in detecting/quantifying CeO2 nanoparticles in different environmental media, it is clear that aquatic and terrestrial organisms have been exposed to CeO2 NPs, potentially yielding in negative impact on human and ecosystem health. Interestingly, there has been contradicting reports about the toxicological effects of CeO2 nanoparticles, acting as either an antioxidant or reactive oxygen species production-inducing agent). This poses a challenge in future regulations for the CeO2 nanoparticle application and the risk assessment in the environment.

  6. Environmental Geochemistry of Cerium: Applications and Toxicology of Cerium Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jessica T. Dahle

    2015-01-01

    Full Text Available Cerium is the most abundant of rare-earth metals found in the Earth’s crust. Several Ce-carbonate, -phosphate, -silicate, and -(hydroxide minerals have been historically mined and processed for pharmaceutical uses and industrial applications. Of all Ce minerals, cerium dioxide has received much attention in the global nanotechnology market due to their useful applications for catalysts, fuel cells, and fuel additives. A recent mass flow modeling study predicted that a major source of CeO2 nanoparticles from industrial processing plants (e.g., electronics and optics manufactures is likely to reach the terrestrial environment such as landfills and soils. The environmental fate of CeO2 nanoparticles is highly dependent on its physcochemical properties in low temperature geochemical environment. Though there are needs in improving the analytical method in detecting/quantifying CeO2 nanoparticles in different environmental media, it is clear that aquatic and terrestrial organisms have been exposed to CeO2 NPs, potentially yielding in negative impact on human and ecosystem health. Interestingly, there has been contradicting reports about the toxicological effects of CeO2 nanoparticles, acting as either an antioxidant or reactive oxygen species production-inducing agent. This poses a challenge in future regulations for the CeO2 nanoparticle application and the risk assessment in the environment.

  7. Cerium Dioxide Thin Films Using Spin Coating

    Directory of Open Access Journals (Sweden)

    D. Channei

    2013-01-01

    Full Text Available Cerium dioxide (CeO2 thin films with varying Ce concentrations (0.1 to 0.9 M, metal basis were deposited on soda-lime-silica glass substrates using spin coating. It was found that all films exhibited the cubic fluorite structure after annealing at 500°C for 5 h. The laser Raman microspectroscopy and GAXRD analyses revealed that increasing concentrations of Ce resulted in an increase in the degree of crystallinity. FIB and FESEM images confirmed the laser Raman and GAXRD analyses results owing to the predicted increase in film thickness with increasing Ce concentration. However, porosity and shrinkage (drying cracking of the films also increased significantly with increasing Ce concentrations. UV-VIS spectrophotometry data showed that the transmission of the films decreased with increasing Ce concentrations due to the increasing crack formation. Furthermore, a red shift was observed with increasing Ce concentrations, which resulted in a decrease in the optical indirect band gap.

  8. Mechanical and Thermophysical Properties of Cerium Monopnictides

    Science.gov (United States)

    Bhalla, Vyoma; Singh, Devraj; Jain, S. K.

    2016-03-01

    The ultrasonic attenuation due to phonon-phonon interaction, thermoelastic relaxation and dislocation damping mechanisms has been investigated in cerium monopnictides CeX (X: N, P, As, Sb and Bi) for longitudinal and shear waves along {third-order elastic constants of CeX have also been computed in the temperature range 0 K to 500 K using Coulomb and Born-Mayer potential upto second nearest neighbours. The computed values of these elastic constants have been applied to find out Young's moduli, bulk moduli, Breazeale's non-linearity parameters, Zener anisotropy, ultrasonic velocity, ultrasonic Grüneisen parameter, thermal relaxation time, acoustic coupling constants and ultrasonic attenuation. The fracture/toughness ratio is less than 1.75, which shows that the chosen materials are brittle in nature as found for other monopnictides. The drag coefficient acting on the motion of screw and edge dislocations due to shear and compressional phonon viscosities of the lattice have also been evaluated for both the longitudinal and shear waves. The thermoelastic loss and dislocation damping loss are negligible in comparison to loss due to Akhieser damping (phonon-phonon interaction). The obtained results for CeX are in qualitative agreement with other semi-metallic monopnictides.

  9. Cerium-iron-based magnetic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Chen; Pinkerton, Frederick E.; Herbst, Jan F.

    2017-01-17

    New magnetic materials containing cerium, iron, and small additions of a third element are disclosed. These materials comprise compounds Ce(Fe.sub.12-xM.sub.x) where x=1-4, having the ThMn.sub.12 tetragonal crystal structure (space group I4/mmm, #139). Compounds with M=B, Al, Si, P, S, Sc, Co, Ni, Zn, Ga, Ge, Zr, Nb, Hf, Ta, and W are identified theoretically, and one class of compounds based on M=Si has been synthesized. The Si cognates are characterized by large magnetic moments (4.pi.M.sub.s greater than 1.27 Tesla) and high Curie temperatures (264.ltoreq.T.sub.c.ltoreq.305.degree. C.). The Ce(Fe.sub.12-xM.sub.x) compound may contain one or more of Ti, V, Cr, and Mo in combination with an M element. Further enhancement in T.sub.c is obtained by nitriding the Ce compounds through heat treatment in N.sub.2 gas while retaining the ThMn.sub.12 tetragonal crystal structure; for example CeFe.sub.10Si.sub.2N.sub.1.29 has T.sub.c=426.degree. C.

  10. Thermodynamic Calculation among Cerium, Oxygen, and Sulfur in Liquid Iron

    Science.gov (United States)

    Pan, Fei; Zhang, Jian; Chen, Hao-Long; Su, Yen-Hsun; Su, Yen-Hao; Hwang, Weng-Sing

    2016-10-01

    Thermodynamic calculation has been applied to predict the inclusion formation in molten SS400 steel. When the Cerium addition in liquid iron is 70 ppm and the initial Oxygen and Sulphur are both 110 ppm, the formation of oxides containing Cerium would experience the transformation from Ce2O3 to CeO2 and also the formation of sulfides containing Cerium would experience the transformation from CeS to Ce2S3 and then to Ce3S4. Below 2000 K the most thermodynamic stable matter is CeO2 and the less thermodynamic stable inclusion is CeS. Only when the amount of [O] is extremely low and the amount of [S] and [Ce] is relatively high, Ce2S3 has the possibility to form.

  11. Elaboration and characterization of thin solid films containing cerium

    Science.gov (United States)

    Hamdi, S.; Guerfi, S.; Siab, R.

    2009-11-01

    Cerium oxide films are widely studied as a promising alternative to Cr(VI) based pre-treatments for the corrosion protection of different metals and alloys. Cathodic electrodeposition of Cerium containing thin films was realised on TA6V substrates from a Ce(NO3)3, 6H2O and mixed water-ethyl alcohol solutions at 0.01 M. Experimental conditions to obtain homogeneous and crack free thin films were determined. The deposited cerium quantity appears proportional to the quantity of electricity used, as indicated by the Faraday law. Subsequent thermal treatment lead to a CeO2 coating, expected to provide an increase of TA6V oxidation resistance at high temperatures. The deposits were characterized by differential scanning calorimetry (DSC), optical and scanning electron microscopies.

  12. Synthesis and characterization of magnesium doped cerium oxide for the fuel cell application

    Science.gov (United States)

    Kumar, Amit; Kumari, Monika; Kumar, Mintu; Kumar, Sacheen; Kumar, Dinesh

    2016-05-01

    Cerium oxide has attained much attentions in global nanotechnology market due to valuable application for catalytic, fuel additive, and widely as electrolyte in solid oxide fuel cell. Doped cerium oxide has large oxygen vacancies that allow for greater reactivity and faster ion transport. These properties make cerium oxide suitable material for SOFCs application. Cerium oxide electrolyte requires lower operation temperature which shows improvement in processing and the fabrication technique. In our work, we synthesized magnesium doped cerium oxide by the co-precipitation method. With the magnesium doping catalytic reactivity of CeO2 was increased. Synthesized nanoparticle were characterized by the XRD and UV absorption techniques.

  13. Optical and electrical studies of cerium mixed oxides

    Science.gov (United States)

    Sherly, T. R.; Raveendran, R.

    2014-10-01

    The fast development in nanotechnology makes enthusiastic interest in developing nanomaterials having tailor made properties. Cerium mixed oxide materials have received great attention due to their UV absorption property, high reactivity, stability at high temperature, good electrical property etc and these materials find wide applications in solid oxide fuel cells, solar control films, cosmetics, display units, gas sensors etc. In this study cerium mixed oxide compounds were prepared by co-precipitation method. All the samples were doped with Zn (II) and Fe (II). Preliminary characterizations such as XRD, SEM / EDS, TEM were done. UV - Vis, Diffuse reflectance, PL, FT-IR, Raman and ac conductivity studies of the samples were performed.

  14. The PL "violet shift" of cerium dioxide on silicon

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    CeO2 thin film was fabricated by dual ion beam epitaxial technique. The phenomenon of PL violet shift at room temperature was observed, and the distance of shift was about 65 nm. After the analysis of crystal structure and valence in the compound were carried out by XRD and XPS technique, it was concluded that the PL shift was related with valence of cerium ion in the oxides. When the valence of cerium ion varied from tetravalence to trivalence, the PL peak position would move from blue region to violet region and the phenomenon of "violet shift" was observed.

  15. Cerium dioxide with large particle size prepared by continuous precipitation

    Institute of Scientific and Technical Information of China (English)

    李梅; 王觅堂; 柳召刚; 胡艳宏; 吴锦绣

    2009-01-01

    Cerium dioxide(CeO2) has attracted much attention and has wide applications such as automotive exhaust catalysts,polishing materials for optical glasses and additives for advanced glasses,as well as cosmetic materials.The particle size and its distribution are key factors to the performance of the materials in the functional applications.However,control of particle size is still a challenge in materials synthesis.Therefore,continuous precipitation of cerium oxalate(precursor of ceria) was carried out at dif...

  16. Optical and electrical studies of cerium mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Sherly, T. R., E-mail: trsherly@gmail.com [Post Graduate Department of Physics, Sanathana Dharma College, Alappuzha, Kerala (India); Raveendran, R. [Nanoscience Research Laboratory, Sree Narayana College, Kollam, Kerala 691001 (India)

    2014-10-15

    The fast development in nanotechnology makes enthusiastic interest in developing nanomaterials having tailor made properties. Cerium mixed oxide materials have received great attention due to their UV absorption property, high reactivity, stability at high temperature, good electrical property etc and these materials find wide applications in solid oxide fuel cells, solar control films, cosmetics, display units, gas sensors etc. In this study cerium mixed oxide compounds were prepared by co-precipitation method. All the samples were doped with Zn (II) and Fe (II). Preliminary characterizations such as XRD, SEM / EDS, TEM were done. UV - Vis, Diffuse reflectance, PL, FT-IR, Raman and ac conductivity studies of the samples were performed.

  17. Isomorphic phase transformation in shocked Cerium using molecular dynamics

    OpenAIRE

    Germann T.C.; Chen S.-P.; Dupont V.

    2011-01-01

    Cerium (Ce) undergoes a significant (∼16%) volume collapse associated with an isomorphic fcc-fcc phase transformation when subject to compressive loading. We present here a new Embedded Atom Method (EAM) potential for Cerium that models two minima for the two fcc phases. We show results from its use in Molecular Dynamics (MD) simulations of Ce samples subjected to shocks with pressures ranging from 0.5 to 25 GPa. A split wave structure is observed, with an elastic precursor followed by a plas...

  18. 40 CFR 124.53 - State certification.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 21 2010-07-01 2010-07-01 false State certification. 124.53 Section... FOR DECISIONMAKING Specific Procedures Applicable to NPDES Permits § 124.53 State certification. (a) Under CWA section 401(a)(1), EPA may not issue a permit until a certification is granted or waived...

  19. 9 CFR 124.42 - Hearing procedure.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Hearing procedure. 124.42 Section 124.42 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE... shall have the right at all times to be advised and accompanied by an attorney. (c) Before the...

  20. 42 CFR 124.3 - Eligibility.

    Science.gov (United States)

    2010-10-01

    ... authority, or public or quasi-public corporation for a project described in paragraph (b) of this section... 42 Public Health 1 2010-10-01 2010-10-01 false Eligibility. 124.3 Section 124.3 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES HEALTH RESOURCES DEVELOPMENT...

  1. Exraction and separation of CERIUM(IV/FLUORINE in fluoride-bearing cerium sulfate solution with fluoride coordination agent

    Directory of Open Access Journals (Sweden)

    Y. Li

    2014-07-01

    Full Text Available In this paper the extraction and separation of cerium/fluorine in fluoride-bearing cerium sulfate solution with fluoride coordination agent has been studied. The UV-vis spectra suggest that Zr6+ and Al3+ can scrub the F- from [CeF2] 2+ complex. The separation and conductivity studies show that aluminum salt is the most suitable fluoride coordination agent, and an ion-exchange reaction is involved between Ce4+/ [CeF2] 2+ and hydrogen ion.

  2. Dicty_cDB: VSD124 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VS (Link to library) VSD124 (Link to dictyBase) - - - Contig-U03055-1 VSD124P (Link to Original site) VSD1...24F 530 VSD124Z 437 VSD124P 967 - - Show VSD124 Library VS (Link to library) Clone ID VSD1... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VS/VSD1-A/VSD124Q.Seq.d/ Representative seq. ID VSD1...24P (Link to Original site) Representative DNA sequence >VSD124 (VSD124Q) /CSM/VS/VSD1-A/VSD1...ing significant alignments: (bits) Value VSD124 (VSD124Q) /CSM/VS/VSD1-A/VSD124Q.

  3. Dicty_cDB: VHI124 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHI124 (Link to dictyBase) - - - Contig-U15897-1 VHI124P (Link to Original site) VHI...124F 546 VHI124Z 721 VHI124P 1247 - - Show VHI124 Library VH (Link to library) Clone ID VHI...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHI1-A/VHI124Q.Seq.d/ Representative seq. ID VHI...124P (Link to Original site) Representative DNA sequence >VHI124 (VHI124Q) /CSM/VH/VHI1-A/VHI...ficant alignments: (bits) Value VHI124 (VHI124Q) /CSM/VH/VHI1-A/VHI124Q.Seq.d/ 2337 0.0 VHH688 (VHH688Q) /CS

  4. Dicty_cDB: CHS124 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available CH (Link to library) CHS124 (Link to dictyBase) - - - Contig-U16439-1 CHS124P (Link to Original site) CHS1...24F 587 CHS124Z 771 CHS124P 1338 - - Show CHS124 Library CH (Link to library) Clone ID CHS1...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/CH/CHS1-A/CHS124Q.Seq.d/ Representative seq. ID CHS1...24P (Link to Original site) Representative DNA sequence >CHS124 (CHS124Q) /CSM/CH/CHS1-A/CHS1...nificant alignments: (bits) Value CHS124 (CHS124Q) /CSM/CH/CHS1-A/CHS124Q.Seq.d/ 2565 0.0 SHD220 (SHD220Q) /

  5. Processing and Characterization of Sol-Gel Cerium Oxide Microspheres

    Energy Technology Data Exchange (ETDEWEB)

    McClure, Zachary D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Padilla Cintron, Cristina [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-27

    Of interest to space exploration and power generation, Radioisotope Thermoelectric Generators (RTGs) can provide long-term power to remote electronic systems without the need for refueling or replacement. Plutonium-238 (Pu-238) remains one of the more promising materials for thermoelectric power generation due to its high power density, long half-life, and low gamma emissions. Traditional methods for processing Pu-238 include ball milling irregular precipitated powders before pressing and sintering into a dense pellet. The resulting submicron particulates of Pu-238 quickly accumulate and contaminate glove boxes. An alternative and dust-free method for Pu-238 processing is internal gelation via sol-gel techniques. Sol-gel methodology creates monodisperse and uniform microspheres that can be packed and pressed into a pellet. For this study cerium oxide microspheres were produced as a surrogate to Pu-238. The similar electronic orbitals between cerium and plutonium make cerium an ideal choice for non-radioactive work. Before the microspheres can be sintered and pressed they must be washed to remove the processing oil and any unreacted substituents. An investigation was performed on the washing step to find an appropriate wash solution that reduced waste and flammable risk. Cerium oxide microspheres were processed, washed, and characterized to determine the effectiveness of the new wash solution.

  6. Structural, optical and photocatalytic activity of cerium doped zinc aluminate

    Science.gov (United States)

    Sumathi, Shanmugam; Kavipriya, A.

    2017-03-01

    Zinc aluminate and cerium-doped zinc aluminate nanoparticles are synthesised by co-precipitation method. Ammonium hydroxide is used as a precipitating agent. The synthesised compounds are characterised by powder X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Surface area measurements. The photocatalytic activity of zinc aluminate and cerium doped zinc aluminate nanoparticles are studied under the UV light and visible light taking methylene blue as a model pollutant. The amount of catalyst, concentration of dye solution and time are optimised under UV-light. Degradation of methylene blue under the UV-light is found to be 99% in 20 min with 10 mg of cerium doped catalyst. Compared to visible light degradation, the degradation of dye under UV-light is higher. Cerium doping in zinc aluminate (ZnAl2O4:Ce3+) increased the photocatalytic activity of zinc aluminate.

  7. Purification of cerium, neodymium and gadolinium for low background experiments

    Directory of Open Access Journals (Sweden)

    Boiko R.S.

    2014-01-01

    Full Text Available Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search, 136Ce (2β+ candidate with one of the highest Q2β. The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

  8. Electrorheological Effects of Cerium-Doped TiO2

    Institute of Scientific and Technical Information of China (English)

    尹剑波; 赵晓鹏

    2001-01-01

    It is found that the doping of cerium ion into anatase TiO2 can improve the electrorheological (ER) effects of TiO2 and broaden the operational temperature range. Especially, the substitution of 7-11 mol% of the cerium dopant for Ti can obtain a relatively high shear stress, t-7.4kPa (at 4kV/mm), which is ten times larger than that of pure TiO2 ER fluid. Also, the typical Ce-doped TiO2 ER fluid shows the highest shear stress at 80℃, but 40℃ for pure TiO2 ER fluid. The dielectric loss and dielectric constant at a low frequency of TiO2 is improved by the doping of cerium, and the temperature dependence of the dielectric properties shows an obvious differnce between pure and doped TiO2 ER fluids. These can well explain the ER behaviour of doped TiO2. Furthermore, the change of rheological and dielectric properties is discussed on the basis of the lattice distortion and defects in TiO2 arising from the doping of cerium.

  9. Cerium; crystal structure and position in the periodic table.

    Science.gov (United States)

    Johansson, Börje; Luo, Wei; Li, Sa; Ahuja, Rajeev

    2014-09-17

    The properties of the cerium metal have intrigued physicists and chemists for many decades. In particular a lot of attention has been directed towards its high pressure behavior, where an isostructural volume collapse (γ phase → α phase) has been observed. Two main models of the electronic aspect of this transformation have been proposed; one where the 4f electron undergoes a change from being localized into an itinerant metallic state, and one where the focus is on the interaction between the 4f electron and the conduction electrons, often referred to as the Kondo volume collapse model. However, over the years it has been repeatedly questioned whether the cerium collapse really is isostructural. Most recently, detailed experiments have been able to remove this worrisome uncertainty. Therefore the isostructural aspect of the α-γ transition has now to be seriously addressed in the theoretical modeling, something which has been very much neglected. A study of this fundamental characteristic of the cerium volume collapse is made in present paper and we show that the localized [rlhar2 ] delocalized 4f electron picture provides an adequate description of this unique behavior. This agreement makes it possible to suggest that an appropriate crossroad position for cerium in The Periodic Table.

  10. Determination of Impurity Elements in Pure Cerium Oxide Product

    Institute of Scientific and Technical Information of China (English)

    Li Peizhong; Chen Limin; Li Jie

    2004-01-01

    Determination of the rare earth impurity in pure cerium oxide is done by ICP-MS.The interference and other factors which affect analytical results were discussed.The accuracy are between 0.81% ~ 11.98% and the recoveries of standard addition are 96% ~ 112.5%.This method can meet the demand for product inspection.

  11. Preparation, Characterization and Antibacterial Property of Cerium Substituted Hydroxyapatite Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Lin Yingguang; Yang Zhuoru; Cheng Jiang

    2007-01-01

    Nanoparticles of hydroxyapatite (HAP) and cerium substituted hydroxyapatite (CeHAP) with the atomic ratio of Ce/[Ca+Ce] (xCe) from 0 to 0.2 were prepared by sol-gel-supercritical fluid drying (SCFD) method. The nanoparticles were characterized by TEM, XRD, and FT-IR, and the effects of cerium on crystal structure, crystallinity, and particle shape were discussed. With the tests of bacterial inhibition zone and antibacterial ratio, the antibacterial property of HAP and CeHAP nanoparticles on Escherichia coli, Staphylococcus aureus, Lactobacillus were researched. Results showed that the nanoparticles of HAP and CeHAP could be made by sol-gel-SCFD, cerium could partially substitute for calcium and enter the structure of HAP. After substitution, the crystallinity, the IR wavenumbers of bonds in CeHAP decreased gradually with increase of cerium substitution, and the morphology of the nanoparticles changed from the short rod-shaped HAP to the needle-shaped CeHAP. The nanoparticles of HAP and CeHAP with xCe below 0.08 had antibacterial property only forcibly contacting with the test bacteria at the test concentration of 0.1 g·ml-1, however, the CeHAP nanoparticles had antibacterial ability at that concentration no matter statically or dynamically contacting with the test bacteria when xCe was above 0.08, and the antibacterial ability gets better with the increase of xCe, indicating that the antibacterial property was improved after calcium was partially substituted by cerium. The improved antibacterial effects of CeHAP nanoparticle on Lactobacillus showed its potential ability to anticaries.

  12. Dicty_cDB: SSF124 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available SS (Link to library) SSF124 (Link to dictyBase) - - - Contig-U14703-1 SSF124Z (Link... to Original site) - - SSF124Z 517 - - - - Show SSF124 Library SS (Link to library) Clone ID SSF124 (Link to...ycdb.biol.tsukuba.ac.jp/CSM/SS/SSF1-A/SSF124Q.Seq.d/ Representative seq. ID SSF12...4Z (Link to Original site) Representative DNA sequence >SSF124 (SSF124Q) /CSM/SS/SSF1-A/SSF124Q.Seq.d/ XXXXX...ces producing significant alignments: (bits) Value SSF124 (SSF124Q) /CSM/SS/SSF1-A/SSF1

  13. Solubility of cerium in LaCoO3-influence on catalytic activity.

    Science.gov (United States)

    French, S A; Catlow, C R A; Oldman, R J; Rogers, S C; Axon, S A

    2002-11-21

    The recent interest in the catalytic properties of lanthanum perovskites for methane combustion and three way catalysis has led to considerable debate as to their structure and defect chemistry. We have investigated the doping of LaCoO3 with the tetravalent cerium cation using atomistic simulation techniques. We have compared three routes for cerium insertion and identified the favoured doping mechanism, which explain experimental observations relating to the effect of cerium on catalytic activity.

  14. Study of cerium diffusion in undoped lithium-6 enriched glass with Rutherford backscattering spectrometry

    Science.gov (United States)

    Zhang, Xiaodong; Moore, Michael E.; Lee, Kyung-Min; Lukosi, Eric D.; Hayward, Jason P.

    2016-07-01

    Undoped lithium-6 enriched glasses coated with pure cerium (99.9%) with a gold protection layer on top were heated at three different temperatures (500, 550, and 600 °C) for varied durations (1, 2, and 4 h). Diffusion profiles of cerium in such glasses were obtained with the conventional Rutherford backscattering technique. Through fitting the diffusion profiles with the thin-film solution of Fick's second law, diffusion coefficients of cerium with different annealing temperatures and durations were solved. Then, the activation energy of cerium for the diffusion process in the studied glasses was found to be 114 kJ/mol with the Arrhenius equation.

  15. Improvement of cerium of photosynthesis functions of maize under magnesium deficiency.

    Science.gov (United States)

    Zhou, Min; Gong, Xiaolan; Wang, Ying; Liu, Chao; Hong, Mengmeng; Wang, Ling; Hong, Fashui

    2011-09-01

    Rare earth elements can promote photosynthesis, but their mechanisms are still poorly understood under magnesium deficiency. The present study was designed to determine the role of cerium in magnesium-deficient maize plants. Maize was cultivated in Hoagland's solution added with cerium with and without adequate quantities of magnesium. Under magnesium-deficient conditions, cerium can prevents inhibition of synthesis of photosynthetic pigment, improves light energy absorption and conversion, oxygen evolution, and the activity of photo-phosphorelation and its coupling factor Ca(2+)-ATPase. These results suggest that cerium could partly substitute magnesium, improving photosynthesis and plant growth.

  16. The effect of cerium valence states at cerium oxide nanoparticle surfaces on cell proliferation

    KAUST Repository

    Naganuma, Tamaki

    2014-05-01

    Understanding and controlling cell proliferation on biomaterial surfaces is critical for scaffold/artificial-niche design in tissue engineering. The mechanism by which underlying integrin ligates with functionalized biomaterials to induce cell proliferation is still not completely understood. In this study, poly-l-lactide (PL) scaffold surfaces were functionalized using layers of cerium oxide nanoparticles (CNPs), which have recently attracted attention for use in therapeutic application due to their catalytic ability of Ce4+ and Ce3+ sites. To isolate the influence of Ce valance states of CNPs on cell proliferation, human mesenchymal stem cells (hMSCs) and osteoblast-like cells (MG63) were cultured on the PL/CNP surfaces with dominant Ce4+ and Ce3+ regions. Despite cell type (hMSCs and MG63 cells), different surface features of Ce4+ and Ce3+ regions clearly promoted and inhibited cell spreading, migration and adhesion behavior, resulting in rapid and slow cell proliferation, respectively. Cell proliferation results of various modified CNPs with different surface charge and hydrophobicity/hydrophilicity, indicate that Ce valence states closely correlated with the specific cell morphologies and cell-material interactions that trigger cell proliferation. This finding suggests that the cell-material interactions, which influence cell proliferation, may be controlled by introduction of metal elements with different valence states onto the biomaterial surface. © 2014 Elsevier Ltd.

  17. Isomorphic phase transformation in shocked cerium using molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Dupont, Virginie [Los Alamos National Laboratory; Germann, Timothy C [Los Alamos National Laboratory; Chen, Shao - Ping [Los Alamos National Laboratory

    2010-08-12

    Cerium (Ce) undergoes a significant ({approx}16%) volume collapse associated with an isomorphic fcc-fcc phase transformation when subject to compressive loading. We present here a new Embedded Atom Method (EAM) potential for Cerium that models two minima for the two fcc phases. We show results from its use in Molecular Dynamics (MD) simulations of Ce samples subjected to shocks with pressures ranging from 0.5 to 25 GPa. A split wave structure is observed, with an elastic precursor followed by a plastic wave. The plastic wave causes the expected fcc-fcc phase transformation. Comparisons to experiments and MD simulations on Cesium (Cs) indicate that three waves could be observed. The construction of the EAM potential may be the source of the difference.

  18. Isomorphic phase transformation in shocked Cerium using molecular dynamics

    Directory of Open Access Journals (Sweden)

    Germann T.C.

    2011-01-01

    Full Text Available Cerium (Ce undergoes a significant (∼16% volume collapse associated with an isomorphic fcc-fcc phase transformation when subject to compressive loading. We present here a new Embedded Atom Method (EAM potential for Cerium that models two minima for the two fcc phases. We show results from its use in Molecular Dynamics (MD simulations of Ce samples subjected to shocks with pressures ranging from 0.5 to 25 GPa. A split wave structure is observed, with an elastic precursor followed by a plastic wave. The plastic wave causes the expected fcc-fcc phase transformation. Comparisons to experiments and MD simulations on Cesium (Cs indicate that three waves could be observed. The construction of the EAM potential may be the source of the difference.

  19. Adsorption of Fluoride Ion by Inorganic Cerium Based Adsorbent

    Institute of Scientific and Technical Information of China (English)

    Jiao Zhongzhi(焦中志); Chen Zhonglin; Yang Min; Zhang Yu; Li Guibai

    2004-01-01

    Excess of fluoride in drinking water is harmful to human health, the concentration of F- ions must be maintained in the range of 0.5 to 1.5 mg/L. An inorganic cerium based adsorbent (CTA) is developed on the basis of research of adsorption of fluoride on cerium oxide hydrate. Some adsorption of fluoride by CTA adsorbent experiments were carried out, and results showed that CTA adsorbent has a quick adsorption speed and a large adsorption capacity. Adsorption follows Freundlich isotherm, and low pH value helps fluoride removal. Some physical-chemical characteristics of CTA adsorbent were experimented, fluoride removal mechanism was explored, and results showed that hydroxyl group of CTA adsorbent played an important role in the fluoride removal.

  20. Synthesis and characterization of cerium sulfide thin film

    Institute of Scientific and Technical Information of China (English)

    Ιshak Afsin Kariper

    2014-01-01

    Cerium sulfide (CexSy) polycrystalline thin film is coated with chemical bath deposition on substrates (commercial glass). Transmittance, absorption, optical band gap and refractive index are examined by using UV/VIS. Spectrum. The hexagonal form is observed in the structural properties in XRD. The structural and optical properties of cerium sulfide thin films are analyzed at different pH. SEM and EDX analyses are made for surface analysis and elemental ratio in films. It is observed that some properties of films changed with different pH values. In this study, the focus is on the observed changes in the properties of films. The pH values were scanned at 6–10. The optical band gap changed with pH between 3.40 to 3.60 eV. In addition, the film thickness changed with pH at 411 nm to 880 nm.

  1. Preparation and characterization of gelatin/cerium(Ⅲ) film

    Institute of Scientific and Technical Information of China (English)

    黄崇军; 黄雅钦; 田娜; 童元建; 殷瑞贤

    2010-01-01

    A novel gelatin film with antibacterial activity was prepared by electrostatic crosslinking using cerium (Ⅲ) nitrate hexahydrate as the crosslinking agent. The structure and properties of the films were investigated by Fourier transform infrared spectra, tensile tests, thermogravimetric analysis, static drop contact angle and disc diffusion method. The results showed that cross-linking could not only improve the thermal and mechanical properties and lower the hydrophilic property of the films, but also make...

  2. Antibacterial activity of polymer coated cerium oxide nanoparticles.

    Directory of Open Access Journals (Sweden)

    Vishal Shah

    Full Text Available Cerium oxide nanoparticles have found numerous applications in the biomedical industry due to their strong antioxidant properties. In the current study, we report the influence of nine different physical and chemical parameters: pH, aeration and, concentrations of MgSO(4, CaCl(2, KCl, natural organic matter, fructose, nanoparticles and Escherichia coli, on the antibacterial activity of dextran coated cerium oxide nanoparticles. A least-squares quadratic regression model was developed to understand the collective influence of the tested parameters on the anti-bacterial activity and subsequently a computer-based, interactive visualization tool was developed. The visualization allows us to elucidate the effect of each of the parameters in combination with other parameters, on the antibacterial activity of nanoparticles. The results indicate that the toxicity of CeO(2 NPs depend on the physical and chemical environment; and in a majority of the possible combinations of the nine parameters, non-lethal to the bacteria. In fact, the cerium oxide nanoparticles can decrease the anti-bacterial activity exerted by magnesium and potassium salts.

  3. Study of tetravalent cerium incorporation in the monazite structure

    Energy Technology Data Exchange (ETDEWEB)

    Bregiroux, D.; Audubert, F.; Bernache-Assollant, D

    2004-07-01

    The incorporation of tetravalent cerium in the monazite structure (La{sub 1-2x}Ce{sup 4+}{sub x}Ca{sub x}PO{sub 4}) by high temperature solid state synthesis was investigated. First of all, the reaction was followed by DTA-TGA method and X-rays diffraction. It has been shown that CaO first reacts with the phosphate precursor to form Ca(PO{sub 3}){sub 2}. This compound melts near 940 deg C, inducing the dissociation of CeO{sub 2} and the reduction of a large part of cerium IV to cerium III. Two methods have been developed to determine the Ce{sup 4+}/Ce{sup 3+} ratio by using X-ray diffraction and microprobe analysis. We show that Ce{sup 4+} incorporation in LaPO{sub 4} is limited to a Ce{sup 4+}/Ce{sup 3+} = 0.15 value. (authors)

  4. Jet formation in cerium metal to examine material strength

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, B. J., E-mail: bjjensen@lanl.gov; Cherne, F. J.; Prime, M. B.; Yeager, J. D.; Ramos, K. J.; Hooks, D. E.; Cooley, J. C.; Dimonte, G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Fezzaa, K. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Iverson, A. J.; Carlson, C. A. [National Security Technologies LLC, Los Alamos, New Mexico 87544 (United States)

    2015-11-21

    Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solid phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2–3 μm spatial resolution. From these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. The data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions.

  5. Jet formation in cerium metal to examine material strength

    Science.gov (United States)

    Jensen, B. J.; Cherne, F. J.; Prime, M. B.; Fezzaa, K.; Iverson, A. J.; Carlson, C. A.; Yeager, J. D.; Ramos, K. J.; Hooks, D. E.; Cooley, J. C.; Dimonte, G.

    2015-11-01

    Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solid phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2-3 μm spatial resolution. From these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. The data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions.

  6. pH-distribution of cerium species in aqueous systems

    Institute of Scientific and Technical Information of China (English)

    B.Bouchaud; J.Balmain; G.Bonnet; F.Pedraza

    2012-01-01

    Cerium-based oxide coalings can be obtained through either chemical or electrochemical processes on various conductor and semiconductor substrates.In both cases the films develop through a precipitation mechanism,which strongly depends on the solution chemistry.In the particular case of the electrolytic approach,the elaboration parameters play a key role on the interfacial pH modification thereby leading to an indirect precipitation mechanism.Indeed,the nucleation and growth mechanisms of crystallites and the composition of the resulting layers have been shown to be also strongly affected by the deposition conditions as well as by the substrate composition,which could in turn modify the protectiveness provided by such coatings.Therefore a better fundamental understanding of the system is required,in particular of the distribution of cerium-containing species in aqueous solution.To this end,the present work intended to develop a diagram showing the distribution as well as the relative amount of Ce(Ⅲ)/Ce(Ⅳ) species in aqueous media as a function of the pH range.The resulting pH-distribution diagram turned out to be a useful tool to predict the relevant precipitation mechanisms and species involved during the growth of cerium-containing films and to draw correlations with the characteristics of the as-deposited films.

  7. 49 CFR 571.124 - Standard No. 124; Accelerator control systems.

    Science.gov (United States)

    2010-10-01

    ... Federal Motor Vehicle Safety Standards § 571.124 Standard No. 124; Accelerator control systems. S1. Scope.... S3. Application. This standard applies to passenger cars, multi-purpose passenger vehicles, trucks, and buses. S4. Definitions. S4.1Driver-operated accelerator control system means all...

  8. LUMINESCENT PROPERTIES OF SILICATE GLASSES WITH CERIUM IONS AND ANTIMONY

    Directory of Open Access Journals (Sweden)

    A. M. Klykova

    2014-05-01

    Full Text Available The paper deals with the results of an experimental study of luminescence excitation spectra and luminescence of silicate glasses containing cerium ions and antimony. The aim of this work was to study the features of the luminescence and the effect of UV irradiation and heat treatment on luminescence and the state of cerium ions and antimony in glass. We investigated glass system Na2O-ZnO-Al2O3-SiO2-NaF-NaBr with additives CeO2 and Sb2O3. Synthesis was carried out in platinum crucibles in the air at 14500C. The samples were polished glass plates with a thickness of 0.5-1 mm. UV irradiation was carried out with a mercury lamp having a wide range of radiation in the spectral range 240-390 nm. It was conducted in a Nabertherm muffle furnaces. Luminescence spectra and excitation spectra were measured using a spectrofluorimeter MPF-44A (PerkinElmer at the room temperature. Measured luminescence spectra were corrected in view of the spectral sensitivity of the photodetector for spectrofluorimeter. Adjustment of the excitation spectra for the spectral dependence of the intensity of the excitation source was not carried out. During the experiments it was found that in silicate glasses Sb3+ ions can exist in two energy states, which corresponds to a different environment with oxygen ions. Heat treatment of these glasses in an oxidizing atmosphere leads to an increase in ion concentration of Sb3+ ions with a greater amount of oxygen in the environment. In glasses containing antimony and cerium ions, ultraviolet irradiation causes a change in the valence of cerium ions and antimony, which is accompanied by luminescence quenching. Subsequent heat treatment of glass leads to the inverse processes and restore luminescence excitation spectra. The study of fluorescent properties of silicate glasses with cerium and antimony ions led to the conclusion of the practical significance of this work. Promising multifunctional materials can be created on the basis of

  9. Induction of pulmonary fibrosis by cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jane Y., E-mail: jym1@cdc.gov [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Mercer, Robert R.; Barger, Mark; Schwegler-Berry, Diane; Scabilloni, James [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Ma, Joseph K. [School of Pharmacy, West Virginia University, Morgantown, WV 26506 (United States); Castranova, Vincent [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States)

    2012-08-01

    Cerium compounds have been used as a diesel engine catalyst to lower the mass of diesel exhaust particles, but are emitted as cerium oxide (CeO{sub 2}) nanoparticles in the diesel exhaust. In a previous study, we have demonstrated a wide range of CeO{sub 2}-induced lung responses including sustained pulmonary inflammation and cellular signaling that could lead to pulmonary fibrosis. In this study, we investigated the fibrogenic responses induced by CeO{sub 2} in a rat model at various time points up to 84 days post-exposure. Male Sprague Dawley rats were exposed to CeO{sub 2} by a single intratracheal instillation. Alveolar macrophages (AM) were isolated by bronchial alveolar lavage (BAL). AM-mediated cellular responses, osteopontin (OPN) and transform growth factor (TGF)-β1 in the fibrotic process were investigated. The results showed that CeO{sub 2} exposure significantly increased fibrotic cytokine TGF-β1 and OPN production by AM above controls. The collagen degradation enzymes, matrix metalloproteinase (MMP)-2 and -9 and the tissue inhibitor of MMP were markedly increased in the BAL fluid at 1 day- and subsequently declined at 28 days after exposure, but remained much higher than the controls. CeO{sub 2} induced elevated phospholipids in BAL fluid and increased hydroxyproline content in lung tissue in a dose- and time-dependent manner. Immunohistochemical analysis showed MMP-2, MMP-9 and MMP-10 expressions in fibrotic regions. Morphological analysis noted increased collagen fibers in the lungs exposed to a single dose of 3.5 mg/kg CeO{sub 2} and euthanized at 28 days post-exposure. Collectively, our studies show that CeO{sub 2} induced fibrotic lung injury in rats, suggesting it may cause potential health effects. -- Highlights: ► Cerium oxide exposure significantly affected the following parameters in the lung. ► Induced fibrotic cytokine OPN and TGF-β1 production and phospholipidosis. ► Caused imbalance of the MMP-9/ TIMP-1 ratio that favors fibrosis

  10. Single crystal to single crystal transformation and hydrogen-atom transfer upon oxidation of a cerium coordination compound.

    Science.gov (United States)

    Williams, Ursula J; Mahoney, Brian D; Lewis, Andrew J; DeGregorio, Patrick T; Carroll, Patrick J; Schelter, Eric J

    2013-04-15

    Trivalent and tetravalent cerium compounds of the octamethyltetraazaannulene (H2omtaa) ligand have been synthesized. Electrochemical analysis shows a strong thermodynamic preference for the formal cerium(IV) oxidation state. Oxidation of the cerium(III) congener Ce(Homtaa)(omtaa) occurs by hydrogen-atom transfer that includes a single crystal to single crystal transformation upon exposure to an ambient atmosphere.

  11. High spin properties of 124Ba

    Indian Academy of Sciences (India)

    K Ilangovan; N Arunachalam

    2002-03-01

    The 124Ba nucleus is investigated on the basis of the method of statistical mechanics by assuming the nucleons to move in triaxially deformed Nilsson potential. The variation in the Fermi energies of protons and neutrons is studied as a function of spin and temperature. The Fermi energies determined as a function of angular momentum is used to study the dependence of shell correction on angular momentum using the Strutinsky smoothing procedure. The most important observation is that the shell correction is almost the same for all spins for 124Ba. The spin cutoff parameter and the single particle level density parameter are studied as a function of spin and temperature. Constant entropy lines drawn by plotting the excitation energy against angular momentum are found to be roughly at constant energy above the yrast line and are almost equally spaced. It is observed that no yrast traps are present for 124Ba.

  12. Cerium doped red mud catalytic ozonation for bezafibrate degradation in wastewater: Efficiency, intermediates, and toxicity.

    Science.gov (United States)

    Xu, Bingbing; Qi, Fei; Sun, Dezhi; Chen, Zhonglin; Robert, Didier

    2016-03-01

    In this study, the performance of bezafibrate (BZF) degradation and detoxification in the aqueous phase using cerium-modified red mud (RM) catalysts prepared using different cerium sources and synthesis methods were evaluated. Experimental results showed that the surface cerium modification was responsible for the development of the catalytic activity of RM and this was influenced by the cerium source and the synthesis method. Catalyst prepared from cerium (IV) by precipitation was found to show the best catalytic activity in BZF degradation and detoxification. Reactive oxygen species including peroxides, hydroxyl radicals, and super oxide ions were identified in all reactions and we proposed the corresponding catalytic reaction mechanism for each catalyst that prepared from different cerium source and method. This was supported by the intermediates profiles that were generated upon BZF degradation. The surface and the structural properties of cerium-modified RM were characterized in detail by several analytical methods. Two interesting findings were made: (1) the surface texture (specific surface area and mesoporous volume) influenced the catalytic reaction pathway; and (2) Ce(III) species and oxygen vacancies were generated on the surface of the catalyst after cerium modification. This plays an important role in the development of the catalytic activity.

  13. Tuning Reactivity and Electronic Properties through Ligand Reorganization within a Cerium Heterobimetallic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Jerome R.; Gordon, Zachary; Booth, Corwin H.; Carroll, Patrick J.; Walsh, Patrick J.; Schelter, Eric J.

    2014-06-24

    Cerium compounds have played vital roles in organic, inorganic, and materials chemistry due to their reversible redox chemistry between trivalent and tetravalent oxidation states. However, attempts to rationally access molecular cerium complexes in both oxidation states have been frustrated by unpredictable reactivity in cerium(III) oxidation chemistry. Such oxidation reactions are limited by steric saturation at the metal ion, which can result in high energy activation barriers for electron transfer. An alternative approach has been realized using a rare earth/alkali metal/1,1'-BINOLate (REMB) heterobimetallic framework, which uses redox-inactive metals within the secondary coordination sphere to control ligand reorganization. The rational syntheses of functionalized cerium(IV) products and a mechanistic examination of the role of ligand reorganization in cerium(III) oxidation are presented.

  14. 7 CFR 1221.124 - Reports.

    Science.gov (United States)

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Reports, Books, and Records § 1221.124... price multiplied by the number of bushels or tons within the State that were marketed to the...

  15. 9 CFR 124.2 - Definitions.

    Science.gov (United States)

    2010-01-01

    ... Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES... Agriculture responsible for licensing veterinary biological products under the Virus-Serum-Toxin Act... under § 124.30 of this part. Informal hearing. A hearing that is not subject to the provisions of 5...

  16. Spectrophotometric determination of cerium with methylthymol blue in the presence of oxalate and cyanide as masking agents

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera-Martin, A.; Izquierdo-Hornillos, R.; Quejido-Cabezas, A.J.; Peral-Fernandez, J.L. (Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas)

    1983-04-01

    The spectrophotometric determination of cerium can be carried out by several methods, which involve either the formation of complexes of cerium(III) and cerium(IV) or the oxidation of suitable reagents by cerium(IV) and further measuring the intensity of the colour of the oxidised matter. The latter methods show a lack of selectivity and low sensitivity owing to the nature of the redox reaction. The methods that involve the formation of complexes have also been shown to have low selectivity and sensitivity. However, the most useful methods are those based on the complexes of cerium(III) with Xylenol Orange and Methylthymol Blue (MTB), but they are affected by many interferences. In this work the reaction of cerium(III) with MTB in the presence of oxalate and cyanide ions was studied at pH 10.2, which improves the sensitivity and the selectivity of the determination of cerium.

  17. Electrochemical studies on cerium(Ⅲ) in molten fluoride mixtures

    Institute of Scientific and Technical Information of China (English)

    VIRGIL; CONSTANTIN; ANA-MARIA; POPESCU; MIRCEA; OLTEANU

    2010-01-01

    This study aims to determine the principal electrochemical characteristics of the electrodeposition of cerium metal from molten fluoride systems.The cathodic process of Ce3+ ions in LiF-NaF and LiF-NaF-CaF2 molten salts was studied using electrochemical techniques as steady state and cyclic voltammetry methods.The decomposition potential(Ed) and the overvoltage(η) were determined for NaCeF4 using current-potential curves under galvanostatic conditions.The Ed was found to be 2.025 V in LiF-NaF and 2.045 V in...

  18. Cerium oxide based nanometric powders: synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Ninić M.

    2007-01-01

    Full Text Available Nanometric powders of solid solutions of cerium oxide were obtained by a modified glycine nitrate procedure. Solid solutions of the host compound CeO2 with one or more dopants in the lattice were synthesized. Rare earth cations (Re=Yb, Gd and Sm were added to ceria in total concentration of x= 0.2 that was kept constant. The criterion in doping was to keep the value of lattice parameter of ceria unchanged. The lattice parameters were calculated by using the model that takes into account the existence of oxygen vacancies in the structure.

  19. Options for the recovery of cerium by solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Soldenhoff, K.H. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1996-12-31

    This paper reports the results of an experimental program to examine the use of various commercial reagents for the extraction of cerium (IV) from sulphate solutions. Extractants tested include organophosphorus esters (TOPO, Cyanex 923 and Cyanex 925), organophosphorus acids (DEHPA, lonquest 801 and Cyanex 272) and high molecular weight amine, Alamine 336. The suitability of reagents is assessed in terms of process relevant criteria such as extraction dependence on acidity, selectivity over other rare earths and thorium, stability of reagent towards oxidation and loading characteristics. (author) 15 refs., 2 tabs., 5 figs.

  20. Identification of the Charge Carriers in Cerium Phosphate Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Hannah L.; Jonghe, Lutgard C. De

    2010-06-02

    The total conductivity of Sr-doped cerium orthophosphate changes by nearly two orders of magnitude depending on the oxygen and hydrogen content of the atmosphere. The defect model for the system suggests that this is because the identity of the dominant charge carrier can change from electron holes to protons when the sample is in equilibrium with air vs. humidified hydrogen. In this work are presented some preliminary measurements that can help to clarify this exchange between carriers. The conduction behavior of a 2percent Sr-doped CePO4 sample under symmetric atmospheric conditions is investigated using several techniques, including AC impedance, H/D isotope effects, and chronoamperometry.

  1. Properties of hot liquid cerium by LDA + U molecular dynamics.

    Science.gov (United States)

    Siberchicot, Bruno; Clérouin, Jean

    2012-11-14

    We present ab initio simulations of liquid cerium in the framework of the LDA + U formulation. The liquid density has been determined self-consistently by searching for the zero pressure equilibrium state at 1320 K with the same set of parameters (U and J) and occupation matrices as those optimized for the γ phase. We have computed static and transport properties. The liquid produced by the simulations appears more structured than the available measurements. This raises questions regarding the ability of the theory to describe such a complex liquid. Conductivity calculations and temperature dependences are nevertheless in reasonable agreement with data.

  2. Hydrothermal synthesis of cerium titanate nanorods and its application in visible light photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Pei, L.Z., E-mail: lzpei@ahut.edu.cn; Liu, H.D.; Lin, N.; Yu, H.Y., E-mail: yuhy@ahut.edu.cn

    2015-01-15

    Highlights: • Cerium titanate nanorods have been synthesized by a simple hydrothermal process. • The size of the cerium titanate nanorods can be controlled by growth conditions. • Cerium titanate nanorods exhibit good photocatalytic activities for methyl blue. - Abstract: Cerium titanate nanorods have been prepared via a hydrothermal process using sodium dodecyl sulfate (SDS) as the surfactant. The cerium titanate nanorods have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and ultraviolet–visible (UV–vis) diffuse reflectance spectrum. XRD shows that the nanorods are composed of CeTi{sub 21}O{sub 38} phase. Electron microscopy observations indicate that the nanorods have good single crystalline nature. The diameter and length of the nanorods are about 50–200 nm and 1–2 μm, respectively. Cerium titanate nanorods have a band gap of 2.65 eV. The photocatalytic activities of the nanorods have been investigated by degrading methylene blue (MB) under visible light irradiation. MB solution with the concentration of 10 mg L{sup −1} can be degraded totally with the irradiation time increasing to 240 min. Cerium titanate nanorods exhibit great potential in photocatalytic degradation of MB under visible light irradiation.

  3. Novel borothermal route for the synthesis of lanthanum cerium hexaborides and their field emission properties

    Energy Technology Data Exchange (ETDEWEB)

    Menaka [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India); Patra, Rajkumar; Ghosh, Santanu [Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India); Ganguli, Ashok K., E-mail: ashok@chemistry.iitd.ac.in [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India)

    2012-10-15

    The present study describes the development of a simple approach to stabilize polycrystalline lanthanum cerium hexaborides without using any flux and at ambient pressure. The nanostructured lanthanum-cerium borides were synthesized using hydroxide precursors. These precursors (La{sub 1-x}Ce{sub x}(OH){sub 3}, x=0.1, 0.2, 0.3 and 0.5) were synthesized via hydrothermal route in the presence of Tergitol (surfactant, nonylphenol ethoxylate) as a capping agent. The precursors on heating with boron at 1300 Degree-Sign C lead to the formation of nanostructures (cubes, rods and pyramids) of lanthanum cerium hexaboride. We have investigated the field emission behaviour of the hexaboride films fabricated by spin coating. It was observed that the pyramidal shaped nanostructures of La{sub 0.5}Ce{sub 0.5}B{sub 6} shows excellent field emission characteristics with high field enhancement factor of 4502. - Graphical abstract: Nanostructured lanthanum cerium hexaboride with efficient field emission have fabricated by low temperature hydroxide precursor mediated route. Highlights: Black-Right-Pointing-Pointer New methodology to prepare lanthanum cerium hexaboride at 1300 Degree-Sign C via borothermal route. Black-Right-Pointing-Pointer Nanostructured lanthanum cerium hexaboride film by spin coating process. Black-Right-Pointing-Pointer Nanopyramids based lanthanum cerium hexaboride shows excellent field emission.

  4. Altering properties of cerium oxide thin films by Rh doping

    Energy Technology Data Exchange (ETDEWEB)

    Ševčíková, Klára, E-mail: klarak.sevcikova@seznam.cz [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); NIMS Beamline Station at SPring-8, National Institute for Materials Science, Sayo, Hyogo 679-5148 (Japan); Nehasil, Václav, E-mail: nehasil@mbox.troja.mff.cuni.cz [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Vorokhta, Mykhailo, E-mail: vorohtam@gmail.com [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Haviar, Stanislav, E-mail: stanislav.haviar@gmail.com [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); Matolín, Vladimír, E-mail: matolin@mbox.troja.mff.cuni.cz [Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8 (Czech Republic); and others

    2015-07-15

    Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeO{sub x} thin films. • Intensive oxygen migration in films with low concentration of rhodium. • Oxygen migration suppressed in films with high amount of Rh dopants. - Abstract: Ceria containing highly dispersed ions of rhodium is a promising material for catalytic applications. The Rh–CeO{sub x} thin films with different concentrations of rhodium were deposited by RF magnetron sputtering and were studied by soft and hard X-ray photoelectron spectroscopies, Temperature programmed reaction and X-ray powder diffraction techniques. The sputtered films consist of rhodium–cerium mixed oxide where cerium exhibits a mixed valency of Ce{sup 4+} and Ce{sup 3+} and rhodium occurs in two oxidation states, Rh{sup 3+} and Rh{sup n+}. We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeO{sub x} thin films. The films with low concentrations of rhodium are polycrystalline, while the films with higher amount of Rh dopants are amorphous. The morphology of the films strongly influences the mobility of oxygen in the material. Therefore, varying the concentration of rhodium in Rh–CeO{sub x} thin films leads to preparing materials with different properties.

  5. Biosorption potential of cerium ions usingSpirulina biomass

    Institute of Scientific and Technical Information of China (English)

    David Sadovsky; Asher Brenner; Boaz Astrachan; Boaz Asaf; Raphael Gonen

    2016-01-01

    Two types of cyanobacteria of the genusArthrospira (commonly known asSpirulina) were tested for biosorption of ce-rium(III) ions from aqueous solutions. An endemic type (ES) found in the northern Negev desert, Israel, and a commercial powder (CS) were used in this study. Biosorption was evaluated as a function of pH, contact time, initial metal concentration, number of sorp-tion-desorption cycles, and salt concentration. The optimum pH range for biosorption was found to be 5.0–5.5. The kinetic character-istics of bothSpirulina types were found to be highly compatible with a pseudo-second order kinetic model. The adsorption isotherms of both types were found to be well-suited to Langmuir and Freundlich adsorption isotherms. Maximum biosorption uptakes, accord-ing to the Langmuir model, were 18.1 and 38.2 mg/g, for ES and CS, respectively. Sodium chloride concentrations of up to 5 g/L had a minor effect on cerium biosorption. Desorption efficiency was found to be greater than 97% with 0.1 mol/L HNO3 after three sorp-tion-desorption cycles, without significant loss in the biosorption capacity. The results indicated the feasibility of cerium recovery from industrial wastes usingSpirulina biomass.

  6. Cerium fluoride nanoparticles protect cells against oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Shcherbakov, Alexander B.; Zholobak, Nadezhda M. [Zabolotny Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kyiv D0368 (Ukraine); Baranchikov, Alexander E. [Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); Ryabova, Anastasia V. [Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow 115409 (Russian Federation); Ivanov, Vladimir K., E-mail: van@igic.ras.ru [Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); National Research Tomsk State University, Tomsk 634050 (Russian Federation)

    2015-05-01

    A novel facile method of non-doped and fluorescent terbium-doped cerium fluoride stable aqueous sols synthesis is proposed. Intense green luminescence of CeF{sub 3}:Tb nanoparticles can be used to visualize these nanoparticles' accumulation in cells using confocal laser scanning microscopy. Cerium fluoride nanoparticles are shown for the first time to protect both organic molecules and living cells from the oxidative action of hydrogen peroxide. Both non-doped and terbium-doped CeF{sub 3} nanoparticles are shown to provide noteworthy protection to cells against the vesicular stomatitis virus. - Highlights: • Facile method of CeF{sub 3} and CeF{sub 3}:Tb stable aqueous sols synthesis is proposed. • Naked CeF{sub 3} nanoparticles are shown to be non-toxic and to protect cells from the action of H{sub 2}O{sub 2}. • CeF{sub 3} and CeF{sub 3}:Tb nanoparticles are shown to protect living cells against the vesicular stomatitis virus.

  7. Cerium Tetrafluoride: Sublimation, Thermolysis, and Atomic Fluorine Migration.

    Science.gov (United States)

    Chilingarov, N S; Knot'ko, A V; Shlyapnikov, I M; Mazej, Z; Kristl, M; Sidorov, L N

    2015-08-06

    Saturated vapor pressure p° and enthalpy of sublimation (ΔsH°) of cerium tetrafluoride CeF4 were determined by means of Knudsen effusion mass spectrometry in the range of 750-920 K. It was discovered that sublimation of cerium tetrafluoride from a platinum effusion cell competes with thermal decomposition to CeF3 in the solid phase, but no accompanying release of fluorine to the gas phase occurs. Thus, fluorine atoms migrate within the surface layer of CeF4(s) to the regions of their irreversible drain. We used scanning electron microscopy to study the distribution of the residual CeF3(s) across the inner surface of the effusion cell after complete evaporation of CeF4(s). It was observed that CeF3 accumulates near the edge of the effusion orifice and near the junction of the lid and the body of the cell, that is, in those regions where the fluorine atoms can migrate to a free platinum surface and thus be depleted from the system. Distribution of CeF3(s) solid particles indicates the ways of fluorine atoms migration providing CeF3(s) formation inside the CeF4(s) surface layer.

  8. Functionalization of nanostructured cerium oxide films with histidine.

    Science.gov (United States)

    Tsud, Nataliya; Bercha, Sofiia; Acres, Robert G; Vorokhta, Mykhailo; Khalakhan, Ivan; Prince, Kevin C; Matolín, Vladimír

    2015-01-28

    The surfaces of polycrystalline cerium oxide films were modified by histidine adsorption under vacuum and characterized by the synchrotron based techniques of core and valence level photoemission, resonant photoemission and near edge X-ray absorption spectroscopy, as well as atomic force microscopy. Histidine is strongly bound to the oxide surface in the anionic form through the deprotonated carboxylate group, and forms a disordered molecular adlayer. The imidazole ring and the amino side group do not form bonds with the substrate but are involved in the intermolecular hydrogen bonding which stabilizes the molecular adlayer. The surface reaction with histidine results in water desorption accompanied by oxide reduction, which is propagated into the bulk of the film. Previously studied, well-characterized surfaces are a guide to the chemistry of the present polycrystalline surface and histidine bonds via the carboxylate group in both cases. In contrast, bonding via the imidazole group occurs on the well-ordered surface but not in the present case. The morphology and structure of the cerium oxide are decisive factors which define the adsorption geometry of the histidine adlayer.

  9. Titrimetric and Spectrophotometric Methods for the Assay of Ketotifen Using Cerium(IV) and Two Reagents

    OpenAIRE

    Madihalli Srinivas Raghu; Kanakapura Basavaiah; Kudige Nagaraj Prashanth; Kanakapura Basavaiah Vinay

    2013-01-01

    One titrimetric and two spectrophotometric methods are described for the determination of ketotifen fumarate (KTF) in bulk drug and in tablets using cerium(IV) as the oxidimetric agent. In titrimetry (method A), the drug was treated with a measured excess of cerium(IV) in H2SO4 medium and after a standing time of 10 min, the surplus oxidant was determined by back titration with iron(II). The spectrophotometric procedures involve addition of a known excess of cerium(IV) to KTF in acid medium f...

  10. Structural, topographical and electrical properties of cerium doped strontium barium niobate (Ce:SBN60) ceramics

    Science.gov (United States)

    Raj, S. Gokul; Mathivanan, V.; Kumar, G. Ramesh; Yathavan, S.; Mohan, R.

    2016-05-01

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr0.6B0.4Nb2O6) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce+ ions on the photoluminescence properties was investigated in detail. The grain size topographical behavior of SBN powders and their associated abnormal grain growth (AGG) were completely analyzed through SEM studies. Finally dielectric, measurement discusses about the broad phase transition observed due to cerium dopant The results were discussed in detail.

  11. Magnetophotonic crystal with cerium substituted yttrium iron garnet and enhanced Faraday rotation angle.

    Science.gov (United States)

    Yoshimoto, Takuya; Goto, Taichi; Isogai, Ryosuke; Nakamura, Yuichi; Takagi, Hiroyuki; Ross, C A; Inoue, M

    2016-04-18

    Magnetophotonic crystals (MPCs) comprising cerium-substituted yttrium iron garnet (CeYIG) sandwiched by two Bragg mirrors were fabricated by vacuum annealing. CeYIG was deposited on Bragg mirrors at room temperature and annealed in 5 Pa of residual air. No ceria or other non-garnet phases were detected. Cerium 3 + ions substituted on the yttrium sites and no cerium 4 + ions were found. The Faraday rotation angle of the MPC was -2.92° at a wavelength of λ = 1570 nm was 30 times larger than that of the CeYIG film. These results showed good agreement with calculated values derived using a matrix approach.

  12. 13 CFR 124.303 - What is termination?

    Science.gov (United States)

    2010-01-01

    ... Section 124.303 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION 8(a) BUSINESS DEVELOPMENT/SMALL DISADVANTAGED BUSINESS STATUS DETERMINATIONS 8(a) Business Development Exiting the 8(a) Bd Program... or business structure, management or control pursuant to §§ 124.105 and 124.106. (5) Failure by...

  13. Effects of uncoated and citric acid coated cerium oxide nanoparticles, bulk cerium oxide, cerium acetate, and citric acid on tomato plants

    Energy Technology Data Exchange (ETDEWEB)

    Barrios, Ana Cecilia [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Rico, Cyren M. [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Trujillo-Reyes, Jesica [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Medina-Velo, Illya A. [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Peralta-Videa, Jose R. [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Environmental Science and Engineering Ph.D. Program, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Gardea-Torresdey, Jorge L., E-mail: jgardea@utep.edu [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Environmental Science and Engineering Ph.D. Program, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States)

    2016-09-01

    Little is known about the physiological and biochemical responses of plants exposed to surface modified nanomaterials. In this study, tomato (Solanum lycopersicum L.) plants were cultivated for 210 days in potting soil amended with uncoated and citric acid coated cerium oxide nanoparticles (nCeO{sub 2}, CA + nCeO{sub 2}) bulk cerium oxide (bCeO{sub 2}), and cerium acetate (CeAc). Millipore water (MPW), and citric acid (CA) were used as controls. Physiological and biochemical parameters were measured. At 500 mg/kg, both the uncoated and CA + nCeO{sub 2} increased shoot length by ~ 9 and ~ 13%, respectively, while bCeO{sub 2} and CeAc decreased shoot length by ~ 48 and ~ 26%, respectively, compared with MPW (p ≤ 0.05). Total chlorophyll, chlo-a, and chlo-b were significantly increased by CA + nCeO{sub 2} at 250 mg/kg, but reduced by bCeO{sub 2} at 62.5 mg/kg, compared with MPW. At 250 and 500 mg/kg, nCeO{sub 2} increased Ce in roots by 10 and 7 times, compared to CA + nCeO{sub 2}, but none of the treatments affected the Ce concentration in above ground tissues. Neither nCeO{sub 2} nor CA + nCeO{sub 2} affected the homeostasis of nutrient elements in roots, stems, and leaves or catalase and ascorbate peroxidase in leaves. CeAc at 62.5 and 125 mg/kg increased B (81%) and Fe (174%) in roots, while at 250 and 500 mg/kg, increased Ca in stems (84% and 86%, respectively). On the other hand, bCeO{sub 2} at 62.5 increased Zn (152%) but reduced P (80%) in stems. Only nCeO{sub 2} at 62.5 mg/kg produced higher total number of tomatoes, compared with control and the rest of the treatments. The surface coating reduced Ce uptake by roots but did not affect its translocation to the aboveground organs. In addition, there was no clear effect of surface coating on fruit production. To our knowledge, this is the first study comparing the effects of coated and uncoated nCeO{sub 2} on tomato plants. - Highlights: • At 500 mg/kg, coated and bare NPs increased stem length by 13 and 9

  14. Synthesis of cerium oxide (CeO{sub 2}) nanoparticles using simple CO-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Farahmandjou, M.; Zarinkamar, M.; Firoozabadi, T. P., E-mail: farahamndjou@iauvaramin.ac.ir [Islamis Azad University, Varamin-Phisva Branch, Department of Physics, Varamin (Iran, Islamic Republic of)

    2016-11-01

    Synthesis of cerium oxide (CeO{sub 2}) nanoparticles was studied by new and simple co-precipitation method. The cerium oxide nanoparticles were synthesized using cerium nitrate and potassium carbonate precursors. Their physicochemical properties were characterized by high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (Sem), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (Ftir) and UV-Vis spectrophotometer. XRD pattern showed the cubic structure of the cerium oxide nanoparticles. The average particle size of CeO{sub 2} was around 20 nm as estimated by XRD technique and direct HRTEM observations. The surface morphological studies from Sem and Tem depicted spherical particles with formation of clusters. The sharp peaks in Ftir spectrum determined the existence of CeO{sub 2} stretching mode and the absorbance peak of UV-Vis spectrum showed the bandgap energy of 3.26 eV. (Author)

  15. Inhaled Diesel Emissions Generated with Cerium Oxide Nanoparticle Fuel Additive Induce Adverse Pulmonary and Systemic Effects

    Science.gov (United States)

    Diesel exhaust (DE) exposure induces adverse cardiopulmonary effects. Cerium oxide nanoparticles added to diesel fuel (DECe) increases fuel burning efficiency but leads to altered emission characteristics and potentially altered health effects. Here, we evaluated whether DECe res...

  16. EFFECT OF CERIUM ION IMPLANTATION ON THE AQUEOUS CORROSION BEHAVIOR OF ZIRCONIUM

    Institute of Scientific and Technical Information of China (English)

    D.Q. Peng; X.D. Bai; Q.G. Zhou; X.W. Chen; R.H. Yu; X.Y. Liu

    2004-01-01

    In order to study the influence of cerium ion implantation on the aqueous corrosion behavior of zirconium, specimens were implanted by cerium ions with a dosage range from 1 ×1016 to 1 ×1017 ions/cm2 at about 150℃, using MEWA source at an acceler ative voltage of 40kV. The valence of the surface layer was analyzed by X-ray photoelectron spectroscopy (XPS); Three-sweep potentiodynamic polarization measurement was employed to value the aqueous corrosion resistance of zirconium in a 0.5mol/L H2SO4 solution. It was found that a remarkable decline in the aqueous corrosion behavior of zirconium implanted with cerium ions compared with that of the as-received zirconium. Finally, the mechanism of the corrosion resistance decline of the cerium-implanted zirconium is discussed.

  17. Study on Catalysts with Rhodium Loading on Different Cerium-Zirconium Mixed Oxides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The catalysts with Rh loading on different cerium-zirconium mixed oxides were characterized by BET, H2-TPR and OSC. The effects of different cerium-zirconium mixed oxides on catalytic performance and thermal stability of Rh loaded catalyst were studied. The results show that: (1) Rh can enhance cerium-zirconium mixed oxides OSC and catalytic reaction rates; (2) cerium-zirconium mixed oxides with high Ce contents and low Zr contents are more favorable to the stability of catalysts. Moreover, the contents of CeO2 have important effect on catalysts characteristics, and the addition of some rare earth components, such as La, Pr and Nd also have some influences.

  18. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents

    OpenAIRE

    2016-01-01

    We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce–Co/Al2O3 membrane, which are employed as catalysts for the catalytic wet oxidation (CWO) reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation ...

  19. Transformation of Cerium Oxide Nanoparticles from a Diesel Fuel Additive during Combustion in a Diesel Engine.

    Science.gov (United States)

    Dale, James G; Cox, Steven S; Vance, Marina E; Marr, Linsey C; Hochella, Michael F

    2017-02-21

    Nanoscale cerium oxide is used as a diesel fuel additive to reduce particulate matter emissions and increase fuel economy, but its fate in the environment has not been established. Cerium oxide released as a result of the combustion of diesel fuel containing the additive Envirox, which utilizes suspended nanoscale cerium oxide to reduce particulate matter emissions and increase fuel economy, was captured from the exhaust stream of a diesel engine and was characterized using a combination of bulk analytical techniques and high resolution transmission electron microscopy. The combustion process induced significant changes in the size and morphology of the particles; ∼15 nm aggregates consisting of 5-7 nm faceted crystals in the fuel additive became 50-300 nm, near-spherical, single crystals in the exhaust. Electron diffraction identified the original cerium oxide particles as cerium(IV) oxide (CeO2, standard FCC structure) with no detectable quantities of Ce(III), whereas in the exhaust the ceria particles had additional electron diffraction reflections indicative of a CeO2 superstructure containing ordered oxygen vacancies. The surfactant coating present on the cerium oxide particles in the additive was lost during combustion, but in roughly 30% of the observed particles in the exhaust, a new surface coating formed, approximately 2-5 nm thick. The results of this study suggest that pristine, laboratory-produced, nanoscale cerium oxide is not a good substitute for the cerium oxide released from fuel-borne catalyst applications and that future toxicity experiments and modeling will require the use/consideration of more realistic materials.

  20. FUN3D Manual: 12.4

    Science.gov (United States)

    Biedron, Robert T.; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bil; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.

    2014-01-01

    This manual describes the installation and execution of FUN3D version 12.4, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixedelement unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.

  1. Thermal Treatment of Cerium Oxide and Its Properties: Adsorption Ability versus Degradation Efficiency

    Directory of Open Access Journals (Sweden)

    Pavel Janoš

    2014-01-01

    Full Text Available Cerium oxide belongs to the most important heterogeneous catalysts, but its applicability as so-called reactive sorbent for the degradation of toxic chemicals was only recently discovered. For these purposes, cerium oxide is prepared by precipitation of insoluble cerium salts (carbonates with a subsequent thermal decomposition. Properties of cerium oxide prepared from the carbonate precursor are strongly affected by the temperature during the calcination. Main physicochemical properties of cerium oxide (specific surface area, crystallinity, and surface chemistry were examined in dependence on the calcination temperature. As the adsorptive properties of CeO2 are undoubtedly of great importance in the abovementioned applications, the adsorption ability was studied using an azo dye Acid Orange 7 (AO7 as a model compound. The highest sorption efficiency towards AO7 exhibited sorbents prepared at temperatures below 700°C, which was attributed mainly to the presence of hydroxyl groups on the oxide surface. A strong correlation was found between an adsorption efficiency of cerium oxides and their degradation efficiency for organophosphate pesticide parathion methyl. The >Ce–OH groups on the sorbent surface are responsible for the dye binding by the surface-complexation mechanism, and probably also for the nucleophilic cleavage of the P–O–aryl bond in the pesticide molecule.

  2. Thermopower enhancement by encapsulating cerium in clathrate cages.

    Science.gov (United States)

    Prokofiev, A; Sidorenko, A; Hradil, K; Ikeda, M; Svagera, R; Waas, M; Winkler, H; Neumaier, K; Paschen, S

    2013-12-01

    The increasing worldwide energy consumption calls for the design of more efficient energy systems. Thermoelectrics could be used to convert waste heat back to useful electric energy if only more efficient materials were available. The ideal thermoelectric material combines high electrical conductivity and thermopower with low thermal conductivity. In this regard, the intermetallic type-I clathrates show promise with their exceedingly low lattice thermal conductivities. Here we report the successful incorporation of cerium as a guest atom into the clathrate crystal structure. In many simpler intermetallic compounds, this rare earth element is known to lead, through the Kondo interaction, to strong correlation phenomena including the occurrence of giant thermopowers at low temperatures. Indeed, we observe a 50% enhancement of the thermopower compared with a rare-earth-free reference material. Importantly, this enhancement occurs at high temperatures and we suggest that a rattling-enhanced Kondo interaction underlies this effect.

  3. Effect of Surface Modification on Behaviors of Cerium Oxide Nanopowders

    Institute of Scientific and Technical Information of China (English)

    Li Mei; Shi Zhenxue; Liu Zhaogang; Hu Yanhong; Wang Mitang; Li Hangquan

    2007-01-01

    Study was made on the effect of surface modification on the behaviors of cerium oxide nanopowders. A surfactant-sodium dodecyl sulfate(C12H25SO4Na) was used to modify the surface of CeO2 powder particles. The unmodified and modified CeO2 powders were characterized by using a powder comprehensive characteristic tester, laser particle size analyzer, specific surface area tester, X-ray diffraction tester, and a scanning electron microscope. The testing and analysis results showed that C12H25SO4Na surface modification might increase the flowability and dispersity, and decrease the specific surface area and agglomeration of CeO2 powders. The mechanism of the surface modification of CeO2 powder particles was also discussed.

  4. EPDM composite membranes modified with cerium doped lead zirconate titanate

    Science.gov (United States)

    Zaharescu, T.; Dumitru, A.; Lungulescu, M. E.; Velciu, G.

    2016-01-01

    This study was performed on γ-irradiated ethylene-propylene diene terpolymer (EPDM) loaded with lead zirconate titanate. The inorganic phase has a perovskite structure with general formula Pb(Zr0.65-xCexTi0.35)O3. The three composites with different Ce dopant concentrations revealed the stabilization activity of filler against oxidation proved by chemiluminescence investigation in respect to pristine polymer. The presence of cerium low concentrations in the solid lead zirconate titanate nanoparticles causes significant slowing of oxidation rate during radiation exposure. The improvement in the stabilization feature of filler is correlated with the existence of traps, whose interaction with free radicals assumes medium energy due to their convenient depth.

  5. On the mixed nature of cerium conversion coatings

    Energy Technology Data Exchange (ETDEWEB)

    Botana, F.J.; Aballe, A.; Bethencourt, M.; Cano, M.J. [Cadiz Univ. (Spain). Dept. de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica; Marcos, M. [Cadiz Univ. (Spain). Dept. de Ingenieria Mecanica y Diseno Industrial

    2002-03-01

    Alternative pretreatments are currently under development in order to avoid the environmental impact produced by using surface finishing processes based on chromates. Some of the environmentally friendly alternatives proposed involve the use of lanthanide based compounds. In this study, conversion coatings on AA5083 (Al-Mg) samples developed using full immersion pretreatments in 500 ppm CeCl{sub 3} aqueous solutions have been investigated. Their microscopic and compositional features have been analyzed using SEM images and EDS spectra. From this analysis it has been determined that this layer over the surface of the samples is of a heterogeneous composition. This coating is formed by an alumina coating covering the aluminum matrix and dispersed cerium-rich islands deposited over the cathodic sites of the alloy. A characterization methodology is proposed based on the utilization of different electrochemical techniques, such as open circuit potential monitoring (OCP), linear polarization (LP) and electrochemical impedance spectroscopy (EIS). (orig.)

  6. Characterization of a zinc-cerium flow battery

    Science.gov (United States)

    Leung, P. K.; Ponce-de-León, C.; Low, C. T. J.; Shah, A. A.; Walsh, F. C.

    The performance of a divided, parallel-plate zinc-cerium redox flow battery using methanesulfonic acid electrolytes was studied. Eight two and three-dimensional electrodes were tested under both constant current density and constant cell voltage discharge. Carbon felt and the three-dimensional platinised titanium mesh electrodes exhibited superior performance over the 2-dimensional electrodes. The charge and discharge characteristics of the redox flow battery were studied under different operating conditions and Zn/Ce reactant, as well as methansulfonic acid concentration. The cell performance improved at higher operating temperatures and faster electrolyte flow velocities. The number of possible cycles increased at reduced states of charge. During 15 min charge/discharge per cycle experiment, 57 cycles were obtained and the zinc reaction was found to be the limiting process during long term operation.

  7. Interplay of spin-orbit and entropic effects in cerium

    Energy Technology Data Exchange (ETDEWEB)

    Lanata, Nicola [Rutgers University; Yao, Yong-Xin [Ames Laboratory; Wang, Cai-Zhuang [Ames Laboratory; Ho, Kai-Ming [Ames Laboratory; Kotliar, Gabriel [Rutgers University

    2014-10-01

    We perform first-principles calculations of elemental cerium and compute its pressure-temperature phase diagram, finding good quantitative agreement with the experiments. Our calculations indicate that, while a signature of the volume-collapse transition appears in the free energy already at low temperatures, at higher temperatures this signature is enhanced because of the entropic effects, and originates an actual thermodynamical instability. Furthermore, we find that the catalyst determining this feature is—in all temperature regimes—a pressure-induced effective reduction of the f-level degeneracy due to the spin-orbit coupling. Our analysis suggests also that the lattice vibrations might be crucial in order to capture the behavior of the pressure-temperature transition line at large temperatures.

  8. Cerium intermetallics with TiNiSi-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Janka, Oliver; Niehaus, Oliver; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ. CNRS (UPR 9048), Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux (ICMCB)

    2016-08-01

    Intermetallic compounds with the equiatomic composition CeTX that crystallize with the orthorhombic TiNiSi-type structure can be synthesized with electron-rich transition metals (T) and X = Zn, Al, Ga, Si, Ge, Sn, As, Sb, and Bi. The present review focusses on the crystal chemistry and chemical bonding of these CeTX phases and on their physical properties, {sup 119}Sn and {sup 121}Sb Moessbauer spectra, high-pressure effects, hydrogenation reactions and the formation of solid solutions in order to elucidate structure-property relationships. This paper is the final one of a series of four reviews on equiatomic intermetallic cerium compounds [Part I: Z. Naturforsch. 2015, 70b, 289; Part II: Z. Naturforsch. 2015, 70b, 695; Part III: Z. Naturforsch. 2016, 71b, 165].

  9. Growth of transition metals on cerium tungstate model catalyst layers

    Science.gov (United States)

    Skála, T.; Tsud, N.; Stetsovych, V.; Mysliveček, J.; Matolín, V.

    2016-10-01

    Two model catalytic metal/oxide systems were investigated by photoelectron spectroscopy and scanning tunneling microscopy. The mixed-oxide support was a cerium tungstate epitaxial thin layer grown in situ on the W(1 1 0) single crystal. Active particles consisted of palladium and platinum 3D islands deposited on the tungstate surface at 300 K. Both metals were found to interact weakly with the oxide support and the original chemical state of both support and metals was mostly preserved. Electronic and morphological changes are discussed during the metal growth and after post-annealing at temperatures up to 700 K. Partial transition-metal coalescence and self-cleaning from the CO and carbon impurities were observed.

  10. The Spin Glass-Kondo Competition in Disordered Cerium Systems

    Science.gov (United States)

    Magalhaes, S. G.; Zimmer, F.; Coqblin, B.

    2013-10-01

    We discuss the competition between the Kondo effect, the spin glass state and a magnetic order observed in disordered Cerium systems. We present firstly the experimental situation of disordered alloys such as CeNi1 - xCux and then the different theoretical approaches based on the Kondo lattice model, with different descriptions of the intersite exchange interaction for the spin glass. After the gaussian approach of the Sherrington-Kirkpatrick model, we discuss the Mattis and the van Hemmen models. Then, we present simple cluster calculations in order to describe the percolative evolution of the clusters from the cluster spin glass to the inhomogeneous ferromagnetic order recently observed in CeNi1 - xCux disordered alloys and finally we discuss the effect of random and transverse magnetic field.

  11. Effects of cerium nitrate on the growth and physiological characteristics in Cyclocarya paliurusseedlings

    Institute of Scientific and Technical Information of China (English)

    谢寅峰; 李颖; 刘娜娜; 张颖颖; 郭楠; 王涛; 尚绪岚

    2015-01-01

    Field studies were conducted to examine the effects of cerium on the growth and physiological characteristics ofCyclo-carya paliurusseedlings by spraying the foliage with different concentrations of cerium nitrate. Optimal concentrations of cerium ni-trate improved the relative growth yield of seedling height and stems and the soluble protein and sugar content of the leaves. Cerium nitrate also increased the concentration of secondary metabolites including triterpenoids, quercetin and kaempferol, mineral elements K, P, Mg, Mn, Fe and Cu, and the activities of superoxide dismutase (SOD), peroxidase (POX), and phenylalanine ammonia-lyase (PAL) in the leaves. The effects of cerium nitrate on these indices were dose dependent. A concentration of 0.20 mmol/L was optimal to promote the relative growth yield of seedling height, contents of soluble sugar, kaempferol, K, P, Cu, and activities of PAL, SOD, and POX, significantlyincreased by 54.61%, 14.71%, 55.19%, 105.2%, 74.5%, 133.3%, 80.48%, 25.35% and 22.54%, respectively, as compared with the control. However, the maximal increase in relative growth yield of stems, contents of triterpenoid, quercetin, Mg, Mn, and Fe was attained at 1.00 mmol/L treatment, which significantlyincreased by 87.00%, 80.56%, 452.44%, 93.2%, 29.4%, and 133.9%, respectively, compared with control check (CK). Correlation analysis revealed positive relationships between activities of PAL, SOD and contents of triterpenoid, quercetin and kaempferol within a certain concentration range of cerium nitrate. These re-sults suggested that an appropriate concentration of cerium not only was effective in the improvement of physiological function ofC. paliurus, but alsoincreased seedling resistance. Moreover, it stimulated the synthesis of medicinal components in leaves.

  12. miRNA-124 in Immune System and Immune Disorders

    OpenAIRE

    2016-01-01

    In recent years, miR-124 has emerged as a critical modulator of immunity and inflammation. Here, we summarize studies on the function and mechanism of miR-124 in the immune system and immunity-related diseases. They indicated that miR-124 exerts a crucial role in the development of immune system, regulation of immune responses, and inflammatory disorders. It is evident that miR-124 may serve as an informative diagnostic biomarker and therapeutic target in the future.

  13. Exposure, Health and Ecological Effects Review of Engineered Nanoscale Cerium and Cerium Oxide Associated with its Use as a Fuel Additive

    Science.gov (United States)

    Advances of nanoscale science have produced nanomaterials with unique physical and chemical properties at commercial levels which are now incorporated into over 1000 products. Nanoscale cerium (di) oxide (CeO(2)) has recently gained a wide range of applications which includes coa...

  14. Exposure and Health Effects Review of Engineered Nanoscale Cerium and Cerium Dioxide Associated with its Use as a Fuel Additive - NOW IN PRINT IN THE JOURNAL

    Science.gov (United States)

    Advances of nanoscale science have produced nanomaterials with unique physical and chemical properties at commercial levels that are now incorporated into over 1000 products. Nanoscale cerium (di) oxide (Ce02) has recently gained a wide range of applications which includes coatin...

  15. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents

    Directory of Open Access Journals (Sweden)

    Mirella Gutiérrez-Arzaluz

    2016-05-01

    Full Text Available We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce–Co/Al2O3 membrane, which are employed as catalysts for the catalytic wet oxidation (CWO reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation methods do not work for formaldehyde, a highly toxic but refractory, low biodegradability substance. The CWO reaction is a recent, promising alternative that also permits much lower temperature and pressure conditions than other oxidation processes, resulting in economic benefits. The CWO reaction employing Ce- and Co-containing catalysts was carried out inside a slurry batch reactor and a membrane reactor. Experimental results are reported. Next, a mixed Ce–Co oxide film was supported on an γ-alumina membrane used in a catalytic membrane reactor to compare formaldehyde removal between both types of systems. Catalytic materials with cerium and with a relatively large amount of cerium favored the transformation of formaldehyde. Cerium was present as cerianite in the catalytic materials, as indicated by X-ray diffraction patterns.

  16. Mechanism of chlorinating lanthanum oxide and cerium oxide with ammonium chloride

    Institute of Scientific and Technical Information of China (English)

    朱国才; 李赋屏; 肖明贵

    2003-01-01

    Using ammonium chloride(NH4Cl)as a chlorinating agent,the effects of chlorinating temperature,at 300℃ for 90 min,and have no advantage to chlorination of lanthanum and cerium oxides at higher temperature.The thermal decomposition of LaCl3 and CeCl3 is carried out to explore the mechanism of chlorinating lanthanum and cerium oxides.At the same time,the chlorination of lanthanum and cerium oxides is not devoted to the HCl decomposed from NH4Cl,but to NH4Cl directly taking part in the chlorination of La2O3 and CeO2.The lanthanum and cerium oxides in chlorination firstly form intermediate LaOCl and CeOCl,and then transfer to LaCl3 and CeCl3,fither prove the existence of the intermediates LaOCl and CeOCl.Therefore the chlorinating temperature and time should strictly be controlled when the lanthanum oxide and cerium oxide are chlorinated with NH4 Cl.And over-dosage of NH4 Cl should be also applied in the process of chlorination.

  17. Production of cerium zinc molybdate nano pigment by innovative ultrasound assisted approach.

    Science.gov (United States)

    Patel, M A; Bhanvase, B A; Sonawane, S H

    2013-05-01

    Ultrasound assisted synthesis of yellow rare earth cerium zinc molybdate anticorrosion nanopigment is presented. This new class of pigment is eco-friendly alternatives to lead, cadmium and chromium pigment as these pigments contains carcinogenic species like Cr(6+) which is responsible for human disease. The synthesis of nanosized cerium zinc molybdate was carried out using cerium nitrate, sodium zinc molybdate as a precursor materials by conventional and ultrasound assisted chemical precipitation method without addition of emulsification agent. XRD, FTIR and elemental analysis confirm the formation of cerium zinc molybdate nanoparticles. The conductivity results indicate that conventional synthesis takes longer time, while in sonochemical technique (US), reaction completes within short period of time. Improved solute transfer rate, rapid nucleation, and formation of large number of nuclei are attributed to presence of cavitation. Saturation of the Ce(3+) ions reaches earlier in case of sonochemical technique which restricts the growth of particles hence smaller size is obtained. The crystallite size of cerium zinc molybdate was found to be 27nm from XRD analysis.

  18. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents.

    Science.gov (United States)

    Gutiérrez-Arzaluz, Mirella; Noreña-Franco, Luis; Ángel-Cuevas, Saúl; Mugica-Álvarez, Violeta; Torres-Rodríguez, Miguel

    2016-05-24

    We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce-Co/Al₂O₃ membrane, which are employed as catalysts for the catalytic wet oxidation (CWO) reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation methods do not work for formaldehyde, a highly toxic but refractory, low biodegradability substance. The CWO reaction is a recent, promising alternative that also permits much lower temperature and pressure conditions than other oxidation processes, resulting in economic benefits. The CWO reaction employing Ce- and Co-containing catalysts was carried out inside a slurry batch reactor and a membrane reactor. Experimental results are reported. Next, a mixed Ce-Co oxide film was supported on an γ-alumina membrane used in a catalytic membrane reactor to compare formaldehyde removal between both types of systems. Catalytic materials with cerium and with a relatively large amount of cerium favored the transformation of formaldehyde. Cerium was present as cerianite in the catalytic materials, as indicated by X-ray diffraction patterns.

  19. Effects of precipitate aging time on the cerium-zirconium composite oxides

    Institute of Scientific and Technical Information of China (English)

    钟强; 崔梅生; 岳梅; 王琦; 王磊; 郭荣贵; 龙志奇; 黄小卫

    2014-01-01

    Cerium-zirconium composite oxides with high performance were synthesized by a co-precipitation method, using zirco-nium oxychloride and rare earth chloride as raw materials. The effects of precipitate aging time on the properties of cerium-zirconium composite oxides were investigated. The prepared cerium-zirconium composite oxides were characterized by X-ray diffraction (XRD), BET specific surface area, pulsed oxygen chemical adsorption, H2 temperature-programmed-reduction (H2-TPR), scanning electron microscopy (SEM), etc. The results showed that the precipitate aging time caused great effects on the properties of cerium zirconium composite oxides. With the increase of aging time, the cerium zirconium composite oxides showed enhanced specific sur-face area, good thermal stability, and high oxygen storage capacity (OSC). The best performance sample was obtained while the pre-cipitate aging time up to 48 h, with the specific surface area of 140.7 m2/g, and OSC of 657.24μmolO2/g for the fresh sample. Even after thermal aged under 1000 ºC for 4 h, the aged specific surface area was 41.6 m2/g, moreover with a good OSC of 569.9μmolO2/g.

  20. Toenail cerium levels and risk of a first acute myocardial infarction: The EURAMIC and heavy metals study

    NARCIS (Netherlands)

    Gomez-Aracena, J.; Riemersma, R.A.; Veer, van 't P.; Kok, F.J.

    2006-01-01

    The association between cerium status and risk of first acute myocardial infarction (AMI) was examined in a case-control study in 10 centres from Europe and Israel. Cerium in toenails was assessed by neutron activation analysis in 684 cases and 724 controls aged 70years or younger. Mean concentratio

  1. 32 CFR 701.124 - PA self assessments/inspections.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false PA self assessments/inspections. 701.124 Section... OF THE NAVY DOCUMENTS AFFECTING THE PUBLIC DON Privacy Program § 701.124 PA self assessments/inspections. (a) Self assessments. DON activities are encouraged to conduct annual self-assessments of...

  2. 13 CFR 124.520 - Mentor/protege program.

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Mentor/protege program. 124.520... § 124.520 Mentor/protege program. (a) General. The mentor/protege program is designed to encourage... form of joint venture arrangements. The purpose of the mentor/protege relationship is to enhance...

  3. 13 CFR 124.107 - What is potential for success?

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What is potential for success? 124... Requirements for Participation in the 8(a) Business Development Program § 124.107 What is potential for success? The applicant concern must possess reasonable prospects for success in competing in the private...

  4. 43 CFR 12.4 - Information collection requirements.

    Science.gov (United States)

    2010-10-01

    ... Section 12.4 Public Lands: Interior Office of the Secretary of the Interior ADMINISTRATIVE AND AUDIT REQUIREMENTS AND COST PRINCIPLES FOR ASSISTANCE PROGRAMS Administrative and Audit Requirements and Cost Principles for Assistance Programs § 12.4 Information collection requirements. Information collections...

  5. 42 CFR 483.124 - FFP for specialized services.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 5 2010-10-01 2010-10-01 false FFP for specialized services. 483.124 Section 483... Screening and Annual Review of Mentally Ill and Mentally Retarded Individuals § 483.124 FFP for specialized services. FFP is not available for specialized services furnished to NF residents as NF services....

  6. 9 CFR 124.20 - Patent term extension calculation.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Patent term extension calculation. 124... OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS PATENT TERM RESTORATION Regulatory Review Period § 124.20 Patent term extension calculation. (a) As provided in 37 CFR...

  7. Antioxidant Cerium Oxide Nanoparticles in Biology and Medicine

    Directory of Open Access Journals (Sweden)

    Bryant C. Nelson

    2016-05-01

    Full Text Available Previously, catalytic cerium oxide nanoparticles (CNPs, nanoceria, CeO2-x NPs have been widely utilized for chemical mechanical planarization in the semiconductor industry and for reducing harmful emissions and improving fuel combustion efficiency in the automobile industry. Researchers are now harnessing the catalytic repertoire of CNPs to develop potential new treatment modalities for both oxidative- and nitrosative-stress induced disorders and diseases. In order to reach the point where our experimental understanding of the antioxidant activity of CNPs can be translated into useful therapeutics in the clinic, it is necessary to evaluate the most current evidence that supports CNP antioxidant activity in biological systems. Accordingly, the aims of this review are three-fold: (1 To describe the putative reaction mechanisms and physicochemical surface properties that enable CNPs to both scavenge reactive oxygen species (ROS and to act as antioxidant enzyme-like mimetics in solution; (2 To provide an overview, with commentary, regarding the most robust design and synthesis pathways for preparing CNPs with catalytic antioxidant activity; (3 To provide the reader with the most up-to-date in vitro and in vivo experimental evidence supporting the ROS-scavenging potential of CNPs in biology and medicine.

  8. Anti-angiogenic activity of heparin functionalised cerium oxide nanoparticles.

    Science.gov (United States)

    Lord, Megan S; Tsoi, Bonny; Gunawan, Cindy; Teoh, Wey Yang; Amal, Rose; Whitelock, John M

    2013-11-01

    Cerium oxide nanoparticles (nanoceria) are widely reported to be non-cytotoxic and modulate intracellular reactive oxygen species (ROS). In this study, nanoceria (dxRD = 12 nm) were functionalised with either 130 or 880 molecules of unfractionated heparin using the organosilane linker, 3-aminopropyltriethoxysilane. Nanoceria with a low level of heparin functionalisation were found to scavenge intracellular ROS to the same extent as unfunctionalised nanoceria and significantly more than cells exposed to medium only. In contrast, nanoceria with the highest level of heparin functionalisation were not as effective at scavenging intracellular ROS. Nanoceria were localised predominantly in the cytoplasm, while heparin-nanoceria were localised in both the cytoplasm and lysosomes. Together these data demonstrated that the level of nanoceria surface functionalisation with heparin determined the intracellular localisation and ROS scavenging ability of these particles. Additionally, heparin-nanoceria were effective in reducing endothelial cell proliferation indicating that they may find application in the control of angiogenesis in cancer in the future.

  9. Surface modification of promising cerium oxide nanoparticles for nanomedicine applications

    KAUST Repository

    Nanda, Himansu Sekhar

    2016-11-14

    Cerium oxide nanoparticles (CNPs) or nanoceria have emerged as a potential nanomedicine for the treatment of several diseases such as cancer. CNPs have a natural tendency to aggregate or agglomerate in their bare state, which leads to sedimentation in a biological environment. Since the natural biological environment is essentially aqueous, nanoparticle surface modification using suitable biocompatible hydrophilic chemical moieties is highly desirable to create effective aqueous dispersions. In this report, (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl)triethoxysilane was used as a functional, biocompatible organosilane to modify the surface of CNPs to produce promising nanoparticles which open substantial therapeutic avenues. The surface modified nanoparticles were produced in situ via an ammonia-induced ethylene glycol-assisted precipitation method and were characterized using complimentary characterization techniques. The interaction between the functional moiety and the nanoparticle was studied using powerful cross polarization/magic angle sample spinning solid state nuclear magnetic resonance spectroscopy. The surface-modified nanoparticles were extremely small and demonstrated a significant improvement in aqueous dispersibility. Moreover, the existence of a strong ionic coordination between the functional moiety and the surface of the nanoparticle was realised, indicating that the surface modified nanoceria are stable and that the nanoparticles should demonstrate an enhanced circulation time in a biological environment. The surface modification approach should be promising for the production of CNPs for nanomedicine applications. © The Royal Society of Chemistry.

  10. Catalytic properties and biomedical applications of cerium oxide nanoparticles

    KAUST Repository

    Walkey, Carl D.

    2014-11-10

    Cerium oxide nanoparticles (nanoceria) have shown promise as catalytic antioxidants in the test tube, cell culture models and animal models of disease. However given the reactivity that is well established at the surface of these nanoparticles, the biological utilization of nanoceria as a therapeutic still poses many challenges. Moreover the form that these particles take in a biological environment, such as the changes that can occur due to a protein corona, are not well established. This review aims to summarize the existing literature on biological use of nanoceria, and to raise questions about what further study is needed to apply this interesting catalytic material to biomedical applications. These questions include: 1) How does preparation, exposure dose, route and experimental model influence the reported effects of nanoceria in animal studies? 2) What are the considerations to develop nanoceria as a therapeutic agent in regards to these parameters? 3) What biological targets of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are relevant to this targeting, and how do these properties also influence the safety of these nanomaterials?

  11. Effect of Impurities and Cerium on Stress Concentration Sensitivity of Al-Li Based Alloys

    Institute of Scientific and Technical Information of China (English)

    孟亮; 田丽

    2002-01-01

    A notch sensitivity factor was derived in order to evaluate the stress concentration sensitivity of Al-Li based alloys. The factor values for the Al-Li alloy sheets containing various contents of impurities and cerium addition were evaluated by determining the mechanical properties. It is found that the impurities Fe, Si, Na and K significantly enhance the stress concentration sensitivity of the alloys 2090 and 8090, whereas cerium addition reduces the stress concentration sensitivity to a certain degree for the high strength alloys. However, an excess amount of cerium addition in the high ductility alloy 1420 can significantly increase the stress concentration sensitivity. As compared with conventional aluminum alloys, the Al-Li based alloys generally show high stress concentration sensitivity. Therefore, a special attention must be paid to this problem in the practical application of Al-Li based alloys.

  12. The role of chemical interactions between thorium, cerium, and lanthanum in lymphocyte toxicity.

    Science.gov (United States)

    Oliveira, Monica S; Duarte, Isabelle M; Paiva, Amanda V; Yunes, Samira N; Almeida, Carlos E; Mattos, Rita C; Sarcinelli, Paula N

    2014-01-01

    Thorium, cerium, and lanthanum are metals present in several types of minerals, the most common of which is monazite. Cerium and lanthanum are elements in the lanthanides series. Thorium, an actinide metal, is a hazardous element due to its radioactive characteristics. There is a lack of information describing the possible chemical interactions among these elements and the effects they may have on humans. Toxicological analyses were performed using cell viability, cell death, and DNA damage assays. Chemical interactions were evaluated based on the Loewe additivity model. The results indicate that thorium and cerium individually have no toxic effects on lymphocytes. However, thorium associated with lanthanum increases the toxicity of this element, thereby reducing the viability of lymphocytes at low concentrations of metals in the mixture.

  13. Oxochloroalkoxide of the Cerium (IV and Titanium (IV as oxides precursor

    Directory of Open Access Journals (Sweden)

    Machado Luiz Carlos

    2002-01-01

    Full Text Available The Cerium (IV and Titanium (IV oxides mixture (CeO2-3TiO2 was prepared by thermal treatment of the oxochloroisopropoxide of Cerium (IV and Titanium (IV. The chemical route utilizing the Cerium (III chloride alcoholic complex and Titanium (IV isopropoxide is presented. The compound Ce5Ti15Cl16O30 (iOPr4(OH-Et15 was characterized by elemental analysis, FTIR and TG/DTG. The X-ray diffraction patterns of the oxides resulting from the thermal decomposition of the precursor at 1000 degreesC for 36 h indicated the formation of cubic cerianite (a = 5.417Å and tetragonal rutile (a = 4.592Å and (c = 2.962 Å, with apparent crystallite sizes around 38 and 55nm, respectively.

  14. Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

    Directory of Open Access Journals (Sweden)

    Subas K. Muduli

    2014-04-01

    Full Text Available A facile, solvothermal synthesis of mesoporous cerium oxide nanospheres is reported for the purpose of the photocatalytic degradation of organic dyes and future applications in sustainable energy research. The earth-abundant, relatively affordable, mixed valence cerium oxide sample, which consists of predominantly Ce7O12, has been characterized by powder X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy, and transmission electron microscopy. Together with N2 sorption experiments, the data confirms that the new cerium oxide material is mesoporous and absorbs visible light. The photocatalytic degradation of rhodamin B is investigated with a series of radical scavengers, suggesting that the mechanism of photocatalytic activity under visible-light irradiation involves predominantly hydroxyl radicals as the active species.

  15. Excitation induced spectroscopic study and quenching effect in cerium samarium codoped lithium aluminoborate glasses

    Science.gov (United States)

    Kaur, Parvinder; Kaur, Simranpreet; Singh, Gurinder Pal; Arora, Deepawali; Kumar, Sunil; Singh, D. P.

    2016-08-01

    Lithium aluminium borate host has been codoped with cerium and samarium to prepare glass by conventional melt quench technique. Their structural and spectroscopic investigation has been carried out using XRD, FTIR and density measurements. The UV-Vis absorption spectra and fluorescence spectra (λexc.=380 nm and 400 nm) have been studied for spectroscopic analysis. The amorphous nature of the prepared samples is shown by XRD. The density is increasing with addition of cerium at the expense of aluminium, keeping other components constant. FTIR study also shows the presence of compact and stable tetrahedral BO4 units thus supporting the density results. The UV- Vis absorption spectra show a shift of optical absorption edge towards longer wavelength along with an increase in intensity of peaks with rising samarium concentration. The fluorescence spectra show a blue shift and subsequent suppression of cerium peaks with addition of samarium.

  16. Structure, Morphology and Reducibility of Epitaxial Cerium Oxide Ultrathin Films and Nanostructures

    Directory of Open Access Journals (Sweden)

    Paola Luches

    2015-08-01

    Full Text Available Cerium oxide is a very interesting material that finds applications in many different fields, such as catalysis, energy conversion, and biomedicine. An interesting approach to unravel the complexity of real systems and obtain an improved understanding of cerium oxide-based materials is represented by the study of model systems in the form of epitaxial ultrathin films or nanostructures supported on single crystalline substrates. These materials often show interesting novel properties, induced by spatial confinement and by the interaction with the supporting substrate, and their understanding requires the use of advanced experimental techniques combined with computational modeling. Recent experimental and theoretical studies performed within this field are examined and discussed here, with emphasis on the new perspectives introduced in view of the optimization of cerium oxide-based materials for application in different fields.

  17. Study of phase transitions in cerium in shock-wave experiments

    Directory of Open Access Journals (Sweden)

    Zhernokletov M.V.

    2015-01-01

    Full Text Available Cerium has a complex phase diagram that is explained by the presence of structure phase transitions. Planar gauges were used in various combinations in experiments for determination of sound velocity dependence on pressure in cerium by the technique of PVDF gauge. The data of time dependence on pressure profiles with use of x(t diagrams and the D(u relation for cerium allowed the definition of the Lagrangian velocity of the unloading wave CLagr and the Eulerian velocity CEul by taking into account the compression σ. These results accords with data obtained by using the technique of VISAR and a manganin-based gauge, and calculated pressure dependence of isentropic sound velocity according to the VNIITF EOS. Metallography analysis of post-experimental samples did not find any changes in a phase composition.

  18. Excitation induced spectroscopic study and quenching effect in cerium samarium codoped lithium aluminoborate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Parvinder; Kaur, Simranpreet [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Singh, Gurinder Pal [Department of Physics, Khalsa College, Amritsar 143002 (India); Arora, Deepawali; Kumar, Sunil [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Singh, D.P., E-mail: dpsinghdr@yahoo.com [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

    2016-08-15

    Lithium aluminium borate host has been codoped with cerium and samarium to prepare glass by conventional melt quench technique. Their structural and spectroscopic investigation has been carried out using XRD, FTIR and density measurements. The UV‐Vis absorption spectra and fluorescence spectra (λ{sub exc}.=380 nm and 400 nm) have been studied for spectroscopic analysis. The amorphous nature of the prepared samples is shown by XRD. The density is increasing with addition of cerium at the expense of aluminium, keeping other components constant. FTIR study also shows the presence of compact and stable tetrahedral BO{sub 4} units thus supporting the density results. The UV‐ Vis absorption spectra show a shift of optical absorption edge towards longer wavelength along with an increase in intensity of peaks with rising samarium concentration. The fluorescence spectra show a blue shift and subsequent suppression of cerium peaks with addition of samarium.

  19. Self-Correction of Lanthanum-Cerium Halide Gamma Spectra (pre-print)

    Energy Technology Data Exchange (ETDEWEB)

    Ding Yuan, Paul Guss, and Sanjoy Mukhopadhyay

    2009-04-01

    Lanthanum-cerium halide detectors generally exhibit superior energy resolutions for gamma radiation detection compared with conventional sodium iodide detectors. However, they are also subject to self-activities due to lanthanum-138 decay and contamination due to beta decay in the low-energy region and alpha decay in the high-energy region. The detector’s self-activity and crystal contamination jointly contribute a significant amount of uncertainties to the gamma spectral measurement and affect the precision of the nuclide identification process. This paper demonstrates a self-correction procedure for self-activity and contamination reduction from spectra collected by lanthanum-cerium halide detectors. It can be implemented as an automatic self-correction module for the future gamma radiation detector made of lanthanum-cerium halide crystals.

  20. Experimental Investigations on the Effects of Cerium Oxide Nanoparticle Fuel Additives on Biodiesel

    Directory of Open Access Journals (Sweden)

    V. Sajith

    2010-01-01

    Full Text Available This paper reports the results of experimental investigations on the influence of the addition of cerium oxide in the nanoparticle form on the major physicochemical properties and the performance of biodiesel. The physicochemical properties of the base fuel and the modified fuel formed by dispersing the catalyst nanoparticles by ultrasonic agitation are measured using ASTM standard test methods. The effects of the additive nanoparticles on the individual fuel properties, the engine performance, and emissions are studied, and the dosing level of the additive is optimized. Comparisons of the performance of the fuel with and without the additive are also presented. The flash point and the viscosity of biodiesel were found to increase with the inclusion of the cerium oxide nanoparticles. The emission levels of hydrocarbon and NOx are appreciably reduced with the addition of cerium oxide nanoparticles.

  1. Fabrication of Cerium Oxide and Uranium Oxide Microspheres for Space Nuclear Power Applications

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey A. Katalenich; Michael R. Hartman; Robert C. O' Brien

    2013-02-01

    Cerium oxide and uranium oxide microspheres are being produced via an internal gelation sol-gel method to investigate alternative fabrication routes for space nuclear fuels. Depleted uranium and non-radioactive cerium are being utilized as surrogates for plutonium-238 (Pu-238) used in radioisotope thermoelectric generators and for enriched uranium required by nuclear thermal rockets. While current methods used to produce Pu-238 fuels at Los Alamos National Laboratory (LANL) involve the generation of fine powders that pose a respiratory hazard and have a propensity to contaminate glove boxes, the sol-gel route allows for the generation of oxide microsphere fuels through an aqueous route. The sol-gel method does not generate fine powders and may require fewer processing steps than the LANL method with less operator handling. High-quality cerium dioxide microspheres have been fabricated in the desired size range and equipment is being prepared to establish a uranium dioxide microsphere production capability.

  2. Synthesis, spectral characterization and antihaemostatic activity of 1,2,4-triazoles incorporating 1,2,4-triazine rings

    Indian Academy of Sciences (India)

    Ravindra R Kamble; Belgur S Sudha

    2006-03-01

    A simple and high yielding method for the integration of a 1,2,4-triazole ring with 1,2,4-triazine- 5-one (4a-j) has been developed starting from 3-arylsydnones (1a-d). The structures were proved by their spectral data and screened for antihaemostatic activity.

  3. Exposure of cerium oxide nanoparticles to kidney bean shows disturbance in the plant defense mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, Sanghamitra [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Peralta-Videa, Jose R. [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Bandyopadhyay, Susmita [Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Castillo-Michel, Hiram [European Synchrotron Radiation Facility, B.P. 220-38043 Grenoble, Cedex (France); Hernandez-Viezcas, Jose-Angel [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Sahi, Shivendra [Department of Biology, Western Kentucky University, Bowling Green, KY 42101 (United States); Gardea-Torresdey, Jorge L., E-mail: jgardea@utep.edu [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States)

    2014-08-15

    Graphical abstract: - Highlights: • Kidney bean roots uptake nCeO{sub 2} primarily without biotransformation. • Cerium reached the root vascular tissues through gaps in the Casparian strip. • On longer exposure to high concentration, roots demonstrate stress response. • In leaves, guaiacol peroxidase plays a major role in ROS scavenging. - Abstract: Overwhelming use of engineered nanoparticles demands rapid assessment of their environmental impacts. The transport of cerium oxide nanoparticles (nCeO{sub 2}) in plants and their impact on cellular homeostasis as a function of exposure duration is not well understood. In this study, kidney bean plants were exposed to suspensions of ∼8 ± 1 nm nCeO{sub 2} (62.5 to 500 mg/L) for 15 days in hydroponic conditions. Plant parts were analyzed for cerium accumulation after one, seven, and 15 days of nCeO{sub 2} exposure. The primary indicators of stress like lipid peroxidation, antioxidant enzyme activities, total soluble protein and chlorophyll contents were studied. Cerium in tissues was localized using scanning electron microscopy and synchrotron μ-XRF mapping, and the chemical forms were identified using μ-XANES. In the root epidermis, cerium was primarily shown to exist as nCeO{sub 2}, although a small fraction (12%) was biotransformed to Ce(III) compound. Cerium was found to reach the root vascular tissues and translocate to aerial parts with time. Upon prolonged exposure to 500 mg nCeO{sub 2}/L, the root antioxidant enzyme activities were significantly reduced, simultaneously increasing the root soluble protein by 204%. In addition, leaf's guaiacol peroxidase activity was enhanced with nCeO{sub 2} exposure in order to maintain cellular homeostasis.

  4. Luminescence properties and decay kinetics of nano ZnO powder doped with cerium ions

    Energy Technology Data Exchange (ETDEWEB)

    Panda, Nihar Ranjan, E-mail: nihar@iitbbs.ac.in [Indian Institute of Technology Bhubaneswar, Bhubaneswar 751013, Orissa (India); Acharya, B.S., E-mail: bsacharya1950@gmail.com [Department of Physics, C.V. Raman College of Engineering, Bhubaneswar 752054, Orissa (India); Singh, Th. Basanta [Luminescence Dating Laboratory, Manipur University, Imphal 795003 (India); Gartia, R.K. [Department of Physics, Manipur University, Imphal 795003 (India)

    2013-04-15

    ZnO nanopowders doped with cerium ions (1.2 and 1.5 at. wt.%) were synthesized through soft solution route using ultrasound. Sonication has been found to be an effective way for doping rare earth ions like cerium into ZnO. This was confirmed from energy dispersive analysis of X-rays (EDAX) measurement. Further, optical absorption and photoluminescence (PL) measurements corroborate this finding. X-ray diffraction (XRD) studies show the increase of crystallite size and unit cell volume with doping of cerium ions. Formation of fibrous structure of ZnO:Ce was observed from the transmission electron microscopy (TEM) measurements. Although the structural measurements indicate Ce{sup 4+} ion occupying substitutional site in ZnO, PL and absorption studies confirmed the presence of Ce{sup 3+} ion in the powder. The coexistence of Ce{sup 3+} and Ce{sup 4+} ions has been explained on the basis of conversion of Ce{sup 3+} to Ce{sup 4+} in the oxidizing environment. Thermoluminescence (TL) and photo-stimulated decay of luminescence (PSDL) decay studies give an idea of various trapping levels present in the band gap of ZnO. These traps release electrons during optical stimulation to give bimolecular kinetics in nano ZnO:Ce powders. -- Highlights: ► Sonication: an effective way of incorporation of cerium ions into ZnO. ► Site dependent characteristic emission of cerium. ► Energy transfer from host lattice to cerium ions. ► Mono and bimolecular kinetics of ZnO:Ce.

  5. Homoleptic cerium(III) and cerium(IV) nitroxide complexes: significant stabilization of the 4+ oxidation state.

    Science.gov (United States)

    Bogart, Justin A; Lewis, Andrew J; Medling, Scott A; Piro, Nicholas A; Carroll, Patrick J; Booth, Corwin H; Schelter, Eric J

    2013-10-07

    Electrochemical experiments performed on the complex Ce(IV)[2-((t)BuNO)py]4, where [2-((t)BuNO)py](-) = N-tert-butyl-N-2-pyridylnitroxide, indicate a 2.51 V stabilization of the 4+ oxidation state of Ce compared to [(n)Bu4N]2[Ce(NO3)6] in acetonitrile and a 2.95 V stabilization compared to the standard potential for the ion under aqueous conditions. Density functional theory calculations suggest that this preference for the higher oxidation state is a result of the tetrakis(nitroxide) ligand framework at the Ce cation, which allows for effective electron donation into, and partial covalent overlap with, vacant 4f orbitals with δ symmetry. The results speak to the behavior of CeO2 and related solid solutions in oxygen uptake and transport applications, in particular an inherent local character of bonding that stabilizes the 4+ oxidation state. The results indicate a cerium(IV) complex that has been stabilized to an unprecedented degree through tuning of its ligand-field environment.

  6. A corrosion resistant cerium oxide based coating on aluminum alloy 2024 prepared by brush plating

    Energy Technology Data Exchange (ETDEWEB)

    Tang Junlei; Han Zhongzhi [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zuo Yu, E-mail: zuoy@mail.buct.edu.cn [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Tang Yuming [School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2011-01-15

    Cerium oxide based coatings were prepared on AA2024 Al alloy by brush plating. The characteristic of this technology is that hydrogen peroxide, which usually causes the plating solution to be unstable, is not necessary in the plating electrolyte. The coating showed laminated structures and good adhesive strength with the substrate. X-ray diffraction and X-ray photoelectron spectroscopy analysis showed that the coatings were composed of Ce(III) and Ce(IV) oxides. The brush plated coatings on Al alloys improved corrosion resistance. The influence of plating parameters on structure and corrosion resistance of the cerium oxide based coating was studied.

  7. Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

    Science.gov (United States)

    Kartsonakis, I. A.; Kontogiani, P.; Pappas, G. S.; Kordas, G.

    2013-06-01

    This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 ± 15 and 221 ± 10 nm, respectively, were synthesized using emulsion polymerization and the sol-gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue-black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

  8. Dissociation of outer membrane for Escherichia coli cell caused by cerium nitrate

    Institute of Scientific and Technical Information of China (English)

    陈爱美; 施庆珊; 冯劲; 欧阳友生; 陈仪本; 谭绍早

    2010-01-01

    The biological effect of cerium nitrate on the outer membrane(OM) of Escherichia coli(E.coli) cell was studied,and the antim-icrobial mechanism of rare earth elements was explored.The antimicrobial effect of cerium nitrate on E.coli cell was valued by plate count method,and the morphology change of E.coli cell was observed with scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results showed that the E.coli cell suspension was flocculated when the concentration of Ce(NO3)3?6H2O...

  9. Evaluation of Antiproliferative Potential of Cerium Oxide Nanoparticles on HeLa Human Cervical Tumor Cell

    Directory of Open Access Journals (Sweden)

    Zoriţa Diaconeasa

    2015-05-01

    Full Text Available Cerium oxide nanoparticles (CeO2 nanoparticles as nanomaterials have promising biomedical applications. In this paper, the cytotoxicity induced by CONPs human cervical tumor cells was investigated. Cerium oxide nanoparticles were synthesized using the precipitation method. The nanoparticles were found to inhibit the proliferation of HeLa human cervical tumor cells in a dose dependent manner but did not showed to be cytotoxic as analyzed by MTT assay. The administrated treatment decreased the HeLa cell viability cells from 100% to 65% at the dose of 100 μg/mL.

  10. Cerium: catalytic properties, technological and environmental applications; Cerio: propriedades cataliticas, aplicacoes tecnologicas e ambientais

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Tereza S. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica; Hewer, Thiago L.R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica; Freire, Renato S. [Universidade de Sao Paulo (USP), Cubatao (Brazil). Centro de Capacitacao e Pesquisa em Meio Ambiente]. E-mail: tmartins@if.usp.br

    2007-07-01

    Cerium based-compounds have great importance in a wide range of technological applications, such as: fuel cell devices development; metallurgic processes, petroleum refining; glass and ceramic production. Recently, its catalytic properties have been also explored for environmental applications, especially those to prevent or to control atmospheric and water pollution. Subjects covered in this work include a brief description of the fundaments of cerium catalytic properties and some relevant technological applications. Special attention is given to its photo catalytic activity and its ability to degrade pollutants. Recent results and future prospect about these applications are also evaluated. (author)

  11. Synthesis and characterization of two dimensional metal organic framework of cerium with tetraaza macrocyclic

    Energy Technology Data Exchange (ETDEWEB)

    Bt Safiin, Nurul Atikah; Yarmo, Ambar; Yamin, Bohari M. [School of Chemical Science and Food Technology. Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Darul Ehsan (Malaysia)

    2013-11-27

    A two dimensional metal organic framework containing cerium sufate layers and ethylenediaminium between layers was obtained by refluxing the mixture of cerium sulphate and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7, 14-diene bromide. The complex was characterized by infrared spectroscopy and microelemental analysis. X-ray study showed that the complex adopts eleven coordination environments about the central atom. Thermogravimetric study showed the removal of water molecules at about 70°C followed by a gradual mass loss until the whole structure collapsed at about 400°C.

  12. Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Kartsonakis, I. A., E-mail: ikartsonakis@ims.demokritos.gr; Kontogiani, P.; Pappas, G. S.; Kordas, G. [NCSR ' DEMOKRITOS' , Sol-Gel Laboratory, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems (Greece)

    2013-06-15

    This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 {+-} 15 and 221 {+-} 10 nm, respectively, were synthesized using emulsion polymerization and the sol-gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue-black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

  13. Feasibility of Substituting Cerium-Rich Metal by La-Pr-Ce Alloy in Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    伏思静; 赵平

    2004-01-01

    In magnesium alloy ZM3, using cheap Lanthanum-praseodymium-cerium (LPC) rare earth as a substitute for rich-cerium rare earth was studied. The experimental results show that when the adding amount of LPC is between 2.53% and 3.33%, the tensile strength increases as the adding amount of LPC increases; when the amount of RE is 2.53% and 3.33%, the average tensile strength is 142.35, 153.65 MPa respectively. The results show that LPC rare earth replacing rich Ce rare earth is feasible for the tensile strength of ZM3.

  14. Effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings

    OpenAIRE

    Yu Mei; Liu Yuxing; Liu Jianhua; Li Songmei; Xue Bing; Zhang You; Yin Xiaolin

    2015-01-01

    The present work examines the effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings. The Si–Zr hybrid sol–gel coatings on a 2A12 aluminum substrate were prepared through hydrolysis and condensation of glycidoxypropyl-trimethoxy-silane (GTMS) and zirconium(IV) n-propoxide (TPOZ). Used as inhibitors for corrosion, three types of cerium salts (Ce(NO3)3, CeCl3, and Ce(CH3COO)3) were doped into the sol–gel coatings. Fourier transform infrared (FTIR) and scanning electron ...

  15. Iodine-124: A Promising Positron Emitter for Organic PET Chemistry

    Directory of Open Access Journals (Sweden)

    Lena Koehler

    2010-04-01

    Full Text Available The use of radiopharmaceuticals for molecular imaging of biochemical and physiological processes in vivo has evolved into an important diagnostic tool in modern nuclear medicine and medical research. Positron emission tomography (PET is currently the most sophisticated molecular imaging methodology, mainly due to the unrivalled high sensitivity which allows for the studying of biochemistry in vivo on the molecular level. The most frequently used radionuclides for PET have relatively short half-lives (e.g. 11C: 20.4 min; 18F: 109.8 min which may limit both the synthesis procedures and the time frame of PET studies. Iodine-124 (124I, t1/2 = 4.2 d is an alternative long-lived PET radionuclide attracting increasing interest for long term clinical and small animal PET studies. The present review gives a survey on the use of 124I as promising PET radionuclide for molecular imaging. The first part describes the production of 124I. The second part covers basic radiochemistry with 124I focused on the synthesis of 124I-labeled compounds for molecular imaging purposes. The review concludes with a summary and an outlook on the future prospective of using the long-lived positron emitter 124I in the field of organic PET chemistry and molecular imaging.

  16. Iodine-124: a promising positron emitter for organic PET chemistry.

    Science.gov (United States)

    Koehler, Lena; Gagnon, Katherine; McQuarrie, Steve; Wuest, Frank

    2010-04-13

    The use of radiopharmaceuticals for molecular imaging of biochemical and physiological processes in vivo has evolved into an important diagnostic tool in modern nuclear medicine and medical research. Positron emission tomography (PET) is currently the most sophisticated molecular imaging methodology, mainly due to the unrivalled high sensitivity which allows for the studying of biochemistry in vivo on the molecular level. The most frequently used radionuclides for PET have relatively short half-lives (e.g. 11C: 20.4 min; 18F: 109.8 min) which may limit both the synthesis procedures and the time frame of PET studies. Iodine-124 (124I, t1/2 = 4.2 d) is an alternative long-lived PET radionuclide attracting increasing interest for long term clinical and small animal PET studies. The present review gives a survey on the use of 124I as promising PET radionuclide for molecular imaging. The first part describes the production of 124I. The second part covers basic radiochemistry with 124I focused on the synthesis of 124I-labeled compounds for molecular imaging purposes. The review concludes with a summary and an outlook on the future prospective of using the long-lived positron emitter 124I in the field of organic PET chemistry and molecular imaging.

  17. Effects of Cerium Oxide Nanoparticles on Sorghum Plant Traits

    Science.gov (United States)

    Mu, L.; Chen, Y.; Darnault, C. J. G.; Rauh, B.; Kresovich, S.; Korte, C.

    2015-12-01

    Nanotechnology and nanomaterials are considered as the development of the modern science. However, besides with that wide application, nanoparticles arouse to the side effects on the environment and human health. As the catalyst of ceramics and fuel industry, Cerium (IV) oxide nanoparticles (CeO2 NPs) can be found in the environment following their use and life-cycle. Therefore, it is critical to assess the potential effects that CeO2 NPs found in soils may have on plants. In this study, CeO2 NPs were analyzed for the potential influence on the sorghum [Sorghum bicolor (L.) Moench] (Reg. no. 126) (PI 154844) growth and traits. The objectives of this research were to determine whether CeO2 NPs impact the sorghum germination and growth characteristics. The sorghum was grown in the greenhouse located at Biosystems Research Complex, Clemson University under different CeO2 NPs treatments (0mg; 100mg; 500mg; 1000mg CeO2 NPs/Kg soil) and harvested around each month. At the end of the each growing period, above ground vegetative tissue was air-dried, ground to 2mm particle size and compositional traits estimated using near-infrared spectroscopy. Also, the NPK value of the sorghum tissue was tested by Clemson Agriculture Center. After the first harvest, the result showed that the height of above ground biomass under the nanoparticles stress was higher than that of control group. This difference between the control and the nanoparticles treatments was significant (F>F0.05; LSD). Our results also indicated that some of the compositional traits were impacted by the different treatments, including the presence and/or concentrations of the nanoparticles.

  18. Cerium-based conversion coatings on magnesium alloys

    Science.gov (United States)

    Castano Londono, Carlos Eduardo

    This research is primarily focused on gaining a better understanding of the deposition and corrosion behavior of cerium-based conversion coatings (CeCCs) on AZ31B and AZ91D Mg alloys. Deposition of homogenous and protective CeCCs was highly dependent on the surface preparation steps. The best results were obtained when Mg samples underwent grinding, acid cleaning, and alkaline cleaning processes. This reduced the number of active cathodic sites and promoted the formation of a protective Al-rich Mg oxide/hydroxide layer. Electrochemical properties of the CeCCs were also strongly correlated with morphological, microstructural, and chemical characteristics. Protective CeCCs were deposited on both AZ31 and AZ91 Mg alloys using a range of deposition times (5 to 180 s) and temperatures (10 to 80 °C). However, shorter deposition times (5 s) and lower deposition temperatures (~10 °C) showed higher impedance and longer bath stability than other deposition conditions. The increase in impedance was related with fewer cracks and smaller nodule sizes. Additional investigations of post-treated CeCCs exposed to NaCl environments showed an increased in the total impedance. The increase in corrosion protection of the CeCCs was associated with an overall increase in coating thickness from 400 to 800 nm. A microstructural evolution from ~3 nm nodular nanocrystals of CeO2/CePO4*H2O embedded in an amorphous matrix to >50 nm CePO4*H2O nanocrystals was responsible for the electrochemically active corrosion protection. Exposure of CeCCs to sunlight in humid environments promoted the reduction of Ce(IV) into Ce(III) species compared to unexposed coatings. This reduction process was related with photocatalytic water oxidation reaction.

  19. Fate of cerium dioxide nanoparticles in endothelial cells: exocytosis

    Energy Technology Data Exchange (ETDEWEB)

    Strobel, Claudia, E-mail: Claudia.Strobel@med.uni-jena.de [Jena University Hospital – Friedrich Schiller University Jena, Department of Experimental Radiology, Institute of Diagnostic and Interventional Radiology (Germany); Oehring, Hartmut [Jena University Hospital – Friedrich Schiller University Jena, Institute of Anatomy II (Germany); Herrmann, Rudolf [University of Augsburg, Department of Physics (Germany); Förster, Martin [Jena University Hospital – Friedrich Schiller University Jena, Department of Internal Medicine I, Division of Pulmonary Medicine and Allergy/Immunology (Germany); Reller, Armin [University of Augsburg, Department of Physics (Germany); Hilger, Ingrid, E-mail: ingrid.hilger@med.uni-jena.de [Jena University Hospital – Friedrich Schiller University Jena, Department of Experimental Radiology, Institute of Diagnostic and Interventional Radiology (Germany)

    2015-05-15

    Although cytotoxicity and endocytosis of nanoparticles have been the subject of numerous studies, investigations regarding exocytosis as an important mechanism to reduce intracellular nanoparticle accumulation are rather rare and there is a distinct lack of knowledge. The current study investigated the behavior of human microvascular endothelial cells to exocytose cerium dioxide (CeO{sub 2}) nanoparticles (18.8 nm) by utilization of specific inhibitors [brefeldin A; nocodazole; methyl-β-cyclodextrin (MβcD)] and different analytical methods (flow cytometry, transmission electron microscopy, inductively coupled plasma mass spectrometry). Overall, it was found that endothelial cells were able to release CeO{sub 2} nanoparticles via exocytosis after the migration of nanoparticle containing endosomes toward the plasma membrane. The exocytosis process occurred mainly by fusion of vesicular membranes with plasma membrane resulting in the discharge of vesicular content to extracellular environment. Nevertheless, it seems to be likely that nanoparticles present in the cytosol could leave the cells in a direct manner. MβcD treatment led to the strongest inhibition of the nanoparticle exocytosis indicating a significant role of the plasma membrane cholesterol content in the exocytosis process. Brefeldin A (inhibitor of Golgi-to-cell-surface-transport) caused a higher inhibitory effect on exocytosis than nocodazole (inhibitor of microtubules). Thus, the transfer from distal Golgi compartments to the cell surface influenced the exocytosis process of the CeO{sub 2} nanoparticles more than the microtubule-associated transport. In conclusion, endothelial cells, which came in contact with nanoparticles, e.g., after intravenously applied nano-based drugs, can regulate their intracellular nanoparticle amount, which is necessary to avoid adverse nanoparticle effects on cells.

  20. Thermoluminescence of cerium and terbium -doped calcium pyrophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Roman L, J.; Cruz Z, E. [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Lozano R, I. B.; Diaz G, J. A. I., E-mail: jesus.roman@nucleares.unam.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria No. 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    The aim of this work is to report the thermoluminescence (Tl) response of Calcium Pyrophosphate phosphor doped with Cerium and Terbium impurities (Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+}). The phosphors were synthesized using the co-precipitation method and annealed at 900 degrees C by two hours for obtain the β phase. The intentional doping with Ce and Tb ions was 1 at.% and 0.1 at.%, whereas in the EDS results the concentration of impurities was 0.39 at.% and 0.05 at.%, respectively. The superficial morphology of phosphor is mainly composed by thin wafers of different size. All samples were exposed to gamma rays from {sup 60}Co in the Gammacell-200 irradiator. The Tl response of the phosphor was measured from Rt up to 350 degrees C and under nitrogen atmosphere in a Harshaw TLD 3500 reader. The glow curves of the Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} powders showed a broad intense Tl peak centered at 165 degrees C and a shoulder at approximate 260 degrees C was observed. A linear Tl response in the range of absorbed dose of 0.2 to 10 Gy was obtained. Tl glow curves were analyzed using the initial rise (IR)and computerized glow curve deconvolution methods to evaluate the kinetics parameters such as activation energy (E), frequency factor (s) and kinetic order (b). (Author)

  1. Variations in Reactivity on Different Crystallographic Orientations of Cerium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Mullins, David R [ORNL; Albrecht, Peter M [ORNL; Calaza, Florencia C [ORNL

    2013-01-01

    Cerium oxide is a principal component in many heterogeneous catalytic processes. One of its key characteristics is the ability to provide or remove oxygen in chemical reactions. The different crystallographic faces of ceria present significantly different surface structures and compositions that may alter the catalytic reactivity. The structure and composition determine the number of coordination vacancies surrounding surface atoms, the availability of adsorption sites, the spacing between adsorption sites and the ability to remove O from the surface. To investigate the role of surface orientation on reactivity, CeO2 films were grown with two different orientations. CeO2(100) films were grown ex situ by pulsed laser deposition on Nb-doped SrTiO3(100). CeO2(111) films were grown in situ by thermal deposition of Ce metal onto Ru(0001) in an oxygen atmosphere. The chemical reactivity was characterized by the adsorption and decomposition of various molecules such as alcohols, aldehydes and organic acids. In general the CeO2(100) surface was found to be more active, i.e. molecules adsorbed more readily and reacted to form new products, especially on a fully oxidized substrate. However the CeO2(100) surface was less selective with a greater propensity to produce CO, CO2 and water as products. The differences in chemical reactivity are discussed in light of possible structural terminations of the two surfaces. Recently nanocubes and nano-octahedra have been synthesized that display CeO2(100) and CeO2(111) faces, respectively. These nanoparticles enable us to correlate reactions on high surface area model catalysts at atmospheric pressure with model single crystal films in a UHV environment.

  2. Ditching Investigation of a 1/24-Scale Model of the Douglas C-124 Airplane

    Science.gov (United States)

    Fisher, Lloyd J.; Windham, John O.

    1951-01-01

    An investigation of a 1/24- scale dynamically similar model of the Douglas C-124 airplane was made to determine the ditching characteristics and proper technique for ditching the airplane. Various conditions of damage, landing attitude, flap setting, and speed were investigated. The behavior of the model was determined from visual observations, motion- picture records, and time-history deceleration records. The results of the investigation are presented in table form, photographs, and curves. It was concluded on the basis of results from model tests with scale-strength bottoms (equivalent to 1150 pounds per square foot, full scale) that the airplane should be ditched at a medium nose-high landing attitude (near 7deg) with flaps full down. The airplane will probably make a smooth run with considerable damage resulting to the fuselage bottom just forward of the wing, but it is not likely that the water inflow will be overwhelming to personnel provided they are not in the belly compartment. Longitudinal decelerations in calm water will be about 2 1/2g and the landing run will be about four fuselage lengths.

  3. 124Te and the E(5) Critical Point Symmetry

    Science.gov (United States)

    Ghiţă, D. G.; Căta-Danil, G.; Bucurescu, D.; Căta-Danil, I.; Ivascu, M.; Mihai, C.; Suliman, G.; Stroe, L.; Sava, T.; Zamfir, N. V.

    We present a new study of the low-lying states in 124Te nucleus by γ-ray spectroscopy following 124I β+/ɛ decay. The β radioactive sources were produced in the 124Te(p, n)124I reaction induced by 11 MeV protons, delivered by the Bucharest FN Tandem Accelerator. The γ-rays were measured in a low background area with three large volume HPGe detectors. A total number of 276 milion double coincidence events were recorded in a six-day run. Most of the gamma line intensities previously measured were confirmed with improved accuracy and several gamma lines were obtained for the first time. Our results, combined with those from a recent (n, γ) study are compared with the predictions of the E(5) critical point symmetry model and numerical IBA-1 model calculations at the critical point of the U(5)-O(6) phase transition.

  4. Structural and electrochemical studies on the utilization of Cerium (Ce3+ as an additive for nickel hydroxide electrode

    Directory of Open Access Journals (Sweden)

    Marcio Vidotti

    2007-03-01

    Full Text Available This paper describes electrochemical and spectroscopic studies on the utilization of cerium atoms as additives for nickel hydroxide electrodes. Thin films were galvanostatically grown with different amounts of cerium and mixed electrodes were studied by electrochemical measurements and the spectroscopic technique. The electrochromic behavior was investigated by “in situ” experiments , while the amount of species was determined by ICP-OES. The addition of cerium to nickel hydroxide electrodes increases durability, due to modifications in the structural properties, as seen by Raman spectras.

  5. Effects of Cerium on Alloy Elements Distribution in Ferrous Matrix Material

    Institute of Scientific and Technical Information of China (English)

    刘英才; 刘俊友; 尹衍生; 刘国权

    2001-01-01

    The effect of the addition of rare earths in Fe-based high chromium alloy powders on elements distribution in matrix materials and mechanical properties were studied. The results show that the addition of cerium can increase the chromium amount in carbonides and increase the micro-hardness after carbonization and the wear-resistant property of materials.

  6. Growth and characterization of Sm3+ doped cerium oxalate single crystals

    Directory of Open Access Journals (Sweden)

    Minu Mary C

    2016-07-01

    Full Text Available Single crystals of Sm3+ doped cerium oxalate decahydrate were synthesized using single diffusion gel technique and the conditions influencing the size, morphology, nucleation density and quality of the crystals were optimized. Highly transparent single crystals of average size 3 mm × 2 mm × 1 mm with well-defined hexagonal morphology were grown during a time period of two weeks. X-ray powder diffraction analysis revealed that the grown crystals crystallize in the monoclinic system with space group P21/c as identical with the pure cerium oxalate. The various functional groups of the oxalate ligand and the water of crystallization were identified by Fourier transform infrared spectroscopy. The photoluminescence spectrum of the Sm3+ doped cerium oxalate indicated that the Sm3+ ions are optically active in the cerium oxalate matrix. The crystal has a strong and efficient orange red emission with a wavelength peak at 595 nm and hence can be effectively used for optical amplification. Microhardness measurements of the crystal revealed that they belong to the soft material category.

  7. Transient Dynamics of Fluoride-Based High Concentration Erbium/Cerium Co-Doped Fiber Amplifier

    Institute of Scientific and Technical Information of China (English)

    S. S-H. Yam; Y. Akasaka; Y. Kubota; R. Huang; D. L. Harris; J. Pan

    2003-01-01

    We designed and evaluated a fluoride-based high concentration erbium/ cerium co-doped fiber amplifier. It is suitable for Metropolitan Area Networks due to faster transient, flatter (unfiltered) gain, smaller footprint and gain excursion than its silica-based counterpart.

  8. Characteristics of cerium-gadolinium oxide (CGO) suspensions as a function of dispersant and powder properties

    DEFF Research Database (Denmark)

    Phair, John; Lönnroth, Nadja; Lundberg, Mats;

    2009-01-01

    A series of concentrated suspensions ( = 0.18–0.34) of cerium-gadolinium oxide (CGO) in terpineol were prepared as a function of dispersant, powder surface area and solids concentration. The stability of the suspensions was assessed by rheological measurements including viscosity and oscillatory...

  9. Phenotypic and genomic responses to titanium dioxide and cerium oxide nanoparticles in Arabidopsis germinants

    Science.gov (United States)

    The effects of exposure to two nanoparticles (NPs) -titanium dioxide (nano-titania) and cerium oxide (nano-ceria) at 500 mg NPs L-1 on gene expression and growth in Arabidopsis thaliana germinants were studied using microarrays and phenotype studies. After 12 days post treatment,...

  10. Cerium (IV) oxide nanotubes prepared by low temperature deposition at normal pressure

    Energy Technology Data Exchange (ETDEWEB)

    Boehme, M; Fu, G; Ionescu, E; Ensinger, W, E-mail: mboehme@ca.tu-darmstadt.de [Department of Materials Science, Darmstadt University of Technology, D-64287 Darmstadt (Germany)

    2011-02-11

    This paper reports the synthesis of cerium dioxide nanotubes (CeNTs) by electroless deposition using ion-track-etched polycarbonate templates. To achieve nanotubes with thin walls and small surface roughness the tubes were generated by a several-step-containing procedure under aqueous conditions. The approach reported below will process open end nanotubes with well-defined outer diameter and wall thickness.

  11. Cerium (IV) oxide nanotubes prepared by low temperature deposition at normal pressure.

    Science.gov (United States)

    Boehme, M; Fu, G; Ionescu, E; Ensinger, W

    2011-02-11

    This paper reports the synthesis of cerium dioxide nanotubes (CeNTs) by electroless deposition using ion-track-etched polycarbonate templates. To achieve nanotubes with thin walls and small surface roughness the tubes were generated by a several-step-containing procedure under aqueous conditions. The approach reported below will process open end nanotubes with well-defined outer diameter and wall thickness.

  12. Growth and characterization of cerium lanthanum oxalate crystals grown in hydro-silica gel

    Energy Technology Data Exchange (ETDEWEB)

    John, M.V.; Ittyachen, M.A. [Mahatma Gandhi Univ., Kerala (India). School of Pure and Applied Physics

    2001-07-01

    Single crystals of mixed cerium lanthanum oxalate (CLO) are grown by gel method. Over the hydrosilica gel prepared by mixing oxalic acid and sodium meta silicate, a mixture of aqueous solutions of cerium nitrate and lanthanum nitrate are poured gently. Cerium and lanthanum ions diffuse into the gel and react with oxalic acid to give colorless, transparent cerium lanthanum oxalate crystals with in a few days. Different growth parameters give crystals of various dimensions. Infrared (IR) spectrum confirms the presence of water molecules and carboxylic acid. X-ray diffraction (XRD) pattern of these samples reveals the crystalline nature. Diffraction peaks are indexed. Unit cell parameters are determined. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) data support the presence of 9 H{sub 2}O molecules attached to the CLO crystal lattice which are lost around 200 C as revealed by the endotherm record. Exothermic peak around 350 C-425 C shows the release of CO and CO{sub 2}. Elemental analysis done by energy dispersive X-ray fluorescence analysis (EDXRF) for the mixed rare earth compound is almost in good agreement with experimental and theoretical values. (orig.)

  13. Release of cerium dibutylphosphate corrosion inhibitors from highly filled epoxy coating systems

    NARCIS (Netherlands)

    Soestbergen, M. van; Baukh, V.; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2014-01-01

    Carcinogenic chromates are phased out as corrosion inhibitors in organic coatings, and are replaced by benign alternatives. Cerium-based compounds are excellent corrosion inhibitors in an aqueous environment. However, whether they are effective as corrosion inhibitor in an organic coating also depen

  14. 1,2,4-triazine derivatives: Synthesis and biological applications

    Directory of Open Access Journals (Sweden)

    Mohammad Arshad

    2014-04-01

    Full Text Available 1,2,4-Triazines are the six membered heterocyclic compounds possessing three nitrogen in its structure with general formula C3H3N3. 1,2,4-Triazines and its derivatives have been found to exhibit the variety of biological applications such as antifungal, anti-HIV, anticancer, antiinflammatory, analgesic and antihypertensive, cardiotonic, neuroleptic, nootropic, antihistaminergic, tuberculostatic, antiviral, anti-protozoal, estrogen receptor modulators, antimalarial, cyclin-dependent kinase inhibitors, antimicrobial and antiparasitic activities.

  15. 4d → 4f resonance in photoabsorption of cerium ion Ce3+ and endohedral cerium in fullerene complex {\\rm{Ce}}@{{{\\rm{C}}}_{82}}^{+}

    Science.gov (United States)

    Schrange-Kashenock, G.

    2016-09-01

    The theoretical investigation of the single-photoionization spectra in the 4d-resonance region (120-150 eV) for the ionic cerium Ce3+ and cerium in the endohedral complex {{Ce}}@{{{{C}}}82}+ (in practice, {{{Ce}}}3+@{{{{C}}}82}2-) is presented. The fullerene cage is modeled by ab initio spherical jellium shell with an accurate account for the real distribution of carbon electron density. The oscillator strengths are calculated within the multiconfiguration Dirac-Fock (MCDF) approach for phototransitions from the outermost shells of the ion Ce3+ with and without the influence of the potential generated by a fullerene cage. It is shown that the integrated oscillator strengths have the main contribution from the Ce3+ 4d → 4f (ten possible from the phototransitions {}2F{7/2,5/2}\\to {}2D{3/2,5/2},{}2F{5/2,7/2},{}2G{5/2,7/2}) resonance photoexcitations. The corresponding precise MCDF values for the oscillator strengths and the transition energies are presented for the first time. It is demonstrated that the resonance {f}4d\\to 4f oscillator strengths are slightly affected by the presence of the cage potential, despite the fact that the spectral levels structure is changed when the effect of this potential is included. The Auger 4d -1 decay from the cerium free ion Ce3+ and the encapsulated endohedral ion Ce3+@ are considered within the two-step model and the corresponding Lorentzian profiles are presented. This model clearly reveals the correspondence of the complex resonance profile in the Ce3+ photoabsorption to the fine structure of ion energy levels. The smoothing of the resonance profile in the photoabsorption of the endohedral system {{Ce}}@{{{{C}}}82}+ compared with the free ion Ce3+ is attributed to increasing the linewidths of the Auger transitions. This increase is estimated from the relevant experiment (Müller et al 2008 Phys. Rev. Lett. 101 133001) to be strong; as at least three times the value for an isolated ion. The presence of the confining fullerene

  16. Effect of cerium substitution on structural and magnetic properties of magnetite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Padalia, Diwakar, E-mail: Padalia.diwakar@gmail.com [Department of Physics, G.B.Pant University of Agriculture & Technology, Pantnagar, Uttrakhand (India); Johri, U.C. [Department of Physics, G.B.Pant University of Agriculture & Technology, Pantnagar, Uttrakhand (India); Zaidi, M.G.H. [Supercritical Fluid Processing Laboratory, Department of Chemistry, G.B.Pant University of Agriculture & Technology, Pantnagar, Uttrakhand (India)

    2016-02-01

    The current work presents the synthesis and properties of cerium doped magnetite (Fe{sub 3}O{sub 4}) nanoparticles synthesized by standard chemical co-precipitation method using NH{sub 4}OH as co-precipitating agent. The effects of cerium ion substitution on structural and magnetic properties of magnetite (Fe{sub 3}O{sub 4}) nanoparticles were reported. These materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). The cerium content has a significant influence on structural and magnetic properties. The X-ray diffraction study confirmed the formation of single-phase magnetite with space group Fd3m and crystallite size ranging from 39 to 58 nm. The addition of cerium resulted in a reduction of crystallite size and an increase of cell parameters. FTIR measurements confirmed the formation of different samples and suggested that the reduction of Fe{sup +3} to Fe{sup +2} preferred on a site adjacent to Ce{sup +4}. Magnetic measurements revealed that the saturation magnetization (Ms) and remanence (M{sub r}) decreased while the coercivity (H{sub C}) and squareness (M{sub r}/M{sub S}) increased with increasing cerium content. - Highlights: • There is an increase in cell parameters and strain with Ce-content. • Samples show the presence of secondary phase after 1.0% doping level. • Ce-ions prefer octahedral sites and charge neutrality is accompanied by Fe{sup +3} → Fe{sup +2}. • Magnetization decreases due to weakening of the super exchange interactions. • Squareness and coercivity start to increase with Ce content.

  17. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Surbhi [Department of Physics and Astrophysics, University of Delhi (India); Tomar, Monika [Physics Department, Miranda House, University of Delhi (India); Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi (India)

    2015-03-15

    The influence of Cerium doping on the structural and magnetic properties of BiFeO{sub 3} thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi{sub 1−x}Ce{sub x}FeO{sub 3} (BCFO) thin films with x=0–0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x≥0.08. All low wavenumber Raman modes (<300 cm{sup −1}) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm{sup −1}), shows a minor shift. Sudden evolution of Raman mode at 668 cm{sup −1}, manifested as A{sub 1}-tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M–H) hysteresis curves with improved saturation magnetization (M{sub s}) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi{sub 0.88}Ce{sub 0.12}FeO{sub 3} thin film found to exhibit better magnetic properties with M{sub s}=15.9 emu/g without any impure phase. - Highlights: • Synthesis of single phase Bi{sub 1−x}Ce{sub x}FeO{sub 3} thin films with (x=0–0.2) on cost effective corning glass and silicon substrates using CSD technique. • Structural modification studies using Rietveld refinement of XRD and de-convolution of Raman spectra revealed partial phase transition from rhombohedral (R3c) to tetragonal (P4mm) phase. • Possible reasons for origin of pinched magnetic behavior of BCFO thin films are identified. • Contribution of both hard and soft magnetic phase in coercivity of BCFO thin films is calculated and practical

  18. Convenient synthesis of substituted pyrroles via a cerium (IV ammonium nitrate (CAN-catalyzed Paal–Knorr reaction

    Directory of Open Access Journals (Sweden)

    Ahmed Kamal

    2016-07-01

    Full Text Available A screening of various cerium salts for promoting the Paal–Knorr pyrrole synthesis revealed the superiority of cerium (IV ammonium nitrate (CAN as a catalyst. Excellent yields of substituted pyrroles were obtained in CAN-catalyzed Paal–Knorr reactions of 1,4-diketones with various amines. The protocol is noteworthy for the mild reaction condition, short reaction times, scalability and easy isolation of products and high yields of the products.

  19. Study of gels of molybdenum with cerium in the preparation of generators of 99Mo - 99mTc

    OpenAIRE

    Vanessa Moraes; Bárbara Marczewski; Carla Roberta Dias; João Alberto Osso Junior

    2005-01-01

    99mTc has ideal nuclear properties for organ imaging in nuclear medicine, and it is obtained from the 99Mo-99mTc generator. Four different types of generators are available: chromatographic that uses 99Mo from fission of uranium; MEK solvent extraction; Tc2O7 sublimation; gel chromatographic. This work presents the preparation of gel generators of molybdenum with cerium and characterization of the gels: mass ratio between molybdenum and cerium, structure, size of particles and elution percent...

  20. Chromatographic separation of cerium(Ⅲ) in L-valine medium using poly[dibenzo-18-crown-6

    Institute of Scientific and Technical Information of China (English)

    SABALE Sandip R; MOHITE Baburao S

    2009-01-01

    A column chromatographic method has been developed for the separation and determination of cerium(Ⅲ) using poly[dibenzo-18-crown-6]. The separation was carried out in L-valine medium. The adsorption of cerium(Ⅲ) was quantitative from 1×10-1 to 1×10-4 mol/L L-valine. Amongst the various eluents, 1.0-8.0 mol/L hydrochloric acid, 1.0-8.0 mol/L hydrobromic acid, 1.0-8.0 mol/L perchloric acid, 1.0-2.0 mol/L sulfuric acid and 4.0-5.0 mol/L acetic acid, were found to be the efficient eluents for cerium(Ⅲ). The capacity of poly[dibenzo-18-crown-6] for cerium(Ⅲ) was (0.428±0.01) mmol/g. The method was applied to the separation of cerium(Ⅲ) from associated elements link uranium(Ⅵ) and thorium(Ⅳ). It was also applied for the determination of cerium(Ⅲ) in geological samples. The method is simple, rapid and selective with good reproducibility (approximately±2% ).

  1. Structure Analysis of Oxidation Film of Ignition-Inhibition AZ91D Ma gnesium Alloy Added with Cerium

    Institute of Scientific and Technical Information of China (English)

    黄晓锋; 周宏; 何镇明

    2003-01-01

    The effect of cerium on ignition temperature of AZ91D magnesium alloy was studied. By the addition of cerium of 1%, the ignition temperature is raised by 180 ℃, so the magnesium alloy added with cerium can be melted in air. The burning temperature increases with the increasing of cerium. The structure and chemical compositions of the surface oxide film were investigated by XRD and Auger electron spectrometry(AES). The results of XRD indicate that the oxide film of the surface of ignition-inhibition magnesium alloy can change from loose structure of simple magnesia to compact composite structure consisting of magnesia, cerium oxide, Mg17 A112 and aluminum oxide, which has excellent ignition-inhibition effect. AES depth profile analysis shows that the oxide film can be divided into three layers. The outside layer is mainly made up of magnesia, the middle layer, which consists of cerium oxide, magnesia, and aluminum oxide, is compound and compact. Thermodynamic analysis indicates that the structure of the surface oxide film is accordant to the change of free energy and high vapor pressure of magnesium.

  2. Excitation functions of 124Te(d,xn)124,125I reactions from threshold up to 14 MeV: comparative evaluation of nuclear routes for the production of 124I.

    Science.gov (United States)

    Bastian, T H; Coenen, H H; Qaim, S M

    2001-09-01

    Excitation functions of the nuclear reactions 124Te(d,xn)124-125I were measured from their respective thresholds up to 14.0 MeV via the stacked-foil technique. Thin samples were prepared by electrolytic deposition of 99.8% enriched 124Te on Ti-backing. The excitation function of the 124Te(d,n)125I reaction was measured for the first time. The present data for the 124Te(d,2n)124I reaction are by an order of magnitude higher than the literature experimental data but are in good agreement with the results of a hybrid model calculation. From the measured cross sections, integral yields of 124,125I were calculated. The energy range Ed = 14 --> 10 MeV appears to be the best compromise between 124I-yield and 1251-impurity. The calculated 124I-yield amounts to 17.5 MBq/microA h and the 125I-impurity to 1.7%. A critical evaluation of the three nuclear routes for the production of 124I, viz. 124Te(d,2n)-, 124Te(p,n)- and 125Te(p,2n)-processes, is given. The reaction studied in this work proved to be least suitable. The 124Te(p,n)-reaction gives 124I of the highest radionuclidic purity, and a small-sized cyclotron is adequate for production purposes. The 125Te(p,2n)-reaction is more suitable at a medium-sized cyclotron: the yield of 124I is four times higher than in the other two reactions but the level of 0.9% 125I-impurity is relatively high.

  3. Effects of Cerium Nitrate on Expression of CaM Ⅰ and PMCA Ca2+-ATPase mRNA in Rat Liver

    Institute of Scientific and Technical Information of China (English)

    杨维东; 王艇; 刘洁生; 雷衡毅; 杨燕生

    2001-01-01

    The effect of cerium nitrate on expression of CaM Ⅰ and PMCA1b in rat liver was studied by means of reverse transcription-polymerase chain reaction (RT-PCR). The result shows that neither a high dose (50 mg*kg-1) nor a low dose (1 mg*kg-1) of cerium nitrate induces any alterations of expression of CaM Ⅰ and PMCA 1b mRNA after recurrent intraperitoneal injection of cerium nitrate, which suggests that effect of cerium nitrate on CaM and Ca2+-ATPase might be at posttranscription level.

  4. Verification of the ASTM G-124 Purge Equation

    Science.gov (United States)

    Robbins, Katherine E.; Davis, Samuel Eddie

    2009-01-01

    ASTM G-124 seeks to evaluate combustion characteristics of metals in high-purity (greater than 99%) oxygen atmospheres. ASTM G-124 provides the following equation to determine the minimum number of purges required to reach this level of purity in a test chamber: n = -4/log10(Pa/Ph), where "n" is the total number of purge cycles required, Ph is the absolute pressure used for the purge on each cycle and Pa is the atmospheric pressure or the vent pressure. The origin of this equation is not known and has been the source of frequent questions as to its accuracy and reliability. This paper shows the derivation of the G-124 purge equation, and experimentally explores the equation to determine if it accurately predicts the number of cycles required.

  5. Reduction behavior of cerium(Ⅲ) ions in NaCl-2CsCl melt

    Institute of Scientific and Technical Information of China (English)

    QI Xue; ZHU Hongmin

    2005-01-01

    The cathodic process of cerium(Ⅲ) ions in NaCl-2CsCl melt was studied by cyclic voltammetry and square wave voltammetry with tungsten and gold electrodes at 873 K. The two electroanalytical methods yield similar results. The cathodic process of cerium(Ⅲ) ions consists of two reversible steps: Ce3+ + e-= Ce2+ and Ce2+ + 2e-= Ce. The half wave potentials of Ce3+/Ce2+ and Ce2+/Ce were determined as -2.525 V vs. Cl2/Cl- and -2.975 V vs. Cl2/Cl-, respectively. The diffusion coefficient of Ce3+ was also determined as 5.5 × 10-5 cm2·s-1.

  6. Deposition of cerium contained conversion films on LC4 alloy with square wave pulse method

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; LI Jiuqing; WU Yinshun; ZHANG Pei; HE Jianping

    2004-01-01

    Cerium contained conversion films were deposited on LC4 aluminum alloy using square wave pulse (SWP) in a CeC13 solution with KMnO4 as the oxidant. Energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) were adopted to study the composition and the morphology of the film. It is found that the film is composed of Al, Zn, Cu,and small amount of cerium. The polarization curves of the specimens treated with SWP technique measured in 3.5% (mass fraction) NaCl solution reveal that the film thus formed inhibits both the anodic and cathodic process of the corrosion of the specimen. The immersion tests of treated specimens in 3.5% NaCl solution indicate that the corrosion resistance of the SWP treated specimen is better than that of the untreated and is equivalent to or even better than that of the traditionally electrochemically treated specimens.

  7. Color-Fading Spectrophotometric Determination of Cerium with DBC-Arsenazo

    Institute of Scientific and Technical Information of China (English)

    翟庆洲; 张晓霞

    2004-01-01

    In the medium of 0.18~1.08 mol·L-1 sulfuric acid, cerium(Ⅳ) has the color-fading effect on DBC-arsenazo. The apparent molar absorptivity of the color-fading reaction is ε530 nm=1.03×104 L·mol-1·cm-1. Beer′s law is obeyed over the range of 1.20~12.0 μg·ml-1 of Ce (Ⅳ) which shows a linear relationship with the decrease in the absorbance of the colored solution. The effect of thirty-six coexisting ions was studied. The method was applied to the determination of the trace amount of cerium in water samples and has the advantage of high accuracy and good selectivity.

  8. Monte Carlo radiative transfer simulation of a cavity solar reactor for the reduction of cerium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Villafan-Vidales, H.I.; Arancibia-Bulnes, C.A.; Dehesa-Carrasco, U. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Col. Centro, A.P. 34, Temixco, Morelos 62580 (Mexico); Romero-Paredes, H. [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No.186, Col. Vicentina, A.P. 55-534, Mexico D.F 09340 (Mexico)

    2009-01-15

    Radiative heat transfer in a solar thermochemical reactor for the thermal reduction of cerium oxide is simulated with the Monte Carlo method. The directional characteristics and the power distribution of the concentrated solar radiation that enters the cavity is obtained by carrying out a Monte Carlo ray tracing of a paraboloidal concentrator. It is considered that the reactor contains a gas/particle suspension directly exposed to concentrated solar radiation. The suspension is treated as a non-isothermal, non-gray, absorbing, emitting, and anisotropically scattering medium. The transport coefficients of the particles are obtained from Mie-scattering theory by using the optical properties of cerium oxide. From the simulations, the aperture radius and the particle concentration were optimized to match the characteristics of the considered concentrator. (author)

  9. Synthesis, characterization and antimicrobial activity of zinc and cerium co-doped α-zirconium phosphate

    Institute of Scientific and Technical Information of China (English)

    DAI Guangjian; YU Aili; CAI Xiang; SHI Qingshan; OUYANG Yousheng; TAN Shaozao

    2012-01-01

    A series of zinc ions or/and cerium ions co-doped a-zirconium phosphate (Zn-Ce@ZrPs) were prepared.The novel Zn-Ce@ZrPs were characterized and the antibacterial activity on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were tested.The results showed that zinc ions (Zn2+) or/and cerium ions (Ce3+) were combined with ZrP,and the Ce3+ was adsorbed on the surface of ZrP through hydrogen bonds,while Zn2+ intercalated into the interlayer of ZrP.Zn-Ce@ZrPs showed excellent synergistic antibacterial activity.When Zn2+/Ce3+ atomic ratio was 0.6,the Zn-Ce@ZrP3 showed the highest synergistic antibacterial efficiency,suggesting great potential application as antibacterial agents in microbial control.

  10. Synthesis of mesoporous cerium-zirconium mixed oxides by hydrothermal templating method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Mesoporous cerium-zirconium mixed oxides were prepared by hydrothermal method using cetyl trimethyl ammonium bromide (CTAB) as template.The effects of amount of template,pH value of solution and hydrothermal temperature on mesostructure of samples were systematically investigated.The final products were characterized by XRD,TEM,FT-IR,and BET.The results indicate that all the cerium-zirconium mixed oxides present a meso-structure.At molar ratio of n(CTAB)/n((Ce)+(Zr))=0.15,pH value of 9,and hydrothermal temperature of 120 ℃,the samples obtained possess a specific surface area of 207.9 m2/g with pore diameter of 3.70 nm and pore volume of 0.19 cm3/g.

  11. Structure and synergetic antibacterial effect of zinc and cerium carried sodium zirconium phosphates

    Institute of Scientific and Technical Information of China (English)

    YANG Yunhua; DAI Guangjian; TAN Shaozao; LIU Yingliang; SHI Qingshan; OUYANG Yousheng

    2011-01-01

    Zinc and cerium carried zirconium phosphates (Zn-Ce/ZrPs) were prepared by exchanging zinc and cerium cations into sodium zirconium phosphate (NaZrP) through the ion-exchange method and characterized by X-ray diffraction(XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). Furthermore, the specific surface area, zeta potential and antibacterial activity were tested. The results showed that Zn-Ce/ZrPs were with hexagonal crystal system, and the surface area of Zn-Ce/ZrPs increased much more than that of NaZrP. Zn-Ce/ZrPs showed obvious synergetic antibacterial effect, and have the potential to be used as antibacterial agents in environmental control.

  12. Post treatment of silane and cerium salt as chromate replacers on galvanized steel

    Institute of Scientific and Technical Information of China (English)

    KONG Gang; LU Jintang; WU Haijiang

    2009-01-01

    A complex film on hot-dip galvanized steel sheet (HDG) was prepared by immersing the sheet in 0.1wt.% Ce(NO3)3 solution and 5vol.% silane solution in turn. The corrosion protection of the complex film was evaluated by potentiodynamic linear polarization(LPR), electrochemical impendence spectra (EIS) and natural salt spray (NSS) tests and compared with that of single cerium film and silane film. The results showed that, the presence of these films on the zinc coating hindered corrosion reaction by reducing the rate of both anodic and cathodic reaction in the corrosion process, and the corrosion protection of the complex film was much better than that of single cerium film or silane film and closed to that of chromate film, because the polarization resistance Rp and electrochemical impendence were increased markedly. Microstructure and chemical composition of these pretreated films were also investigated by scanning electron microscopy (SEM) and AES.

  13. Effect of oxygen defects on thermal conductivity of thorium-cerium dioxide solid solutions

    Science.gov (United States)

    Muta, Hiroaki; Kado, Hirohisa; Ohishi, Yuji; Kurosaki, Ken; Yamanaka, Shinsuke

    2017-01-01

    Thermal conductivity of thorium-cerium dioxide solid solutions has been measured and analyzed using the relaxation time approximation. Despite the presence of oxygen defects, the partially reduced Th0.8Ce0.2O1.97 exhibited higher thermal conductivity than the stoichiometric one, Th0.8Ce0.2O2.00, showing the same tendency as that previously reported for Th0.7Pu0.3O2-δ. The increase in thermal conductivity with the oxygen defects can be explained by assuming that cerium ions have an average ionic radius of the ionic radii of Ce3+ and Ce4+ in the description of phonon-impurity scattering. This result indicates that the small reduction of (Th,Pu)O2-δ fuel increases the thermal conductivity, especially at high temperatures.

  14. Energy transfer and thermal studies of Pr3+ doped cerium oxalate crystals

    Indian Academy of Sciences (India)

    R Pragash; Gijo Jose; N V Unnikrishnan; C Sudarsanakumar

    2011-07-01

    Energy transfer process at room temperature for cerium (sensitizer) oxalate single crystals doped with different concentrations (10, 13, 15, 17 and 20%) of praseodymium ions (activator) grown by hydro silica gel method has been evaluated. The analysis of energy level diagrams of cerium and praseodymium ions indicates that the energy gap between the sensitizer and the activator ions varies in a small range suggesting a possible energy transfer from the Ce3+ to Pr3+. The emission and absorption spectra of these crystals were recorded. The overlapping of the absorption spectra of Pr3+ and emission spectra of Ce3+ at wavelengths 484 and 478 nm, respectively, strongly supports the possible energy transfer process in this system. From the absorption spectra, oscillator strength, electric dipole moment, branching ratio and Judd–Ofelt parameters of this system were evaluated by least square programming. The quantum efficiency, energy transfer probabilities and thermal properties have been studied.

  15. Thermodynamics of the α -γ transition in cerium studied by an LDA + Gutzwiller method

    Science.gov (United States)

    Tian, Ming-Feng; Song, Hai-Feng; Liu, Hai-Feng; Wang, Cong; Fang, Zhong; Dai, Xi

    2015-03-01

    Utilizing the local-density approximation (LDA) + Gutzwiller method, we have studied the α -γ transition in cerium. Our results indicate that the volume collapse transition between α and γ phases is present at zero temperature with negative pressure. By further providing a newly finite temperature generalization of the LDA + Gutzwiller method (using the mean-field potential approach), the entropy contributed by both electronic quasiparticles and lattice vibration included, we obtain the Gibbs free energy at a given volume and temperature, from which we get the α -γ transition at finite temperature and pressure. Our results indicate that the electronic entropy and lattice vibrational entropy both play important roles in the α -γ transition. We also calculated the equation of state and phase diagram of cerium, finding good agreement with the experiments.

  16. Intensification of electrochemical properties of the molten chloride electrolytes of the cerium subgroup lanthanides

    Science.gov (United States)

    Shabanov, O. M.; Suleymanov, S. I.; Magomedova, A. O.

    2017-01-01

    The electrical conductivity of molten chloride electrolytes of the cerium subgroup lanthanides increases with rising electric field strength and strive to achieve the limiting high voltage values (Wien effect). On exposure of the high-voltage microsecond pulsed fields, the melts are transited into a prolonged non-equilibrium state with increased electrical conductivity and electrolyze current density. During the relaxation processes in non-equilibrium melts, increased electrical conductivity tends to restore the values that are specific to equilibrium systems.

  17. Effect of cerium addition on microstructure and texture of aluminum foil for electrolytic capacitors

    Institute of Scientific and Technical Information of China (English)

    王海燕; 李文学; 任慧平; 黄丽颖; 王向阳

    2010-01-01

    Anode foil of aluminum electrolytic capacitor,which requires large surface area for high capacitance,were prepared by rolling,annealing and electrochemical etching.Effects of cerium addition on the capacitance of aluminum electrolytic capacitors were investigated.Microstructure of the aluminum foil surface was observed by optical microscopy(OM) and scanning electron microscopy(SEM).Electron back scattered diffraction(EBSD) was also employed to reveal texture evolvement of cold-rolled aluminum foil after ann...

  18. Photocatalytic C-C Bond Cleavage and Amination of Cycloalkanols by Cerium(III) Chloride Complex.

    Science.gov (United States)

    Guo, Jing-Jing; Hu, Anhua; Chen, Yilin; Sun, Jianfeng; Tang, Haoming; Zuo, Zhiwei

    2016-12-05

    A general strategy for the cleavage and amination of C-C bonds of cycloalkanols has been achieved through visible-light-induced photoredox catalysis utilizing a cerium(III) chloride complex. This operationally simple methodology has been successfully applied to a wide array of unstrained cyclic alcohols, and represents the first example of catalytic C-C bond cleavage and functionalization of unstrained secondary cycloalkanols.

  19. CO Responses of Sensors Based on Cerium Oxide Thick Films Prepared from Clustered Spherical Nanoparticles

    OpenAIRE

    Woosuck Shin; Takafumi Akamatsu; Toshio Itoh; Ichiro Matsubara; Noriya Izu

    2013-01-01

    Various types of CO sensors based on cerium oxide (ceria) have been reported recently. It has also been reported that the response speed of CO sensors fabricated from porous ceria thick films comprising nanoparticles is extremely high. However, the response value of such sensors is not suitably high. In this study, we investigated methods of improving the response values of CO sensors based on ceria and prepared gas sensors from core-shell ceria polymer hybrid nanoparticles. These hybrid nano...

  20. Nanoceria and bulk cerium oxide effects on the germination of asplenium adiantum-nigrum spores

    Directory of Open Access Journals (Sweden)

    Aranzazu Gomez-Garay

    2016-12-01

    Full Text Available Aim of study: The effect of cerium oxide engineered nanoparticles on the spore germination of the fern. Asplenium adiantum-nigrum. Area of study: France, Britanny Region, Finistére Department, Plougonvelin, in rocks near the sea. Material and methods: Asplenium spores were cultured in vitro on agar medium with Nano-CeO2 (less than 25 nm particle size and bulk-CeO2. The addition of each nano- and bulk particles ranged from 0 to 3000 mg L-1. Observations on rhizoidal and prothallial cells during first stages of gametophyte development were made. The No-Observed-Adverse-Effect concentration (NOAEC and Lowest-Observed-Adverse-Effect-Concentration (LOEC values for spore germination rate data were analyzed.  Main results: Germination was speeded up by 100 to 2000 mg L-1 nanoceria, while bulk cerium oxide had the same effect for 500 to 200 mg L-1 concentrations. Present results showed cellular damage in the protonema while rhizoid cells seemed not to be affected, as growth and membrane integrity remained. Research highlights: Both nanosized and bulk cerium oxide are toxic for the fern Asplenium adiantum-nigrum, although diverse toxicity patterns were shown for both materials. Diverse toxic effects have been observed: chloroplast membrane damage and lysis, cell wall and membrane disruption which leads to cell lysis; and alterations in morphology and development. Keywords: Nanoparticles; rhizoid; prothallus; chloroplast; fern.

  1. Synthesis and Characterization of Cerium Doped Titanium Catalyst for the Degradation of Nitrobenzene Using Visible Light

    Directory of Open Access Journals (Sweden)

    Padmini Ellappan

    2014-01-01

    Full Text Available Cerium doped catalyst was synthesized using Titanium isopropoxide as the Titanium source. The metal doped nanoparticles semiconductor catalyst was prepared by sol-sol method with the sol of Cerium. The synthesized catalyst samples were characterized by powder X-ray diffraction, BET surface area, thermogravimetric analysis (TGA, scanning electron microscopy (SEM, and UV-vis diffuse reflectance measurements (DRS and compared with undoped TiO2 catalyst. The photocatalytic activity of the sample was investigated for the decomposition of nitrobenzene (NB using visible light as the artificial light source. Cerium doped catalyst was found to have better degradation of nitrobenzene owing to its shift in the band gap from UV to visible region as compared to undoped TiO2 catalyst. The operational parameters were optimized with catalyst dosage of 0.1 g L−1, pH of 9, and light intensity of 500 W. The degradation mechanism followed the Langmuir Hinshelwood kinetic model with the rate constant depending nonlinearly on the operational parameters as given by the relationship Kapp (theoretical = 2.29 * 10−4 * Intensity0.584 * Concentration−0.230 * Dosage0.425 * pH0.336.

  2. Cerium(III-Selective Membrane Electrode Based on Dibenzo-24-crown-8 as a Neutral Carrier

    Directory of Open Access Journals (Sweden)

    Susheel K. Mittal

    2010-01-01

    Full Text Available Cerium(III-selective membrane electrodes have been prepared using dibenzo-24-crown-8 (DB24C8 as an electroactive material. A membrane having a composition: DB24C8 (4.5%, plasticizer (NPOE, 62.5% and PVC (33% gives the best performance. It works well over a wide Ce(III ion-concentration range of 1x10-5 M to 1x10-1 M with a Nernstian slope of 19.0 mV/decade and a detection limit of 3x10-5 M. It has a fast response time of 20 seconds and has an average lifetime of four months. The internal solution concentration does not have a significant effect on the response of the electrode except for a change in intercept of the calibration curves. The working pH range for Ce(III solutions (1x10-2 M and 1x10-3 M is 3.5-8.0. The proposed sensor shows a good selectivity for cerium(III with respect to alkali, alkaline earth, some transition and rare earth metal ions that are normally present along with cerium in its ores. The proposed sensor was investigated in partially non-aqueous media using acetone, methanol and DMSO mixtures with water. The electrode was further used as an indicator electrode for the potentiometric titration of Ce(III solution against oxalic acid solution.

  3. Preparation and Characterization of Cerium (III Doped Captopril Nanoparticles and Study of their Photoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Ghamami Shahriar

    2016-01-01

    Full Text Available In this research Ce3+ doped Captopril nanoparticles (Ce3+ doped CAP-NP were prepared by a cold welding process and have been studied. Captopril may be applied in the treatment of hypertension and some types of congestive heart failure and for preventing kidney failure due to high blood pressure and diabetes. CAP-NP was synthesized by a cold welding process. The cerium nitrate was added at a ratio of 10% and the optical properties have been studied by photoluminescence (PL. The synthesized compounds were characterized by Fourier transform infrared spectroscopy. The size of CAP-NP was calculated by X-ray diffraction (XRD. The size of CAP-NP was in the range of 50 nm. Morphology of surface of synthesized nanoparticles was studied by scanning electron microscopy (SEM. Finally the luminescence properties of undoped and doped CAP-NP were compared. PL spectra from undoped CAP-NP show a strong pack in the range of 546 nm after doped cerium ion into the captopril appeared two bands at 680 and 357 nm, which is ascribed to the well-known 5d–4f emission band of the cerium.

  4. Cerium Biomagnification in a Terrestrial Food Chain: Influence of Particle Size and Growth Stage.

    Science.gov (United States)

    Majumdar, Sanghamitra; Trujillo-Reyes, Jesica; Hernandez-Viezcas, Jose A; White, Jason C; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

    2016-07-01

    Mass-flow modeling of engineered nanomaterials (ENMs) indicates that a major fraction of released particles partition into soils and sediments. This has aggravated the risk of contaminating agricultural fields, potentially threatening associated food webs. To assess possible ENM trophic transfer, cerium accumulation from cerium oxide nanoparticles (nano-CeO2) and their bulk equivalent (bulk-CeO2) was investigated in producers and consumers from a terrestrial food chain. Kidney bean plants (Phaseolus vulgaris var. red hawk) grown in soil contaminated with 1000-2000 mg/kg nano-CeO2 or 1000 mg/kg bulk-CeO2 were presented to Mexican bean beetles (Epilachna varivestis), which were then consumed by spined soldier bugs (Podisus maculiventris). Cerium accumulation in plant and insects was independent of particle size. After 36 days of exposure to 1000 mg/kg nano- and bulk-CeO2, roots accumulated 26 and 19 μg/g Ce, respectively, and translocated 1.02 and 1.3 μg/g Ce, respectively, to shoots. The beetle larvae feeding on nano-CeO2 exposed leaves accumulated low levels of Ce since ∼98% of Ce was excreted in contrast to bulk-CeO2. However, in nano-CeO2 exposed adults, Ce in tissues was higher than Ce excreted. Additionally, Ce content in tissues was biomagnified by a factor of 5.3 from the plants to adult beetles and further to bugs.

  5. Controlled Redox Chemistry at Cerium within a Tripodal Nitroxide Ligand Framework.

    Science.gov (United States)

    Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Booth, Corwin H; Schelter, Eric J

    2015-12-01

    Ligand reorganization has been shown to have a profound effect on the outcome of cerium redox chemistry. Through the use of a tethered, tripodal, trianionic nitroxide ligand, [((2-tBuNOH)C6 H4 CH2 )3 N](3-) (TriNOx (3-) ), controlled redox chemistry at cerium was accomplished, and typically reactive complexes of tetravalent cerium were isolated. These included rare cationic complexes [Ce(TriNOx )thf][BAr(F) 4 ], in which Ar(F) =3,5-(CF3 )2 -C6 H3 , and [Ce(TriNOx )py][OTf]. A rare complete Ce-halide series, Ce(TriNOx )X, in which X=F(-) , Cl(-) , Br(-) , I(-) , was also synthesized. The solution chemistry of these complexes was explored through detailed solution-phase electrochemistry and (1) H NMR experiments and showed a unique shift in the ratio of species with inner- and outer-sphere anions with size of the anionic X(-) group. DFT calculations on the series of calculations corroborated the experimental findings.

  6. Cerium, gallium and zinc containing mesoporous bioactive glass coating deposited on titanium alloy

    Science.gov (United States)

    Shruti, S.; Andreatta, F.; Furlani, E.; Marin, E.; Maschio, S.; Fedrizzi, L.

    2016-08-01

    Surface modification is one of the methods for improving the performance of medical implants in biological environment. In this study, cerium, gallium and zinc substituted 80%SiO2-15%CaO-5%P2O5 mesoporous bioactive glass (MBG) in combination with polycaprolactone (PCL) were coated over Ti6Al4 V substrates by dip-coating method in order to obtain an inorganic-organic hybrid coating (MBG-PCL). Structural characterization was performed using XRD, nitrogen adsorption, SEM-EDXS, FTIR. The MBG-PCL coating uniformly covered the substrate with the thickness found to be more than 1 μm. Glass and polymer phases were detected in the coating along with the presence of biologically potent elements cerium, gallium and zinc. In addition, in vitro bioactivity was investigated by soaking the coated samples in simulated body fluid (SBF) for up to 30 days at 37 °C. The apatite-like layer was monitored by FTIR, SEM-EDXS and ICP measurements and it formed in all the samples within 15 days except zinc samples. In this way, an attempt was made to develop a new biomaterial with improved in vitro bioactive response due to bioactive glass coating and good mechanical strength of Ti6Al4 V alloy along with inherent biological properties of cerium, gallium and zinc.

  7. Infrared, thermal and X-ray diffraction analysis of cerium soaps

    Energy Technology Data Exchange (ETDEWEB)

    Mehrotra, K.N. [Agra Univ. (India). Dept. of Chemistry; Chauhan, M. [Agra Univ. (India). Dept. of Chemistry; Shukla, R.K. [R.B.S. Coll., Agra (India)

    1997-03-01

    The physico-chemical characteristics of cerium soaps (Caproate and caprate) in solid state were investigated by IR, thermal and X-ray diffraction measurements. The IR results reveal that the fatty acids exist in dimeric state through hydrogen bonding and soaps possess partial ionic character. The decomposition reaction was found kinetically of zero order with energy of activation 6.7 and 7.3 K cal mol{sup -1} for cerium caproate and caprate, respectively. The X-ray diffraction measurements were used to calculate the long spacings and the results confirm the double layer structure of cerium soaps. (orig.) [Deutsch] Mit Hilfe von IR-, thermischen und Roentgendiffraktionsmessungen wurden die physikalisch-chemischen Eigenschaften von Cerseifen (Capron- und Caprylsaeuresalze)in festem Zustand bestimmt. Die IR-Untersuchungen zeigen, dass die Fettseifen in dimerem Zustand, gebunden durch Wasserstoffbruecken vorliegen und partiell ionischen Charakter haben. Die Zersetzungsreaktion war von einer Kinetik nullter Ordnung, die Aktivierungsenergien lagen bei 6,7 K cal mol{sup -1} fuer Capronsaeuresalze und 7,3 K cal mol{sup -1} fuer Caprylsaeuresalze. Mit Hilfe von Roentgendiffraktionsmessungen wurden die grossen Zwischenraeume bestimmt. Die Ergebnisse lassen auf eine Doppelschichtstruktur der Cerseifen schliessen. (orig.)

  8. Effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings

    Directory of Open Access Journals (Sweden)

    Yu Mei

    2015-04-01

    Full Text Available The present work examines the effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings. The Si–Zr hybrid sol–gel coatings on a 2A12 aluminum substrate were prepared through hydrolysis and condensation of glycidoxypropyl-trimethoxy-silane (GTMS and zirconium(IV n-propoxide (TPOZ. Used as inhibitors for corrosion, three types of cerium salts (Ce(NO33, CeCl3, and Ce(CH3COO3 were doped into the sol–gel coatings. Fourier transform infrared (FTIR and scanning electron microscopy (SEM were employed to investigate the structures and morphologies of various coatings, and the corrosion resistances of the coatings were evaluated by electrochemical methods and neutral salt spray tests. Experimental results indicate that the addition of cerium salts can hinder the process of corrosion due to their self-healing abilities. Furthermore, the sol–gel coating doped with Ce(CH3COO3 has the best corrosion resistance because of the promotions of hydrolysis and condensation provided by CH3COO−.

  9. Chromium VI adsorption on cerium oxide nanoparticles and morphology changes during the process

    Energy Technology Data Exchange (ETDEWEB)

    Recillas, Sonia; Colon, Joan [Department of Chemical Engineering, Engineering School, Autonomous University of Barcelona, 08193 Bellaterra (Spain); Casals, Eudald; Gonzalez, Edgar [Catalan Institute of Nanotechnology, Autonomous University of Barcelona Campus, 08193 Bellaterra (Spain); Puntes, Victor [Catalan Institute of Nanotechnology, Autonomous University of Barcelona Campus, 08193 Bellaterra (Spain); Catalan Institute of Research and Advanced Studies, Passeig Lluis Companys, 23, 08010 Barcelona (Spain); Sanchez, Antoni, E-mail: antoni.sanchez@uab.cat [Department of Chemical Engineering, Engineering School, Autonomous University of Barcelona, 08193 Bellaterra (Spain); Font, Xavier [Department of Chemical Engineering, Engineering School, Autonomous University of Barcelona, 08193 Bellaterra (Spain)

    2010-12-15

    In this study, suspended cerium oxide nanoparticles stabilized with hexamethylenetetramine were used for the removal of dissolved chromium VI in pure water. Several concentrations of adsorbent and adsorbate were tested, trying to cover a large range of possible real conditions. Results showed that the Freundlich isotherm represented well the adsorption equilibrium reached between nanoparticles and chromium, whereas adsorption kinetics could be modeled by a pseudo-second-order expression. The separation of chromium-cerium nanoparticles from the medium and the desorption of chromium using sodium hydroxide without cerium losses was obtained. Nanoparticles agglomeration and morphological changes during the adsorption-desorption process were observed by TEM. Another remarkable result obtained in this study is the low toxicity in the water treated by nanoparticles measured by the Microtox commercial method. These results can be used to propose this treatment sequence for a clean and simple removal of drinking water or wastewater re-use when a high toxicity heavy metal such as chromium VI is the responsible for water pollution.

  10. Effect of cerium oxide addition on electrical properties of ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, D.M. [National Research Center, Dokki, Giza (Egypt). Dept. of Ceramics; Mounir, M. [Dept. of Physics, Cairo Univ., Giza (Egypt); Mahgoub, A.S. [Cairo Univ., Giza (Egypt). Dept. of Chemistry; Turky, G. [Dept. of Physics, National Research Center, Dokki, Giza (Egypt); El-Desouky, O.A. [Cer. Cleopatra Co., Ramadan City (Egypt)

    2002-07-01

    Mixtures of ZnO and Ce{sub 6} O{sub 11} as additive were prepared by solid state reaction from the calcined oxides with the following proportions: 0.03, 0.08, 0.1, 0.2 and 0.4 mole. Disc specimens 1.2 cm 5 cm in diameter and 0.3 cm thickness were processed under a force of 70 kN and fired at 1150 C/ 30 minutes. XRD revealed the presence of limited solid solution of cerium in ZnO, as evident from the shift in the peaks [0.03-0.04 A ] up to 0.1 mole addition and remains constant. SEM revealed the presence of inter-granular phase. EDAX showed it to be a mixture of ZnO and Ce{sub 6}O{sub 11}. Also cerium was detected in the ZnO grains confirming the XRD results. RCL circuit was used to measure the capacitance and resistance at different frequencies at room temperature. The dielectric constant and conductivity were calculated. The change in resistivity with temperature was followed up to 523 K. The change in dielectric strength with temperature at spot frequency of 10 kHz is demonstrated. The electrical conductivity was found to increase with the proportion of cerium oxide up to 0.2 mole then decreased. (orig.)

  11. Bis(4H-1,2,4-triazol-3-yldisulfane

    Directory of Open Access Journals (Sweden)

    Dongsheng Liu

    2008-01-01

    Full Text Available The title compound, C4H4N6S2, was synthesized by the reaction of 3-mercapto-1H-1,2,4-triazole with sodium hydroxide in ethanol. The molecule possesses a crystallographically imposed twofold axis. Intermolecular N—H...N hydrogen bonds link the molecules into chains along the c axis.

  12. Imaging brain tumor proliferative activity with [I-124]iododeoxyuridine

    NARCIS (Netherlands)

    Blasberg, RG; Roelcke, U; Weinreich, R; Beattie, B; von Ammon, K; Yonekawa, Y; Landolt, H; Guenther, [No Value; Crompton, NEA; Vontobel, P; Missimer, J; Maguire, RP; Koziorowski, J; Knust, EJ; Finn, RD; Leenders, KL

    2000-01-01

    Iododeoxyuridine (IUdR) uptake and retention was imaged by positron emission tomography (PET) at 0-48 min and 24 h after administration of 28.0-64.4 MBq (0.76-1.74 mCi) of [I-124]IUdR in 20 patients with brain tumors, including meningiomas and gliomas, The PET images were directly compared with gado

  13. Ozone Depletion Potentials of HCFC-123 and HCFC-124

    Science.gov (United States)

    Riepe, E. L.; Patten, K. O.; Wuebbles, D. J.

    2005-05-01

    The Montreal Protocol has phased out most chlorinated and brominated compounds because of their great efficiency in depleting ozone in the stratosphere. Compounds such as CHCl2CF3 (HCFC-123) and CHClFCF3 (HCFC-124) are being used in commercial refrigeration units and have much shorter atmospheric lifetimes than the chlorofluorocarbons they replace. Despite their small resulting Ozone Depletion Potentials (ODPs), these compounds are still currently expected to be eliminated under the existing Protocol, but there remain questions about finding suitable replacements that would not have other environmental effects. The HCFC-123 and HCFC-124 model-calculated atmospheric lifetimes of 1.3 years and 5.8 years are much shorter compared to the 45 years of CCl3F (CFC-11). In this study, we have reevaluated these compounds with an updated version of the UIUC two-dimensional chemical transport model and with the MOZART (version 3) three-dimensional chemical-transport model. The new version of the two-dimensional model gives ODPs of 0.012 and 0.0125 for HCFC-123 and HCFC-124, respectively. The ODP for HCFC-123 agrees well with previously reported values while the ODP for HCFC-124 is much smaller than earlier estimates. These analyses along with those from the three-dimensional modeling studies will be discussed in the presentation.

  14. 17 CFR 248.124 - Reasonable opportunity to opt out.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) REGULATIONS S-P AND S-AM Regulation S-AM: Limitations on Affiliate Marketing § 248.124 Reasonable... affiliate to make marketing solicitations to a consumer about your products or services unless the consumer... Internet Web site at which the consumer has obtained a product or service. The consumer...

  15. 9 CFR 354.124 - Quarantine of diseased rabbits.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Quarantine of diseased rabbits. 354... INSPECTION AND CERTIFICATION VOLUNTARY INSPECTION OF RABBITS AND EDIBLE PRODUCTS THEREOF Inspection Procedures; Ante-Mortem Inspections § 354.124 Quarantine of diseased rabbits. If live rabbits, which...

  16. 42 CFR 124.513 - Public facility compliance alternative.

    Science.gov (United States)

    2010-10-01

    ... facility which is owned and operated by a unit of State or local government or a quasi-public corporation...-public corporation as defined at 42 CFR 124.2(m), to cover operating deficits attributable to the... 42 Public Health 1 2010-10-01 2010-10-01 false Public facility compliance alternative....

  17. 1,2,4-Butanetriol: Analysis and Synthesis

    Science.gov (United States)

    1982-12-08

    ANHYDRIDE ........................41 CLEAVAGE OF CYCLIC ETHERS. .. ....... ......... 43 REFERENCES .. ... .......... .......... ......... 45... NOMENCLATURE .. ... .......... .......... ........ 49 1. iii/jy NSWC TR 82-380 ILLUSTRATIONS Figure Page I HYDROGENATION OF DIETHYLMALATE IN ETHANOL OVER NIKKI...of acetic acid, acetic anhydride , and sul Uric acid yielded 1,2,4-butanetriol triacetate. Subsequent methanolysis of the acetate produced BT. Wagaman

  18. 42 CFR 417.124 - Administration and management.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Administration and management. 417.124 Section 417... (CONTINUED) MEDICARE PROGRAM HEALTH MAINTENANCE ORGANIZATIONS, COMPETITIVE MEDICAL PLANS, AND HEALTH CARE... to organize, plan, control and evaluate the financial, marketing, health services, quality...

  19. Clarification of Confusion in Level Scheme of 124Cs

    Institute of Scientific and Technical Information of China (English)

    YANG Dong; LU Jing-Bin; LIU Yun-Zuo; WANG Lie-Lin; MA Ke-Yan; YANG Chuan-Ding; HAN De-Kai; ZHAO Yan-Xin; MA Ying-Jun; ZHU Li-Hua; WU Xiao-Guang; LI Guang-Sheng

    2009-01-01

    Low-lying and high-spin states of 124Cs are studied through the 116Sn (11B,3n)124Cs reaction at a beam energy of 45 MeV.Several new linking transitions are observed,including three transitions between the yrast and πh11/2 (×) vd3/2 bands and two transitions between the yrast and πh11/2 (×) v(d5/2,g7/2) bands.These transitions fix the excitation energy of the yrast band and its decay path,and confirm the existence of eight E1 linking transitions between the yrast and πh11/2 (×) v( d5/2,g7/2) bands observed before.These E1 linldng transitions infer the octupole correlation in 124Cs.The decay paths of the yrast band are investigated,and discrepancies in the level scheme of 124Cs in the latest two studies are clarified.The reason for the discrepancies is discussed.A new decoupled band is established and temporarily assigned as the unfavored signature partner of πh11/2 (×) vd3/2 configuration.

  20. 38 CFR 4.124 - Neuralgia, cranial or peripheral.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Neuralgia, cranial or....124 Neuralgia, cranial or peripheral. Neuralgia, cranial or peripheral, characterized usually by a... code number and rating. Tic douloureux, or trifacial neuralgia, may be rated up to complete...

  1. 27 CFR 9.124 - Wild Horse Valley.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Wild Horse Valley. 9.124... Horse Valley. (a) Name. The name of the viticultural area described in this section is “Wild Horse Valley.” (b) Approved Map. The appropriate map for determining the boundaries of the “Wild Horse...

  2. 18 CFR 367.1240 - Account 124, Other investments.

    Science.gov (United States)

    2010-04-01

    ... ACT Balance Sheet Chart of Accounts Other Property and Investments § 367.1240 Account 124, Other... investments. 367.1240 Section 367.1240 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005,...

  3. Influence of agglomeration of cerium oxide nanoparticles and speciation of cerium(III) on short term effects to the green algae Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Röhder, Lena A. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Brandt, Tanja [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); Sigg, Laura [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Behra, Renata, E-mail: Renata.behra@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland)

    2014-07-01

    Highlights: • Phosphate-dispersed CeO₂ NP did not affect photosynthetic yield in C. reinhardtii. • Agglomerated CeO₂ NP slightly decreased photosynthetic yield. • Cerium(III) was shown to affect photosynthetic yield and intracellular ROS level. • Slight effects of CeO₂ NP were caused by dissolved Ce³⁺ ions present in suspensions. • Wild type and cell wall free mutant of C. reinhardtii showed the same sensitivity. - Abstract: Cerium oxide nanoparticles (CeO₂ NP) are increasingly used in industrial applications and may be released to the aquatic environment. The fate of CeO₂ NP and effects on algae are largely unknown. In this study, the short term effects of CeO₂ NP in two different agglomeration states on the green algae Chlamydomonas reinhardtii were examined. The role of dissolved cerium(III) on toxicity, its speciation and the dissolution of CeO₂ NP were considered. The role of cell wall of C. reinhardtii as a barrier and its influence on the sensitivity to CeO₂ NP and cerium(III) was evaluated by testing both, the wild type and the cell wall free mutant of C. reinhardtii. Characterization showed that CeO₂ NP had a surface charge of ~0 mV at physiological pH and agglomerated in exposure media. Phosphate stabilized CeO₂ NP at pH 7.5 over 24 h. This effect was exploited to test CeO₂ NP dispersed in phosphate with a mean size of 140 nm and agglomerated in absence of phosphate with a mean size of 2000 nm. The level of dissolved cerium(III) in CeO₂ NP suspensions was very low and between 0.1 and 27 nM in all tested media. Exposure of C. reinhardtii to Ce(NO₃)₃ decreased the photosynthetic yield in a concentration dependent manner with EC₅₀ of 7.5 ± 0.84 μM for wild type and EC₅₀ of 6.3 ± 0.53 μM for the cell wall free mutant. The intracellular level of reactive oxygen species (ROS) increased upon exposure to Ce(NO₃)₃ with effective concentrations similar to those inhibiting photosynthesis. The agglomerated Ce

  4. Cyanex 923 as the extractant in a rare earth element impurity analysis of high-purity cerium oxide.

    Science.gov (United States)

    Duan, Taicheng; Li, Hongfei; Kang, JianZhen; Chen, Hangting

    2004-06-01

    In this work, the feasibility of employing Cyanex 923 as an extractant into the non-cerium REE (rare earth elements) impurity analysis of high-purity cerium oxide was investigated. Through investigations on the choice of the extraction medium, the optimium extraction acidity, matrix Ce4+ effect on the non-cerium REE ion extraction, the optimium extractant concentration and suitable extracting time, and oscillation strengh, it was found that when the phase ratio was at 1:1 and the acicidity was about 2% H2SO4, by gently shaking by hand for about 2 min, 10 mL of 30% Cyanex 923 could not extract even for a 20 ng amount of non-cerium REE3+ ions. However, the extraction efficiency for Ce4+ of 100 mg total amount under the same conditions was about 96%, indicating that a 25-fold preconcentration factor could be achieved. Thus, it was concluded that Cyanex 923 could be used in a REE impurity analysis of 99.9999% or so pure cerium oxide for primary sepapation to elimilate matrix-induced interferences encountered in an ICP-MS (inductively coupled plasma mass spectroscopy) determination.

  5. SYNTHESIS OF CATIONIC CERIUM COMPOUNDS [CP2CE(L)2][BPH4] (L = TETRAHYDROFURAN OR TETRAHYDROTHIOPHENE) AND THE CRYSTAL-STRUCTURE OF THE TETRAHYDROTHIOPHENE DERIVATIVE

    NARCIS (Netherlands)

    HEERES, HJ; MEETSMA, A; TEUBEN, JH

    1991-01-01

    Protolysis of the cerium alkyl Cp2*CeCH(SiMe3)2 (1) by triethylammoniumtetraphenylborate provides a useful route to cationic cerium compounds [Cp2*Ce(L)2][BPh4] (2, L = tetrahydrofuran; 3, L = tetrahydrothiophene). The crystal structure of the tetrahydrothiophene derivative was determined by X-ray d

  6. Reactive removal of 2-chloroethyl ethyl sulfide vapors under visible light irradiation by cerium oxide modified highly porous zirconium (hydr) oxide

    Science.gov (United States)

    Mitchell, Joshua K.; Arcibar-Orozco, Javier A.; Bandosz, Teresa J.

    2016-12-01

    Highly porous cerium oxide modified Zr(OH)4 samples were synthesized using a simple one stage urea precipitation method. The amorphicity level of zirconium hydroxide did not change upon addition of cerium oxide particles. A unique aspect of the cerium oxide-modified materials is the presence of both the oxide (CeO2) and hydroxide (Zr(OH)4) phases resulting in a unique microporous structure of the final material. Extensive characterization using various chemical and physical methods revealed significant differences in the surface features. All synthesized materials were microporous and small additions of cerium oxide affected the surface chemistry. These samples were found as effective catalysts for a decontamination of mustard gas surrogate, 2-chloroethyl ethyl sulfide (CEES). Cerium oxide addition significantly decreased the band gap of zirconium hydroxide. Ethyl vinyl sulfide and 1,2-bis (Ethyl thio) ethane were identified as surface reaction products.

  7. Effect of cerium additive and secondary phase analysis on Ag0.5Bi0.5TiO3 ceramics

    Indian Academy of Sciences (India)

    S Supriya; Antonio J Dos Santos-García; F Fernández-Martinez

    2016-02-01

    Cerium-doped silver bismuth titanate—Ag0.5Bi0.5TiO3 (ABT) ceramics have been synthesized by the high-temperature solid-state reaction method. The structure and elemental examination of the prepared ceramic was analysed by X-ray diffraction (XRD), Fourier transform infrared, scanning electron microscopy and energydispersive spectroscopy. XRD analysis showed the presence of pyrochlore structure and secondary phase when more than 5 mol% cerium was added. The impact of temperature on cerium-doped silver bismuth titanate samples was analysed by differential thermal analysis and differential scanning calorimetry. Cerium doping caused the flaky morphology comparing with undoped sample. The homogeneity of all the samples was discussed in detail by diffuse reflectance spectrum. This is the first time the reflection process is analysed for the cerium-doped ABT system to the best of our knowledge.

  8. Ab initio molecular dynamics study of the properties of cerium in liquid sodium at 1000 K temperature

    Energy Technology Data Exchange (ETDEWEB)

    Samin, Adib; Li, Xiang; Zhang, Jinsuo [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, Ohio 43210 (United States); Mariani, R. D. [Idaho National Laboratory, Materials and Fuels Complex, Idaho Falls, Idaho 83415 (United States); Unal, Cetin [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)

    2015-12-21

    For liquid-sodium-cooled fast nuclear reactor systems, it is crucial to understand the behavior of lanthanides and other potential fission products in liquid sodium or other liquid metal solutions such as liquid cesium-sodium. In this study, we focus on lanthanide behavior in liquid sodium. Using ab initio molecular dynamics, we found that the solubility of cerium in liquid sodium at 1000 K was less than 0.78 at. %, and the diffusion coefficient of cerium in liquid sodium was calculated to be 5.57 × 10{sup −9} m{sup 2}/s. Furthermore, it was found that cerium in small amounts may significantly alter the heat capacity of the liquid sodium system. Our results are consistent with the experimental results for similar materials under similar conditions.

  9. Ab initio molecular dynamics study of the properties of cerium in liquid sodium at 1000 K temperature

    Science.gov (United States)

    Samin, Adib; Li, Xiang; Zhang, Jinsuo; Mariani, R. D.; Unal, Cetin

    2015-12-01

    For liquid-sodium-cooled fast nuclear reactor systems, it is crucial to understand the behavior of lanthanides and other potential fission products in liquid sodium or other liquid metal solutions such as liquid cesium-sodium. In this study, we focus on lanthanide behavior in liquid sodium. Using ab initio molecular dynamics, we found that the solubility of cerium in liquid sodium at 1000 K was less than 0.78 at. %, and the diffusion coefficient of cerium in liquid sodium was calculated to be 5.57 × 10-9 m2/s. Furthermore, it was found that cerium in small amounts may significantly alter the heat capacity of the liquid sodium system. Our results are consistent with the experimental results for similar materials under similar conditions.

  10. Catalytic activity of cerium-doped Ru/Al2O3 during ozonation of dimethyl phthalate

    Institute of Scientific and Technical Information of China (English)

    Yunrui ZHOU; Wanpeng ZHU; Xun CHEN

    2008-01-01

    In this paper, factors influencing the mineraliza-tion of dimethyl phthalate (DMP) during catalytic ozona-tion with a cerium-doped Ru/Al2O3 catalyst were studied. The catalytic contribution was calculated through the results of a companrison experiment. It showed that doping cerium significantly enhanced catalytic activity. The total organic carbon (TOC) removal over the doped catalyst at 100 rain reached 75.1%, 61.3% using Ru/Al2O3 catalyst and only 14.0% using ozone alone. Catalytic activity reached the maximum when 0.2% of ruthenium and 1.0% of cerium'were simultaneously loaded onto Al2O3 support. Results of experiments on oxidation by ozone alone, adsorption of the catalyst, Ce ion's and heterogeneous catalytic ozonation confirmed that the contribution of het-erogeneous catalytic ozonation was about 50%, which showed the obvious effect of Ru-Ce/Al2O3 on catalytic activity.

  11. Single crystal fiber growth of cerium doped strontium yttrate, SrY2O4:Ce3+

    Science.gov (United States)

    Philippen, J.; Guguschev, C.; Klimm, D.

    2017-02-01

    First single crystal fibers of cerium doped strontium yttrate were fabricated using the laser-heated pedestal growth technique. Through thermodynamic equilibrium calculations and by high-temperature mass spectrometry suitable growth conditions could be determined. The atmosphere played an important role during crystallization. It affected the composition shift, on the one hand, and the valence state of cerium, on the other hand. These dependencies can be explained by combining X-ray diffraction, elemental analysis, and optical spectroscopy. Crystallization in slightly reducing nitrogen atmosphere proved to be a reasonable choice, because evaporation is suppressed and trivalent cerium is stabilized. Strong green emission that depends on the oxygen fugacity during crystallization could be excited using UV light. Optical properties of SrY2O4:Ce3+ were measured for the first time.

  12. Crystallization behavior of electroless Co-Ni-B alloy plated in magnetic field in presence of cerium

    Institute of Scientific and Technical Information of China (English)

    XUAN Tian-peng; ZHANG Lei; HUANG Qin-hua

    2006-01-01

    The electrochemical property, chemical composition and crystal structure of electroless Co-Ni-B-Ce alloy plated in general state as well as in magnetic field were studied using potentiometer, plasma emission spectrometer, X-ray diffractometer,transmission electron microscope. The results show that the static potential and polarizability of electroless Co-Ni-B alloy are remarkably improved as the plating is carried out in magnetic field in the presence of a little amount of cerium in plating bath.Because of the action of magnetic field and rare earth element cerium, the boron content in alloy decreases, while cobalt and nickel contents increase. As a result, the amorphous Co-Ni-B alloy transforms to the microcrystalline Co-Ni-B-Ce alloy when the plating is in general state, and the Co-Ni-B alloy makes a crystalline transformation because of the action of magnetic field and rare earth element cerium.

  13. Corrosion resistance of flaky aluminum pigment coated with cerium oxides/hydroxides in chloride and acidic electrolytes

    Science.gov (United States)

    Niroumandrad, S.; Rostami, M.; Ramezanzadeh, B.

    2015-12-01

    The objective of this study was to enhance the corrosion resistance of lamellar aluminum pigment through surface treatment by cerium oxides/hydroxides. The surface composition of the pigments was studied by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the pigment was evaluated by conventional hydrogen evolution measurements in acidic solution and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. Results showed that the Ce-rich coating composed of Ce2O3 and CeO2 was precipitated on the pigment surface after immersion in the cerium solution. The corrosion resistance of pigment was significantly enhanced after modification with cerium layer.

  14. Implementation of a complex multi-phase equation of state for cerium and its correlation with experiment

    Energy Technology Data Exchange (ETDEWEB)

    Cherne, Frank J [Los Alamos National Laboratory; Jensen, Brian J [Los Alamos National Laboratory; Elkin, Vyacheslav M [VNIITF

    2009-01-01

    The complexity of cerium combined with its interesting material properties makes it a desirable material to examine dynamically. Characteristics such as the softening of the material before the phase change, low pressure solid-solid phase change, predicted low pressure melt boundary, and the solid-solid critical point add complexity to the construction of its equation of state. Currently, we are incorporating a feedback loop between a theoretical understanding of the material and an experimental understanding. Using a model equation of state for cerium we compare calculated wave profiles with experimental wave profiles for a number of front surface impact (cerium impacting a plated window) experiments. Using the calculated release isentrope we predict the temperature of the observed rarefaction shock. These experiments showed that the release state occurs at different magnitudes, thus allowing us to infer where dynamic {gamma} - {alpha} phase boundary is.

  15. [Hydrogen bis(1,2,4-triazole] 1,2,4-triazolium bis(3-carboxy-4-hydroxybenzenesulfonate 1,2,4-triazole disolvate

    Directory of Open Access Journals (Sweden)

    Ming-qiang Qiu

    2010-08-01

    Full Text Available The title compound, C2H4N3+·[H(C2H3N32]+·2C7H5O6S−·2C2H3N3, consists of two types of 1,2,4-triazole monocation, one protonated at the 2-site lying across a twofold axis and the other protonated at the 4-site with the H atom disordered over a center of symmetry, a 5-sulfosalicylate anion and a neutral 1,2,4-triazole molecule. The component ions are linked into a three-dimensional network by a combination of N—H...O, N—H...N, O—H...O, O—H...N, C—H...O and C—H...N hydrogen bonds. In addition, benzene–benzene π–π interactions of 3.942 (2 Å [interplanar spacing = 3.390 (2 Å] and C—O...π (3.331 Å interactions are observed.

  16. Effect of ultrasound on the structural and textural properties of copper-impregnated cerium-modified zirconium-pillared bentonite

    Science.gov (United States)

    Tomul, Fatma

    2011-12-01

    In this study, the synthesis of zirconium-pillared bentonite modified with cerium was performed via two different methods by the application of conventional and ultrasonic treatments during the intercalation stage. To synthesise copper-impregnated pillared clays by wet impregnation, cerium-modified zirconium-pillared clays were used as supportive materials after being calcined at 300 °C. Ultrasonic treatment significantly decreased the required processing time compared with the conventional treatment of the synthesised pillared bentonites. Chemical analysis confirmed the incorporation of Zr 4+, Ce 4+ and Cu 2+ species into the pillared bentonites. X-ray diffraction (XRD) patterns of zirconium- and cerium/zirconium-pillared bentonites prepared by conventional treatment show that one large d-spacing above 3.5 nm corresponds to the mesoporous delaminated part, and another small d-spacing above 1.7 nm is indicative of the microporous pillared part. Zirconium- and cerium/zirconium-pillared bentonites prepared via ultrasonic treatment exhibited similar results, with the same high d-spacing but with a second low-intensity d-spacing above 1.9 nm. The delaminated structures of the pillared bentonites synthesised by both methods were conserved after copper impregnation. Nitrogen-adsorption isotherm analysis showed that the textural characteristics of products synthesised by ultrasonic treatment were comparable to those of products synthesised by conventional treatment. Fourier-transform infrared spectroscopy (FTIR) analyses showed the presence of Brønsted- and Lewis-acid sites, and zirconium-pillared clays synthesised by conventional treatment exhibited increased numbers of Brønsted- and Lewis-acid sites after cerium addition and copper impregnation. However, the products synthesised by ultrasonic treatment exhibited an increased number of Brønsted- and Lewis-acid sites after cerium addition, but a decreased number of acid sites after copper impregnation.

  17. 13 CFR 124.402 - How does a Participant develop a business plan?

    Science.gov (United States)

    2010-01-01

    ... business plan? 124.402 Section 124.402 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION 8(a... Development § 124.402 How does a Participant develop a business plan? (a) General. In order to assist the SBA... Participant must develop a comprehensive business plan setting forth its business targets, objectives,...

  18. 29 CFR 780.124 - Raising of fur-bearing animals.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Raising of fur-bearing animals. 780.124 Section 780.124... General Scope of Agriculture Raising of Livestock, Bees, Fur-Bearing Animals, Or Poultry § 780.124 Raising of fur-bearing animals. (a) The term “fur-bearing animals” has reference to animals which bear fur...

  19. 13 CFR 124.1010 - What procedures apply to disadvantaged status protests?

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What procedures apply to disadvantaged status protests? 124.1010 Section 124.1010 Business Credit and Assistance SMALL BUSINESS..., Certification, and Protests Relating to Federal Small Disadvantaged Business Programs § 124.1010 What...

  20. Regioselectivity in the Thermal Rearrangement of Unsymmetrical 4-Methyl-4H-1,2,4-triazoles to 1-Methyl-1H-1,2,4-triazoles

    Directory of Open Access Journals (Sweden)

    Per H.J. Carlsen

    2001-11-01

    Full Text Available The rearrangement of 4-methyl-3,5-diaryl-4H-1,2,4-triazoles to the corresponding 1-methyl-3,5-diaryl-1H-1,2,4-triazoles showed regioselectivity comparable to that observed for the alkylation of 3,5-diaryl-1H-1,2,4-triazoles. This lends support to a proposed mechanism for the rearrangement that involves consecutive nucleophilic displacements steps.

  1. Improvement of corrosion resistance of AZ31 Mg alloy by anodizing with co-precipitation of cerium oxide

    Institute of Scientific and Technical Information of China (English)

    Salah Abdelghany SALMAN; Ryoichi ICHINO; Masazumi OKIDO

    2009-01-01

    Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated. The chemical composition and phase structure of the coating film were determined via optical microscopy, SEM and XRD. The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K. The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution. In addition, the surface properties are enhanced and the film contains no crack.

  2. Equivalent Activity Coefficient Phenomenon of Cerium Reacting with Lead or Bismuth in Ag, Cu and Zn Alloy

    Institute of Scientific and Technical Information of China (English)

    薛松柏; 钱乙余; 董健

    2002-01-01

    The relation between contents of cerium and impurity lead or bismuth to their activity coefficient in Ag, Cu and Zn-base alloy was calculated and analyzed by using the ternary system Chou model. The thermodynamic calculation results show that the "equivalent activity coefficient phenomenon" emerges among the activity coefficient of solute in a certain range of cerium (or at a certain point) for the Ce-Pb-X and Ce-Bi-X (X=Ag, Cu or Zn) ternary alloy system. Under this condition, the activity coefficient of solute has nothing to do with its own concentration. The preliminary theoretical analysis to this phenomenon was also made.

  3. Catalytic wet peroxidation of pyridine bearing wastewater by cerium supported SBA-15

    Energy Technology Data Exchange (ETDEWEB)

    Subbaramaiah, V. [Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 Uttarakhand (India); Srivastava, Vimal Chandra, E-mail: vimalcsr@yahoo.co.in [Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 Uttarakhand (India); Mall, Indra Deo [Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 Uttarakhand (India)

    2013-03-15

    Highlights: ► Cerium supported SBA-15 (Ce/SBA-15) synthesized by two-step synthesis. ► Characterization of Ce/SBA-15 by FTIR, XRD and BET surface area. ► Catalytic peroxidation of pyridine by Ce/SBA-15. ► Optimization of parameters like catalyst dose, H{sub 2}O{sub 2} dose, initial concentration and temperature. ► Catalyst reusability and leaching study performed. -- Abstract: Cerium supported SBA-15 (Ce/SBA-15) was synthesized by two-step synthesis method in acidic medium. It was further characterized by various characterization techniques such as X-ray diffraction, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy and N{sub 2} adsorption–desorption pore size distribution analysis. The Ce/SBA-15 showed highly ordered meso-structure with pore diameter ≈ 70–100 A and pore volume ≈ 0.025 cm{sup 3}/g. Ce/SBA-15 was further evaluated as a catalyst for the oxidation of highly toxic and non-biodegradable material, pyridine, by catalytic wet-peroxidation method. The effects of various operating parameters such as catalyst dose (0.5–6 g/l), stoichiometric ratio of H{sub 2}O{sub 2}/pyridine (1–6), initial pyridine concentration (50–800 mg/l) and temperature (313–358 K) have been evaluated and optimized. Ce/SBA-15 showed stable performance during reuse for six cycles with negligible cerium leaching. Kinetic and thermodynamic parameters and operation cost have also been determined.

  4. Spectroscopy of gadolinium gallium garnet doped with cerium under high hydrostatic pressure

    OpenAIRE

    2012-01-01

    Studies of the spectroscopic properties of Ce3+ dopant in bulk Gd3Ga5O12:Ce crystal under pressure are presented. In spite of strong inter-shell 4f ® 5d absorption bands at ambient pressure the cerium luminescence in Gd3Ga5O12 is entirely quenched even at low temperature. It has been shown that applying pressure allows for recovering the 5d ® 4f radiative transitions. Further increase of pressure improves the emission efficiency. This effect is analyzed in terms of two possible phenomen...

  5. ARTICLES: Photoinduced light scattering in cerium-doped barium strontium niobate crystals

    Science.gov (United States)

    Voronov, Valerii V.; Dorosh, I. R.; Kuz'minov, Yu S.; Tkachenko, N. V.

    1980-11-01

    Photoinduced light scattering was observed in cerium-doped (SrxBa1-x)1-y(Nb2O6)y crystals having the composition x = 0.61, y = 0.4993. It was found that this effect is due to holographic amplification of light scattered by crystal defects. An analysis is made of static and dynamic characteristics of self-amplification of scattered light in the crystals. A theoretical model of the process is constructed assuming that the hologram recording process is of the diffusion type. Theoretical results are compared with the experiment.

  6. Photoinduced light scattering in cerium-doped barium strontium niobate crystals

    Science.gov (United States)

    Voronov, V. V.; Dorosh, I. R.; Kuz'minov, Yu. S.; Tkachenko, N. V.

    Photoinduced light scattering was observed in cerium-doped (Srx Ba1-x)1-y(Nb2O6)y crystals having the composition x = 0.61, y = 0.4993. It was found that this effect is due to holographic amplification of light scattered by crystal defects. An analysis is made of static and dynamic characteristics of self-amplification of scattered light in the crystals. A theoretical model of the process is constructed assuming that the hologram recording process is of the diffusion type. Theoretical results are compared with the experiment.

  7. Sequence-specific Hydrolysis of Single-stranded DNA by PNA-Cerium (Ⅳ) Adduct

    Institute of Scientific and Technical Information of China (English)

    He Bai SHEN; Feng WANG; Yong Tao YANG

    2005-01-01

    A novel artificial site specific cleavage reagent, with peptide nucleic acid (PNA) as sequence-recognizing moiety and cerium (Ⅳ) ions as "scissors" for cleaving target DNA, was synthesized. Subsequently, it was employed in the cleavage of target 26-mer single-stranded DNA (ssDNA), which has 10-mer sequence complementary with PNA recognizer in the hybrids,under physiological conditions. Reversed-phase high-performance liquid chromatogram (RPHPLC) experiments indicated that the artificial site specific cleavage reagent could cleave the target DNA specifically.

  8. Trace electrochemical analysis of Europium, Ytterbium, and Cerium at their joint presence in solution

    Directory of Open Access Journals (Sweden)

    Rema Matakova

    2012-03-01

    Full Text Available In the course of several decades at the department of analytical chemistry and chemistry of rare elements there were studied the electrode processes with participation of rare-earth metals (REM in accordance with the long awaiting problem of the development of rare-metal and rare-earth branch of non-ferrous metallurgy of Kazakhstan. With the aim of express and highly sensitive analytical control of raw materials and final product of rare-earth industry there were developed the methods of inversion-voltamperometric determination of low concentrations of europium, ytterbium and cerium under the conditions of their individual and combined presence in the solution.

  9. A nonreciprocal racetrack resonator based on vacuum-annealed magnetooptical cerium-substituted yttrium iron garnet.

    Science.gov (United States)

    Goto, Taichi; Onbasli, Mehmet C; Kim, Dong Hun; Singh, Vivek; Inoue, M; Kimerling, Lionel C; Ross, C A

    2014-08-11

    Vacuum annealed polycrystalline cerium substituted yttrium iron garnet (CeYIG) films deposited by radio frequency magnetron sputtering on non-garnet substrates were used in nonreciprocal racetrack resonators. CeYIG annealed at 800°C for 30 min provided a large Faraday rotation angle, close to the single crystal value. Crystallinity, magnetic properties, refractive indices and absorption coefficients were measured. The resonant transmission peak of the racetrack resonator covered with CeYIG was non-reciprocally shifted by applying an in-plane magnetic field.

  10. APPLICATIONS OF CERIUM BIS (MONOMYRISTY—LPHOSPHATE)ADSORBENT TO REVERSED PHASE LIQUID CHROMATOGRAPHY

    Institute of Scientific and Technical Information of China (English)

    SuZhengquan; FengHuixia; 等

    1996-01-01

    The tetravalent metal salts of monoalkyl phosphates [M(O3POR)2]are a new kind of stationary phases of Chromatography-homogeneous bonded phases.This paper deals with the application of cerium bis(monomyristylphosphate)as support to reversed phase liquid chromatography.The results show that the best mobil phase is CH3CN:H2O=95:5.The good separation to the mixture containing six aromatic hydrocarbons and the determination of naphthalene in a group samples have been achieved.The regression analysis shows that detect limits,linearities and precision for six aromatic hydrocarbons are good.

  11. Relationship between surface area and crystal size of pure and doped cerium oxides

    Institute of Scientific and Technical Information of China (English)

    C.; Bueno-Ferrer; S.; Parres-Esclapez; D.; Lozano-Castelló; A.; Bueno-López

    2010-01-01

    Pure and Zr, La or Pr-doped cerium oxides were characterised by transmission electron microscopy (TEM), N2 adsorption-desorption at -196 oC and X-ray diffraction (XRD). For crystal sizes calculation, the Scherrer and Williamson-Hall equations were compared, and the relationship between surface area and crystal size was critically discussed. It was demonstrated that the Williamson-Hall equation must be used instead of the Scherrer equation to calculate crystal sizes, since the latter equation underestimated ...

  12. UV-Shielding and Catalytic Characteristics of Nanoscale Zinc-Cerium Oxides

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Fine particles of zinc-cerium oxides (ZCO) used as an ultraviolet filter were prepared via combustion synthesis route. The catalytic activity, UV-shielding performance, surface modification and application of ZCO in polyester varnish were discussed in detail. The experimental results indicate that the photo-catalytic activity of ZCO is much smaller than these of ZnO and TiO2; the oxidation catalytic activity of ZCO is far lower than that of CeO2; the ZCO has shown excellent ultraviolet absorption in the range of UV;addition modified ZCO (MZCO) into polyester will enhance the UV-shielding capability of polyester.

  13. High-quality single-crystal growth and unique electronic states in cerium and uranium compounds

    Science.gov (United States)

    Onuki, Yoshichika; Settai, Rikio; Sugiyama, Kiyohiro; Inada, Yoshihiko; Takeuchi, Tetsuya; Haga, Yoshinori; Yamamoto, Etsuji; Harima, Hisatomo; Yamagami, Hiroshi

    2007-03-01

    We have grown many kinds of high-quality single crystals of cerium and uranium compounds and studied the Fermi surface properties via the de Haas-van Alphen experiments and energy band calculations. The quasi-two-dimensional electronic states are clarified in some compounds such as USb2, CeCoIn5, UPtGa5 and most likely UIr. In a ferromagnet CeRh3B2, we have found unique electronic states with quasi-one-dimensional character.

  14. Surface structures of cerium oxide nanocrystalline particles from the size dependence of the lattice parameters

    Science.gov (United States)

    Tsunekawa, S.; Ito, S.; Kawazoe, Y.

    2004-10-01

    Cerium oxide nanocrystalline particles are synthesized and monodispersed in the size range from 2 to 8nm in diameter. The dependence of the lattice parameters on particle size is obtained by x-ray and electron diffraction analyses. The size dependence well coincides with the estimation based on the assumption that the surface is composed of one layer of Ce2O3 and the inside consists of CeO2. The effect of particle size on lattice parameters is discussed from the differences in the fabrication method and the surface structure.

  15. Neurophysiological defects and neuronal gene deregulation in Drosophila mir-124 mutants.

    Directory of Open Access Journals (Sweden)

    Kailiang Sun

    2012-02-01

    Full Text Available miR-124 is conserved in sequence and neuronal expression across the animal kingdom and is predicted to have hundreds of mRNA targets. Diverse defects in neural development and function were reported from miR-124 antisense studies in vertebrates, but a nematode knockout of mir-124 surprisingly lacked detectable phenotypes. To provide genetic insight from Drosophila, we deleted its single mir-124 locus and found that it is dispensable for gross aspects of neural specification and differentiation. On the other hand, we detected a variety of mutant phenotypes that were rescuable by a mir-124 genomic transgene, including short lifespan, increased dendrite variation, impaired larval locomotion, and aberrant synaptic release at the NMJ. These phenotypes reflect extensive requirements of miR-124 even under optimal culture conditions. Comparison of the transcriptomes of cells from wild-type and mir-124 mutant animals, purified on the basis of mir-124 promoter activity, revealed broad upregulation of direct miR-124 targets. However, in contrast to the proposed mutual exclusion model for miR-124 function, its functional targets were relatively highly expressed in miR-124-expressing cells and were not enriched in genes annotated with epidermal expression. A notable aspect of the direct miR-124 network was coordinate targeting of five positive components in the retrograde BMP signaling pathway, whose activation in neurons increases synaptic release at the NMJ, similar to mir-124 mutants. Derepression of the direct miR-124 target network also had many secondary effects, including over-activity of other post-transcriptional repressors and a net incomplete transition from a neuroblast to a neuronal gene expression signature. Altogether, these studies demonstrate complex consequences of miR-124 loss on neural gene expression and neurophysiology.

  16. MicroRNA-124 suppresses growth of human hepatocellular carcinoma by targeting STAT3

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yanxin [Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Beijing 100191 (China); Biomedical Research Institute, Shenzhen-PKU-HKUST Medical Center, Guangdong Province, Shenzhen 518036 (China); Yue, Xupeng [Biomedical Research Institute, Shenzhen-PKU-HKUST Medical Center, Guangdong Province, Shenzhen 518036 (China); Cui, Yuanyuan [Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Beijing 100191 (China); Zhang, Jufeng, E-mail: jfzhang111@163.com [Biomedical Research Institute, Shenzhen-PKU-HKUST Medical Center, Guangdong Province, Shenzhen 518036 (China); Wang, KeWei, E-mail: wangkw@bjmu.edu.cn [Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Beijing 100191 (China); Biomedical Research Institute, Shenzhen-PKU-HKUST Medical Center, Guangdong Province, Shenzhen 518036 (China); Department of Molecular and Cellular Pharmacology, State Key Laboratory of Natural and Biomimetic Drugs, Peking University School of Pharmaceutical Sciences, Beijing 100191 (China)

    2013-11-29

    Highlights: •miR-124 is down-regulated in hepatocellular carcinoma HepG2 cells. •Over-expression of miR-124 suppresses proliferation and induces apoptosis in HepG2 cells. •miR-124 inhibits xenograft tumor growth in nude mice implanted with HepG2 cells by reducing STAT3 expression. •STATs function as a novel target of miR-124 in HCC HepG2 cells. -- Abstract: The aberrant expression of microRNAs is associated with development and progression of cancers. Down-regulation of miR-124 has been demonstrated in the hepatocellular carcinoma (HCC), but the underlying mechanism by which miR-124 suppresses tumorigenesis in HCC remains elusive. In this study, we found that miR-124 suppresses the tumor growth of HCC through targeting the signal transducers and activators of transcription 3 (STAT3). Overexpression of miR-124 suppressed proliferation and induced apoptosis in HepG-2 cells. Luciferase assay confirmed that miR-124 binding to the 3′-UTR region of STAT3 inhibited the expression of STAT3 and phosphorylated STAT3 proteins in HepG-2 cells. Knockdown of STAT3 by siRNA in HepG-2 cells mimicked the effect induced by miR-124. Overexpression of STAT3 in miR-124-transfected HepG-2 cells effectively rescued the inhibition of cell proliferation caused by miR-124. Furthermore, miR-124 suppressed xenograft tumor growth in nude mice implanted with HepG-2 cells by reducing STAT3 expression. Taken together, our findings show that miR-124 functions as tumor suppressor in HCC by targeting STAT3, and miR-124 may therefore serve as a biomarker for diagnosis and therapeutics in HCC.

  17. Scintillation and Luminescence Properties of Undoped and Cerium-doped LiGdCl4 and NaGdCl4

    Energy Technology Data Exchange (ETDEWEB)

    Porter-Chapman, Yetta D.; Bourret-Courchesne, Edith D.; Bizarri, Gregory; Weber, Marvin J.; Derenzo, Stephen E.

    2008-10-05

    We report the scintillation properties of the undoped and cerium-doped variations of LiGdCl4 and NaGdCl4. Powder samples of these materials exhibit significant scintillation under X-rays. The samples were synthesized by solid-state methods from a 1:1 molar ratio of lithium or sodium chloride and gadolinium chloride. Cerium trichloride was used as the dopant. The physical, optical, and scintillation properties of these materials were analyzed by powder X-ray diffraction, photoluminescence, X-ray excited luminescence, and pulsed X-ray luminosity measurements. Increases in light yields are observed as the concentration of cerium increases. The highest light yields occurred at 20 percent cerium doping for both compounds. At larger concentrations neither compound formed, indicating a breakdown of the lattice with the addition of large amounts of cerium cations. At 20 percent cerium, LiGdCl4 and NaGdCl4 display scintillation light 3.6 times and 2.2 times the light yield of the reference material, YAlO3:Ce3+, respectively. Both emit in the ranges of 340 ? 350 nm and 365 - 370 nm and display multiexponential decays with cerium-like decay components at 33 ns (LiGdCl4:Ce) and 26 ns (NaGdCl4:Ce).

  18. Characterization of microstructure and catalytic of cerium oxide obtained by colloidal solution; Caracterizacao da microestrutura e da atividade catalitica de oxido de cerio obtido por solucao coloidal

    Energy Technology Data Exchange (ETDEWEB)

    Senisse, C.A.L.; Bergmann, C.P.; Alves, A.K., E-mail: carolinasenisse@hotmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alege, RS (Brazil). Lab. de Materiais Ceramicos

    2012-07-01

    This study investigated to obtain particles of cerium oxide, for use as catalysts for the combustion of methane using the technique of through polymeric colloidal solution. Obtaining the colloidal system is based on hydrolysis of salts such as cerium acetylacetonate, cerium nitrate in the presence of additives such as polyvinylbutyral (PVB), polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA), at concentrations of 5, 10 and 15% in aqueous or alcoholic medium. These solutions containing ions of interest were subjected to a heat treatment at 650° C for 30 minutes, with heating rate of 2 ° C/ min. After heat treatment, the fibers were characterized according to their morphology, surface area, crystallinity, weight loss and catalytic activity. Samples obtained from cerium acetylacetonate were more reactive than the cerium nitrate to the combustion of methane, as showed greater conversions and higher temperatures reached during the process, which is of utmost importance since the combustion catalytic methane is used for generating thermal energy. After the reaction with methane, the samples underwent significant change in surface area, probably due to the intensity of combustion reactions of the nitrate and the generation of heat involved in this reaction, which gave rise to coarse particles. During the combustion process using the obtained from particles of cerium acetylacetonate, there was the release of large quantities of nitrogen compared to the results of assays with the particles obtained with cerium nitrate. (author)

  19. Effects of cerium oxide supplementation to laying hen diets on performance, egg quality, some antioxidant enzymes in serum and lipid oxidation in egg yolk.

    Science.gov (United States)

    Bölükbaşı, S C; Al-Sagan, A A; Ürüşan, H; Erhan, M K; Durmuş, O; Kurt, N

    2016-08-01

    This study was conducted to determine the effects of dietary cerium oxide levels (0, 100, 200, 300 or 400 mg/kg) on the laying performance, egg quality, some blood serum parameters and egg lipid peroxidation of laying hen. In total, one hundred and twenty 22-week-old brown Lohman LSL laying hens were randomly assigned to five groups equally (n = 24). Each treatment was replicated six times. Dietary supplementation of cerium oxide had no significant effect on feed intake and egg weight. The addition of cerium oxide to the laying hens' feed improved feed conversion ratio and increased (p laying hens feed led to a significant (p laying hen diets. It was also observed that serum superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration decreased significantly with supplementation of cerium oxide in diets. Inclusion of cerium oxide resulted in a significant reduction in thiobarbituric acid reactive substance (TBARS) values in egg yolk in this study. It can be concluded that the addition of cerium oxide had positive effects on egg production, feed conversion ratio and egg shelf life. Based on the results of this study, it could be advised to supplement laying hens feed with cerium oxide as feed additives.

  20. Effect of cerium on structure modifications of a hybrid sol–gel coating, its mechanical properties and anti-corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Cambon, Jean-Baptiste, E-mail: cambon@chimie.ups-tlse.fr [Institut Carnot CIRIMAT, Université de Toulouse, UMR CNRS 5085, 118 Route de Narbonne, 31062 Toulouse Cedex 9 (France); Esteban, Julien; Ansart, Florence; Bonino, Jean-Pierre; Turq, Viviane [Institut Carnot CIRIMAT, Université de Toulouse, UMR CNRS 5085, 118 Route de Narbonne, 31062 Toulouse Cedex 9 (France); Santagneli, S.H.; Santilli, C.V.; Pulcinelli, S.H. [Departamento Fısico-Química, Instituto de Química, Universidade Estadual Paulista, UNESP, CP 355, 14801-970 Araraquara, SP (Brazil)

    2012-11-15

    Highlights: ► New sol–gel routes to replace chromates for corrosion protection of aluminum. ► Effect of cerium concentration on the microstructure of xerogel. ► Electrochemical and mechanical performances of hybrid coating with different cerium contents. ► Good correlation between the different results with an optimal cerium content of 0.01 M. -- Abstract: An organic–inorganic hybrid coating was developed to improve the corrosion resistance of the aluminum alloy AA 2024-T3. Organic and inorganic coatings derived from glycidoxypropyl-trimethoxysilane (GPTMS) and aluminum tri-sec-butoxide Al(O{sup s}Bu){sub 3}, with different cerium contents, were deposited onto aluminum by dip-coating process. Corrosion resistance and mechanical properties were investigated by electrochemical impedance measurements and nano-indentation respectively. An optimal cerium concentration of 0.01 M was evidenced. To correlate and explain the hybrid coating performances in relation to the cerium content, NMR experiments were performed. It has been shown that when the cerium concentration in the hybrid is higher than 0.01 M there are important modifications in the hybrid structure that account for the mechanical properties and anti-corrosion behavior of the sol–gel coating.

  1. Catalytic wet peroxidation of pyridine bearing wastewater by cerium supported SBA-15.

    Science.gov (United States)

    Subbaramaiah, V; Srivastava, Vimal Chandra; Mall, Indra Deo

    2013-03-15

    Cerium supported SBA-15 (Ce/SBA-15) was synthesized by two-step synthesis method in acidic medium. It was further characterized by various characterization techniques such as X-ray diffraction, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy and N2 adsorption-desorption pore size distribution analysis. The Ce/SBA-15 showed highly ordered meso-structure with pore diameter≈70-100Ǻ and pore volume≈0.025cm(3)/g. Ce/SBA-15 was further evaluated as a catalyst for the oxidation of highly toxic and non-biodegradable material, pyridine, by catalytic wet-peroxidation method. The effects of various operating parameters such as catalyst dose (0.5-6g/l), stoichiometric ratio of H2O2/pyridine (1-6), initial pyridine concentration (50-800mg/l) and temperature (313-358K) have been evaluated and optimized. Ce/SBA-15 showed stable performance during reuse for six cycles with negligible cerium leaching. Kinetic and thermodynamic parameters and operation cost have also been determined.

  2. Removal of aromatic amines from water by montmorillonite-(cerium or zirconium) phosphate crosslinked compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Pradas, E.; Villafranca-Sanchez, M.; Urena-Amate, M.D. (Univ. of Almeria (Spain). Dept. of Inorganic Chemistry); Del Rey-Bueno, F.; Garcia-Rodriguez, A. (Univ. of Granada (Spain). Dept. of Inorganic Chemistry)

    To evaluate the potential use of two montmorillonite-(Ce or Zr) phosphate crosslinked compounds in removing organic pollutants such as aniline, p-toluidine, and p-acetylaniline from water, adsorption experiments were performed under conditions of varied temperature (288 and 308 K). Adsorption on the montmorillonite-Ce-phosphate compound was best described by a hyperbolic (H-type) isotherm, whereas for the montmorillonite-Zr-phosphate compound, S-type isotherms were obtained for p-toluidine and aniline and L-type for p-acetylaniline. Amines adsorption increases with increasing temperature on the cerium crosslinked material, while for the zirconium-crosslinked compound, adsorption decreases as temperature increases from 288 to 308 K, possibly due to a mainly physical process. Fourier-transform infrared (FTIR) spectroscopy indicated that at the pH generated by the adsorbents, the protonated species of these amines plays an important role in the adsorption process. X-ray diffraction analysis showed that the aromatic amines are intercalated into the adsorbents. For any given amine, the cerium-montmorillonite adsorbent shows a higher capacity of adsorption compared with zirconium-montmorillonite adsorbent, so it might be reasonably used in removing aromatic amines from water.

  3. Visible Light Induced Photocatalysis of Cerium Ion Modified Titania Sol and Nanocrystallites

    Institute of Scientific and Technical Information of China (English)

    Yibing XIE; Chunwei YUAN

    2004-01-01

    The cerium ion(Ce4+) doped titania sol and nanocrystallites were prepared by chemical coprecipitation-peptization and hydrothermal synthesis methods, respectively. The X-ray diffraction pattern shows that Ce4+-TiO2 xerogel powder has semicrystalline structure and thermal sintering sample has crystalline structure. Ce4+-TiO2 nanocrystallites are composed of the major anatase phase titania (88.82 wt pct) and a small amount of crystalline cerium titanate.AFM micrograph shows that primary particle size of well-dispersed ultrafine sol particles is below 15 nm in diameter.The particle sizes are 30 nm for xerogel sample and 70 nm for nanocrystallites sample, which is different from the estimated values (2.41 nm and 4.53 nm) by XRD Scherrer's formula. The difference is mainly due to aggregation of nanocrystallites. The experimental results exhibit that photocatalysts of Ce4+-TiO2 sol and nanocrystallites have the ability to photodegrade reactive brilliant red dye (X-3B) under visible light irradiation with the ion-TiO2/VIS/dye system. Moreover, Ce4+ doped titania sol has shown higher efficiency than the nanocrystallites sample in respect of potocatalytic activity. Meanwhile, dye photodegradation mechanisms are proposed to different photocatalytic reaction systems, which are dye photosensitization, ion-dye photosensitization and interband photocatalysis & dye photosensitization with respect to TiO2 nanocrystallites, Ce4+-TiO2 sol and Ce4+-TiO2 nanocrystallites system.

  4. Cerium(III) molybdate nanoparticles: Synthesis, characterization and radionuclides adsorption studies.

    Science.gov (United States)

    Yousefi, Taher; Khanchi, Ali Reza; Ahmadi, Seyed Javad; Rofouei, Mohamad Kazem; Yavari, Ramin; Davarkhah, Reza; Myanji, Behzad

    2012-05-15

    Cerium(III) molybdate nanostructure with average size about 40nm was prepared by adding cerium(III) chloride and ammonium molybdate solutions under varying conditions. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and Brunauere Emmette Teller (BET) techniques. Ion exchange capacity of the sample for potassium ion and distribution coefficients (K(d)) for 23 metal ions were determined, the K(d) values for Tl(I), Pb(II), Th(IV), U(VI), and Cs(I) ions were found to be sufficiently high for their removal from various effluents. The adsorption behavior of the sample towards Cs(I)(134) species were studied. Finally, the binary separation of Dy(III)-U(VI), Sm(III)-Th(IV) and Cs(I)-Rb(I) and removal of Cs(I)(134) from the real sample were successfully achieved.

  5. Cerium and neodymium co-precipitation in molten chloride by wet argon sparging

    Energy Technology Data Exchange (ETDEWEB)

    Vigier, J.F. [CEA, Nuclear Energy Division, RadioChemistry and Processes Department, SMCS/LEPS, F-30207 Bagnols sur Ceze (France); Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Renard, C., E-mail: catherine.renard@ensc-lille.fr [Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France); Laplace, A. [CEA, Nuclear Energy Division, RadioChemistry and Processes Department, SMCS/LEPS, F-30207 Bagnols sur Ceze (France); Lacquement, J. [CEA, Nuclear Energy Division, DTEC/DIR, F-30207 Bagnols sur Ceze (France); Abraham, F. [Unite de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, Univ. Lille Nord de France, ENSCL-USTL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France)

    2013-01-15

    Co-precipitations of cerium (III) and neodymium (III) at 10 wt.% in LiCl-CaCl{sub 2} (30-70 mol%) molten salt at 705 Degree-Sign C have been achieved using an original way of precipitation, wet argon sparging. Several CeCl{sub 3}/NdCl{sub 3} ratios have been studied, and the isolated powders were analyzed using different characterization methods including XRD investigations. The lanthanides precipitation yields have been determined around 99.9% using ICP-AES analysis. XRD demonstrated that the precipitates mainly contained mixed oxychloride (Ce{sub 1-x}Nd{sub x})OCl and a small amount of the mixed oxide Ce{sub 1-y}Nd{sub y}O{sub 2-0.5y}. Calcination of these precipitates has resulted in the cerium and neodymium mixed oxides. For the precipitation with a Ce/Nd = 50/50 ratio, an hydroxychloride Ln(OH){sub 2}Cl and the oxychloride Ce{sup IV}(Nd{sub 0.7}Ce{sub 0.3}){sup III}O{sub 3}Cl have been identified as unexpected intermediate compounds.

  6. Self-healing Performance of Composite Coatings Prepared by Phosphating and Cerium Nitrate Post-sealing

    Institute of Scientific and Technical Information of China (English)

    LIN Bilan; LU Jintang

    2015-01-01

    The phosphated and cerium nitrate post-sealed galvanized steel was ifrstly scratched to expose zinc layer and then placed in neutral salt spray (NSS) chamber for different durations. The microstructure and compositions of the scratches were investigated using SEM and EDS. The phases of the corrosion products were examined through XRD. The self-healing mechanism of the composite coatings was discussed. The experimental results show that the composite coatings have an excellent corrosion resistance. The corrosion products increase with corrosion time and ifnally cover the whole scratch. They contain phosphorous, cerium, oxygen, chloride and zinc, and are ifne needle and exceedingly compact. The composite coatings are favorable self-healing. During corrosion, the self-healing ions such as Ce3+, Ce4+, PO43-, Zn2+ in the composite coatings were dissolved, migrated, recombined, and covered the exposed zinc, impeding zinc corrosion. The self-healing process of the scratches on the composite coatings can be divided into three stages, about 2 h, 4 h, and 24 h, respectively.

  7. Custom cerium oxide nanoparticles protect against a free radical mediated autoimmune degenerative disease in the brain.

    Science.gov (United States)

    Heckman, Karin L; DeCoteau, William; Estevez, Ana; Reed, Kenneth J; Costanzo, Wendi; Sanford, David; Leiter, James C; Clauss, Jennifer; Knapp, Kylie; Gomez, Carlos; Mullen, Patrick; Rathbun, Elle; Prime, Kelly; Marini, Jessica; Patchefsky, Jamie; Patchefsky, Arthur S; Hailstone, Richard K; Erlichman, Joseph S

    2013-12-23

    Cerium oxide nanoparticles are potent antioxidants, based on their ability to either donate or receive electrons as they alternate between the +3 and +4 valence states. The dual oxidation state of ceria has made it an ideal catalyst in industrial applications, and more recently, nanoceria's efficacy in neutralizing biologically generated free radicals has been explored in biological applications. Here, we report the in vivo characteristics of custom-synthesized cerium oxide nanoparticles (CeNPs) in an animal model of immunological and free-radical mediated oxidative injury leading to neurodegenerative disease. The CeNPs are 2.9 nm in diameter, monodispersed and have a -23.5 mV zeta potential when stabilized with citrate/EDTA. This stabilizer coating resists being 'washed' off in physiological salt solutions, and the CeNPs remain monodispersed for long durations in high ionic strength saline. The plasma half-life of the CeNPs is ∼4.0 h, far longer than previously described, stabilized ceria nanoparticles. When administered intravenously to mice, the CeNPs were well tolerated and taken up by the liver and spleen much less than previous nanoceria formulations. The CeNPs were also able to penetrate the brain, reduce reactive oxygen species levels, and alleviate clinical symptoms and motor deficits in mice with a murine model of multiple sclerosis. Thus, CeNPs may be useful in mitigating tissue damage arising from free radical accumulation in biological systems.

  8. Effects of different valences of cerium ion on conformation of Horseradish Peroxidase

    Institute of Scientific and Technical Information of China (English)

    XIANG Li; GE Zhiqiang

    2008-01-01

    Our previous studies demonstrated that Ce4+ could induce reactive oxygen species (ROS) burst as a signal to promote pacilitaxel biosynthesis in suspension cultured Taxus cuspidate cells. To further understand the mechanism of cerium ions inducing ROS burst, circular dichroism (CD), synchronous fluorescence, and electron paramagnetic resonance (EPR) were used to detect them inducing conforma-tional change of horseradish peroxidase (HRF). Horseradish peroxidase activity was reduced by 78% by 0.1 mmol/L Ce4+, whereas it was only reduced by 28% by 0.1 mmol/L Ce3+. Circular dichroism spectra showed that the percentage of transition from helical content and other structure to βstrands andβturns was 23.1 when induced by Ce4+, whereas it was only 13.2 when induced by Ce3+. In synchronous fluorescence spectra, Ce4+ led to red shift and intensity-elevation of tryptophan fluorescence emission maximum, whereas in the case of Ce3+, the results were a contrast to the above. Furthermore, g factor (gx and gy) in electron paramagnetic resonance (EPR) induced by Ce4+ and Ce3+ was significantly different. These results indicated that the different valence of cerium ion induced various conformations of HRP, and Ce4+ was more effective than Ce3+. This suggested that Ce4+ affected the burst of ROS through changing the conformation of oxidoreductase.

  9. FT-IR Studies of Cerium Oxide Nanoparticles and Natural Zeolite Materials

    Directory of Open Access Journals (Sweden)

    Oana Lelia Pop

    2015-05-01

    Full Text Available An emerging topic of our days is nanoscience and nanotechnology successfully applied in the food industry. Characteristics such as size, surface area and morphology can modify the basic properties and the chemical reactivity of the nanomaterials. The breakthrough of innovative materials, processes, and phenomena at the nanoscale, as well as the progress of new experimental and theoretical techniques for research, supply novel opportunities for the expansion of original nanosystems and nanostructured materials. These study examine two types of nanoparticles, namely cerium oxide nanoparticles (CeO2 NP and natural zeolites. In view of the importance of CeO2 NP in various biological applications, the primary objective of this study is to characterise four samples of CeO2 NP in order to understand the role of the synthesis process in the final product. Nanocrystalline natural zeolites are materials with interesting properties which allows them to be used as adjuvant in many therapies. The characterisation of CeO2 NP and two types of natural zeolites using Fourier Transform Infrared (FT-IR spectroscopy is described. Therefore, this study examined two types of nanomaterials, namely cerium oxide nanoparticles and zeolites, for further applications on microorganisms and living cells.

  10. Kinetics of Cerium(IV) Extraction from H(2)SO(4)-HF Medium with Cyanex 923.

    Science.gov (United States)

    Liao, Wuping; Yu, Guihong; Yue, Shantang; Li, Deqian

    2002-03-11

    Studies of the extraction kinetics of cerium(IV) from H(2)SO(4)-HF solutions with Cyanex 923 in n-heptane have been carried out using a constant interfacial area cell with laminar flow. The experimental hydrodynamic conditions were chosen so that the contribution of diffusion to the measured rate of reaction was minimized. The data were analyzed in terms of pseudo-first order constants. The results were compared with those of the system without HF. It was concluded that the addition of HF reduces the activation energy for the forward rate from 46.2 to 36.5 kJ mol(-1) while it has an opposite effect on the activation energy for the reverse process(the activation energy increased from 23.3 to 90.8 kJ mol(-1)). Thus, HF can accelerate the rate of cerium(IV) extraction. At the same time, the extraction rate is controlled by a mixed chemical reaction-diffusion rather than by a chemical reaction alone. A rate equation has also been obtained.

  11. [XPS study on the influence of calcination conditions to cerium ion valence].

    Science.gov (United States)

    Mei, Yan; Yan, Jian-ping; Nie, Zuo-ren

    2010-01-01

    For the system of Ce(NO3)2.6H2O and urea solution during homogeneous precipitation method, X-ray diffraction (XRD), infrared spectrum (IR) and especially X-ray photoelectron spectroscopy (XPS) were used to study and characterize the product structure, variety of cerium ion valence, compound surface character and kernel electronic configurations. The results of XRD and IR showed that calcination temperature had a great effect on the cerium ion valence. The products are orthorhombic Ce2 O(CO3)2.H2O with valence III by using homogeneous precipitation method directly. When heated from the temperature 200 degrees C to 250 degrees C, the product of CeO(CO3)2.H2O with valence VI was finally changed into stable CeO2 with valence IV. XPS was used to study the surface character and kernel electronic configurations of the three different compounds through fine scanning of O(1s), Ce(3d) and Ce(4d) apices, and the results approved that the compounds with different valences are caused by the different valence electronic configurations of the products.

  12. Selective catalytic oxidation of ammonia over copper-cerium composite catalyst.

    Science.gov (United States)

    Lou, Jie-Chung; Hung, Chang-Mao; Yang, Sheng-Fu

    2004-01-01

    This work considers the oxidation of ammonia (NH3) by selective catalytic oxidation (SCO) over a copper (Cu)-cerium (Ce) composite catalyst at temperatures between 150 and 400 degrees C. A Cu-Ce composite catalyst was prepared by coprecipitation of copper nitrate and cerium nitrate at various molar concentrations. This study also considers how the concentration of influent NH3 (500-1000 ppm), the space velocity (72,000-110,000 hr(-1)), the relative humidity (12-18%) and the concentration of oxygen (4-20%) affect the operational stability and the capacity for removing NH3. The effects of the O2 and NH3 content of the carrier gas on the catalyst's reaction rate also are considered. The experimental results show that the extent of conversion of NH3 by SCO in the presence of the Cu-Ce composite catalyst was a function of the molar ratio. The NH3 was removed by oxidation in the absence of Cu-Ce composite catalyst, and approximately 99.2% NH3 reduction was achieved during catalytic oxidation over the Cu-Ce (6:4, molar/molar) catalyst at 400 degrees C with an O2 content of 4%. Moreover, the effect of the initial concentration and reaction temperature on the removal of NH3 in the gaseous phase was also monitored at a gas hourly space velocity of less than 92,000 hr(-1).

  13. Cerium relieving the inhibition of photosynthesis and growth of spinach caused by lead

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Min

    2009-01-01

    Chloroplasts were isolated from spinach cultured in lead chloride-present, Ce3+-administered, cerium chloride-administered lead chloride-present Hoagland's media or that of Hoagland's media. The experimental study demonstrated the effects of cerium (Ce) on distribu-tion of light energy and photochemical activities of spinach chloroplast grown in lead (Pb)-present media. It was observed that Pb2+ signifi-cantly inhibited photosynthesis in spinach, including light absorption, energy transfer from LHCII to photosystem II, excitation energy dis-tribution from photosystem I to photosystem II, and transformation from light energy to electron energy and oxygen evolution of chloroplasts,and decreased spinach growth. However, Ce3+ treatment to pb2+-present chloroplasts could obviously improve light absorption and excitation energy distribution in both photosystems and increase activity of photochemical reaction and oxygen evolution of chloroplasts. The results suggested that Ce3+ under Pb2+ stress could maintain the stability of chloroplast membrane, and improve photosynthesis of spinach chloro-plast, thus promote spinach growth.

  14. Cerium relieving the inhibition of photosynthesis and growth of spinach caused by lead

    Institute of Scientific and Technical Information of China (English)

    ZHOU Min; ZE Yuguan; LI Na; DUAN Yanmei; CHEN Ting; LIU Chao; HONG Fashui

    2009-01-01

    Chloroplasts were isolated from spinach cultured in lead chloride-present, Ce~(3+)-administered, cerium chloride-administered lead chloride-present Hoagland's media or that of Hoagland's media. The experimental study demonstrated the effects of cerium (Ce) on distribu-tion of light energy and photochemical activities of spinach chloroplast grown in lead (Pb)-present media. It was observed that Pb~(2+) signifi-cantly inhibited photosynthesis in spinach, including light absorption, energy transfer from LHCII to photosystem II, excitation energy dis-tribution from photosystem I to photosystem II, and transformation from light energy to electron energy and oxygen evolution of chloroplasts,and decreased spinach growth. However, Ce~(3+) treatment to pb~(2+)-present chloroplasts could obviously improve light absorption and excitation energy distribution in both photosystems and increase activity of photochemical reaction and oxygen evolution of chloroplasts. The results suggested that Ce~(3+) under Pb~(2+) stress could maintain the stability of chloroplast membrane, and improve photosynthesis of spinach chloro-plast, thus promote spinach growth.

  15. Cerium-zinc redox flow battery: Positive half-cell electrolyte studies

    Institute of Scientific and Technical Information of China (English)

    XIE Zhipeng; ZHOU Debi; XIONG Fengjiao; ZHANG Shimin; HUANG Kelong

    2011-01-01

    Experimental work was performed to evaluate the Ce3+/Ce4+ redox couple in methane sulfonic acid (MSA) electrolyte for use in redox flow battery (RFB) technology. The electrochemical behaviour of the Ce3+/Ce4+ in MSA media was investigated using cyclic voltammetry, linear sweep voltammetry, chronoamperometry and rotating disc electrode. The standard rate constant of the Ce3+/Ce4+ redox reaction on graphite electrode in MSA was 4.06x10-4 cm/s. The diffusion coefficient of Ce3+ in MSA was 5.87-6.15x10-6 cm2/s, and was 2.56-2.68x 10-6 cm2/s for Ce4+. The energy efficiency of a cerium-zinc test cell was 74.8%. The high stability of cerium salts in MSA media and relatively fast redox kinetics of the Ce3+/Ce4+ redox reaction at graphite ectrode indicated that the Ce3+/Ce4+ might be well suited for use in RFB technology.

  16. Effect of cerium ion implantation on the oxidation behavior of zircaloy-4 at 500 degree sign C

    CERN Document Server

    Chen, X W; Yu, H R; Zhou, Q G; Chen, B S

    2002-01-01

    In order to investigate the oxidation behavior changes of zircaloy-4 induced by cerium ion implantation using a MEVVA source at an energy of 40 keV with a dose range from 1x10 sup 1 sup 6 to 1x10 sup 1 sup 7 ions/cm sup 2 at the maximum temperature of 130 degree sign C, weight gain curves of the different specimens including as-received zircaloy-4 and cerium-implanted zircaloy-4 were measured after oxidation in air at 500 degree sign C for 100 min. It was obviously found that a significant improvement was achieved in the oxidation behavior of cerium ion implanted zircaloy-4 compared with that of the as-received zircaloy-4. The depth profile of the element composition in the surface region of the samples was obtained by Auger electron spectroscopy, and the valence of the oxides in the scale was analyzed by X-ray photoemission spectroscopy. Glancing angle X-ray diffraction employed to examine the phase transformation in the oxide films showed that the addition of cerium transformed the phase from monoclinic zir...

  17. Effect of rare element cerium on the morphology and corrosion resistance of electro-less Ni-P coatings

    Directory of Open Access Journals (Sweden)

    Fu Chuan-qi

    2015-01-01

    Full Text Available This paper reports an experimental study on the microstructure and corrosion resistance of electro-less Ni-P coatings with increasing content of the rare element cerium (Ce. Surface morphology and the composition of the electro-less Ni-P coatings were studied by scanning electron microscope (SEM, X-ray energy dispersed analysis (EDS and X-ray diffraction analysis (XRD. Hardness and Adhesive force are researched by a HX-200 Vickers diamond indenter micro-hardness tester. Furthermore, we study the adhesive force by using the Revetest scratch tester. We get the possession of Ce amorphous Ni-P coatings which has excellent properties in anti-corrosion. The effect of the rare element cerium concentration on corrosion resistance of the coatings was evaluated in the groundwater immersion test and porosity test, respectively. The results indicated that added little the rare element cerium into the plating bath increased the phosphorus content of the coatings, decreased the corrosion rates, it also decreases the porosity of the amorphous Ni-P coatings. The lowest corrosion rates of the amorphous Ni-P coatings in groundwater immersion test is 4.1 um · h-1, at the rare element cerium concentration of 0.12g · L-1.

  18. A mixed acid based vanadium-cerium redox flow battery with a zero-gap serpentine architecture

    Science.gov (United States)

    Leung, P. K.; Mohamed, M. R.; Shah, A. A.; Xu, Q.; Conde-Duran, M. B.

    2015-01-01

    This paper presents the performance of a vanadium-cerium redox flow battery using conventional and zero-gap serpentine architectures. Mixed-acid solutions based on methanesulfonate-sulfate anions (molar ratio 3:1) are used to enhance the solubilities of the vanadium (>2.0 mol dm-3) and cerium species (>0.8 mol dm-3), thus achieving an energy density (c.a. 28 Wh dm-3) comparable to that of conventional all-vanadium redox flow batteries (20-30 Wh dm-3). Electrochemical studies, including cyclic voltammetry and galvanostatic cycling, show that both vanadium and cerium active species are suitable for energy storage applications in these electrolytes. To take advantage of the high open-circuit voltage (1.78 V), improved mass transport and reduced internal resistance are facilitated by the use of zero-gap flow field architecture, which yields a power density output of the battery of up to 370 mW cm-2 at a state-of-charge of 50%. In a charge-discharge cycle at 200 mA cm-2, the vanadium-cerium redox flow battery with the zero-gap architecture is observed to discharge at a cell voltage of c.a. 1.35 V with a coulombic efficiency of up to 78%.

  19. Influence of hydroxyl content of binders on rheological properties of cerium-gadolinium oxide (CGO) screen printing inks

    DEFF Research Database (Denmark)

    Marani, Debora; Gadea, Christophe; Hjelm, Johan;

    2015-01-01

    vinyl resins) were selected and characterized in solution via viscosimetry method. A high degree of hyper-entanglement was observed for ethyl cellulose polymers, whereas a mitigated effect characterized the two vinyl resins. Cerium-gadolinium oxides (CGO)-based inks, prepared using the selected binders...

  20. [The changes of the motor function of the stomach and the colon under the action of the nanocrystalline cerium dioxide].

    Science.gov (United States)

    Iefimenko, O Iu; Savchenko, Iu O; Falalieieva, T M; Berehova, T V; Shcherbakov, O B; Ivanov, V K; Zholobak, N M; Maliukin, Iu V; Spivak, M Ia

    2014-01-01

    We investigated the effect of nanocrystalline cerium dioxide on parameters of spontaneous and stimulated motility of the stomach and colon in rats. It was found that administration of nanocrystalline cerium dioxide for 10 days increased the amplitude of contractions of stimulated motility in the stomach by 33.0 +/- 2.4% and the frequency of contractions of the colon by 80.3 +/- 7.5%. In this group, the introduction of carbachol also increased the frequency of the contractions by 274.0 +/- 22.9%, compared to the control group. The administration of nanocrystalline cerium dioxide increased the index of motor activity of spontaneous and stimulated motility of the stomach by 19.8 +/- 1.4 and 14.5 +/- 9.0%, respectively. In the colon, the motor activity increased by 14.3 +/- 1.1 and 11.1 +/- 0.8%, respectively. We also found that the nanocrystalline cerium dioxide rebuilt morphological condition of the mucous of the colon.

  1. Germination and early plant development of ten plant species exposed to titanium dioxide and cerium oxide nanoparticles

    Science.gov (United States)

    Ten agronomic plant species were exposed to different concentrations of nano titanium dioxide (nTiO2) or nano cerium oxide (nCeO2) (0, 250, 500 and 1000 mg/L) to examine potential effects on germination and early seedling development. We modified a standard test protocol develop...

  2. The properties of protective oxide scales containing cerium on alloy 800H in oxidizing and oxidizing/sulphidizing environments

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Fransen, T.; Geerdink, B.; Gellings, P.J.; Stroosnijder, M.F.

    1991-01-01

    The corrosion protection of oxide scales formed by electrophoretic deposition in a cerium-containing sol on Alloy 800H, a 32Ni-20Cr steel, followed by firing in air at 1123 K was studied in oxidizing and mixed oxidizing/sulphidizing environments at elevated temperatures. In particular, the influence

  3. Recent advances bioactive 1,2,4-triazole-3-thiones.

    Science.gov (United States)

    Küçükgüzel, Ş Güniz; Çıkla-Süzgün, Pelin

    2015-06-05

    Triazoles are heterocyclic compounds which have a five-membered ring of two carbon atoms and three nitrogen atoms. These structures have been interest in the development of novel compounds with anticonvulsant, antidepressant, antioxidant, anti-inflammatory, analgesic, antinociceptive, antibacterial, antimycobacterial, antifungal, antiviral, anticancer, anti-parasitic, anti-urease and other activities. Therefore, many researchers have synthesized these compounds as target structures and evaluated their biological activities. This review contains various pharmacological activities of 1,2,4-triazole-3-thiones in one place and it is also the milestone for the new research towards this moiety.

  4. Preparation of perfluorinated 1,2,4-oxadiazoles

    Science.gov (United States)

    Kratzer, R. H.; Paciorek, K. J. L.; Ito, T. I.; Rosser, R. W. (Inventor)

    1982-01-01

    Fluorinated alkyl or alkylether 1,2,4 oxadiazole compounds are prepared by cyclizing the corresponding alkyl or alkylether imidoyl amidoximes in vacuo or in an inert atmosphere at a temperature within the range of 40 C to 100 C. for a period of 8 to 144 hours in the presence of an acid compound which can accept ammonia to form a salt. The imidoyl amidoximes usable in this process are either polymeric or nonpolymeric. The products, when polymeric, have excellent heat, chemical and solvent resistance.

  5. MicroRNA-124 (MiR-124 Inhibits Cell Proliferation, Metastasis and Invasion in Colorectal Cancer by Downregulating Rho-Associated Protein Kinase 1(ROCK1

    Directory of Open Access Journals (Sweden)

    Liqing Zhou

    2016-05-01

    Full Text Available Background/Aims: MiR-124 inhibits neoplastic transformation, cell proliferation, and metastasis and downregulates Rho-associated protein kinase (ROCK1 in Colorectal Cancer (CRC. The aim of this study was to further investigate the roles and interactions of ROCK1 and miR-124 and the effects of knockdown of ROCK1and MiR-124 in human Colorectal Cancer (CRC. Methods: Three Colorectal cancer cell lines (HCT116, HT29 and SW620 and one Human Colonic Mucosa Epithelial cell line (NCM460 were studied. The protein expression of ROCK1 was examined by Western-blot and qRT-PCR were performed to examine the expression levels of ROCK1 mRNA and miR-124. Furthermore, We performed transfection of cancer cell line (SW620 with pre-miR-124(mimics, anti-miR-124(inhibitor, ROCK1 siRNA and the control, then observed the affects of ROCK1 protein expression by westen-blot, cell proliferation by EDU (5-ethynyl-2'deoxyuridine assay and expression levels of ROCK1mRNA by qRT-PCR . A soft agar formation assay, Migration and invasion assays were used to determine the effect of regulation of miR-124 and ROCK1, and survivin on the transformation and invasion capability of colorectal cancer cell. Results: MiR-124 expression was significantly downregulated in CRC cell lines compare to normal (P 0.05. ROCK1 mRNA was unaltered in cells transfected with miR-124 mimic and miR-124 inhibitor, compared to normal controls. There was a significant reduction in ROCK1 protein in cells transfected with miR-124 mimic and a significant increase in cells transfected with miR-124 inhibitor (P Conclusions: In conclusion, our results demonstrated that miR-124 not only promoted cancer cell hyperplasia and significantly associated with CRC metastasis and progression, but also downregulated ROCK1 protein expression. More importantly, increased ROCK1 expression or inhibited miR-124 expression may constitute effective new therapeutic strategies for the treatment of renal cancer in the future.

  6. Nanocrystalline cerium dioxide efficacy for prophylaxis of erosive and ulcerative lesions in the gastric mucosa of rats induced by stress.

    Science.gov (United States)

    Golyshkin, Dmytro; Kobyliak, Nazarii; Virchenko, Oleksandr; Falalyeyeva, Tetyana; Beregova, Tetyana; Ostapchenko, Lyudmyla; Caprnda, Martin; Skladany, Lubomir; Opatrilova, Radka; Rodrigo, Luis; Kruzliak, Peter; Shcherbokov, Alexandr; Spivak, Mykola

    2016-12-01

    In our previous works, the important therapeutic properties of nanocrystalline cerium dioxide such as strong antioxidant ability, prebiotical and antibiotic activity were shown. Such properties were obtained due to stabilization of nanoparticles with precise size 3-7nm. Such modification of nanocrystalline cerium dioxide has contributed to its remarkable efficacy and low toxicity. We have carried out the investigation of toxicity of the nanodrug and revealed that in the condition of the acute toxicity test, LD 50 was 2000mg/kg when it was administered per os. This indicator is approximately 1000 times greater than effective dose of the compound that proved the possibility of its usage for humans. Considering the strong antioxidant properties of this substance, we have performed the investigation of the influence of nanocrystalline cerium dioxide on the erosive-ulcerative lesions in gastric mucosa of rats induced by Selye's restraint stress. It was established that the studied compound significantly reduced the lesions area by 58.3% (p<0.05) induced by Selye's restraint stress. The attenuation of inflammation and decrease of lipid peroxidation in the conditions of gastric lesions and prophylactic administration of nanocrystalline cerium dioxide were shown. That was confirmed by the decrease of pro-inflammatory cytokines content (interleukin (IL) 1β, 12B p40) and raise of anti-inflammatory cytokines content (IL-10 and transforming growth factor β). Measurement of lipid peroxidation products has proved the antioxidant properties of nanocrystalline cerium dioxide as it decreased the content of conjugated dienes and thiobarbituric acid active products in the conditions of gastric ulceration induced by stress.

  7. Functional comparison of annexin V analogues labeled indirectly and directly with iodine-124

    Energy Technology Data Exchange (ETDEWEB)

    Dekker, Bronwen [CRUK/UMIST Dept. of Radiochemical Targeting and Imaging, Paterson Inst. for Cancer Research, M20 4BX Manchester (United Kingdom)]|[Dept. of Instrumentation and Analytical Science, Univ. of Manchester Inst. for Science and Technology (United Kingdom)]. E-mail: bdekker@picr.man.ac.uk; Keen, Heather [CRUK/UMIST Dept. of Radiochemical Targeting and Imaging, Paterson Inst. for Cancer Research, M20 4BX Manchester (United Kingdom)]|[Dept. of Instrumentation and Analytical Science, Univ. of Manchester Inst. for Science and Technology, M60 1QD Manchester (United Kingdom); Shaw, David [CRUK/UMIST Dept. of Radiochemical Targeting and Imaging, Paterson Inst. for Cancer Research, M20 4BX Manchester (United Kingdom)]|[CRUK Dept. of Immunology, Paterson Inst. for Cancer Research, M20 4BX Manchester (United Kingdom); Disley, Lynn [CRUK/UMIST Dept. of Radiochemical Targeting and Imaging, Paterson Inst. for Cancer Research, M20 4BX Manchester (United Kingdom); Hastings, David; Julyan, Peter [CRUK/UMIST Dept. of Radiochemical Targeting and Imaging, Paterson Inst. for Cancer Research, M20 4BX Manchester (United Kingdom)]|[North Western Medical Physics, Christie Hospital NHS Trust, M20 4BX Manchester (United Kingdom); Hadfield, John [School of Environment and Life Sciences, Univ. of Salford, M5 4WT Manchester (United Kingdom); Reader, Andrew [Dept. of Instrumentation and Analytical Science, Univ. of Manchester Inst. for Science and Technology, M60 1QD Manchester (United Kingdom); Allan, Donald [Physics and Electronic Unit, Paterson Inst. for Cancer Research, M20 4BX Manchester (United Kingdom); Watson, Alastair [Dept. of Medicine, Univ of Liverpool (United Kingdom); Zweit, Jamal [CRUK/UMIST Dept. of Radiochemical Targeting and Imaging, Paterson Inst. for Cancer Research, M20 4BX Manchester (United Kingdom)]|[Dept. of Instrumentation and Analytical Science, Univ. of Manchester Inst. for Science and Technology (United Kingdom)]. E-mail: jzweit@picr.man.ac.uk

    2005-05-01

    We are interested in imaging cell death in vivo using annexin V radiolabeled with {sup 124}I. In this study, [{sup 124}I]4IB-annexin V and [{sup 124}I]4IB-ovalbumin were made using [{sup 124}I]N-hydroxysuccinimidyl-4-iodobenzoate prepared by iododestannylation of N-hydroxysuccinimidyl-4-(tributylstannyl)benzoate. [{sup 124}I]4IB-annexin V binds to phosphatidylserine-coated microtiter plates and apoptotic Jurkat cells and accumulates in hepatic apoptotic lesions in mice treated with anti-Fas antibody, while [{sup 124}I]4IB-ovalbumin does not. In comparison with {sup 124}I-annexin V, [{sup 124}I]4IB-annexin V has a higher rate of binding to phosphatidylserine in vitro, a higher kidney and urine uptake, a lower thyroid and stomach content uptake, greater plasma stability and a lower rate of plasma clearance. Binding of radioactivity to apoptotic cells relative to normal cells in vitro and in vivo appears to be lower for [{sup 124}I]4IB-annexin V than for {sup 124}I-annexin V.

  8. Banana-shaped 1,2,4-oxadiazoles

    Indian Academy of Sciences (India)

    S I Torgova; T A Geivandova; O Francescangeli; A Strigazzi

    2003-08-01

    3,5-Disubstituted 1,2,4-oxadiazoles are a new type of liquid crystalline (LC) compounds with asymmetrical five-membered heterocycle as a central unit. They have a bent shape and are very convenient model-compounds for studying the dependence of the LC properties on the molecular design. We have also synthesized and investigated ‘banana-shaped’ 1,2,4-oxadiazoles using the ester groups as the linkage units. The new compounds exhibit spontaneous polarization in the smectic phase, even if there is no chiral group in the molecules. Preliminary experimental data suggest the presence of spontaneous polarization in the nematic phase as well. In order to study the structural properties of the LC phases, X-ray diffraction (XRD) measurements on powder samples have been carried out. Based on the XRD data, a model of the structural arrangement of the bent molecules in the smectic phase is provided, which accounts for the macroscopic spontaneous polarization as well as the ferroelectric switching behavior.

  9. Evaluation of {sup 124}I PET/CT and {sup 124}I PET/MRI in the management of patients with differentiated thyroid cancer

    Energy Technology Data Exchange (ETDEWEB)

    Dercle, Laurent; Deandreis, Desiree; Terroir, Marie; Leboulleux, Sophie; Lumbroso, Jean; Schlumberger, Martin [Institut Gustave Roussy and University Paris Saclay, Department of Nuclear Medicine and Endocrine Oncology, Villejuif Cedex (France)

    2016-06-15

    The work of Binse and colleagues points out that there are probably some research perspectives for the use of {sup 124}I PET/ CT and PET/MRI in patients with DTC. It shows that there is no substantial advantage of {sup 124}I PET/MRI over {sup 124}I PET/CT for the detection of tumour lesions in the neck when using similar PET devices. It confirms the superiority of {sup 124}I PET over CT and MRI for the detection of iodine-positive lesions. It demonstrates that the use of a more sensitive PET device and a longer acquisition time leads to the detection of more lesions. {sup 124}I PET is a promising research tool for pretherapy dosimetry, the evaluation of response to {sup 131}I treatment and the staging of recurrent or residual disease. The recognized advantages of MRI are the evaluation of aerodigestive tract lesions and suprahyoid region lesions. The coregistration of MRI and {sup 124}I PET/CT might thus be more convenient than {sup 124}I PET/ MRI (shorter time of acquisition, better cost-effectiveness and more accurate attenuation correction). The benefits of these procedures in terms of patient outcome, and for the clinician and the healthcare system remain to be determined.

  10. Tribological characteristics of monodispersed cerium borate nanospheres in biodegradable rapeseed oil lubricant

    Energy Technology Data Exchange (ETDEWEB)

    Boshui, Chen, E-mail: boshuichen@163.com; Kecheng, Gu; Jianhua, Fang; Jiang, Wu; Jiu, Wang; Nan, Zhang

    2015-10-30

    Graphical abstract: - Highlights: • Monodispersed stearic acid-capped cerium borate composite nanoparticles were prepared by hydrothermal method. Their morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics were also characterized. • The surface-capped cerium borate nanoparticles exhibited excellent dispersing stability in rapeseed oil. As new lubricating additives, they were also outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil in biodegradable rapeseed oil. The results presented in this paper would be of important significance for developing green lubricants and lubricant additives. • The prominent tribological performances of SA/CeBO{sub 3} in rapeseed oil were investigated and attributed to the formation of a composite boundary lubrication film mainly composed of lubricous tribochemical species on the tribo-surfaces. - Abstract: Stearic acid-capped cerium borate composite nanoparticles, abbreviated as SA/CeBO{sub 3}, were prepared by hydrothermal method. The morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics, of SA/CeBO{sub 3} were characterized by scanning electron microscope, energy dispersive X-ray spectrometer, dynamic laser particle size analyzer, X-ray diffraction, and Fourier transform infrared spectrometer, respectively. The friction and wear performances of SA/CeBO{sub 3} as a lubricating additive in a rapeseed oil were evaluated on a four-ball tribo-tester. The tribochemical characteristics of the worn surfaces were investigated by X-ray photoelectron spectroscopy. The results showed that the hydrophobic SA/CeBO{sub 3} were monodispersed nanospheres with an average diameter of 8 nm, and exhibited excellent dispersing stability in rapeseed oil. Meanwhile, SA/CeBO{sub 3} nanospheres were outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil. The prominent

  11. Cerium doped lanthanum halides: fast scintillators for medical imaging; Halogenures de lanthane dopes cerium des scintillateurs rapides pour l'imagerie medicale

    Energy Technology Data Exchange (ETDEWEB)

    Selles, O

    2006-12-15

    This work is dedicated to two recently discovered scintillating crystals: cerium doped lanthanum halides (LaCl{sub 3}:Ce{sup 3+} and LaBr{sub 3}:Ce{sup 3+}).These scintillators exhibit interesting properties for gamma detection, more particularly in the field of medical imaging: a short decay time, a high light yield and an excellent energy resolution. The strong hygroscopicity of these materials requires adapting the usual experimental methods for determining physico-chemical properties. Once determined, these can be used for the development of the industrial manufacturing process of the crystals. A proper comprehension of the scintillation mechanism and of the effect of defects within the material lead to new possible ways for optimizing the scintillator performance. Therefore, different techniques are used (EPR, radioluminescence, laser excitation, thermally stimulated luminescence). Alongside Ce{sup 3+} ions, self-trapped excitons are involved in the scintillation mechanism. Their nature and their role are detailed. The knowledge of the different processes involved in the scintillation mechanism leads to the prediction of the effect of temperature and doping level on the performance of the scintillator. A mechanism is proposed to explain the thermally stimulated luminescence processes that cause slow components in the light emission and a loss of light yield. Eventually the study of afterglow reveals a charge transfer to deep traps involved in the high temperature thermally stimulated luminescence. (author)

  12. Effects of acetic acid on microstructure and electrochemical properties of nano cerium oxide films coated on AA7020-T6 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    H. Hasannejad; T. Shahrabi; M. Aliofkhazraei

    2009-01-01

    Nano cerium oxide films were applied on AA7020-T6 aluminum alloy and the effects of acetic acid concentration on the microstructure and electrochemical properties of the coated samples were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), crack-flee films with well-developed grains were obtained and grain sizes of the films decreased. Elimination of cracks and decreasing grain size of the nano cerium oxide films caused corrosion resistance to increase.

  13. Synthesis of new tetrazene(N-N=N-N)-linked bi(1,2,4-triazole)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The reaction of 4-amino-1,2,4-triazole with sodium dichloroisocyanurate (SDCI) afforded new tetrazene(N-N=N-N)-linked bi(1,2,4-triazole) 2a in excellent yield. Increasing the molar ratio of SDCI to 4-amino- 1,2,4-triazole, the chlorinated product 1,5,5'-trichloro-4,4'-azo- 1,2,4-triazole (2b) was formed. These new compounds have been characterized by MS, 1H NMR, 13C NMR, and elemental analysis.

  14. 124Iodine: A Longer-Life Positron Emitter Isotope—New Opportunities in Molecular Imaging

    Directory of Open Access Journals (Sweden)

    Giuseppe Lucio Cascini

    2014-01-01

    Full Text Available 124Iodine (124I with its 4.2 d half-life is particularly attractive for in vivo detection and quantification of longer-term biological and physiological processes; the long half-life of 124I is especially suited for prolonged time in vivo studies of high molecular weight compounds uptake. Numerous small molecules and larger compounds like proteins and antibodies have been successfully labeled with 124I. Advances in radionuclide production allow the effective availability of sufficient quantities of 124I on small biomedical cyclotrons for molecular imaging purposes. Radioiodination chemistry with 124I relies on well-established radioiodine labeling methods, which consists mainly in nucleophilic and electrophilic substitution reactions. The physical characteristics of 124I permit taking advantages of the higher PET image quality. The availability of new molecules that may be targeted with 124I represents one of the more interesting reasons for the attention in nuclear medicine. We aim to discuss all iodine radioisotopes application focusing on 124I, which seems to be the most promising for its half-life, radiation emissions, and stability, allowing several applications in oncological and nononcological fields.

  15. Porous microspheres of manganese-cerium mixed oxides by a polyvinylpyrrolidone assisted solvothermal method

    Science.gov (United States)

    Schmit, F.; Bois, L.; Chiriac, R.; Toche, F.; Chassagneux, F.; Descorme, C.; Besson, M.; Khrouz, L.

    2017-04-01

    Mixed cerium manganese oxides were synthesized using a polyvinylpyrrolidone (PVP) assisted solvothermal method. Materials obtained after calcination at 400 °C were characterized by X-ray diffraction, scanning and transmission electron microscopies, electron paramagnetic resonance (EPR), Raman spectroscopy, thermal analysis and nitrogen adsorption/desorption isotherms. The influence of the synthesis parameters on the oxide structure, such as the Mn:Ce ratio or the amount of PVP, was discussed. Micrometric spheres of mixed Mn-Ce oxides, resulting from the aggregation of 100 nm porous snowflakes, were successfully synthesized. These snowflakes were formed from the aggregation of smaller oriented crystallites (size 4 nm). The hydrothermal stability of these materials was also investigated.

  16. Highly stable, mesoporous mixed lanthanum-cerium oxides with tailored structure and reducibility

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Shuang; Broitman, Esteban; Wang, Yanan; Cao, Anmin; Veser, Goetz

    2011-05-01

    Pure and mixed lanthanum and cerium oxides were synthesized via a reverse microemulsion-templated route. This approach yields highly homogeneous and phase-stable mixed oxides with high surface areas across the entire range of La:Ce ratios from pure lanthana to pure ceria. Surprisingly, all mixed oxides show the fluorite crystal structure of ceria, even for lanthanum contents as high as 90%. Varying the La:Ce ratio not only allows tailoring of the oxide morphology (lattice parameter, pore structure, particle size, and surface area), but also results in a fine-tuning of the reducibility of the oxide which can be explained by the creation of oxygen vacancies in the ceria lattice upon La addition. Such finely controlled syntheses, which enable the formation of stable, homogeneous mixed oxides across the entire composition range, open the path towards functional tailoring of oxide materials, such as rational catalyst design via fine-tuning of redox activity.

  17. Cerium(IV)-based chemiluminescence of phentolamine sensitized by rhodamine 6G

    Energy Technology Data Exchange (ETDEWEB)

    Liu Weibing; Huang Yuming

    2004-03-24

    A new chemiluminescence (CL) method is proposed for the determination of phentolamine, which is based on the reaction between studied drug and Cerium(IV) (Ce(IV)) in a nitric acid medium and measurement of the CL intensity produced by rhodamine 6G used as a sensitizer. In the optimum conditions, CL intensities are proportional to concentrations of the studied drug over the range 1x10{sup -9}-1x10{sup -6} g/ml with a detection limit of 4x10{sup -10} g/ml. The relative standard deviation (R.S.D.) is 3.4% for 1x10{sup -7} g/ml phentolamine (n=11). The method has been applied to the determination of studied drug in injections and biological fluids with satisfactory results.

  18. Boric Acid as an Accelerator of Cerium Surface Treatment on Aluminum

    Directory of Open Access Journals (Sweden)

    K. Cruz-Hernández

    2014-01-01

    Full Text Available Aluminum pieces are often used in various industrial processes like automotive and aerospace manufacturing, as well as in ornamental applications, so it is necessary to develop processes to protect these materials, processes that can be industrialized to protect the aluminum as well or better than chromate treatments. The purpose of this research is to evaluate boric acid as an accelerator by optimizing its concentration in cerium conversion coatings (CeCC with 10-minute immersion time with a concentration of 0.1 g L−1 over aluminum to protect it. The evaluation will be carried out by measuring anticorrosion properties with electrochemical techniques (polarization resistance, Rp, polarization curves, PC, and electrochemical impedance spectroscopy, EIS in NaCl 3.5% wt. aqueous solution and surface characterization with scanning electron microscopy (SEM.

  19. Effect of cerium on ignition point of AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    Zhao Hongjin; Zhang Yinghui; Kang Yonglin

    2008-01-01

    The surface and interior temperature-time curves of blocky cerium modified AZ91D magnesium alloy were measured during a non-protective heating and melting process. Two inflection points with rapid increase in temperature were found on both curves, which corresponded to the formation of "auliflower" oxide on the surface and the occurrence of flame during melting. These two temperatures are therefore defined as oxidation point and ignition point, respectively.The interior temperature-time curve is similar to that measured on the surface except for a comparable time delay. The oxidation and ignition temperatures increase with Ce content, an average increase of 33℃ and 61℃ was found when Ce addition was about 1.0 wt %. However, the increasing rate of the oxidation and ignition temperature decreases with increasing Ce content. An addition of 0.6wt% Ce is recommended for ignition-resistant AZ91 magnesium alloy.

  20. Effect of cerium on ignition point of AZ91D magnesium alloy

    Directory of Open Access Journals (Sweden)

    Zhao Hongjin

    2008-02-01

    Full Text Available The surface and interior temperature-time curves of blocky cerium modified AZ91D magnesium alloy were measured during a non-protective heating and melting process. Two inflection points with rapid increase in temperature were found on both curves, which corresponded to the formation of “auliflower”oxide on the surface and the occurrence of flame during melting. These two temperatures are therefore defined as oxidation point and ignition point, respectively. The interior temperature-time curve is similar to that measured on the surface except for a comparable time delay. The oxidation and ignition temperatures increase with Ce content, an average increase of 33=and 61= was found when Ce addition was about 1.0 wt %. However, the increasing rate of the oxidation and ignition temperature decreases with increasing Ce content. An addition of 0.6wt% Ce is recommended for ignition-resistant AZ91 magnesium alloy.

  1. Effect of cerium and lanthanum additives on plasma electrolytic oxidation of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    沈德久; 马豪杰; 郭长虹; 蔡景瑞; 李国龙; 何东磊; 杨庆祥

    2013-01-01

    Plasma electrolytic oxidation (PEO) coatings on AZ31 magnesium (Mg) alloy were developed using the aqueous solution with alkaline silicate and sodium hydroxide as a base electrolyte system. The effects of cerium (Ce) nitrate and lanthanum (La) nitrate additives on the voltage response, microstructure, compositions and corrosion resistance of PEO coatings were investigated by scan-ning electron microscopy (SEM), energy-dispersive spectrum (EDS), X-ray diffraction (XRD) and potentiodynamic polarization tests, etc. The results showed that Ce and La additives increased the stable voltage and compactness of the PEO coatings, while, those did not change the compositions of the PEO coatings. The corrosion resistance of the PEO coating obtained in solutions with La nitrate of 0.1 g/L was the best, followed by that with Ce nitrate of 0.1 g/L and that without additives.

  2. Inconsistencies with the single-impurity Anderson model in photoelectron spectra of cerium heavy fermion compounds

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, J.J.; Arko, A.J.; Lawrence, J.; Canfield, P.C.; Fisk, Z.; Bartlett, R.J.; Thompson, J.D.; Smith, J.L. (Los Alamos National Lab., NM (United States))

    1992-04-03

    A series of cerium heavy fermion compounds have been studied in order to check for the systematics with T{sub K} and the temperature dependence of the Kondo resonance predicted by the Kondo model. Neither the systematics nor the temperature dependence is found, the latter primarily determined from a detailed study in CeSi{sub 2}. The qualitative shapes of the features at E{sub F} remain nearly constant irrespectively of T{sub K}, while all the temperature dependence can be explained as resulting from phonon broadening of core-like states as well as Fermi function broadening. In addition, if the d electron contribution to the spectra is subtracted, one obtains a symmetric, lorentzian line shape for the ''main'' 4f peak. (orig.).

  3. Investigation of the Carbon Monoxide Gas Sensing Characteristics of Tin Oxide Mixed Cerium Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Muhammad B. Haider

    2012-02-01

    Full Text Available Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6–21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

  4. Sorptive separation of yttrium and cerium on a weakly basic anionite

    Science.gov (United States)

    Cheremisina, O. V.; Ponomareva, M. A.; Chirkst, D. E.; Lobacheva, O. L.; Shul'gin, I. A.

    2015-01-01

    The sorption of complex yttrium ions with Trilon B onto the weakly basic anionite D-403 in nitrate form from an acidic medium at pH 3 with constant ionic strength (NaNO3, 1 mol/kg) is investigated. A thermodynamic evaluation of the sorption isotherm of anionic yttrium complexes is performed using a method based on the linearization of the equation of the law of active mass, modified for ionic exchange reactions. The ionic exchange constant, the Gibbs free energy of ionic exchange, the capacity of the anionite, and the sorption limit of ethylenediaminetetraacetatoyttrate ions (EDTA yttrate ions) are calculated. Using a frontal version of ion exchange chromatography, cerium and yttrium are separated on D-403 anionite with a fraction of pure yttrium at the column outlet of no less than 30%.

  5. Domain Structure in Calcium-Cerium Fluorocarbonate Minerals, Mianning County, Sichuan Province, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The domain structures in calcium-cerium fluorocarbonate mineral series from a rare earth mineral deposit within an aegirine alkali granite massif in Mianning County, Sichuan Province, China, were studied by means of transmission electron microscopy. Many categories of domain structures in this mineral series were observed and investigated, including the microtwin domains of parisite-6R2 and B2S-6R, the antiphase domains of B2S-2H. The results show that the antiphase domains which are faults along crystal plane (0001) are formed by the displacement of crystal lattice in c* direction and the displacement is 0.471 nm. A new polytype (B4S2-3R) of regular mixed-layer structure with B4S2 type is found in the domain region of mixed-layer structure.

  6. Electrospun cerium nitrate/polymer composite fibres:synthesis, characterization and fibre-division model

    Institute of Scientific and Technical Information of China (English)

    Li Meng-Meng; Long Yun-Ze; Yin Hong-Xing; Zhang Zhi-Ming

    2011-01-01

    Cerium (III)nitrate/poly(vinylpyrrolidone)(Ce(NO3)3/PVP)composite fibres have been prepared by electrospinning. After calcining the composite fibres in air at 500℃, CeO2 nanowires were obtained. The characterizations of the as-spun composite fibres and resultant nanowires have been carried out by a scanning electron microscope (SEM),an infrared spectrometer, an x-ray diffractometer and a fluorescence spectrophotometer. Interestingly, some unusual ribbon-like or twin fibres were observed besides the common fibres with circular or elliptic cross sections. We developed a fibre-division model resulting from Coulomb repulsion and solvent vaporization to interpret the formation of the ribbona or twin fibres, which has been confirmed by the SEM studies. Our results also indicate that the formation of the ribbons or twin fibres is less dependent on operation voltage and work distance.

  7. Dielectric studies on cerium doped BaLa2Ti3O10

    Directory of Open Access Journals (Sweden)

    Parshuram B. Abhange

    2015-12-01

    Full Text Available The BaLa2-xCexTi3O10 samples (with x = 0.2, 0.4, 0.6 and 0.8 were prepared by hydroxide co-precipitation method and finally sintered at 1150 °C. The structure of the prepared samples was characterized by XRD and SEM. The single phase material was confirmed only for the BaLa1.8Ce0.2Ti3O10 ceramics. However, at higher cerium concentration secondary phase was observed. The characteristic plate-like structure, having grains with submicrometer thickness and high aspect ratio, was clearly observed by SEM. The results of dielectric measurement suggest that the appropriate adjustment of doping (with x between 0.2 and 0.8 will give sufficient high dielectric constant at very low loss. The resistivity of samples decreases with increase in temperature indicating the normal semiconducting electrical behaviour.

  8. Valence Control of Ce Ions in Cerium-substituted Yttrium Iron Garnet

    Institute of Scientific and Technical Information of China (English)

    SONG Fengbing; LI Qiang; ZHONG Zhifeng

    2005-01-01

    Cerium-substituted yttrium iron garnet(CexY3-xFe5O12, Ce∶YIG) was prepared via coprecipitation. The structure, morphology, valence state and constituent of Ce ions were investigated respectively. X-ray powder diffraction(XRD) analysis shows that Ce∶YIG was of single cubic YIG phase. The result of X-ray photoelectron spectroscopy(XPS) indicates the Ce ions in Ce∶YIG were in the state of trivalence. Scanning electron microscope(SEM) demonstrates the conglobation of Ce∶YIG particles about 0.2μm scale.The magnetic properties were studied by a vibrating sample magnetometer(VSM) and the result exhibits that substitution of Ce3+ changes the magnetic parameters of YIG. The effects of doping content of Ce ions and synthesis temperature on valence control were discussed in detail.

  9. Nanoscale Hybrid Langmuir-Blodgett Films Based on Cerium-Substituted Heteropolymolybdate and Polyquinoline

    Institute of Scientific and Technical Information of China (English)

    王峥; 柳士忠; 杜祖亮; 胡振纲; 张洪杰

    2003-01-01

    Nanoscale hybrid organic/inorganic Langmuir-Blodgett films of cerium-substituted heteropolymolybdates(Ce-HPMo) and π-conjugated macromolecule poly(1,2-dihydro-2,2,4-trimethyl)quinoline(PQ) were obtained with auxiliary film-forming material stearic acid(SA) or octadecylamine(ODA). The surface pressure-area isotherms illuminate the formation of the hybrid LB films of PQ/ODA/Ce-HPMo and P Q/SA/Ce-HPMo. The different film-forming mechanism was discussed when the different auxiliary film-forming materials were used in the system. The absorption spectra indicate that the molecules of PQ and Ce-HPMo are incorporated into the LB films. Tapping-mode AFM image reveals a granular surface texture of nanosized Ce-substituted heteropolymolybdate. STM image shows that the conductivity is greatly improved after Ce-substituted heteropolymolybdates are incorporated in the films.

  10. Cerium oxide-chitosan based nanobiocomposite for food borne mycotoxin detection

    Science.gov (United States)

    Kaushik, Ajeet; Solanki, Pratima R.; Pandey, M. K.; Ahmad, Sharif; Malhotra, Bansi D.

    2009-10-01

    Cerium oxide nanoparticles (NanoCeO2) and chitosan (CH) based nanobiocomposite film deposited onto indium-tin-oxide coated glass substrate has been used to coimmobilize rabbit immunoglobin (r-IgGs) and bovine serum albumin (BSA) for food borne mycotoxin [ochratoxin-A (OTA)] detection. Electrochemical studies reveal that presence of NanoCeO2 increases effective electro-active surface area of CH-NanoCeO2/indium tin oxide (ITO) nanobiocomposite resulting in high loading of r-IgGs. BSA/r-IgGs/CH-NanoCeO2/ITO immunoelectrode exhibits improved linearity (0.25-6.0 ng/dl), detection limit (0.25 ng/dl), response time (25 s), sensitivity (18 μA/ng dl-1 cm-2), and regression coefficient (r2˜0.997).

  11. Stability and morphology of cerium oxide surfaces in an oxidizing environment: A first-principles investigation

    Science.gov (United States)

    Fronzi, Marco; Soon, Aloysius; Delley, Bernard; Traversa, Enrico; Stampfl, Catherine

    2009-09-01

    We present density functional theory investigations of the bulk properties of cerium oxides (CeO2 and Ce2O3) and the three low index surfaces of CeO2, namely, (100), (110), and (111). For the surfaces, we consider various terminations including surface defects. Using the approach of "ab initio atomistic thermodynamics," we find that the most stable surface structure considered is the stoichiometric (111) surface under "oxygen-rich" conditions, while for a more reducing environment, the same (111) surface, but with subsurface oxygen vacancies, is found to be the most stable one, and for a highly reducing environment, the (111) Ce-terminated surface becomes energetically favored. Interestingly, this latter surface exhibits a significant reconstruction in that it becomes oxygen terminated and the upper layers resemble the Ce2O3(0001) surface. This structure could represent a precursor to the phase transition of CeO2 to Ce2O3.

  12. Effect of CO2 on the Conversion of Isobutane over Iron, Cerium and Molybdenum Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Daifallah Al-Dhayan

    2016-10-01

    Full Text Available A series of cerium and iron mixed oxide catalysts were prepared by thermal decomposition of Fe1.5PMo12O40 and Ce1.5PMo12O40 heteropolyanions mixture. The prepared catalysts have been characterized and tested for the conversion of isobutane in the presence of CO2. Characterization by XRD showed that besides Fe2O3 and CeO2, α-MoO3 was the main phase formed after thermal treatment. The effect of the support, the reaction temperature, and the presence of H2O in the reactant mixture was investigated. It has been found that the support enhanced both the conversion and isobutene selectivity. As for the reaction temperature and addition of water, it has been found that increasing the temperature increased both the conversion and isobutene selectivity, whereas the presence of water increased the isobutene selectivity but decreased the conversion.

  13. Structural Characteristics of Cerium Oxide Nanocrystals Prepared by the Microemulsion Method

    Institute of Scientific and Technical Information of China (English)

    J.Zhang; X.Ju; Z.Y.Wu; T.Liu; T.D.Hu; Y.N.Xie

    2001-01-01

    The aim of this work is to investigate the microstructure development of erium oxide nanocrystal,prepared by the microemulsion process,as a function of annealing temperature in air.Combined with the HRTEM and the thermogravimetric-differential thermal analysis in air.Combined withthe HRTEm and the thremogravimetric-differential thermal analysis(TG-DTA),the XRD patterns reveal that the sample annealed at 623 K is amorphous,and the formation of cerium oxide nanocrystal occurs above 773 K.The local structural and electronic properties in the nanocrystallization process are probed by X-ray absorption spectra (XAS) at the Ce L3 edge.It is found that the phase structure changes from triclinic to cubic (CeO2),and the electroic structure changes from Ce3 to Ce4 upon increasing the annealing temperature.

  14. Effect of Cerium on the Viscosity of Liquid Fe-C Alloy of Eutectic Content

    Institute of Scientific and Technical Information of China (English)

    滕新营; 叶以富; 刘含莲; 王焕荣; 石志强; 耿浩然

    2002-01-01

    The viscosities of liquid Fe-4.30C and Fe-4.30C-Ce alloys were measured by oscillating crucible viscometer. The results show that viscosity of Fe-4.30C alloy changes from 5.50 to 8.30 MPa*s when the liquid is cooled from 1425 ℃ to the melting point. The abnormity of viscosity of Fe-4.30C alloy near the melting point is reasonable due to the formation of graphite. The addition of cerium especially with content higher than 0.21% causes an evidently decrease in viscosity for eutectic alloy resulting from increase of free volume and size decrease of atom cluster in the liquids. It can be concended that the existence of C-Ce compound contributes to the discontinuous of viscosity at 1340~1370 ℃ for the Fe-4.30C-Ce alloy by experinments with differential scanning calorimeter.

  15. Effects of Cerium on Microalloying in Low Sulfur Nb-Ti-Bearing Steel

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The CCT curves of supercooled austenite were investigated by using THERMECMASTOR-Z simulation machine, test samples refined from 50 kg vacuum induction furnace and two-stage controlled rolling in laboratorial condition.Test results show that influence of cerium (Ce) addition in low sulfur Nb-Ti-Bearing steel is as follows: Ce can increase the transformation point tAr3 and tAr1, enlarge the interval of transformation (tAr3-tAr1). Ce moves CCT curves upwards and rightwards, and reduces hardenability. Ce increases bainitic transformation temperature and enlarges interval of bainite formation. With higher cooling rates, Ce changes the martensite from coarse strip to fine strip. It decreases Ms, enhances the trend of lath martensitic structure and limits the formation of lamellar crystal.

  16. Deuterium isotope effect on the induction period of the cerium catalyzed Belousov-Zhabotinsky reaction

    Science.gov (United States)

    Rossi, Federico; Simoncini, Eugenio; Marchettini, Nadia; Tiezzi, Enzo

    2009-02-01

    In this work we present results about the deuterium isotopic effect on the global kinetics of a cerium catalyzed Belousov-Zhabotinsky reaction. A nonlinear dependence of the induction period upon the percentage of deuterated reactants was found in batch conditions. In order to understand this result, we investigated two reaction pathways responsible for the length of the induction period, namely: (a) the reaction between the enolic form of the malonic acid with molecular bromine and (b) the oxidation of malonic acid by the Ce(IV) ion. In both cases we obtained a linear dependence of the kinetic constants on the percentage of deuterated reactants. Nevertheless, by inserting the experimental values in the MBM (Marburg-Budapest-Missoula) model, we were able to qualitatively simulate the observed trend of the induction period.

  17. Label-free electrochemical immunosensor based on cerium oxide nanowires for Vibrio cholerae O1 detection

    Energy Technology Data Exchange (ETDEWEB)

    Tam, Phuong Dinh, E-mail: phuongdinhtam@gmail.com; Thang, Cao Xuan, E-mail: thang.caoxuan@hust.edu.vn

    2016-01-01

    This paper developed a label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application. The CeO{sub 2} nanowires were synthesized by hydrothermal reaction. The immobilization of Anti-V. cholerae O1 onto CeO{sub 2} nanowire-deposited sensor was performed via an amino ester, which was created by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and sulfo-N-hydroxysuccinimide. The electrochemical responses of the immunosensor were studied by electrochemical impedance spectroscopy with [Fe (CN) {sub 6}] {sup 3−/4−} as redox probe. A linear response in electron transfer resistance for cell of V. cholerae O1 concentration was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. The immunosensor sensitivity was 56.82 Ω/CFU·mL{sup −1}. Furthermore, the parameters affecting immunosensor response were also investigated, as follows: pH value, immunoreaction time, incubation temperature, and anti-V. cholerae O1 concentration. - Highlights: • A label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application was developed. • A linear response was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. • The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. • The immunosensor sensitivity was 56.82 Ω/CFU.mL{sup −1}.

  18. Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates

    KAUST Repository

    Naganuma, Tamaki

    2014-01-01

    Abundant oxygen vacancies coexisting with Ce3+ ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce3+ ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce3+ ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce3+ and Ce4+ ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce3+ ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce 3+ ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce3+ ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce 3+ to Ce4+ occurred at 350 °C in air. Highly concentrated Ce3+ ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce 3+ stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce3+ sites. This study also illuminates the potential interaction mechanisms of stable Ce3+ ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. © The Royal Society of Chemistry 2014.

  19. Cerium(III) molybdate nanoparticles: Synthesis, characterization and radionuclides adsorption studies

    Energy Technology Data Exchange (ETDEWEB)

    Yousefi, Taher, E-mail: Taher_yosefy@yahoo.com [NFCRS, Nuclear Science and Technology Institute, Kargher Ave, Tehran (Iran, Islamic Republic of); Tarbiat Moallem University, Mofatteh Ave, Tehran (Iran, Islamic Republic of); Khanchi, Ali Reza; Ahmadi, Seyed Javad [NFCRS, Nuclear Science and Technology Institute, Kargher Ave, Tehran (Iran, Islamic Republic of); Rofouei, Mohamad Kazem [Tarbiat Moallem University, Mofatteh Ave, Tehran (Iran, Islamic Republic of); Yavari, Ramin; Davarkhah, Reza; Myanji, Behzad [NFCRS, Nuclear Science and Technology Institute, Kargher Ave, Tehran (Iran, Islamic Republic of)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer A new inorganic nanoparticles with average size about 40 nm were synthesized by chemical method. Black-Right-Pointing-Pointer The morphology studies reveal existing nanowires among dense nanoparticles. Black-Right-Pointing-Pointer Investigation shows it has high stability in rough media and high affinity for Cs(I), U(VI), and Th(IV). Black-Right-Pointing-Pointer It was used for adsorption of radionuclides and removal of {sup 134}Cs from real sample. Black-Right-Pointing-Pointer These findings are important for evaluating human and environmental risk assessment. - Abstract: Cerium(III) molybdate nanostructure with average size about 40 nm was prepared by adding cerium(III) chloride and ammonium molybdate solutions under varying conditions. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and Brunauere Emmette Teller (BET) techniques. Ion exchange capacity of the sample for potassium ion and distribution coefficients (K{sub d}) for 23 metal ions were determined, the K{sub d} values for Tl(I), Pb(II), Th(IV), U(VI), and Cs(I) ions were found to be sufficiently high for their removal from various effluents. The adsorption behavior of the sample towards Cs(I){sub 134} species were studied. Finally, the binary separation of Dy(III)-U(VI), Sm(III)-Th(IV) and Cs(I)-Rb(I) and removal of Cs(I){sub 134} from the real sample were successfully achieved.

  20. Cerium oxide nanoparticles inhibit the migration and proliferation of gastric cancer by increasing DHX15 expression

    Directory of Open Access Journals (Sweden)

    Xiao YF

    2016-07-01

    Full Text Available Yu-Feng Xiao,1 Jian-Mei Li,2 Su-Min Wang,1 Xin Yong,1 Bo Tang,1 Meng-Meng Jie,1 Hui Dong,1 Xiao-Chao Yang,2 Shi-Ming Yang1 1Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, People’s Republic of China; 2School of Biomedical Engineering, Third Military Medical University, Chongqing, People’s Republic of China Abstract: Gastric cancer is one of the leading causes of tumor-related deaths in the world. Current treatment options do not satisfy doctors and patients, and new therapies are therefore needed. Cerium oxide nanoparticles (CNPs have been studied as a potential therapeutic approach for treating many diseases. However, their effects on human gastric cancer are currently unknown. Therefore, in this study, we aimed to characterize the effects of CNPs on human gastric cancer cell lines (MKN28 and BGC823. Gastric cancer cells were cocultured with different concentrations of CNPs, and proliferation and migration were measured both in vitro and in vivo. We found that CNPs inhibited the migration of gastric cancer cells when applied at different concentrations, but only a relatively high concentration (10 µg/mL of CNPs suppressed proliferation. Furthermore, we found that CNPs increased the expression of DHX15 and its downstream signaling pathways. We therefore provide evidence showing that CNPs may be a promising approach to suppress malignant activity of gastric cancer by increasing the expression of DHX15. Keywords: cerium oxide nanoparticles, gastric cancer, DHX15, p38

  1. Structural and electronic properties of cerium from LDA+U calculations

    Directory of Open Access Journals (Sweden)

    F. Kheradmand

    2008-12-01

    Full Text Available  In this work structural, electronic and magnetic properties of alpha and gamma phases of cerium crystal have been calculated by means of the LDA and LDA+U methods. The equilibrium volume and magnetic moment obtained from the GGA approximation in agreement with the experiment are equal to 27.64 Å3 and 0.00018 µB, respectively. This agreement shows that the 4f electrons in alpha phase are itinerant due to the use of the GGA, where no strong correlations have been yet thaken into account. We have observed that even after applying the GGA+U method with U = 6.1 eV, the density of states of f orbital remains still at Fermi surface. Therefore, in complete accord with the experiment, our results show that the 4f electrons in the alpha phase are not localized. This is the case where the LDA and the GGA approximations could not describe the gamma phase properly. Indeed, physical properties of the gamma phase is consistent with the experiment and could only be reproduced after applying LDA+U method with U = 4.4 eV. In this way, the value of equilibrium volume and magnetic moment calculated for the gamma phase were found to be 34.33 Å3 and 1.15 µB, respectively. After including correlations among 4f electrons the γ-Ce DOS is positioned at its more reasonable place lower than Fermi level compared with the DOS obtained from GGA calculations. Our results, then, show that the 4f electrons in the gamma phase, as opposed to the alpha phase, are localized which is indicative of the fact that gamma cerium is a strongly correlated system. The volume of 11 kbar has been obtained for the pressure of the alpha-gamma phase transition .

  2. The Effect of MicroRNA-124 Overexpression on Anti-Tumor Drug Sensitivity.

    Directory of Open Access Journals (Sweden)

    Shiau-Mei Chen

    Full Text Available MicroRNAs play critical roles in regulating various physiological processes, including growth and development. Previous studies have shown that microRNA-124 (miR-124 participates not only in regulation of early neurogenesis but also in suppression of tumorigenesis. In the present study, we found that overexpression of miR-124 was associated with reduced DNA repair capacity in cultured cancer cells and increased sensitivity of cells to DNA-damaging anti-tumor drugs, specifically those that cause the formation of DNA strand-breaks (SBs. We then examined which DNA repair-related genes, particularly the genes of SB repair, were regulated by miR-124. Two SB repair-related genes, encoding ATM interactor (ATMIN and poly (ADP-ribose polymerase 1 (PARP1, were strongly affected by miR-124 overexpression, by binding of miR-124 to the 3¢-untranslated region of their mRNAs. As a result, the capacity of cells to repair DNA SBs, such as those resulting from homologous recombination, was significantly reduced upon miR-124 overexpression. A particularly important therapeutic implication of this finding is that overexpression of miR-124 enhanced cell sensitivity to multiple DNA-damaging agents via ATMIN- and PARP1-mediated mechanisms. The translational relevance of this role of miR-124 in anti-tumor drug sensitivity is suggested by the finding that increased miR-124 expression correlates with better breast cancer prognosis, specifically in patients receiving chemotherapy. These findings suggest that miR-124 could potentially be used as a therapeutic agent to improve the efficacy of chemotherapy with DNA-damaging agents.

  3. Spectral tunability of cerium photoluminescence in nano sized LaF{sub 3}:Ce{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, T. K.; Suriyamurthy, N., E-mail: igcarsuri@yahoo.com; Panigrahi, B. S.; Venkatraman, B. [Indira Gandhi Centre for Atomic Research, Kalpakkam – 603 102 (India); Sukumar, A. A. [CCCM, Bhabha Atomic Research Centre, Hyderabad (India)

    2015-06-24

    Nano sized LaF{sub 3}:Ce{sup 3+} was synthesized by adopting co-precipitation technique with nominal composition as well as with different molar ratio of reactants La{sup 3+} (Lanthanum) and F{sup −} (Fluoride). All the samples were subjected to X-ray diffraction (XRD), XRF, UV-Vis absorption, and PL characterizations. XRD analysis did not reveal any significant change in the diffraction profile. Particle size variations were observed with respect to change in lanthanum to fluoride molar ratio. An interesting and intense photoluminescence excitation peaks were observed for the samples prepared non-stoichiometrically. The effect of varying nominal reactant composition demonstrates a possibility of introducing tunability in cerium emission in the same host. Life time of cerium has been measured to be in the order of nano seconds.

  4. Ceria nanoparticles vis-à-vis cerium nitrate as corrosion inhibitors for silica-alumina hybrid sol-gel coating

    Science.gov (United States)

    Lakshmi, R. V.; Aruna, S. T.; Sampath, S.

    2017-01-01

    The present work provides a comparative study on the corrosion protection efficiency of defect free sol-gel hybrid coating containing ceria nanoparticles and cerium nitrate ions as corrosion inhibitors. Less explored organically modified alumina-silica hybrid sol-gel coatings are synthesized from 3-glycidoxypropyltrimethoxysilane and aluminium-tri-sec-butoxide. The microemulsion derived nanoparticles and the hybrid coatings are characterized and compared with coatings containing cerium nitrate. Corrosion inhibiting capability is assessed using electrochemical impedance spectroscopy. Scanning Kelvin probe measurements are also conducted on the coatings for identifying the apparent corrosion prone regions. Detailed X-ray photoelectron spectroscopy (XPS) analysis is carried out to comprehend the bonding and corrosion protection rendered by the hybrid coatings.

  5. Preparation and properties of a cerium-containing hydroxyapatite coating on commercially pure titanium by micro-arc oxidation

    Institute of Scientific and Technical Information of China (English)

    HUANG Yong; WANG Yingjun; NING Chengyun; NAN Kaihui; HAN Yong

    2008-01-01

    A porous cerium-containing hydroxyapatite coating on commercially pure titanium was prepared by micro-arc oxidation (MAO) in an electrolytic solution containing calcium acetate, β-glycerol phosphate disodium salt pentahydrate (β-GP), and cerium nitrate. The thickness, phase, composition morphology, and biocompatibility of the oxide coating were characterized by X-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS), and cell culture. The thickness of the MAO film is about 15-25μm, and the coating is porous and uneven, without any apparent interface to the titanium substrates. The results of XRD and EDS show that the porous coating is made up of hydroxyapatite (HA) film containing Ce. The favorable osteoblast cell affinity makes the Ce-HA film have a good biocompatibility. The Ce-HA film is expected to have significant medical applications as dental implants and artificial bone joints.

  6. 34 CFR 668.124 - Interlocutory appeals to the Secretary from rulings of a hearing official.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 3 2010-07-01 2010-07-01 false Interlocutory appeals to the Secretary from rulings of a hearing official. 668.124 Section 668.124 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION...

  7. 13 CFR 124.3 - What definitions are important in the 8(a) BD program?

    Science.gov (United States)

    2010-01-01

    ... functions of the firm. Immediate family member means father, mother, husband, wife, son, daughter, brother... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What definitions are important in the 8(a) BD program? 124.3 Section 124.3 Business Credit and Assistance SMALL BUSINESS...

  8. 7 CFR 1955.124 - Sale with inventory real estate (chattel).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 14 2010-01-01 2009-01-01 true Sale with inventory real estate (chattel). 1955.124... Property Chattel Property § 1955.124 Sale with inventory real estate (chattel). Inventory chattel property may be sold with inventory real estate if a higher aggregate price can be obtained. Proceeds from...

  9. Yeast Interacting Proteins Database: YLR291C, YPL124W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available YPL124W SPC29 Inner plaque spindle pole body (SPB) component, links the central p...rey (0) Prey ORF YPL124W Prey gene name SPC29 Prey description Inner plaque spindle pole body (SPB) component, links

  10. 42 CFR 413.124 - Reduction to hospital outpatient operating costs.

    Science.gov (United States)

    2010-10-01

    ... surgical center approved surgical procedures performed in the hospital outpatient setting under § 413.118.... 413.124 Section 413.124 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH... RENAL DISEASE SERVICES; OPTIONAL PROSPECTIVELY DETERMINED PAYMENT RATES FOR SKILLED NURSING...

  11. 12 CFR 221.124 - Purchase of debt securities to finance corporate takeovers.

    Science.gov (United States)

    2010-01-01

    ... securities to finance corporate takeovers. (a) Petitions have been filed with the Board raising questions as... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Purchase of debt securities to finance corporate takeovers. 221.124 Section 221.124 Banks and Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD...

  12. 40 CFR 124.9 - Administrative record for draft permits when EPA is the permitting authority.

    Science.gov (United States)

    2010-07-01

    ....9 Administrative record for draft permits when EPA is the permitting authority. (a) The provisions... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Administrative record for draft permits when EPA is the permitting authority. 124.9 Section 124.9 Protection of Environment...

  13. 18 CFR 12.4 - Staff administrative responsibility and supervisory authority.

    Science.gov (United States)

    2010-04-01

    ... supervisory authority. (a) Administrative responsibility. The Director of the Office of Energy Projects... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Staff administrative responsibility and supervisory authority. 12.4 Section 12.4 Conservation of Power and Water Resources...

  14. 40 CFR 124.18 - Administrative record for final permit when EPA is the permitting authority.

    Science.gov (United States)

    2010-07-01

    ....18 Administrative record for final permit when EPA is the permitting authority. (a) The Regional... 40 Protection of Environment 21 2010-07-01 2010-07-01 false Administrative record for final permit when EPA is the permitting authority. 124.18 Section 124.18 Protection of Environment...

  15. 10 CFR 1040.124 - Responsibility of the Federal Energy Regulatory Commission.

    Science.gov (United States)

    2010-01-01

    ... be placed in title 18 CFR. Judicial Review ... 10 Energy 4 2010-01-01 2010-01-01 false Responsibility of the Federal Energy Regulatory Commission. 1040.124 Section 1040.124 Energy DEPARTMENT OF ENERGY (GENERAL PROVISIONS) NONDISCRIMINATION...

  16. 13 CFR 124.702 - What types of assistance are available through the 7(j) program?

    Science.gov (United States)

    2010-01-01

    ..., marketing, and operation of small business concerns; and (b) The identification and development of new... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What types of assistance are available through the 7(j) program? 124.702 Section 124.702 Business Credit and Assistance SMALL...

  17. 29 CFR 784.124 - Going to and returning from work.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Going to and returning from work. 784.124 Section 784.124... to and returning from work. The phrase “including the going to and returning from work” relates to... returning from work at processing or refrigerator plants or wholesale establishments....

  18. Cerium-modified doped strontium titanate compositions for solid oxide fuel cell anodes and electrodes for other electrochemical devices

    Science.gov (United States)

    Marina, Olga A [Richland, WA; Stevenson, Jeffry W [Richland, WA

    2010-03-02

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells and electrochemical devices such as solid oxide fuel cells, electrolyzers, sensors, pumps and the like, the compositions comprising cerium-modified doped strontium titanate. The invention also provides novel methods for making and using anode material compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having anodes comprising the compositions.

  19. Study on corrosion resistance of the BTESPT silane cooperating with rare earth cerium on the surface of aluminum-tube

    Institute of Scientific and Technical Information of China (English)

    肖围; 满瑞林; 缪畅; 彭天兰

    2010-01-01

    Bis-3-(triethoxysilyl)propyltetrasulfide(BTESPT) silane-rare earth cerium composite coatings on aluminum-tube were prepared at 60 °C by immersion method.The performance of composite coatings to protect the aluminum-tube against corrosion was investigated with potentiodynamic polarization curves,electrochemical impedance spectroscopy(EIS),and salt spray test(SST).The results of potentiodynamic polarization curves and EIS indicated that the self-corrosion current decreased by two orders of magnitude and the i...

  20. Cerium(Ⅳ) ammonium nitrate catalysed facile and efficient synthesis of polyhydroquinoline derivatives through Hantzsch multicomponent condensation

    Institute of Scientific and Technical Information of China (English)

    Cherkupally Sanjeeva Reddy; Mekala Raghu

    2008-01-01

    A general and convenient practical approach for the synthesis of polyhydroquinoline derivatives has been achieved via one-pot four-component Hantzsch condensation of aromatic aldehydes,dimedone,ethyl acetoacetate and ammonium acetate in the presence of a catalytic amount of cerium(Ⅳ) ammonium nitrate (CAN),in ethanol solvent at ambient temperature.Simple work-up,mild reaction conditions,inexpensive and non-toxic catalyst,and excellent product yields are the advantageous features of this method.

  1. The biological effects of subacute inhalation of diesel exhaust following addition of cerium oxide nanoparticles in atherosclerosis-prone mice

    Energy Technology Data Exchange (ETDEWEB)

    Cassee, Flemming R., E-mail: flemming.cassee@rivm.nl [National Institute for Public Health and the Environment, PO box 1, 3720 BA Bilthoven (Netherlands); Campbell, Arezoo, E-mail: acampbell@westernu.edu [Western University of Health Sciences, Pomona, CA (United States); Boere, A. John F., E-mail: john.boere@rivm.nl [National Institute for Public Health and the Environment, PO box 1, 3720 BA Bilthoven (Netherlands); McLean, Steven G., E-mail: smclean1@staffmail.ed.ac.uk [BHF/University Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh (United Kingdom); Duffin, Rodger, E-mail: Rodger.Duffin@ed.ac.uk [MRC Centre for Inflammation Research, University of Edinburgh, Edinburgh (United Kingdom); Krystek, Petra, E-mail: petra.krystek@philips.com [Philips Innovation Services, Eindhoven (Netherlands); Gosens, Ilse, E-mail: Ilse.gosens@rivm.nl [National Institute for Public Health and the Environment, PO box 1, 3720 BA Bilthoven (Netherlands); Miller, Mark R., E-mail: Mark.Miller@ed.ac.uk [BHF/University Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh (United Kingdom)

    2012-05-15

    Background: Cerium oxide (CeO{sub 2}) nanoparticles improve the burning efficiency of fuel, however, little is known about health impacts of altered emissions from the vehicles. Methods: Atherosclerosis-prone apolipoprotein E knockout (ApoE{sup -/-}) mice were exposed by inhalation to diluted exhaust (1.7 mg/m{sup 3}, 20, 60 or 180 min, 5 day/week, for 4 weeks), from an engine using standard diesel fuel (DE) or the same diesel fuel containing 9 ppm cerium oxide nanoparticles (DCeE). Changes in hematological indices, clinical chemistry, atherosclerotic burden, tissue levels of inflammatory cytokines and pathology of the major organs were assessed. Results: Addition of CeO{sub 2} to fuel resulted in a reduction of the number (30%) and surface area (10%) of the particles in the exhaust, whereas the gaseous co-pollutants were increased (6-8%). There was, however, a trend towards an increased size and complexity of the atherosclerotic plaques following DE exposure, which was not evident in the DCeE group. There were no clear signs of altered hematological or pathological changes induced by either treatment. However, levels of proinflammatory cytokines were modulated in a brain region and liver following DCeE exposure. Conclusions: These results imply that addition of CeO{sub 2} nanoparticles to fuel decreases the number of particles in exhaust and may reduce atherosclerotic burden associated with exposure to standard diesel fuel. From the extensive assessment of biological parameters performed, the only concerning effect of cerium addition was a slightly raised level of cytokines in a region of the central nervous system. Overall, the use of cerium as a fuel additive may be a potentially useful way to limit the health effects of vehicle exhaust. However, further testing is required to ensure that such an approach is not associated with a chronic inflammatory response which may eventually cause long-term health effects.

  2. Mixtures of room temperature ionic liquid/ethanol solutions as electrolytic media for cerium oxide thin layer electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Lair, V., E-mail: virginie-lair@chimie-paristech.f [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575-Chimie Paristech (ENSCP)-Paris, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Sirieix-Plenet, J.; Gaillon, L.; Rizzi, C. [UPMC University Paris 06, UMR 7195, Laboratoire de Physicochimie des Electrolytes, Colloides et Sciences Analytiques (PECSA), F-75005 Paris (France); CNRS, UMR 7195, PECSA, F-75005 Paris (France); ESPCI, UMR 7195, PECSA, F-75005 Paris (France); Ringuede, A. [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575-Chimie Paristech (ENSCP)-Paris, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France)

    2010-12-30

    A cerium oxide thin layer was electrodeposited onto stainless steel, using mixed room temperature ionic liquid (the 1-methyl-3-butylimidazolium bis(trifluoromethyl sulfonyl)imide)/ethanol solutions, as electrolytic medium. The hydrophobic ionic liquid content is one of the main parameters in the morphology control influencing the ceria growth rate and crystallinity. Micro-nano structural properties and electrical behaviour are presented, using XRD, SEM/EDS and impedance spectroscopy, as a function of electrodeposition conditions.

  3. Adsorption kinetics of NO on ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jinghuan; Cao, Feifei; Chen, Songze; Ni, Mingjiang; Gao, Xiang, E-mail: xgao1@zju.edu.cn; Cen, Kefa

    2014-10-30

    Graphical abstract: - Highlights: • Ordered mesoporous carbon (OMC) and Ce-OMC were used for NO adsorption. • The NO adsorption capacity of OMC was two times larger than that of activated carbon. • With the addition of cerium both adsorption capacity and adsorption rate increased. • The pseudo-second-order model was the most suitable model for NO adsorption on OMC. • Intraparticle diffusion was the rate controlling step for NO adsorption. - Abstract: Ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC) were prepared using evaporation-induced self-assembly (EISA) method and used to adsorb NO. N{sub 2} sorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to confirm their structures. The results showed that the ordered and uniform structures were successfully synthesized and with the introduction of cerium pore properties were not significantly changed. The NO adsorption capacity of OMC was two times larger than that of activated carbon (AC). With the introduction of cerium both the adsorption capacity and the adsorption rate were improved. The effects of residence time and oxygen concentration on NO adsorption were also investigated. Oxygen played an important role in the NO adsorption (especially in the form of chemisorption) and residence time had small influence on the NO adsorption capacity. The NO adsorption kinetics was analyzed using pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion models. The results indicated that the NO adsorption process can be divided into rapid adsorption period, slow adsorption period, and equilibrium adsorption period. The pseudo-second-order model was the most suitable model for NO adsorption on OMC and Ce-OMC. The rate controlling step was the intraparticle diffusion together with the adsorption reaction.

  4. The effects of cerium doping concentration on the properties and photocatalytic activity of bimetallic Mo/Ce catalyst

    Science.gov (United States)

    Allaedini, Ghazaleh; Tasirin, Siti Masrinda; Aminayi, Payam

    2016-10-01

    In this study, the characterization and photocatalytic activity of MoO3 nanoparticles doped with various doping concentrations of cerium have been investigated. The Fourier transform infrared (FT-IR) spectra of the prepared catalysts confirmed that MoO3 particles have been successfully doped by cerium. Field emission scanning electron microscopy (FESEM) was performed to visualize the surface morphology of the obtained catalysts. The XRD patterns suggested that the crystallinity of the sample with the lowest doping concentration of 15 mol % was higher in comparison with samples of higher doping concentrations. The volume-averaged crystal sizes of the obtained catalysts were calculated to be 25, 28, and 32 nm for 15, 35, and 60 mol % samples, respectively. The photocatalytic activity along with the reaction kinetics of Ce-doped MoO3 nanoparticles have also been investigated through the dye degradation of methyl orange. The synthesized Ce-doped MoO3 particles with the lowest dopant concentration of 15 mol % exhibited the highest photocatalytic activity for methyl orange dye degradation. It was observed that photo-degradation activity decreased with an increase in the doping concentration of cerium. The predicted rate constants for samples with 15, 35, and 60 mol % doping concentrations were found to be 0.0432, 0.035, and 0.029 min-1, respectively.

  5. Study on cerium-doped nano-TiO2 coatings for corrosion protection of 316 L stainless steel

    Science.gov (United States)

    Li, Suning; Wang, Qian; Chen, Tao; Zhou, Zhihua; Wang, Ying; Fu, Jiajun

    2012-04-01

    Many methods have been reported on improving the photogenerated cathodic protection of nano-TiO2 coatings for metals. In this work, nano-TiO2 coatings doped with cerium nitrate have been developed by sol-gel method for corrosion protection of 316 L stainless steel. Surface morphology, structure, and properties of the prepared coatings were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The corrosion protection performance of the prepared coatings was evaluated in 3 wt% NaCl solution by using electrochemical techniques in the presence and absence of simulated sunlight illumination. The results indicated that the 1.2% Ce-TiO2 coating with three layers exhibited an excellent photogenerated cathodic protection under illumination attributed to the higher separation efficiency of electron-hole pairs and higher photoelectric conversion efficiency. The results also showed that after doping with an appropriate concentration of cerium nitrate, the anti-corrosion performance of the TiO2 coating was improved even without irradiation due to the self-healing property of cerium ions.

  6. High-pressure synthesis and characterization of the first cerium fluoride borate CeB2O4F☆

    Science.gov (United States)

    Hinteregger, Ernst; Wurst, Klaus; Tribus, Martina; Huppertz, Hubert

    2013-01-01

    CeB2O4F is the first cerium fluoride borate, which is exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO3]3− groups. This new cerium fluoride borate was synthesized under high-pressure/high-temperature conditions of 0.9 GPa and 1450 °C in a Walker-type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with eight formula units and the lattice parameters a=821.63(5), b=1257.50(9), c=726.71(6) pm, V=750.84(9) Å3, R1=0.0698, and wR2=0.0682 (all data). The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO3]3− groups. Furthermore, IR spectroscopy, Electron Micro Probe Analysis and temperature-dependent X-ray powder diffraction measurements were performed. PMID:23935215

  7. High-pressure synthesis and characterization of the first cerium fluoride borate CeB2O4F.

    Science.gov (United States)

    Hinteregger, Ernst; Wurst, Klaus; Tribus, Martina; Huppertz, Hubert

    2013-08-01

    CeB2O4F is the first cerium fluoride borate, which is exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO3](3-) groups. This new cerium fluoride borate was synthesized under high-pressure/high-temperature conditions of 0.9 GPa and 1450 °C in a Walker-type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with eight formula units and the lattice parameters a=821.63(5), b=1257.50(9), c=726.71(6) pm, V=750.84(9) Å(3), R1=0.0698, and wR2=0.0682 (all data). The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO3](3-) groups. Furthermore, IR spectroscopy, Electron Micro Probe Analysis and temperature-dependent X-ray powder diffraction measurements were performed.

  8. Study of cerium-promoted rhodium alumina catalyst as a steam reforming catalyst for treatment of spent solvents

    Institute of Scientific and Technical Information of China (English)

    Hee-Chul Yang; Min-Woo Lee; Ho-Sang Hwang; Jei-Kwon Moon; Dong-Yong Chung

    2014-01-01

    This study attempted to develop an appropriate catalyst used for the steam reforming of gasified spent solvents. Rh2O3/ CeO2-Al2O3 catalysts with various CeO2 loadings were prepared and heated at different temperatures of 500 and 800 ºC, and their surface properties were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron mi-croscopy (TEM), temperature programmed reduction (TPR) and Brumauer-Emmett-Teller (BET) analyses. Rhodium existed in the form of Rh2O3, regardless of the sample composition as well as the heating temperature. In the tested range of cerium addition (up to 12 times the rhodium mass), no significant changes in BET surface areas and binding energy corresponding to Rh 3d5/2were observed. Instead, the addition of cerium led to a greatly enhanced dispersion of rhodium nanoparticles, and no agglomeration of rhodium was observed for samples heated even at 800 ºC. Honeycomb monolith rhodium catalysts promoted with cerium were fabricated and tested for the steam reforming of a gasified spent solvent, mainly consisting of butylene (C4H8). The test results suggested that a ce-rium-promoted rhodium catalyst could be used as an appropriate reforming catalyst for treating low-quality non-methane hydrocar-bons without the formation of coke at high temperatures of up to 900 ºC.

  9. A phosphate-dependent shift in redox state of cerium oxide nanoparticles and its effects on catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sanjay; Dosani, Talib; Karakoti, Ajay S.; Kumar, Amit; Seal, Sudipta; Self, William

    2011-10-01

    Cerium oxide nanoparticles (CeNPs) have shown promise as catalytic antioxidants in cell culture and animal models as both superoxide dismutase and catalase mimetics. The reactivity of the cerium (Ce) atoms at the surface of its oxide particle is critical to such therapeutic properties, yet little is known about the potential for a protein or small molecule corona to form on these materials in vivo. Moreover Ce atoms in these active sites have the potential to interact with small molecule anions, peptides, or sugars when administered in culture or animal models. Several nanomaterials have been shown to alter or aggregate under these conditions, rendering them less useful for biomedical applications. In this work we have studied the change in catalytic properties of CeNPs when exposed to various biologically relevant conditions in vitro. We have found that CeNPs are resistant to broad changes in pH and also not altered by incubation in cell culture medium. However to our surprise phosphate anions significantly altered the characteristics of these nanomaterials and shifted the catalytic behavior due to the binding of phosphate anions to cerium. Given the abundance of phosphate in biological systems in an inorganic form, it is likely that the action of CeNPs as a catalyst may be strongly influenced by the local concentration of phosphate in the cells and/or tissues in which it has been introduced.

  10. The cerium magnetic form factor and diffuse polarization in CeRh3B2 as functions of temperature

    Science.gov (United States)

    Givord, F.; Boucherle, J.-X.; Lelièvre-Berna, E.; Lejay, P.

    2004-03-01

    In the compound CeRh3B2, a rather special polarization of the conduction electrons along the c-chains of cerium atoms had been previously reported at low temperatures (Alonso et al 1998 J. Magn. Magn. Mater. 177-181 1048). The distribution of the CeRh3B2 magnetization has now been studied as a function of temperature up to 150 K—that is, above the Curie temperature of 115 K. The magnetization density maps have been obtained from polarized neutron diffraction experiments by using the maximum entropy method. The cerium form factor has also been analysed. Calculations of the form factor including several multiplets are developed and it is shown that it is necessary to take into account the influence of the higher multiplet of the Ce3+ ion. This result is coherent with the observation of a peak at high energy in the inelastic neutron spectra, indicating a very large crystal electric field splitting. Both analyses lead to the same conclusion that, on heating, the diffuse negative magnetization observed at low temperature along the cerium chains disappears at the magnetic ordering temperature. The influence of the second multiplet of the Ce3+ ion could be part of the explanation for the low value of the 4f moment and the large Curie temperature in CeRh3B2.

  11. Effect of cerium addition on catalytic performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    Mengwei Xue; Yuming Zhou; Yiwei Zhang; Xuan Liu; Yongzheng Duan; Xiaoli Sheng

    2012-01-01

    The effect of cerium addition on the catalytic performance of propane dehydrogenation over PtSnNa/ZSM-5 catalyst has been investigated by reaction tests and some physicochemical characterization such as XRD,BET,TEM,XPS.NH3-TPD,H2 chemisorption,TPR and TPO techniques.It has been found that with suitable amount of cerium addition,the platinum dispersion increased,while the carbon deposition tended to be eliminated easily.In these cases,the presence of cerium could not only realize the better distribution of metallic particles on the support,but also strengthen the interactions between Sn species and the support.Additionally,XPS spectra confirmed that more amounts of tin could exist in oxidized form,which was advantageous to the reaction.In our experiments,PtSnNaCe (1.1 wt%)/ZSM-5 catalyst exhibited the best catalytic performance.After running the reaction for 750 h,propane conversion was maintained higher than 30% with the corresponding selectivity to propylene of about 97%.

  12. Adsorption kinetics of NO on ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC)

    Science.gov (United States)

    Chen, Jinghuan; Cao, Feifei; Chen, Songze; Ni, Mingjiang; Gao, Xiang; Cen, Kefa

    2014-10-01

    Ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC) were prepared using evaporation-induced self-assembly (EISA) method and used to adsorb NO. N2 sorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to confirm their structures. The results showed that the ordered and uniform structures were successfully synthesized and with the introduction of cerium pore properties were not significantly changed. The NO adsorption capacity of OMC was two times larger than that of activated carbon (AC). With the introduction of cerium both the adsorption capacity and the adsorption rate were improved. The effects of residence time and oxygen concentration on NO adsorption were also investigated. Oxygen played an important role in the NO adsorption (especially in the form of chemisorption) and residence time had small influence on the NO adsorption capacity. The NO adsorption kinetics was analyzed using pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion models. The results indicated that the NO adsorption process can be divided into rapid adsorption period, slow adsorption period, and equilibrium adsorption period. The pseudo-second-order model was the most suitable model for NO adsorption on OMC and Ce-OMC. The rate controlling step was the intraparticle diffusion together with the adsorption reaction.

  13. Synthesis and antimicrobial activity of chromone-linked 2-pyridone fused with 1,2,4-triazoles, 1,2,4-triazines and 1,2,4-triazepines ring systems

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Tarik El-Sayed; Ibrahim, Magdy Ahmed, E-mail: magdy_ahmed1977@yahoo.co [Ain Shams University, Cairo (Egypt). Faculty of Education. Dept. of Chemistry

    2010-07-01

    Three series of novel fused nitrogen heterocyclic systems such as 1,2,4-triazolo[1,5-a ] pyridines (5-7 and 9), pyrido[1,2-b][1,2,4]triazines (10, 11, 13 and 15), and pyrido[1,2-b][1,2,4]triazepines (17, 18, 20 and 22) linked with a chromone moiety were synthesized from the key intermediate 1,6-diamino-(6-chloro-4-oxo-4H-chromen-3-yl)-2-oxo-1,2-dihydropyridine-3,5- dicarbonitrile (4) with some electrophilic reagents. The structures of the novel compounds were established by elemental analyses and spectral data. All the products were also screened in vitro for their antimicrobial activity. Compounds 7, 9 and 15 showed the highest activities when compared with the reference drugs. (author)

  14. A SNP site in pri-miR-124 changes mature miR-124 expression but no contribution to Alzheimer's disease in a Mongolian population.

    Science.gov (United States)

    Qi, Lu; Hu, Yi; Zhan, Ying; Wang, Jing; Wang, Bing-Bing; Xia, Hong-Fei; Ma, Xu

    2012-04-25

    Increasing evidence shows that single nucleotide polymorphisms (SNPs) or mutations in microRNAs (miRNAs) sequence may affect the processing and function of miRNAs and participate in the occurrence of diseases. Although many SNPs of miRNAs were found, their functions in the pathological process of nerve cells were only just emerging. In the present study, the effect of the SNP of one neuronal miRNA, miR-124, on miRNA biogenesis and human genetic disease was investigated using in vitro cell line model and Alzheimer's disease (AD) in the Mongolian population. Bioinformatics prediction showed that a common G/C polymorphism designated rs531564 was found in the pri-miR-124 and the G allele changed the formation of a ring-shaped structure in the predicted secondary structure of the pri-miRNA for miR-124-1. Northern blot and real-time PCR analysis showed that the amount of mature miR-124 from the C/G heterozygosity of rs531564 was increased compared with the CC or GG homozygosity of rs531564. The expression of mature miR-124 from GG homozygosity was also higher than that from CC homozygosity. But in an association study of AD patients and controls, neither genotype nor allele distribution difference was found in AD patients compared with controls. Collectively, the present study is the first to evaluate the relationship between miR-124 and AD in the Mongolian population. SNP rs531564 of miR-124 may not represent a risk factor in the development of AD among Mongolian population.

  15. 老年癫痫124例临床研究%Clinical study on 124 cases of elderly epilepsy

    Institute of Scientific and Technical Information of China (English)

    赵洪利; 李剑

    2015-01-01

    Objective:To explore the clinical characteristics and treatment methods of elderly epilepsy.Methods:124 patients with elderly epilepsy were selected from January 2013 to August 2014.As the clinical study objects,the patients were divided into the primary epilepsy group in 32 cases and the secondary epilepsy group in 92 cases according to the etiology.The patients in two groups were given antiepileptic drug monotherapy.The treatment effects of two groups were compared.Results:The treatment total effective rate of the primary epilepsy group was 78.13%,and the treatment total effective rate of the secondary epilepsy group was 89.13%.The treatment effect of the secondary epilepsy group was much better than that of the primary epilepsy group,and the difference was statistically significant(P<0.05).Conclusion:Secondary epilepsy is the main disease type of elderly epilepsy,at the same time as the etiology is definite,so the treatment effect is better when giving antiepileptic drug monotherapy.%目的:探讨老年癫痫病的临床特点及治疗方法。方法:2013年1月-2014年8月收治老年癫痫患者124例,作为临床研究对象,根据病因将患者分为原发性癫痫组32例和继发性癫痫组92例。给予两组患者抗癫痫药物单药治疗,比较两组患者的治疗效果。结果:原发性癫痫组治疗总有效率78.13%,继发性癫痫组治疗总有效率89.13%,继发性癫痫组治疗效果明显优于原发性癫痫组,差异具有统计学意义(P<0.05)。结论:继发性癫痫是老年癫痫的主要发病类型,同时由于病因明确,因此在给予抗癫痫药物单药治疗时取得的治疗效果更好。

  16. High-spin {gamma}-ray spectroscopy of {sup 124}Ba, {sup 124}Xe and {sup 125}Xe

    Energy Technology Data Exchange (ETDEWEB)

    Al-Khatib, Ali

    2008-08-18

    rotational bands loose collectivity and, finally, when all nucleons outside the core have their spins aligned, the bands terminate. In the framework of this thesis, extensive spectroscopic investigations of three nuclei of the A {proportional_to}125 region, {sup 124}Ba, {sup 124}Xe and {sup 125}Xe, have been performed. These nuclei have been studied with the largest spectrometers available, Euroball and Gammasphere. The previously known level schemes of these nuclei have been extended substantially, both in the low- and high-spin regions. Many new rotational bands could be established. Lifetimes have been measured for several of the long large-deformation bands. The rotational structures, shape co-existence and band termination at high spins have been investigated. (orig.)

  17. Cytotoxicity and antibacterial activity of gold-supported cerium oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Suresh Babu K

    2014-11-01

    Full Text Available K Suresh Babu,1,† M Anandkumar,1,† TY Tsai,2 TH Kao,2 B Stephen Inbaraj,2 BH Chen2,31Centre for Nano Sciences and Technology, Madanjeet School of Green Energy Technologies, Pondicherry University, Kalapet, India; 2Department of Food Science, 3Graduate Institute of Medicine, Fu Jen University, Taipei, Taiwan†These authors contributed equally to this workBackground: Cerium oxide nanoparticles (CeO2 have been shown to be a novel therapeutic in many biomedical applications. Gold (Au nanoparticles have also attracted widespread interest due to their chemical stability and unique optical properties. Thus, decorating Au on CeO2 nanoparticles would have potential for exploitation in the biomedical field. Methods: In the present work, CeO2 nanoparticles synthesized by a chemical combustion method were supported with 3.5% Au (Au/CeO2 by a deposition-precipitation method. The as-synthesized Au, CeO2, and Au/CeO2 nanoparticles were evaluated for antibacterial activity and cytotoxicity in RAW 264.7 normal cells and A549 lung cancer cells. Results: The as-synthesized nanoparticles were characterized by X-ray diffraction, scanning and transmission electron microscopy, and ultraviolet-visible measurements. The X-ray diffraction study confirmed the formation of cubic fluorite-structured CeO2 nanoparticles with a size of 10 nm. All synthesized nanoparticles were nontoxic towards RAW 264.7 cells at doses of 0–1,000 µM except for Au at >100 µM. For A549 cancer cells, Au/CeO2 had the highest inhibitory effect, followed by both Au and CeO2 which showed a similar effect at 500 and 1,000 µM. Initial binding of nanoparticles occurred through localized positively charged sites in A549 cells as shown by a shift in zeta potential from positive to negative after 24 hours of incubation. A dose-dependent elevation in reactive oxygen species indicated that the pro-oxidant activity of the nanoparticles was responsible for their cytotoxicity towards A549 cells. In

  18. Freshwater dispersion stability of PAA-stabilised cerium oxide nanoparticles and toxicity towards Pseudokirchneriella subcapitata

    Energy Technology Data Exchange (ETDEWEB)

    Booth, Andy, E-mail: andy.booth@sintef.no [SINTEF Materials and Chemistry, Trondheim N-7465 (Norway); Størseth, Trond [SINTEF Materials and Chemistry, Trondheim N-7465 (Norway); Altin, Dag [BioTrix, Trondheim N-7022 (Norway); Fornara, Andrea; Ahniyaz, Anwar [German Federal Institute for Risk Assessment (BfR), Department of Product Safety, Berlin (Germany); Jungnickel, Harald; Laux, Peter; Luch, Andreas [SP Chemistry, Materials and Surfaces, Drottning Kristinas vag 45, SE-11686 Stockholm (Sweden); Sørensen, Lisbet [SINTEF Materials and Chemistry, Trondheim N-7465 (Norway)

    2015-02-01

    An aqueous dispersion of poly (acrylic acid)-stabilised cerium oxide (CeO{sub 2}) nanoparticles (PAA-CeO{sub 2}) was evaluated for its stability in a range of freshwater ecotoxicity media (MHRW, TG 201 and M7), with and without natural organic matter (NOM). In a 15 day dispersion stability study, PAA-CeO{sub 2} did not undergo significant aggregation in any media type. Zeta potential varied between media types and was influenced by PAA-CeO{sub 2} concentration, but remained constant over 15 days. NOM had no influence on PAA-CeO{sub 2} aggregation or zeta potential. The ecotoxicity of the PAA-CeO{sub 2} dispersion was investigated in 72 h algal growth inhibition tests using the freshwater microalgae Pseudokirchneriella subcapitata. PAA-CeO{sub 2} EC{sub 50} values for growth inhibition (GI; 0.024 mg/L) were 2–3 orders of magnitude lower than pristine CeO{sub 2} EC{sub 50} values reported in the literature. The concentration of dissolved cerium (Ce{sup 3+}/Ce{sup 4+}) in PAA-CeO{sub 2} exposure suspensions was very low, ranging between 0.5 and 5.6 μg/L. Free PAA concentration in the exposure solutions (0.0096–0.0384 mg/L) was significantly lower than the EC{sub 10} growth inhibition (47.7 mg/L) value of pure PAA, indicating that free PAA did not contribute to the observed toxicity. Elemental analysis indicated that up to 38% of the total Cerium becomes directly associated with the algal cells during the 72 h exposure. TOF-SIMS analysis of algal cell wall compounds indicated three different modes of action, including a significant oxidative stress response to PAA-CeO{sub 2} exposure. In contrast to pristine CeO{sub 2} nanoparticles, which rapidly aggregate in standard ecotoxicity media, PAA-stabilised CeO{sub 2} nanoparticles remain dispersed and available to water column species. Interaction of PAA with cell wall components, which could be responsible for the observed biomarker alterations, could not be excluded. This study indicates that the increased

  19. Preparation,characterization and photocatalytic activities of boron-and cerium-codoped TiO2

    Institute of Scientific and Technical Information of China (English)

    WEI Chao-hai; TANG Xin-hu; LIANG Jie-rong; TAN Shu-ying

    2007-01-01

    Boron- and cerium-codoped TiO2 photocatalysts were synthesized using modified sol-gel reaction process and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), particle size distribution (PSD), diffuse reflectance spectra (DRS), and Brunauer-Emmett-Teller (BET). The photocatalytic activities were evaluated by monitoring the degradation of dye Acid Recd B (ARB). The results showed that the prepared photocatalysts were mixed oxides mainly consisting of titania, ceria, and boron oxide. The structure of TiO2 could be transformed from amorphous to anatase and then to rutile by increasing calcination temperature; the transformation being accompanied by the growth of particle size without any obvious change in phase structure of CeO2. The XPS of B1.6Ce1.0-TiO2 prepared at 500℃ showed that a few boron atoms incorporated into titania and ceria lattice, whereas others existed as B2O3. Cerium ions existed in two states, Ce3+ and Ce4+, and the atomic ratio of Ce3+/Ce4+ was 1.86. When boron and cerium were doped, the UV-Vis adsorption band wavelength showed an obvious shift toward the visible range (≤526 nm). As the atomic ratio of Ce/Ti increased to 1.0, the absorbance edge wavelength also increased to 481 nm. The absorbance edge wavelength decreased for higher cerium doping levels (Ce/Ti = 2.0),. The particles size ranged from 122 to 255 nm with a domain at 168 nm (39.4%). The degradation of ARB dye indicated that the photocatalytic activities of boron- and cerium-codoped TiO2 were much higher than those of P25 (a standard TiO2 powder). The activities increased as the boron doping increased, whereas decreased when the Ce/Ti atomic ratio was greater than 0.5. The optimum atomic ratio of B/Ti and Ce/Ti was 1.6 and 0.5, respectively.

  20. Effects of amorphous silica coating on cerium oxide nanoparticles induced pulmonary responses

    Science.gov (United States)

    Ma, Jane; Mercer, Robert R.; Barger, Mark; Schwegler-Berry, Diane; Cohen, Joel M.; Demokritou, Philip; Castranova, Vincent

    2015-01-01

    Recently cerium compounds have been used in a variety of consumer products, including diesel fuel additives, to increase fuel combustion efficiency and decrease diesel soot emissions. However, cerium oxide (CeO2) nanoparticles have been detected in the exhaust, which raises a health concern. Previous studies have shown that exposure of rats to nanoscale CeO2 by intratracheal instillation (IT) induces sustained pulmonary inflammation and fibrosis. In the present study, male Sprague–Dawley rats were exposed to CeO2 or CeO2 coated with a nano layer of amorphous SiO2 (aSiO2/CeO2) by a single IT and sacrificed at various times post-exposure to assess potential protective effects of the aSiO2 coating. The first acellular bronchoalveolar lavage (BAL) fluid and BAL cells were collected and analyzed from all exposed animals. At the low dose (0.15 mg/kg), CeO2 but not aSiO2/CeO2 exposure induced inflammation. However, at the higher doses, both particles induced a dose-related inflammation, cytotoxicity, inflammatory cytokines, matrix metalloproteinase (MMP)-9, and tissue inhibitor of MMP at 1 day post-exposure. Morphological analysis of lung showed an increased inflammation, surfactant and collagen fibers after CeO2 (high dose at 3.5 mg/kg) treatment at 28 days post-exposure. aSiO2 coating significantly reduced CeO2-induced inflammatory responses in the airspace and appeared to attenuate phospholipidosis and fibrosis. Energy dispersive X-ray spectroscopy analysis showed Ce and phosphorous (P) in all particle-exposed lungs, whereas Si was only detected in aSiO2/CeO2-exposed lungs up to 3 days after exposure, suggesting that aSiO2 dissolved off the CeO2 core, and some of the CeO2 was transformed to CePO4 with time. These results demonstrate that aSiO2 coating reduce CeO2-induced inflammation, phospholipidosis and fibrosis. PMID:26210349

  1. Interactive effects of cerium oxide and diesel exhaust nanoparticles on inducing pulmonary fibrosis

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jane Y.C., E-mail: jym1@cdc.gov [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Young, Shih-Houng; Mercer, Robert R.; Barger, Mark; Schwegler-Berry, Diane [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States); Ma, Joseph K. [School of Pharmacy, West Virginia University, Morgantown, WV 26506 (United States); Castranova, Vincent [Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505 (United States)

    2014-07-15

    Cerium compounds have been used as a fuel-borne catalyst to lower the generation of diesel exhaust particles (DEPs), but are emitted as cerium oxide nanoparticles (CeO{sub 2}) along with DEP in the diesel exhaust. The present study investigates the effects of the combined exposure to DEP and CeO{sub 2} on the pulmonary system in a rat model. Specific pathogen-free male Sprague–Dawley rats were exposed to CeO{sub 2} and/or DEP via a single intratracheal instillation and were sacrificed at various time points post-exposure. This investigation demonstrated that CeO{sub 2} induces a sustained inflammatory response, whereas DEP elicits a switch of the pulmonary immune response from Th1 to Th2. Both CeO{sub 2} and DEP activated AM and lymphocyte secretion of the proinflammatory cytokines IL-12 and IFN-γ, respectively. However, only DEP enhanced the anti-inflammatory cytokine IL-10 production in response to ex vivo LPS or Concanavalin A challenge that was not affected by the presence of CeO{sub 2}, suggesting that DEP suppresses host defense capability by inducing the Th2 immunity. The micrographs of lymph nodes show that the particle clumps in DEP + CeO{sub 2} were significantly larger than CeO{sub 2} or DEP, exhibiting dense clumps continuous throughout the lymph nodes. Morphometric analysis demonstrates that the localization of collagen in the lung tissue after DEP + CeO{sub 2} reflects the combination of DEP-exposure plus CeO{sub 2}-exposure. At 4 weeks post-exposure, the histological features demonstrated that CeO{sub 2} induced lung phospholipidosis and fibrosis. DEP induced lung granulomas that were not significantly affected by the presence of CeO{sub 2} in the combined exposure. Using CeO{sub 2} as diesel fuel catalyst may cause health concerns. - Highlights: • DEP induced acute lung inflammation and switched immune response from Th1 to Th2. • DEP induced lung granulomas were not affected by the presence of CeO{sub 2}. • CeO{sub 2} induced sustained lung

  2. Micro RNA-124a Regulates Lipolysis via Adipose Triglyceride Lipase and Comparative Gene Identification 58

    Directory of Open Access Journals (Sweden)

    Suman K. Das

    2015-04-01

    Full Text Available Lipolysis is the biochemical pathway responsible for the catabolism of cellular triacylglycerol (TG. Lipolytic TG breakdown is a central metabolic process leading to the generation of free fatty acids (FA and glycerol, thereby regulating lipid, as well as energy homeostasis. The precise tuning of lipolysis is imperative to prevent lipotoxicity, obesity, diabetes and other related metabolic disorders. Here, we present our finding that miR-124a attenuates RNA and protein expression of the major TG hydrolase, adipose triglyceride lipase (ATGL/PNPLA2 and its co-activator comparative gene identification 58 (CGI-58/ABHD5. Ectopic expression of miR-124a in adipocytes leads to reduced lipolysis and increased cellular TG accumulation. This phenotype, however, can be rescued by overexpression of truncated Atgl lacking its 3'UTR, which harbors the identified miR-124a target site. In addition, we observe a strong negative correlation between miR-124a and Atgl expression in various murine tissues. Moreover, miR-124a regulates the expression of Atgl and Cgi-58 in murine white adipose tissue during fasting as well as the expression of Atgl in murine liver, during fasting and re-feeding. Together, these results point to an instrumental role of miR-124a in the regulation of TG catabolism. Therefore, we suggest that miR-124a may be involved in the regulation of several cellular and organismal metabolic parameters, including lipid storage and plasma FA concentration.

  3. Experimental determination of water activity for binary aqueous cerium(III) ionic solutions: application to an assessment of the predictive capability of the binding mean spherical approximation model.

    Science.gov (United States)

    Ruas, Alexandre; Simonin, Jean-Pierre; Turq, Pierre; Moisy, Philippe

    2005-12-08

    This work is aimed at a description of the thermodynamic properties of actinide salt solutions at high concentration. The predictive capability of the binding mean spherical approximation (BIMSA) theory to describe the thermodynamic properties of electrolytes is assessed in the case of aqueous solutions of lanthanide(III) nitrate and chloride salts. Osmotic coefficients of cerium(III) nitrate and chloride were calculated from other lanthanide(III) salts properties. In parallel, concentrated binary solutions of cerium nitrate were prepared in order to measure experimentally its water activity and density as a function of concentration, at 25 degrees C. Water activities of several binary solutions of cerium chloride were also measured to check existing data on this salt. Then, the properties of cerium chloride and cerium nitrate solutions were compared within the BIMSA model. Osmotic coefficient values for promethium nitrate and promethium chloride given by this theory are proposed. Finally, water activity measurements were made to examine the fact that the ternary system Ce(NO3)3/HNO3/H2O and the quaternary system Ce(NO3)3/HNO3/N2H5NO3/H2O may be regarded as "simple solutions" (in the sense of Zdanovskii and Mikulin).

  4. Biogenic unmodified gold nanoparticles for selective and quantitative detection of cerium using UV-vis spectroscopy and photon correlation spectroscopy (DLS).

    Science.gov (United States)

    Priyadarshini, E; Pradhan, N; Panda, P K; Mishra, B K

    2015-06-15

    The ability of self-functionalized biogenic GNPs towards highly selective colorimetric detection of rare earth element cerium is being reported for the first time. GNPs underwent rapid aggregation on addition of cerium indicated by red shift of SPR peak followed by complete precipitation. Hereby, this concept of co-ordination of cerium ions onto the GNP surface has been utilized for detection of cerium. The remarkable capacity of GNPs to sensitively detect Ce without proves beneficial compared to previous reports of colorimetric sensing. MDL was 15 and 35 ppm by DLS and UV-vis spectroscopy respectively, suggesting DLS to be highly sensitive and a practical alternative in ultrasensitive detection studies. The sensing system showed a good linear fit favouring feasible detection of cerium in range of 2-50 ppm. Similar studies further showed the superior selectivity of biogenic GNPs compared to chemically synthesized counterparts. The sensing system favours on-site analysis as it overcomes need of complex instrumentation, lengthy protocols and surface modification of GNP.

  5. Recovery of Cerium Dioxide from Spent Glass-Polishing Slurry and Its Utilization as a Reactive Sorbent for Fast Degradation of Toxic Organophosphates

    Directory of Open Access Journals (Sweden)

    Pavel Janoš

    2015-01-01

    Full Text Available The recovery of cerium (and possibly other rare earth elements from the spent glass-polishing slurries is rather difficult because of a high resistance of polishing-grade cerium oxide toward common digestion agents. It was shown that cerium may be extracted from the spent polishing slurries by leaching with strong mineral acids in the presence of reducing agents; the solution may be used directly for the preparation of a ceria-based reactive sorbent. A mixture of concentrated nitric acid and hydrogen peroxide was effective in the digestion of partially dewatered glass-polishing slurry. After the removal of undissolved particles, cerous carbonate was precipitated by gaseous NH3 and CO2. Cerium oxide was prepared by a thermal decomposition of the carbonate precursor in an open crucible and tested as reactive sorbent for the degradation of highly toxic organophosphate compounds. The samples annealed at the optimal temperature of approximately 400°C exhibited a good degradation efficiency toward the organophosphate pesticide fenchlorphos and the nerve agents soman and VX. The extraction/precipitation procedure recovers approximately 70% of cerium oxide from the spent polishing slurry. The presence of minor amounts of lanthanum does not disturb the degradation efficiency.

  6. MicroRNA-124 inhibits cellular proliferation and invasion by targeting Ets-1 in breast cancer.

    Science.gov (United States)

    Li, Wentao; Zang, Wenqiao; Liu, Pei; Wang, Yuanyuan; Du, Yuwen; Chen, Xiaonan; Deng, Meng; Sun, Wencong; Wang, Lei; Zhao, Guoqiang; Zhai, Baoping

    2014-11-01

    MicroRNAs (miRNAs) are small non-coding RNAs that, by targeting certain messenger RNAs (mRNAs) for translational repression or cleavage, can regulate the expression of these genes. In addition, miRNAs may also function as oncogenes and tumor-suppressor genes, as the abnormal expression of miRNAs is associated with various human tumors. However, the effects of the expression of miR-124 in breast cancer remain unclear. The present study was conducted to study the expression of miR-124 in breast cancer, paying particular attention to miR-124's relation to the proliferation, invasion, and apoptosis in breast cancer cell MCF-7 and MDA-MB-231. Real-time quantitative RT-PCR (qRT-PCR) was performed to identify miR-124 that was down-regulated in breast cancer tissues. We also showed E26 transformation specific-1 (Ets-1) and miR-124 expression levels in breast cancer tissues that were associated with lymph node metastases. With transfected synthetic miR-124 agomir into MCF-7 and MDA-MB-231, a significant reduction (P Ets-1 as a potential major target gene of miR-124, and the result showed that miR-124 can bind to putative binding sites within the Ets-1 mRNA 3' untranslated region (UTR) to reduce its expression. Based on these findings, we propose that miR-124 and Ets-1 may serve as a therapeutic agent in breast cancer.

  7. TREATMENT AND RESOURCE REUSE OF 1,2,4-ACID PRODUCING EFFLUENT WITH MACROPOROUS POLYMERIC ADSORBENT

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The treatment and resource reuse of 1,2,4-acid producing wastewater by self-mademacroporous adsorption resin ND,A-107 was studied in this paper. Optimum adsorption anddesorption process parameters were acquired by systematically study. The polymeric resin NDA-10 7indicated good adsorption & desorption of 1,2, 4-acid in the wastewater. The removal efficiency of1,2,4-acid, CODer is about 78%, 72% respectively. It is evident that this adsorption process is anefficient treatment method for 1,2,4-acid producing wastewater. At the same time, the accumulationand resource reuse of l,2, 4-acid can be realized in this process.

  8. 33 CFR 100.124 - Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York.

    Science.gov (United States)

    2010-07-01

    ... South Bay Cross Bay Swim, Great South Bay, New York. 100.124 Section 100.124 Navigation and Navigable... NAVIGABLE WATERS § 100.124 Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York... swimmer or safety craft on the swim event race course bounded by the following points: Starting Point...

  9. 13 CFR 124.513 - Under what circumstances can a joint venture be awarded an 8(a) contract?

    Science.gov (United States)

    2010-01-01

    ... joint venture be awarded an 8(a) contract? 124.513 Section 124.513 Business Credit and Assistance SMALL...) Business Development Contractual Assistance § 124.513 Under what circumstances can a joint venture be... the purpose of performing one or more specific 8(a) contracts. (2) A joint venture agreement...

  10. 42 CFR 124.515 - Compliance alternative for community health centers, migrant health centers and certain National...

    Science.gov (United States)

    2010-10-01

    ..., migrant health centers and certain National Health Service Corps sites. 124.515 Section 124.515 Public... Unable To Pay § 124.515 Compliance alternative for community health centers, migrant health centers and... migrant health center under section 329 of the Act is in substantial compliance with the terms...

  11. Simultaneous oxidation and adsorption of As(III) from water by cerium modified chitosan ultrafine nanobiosorbent.

    Science.gov (United States)

    Zhang, Lingfan; Zhu, Tianyi; Liu, Xin; Zhang, Wenqing

    2016-05-05

    Since most existing arsenic removal adsorbents are difficult to effectively remove arsenite (As(III)), an urgent need is to develop an efficient adsorbent for removing As(III) from contaminated water. In this study, a novel ultrafine nanobiosorbent of cerium modified chitosan (Ce-CNB) with simultaneous oxidation and adsorption As(III) performance has been successfully developed. The resulting Ce-CNB with or without As(III) adsorption was characterized by FTIR, XRD, SEM, EDS, TEM, EMI and XPS analysis. Batch of adsorption experiments were performed to investigate the effects of various conditions on the As(III) adsorption. The adsorption behaviors were well described by the Langmuir isotherm and the pseudo-second-order kinetic model, with the maximum adsorption capacities of 57.5 mg g(-1). The adsorption mechanisms for As(III) were (i) formed monodentate and bidentate complexes between hydroxyl groups and arsenite; and (ii) partial As(III) oxidized to As(V) followed by simultaneously adsorbed on the surface of Ce-CNB. This novel nanocomposite can be reused while maintaining a high removal efficiency and can be applied to treat 5.8L of As(III)-polluted water with the effluent concentration lower than the World Health Organization standard, which suggests its great potential to remove As(III) from contaminated water.

  12. Press or pulse exposures determine the environmental fate of cerium nanoparticles in stream mesocosms.

    Science.gov (United States)

    Baker, Leanne F; King, Ryan S; Unrine, Jason M; Castellon, Benjamin T; Lowry, Gregory V; Matson, Cole W

    2016-05-01

    Risk-assessment models indicate that stream ecosystems receiving municipal wastewater effluent may have the greatest potential for exposure to manufactured nanoparticles. The authors determined the fate of cerium oxide (CeO2 ) nanoparticles in outdoor stream mesocosms using 1) 1-time pulse addition of CeO2 nanoparticles, representative of accidental release, and 2) continuous, low-level press addition of CeO2 nanoparticles, representative of exposure via wastewater effluent. The pulse addition led to rapid nanoparticle floc formation, which appeared to preferentially deposit on periphyton in low-energy areas downstream from the location of the input, likely as a result of gravitational sedimentation. Floc formation limited the concentration of suspended nanoparticles in stream water to press addition of nanoparticles led to higher suspended nanoparticle concentrations (77% of target) in stream water, possibly as a result of stabilization of suspended nanoparticles through interaction with dissolved organic carbon. Smaller nanoparticle aggregates appeared to preferentially adsorb to stream surfaces in turbulent sections, where Ce concentrations were highest in the press, likely a result of stochastic encounter with the surface. Streams receiving wastewater effluent containing nanoparticles may lead to exposure of aquatic organisms over a greater spatial extent than a similar amount of nanoparticles from an accidental release. Exposure models must take into account these mechanisms controlling transport and depositional processes.

  13. Effect of cerium on photosynthetic characteristics of soybean seedling exposed to supplementary ultraviolet-B radiation

    Institute of Scientific and Technical Information of China (English)

    LIANG Chan-juan; HUANG Xiao-hua; ZHOU Qing

    2006-01-01

    Effects of cerium (Ce3+) on photosynthetic characteristics were investigated by hydroponics under laboratory conditions when soybean seedlings were exposed to two levels of supplementary UV-B radiation. UV-B radiation badly inhibited the photosynthesis in soybean seedling, leading to a reduction in net photosynthetic rate (Ph), Hill reaction activity, light saturated photosynthetic rate (Ps) and apparent quanta yield (AQY), as well as the CO2 and light saturated photosynthetic rate (Pm) and carboxulation efficiency (CE). On the contrary, Ce obviously promoted the photosynthesis of plants by increasing Hill reaction activity, accelerating electron transport and photophosphorylation, and enhancing carboxylation efficiency. For Ce+UV-B treatments,the values of photosynthetic parameters were still lower than those of the control, but obviously higher than those of UV-B treatment.The results indicated that Ce alleviated the inhibition of UV-B radiation on the photosynthesis in soybean seedling to a certain extent.In correlating of Pn with Hill activity, AQY and CE, we found that the changes of photosynthetic rate were mainly influenced by the regulating effect of Ce on Hill activity and AQY at low level (0.15 W/m2) of UV-B radiation, but were dominated by the regulating effect of Ce on CE at high level (0.45 W/m2). Thus, Ce could regulate many aspects in photosynthesis of soybean seedling under UV-B stress. The regulating mechanism was close related with the dosage of UV-B radiation.

  14. Ultrastructural Interactions and Genotoxicity Assay of Cerium Dioxide Nanoparticles on Mouse Oocytes

    Directory of Open Access Journals (Sweden)

    Blandine Courbiere

    2013-10-01

    Full Text Available Cerium dioxide nanoparticles (CeO2 ENPs are on the priority list of nanomaterials requiring evaluation. We performed in vitro assays on mature mouse oocytes incubated with CeO2 ENPs to study (1 physicochemical biotransformation of ENPs in culture medium; (2 ultrastructural interactions with follicular cells and oocytes using Transmission Electron Microscopy (TEM; (3 genotoxicity of CeO2 ENPs on follicular cells and oocytes using a comet assay. DNA damage was quantified as Olive Tail Moment. We show that ENPs aggregated, but their crystal structure remained stable in culture medium. TEM showed endocytosis of CeO2 ENP aggregates in follicular cells. In oocytes, CeO2 ENP aggregates were only observed around the zona pellucida (ZP. The comet assay revealed significant DNA damage in follicular cells. In oocytes, the comet assay showed a dose-related increase in DNA damage and a significant increase only at the highest concentrations. DNA damage decreased significantly both in follicular cells and in oocytes when an anti-oxidant agent was added in the culture medium. We hypothesise that at low concentrations of CeO2 ENPs oocytes could be protected against indirect oxidative stress due to a double defence system composed of follicular cells and ZP.

  15. Copper-cerium oxides supported on carbon nanomaterial for preferential oxidation of carbon monoxide

    Institute of Scientific and Technical Information of China (English)

    高美怡; 江楠; 赵宇宏; 徐长进; 苏海全; 曾尚红

    2016-01-01

    The CuxO-CeO2/Fe@CNSs, CuxO-CeO2/MWCNTs-Co and CuxO-CeO2/MWCNTs-Ni catalysts were prepared by the im-pregnation method and characterized by transmission electron microscopy, scanning electron microscopy, X-ray powder diffrac-tion, H2-temperature programmed reduction and N2 adsorption-desorption techniques. It was found that the Fe nanoparticles were encapsulated into the multi-layered carbon nanospheres (CNSs). However, the multi-wall carbon nanotubes (MWCNTS) were generated on the Co/Al2O3 and Ni/Al2O3 precursor. The addition of carbon nanomaterial as supports could improve structural properties and low-temperature activity of the CuO-CeO2 catalyst, and save the used amount of metal catalysts in the temperature range with high selectivity for CO oxidation. The copper-cerium oxides supported on carbon nanomaterial had good resistence to H2O and CO2.

  16. RM1 Semiempirical Quantum Chemistry: Parameters for Trivalent Lanthanum, Cerium and Praseodymium.

    Directory of Open Access Journals (Sweden)

    José Diogo L Dutra

    Full Text Available The RM1 model for the lanthanides is parameterized for complexes of the trications of lanthanum, cerium, and praseodymium. The semiempirical quantum chemical model core stands for the [Xe]4fn electronic configuration, with n =0,1,2 for La(III, Ce(III, and Pr(III, respectively. In addition, the valence shell is described by three electrons in a set of 5d, 6s, and 6p orbitals. Results indicate that the present model is more accurate than the previous sparkle models, although these are still very good methods provided the ligands only possess oxygen or nitrogen atoms directly coordinated to the lanthanide ion. For all other different types of coordination, the present RM1 model for the lanthanides is much superior and must definitely be used. Overall, the accuracy of the model is of the order of 0.07Å for La(III and Pr(III, and 0.08Å for Ce(III for lanthanide-ligand atom distances which lie mostly around the 2.3Å to 2.6Å interval, implying an error around 3% only.

  17. Prediction of yttrium, lanthanum, cerium, and neodymium leaching recovery from apatite concentrate using artificial neural networks

    Institute of Scientific and Technical Information of China (English)

    E. Jorjani; A.H. Bagherieh; Sh. Mesroghli; S. Chehreh Chelgani

    2008-01-01

    The assay and recovery of rare earth elements (REEs) in the leaching process is being determined using expensive analytical methods: inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectroscopy (ICP-MS). A neural network model to predict the effects of operational variables on the lanthanum, cerium, yttrium, and neodymium recovery in the leaching of apatite concentrate is presented in this article. The effects of leaching time (10 to 40 min),pulp densities (30% to 50%), acid concentrations (20% to 60%), and agitation rates (100 to 200 r/min), were investigated and optimized on the recovery of REEs in the laboratory at a leaching temperature of 60οC. The obtained data in the laboratory optimization process were used for training and testing the neural network. The feed-forward artificial neural network with a 4-5-5-1 arrangement was capable of estimating the leaching recovery of REEs. The neural network predicted values were in good agreement with the experimental results. The correlations of R=1 in training stages, and R=0.971, 0.952, 0.985, and 0.98 in testing stages were a result of Ce, Nd, La, and Y recovery prediction respectively, and these values were usually acceptable. It was shown that the proposed neural network model accurately reproduced all the effects of the operation variables, and could be used in the simulation of a leaching plant for REEs.

  18. Recent advances of cerium oxide nanoparticles in synthesis, luminescence and biomedical studies:a review

    Institute of Scientific and Technical Information of China (English)

    何立莹; 苏玉民; 蒋兰宏; 石士考

    2015-01-01

    Nanostructured cerium oxide (CeO2) commonly known as nanoceria is a rare earth metal oxide, which plays a technologi-cally important role due to its versatile applications as automobile exhaust catalysts, oxide ion conductors in solid oxide fuel cells, electrode materials for gas sensors, ultraviolet absorbents and glass-polishing materials. However, nanoceria has little or weak lumi-nescence, and therefore its uses in high-performance luminescent devices and biomedical areas are limited. In this review, we present the recent advances of nanoceria in the aspects of synthesis, luminescence and biomedical studies. The CeO2 nanoparticles can be synthesized by solution-based methods including co-precipitation, hydrothermal, microemulsion process, sol-gel techniques, combus-tion reaction and so on. Achieving controlled morphologies and enhanced luminescence efficiency of nanoceria particles are quite es-sential for its potential energy- and environment-related applications. Additionally, a new frontier for nanoceria particles in biomedi-cal research has also been opened, which involves low toxicity, retinopathy, biosensors and cancer therapy aspects. Finally, the sum-mary and outlook on the challenges and perspectives of the nanoceria particles are proposed.

  19. Preparation and Biocompatible Surface Modification of Redox Altered Cerium Oxide Nanoparticle Promising for Nanobiology and Medicine

    KAUST Repository

    Nanda, Himansu

    2016-11-03

    The biocompatible surface modification of metal oxide nanoparticles via surface functionalization technique has been used as an important tool in nanotechnology and medicine. In this report, we have prepared aqueous dispersible, trivalent metal ion (samarium)-doped cerium oxide nanoparticles (SmCNPs) as model redox altered CNPs of biological relevance. SmCNP surface modified with hydrophilic biocompatible (6-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxy}-hexyl) triethoxysilane (MEEETES) were prepared using ammonia-induced ethylene glycol-assisted precipitation method and were characterized using a variety of complementary characterization techniques. The chemical interaction of functional moieties with the surface of doped nanoparticle was studied using powerful 13C cross polarization magic angle sample spinning nuclear magnetic resonance spectroscopy. The results demonstrated the production of the extremely small size MEEETES surface modified doped nanoparticles with significant reduction in aggregation compared to their unmodified state. Moreover, the functional moieties had strong chemical interaction with the surface of the doped nanoparticles. The biocompatible surface modification using MEEETES should also be extended to several other transition metal ion doped and co-doped CNPs for the production of aqueous dispersible redox altered CNPs that are promising for nanobiology and medicine.

  20. Role of cerium, lanthanum, and strontium additions in an Al-Si-Mg (A356) alloy

    Energy Technology Data Exchange (ETDEWEB)

    Nabawy, Ahmed M.; Samuel, Agnes M.; Samuel, Fawzy H. [Universite du Quebec, Chicoutimi (Canada). Dept. des Sciences Appliquees; Alkahtani, Saleh A.; Abuhasel, Khaled A. [Salman Bin Abdulaziz Univ., Riyadh (Saudi Arabia). Mechanical Engineering Dept.

    2016-05-15

    The effects of individual and combined additions of cerium (Ce), lanthanum (La), and strontium (Sr) on the eutectic modification and solidification characteristics of an Al-Si-Mg (A356) aluminum alloy were investigated using optical microscopy and thermal analysis techniques. Addition of Ce, La, and Sr resulted in different depression levels of the eutectic nucleation temperature and eutectic growth undercooling, generating modified eutectic structures exhibiting different levels of modification. Microstructural results showed that the best modification levels using individual additions were achieved by Sr which produced a fine fibrous eutectic structure, followed by La, which produced a refined lamellar structure, with Ce providing the lowest level of modification. On the other hand, a combined addition of Ce and Sr provided the highest modification level, with the production of a very fine fibrous eutectic silicon structure. In general, the addition of Sr helped to further increase the refinement obtained in the alloys containing La or Ce + La additions. In the latter alloy, the main intermetallic phases observed were La(Al,Si){sub 2} and Al{sub 20}(La,Ce)Ti{sub 2}Si. The improved modification levels were found to be proportional to the depression in the eutectic nucleation temperature and the eutectic growth undercooling. A high cooling rate also improved the modification level by at least one level.

  1. Enhanced hydrogen desorption property of MgH{sub 2} with the addition of cerium fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Huai-Jun, E-mail: huaijun.lin.489@s.kyushu-u.ac.jp [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Matsuda, Junko [International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); Li, Hai-Wen [International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395 (Japan); Zhu, Min [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); China–Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou 510640 (China); Akiba, Etsuo [Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395 (Japan); International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University, Fukuoka 819-0395 (Japan)

    2015-10-05

    Highlights: • Activation energy of MgH{sub 2} desorption is remarkably reduced with the dopant of CeF{sub 4}. • The improvement might be attributed to new Ce–F–Mg species at the CeF{sub 4}/MgH{sub 2} interface. • Easy electron transfer induced from the high valence Ce-cation benefits MgH{sub 2} desorption. - Abstract: Hydrogen desorption property of MgH{sub 2} doped with cerium fluorides with different valences prepared using ball milling has been studied. CeF{sub 4} is catalytically active for hydrogen desorption of MgH{sub 2}. Hydrogen desorption temperature and apparent activation energy of MgH{sub 2} are significantly reduced with dopant of 2 mol% of CeF{sub 4}, which might be attributed to the formation of a new Ce–F–Mg specie at the CeF{sub 4}/MgH{sub 2} interface and the easy electron transfer induced from the high valence Ce-cation. The apparent activation energy of hydrogen desorption of MgH{sub 2} is reduced from ∼160 kJ/mol to ∼110 kJ/mol with the dopant of CeF{sub 4}.

  2. Effect of the phosphorous/cerium ratio in the properties of sintered Ce-monazite

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Teresa [CIEMAT, Materials For Fusion, Avda. Complutense 22, 28040 Madrid (Spain)], E-mail: teresa.hernandez@ciemat.es; Martin, Piedad [CIEMAT, Materials For Fusion, Avda. Complutense 22, 28040 Madrid (Spain)

    2008-10-20

    Three Ce-phosphates were prepared by the precipitation method containing different P/Ce ratio. It has been observed that an excess of phosphorous considerably increases the amount of glassy phase surrounding the monazite grains in the ceramic body and produces the decomposition at high temperatures (over 1400 deg. C). This glassy phase is related with the metaphosphate Ce(PO{sub 3}){sub 3}. On the other hand, an excess of cerium yields the massive precipitation of CeO{sub 2} that appears in the microstructure perfectly distributed into the monazite matrix, but the material remains stable up to 1600 deg. C. In the equimolar composition, an exaggerated grain growth can be observed joined to microcracking. Optical properties and hardness were measured for the three materials and are clearly related with the Ce{sup 3+} presence and the crystalline phase in the material, respectively. The intermediate phases found during heating are discussed and these phases are related to the final characteristics for each material.

  3. Preparation of Nano-TiO2 Doped with Cerium and Its Photocatalytic Activity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Cerium-doped titanium dioxide nano-powders were prepared through the sol-gel method and the compound samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis diffuse reflectance spectra (DRS). The photocatalytic activity was evaluated by photocatalytic degradation of phenol in water. The results of XRD, TEM, and DRS show that pure TiO2 and Ce-doped TiO2 powder crystallines are a mixture of anatase and rutile;the doping can retard the development of the grain size of TiO2 and decrease the diameter of TiO2 from more than 20nm of pure TiO2 to about 10 nm;the doped TiO2 can improve the light absorption of TiO2 and suitable doping content tends to move the DRS spectrum of TiO2 towards visible light, but too much doping is not good for the light absorption ability.The results of the photocatalytic experiments show that doping with Ce content of 0.08 % ~ 0.4 % can increase the photocatalytic activity of TiO2;however, doping with Ce content of 0.5 % ~ 2.5 % can significantly decrease the photocatalytic activity of TiO2. The favorite doping content is 0.4 % in the range of our experiments.

  4. The low-aluminium cast iron of reduced silicon content treated with cerium mischmetal

    Directory of Open Access Journals (Sweden)

    M. S. Soiński

    2008-07-01

    Full Text Available The work presents the effect of cerium mischmetal used in quantities of 0.1 and 0.2 wt-% and ferrosilicon used in quantities from 0.5% to 1.5% on the alloy matrix and the shape of graphite precipitates in the low-aluminium cast iron from seven heats, basing on the examination of its structure. The hypereutectic cast iron of the relatively high carbon content (4.0÷4.2% at the prior-to-treatment silicon and manganese content equal to ca. 0.6% and ca. 0.04%, respectively, has been examined.It has been found that the performed treatment leads to the change in the alloy matrix from the nearly almost pearlitic to the ferritic-pearlitic one accompanied by changes in the shape of graphite precipitates. Due to applying both of the mentioned substances in the above stated amounts the graphite precipitates in cast iron have taken the shape of nodular and vermicular ones, and no presence of flake graphite has been revealed. A quantitative analysis of the performed treatment i.e. determining the fractions of graphite precipitates of different shapes has been possible by means of a computer image analyser.

  5. Preparation and evaluation of cerium oxide-bovine hydroxyapatite composites for biomedical engineering applications.

    Science.gov (United States)

    Gunduz, O; Gode, C; Ahmad, Z; Gökçe, H; Yetmez, M; Kalkandelen, C; Sahin, Y M; Oktar, F N

    2014-07-01

    The fabrication and characterization of bovine hydroxyapatite (BHA) and cerium oxide (CeO2) composites are presented. CeO2 (at varying concentrations 1, 5 and 10wt%) were added to calcinated BHA powder. The resulting mixtures were shaped into green cylindrical samples by powder pressing (350MPa) followed by sintering in air (1000-1300°C for 4h). Density, Vickers microhardness (HV), compression strength, scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies were performed on the products. The sintering behavior, microstructural characteristics and mechanical properties were evaluated. Differences in the sintering temperature (for 1wt% CeO2 composites) between 1200 and 1300°C, show a 3.3% increase in the microhardness (564 and 582.75HV, respectively). Composites prepared at 1300°C demonstrate the greatest compression strength with comparable results for 5 and 10wt% CeO2 content (106 and 107MPa) which are significantly better than those for 1wt% and those that do not include any CeO2 (90 and below 60MPa, respectively). The results obtained suggest optimal parameters to be used in preparation of BHA and CeO2 composites, while also highlighting the potential of such materials in several biomedical engineering applications.

  6. Spectrophotometric determination of H(2)-receptor antagonists via their oxidation with cerium(IV).

    Science.gov (United States)

    Darwish, Ibrahim A; Hussein, Samiha A; Mahmoud, Ashraf M; Hassan, Ahmed I

    2008-01-01

    A simple, accurate and sensitive spectrophotometric method has been developed and validated for determination of H(2)-receptor antagonists: cimetidine, famotidine, nizatidine and ranitidine hydrochloride. The method was based on the oxidation of these drugs with cerium(IV) in presence of perchloric acid and subsequent measurement of the excess Ce(IV) by its reaction with p-dimethylaminobenzaldehyde to give a red colored product (lambda(max) at 464nm). The decrease in the absorption intensity of the colored product (DeltaA), due to the presence of the drug was correlated with its concentration in the sample solution. Different variables affecting the reaction were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9990-0.9994) were found between DeltaA values and the concentrations of the drugs in a concentration range of 1-20microgml(-1). The assay limits of detection and quantitation were 0.18-0.60 and 0.54-1.53microgml(-1), respectively. The method was validated, in terms of accuracy, precision, ruggedness and robustness; the results were satisfactory. The proposed method was successfully applied to the determination of the investigated drugs in pure and pharmaceutical dosage forms (recovery was 98.3-102.6+/-0.57-1.90%) without interference from the common excipients. The results obtained by the proposed method were comparable with those obtained by the official methods.

  7. Toxic Effects of Lanthanum, Cerium, Chromium and Zinc on Potamogeton Malaianus

    Institute of Scientific and Technical Information of China (English)

    Wang Xue; Shi Guoxin; Xu Qinsong; Wang Chuntao

    2005-01-01

    The toxic effects of rare earth elements such as lanthanum, cerium and heavy metal elements such as chromium, zinc on Potamogeton malaianus Miq. were studied. The results show that the contents of chlorophyll and soluble protein increase to a certain degree and then decrease under La3+, Ce3+, Zn2+ stress, while there is a constantly dropping tendency under Cr6+ stress. The four ions have different effects on protective enzyme systems of Potamogeton malaianus. They can induce rises of the activities of catalase (CAT) and peroxides (POD) at lower concentration, however, with the increase of ions concentration, the activities decline. The change of SOD activity is exactly opposite to that of CAT and POD activity. It falls at first and rises later. An increasing tendency of MDA content appears with the increasing concentration. The toxicities of La3+, Zn2+, Ce3+ and Cr6+ become more serious in the order. The lethal concentration of Cr6+ to Potamogeton malaianus ranges from 0.5 to 1 mg·L-1, that of Ce3+ and Zn2+ ranges from 3 to 5 mg·L-1, and that of La3+ ranges from 7 to 10 mg·L-1. The toxic mechanism of La3+ and Ce3+ is similar to that of Cr6+ and Zn2+.

  8. Characterization of the alumina film with cerium doped on the iron-aluminide diffusion coating

    Energy Technology Data Exchange (ETDEWEB)

    Zhan, Q., E-mail: zhanqin1983@163.com; Yang, H.G.; Zhao, W.W.; Yuan, X.M.; Hu, Y.

    2013-11-15

    An iron-aluminide layer with a thin alumina film on the top as a composite tritium permeation barrier (TPB) coating was characterized under different oxidation conditions. The TPB coating was prepared initially on a China Low Activation Ferritic-Martensitic (CLAM) steel by a pack cementation aluminizing process and then an alumina film was formed on the surface of this iron-aluminide diffusion layer by an oxidizing process. To modify the properties of the FeAl/Al{sub 2}O{sub 3} composite TPB coatings, the rare earth element (cerium) was introduced as a dopant while oxidizing. Characterization showed that a continuous oxide scale with a thickness of about 300–400 nm was formed on the FeAl diffusion layer. The film was mainly composed of Al{sub 2}O{sub 3} doped with a little CeO{sub 2}. In addition, the concentration of α-Al{sub 2}O{sub 3} increased with elevated temperature while oxidizing. The phase transformation behavior of alumina scale on the surface of an iron-aluminide layer was studied in this paper.

  9. STUDY ON ORGANIC LIGHT—RARE—EARTH ADSORBENT—CERIUM BIS(OCTYLPHOSPHATE)

    Institute of Scientific and Technical Information of China (English)

    SuZhengquan; FengHuixia

    1996-01-01

    The tetravalent metal salts of monoalkyl phosphates[M(R-OPO3)2] are a new kind of stationary phases of chromatography-homogeneous bonded phases.The studies on preparation,structure and gas chromatographic efficiency of cerium bis (octylphosphate) (COPP) are reported in this paper. By using chemical analysis,infrared spectra,x-ray diffraction analysis ,the strong evidence that COPP has a layered structure of the α-zirconium phosphate type was demonstrated,the repetitive unit is C8H17OPO3CeO3POC8H17 and there is a little bending or interpenetration of the alkyl chains within the layers.The thermogravimetic analysis of the COPP indicated that it has much more thermalstability than silica-based packings.The thermodynamic parameters ΔH and molecular connectivity indexes x′ for the adsorption of several dozen compounds on the COPP have also been determined by gas chromatographic method,and the fine linearity between them was shown.

  10. Role of phosphate on stability and catalase mimetic activity of cerium oxide nanoparticles.

    Science.gov (United States)

    Singh, Ragini; Singh, Sanjay

    2015-08-01

    Cerium oxide nanoparticles (CeNPs) have been recently shown to scavenge reactive oxygen and nitrogen species (ROS and RNS) in different experimental model systems. CeNPs (3+) and CeNPs (4+) have been shown to exhibit superoxide dismutase (SOD) and catalase mimetic activity, respectively. Due to their nanoscale dimension, CeNPs are expected to interact with the components of biologically relevant buffers and medium, which could alter their catalytic properties. We have demonstrated earlier that CeNPs (3+) interact with phosphate and lose the SOD activity. However, very little is known about the interaction of CeNPs (4+) with the phosphate and other anions, predominantly present in biological buffers and their effects on the catalase mimetic-activity of these nanoparticles. In this study, we report that catalase mimetic-activity of CeNPs (4+) is resistant to the phosphate anions, pH changes and composition of cell culture media. Given the abundance of phosphate anions in the biological system, it is likely that internalized CeNPs would be influenced by cytoplasmic and nucleoplasmic concentration of phosphate.

  11. Tribological characteristics of monodispersed cerium borate nanospheres in biodegradable rapeseed oil lubricant

    Science.gov (United States)

    Boshui, Chen; Kecheng, Gu; Jianhua, Fang; Jiang, Wu; Jiu, Wang; Nan, Zhang

    2015-10-01

    Stearic acid-capped cerium borate composite nanoparticles, abbreviated as SA/CeBO3, were prepared by hydrothermal method. The morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics, of SA/CeBO3 were characterized by scanning electron microscope, energy dispersive X-ray spectrometer, dynamic laser particle size analyzer, X-ray diffraction, and Fourier transform infrared spectrometer, respectively. The friction and wear performances of SA/CeBO3 as a lubricating additive in a rapeseed oil were evaluated on a four-ball tribo-tester. The tribochemical characteristics of the worn surfaces were investigated by X-ray photoelectron spectroscopy. The results showed that the hydrophobic SA/CeBO3 were monodispersed nanospheres with an average diameter of 8 nm, and exhibited excellent dispersing stability in rapeseed oil. Meanwhile, SA/CeBO3 nanospheres were outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil. The prominent tribological performances of SA/CeBO3 in rapeseed oil were attributed to the formation of a composite boundary lubrication film mainly composed of lubricous tribochemical species of B2O3, CeO2 and Fe2O3, and the adsorbates of SA/CeBO3 and rapeseed oil, on the tribo-surfaces.

  12. Impact of cerium oxide nanoparticles shape on their in vitro cellular toxicity.

    Science.gov (United States)

    Forest, Valérie; Leclerc, Lara; Hochepied, Jean-François; Trouvé, Adeline; Sarry, Gwendoline; Pourchez, Jérémie

    2017-02-01

    Cerium oxides (CeO2) nanoparticles, also referred to as nanoceria, are extensively used with a wide range of applications. However, their impact on human health and on the environment is not fully elucidated. The aim of this study was to investigate the influence of the CeO2 nanoparticles morphology on their in vitro toxicity. CeO2 nanoparticles of similar chemical composition and crystallinity were synthesized, only the shape varied (rods or octahedrons/cubes). Macrophages from the RAW264.7 cell line were exposed to these different samples and the toxicity was evaluated in terms of lactate dehydrogenase (LDH) release, Tumor Necrosis Factor alpha (TNF-α) production and reactive oxygen species (ROS) generation. Results showed no ROS production, whatever the nanoparticle shape. The LDH release and the TNF-α production were significantly and dose-dependently enhanced by rod-like nanoparticles, whereas they did not vary with cubic/octahedral nanoparticles. In conclusion, a strong impact of CeO2 nanoparticle morphology on their in vitro toxicity was clearly demonstrated, underscoring that nanoceria shape should be carefully taken in consideration, especially in a "safer by design" context.

  13. Shifts in oxidation states of cerium oxide nanoparticles detected inside intact hydrated cells and organelles

    Energy Technology Data Exchange (ETDEWEB)

    Szymanski, Craig J.; Munusamy, Prabhakaran; Mihai, Cosmin; Xie, Yumei; Hu, Dehong; Gilles, Marry K.; Tyliszczak, T.; Thevuthasan, Suntharampillai; Baer, Donald R.; Orr, Galya

    2015-09-01

    Cerium oxide nanoparticles (CNPs) have been shown to induce diverse biological effects, ranging from toxic to beneficial. The beneficial effects have been attributed to the potential antioxidant activity of CNPs via certain redox reactions, depending on their oxidation state or Ce3+/Ce4+ ratio. However, this ratio is strongly dependent on the environment and age of the nanoparticles and it is unclear whether and how the complex intracellular environment impacts this ratio and the possible redox reactions of CNPs. To identify any changes in the oxidation state of CNPs in the intracellular environment and better understand their intracellular reactions, we directly quantified the oxidation states of CNPs outside and inside intact hydrated cells and organelles using correlated scanning transmission x-ray and super resolution fluorescence microscopies. By analyzing hundreds of small CNP aggregates, we detected a shift to a higher Ce3+/Ce4+ ratio in CNPs inside versus outside the cells, indicating a net reduction of CNPs in the intracellular environment. We further found a similar ratio in the cytoplasm and in the lysosomes, indicating that the net reduction occurs earlier in the internalization pathway. Together with oxidative stress and toxicity measurements, our observations identify a net reduction of CNPs in the intracellular environment, which is consistent with their involvement in potentially beneficial oxidation reactions, but also point to interactions that can negatively impact the health of cells.

  14. Cellular uptake and activity of heparin functionalised cerium oxide nanoparticles in monocytes.

    Science.gov (United States)

    Ting, S R Simon; Whitelock, John M; Tomic, Romana; Gunawan, Cindy; Teoh, Wey Yang; Amal, Rose; Lord, Megan S

    2013-06-01

    Cerium oxide nanoparticles (nanoceria) are effective in scavenging intracellular reactive oxygen species (ROS). In this study nanoceria synthesized by flame spray pyrolysis (dXRD = 12 nm) were functionalised with heparin via an organosilane linker, 3-aminopropyltriethoxysilane. Nanoceria were functionalised with approximately 130 heparin molecules per nanoparticle as determined by thermo gravimetric analysis. Heparin functionalised nanoceria were more effectively internalised by the human monocyte cell line, U937, and U937 cells that had been activated with phorbol 12 myristate 13-acetate (PMA) than bare nanoceria. The heparin functionalised nanoceria were also more effective in scavenging ROS than nanoceria in both activated and unactivated U937 cells. Heparin coupled nanoceria were found to be biologically active due to their ability to bind fibroblast growth factor 2 and signal through FGF receptor 1. Additionally, the heparin-coupled nanoceria, once internalised by the cells, were found to be degraded by 48 h. Together these data demonstrated that heparin enhanced the biological properties of nanoceria in terms of cellular uptake and ROS scavenging, while the nanoceria themselves were more effective at delivering heparin intracellularly than exposing cells to heparin in solution.

  15. CO responses of sensors based on cerium oxide thick films prepared from clustered spherical nanoparticles.

    Science.gov (United States)

    Izu, Noriya; Matsubara, Ichiro; Itoh, Toshio; Akamatsu, Takafumi; Shin, Woosuck

    2013-03-08

    Various types of CO sensors based on cerium oxide (ceria) have been reported recently. It has also been reported that the response speed of CO sensors fabricated from porous ceria thick films comprising nanoparticles is extremely high. However, the response value of such sensors is not suitably high. In this study, we investigated methods of improving the response values of CO sensors based on ceria and prepared gas sensors from core-shell ceria polymer hybrid nanoparticles. These hybrid nanoparticles have been reported to have a unique structure: The core consists of a cluster of ceria crystallites several nanometers in size. We compared the characteristics of the sensors based on thick films prepared from core-shell nanoparticles with those of sensors based on thick films prepared from conventionally used precipitated nanoparticles. The sensors prepared from the core-shell nanoparticles exhibited a resistance that was ten times greater than that of the sensors prepared from the precipitated nanoparticles. The response values of the gas sensors based on the core-shell nanoparticles also was higher than that of the sensors based on the precipitated nanoparticles. Finally, improvements in sensor response were also noticed after the addition of Au nanoparticles to the thick films used to fabricate the two types of sensors.

  16. Preparation and investigation of structural, magnetic and microwave absorption properties of cerium doped barium hexaferrite

    Directory of Open Access Journals (Sweden)

    P Kameli

    2015-01-01

    Full Text Available In this study the structure, magnetic and microwave absorption properties of cerium (Ce doped barium hexaferrite with general formulae BaCexFe12-xO19 (x=0.0, 0.05, 0.1, 0.15, 0.2 have been investigated. These samples have been prepared by sol- gel method. Influence of replacing Fe+3 ion by rare- earth Ce+3 ion on the structural, magnetic and microwave absorption properties have been investigated by X- ray diffraction (XRD, Fourier transform infrared (FT-IR, Vibrating sample magnetometer (VSM and vector network analyzer (VNA. X-ray diffraction analysis indicated that the samples are of single phase with space group p63/mmc. The magnetic properties of samples indicated that with the Ce doping the saturation magnetization show no regular behavior. Moreover, coercivity (Hc first decreased and reached to the minimum value for x=0.1 sample and then increased with Ce content increasing. Also, measurement of electromagnetic wave absorption in X and Ku frequency bands indicated that the maximum of reflection loss obtained for x=0.15 sample. Moreover, result indicated that absorption peak shifted toward a lower frequency when thickness was increased.

  17. Ferromagnetism and crystal electric field in the cerium compound CeRh3B2

    Science.gov (United States)

    Givord, F.; Boucherle, J.-X.; Galéra, R.-M.; Fillion, G.; Lejay, P.

    2007-09-01

    The magnetic behavior of CeRh3B2 is very unusual: it orders ferromagnetically with an exceptionally high Curie temperature TC around 115 K, but with a small saturation moment of about 0.4 μB/fu. The thermal variations of magnetization and susceptibility have been measured on a single crystal for fields applied along the easy and hard magnetization directions, with, in the latter case, special care taken to avoid rotation of the sample. The results are compared to calculations based on the crystalline electric field formalism. Due to its large value, one has to take into account the admixture of the two J multiplets of the Ce3+ ion as it is usually used for samarium compounds but not for cerium ones. These calculations actually show the important role of the excited J' = 7/2 multiplet on the 4f spin moment, leading to an enhancement of the exchange, i.e. the Curie temperature, and to a decrease of the moment. An extra polarization, as previously found from the study of magnetization density maps, is confirmed and discussed.

  18. China's Rare Earth Supply Chain: Illegal Production, and Response to new Cerium Demand

    Science.gov (United States)

    Nguyen, Ruby Thuy; Imholte, D. Devin

    2016-07-01

    As the demand for personal electronic devices, wind turbines, and electric vehicles increases, the world becomes more dependent on rare earth elements. Given the volatile, Chinese-concentrated supply chain, global attempts have been made to diversify supply of these materials. However, the overall effect of supply diversification on the entire supply chain, including increasing low-value rare earth demand, is not fully understood. This paper is the first attempt to shed some light on China's supply chain from both demand and supply perspectives, taking into account different Chinese policies such as mining quotas, separation quotas, export quotas, and resource taxes. We constructed a simulation model using Powersim Studio that analyzes production (both legal and illegal), production costs, Chinese and rest-of-world demand, and market dynamics. We also simulated new demand of an automotive aluminum-cerium alloy in the US market starting from 2018. Results showed that market share of the illegal sector has grown since 2007-2015, ranging between 22% and 25% of China's rare earth supply, translating into 59-65% illegal heavy rare earths and 14-16% illegal light rare earths. There will be a shortage in certain light and heavy rare earths given three production quota scenarios and constant demand growth rate from 2015 to 2030. The new simulated Ce demand would require supply beyond that produced in China. Finally, we illustrate revenue streams for different ore compositions in China in 2015.

  19. Effects of cerium on growth and physiological characteristics of Anabaena flosaquae

    Institute of Scientific and Technical Information of China (English)

    WANG Yingjun; LI Jia; L(U) Yun; JIN Hangbiao; DENG Shihuai; ZENG Yunmin

    2012-01-01

    In the present study,the effects of cerium (Ce) on the growth and physiological changes were investigated in the cyanobacterium Anabaenaflosaquae (A.flosaquae) during a 17-day period.The results showed that the content of chlorophyll a (chl-a) and activity of antioxidase (e.g.superoxide dismutase,peroxidase,and catalase) increased with Ce3+ concentration in the range of 0.05 to 0.1 mg/L and the growth of A.flosaquae was stimulated.While at around 5 mg/L,the content of malondiadehyde (MDA) increased significantly but the activity of antioxidase reduced,which resulted in the ruin of antioxidant defense system.Compared to the control (Ce3+-free),the population size of live cells declined significantly.Microcystin-LR (MC-LR),the most common and toxic cyanotoxins produced by A.flosaquae,was detected and the highest content of MC-LR was observed in 10 mg/L Ce3+ treatment.These results implied that the aqueous environment might suffer a more negative ecological impact when exposed to relatively low Ce3+ concentrations (<0.1 mg/L).

  20. Gold-supported cerium-doped NiOx catalysts for water oxidation

    Science.gov (United States)

    Ng, Jia Wei Desmond; García-Melchor, Max; Bajdich, Michal; Chakthranont, Pongkarn; Kirk, Charlotte; Vojvodic, Aleksandra; Jaramillo, Thomas F.

    2016-05-01

    The development of high-performance catalysts for the oxygen-evolution reaction (OER) is paramount for cost-effective conversion of renewable electricity to fuels and chemicals. Here we report the significant enhancement of the OER activity of electrodeposited NiOx films resulting from the combined effects of using cerium as a dopant and gold as a metal support. This NiCeOx-Au catalyst delivers high OER activity in alkaline media, and is among the most active OER electrocatalysts yet reported. On the basis of experimental observations and theoretical modelling, we ascribe the activity to a combination of electronic, geometric and support effects, where highly active under-coordinated sites at the oxide support interface are modified by the local chemical binding environment and by doping the host Ni oxide with Ce. The NiCeOx-Au catalyst is further demonstrated in a device context by pairing it with a nickel-molybdenum hydrogen evolution catalyst in a water electrolyser, which delivers 50 mA consistently at 1.5 V over 24 h of continuous operation.

  1. Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

    Institute of Scientific and Technical Information of China (English)

    LI Kongzhai; WANG Hua; WEI Yonggang; LIU Mingchun

    2008-01-01

    The cerium iron complex oxides oxygen carder was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carrier could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carriers were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carder: the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species (bulk lattice oxygen) that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction con-dition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.

  2. Enhanced corrosion resistance of magnesium alloy AM60 by cerium(III) in chloride solution

    Energy Technology Data Exchange (ETDEWEB)

    Heakal, F. El-Taib, E-mail: fakihaheakal@yahoo.com [Chemistry Department, Faculty of Science, Cairo University, Giza 12613 (Egypt); Shehata, O.S. [Physical Chemistry Department, National Research Centre, Dokki, Giza (Egypt); Tantawy, N.S. [Girl' s College of Arts, Science and Education, Ain Shams University, Asma Fahmi Street, Cairo (Egypt)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Corrosion rate of AM60 in Cl{sup -} solution decreases with increasing [Ce{sup 3+}] up to 1 mM. Black-Right-Pointing-Pointer Beyond that level the corrosion rate increases and then stabilizes. Black-Right-Pointing-Pointer The spontaneously formed film characterises by increasing resistance with time. Black-Right-Pointing-Pointer The converted film after 10 d immersion exhibits self-healing in plain Cl{sup -} solution. Black-Right-Pointing-Pointer Ce(III) should be present in the corrodent to form a more compact surface coating. - Abstract: Cerium(III) was utilised to enhance the corrosion resistance of AM60 in NaCl solution. Ce{sup 3+} can suppress corrosion deterioration up to 1.0 mM. Beyond that level corrosion rate increases till a steady value. Surface film resistance increases with time evolution until 24 h, then decreases and stabilizes. The converted film after 240 h immersion exhibits self-healing and thickening when re-exposed to plain chloride solution. SEM and EDX confirmed that when Ce is present as additive in solution, more compact coating is formed better than its presence as a post coating on the alloy surface before being immersed in the corrosive environment.

  3. A nanostructured cerium oxide film-based immunosensor for mycotoxin detection

    Science.gov (United States)

    Kaushik, Ajeet; Rathee Solanki, Pratima; Ansari, Anees Ahmad; Ahmad, Sharif; Dhar Malhotra, Bansi

    2009-02-01

    Rabbit-immunoglobulin antibodies (r-IgGs) and bovine serum albumin (BSA) have been immobilized onto sol-gel-derived nanostructured cerium oxide (nanoCeO2) film fabricated onto an indium-tin-oxide (ITO) coated glass plate to detect ochratoxin-A (OTA). Broad reflection planes obtained in x-ray diffraction (XRD) patterns reveal the formation of CeO2 nanostructures. Electrochemical studies reveal that nanoCeO2 particles provide an increased electroactive surface area for loading of r-IgGs with desired orientation, resulting in enhanced electron communication between r-IgGs and electrode. BSA/r-IgGs/nano CeO2/ITO immunoelectrode exhibits improved characteristics such as linear range (0.5-6 ng dl-1), low detection limit (0.25 ng dl-1), fast response time (30 s) and high sensitivity (1.27 µA ng-1 dl-1 cm-2). The high value of the association constant (Ka, 0.9 × 1011 l mol-1) indicates the high affinity of the BSA/r-IgGs/nanoCeO2/ITO immunoelectrode to OTA.

  4. Adsorptional removal of methylene blue by guar gum-cerium (IV) tungstate hybrid cationic exchanger.

    Science.gov (United States)

    Gupta, V K; Pathania, Deepak; Singh, Pardeep; Kumar, Amit; Rathore, B S

    2014-01-30

    Guar gum-cerium (IV) tungstate nanocomposite (GG/CTNC) cationic exchanger was synthesized using simple sol gel method. The GG/CTNC was characterized using X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectrophotometer (EDX). The XRD studies confirmed amorphous and fibrous in nature of GG/CTNC. The high percentage of oxygen in the nanocomposite material confirmed the functionality tungstate (WO4(-)). The ion exchange capacity of GG/CTNC for Na(+) ion was observed to be 1.30 mequivg(-1). The hybrid exchanger was used as potential adsorbent for the removal of methylene blue (MB) from aqueous system. The correlation coefficients value indicated a good fit of monolayer Langmuir model to the adsorption of methylene blue onto GG/CTNC. The adsorption kinetic study revealed that the adsorption process followed the pseudo second order kinetic. The Gibbs free energy (ΔG) values confirmed the spontaneous nature of adsorption process.

  5. Hierarchical porous carbon toward effective cathode in advanced zinc-cerium redox flow battery

    Institute of Scientific and Technical Information of China (English)

    谢志鹏; 杨斌; 蔡定建; 杨亮

    2014-01-01

    Advanced zinc-cerium redox flow battery (ZCRFB) is a large-scale energy storage system which plays a significant role in the application of new energy sources. The requirement of superior cathode with high acitivity and fast ion diffusion is a hierarchical porous structure, which was synthesized in this work by a method in which both hard template and soft template were used. The structure and the performance of the cathode prepared here were characterized and evaluated by a variety of techniques such as scan-ning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltam-metry (CV), linear sweep voltammetry (LSV), and chronoamperometry (CA). There were mainly three types of pore size within the hierarchical porous carbon:2μm, 80 nm, and 10 nm. The charge capacity of the cell using hierarchical porous carbon (HPC) as posi-tive electrode was obviously larger than that using carbon felt;the former was 665.5 mAh with a coulombic efficiency of 89.0%and an energy efficiency of 79.0%, whereas the latter was 611.1 mAh with a coulombic efficiency of 81.5%and an energy efficiency of 68.6%. In addition, performance of the ZCRFB using HPC as positive electrode showed a good stability over 50 cycles. These results showed that the hierarchical porous carbon was superior over the carbon felt for application in ZCRFB.

  6. Spectrophotometric determination of H 2-receptor antagonists via their oxidation with cerium(IV)

    Science.gov (United States)

    Darwish, Ibrahim A.; Hussein, Samiha A.; Mahmoud, Ashraf M.; Hassan, Ahmed I.

    2008-01-01

    A simple, accurate and sensitive spectrophotometric method has been developed and validated for determination of H 2-receptor antagonists: cimetidine, famotidine, nizatidine and ranitidine hydrochloride. The method was based on the oxidation of these drugs with cerium(IV) in presence of perchloric acid and subsequent measurement of the excess Ce(IV) by its reaction with p-dimethylaminobenzaldehyde to give a red colored product ( λmax at 464 nm). The decrease in the absorption intensity of the colored product (Δ A), due to the presence of the drug was correlated with its concentration in the sample solution. Different variables affecting the reaction were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9990-0.9994) were found between Δ A values and the concentrations of the drugs in a concentration range of 1-20 μg ml -1. The assay limits of detection and quantitation were 0.18-0.60 and 0.54-1.53 μg ml -1, respectively. The method was validated, in terms of accuracy, precision, ruggedness and robustness; the results were satisfactory. The proposed method was successfully applied to the determination of the investigated drugs in pure and pharmaceutical dosage forms (recovery was 98.3-102.6 ± 0.57-1.90%) without interference from the common excipients. The results obtained by the proposed method were comparable with those obtained by the official methods.

  7. Evaluation of cerium oxide coated Cu cermets as inert anodes for aluminum electrowinning

    Energy Technology Data Exchange (ETDEWEB)

    1992-08-01

    Cu/NiFe{sub 2}O{sub 4} cermets were evaluated, with and without an in-situ deposited CEROX (TM; cerium oxide) coating, in 100 h laboratory A1 electrowinning tests. Bath ratio and current density were varied between tests and corrosion was determined by contamination of the aluminum and cryolite by cermet components (Cu, Fe, and Ni). Higher bath ratios of 1.5 to 1.6 led to less corrosion and thicker CEROX coatings. Lower current densities led to slightly less corrosion but much less oxidation of the Cu cermet substrate. At identical test conditions, the corrosion of the CEROX coated cermets was 1/7 that of an uncoated cermet. Corrosion was increased in CEROX coated cermets tested under unsaturated alumina conditions. The electrical conductivity of the CEROX coating was measured to be {approximately}0.2 ohm{sup {minus}1}cm{sup {minus}1}, resulting in a slight voltage penalty, depending on the thickness of the coating.

  8. Cerium Oxide Nanoparticles Decorated Graphene Nanosheets for Selective Detection of Dopamine.

    Science.gov (United States)

    Nayak, Pranati; Santhosh, P N; Ramaprabhu, S

    2015-07-01

    The fabrication of a novel amperometric biosensor based on selective determination of dopamine (DA) using nafion coated cerium oxide nanoparticles (NPs) decorated graphene nanosheets (CeO2-HEG-nafion) as a transducer candidate is reported. Graphene was synthesized by hydrogen exfoliation technique. Decoration of CeO2NPs over graphene nanosheets was done by chemical reduction method. The electrochemical impedance spectroscopy (EIS) study shows the enhanced electron transfer kinetics of the composite compared to HEG modified and bare glassy carbon electrode (GCE). The response of the composite towards dopamine displays a lower oxidation potential of 0.23 V and a high oxidation current. The sensor exhibits linearity from 10 µM to 780 µM with a detection limit of 1 µM. In the presence of nafion, it shows excellent selectivity for coexisting interference species like Ascorbic acid (AA) and Uric acid (UA). The excellent performance of the biosensor can be attributed to large active surface area, enhanced electron transfer kinetics and high catalytic activity of the composite.

  9. 124Xe(n,γ125Xe and 124Xe(n,2n123Xe measurements for National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Bhike Megha

    2015-01-01

    Full Text Available The cross section for the 124Xe(n,γ125Xe reaction has been measured for the first time for neutron energies above 100 keV. In addition, the 124Xe(n,2n123Xe reaction has been studied between threshold and 14.8 MeV. The results of these measurements provide sensitive diagnostic tools for investigating properties of the inertial confinement fusion plasma in Deuterium-Tritium (DT capsules at the National Ignition Facility (NIF located at Lawrence Livermore National Laboratory.

  10. Nuclear 111Cd probes detect a hidden symmetry change at the γ → α transition in cerium considered isostructural for 60 years

    Science.gov (United States)

    Tsvyashchenko, A. V.; Nikolaev, A. V.; Velichkov, A. I.; Salamatin, A. V.; Fomicheva, L. N.; Ryasny, G. K.; Sorokin, A. A.; Kochetov, O. I.; Budzynski, M.

    2010-10-01

    We use the time-differential perturbed angular correlation technique to study nuclear electric quadupole hyperfine interactions of probe 111Cd nuclei in cerium lattice sites at room temperature under pressures up to 8 GPa. We have found that the well known γ → α phase transition in cerium is not isostructural. In α-Ce, the probe 111Cd nuclei reveal a quadrupole electron charge density component that is absent in γ-Ce. The hidden spacial structure of electronic quadrupoles in α-Ce is triple-q antiferroquadrupolar, as was suggested in [14]. We relate our findings to the current understanding of the γ → α phase transition and also report on nuclear quadrupole interactions in other high-pressure phases of cerium: α″ ( C2/ m space symmetry) and α' (α-U structure).

  11. Synergism between cerium nitrate and sodium dodecylbenzenesulfonate on corrosion of AA5052 aluminium alloy in 3 wt.% NaCl solution

    Science.gov (United States)

    Liu, Jie; Wang, Dapeng; Gao, Lixin; Zhang, Daquan

    2016-12-01

    The synergistic inhibition effect of rare earth cerium nitrate and sodium dodecylbenzenesulfonate (DBS) on corrosion of AA5052 aluminium alloy in 3 wt.% NaCl solution was investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curve, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). The results show that the single cerium nitrate or DBS has a limited inhibition effect against corrosion of AA5052 alloy. The combination cerium ions with DBS produced strong synergistic effect on corrosion inhibition for AA5052 alloy and rendered a negaitve shift of the corrosion potential. The formation of the complex of Al(DBS)3 and Ce(DBS)3 stabilized the passive film of Al2O3 and CeO2, retarding both the cathodic and anodic processes of AA5052 alloy corrosion reaction significantly.

  12. Effect of cerium (IV) ions on the anticorrosion properties of siloxane-poly(methyl methacrylate) based film applied on tin coated steel

    Energy Technology Data Exchange (ETDEWEB)

    Suegama, P.H. [Departamento de Engenharia Quimica, Escola Politecnica, Universidade de Sao Paulo, CP 61548, 05424-970 Sao Paulo, SP (Brazil); Sarmento, V.H.V. [Departamento Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, UNESP, CP 355, 14801-970 Araraquara, SP (Brazil); Montemor, M.F. [ICEMS, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Benedetti, A.V. [Departamento Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, UNESP, CP 355, 14801-970 Araraquara, SP (Brazil); de Melo, H.G.; Aoki, I.V. [Departamento de Engenharia Quimica, Escola Politecnica, Universidade de Sao Paulo, CP 61548, 05424-970 Sao Paulo, SP (Brazil); Santilli, C.V., E-mail: santilli@iq.unesp.b [Departamento Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, UNESP, CP 355, 14801-970 Araraquara, SP (Brazil)

    2010-07-15

    This work investigates the influence of the addition of cerium (IV) ions on the anticorrosion properties of organic-inorganic hybrid coatings applied to passivated tin coated steel. In order to evaluate the specific effect of cerium (IV) addition on nanostructural features of the organic and inorganic phases of the hybrid coating, the hydrolytic polycondensation of silicon alkoxide and the radical polymerization of the methyl methacrylate (MMA) function were induced separately. The corrosion resistance of the coatings was evaluated by means of linear polarization, Tafel type curves and electrochemical impedance measurements. The impedance results obtained for the hybrid coatings were discussed based on an electrical equivalent circuit used to fit the experimental data. The electrochemical results clearly showed the improvement of the protective properties of the organic-inorganic hybrid coating mainly when the cerium (IV) was added to the organic phase solution precursor, which seemed to be due to the formation of a more uniform and densely reticulated siloxane-PMMA film.

  13. Improving in-vitro biocorrosion resistance of Mg-Zn-Mn-Ca alloy in Hank’s solution through addition of cerium

    Institute of Scientific and Technical Information of China (English)

    张凡; 马爱斌; 宋丹; 江静华; 卢富敏; 张留艳; 杨东辉; 陈建清

    2015-01-01

    Two kinds of Mg-Zn-Mn-Ca alloys with and without cerium were designed and fabricated. In-vitro degradation tests and electrochemical evaluations were carried out to compare their biocorrosion behavior in Hank’s solution at 37 ºC. After adding cerium, the continuous network distributed Ca2Mg6Zn3 phases in Mg-2Zn-0.5Mn-1Ca alloy (Alloy I) were separated due to the emerging non-continuously distributed Mg2Ca phase and Mg12CeZn phase. This change led to corrosion acceleration of Mg ma-trix at the initial stage but also sped up the formation of compact corrosion products for Mg-2Zn-0.5Mn-1Ca-1.5Ce alloy (Alloy II), and therefore enhanced its biocorrosion resistance. Cerium containing Alloy II has the potential to be used as future biomate-rials.

  14. Synthesis and Antimicrobial Activity of Some [1,2,4]-Triazole Derivatives

    Directory of Open Access Journals (Sweden)

    Bhimagouda S. Patil

    2013-01-01

    Full Text Available A series of novel [1,2,4]-triazolo piperidine (8, [1,2,4]-triazolo piperazine (9a-c, [1,2,4]-triazolo phenylether (10a-e, and [1,2,4]-triazolo aniline (11a-c derivatives have been synthesized. The chemical structures of the newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR, and LCMS. The newly synthesized compounds were screened for antimicrobial activity. Among all the compounds tested, 11b (R4=4-MeO– showed the highest activity against Staphylococcus aureus and Escherichia coli, and 9a (R1 and R2=Cl showed the highest activity against Pseudomonas aeruginosa.

  15. Yeast Interacting Proteins Database: YHR166C, YPL124W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available SPC29 Inner plaque spindle pole body (SPB) component, links the central plaque c... ORF YPL124W Prey gene name SPC29 Prey description Inner plaque spindle pole body (SPB) component, links the

  16. Yeast Interacting Proteins Database: YBR270C, YPL124W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available bait as prey (2) YPL124W SPC29 Inner plaque spindle pole body (SPB) component, links...ue spindle pole body (SPB) component, links the central plaque component Spc42p to the inner plaque componen

  17. Yeast Interacting Proteins Database: YLR347C, YPL124W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available as prey (0) YPL124W SPC29 Inner plaque spindle pole body (SPB) component, links ...e pole body (SPB) component, links the central plaque component Spc42p to the inner plaque component Spc110p

  18. Yeast Interacting Proteins Database: YDL155W, YPL124W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available bait as prey (0) YPL124W SPC29 Inner plaque spindle pole body (SPB) component, links...que spindle pole body (SPB) component, links the central plaque component Spc42p to the inner plaque compone

  19. Yeast Interacting Proteins Database: YDL203C, YPL124W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available SPC29 Inner plaque spindle pole body (SPB) component, links the central plaque c...RF YPL124W Prey gene name SPC29 Prey description Inner plaque spindle pole body (SPB) component, links the c

  20. Identification of protein tyrosine phosphatase 1B and casein as substrates for 124-v-Mos

    Directory of Open Access Journals (Sweden)

    Stabel Silvia

    2002-04-01

    Full Text Available Abstract Background The mos proto-oncogene encodes a cytoplasmic serine/threonine-specific protein kinase with crucial function during meiotic cell division in vertebrates. Based on oncogenic amino acid substitutions the viral derivative, 124-v-Mos, displays constitutive protein kinase activity and functions independent of unknown upstream effectors of mos protein kinase. We have utilized this property of 124-v-Mos and screened for novel mos substrates in immunocomplex kinase assays in vitro. Results We generated recombinant 124-v-Mos using the baculovirus expression system in Spodoptera frugiperda cells and demonstrated constitutive kinase activity by the ability of 124-v-Mos to auto-phosphorylate and to phosphorylate vimentin, a known substrate of c-Mos. Using this approach we analyzed a panel of acidic and basic substrates in immunocomplex protein kinase assays and identified novel in vitro substrates for 124-v-Mos, the protein tyrosine phosphatase 1B (PTP1B, alpha-casein and beta-casein. We controlled mos-specific phosphorylation of PTP1B and casein in comparative assays using a synthetic kinase-inactive 124-v-Mos mutant and further, tryptic digests of mos-phosphorylated beta-casein identified a phosphopeptide specifically targeted by wild-type 124-v-Mos. Two-dimensional phosphoamino acid analyses showed that 124-v-mos targets serine and threonine residues for phosphorylation in casein at a 1:1 ratio but auto-phosphorylation occurs predominantly on serine residues. Conclusion The mos substrates identified in this study represent a basis to approach the identification of the mos-consensus phosphorylation motif, important for the development of specific inhibitors of the Mos protein kinase.

  1. Antimicrobial activity of 2,4-dihydro-[1,2,4]triazol-3-one derivatives.

    Science.gov (United States)

    Stefańska, Joanna; Struga, Marta; Tyski, Stefan; Kossakowski, Jerzy; Dobosz, Maria

    2008-01-01

    Antibacterial and antifungal activity of 2,4-dihydro- [1,2,4]triazol-3-one derivatives were examined by the disc-diffusion method (growth inhibition zone diameter in agar medium). The MIC's for the most active agents were determined. Of all the tested compounds, aminomethyl derivatives of 2,4-dihydro-[1,2,4]triazol-3-one exhibit activity against the majority of microorganisms studied.

  2. Steady photo-darkening of thulium alumino-silicate fibers pumped at $1.07~\\mu m$: Quantitative effect of lanthanum, cerium and thulium

    CERN Document Server

    Lupi, Jean-François; Blanc, Wilfried; Mady, Franck; Benabdesselam, Mourad; Dussardier, Bernard; Neuville, Daniel R

    2016-01-01

    By pumping thulium-doped silica-based fibers at 1.07~\\mu m, rapid generation of absorbing centers leads to photo-induced attenuation (PIA). This detrimental effect prevents exploiting laser emissions in the visible and near infrared. We report on the characterization of the PIA versus the fiber core composition, particularly the concentration of thulium (Tm), lanthanum (La) and cerium (Ce) ions. We show that UV emision induced by Tm-Tm energy transfers is the source of photo-darkening, and that lanthanum and cerium are efficient hardeners against PIA.

  3. Scintillation and Luminescence Properties of Undoped and Cerium-doped LiGdCl4 and NaGdCl4

    OpenAIRE

    Porter-Chapman, Yetta D.

    2008-01-01

    We report the scintillation properties of the undoped and cerium-doped variations of LiGdCl4 and NaGdCl4. Powder samples of these materials exhibit significant scintillation under X-rays. The samples were synthesized by solid-state methods from a 1:1 molar ratio of lithium or sodium chloride and gadolinium chloride. Cerium trichloride was used as the dopant. The physical, optical, and scintillation properties of these materials were analyzed by powder X-ray diffraction, photoluminescence, X-r...

  4. New 1,2,4-triazine bearing compounds: molecular modeling, synthesis and biotesting

    Directory of Open Access Journals (Sweden)

    Negrutska V. V.

    2009-12-01

    Full Text Available Aim. To enlarge a spectrum of biologically active compounds in the series of the 1,2,4-triazino[5,6-b] [1,4]benzothiazine (1,2,4-TBT derivatives and reveal among them efficient inhibitors of RNA synthesis Methods. The methods of structure optimization of the 3-oxo-1,2,4-TBT by fragment-oriented substitution, the molecular doking of new structures in a virtual target, the rational chemical synthesis of the theoretically predicted compounds and their testing in the system of transcription in vitro. Results. The series of 1,2,4-TBT derivatives with substituents in the benzene and triazine cycles of a base molecule were synthesized. The testing of synthesized compounds in the in vitro transcription system directed by T7 RNA polymerase revealed the structure- and concentration-dependent inhibition of the RNA synthesis by some of these compounds. The experimental and virtual screening data for all investigated compounds have a good correlation. It was found that most effective derivative is the 3-oxo-8-butyl-1,2,4-TBT which completely inhibited transcription at the concentration of 6 mg/ml. Conclusions. The biotesting results allow us to assume that the inhibition of RNA synthesis is caused by binding of the 3-oxo- 8-butyl-1,2,4-TBT to both free RNA polymerase molecules and those including in a transcriptional complex with DNA

  5. Experimental study of the astrophysical gamma-process reaction 124Xe(alpha,gamma)128Ba

    CERN Document Server

    Halász, Z; Gyürky, Gy; Elekes, Z; Fülöp, Zs; Szücs, T; Kiss, G G; Szegedi, N; Rauscher, T; Görres, J; Wiescher, M

    2016-01-01

    The synthesis of heavy, proton rich isotopes in the astrophysical gamma-process proceeds through photodisintegration reactions. For the improved understanding of the process, the rates of the involved nuclear reactions must be known. The reaction 128Ba(g,a)124Xe was found to affect the abundance of the p nucleus 124Xe. Since the stellar rate for this reaction cannot be determined by a measurement directly, the aim of the present work was to measure the cross section of the inverse 124Xe(a,g)128Ba reaction and to compare the results with statistical model predictions. Of great importance is the fact that data below the (a,n) threshold was obtained. Studying simultaneously the 124Xe(a,n)127Ba reaction channel at higher energy allowed to further identify the source of a discrepancy between data and prediction. The 124Xe + alpha cross sections were measured with the activation method using a thin window 124Xe gas cell. The studied energy range was between E = 11 and 15 MeV close above the astrophysically relevant...

  6. The effect of a newly synthesized indazole compound, TAS-3-124, on experimental autoimmune disease.

    Science.gov (United States)

    Akabane, Hirotomo; Miyagawa, Naoki; Nii, Hiroaki; Inami, Yoshihiro; Togawa, Michinori; Tanaka, Hiroyuki; Inagaki, Naoki; Nagai, Hiroichi

    2004-08-01

    The effects of a newly synthesized compound, 6-acetoamido-1-acetyl-1-indazole (TAS-3-124), on autoimmune diseases were studied. We used animal models of collagen-induced arthritis (CIA) in mice and experimental autoimmune encephalomyelitis (EAE) in rats to evaluate the efficacy of TAS-3-124. TAS-3-124 at doses of 100 and 300 mg/kg p.o. inhibited the development of CIA, decreasing the swelling of fore- and hind-limbs and bone destruction in knee joints. This agent also suppressed the delayed type hypersensitivity reaction (DTH) against type II collagen. These effects were confirmed by histopathological examination and measurement of the expression of mRNA of proinflammatory cytokines in the knee joint. In addition, TAS-3-124 at a dose of 300 mg/kg inhibited the development of EAE and the DTH to myelin basic protein (MBP) in rats. Moreover, TAS-3-124 inhibited the production of proinflammatory cytokines including interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and IL-6 but not T cell derived cytokines in mice. These demonstrate the efficacy of TAS-3-124 against experimental autoimmune disease, probably due to the suppression of the production of proinflammatory cytokines in the pathological lesion.

  7. SU-E-T-279: Dose Enhancement Effect Due to Cerium Oxide Nanoparticles Employed as Radiation Protectants

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Z; Altundal, Y; Sajo, E [Univ Massachusetts Lowell, Lowell, MA (United States); Ngwa, W [Univ Massachusetts Lowell, Lowell, MA (United States); Brigham and Women’s Hospital, Dana Farber Cancer Institute, Harvard Medical, Boston, MA (United States)

    2015-06-15

    Purpose: The goal of radiotherapy is to maximize radiation dose to diseased cells while minimizing radiation damage to normal tissues. In order to minimize damage to normal tissues, cerium oxide nanoparticles (nanoceria) are currently considered as a radioprotectant. However, some studies have reported concerns that nanoceria can also lead to radiotherapy dose enhancement due to the high atomic number of cerium, especially when used in conjunction with kV energy and brachytherapy sources. In this study, this concern is investigated to determine if the concentrations of nanoceria employed in in-vivo studies to confer radioprotection can engender a significant dose enhancement. Methods: Radiation with energies ranging from 50kVp to 140kVp is investigated in this work along with brachytherapy sources Pd-103 and I-125. A previously established theoretical model is used to calculate the dose enhancement factor (DEF). In this model, each cell is assumed to be a voxel of size (10 µm, 10 µm, 10 µm) with nanoceria homogeneously distributed among them. Electron energy loss formula of Cole is used to calculate energy (and hence dose) deposited by photoelectrons and Auger electrons in each tissue voxel due to irradiation of nanoceria. The DEF is defined as the ratio of the dose with and without nanoparticles. Results: DEF calculation results are smaller than 1.02 with dosages of nanoceria smaller than 0.645 mg/g, which is shown to be sufficiently protective by some previous in-vitro and in-vivo experiments. The brachytherapy sources show higher DEF’s than kVp radiations. DEF peaks are consistent with K shell and L shell energies of cerium, 40 keV and 6 keV, respectively. Conclusion: The results show that for sufficiently radioprotective concentrations of nanoceria, there will be minimal DEF when used in conjunction with clinically applicable kV energy radiotherapy sources or brachytherapy sources.

  8. Influence of the surface pre-treatment of aluminum on the processes of formation of cerium oxides protective films

    Science.gov (United States)

    Andreeva, R.; Stoyanova, E.; Tsanev, A.; Stoychev, D.

    2016-03-01

    It is known that there is special interest in the contemporary investigations on conversion treatment of aluminum aimed at promoting its corrosion stability, which is focused on electrolytes on the basis of salts of metals belonging to the group of rare-earth elements. Their application is especially attractive, as it enables a successful substitution of the presently applied highly efficient, but at the same time toxic Cr6+-containing electrolytes. The present paper presents a study on the influence of the preliminary alkaline activation and acidic de-oxidation of the aluminum surface on the processes of immersion formation of protective cerium oxides films on Al 1050. The results obtained show that their deposition from simple electrolytes (containing only salts of Ce3+ ions) on the Al surface, treated only in alkaline solution, occurs at a higher rate, which leads to preparing thicker oxide films having a better protective ability. In the cases when the formation of oxide films is realized in a complex electrolyte (containing salts of Ce3+ and Cu2+ ions), better results are obtained with respect to the morphology and protective action of cerium oxides film on samples that have been consecutively activated in alkaline solution and deoxidized in acidic solution. Electrochemical investigations were carried out in a model corrosion medium (0.1 M NaCl); it was shown that the cerium protective films, deposited by immersion, have a cathodic character with regard to the aluminum support and inhibit the occurrence of the depolarizing corrosion process -- the reaction of oxygen reduction.

  9. Potential of a Hydrometallurgical Recycling Process for Catalysts to Cover the Demand for Critical Metals, Like PGMs and Cerium

    Science.gov (United States)

    Steinlechner, Stefan; Antrekowitsch, Jürgen

    2015-02-01

    The metals from the platinum group are used in many different industries, for example dental, jewelry, and chemicals. Nevertheless, the most important use is based on their catalytic properties. Approximately 50% of platinum and palladium are used as automotive and industrial catalysts. In case of rhodium, an even higher percentage (around 80-90%) is used as an alloying element in the active layer of different catalysts. The high required amount of 300-900 kg of treated ore to obtain approximately 1 g of PGM is responsible for the high prices. On average, the contents in the ore of Pt and Pd are 5-10 times higher than Rh and Ru and around 50 times higher than Ir and Os. Additionally, the regional limitation of ore bodies leads to a strong dependence on mainly South Africa and Russia as PGM suppliers. Based on the strong discrepancy in supply and demand of PGM's around the world, recycling of catalysts is mandatory and meaningful from the ecological and economical point of view. Based on the high prices of PGM, the industry is forced to improve the efficiency of catalysts, which is done by improving the wash coat technology. By using rare-earth elements, like cerium oxide, the surface can be increased and the ability to supply oxygen is secured. As a side effect, cerium as an additional critical element is introduced into the recycling circuit of catalytic converters, forming a further valuable component and forming a major challenge for common pyrometallurgical converter recycling. Therefore, this article introduces a hydrometallurgical process, developed together with Railly&Hill Inc., for PGM as well as cerium recovery from catalytic converters.

  10. Preparation of 1,1'-dinitro-3,3'-azo-1,2,4-triazole. [1,1'-dinitro-3,3'-azo-1,2,4-triazole

    Science.gov (United States)

    Lee, K.Y.

    1985-03-05

    A new high density composition of matter, 1,1'-dinitro-3,3'-azo-1,2,4-triazole, has been synthesized using inexpensive, commonly available compounds. This compound has been found to be an explosive, and its use as a propellant is anticipated. 1 fig., 1 tab.

  11. Effect of 1,24R-dihydroxyvitamin D3 on the growth of human keratinocytes.

    LENUS (Irish Health Repository)

    Matsumoto, K

    1990-02-01

    The effect of 1,24R-dihydroxyvitamin D3 (1,24R(OH)2D3), a synthetic analogue of a biologically active form of vitamin D3 (1,25-dihydroxyvitamin D3, 1,25(OH)2D3), on the growth of human keratinocytes cultured in serum-free medium was investigated. The growth of cultured normal human keratinocytes was inhibited by 65% by 10(-8)M 1,24R(OH)2D3 and by 90% by 10(-7)M 1,24(OH)2D3. It inhibited cell growth almost completely at 10(-6)M. The DNA synthesis of keratinocytes was also inhibited with 1,24R(OH)2D3 by 27% at 10(-8)M, 59% at 10(-7)M, and 92% at 10(-6)M. The inhibition of cell growth and DNA synthesis were more remarkable by 1,24R(OH)2D3 than by 1,25(OH)2D3. 1,24R(OH)2D3 also inhibited the growth of keratinocytes derived from patients with psoriasis vulgaris; the growth inhibitory effect was again more remarkable with 1,24R(OH)2D3 than with 1,25(OH)2D3. The viability and protein synthesis of keratinocytes were not affected by 1,24R(OH)2D3, suggesting that the growth inhibitory effect is due to its biological activity, not to cytotoxicity. The binding of [3H]-labeled 1,25(OH)2D3 to its receptor in the cytosolic fraction of cultured keratinocytes was competitively substituted by unlabeled 1,24R(OH)2D3 as well as 1,25(OH)2D3, suggesting that 1,24R(OH)2D3 binds to the 1,25(OH)2D3 receptor. It was found that the affinity of 1,24R(OH)2D3 for the receptor was slightly higher than that of 1,25(OH)2D3. These results demonstrate that 1,24R(OH)2D3 functions as a potent growth inhibitor in vitro in human keratinocytes from both normal and psoriatic epidermis, and it possesses a higher affinity for the 1,25(OH)2D3 receptor in cultured human keratinocytes. The difference in affinity of 1,24R(OH)2D3 for the 1,25(OH)2D3 receptor correlates with its greater inhibition of keratinocyte growth than 1,25(OH)2D3. 1,24R(OH)2D3 may be useful in the treatment of psoriasis.

  12. Analysis of DNA modified by cerium (III, lanthanum (III and gadolinium (III ions by using of raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Veronika Kohoutkova

    2010-12-01

    Full Text Available Lanthanides are at the present group of heavy metals, which are at the centre of interest, especially because of their ability to interact with DNA and similarity with calcium(III ions, which play crucial role in many cell processes. On basis of DNA interactions, anti–cancerogenic potential is established. In our work, we were focused on interactions of chosen lanthanides – lanthanum, cerium and gadolinium – with DNA. Results of our experiments demonstrate ability of lanthanides to form DNA adducts.

  13. Synthesis of β-SiC/SiO_2 core-shell nanowires with the assistance of cerium oxide

    Institute of Scientific and Technical Information of China (English)

    于伟鹏; 郑瑛; 杨娥; 邱健斌; 兰瑞芳

    2010-01-01

    The β-SiC/SiO2 core-shell nanowires with the "stem-and-node" structure were synthesized in the presence of cerium oxide by the carbothermal reduction of the starch-SiO2 hybrids gel.The samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM) and energy-dispersed X-ray(EDX).The results showed that the nanowires consisted of a 20-35 nm diameter crystalline β-SiC core wrapped with a 2-5 n...

  14. Interactive effect of cerium and aluminum on the ignition point and the oxidation resistance of magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lin Pengyu [Key Laboratory of Automobile Materials of Ministry of Education, School of Materials Science and Engineering, Nanling Campus of Jilin University, Changchun Jilin 130025 (China)], E-mail: linpengyu2000@yahoo.com.cn; Zhou Hong; Li Wei; Li Wenping; Sun Na [Key Laboratory of Automobile Materials of Ministry of Education, School of Materials Science and Engineering, Nanling Campus of Jilin University, Changchun Jilin 130025 (China); Yang Rong [Public Mathematics Teaching and Research Center, College of Mathematics, Qianwei Campus of Jilin University, Changchun Jilin 130012 (China)

    2008-09-15

    This paper focused on the interactive effect of cerium (Ce) addition and aluminum (Al) content in magnesium alloy on ignition point and oxidation resistance. Ce content played an important role in improving the oxidation resistance of Mg alloy. Ignition point ascended with increasing Ce content. 0.25 wt% Ce content in Mg alloys could greatly improve tightness of the oxide film of Mg alloys. However, when Ce content in the alloy exceeded its solid solubility, ignition point descended. Furthermore, Al content in the alloy also influenced the ignition point. The higher the Al content was, the lower the ignition point.

  15. Linking the chemical speciation of cerium to its bioavailability in water for a freshwater alga.

    Science.gov (United States)

    El-Akl, Philippe; Smith, Scott; Wilkinson, Kevin J

    2015-08-01

    Over the past decade, researchers have begun to use metals of the lanthanide family for numerous applications, including liquid crystal display (LCD) screens, optical fibers, and laser technology. Unfortunately, little is presently known about their bioavailability or the mechanisms by which they might cause toxicity. The present study focuses on cerium (Ce), one of the most widely used lanthanides, and on validating the biotic ligand model as a means to predict Ce bioaccumulation. Short-term exposures to Ce were performed using the unicellular alga Chlamydomonas reinhardtii, to better relate Ce bioavailability to its chemical speciation in solution. Maximum uptake fluxes (Jmax ) and affinity constants for the binding of Ce to the biological uptake sites (KS ) were established at pH 5.0 and pH 7.0. An apparent affinity constant of 1.8 × 10(7) M(-1) was observed at pH 5.0, with a larger value obtained at pH 7.0 (6 × 10(7) M(-1) ), albeit under conditions where equilibrium could not be confirmed. By evaluating Ce speciation using centrifugal ultrafiltration and single-particle inductively coupled plasma spectrometry, it could be concluded that very little (∼30%) Ce was truly dissolved at pH 7.0, with the majority of the metal being present in colloidal species. Speciation was also monitored by fluorescence to evaluate Ce complexation by natural organic matter (NOM). The presence of NOM decreased Ce bioaccumulation in line with free Ce concentrations. Finally, competition with calcium for the metal uptake sites was shown to result in a decrease in Ce uptake by C. reinhardtii.

  16. Separation chemistry and clean technique of cerium(IV):A review

    Institute of Scientific and Technical Information of China (English)

    邹丹; 陈继; 李德谦

    2014-01-01

    The separation method of changeable valence RE element of cerium (Ce) was reviewed in this paper. Solvent extraction is the most effective and efficient method to separate Ce(IV) from RE(III), usually accompanied with fluorine (F) and phosphor (P) from bastnaesite and monazite etc. By roast or wet-air oxidation, Ce(III) of bastnaesite and monazite was oxidized into Ce(IV), and Cyanex923 and [A336][P507] have been investigated to co-extract and recover Ce(IV), F and P from H2SO4 leaching liquor, leading to favorable conditions for the subsequent separation of Th(IV) and RE(III). The interaction of Ce(IV) and F and/or P enhances the roasting, leaching and extraction of Ce(IV) due to increasing of the stability of Ce(IV), and the formation of CeF3 and CePO4 after reductive stripping will benefit the utilization of F and P. For dealing with RE ores of high-content Ce, the clean process of oxidation roasting and Ce(IV)-F separation for Sichuan bastnaesite highlights the advantages of Ce(IV) based clean technique, which firstly demonstrates the comprehensive utilization of Ce(IV), Th(IV), F and RE(III) and prevention of environmental pollution from foun-tainhead. A preliminary flowsheet of two-step oxidation and extraction of Ce(IV) for Bayan Obo mixed ores was further proposed to process the oxidation and extraction of Ce(IV) in presence of both F and P, indicating the possibility of similar effects with clean process of Sichuan bastnaesite. Ce(IV) separation chemistry and clean technique will open up new realms for light RE resources utilization, meeting“Emission Standards of Pollutants from Rare Earths Industry”promulgated by China’s Ministry of Environment Protection (MOP) in 2011.

  17. The protective effects of cerium oxide nanoparticles against hepatic oxidative damage induced by monocrotaline

    Directory of Open Access Journals (Sweden)

    Kamal A Amin

    2011-01-01

    Full Text Available Kamal A Amin1, Mohamed S Hassan2, El-Said T Awad3, Khalid S Hashem11Department of Biochemistry, 2Department of Internal Medicine, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, Egypt; 3Department of Biochemistry, Faculty of Veterinary Medicine, Cairo University, Cairo, EgyptObjective: The objective of the present study was to determine the ability of cerium oxide (CeO2 nanoparticles to protect against monocrotaline (MCT-induced hepatotoxicity in a rat model.Method: Twenty male Sprague Dawley rats were arbitrarily assigned to four groups: control (received saline, CeO2 (given 0.0001 nmol/kg intraperitoneally [IP], MCT (given 10 mg/kg body weight IP as a single dose, and MCT + CeO2 (received CeO2 both before and after MCT. Electron microscopic imaging of the rat livers was carried out, and hepatic total glutathione (GSH, glutathione reductase (GR, glutathione peroxidase (GPX, glutathione S-transferase (GST, superoxide dismutase (SOD, and catalase (CAT enzymatic activities were quantified.Results: Results showed a significant MCT-induced decrease in total hepatic GSH, GPX, GR, and GST normalized to control values with concurrent CeO2 administration. In addition, MCT produced significant increases in hepatic CAT and SOD activities, which also ameliorated with CeO2.Conclusions: These results indicate that CeO2 acts as a putative novel and effective hepatoprotective agent against MCT-induced hepatotoxicity.Keywords: monocrotaline, ceruim oxide nanoparticle, hepatotoxicity, oxidative stress

  18. Effect of Cerium on Microstructure and Electrochemical Performance of Ti-V-Cr-Ni Electrode Alloy

    Institute of Scientific and Technical Information of China (English)

    Qiao Yuqing; Zhao Minshou; Zhu Xinjian; Cao Guangyi

    2007-01-01

    Effect of cerium on the microstructure and electrochemical performance of the Ti0.25V0.35-xCexCr0.1Ni0.3 (x=0, 0.005) electrode alloy was investigated by X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectrometry (FESEM-EDS), and electrochemical impedance spectroscopy (EIS) measurements. On the basis of XRD and FESEM-EDS analysis, the alloy was mainly composed of V-based solid solution with body-centered-cubic structure and TiNi-based secondary phase. Ce did not exist in two phases, instead, it existed as Ce-rich small white particles, with irregular edges, distributed near the grain boundaries of the V-based solid solution phase. Discharge capacity, cycle stability, and high-rate discharge ability of the alloy electrode were effectively improved with the addition of Ce at 293 K. It was very surprising that the charge retention was abnormal with larger discharge capacity after standing at the open circuit for 24 h. EIS indicated that addition of Ce improved the dynamic performance, which caused the charge transfer resistance (RT) to decrease and exchange current density (I0) to increase markedly. The exchange current density of the electrochemical reaction on the alloy surface with Ce addition was about 2.07 and 3.10 times larger than that of the alloy without Ce at 303 and 343 K, respectively. The diffusion coefficient of hydrogen (D) in the bulk alloy electrode decreased with addition of Ce, but it did not decrease so much, and the apparent activation energy (△rH) was far higher than that of the AB5 type alloy.

  19. Pulmonary toxicity of well-dispersed cerium oxide nanoparticles following intratracheal instillation and inhalation

    Energy Technology Data Exchange (ETDEWEB)

    Morimoto, Yasuo, E-mail: yasuom@med.uoeh-u.ac.jp; Izumi, Hiroto; Yoshiura, Yukiko; Tomonaga, Taisuke; Oyabu, Takako; Myojo, Toshihiko; Kawai, Kazuaki; Yatera, Kazuhiro [University of Occupational and Environmental Health (Japan); Shimada, Manabu; Kubo, Masaru [Hiroshima University (Japan); Yamamoto, Kazuhiro [National Institute of Advanced Industrial Science and Technology (AIST) (Japan); Kitajima, Shinichi [National Sanatorium Hoshizuka Keiaien (Japan); Kuroda, Etsushi [Osaka University, Laboratory of Vaccine Science, WPI Immunology Frontier Research Center (Japan); Kawaguchi, Kenji; Sasaki, Takeshi [National Institute of Advanced Industrial Science and Technology (AIST) (Japan)

    2015-11-15

    We performed inhalation and intratracheal instillation studies of cerium dioxide (CeO{sub 2}) nanoparticles in order to investigate their pulmonary toxicity, and observed pulmonary inflammation not only in the acute and but also in the chronic phases. In the intratracheal instillation study, F344 rats were exposed to 0.2 mg or 1 mg of CeO{sub 2} nanoparticles. Cell analysis and chemokines in bronchoalveolar lavage fluid (BALF) were analyzed from 3 days to 6 months following the instillation. In the inhalation study, rats were exposed to the maximum concentration of inhaled CeO{sub 2} nanoparticles (2, 10 mg/m{sup 3}, respectively) for 4 weeks (6 h/day, 5 days/week). The same endpoints as in the intratracheal instillation study were examined from 3 days to 3 months after the end of the exposure. The intratracheal instillation of CeO{sub 2} nanoparticles caused a persistent increase in the total and neutrophil number in BALF and in the concentration of cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-2, chemokine for neutrophil, and heme oxygenase-1 (HO-1), an oxidative stress marker, in BALF during the observation time. The inhalation of CeO{sub 2} nanoparticles also induced a persistent influx of neutrophils and expression of CINC-1, CINC-2, and HO-1 in BALF. Pathological features revealed that inflammatory cells, including macrophages and neutrophils, invaded the alveolar space in both studies. Taken together, the CeO{sub 2} nanoparticles induced not only acute but also chronic inflammation in the lung, suggesting that CeO{sub 2} nanoparticles have a pulmonary toxicity that can lead to irreversible lesions.

  20. Intermediate valence behavior of ternary cerium and uranium transition metal borides

    Science.gov (United States)

    Yang, K. N.; Torikachvili, M. S.; Maple, M. B.; Ku, H. C.

    1984-09-01

    Low-temperature specific heat, electrical resistivity, ac magnetic susceptibility, and dc magnetization measurements were made on ternary cerium and uranium transition metal borides with the general formula CeT3B2 (T=Co, Ru, Rh, and Ir) and UT3B2 (T=Co, Ru, and Ir). The compound CeRu3B2 was found to exhibit superconductivity below 0.68 K. The values of the electronic specific heat coefficient range from 9.7 mJ/mole-K2 for CeCo3B2 to 64 mJ/mole-K2 for UIr3B2. The electrical resistivity versus temperature curves of all of the compounds exhibit negative curvature and are reminiscent of valence fluctuation behavior. In the case of CeIr3B2, the electrical resistivity attains a maximum value at 180 K, while the dc magnetic susceptibility has a temperature dependence that is typical of intermediate valence Ce compounds, approaching a finite value at zero temperature. The electrical resistivity of the ferromagnetic compound CeRh3B2 reveals a rapid decrease in spin disorder resistivity below 120 K. The dc magnetic susceptibility of this material can be described as the sum of a constant term and a Curie-Weiss contribution with an effective magnetic moment of 1.01 µB per formula unit and a Curie-Weiss temperature of 119 K. Magnetization measurements on CeRh3B2 yield a saturation magnetic moment of 0.37 µB per formula unit and a Curie temperature of 113 K.

  1. Cerium anomaly across the mid-Tournaisian carbon isotope excursion (TICE)

    Science.gov (United States)

    Jiang, G.; Morales, D. C.; Maharjan, D. K.

    2015-12-01

    The Early Mississippian (ca. 359-345 Ma) represents one of the most important greenhouse-icehouse climate transitions in Earth history. Closely associated with this critical transition is a prominent positive carbon isotope excursion (δ13C ≥ +5‰) that has been documented from numerous stratigraphic successions across the globe. This δ13C excursion, informally referred to as the TICE (mid-Tournaisian carbon isotope excursion) event, has been interpreted as resulting from enhanced organic carbon burial, with anticipated outcomes including the lowering of atmospheric CO2 and global cooling, the growth of continental ice sheets and sea-level fall, and the increase of ocean oxygenation and ocean redox changes. The casual relationship between these events has been addressed from various perspectives but not yet clearly demonstrated. To document the potential redox change associated with the perturbation of the carbon cycle, we have analyzed rare earth elements (REE) and trace elements across the TICE in two sections across a shallow-to-deep water transect in the southern Great Basin (Utah and Nevada), USA. In both sections, the REE data show a significant positive cerium (Ce) anomaly (Ce/Ce* = Ce/(0.5La+0.5Pr)). Prior to the positive δ13C shift, most Ce/Ce* values are around 0.3 (between 0.2 and 0.4). Across the δ13C peak, Ce/Ce* values increase up to 0.87, followed by a decrease back to 0.2~0.3 after the δ13C excursion (Figure 1). The positive Ce anomaly is best interpreted as recording expansion of oxygen minimum zone and anoxia resulted from increased primary production. This is consistent with a significant increase of nitrogen isotopes (δ15N) across the δ13C peak. Integration of the carbon, nitrogen, and REE data demonstrates a responsive earth systems change linked to the perturbation of the Early Mississippian carbon cycle.

  2. Reinforcement of natural rubber latex with silica modified by cerium oxide:preparation and properties

    Institute of Scientific and Technical Information of China (English)

    张福全; 廖禄生; 王永周; 汪月琼; 黄红海; 李普旺; 彭政; 曾日中

    2016-01-01

    Variable masses of nano cerium oxide (CeO2) were added into nano silica (SiO2) to prepare the well-dispersed SiO2-CeO2 suspension (SiO2-CeO2), cetyltrimethyl ammonium bromide (CTAB) was used to adjust the compatibility of SiO2-CeO2 with rubber matrix, then SiO2-CeO2 modified by CTAB and curing formulas were mixed with fresh natural rubber (NR) latex to prepare NR/SiO2-CeO2 nanocomposites that contained 0–10 parts of CeO2 by a new emulsion compounding method. The morphologies, cure characteristics, mechanical properties and thermal-oxidative stability of NR/SiO2-CeO2 nanocomposites were investigated. The re-sults revealed that the presence of CeO2 in NR/SiO2-CeO2nanocomposites was favorable for enhancing the interaction between NR matrix and fillers, helped to get smaller SiO2-CeO2 particles with narrower particle size distribution, further improved the crosslink densities and mechanical properties of NR/SiO2-CeO2 nanocomposites vulcanizates. Meanwhile, the addition of CeO2 increased the active energy at least 4.66%, obviously improved the thermal-oxidative aging-inhibiting properties of NR/SiO2-CeO2 nanocomposites. Additionally, nanocomposites containing CeO2 promotedTg shift to high temperature direction, causing the nanocomposites featured higher tanδ at 0 ºC and lower tanδ at 60 ºC and exhibited comparable wet grip and lower rolling resistance when NR/SiO2-CeO2nano-composites were used in tire tread compound.

  3. Magmatic oxygen fugacity estimated using zircon-melt partitioning of cerium

    Science.gov (United States)

    Smythe, Duane J.; Brenan, James M.

    2016-11-01

    Using a newly-calibrated relation for cerium redox equilibria in silicate melts (Smythe and Brenan, 2015), and an internally-consistent model for zircon-melt partitioning of Ce, we provide a method to estimate the prevailing redox conditions during crystallization of zircon-saturated magmas. With this approach, oxygen fugacities were calculated for samples from the Bishop tuff (USA), Toba tuff (Indonesia) and the Nain plutonic suite (Canada), which typically agree with independent estimates within one log unit or better. With the success of reproducing the fO2 of well-constrained igneous systems, we have applied our Ce-in-zircon oxygen barometer to estimating the redox state of Earth's earliest magmas. Using the composition of the Jack Hills Hadean zircons, combined with estimates of their parental magma composition, we determined the fO2 during zircon crystallization to be between FMQ -1.0 to +2.5 (where FMQ is the fayalite-magnetite-quartz buffer). Of the parental magmas considered, Archean tonalite-trondhjemite-granodiorite (TTG) compositions yield zircon-melt partitioning most similar to well-constrained modern suites (e.g., Sano et al., 2002). Although broadly consistent with previous redox estimates from the Jack Hills zircons, our results provide a more precise determination of fO2, narrowing the range for Hadean parental magmas by more than 8 orders of magnitude. Results suggest that relatively oxidized magmatic source regions, similar in oxidation state to that of 3.5 Ga komatiite suites, existed by ∼4.4 Ga.

  4. Characterization and activity of visible-light-driven TiO 2 photocatalyst codoped with nitrogen and cerium

    Science.gov (United States)

    Liu, Chao; Tang, Xinhu; Mo, Cehui; Qiang, Zhimin

    2008-04-01

    Nitrogen and cerium codoped TiO 2 photocatalysts were prepared by a modified sol-gel process with doping precursors of cerium nitrate and urea, and characterized by X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray photoelectron spectra (XPS) and ultraviolet-visible light diffuse reflectance spectra (UV-vis DRS). Results indicate that anatase TiO 2 is the dominant crystalline type in as-prepared samples, and CeO 2 crystallites appear as the doping ratio of Ce/Ti reaches to 3.0 at%. The TiO 2 starts to transform from amorphous phase to anatase at 987.1 K during calcination, according to the TG-DSC curves. The XPS show that three major metal ions of Ce 3+, Ce 4+, Ti 4+ and one minor metal ion of Ti 3+ coexist on the surface. The codoped TiO 2 exhibits significant absorption within the range of 400-500 nm compared to the non-doped and only nitrogen-doped TiO 2. The enhanced photocatalytic activity of the codoped TiO 2 is demonstrated through degradation of methyl orange under visible light irradiation.

  5. Effect of cerium additive on aluminum-based chemical conversion coating on AZ91D magnesium alloy

    Science.gov (United States)

    Wang, Ximei; Zhu, Liqun; He, Xiang; Sun, Fenglou

    2013-09-01

    Based on environmentally friendly and recycling of magnesium alloys, chemical conversion coatings were prepared in aluminum nitrate solutions with cerium nitrate additive on AZ91D magnesium alloys surfaces. Effect of additive's concentration on the surface morphology, composition and corrosion resistance of aluminum-based conversion coating on magnesium alloys was studied. The surface morphology, composition, microstructure and corrosion resistance of conversion coatings were investigated using scanning electron microscopy (SEM), X-ray energy dispersion spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical tests respectively. The results show that the cerium content of the conversion coatings surface increased with increasing additive concentration. The conversion coatings’ morphologies first gradually became dense and the micro-cracks on the coating surface became narrow with the increase of the additive concentration. Then the coatings’ morphologies became bad and the micro-cracks widened after the additive concentration reached 0.005 mol/L. When the additive concentration was 0.005 mol/L, the conversion coating consists of Al(OH)3, Al2O3, Mg(OH)2, MgO, CeO2 and Ce2O3; the conversion coating surface morphology was the densest and the micro-cracks were the narrowest, and the corrosion resistance was also the best.

  6. Nano-cerium vanadate: a novel inorganic ion exchanger for removal of americium and uranium from simulated aqueous nuclear waste.

    Science.gov (United States)

    Banerjee, Chayan; Dudwadkar, Nilesh; Tripathi, Subhash Chandra; Gandhi, Pritam Maniklal; Grover, Vinita; Kaushik, Chetan Prakash; Tyagi, Avesh Kumar

    2014-09-15

    Cerium vanadate nanopowders were synthesized by a facile low temperature co-precipitation method. The product was characterized by X-ray diffraction and transmission electron microscopy and found to consist of ∼25 nm spherical nanoparticles. The efficiency of these nanopowders for uptake of alpha-emitting radionuclides (233)U (4.82 MeV α) and (241)Am (5.49 MeV α, 60 keV γ) has been investigated. Thermodynamically and kinetically favorable uptake of these radionuclides resulted in their complete removal within 3h from aqueous acidic feed solutions. The uptake capacity was observed to increase with increase in pH as the zeta potential value decreased with the increase in pH but effect of ionic strength was insignificant. Little influence of the ions like Sr(2+), Ru(3+), Fe(3+), etc., in the uptake process indicated CeVO4 nanopowders to be amenable for practical applications. The isotherms indicated predominant uptake of the radioactive metal ions in the solid phase of the exchanger at lower feed concentrations and linear Kielland plots with positive slopes indicated favorable exchange of the metal ions with the nanopowder. Performance comparison with the other sorbents reported indicated excellent potential of nano-cerium vanadate for removing americium and uranium from large volumes of aqueous acidic solutions.

  7. Selective catalytic reduction of nitric oxide by methane over cerium and silver ion-exchanged ZSM-5 zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhijiang; Flytzani-Stephanopoulos, Maria [Department of Chemical Engineering, Tufts University, Medford, MA (United States)

    1997-12-31

    A new catalyst comprising cerium and silver ion-exchanged ZSM-5 zeolite is reported in this paper, for the reduction of nitric oxide by methane in the presence of excess oxygen. The bi-cation exchanged Ce-Ag-ZSM-5 catalyst was very active for this reaction, while either Ce-ZSM-5 or Ag-ZSM-5 alone showed low activity. The presence of oxygen in the feed gas mixture enhanced the activity of the catalyst and the NO conversion to N{sub 2} increased with the CH{sub 4}/NO ratio and Ag loading of the zeolite. The presence of water vapor had a small adverse effect on the catalyst activity. The coexistence of Ce and Ag ions in the zeolite is crucial for achieving high NO conversion to N{sub 2}. A small amount of cerium is adequate to promote the selective catalytic reduction of NO. The two main functions of Ce ions are (1) to provide the Ag ion sites with NO{sub 2} by catalyzing the oxidation of NO to NO{sub 2} and (2) to suppress the direct CH{sub 4} oxidation to CO{sub 2}. The Ag sites are the active centers where the reaction of NO{sub 2} with CH{sub 4} takes place

  8. Catalytic ozonation of oxalate with a cerium supported palladium oxide: An efficient degradation not relying on hydroxyl radical oxidation

    KAUST Repository

    Zhang, Tao

    2011-11-01

    The cerium supported palladium oxide (PdO/CeO 2) at a low palladium loading was found very effective in catalytic ozonation of oxalate, a probe compound that is difficult to be efficiently degraded in water with hydroxyl radical oxidation and one of the major byproducts in ozonation of organic matter. The oxalate was degraded into CO 2 during the catalytic ozonation. The molar ratio of oxalate degraded to ozone consumption increased with increasing catalyst dose and decreasing ozone dosage and pH under the conditions of this study. The maximum molar ratio reached around 1, meaning that the catalyst was highly active and selective for oxalate degradation in water. The catalytic ozonation, which showed relatively stable activity, does not promote hydroxyl radical generation from ozone. Analysis with ATR-FTIR and in situ Raman spectroscopy revealed that 1) oxalate was adsorbed on CeO 2 of the catalyst forming surface complexes, and 2) O 3 was adsorbed on PdO of the catalyst and further decomposed to surface atomic oxygen (*O), surface peroxide (*O 2), and O 2 gas in sequence. The results indicate that the high activity of the catalyst is related to the synergetic function of PdO and CeO 2 in that the surface atomic oxygen readily reacts with the surface cerium-oxalate complex. This kind of catalytic ozonation would be potentially effective for the degradation of polar refractory organic pollutants and hydrophilic natural organic matter. © 2011 American Chemical Society.

  9. Effect of Cerium on Microstructures and High Temperature Oxidation Resistance of An Nb-Si System In-Situ Composite

    Institute of Scientific and Technical Information of China (English)

    Liu Aiqin; Sun Lu; Li Shusuo; Han Yafang

    2007-01-01

    Nb-16Si-24Ti-6Cr-6Al-2Hf-xCe (x=0, 0.05, 0.1, 0.25, 0.5, 1 (%, atom fraction)) in situ composites were prepared by arc melting. The microstructure and the effect of rare earth element cerium on 1250 ℃ oxidation resistance of the composites were investigated with scanning electron microscopy (SEM) and X-ray energy disperse spectrum (EDS), as well as X-ray diffraction (XRD). The experimental results showed that the high temperature oxidation resistance of the alloy was improved by adding a proper amount of cerium (Ce). The effect of Ce was considered as the concurrent of the following three factors: first, the oxide of Ce formed in the interface reduced the internal oxidation rate; second, the lath shaped oxide containing Ce increased the cracking resistance and reduced the expansion of the oxide scale; and third, the decrease of the silicide volume fraction on account of Ce addition reduces the power of the sample resisting oxy gen penetration.

  10. Nafion-porous cerium oxide nanotubes composite membrane for polymer electrolyte fuel cells operated under dry conditions

    Science.gov (United States)

    Ketpang, Kriangsak; Oh, Kwangjin; Lim, Sung-Chul; Shanmugam, Sangaraju

    2016-10-01

    A composite membrane operated in polymer electrolyte fuel cells (PEFCs) under low relative humidity (RH) is developed by incorporating cerium oxide nanotubes (CeNT) into a perfluorosulfonic acid (Nafion®) membrane. Porous CeNT is synthesized by direct heating a precursor impregnated polymer fibers at 500 °C under an air atmosphere. Compared to recast Nafion and commercial Nafion (NRE-212) membranes, the Nafion-CeNT composite membrane generates 1.1 times higher power density at 0.6 V, operated at 80 °C under 100% RH. Compared to Nafion-cerium oxide nanoparticles (Nafion-CeNP) membrane, the Nafion-CeNT provides 1.2 and 1.7 times higher PEFC performance at 0.6 V when operated at 80 °C under 100% and 18% RH, respectively. Additionally, the Nafion-CeNT composite membrane exhibits a good fuel cell operation under 18% RH at 80 °C. Specifically, the fluoride emission rate of Nafion-CeNT composite membrane is 20 times lower than that of the commercial NRE-212 membrane when operated under 18% RH at 80 °C for 96 h. The outstanding PEFC performance and durability operated under dry conditions is mainly attributed to the facile water diffusion capability as well as the effective hydroxyl radical scavenging property of the CeNT filler, resulting in significantly mitigating both the ohmic resistance and Nafion membrane degradation.

  11. Sulfonated macro-RAFT agents for the surfactant-free synthesis of cerium oxide-based hybrid latexes.

    Science.gov (United States)

    Garnier, Jérôme; Warnant, Jérôme; Lacroix-Desmazes, Patrick; Dufils, Pierre-Emmanuel; Vinas, Jérôme; van Herk, Alex

    2013-10-01

    Three types of amphiphatic macro-RAFT agents were employed as compatibilizers to promote the polymerization reaction at the surface of nanoceria for the synthesis of CeO2-based hybrid latexes. Macro-RAFT copolymers and terpolymers were first synthesized employing various combinations of butyl acrylate as a hydrophobic monomer and acrylic acid (AA) and/or 2-acrylamido-2-methylpropane sulfonic acid (AMPS) as hydrophilic monomers. After characterizing the adsorption of these macro-RAFT agents at the cerium oxide surface by UV-visible spectrometry, emulsion copolymerization reactions of styrene and methyl acrylate were then carried out in the presence of the surface-modified nanoceria. Dynamic Light Scattering and cryo-Transmission Electron Microscopy were employed to confirm the hybrid structure of the final CeO2/polymer latexes, and proved that the presence of acrylic acid units in amphiphatic macro-RAFT agents enabled an efficient formation of hybrid structures, while the presence of AMPS units, when combined with AA units, resulted in a better distribution of cerium oxide nanoclusters between latex particles.

  12. Effect of variable cerium concentration on photoluminescence behaviour in ZrO2 phosphor synthesized by combustion synthesis method

    Science.gov (United States)

    Dubey, Vikas; Kaur, Jagjeet

    2016-05-01

    Present paper reports synthesis and characterization of trivalent cerium (Ce3+) doped zirconium dioxide (ZrO2) phosphors. Effect of variable concentration of cerium on photoluminescence (PL) is studied. Samples were prepared by combustion synthesis technique which is suitable for less time taking techniques also for large scale production for phosphors. Starting material used for sample preparation are Zr(NO3)3 and Ce(NO3)3 and urea used as a fuel. All prepared phosphor with variable concentration of Ce3+ (0.1 to 2mol%) was studied by photoluminescence analysis it is found that the excitation spectra of prepared phosphor shows broad excitation centred at 390nm. The excitation spectra with variable concentration of Ce3+ show strong peaks at 447nm. Spectrophotometric determinations of peaks are evaluated by Commission Internationale de I'Eclairage technique. Using this phosphor, the desired CIE values including emissions throughout the violet (390 nm) and blue (427 nm) of the spectra were achieved. Efficient blue light emitting diodes were fabricated using Ce3+ doped phosphor based on near ultraviolet (NUV) excited LED lights.

  13. Effect of Rare Earth Cerium on Yield Strength Anisotropy of Al-Li Alloy Sheet and Its Theoretical Prediction

    Institute of Scientific and Technical Information of China (English)

    赵志龙; 刘林; 陈铮

    2004-01-01

    The variation of yield strength along rolling direction, transverse direction and 45° to transverse direction of 2090 Al-Li alloy and 2090+Ce alloy sheet containing rare earth cerium was comparatively investigated. The difference of deformation texture in these two alloy sheets was analyzed by means of X-ray orientation distribution function (ODF). The results show that cerium has the effects of enhancing the Brass and S rolling texture components and reducing the recrystallized texture components of Cube and Goss. This is the reason that the anisotropic degree of yield strength in 2090+Ce sheet is higher than that of 2090 alloy sheet. The prediction of yield strength along various orientations in two alloy sheets was done based on Taylor/Bishop-Hill model, and the strengthening effect of grain boundary was evaluated using Hall-Petch relationship. A modified plastic inclusion model was proposed using the concept of grain-orientation factor and T1 phase orientation factor by fitting with tensile test results.

  14. Effective improvement of interface modified strontium titanate based solid oxide fuel cell anodes by infiltration with nano-sized palladium and gadolinium-doped cerium oxide

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Høgh, Jens Valdemar Thorvald; Zhang, Wei

    2013-01-01

    The development of low temperature solid oxide fuel cell (SOFC) anodes by infiltration of Pd/Gd-doped cerium oxide (CGO) electrocatalysts in Nb-doped SrTiO3 (STN) backbones has been investigated. Modification of the electrode/electrolyte interface by thin layer of spin-coated CGO (400-500 nm...

  15. Pure cerium dioxide preparation for use as spectrochemical standard and analysed by inductively coupled plasma mass spectrometry (SF ICP-MS)

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Carlos A. da S.; Abrao, Alcidio; Rocha, Soraya M.R. da; Vasconcellos, Mari E. de; Seneda, Jose A.; Forbicini, Christina A.L.G. de O. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: cqueiroz@ipen.br; Pedreira, Walter R.; Boaventura, Geraldo R. [Brasilia Univ., DF (Brazil). Dept. de Geociencias; Pimentel, Marcio M. [Fundacao Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), Sao Paulo, SP (Brazil)]. E-mail: walter.pedreira@fundacentro.gov.br

    2005-11-15

    several years, IPEN/CNEN-SP has been working in the separation of the Rare Earth (RE) elements. A simple and economic procedure for the purification of technical grade cerium concentrate is described. The highly pure cerium dioxide is designed to be used as spectrochemical standard. It is obtained by association of the fractional precipitation technique, in the system RECl{sub 3}/NH{sub 4}OH/ Air/H{sub 2}O{sub 2}, to enrich the cerium up to 90% and then it is upgraded by ion exchange technique to 99.99% CeO{sub 2}. The quality control warranty was accomplished by inductively coupled mass spectrometry (ICP-MS) and neutron activation analysis. The collected values for the accompanying Rare Earth elements in a CeO{sub 2} sample are the following (ppm): La(36), Pr(19), Nd(161), Sm(11), Eu(5.3), Gd(113), Tb(89), Dy(2), Ho(0.05), Er(1), Tm(<0.05), Yb(11), Lu(19) and Y(2.1), respectively. The purity of this cerium oxide is comparable to the international spectrographic standards. (author)

  16. Effect of cerium and thermomechanical processing on microstructure and mechanical properties of Fe–10.5Al–0.8C alloy

    Indian Academy of Sciences (India)

    R G Baligidad; Shivkumar Khaple

    2009-10-01

    The effect of cerium content and thermomechanical processing on structure and properties of Fe–10.5 wt.%Al–0.8 wt%C alloy has been investigated. Alloys were prepared by a combination of air induction melting with flux cover (AIMFC) and electroslag remelting (ESR). The ESR ingots were hot-forged and hotrolled at 1373 K as well as warm-rolled at 923 K and heat-treated. Hot-rolled, warm-rolled and heat treated alloys were examined using optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction to understand the microstructure of these alloys. The ternary, Fe–10.5 wt.%Al–0.8 wt.%C alloy showed the presence of two phases; Fe–Al with bcc structure, and large volume fraction of Fe3AlC0.5 precipitates. Addition of cerium to Fe–10.5 wt.%Al–0.8 wt.%C alloy resulted in three phases, the additional phase being small volume fraction of fine cerium oxy-carbide precipitates. Improvement in tensile elongation from 3–6.4% was achieved by increasing the cerium content from 0.01–0.2 wt.% and further improvement in tensile elongation from 6.4–10% was achieved by warm-rolling and heat treatment.

  17. Toxicity assessment of aggregated/agglomerated cerium oxide nanoparticles in an in vitro 3D airway model: The influence of mucociliary clearance

    NARCIS (Netherlands)

    Kuper, C.F.; Gröllers-Mulderij, M.; Maarschalkerweerd, T.; Meulendijks, N.M.M.; Reus, A.; Acker, F. van; Zondervan-van den Beuken, E.K.; Wouters, M.E.L.; Bijlsma, S.; Kooter, I.M.

    2014-01-01

    We investigated the toxicity of aggregated nanoparticles of cerium oxide (CeO2) using an in vitro 3D human bronchial epithelial model that included a mucociliary apparatus (MucilAir™). CeO2 was dispersed in saline and applied to the apical surface of the model. CeO2 did not induce distinct effects i

  18. Kinetics and Mechanism of Ruthenium(III) Catalyzed Oxidation of Butanone and Uncatalyzed Oxidation of Cychlohexanone by Cerium(IV) in Acid Sulphate Medium

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Priyamvada; Hemkar, Shalini; Khandelwal, C. L.; Sharma, P. D. [Univ. of Rajasthan, Jaipur (India)

    2012-02-15

    The kinetics of ruthenium(III) chloride catalyzed oxidation of butanone and uncatalyzed oxidation of cyclohexanone by cerium(IV) in sulphuric acid medium have been studied. The kinetic rate law(I) in case of butanone conforms to the proposed mechanism. Kinetics and activation parameters have been evaluated conventionally. Kinetically preferred mode of reaction is via ketonic and not the enolic forms.

  19. Characteristics of rare earth elements and cerium anomalies in cherts from the Paleo-Tethys in Changning-Menglian belt in western Yunnan, China

    Institute of Scientific and Technical Information of China (English)

    丁林; 钟大赉

    1996-01-01

    Based on research on rare earth elements (REEs) and cerium anomalies in cherts from the Paleo-Tethys, their depositional environments are shown and the evolution of the Paleo-Tethys is traced. The amount of terrigenous, biogenic and hydrothermal inputs are the important factors that affect the REEs composition of the cherts.

  20. EMISSION REDUCTION FROM A DIESEL ENGINE FUELED BY CERIUM OXIDE NANO-ADDITIVES USING SCR WITH DIFFERENT METAL OXIDES COATED CATALYTIC CONVERTER

    Directory of Open Access Journals (Sweden)

    B. JOTHI THIRUMAL

    2015-11-01

    Full Text Available This paper reports the results of experimental investigations on the influence of the addition of cerium oxide in nanoparticle form on the major physiochemical properties and the performance of diesel. The fuel is modified by dispersing the catalytic nanoparticle by ultrasonic agitation. The physiochemical properties of sole diesel fuel and modified fuel are tested with ASTM standard procedures. The effects of the additive nanoparticles on the individual fuel properties, the engine performance, and emissions are studied, and the dosing level of the additive is optimized. Cerium oxide acts as an oxygen-donating catalyst and provides oxygen for the oxidation of CO during combustion. The active energy of cerium oxide acts to burn off carbon deposits within the engine cylinder at the wall temperature and prevents the deposition of non-polar compounds on the cylinder wall which results in reduction in HC emission by 56.5%. Furthermore, a low-cost metal oxide coated SCR (selective catalyst reduction, using urea as a reducing agent, along with different types of CC (catalytic converter, has been implemented in the exhaust pipe to reduce NOx. It was observed that a reduction in NOx emission is 50–60%. The tests revealed that cerium oxide nanoparticles can be used as an additive in diesel to improve complete combustion of the fuel and reduce the exhaust emissions significantly.

  1. Simple cerium-triethanolamine complex: Synthesis, characterization, thermal decomposition and its application to prepare ceria support for platinum catalysts used in methane steam reforming

    Science.gov (United States)

    Wattanathana, Worawat; Nootsuwan, Nollapan; Veranitisagul, Chatchai; Koonsaeng, Nattamon; Laosiripojana, Navadol; Laobuthee, Apirat

    2015-06-01

    Cerium-triethanolamine complex was synthesized by simple complexation method in 1-propanol solvent using cerium(III) chloride as a metal source and triethanolamine as a ligand. The structures of the prepared complex were proposed based on FT-IR, FT-Raman and ESI-MS results as equimolar of triethanolamine and cerium chelated complex having monomeric tricyclic structure with and without chloride anion as another coordinating group known as ceratrane. The complex was used as a precursor for ceria material done by thermal decomposition. XRD result revealed that when calcined at 600 °C for 2 h, the cerium complex was totally turned into pure ceria with cubic fluorite structure. The obtained ceria was then employed to synthesize platinum doped ceria catalysts for methane steam reforming. Various amounts of platinum i.e. 1, 3, 5 and 10 mol percents were introduced on the ceria support by microwave-assisted wetness impregnation using ammonium tetrachloroplatinate(II). The platinum-impregnated ceria powders were subjected to calcination in 10% hydrogen/helium atmosphere at 500 °C for 3 h to reduce platinum(II) to platinum(0). XRD patterns of the catalysts confirmed that the platinum particles doped on the ceria support were in the form of platinum(0). Catalytic activity test showed that the catalytic activities got higher as the amounts of platinum doped increased. Besides, the portions of coke formation on the surface of catalysts were reduced as the amounts of platinum doped increased.

  2. Steric and electronic effects of 1,3-disubstituted cyclopentadienyl ligands on metallocene derivatives of Cerium, Titanium, Manganese, and Iron

    Energy Technology Data Exchange (ETDEWEB)

    Sofield, Chadwick Dean [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    Sterically demanding 1,3-disubstituted cyclopentadienyl ligands were used to modify the physical properties of the corresponding metallocenes. Sterically demanding ligands provided kinetic stabilization for trivalent cerium compounds. Tris(di-t-butylcyclopentadienyl)cerium was prepared and anion competition between halides and cyclopentadienyl groups which had complicated synthesis of the tris(cyclopentadienyl)compound was qualitatively examined. Bis(di-t-butylcyclopentadienyl)cerium methyl was prepared and its rate of decomposition, by ligand redistribution, to tris(di-t-butylcyclopentadienyl)cerium was shown to be slower than the corresponding rate for less sterically demanding ligands. Asymmetrically substituted ligands provided a symmetry label for examination of chemical exchange processes. Tris[trimethylsilyl(t-butyl)cyclopentadienyl]cerium was prepared and the rate of interconversion between the C1 and C3 isomers was examined. The enthalpy difference between the two distereomers is 7.0 kJ/mol. The sterically demanding cyclopentadienyl ligands ansa-di-t-butylcyclopentadiene (Me2Si[(Me3C)2C5H3]2), ansa-bis(trimethylsilyl)cyclopentadiene (Me2Si[(Me3Si)2C5H3]2) and tetra-t-butylfulvalene and metallocene derivatives of the ligands were prepared and their structures were examined by single crystal X-ray crystallography. The effect that substituents on the cyclopentadienyl ring have on the pi-electron system of the ligand was examined through interaction between ligand and metal orbitals. A series of 1,3-disubstituted manganocenes was prepared and their electronic states were determined by solid-state magnetic susceptibility, electron paramagnetic resonance, X-ray crystallography, and variable temperature UV-vis spectroscopy. Spin-equilibria in [(Me3C)2C5H3]2Mn and [(Me3

  3. Recent Developments on 1,2,4-Triazole Nucleus in Anticancer Compounds: A Review.

    Science.gov (United States)

    Kaur, Ramandeep; Dwivedi, Ashish Ranjan; Kumar, Bhupinder; Kumar, Vinod

    2016-01-01

    1,2,4-triazole is an important nucleus present in a large number of compounds. More than thirty-five compounds containing this nucleus are introduced into the market. 1,2,4-triazole nucleus is stable to metabolism and acts as an important pharmacophore by interacting at the active site of a receptor as hydrogen bond acceptor and as a donor. Due to its polar nature, the triazole nucleus can increase the solubility of the ligand and it can significantly improve the pharmacological profile of the drug. A large number of 1,2,4-triazole derivatives are reported to possess a wide range of bioactivities including anti-cancer activity. This review article describes the role of 1,2,4-triazole nucleus in different types of anti-cancer agents such as nucleoside based anti-cancer agents, kinase inhibitors, tubulin modulators, aromatase and steroid sulfatase inhibitors, methionine aminopeptidase inhibitors, tankyrase inhibitors and metal complex based anti-cancer agents. It is expected that the current review article will provide insight into various ligand-receptor interactions and help in the rational design and development of novel 1,2,4-triazole based anti-cancer drugs with improved selectivity for cancer cells.

  4. Exosome-Based Delivery of miR-124 in a Huntington’s Disease Model

    Science.gov (United States)

    Lee, Soon-Tae; Im, Wooseok; Ban, Jae-Jun; Lee, Mijung; Jung, Keun-Hwa; Lee, Sang Kun; Chu, Kon; Kim, Manho

    2017-01-01

    Objective Huntington’s disease (HD) is a genetic neurodegenerative disease that is caused by abnormal CAG expansion. Altered microRNA (miRNA) expression also causes abnormal gene regulation in this neurodegenerative disease. The delivery of abnormally downregulated miRNAs might restore normal gene regulation and have a therapeutic effect. Methods We developed an exosome-based delivery method to treat this neurodegenerative disease. miR-124, one of the key miRNAs that is repressed in HD, was stably overexpressed in a stable cell line. Exosomes were then harvested from these cells using an optimized protocol. The exosomes (Exo-124) exhibited a high level of miR-124 expression and were taken up by recipient cells. Results When Exo-124 was injected into the striatum of R6/2 transgenic HD mice, expression of the target gene, RE1-Silencing Transcription Factor, was reduced. However, Exo-124 treatment did not produce significant behavioral improvement. Conclusion This study serves as a proof of concept for exosome-based delivery of miRNA in neurodegenerative diseases. PMID:28122430

  5. The {sup 124}Sb activity standardization by gamma spectrometry for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, M.C.M. de, E-mail: marcandida@yahoo.com.b [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes, Instituto de Radioprotecao e Dosimetria, Comissao Nacional de Energia Nuclear (SEMRA/LNMRI/IRD/CNEN), Av. Salvador Allende s/n, Recreio, Rio de Janeiro, RJ, CEP 22780-160 (Brazil); Iwahara, A.; Delgado, J.U.; Poledna, R.; Silva, R.L. da [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes, Instituto de Radioprotecao e Dosimetria, Comissao Nacional de Energia Nuclear (SEMRA/LNMRI/IRD/CNEN), Av. Salvador Allende s/n, Recreio, Rio de Janeiro, RJ, CEP 22780-160 (Brazil)

    2010-07-21

    This work describes a metrological activity determination of {sup 124}Sb, which can be used as radiotracer, applying gamma spectrometry methods with hyper pure germanium detector and efficiency curves. This isotope with good activity and high radionuclidic purity is employed in the form of meglumine antimoniate (Glucantime) or sodium stibogluconate (Pentostam) to treat leishmaniasis. {sup 124}Sb is also applied in animal organ distribution studies to solve some questions in pharmacology. {sup 124}Sb decays by {beta}-emission and it produces several photons (X and gamma rays) with energy varying from 27 to 2700 keV. Efficiency curves to measure point {sup 124}Sb solid sources were obtained from a {sup 166m}Ho standard that is a multi-gamma reference source. These curves depend on radiation energy, sample geometry, photon attenuation, dead time and sample-detector position. Results for activity determination of {sup 124}Sb samples using efficiency curves and a high purity coaxial germanium detector were consistent in different counting geometries. Also uncertainties of about 2% (k=2) were obtained.

  6. White spot syndrome virus envelope protein VP124 involved in the virus infection

    Institute of Scientific and Technical Information of China (English)

    ZHU Yanbing; WU Chenglin; YANG Feng

    2008-01-01

    White spot syndrome virus(WSSV)is one of the major shrimp pathogens causing large economic losses to shrimp farming.In an attempt to identify the envelope proteins involved in the virus infection,purified WSSV virions were mixed with three antisera against WSSV envelope proteins(VP39,VP124 and VP187),individually.And then they were injected intramuscularly into crayfish (Procambarus clarkii) to conduct in vivo neutralization assays.The results showed that for groups injected with virions only and groups injected with the mixture of virions and antiserum against VP124,the crayfish mortalities were 100% and 60% on the 8th day postinfection,individually.The virus infection could be delayed or neutralized by antibody against the envelope pro-tein VP124.Quantitative PCR was used to further investigate the influence of three antisera described above on the virus infec-tion.The results showed that the antiserum against VP124 could restrain the propagation of WSSV in crayfish.All of the results suggested that the viral envelope protein VP124 played a role in WSSV infection.

  7. Methylation-mediated silencing and tumour suppressive function of hsa-miR-124 in cervical cancer

    Directory of Open Access Journals (Sweden)

    le Sage Carlos

    2010-06-01

    Full Text Available Abstract Background A substantial number of microRNAs (miRNAs is subject to epigenetic silencing in cancer. Although epigenetic silencing of tumour suppressor genes is an important feature of cervical cancer, little is known about epigenetic silencing of miRNAs. Since DNA methylation-based silencing of hsa-miR-124 occurs in various human cancers, we studied the frequency and functional effects of hsa-miR-124 methylation in cervical carcinogenesis. Results Quantitative MSP analysis of all 3 loci encoding the mature hsa-miR-124 (hsa-miR-124-1/-2/-3 showed methylation in cervical cancer cell lines SiHa, CaSki and HeLa as well as in late passages of human papillomavirus (HPV type 16 or 18 immortalised keratinocytes. Treatment of SiHa cells with a demethylating agent reduced hsa-miR-124 methylation levels and induced hsa-miR-124 expression. In HPV-immortalised keratinocytes increased methylation levels were related to reduced hsa-miR-124 expression and higher mRNA expression of IGFBP7, a potential hsa-miR-124 target gene. Ectopic hsa-miR-124 expression in SiHa and CaSki cells decreased proliferation rates and migratory capacity. Combined hsa-miR-124-1 and/or hsa-miR-124-2 methylation analysis of 139 cervical tissue specimens showed an increasing methylation frequency from 0% in normal tissues up to 93% in cervical carcinomas. Increased methylation levels of hsa-miR-124-1 and hsa-miR-124-2 were significantly correlated with reduced hsa-miR-124 expression in cervical tissue specimens. Combined hsa-miR-124-1 and/or hsa-miR-124-2 methylation analysis of 43 cervical scrapes of high-risk HPV positive women was predictive of underlying high-grade lesions. Conclusions DNA methylation-based silencing of hsa-miR-124 is functionally involved in cervical carcinogenesis and may provide a valuable marker for improved detection of cervical cancer and its high-grade precursor lesions.

  8. Fluorine for Hydrogen Exchange in the Hydrofluorobenzene Derivatives C6HxF(6-x), where x = 2, 3, 4 and 5 by Monomeric [1,2,4-(Me3C)3C5H2]2CeH; The Solid State Isomerization of [1,2,4-(Me3C)3C5H2]2Ce(2,3,4,5-C6HF4) to [1,2,4-(Me3C)3C5H2]2Ce(2,3,4,6-C6HF4)

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Richard; Werkema, Evan L.; Andersen, Richard A.

    2008-04-21

    The reaction between monomeric bis(1,2,4-tri-t-butylcyclopentadienyl)cerium hydride, Cp'2CeH, and several hydrofluorobenzene derivatives is described. The aryl derivatives that are the primary products, Cp'2Ce(C6H5-xFx) where x = 1,2,3,4, are thermally stable enough to be isolated in only two cases, since all of them decompose at different rates to Cp'2CeF and a fluorobenzyne; the latter is trapped by either solvent when C6D6 is used or by a Cp'H ring when C6D12 is the solvent. The trapped products are identified by GCMS analysis after hydrolysis. The aryl derivatives are generated cleanly by reaction of the metallacycle, Cp'((Me3C)2C5H2C(Me2)CH2)Ce, with a hydrofluorobenzene and the resulting arylcerium products, in each case, are identified by their 1H and 19F NMR spectra at 20oC. The stereochemical principle that evolves from these studies is that the thermodynamic isomer is the one in which the CeC bond is flanked by two ortho-CF bonds. This orientation is suggested to arise from the negative charge that is localized on the ipso-carbon atom due to Co(delta+)-Fo(delta-) polarization. The preferred regioisomer is determined by thermodynamic rather than kinetic effects; this is illustrated by the quantitative, irreversible solid-state conversion at 25oC over two months of Cp'2Ce(2,3,4,5-C6HF4) to Cp'2Ce(2,3,4,6-C6HF4), an isomerization that involves a CeC(ipso) for C(ortho)F site exchange.

  9. Theoretical study of projectile fragmentation in the reactions $^{112}$Sn + $^{112}$Sn and $^{124}$Sn + $^{124}$Sn at 1 GeV/nucleon

    CERN Document Server

    Imal, H; Buyukcizmeci, N; Ogul, R; Botvina, A S; Trautmann, W

    2014-01-01

    We analyze the production cross sections and isotopic distributions of projectile-like residues in the reactions $^{112}$Sn + $^{112}$Sn and $^{124}$Sn + $^{124}$Sn at an incident beam energy of 1 GeV/nucleon measured with the FRS fragment separator at the GSI laboratory. Calculations within the statistical multifragmentation model (SMM) for an ensemble of excited sources were performed with ensemble parameters determined previously for similar reactions at 600 MeV/nucleon. The obtained good agreement with the experiment establishes the universal properties of the excited spectator systems produced during the dynamical stage of the reaction. It is furthermore confirmed that a significant reduction of the symmetry-energy term at the freeze-out stage of reduced density and high temperature is necessary to reproduce the experimental isotope distributions. A trend of decreasing symmetry energy for large neutron-rich fragments of low excitation energy is interpreted as a nuclear-structure effect.

  10. MCNP6 Study of Fragmentation Products from 112Sn + 112Sn and 124Sn + 124Sn at 1 GeV/nucleon

    CERN Document Server

    Mashnik, Stepan G

    2013-01-01

    Isotope production cross sections from 112Sn + 112Sn and 124Sn + 124Sn reactions at 1 GeV/nucleon, which were measured recently at GSI using the heavy-ion accelerator SIS18 and the Fragment Separator (FRS), have been analyzed with the latest Los Alamos Monte-Carlo transport code MCNP6 using the LAQGSM03.03 event generator. MCNP6 reproduces reasonably well all the measured cross sections. Comparison of the MCNP6 results with the measured data and with calculations by a modification of the Los Alamos version of the Quark-Gluon String Model allowing for multifragmentation processes in the framework of the Statistical Multifragmentation Model (SMM) by Botvina and coauthors, as realized in the code LAQGSM03.S1, does not suggest unambiguous evidence of a multifragmentation signature.

  11. Biodegradation of p-nitrophenol via 1,2,4-benzenetriol by an Arthrobacter sp.

    Energy Technology Data Exchange (ETDEWEB)

    Jain, R.K.; Spain, J.C. [Armstrong Lab., Tyndall Air Force Base, FL (United States); Dreisbach, J.H. [Univ. of Scranton, PA (United States)

    1994-08-01

    The degradation of p-nitrophenol (PNP) by Moraxella and Pseudomonas spp. involves an initial monooxygenase-catalyzed removal of the nitro group. The resultant hydroquinone is subject to ring fission catalyzed by a dioxygenase enzyme. A strain of an Arthrobacter sp. JS443, capable of degrading PNP with stoichiometric release of nitrite has been isolated. During induction of the enzymes required for growth on PNP, 1,2,4-benzenetriol was identified as an intermediate by gas chromatography-mass spectroscopy and radiotracer studies. 1,2,4-Benzenetriol was converted to maleylacetic acid, which was further degraded by the beta-ketoadipate pathway. Conversion of PNP to 1,2,4-benzenetriol is catalyzed by a monooxygenase system in strain JS443 through the formation of 4-nitrocatechol, 4-nitroresorcinol, or both. Results clearly indicate the existence of an alternative pathway for the biodegradation of PNP. 15 refs, 2 figs., 2 tabs.

  12. MicroRNA-124 as a novel treatment for persistent hyperalgesia

    Directory of Open Access Journals (Sweden)

    Willemen Hanneke LDM

    2012-06-01

    Full Text Available Abstract Background Chronic pain is often associated with microglia activation in the spinal cord. We recently showed that microglial levels of the kinase G protein–coupled receptor kinase (GRK2 are reduced in models of chronic pain. We also found that mice with a cell-specific reduction of around 50% in GRK2 level in microglia/macrophages (LysM-GRK2+/− mice develop prolonged inflammatory hyperalgesia concomitantly with ongoing spinal microglia/macrophage activation. The microRNA miR-124 is thought to keep microglia/macrophages in brain and spinal cord in a quiescent state. In the present study, we investigated the contribution of miR-124 to regulation of hyperalgesia and microglia/macrophage activation in GRK2-deficient mice. In addition, we investigated the effect of miR-124 on chronic inflammatory and neuropathic pain in wild-type (WT mice. Methods Hyperalgesia was induced by intraplantar IL-1β in WT and LysM-GRK2+/− mice. We determined spinal cord microglia/macrophage miR-124 expression and levels of pro-inflammatory M1 and anti-inflammatory M2 activation markers. The effect of intrathecal miR-124 treatment on IL-1β-induced hyperalgesia and spinal M1/M2 phenotype, and on carrageenan-induced and spared nerve injury-induced chronic hyperalgesia in WT mice was analyzed. Results Transition from acute to persistent hyperalgesia in LysM-GRK2+/− mice is associated with reduced spinal cord microglia miR-124 levels. In our LysM-GRK2+/− mice, there was a switch towards a pro-inflammatory M1 phenotype together with increased pro-inflammatory cytokine production. Intrathecal administration of miR-124 completely prevented the transition to persistent pain in response to IL-1β in LysM-GRK2+/− mice. The miR-124 treatment also normalized expression of spinal M1/M2 markers of LysM-GRK2+/− mice. Moreover, intrathecal miR-124 treatment reversed the persistent hyperalgesia induced by carrageenan in WT mice and prevented development of

  13. PET quantitation and imaging of the non-pure positron-emitting iodine isotope 124I.

    Science.gov (United States)

    Herzog, H; Tellman, L; Qaim, S M; Spellerberg, S; Schmid, A; Coenen, H H

    2002-05-01

    A series of PET studies using phantoms is presented to characterize the imaging and quantitative performance of the positron-emitting iodine isotope 124I. Measurements were performed on the 2D-PET scanner GE 4096+ as well as on the Siemens PET scanner HRR+ operated in both 2D and 3D modes. No specific correction was applied for the gamma-rays emitted together with the positrons. As compared to 18F, in studies with 124I there is a small loss of image resolution and contrast, and an increase in background. The quantitative results varied between different scanners and various acquisition as well as reconstruction modes, with an average relative difference of -6 +/- 13% (mean+/-SD) in respect of the phantom radioactivity as measured with gamma-ray spectroscopy. We conclude that quantitation of a radiopharmaceutical labelled with 124I is feasible and may be improved by the development of specific corrections.

  14. Pressure-induced luminescence of cerium-doped gadolinium gallium garnet crystal

    Science.gov (United States)

    Kaminska, A.; Duzynska, A.; Berkowski, M.; Trushkin, S.; Suchocki, A.

    2012-04-01

    Studies of the spectroscopic properties of Ce3+ dopant in bulk Gd3Ga5O12:Ce crystal under pressure are presented. In spite of strong intershell 4f→5d absorption bands at ambient pressure, the cerium luminescence in Gd3Ga5O12 is entirely quenched even at low temperature. It has been shown that applying pressure allows for recovery of the 5d→4f radiative transitions. Further increase of pressure improves the emission efficiency. This effect is analyzed in terms of two possible phenomena: (i) by pressure-induced electronic crossover of the excited 5d energy level of the Ce3+ with the conduction band bottom of the host crystal, and (ii) by decrease of electron-lattice coupling with increasing pressure, resulting in reduction of the Stokes shift and nonradiative transitions between the low vibrational levels of the 5d state and high vibrational levels of the ground 4f state. The results of high-pressure absorption and luminescence measurements point out that the ambient-pressure luminescence quenching is caused by the donor-like charge transfer processes due to the resonant location of the Ce3+ 5d electronic levels with respect to the host conduction band. In such a situation, the ionization of Ce3+ to Ce4+ occurs, accompanied by large lattice relaxation, which enables the nonradiative recombination to the Ce 4f state. The pressure-induced approach of the conduction-band bottom of the host crystal by the excited 5d energy level of the Ce3+ results in mixing between conduction band states and the 5d state, and the broadband luminescence from this mixed state is observed at pressures from 30 up to about 60 kbar. Then, for pressures exceeding 60 kbar, this luminescence is replaced by the classic Ce3+5d→4f transitions. Using a simple anticrossing model and configuration coordinate model in the appropriate pressure range, quantitative description of the system has been carried out, and the pressure-induced decrease of electron-lattice coupling has been shown.

  15. Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Nicholas, Jason Dale [Univ. of California, Berkeley, CA (United States)

    2007-01-01

    Cerium gadolinium oxide (CGO) has been identified as an acceptable solid oxide fuel cell (SOFC) electrolyte at temperatures (500-700 C) where cheap, rigid, stainless steel interconnect substrates can be used. Unfortunately, both the high sintering temperature of pure CGO, >1200 C, and the fact that constraint during sintering often results in cracked, low density ceramic films, have complicated development of metal supported CGO SOFCs. The aim of this work was to find new sintering aids for Ce0.9Gd0.1O1.95, and to evaluate whether they could be used to produce dense, constrained Ce0.9Gd0.1O1.95 films at temperatures below 1000 C. To find the optimal sintering aid, Ce0.9Gd0.1O1.95 was doped with a variety of elements, of which lithium was found to be the most effective. Dilatometric studies indicated that by doping CGO with 3mol% lithium nitrate, it was possible to sinter pellets to a relative density of 98.5% at 800 C--a full one hundred degrees below the previous low temperature sintering record for CGO. Further, it was also found that a sintering aid's effectiveness could be explained in terms of its size, charge and high temperature mobility. A closer examination of lithium doped Ce0.9Gd0.1O1.95 indicated that lithium affects sintering by producing a Li2O-Gd2O3-CeO2 liquid at the CGO grain boundaries. Due to this liquid phase sintering, it was possible to produce dense, crack-free constrained films of CGO at the record low temperature of 950 C using cheap, colloidal spray deposition processes. This is the first time dense constrained CGO films have been produced below 1000 C and could help commercialize metal supported ceria based solid oxide fuel cells.

  16. Effects of cerium on growth and physiological mechanism in plants under enhanced ultraviolet-B radiation

    Institute of Scientific and Technical Information of China (English)

    LIANG Chan-juan; HUANG Xiao-hua; TAO Wen-yi; ZHOU Qing

    2006-01-01

    Effect of cerium (Ce3+) on the growth, photosynthesis and antioxidant enzyme system in rape seedlings (Brassica juncea L.)exposed to two levels of UV-B radiation (T1: 0.15 W/m2 and T2:0.35 W/m2) was studied by hydroponics under laboratory conditions.After 5 d of UV-B treatment, the aboveground growth indices were obviously decreased by 13.2%-44.1%(T1) and 21.4%-49.3%(T2), compared to CK, and except active absorption area of roots, the belowground indices by 14.1%-35.6%(T1) and 20.3%-42.6%(T2). For Ce+UV-B treatments, the aboveground and belowground growth indices were decreased respectively by 4.1%-23.6%, 5.2%-23.3%(Ce+T1) and 10.8%-28.4%, 7.0%-27.8%(Ce+T2), lower than those of UV-B treatments. The decrease of growth indices appeared to be the result of changes of physiological processes. Two levels of UV-B radiation induced the decrease in chlorophyll content, net photosynthesis rate, transpiration rate, stomatal conductance and water use efficiency by 11.2%-25.9%(T1) and 20.9%-56.9%(T2), whereas increase in membrane permeability and activities of antioxidant enzymes including superoxide dismutase(SOD),catalase (CAT) and peroxidase (POD) by 6.9%, 22.8%, 21.5%, 9.5%(T1) and 36.6%, 122.3%, 103.5%, 208.9%(T2), respectively. The reduction of the photosynthetic parameters in Ce+UV-B treatments was lessened to 3.2%-13.8%(Ce+T1) and 4.9%-27.6%(Ce+T2),and the increase of membrane permeability and activities of antioxidant enzymes except POD in the same treatments were lessened to 2.4%, 8.4%, 6.6%(Ce+T1) and 30.1%, 116.7%, 75.4%(Ce+T2). These results indicate that the regulative effect of Ce on photosynthesis and antioxidant enzymatic function is the ecophysiological basis of alleviating the suppression of UV-B radiation on growth of seedlings. Furthermore, the protective effect of Ce on seedlings exposed to T1 level of UV-B radiation is superior to T2 level.

  17. Adsorption behavior of lead on aquatic sediments contaminated with cerium dioxide nanoparticles.

    Science.gov (United States)

    Wang, Chao; Fan, Xiulei; Wang, Peifang; Hou, Jun; Ao, Yanhui; Miao, Lingzhan

    2016-12-01

    Aquatic sediments serve as an important sink for engineered nanomaterials (ENMs), such as metal oxide nanoparticles (MeO NPs) and carbon nanotubes (CNTs). Owing to their remarkable properties, ENMs demonstrate significant potential to disturb the adsorption behavior of other contaminants in aquatic sediments, thereby altering the bioavailability and toxicity of these contaminants. Thus far, most studies have investigated the effect of CNTs on the adsorption of other contaminants on sediments. Cerium dioxide nanoparticles (CeO2 NPs), as one of the important MeO NPs, are also inevitably discharged into aquatic sediments because of their widespread use. In this study, we investigated the adsorption behavior of Pb(2+) on sediments spiked with CeO2 NPs at a weight ratio of 5.0%. The results showed that the adsorption rates at three stages occurring during adsorption clearly increase for sediments contaminated with CeO2 NPs. Moreover, the results obtained from the adsorption isotherms indicated that the Langmuir isotherm model best fits the isotherm data for both sediments and those contaminated with CeO2 NPs. After spiking the sediments with CeO2 NPs, the theoretical maximum monolayer adsorption capacity (Qmax) for Pb(2+) increased from 4.433 to 4.995 mg/g and the Langmuir isotherm coefficient (KL) decreased from 8.813 to 7.730 L/g. The effects of CeO2 NPs on the surface charge and pore surface properties of sediments were also studied as these properties affect the adsorption of several chemicals in sediments. The results showed that pHzpc, SBET, Sext, and average pore size of sediments clearly decrease for sediments contaminated with CeO2 NPs. Hence, the strong adsorption capacity of CeO2 NPs and the changes of sediment surface charge and pore surface properties caused by CeO2 NPs are important factors affecting the adsorption behavior of Pb(2+). The potential risk of Pb(2+) in aquatic environment may increase with CeO2 NPs buried in sediments.

  18. Cerium dioxide nanoparticle exposure improves microvascular dysfunction and reduces oxidative stress in spontaneously hypertensive rats

    Directory of Open Access Journals (Sweden)

    Valerie C Minarchick

    2015-11-01

    Full Text Available The elevated production of reactive oxygen species (ROS in the vascular wall is associated with cardiovascular diseases such as hypertension. This increase in oxidative stress contributes to various mechanisms of vascular dysfunction, such as decreased nitric oxide bioavailability. Therefore, anti-oxidants are being researched to decrease the high levels of ROS, which could improve the microvascular dysfunction associated with various cardiovascular diseases. From a therapeutic perspective, cerium dioxide nanoparticles (CeO2 NP hold great anti-oxidant potential, but their in vivo activity is unclear. Due to this potential anti-oxidant action, we hypothesize that injected CeO2 NP would decrease microvascular dysfunction and oxidative stress associated with hypertension. In order to simulate a therapeutic application, spontaneously hypertensive (SH and Wistar-Kyoto (WKY rats were intravenously injected with either saline or CeO2 NP (100 µg suspended in saline. Twenty-four hours post-exposure mesenteric arteriolar reactivity was assessed via intravital microscopy. Endothelium-dependent and –independent function was assessed via acetylcholine and sodium nitroprusside. Microvascular oxidative stress was analyzed using fluorescent staining in isolated mesenteric arterioles. Finally, systemic inflammation was examined using a multiplex analysis and venular leukocyte flux was counted. Endothelium-dependent dilation was significantly decreased in the SH rats (29.68 ± 3.28%, maximal response and this microvascular dysfunction was significantly improved following CeO2 NP exposure (43.76 ± 4.33%, maximal response. There was also an increase in oxidative stress in the SH rats, which was abolished following CeO2 NP treatment. These results provided evidence that CeO2 NP act as an anti-oxidant in vivo. There were also changes in the inflammatory profile in the WKY and SH rats. In WKY rats, IL-10 and TNF-α were increased following CeO2 NP treatment

  19. Cerium Anomalies in Fossil Fish Teeth Reveal Changes in Bottom Water Oxygenation

    Science.gov (United States)

    Chun, C. O.; Scher, H. D.; Delaney, M. L.

    2007-12-01

    Shale-normalized rare earths and yttrium (REY) concentrations of fossil fish teeth in deep sea sediments display prominent negative cerium (Ce) anomalies and positive yttrium (Y) anomalies. These features are ultimately inherited from seawater and strongly indicate that fossil fish teeth preserve a seawater REY signature. In seawater, Ce+3 is oxidized to Ce+4, and Ce becomes depleted relative to the other REY's as it partitions into other phases (e.g., ferromanganese oxyhydroxides). The magnitude of Ce depletion in a water mass is thus related to its oxygen content. We hypothesize that changes in the oxygenation of bottom waters may be revealed by examining downcore variability in the magnitude of the Ce anomaly of fossil fish teeth. To test this hypothesis, REY concentrations were measured on samples of cleaned fossil fish teeth recovered from the late Paleogene to early Eocene sections of Ocean Drilling Program (ODP) Sites 1262 and 1263 (lower and upper Walvis Ridge, ODP Leg 208, South Atlantic Ocean). These sites are vertically offset (early Eocene paleodepths were 3700 and 1700 meters, respectively) and have been extensively studied to characterize the oceanic response to the Paleocene/Eocene Thermal Maximum (PETM). Manganese enrichment factors (Mn EF) determined from total digestions of samples from these sites reveal abrupt changes in the oxygenation of bottom waters across the PETM interval. Mn EF's decrease to crustal values (~1) during the PETM, which reflects the reduction of Mn oxides as bottom water oxygen levels were depleted. Mn EF's begin to increase to 6-8 during the 'recovery phase' following the PETM. The Ce anomaly for these samples, Ce/Ce*, was calculated according to the geometric approach reported by Lawrence et al. (2006, Aquatic Geochemistry 12, 39-72), where Ce* represents an interpolation of the expected shale-normalized Ce concentration from near neighbors. In this notation, when Ce/Ce* = 1 no Ce anomaly is present. At upper Walvis Ridge

  20. Particulate Emissions from the Combustion of Diesel Fuel with a Fuel-Borne Nanoparticulate Cerium Catalyst

    Science.gov (United States)

    Conny, J. M.; Willis, R. D.; Weinstein, J. P.; Krantz, T.; King, C.

    2013-12-01

    To address the adverse impacts on health and climate from the use of diesel-fueled vehicles, a number of technological solutions have been developed for reducing diesel soot emissions and to improve fuel economy. One such solution is the use fuel-borne metal oxide catalysts. Of current interest are commercially-available fuel additives consisting of nanoparticulate cerium oxide (CeO2). In response to the possible use of CeO2-containing fuels in on-road vehicles in the U.S., the Environmental Protection Agency is conducting research to address the potential toxicity and environmental effects of particulate CeO2 emitted with diesel soot. In this study, emissions from a diesel-fueled electric generator were size-segregated on polished silicon wafers in a nanoparticle cascade impactor. The diesel fuel contained 10 ppm Ce by weight in the form of crystalline CeO2 nanoparticles 4 nm to 7.5 nm in size. Primary CeO2 nanoparticles were observed in the diesel emissions as well as CeO2 aggregates encompassing a broad range of sizes up to at least 200 nm. We report the characterization of individual particles from the size-resolved samples with focused ion-beam scanning electron microscopy and energy-dispersive x-ray spectroscopy. Results show a dependency between the impactor size range and CeO2 agglomeration state: in the larger size fractions of the impactor (e.g., 560 nm to 1000 nm) CeO2 nanoparticles were predominantly attached to soot particles. In the smaller size fractions of the impactor (e.g., 100 nm to 320 nm), CeO2 aggregates tended to be larger and unattached to soot. The result is important because the deposition of CeO2 nanoparticles attached to soot particles in the lung or on environmental surfaces such as plant tissue will likely present different consequences than the deposition of unagglomerated CeO2 particles. Disclaimer The U.S. Environmental Protection Agency through its Office of Research and Development funded and collaborated in the research described