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Sample records for barium lanthanum cerium

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. On the synthesis of monopentamethylcyclopentadienyl derivatives of yttrium, lanthanum, and cerium

    NARCIS (Netherlands)

    Booij, Martin; Kiers, Niklaas H.; Heeres, Hero J.; Teuben, Jan H.

    1989-01-01

    Two routes leading to monopentamethylcyclopentadienyl-yttrium, -lanthanum and -cerium complexes have been explored. Transmetallation of LnCl3(THF)x with Cp*Li (Cp* = C5Me5) proved useful only in some particular cases. Acid-base reactions of homoleptic complexes LnR3 with Cp*H generally gave Cp*2LnR

  6. 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.)

  7. Structural and luminescent studies on nanosized cerium doped strontium barium niobate

    Science.gov (United States)

    John, Nuja; Nandakumar, K.

    2017-06-01

    The nanosized cerium doped Strontium Barium Niobate ceramic powder system have been synthesized by sol-gel technique. The X-ray diffraction measurement confirmed the structure of cerium doped Strontium Barium Niobate ceramic powder system. The absorption peaks were analysed by FTIR spectroscopy. Particle morphology and size of the powder were examined using SEM and TEM. Crystal quality and structure were also examined by micro raman spectra. The transmission electron microscopy image of cerium doped Strontium Barium Niobate nano powder system consist of particles with average size of 20 nm. A band gap of the system was measured by optical absorption spectra. Photoluminescence data were recorded at room temperature. The emission peaks were detected under excitation at 305 nm wavelength. The peaks are assigned to the cerium electron transition from lowest 5d level to 2F5/2 and 2F7/2 of 4f, respectively. The decay time were also measured for cerium doped Strontium Barium Niobate powder system.

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Raj, S. Gokul [Department of Physics, C. Kandaswami Naidu College For Men (CKNC), Annanagar, Chennai-600102 (India); Mathivanan, V.; Mohan, R. [Department of Physics, Presidency College, Chennai – 600005 (India); Kumar, G. Ramesh, E-mail: rameshvandhai@gmail.com; Yathavan, S. [Department of Physics, University College of Engineering Arni, Anna University Chennai, Arni-632317 (India)

    2016-05-06

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr{sub 0.6}B{sub 0.4}Nb{sub 2}O{sub 6}) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce{sup +} 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.

  10. Separation of lanthanum, hafnium, barium and radiotracers yttrium-88 and barium-133 using crystalline zirconium phosphate and phosphonate compounds as prospective materials for a Ra-223 radioisotope generator

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, Teresia [Lynntech Inc., 7610 Eastmark Dr, College Station, TX 77840 (United States); Bestaoui, Naima, E-mail: Naima.Bestaoui@Lynntech.co [Lynntech Inc., 7610 Eastmark Dr, College Station, TX 77840 (United States); Wierzbicki, Melissa; Adams, Todd; Clearfield, Abraham [Lynntech Inc., 7610 Eastmark Dr, College Station, TX 77840 (United States)

    2011-07-15

    Crystalline hybrid organic/inorganic ion exchangers based on zirconium phosphate and phosphonate compounds were evaluated for application in radium-223 generator for radiopharmaceutical applications. Various compositions were synthesized and the selectivity of these materials was determined for inactive lanthanum, hafnium and barium, and radiotracers yttrium-88 and barium-133. The hybrid materials show very efficient lanthanum/barium separation; the response for zirconium phosphate was even better. A small-scale column loaded with pelletized zirconium phosphate compound demonstrated excellent retention of {sup 88}Y and release of {sup 133}Ba.

  11. [The influences of lanthanum,cerium and fluoride on the activity of glucosyltransferase(GTF) and adherence of oral cariogenic bacteria in vitro

    Science.gov (United States)

    Li, M Y; Zhang, W G; Liu, Z

    1998-09-01

    OBJECTIVE:Study of the influences of lanthanum,cerium and fluoride on the activity of flucosyltransferase(GTF) and adherence of oral cariogenic bacteria. METHODS: The influences of lanthanum,certium and fluoride on the acitivity of GTF and adherences of Steptococcus sobrinus 6715,Lactobacillus 4356 and Actinomycetes viscosus 19246 in vitro were investigated. RESULTS: Lanthanum and cerium can efficiently inhibit the acitivity of GTF than fluoride. CONCLUSION: The result was given a data that lanthanum and cerium could be used as a cariostatic agent in future.At the same time the inhibition of the bacterial adherence by these trace elements was also revealed.

  12. Chemical bonding and charge density distribution analysis of undoped and lanthanum doped barium titanate ceramics

    Indian Academy of Sciences (India)

    J MANGAIYARKKARASI; R SARAVANAN; MUKHLIS M ISMAIL

    2016-12-01

    A-site deficient, Lanthanum substituted Ba1−xLa2x/3TiO3 (x=0.000, 0.005, 0.015, 0.020 and 0.025) ceramics have been synthesized by chemical route. The effects of lanthanum dopant on the BaTiO3 lattice and the electron density distributions in the unit cell of the samples were investigated. Structural studies suggested the reduction in cell parameters and shrinkage in cell volume with the increase in lanthanum content. Chemical bonding and electron density distributions were examined through high resolution maximum entropy method (MEM). The mid bond electron density values revealed the enhancement of covalent nature between titanium and oxygen ions and predominant ionic nature between barium and oxygen ions. Average grain sizes were estimated for the undoped and doped samples. SEM investigations showed the existence of smaller grains with large voids in between them.

  13. 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.

  14. [A comparative study of lanthanum, cerium and fluoride on the prevention of root surface caries by various procedure].

    Science.gov (United States)

    Jin, H; Zhang, W; Liu, A

    1997-05-01

    In order to evaluate the anticaries effects of several trace elements by combined and respective treating procedure, studies on inhibiting demineralization and improving remineralization were carried out with lanthanum, cerium and fluoride in a pH-cycling condition. The analysis of polarized microscope and electron microprobe demonstrated that the lanthanum and fluoride to an acetate buffer solutions had less severe demineralization of root surface than individual lanthanum or fluoride to the solution. The former, furthermore, precipitated a compound membrane which may be F-La(Ce)-Ca containing crystal on the root surface, and showed a better resistibility to acid. A further discussion was made from the viewpoint of crystal physiochemistry.

  15. On-line ultrasonic characterisation of barium doped lanthanum perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Thamilmaran, P.; Arunachalam, M. [Department of Physics, Sri SRNM College, Sattur 626203, Tamil Nadu (India); Research scholars in Physics, Manonmanium Sundaranar University, Tirunelveli 627012 Tamil Nadu (India); Sankarrajan, S. [Department of Physics, Unnamalai Institute of Technology, Kovilpatti 628503, Tamil Nadu (India); Sakthipandi, K., E-mail: sakthipandi@gmail.com [Department of Physics, Sethu Institute of Technology, Kariapatti 626115, Tamil Nadu (India)

    2015-06-15

    Perovskite manganite samples La{sub 1−x}Ba{sub x}MnO{sub 3} with the composition of x=0.30, 0.33 and 0.36 were prepared by employing solid state reaction technique. The X-ray diffraction (XRD) patterns confirmed the rhombhedral structure with R3c space group of the samples. The obtained energy dispersive analysis X-rays (EDX) spectra of the samples have confirmed the elemental composition of the samples. The scanning electron microscope (SEM) images of the samples were used to find out the size of the particles. In-situ ultrasonic measurements were carried out on the samples by through transmission method. The temperature dependence of the ultrasonic parameters revealed interesting features of the samples. The observed ultrasonic velocities and attenuation both in longitudinal and shear mode are related to the paramagnetic (PM) to ferromagnetic (FM) phase transition in the prepared samples. The results confirmed that an increase in the barium content in the sample leads to an increase in the phase transition temperature T{sub C}.

  16. 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.

  17. Energy transfer and NIR emission in rare earth tri-doped barium lanthanum fluoro tellurite glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, J. Suresh; Pavani, K.; Graca, M.P.F.; Soares, M.J. [Department of Physics and I3N, University of Aveiro (Portugal); Venkataiah, G. [Department of Physics, Sri Venkateswara University, Tirupati (India); Jayasimhadri, M. [Department of Applied Physics, Delhi Technological University, Delhi (India)

    2014-09-15

    Barium lanthanum fluoro tellurite (BLFT) glasses doped with rare earth ions (ErF{sub 3}, PrF{sub 3} and YbF{sub 3}) both singly or in combinations were prepared by melt-quench technique and analysed spectroscopically. The prepared glasses were found to be mechanically strong and transparent. Optical absorption and NIR fluorescence were measured to the highly transparent and stable glass samples. Judd-Ofelt parameters and radiative properties were estimated for the single rare earth doped BLFT glasses using the optical absorption spectra. NIR fluorescence is measured using laser excitation. From the NIR emission spectra, energy transfer among the rare earth ions is analysed in the rare earth tri-doped BLFT glasses. These rare earth tri-doped BLFT glasses are found to be highly useful for the multi- wavelength emission in the NIR region for opto-electronic applications. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. 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.

  19. 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+.

  20. 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.

  1. 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.

  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. [A recent observation of clinical effects by combined application of lanthanum,cerium and fluoride-contained gel on root surface caries

    Science.gov (United States)

    Pan, Y H; Yi, N

    1999-09-01

    OBJECTIVE:The present study was to investigate the effects of combined application of lanthanum,cerium and fluoride-contained gel on root surface caries.METHODS:2000ppm lanthanum.cerium and fluoride-contained gels were used by various procedures to treat 164 teeth with root surface caries.RESULTS:The six months follow-up data revealed that combined procedure showed a better effect than each kind of trace element used alone.CONCLUSION:The study indicated that combined F/La(Ce) applying procedure has a potential value on the carious resisted root surface.

  4. [Effects of demineral-resistant of Lanthanum,Cerium and Fluoride on human root surface:A comparative study in vitro

    Science.gov (United States)

    Jin, H; Zhang, W G; Gao, H; Liu, A R

    1995-09-01

    An in vitro acid-resistant and remineralized study on human root surface with 500ppm lanthanum,Cerium and Fluoride accidulate buffer was carried out in a pH-cy-cling system.The results of quantitative chemical and energy spectrometry analyses showed that all these three elements had the demineral-resistant effects,although fluoride showed a better effect,Furthermore,the mechanisms of lanthanum,Cerium and Fluoride on demineral-resistant were discussed from the viewpoint of crystal physicochemistry.

  5. 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.

  6. X-Band Microwave Reflection Properties of Samarium/Bismuth-Substituted Barium Lanthanum Titanate Ceramics

    Science.gov (United States)

    Bahel, Shalini; Pubby, Kunal; Narang, Sukhleen Bindra

    2017-01-01

    Samarium/bismuth-substituted barium lanthanum titanate ceramics with chemical composition Ba4 (La_{1 - y - z} Smy Biz )_{9.33} Ti_{18} O_{54} (y = 0.5, 0.7; z = 0.05, 0.10, 0.15), intended as microwave reflecting materials, have been investigated in microwave X-band (8.2 GHz to 12.4 GHz) and the effect of substitution on their dielectric properties, i.e., dielectric constant and dielectric loss tangent, has been studied by vector network analyzer. Dielectric analysis showed that the dielectric constant increased with increasing samarium as well as bismuth content. Dielectric relaxation was observed for all samples in the scanned frequency range. Microwave reflection and transmission analysis of ceramic pellets of thickness 4 mm was carried out using two methods, i.e., open- and short-circuit approach, both indicating very high values of reflected power and very low values of transmitted power for all the doped materials in comparison with the base composition. The doped compositions are therefore potential microwave shielding materials for use in anechoic chambers, microwave laboratories, and radar equipment. Double-layer reflectors are also proposed, having better reflection properties (˜99% reflection) compared with single-layer reflectors.

  7. X-Band Microwave Reflection Properties of Samarium/Bismuth-Substituted Barium Lanthanum Titanate Ceramics

    Science.gov (United States)

    Bahel, Shalini; Pubby, Kunal; Narang, Sukhleen Bindra

    2017-03-01

    Samarium/bismuth-substituted barium lanthanum titanate ceramics with chemical composition Ba4 (La_{1 - y - z} Smy Biz )_{9.33} Ti_{18} O_{54} ( y = 0.5, 0.7; z = 0.05, 0.10, 0.15), intended as microwave reflecting materials, have been investigated in microwave X-band (8.2 GHz to 12.4 GHz) and the effect of substitution on their dielectric properties, i.e., dielectric constant and dielectric loss tangent, has been studied by vector network analyzer. Dielectric analysis showed that the dielectric constant increased with increasing samarium as well as bismuth content. Dielectric relaxation was observed for all samples in the scanned frequency range. Microwave reflection and transmission analysis of ceramic pellets of thickness 4 mm was carried out using two methods, i.e., open- and short-circuit approach, both indicating very high values of reflected power and very low values of transmitted power for all the doped materials in comparison with the base composition. The doped compositions are therefore potential microwave shielding materials for use in anechoic chambers, microwave laboratories, and radar equipment. Double-layer reflectors are also proposed, having better reflection properties (˜99% reflection) compared with single-layer reflectors.

  8. [A SEM observation of acid-resistant effect of lanthanum and cerium contained gel on dental root surface

    Science.gov (United States)

    Gu, Y H; Zhang, B

    1999-06-01

    OBJECTIVE:The present study was to investigate the acid-resistant effect of lanthanum,cerium contained gel.METHODS:30 of enamel-cementum slabs were treated individually with 2000ppm lanthanum,cerium and fluoride-contained gel in a pH-cycle condition for 5 days and etched with acetic buffer gel for 24 hours.RESULTS:There were spherical grains coating layers on the surface of enamel or cementum surfaces treated with F/La and F/Ce groups.24-hour successive etching made the grains disappeared,and still showed the sound surfaces.However,there were obvious etching feature in control group,which showed the enlarged Tome's process pits as well as the dissolved crystals.CONCLUSION:Combined treatment procedure of 2000ppm F and La(Ce)-gel showed the strong acid-resistant ability,which suggested that La(Ce)-Ca-F compounds play an important role,and established the foundation the oretically and experimentally for the clinical application.

  9. Preparation and Characterization on Nano-Sized Barium Titanate Powder Doped with Lanthanum by Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The nano-sized BaTiO3:La3+ powders were prepared by sol-gel process using butyl phthalate, barium acetate and lanthanum oxide as raw material, and these samples were tested by means of TG-DTA, XRD and SEM. The results indicate that with the annealing temperature and the doped concentration rising, the powders' particle sizes will increase and decrease respectively. When annealing temperature is 900 ℃ and doped concentration is 7%, the phase is cubic without other phases, and the particle size of power is 43.34 nm.

  10. 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.

  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. Photoluminescence properties of cerium oxide nanoparticles as a function of lanthanum content

    Energy Technology Data Exchange (ETDEWEB)

    Deus, R.C. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Cortés, J.A., E-mail: leandrosrr89@gmail.com [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Ramirez, M.A. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Ponce, M.A. [Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA) (CONICET-Universidad Nacional de Mar del Plata), Juan B. Justo 4302, 7600 Mar del Plata (Argentina); Andres, J. [Laboratório Interdisciplinar em Cerâmica, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, São Paulo (Brazil); Rocha, L.S.R. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); and others

    2015-10-15

    Highlights: • CeO{sub 2} nanoparticles were obtained by microwave-hydrothermal method. • Rietveld refinement reveals a cubic structure. • KOH mineralizer agent exhibit weak agglomeration at low temperature and shorter time. - Abstract: The structural and photoluminescent properties at room temperature of CeO{sub 2} and La-doped CeO{sub 2} particles were undertaken. The obtained particles were synthesized by a microwave-assisted hydrothermal method (MAH) under different lanthanum contents. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), Ultra-violet spectroscopy (UV–vis) and photoluminescence (PL) measurements were carried out. XRD revealed that the powders are free of secondary phases and crystallize in the cubic structure. Raman data show that increasing La doping content increase oxygen vacancies due to lattice expansion. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. Lanthanum addition creates oxygen vacancies and shifts the photoluminescence in the low energy range leading to intense PL emission.

  13. Investigation of ionic conductivity of lanthanum cerium oxide nano crystalline powder synthesized by co precipitation method

    Science.gov (United States)

    Tinwala, Hozefa; Shah, Patij; Siddhapara, Kirit; Shah, Dimple; Menghani, Jyoti

    2016-10-01

    Lanthanum (La) doped Ceria (CeO2) electrolyte has attracted considerable interest, as a candidate material for solid oxide fuel cells (SOFCs). The ionic conductivity of La doped CeO2 system (La2Ce2O7) nano-particles synthesized by the co-precipitation method has been investigated. The cubic fluorite structure was observed from the structural analysis of the material. Morphology of the sintered pellets are observed by scanning electron microscope (SEM), respectively. From the results of impedance spectroscopy from temperature range of room temperature to 400 °C, the oxide ion conductivity due to proton charge carrier was observed. Thermogravimetric analysis (TGA) was performed on the material to check stability of phase at high temperature.

  14. Effect of temperature on the crystallite size of Lanthanum Cerium Oxide (La2Ce2O7 and its optical properties

    Directory of Open Access Journals (Sweden)

    Hozefa Tinwala

    2013-03-01

    Full Text Available The effect of the calcination process on the crystallite size and optical properties of Lanthanum Cerium Oxide (La2Ce2O7 nanopowders synthesized using co-precipitation process were reported. X-ray diffraction analysis revealed that the synthesized nanopowders calcined at various temperatures have cubic fluorite phase. Thermal Gravimetric Analysis (TGA, X-ray Diffraction (XRD, Energy Dispersive Spectroscopy (EDS, Transmission Electron Microscopy (TEM, Laser Raman Spectroscopy, and UVvisible spectroscopy were utilized to characterize phase structure and morphology of the products.

  15. 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.

  16. 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.

  17. Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS

    Directory of Open Access Journals (Sweden)

    Yan Li

    2016-03-01

    Full Text Available Rare earth elements (REEs have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs (89Y, 139La, 140Ce, 141Pr, 146Nd, 147Sm, 153Eu, 157Gd, 159Tb, 163Dy, 165Ho, 166Er, 169Tm, 172Yb and 175Lu in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001–1.000 μg∙L−1 with r2 > 0.997. The limits of detection and quantification for this method were in the range of 0.009–0.010 μg∙L−1 and 0.029–0.037 μg∙L−1, the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg∙L−1, Ce (1.492 ± 0.995 μg∙L−1, Nd (0.014 ± 0.009 μg∙L−1 and Gd (0.023 ± 0.010 μg∙L−1 among the exposed workers were significantly higher (p < 0.05 than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and the control subjects show a

  18. Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS.

    Science.gov (United States)

    Li, Yan; Yu, Hua; Zheng, Siqian; Miao, Yang; Yin, Shi; Li, Peng; Bian, Ying

    2016-03-22

    Rare earth elements (REEs) have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs ((89)Y, (139)La, (140)Ce, (141)Pr, (146)Nd, (147)Sm, (153)Eu, (157)Gd, (159)Tb, (163)Dy, (165)Ho, (166)Er, (169)Tm, (172)Yb and (175)Lu) in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001-1.000 μg ∙ L(-1) with r² > 0.997. The limits of detection and quantification for this method were in the range of 0.009-0.010 μg ∙ L(-1) and 0.029-0.037 μg ∙ L(-1), the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg ∙ L(-1)), Ce (1.492 ± 0.995 μg ∙ L(-1)), Nd (0.014 ± 0.009 μg ∙ L(-1)) and Gd (0.023 ± 0.010 μg ∙ L(-1)) among the exposed workers were significantly higher (p < 0.05) than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and

  19. Lanthanum-cerium-silicon system

    Energy Technology Data Exchange (ETDEWEB)

    Bulanova, M.V.; Zheltov, P.N.; Meleshevich, K.A

    2002-12-16

    By the methods of differential thermal analysis, metallography and X-ray examination of 17 as-cast alloys with a composition ratio La:Ce=1:1 (at.%) the phase equilibria in the La-Ce-Si system were studied. The results are presented by means of liquidus and solidus projections and a vertical section. As expected, no ternary compounds form in this system, while all isostructural binary-based La-Si and Ce-Si phases form continuous solid solutions. Similar to the La-Si and Ce-Si systems two disilicides were found: (La,Ce)Si{sub 2-a1} ({alpha}-GdSi{sub 2} structure type) and (La,Ce)Si{sub 2-a2} ({alpha}-ThSi{sub 2} structure type). The two-phase region (La,Ce)Si{sub 2-a1}+(La,Ce)Si{sub 2-a2} is very narrow. The (La,Ce)Si and (La,Ce)Si{sub 2-a1} intermetallics melt congruently. The compounds (La,Ce){sub 5}Si{sub 3}, (La,Ce){sub 3}Si{sub 2}, (La,Ce){sub 5}Si{sub 4} and (La,Ce)Si{sub 2-a2} form via peritectic reactions. The corresponding temperatures decrease from the La-Si to the Ce-Si system. Three eutectic equilibria take place in the system: L{r_reversible}{beta}-La,{gamma}-Ce>+(La,Ce){sub 5}Si{sub 3}, L{r_reversible}(La,Ce)Si+(La,Ce)Si{sub 2-a1}, L{r_reversible}(La,Ce)Si{sub 2-a2}+. All equilibria are of the monovariant type.

  20. 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+)).

  1. Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate; Aproveitamento de itrio e lantanio de um carbonato de terras raras de baixo teor em cerio, de um carbonato de itrio e de um oxido de terras itricas

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Mari Estela de

    2006-07-01

    In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

  2. 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.

  3. Review on dielectric properties of rare earth doped barium titanate

    Science.gov (United States)

    Ismail, Fatin Adila; Osman, Rozana Aina Maulat; Idris, Mohd Sobri

    2016-07-01

    Rare earth doped Barium Titanate (BaTiO3) were studied due to high permittivity, excellent electrical properties and have wide usage in various applications. This paper reviewed on the electrical properties of RE doped BaTiO3 (RE: Lanthanum (La), Erbium (Er), Samarium (Sm), Neodymium (Nd), Cerium (Ce)), processing method, phase transition occurred and solid solution range for complete study. Most of the RE doped BaTiO3 downshifted the Curie temperature (TC). Transition temperature also known as Curie temperature, TC where the ceramics had a transition from ferroelectric to a paraelectric phase. In this review, the dielectric constant of La-doped BaTiO3, Er-doped BaTiO3, Sm-doped BaTiO3, Nd-doped BaTiO3 and Ce-doped BaTiO3 had been proved to increase and the transition temperature or also known as TC also lowered down to room temperature as for all the RE doped BaTiO3 except for Er-doped BaTiO3.

  4. XPS Study on Barium Lanthanum Magnesium Niobate

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Relaxor-type ferroelectric perovskites attract a lot of attentions due to their excellent dielectric and electrostrictive properties. (Ba,La)(Mg,Nb)O3(BLMN) ceramics were synthesized from oxides by sintering in airs using a conventional mixed oxide process. Thermogravimetry-differential analyzer (TG-DTA) analysis shows that the fired temperature of the Ba(Mg1/3, Nb2/3)O3 is above 1627.2 K. From the study of X-ray diffraction (XRD) patterns, it is founded that the amount of the perovskite phase increases with the increasing amount of La2O3. Furthermore, by the X-ray photoelectron spectroscopy (XPS) analysis, it is discovered that the amount of Nb4+ is increased as La2O3 dopant increases from 0 to 0.04.

  5. Síntese e caracterização da hexaferrita de bário tipo m dopada com lantânio e sódio para utilização como absorvedor de microondas Synthesis and characterisation of lanthanum and sodium doped m type barium hexaferrite to be used as microwave absorber

    Directory of Open Access Journals (Sweden)

    R. C. Lima

    2003-03-01

    Full Text Available Hexaferrita de Bário, dopada com lantânio e sódio, foi obtida pelo processo de mistura de óxidos. A composição utilizada foi Ba0,8La0,1Na0,1Fe12O 19. Este trabalho teve como objetivo reduzir o valor da freqüência de ressonância da hexaferrita de bário tipo M de modo que a mesma possa absorver microondas na faixa de freqüência de 8 a 16 GHz. Para se investigar a fase obtida, o material foi submetido a difração de raios X. A morfologia das partículas foi verificada pela técnica de microscopia eletrônica de varredura. Suas propriedades magnéticas e de absorção de microondas foram estudadas utilizando-se o magnetômetro de amostra vibrante e guia de ondas, respectivamente.Lanthanum and sodium doped barium hexaferrite was obtained by the mixed-oxide technique. The composition was Ba0,8La0,1Na0,1Fe12O 19. The aim of this work was to reduce the resonance frequency value of barium hexaferrite in order to be used as microwave absorber material, in the 8-16 GHz frequency range. The analysis of phases was carried out by X-ray diffraction. Particle's morphology was studied by scanning electron microscopy (SEM. Magnetic and microwave absorption properties were evaluated by using a vibrating sample magnetometer and a waveguide measurement set-up.

  6. 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.

  7. 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.

  8. Destructive adsorption of carbon tetrachloride on lanthanum and cerium oxides

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Rosynek, M.P.; Lunsford, J.H.

    1999-01-01

    The destructive adsorption of CCl4 on La2O3 and CeO2 in the absence of any oxidant, such as oxygen, has been studied by X-ray photoelectron spectroscopy and insitu Raman spectroscopy as a function of the reaction temperature and the amount of CCl4 injected. La2O3 was much more reactive than CeO2, an

  9. 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.

  10. Barium titanate thick films prepared by screen printing technique

    Directory of Open Access Journals (Sweden)

    Mirjana M. Vijatović

    2010-06-01

    Full Text Available The barium titanate (BaTiO3 thick films were prepared by screen printing technique using powders obtained by soft chemical route, modified Pechini process. Three different barium titanate powders were prepared: i pure, ii doped with lanthanum and iii doped with antimony. Pastes for screen printing were prepared using previously obtained powders. The thick films were deposited onto Al2O3 substrates and fired at 850°C together with electrode material (silver/palladium in the moving belt furnace in the air atmosphere. Measurements of thickness and roughness of barium titanate thick films were performed. The electrical properties of thick films such as dielectric constant, dielectric losses, Curie temperature, hysteresis loop were reported. The influence of different factors on electrical properties values was analyzed.

  11. 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.

  12. 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.

  13. Zirconium, Barium, Lanthanum and Europium Abundances in Open Clusters

    CERN Document Server

    Jacobson, H R; 10.1088/0004-6256/145/4/107

    2013-01-01

    We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We investigate cluster mean neutron-capture abundance trends as a function of cluster age and location in the Milky Way disk and compare them to results found in other studies in the literature. We find a statistically significant trend of increasing cluster [Ba/Fe] as a function of decreasing cluster age, in agreement with recent findings for other open cluster samples, supporting the increased importance of low-mass asymptotic giant branch stars to the generation of s-process elements. However, the other s-process elements, [La/Fe] and [Zr/Fe], do not show similar dependences, in contrast to theoretical expectations and the limited observational data from other studies. Conversely, cluster [Eu/Fe] ratios show a slight ...

  14. A chemical-spectrochemical method for the determination of rare earth elements and thorium in cerium minerals

    Science.gov (United States)

    Rose, H.J.; Murata, K.J.; Carron, M.K.

    1954-01-01

    In a combined chemical-spectrochemical procedure for quantitatively determining rare earth elements in cerium minerals, cerium is determined volumetrically, a total rare earths plus thoria precipitate is separated chemically, the ceria content of the precipitate is raised to 80??0 percent by adding pure ceria, and the resulting mixture is analyzed for lanthanum, praseodymium, neodymium, samarium, gadolinium, yttrium, and thorium spectrochemically by means of the d.c. carbon arc. Spectral lines of singly ionized cerium are used as internal standard lines in the spectrochemical determination which is patterned after Fassel's procedure [1]. Results of testing the method with synthetic mixtures of rare earths and with samples of chemically analyzed cerium minerals show that the coefficient of variation for a quadruplicate determination of any element does not exceed 5??0 (excepting yttrium at concentrations less than 1 percent) and that the method is free of serious systematic error. ?? 1954.

  15. Lanthanum(III) and praseodymium(III) derivatives with dithiocarbamates derived from α-amino acids

    Science.gov (United States)

    Rai, Anita; Sengupta, Soumitra K.; Pandey, Om P.

    2006-06-01

    Lanthanum(III) and praseodymium(III) complexes with dithiocarbamates have been synthesized by the reactions of lanthanum(III) and praseodymium(III) chloride with barium dithiocarbamate and complexes of type [LnCl(L)H 2O] n have been obtained (where Ln = La(III) or Pr(III); L = barium salt of dithiocarbamate derived from glycine, L-leucine, L-valine, DL-alanine). The complexes have been characterized by elemental analysis, molar conductance, electronic absorption and fluorescence, infrared, far infrared, 1H NMR spectral studies. The presence of coordinated water molecule is inferred from thermogravimetric analysis which indicates the loss of one water molecule at 150-170 °C. The oscillator strength, Judd-Ofelt intensity parameter, stimulated emission cross-section, etc. have been obtained for different transitions of Pr 3+.

  16. Nanostructured composite materials of cerium oxide and barium cerate

    Science.gov (United States)

    Medvedev, D. A.; Pikalova, E. Yu.; Demin, A. K.; Khrustov, V. R.; Nikolaenko, I. V.; Nikonov, A. V.; Malkov, V. B.; Antonov, B. D.

    2013-02-01

    Nanosized powders with a composition of (1- x)Ce0.8Sm0.2O2-δ- xBace0.8Sm0.2O3-δ ( x = 0, 0.3, and 1) were obtained by self-ignition combustion synthesis (SICS) from the appropriate nitrates and various organic fuels (glycine, glycerol, citric acid, and a mixture of citric acid and ethylene glycol). The most finely dispersed powders formed when the concentration of the perovskite phase in the system decreased or when glycerol or citric acid-enthyleneglycol mixture was used as a fuel during SICS. A procedure for the preparation of powders and nanostructured ceramics was developed and their electric properties were studied.

  17. Encephalopathy caused by lanthanum carbonate.

    Science.gov (United States)

    Fraile, Pilar; Cacharro, Luis Maria; Garcia-Cosmes, Pedro; Rosado, Consolacion; Tabernero, Jose Matias

    2011-06-01

    Lanthanum carbonate is a nonaluminum, noncalcium phosphate-binding agent, which is widely used in patients with end-stage chronic kidney disease. Until now, no significant side-effects have been described for the clinical use of lanthanum carbonate, and there are no available clinical data regarding its tissue stores. Here we report the case of a 59-year-old patient who was admitted with confusional syndrome. The patient received 3750 mg of lanthanum carbonate daily. Examinations were carried out, and the etiology of the encephalopathy of the patient could not be singled out. The lanthanum carbonate levels in serum and cerebrospinal fluid were high, and the syndrome eased after the drug was removed. The results of our study confirm that, in our case, the lanthanum carbonate did cross the blood-brain barrier (BBB). Although lanthanum carbonate seems a safe drug with minimal absorption, this work reveals the problem derived from the increase of serum levels of lanthanum carbonate, and the possibility that it may cross the BBB. Further research is required on the possible pathologies that increase serum levels of lanthanum carbonate, as well as the risks and side-effects derived from its absorption.

  18. Barium periostitis: an intraoral complication following barium swallow.

    Science.gov (United States)

    Stanton, David C; Seeger, Douglas; Robinson, Brian T

    2007-05-01

    Barium is used with great frequency for various gastrointestinal radiographic studies. Complications arising from the use of barium are uncommon and can range from peritonitis, pneumonitis, vascular intravasation, allergic reactions, and even "barium appendicitis." We report a case of an unusual complication, periostitis, from the use of barium in a 46-year-old male.

  19. 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.

  20. Lanthanum carbonate: safety data after 10years

    OpenAIRE

    Hutchison, Alastair

    2016-01-01

    Despite 10years of post-marketing safety monitoring of the phosphatebinder lanthanum carbonate, concerns about aluminium-like accumulationand toxicity persist. Here, we present a concise overview of the safety profileof lanthanum carbonate and interim results from a 5-year observationaldatabase study (SPD405-404; ClinicalTrials.gov identifier: NCT00567723). Thepharmacokinetic paradigms of lanthanum and aluminium are different inthat lanthanum is minimally absorbed and eliminated via the hepat...

  1. Development of Doped Lanthanum Gallate Solid Electrolytes

    Institute of Scientific and Technical Information of China (English)

    蒋凯; 王海霞; 郑立庆; 杨林; 孟健; 苏锵

    2003-01-01

    Development of the doped lanthanum gallate solid electrolytes in the recent years was reviewed. The structure and oxygen ion transference mechanism were discussed. Effects of alkali earths, transition metals, and impurities on electrical conductivity of the doped lanthanum gallates were also discussed. The applications of doped lanthanum gallate were described. The current problems and corresponding strategies were explored.

  2. Preparation of porous lanthanum phosphate with templates

    Energy Technology Data Exchange (ETDEWEB)

    Onoda, Hiroaki, E-mail: onoda@kpu.ac.jp [Department of Informatics and Environmental Sciences, Faculty of Life and Environmental Sciences, Kyoto Prefectural University, 1-5, Shimogamo Nakaragi-cyo, Sakyo-ku, Kyoto 606-8522 (Japan); Ishima, Yuya [Department of Applied Chemistry, Faculty of Life Sciences, Ritsumeikan University, 1-1-1, Nojihigashi, Kusatsu, Shiga 525-8577 (Japan); Takenaka, Atsushi [Department of Materials Science, Yonago National College of Technology, 4448, Hikona-cho, Yonago, Tottori 683-8502 (Japan); Tanaka, Isao [Department of Materials Science and Engineering, Faculty of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501 (Japan)

    2009-08-05

    Malonic acid, propionic acid, glycine, n-butylamine, and urea were added to the preparation of lanthanum phosphate from lanthanum nitrate and phosphoric acid solutions. All additives were taken into lanthanum phosphate particles. The additives that have a basic site were easy to contain in precipitates. The addition of templates improved the specific surface area of lanthanum phosphate. The amount of pore, with radius smaller than 4 nm, increased with the addition of templates. The remained additives had influence on the acidic properties of lanthanum phosphate.

  3. 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.

  4. Controlling barium sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Greenley, R.

    Even though for several years success has been realized in controlling barium sulfate scale deposition in relatively shallow, low pressure oil wells--by squeezing an organic phosphonate scale inhibitor into the producing zone--barium sulfate scale depositon in deep, high pressure/high temperature wells usually meant an expensive workover operation. A case history of a deep (16,000 ft) well in St. Mary Parish, Louisiana, and the scale inhibitor squeeze operation are described. Based on the successful results obtained in treating this well, a generalized treating procedure for combating downhole scale deposition in high pressure/high temperature gas wells is presented. Formation squeezing with such an inhibitor represents a significant breakthrough for the oil and gas industry.

  5. Measurement of the electron affinity of lanthanum

    Energy Technology Data Exchange (ETDEWEB)

    Covington, A.M.; Calabrese, D.; Thompson, J.S. [Department of Physics and Chemical Physics Programme, University of Nevada, Reno, NV 89557-0058 (United States); Kvale, T.J. [Department of Physics and Astronomy, University of Toledo, OH 43606-3390 (United States)

    1998-10-28

    The electron affinity of lanthanum has been measured using laser photoelectron energy spectroscopy. This is the first electron affinity measurement for lanthanum and one of the first measurements of an electron affinity of a rare-earth series element. The electron affinity of lanthanum was measured to be 0.47{+-}0.02 eV. At least one bound excited state of La{sup -} was also observed in the photoelectron spectra, and the binding energy relative to the ground state of lanthanum was measured as 0.17{+-}0.02 eV. The present experimental measurements are compared to a recent calculation. (author). Letter-to-the-editor.

  6. Study on Surface and Bulk Properties of Ce-5 % Lanthanum Alloy

    Institute of Scientific and Technical Information of China (English)

    Luo Lizhu; Wang Xiaolin; Fu Xiaoguo; Zhang Yanzhi; Zhao Zhengping; Liu Chunrong

    2004-01-01

    The surface and bulk properties of Ce-5% La were studied with X-ray photoelectron spectroscopy (XPS)and X-ray diffraction (XRD), respectively.The XRD analysis shows that cerium in bulk is in γ-phase, and its lattice parameter is 0.516 nm.And we also find Ce2O3 in the bulk from the XRD figure but no existence of metal lanthanum because of its small quantity.The XPS analysis shows that there are always oxides existing in the surface.The O1s peak always exists at the binding energy of 530.3 eV, which may be attributed to Ce2O3 and La2O3, but no evidence was found for the existence of CeO2.It is concluded that there is a thick layer of Ce2O3 on the sample surface.And the Ce3d peak show multi-split in the figure, in which there are two peaks in each region, 3d5/2 and 3d3/2, and the binding energy of these peaks are 882.86, 887.70 eV for 3d5/2, and 901.44, 905.93 eV for 3d3/2.The special phenomena can be attributed to the changes of 4f electronic configuration, and the cerium in the sample exhibits properties similar to Ce2O3.But the influence of the addition of lanthanum to cerium is not visible, and further investigations are expected.

  7. 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.

  8. On barium oxide solubility in barium-containing chloride melts

    Energy Technology Data Exchange (ETDEWEB)

    Nikolaeva, Elena V.; Zakiryanova, Irina D.; Bovet, Andrey L.; Korzun, Iraida V. [Ural Federal Univ., Yekaterinburg (Russian Federation). Inst. of High Temperature Electrochemistry

    2016-11-01

    Oxide solubility in chloride melts depends on temperature and composition of molten solvent. The solubility of barium oxide in the solvents with barium chloride content is essentially higher than that in molten alkali chlorides. Spectral data demonstrate the existence of oxychloride ionic groupings in such melts. This work presents the results of the BaO solubility in two molten BaCl{sub 2}-NaCl systems with different barium chloride content. The received data together with earlier published results revealed the main regularities of BaO solubility in molten BaO-BaCl{sub 2}-MCl systems.

  9. Photoluminescence of cerium fluoride and cerium-doped lanthanum fluoride nanoparticles and investigation of energy transfer to photosensitizer molecules.

    Science.gov (United States)

    Cooper, Daniel R; Kudinov, Konstantin; Tyagi, Pooja; Hill, Colin K; Bradforth, Stephen E; Nadeau, Jay L

    2014-06-28

    CexLa1-xF3 nanoparticles have been proposed for use in nanoscintillator-photosensitizer systems, where excitation of nanoparticles by ionizing radiation would result in energy transfer to photosensitizer molecules, effectively combining the effects of radiotherapy and photodynamic therapy. Thus far, there have been few experimental investigations of such systems. This study reports novel synthesis methods for water-dispersible Ce0.1La0.9F3/LaF3 and CeF3/LaF3 core/shell nanoparticles and an investigation of energy transfer to photosensitizers. Unbound deuteroporphyrin IX 2,4-disulfonic acid was found to substantially quench the luminescence of large (>10 nm diameter) aminocaproic acid-stabilized nanoparticles at reasonable concentrations and loading amounts: up to 80% quenching at 6% w/w photosensitizer loading. Energy transfer was found to occur primarily through a cascade, with excitation of "regular" site Ce(3+) at 252 nm relayed to photosensitizer molecules at the nanoparticle surface through intermediate "perturbed" Ce(3+) sites. Smaller (<5 nm) citrate-stabilized nanoparticles were coated with the bisphosphonate alendronate, allowing covalent conjugation to chlorin e6 and resulting in static quenching of the nanoparticle luminescence: ∼50% at ∼0.44% w/w. These results provide insight into energy transfer mechanisms that may prove valuable for optimizing similar systems.

  10. Doped barium titanate nanoparticles

    Indian Academy of Sciences (India)

    T K Kundu; A Jana; P Barik

    2008-06-01

    We have synthesized nickel (Ni) and iron (Fe) ion doped BaTiO3 nanoparticles through a chemical route using polyvinyl alcohol (PVA). The concentration of dopant varies from 0 to 2 mole% in the specimens. The results from X-ray diffractograms and transmission electron micrographs show that the particle diameters in the specimen lie in the range 24–40 nm. It is seen that the dielectric permittivity in doped specimens is enhanced by an order of magnitude compared to undoped barium titanate ceramics. The dielectric permittivity shows maxima at 0.3 mole% doping of Fe ion and 0.6 mole% of Ni ion. The unusual dielectric behaviour of the specimens is explained in terms of the change in crystalline structure of the specimens.

  11. Effect of lanthanum doping on electrical and electromechanical properties of Ba1–LaTiO3

    Indian Academy of Sciences (India)

    M Aparna; T Bhimasankaram; S V Suryanarayana; G Prasad; G S Kumar

    2001-10-01

    The effect of lanthanum doping is studied on ferroelectric properties of Ba1–LaTiO3 with = 0.0005, 0.001, 0.003 prepared through solid state sintering route. Dielectric and impedance spectroscopic studies have been carried out. The tetragonal distortion of the unit cell decreased and ferroelectric transition temperature, c increased with the increase of lanthanum content. Combined impedance and admittance spectroscopy was used to analyse impedance data. The electromechanical parameters were calculated from the resonant and anti-resonant frequencies from vector admittance plots. The electromechanical coefficients for Ba1–LaTiO3 with = 0.003 were found to be much larger than that of pure barium titanate.

  12. 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.

  13. Compact lanthanum hexaboride hollow cathode.

    Science.gov (United States)

    Goebel, Dan M; Watkins, Ronald M

    2010-08-01

    A compact lanthanum hexaboride hollow cathode has been developed for space applications where size and mass are important and research and industrial applications where access for implementation might be limited. The cathode design features a refractory metal cathode tube that is easily manufactured, mechanically captured orifice and end plates to eliminate expensive e-beam welding, graphite sleeves to provide a diffusion boundary to protect the LaB6 insert from chemical reactions with the refractory metal tube, and several heater designs to provide long life. The compact LaB(6) hollow cathode assembly including emitter, support tube, heater, and keeper electrode is less than 2 cm in diameter and has been fabricated in lengths of 6-15 cm for different applications. The cathode has been operated continuously at discharge currents of 5-60 A in xenon. Slightly larger diameter versions of this design have operated at up to 100 A of discharge current.

  14. 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

  15. Lanthanum

    Science.gov (United States)

    ... Achromycin V, in Pylera); a cholesterol-lowering medication (statins) such as atorvastatin (Lipitor) or rosuvastatin (Crestor); a ... to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/ ...

  16. Formulation and method for preparing gels comprising hydrous cerium oxide

    Science.gov (United States)

    Collins, Jack L; Chi, Anthony

    2013-05-07

    Formulations useful for preparing hydrous cerium oxide gels contain a metal salt including cerium, an organic base, and a complexing agent. Methods for preparing gels containing hydrous cerium oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including cerium, an organic base, and a complexing agent.

  17. A cerium(IV)-carbon multiple bond

    Energy Technology Data Exchange (ETDEWEB)

    Gregson, Matthew; Lu, Erli; McMaster, Jonathan; Lewis, William; Blake, Alexander J.; Liddle, Stephen T. [Nottingham Univ. (United Kingdom). School of Chemistry

    2013-12-02

    Straightforward access to a cerium(IV)-carbene complex was provided by one-electron oxidation of an anionic ''ate'' cerium(III)-carbene precursor, thereby avoiding decomposition reactions that plague oxidations of neutral cerium(III) compounds. The cerium(IV)-carbene complex is the first lanthanide(IV)-element multiple bond and involves a twofold bonding interaction of two electron pairs between cerium and carbon. [German] Auf direktem Wege zu einem Cer(IV)-Carbenkomplex gelangt man durch die Einelektronenoxidation einer anionischen Carben-Cerat(III)-Vorstufe. So werden Zersetzungsprozesse vermieden, die die Oxidation neutraler Cer(III)-Verbindungen erschweren. Der Cer(IV)-Carbenkomplex enthaelt die erste Lanthanoid(IV)-Element-Mehrfachbindung; dabei binden Cer und Kohlenstoff ueber zwei Elektronenpaare.

  18. Mechanochemical Reaction of Lanthanum Carbonate with Sodium Hydroxide and Preparation of Lanthanum Oxide Nanoparticle

    Institute of Scientific and Technical Information of China (English)

    李永绣; 周雪珍; 王志强

    2002-01-01

    The preparation of nano sized La2O3 powder by mechanochemical reaction of lanthanum carbonate with sodium hydroxide and subsequent heat treatment was studied using X-ray diffraction, differential thermal and thermo gravimetric analysis and transmission electron microscopy. It was found that the mechanochemical reaction process can be divided into two steps: the first step is the multi-phases mechanochemical reaction of lanthanum carbonate with NaOH to form amorphous lanthanum basic carbonate and lanthanum hydroxide, and the second step is the crystallization of basic lanthanum carbonate with the formula of La2(OH)2(CO3)2*H2O under a quasi-hydrothermal synthesis condition caused by the mechanical ball-milling. The synthesized La2O3 powder appears clearly separated spherical-like monodisperse nano-size particles in which particle size ranges from 30 to 50 nm.

  19. 75 FR 33824 - Barium Chloride From China

    Science.gov (United States)

    2010-06-15

    ... COMMISSION Barium Chloride From China Determination On the basis of the record\\1\\ developed in the subject... order on barium chloride from China would be likely to lead to continuation or recurrence of material... Barium Chloride from China: Investigation No. 731-TA-149 (Third Review). By order of the...

  20. Lanthanum carbonate: safety data after 10 years

    OpenAIRE

    Hutchison, Alastair J.; Wilson, Rosamund J.; Garafola, Svetlana; Copley, John Brian

    2016-01-01

    Abstract Despite 10 years of post‐marketing safety monitoring of the phosphate binder lanthanum carbonate, concerns about aluminium‐like accumulation and toxicity persist. Here, we present a concise overview of the safety profile of lanthanum carbonate and interim results from a 5‐year observational database study (SPD405‐404; ClinicalTrials.gov identifier: NCT00567723). The pharmacokinetic paradigms of lanthanum and aluminium are different in that lanthanum is minimally absorbed and eliminat...

  1. MR Colonography with fecal tagging: Barium vs. barium ferumoxsil

    DEFF Research Database (Denmark)

    Achiam, M.P.; Chabanova, E.; Logager, V.B.

    2008-01-01

    qualitatively (with the standard method using contrast-to-wall ratio) and subjectively (using a visual analog scale [VAS]) by three different blinded observers. Results. Evaluated both qualitatively and subjectively, the tagging efficiency of barium sulfate/ferumoxsil was significantly better (P

  2. Effects of lanthanum and cerium on low temperature plasma nitrocarburizing of nanocrystallized 3J33 steel

    Institute of Scientific and Technical Information of China (English)

    WU Yeqiong; YAN Mufu

    2011-01-01

    Plasma nitrocarburizing of nanocrystallized (NC) 3J33 steel were carried out at 400 and 430 ℃ for 4 h in a mixed gas of N2:3H2and different flow rates of rare earths (RE) La and Ce reagents in this paper. Effects of temperature, rare earth addition and its addition amount on the microstructure and hardness of the nitrocarburized layer of NC 3J33 steel were also investigated. Surface phase composition of the nitrocarburized samples was analyzed by X-ray diffraction. Metallurgical structure, La and Ce concentration and microhardness profiles of cross-sectional nitrocarburized samples were studied using an optical microscope, a scanning electron microscope equipped with an energy dispersive X-ray analyzer and Vickers microhardness tester, respectively. The results showed that the surfaces of the nitrocarburized samples were mainly composed ofγ'-Fe4N and α'-Fe (α-Fe dissolved with N and C) when the NC 3J33 steel was nitrocarburized at 400 ℃. As the temperature was enhanced up to 430 ℃, the surfaces consisted of γ'-Fe4N, α'-Fe and low nitrogen compound FeNx (x=0.0324-0.0989), and simple substance La was presented when RE flow rate was 0.1 L/min. The addition of La and Ce into nitrocarburized gas increased the thickness and hardness of the nitrocarburized layers. The samples nitrocarburized at 400 ℃ with RE flow rate of 0.025 L/min and 430 ℃ of 0.05 L/min possessed the thickest nitrocarburized layer, highest proportion of nitrides and hardness profile. RE elements could diffuse into the nitrocarburized layer and their concentration increased with temperature. The excess RE impeded the permeation of N, C elements and led to thinner compound layer as well as the diffusion layer.

  3. Cerium and Lanthanum Modified Pd/Al2O3 Catalysts for Methanol Decomposition

    Institute of Scientific and Technical Information of China (English)

    杨成; 任杰; 孙予罕

    2001-01-01

    CeO2 improves the activity and selectivity of Pd/Al2O3 catalyst for methanol decomposition. The interaction between Pd and CeO2 was then proposed to result in the promoting effect. The selectivity of CO and H2 is significantly improved by addition of La2O3 to either Pd/Al2O3 or Pd/CeO2/Al2O3 catalysts. Moreover, a synergistic promotion between CeO2 and La2O3 on γ-Al2O3 supported Pd catalysts was observed for the catalytic activity towards methanol decomposition into CO and H2.

  4. Cerium and lanthanum-modified, magnetically separable nano-catalysts for water treatment

    Science.gov (United States)

    Currently, people are exposed to many chemicals in the environment by a variety of chemicals used and produced for anthropogenic activities. Many studies reportadverse effects of chemicals in the environment on the health of humans and animals; such as endocrine disruption, femin...

  5. Fabrication of lanthanum doped yttria transparent ceramics

    Institute of Scientific and Technical Information of China (English)

    HUANG YiHua; JIANG DongLiang; ZHANG JingXian; LIN QingLing

    2009-01-01

    Yttria nanocrystalline powder doped with 9% lanthanum was synthesized by co-precipitation method using ammonia for pH adjusting. After calcinations, finer particles with narrow distribution and large surface area were obtained. After dry pressing, samples were sintered at 1500℃-1700℃ for 4 h in vacuum to produce transparent polycrystalline ceramics with uniform grains. Samples with 9 mol%lanthanum were transparent in visible light after being sintered at 1500℃ for 4 h. The grain sizes increased with lanthanum doping compared with those of pure yttria transparent ceramic sintered at the same conditions. Relative density of the transparent ceramic was 99.7%. The in-line transmittance was 73% at 580 nm wavelength after milling and polishing.

  6. Sprayed lanthanum doped zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bouznit, Y., E-mail: Bouznit80@gmail.com [Laboratory of Materials Study, Jijel University, Jijel 18000 (Algeria); Beggah, Y. [Laboratory of Materials Study, Jijel University, Jijel 18000 (Algeria); Ynineb, F. [Laboratory of Thin Films and Interface, University Mentouri, Constantine 25000 (Algeria)

    2012-01-15

    Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

  7. Sprayed lanthanum doped zinc oxide thin films

    Science.gov (United States)

    Bouznit, Y.; Beggah, Y.; Ynineb, F.

    2012-01-01

    Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

  8. Fuel cells with doped lanthanum gallate electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Feng Man [Texas Univ., Austin, TX (United States). Center for Materials Science and Engineering; Goodenough, J.B. [Texas Univ., Austin, TX (United States). Center for Materials Science and Engineering; Huang Keqin [Texas Univ., Austin, TX (United States). Center for Materials Science and Engineering; Milliken, C. [Cerematec, Inc., Salt Lake City, UT (United States)

    1996-11-01

    Single cells with doped lanthanum gallate electrolyte material were constructed and tested from 600 to 800 C. Both ceria and the electrolyte material were mixed with NiO powder respectively to form composite anodes. Doped lanthanum cobaltite was used exclusively as the cathode material. While high power density from the solid oxide fuel cells at 800 C was achieved, our results clearly indicate that anode overpotential is the dominant factor in the power loss of the cells. Better anode materials and anode processing methods need to be found to fully utilize the high ionic conductivity of the doped lanthanum gallate and achieve higher power density at 800 C from solid oxide fuel cells. (orig.)

  9. 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.

  10. Structure and Growth Mechanism of Lanthanum Chromate

    Institute of Scientific and Technical Information of China (English)

    Li Shengli; Liu Weiming; Ling Ziyu; Sun Liangcheng; Ao Qing; Fu Guifu

    2005-01-01

    The unit cell of lanthanum chromate was constructed by calculating equivalent points. By means of calculation of the hole octahedrally surrounded by O2- ions, it was considered that the sintered property of lanthanum chromate and the stability of Cr-O octahedron might be promoted by mixing a little Ca2+ ions. The growth mechanism was discussed in terms of structural ledge observed by SEM, the surfaces of the structural ledges parallel to (001), (010) and (110) planes, respectively. The misfit between (110) and (001) planes is only 0.0021 on common atomic plane, and the interconnection of the structured ledge may occur during crystal growth.

  11. Image correlation using isotropic and anisotropic higher-order generation and mutually pumped phase conjugation in photorefractive barium titanate

    Science.gov (United States)

    Buranasiri, Prathan; Banerjee, Partha P.; Polejaev, Vladimir; Sun, Ching-Cherng

    2003-10-01

    Using two beam coupling geometry, high order copropagating and contrapropagating isotropic and copropagating anisotropic self-diffraction are demonstrated using photorefractive cerium doped barium titanate. At small incident angles, typically less than 0.015 radians, both codirectional isotropic self-diffraction (CODIS) and contradirectional isotropic self-diffraction (CONDIS) orders are generated simultaneously. At larger incident angles, typically approximately more than 0.2094 radians, only codirectional anisotropic-self diffraction (CODAS) orders are generated. Ongoing work on image auto/cross correlation results are also shown.

  12. 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.

  13. 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.

  14. Gastric mucosal status susceptible to lanthanum deposition in patients treated with dialysis and lanthanum carbonate.

    Science.gov (United States)

    Ban, Shinichi; Suzuki, Syunji; Kubota, Kenji; Ohshima, Susumu; Satoh, Hideaki; Imada, Hiroki; Ueda, Yoshihiko

    2017-02-01

    Lanthanum carbonate is a popular chemical which is administered for patients with end-stage kidney disease to reduce the absorption of phosphate, and lanthanum deposition in the gastroduodenal mucosa has recently been reported. The aim of this study was to assess whether any histologic changes of the gastric mucosa are related to the deposition of lanthanum. Twenty-four patients who revealed the histology of lanthanum deposition on gastroduodenal biopsy between 2011 and 2014 were included in the study, and their clinical records and gastroduodenal biopsies obtained from 2011 to 2015 were reviewed, adding the review of gastroduodenal biopsies before 2011 if possible. Analysis of the deposited materials by scanning electron microscopy-energy dispersive x-ray spectroscopy was performed for a representative gastric biopsy. All patients were diagnosed as having renal insufficiency due to chronic kidney disease and treated with dialysis for more than 5 years, with confirmation of lanthanum carbonate use for 22 patients. Of 121 gastric biopsies and 10 duodenal ones between 2011 and 2015, 86 gastric biopsies (71.1%) and 3 duodenal biopsies (30%), respectively, revealed histology consistent with lanthanum deposition, which was confirmed by scanning electron microscopy-energy dispersive x-ray spectroscopy analysis for a representative case. The deposition tended to occur in the gastric mucosa with regenerative change, intestinal metaplasia, or foveolar hyperplasia (Pcarbonate is administered for patients with chronic kidney disease treated with dialysis.

  15. Superconductivity at 52.5 K in the lanthanum-barium-copper-oxide system

    Science.gov (United States)

    Chu, C. W.; Hor, P. H.; Meng, R. L.; Gao, L.; Huang, Z. J.

    1987-01-01

    The electrical properties of the (La/0/9/Ba/0.1/)CuO/4-y/ system are examined under ambient and hydrostatic pressures. The resistance, ac magnetic susceptibility, and superconductivity onset, midpoint, and intercept temperatures are measured. It is observed that at ambient pressure the resistance decreases with temperature decreases, and the ac susceptibility shows diamagnetic shifts starting at about 32 K. Under hydrostatic pressure a superconducting transition with an onset temperature of 52.5 K is observed, and the resistance increases at lower temperatures. The data reveal that the electrical properties of the La-Ba-Cu-O system are dependent on samples and preparation conditions. Various causes for the high temperature superconductivity of the system are proposed.

  16. Synthesis, Microstructure and the Crystalline Structure of the Barium Titanate Ceramics Doped with Lanthanum

    Directory of Open Access Journals (Sweden)

    Wodecka-Duś B.

    2013-12-01

    Full Text Available W prezentowanej pracy przeprowadzono badania ceramiki BaTiO3 i Ba1-xLąxTi1-x/4O3 (BLT dla koncentracji z prze- działu 0,001< x <0,004 (0,l-0,4mol.% La. Ceramikę BLT wytworzono z mieszaniny prostych tlenków La203, TiOi i BaCOj (wszystkie o czystości 99,9+%, Aldrich Chemical Co. Proszki ceramiczne otrzymano metodą konwencjonalną w stanie stałym (metodą MOM i poddano badaniu mikrostruktury i struktury krystalicznej. Mieszaniny proszków poddano analizie termicznej. Wyniki analizy termicznej określiły optymalną temperaturę syntezy oraz procesy zachodzące podczas ogrzewania proszków. Następnie proszki formowano w dyski pod ciśnieniem 300MPa w matrycach ze stali nierdzewnej o średnicy 10 mm. Syntezę przeprowadzono w Ts =950°C t =2godz. Ostatnim krokiem technologii było bezciśnieniowe spiekanie metodą swobodnego spiekania w T = 1350^ przez / =2 godziny. Morfologię otrzymanego materiału ceramicznego obserwowano metodą skaningowej mikroskopii elektronowej. Ceramikę BLT badano również pod względem składu chemicznego metodą EDS. Analizę strukturalną przeprowadzono metodą dyfrakcji rentgenowskiej. Badania mikrostruktury i struktury krystalicznej ceramiki przeprowadzono w temperaturze pokojowej. Badania EDS potwierdziły zachowanie stechiometrii otrzymanych próbek według wzoru chemicznego. Rentgenowska analiza dyfrakcyjna potwierdziły wytworzenie pożądanej struktury krystalicznej zarówno czystej ceramiki BaTiOj jak i z domieszką Lau. Otrzymana ceramika wykazuje strukturę typu perowskitu A BO? o symetrii tetragonalnej P4 mm. Stwierdzono, że wraz ze wzrostem stężenia La3* w BaTiOj następuje zmniejszenie wielkości ziam krystalicznych, zmniejszenie średniego wymiaru krystalitów, zmniejszenie objętości komórki elementarnej oraz wzrost obliczonej rentgenowskiej gęstości.

  17. Barium aspiration and alveolarisation of barium in an infant: A case report and review of management

    Directory of Open Access Journals (Sweden)

    Alan F. Isles

    2014-05-01

    Full Text Available We describe a case of bilateral inhalation and alveolarisation of barium in an infant following a barium swallow for investigation of dusky spells associated with feeds. A bronchoscopy subsequently revealed the presence of a mid-tracheal tracheo-oesophageal cleft. We review the literature on barium aspiration, its consequences and make recommendations for management.

  18. INFLUENCE OF BARIUM OXIDE ADDITIONS ON PORTLAND CLINKER

    National Research Council Canada - National Science Library

    Zezulova, Anezka

    2016-01-01

    ... that the radiation shielding capability of cement can be improved by incorporation of barium. This work deals with the influence of barium oxide, added in the form of barium carbonate and sulphate, on the formation and properties of Portland clinker...

  19. ONE CASE REPORT OF ACUTE POISONING BY BARIUM CARBONATE

    Institute of Scientific and Technical Information of China (English)

    GE Qin-min; BIAN Fan; WANG Shu-yun; SHEN Sheng-hui

    2009-01-01

    @@ Most barium poisoning cases were caused by oral intake by mistake. Recent years, barium carbonate poisoning has been rare to be reported. Here we reported a case of acute barium carbonate toxication taken orally on purpose.

  20. Cerium anomaly at microscale in fossils.

    Science.gov (United States)

    Gueriau, Pierre; Mocuta, Cristian; Bertrand, Loïc

    2015-09-01

    Patterns in rare earth element (REE) concentrations are essential instruments to assess geochemical processes in Earth and environmental sciences. Excursions in the "cerium anomaly" are widely used to inform on past redox conditions in sediments. This proxy resources to the specificity of cerium to adopt both the +III and +IV oxidation states, while most rare earths are purely trivalent and share very similar reactivity and transport properties. In practical terms, the level of cerium anomaly is established through elemental point quantification and profiling. All these models rely on a supposed homogeneity of the cerium oxidation state within the samples. However, this has never been demonstrated, whereas the cerium concentration can significantly vary within a sample, as shown for fossils, which would vastly complicate interpretation of REE patterns. Here, we report direct micrometric mapping of Ce speciation through synchrotron X-ray absorption spectroscopy and production of local rare earth patterns in paleontological fossil tissues through X-ray fluorescence mapping. The sensitivity of the approach is demonstrated on well-preserved fishes and crustaceans from the Late Cretaceous (ca. 95 million years (Myr) old). The presence of Ce under the +IV form within the fossil tissues is attributed to slightly oxidative local conditions of burial and agrees well with the limited negative cerium anomaly observed in REE patterns. The [Ce(IV)]/[Ce(tot)] ratio appears remarkably stable at the microscale within each fossil and is similar between fossils from the locality. Speciation maps were obtained from an original combination of synchrotron microbeam X-ray fluorescence, absorption spectroscopy, and diffraction, together with light and electron microscopy. This work also highlights the need for more systematic studies of cerium geochemistry at the microscale in paleontological contexts, in particular across fossil histologies.

  1. Synthesis, characterization and electric evaluation of barium zirconate doped with trivalent lanthanides; Sintesis, caracterizacion y evaluacion electrica de circonatos de bario dopados con lantanidos trivalentes

    Energy Technology Data Exchange (ETDEWEB)

    Gerena, O. A.; Carda, J. B.; Beltran, H.; Cordoncillo, E.; Valencia, J. S.

    2014-04-01

    Barium zirconate is an oxidic material having perovskite structure that exhibits high chemical stability in both oxidizing and reducing environments, such as in the presence of water and carbon dioxide, its conductivity has led to consider it as a electrolyte for solid oxide fuel cell finding good results, with the limitation of operating at temperatures above 800 degree centigrade. Several researchers have proposed that it is possible to improve their electrical conductivity by changes in chemical composition, particularly for doping with trivalent cations that replace the zirconium in B site of perovskite. In this study, barium zirconate was synthesized by the amorphous citrate method to examine the possibility of obtaining in more favorable conditions than those made by the conventional method of synthesis (ceramic method or solid state reaction) conditions are synthesized. Barium zirconate doped with europium, gadolinium, holmium, lanthanum, neodymium and praseodymium was prepared, the present phase identified cation was verified by X-ray diffraction (XRD), the electrical properties were examined by impedance spectroscopy (IS) at temperatures between 480 and 680 degree centigrade in order to evaluate its potential use as a fuel cell electrolyte in solid oxide. The contributions of this research has focused on the synthesis method, in the production of ceramic powders of barium zirconate at temperatures lower than those required by the ceramic method, in obtaining chemical, structural, morphological and electrical information of material synthesized. The desired phase synthesis conditions set found, also, a significant increase is seen in the solid conductivity of doped lanthanum, holmium and europium zirconate of barium in relation to the material without doping. (Author)

  2. Cerium-doped barium halide scintillators for x-ray and γ-ray detections

    NARCIS (Netherlands)

    Selling, J.; Schweizer, S.; Birowosuto, M.D.; Dorenbos, P.

    2007-01-01

    Single crystals of Ce-activated BaCl2, BaBr2, and BaI2 were investigated under x-ray and γ-ray excitation. The Ce3+-related x-ray excited luminescence in BaBr2 shifts significantly to longer wavelengths upon increasing the doping level from 0.1% to 1%. In Ce-activated BaCl2 only a slight shift can b

  3. Cerium-doped barium halide scintillators for x-ray and γ-ray detections

    NARCIS (Netherlands)

    Selling, J.; Schweizer, S.; Birowosuto, M.D.; Dorenbos, P.

    2007-01-01

    Single crystals of Ce-activated BaCl2, BaBr2, and BaI2 were investigated under x-ray and γ-ray excitation. The Ce3+-related x-ray excited luminescence in BaBr2 shifts significantly to longer wavelengths upon increasing the doping level from 0.1% to 1%. In Ce-activated BaCl2 only a slight shift can

  4. Processing science of barium titanate

    Science.gov (United States)

    Aygun, Seymen Murat

    Barium titanate and barium strontium titanate thin films were deposited on base metal foils via chemical solution deposition and radio frequency magnetron sputtering. The films were processed at elevated temperatures for densification and crystallization. Two unifying research goals underpin all experiments: (1) To improve our fundamental understanding of complex oxide processing science, and (2) to translate those improvements into materials with superior structural and electrical properties. The relationships linking dielectric response, grain size, and thermal budget for sputtered barium strontium titanate were illustrated. (Ba 0.6Sr0.4)TiO3 films were sputtered on nickel foils at temperatures ranging between 100-400°C. After the top electrode deposition, the films were co-fired at 900°C for densification and crystallization. The dielectric properties were observed to improve with increasing sputter temperature reaching a permittivity of 1800, a tunability of 10:1, and a loss tangent of less than 0.015 for the sample sputtered at 400°C. The data can be understood using a brick wall model incorporating a high permittivity grain interior with low permittivity grain boundary. However, this high permittivity value was achieved at a grain size of 80 nm, which is typically associated with strong suppression of the dielectric response. These results clearly show that conventional models that parameterize permittivity with crystal diameter or film thickness alone are insufficiently sophisticated. Better models are needed that incorporate the influence of microstructure and crystal structure. This thesis next explores the ability to tune microstructure and properties of chemically solution deposited BaTiO3 thin films by modulation of heat treatment thermal profiles and firing atmosphere composition. Barium titanate films were deposited on copper foils using hybrid-chelate chemistries. An in-situ gas analysis process was developed to probe the organic removal and the

  5. 75 FR 19657 - Barium Chloride From China

    Science.gov (United States)

    2010-04-15

    ... COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION: Notice of... chloride from China. SUMMARY: The Commission hereby gives notice that it will proceed with a full review... revocation of the antidumping duty order on barium chloride from China would be likely to lead...

  6. Laser cooling and trapping of barium

    NARCIS (Netherlands)

    De, Subhadeep

    2008-01-01

    Laser cooling and trapping of heavy alkaline-earth element barium have been demonstrated for the first time ever. For any possible cycling transition in barium that could provide strong cooling forces, the excited state has a very large branching probability to metastable states. Additional lasers

  7. Laser cooling and trapping of barium

    NARCIS (Netherlands)

    De, Subhadeep

    2008-01-01

    Laser cooling and trapping of heavy alkaline-earth element barium have been demonstrated for the first time ever. For any possible cycling transition in barium that could provide strong cooling forces, the excited state has a very large branching probability to metastable states. Additional lasers a

  8. Sorption of lanthanum ions by natural clinoptilolite tuff

    Science.gov (United States)

    Dampilova, B. V.; Zonkhoeva, E. L.

    2013-08-01

    The equilibrium and kinetics of sorption of lanthanum ions on natural clinoptilolite tuff are studied. It is demonstrated that sorption of lanthanum ions from diluted solutions occurs in micropores of clinoptilolite, and from concentrated solutions in the mesoporous structure of tuff. The main capacity of zeolite tuff is found in the secondary porous structure. The sorption of lanthanum ions is limited by diffusion in tuff grains. Lanthanum ions are regularly distributed in the tuff phase and interact with the Brønsted centers of large clinoptilolite cavities.

  9. Adsorption of lanthanum to goethite in the presence of gluconate

    Energy Technology Data Exchange (ETDEWEB)

    Hull, Laurence C.; Sarah Pepper; Sue Clark

    2005-05-01

    Adsorption of Lanthanum to Goethite in the Presence of Gluconic Acid L. C. HULL,1 S. E. PEPPER2 AND S. B. CLARK2 1Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (hulllc@inel.gov) 2Washington State University, Pullman, WA (spepper@wsu.edu), (s_clark@wsu.edu) Lanthanide and trivalent-actinide elements in radioactive waste can pose risks to humans and ecological systems for many years. Organic complexing agents, from natural organic matter or the degradation of waste package components, can alter the mobility of these elements. We studied the effect of gluconic acid, as an analogue for cellulose degradation products, on the adsorption of lanthanum, representing lanthanide and trivalent-actinide elments, to goethite, representing natural iron minearals and degradation products of waste packages. Batch pH adsorption edge experiments were conducted with lanthanum alone, and with lanthanum and gluconate at a 1:1 mole ratio. Lanthanum concentrations studied were 0.1, 1, and 10 mM, covering a range from 10% to 1000% of the calculated available adsorption sites on goethite. In the absence of gluconate, lanthanum was primarily present in solution as free lanthanum ion. With gluconate present, free lanthanum concentration in solution decreased with increasing pH as step-wise deprotonation of the gluconate molecule increased the fraction lanthanum complexed with gluconate. Adsorption to the goethite surface was represented with the diffuse double-layer model. The number of adsorption sites and the intrinsic binding constants for the surface complexes were estimated from the pH adsorption edge data using the computer code FITEQL 4.0. Two surface reactions were used to fit the adsorption data in the absence of gluconate. A strong binding site with no proton release and a much higher concentration of weak binding sites with release of two protons per lanthanum adsorbed. The adsorption of lanthanum was not measurably affected by the presence of gluconate

  10. 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.

  11. Properties of lanthanum hexaboride a compilation

    CERN Document Server

    Fisher, D J

    2013-01-01

    Lanthanum hexaboride is useful because it possesses a high melting point (2210C), a low work function, one of the highest known electron emissivities, and is stable in vacuum. This volume summarises the extant data on the properties of this material, including the: bulk modulus, conductivity, crystal structure, Debye temperature, defect structure, elastic constants, electronic structure, emissivity, Fermi surface, hardness, heat capacity, magnetoresistance, reflectivity, resistivity, specific heat, surface structure, thermal conductivity, thermoelectric power, toughness and work function. The

  12. Large-area lanthanum hexaboride electron emitter

    Science.gov (United States)

    Goebel, D. M.; Hirooka, Y.; Sketchley, T. A.

    1985-09-01

    The characteristics of lanthanum-boron thermionic electron emitters are discussed, and a large-area, continuously operating cathode assembly and heater are described. Impurity production and structural problems involving the support of the LaB6 have been eliminated in the presented configuration. The performance of the cathode in a plasma discharge, where surface modification occurs by ion sputtering, is presented. Problem areas which affect lifetime and emission current capability are discussed.

  13. Fluoride removal using lanthanum incorporated chitosan beads.

    Science.gov (United States)

    Bansiwal, Amit; Thakre, Dilip; Labhshetwar, Nitin; Meshram, Siddharth; Rayalu, Sadhana

    2009-11-01

    Highly selective material based on naturally occurring biomaterial namely chitosan has been designed for the defluoridation of water. Lanthanum incorporated chitosan beads (LCB) were prepared using precipitation method. The synthesis was optimized by varying different synthesis parameters namely lanthanum loading, complexation and precipitation time, strength of ammonia solution used for precipitation, drying time, etc. Lanthanum incorporated chitosan beads were characterized using SEM, FTIR, XRD and EDX. Surface area of LCB was observed to be 2.76 m(2)g(-1). The equilibrium adsorption data fitted well to Langmuir adsorption isotherm and showing maximum fluoride adsorption capacity of 4.7 mg g(-1) with negligible lanthanum release. Kinetic study reveals that adsorption of fluoride is fast and follows pseudo-first-order kinetics. The effect of pH was also studied and the best efficiency was observed at pH 5. Presence of sulphate, nitrate and chloride marginally affected the removal efficiency, however drastic reduction in fluoride uptake was observed in the presence of carbonate and bicarbonate. Negative value of change in free energy (DeltaG degrees) and positive value of change in entropy (DeltaS degrees) suggest the adsorption of fluoride by LCB is feasible and spontaneous process. Positive value of change in enthalpy (DeltaH degrees) suggests the process of fluoride adsorption is endothermic in nature. Regeneration study reveals that 1M ammonium chloride solution appears to be the promising regeneration media showing 81.22% regeneration. The adsorption capacity of LCB was similar in fluoride-contaminated ground water collected from Dhar district of Madhya Pradesh, India, as compared to simulated water.

  14. Oxidation process of lanthanum hexaboride ceramics

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Oxidation process of lanthanum hexaboride (LaB6) ceramic powder was investigated . The LaB6 powder samples were heated continually from room temperature to 1 473 K at a heating rate of 10 K/min by differential scanning calorimetry. The oxidation tests were conducted at different exposure temperatures. The phases and morphologies of the samples before and after exposure were analyzed by XRD and SEM. It was pointed out that before 1 273 K, LaB6 has high oxidation resistant ability, which was due to that the oxide layer hinders the oxygen diffusion from outer to the surface of LaB6 grains. The oxide layer was composed of the transition phases, which were composed of La2O3 and B2O3 formed from the initial oxidation; when the oxidation temperature exceeded 1 273 K, protective layer was destroyed due to the vaporization of liquid B2O3. Based on the results of X-ray diffraction analysis, oxidation process of LaB6 ceramic powder can be described as follows: Before 1 273 K, lanthanum borate,La(BO2)3 was formed on the surface of samples, then lanthanum oxide (La2O3) and boron oxide (B2O3) were present on the surface of samples oxidized when the temperature reached to 1 473 K.

  15. 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.

  16. Nanostructured Lanthanum Halides and CeBr3 for Nuclear Radiation and Detection

    Energy Technology Data Exchange (ETDEWEB)

    Paul Guss, Sanjoy Mukhopadhyay, Ron Guise, Ding Yuan

    2010-06-09

    Scintillator materials are used to detect, and in some cases identify, gamma rays. Higher performance scintillators are expensive, hard to manufacture, fragile, and sometimes require liquid nitrogen or cooling engines. But whereas lower-quality scintillators are cheap, easy to manufacture, and more rugged, their performance is lower. At issue: can the desirable qualities of high-and low-performance scintillators be combined to achieve better performance at lower cost? Preliminary experiments show that a LaF{sub 3}:Ce oleic acid-based nanocomposite exhibits a photopeak when exposed to {sup 137}Cs source gamma-radiation. The chemical synthesis of the cerium-doped lanthanum halide nanoparticles are scalable and large quantities of material can be produced at a time, unlike typical crystal growth processes such as the Bridgeman process. Using a polymer composite (Figure 1), produced by LANL, initial measurements of the unloaded and 8% LaF{sub 3}:Ce-loaded sample have been made using {sup 137}Cs sources. Figure 2 shows an energy spectrum acquired for CeF{sub 3}. The lighter plot is the measured polymer-only spectrum and the black plot is the spectrum from the nanocomposite scintillator. As the development of this material continues, the energy resolution is expected to improve and the photopeak-to-Compton ratio will become greater at higher loadings. These measurements show the expected Compton edge in the polymer-only sample, and the Compton edge and photo-peak expected in the nanophosphor composites that LANL has produced. Using a porous VYCORR with CdSe/ZnS core shell quantum dots, Letant has demonstrated that he has obtained signatures of the 241Am photopeak with energy resolution as good at NaI (Figure 3). We begin with the fact that CeBr{sub 3} crystals do not have a self-activity component as strong as the lanthanum halides. The radioactive 0.090% {sup 138}La component of lanthanum leads to significant self-activity, which will be a problem for very large

  17. Characterization of gadolinium and lanthanum oxide films on Si (100)

    Science.gov (United States)

    Wu, X.; Landheer, D.; Sproule, G. I.; Quance, T.; Graham, M. J.; Botton, G. A.

    2002-05-01

    High-resolution transmission electron microscopy, electron energy loss spectroscopy, and Auger electron spectroscopy, were used to study gadolinium and lanthanum oxide films deposited on Si (100) substrates using electron-beam evaporation from pressed-powder targets. As-deposited films consist of a crystalline oxide layer and an amorphous interfacial layer. A complicated distinct multilayer structure consisting of oxide layers, silicate layers, and SiO2-rich layers in thick (~30 nm) annealed films has been observed for both gadolinium and lanthanum films. For thinner annealed films (~8 nm), there is no longer a crystalline oxide layer but an amorphous gadolinium or lanthanum silicate layer and an interfacial SiO2-rich layer. The formation of the lanthanum silicate by annealing lanthanum oxide is found to be thermodynamically more favorable than the formation of gadolinium silicate.

  18. Effects of lanthanum and lanthanum-modified clay on growth, survival and reproduction of Daphnia magna

    NARCIS (Netherlands)

    Lürling, M.F.L.L.W.; Tolman, Y.

    2010-01-01

    The novel lanthanum-modified clay water treatment technology (Phoslock) seems very promising in remediation of eutrophied waters. Phoslock is highly efficient in stripping dissolved phosphorous from the water column and in intercepting phosphorous released from the sediments. The active phosphorous-

  19. Radium/Barium Waste Project

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, Allen K.; Ellefson, Mark D.; McDonald, Kent M.

    2015-06-25

    The treatment, shipping, and disposal of a highly radioactive radium/barium waste stream have presented a complex set of challenges requiring several years of effort. The project illustrates the difficulty and high cost of managing even small quantities of highly radioactive Resource Conservation and Recovery Act (RCRA)-regulated waste. Pacific Northwest National Laboratory (PNNL) research activities produced a Type B quantity of radium chloride low-level mixed waste (LLMW) in a number of small vials in a facility hot cell. The resulting waste management project involved a mock-up RCRA stabilization treatment, a failed in-cell treatment, a second, alternative RCRA treatment approach, coordinated regulatory variances and authorizations, alternative transportation authorizations, additional disposal facility approvals, and a final radiological stabilization process.

  20. Magneto optical trapping of Barium

    CERN Document Server

    De, S; Jungmann, K; Willmann, L

    2008-01-01

    First laser cooling and trapping of the heavy alkaline earth element barium has been achieved based on the strong 6s$^2$ $^1$S$_0$ - 6s6p $^1$P$_1$ transition for the main cooling. Due to the large branching into metastable D-states several additional laser driven transitions are required to provide a closed cooling cycle. A total efficiency of $0.4(1) \\cdot 10^{-2}$ for slowing a thermal atomic beam and capturing atoms into a magneto optical trap was obtained. Trapping lifetimes of more than 1.5 s were observed. This lifetime is shortened at high laser intensities by photo ionization losses. The developed techniques will allow to extend significantly the number of elements that can be optically cooled and trapped.

  1. Lanthanum carbonate: safety data after 10 years.

    Science.gov (United States)

    Hutchison, Alastair J; Wilson, Rosamund J; Garafola, Svetlana; Copley, John Brian

    2016-12-01

    Despite 10 years of post-marketing safety monitoring of the phosphate binder lanthanum carbonate, concerns about aluminium-like accumulation and toxicity persist. Here, we present a concise overview of the safety profile of lanthanum carbonate and interim results from a 5-year observational database study (SPD405-404; ClinicalTrials.gov identifier: NCT00567723). The pharmacokinetic paradigms of lanthanum and aluminium are different in that lanthanum is minimally absorbed and eliminated via the hepatobiliary pathway, whereas aluminium shows appreciable absorption and is eliminated by the kidneys. Randomised prospective studies of paired bone biopsies revealed no evidence of accumulation or toxicity in patients treated with lanthanum carbonate. Patients treated with lanthanum carbonate for up to 6 years showed no clinically relevant changes in liver enzyme or bilirubin levels. Lanthanum does not cross the intact blood-brain barrier. The most common adverse effects are mild/moderate nausea, diarrhoea and flatulence. An interim Kaplan-Meier analysis of SPD405-404 data from the United States Renal Data System revealed that the median 5-year survival was 51.6 months (95% CI: 49.1, 54.2) in patients who received lanthanum carbonate (test group), 48.9 months (95% CI: 47.3, 50.5) in patients treated with other phosphate binders (concomitant therapy control group) and 40.3 months (95% CI: 38.9, 41.5) in patients before the availability of lanthanum carbonate (historical control group). Bone fracture rates were 5.9%, 6.7% and 6.4%, respectively. After more than 850 000 person-years of worldwide patient exposure, there is no evidence that lanthanum carbonate is associated with adverse safety outcomes in patients with end-stage renal disease.

  2. 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.

  3. 75 FR 20625 - Barium Chloride From China

    Science.gov (United States)

    2010-04-20

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION: Revised schedule for the subject review. DATES: Effective Date: April 9, 2010. FOR FURTHER INFORMATION CONTACT:...

  4. Neutral Barium Cloud Evolution at Different Altitudes

    Institute of Scientific and Technical Information of China (English)

    李磊; 徐荣栏

    2002-01-01

    Considering the joint effects of diffusion, collision, oxidation and photoionization, we study the evolution of the barium cloud at different altitudes in the space plasma active experiment. The results present the variation of the loss rate, number density distribution and brightness of the barium cloud over the range from 120 to 260km.This can be divided into oxidation, oxidation plus photoionization and photoionization regions.

  5. Bacterial Reduction Of Barium Sulphate By Sulphate-Reducing Bacteria

    Directory of Open Access Journals (Sweden)

    Luptáková Alena

    2015-12-01

    Full Text Available Acid mine drainage (AMD is a worldwide problem leading to contamination of water sources. AMD are characterized by low pH and high content of heavy metals and sulphates. The barium salts application presents one of the methods for the sulphates removing from AMD. Barium chloride, barium hydroxide and barium sulphide are used for the sulphates precipitation in the form of barium sulphate. Because of high investment costs of barium salts, barium sulphide is recycled from barium sulphate precipitates. It can be recycled by thermic or bacterial reduction of barium sulphate. The aim of our study was to verify experimentally the possibility of the bacterial transformation of BaSO4 to BaS by sulphate-reducing bacteria. Applied BaSO4 came from experiments of sulphates removal from Smolnik AMD using BaCl2.

  6. Effect of Lanthanum on Mycelium Growth and Some Pathogenic Factors

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Three soil-transmitted pathogenic fungi including Rhizoctonia solani, Fusarium solani, and Pythium sp. were selected to investigate the effect of lanthanum on their growth and the pathogenic enzymes using liquid culture. Variance analysis shows significant differences among treatments with different concentrations of lanthanum (Rhizoctonia solani F=6.75>F0.01=5.99; Fusarium solani F=18.1>F0.01=5.99, Pythium sp. F=23.29>F0.01=5.99). The inhibitory effect of lanthanum on pathogenic fungi increased with an increase in La concentration. The activities of the three pathogenic enzymes per gram mycelium were promoted remarkably. However, the quantity or the activities of the total enzymes were inhibited because of the strong inhibition of mycelium growth by lanthanum. Meanwhile, the effect of lanthanum on toxins of pathogenic fungi were studied using the seed germination experiment. Toxins of pathogenic fungi are influenced by lanthanum and the virulence decreases significantly with the increase of lanthanum concentration.

  7. 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.

  8. Filamentation and supercontinuum generation in lanthanum glass

    Science.gov (United States)

    Yang, Yuxia; Liao, Meisong; Li, Xia; Bi, Wanjun; Ohishi, Yasutake; Cheng, Tonglei; Fang, Yongzheng; Zhao, Guoying; Gao, Weiqing

    2017-01-01

    A broadband supercontinuum (SC) covering 400-2800 nm in a 20 dB dynamic range is reported in a piece of highly nonlinear, low-dispersion bulk lanthanum glass without employing any lens to focus the pump pulse. The spectrum width obtained in this study is broader than the maximum spectrum width obtained in silica photonic crystal fibers. The filaments and bright conical visible emission patterns of the SC are analyzed. Under optimum pump conditions, an SC conversion efficiency of 75% is obtained. The SC conversion efficiency is confirmed to be stable. Additionally, the relationship between the input peak intensity and the output beam radius is elucidated by simulating the propagation of a Gaussian beam in the bulk lanthanum glass. A 0.20 mm stable laser beam radius at the end of the propagation domain is demonstrated in a certain input peak intensity range. This small value of the beam radius indicates that most of the output power is localized over a small region because of the Kerr focusing effect despite the existence of conical emission in the SC generation by filamentation. The findings of this study are of significance for the development of ultra-broadband SC sources based on bulk glasses and high peak power lasers.

  9. Thermochemical hydrogen production via a cycle using barium and sulfur - Reaction between barium sulfide and water

    Science.gov (United States)

    Ota, K.; Conger, W. L.

    1977-01-01

    The reaction between barium sulfide and water, a reaction found in several sulfur based thermochemical cycles, was investigated kinetically at 653-866 C. Gaseous products were hydrogen and hydrogen sulfide. The rate determining step for hydrogen formation was a surface reaction between barium sulfide and water. An expression was derived for the rate of hydrogen formation.

  10. Sulphate removal from sodium sulphate-rich brine and recovery of barium as a barium salt mixture.

    Science.gov (United States)

    Vadapalli, Viswanath R K; Zvimba, John N; Mulopo, Jean; Motaung, Solly

    2013-01-01

    Sulphate removal from sodium sulphate-rich brine using barium hydroxide and recovery of the barium salts has been investigated. The sodium sulphate-rich brine treated with different dosages of barium hydroxide to precipitate barium sulphate showed sulphate removal from 13.5 g/L to less than 400 mg/L over 60 min using a barium to sulphate molar ratio of 1.1. The thermal conversion of precipitated barium sulphate to barium sulphide achieved a conversion yield of 85% using coal as both a reducing agent and an energy source. The recovery of a pure mixture of barium salts from barium sulphide, which involved dissolution of barium sulphide and reaction with ammonium hydroxide resulted in recovery of a mixture of barium carbonate (62%) and barium hydroxide (38%), which is a critical input raw material for barium salts based acid mine drainage (AMD) desalination technologies. Under alkaline conditions of this barium salt mixture recovery process, ammonia gas is given off, while hydrogen sulfide is retained in solution as bisulfide species, and this provides basis for ammonium hydroxide separation and recovery for reuse, with hydrogen sulfide also recoverable for further industrial applications such as sulfur production by subsequent stripping.

  11. 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.)

  12. Synthesis of barium mercaptides and application of antimony/barium mercaptides

    Institute of Scientific and Technical Information of China (English)

    瞿龙; 张露露; 舒万艮

    2001-01-01

    Mercaptoacetic acid, isooctyl thioglycolate and barium hydroxide used as start materials, barium bis (2-ethylhexyl thioglycolate) (Ba(2EHTG)2), barium thioglycolate (Ba(TG)) and barium bisthioglycolate (Ba(TG)2) were synthesized. Their optimum synthetic techniques were discussed, and some physicochemical data were reported. Infrared spectroscopy and elemental analysis methods were used to identify the structures. They were put into PVC plastic products together with antimony tris (2-ethylhexyl thioglycolate) (Sb(2EHTG)3) under the suitable compounding, and their heat stability to PVC was studied. It is shown that these barium mercaptides have remarkable synergisms with antimony mercaptides and the long-term stabilizing effect of organoantimony stabilizer can be effectively improved, reducing the amount of antimony compounds so as to avoid the decrease of its stabilizing effect.

  13. 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.

  14. Scintillators with potential to supersede lanthanum bromide

    Energy Technology Data Exchange (ETDEWEB)

    Cherepy, Nerine; Payne, Steven; Aszatlos, Steve; Hull, Giulia; Kuntz, J.; Niedermayr, Tom; Pimputkar, S.; Roberts, J.; Sanner, R.; Tillotson, T.; van Loef, Edger; Wilson, Cody; Shah, Kanai; Roy, U.; Hawrami, R.; Burger, Arnold; Boatner, Lynn; Choong, Woon-Seng; Moses, William

    2009-06-01

    New scintillators for high-resolution gamma ray spectroscopy have been identified, grown and characterized. Our development efforts have focused on two classes of high light yield materials: Europium-doped alkaline earth halides and Cerium-doped garnets. Of the halide single crystals we have grown by the Bridgman method - SrI{sub 2}, CaI{sub 2}, SrBr{sub 2}, BaI{sub 2} and BaBr{sub 2} - SrI{sub 2} is the most promising. SrI{sub 2}(Eu) emits into the Eu{sup 2+} band, centered at 435 nm, with a decay time of 1.2 {micro}s and a light yield of up to 115,000 photons/MeV. It offers energy resolution better than 3% FWHM at 662 keV, and exhibits excellent light yield proportionality. Transparent ceramics fabrication allows production of Gadolinium- and Terbium-based garnets which are not growable by melt techniques due to phase instabilities. While scintillation light yields of Cerium-doped ceramic garnets are high, light yield non-proportionality and slow decay components appear to limit their prospects for high energy resolution. We are developing an understanding of the mechanisms underlying energy dependent scintillation light yield non-proportionality and how it affects energy resolution. We have also identified aspects of optical design that can be optimized to enhance energy resolution.

  15. Abundance analysis of Barium stars

    Institute of Scientific and Technical Information of China (English)

    Guo-Qing Liu; Yan-Chun Liang; Li-Cai Deng

    2009-01-01

    We obtain the chemical abundances of six barium stars and two CH subgiant stars based on the high signal-to-noise ratio and high resolution Echelle spectra. The neu- tron capture process elements Y, Zr, Ba, La and Eu show obvious overabundances relative to the Sun, for example, their [Ba/Fe] values are from 0.45 to 1.27. Other elements, in- cluding Na, Mg, A1, Si, Ca, Sc, Ti, V, Cr, Mn and Ni, show comparable abundances to the Solar ones, and their [Fe/H] covers a range from -0.40 to 0.21, which means they belong to the Galactic disk. The predictions of the theoretical model of wind accretion for bi- nary systems can explain the observed abundance patterns of the neutron capture process elements in these stars, which means that their overabundant heavy-elements could be caused by accreting the ejecta of AGB stars, the progenitors of present-day white dwarf companions in binary systems.

  16. Lanthanum additions and the toughness of ultra-high strength steels and the determination of appropriate lanthanum additions

    Energy Technology Data Exchange (ETDEWEB)

    Garrison, Warren M. [Department of Metallurgical Engineering and Materials Science, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States)]. E-mail: wmg@andrew.cmu.edu; Maloney, James L. [Timken Company, 1835 Dueber Avenue S.W., Canton, OH 44706-0930 (United States)

    2005-08-25

    Studies of commercial heats of AF1410 steel suggest that under appropriate conditions additions of rare-earth elements can significantly enhance fracture toughness. This improvement in toughness is not due to an extremely low inclusion volume fraction but is apparently due to the formation of larger and more widely spaced inclusions. The purpose of this work is to discuss our experience in using rare-earth additions to laboratory scale vacuum induction melted and subsequently vacuum arc remelted heats of ultra-high strength steels to achieve inclusion distributions similar to those observed in commercial heats modified with lanthanum additions. The results indicate that lanthanum additions of 0.015 wt.% to low sulfur steels which have been well deoxidized using carbon-vacuum deoxidation can result in lanthanum rich inclusions which are similar in size, volume fraction and spacing to those obtained in commercially produced heats of ultra-high strength steel to which lanthanum has been added. The heat of steel to which lanthanum additions of 0.015 wt.% were made had significantly higher toughness than did the heat of the same steel in which the sulfur had been gettered as small and closely spaced particles of MnS and which had an inclusion volume fraction similar to that of the heat modified by the addition of 0.015 wt.% lanthanum. This improvement in toughness was attributed to an increase in inclusion spacing. An addition of 0.06 wt.% lanthanum was excessive. Such an addition of lanthanum resulted in a huge volume fraction of large cuboidal inclusions which primarily contain lanthanum and oxygen and which are extremely detrimental to toughness.

  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. Characterization and bacterial toxicity of lanthanum oxide bulk and nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Brabu Balusamy; Yamuna Gowri Kandhasamy; Anitha Senthamizhan; Gopalakrishnan Chandrasekaran; Murugan Siva Subramanian; Kumaravel Tirukalikundram S

    2012-01-01

    This study evaluated the bacterial toxicity of lanthanum oxide micron and nano sized particles using shake flask method against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli,Pseudomonas aeruginosa) bacteria.Particle size,morphology and chemical composition were determined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).Resuits indicated that lanthanum oxide nanoparticles showed antimicrobial activity against Staphylococcus aureus,but not against Escherichia coli and Pseudomonas aeruginosa.It was speculated that lanthanum oxide produced this effect by interacting with the gram-positive bacterial cell wall.Furthermore,lanthanum oxide bulk particles were found to enhance the pyocyanin pigment production in Pseudomonas aeruginosa.

  19. 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.

  20. 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)

  1. 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.

  2. Clinical pharmacokinetics of the phosphate binder lanthanum carbonate.

    Science.gov (United States)

    Damment, Stephen J P; Pennick, Michael

    2008-01-01

    Lanthanum carbonate is considered to be the most potent of a new generation of noncalcium phosphate binders used to treat hyperphosphataemia in chronic kidney disease (CKD), a condition associated with progressive bone and cardiovascular pathology and a markedly elevated risk of death. Its phosphate-binding action involves ionic binding and precipitation of insoluble complexes within the lumen of the intestine, thereby preventing absorption of dietary phosphate. While pharmacokinetics have little relevance to the efficacy of lanthanum carbonate, they are of fundamental importance when it comes to evaluating safety. When administered as lanthanum carbonate, the oral bioavailability of lanthanum is low (approximately 0.001%). The small absorbed fraction is excreted predominantly in bile, with less than 2% being eliminated by the kidneys. Predictably, therefore, plasma exposure and pharmacokinetics have been shown to be similar in healthy human volunteers and CKD stage 5 patients. With almost complete plasma protein binding, free lanthanum concentrations in patients at steady state are carbonate has a low propensity to cause systemic drug interactions due to its poor absorption. However, the higher concentrations present in the gastrointestinal tract can form chelates with some drugs, such as fluoroquinolones, and reduce their absorption. The improved understanding of the pharmacokinetics of lanthanum that has emerged in recent years has helped to explain why the myriad of calcium-like effects described in vitro for lanthanum have little if any relevance in vivo. The pharmacokinetic investigations of lanthanum carbonate formed an important part of the stringent premarketing safety assessment process and have been influential in reassuring both regulators and physicians that the agent can be used safely and effectively in this vulnerable dialysis population.

  3. Phase Stability of the Lanthanum Strontium Manganites

    Science.gov (United States)

    Zheng, Feng; Pederson, Larry

    1996-03-01

    Phase diagram and thermodynamic data of the La-Sr-Mn-O system has been studied. The ABO3 -type perovskite of this system is presently the preferred cathode material for application in solid oxide fuel cells. And the phase stability of the lanthanum strontium manganites at elevated temperature is vital to fuel cell operation. Measuring the electromotive force through solid galvanic cell (-) Air,Pt|SrF_2,SrO||CaF_2||La_1-xSr_xMnO_3,SrF_2|Pt,Air (+) and the like enable us to derive the strontium oxide activity and other thermodynamic parameters such as Gibbs free energy of reaction, etc, which help us to understand the materials in using.

  4. Coherent Dark Resonances in Atomic Barium

    CERN Document Server

    Dammalapati, U; Jungmann, K; Willmann, L

    2007-01-01

    The observation of dark-resonances in the two-electron atom barium and their influence on optical cooling is reported. In heavy alkali earth atoms, i.e. barium or radium, optical cooling can be achieved using n^1S_0-n^1P_1 transitions and optical repumping from the low lying n^1D_2 and n^3D_{1,2} states to which the atoms decay with a high branching ratio. The cooling and repumping transition have a common upper state. This leads to dark resonances and hence make optical cooling less inefficient. The experimental observations can be accurately modelled by the optical Bloch equations. Comparison with experimental results allows us to extract relevant parameters for effective laser cooling of barium.

  5. Improved spectrophotometric analysis of barium styphnate

    Energy Technology Data Exchange (ETDEWEB)

    Brown, N E; Blasi, J A

    1983-01-01

    A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413.3 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in barium styphnate and in styphnic acid. Our investigation has shown that the molar absorptivity and lambda maxima of the styphnate ion are quite pH dependent; therefore, the pH is buffered to 6.8 to 7.0 with ammonium acetate. Under these conditions the molar absorptivity is 1.6 x 10/sup 4/ L/mol-cm. Analyses following the procedure in the Navy specification WS13444A using water were found to give low molar absorptivities (1.3 x 10/sup 4/ L/mol-cm) for the styphnic acid calibration resulting in erroneous values for barium styphnate purity.

  6. Printed Barium Strontium Titanate capacitors on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Sette, Daniele [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg); Kovacova, Veronika [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Defay, Emmanuel, E-mail: emmanuel.defay@list.lu [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg)

    2015-08-31

    In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography.

  7. Electronic structure of nanograin barium titanate ceramics

    Institute of Scientific and Technical Information of China (English)

    DENG Xiangyun; WANG Xiaohui; LI Dejun; LI Longtu

    2007-01-01

    The density of states and band structure of 20 nm barium titanate(BaTiO3,BT)ceramics are investigated by first-principles calculation.The full potential linearized augmented plane wave(FLAPW)method is used and the exchange correlation effects are treated by the generalized gradient approximation(GGA).The results show that there is substantial hybridization between the Ti 3d and O 2p states in 20 nm BT ceramics and the interaction between barium and oxygen is typically ionic.

  8. Barium halide nanocrystals in fluorozirconate based glass ceramics for scintillation application

    Energy Technology Data Exchange (ETDEWEB)

    Selling, J.

    2007-07-01

    Europium (Eu)-activated barium halide nanocrystals in fluorozirconate based glass ceramics represent a promising class of Xray scintillators. The scintillation in these glass ceramics is mainly caused by the emission of divalent Eu incorporated in hexagonal BaCl{sub 2} nanocrystals which are formed in the glass matrix upon appropriate annealing. Experiments with cerium (Ce)-activated fluorozironate glass ceramics showed that Ce is an interesting alternative. In order to get a better understanding of the scintillation mechanism in Eu- or Ce-activated barium halide nanocrystals, an investigation of the processes in the corresponding bulk material is essential. The objective of this thesis is the investigation of undoped, Eu-, and Ce-doped barium halides by X-ray excited luminescence (XL), pulse height, and scintillation decay spectra. That will help to figure out which of these crystals has the most promising scintillation properties and would be the best nanoparticles for the glass ceramics. Furthermore, alternative dopants like samarium (Sm) and manganese (Mn) were also investigated. Besides the above-mentioned optical investigation electron paramagnetic resonance (EPR) and Moessbauer measurements were carried out in order to complete the picture of Eu-doped barium halides. The EPR data of Eu-doped BaI{sub 2} is anticipated to yield more information about the crystal field and crystal structure that will help to understand the charge carrier process during the scintillation process. The main focus of the Moessbauer investigations was set on the Eu-doped fluorochlorozirconate glass ceramics. The results of this investigation should help to improve the glass ceramics. The Eu{sup 2+}/Eu{sup 3+} ratio in the glass ceramics should be determined and optimize favor of the Eu{sup 2+}. We also want to distinguish between Eu{sup 2+} in the glass matrix and Eu{sup 2+} in the nanocrystals. For a better understanding of Moessbauer spectroscopy on Eu also measurements on Eu in a

  9. Room-temperature scintillation properties of cerium-doped REOX (RE=Y, La, Gd, and Lu; X=F, Cl, Br, and I)

    Energy Technology Data Exchange (ETDEWEB)

    Eagleman, Yetta; Bourret-Courchesne, Edith; Derenzo, Stephen

    2010-12-10

    The scintillation properties of cerium-doped oxyhalides following the general formula REOX (RE=Y, La, Gd, and Lu; X=F, Cl, Br, and I) are reported. These materials were synthesized under dry conditions as microcrystalline powders from conventional solid state reactions. The room temperature X-ray excited emission and scintillation decay curves were measured and analyzed for each material. Additionally, the hygroscopic nature of the oxychlorides and oxybromides was compared to that of their corresponding rare earth halides. The yttrium, lanthanum, and gadolinium oxychlorides, and all of the oxybromides and oxyiodides are found to be activated by Ce{sup 3+}. GdOBr doped with 0.5% Ce{sup 3+} has the highest light output with a relative luminosity of about one-half that of LaBr{sub 3}: Ce{sup 3+}. It displays a single exponential decay of 30 ns.

  10. 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.

  11. Preparation and Characterization of Lanthanum Carbonate Octahydrate for the Treatment of Hyperphosphatemia

    Directory of Open Access Journals (Sweden)

    Anqi He

    2013-01-01

    Full Text Available We proposed a new approach to prepare lanthanum carbonate via reactions between lanthanum chloride and NaHCO3. In the reaction, small amount of NaHCO3 solution was firstly added to the acidic lanthanum chloride solution to generate lanthanum carbonate nuclei and then NaHCO3 is added to the lanthanum chloride at a constant speed. This approach makes both precipitation reaction and neutralization reaction take place simultaneously. Consequently, lanthanum carbonate is produced at low pH environment (pH below 4.0 so that the risk of generating lanthanum carbonate hydroxide is reduced. The product of the above reaction is validated by EDTA titration, elemental analysis, and XRD characterization. In addition, we established a FTIR spectroscopic method to identify La(OHCO3 from La2(CO32·8H2O. Lanthanum carbonate exhibits considerable ability to bind phosphate.

  12. Work Function Calculation For Hafnium- Barium System

    Directory of Open Access Journals (Sweden)

    K.A. Tursunmetov

    2015-08-01

    Full Text Available The adsorption process of barium atoms on hafnium is considered. A structural model of the system is presented and on the basis of calculation of interaction between ions dipole system the dependence of the work function on the coating.

  13. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

    Torres, P.; Norby, Poul; Grivel, Jean-Claude

    2015-01-01

    The thermal decomposition of barium valerate (Ba(C4H9CO2)(2)/Ba-pentanoate) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage optical microscopy. Melting takes place in two different steps, at 200 degrees C and 280...

  14. Scattering lengths of calcium and barium isotopes

    NARCIS (Netherlands)

    Dammalapati, U.; Willmann, L.; Knoop, S.

    2011-01-01

    We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba) in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca

  15. Barium Ferrite Films Grown by Laser Ablation

    NARCIS (Netherlands)

    Lisfi, A.; Lodder, J.C.; Haan, de P.; Smithers, M.A.; Roesthuis, F.J.G.

    1998-01-01

    Pulsed laser ablation (PLA) has been used to grow barium ferrite films on Al2O3 single crystal substrates. When deposition occurs in an oxidising atmosphere at high temperatures, the films are single BaFe12O19 phase, very well oriented with (001) texture, and exhibit a large perpendicular magnetic a

  16. 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.

  17. 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(-)).

  18. 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).

  19. Density Optimization of Lithium Lanthanum Titanate Ceramics for Lightweight Lithium-Air Batteries

    Science.gov (United States)

    2014-11-01

    Density Optimization of Lithium Lanthanum Titanate Ceramics for Lightweight Lithium -Air Batteries by Claire Weiss Brennan, Victoria Blair...Ground, MD 21005-5069 ARL-TR-7145 November 2014 Density Optimization of Lithium Lanthanum Titanate Ceramics for Lightweight Lithium -Air...COVERED (From - To) 1 June–31 August 2014 4. TITLE AND SUBTITLE Density Optimization of Lithium Lanthanum Titanate Ceramics for Lightweight Lithium

  20. 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.

  1. Barium carbonate as an agent to improve the electrical properties of neodymium-barium-copper system at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, J.P. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Duarte, G.W. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Research Group in Technology and Information, Centro Universitário Barriga Verde (UNIBAVE), Santa Catarina, SC (Brazil); Caldart, C. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Kniess, C.T. [Post-Graduate Program in Professional Master in Management, Universidade Nove de Julho, São Paulo, SP (Brazil); Montedo, O.R.K.; Rocha, M.R. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Riella, H.G. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Fiori, M.A., E-mail: fiori@unochapeco.edu.br [Post-Graduate Program in Environmental Science, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil); Post-Graduate Program in Technology and Management of the Innovation, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil)

    2015-11-15

    Specialized ceramics are manufactured under special conditions and contain specific elements. They possess unique electrical and thermal properties and are frequently used by the electronics industry. Ceramics containing neodymium-barium-copper (NBC) exhibit high conductivities at low temperatures. NBC-based ceramics are typically combined with oxides, i.e., NBCo produced from neodymium oxide, barium oxide and copper oxide. This study presents NBC ceramics that were produced with barium carbonate, copper oxide and neodymium oxide (NBCa) as starting materials. These ceramics have good electrical conductivities at room temperature. Their conductivities are temperature dependent and related to the starting amount of barium carbonate (w%). - Highlights: • The new crystalline structure were obtained due presence of the barium carbonate. • The NBCa compound has excellent electrical conductivity at room temperature. • The grain crystalline morphology was modified by presence of the barium carbonate. • New Phases α and β were introduced by carbonate barium in the NBC compound.

  2. Application of artificial neural network in 3D imaging with lanthanum bromide calorimeter

    Science.gov (United States)

    Gostojic, A.; Tatischeff, V.; Kiener, J.; Hamadache, C.; Karkour, N.; Linget, D.; Grave, X.; Gibelin, L.; Travers, B.; Blin, S.; Barrillon, P.

    2015-07-01

    Gamma-ray astronomy in the energy range from 0.1 up to 100 MeV holds many understudied questions connected with e.g. stellar nucleosynthesis, the active Sun, neutron stars and black holes. To access the physics behind, a significant improvement in detection sensitivity is needed compared to previous missions, e.g. CGRO and INTEGRAL. One of the promising concepts for a future gamma-ray mission is an Advanced Compton Telescope. Under the project of creating a prototype of such instrument, we study the perspectives of using a novel inorganic scintillator as a calorimeter part. Modern inorganic crystal or ceramics scintillators are constantly improving on qualities such as energy resolution and radiation hardness, and this makes them a smart choice for a new space-borne telescope. At CSNSM Orsay, we have assembled a detection module from a 5 × 5cm2 area and 1 cm thick, cerium-doped lanthanum (III) bromide (LaBr3:Ce) inorganic scintillator coupled to a 64 channel multi-anode photomultiplier. The readout of the PMT signals is carried out with the ASIC MAROC, used previously for the luminometer of the ATLAS detector (CERN). Characterization, thorough measurements with various radioactive sources, as well as, single photoelectron detection have been done. Furthermore, we made a comparison of measurements with a detailed GEANT4-based simulation which includes tracking of the optical photons. Finally, we have studied the 3D reconstruction of the first interaction point of incident gamma rays, utilizing a neural network algorithm. This spatial position resolution plays a crucial part in the future implementations and, together with the other measured properties, it makes our detector module very interesting for the next generation of space telescopes operating in the MeV range.

  3. Effect of counterions on lanthanum biosorption by Sargassum polycystum.

    Science.gov (United States)

    Diniz, Vivian; Volesky, Bohumil

    2005-06-01

    The effect of the presence of different anions on the biosorption of La(3+) (Lanthanum) using Sargassum polycystum Ca-loaded biomass was studied in this work. Different types of metal salts were used, such as nitrate, sulphate and chloride. The presence of the anion sulphate decreased the metal uptake for tested pH values of 3--5 when compared to the nitrate and chloride systems. The presence of chloride ions did not seem to interfere with the lanthanum removal. The speciation of lanthanum in solution could explain the differences obtained for the different systems and the Mineql+ program was used for the calculations. A monovalent complex with sulphate and lanthanum was formed that had lower apparent affinity towards the biomass compared to the free trivalent metal ion. The La uptake varied from 0.6 to 1.0 mmol g(-1). The Langmuir model was used to describe quantitatively the sorption isotherms. The addition of sulphuric acid for pH adjustment decreased the metal uptake from lanthanum sulphate solutions when compared to the nitric acid addition. The effect was more pronounced with sulphuric acid due to the formation of complexes.

  4. Methyl chloride production from methane over lanthanum-based catalysts.

    Science.gov (United States)

    Podkolzin, Simon G; Stangland, Eric E; Jones, Mark E; Peringer, Elvira; Lercher, Johannes A

    2007-03-07

    The mechanism of selective production of methyl chloride by a reaction of methane, hydrogen chloride, and oxygen over lanthanum-based catalysts was studied. The results suggest that methane activation proceeds through oxidation-reduction reactions on the surface of catalysts with an irreducible metal-lanthanum, which is significantly different from known mechanisms for oxidative chlorination. Activity and spectroscopic measurements show that lanthanum oxychloride (LaOCl), lanthanum trichloride (LaCl3), and lanthanum phases with an intermediate extent of chlorination are all active for this reaction. The catalyst is stable with no noticeable deactivation after three weeks of testing. Kinetic measurements suggest that methane activation proceeds on the surface of the catalyst. Flow and pulse experiments indicate that the presence of hydrogen chloride is not required for activity, and its role appears to be limited to maintaining the extent of catalyst chlorination. In contrast, the presence of gas-phase oxygen is essential for catalytic activity. Density-functional theory calculations suggest that oxygen can activate surface chlorine species by adsorbing dissociatively and forming OCl surface species, which can serve as an active site for methane activation. The proposed mechanism, thus, involves changing of the formal oxidation state of surface chlorine from -1 to +1 without any changes in the oxidation state of the underlying metal.

  5. Study on Aldol Condensation of HCHO and CH3CHO over MgO Catalysts Modified by Lanthanum and Cerium

    Institute of Scientific and Technical Information of China (English)

    王幸宜; 李春香; 杨菊群

    2004-01-01

    Aldol condensation of HCHO and CH3CHO over MgO, modified MgO and Al2O3 with rare earth oxides, was studied. The measurement of adsorption of pyrrole on catalysts by in-situ FT-IR and NH3 TPD indicated that the addition of elements La or Ce into MgO increased the acidity of the solid. In-situ FT-IR showed that the activation of-C=O in HCHO adsorbed on CeO-MgO and La2O3-MgO occurred. The measurement of catalytic activity implied that the modified catalysts can promote the formation of pentaerythritol, dipentaerthritol and tripentaerythritol.

  6. Complex formation reactions of lanthanum(III), cerium(III), thorium(IV), dioxouranyl(IV) complexes with tricine.

    Science.gov (United States)

    Mohamed, Mahmoud M A

    2007-08-01

    Equilibrium studies for the heavy metal ions La(III), Ce(III), Th(IV) and UO2(IV) (M) complexes of the zwitterionic buffer tricine (L) in aqueous solution are investigated. Stoichiometry and stability constants for the different complexes formed as well as hydrolysis products of the metal cations are determined at 25 degrees C and ionic strength 0.1 M NaNO3. The stability of the formed complexes are discussed in terms of the nature of the heavy metal cation. The solid complexes are synthesized and characterized by means of elemental analysis, FTIR, and TG analysis. The general molecular formulae of the obtained complexes is suggested to be [M(L)2](NO3)n-2(H2O)x, where n = the charge of the metal cation, x = no. of water molecules.

  7. Advanced Catalysis Technologies: Lanthanum Cerium Manganese Hexaaluminate Combustion Catalysts for Flat Plate Reactor for Compact Steam Reformers

    Science.gov (United States)

    2008-12-01

    E. Pocoroba, E.M. Johansson, S.G. Jaras, ”Aging Of Palladium, Platinum And Manganese-Based Combustion Catalysts For Biogas Applications,” Catalysis...M.J. Binder, “JP-8 Catalytic Cracking For Compact Fuel Processors,” Journal of Power Sources 129 (2004) 81-89. 12. P-O.F. Andersson, M

  8. Effect of cerium/lanthanum addition on microstructure and mechanical properties of Al7075 alloyvia mechanical alloying and sintering

    Institute of Scientific and Technical Information of China (English)

    R Prez-Bustamante; A Reyna-Cruz; D C Acosta-Pea; C R Santilln-Rodrguez; J A Matutes-Aquino; F Prez-Bustamante; M C Maldonado-Orozco; J Aguilar-Santilln; R Martnez-Snchez

    2016-01-01

    The effect of the Al-6Ce-3La (ACL) on the microstructural behavior of the Al7075 was investigated. Materials were syn-thesized by mechanical alloying with variation in the ACL content and milling time. Products were characterized and studied in the as-milled condition and mechanically evaluated after sintering. The synergetic effect of milling time and ACL content in the modified materials led to a reduction in the particle size. Results from electron microscopy showed a homogeneous dispersion of Ce/La phases up to 20 wt.% of ACL content after 10 h of milling. Mechanical evaluation under compressive test showed an improved performance for those alloys reinforced with 0.2 wt.% and 0.5 wt.% of ACL.

  9. Toward laser cooling of negative lanthanum

    Science.gov (United States)

    Jordan, Elena; Cerchiari, Giovanni; Erlewein, Stefan; Kellerbauer, Alban; UNIC Team

    2016-05-01

    Anion laser cooling holds the potential to allow the production of ultracold ensembles of any negatively charged species by sympathetic cooling. It is a promising technique for cooling of antiprotons to a few mK and could clear the way for precision measurements on cold antihydrogen. Laser cooling of negative ions has never been achieved, since most species have no bound-bound electric dipole transitions. Negative lanthanum (La-) is one of the few anions with multiple electric dipole transitions. The bound-bound transition from the 3F2e ground state to the 3D1o excited state in La- has been proposed theoretically as a candidate for laser cooling. The potential laser cooling transition was identified using laser photodetachment spectroscopy and its excitation energy was measured. We have studied the aforementioned transition in a beam of La anions by high-resolution laser photodetachment spectroscopy. Seven of the nine expected hyperfine structure transitions have been resolved and the transition cross sections have been estimated from experimental observations. It was found that presently La- is the most promising candidate among the atomic anions. We plan to demonstrate the first direct laser cooling of negative ions in a linear radio frequency trap. We gratefully acknowledge support from the European Research Council (ERC).

  10. Phosphate adsorption on lanthanum loaded biochar.

    Science.gov (United States)

    Wang, Zhanghong; Shen, Dekui; Shen, Fei; Li, Tianyu

    2016-05-01

    To attain a low-cost and high-efficient phosphate adsorbent, lanthanum (La) loaded biochar (La-BC) prepared by a chemical precipitation method was developed. La-BC and its pristine biochar (CK-BC) were comparatively characterized using zeta potential, BET surface area, scanning electron microscopy/energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The adsorption ability and the mechanisms during adsorption process for the La-BC samples were also investigated. La loaded on the surface of biochar can be termed as La-composites (such as LaOOH, LaONO3 and La(OH)3), leading to the decrease of negative charge and surface area of biochar. La-BC exhibited the high adsorption capacity to phosphate compared to CK-BC. Adsorption isotherm and adsorption kinetic studies showed that the Langmuir isotherm and second order model could well describe the adsorption process of La-BC, indicating that the adsorption was dominated by a homogeneous and chemical process. The calculated maximum adsorption capacity was as high as 46.37 mg g(-1) (computed in P). Thermodynamic analysis revealed that the adsorption was spontaneous and endothermic. SEM, XRD, XPS and FT-IR analysis suggested that the multi-adsorption mechanisms including precipitation, ligand exchange and complexation interactions can be evidenced during the phosphate adsorption process by La-composites in La-BC.

  11. Mechanical properties of lanthanum and yttrium chromites

    Energy Technology Data Exchange (ETDEWEB)

    Paulik, S.W.; Armstrong, T.R. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-31

    In an operating high-temperature (1000{degrees}C) solid oxide fuel cell (SOFC), the interconnect separates the fuel (P(O{sub 2}){approx}10{sup -16} atm) and the oxidant (P(O2){approx}10{sup 0.2} atm), while being electrically conductive and connecting the cells in series. Such severe atmospheric and thermal demands greatly reduce the number of viable candidate materials. Only two materials, acceptor substituted lanthanum chromite and yttrium chromite, meet these severe requirements. In acceptor substituted chromites (Sr{sup 2+} or Ca{sup 2+} for La{sup 3+}), charge compensation is primarily electronic in oxidizing conditions (through the formation of Cr{sup 4+}). Under reducing conditions, ionic charge compensation becomes significant as the lattice becomes oxygen deficient. The formation of oxygen vacancies is accompanied by the reduction of Cr{sup 4+} ions to Cr{sup 3+} and a resultant lattice expansion. The lattice expansion observed in large chemical potential gradients is not desirable and has been found to result in greatly reduced mechanical strength.

  12. 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.

  13. 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 ...

  14. 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.

  15. Gas solid techniques for preparation of pure lanthanum hexaboride

    Institute of Scientific and Technical Information of China (English)

    Mukherjee; A.; Gulnar; A.K.; Sahoo; D.K.; Krishnamurthy; N.

    2012-01-01

    The processes reported for the preparation of lanthanum hexaboride (LaB6) from lanthanum oxide involve the use of carbon either elemental or in the form of boron carbide or elemental boron itself as reducing agents, fused salts at high temperatures or reactions which require the product boride to be leached out. Each of these techniques either increases the process costs and/or increases chances of contamination in fi-nal product. Pure LaB6 can best be prepared by a reaction which produces a gaseous byprodu...

  16. Synthesis and characterization of lanthanum doped zinc oxide nanoparticles

    Science.gov (United States)

    Kumar, Vinod; Sonia, Suman, Kumar, Sacheen; Kumar, Dinesh

    2016-05-01

    La doped ZnO (Zn1-xLaxO, x = 0, 3, 6 and 9) were prepared via chemical co-precipitation method using Zinc Acetate, Lanthanum Acetate and Sodium Hydroxide at 50°C. Hydrate nanoparticles were annealed in air at 300°C for 3 hours. The synthesized samples have been characterized by powder X-ray diffraction and UV-Visiblespectrophotometer. The XRD measurement revealsthat the prepared nanoparticles have different microstructure without changing a hexagonal wurtzite structure. The result shows the change in nanoparticles size with the increment of lanthanum concentration for lower concentration for x = 0 to 6 and decreases at x = 9.

  17. Spectroscopy of titanium-doped gallium lanthanum sulfide glass

    OpenAIRE

    2008-01-01

    Titanium-doped gallium lanthanum sulfide (Ti:GLS) and gallium lanthanum oxysulfide (Ti:GLSO) glasses have an absorption band at similar to 500-600 nm that cannot be fully resolved because of its proximity to the band edge of the glass. At concentrations >0.5% a shoulder at 980 nm is observed in Ti:GLS but not in Ti :GLSO. The emission spectra of Ti:GLS and T :GLSO both peak at 900 nm with lifetimes of 67 and 97)us, respectively. We propose that the absorption at similar to 600 nm is due to th...

  18. Eutrophication management in surface waters using lanthanum modified bentonite

    DEFF Research Database (Denmark)

    Copetti, Diego; Finsterle, Karin; Marziali, Laura

    2016-01-01

    This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales. The availa......This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales...

  19. Enhancement of Superconductivity of Lanthanum and Yttrium Sesquicarbide

    Science.gov (United States)

    Krupka, M. C.; Giorgi, A. L.; Krikorian, N. H.; Szklarz, E. G.

    1972-06-22

    A method of enhancing the superconductivity of body-centered cubic lanthanum and yttrium sesquicarbide through formation of the sesquicarbides from ternary alloys of novel composition (N/sub x/M/sub 1-x/)C/sub z/, where N is yttrium or lanthanum, M is thorium, any of the Group IV and VI transition metals, or gold, germanium or silicon, and z is approximately 1.2 to 1.6. These ternary sesquicarbides have superconducting transition temperatures as high as 17.0/sup 0/K.

  20. 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].

  1. Production of translationally cold barium monohalide ions

    CERN Document Server

    DePalatis, M V

    2013-01-01

    We have produced sympathetically cooled barium monohalide ions BaX$^+$ (X = F, Cl, Br) by reacting trapped, laser cooled Ba$^+$ ions with room temperature gas phase neutral halogen-containing molecules. Reaction rates for two of these (SF$_6$ and CH$_3$Cl) have been measured and are in agreement with classical models. BaX$^+$ ions are promising candidates for cooling to the rovibrational ground state, and our method presents a straightforward way to produce these polar molecular ions.

  2. Crystallization behavior of a barium titanate tellurite glass doped with Eu3+ and Er3+

    Science.gov (United States)

    Ferreira, Elivelton Alves; Cassanjes, Fábia Castro; Poirier, Gael

    2013-04-01

    The main objective of this work has been to investigate the crystallization behavior of the glass composition 70TeO2-15BaO-15TiO2 doped with Eu3+ and Er3+ in order to check the possibility of obtaining transparent glass-ceramics containing rare earth-doped BaTiO3 nanocrystals. Glass samples with the ternary composition 70TeO2-15BaO-15TiO2 were synthesized by the melt-quenching method and doped with 0.1% of Eu3+ and Er3+. Thermal properties were investigated by DTA and heat-treatments were applied between Tg and Tx to induce the controlled crystallization of these glasses. One-step and two-step heat treatments were tested and the final glass-ceramics characterized by X-ray diffraction and UV-Vis absorption. It has been shown that transparent glass-ceramics can be obtained after heat-treatment but barium titanate BaTiO3 is hardly precipitated without coprecipitation of another crystalline phase identified as an isostructure of lanthanum tellurate. In addition, the crystalline volume fraction is relatively small in these transparent samples. Finally, Gold doping has been shown to be very effective to promote a volume nucleation and preferential crystallization of BaTiO3 over the other crystalline phases.

  3. Analysis of 26 Barium Stars I. Abundances

    CERN Document Server

    Allen, D M; Allen, Dinah M.; Barbuy, Beatriz

    2006-01-01

    We present a detailed analysis of 26 barium stars, including dwarf barium stars, providing their atmospheric parameters (Teff, log g, [Fe/H], vt) and elemental abundances. We aim at deriving gravities and luminosity classes of the sample stars, in particular to confirm the existence of dwarf barium stars. Accurate abundances of chemical elements were derived. Abundance ratios between nucleosynthetic processes, by using Eu and Ba as representatives of the r- and s-processes are presented. High-resolution spectra with the FEROS spectrograph at the ESO-1.5m Telescope, and photometric data with Fotrap at the Zeiss telescope at the LNA were obtained. The atmospheric parameters were derived in an iterative way, with temperatures obtained from colour-temperature calibrations. The abundances were derived using spectrum synthesis for Li, Na, Al, alpha-, iron peak, s- and r-elements atomic lines, and C and N molecular lines. Atmospheric parameters in the range 4300 < Teff < 6500, -1.2 < [Fe/H] < 0.0 and 1.4...

  4. Chemical abundances and kinematics of barium stars

    CERN Document Server

    de Castro, D B; Roig, F; Jilinski, E; Drake, N A; Chavero, C; Silva, J V Sales

    2016-01-01

    In this paper we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scale height, radial velocities, abundances of the Na, Al, $alpha$-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code {\\sc moog}. We found that the metallicities, the temperatures and the surface gravities for barium stars can not be represented by a single gaussian distribution. The abundances of $alpha$-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heav...

  5. 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.

  6. Barium peritonitis following upper gastrointestinal series: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Su Jin; Hwang, Ji Young; Kim, Yong Jin; Hong, Seong Sook [Soonchunhyang University College of Medicine, Seoul Hospital, Seoul (Korea, Republic of)

    2017-06-15

    We report a rare case of barium peritonitis following an upper gastrointestinal (GI) series and its imaging findings in a 74-year-old female. Barium peritonitis is a rare but life-threatening complication of GI contrast investigation. Therefore, clinical awareness of barium peritonitis as a complication of GI tract contrast investigation would help to prevent such a complication and manage the patients properly.

  7. History and challenges of barium titanate: Part I

    Directory of Open Access Journals (Sweden)

    Vijatović M.M.

    2008-01-01

    Full Text Available Barium titanate is the first ferroelectric ceramics and a good candidate for a variety of applications due to its excellent dielectric, ferroelectric and piezoelectric properties. Barium titanate is a member of a large family of compounds with the general formula ABO3 called perovskites. Barium titanate can be prepared using different methods. The synthesis method depends on the desired characteristics for the end application. The used method has a significant influence on the structure and properties of barium titanate materials. In this review paper, Part I contains a study of the BaTiO3 structure and frequently used synthesis methods.

  8. Lanthanide doped strontium-barium cesium halide scintillators

    Science.gov (United States)

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  9. Thermochemical hydrogen production via a cycle using barium and sulfur: reaction between barium sulfide and water

    Energy Technology Data Exchange (ETDEWEB)

    Ota, K.; Conger, W.L.

    1977-01-01

    The reaction between barium sulfide and water, a reaction found in several sulfur based thermochemical cycles, was investigated kinetically at 653 to 866/sup 0/C. Gaseous products were hydrogen and hydrogen sulfide. The rate determining step for hydrogen formation was a surface reaction between barium sulfide and water. The rate of formation of hydrogen can be expressed as: RH2 = 1.07 x 10/sup -2/ exp (-3180/RT) (mol H/sub 2//mol BaS s). Hydrogen sulfide was produced during the initial period of reaction and the quantity of hydrogen sulfide formed during this period decreased as the temperature of reaction was increased.

  10. Photorefractive properties of ion-implanted waveguides in strontium barium niobate crystals

    Science.gov (United States)

    Kip, D.; Kemper, B.; Nee, I.; Pankrath, R.; Moretti, P.

    1997-10-01

    Planar optical waveguides were formed in cerium-doped strontium barium niobate single crystals (Sr0.61Ba0.39Nb2O6, SBN61), either by proton or helium ion implantation. Proton-implanted samples show a large increase of dark conductivity that reduces or even prevents the recording of refractive index gratings. For waveguides formed by helium implantation this effect is absent, and they can be used for efficient holographic recording. Photorefractive properties of the waveguides are investigated by two-beam coupling. After implantation with 2.0 MeV He+ and doses of (0.5-5)񺔗 cm-2, the samples have to be polarized again, because heating or charge effects at the crystals surface during the implantation process decreases or even reverses the effective electrooptic coefficients in the waveguiding layer. For repoled samples, we find logarithmic gain coefficients of up to 45 cm-1 with time constants for the build-up of the purely ?/2-shifted refractive index grating of the order of 1 ms for the blue lines of an Ar+ laser. Photoconductivity depends nonlinearly on light intensity with an exponent xƸ.55. With increasing implanted helium dose, both electronic and nuclear damage of the waveguiding layer grows, and the photorefractive properties of the waveguides are considerably degraded.

  11. 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...

  12. 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...

  13. Joint electroreduction of lanthanum, gadolinium and boron in halide melts

    Directory of Open Access Journals (Sweden)

    Khushkhov KH.B.

    2003-01-01

    Full Text Available The joint electroreduction of La, Gd and B from chloride-fluoride melts has been studied by cyclic voltametry. Based on the analysis of voltamograms the possibility of electrosynthesis of lanthanum-gadolinium borides from chloride-fluoride melts has been shown.

  14. Electrical behaviour of strontium-doped lanthanum manganite interfaces

    DEFF Research Database (Denmark)

    Koch, Søren; Hendriksen, P.V.; Jacobsen, Torben

    2005-01-01

    The contact resistance of strontium-doped lanthanum manganite (LSM) contact pairs is investigated by polarisation analysis at different temperatures and atmospheres. The ceramic contacts have a high contact resistance, and strongly nonlinear current–voltage behaviour is observed at low temperatures...

  15. Formation mechanism and characteristics of lanthanum-doped BaTiO{sub 3} powders and ceramics prepared by the sol–gel process

    Energy Technology Data Exchange (ETDEWEB)

    Ianculescu, Adelina Carmen [Department of Oxide Materials Science and Engineering, Politehnica University of Bucharest, 17 Gh. Polizu, 011061 Bucharest (Romania); Vasilescu, Catalina Andreea, E-mail: katyvasilescu85@yahoo.com [Department of Oxide Materials Science and Engineering, Politehnica University of Bucharest, 17 Gh. Polizu, 011061 Bucharest (Romania); National Institute for Lasers, Plasma and Radiation Physics, P.O. Box MG54, 077125 Magurele (Romania); Crisan, Maria; Raileanu, Malina [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Vasile, Bogdan Stefan; Calugaru, Mihai [Department of Oxide Materials Science and Engineering, Politehnica University of Bucharest, 17 Gh. Polizu, 011061 Bucharest (Romania); Crisan, Dorel; Dragan, Nicolae [Ilie Murgulescu Institute of Physical Chemistry, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Curecheriu, Lavinia; Mitoseriu, Liliana [Department of Physics, Al. I. Cuza University of Iasi, Blvd. Carol I 11, 700506 Iasi (Romania)

    2015-08-15

    Pure and lanthanum-doped barium titanate nanopowders described by two different formulae, as Ba{sub 1−x}La{sub x}TiO{sub 3}, for lower La concentrations (0 ≤ x ≤ 0.005) and Ba{sub 1−x}La{sub x}Ti{sub 1−x/4}O{sub 3} for higher La concentration (x = 0.025) were prepared by an alkoxide sol–gel method. Single phase compositions were obtained after annealing at 900 °C for 2 h, in air. The increase of the lanthanum content causes structural and morphological changes in the oxide powders, including the evolution of the unit cell from tetragonal toward a cubic symmetry, the particle size decrease and a higher aggregation tendency. SEM investigations of the ceramics sintered at 1300 °C for 4 h indicate significant changes of the microstructural features (strong decrease of the average grain size and increase of the intergranular porosity) with the raise of La amount. Lanthanum addition to barium titanate prepared by sol–gel induces a more significant shift of the Curie temperature toward lower values, than that one reported in literature for ceramics of similar compositions, but processed by the conventional solid state method. The compositions with smaller La amount (x ≤ 0.005) show semiconducting properties at room temperature and high relative dielectric permittivity values, while the undoped ceramics and those doped with higher La content (x = 0.025) are good dielectrics. The ceramic with x = 0.025 exhibits acceptable low losses, a very diffuse ferroelectric–paraelectric transition and Curie temperature closed to the room temperature, being thus susceptible for high tunability applications. - Highlights: • Ba{sub 1−x}La{sub x}TiO{sub 3} (x ≤ 0.005) and Ba{sub 1−x}La{sub x}Ti{sub 1−x/4}O{sub 3} (x = 0.025) were prepared by sol–gel. • Ceramics with x < 0.5 exhibit semiconductor and high dielectric properties. • Ceramic with x = 0.025 exhibits acceptable low losses and diffuse phase transition.

  16. Responses in sediment phosphorus and lanthanum concentrations and composition across 10 lakes following applications of lanthanum modified bentonite

    NARCIS (Netherlands)

    Dithmer, Line; Nielsen, Ulla Gro; Lurling, Miguel; Spears, Bryan M.; Yasseri, Said; Lundberg, Daniel; Moore, Alanna; Jensen, Nicholai D.; Reitzel, Kasper

    2016-01-01

    A combined field and laboratory scale study of 10 European lakes treated between 2006 and 2013 with a lanthanum (La) modified bentonite (LMB) to control sediment phosphorus (P) release was conducted. The study followed the responses in sediment characteristics including La and P fractions and bin

  17. Responses in sediment phosphorus and lanthanum concentrations and composition across 10 lakes following applications of lanthanum modified bentonite

    DEFF Research Database (Denmark)

    Dithmer, Line; Nielsen, Ulla Gro; Lürling, Miquel;

    2016-01-01

    A combined field and laboratory scale study of 10 European lakes treated between 2006 and 2013 with a lanthanum (La) modified bentonite (LMB) to control sediment phosphorus (P) release was conducted. The study followed the responses in sediment characteristics including La and P fractions...

  18. 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

  19. Distribution of lanthanum among the chloroplast subcomponents of spinach and its biological effects on photosynthesis: location of the lanthanum binding sites in photosystem II

    Institute of Scientific and Technical Information of China (English)

    YAN Wenwu; YANG Limin; WANG Qiuquan

    2005-01-01

    The effects of lanthanum at different concentrations on the related photosynthetic activities of Hill reaction, Mg2+-ATPase and Ca2+-ATPase in spinach chloroplast were studied. Experimental results showed that lanthanum can increase all the activities at suitable concentration (15-30 mg·L-1), however, it behaves toxically on them when over used (60 mg·L-1). To get an improved understanding of the mechanism of lanthanum effects on the photosynthesis of spinach, the different subcomponents in the chloroplast of the cultured spinach were isolated, and the content of lanthanum in each subcomponent was determined by ICP-MS. The results obtained indicated that among these different subcomponents, about 90% out of the total chloroplast lanthanum was located in photosystem II (PS II) while there was little lanthanum in photosystem I (PS I). Moreover, size exclusion high performance liquid chromatography (SE-HPLC) coupled with online UV and ICP-MS detections was novelly used for locating lanthanum binding sites in PS II proteins for the first time. It was found that lanthanum has two binding sites in PS II: La associates with chlorophyll together with magnesium in PS II by partly replacing magnesium and also shares the common binding sites of PS II proteins together with the inorganic cofactors of calcium and manganese, influencing the process of photosynthesis.

  20. 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.

  1. 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}.

  2. Effect of thickness on microwave absorptive behavior of La-Na doped Co-Zr barium hexaferrites in 18.0-26.5 GHz band

    Science.gov (United States)

    Arora, Amit; Narang, Sukhleen Bindra; Pubby, Kunal

    2017-02-01

    In this research, the microwave properties of Lanthanum-Sodium doped Cobalt-Zirconium barium hexaferrites, intended as microwave absorbers, are analyzed on Vector Network Analyzer in K-band. The results indicate that the doping has resulted in lowering of real permittivity and enhancement of dielectric losses. Real permeability has shown increase while magnetic losses have shown decrease in value with doping. All these four properties have shown very small variation with frequency in the scanned frequency range which indicates the relaxation type of behavior. Microwave absorption characteristics of these compositions are analyzed with change in sample thickness. The results demonstrate that the matching frequency of the microwave absorber shifts towards lower side of frequency band with increase in thickness. The complete analysis of the prepared microwave absorbers shows a striking achievement with very low reflection loss and wide absorption bandwidth for all the six compositions in 18-26.5 GHz frequency band.

  3. INFLUENCE OF BARIUM OXIDE ADDITIONS ON PORTLAND CLINKER

    Directory of Open Access Journals (Sweden)

    Anezka Zezulova

    2016-12-01

    Full Text Available Nowadays, nuclear power plants are widespread around the world and research is of great interest. Together with nuclear research, shielding of different types of radiation is an important current topic of research aiming at their safety. Portland cement has been an elementary building material for centuries. Since barium is very efficient in shielding different types of radiation, it can be assumed that the radiation shielding capability of cement can be improved by incorporation of barium. This work deals with the influence of barium oxide, added in the form of barium carbonate and sulphate, on the formation and properties of Portland clinker. The structure of burnt clinkers and the ratio of clinker phases were studied by polarizing microscopy and by X-ray diffraction. With increasing barium content, the alite-belite ratio decreases and the content of free lime gradually increases. Moreover, sulphates induce the growth of alite crystals. The ability of barium to be a part of the clinker minerals was observed by scanning electron microscopy. Belite and clinker melt contain the highest amount of barium, but aggregates of barium oxide are formed in the clinker melt. Furthermore, the rate of alite crystallization was studied under isothermal conditions.

  4. Barium enema findings of milk allergy in infants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gyoung Ju; Kim, Mi Jeong; Lee, Hee Jung [Keimyung University School of Medicine, Daegu (Korea, Republic of)

    2006-09-15

    We wanted to evaluate the barium enema findings of milk allergy in infants. Retrospective evaluation of the plain abdominal radiography and barium enema findings was performed in fifteen young infants suffering with milk allergy. The presence of gaseous distension, rectal gas, paralytic ileus and mechanical obstruction was evaluated on the plain radiography. The presence of spasm, a transitional zone, a reversed rectosigmoid index and mucosal irregularity was analyzed on the barium enema; the presence of barium retention was also evaluated on 24-hour-delayed plain radiography. Paralytic ileus was the most common finding on the plain radiography (93%). On the barium enema, continuous spasm of the colon, ranging from the rectum to the descending colon, was revealed in ten infants (67%). A transitional zone was observed in one infant and a reversed rectosigmoid index was revealed in four. Mucosal irregularity was observed in two infants. Barium retention was demonstrated in 11 of fifteen cases: throughout the entire colon (n = 3), from the rectum to the descending colon (n = 7), and up to the transverse colon (n = 1). The most common barium enema finding of milk allergy in infants was spasm of the distal colon. The other findings were a transitional zone, a reversed rectosigmoid index, mucosal irregularity and barium retention.

  5. [Silica, aluminum, iron, sulfur, and barium in a urinary calculus].

    Science.gov (United States)

    Rodríguez-Miñón Cifuentes, J L; Salvador, E; Bellanato, J; Medina, J A

    1994-05-01

    Presentation of the analytical results by Sweep Microscopy of a small papillary calculus spontaneously eliminated after a nephritic colic. The main component is monohydrate calcium oxalate. When the stone core was analyzed with EDAX, silica, aluminium, iron, sulphur and barium were detected. The origin of these elements is discussed and the presence of barium emphasized as exceptional.

  6. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance... manganese strontium oxide (PMN P-00-1124; CAS No. 359427-90-0) is subject to reporting under this...

  7. Scattering lengths of calcium and barium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Dammalapati, U.; Willmann, L.; Knoop, S. [Kernfysisch Versneller Instituut (KVI), University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); LaserLaB Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands)

    2011-11-15

    We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba) in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca does not provide other isotopes alternative to the recently Bose condensed {sup 40}Ca that suffers strong losses because of a very large scattering length. For Ba we show by using a model potential that the even isotopes cover a broad range of scattering lengths, opening the possibility of BEC for at least one of the isotopes.

  8. Europium-doped barium bromide iodide

    Energy Technology Data Exchange (ETDEWEB)

    Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.

    2009-10-21

    Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.

  9. 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.

  10. 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.

  11. 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.

  12. Characterization of cerium fluoride nanocomposite scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Stange, Sy [Los Alamos National Laboratory; Esch, Ernst I [Los Alamos National Laboratory; Brown, Leif O [Los Alamos National Laboratory; Couture, Aaron J [Los Alamos National Laboratory; Mckigney, Edward A [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Del Sesto, Rico E [Los Alamos National Laboratory; Gilbertson, Robert D [Los Alamos National Laboratory; Mccleskey, T Mark [Los Alamos National Laboratory; Reifarth, Rene [Los Alamos National Laboratory

    2009-01-01

    Measurement of the neutron capture cross-sections of a number of short-lived isotopes would advance both pure and applied scientific research. These cross-sections are needed for calculation of criticality and waste production estimates for the Advanced Fuel Cycle Initiative, for analysis of data from nuclear weapons tests, and to improve understanding of nucleosynthesis. However, measurement of these cross-sections would require a detector with a faster signal decay time than those used in existing neutron capture experiments. Crystals of faster detector materials are not available in sufficient sizes and quantities to supply these large-scale experiments. Instead, we propose to use nanocomposite detectors, consisting of nanoscale particles of a scintillating material dispersed in a matrix material. We have successfully fabricated cerium fluoride (CeF{sub 3}) nanoparticles and dispersed them in a liquid matrix. We have characterized this scintillator and have measured its response to neutron capture. Results of the optical, structural, and radiation characterization will be presented.

  13. 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.

  14. 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.

  15. 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.

  16. Friction and wear performances of borates and lanthanum chloride in water

    Institute of Scientific and Technical Information of China (English)

    CHEN Boshui; FANG Jianhua; WANG Jiu; LI Jia; LOU Fang

    2008-01-01

    The antiwear and friction-reducing performances of sodium borate, potassium borate and lanthanum chloride in water were evaluated on a four-ball friction tester. The topographies, element distribution and chemical characteristics of the worn surfaces were investigated by scanning electron microscope (SEM), energy dispersion of X-ray (EDX) and X-ray photoelectron spectroscope (XPS). The results indicated that sodium borate, potassium borate and lanthanum chloride increased extreme pressure, antiwear and friction-reducing capacities of water to a certain extent, of which potassium borate was the best candidate. Combination of lanthanum chloride with sodium borate and potassium borate respectively further improved antiwear and friction-reducing capacities. Scratches of worn surfaces lubricated with water containing borates and lanthanum chloride were less severe than those lubricated with water containing borates alone. A tribochemical film mainly composed of oxides of lanthanum, boron and iron reduced friction and wear for water lubricant formulated with both borates and lanthanum chloride.

  17. Barium appendicitis: A single institution review in Japan

    Science.gov (United States)

    Katagiri, Hideki; Lefor, Alan Kawarai; Kubota, Tadao; Mizokami, Ken

    2016-01-01

    AIM To review clinical experience with barium appendicitis at a single institution. METHODS A retrospective review of patients admitted with a diagnosis of acute appendicitis, from January 1, 2013 to December 31, 2015 was performed. Age, gender, computed tomography (CT) scan findings if available, past history of barium studies, pathology, and the presence of perforation or the development of complications were reviewed. If the CT scan revealed high density material in the appendix, the maximum CT scan radiodensity of the material is measured in Hounsfield units (HU). Barium appendicitis is defined as: (1) patients diagnosed with acute appendicitis; (2) the patient has a history of a prior barium study; and (3) the CT scan shows high density material in the appendix. Patients who meet all three criteria are considered to have barium appendicitis. RESULTS In total, 396 patients were admitted with the diagnosis of acute appendicitis in the study period. Of these, 12 patients (3.0%) met the definition of barium appendicitis. Of these 12 patients, the median CT scan radiodensity of material in the appendix was 10000.8 HU, ranging from 3066 to 23423 HU (± 6288.2). In contrast, the median CT scan radiodensity of fecaliths in the appendix, excluding patients with barium appendicitis, was 393.1 HU, ranging from 98 to 2151 HU (± 382.0). The CT scan radiodensity of material in the appendices of patients with barium appendicitis was significantly higher than in patients with nonbarium fecaliths (P < 0.01). CONCLUSION Barium appendicitis is not rare in Japan. Measurement of the CT scan radiodensity of material in the appendix may differentiate barium appendicitis from routine appendicitis.

  18. 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.

  19. 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.

  20. 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.

  1. The Novel Formation of Barium Titanate Nanodendrites

    Directory of Open Access Journals (Sweden)

    Chien-Jung Huang

    2014-01-01

    Full Text Available The barium titanate (BaTiO3 nanoparticles with novel dendrite-like structures have been successfully fabricated via a simple coprecipitation method, the so-called BaTiO3 nanodendrites (BTNDs. This method was remarkable, fast, simple, and scalable. The growth solution is prepared by barium chloride (BaCl2, titanium tetrachloride (TiCl4, and oxalic acid. The shape and size of BaTiO3 depend on the amount of added BaCl2 solvent. To investigate the influence of amount of BaCl2 on BTNDs, the amount of BaCl2 was varied in the range from 3 to 6 mL. The role of BaCl2 is found to have remarkable influence on the morphology, crystallite size, and formation of dendrite-like structures. The thickness and length of the central stem of BTND were ~300 nm and ~20 μm, respectively. The branchings were found to occur at irregular intervals along the main stem. Besides, the formation mechanism of BTND is proposed and discussed.

  2. NANOSCALE BARIUM HYDROSILICATES: CHOOSING THE SYNTHESIS TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    GRISHINA Anna Nikolaevna

    2013-08-01

    Full Text Available Cement concretes are the most used materials in modern civil engineering. Due to that such materials draw great attention both in the Russian Federation and abroad. The possibility to enhance the manufacturability and operational properties of concretes results in significant reduction of overall operating costs. Many enhancement methods have been elaborated. Among them there is one based on introduction of calcium hydrosilicates into construction composition. The authors set up a hypothesis that similarity between properties and structures of different hydrosilicates (for example, alkaline earth metals and metals of the second group will provide similar increased operational characteristics. The specialists of Research and Educational Center «Nanotechnology» are developing cement composites nanomodification methods which include introduction of nanodimensional barium hydrosilicates particles. The synthesis of barium hydrosilicates particles can be done with the use of many technologies, different by energy consumption or performing complexity. Taking into account both these factors, one can assume that low-temperature sol-gel synthesis from diluted water solutions is the proper technology. The present paper shows that this assumption is correct. The selection of certain technology is made by the means of multiobjective optimization, which is in turn is performed by the means of linear scalarization. This method, while not always giving the Pareto optimal solutions, can be easily implemented. The particle size distribution is taken into consideration during selection of objectives and weights. It is shown that selected technology allows manufacturing nanoparticles with median size about 30 nm.

  3. 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...

  4. 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.

  5. 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.

  6. Cerium fluoride nanoparticles protect cells against oxidative stress.

    Science.gov (United States)

    Shcherbakov, Alexander B; Zholobak, Nadezhda M; Baranchikov, Alexander E; Ryabova, Anastasia V; Ivanov, Vladimir K

    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 CeF3: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 CeF3 nanoparticles are shown to provide noteworthy protection to cells against the vesicular stomatitis virus. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. 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...

  8. 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.

  9. Lanthanum Deposition in the Stomach: Usefulness of Scanning Electron Microscopy for Its Detection.

    Science.gov (United States)

    Iwamuro, Masaya; Urata, Haruo; Tanaka, Takehiro; Ando, Akemi; Nada, Takahiro; Kimura, Kosuke; Yamauchi, Kenji; Kusumoto, Chiaki; Otsuka, Fumio; Okada, Hiroyuki

    2017-02-01

    After having been treated with lanthanum carbonate administration for 4 years for hyperphosphatemia, a 75-year-old Japanese woman undergoing hemodialysis was diagnosed with lanthanum phosphate deposition in the stomach. The deposition, seen as white microgranules, was observed using esophagogastroduodenoscopy with magnifying observation. To the best of our knowledge, these are the minutest endoscopy images of lanthanum phosphate deposition in the gastric mucosa. Scanning electron microscopy (SEM) observation enabled easier identification of the deposited material, which was visible as bright areas. The present case suggests the usefulness of SEM observation in the detection of lanthanum phosphate deposition in the gastrointestinal tract.

  10. Cytotoxicity and genotoxicity of a monazite component: lanthanum effects on the viability and induction of breaks in the DNA of human lymphocytes; Citotoxicidade e genotoxicidade de um componente da monazita: efeitos do lantanio na viabilidade e inducao de quebras no DNA de linfocitos humanos

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Amanda Valle de Almeida

    2007-07-01

    The Monazite is a mineral extracted from open mines. It is constituted by lanthanum element aggregated with cerium, yttrium and thorium [(Ce, La, Y, Th)PO{sub 4}]. Lanthanum (La) is a rare-earth metal with applications in agriculture, industry and medicine. Since lanthanides and their compounds show a broad spectrum of applications there is an increased risk of incorporation in human. Inhalation of aerosols containing La is the main route of incorporation in workers exposed to several chemical forms of La. Herein, we examined the effect of lanthanum nitrate - La(NO{sub 3}){sub 3} in human lymphocytes. JURKAT cells and human peripheral lymphocytes (HPL) were used to evaluate the effect of La(NO{sub 3}){sub 3} on viability (apoptosis or necrosis) and DNA strand breaks induction or/and alkali-labile sites (ALS). We demonstrate that La has a cytotoxic and genotoxic effect on both cell lines. The results indicate that necrosis is the pathway by which La(NO{sub 3}){sub 3} induces cytotoxicity. The vitamin E is able to diminish DNA strand breaks induced by La(NO{sub 3}){sub 3} suggesting that reactive oxygen species (ROS) may be involved in the genotoxic process. (author)

  11. Thorium adsorption behaviour on mixed ammonium lanthanum oxalate, LAOX

    Energy Technology Data Exchange (ETDEWEB)

    Valentini Ganzerli, M.T.; Maggi, L.; Crespi Caramella, V

    1999-07-01

    The cation-exchange properties of mixed ammonium lanthanum oxalate, LAOX, were studied by batch equilibration as a function of the concentration of some cations, such as alkaline earths or ammonium and of some anions and acids. The distribution coefficients for thorium are high, while U(VI) is not adsorbed over a large acidity range. Thus, the separation of thorium from uranium may be successfully carried out. The experimental conditions of adsorption, elution and recovery of thorium were investigated as well, by using chromatographic columns filled with LAOX, in order to set best the separation conditions from uranyl ions. Instrumental neutron activation analysis, ICP emission spectrometry and the UV spectrometry were used to evaluate the thorium, uranium and lanthanum concentrations00.

  12. Tribological Performance and Tribochemical Mechanism of Lanthanum Dialkyldithiophosphate

    Institute of Scientific and Technical Information of China (English)

    Jiang Song; Wei Yunlong; Cheng Xiyun; Chen Boshui

    2005-01-01

    Lanthanum dialkyldithiophosphate (LaDDP) was synthesized. Its tribological behavior was evaluated with a four-ball machine. The results show that LaDDP possesses very good antiwear and friction reduction capacities. The boundary film composition, characterized by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), reveals that the antiwear and friction reduction layer containing metallic La, La2O3, phosphate, sulphate, tribopolmer and lanthanum tribodiffusion layer prevent the rubbing pairs from contacting directly and result in better extreme pressure and antiwear behavior. The microhardness of frictional surface increases by 25%. It indicates that the frictional surface is strengthened by La tribodiffusion layer. The tribological decomposition reactions of LaDDP are simulated through mass spectroscopy. Its tribological mechanism was suggested.

  13. Preparation of lanthanum ferrite powder at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Andoulsi, R.; Horchani-Naifer, K.; Ferid, M., E-mail: karima_horchani@yahoo.com [Physical Chemistry Laboratory of Mineral Materials and their Applications, Hammam-Lif (Tunisia)

    2012-01-15

    Single lanthanum ferrite phase was successfully prepared at low processing temperature using the polymerizable complex method. To implement this work, several techniques such as differential scanning calorimetry, X-ray diffraction, Fourier Transform Infrared Spectroscopy, scanning electron microscopy and BET surface area measurements were used. Throw the obtained results, it was shown that steps of preparing the powder precursor and temperature of its calcination are critical parameters for avoiding phase segregation and obtaining pure lanthanum ferrite compound. Thus, a single perovskite phase was obtained at 600 deg C. At this temperature, the powder was found to be fine and homogeneous with an average crystallite size of 13 nm and a specific surface area of 12.5 m{sup 2}.g{sup -1}. (author)

  14. Design and fabrication of lanthanum-doped tin-silver-copper lead-free solder for the next generation of microelectronics applications in severe environment

    Science.gov (United States)

    Sadiq, Muhammad

    Tin-Lead solder (Sn-Pb) has long been used in the Electronics industry. But, due to its toxic nature and environmental effects, certain restrictions are made on its use by the European Rehabilitation of Hazardous Substances (RoHS) directive, and therefore, many researchers are looking to replace it. The urgent need for removing lead from solder alloys led to the very fast introduction of lead-free solder alloys without a deep knowledge of their behavior. Therefore, an extensive knowledge and understanding of the mechanical behavior of the emerging generation of lead-free solders is required to satisfy the demands of structural reliability. Sn-Ag-Cu (SAC) solders are widely used as lead-free replacements but their coarse microstructure and formation of hard and brittle Inter-Metallic Compounds (IMCs) have limited their use in high temperature applications. Many additives are studied to refine the microstructure and improve the mechanical properties of SAC solders including iron (Fe), bismuth (Bi), antimony (Sb) and indium (In) etc. Whereas many researchers studied the impact of novel rare earth (RE) elements like lanthanum (La), cerium (Ce) and lutetium (Lu) on SAC solders. These RE elements are known as “vitamins of metals” because of their special surface active properties. They reduce the surface free energy, refine the grain size and improve the mechanical properties of many lead free solder alloys like Sn-Ag, Sn-Cu and SAC but still a systematic study is required to explore the special effects of “La” on the eutectic SAC alloys. The objective of this PhD thesis is to extend the current knowledge about lead free solders of SAC alloys towards lanthanum doping with varying environmental conditions implemented during service. This thesis is divided into six main parts.

  15. A New Homologous Series of Lanthanum Copper Oxides

    NARCIS (Netherlands)

    Cava, R.J.; Siegrist, T.; Hessen, B.; Krajewski, J.J.; Peck, Jr.; Batlogg, B.; Tagaki, H.; Waszczak, J.V.; Schneemeyer, L.F.; Zandbergen, H.W.

    1991-01-01

    We report the synthesis and structural characterization of a new homologous series of lanthanum cuprates, with the formula La4+4nCu8+2nO14+8n . The n = 2 and n = 3 members, La2Cu2O5 and La8Cu7O19 , synthesized in the bulk, are stable in very narrow temperature ranges in air and oxygen. The n = 4 mem

  16. Lanthanum halide nanoparticle scintillators for nuclear radiation detection

    Energy Technology Data Exchange (ETDEWEB)

    Guss, Paul; Guise, Ronald [Remote Sensing Laboratory, P.O. Box 98521, M/S RSL-48, Las Vegas, Nevada 89193 (United States); Yuan Ding [National Security Technologies, LLC, Los Alamos Operations, P.O. Box 809, M/S LAO/C320, Los Alamos, New Mexico 87544 (United States); Mukhopadhyay, Sanjoy [Remote Sensing Laboratory-Andrews, Building 1783, Arnold Avenue Andrews AFB, Maryland 20762 (United States); O' Brien, Robert; Lowe, Daniel [University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, Nevada 89154 (United States); Kang Zhitao; Menkara, Hisham [Georgia Tech Research Institute, 925 Dalney St., Atlanta, Georgia 30332 (United States); Nagarkar, Vivek V. [RMD, Inc., 44 Hunt Street, Watertown, Massachusetts 02472 (United States)

    2013-02-14

    Nanoparticles with sizes <10 nm were fabricated and characterized for their nanocomposite radiation detector properties. This work investigated the properties of several nanostructured radiation scintillators, in order to determine the viability of using scintillators employing nanostructured lanthanum trifluoride. Preliminary results of this investigation are consistent with the idea that these materials have an intrinsic response to nuclear radiation that may be correlated to the energy of the incident radiation.

  17. First Synthesis of Zirconia-pillared Layered Lanthanum Niobate

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A zirconia-pillared layered lanthanum niobate was prepared by first preswelling layered HLaNb2O7 with n-hexadecylamine(n-C16H33NH2), then further reacting with zirconyl chloride aqueous solution, and finally calcining the resultant solid product in air. The obtained new material has an interlayer spacing of 1.36nm, and a high thermal stability above 700°C.

  18. Lanthanum(III) catalysts for highly efficient and chemoselective transesterification.

    Science.gov (United States)

    Hatano, Manabu; Ishihara, Kazuaki

    2013-03-11

    A facile, atom-economical, and chemoselective esterification is crucial in modern organic synthesis, particularly in the areas of pharmaceutical, polymer, and material science. However, a truly practical catalytic transesterification of carboxylic esters with various alcohols has not yet been well established, since, with many conventional catalysts, the substrates are limited to 1°- and cyclic 2°-alcohols. In sharp contrast, if we take advantage of the high catalytic activities of La(Oi-Pr)(3), La(OTf)(3), and La(NO(3))(3) as ligand-free catalysts, ligand-assisted or additive-enhanced lanthanum(III) catalysts can be highly effective acid-base combined catalysts in transesterification. A highly active dinuclear La(III) catalyst, which is prepared in situ from lanthanum(III) isopropoxide and 2-(2-methoxyethoxy)ethanol, is effective for the practical transesterification of methyl carboxylates, ethyl acetate, weakly reactive dimethyl carbonate, and much less-reactive methyl carbamates with 1°-, 2°-, and 3°-alcohols. As the second generation, nearly neutral "lanthanum(III) nitrate alkoxide", namely La(OR)(m)(NO(3))(3-m), has been developed. This catalyst is prepared in situ from inexpensive, stable, low-toxic lanthanum(III) nitrate hydrate and methyltrioctylphosphonium methyl carbonate, and is highly useful in the non-epimerized transesterification of α-substituted chiral carboxylic esters, even under azeotropic reflux conditions. In these practical La(III)-catalyzed transesterifications, colorless esters can be obtained in small- to large-scale synthesis without the need for inconvenient work-up or careful purification procedures.

  19. Effect of Lanthanum on Disease Resistance Related Enzymes of Rape

    Institute of Scientific and Technical Information of China (English)

    曾青; 朱建国; 谢祖彬; 褚海燕; 张雅莉

    2003-01-01

    The effects of lanthanum on the protective enzymes of rape (Brassica juncea) were studied in hydroponics experiment. Results show that when treated with 0.3 mg*kg-1 La, the content of chlorophyll and the activities of peroxidase(POD), catalase(CAT), superoxide dismutase(SOD) and polyphenoloxidase(PPO) in rape increase, but the content of malondialdehyde(MDA) in rape decreases. However, the treatments do not change the content of soluble protein in rape significantly.

  20. Strengthening mechanism of steels treated by barium-bearing alloys

    Institute of Scientific and Technical Information of China (English)

    Zhouhua Jiang; Yang Liu

    2008-01-01

    The deoxidation, desulfurization, dephosphorization, microstructure, and mechanical properties of steels treated by barium-bearing alloys were investigated in laboratory and by industrial tests. The results show that barium takes part in the deoxidation reaction at the beginning of the experiments, generating oxide and sulfide compound inclusions, which easily float up from the molten steel, leading to the rapid reduction of total oxygen content to a very low level. The desulfurization and dephosphorization capabilities of calcium-bearing alloys increase with the addition of barium. The results of OM and SEM observations and mechanical property tests show that the structure of the steel treated by barium-bearing alloys is refined remarkably, the iamellar thickness of pearlitic structure decreases, and the pearlitic morphology shows clustering distribution. Less barium exists in steel substrate and the enrichment of barium-bearing precipitated phase mostly occurs in grain boundary and phase boundary, which can prevent the movement of grain boundary and dislocation during the heat treatment and the deformation processes. Therefore, the strength and toughness of barium-treated steels are improved by the effect of grain-boundary strengthening and nail-prick dislocation.

  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. Electrical properties of iron doped apatite-type lanthanum silicates

    Institute of Scientific and Technical Information of China (English)

    SHI Qingle; ZHANG Hua

    2012-01-01

    The effect of Fe doping on the electrical properties of lanthanum silicates was investigated.The apatite-type lanthanum silicates La10Si6-xFexO27-x/2 (x=0.2,0.4,0.6,0.8,1.0) were synthesized via sol-gel process.The unit cell volume increased with Fe doping because the ionic radius of Fe3+ ion is larger than that of Si4+ ion.The conductivities of La10Si6-xFexO27 x/2 first increased and then decreased with the increasing of Fe content.The increase of the conductivity might be attributed to the distortion of the cell lattice,which assisted the migration of the interstitial oxygen ions.The decrease of the conductivity might be caused by the lower concentration of interstitial oxygen ions.The optimum Fe doping content in lanthanum silicates was 0.6.La10Si5.4Fe0.6O26.7 exhibited the highest ionic conductivity of 2.712× 10-2 S/cm at 800 ℃.The dependence of conductivity on oxygen partial pressure p(O2) suggested that the conductivity of La10Si6-xFexO27-x/2 was mainly contributed by ionic conductivity.

  3. Picosecond Photovoltaic Response in Tilted Lanthanum Doped Manganite Films

    Directory of Open Access Journals (Sweden)

    Zhiqing Lu

    2013-01-01

    Full Text Available Anisotropic picosecond photovoltaic responses were observed in lanthanum doped manganite LaxCa1-xMnO3 (x=0.67 and 0.4 thin films, which were deposited on miscut LaSrAlO4 substrates under ultraviolet pulsed laser irradiation without external bias. The 10%–90% rise time and the full width at half maximum of La0.67Ca0.33MnO3 were 470 and 585 ps, respectively, and those of La0.4Ca0.6MnO3 were 220 and 515 ps. The photovoltage sensitivities of La0.67Ca0.33MnO3 and La0.4Ca0.6MnO3, which are sensitive to the concentrations of lanthanum of the samples, are 0.28 V/mJ and 3.47 V/mJ, respectively. The photosensitivity in the films deposited on MgO is higher than that in those deposited on LaSrAlO4 substrates, for it has a big lattice mismatch. These results should open a route for the application of lanthanum doped manganite as an ultrafast photodetector material.

  4. Barium concentration in grain of Aegilops and Triticum species

    Directory of Open Access Journals (Sweden)

    Denčić Srbislav S.

    2015-01-01

    Full Text Available The aim of this study was to evaluate the concentration of barium in grain of various Aegilops and Triticum species with different genomes. The studied species differed significantly with respect to the concentration of barium. The grain of wild diploid Aegilops speltoides, the donor of B genome, contained significantly higher Ba concentration than all other analyzed genotypes. Wild and cultivated tetraploid wheats (Triticum diciccoides, Triticum dicoccon, Triticum turgidum and Triticum durum had the lowest Ba concentration in grain. The modern cultivated hexaploid varieties presented substantial variation in grain concentration of barium. The highest Ba concentration (3.42 mg/kg occurred in Serbian winter wheat variety Panonnia.

  5. Analysis of europium doped luminescent barium thioaluminate

    Institute of Scientific and Technical Information of China (English)

    张东璞; 喻志农; 薛唯; 章婷; 丁瞾; 王武育

    2010-01-01

    Europium-doped barium thioaluminate sputtering target was synthesized by powder sintering method and thin film was deposited by radio frequency(RF) sputtering.X-ray diffractometer(XRD) pattern indicated that the main compound of the target was BaAl4S7.Oxygen was the main impurity which led to the formation of BaAl2O4.It was shown that both BaAl4S7 and BaAl2S4 were contained in the as-grown thin films and a 471.7 nm emission peak in the PL spectra appeared due to a combination of BaAl4S7:Eu2+ and BaAl2S4:Eu2...

  6. Chemical abundance analysis of 19 barium stars

    CERN Document Server

    Yang, G C; Spite, M; Chen, Y Q; Zhao, G; Zhang, B; Liu, G Q; Liu, Y J; Liu, N; Deng, L C; Spite, F; Hill, V; Zhang, C X

    2016-01-01

    We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16 m telescope at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. The chemical abundances of the sample stars were obtained from an LTE, plane-parallel and line-blanketed atmospheric model by inputting the atmospheric parameters (effective temperatures, surface gravities, metallicity and microturbulent velocity) and equivalent widths of stellar absorption lines. These samples of Ba stars are giants indicated by atmospheric parameters, metallicities and kinematic analysis about UVW velocity. Chemical abundances of 17 elements were obtained for these Ba stars. Their light elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn and Ni) are similar to the solar abundances. Our samples of Ba stars show obvious overabundances of neutron-capture (n-ca...

  7. Hydrolytic enzyme activity enhanced by Barium supplementation

    Directory of Open Access Journals (Sweden)

    Camilo Muñoz

    2016-10-01

    Full Text Available Hydrolysis of polymers is a first and often limiting step during the degradation of plant residues. Plant biomass is generally a major component of waste residues and a major renewable resource to obtain a variety of secondary products including biofuels. Improving the performance of enzymatic hydrolysis of plant material with minimum costs and limiting the use of additional microbial biomass or hydrolytic enzymes directly influences competitiveness of these green biotechnological processes. In this study, we cloned and expressed a cellulase and two esterases recovered from environmental thermophilic soil bacterial communities and characterize their optimum activity conditions including the effect of several metal ions. Results showed that supplementing these hydrolytic reactions with Barium increases the activity of these extracellular hydrolytic enzymes. This observation represents a simple but major improvement to enhance the efficiency and competitiveness of this process within an increasingly important biotechnological sector.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Progress on Radiative Transition Probabilities in Neutral Cerium

    Science.gov (United States)

    Curry, J. J.

    2009-10-01

    Cerium is a rare-earth atom that is currently used in energy-efficient metal-halide lamps because of its rich visible emission spectrum. More than 20,000 lines have been observed and classified for neutral cerium in the wavelength range of 340 nm to 1 μm (Bill Martin, unpublished). We recently derived more than 500 absolute transition probabilities from existing experimental data (J. Phys. D: Appl. Phys. 2009). Lawler and Den Hartog at the University of Wisconsin have made measurements that are expected to produce a few thousand transition probabilities. These advances, however, leave the data situation far short of what is needed to simulate an accurate global emission spectrum in numerical models of metal-halide lamps containing cerium. One possibility for closing this gap is through atomic structure calculations. Although it may be difficult for calculations to match the accuracy of measurements for any given transition, the global spectral distribution produced with calculated transition probabilities may still be satisfactory. For such a large number of lines, calculations may be the only realistic way to produce a reasonably complete set of data. We will discuss our recent atomic structure calculations of neutral cerium with the Cowan code based on a parametric fit of calculated energy level values to experimental values.

  14. The influence of small stoichiometric deviations in the properties dielectric of barium titanate ceramics laser sintering; A influencia de pequenos desvios estequiometricos nas propriedades eletricas de ceramicas de titanato de bario sinterizadas a laser

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcelo Souza da; Silva, Ronaldo Santos da, E-mail: ssiilva990@hotmmail.com [Universidade Federal de Sergipe (UFS), Sao Cristovao, SP (Brazil). Departameneto de Fisica. Grupo de Materiais Ceramicos Avancados

    2012-07-01

    It has recently been investigated the influence of the laser sintering on the electrical properties of the ceramic bodies. This work is dedicated to studying how a small deviation stoichiometric barium and / or titanium may interfere with the dielectric properties of ceramics based on barium titanate (BaTiO3) when they are sintered by laser. Ceramics based on doped barium titanate lanthanum (Ba{sub 0,998}La{sub 0,002}Ti{sub 1-n}O{sub 3}) were produced and laser sintering. The crystalline phase was verified by X-ray diffraction, information on the microstructure of the sintered samples laser were obtained with the aid of the technique of electron microscopy (SEM) and, the impedance spectroscopy technique was used to characterize the dielectric material. The preliminary results obtained show ceramic bodies with a density of 93% and with good homogeneity of the microstructure. The high values of dielectric permittivity of the ceramics were observed for samples with a deviation where the stoichiometric ratio [Ba]/[Ti] <1. (author)

  15. 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.

  16. Effects of Lanthanum-Amino Acid Complexes on Egg Hatching and Nauplius Metamorphosis of Penaeus chinensis

    Institute of Scientific and Technical Information of China (English)

    Xin Fuyan; Qu Keming

    2002-01-01

    Studies have been carried out on the effect of lanthanum-amino acid complexes on embryo development and nauplius growth ofPenaeus chinensis. The experimental results indicate that: (1)The optimum concentrations of lanthanum-proline and Lanthanumphenylalanine for the development of eggs in monocell and dicell stages are 1.50~ 4.00mg/L and 0.50~3.00 mg/L, respectively, the egg hatching rates being raised by 21.0 ~ 46.0% and 23.0 ~42.8% ( P < 0.05 ) respectively. (2)The optimum concentrations of lanthanum- proline complex and Lanthanum-phenylalanine complex for the growth ofnauplii are 1.50~4.00 mg/L and 0.50~3.00 mg/L, the metamorphosis rate from nauplius to protozoea being raised by 16.4 ~27.5% and 20.4~26.7% (P < 0.05 ) respectively. (3)The positive effect of lanthanum-amino acid complexes on egg hatching and nauplius metamorphosis of Penaeus chinensis is better than that of lanthanum. With regard to the positive effect, lanthanum-proline complex is better than Lanthanum-phenylalanine complex.

  17. A NOVEL HYDROTHERMAL SYNTHESIS METHOD FOR BARIUM FERRITE

    Institute of Scientific and Technical Information of China (English)

    Kang Li; Hongchen Gu; Qun Wei

    2004-01-01

    In the present work, fine barium ferrite powder has been synthesized through a one-step hydrothermal process in an autoclave at [OH-]/[Cl-] ratio of 2:1 in the temperature range from 180 to 260 ℃ using barium chloride (BaCl2), ferrous chloride (FeCl2) and potassium nitrate (KNO3) as the starting materials. Both particle size and saturation magnetization (Ms) increase with increasing hydrothermal reaction temperature, while the intrinsic coercivity (iHc) peaks at 685 Oe at 230 ℃. Morphology progress from the barium ferrite precursor particles to the barium hexaferrite particles has been monitored with increasing hydrothermal reaction time at 230 ℃ in the autoclave.

  18. Peritonite por bário Barium peritonitis

    Directory of Open Access Journals (Sweden)

    Gerson Alves Pereira Júnior

    1999-10-01

    Full Text Available We report a case of a 49 years-old man who underwent a barium meal examination for an epigastric pain. A perforated gastric ulcer with barium extravasation into peritoneal cavity was seen on X-rays. During an emergency laparotomy, a perforated pyloric ulcer was noted, along with barium contamination in the peritoneal cavity. The ulcer was closed with an omental patch and an extensive peritoneal lavage with saline was performed. During the postoperative period, the patient developed signs of peritonitis and underwent a new laparotomy was at the 9th day showing a subfrenic abscess with a large barium contamination. The patient presented septic shock and multiple organ failure. dying on the 21th day.

  19. Upper gastrointestinal barium evaluation of duodenal pathology: A pictorial review

    Institute of Scientific and Technical Information of China (English)

    Pankaj; Gupta; Uma; Debi; Saroj; Kant; Sinha; Kaushal; Kishor

    2014-01-01

    Like other parts of the gastrointestinal tract(GIT), duodenum is subject to a variety of lesions both congenital and acquired. However, unlike other parts of the GIT viz. esophagus, rest of the small intestine and large intestine, barium evaluation of duodenal lesions is technically more challenging and hence not frequently reported. With significant advances in computed tomography technology, a thorough evaluation including intraluminal, mural and extramural is feasible in a single non-invasive examination. Notwithstanding, barium evaluation still remains the initial and sometimes the only imaging study in several parts of the world. Hence,a thorough acquaintance with the morphology of various duodenal lesions on upper gastrointestinal barium examination is essential in guiding further evaluation. We reviewed our experience with various common and uncommon barium findings in duodenal abnormalities.

  20. Coastal barium cycling at the West Antarctic Peninsula

    Science.gov (United States)

    Pyle, K. M.; Hendry, K. R.; Sherrell, R. M.; Meredith, M. P.; Venables, H.; Lagerström, M.; Morte-Ródenas, A.

    2017-05-01

    Barium cycling in the ocean is associated with a number of processes, including the production and recycling of organic matter, freshwater fluxes, and phenomena that affect alkalinity. As a result, the biogeochemical cycle of barium offers insights into past and present oceanic conditions, with barium currently used in various forms as a palaeoproxy for components of organic and inorganic carbon storage, and as a quasi-conservative water mass tracer. However, the nature of the oceanic barium cycle is not fully understood, particularly in cases where multiple processes may be interacting simultaneously with the dissolved and particulate barium pools. This is particularly the case in coastal polar regions such as the West Antarctic Peninsula, where biological drawdown and remineralisation occur in tandem with sea ice formation and melting, glacial meltwater input, and potential fluxes from shelf sediments. Here, we use a high-precision dataset of dissolved barium (Bad) from a grid of stations adjacent to the West Antarctic Peninsula in conjunction with silicic acid (Si(OH)4), the oxygen isotope composition of water, and salinity measurements, to determine the relative control of various coastal processes on the barium cycle throughout the water column. There is a strong correlation between Bad and Si(OH)4 present in deeper samples, but nevertheless persists significantly in surface waters. This indicates that the link between biogenic opal and barium is not solely due to barite precipitation and dissolution at depth, but is supplemented by an association between Bad and diatom tests in surface waters, possibly due to barite formation within diatom-dominated phytodetritus present in the photic zone. Sea-ice meltwater appears to exert a significant secondary control on barium concentrations, likely due to non-conservative biotic or abiotic processes acting as a sink for Bad within the sea ice itself, or sea-ice meltwater stimulating non-siliceous productivity that acts

  1. Synthesis, photoluminescence and magnetic properties of barium vanadate nanoflowers

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jing [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Chongqing University of Science and Technology, Chongqing 401331 (China); Hu, Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Xi, Yi [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Peng, Chen [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Wan, Buyong; He, Xiaoshan [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)

    2011-06-15

    Graphical abstract: The flower-shaped barium vanadate was obtained for the first time. The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. Research highlights: {yields} In the paper, the flower-shaped barium vanadate were obtained for the first time. The CHM method used here is new and simple for preparation of barium vanadate. {yields} The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. The strong bluish-green emission was observed. {yields} The ferromagnetic behavior of the barium vanadate nanoflowers was found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g. {yields} The mechanisms of PL and magnetic property of barium vanadate nanoflowers have been discussed. -- Abstract: The flower-shaped barium vanadate has been obtained by the composite hydroxide mediated (CHM) method from V{sub 2}O{sub 5} and BaCl{sub 2} at 200 {sup o}C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba{sub 3}V{sub 2}O{sub 8} with small amount of Ba{sub 3}VO{sub 4.8} coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of {approx}20 nm. The UV-visible spectrum shows that the barium vanadate sample has two optical gaps (3.85 eV and 3.12 eV). Photoluminescence spectrum of the barium vanadate flowers exhibits a visible light emission centered at 492 and 525 nm which might be attributed to VO{sub 4} tetrahedron with T{sub d} symmetry in Ba{sub 3}V{sub 2}O{sub 8}. The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g, which is mainly due to the presence of a non

  2. Solar eclipse sign of intussusception on barium enema.

    Science.gov (United States)

    Raveenthiran, V

    2002-01-01

    The colographic appearance of intussusception is variously described as a claw sign, pincer defect, shouldering effect, and coiled-spring pattern. This report adds a new radiographic sign to the list. An end-on view of an intussusception on barium enema shows a ring of contrast resembling a solar eclipse. Familiarity with this bizarre appearance is desirable, lest it may be mistaken for spillage of barium due to a colonic perforation.

  3. INFLUENCE OF BARIUM OXIDE ADDITIONS ON PORTLAND CLINKER

    OpenAIRE

    Anezka Zezulova; Theodor Stanek; Opravil Tomas

    2016-01-01

    Nowadays, nuclear power plants are widespread around the world and research is of great interest. Together with nuclear research, shielding of different types of radiation is an important current topic of research aiming at their safety. Portland cement has been an elementary building material for centuries. Since barium is very efficient in shielding different types of radiation, it can be assumed that the radiation shielding capability of cement can be improved by incorporation of barium. ...

  4. Fabrication of large-volume, low-cost ceramic lanthanum halide scintillators for gamma ray detection : final report for DHS/DNDO/TRDD project TA-01-SL01.

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, Timothy J.; Ottley, Leigh Anna M.; Yang, Pin; Chen, Ching-Fong; Sanchez, Margaret R.; Bell, Nelson Simmons

    2008-10-01

    This project uses advanced ceramic processes to fabricate large, optical-quality, polycrystalline lanthanum halide scintillators to replace small single crystals produced by the conventional Bridgman growth method. The new approach not only removes the size constraint imposed by the growth method, but also offers the potential advantages of both reducing manufacturing cost and increasing production rate. The project goal is to fabricate dense lanthanum halide ceramics with a preferred crystal orientation by applying texture engineering and solid-state conversion to reduce the thermal mechanical stress in the ceramic and minimize scintillation light scattering at grain boundaries. Ultimately, this method could deliver the sought-after high sensitivity and <3% energy resolution at 662 keV of lanthanum halide scintillators and unleash their full potential for advanced gamma ray detection, enabling rapid identification of radioactive materials in a variety of practical applications. This report documents processing details from powder synthesis, seed particle growth, to final densification and texture development of cerium doped lanthanum bromide (LaBr{sub 3}:Ce{sup +3}) ceramics. This investigation demonstrated that: (1) A rapid, flexible, cost efficient synthesis method of anhydrous lanthanum halides and their solid solutions was developed. Several batches of ultrafine LaBr{sub 3}:Ce{sup +3} powder, free of oxyhalide, were produced by a rigorously controlled process. (2) Micron size ({approx} 5 {micro}m), platelet shape LaBr{sub 3} seed particles of high purity can be synthesized by a vapor phase transport process. (3) High aspect-ratio seed particles can be effectively aligned in the shear direction in the ceramic matrix, using a rotational shear-forming process. (4) Small size, highly translucent LaBr{sub 3} (0.25-inch diameter, 0.08-inch thick) samples were successfully fabricated by the equal channel angular consolidation process. (5) Large size, high density

  5. Photocatalytic hydrogen generation over lanthanum doped TiO2 under UV light irradiation.

    Science.gov (United States)

    Liu, Y; Xie, L; Li, Y; Qu, J L; Zheng, J; Li, X G

    2009-02-01

    TiO2 nanoparticles doped with different amount of lanthanum were obtained by sol-gel approach and followed annealing at different temperature. The crystal size of TiO2 doped with lanthanum was smaller than that of pure TiO2. Photocatalytic activity of TiO2 doped with lanthanum for water splitting into H2 was investigated. The photocatalytic activity of TiO2 doped with lanthanum for water splitting into H2 is higher than that of pure TiO2. It was found that the optimal photocatalyst was TiO2 doped with 2 wt% lanthanum and calcined at 600 degrees C for 4 h which had hydrogen generation rate 700.6 micromol h(-1).

  6. Chemical States of Lanthanum in Carbonized La2O3-Mo Thermionic Cathode Materials

    Institute of Scientific and Technical Information of China (English)

    王金淑; 周美玲; 王亦曼; 张久兴; 聂祚仁; 左铁镛

    2003-01-01

    The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calculation, thermal analysis and in-situ X-ray Photoelectron Spectroscopy. The theoretical results show that at the environment allowing for the evaporation of lanthanum, such as in high vacuum, La2O3 in the La2O3-Mo materials can be reduced to metallic lanthanum by molybdenum carbide (Mo2C). To confirm the conclusion, many analysis methods such as XRD, SPS, and TG-DTA were taken. The experimental results show that the chemical state of lanthanum changes during heating. It was proved, for the first time, that reacted metallic lanthanum appears at the surface of this kind of material at high temperature.

  7. Large-scale Hydrothermal Synthesis and Characterization of Size-controlled Lanthanum Hydroxide Nanorods

    Institute of Scientific and Technical Information of China (English)

    YI,Ran; ZHANG,Ning; SHI,Rongrong; LI,Yongbo; QIU Guanzhou; LIU Xiaohe

    2009-01-01

    Uniform lanthanum hydroxide nanorods were successfully synthesized in large quantities through a facile hydrothermal synthetic method, in which soluble lanthanum nitrate was used to supply the lanthanum source and triethylamine (TEA) was used as both alkaline agent and complexing agent. The influences of triethylamine amount, surfactant, reaction temperature and time on the size and shape of lanthanum hydroxide nanorods were investigated in detail. Trivalent rare earth ion doped lanthanum hydroxide nanorods were also obtained in this paper. The phase structures and morphologies of the as-prepared products were investigated in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high-resolution transmis-sion electron microscopy (HRTEM). The probable formation mechanism was proposed based on the experimental results.

  8. Electrorheological behavior of rare earth-doped barium titanate suspensions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Doping Y, La, Ce into barium titanate is found to be able to improve its electrorheological (ER) effect in DC electrical field. The yield stress of a typical doped barium titanate/silicone oil suspension is approximately 3.2 -*7〗kPa at 3.5 -*7〗kV/mm, which is 10 times larger than that of pure barium titanate/silicone oil suspensions. The ER effect increases with the decrease of ionic radius of rare earth (RE) dopant when RE concentration remains constant, and the suspensions exhibit a relatively high shear stress when Y, La, Ce mole fractions are 15%, 10%~15%, and 5%, respectively. Dielectric measurements show that the suitable doping with RE element increases dielectric loss of barium titanate and causes very marked dielectric relaxation at low frequency. By measuring X-ray diffraction patterns of doped barium titanate, it is considered that the occurrence of lattice distortion or defects may be responsible for the change of dielectric properties which results in the improvement of ER effect of barium titanate in DC electrical field.

  9. Lifetime Measurement for 6snp Rydberg States of Barium

    Institute of Scientific and Technical Information of China (English)

    SHEN Li; WANG Lei; YANG Hai-Feng; LIU Xiao-Jun; LIU Hong-Ping

    2011-01-01

    @@ We present a simple and efficient method for measuring the atomic lifetimes in order of tens of microseconds and demonstrate it in the lifetime determination of barium Rydberg states.This method extracts the lifetime information from the time-of-flight spectrum directly, which is much more efficient than other methods such as the time-delayed field ionization and the traditional laser induced fluorescence.The lifetimes determined with our method for barium Rydberg 6snp(n=37-59)series are well coincident with the values deduced from the absolute oscillator strengths of barium which were given in the literature [J.Phys.B 14(1981)4489, 29(1996)655]on experiments.%We present a simple and efficient method for measuring the atomic lifetimes in order of tens of microseconds and demonstrate it in the lifetime determination of barium Rydberg states. This method extracts the lifetime information from the time-of-flight spectrum directly, which is much more efficient than other methods such as the time-delayed field ionization and the traditional laser induced fluorescence. The lifetimes determined with our method for barium Rydberg 6snp (n=37-59) series are well coincident with the values deduced from the absolute oscillator strengths of barium which were given in the literature [J. Phys. B 14 (1981) 4489, 29 (1996) 655] onexperiments.

  10. Phase I. Lanthanum-based Start Materials for Hydride Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Gschneidner, K. A. [Ames Lab., Ames, IA (United States); Schmidt, F. A. [Ames Lab., Ames, IA (United States); Frerichs, A. E. [Ames Lab., Ames, IA (United States); Ament, K. A. [Ames Lab., Ames, IA (United States)

    2013-08-20

    The purpose of Phase I of this work is to focus on developing a La-based start material for making nickel-metal (lanthanum)-hydride batteries based on our carbothermic-silicon process. The goal is to develop a protocol for the manufacture of (La1-xRx)(Ni1-yMy)(Siz), where R is a rare earth metal and M is a non-rare earth metal, to be utilized as the negative electrode in nickel-metal hydride (NiMH) rechargeable batteries.

  11. Hyperfine structure of singly ionized lanthanum and praseodymium

    Institute of Scientific and Technical Information of China (English)

    马洪良

    2002-01-01

    Hyperfine structure spectra of singly ionized lanthanum and praseodymium have been measured by collinearfast-ion-beam laser spectroscopy. All the spectral lines were resolved and the magnetic dipole and electric quadruplecoupling constants of the metastable levels and excited levels were determined. Our results are in agreement withthe published data within the experimental uncertainty. For praseodymium ions, the accuracy of the magnetic dipolecoupling constants are improved by one order of magnitude compared with other published data, and the electricquadruple coupling constants are reported for the first time.

  12. Relativistic Multichannel Treatment of Ionic Rydberg States of Lanthanum

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-Feng; JIA Feng-Dong; ZHONG Zhi-Ping; XUE Ping; XU Xiang-Yuan; YAN Jun

    2007-01-01

    Ionic Rydberg energy levels of lanthanum are calculated from first principles by relativistic multichannel theory within the framework of multichannel quantum defect theory. The present calculated results are in better agreement with the experimental measurements than the previous calculations [J. Phys. B 34 (2001)369] due to the consideration of dynamical polarizations. Moreover, in the experimental spectra achieved by a five-laser resonance excitation via the intermediate state 5d6d3 F2, a series of weak ionic Rydberg states and some of perturbing states are found and assigned in this work.

  13. Spectroscopy of vanadium (III) doped gallium lanthanum sulphide chalcogenide glass

    CERN Document Server

    Hughes, M; Rutt, H; Hewak, D

    2014-01-01

    Vanadium doped gallium lanthanum sulphide glass (V:GLS) displays three absorption bands at 580, 730 and 1155 nm identified by photoluminescence excitation measurements. Broad photoluminescence, with a full width half maximum (FWHM) of 500 nm, is observed peaking at 1500 nm when exciting at 514, 808 and 1064 nm. The fluorescence lifetime and quantum efficiency at 300 K were measured to be 33.4 us and 4 % respectively. From the available spectroscopic data we propose the vanadium ions valence to be 3+ and be in tetrahedral coordination The results indicate potential for development of a laser or optical amplifier based on V:GLS.

  14. a Bombardment Heated Lanthanum-Hexaboride Thermionic Cathode Electron Gun.

    Science.gov (United States)

    Herniter, Marc Efrem

    This dissertation concerns the development and operation of a high current density Pierce-type electron gun with a 0.75-inch-diameter lanthanum hexaboride (LaB _6) thermionic cathode. The objective of this research is to achieve as high a current density as possible from the lanthanum hexaboride cathode. The topics which are addressed are the cathode heating and control system, the Pierce-type electron gun design, and the high voltage pulsing and isolation system. Lanthanum hexaboride is used as a cathode material in applications where high current density and resistance to chemical poisoning are important. Applications include free electron lasers and high power microwave generation. A four stage Marx generator capable of producing 140-kV-peak pulses with a 16 mus decay time constant is used to pulse the electron gun. The cathode is heated to temperatures greater than 1800 ^circ C by electron bombardment from a tungsten filament. Both temperature-limited and space -charge-limited bombardment methods have been investigated. The temperature-limited method is open-loop unstable. Analog and digital control circuits have been developed to control this instability. A simple heating model has been developed and criteria for constructing a controllable system have been established. An instability in the heating system which is caused by evaporation of lanthanum hexaboride from the cathode is discussed. This evaporation reduces the work function of the bombarding filament and makes the temperature -limited bombardment system uncontrollable. The gun has been operated up to voltages of 115 kV achieving beam current densities of 30 A/cm ^2. The electron gun operated dependably up to voltages of 90 kV achieving temperature-limited currents of 50 A. Due to the high fields at the tip of the Pierce -focusing electrode the gun would usually arc at voltages greater than 90 kV. Electron gun operation has been observed in the temperature-limited and space-charge-limited regimes. The

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaodong, E-mail: xzhang39@utk.edu [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Moore, Michael E.; Lee, Kyung-Min; Lukosi, Eric D. [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Hayward, Jason P. [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Oak Ridge National Lab, Oak Ridge, TN 37831 (United States)

    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.

  16. 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.

  17. 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.

  18. The efficacy of steroids for postoperative persistent inflammatory reaction in a patient with barium peritonitis: A case report

    Directory of Open Access Journals (Sweden)

    Hirofumi Kojima

    2017-01-01

    Conclusion: Residual barium in the intraperitoneal cavity causes persistent inflammatory reaction in patients with barium peritonitis. The use of steroids is effective for postoperative persistent inflammation due to the residual barium.

  19. Chemical compositions of four barium stars

    CERN Document Server

    Liang, Y C; Chen, Y Q; Qiu, H M; Zhang, B

    2003-01-01

    Chemical compositions of four barium stars HD 26886, HD 27271, HD 50082 and HD 98839 are studied based on high resolution, high signal-to-noise Echelle spectra. Results show that all of them are disk stars. Their \\alpha and iron peak elements are similar to the solar abundances. The neutron-capture process elements are overabundant relative to the Solar. The heavy-element abundances of the strong Ba star HD 50082 are higher than those of other three mild Ba stars. Its mass is 1.32Msun (+0.28,-0.22Msun), and is consistent with the average mass of strong Ba stars (1.5Msun). For mild Ba star HD 27271 and HD 26886, the derived masses are 1.90Msun (+0.25,-0.20Msun) and 2.78Msun (+0.75,-0.78M_sun), respectively, which are consistent with the average mass of mild Ba stars. We also calculate the theoretical abundances of Ba stars by combining the AGB stars nucleosynthesis and wind accretion formation scenario of Ba binary systems. The comparisons between the observed abundance patterns of the sample stars with the th...

  20. High H- ionic conductivity in barium hydride

    Science.gov (United States)

    Verbraeken, Maarten C.; Cheung, Chaksum; Suard, Emmanuelle; Irvine, John T. S.

    2015-01-01

    With hydrogen being seen as a key renewable energy vector, the search for materials exhibiting fast hydrogen transport becomes ever more important. Not only do hydrogen storage materials require high mobility of hydrogen in the solid state, but the efficiency of electrochemical devices is also largely determined by fast ionic transport. Although the heavy alkaline-earth hydrides are of limited interest for their hydrogen storage potential, owing to low gravimetric densities, their ionic nature may prove useful in new electrochemical applications, especially as an ionically conducting electrolyte material. Here we show that barium hydride shows fast pure ionic transport of hydride ions (H-) in the high-temperature, high-symmetry phase. Although some conductivity studies have been reported on related materials previously, the nature of the charge carriers has not been determined. BaH2 gives rise to hydride ion conductivity of 0.2 S cm-1 at 630 °C. This is an order of magnitude larger than that of state-of-the-art proton-conducting perovskites or oxide ion conductors at this temperature. These results suggest that the alkaline-earth hydrides form an important new family of materials, with potential use in a number of applications, such as separation membranes, electrochemical reactors and so on.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Management of hyperphosphatemia in patients with end-stage renal disease: focus on lanthanum carbonate

    Directory of Open Access Journals (Sweden)

    Veerle P Persy

    2009-04-01

    Full Text Available Veerle P Persy, Geert J Behets, Marc E De Broe, Patrick C D’HaeseLaboratory of Pathophysiology, University of Antwerp, BelgiumAbstract: Elevated serum phosphate levels as a consequence of chronic kidney disease (CKD contribute to the increased cardiovascular risk observed in dialysis patients. Protein restriction and dialysis fail to adequately prevent hyperphosphatemia, and in general treatment with oral phosphate binding agents is necessary in patients with advanced CKD. Phosphate plays a pivotal role in the development of vascular calcification, one of the factors contributing to increased cardiovascular risk in CKD patients. Treatment of hyperphosphatemia with standard calcium-based phosphate binders and vitamin D compounds can induce hypercalcemic episodes, increase the Ca × PO4 product and thus add to the risk of ectopic mineralization. In this review, recent clinical as well as experimental data on lanthanum carbonate, a novel, non-calcium, non-resin phosphate binding agent are summarized. Although lanthanum is a metal cation no aluminium-like toxicity is observed since the bioavailability of lanthanum is extremely low and its metabolism differs from that of aluminium. Clinical studies now document the absence of toxic effects of lanthanum for up to 6 years of follow-up. The effects of lanthanum on bone, vasculature and brain are discussed and put in perspective with lanthanum pharmacokinetics.Keywords: lanthanum carbonate, phosphate binding, chronic kidney disease

  7. 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...

  8. Cerium chloride reduces enamel lesion initiation and progression in vitro.

    Science.gov (United States)

    Wegehaupt, F J; Buchalla, W; Sener, B; Attin, T; Schmidlin, P R

    2014-01-01

    Determination of the potential of cerium chloride to reduce artificial carious mineral loss and lesion depth progression. A total of 160 enamel samples were prepared from 40 bovine lower central incisors. Crowns were sectioned into four pieces, embedded in acrylic resin, ground flat and allocated to eight groups (S1-S4 and D1-D4; n = 20). Specimens of groups D1-D4 were stored (for 7 days) in a demineralizing buffer solution to induce caries-like lesions. Afterwards, samples were treated for 30 s with one of the following solutions: placebo (S1 and D1), amine fluoride (S2 and D2), cerium chloride (S3 and D3) and a combination of fluoride and cerium chloride (S4 and D4). After another 7 (D1-D4) or 14 (S1-S4) days in demineralizing buffer solution, integrated mineral loss and lesion depth were determined by transversal microradiography and compared by Scheffé's post hoc tests. In groups S1-S4, the highest values for integrated mineral loss and lesion depth were observed for group S1 (placebo), the lowest values for group S4. The results in groups S2-S4 were not significantly different. In groups D1-D4, the highest values for integrated mineral loss and lesion depth were observed for group D1 (placebo), the lowest values in groups D3 and D4. In group D2, integrated mineral loss and lesion depth were significantly lower as compared to D1, but significantly higher compared to groups D3 and D4. Cerium chloride and its combination with fluoride are able to significantly reduce carious mineral loss and the progression of lesion depth.

  9. 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.

  10. 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.

  11. 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.

  12. 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)

  13. 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.

  14. Microwave Combustion Synthesis of Silver Doped Lanthanum Ferrite Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    P. A. Desai

    2013-05-01

    Full Text Available Lanthanum ferrite (LaFeO3 and silver doped LaFeO3 powders were synthesized by a single step microwave combustion route using nitrates as precursors and glycine as a fuel. XRD analysis indicated the formation of cubic phase with the dopant peaks at 2θ values of 38.3°, 44.1° and 64.4° apart from the peaks corresponding to LaFeO3. As observed from the transmission electron micrographs, LaFeO3 exhibits particles with a larger size (mean size ~57 nm, significant decrease in particle size is observed for silver doped samples. The magnetic measurements reveal weak ferromagnetic nature of LaFeO3, while silver doped samples are ferromagnetic in nature. Lanthanum silver ferrite (x=0.25, A site shows maximum coercivity (Hci=480.96G with hysteresis loop at room temperature which is a clear sign of ferromagnetic ordering. The S shape of the curve implies the presence of domain wall movements in nanoparticles. Thermogravimetric analysis of the samples show stable behavior of the products.Defence Science Journal, 2013, 63(3, pp.285-291, DOI:http://dx.doi.org/10.14429/dsj.63.2387

  15. Microwave Combustion Synthesis of Silver Doped Lanthanum Ferrite Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    P.A. Desai

    2013-05-01

    Full Text Available Lanthanum ferrite (LaFeO3 and silver doped LaFeO3 powders were synthesized by a single step microwave combustion route using nitrates as precursors and glycine as a fuel. XRD analysis indicated the formation of cubic phase with the dopant peaks at 2θ values of 38.3°, 44.1°, and 64.4° apart from the peaks corresponding to LaFeO3. As observed from the transmission electron micrographs, LaFeO3 exhibits particles with a larger size (mean size ~57 nm, significant decrease in particle size is observed for silver doped samples. The magnetic measurements reveal weak ferromagnetic nature of LaFeO3, while silver doped samples are ferromagnetic in nature. Lanthanum silver ferrite (x = 0.25, A site shows maximum coercivity (Hci = 480.96 G with hysteresis loop at room temperature which is a clear sign of ferromagnetic ordering. The S shape of the curve implies the presence of domain wall movements in nanoparticles. Thermogravimetric analysis of the samples show stable behavior of the products.

  16. Both barium and calcium activate neuronal potassium currents

    Energy Technology Data Exchange (ETDEWEB)

    Ribera, A.B.; Spitzer, N.C.

    1987-09-01

    Amphibian spinal neurons in culture possess both rapidly inactivating and sustained calcium-dependent potassium current components, similar to those described for other cells. Divalent cation-dependent whole-cell outward currents were isolated by subtracting the voltage-dependent potassium currents recorded from Xenopus laevis neurons in the presence of impermeant cadmium from the currents produced without cadmium but in the presence of permeant divalent cations. These concentrations of permeant ions were low enough to avoid contamination by macroscopic inward currents through calcium channels. Calcium-dependent potassium currents were reduced by 1 ..mu..M tetraethylammonium. These currents can also be activated by barium or strontium. Barium as well as calcium activated outward currents in young neurons (6-8 hr) and in relatively mature neurons (19-26 hr in vitro). However, barium influx appeared to suppress the sustained voltage-dependent potassium current in most cells. Barium also activated at least one class of potassium channels observed in excised membrane patches, whole blocking others. The blocking action may have masked and hindered detection of the stimulatory action of barium in other systems.

  17. The fluoroscopic barium enema in colonic polyp detection.

    Science.gov (United States)

    Teefey, S A; Carlson, H C

    1983-12-01

    The results of 1,500 barium enema studies done by vigorous manual palpation under fluoroscopy were reviewed to determine the adequacy of this technique in detecting polyps above the proctoscopic level. Of the 1,500 patients examined, 103 (7%) were diagnosed radiographically as having a total of 149 polyps. Polyps were found at proctoscopy in about 10% of the 1,500 patients. Colonoscopy or surgery was performed on 35 of the 103 patients. Of the 52 polyps discovered during these procedures, only three were missed at fluoroscopic barium enema study, a false-negative rate of 6%. Fourteen patients whose barium enemas initially were reported as negative for polyps or neoplasia had colonoscopy. Two of the 14 patients had positive findings, for a true-negative rate of 86%. If the detection rate of 7% found at barium enema, taking into account an overlap of 10%, is combined with the rate of 7.5% found at proctoscopy, a frequency of about 14% emerges in detecting polyps in the rectum and in the colon. Thus, the fluoroscopic barium enema when combined with proctoscopy is a sensitive method in the detection of colorectal polyps. In addition, it has the advantage of rapid execution and relatively low cost.

  18. Lanthanum doped BiFeO{sub 3} powders: Syntheses and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Garcia, F. [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro Amazonas - Itabira-MG, CEP 35900-373 (Brazil); Riccardi, C.S. [Laboratorio Interdisciplinar em Ceramica, Departamento de Fisico-Quimica, Instituto de Quimica Universidade Estadual Paulista, Bairro: Quitandinha, CEP: 14800-900, Araraquara, SP (Brazil); Simoes, A.Z., E-mail: alezipo@yahoo.co [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro Amazonas - Itabira-MG, CEP 35900-373 (Brazil)

    2010-07-02

    A soft chemistry route was employed to fabricate single-phase lanthanum modified BiFeO{sub 3} (BFO) powders. Effects of lanthanum concentration on the phase formation, grain size and morphologies of BFO powders were systematically investigated. X-ray diffraction results indicated that perovskite phase have been synthesized at the temperature of 850 {sup o}C/2 h while infrared data indicates no traces of carbonate. Raman analysis reveals that lanthanum atom substitutes bismuth into the BFO site. A homogeneous size distribution of BFO powders was evidenced by scanning electron microscopy.

  19. Doping of ceria surfaces with lanthanum: a DFT + U study

    Energy Technology Data Exchange (ETDEWEB)

    Yeriskin, Irene; Nolan, Michael, E-mail: michael.nolan@tyndall.i [Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork (Ireland)

    2010-04-07

    In this paper we use density functional theory corrected for on-site Coulomb interactions (DFT + U) to study the defects formed in the ceria (111) and (110) surfaces doped with La. To describe consistently the defect formed with substitutional La{sup 3+} doping at a Ce{sup 4+} site we use DFT and DFT + U, with U = 5 eV for Ce 4f states and U = 7 eV for O 2p states. When La{sup 3+} substitutes on a Ce{sup 3+} site, an La{sub Ce}{sup '}+O{sub O}{sup .} defect state, with an oxygen hole, is formed at both surfaces, but only with the DFT + U approach. The formation energy of an oxygen vacancy in a structure with two La dopants in their most stable distribution is reduced over the undoped surfaces but remains positive. Formation of an oxygen vacancy results in the appearance of a reduced Ce{sup 3+} cation and a compensated oxygen hole, instead of compensation of both oxygen holes, which is typical of metal oxides doped with lower valence cations. We tentatively suggest that the key role in the formation of this unusual defect is played by cerium and arises from the ease with which cerium can be reduced, as compared to other metal oxides. Experimental confirmation of these results is suggested.

  20. Synthesis and Characterization of La, Sc, Yb and Nd co-doped Gadolinium doped Cerium (GDC) Composite Electrolyte for IT-SOFC

    Science.gov (United States)

    Damisih; Raharjo, Jarot; Masmui; Setya Aninda, Raffty; Ami Lestari, Novita

    2017-07-01

    Composite based on gadolinium doped cerium (GDC) co-doped Lanthanum (La), Scandium (Sc), Ytterbium (Yb) were investigated as electrolyte for solid oxide fuel cell (SOFC), namely GDC-La, GDC-Sc, GDC-Yb and GDC-Nd, respectively. The second co-doped La, Sc, Yb and Nd ensured the stability and high ionic conductivity of the GDC ceria-based electrolyte materials for SOFC. The GDC powder was synthesized via sol-gel technique. Then the La-GDC, Sc-GDC, Yb-GDC and GDC-Nd were subsequently prepared by mixing the GDC with La, Sc, Yb, and Nd respectively, through solid-state reaction in ballmill at 200rpm alumina balls. The composite electrolytes were then characterized in terms of its morphology, phase and thermal properties of the powders. Among the composite electrolytes investigated, GDC-Yb powder show higher purity and better dispersion than the others co-doped GDC. TGA analysis present that the addition of co-dopant led to improve thermal resistance and stability of solid electrolyte powders. The results confirm that GDC with co-dopant is promising alternative electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFC).

  1. 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

  2. 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

  3. 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.

  4. Durability of Alite-calcium Barium Sulphoaluminate Cement

    Institute of Scientific and Technical Information of China (English)

    LU Lingchao; LU Zeye; LIU Shiquan; WANG Shoude; CHENG Xin

    2009-01-01

    The durability of the cement was mainly studied.Under 1.0 MPa of hydraulic pressure for 8 hours,water could penetrate completely through the sample made by portland cement,but could not penetrate through that by alite-barium sulphoaluminate cement.Under the condition of freezing and thawing cycle,the loss ratio of compressive strength of the cement was only about 17.3%at curing 28 d ages,but the loss of portland cement was as high as 29.5%.Alite-calcium bar-ium sulphoaluminate cement also has an excellent resistance to sulfate attack.The coefficients of resistance to sulfate attack of the cement exceeded 1.0.Meanwhile,the composition and microstructure of the hardened paste of alite-calcium barium sulphoaluminate cement were analyzed by XRD and SEM.

  5. Barium-borate-flyash glasses: As radiation shielding materials

    Science.gov (United States)

    Singh, Sukhpal; Kumar, Ashok; Singh, Devinder; Thind, Kulwant Singh; Mudahar, Gurmel S.

    2008-01-01

    The attenuation coefficients of barium-borate-flyash glasses have been measured for γ-ray photon energies of 356, 662, 1173 and 1332 keV using narrow beam transmission geometry. The photon beam was highly collimated and overall scatter acceptance angle was less than 3°. Our results have an uncertainty of less than 3%. These coefficients were then used to obtain the values of mean free path (mfp), effective atomic number and electron density. Good agreements have been observed between experimental and theoretical values of these parameters. From the studies of the obtained results it is reported here that from the shielding point of view the barium-borate-flyash glasses are better shields to γ-radiations in comparison to the standard radiation shielding concretes and also to the ordinary barium-borate glasses.

  6. Deoxidation Behavior of Alloys Bearing Barium in Molten Steel

    Institute of Scientific and Technical Information of China (English)

    LI Yang; JIANG Zhou-hua; JIANG Mao-fa; WANG Jun-wen; GU Wen-bing

    2003-01-01

    The deoxidation behaviors of alloys bearing barium in pipe steel were researched with MgO crucible under argon atmosphere in MoSi2 furnace at 1 873 K. The total oxygen contents of molten steel, the distribution, size and morphology of deoxidation products in the steel were surveyed. The metamorphic mechanism for deoxidation products of alloy bearing barium was also discussed. The results show that applying alloy bearing barium to the pipe steel, very low total oxygen contents can be obtained, and deoxidation products, which easily float up from molten steel, can be changed into globular shape and uniformly distributed in steel. The equilibrium time of total oxygen is about 25 min, and the terminal total oxygen contents range from 0.002 0 % to 0.002 2 % after treating with SiCa wire. The best deoxidizers are SiAlBaCa and SiAlBaCaSr.

  7. Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Dong Rip, E-mail: dongrip@hanyang.ac.kr [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-06-15

    Graphical abstract: - Highlights: • Cerium oxide nanorods were uniformly grown on diverse substrates. • Changes in growth conditions led to morphology evolution of cerium oxide nanostructures. • The grown cerium oxide nanostructures were single or poly crystalline. • Direct growth of cerium oxide nanorods made the diverse substrates superhydrophobic and anti-corrosive without any surface modifiers. - Abstract: Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields.

  8. 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.

  9. 75 FR 36629 - Barium Chloride From the People's Republic of China: Continuation of Antidumping Duty Order

    Science.gov (United States)

    2010-06-28

    ... International Trade Administration Barium Chloride From the People's Republic of China: Continuation of... China: Final Results of Expedited Third Sunset Review of Antidumping Duty Order, 74 FR 55814 (October 29... Barium Chloride From China, 75 FR 33824 (June 15, 2010), and Barium Chloride from China (Inv. No....

  10. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  11. Photoionization and Photoelectric Loading of Barium Ion Traps

    CERN Document Server

    Steele, A V; Churchill, L R; Griffin, P F

    2007-01-01

    Simple and effective techniques for loading barium ions into linear Paul traps are demonstrated. Two-step photoionization of neutral barium is achieved using a weak intercombination line (6s2 1S0 6s6p 3P1, 791 nm) followed by excitation above the ionization threshold using a nitrogen gas laser (337 nm). Isotopic selectivity is achieved by using a near Doppler-free geometry for excitation of the triplet 6s6p 3P1 state. Additionally, we report a particularly simple and efficient trap loading technique that employs an in-expensive UV epoxy curing lamp to generate photoelectrons.

  12. Esophageal intramural pseudodiverticulosis characterized by barium esophagography: a case report

    LENUS (Irish Health Repository)

    O'Connor, Owen J

    2010-05-21

    Abstract Introduction Esophageal intramural pseudodiverticulosis is a rare condition characterized by the dilatation of the submucosal glands. Case presentation We present a case of esophageal intramural pseudodiverticulosis in a 72-year-old Caucasian man who presented with dysphagia and with a background history of alcohol abuse. An upper gastrointestinal endoscopy of our patient showed an esophageal stricture with abnormal mucosal appearances, but no malignant cells were seen at biopsy. Appearances on a barium esophagram were pathognomonic for esophageal intramural pseudodiverticulosis. Conclusion We demonstrate the enduring usefulness of barium esophagography in the characterization of abnormal mucosal appearances at endoscopy.

  13. Effects of Cerium Doping at Ti Sites and Europium Doping at Ba Sites on Dielectric Properties of BaTiO3 Ceramics

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Two special rare earth elements cerium and europium were chosen to conduct chemical modification of the BaTiO3 structure. The cold-pressing ceramic processing technique was used to prepare barium titanate ceramics doped with Ce at Ti sites and with Eu at Ba sites on the base of formulas Ba(Ti1-xCex)O3(x=0.05, 0.10)(CBT) and(Ba1-yEuy)Ti1-y/8O3(y=0.05, 0.10)(EBT). Associated with structures and microstructures, the effects of cerium and europium doping on dielectric properties of BaTiO3 ceramics were discussed. The CBT ceramics exhibit a pseudo-cubic perovskite structure, while the EBT ceramics exhibit a tetragonal perovskite structure with the exception of the existence of a small percentage of the Eu2Ti2O7 phase. The Curie peak of BaTiO3 shifts towards room temperature at rates of 3 ℃/mol Ce atoms and 10 ℃/mol Eu atoms(Eu≤5%), respectively. Compared with the CBT ceramics, the EBT ceramics show significant advantages, such as a narrow fine grain size distribution(1 μm), a lower porosity and a higher density(5.85 g/cm3), more stable dielectric-temperature dependence(ε'=1600-1800 at t<50 ℃) and a lower dissipation factor(<0.05). The stability of dielectric constant with frequency in BaTiO3 can extend to 107 Hz due to Ce and Eu doping.

  14. Inhibition of the cytotoxicity of pelagia noctiluca Venom by lanthanum sulfate

    Directory of Open Access Journals (Sweden)

    G.L. Mariottini

    2010-01-01

    Full Text Available Abstract Cnidarians exert a meaningful influence on human activities and healyh being able to produce several local and systemic symptoms on humans. Mediterranean jellyfish are scarcely poisonous, but during outbreaks the impact of some of them, such as the Scyphomedusa Pelagia noctiluca, is noteworthy. As some compounds containing lanthanum ions could act as protective agents, the protection of lanthanum sulfate was evaluated on cultured L929 cells treated with three doses (120,000 nematocysts (N/ml, 240,000 N/ml and 480,000 N/ml of jellyfish crude venom. The protection was effective against all considered doses of crude venom and showed the maximun efficacy after preincubation of cells with 10-5M lanthanum sulfate. These results indicate that lanthanum sulfate could be an useful component in preparations devoted to struggle the cutaneous and systemic effects consequent to Pelagia noctiluca stings.

  15. 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.

  16. Hydrophilic block copolymer-directed growth of lanthanum hydroxide nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Bouyer, F.; Sanson, N.; Gerardin, C. [Laboratoire de Materiaux Catalytiques et Catalyse en Chimie Organique, UMR 5618 CNRS-ENSCM-UM1, FR 1878, Institut Gerhardt, 34 - Montpellier (France); Destarac, M. [Centre de Recherches Rhodia Aubervilliers, 93 - Aubervilliers (France)

    2006-03-15

    Stable hairy lanthanum hydroxide nano-particles were synthesized in water by performing hydrolysis and condensation reactions of lanthanum cations in the presence of double hydrophilic poly-acrylic acid-b-polyacrylamide block copolymers (PAA-b-PAM). In the first step, the addition of asymmetric PAA-b-PAM copolymers (M{sub w,PAA} {<=} M{sub w,PAM}) to lanthanum salt solutions, both at pH = 5.5, induces the formation of monodispersed micellar aggregates, which are predominantly isotropic. The core of the hybrid aggregates is constituted of a lanthanum polyacrylate complex whose formation is due to bidentate coordination bonding between La{sup 3+} and acrylate groups, as shown by ATR-FTIR experiments and pH measurements. The size of the micellar aggregates depends on the molecular weight of the copolymer but is independent of the copolymer to metal ratio in solution. In the second step, the hydrolysis of lanthanum ions is induced by addition of a strong base such as sodium hydroxide. Either flocculated suspensions or stable anisotropic or spherical nano-particles of lanthanum hydrolysis products were obtained depending on the metal complexation ratio [acrylate]/[La]. The variation of that parameter also enables the control of the size of the core-corona nano-particles obtained by lanthanum hydroxylation. The asymmetry degree of the copolymer was shown to influence both the size and the shape of the particles. Elongated particles with a high aspect ratio, up to 10, were obtained with very asymmetric copolymers (M{sub w,PAM}/M{sub w,PAA}{>=}10) while shorter rice grain-like particles were obtained with a less asymmetric copolymer. The asymmetry degree also influences the value of the critical metal complexation degree required to obtain stable colloidal suspensions of polymer-stabilized lanthanum hydroxide. (authors)

  17. Cr(VI) Adsorption on Red Mud Modified by Lanthanum: Performance, Kinetics and Mechanisms

    OpenAIRE

    Cui, You-Wei; Li,Jie; Du, Zhao-Fu; Peng, Yong-Zhen

    2016-01-01

    Water pollution caused by the highly toxic metal hexavalent chromium (Cr(VI)) creates significant human health and ecological risks. In this study, a novel adsorbent was used to treat Cr(VI)-containing wastewater; the adsorbent was prepared using red mud (RM) generated from the alumina production industry and the rare earth element lanthanum. This study explored adsorption performance, kinetics, and mechanisms. Results showed that the adsorption kinetics of the RM modified by lanthanum (La-RM...

  18. Dynamic compressive behavior and constitutive relations of lanthanum metal

    Institute of Scientific and Technical Information of China (English)

    WANG Huanran; CAI Canyua; CHEN Danian; MA Dongfang; DENG Gaotao

    2012-01-01

    The dynamic compressive behavior and constitutive relations of Lanthanum (La) metal was determined by using the first compression in split Hopkinson pressure bar (SHPB) tests at different strain rates and temperatures.The constitutive relation of La metal determined in a certain range of strains was employed and adjusted in numerically simulating large deformations of La metal spEcimens generated by multi-compression in SHPB tests and recorded by a high-speed camera.The dynamic compressive behavior and constitutive relations of La metal under multiple SHPB tests loading was also revealed.The results of scanning electron microscope (SEM) investigation of the recovered La metal specimens for typical tests showed that there was a variety of deformation microstructures depending on strain rate,temperature and stress state.

  19. Electrochemical Preparation and Characterization of Lanthanum Hexacyanoferrate Modified Electrode

    Institute of Scientific and Technical Information of China (English)

    吴萍; 蔡称心

    2005-01-01

    An electroactive polynuclear inorganic compound of rare earth metal hexacyanoferrate, lanthanum hexacyanoferrate (LaHCF), was prepared by electrochemical deposition on the surface of a glassy carbon electrode with a potential cycling procedure. The cyclic voltammogram of LaHCF exhibits a pair of well-defined redox peaks with the formal potential of 208 mV (vs. SCE) at a scan rate of 100 mV/s in 0.2 mol/L NaCl solution and the redox peak currents increase linearly with the square root of the scan rate up to 1000 mV/s. The effects of the concentration of supporting electrolyte on the electrochemical characteristics of LaHCF were studied by voltammetry. LaHCF was also characterizated by scanning electron microscope (SEM), FTIR and XPS techniques.

  20. Hydrothermal synthesis and dielectric properties of lanthanum titanate ceramics

    Institute of Scientific and Technical Information of China (English)

    DENG Yuan; NAN Ce-wen

    2005-01-01

    Lanthanum titanate (La2/3TiO3) powders were synthesized by hydrothermal method based on the reaction of TiO2, La(NO3 )3 and KOH at 160 ℃ for 24 h followed by the treatment of acidification. The microstructure,morphology and dielectric properties were investigated by using X-ray diffraction, scanning electron microscope,transmission electron microscope and impedance method. The results show that the La2/3 TiO3 particles consist of nearly homogenous and lamellar grains. The particles can be sintered into porous ceramics above 1 150 ℃. The dielectric properties of La2/3 TiO3 show that both the dielectric constant and the dielectric loss tangent decrease with the increase of frequency.

  1. Aging Effect on Lanthanum Doped Ferroelectric Lead Titanate Ceramics

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Ferroelectric devices are widely applied in many fields, such as energy conversion and communication. The aging effect in ferroelectric materials plays a central role in the reliability of the related equipments. But it is very difficult to understand the origin of aging effect in ferroelectrics because these materials possess different defects and exhibit various aging behavior. The reverse transition temperature in lead titanate doped with lanthanum increases during aging at ferroelectric phase was reported. It is well known that lattice defects, such as vacancies and solute atoms, are ubiquitous in crystalline solids. These point defects affect physical properties in ferroelectrics significantly. The abnormal increase of the reverse transition temperature was discussed in terms of diffusion of point defects during aging. Dielectric performance in the material after aging was measured and discussed as well.

  2. Highly transparent ytterbium doped yttrium lanthanum oxide ceramics

    Institute of Scientific and Technical Information of China (English)

    M.Ivanov; Yu.Kopylov; V.Kravchenko; 李江; A.Medvedev; 潘裕柏

    2014-01-01

    To prepare ytterbium doped lanthania yttria nanopowder a method of laser evaporation of mixed oxides was used. After calcinations of the powder at 1200 °C a pure single-phase solid solution Yb3+:(LaxY1-x)2O3 was formed in the nanoparticles. Influence of lanthanum oxide as an isovalent additive on the yttria structure was investigated. The lanthanium ions were proved to be a good aid to sinter yttria ceramics doped with Yb3+at moderate temperatures about 1650 °С. The ceramics with relative density higher than 99.99%and grain size about 40 µm were fabricated. Full transmittance of 1.8 mm thick Yb0.11La0.23Y1.66O3 ceramics reached 82.5%at 800 nm. This material could be a good gain medium for ytterbium high power pulse lasers.

  3. Infrared emission from holmium doped gallium lanthanum sulphide glass

    Science.gov (United States)

    Schweizer, T.; Samson, B. N.; Hector, J. R.; Brocklesby, W. S.; Hewak, D. W.; Payne, D. N.

    1999-08-01

    Infrared emission at 1.2, 1.25, 1.67, 2.0, 2.2, 2.9, 3.9, and 4.9 μm is measured in holmium (Ho 3+) doped gallium lanthanum sulphide (GLS) glass. Branching ratios, radiative quantum efficiencies, and emission cross-sections are calculated from lifetime, absorption, and emission measurements using Judd-Ofelt analysis and the Füchtbauer-Ladenburg equation. The fluorescence band at 3.9 μm coincides with an atmospheric transmission window and the fluorescence band at 4.9 μm overlaps with the fundamental absorption of carbon monoxide, making the glass a potential fibre laser source for remote sensing and gas sensing applications. This is the first time this latter transition has been reported in any holmium doped host.

  4. Chemical and Thermal Expansion of Calcium-Doped Lanthanum Chromite

    Science.gov (United States)

    Williford, R. E.; Armstrong, T. R.; Gale, J. D.

    2000-02-01

    Atomistic free-energy minimization techniques were used to simulate three simultaneous volumetric shrinkage/expansion phenomena in calcium-doped lanthanum chromite solid oxide fuel cell (SOFC) interconnect materials. Four sets of interatomic potentials were developed and tested over the temperature range 0-1273 K. The predicted unit-cell volumes, elastic properties, volumetric shrinkage due to A-site doping of the ABO3 perovskite (La1-xCax)CrO3, defect-induced volumetric expansion due to reducing atmospheres, and thermal expansion were in reasonable agreement with experiment, though not all concurrently with a single set of potentials. Potentials based either on simple oxides or on partial charge models appeared to give the best overall predictions. Additional experimental data are needed to improve the potentials.

  5. Phosphate modulated luminescence in lanthanum vanadate nanorods- Catechin, polyphenolic ligand

    Science.gov (United States)

    Tamilmani, Vairapperumal; Nair, Balachandran Unni; Sreeram, Kalarical Janardhanan

    2017-08-01

    Rare earth orthovanadates and phosphates offer a very high opportunity for fabrication of nanoscale devices that exploit their luminescence properties. Optimization of luminescence by way of modulation of size, shape, structure, and morphology has been an area of study for several researchers. There has been a debate as to whether doped orthophosphate or orthovanadate is better luminescent material as both are chemically similar. It has been reported earlier that catechin hydrate can play the role of a structure director and thus influence the luminescence properties of orthovanadates. In this work, a catechin modulated the synthesis of Eu-doped lanthanum orthophosphate by phosphate substitution into vanadate host lattice is reported. A mechanistic understanding of the luminescence changes in LaMO4 has been proposed. During the substitution of V with P, catechin modulates the structure between 1D nanorods and nanowires. The host crystal structure, shape, and size influence the luminescence properties in doped LaMO4.

  6. Features of the Real Structure of Lanthanum Hexaboride Polycrystalline

    Institute of Scientific and Technical Information of China (English)

    郑树起; 闵光辉; 邹增大; 于普涟; 韩建德; Y. B. Paderno

    2001-01-01

    The microstructure of lanthanum hexaboride (LaB6) polycrystalline has been studied by using transmission electron microscopy. This shows that the ideal LaB6 polycrystalline can be obtained by sintering ingots at the temperature of 2273 K for a holding time of 120min in Ar pressure of 800Torr, where the ingots are formed by pressing LaB6 powder at room temperature at a pressure of 0.4-0.5 GPa. The particles in LaB6 polycrystalline hardly bind; there are only a few pores at the joint parts of three particles and a few impurities exist in some pores. The sintering process for fabricating LaB6 polycrystalline is analysed and the formation of the pore and the impurities are studied from the point of surface tension.

  7. The management of hyperphosphatemia by lanthanum carbonate in chronic kidney disease patients.

    Science.gov (United States)

    Shigematsu, Takashi; Nakashima, Yuri; Ohya, Masaki; Tatsuta, Koichi; Koreeda, Daisuke; Yoshimoto, Wataru; Yamanaka, Shintaro; Sakaguchi, Toshifumi; Hanba, Yoshiyuki; Mima, Toru; Negi, Shigeo

    2012-01-01

    Hyperphosphatemia has been shown to be involved not only in the onset and progression of secondary hyperparathyroidism but also in vascular calcification. In addition, it influences the clinical course of patients with chronic kidney disease. Phosphate (Pi) binder is required in the management of hyperparaphosphatemia, because dietary Pi restriction and Pi removal by hemodialysis alone are insufficient. Lanthanum carbonate, a powerful Pi binder, has a similar effect to aluminum hydroxide in reducing serum Pi levels. As it is excreted via the liver, lanthanum carbonate has an advantage in patients with renal failure. The effect of lanthanum carbonate on serum Pi levels is almost two times higher than that of calcium (Ca) carbonate, which is commonly used. Lanthanum carbonate and Ca carbonate have an additive effect. Worldwide, there is 6 years worth of clinical treatment data on lanthanum carbonate; however, we have 3 years of clinical use in Japanese patients with hyperphosphatemia. No serious side effects have been reported. However, the most important concern is bone toxicity, which has been observed with use of aluminum hydroxide. For this study, clinical research involved analysis of bone biopsies. Although osteomalacia is the most noticeable side effect, this was not observed. Both the high- and the low-turnover bone disease concentrated into a normal bone turnover state. However, as the authors have less than 10 years' clinical experience with lanthanum carbonate, patients should be monitored carefully. In addition, it is necessary to demonstrate whether potent treatment effects on hyperphosphatemia improve the long-term outcome.

  8. Infrared spectra of oxygen-rich yttrium and lanthanum dioxygen/ozonide complexes in solid argon.

    Science.gov (United States)

    Gong, Yu; Ding, Chuanfan; Zhou, Mingfei

    2009-07-30

    The reactions of yttrium and lanthanum atoms with O(2) have been reinvestigated using matrix isolation infrared spectroscopy and theoretical calculations. The ground-state yttrium and lanthanum atoms react with O(2) to produce the inserted yttrium and lanthanum dioxide molecules as the initial products. The yttrium dioxide molecule interacts spontaneously with additional O(2) molecules to form the oxygen-rich OY(eta(2)-O(3)) complex and possibly the (eta(2)-O(2))Y(eta(2)-O(3))(2) complexes upon sample annealing, which can be regarded as the side-on bonded yttrium monoxide ozonide complex and the superoxo yttrium bisozonide complex, respectively. Visible irradiation induces the isomerization of the OY(eta(2)-O(3)) complex to the superoxo yttrium peroxide Y(eta(2)-O(2))(2) isomer, in which both the superoxo and peroxo ligands are side-on bonded to the yttrium center. The lanthanum dioxide molecule reacts with additional O(2) molecules to form the lanthanum dioxide-dioxygen complex with planar C(2v) symmetry, which rearranges to the lanthanum monoxide ozonide complex, OLa(eta(2)-O(3)), under near-infrared excitation.

  9. Borohydride electro-oxidation by Ag-doped lanthanum chromites

    Indian Academy of Sciences (India)

    S Suresh Balaji; A Usha; V V Giridhar

    2014-05-01

    The electrocatalytic activity of Ag-doped lanthanum chromites electrode materials viz., LaCr0.4Ag0.6O3 and LaCr0.7Ag0.3O3 prepared by decomposing the precursor complex is studied. Pure LaCrO3 is synthesized by combustion route using oxalic acid as a fuel. The decomposition behaviour of the assynthesized powder obtained in the latter method is characterized by TGA-DTA and XRD. Both the precursor complex and the as-synthesized powder are calcined at 900°C for 7 and 10 h, respectively. XRD of the final product after calcinations indicated the formation of perovskite phase with minor amounts of impurity phases of component oxides in the Ag-doped lanthanum chromites and pure perovskite phase in the undoped one. The surface morphology of the perovskites is studied by SEM. The electrocatalytic activity of the perovskite powders for borohydride oxidation is studied by using cyclic voltammetry (CV) at a catalyst loading of 0.7 mgcm−2 for both Ag-doped and undoped LaCrO3 coated on glassy carbon substrate. Calibration plots are obtained by plotting the anodic peak current versus concentration of borohydride in the range of 20-100 mM. The sensitivities of the three perovskites towards borohydride oxidation indicated that LaCr0.4Ag0.6O3 is the best among all the perovskites studied giving a value of 1.395 A/mM.

  10. Lanthanum chromite colloidal processing; Processamento coloidal de cromito de lantanio

    Energy Technology Data Exchange (ETDEWEB)

    Setz, Luiz Fernando Grespan

    2009-07-01

    Lanthanum chromite (LaCrO{sub 3}) is currently the most studied material for applications such as solid oxide fuel cell inter connector (HTSOFC). The complexity of microstructures and geometries of HTSOFC devices, require a precise control of processing parameters to get the desired combination of properties and this, the use of techniques involving concentrated ceramic slips conformation are appropriate, therefore, is well controlled, assist in obtaining homogeneous parts, reproductive and complex geometries. Thus, studies involving the surface chemistry, the stability conditions and slips flow behaviour in the forming conditions, provide important elements for processes control in the inter connectors manufacture, where more applied settings have slots and channels for the gases passage. Thus, surface chemistry, stability and rheological behaviour of strontium and cobalt doped LaCrO{sub 3} (La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3}) slips prepared with ethanol and water, were studied. The doped lanthanum chromite was produced by combustion synthesis in the IPEN/SP labs. The influence of parameters: p H (water), dispersant concentration, homogenization times and conditions, solid concentration, different ratios binder:plasticizer in the stability and the flow behavior of ceramic suspensions prepared were evaluated. The La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3} products obtained by casting aqueous slips in a plaster mould, using alkaline p H and anionic polyelectrolyte and tapes obtained by using ethanol as a dispersant medium, after sintering at 1600 deg C/4h presented theoretical density > 94%, suitable for use as HTSOFC inter connector. (author)

  11. Lanthanum chromite colloidal processing; Processamento coloidal de cromito de lantanio

    Energy Technology Data Exchange (ETDEWEB)

    Setz, Luiz Fernando Grespan

    2009-07-01

    Lanthanum chromite (LaCrO{sub 3}) is currently the most studied material for applications such as solid oxide fuel cell inter connector (HTSOFC). The complexity of microstructures and geometries of HTSOFC devices, require a precise control of processing parameters to get the desired combination of properties and this, the use of techniques involving concentrated ceramic slips conformation are appropriate, therefore, is well controlled, assist in obtaining homogeneous parts, reproductive and complex geometries. Thus, studies involving the surface chemistry, the stability conditions and slips flow behaviour in the forming conditions, provide important elements for processes control in the inter connectors manufacture, where more applied settings have slots and channels for the gases passage. Thus, surface chemistry, stability and rheological behaviour of strontium and cobalt doped LaCrO{sub 3} (La){sub 0.80}Sr{sub 0.}2{sub 0}Cr{sub 0.92}Co{sub 0.08}O{sub 3}) slips prepared with ethanol and water, were studied. The doped lanthanum chromite was produced by combustion synthesis in the IPEN/SP labs. The influence of parameters: pH (water), dispersant concentration, homogenization times and conditions, solid concentration, different ratios binder:plasticizer in the stability and the flow behavior of ceramic suspensions prepared were evaluated. The La){sub 0.80}Sr{sub 0.}2{sub 0}Cr{sub 0.92}Co{sub 0.08}O{sub 3} products obtained by casting aqueous slips in a plaster mould, using alkaline pH and anionic polyelectrolyte and tapes obtained by using ethanol as a dispersant medium, after sintering at 1600 degree C/4 hours presented theoretical density > 94%, suitable for use as HTSOFC inter connector. (author)

  12. Phosphate binding therapy in dialysis patients: focus on lanthanum carbonate

    Directory of Open Access Journals (Sweden)

    Ismail A Mohammed

    2008-11-01

    Full Text Available Ismail A Mohammed, Alastair J HutchisonManchester Institute of Nephrology and Transplantation, Manchester Royal Infirmary, Oxford Road, Manchester, UKAbstract: Hyperphosphatemia is an inevitable consequence of end stage chronic kidney disease and is present in the majority of dialysis patients. Recent observational data has associated hyperphosphatemia with increased cardiovascular mortality among dialysis patients. Dietary restriction of phosphate and current dialysis prescription practices are not enough to maintain serum phosphate levels within the recommended range so that the majority of dialysis patients require oral phosphate binders. Unfortunately, conventional phosphate binders are not reliably effective and are associated with a range of limitations and side effects. Aluminium-containing agents are highly efficient but no longer widely used because of well established and proven toxicity. Calcium based salts are inexpensive, effective and most widely used but there is now concern about their association with hypercalcemia and vascular calcification. Sevelamer hydrochloride is associated with fewer adverse effects, but a large pill burden and high cost are limiting factors to its wider use. In addition, the efficacy of sevelamer as a monotherapy in lowering phosphate to target levels in severe hyperphosphatemia remains debatable. Lanthanum carbonate is a promising new non-aluminium, calcium-free phosphate binder. Preclinical and clinical studies have demonstrated a good safety profile, and it appears well tolerated and effective in reducing phosphate levels in dialysis patients. Its identified adverse events are apparently mild to moderate in severity and mostly GI related. It appears to be effective as a monotherapy, with a reduced pill burden, but like sevelamer, it is significantly more expensive than calcium-based binders. Data on its safety profile over 6 years of treatment are now available.Keywords: hyperphosphatemia, lanthanum

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

    Science.gov (United States)

    Barrios, Ana Cecilia; Rico, Cyren M; Trujillo-Reyes, Jesica; Medina-Velo, Illya A; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

    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 210days in potting soil amended with uncoated and citric acid coated cerium oxide nanoparticles (nCeO2, CA+nCeO2) bulk cerium oxide (bCeO2), and cerium acetate (CeAc). Millipore water (MPW), and citric acid (CA) were used as controls. Physiological and biochemical parameters were measured. At 500mg/kg, both the uncoated and CA+nCeO2 increased shoot length by ~9 and ~13%, respectively, while bCeO2 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+nCeO2 at 250mg/kg, but reduced by bCeO2 at 62.5mg/kg, compared with MPW. At 250 and 500mg/kg, nCeO2 increased Ce in roots by 10 and 7 times, compared to CA+nCeO2, but none of the treatments affected the Ce concentration in above ground tissues. Neither nCeO2 nor CA+nCeO2 affected the homeostasis of nutrient elements in roots, stems, and leaves or catalase and ascorbate peroxidase in leaves. CeAc at 62.5 and 125mg/kg increased B (81%) and Fe (174%) in roots, while at 250 and 500mg/kg, increased Ca in stems (84% and 86%, respectively). On the other hand, bCeO2 at 62.5 increased Zn (152%) but reduced P (80%) in stems. Only nCeO2 at 62.5mg/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 nCeO2 on tomato plants. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. 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.

  15. Barium Ferrite Films Grown By Pulsed Laser Ablation

    NARCIS (Netherlands)

    Lisfi, A.; Lodder, J.C.; Haan, de P.; Roesthuis, F.J.G.

    1998-01-01

    Abstract available only. It is known that barium ferrite (BaFe12019) can grow with perpendicular anisotropy on A1203 a single crystal substrate,' but also on an amorphous substrate by using a ZnO buffer.2 Because of its large magnetic anisotropy which can easily overcome the shape anisotropy of the

  16. The Kerr nonlinearity of the beta-barium borate crystal

    DEFF Research Database (Denmark)

    Bache, Morten; Guo, Hairun; Zhou, Binbin

    2013-01-01

    A popular crystal for ultrafast cascading experiments is beta-barium-borate (β-BaB2O4, BBO). It has a decent quadratic nonlinear coefficient, and because the crystal is anisotropie it can be birefringence phase-matched for type I (oo → e) second-harmonic generation (SHG). For femtosecond...

  17. Magnetoelastic coupling in epitaxial cobalt ferrite/barium titanate heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gräfe, Joachim; Welke, Martin [Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstraße 2, 04103 Leipzig (Germany); Bern, Francis; Ziese, Michael [Institut für Experimentelle Physik II, Universität Leipzig, Linnéstraße 5, 04103 Leipzig (Germany); Denecke, Reinhard, E-mail: denecke@uni-leipzig.de [Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstraße 2, 04103 Leipzig (Germany)

    2013-08-15

    Ultra-thin cobalt ferrite films have been synthesised on ferroelectric barium titanate crystals. The cobalt ferrite films exhibit a magnetic response to strain induced by structural changes in the barium titanate substrate, suggesting a pathway to multiferroic coupling. These structural changes are achieved by heating through the phase transition temperatures of barium titanate. In addition the ferromagnetic signal of the substrate itself is taken into account, addressing the influence of impurities or defects in the substrate. The cobalt ferrite/barium titanate heterostructure is a suitable oxidic platform for future magnetoelectric applications with an established ferroelectric substrate and widely tuneable magnetic properties by changing the transition metal in the ferrite film. - Highlights: ► Ultra-thin CoFe{sub 2}O{sub 4} films grown on ferroelectric BaTiO{sub 3} crystals by PLD. ► Magnetic response to structural changes of BaTiO{sub 3} at transition temperatures. ► Significant magneto-elastic coupling of in-plane magnetisation in SQUID experiments. ► Clear distinction between contribution by BaTiO{sub 3} substrate and by CoFe{sub 2}O{sub 4} film.

  18. Heavy ion recoil spectrometry of barium strontium titanate films

    Science.gov (United States)

    Stannard, W. B.; Johnston, P. N.; Walker, S. R.; Bubb, I. F.; Scott, J. F.; Cohen, D. D.; Dytlewski, N.; Martin, J. W.

    1995-05-01

    Thin films of barium strontium titanate have been analysed using heavy ion recoil spectrometry with 77 and 98 MeV 127I ions at the new heavy ion recoil facility at ANSTO, Lucas Heights. New calibration procedures have been developed for quantitative analysis. Energy spectra for each of the elements present reveal interdiffusion that was not previously known.

  19. Excitation energies of barium oxide bands measured in flames

    NARCIS (Netherlands)

    Hurk, J. van der; Hollander, Tj.; Alkemade, C.T.J.

    1975-01-01

    Experiments are described that yield additional information about the excitation energy of visible barium oxide bands appearing in flames. Excitation energy differences are derived directly from the ratios of thermal band intensities as a function of temperature and agree with the value calculated f

  20. CNO and F abundances in the barium star HD 123396

    CERN Document Server

    Alves-Brito, Alan; Yong, David; Meléndez, Jorge; Vásquez, Sergio

    2011-01-01

    [Abridged] Barium stars are moderately rare chemically peculiar objects which are believed to be the result of the pollution of an otherwise normal star by material from an evolved companion on the asymptotic giant branch (AGB). We aim to derive carbon, nitrogen, oxygen, and fluorine abundances for the first time from infrared spectra of the barium red giant star HD 123396 to quantitatively test AGB nucleosynthesis models for producing barium stars via mass accretion. High-resolution and high S/N infrared spectra were obtained using the Phoenix spectrograph mounted at the Gemini South telescope. The abundances were obtained through spectrum synthesis of individual atomic and molecular lines, using the MOOG stellar line analysis program together with Kurucz's stellar atmosphere models. The analysis was classical, using 1D stellar models and spectral synthesis under the assumption of local thermodynamic equilibrium. We confirm that HD 123396 is a metal-deficient barium star ([Fe/H] = -1.05), with A(C) = 7.88, A...

  1. Barium titanate inverted opals-synthesis, characterization, and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Soten, I.; Miguez, H.; Yang, S.M.; Petrov, S.; Coombs, N.; Tetreault, N.; Ozin, G.A. [Toronto Univ., ON (Canada). Dept. of Chemistry; Matsuura, N.; Ruda, H.E. [Toronto Univ., ON (Canada). Dept. of Metallurgy and Materials Science

    2002-01-01

    The engineering of cubic or tetragonal polymorphs of nanocrystalline barium titanate inverted opals has been achieved by thermally induced transformations. Optical characterization demonstrated photonic crystal behavior of the opals. The tuning of the ferroelectric-paraelectric transition around the Curie temperature is shown in this paper. (orig.)

  2. Synthesis of Nanocrystalline Barium Ferrite in Ethanol/Water Media

    Institute of Scientific and Technical Information of China (English)

    M.Montazeri-Pour; A.Ataie

    2009-01-01

    Nanocrystalline particles of barium ferrite magnetic material have been prepared by co-precipitation route using aqueous and non-aqueous solutions of iron and barium chlorides with a Fe/Ba molar ratio of 11 and subsequent drying-annealing treatment. Water and ethanol/water mixture with volume ratio of 3:1 were used as solvents in the process. Coprecipitated powders were annealed at various temperatures for 1 h. FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), DTA/TGA (differential thermal analy-sis/thermogravimetric analysis) and SEM (scanning electron microscopy) techniques were used to evaluate powder particle characteristics. DTA/TGA results confirmed by those obtained from XRD indicated that the formation of barium ferrite occurs in sample synthesized in ethanol/water solution at a relatively low temperature of 631℃. Nano-size particles of barium ferrite with mean particle size of almost 75 and 100 nm were observed in the SEM micrographs of the samples synthesized in ethanol/water solution after annealing at 700 and 800℃ for 1 h, respectively.

  3. 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...

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Soil organic matter influences cerium translocation and physiological processes in kidney bean plants exposed to cerium oxide nanoparticles.

    Science.gov (United States)

    Majumdar, Sanghamitra; Peralta-Videa, Jose R; Trujillo-Reyes, Jesica; Sun, Youping; Barrios, Ana C; Niu, Genhua; Margez, Juan P Flores-; Gardea-Torresdey, Jorge L

    2016-11-01

    Soil organic matter plays a major role in determining the fate of the engineered nanomaterials (ENMs) in the soil matrix and effects on the residing plants. In this study, kidney bean plants were grown in soils varying in organic matter content and amended with 0-500mg/kg cerium oxide nanoparticles (nano-CeO2) under greenhouse condition. After 52days of exposure, cerium accumulation in tissues, plant growth and physiological parameters including photosynthetic pigments (chlorophylls and carotenoids), net photosynthesis rate, transpiration rate, and stomatal conductance were recorded. Additionally, catalase and ascorbate peroxidase activities were measured to evaluate oxidative stress in the tissues. The translocation factor of cerium in the nano-CeO2 exposed plants grown in organic matter enriched soil (OMES) was twice as the plants grown in low organic matter soil (LOMS). Although the leaf cover area increased by 65-111% with increasing nano-CeO2 concentration in LOMS, the effect on the physiological processes were inconsequential. In OMES leaves, exposure to 62.5-250mg/kg nano-CeO2 led to an enhancement in the transpiration rate and stomatal conductance, but to a simultaneous decrease in carotenoid contents by 25-28%. Chlorophyll a in the OMES leaves also decreased by 27 and 18% on exposure to 125 and 250mg/kg nano-CeO2. In addition, catalase activity increased in LOMS stems, and ascorbate peroxidase increased in OMES leaves of nano-CeO2 exposed plants, with respect to control. Thus, this study provides clear evidence that the properties of the complex soil matrix play decisive roles in determining the fate, bioavailability, and biological transport of ENMs in the environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. 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.

  10. 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.

  11. 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.

  12. Interactional effect of cerium and manganese on NO catalytic oxidation.

    Science.gov (United States)

    Liang, Yanli; Huang, Yufen; Zhang, Hailong; Lan, Li; Zhao, Ming; Gong, Maochu; Chen, Yaoqiang; Wang, Jianli

    2017-04-01

    To preferably catalyze the oxidation of NO to NO2 in diesel after-treatment system, a series of CeO2-MnO x composite oxides was supported on silica-alumina material by the co-impregnation method. The maximum conversion of NO of the catalyst with a Ce/Mn weight ratio of 5:5 was improved by around 40%, compared to the supported manganese-only or cerium-only sample. And its maximum reaction rate was 0.056 μmol g(-1) s(-1) at 250 °C at the gas hourly space velocity of 30,000 h(-1). The experimental results suggested that Ce-Mn solid solution was formed, which could modulate the valence state of cerium and manganese and exhibit great redox properties. Moreover, the strong interaction between ceria and manganese resulted in the largest desorption amount of strong chemical oxygen and oxygen vacancies, leading to the maximum O α area ratio of 62.26% from the O 1s result. These effective oxygen species could be continually transferred to the surface, leading to the best NO catalytic activity of 5Ce5Mn/SA catalyst. Graphical abstract.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. Removal of fluoride from fluoride-bering cerium sulfate solution by hydrous zirconium oxide

    Directory of Open Access Journals (Sweden)

    J. G. He

    2014-04-01

    Full Text Available In this paper the removal of fluoride from fluoride-bearing cerium sulfate solution by amorphous hydrous zirconium oxide was studied. The FTIR, SEM, EDS and UV-vis spectra show that fluoride is successfully adsorbed on hydrous zirconium oxide, and cerium exists as Ce4+ in solution. The study indicates that it is feasible to separate fluorine and cerium from fluorine-bearing rare earth sulfate solution using hydrous zirconium oxide, and eliminate the influence of fluoride on the extraction separation of rare earths.

  18. 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.

  19. Conversion to lanthanum carbonate monotherapy effectively controls serum phosphorus with a reduced tablet burden: a multicenter open-label study

    Directory of Open Access Journals (Sweden)

    Matalon Albert

    2011-09-01

    Full Text Available Abstract Background Lanthanum carbonate (FOSRENOL® is an effective, well-tolerated phosphate binder. The ability of lanthanum to reduce serum phosphorus levels to ≤5.5 mg/dL in patients with end-stage renal disease (ESRD was assessed in a clinical practice setting. Methods A 16-week, phase IV study enrolled 2763 patients at 223 US sites to evaluate the efficacy of lanthanum carbonate in controlling serum phosphorus in patients with ESRD, and patient and physician satisfaction with, and preference for, lanthanum carbonate after conversion from other phosphate-binder medications. Patients received lanthanum carbonate prescriptions from physicians. These prescriptions were filled at local pharmacies rather than obtaining medication at the clinical trial site. Changes from serum phosphorus baseline values were analyzed using paired t tests. Patient and physician preferences for lanthanum carbonate versus previous medications were assessed using binomial proportion tests. Satisfaction was analyzed using the McNemar test. Daily dose, tablet burden, and laboratory values including albumin-adjusted serum calcium, calcium × phosphorus product, and parathyroid hormone levels were secondary endpoints. Results Serum phosphorus control (≤5.5 mg/dL was effectively maintained in patients converting to lanthanum carbonate monotherapy; 41.6% of patients had controlled serum phosphate levels at 16 weeks. Patients and physicians expressed markedly higher satisfaction with lanthanum carbonate, and preferred lanthanum carbonate over previous medication. There were significant reductions in daily dose and daily tablet burden after conversion to lanthanum carbonate. Conclusions Serum phosphorus levels were effectively maintained in patients converted from other phosphate-binder medications to lanthanum carbonate, with increased satisfaction and reduced tablet burden. Trial Registration ClinicalTrials.gov: NCT0016012

  20. Lake responses following lanthanum-modified bentonite clay (Phoslock) application: an analysis of water column lanthanum data from 16 case study lakes

    NARCIS (Netherlands)

    Spears, B.M.; Lürling, M.F.L.L.W.; Yasseri, S.; Castro-Castellon, A.T.; Gibbs, M.; Meis, S.; McDonald, C.; McIntosh, J.; Sleep, D.; Oosterhout, van F.

    2013-01-01

    Phoslock is a lanthanum (La) modified bentonite clay that is being increasingly used as a geo-engineering tool for the control of legacy phosphorus (P) release from lake bed sediments to overlying waters. This study investigates the potential for negative ecological impacts from elevated La concentr

  1. Lake responses following lanthanum-modified bentonite clay (Phoslock) application: an analysis of water column lanthanum data from 16 case study lakes

    NARCIS (Netherlands)

    Spears, B.M.; Lürling, M.F.L.L.W.; Yasseri, S.; Castro-Castellon, A.T.; Gibbs, M.; Meis, S.; McDonald, C.; McIntosh, J.; Sleep, D.; Oosterhout, van F.

    2013-01-01

    Phoslock is a lanthanum (La) modified bentonite clay that is being increasingly used as a geo-engineering tool for the control of legacy phosphorus (P) release from lake bed sediments to overlying waters. This study investigates the potential for negative ecological impacts from elevated La

  2. Gas permeability of lanthanum oxycarbide targets for the SPES project

    Energy Technology Data Exchange (ETDEWEB)

    Biasetto, L., E-mail: lisa.biasetto@unipd.it [Università di Padova-Department DTG, Stradella San Nicola 3, I-36100 Vicenza (Italy); Laboratori Nazionali di Legnaro-INFN, V.le dell’Università 2, I-35020 Legnaro (PD) (Italy); Innocentini, M.D.M.; Chacon, W.S. [Curso de Engenharia Química, Universidade de Ribeirão Preto, 14096-900 Ribeirão Preto, SP (Brazil); Corradetti, S.; Carturan, S. [Laboratori Nazionali di Legnaro-INFN, V.le dell’Università 2, I-35020 Legnaro (PD) (Italy); Colombo, P. [Università di Padova, Department DII, via Marzolo 9, I-35131 Padova (Italy); Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Andrighetto, A. [Laboratori Nazionali di Legnaro-INFN, V.le dell’Università 2, I-35020 Legnaro (PD) (Italy)

    2013-09-15

    The creation of a porous matrix made of interconnected and permeable paths is a key step for the processing of optimized metal carbide targets in the SPES (Selective Production of Exotic Species) project. Unlike close or non-connected open pores, permeable pores link more efficiently the interior and the surface of target disks, and therefore facilitate the effusion and convection transport mechanisms for a faster extraction of exotic nuclei with short decay times. This work describes the analysis of the interconnected porosity of lanthanum oxycarbide targets through the evaluation of permeability coefficients obtained in argon flow experiments at room and high temperature. Samples were produced by the sacrificial template method using phenolic resin (PR) as source of carbon for the carbothermal reaction of lanthanum oxide, and different amounts of polymethilmetacrylate (PMMA) microbeads as template for the production of porosity. Results showed that conventional targets prepared without sacrificial templates displayed relatively high total porosity (45.6%), but very low permeability coefficients (k{sub 1} = 4.21 × 10{sup −17} m{sup 2} and k{sub 2} = 1.90 × 10{sup −15} m), comparable to other dense ceramic materials. The linear increase in total porosity from 64.8% to 88.9% achieved by the gradual increase of PMMA from 30% to 80 wt.% resulted in a remarkable increase of five orders of magnitude for k{sub 1} (2.36 × 10{sup −12} m{sup 2}) and eight orders for k{sub 2} (7.48 × 10{sup −7} m{sup 2}). The addition of sacrificial fillers was found to be much more efficient to create interconnected and permeable paths in the structure than the carbothermal reduction itself. Preliminary tests with argon flow up to 450 °C revealed that the porous matrix also became more permeable with the increase in the gas temperature due to thermal expansion effects, but the extent of this gain depended on the initial porosity level of the sample.

  3. Potentiometric measurement of polymer-membrane electrodes based on lanthanum

    Energy Technology Data Exchange (ETDEWEB)

    Saefurohman, Asep, E-mail: saefurohman.asep78@Gmail.com; Buchari,, E-mail: saefurohman.asep78@Gmail.com; Noviandri, Indra, E-mail: saefurohman.asep78@Gmail.com [Department of Chemistry, Bandung Institute of Technology (Indonesia); Syoni [Department of Metallurgy Engineering, Bandung Institute of Technology (Indonesia)

    2014-03-24

    Quantitative analysis of rare earth elements which are considered as the standard method that has a high accuracy, and detection limits achieved by the order of ppm is inductively coupled plasma atomic emission spectroscopy (ICPAES). But these tools are expensive and valuable analysis of the high cost of implementation. In this study be made and characterized selective electrode for the determination of rare earth ions is potentiometric. Membrane manufacturing techniques studied is based on immersion (liquid impregnated membrane) in PTFE 0.5 pore size. As ionophores to be used tri butyl phosphate (TBP) and bis(2-etylhexyl) hydrogen phosphate. There is no report previously that TBP used as ionophore in polymeric membrane based lanthanum. Some parameters that affect the performance of membrane electrode such as membrane composition, membrane thickness, and types of membrane materials studied in this research. Manufacturing of Ion Selective Electrodes (ISE) Lanthanum (La) by means of impregnation La membrane in TBP in kerosene solution has been done and showed performance for ISE-La. FTIR spectrum results for PTFE 0.5 pore size which impregnated in TBP and PTFE blank showed difference of spectra in the top 1257 cm{sup −1}, 1031 cm{sup −1} and 794.7 cm{sup −1} for P=O stretching and stretching POC from group −OP =O. The result showed shift wave number for P =O stretching of the cluster (−OP=O) in PTFE-TBP mixture that is at the peak of 1230 cm{sup −1} indicated that no interaction bond between hydroxyl group of molecules with molecular clusters fosforil of TBP or R{sub 3}P = O. The membrane had stable responses in pH range between 1 and 9. Good responses were obtained using 10{sup −3} M La(III) internal solution, which produced relatively high potential. ISE-La showed relatively good performances. The electrode had a response time of 29±4.5 second and could be use for 50 days. The linear range was between 10{sup −5} and 10{sup −1} M.

  4. Regeneration of barium carbonate from barium sulphide in a pilot-scale bubbling column reactor and utilization for acid mine drainage

    CSIR Research Space (South Africa)

    Mulopo, J

    2012-01-01

    Full Text Available Batch regeneration of barium carbonate (BaCO3) from barium sulphide (BaS) slurries by passing CO2 gas into a pilot-scale bubbling column reactor under ambient conditions was used to assess the technical feasibility of BaCO3 recovery in the Alkali...

  5. Influence of partial substitution of cerium for lanthanum on magnetocaloric properties of La1-xCexFe11.44Si1.56 and their hydrides

    Institute of Scientific and Technical Information of China (English)

    慕利娟; 黄焦宏; 张文佳; 刘翠兰; 王高峰; 赵增祺

    2014-01-01

    The structure and magnetocaloric properties of La1–xCexFe11.44Si1.56 and their hydrides La1–xCexFe11.44Si1.56Hy (x=0, 0.1, 0.2, 0.3, 0.4) were investigated. The samples crystallized mainly in the cubic NaZn13-type structure with a small amount ofα-Fe phase as impurity. The lattice constants and Curie temperature presented the same change tendency with increasing of Ce content. For the hydrides, the influence of Ce content on lattice constants was weakened and the values of H concentration y were approximate to be 1.56. The La1–xCexFe11.44Si1.56 compounds exhibited large values of isothermal entropy change –ΔSm around the Curie tem-perature TC under a low magnetic field change of 1.5 T. The value of–ΔSm increased and then decreased with increasing Ce con-tent, reached the maximum, 26.07 J/kg·K for x=0.3. TC increased up to the vicinity of room temperature by hydrogen absorption for the Ce substituted compounds, but TC only slightly decreased with increasing Ce content. The first-order metamagnetic transi-tion was still kept in the hydrides and the maximum values of–ΔSm were lower than those of the La1–xCexFe11.44Si1.56 compounds, but still remained large values, about 10.5 J/kgK under a magnetic field change of 1.5 T. The values of–ΔSm were nearly inde-pendent of the Ce content and did not increase with increasing x for the hydrides. The La1–xCexFe11.44Si1.56Hy (x=0–0.4) hydrides exhibited large magnetic entropy changes, small hysteresis loss and effective refrigerant capacity covered the room temperature range from 305 to 317 K. These hydrides are very useful for the magnetic refrigeration applications near room temperature under low magnetic field change.

  6. Lanthanum carbonate stimulates bone formation in a rat model of renal insufficiency with low bone turnover.

    Science.gov (United States)

    Fumoto, Toshio; Ito, Masako; Ikeda, Kyoji

    2014-09-01

    Control of phosphate is important in the management of chronic kidney disease with mineral and bone disorder (CKD-MBD), for which lanthanum carbonate, a non-calcium phosphate-binding agent, has recently been introduced; however, it remains to be determined whether it has any beneficial or deleterious effect on bone remodeling. In the present study, the effects of lanthanum carbonate were examined in an animal model that mimics low turnover bone disease in CKD, i.e., thyroparathyroidectomized (TPTX) and 5/6 nephrectomized (NX) rats undergoing a constant infusion of parathyroid hormone (PTH) and thyroxine injections (TPTX-PTH-5/6NX). Bone histomorphometry at the second lumbar vertebra and tibial metaphysis revealed that both bone formation and resorption were markedly suppressed in the TPTX-PTH-5/6NX model compared with the sham-operated control group, and treatment with lanthanum carbonate was associated with the stimulation of bone formation but not an acceleration of bone resorption. Lanthanum treatment caused a robust stimulation of bone formation with an activation of osteoblasts on the endosteal surface of femoral diaphysis, leading to an increase in cortical bone volume. Thus, lanthanum carbonate has the potential to stimulate bone formation in cases of CKD-MBD with suppressed bone turnover.

  7. Bifunctional lanthanum phosphate substrates as novel adsorbents and biocatalyst supports for perchlorate removal

    Energy Technology Data Exchange (ETDEWEB)

    Sankar, Sasidharan [Materials Science and Technology Division (India); Prajeesh, Gangadharan Puthiya Veetil; Anupama, Vijaya Nadaraja [Process Engineering and Environmental Technology Division, CSIR – National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019 (India); Krishnakumar, Bhaskaran [Process Engineering and Environmental Technology Division, CSIR – National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019 (India); Academy of Scientific and Industrial Research (AcSIR) (India); Hareesh, Padinhattayil [Materials Science and Technology Division (India); Nair, Balagopal N. [R and D Centre, Noritake Co. Ltd., Aichi (Japan); Warrier, Krishna Gopakumar [Materials Science and Technology Division (India); Academy of Scientific and Industrial Research (AcSIR) (India); Hareesh, Unnikrishnan Nair Saraswathy, E-mail: hareesh@niist.res.in [Materials Science and Technology Division (India); Academy of Scientific and Industrial Research (AcSIR) (India)

    2014-06-30

    Graphical abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign thermal gelation process, performed the role of dual functional sorbent facilitating perchlorate adsorption and bioremediation through the growth of perchlorate reducing microbial colonies. - Highlights: • Lanthanum phosphate monoliths as efficient perchlorate adsorbents. • And also as substrates for biofilm (perchlorate reducing bacteria) growth. • Environmentally benign thermal gelation process for substrate fabrication. • 98% adsorption efficiency for perchlorate concentrations up to 100 μg/L. • The regenerated monoliths show nearly 100% reusability. - Abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign colloidal forming process employing methyl cellulose, are reported here as excellent adsorbents of perchlorate with >98% efficiency and with 100% reusability. Additionally, the effectiveness of such substrates as biocatalyst supports that facilitate biofilm formation of perchlorate reducing microbes (Serratia marcescens NIIST 5) is also demonstrated for the first time. The adsorption of perchlorate ions is attributed to the pore structure of lanthanum phosphate substrate and the microbial attachment is primarily ascribed to its intrinsic hydrophobic property. Lanthanum phosphate thus emerges as a dual functional material that possesses an integrated adsorption/bioremediation property for the effective removal of ClO{sub 4}{sup −} which is an increasingly important environmental contaminant.

  8. Effect of Lanthanum on Nodule Count and Nodularity of Ductile Iron

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The present study aims at finding out the effect of the addition of a single rare earth element, that is, lanthanum on the nodularity and nodule count of ductile iron under controlled conditions. For this purpose, four melts with different compositions were made, using a 28 kg inductotherm medium frequency induction furnace. The temperature was carefully maintained between 1400 and 1450 ℃ for these heats. A good quality charge consisting of Sorel metal, ferrosilicon, Swedish iron, ferrosilicon magnesium, and ferrosilicon lanthanum was used for the production of melts. A vertically parted sand mould was used for casting of 10 test bars made from local silica sand. Standard coin samples were chill-cast to conduct chemical analysis of the ductile iron. Microstructure study of the samples was conducted using a Leica optical microscope. Nodule count and nodularity of the samples were carried out using an image analyzer. The results obtained indicated that with the increased addition of lanthanum the nodule count of ductile iron increased, thus making it evident that it played a significant role in increasing the mechanical properties. The highest nodule count of 467 was obtained with the addition of 0.03% lanthanum. However, the effect of lanthanum on nodularity was negligible with nodularity ranging from 81% to 83%.

  9. Lanthanum acetate inhibits vascular calcification induced by vitamin D3 plus nicotine in rats.

    Science.gov (United States)

    Zhou, Ye-Bo; Jin, Shao-Ju; Cai, Yan; Teng, Xu; Chen, Li; Tang, Chao-Shu; Qi, Yong-Fen

    2009-08-01

    Lanthanum, a rare earth element, has been used to decrease serum phosphorus level in patients with chronic renal disease and hyperphosphatemia. We aimed to observe the effect and mechanism of two doses of lanthanum acetate (375 and 750 mg/kg/day) on vascular calcification induced by vitamin D3 plus nicotine treatment in rats for 4 weeks. As compared with control rats, rats with calcification showed widespread calcified nodules and irregular elastic fibers in calcified aorta on von Kossa calcium staining and increased aortic calcium and phosphorus contents, alkaline phosphatase (ALP) activity and bone-related protein expressions for osteopontin (OPN) and type III sodium dependent phosphate cotransporter Pit-1 (Pit-1). After treatment with either dose of lanthanum acetate, the calcified nodules and degree of irregular elastic fibers decreased in aortas. Lanthanum acetate at 750 mg/kg/day was more effective than 375 mg/kg/day in lessening vascular calcification by significantly reducing plasma phosphorus level, calcium x phosphorus product and ALP activity, by 30.3%, 28.6%, and 68.6%, respectively; reducing aortic phosphorus and calcium contents and ALP activity, by 48%, 53.1%, and 63.5% (all P nicotine alone. Lanthanum acetate could effectively inhibit the pathogenesis of vascular calcification.

  10. Silica doped with lanthanum sol-gel thin films for corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Abuin, M. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Serrano, A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); Llopis, J. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Garcia, M.A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); IMDEA Nanoscience, Fco. Tomas y Valiente 7, 28049 Madrid (Spain); Carmona, N., E-mail: n.carmona@fis.ucm.es [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain)

    2012-06-01

    We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol-gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: Black-Right-Pointing-Pointer Silica sol-gel films doped with lanthanum ions were synthesized. Black-Right-Pointing-Pointer Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. Black-Right-Pointing-Pointer La-acetate is an affordable chemical reactive preferred for the industry. Black-Right-Pointing-Pointer Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. Black-Right-Pointing-Pointer An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

  11. Design, testing, fabrication and launch support of a liquid chemical barium release payload (utilizing the liquid fluorine-barium salt/hydrazine system)

    Science.gov (United States)

    Stokes, C. S.; Smith, E. W.; Murphy, W. J.

    1972-01-01

    A payload was designed which included a cryogenic oxidizer tank, a fuel tank, and burner section. Release of 30 lb of chemicals was planned to occur in 2 seconds at the optimum oxidizer to fuel ratio. The chemicals consisted of 17 lb of liquid fluorine oxidizer and 13 lb of hydrazine-barium salt fuel mixture. The fuel mixture was 17% barium chloride, 16% barium nitrate, and 67% hydrazine, and contained 2.6 lb of available barium. Two significant problem areas were resolved during the program: explosive valve development and burner operation. The release payload was flight tested, from Wallops Island, Virginia. The release took place at an altitude of approximately 260 km. The release produced a luminous cloud which expanded very rapidly, disappearing to the human eye in about 20 seconds. Barium ion concentration slowly increased over a wide area of sky until measurements were discontinued at sunrise (about 30 minutes).

  12. 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

  13. 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.

  14. 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.

  15. 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)

  16. 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...

  17. Stark spectrum of barium in highly excited Rydberg states

    Institute of Scientific and Technical Information of China (English)

    Yang Hai-Feng; Gao Wei; Cheng Hong; Liu Xiao-Jun; Liu Hong-Ping

    2013-01-01

    We present observations of Stark spectra of barium in highly excited Rydberg states in the energy region around n =35.The one-photon excitation concerns the π transition.The observed Stark spectra at electric fields ranging from 0 to 60 V·cm-1 are well explained by the diagonalization of the Hamiltonian incorporating the core effects.From the Stark maps,the anti-crossings between energy levels are identified experimentally and theoretically.The time of flight spectra at the specified Stark states are recorded,where the deceleration and acceleration of barium atoms are observed.This is very consistent with the prediction derived from the Stark maps from the point of view of energy conservation.

  18. Barium titanate nanoparticles: promising multitasking vectors in nanomedicine

    Science.gov (United States)

    Graziana Genchi, Giada; Marino, Attilio; Rocca, Antonella; Mattoli, Virgilio; Ciofani, Gianni

    2016-06-01

    Ceramic materials based on perovskite-like oxides have traditionally been the object of intense interest for their applicability in electrical and electronic devices. Due to its high dielectric constant and piezoelectric features, barium titanate (BaTiO3) is probably one of the most studied compounds of this family. Recently, an increasing number of studies have been focused on the exploitation of barium titanate nanoparticles (BTNPs) in the biomedical field, owing to the high biocompatibility of BTNPs and their peculiar non-linear optical properties that have encouraged their use as nanocarriers for drug delivery and as label-free imaging probes. In this review, we summarize all the recent findings about these ‘smart’ nanoparticles, including the latest, most promising potential as nanotransducers for cell stimulation.

  19. HYBRID AND CHARACTERISTIC OF POLYANILINE- BARIUM TITANATE NANOCOMPOSITE PARTICLES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Polyaniline-barium titanate (PAn-BaTiO3) ultrafine composite particles were prepared by the oxidative polymerization of aniline with H2O2 while barium titanate nanoparticles were synthesized with a sol-gel method. The infrared spectrogram shows that the polymerization of PAn in the hybrid process of PAn-BaTiO3 is similar with the polymeric process of pure aniline, and there is interaction of PAn and BaTiO3 in the PAn-BaTiO3. SEM and TEM results show that the average diameter of the composite particles is 1.50 μm and the diameters of BaTiO3 nanoparticles are 5-15 nm in the composite particle. The electrical conductivity of the ultrafine composite particles is transformable from 100 to 10-11S/cm by equilibrium doping or dedoping method using various concentration of HCl or NaOH solutions.

  20. The crystal growth of barium flouride in aqueous solution

    Science.gov (United States)

    Barone, J. P.; Svrjcek, D.; Nancollas, G. H.

    1983-06-01

    The kinetics of growth of barium flouride seed crystals were investigated in aqueous solution at 25°C using a constant composition method, in which the supersaturation and ionic strength were maintained constant by the addition of titrants consisting of barium nitrate and potassium flouride solutions. The rates of reaction, studied over a range of supersaturation (σ ≈ 0.4 to 1.0), were interpreted in terms of crystal growth models. A spiral growth mechanism best describes the data, and scanning electron microscopy indicates a three-dimensional growth. In the presence of inorganic additives such as phosphate, however, induction periods precede a morphological two-dimensional crystallization. Coulter Counter results show little crystal agglomeration.

  1. Electromagnetic properties of carbon black and barium titanate composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guiqin [School of Material Science and Engineering, Dalian University of Technology, Dalian 116023 (China)], E-mail: c2b2chen@163.com; Chen Xiaodong; Duan Yuping; Liu Shunhua [School of Material Science and Engineering, Dalian University of Technology, Dalian 116023 (China)

    2008-04-24

    Nanocrystalline carbon black/barium titanate compound particle (CP) was synthesized by sol-gel method. The phase structure and morphology of compound particle were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM) and Raman spectrum measurements, the electroconductivity was test by trielectrode arrangement and the precursor powder was followed by differential scanning calorimetric measurements (DSC) and thermal gravimetric analysis (TGA). In addition, the complex relative permittivity and permeability of compound particle were investigated by reflection method. The compound particle/epoxide resin composite (CP/EP) with different contents of CP were measured. The results show barium titanate crystal is tetragonal phase and its grain is oval shape with 80-100 nm which was coated by carbon black film. As electromagnetic (EM) complex permittivity, permeability and reflection loss (RL) shown that the compound particle is mainly a kind of electric and dielectric lossy materials and exhibits excellent microwave absorption performance in the X- and Ku-bands.

  2. Particularities of Radiation Defect Formation in Ceramic Barium Cerate

    Science.gov (United States)

    Khromushin, I. V.; Aksenova, T. I.; Tuseev, T.; Munasbaeva, K. K.; Ermolaev, Yu V.; Ermolaev, V. N.; Seitov, A. S.

    2015-04-01

    The effects of irradiation with electrons, ions of noble gases (Ne, Ar, Kr) and oxygen on the structure and properties of neodymium-doped barium cerate have been studied using the methods of X-ray diffraction analysis, scanning electron and atomic force microscopy, thermal desorption spectroscopy. It was shown that irradiation by low-energy ions of noble gases stimulates the blistering processes on the sample surface, while the high-energy ions contribute to formation of the structures on the irradiated surface that resemble the various stages of spherulitegrowth. The similar structures were not observed in the case of irradiation with high-energy oxygen ions. According to the data on thermal desorption of water and oxygen molecules from the irradiated barium cerate it was supposed that irradiation by the noble gas ions promotes neodymium oxidation state change. It was noticed that the electron irradiation leads to the formation of the nano-sized acicular structures on the cerate surface.

  3. Mechanical properties of thermoelectric lanthanum telluride from quantum mechanics

    Science.gov (United States)

    Li, Guodong; Aydemir, Umut; Wood, Max; Goddard, William A., III; Zhai, Pengcheng; Zhang, Qingjie; Snyder, G. Jeffrey

    2017-07-01

    Lanthanum telluride (La3Te4) is an n-type high-performance thermoelectric material in the high temperature range, but its mechanical properties remain unknown. Since we want robust mechanical properties for their integration into industrial applications, we report here quantum mechanics (QM) simulations to determine the ideal strength and deformation mechanisms of La3Te4 under pure shear deformations. Among all plausible shear deformation paths, we find that shearing along the (0 0 1)/ slip system has the lowest ideal shear strength of 0.99 GPa, making it the most likely slip system to be activated under pressure. We find that the long range La-Te ionic interactions play the predominant role in resisting shear deformation. To enhance the mechanical strength, we suggest improving the long ionic La-Te bond stiffness to strengthen the ionic La-Te framework in La3Te4 by a defect-engineering strategy, such as partial substitution of La by Ce or Pr having isotypic crystal structures. This work provides the fundamental information to understand the intrinsic mechanics of La3Te4.

  4. Structure modeling of terbium doped strontium-lanthanum borate

    Institute of Scientific and Technical Information of China (English)

    A. Shyichuk; S. Lis; G. Meinrath

    2014-01-01

    Terbium doped strontium-lanthanum borate, Sr3La2(BO3)4:Tb (SLB), was studied by semi-empirical computational ap-proaches using PM6 parametrization and the SPARKLE model for lanthanide(III) (Ln(III)) cations. The focus of interest was on structural aspects, e.g. the cell parameters and distribution of dopant ions between various sites as a function of dopant concentration. The cell linear dimensions were calculated to decrease linearly with increasing dopant molar concentration. SLB offered two sites for the dopant. Calculations predicted that one of these sites should be preferred by the Tb(III) dopant. The optimized cell dimensions as well as the total energies differed for structures with dopant exclusively in site 1 or site 2. Computational predictions were tested against experimental results obtained for SLB synthesized by sol-gel method varying the dopant concentration. The agreement be-tween experimental and computational results was found sufficiently promising to continue the computational studies.

  5. Synthesis of lanthanum tungstate interconnecting nanoparticles by high voltage electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Keereeta, Yanee, E-mail: ynkeereeta@gmail.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongtem, Titipun, E-mail: ttpthongtem@yahoo.com [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongtem, Somchai [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-10-01

    Graphical abstract: - Highlights: • La{sub 2}(WO{sub 4}){sub 3} as one of semiconducting materials. • H.V. electrospinning was used to synthesize La{sub 2}(WO{sub 4}){sub 3} interconnecting nanoparticles. • A promising material for photoemission. - Abstract: Lanthanum tungstate (La{sub 2}(WO{sub 4}){sub 3}) interconnecting nanoparticles in the shape of fibers were successfully synthesized by electrospinning in combination with high temperature calcination. In this research, calcination temperature for the synthesis of the fibers evidently influenced the diameter, morphology and crystalline degree. The crystalline monoclinic La{sub 2}(WO{sub 4}){sub 3} fibers with 200–700 nm in diameter, two main Raman peaks at 945 and 927 cm{sup −1}, FTIR stretching modes at 936 and 847 cm{sup −1}, 2.02 eV energy gap and 415–430 nm blue emission were synthesized by calcination of inorganic/organic hybrid fibers at 750 °C for 5 h, characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV–visible spectroscopy and photoluminescence (PL) spectroscopy. The surface of the composite fibers before calcination was very smooth. Upon calcination the composite fibers at 750 °C for 5 h, they were transformed into nanoparticles join together in the shape of fibers with rough surface.

  6. Thermochemical Study of Lanthanum Complex Crystal with β-Alanine

    Institute of Scientific and Technical Information of China (English)

    陈平初; 屈松生; 詹正坤; 吴新明

    2002-01-01

    Lanthanum complex crystal with β-alanine (1∶3) was synthesized. Through the DTA,TG,chemistry analysis and comparison with literature, it shows that its form is {[La2(β-ala)6* (H2O)4](ClO4)6*H2O}n, and its purity is 98.86%. The dissolution enthalpy of the reactants and products in 2 mol*L-1 HCl solution (298.15K) was measured by using the isoperibol reaction calorimetry. ΔrHm was calculated by a designed thermochemical cycle of the coordination reaction. From the results and other auxiliary quantities, the standard molar enthalpy of formation of [La2(β-ala)6*(H2O)4](ClO4)6*H2O is obtained to be ΔfHm°{[La2(β-ala)6*(H2O)4](ClO4)6*H2O} = - 7062.911 kJ*mol-1.

  7. Signal amplification of dopamine using lanthanum hexacyanoferrate-modified electrode

    Indian Academy of Sciences (India)

    T Selvaraju; R Ramaraj

    2014-01-01

    A sensitive and selective electrochemical sensor has been developed using an electroactive polynuclear lanthanum hexacyanoferrate (LaHCF) complex with counter alkali cation (Na+) deposited on the glassy carbon (GC) electrode (GC/LaHCF). The GC/LaHCF-modified electrode is found to be an excellent transducer in mediating the oxidation of neurotransmitter molecule such as dopamine (DA) at physiological pH 7.2. Interestingly, the GC/LaHCF-modified electrode amplifies a 50-fold enhancement in the oxidation of DA signal compared to the bare GC electrode. Besides, the GC/LaHCF-modified electrode shows excellent selectivity in the voltammetric oxidation of DA in the presence of ascorbic acid (AA). Under optimal conditions, the GC/LaHCF modified electrode shows a linear relationship in DA oxidation between 0.1 × 10−6 and 1.0 × 10−6M with the detection limit of 1 × 10−8M (10 nM). Importantly, practical utility of the modified electrode is good in studying the real sample analysis such as dopamine hydrochloride injection assay.

  8. Dynamic Effects in Core Electron Impact Excitation of Lanthanum

    Science.gov (United States)

    Nuroh, Kofi

    2000-05-01

    Experimental data of inelastic electron scattering exciting inner3d-shell of metallic lanthanum show strong dependence on the projectile electron energy.^1 Calculations based on an atomic physics description of the triply ionized free atom are made. The large spin-orbit coupling constant of the 3d-hole leads to an approximate jK-coupling. The resulting excitation strength is formulated in terms of the Born approximation including resonant contributions. The intensity is folded with a Lorentzian broadening with full width at half maximum (FWHM) parameter Γ. This parameter is considered to be dependent on the projectile electron energy so that the dynamic effects found in experimental electron-energy-loss-spectra (EELS) may be addressed. The systematic variation of the relative intensities of the spin-orbit doublet structures with exciation energy found in experiment is generally accounted for as Γ is varied from the experimentally measured values of 0.7eV - 0.5eV and beyond^2 ^1J. Kanski and G. Wendin, Phys. Rev.B24, 1981 (4977). ^2K. Nuroh, Physica Scripta 61, 2000(in press).

  9. Memory phenomenon in a lanthanum based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ye [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Huang, Wei Min, E-mail: mwmhuang@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Zhao, Yong [School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013 (China); Ding, Zhen [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Li, Yan [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Tor, Shu Beng; Liu, Erjia [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

    2016-07-05

    In this paper, we experimentally investigate two memory phenomena in a lanthanum based bulk metallic glass (BMG). While the temperature memory effect (TME) is not found by differential scanning calorimeter (DSC) test, shape recovery is observed in samples indented at both low and high temperatures. In terms of shape memory related characteristics, this BMG shares some features of shape memory alloys (SMAs) due to its metal nature, and some other features of shape memory polymers (SMPs) owing to its glassy–rubbery transition. The formation of protrusion in the polished sample after heating to super-cooled liquid region (SCLR) indicates that surface tension is not a necessarily positive contributor for shape recovery. Release of internal elastic stress is concluded as the major player. Although the amorphous nature of BMGs enables for storing appreciable amount of internal elastic stress upon deformation, without the presence of cross-linker as in typical SMPs, the shape recovery in BMGs is rather limited. - Highlights: • Experimental investigation of shape recovery in BMG. • Surface tension is not the major reason for shape recovery in BMG. • Release of internal stress is the major contributor for shape recovery. • Comparison of shape memory features of BMG with other shape memory materials.

  10. Catalytic graphitization of carbon/carbon composites by lanthanum oxide

    Institute of Scientific and Technical Information of China (English)

    ZHANG Can; LU Guimin; SUN Ze; YU Jianguo

    2012-01-01

    Graphitized carbon/carbon composites were prepared by the process of catalytic graphitization with the rare-earth catalyst,lanthanum oxide (La2O3),in order to increase the degree of graphitization and reduce the electrical resistivity.The modified coal tar pitch and coal-based needle coke were used as carbon source,and a small amount of La2O3 was added to catalyze the graphitization of the disordered carbon materials.The effects of La2O3 catalyst on the graphitization degree and microstructure oftbe carbon/carbon composites were investigated by X-ray diffraction,scanning electron microscopy,and Raman spectroscopy.The results showed that La2O3 promoted the formation of more perfect and larger crystallites,and improved the electrical/mechanical properties of carbon/carbon composites.Carbon/carbon composites with a lower electrical resistivity (7.0 μΩ·m) could be prepared when adding 5 wt.% La2O3 powder with heating treatment at 2800 ℃.The catalytic effect of La2O3 for the graphitization of carbon/carbon composites was analyzed.

  11. Work function measurement of lanthanum-boron compounds

    Science.gov (United States)

    Jacobson, D. L.; Storms, E. K.

    1978-01-01

    The relationship between emission properties and sample composition is studied for lanthanum-boron compounds. Specifically, the La-B system is considered between 1400 and 2100 K and between LaB(4.24) and LaB(29.2) to determine the phase relationship, chemical activity of the compounds, vapor composition, and vaporization rate. The results indicate that: (1) a blue-colored phase near LaB(9) exists between a purple-colored LaB(6) and elemental boron, (2) vaporization is sufficiently more rapid than diffusion so that great compositional differences exist between the surface and the interior, (3) an activation energy lowers the boron vaporization rate from LaB(6), and (4) a steady-state surface composition between LaB(6.04) and LaB(6.07) exists for freely vaporizing materials as a function of interior composition, purity, and temperature. It is noted that the ultimate life of a thermionic diode is governed by electrode vaporization rate whereas efficiency is governed by the electrode work function.

  12. Complex Impedance Studies of Optically Excited Strontium Barium Niobate

    Science.gov (United States)

    2007-11-02

    has a tetragonal tungsten - bronze structure. The unit cell for this structure, illustrated below in Fig. 2.1, consists of ten oxygen octahedra joined...4 Kittel, pp. 373-374. 5 P. B. Jamieson, et al, “Ferroelectric Tungsten Bronze -Type Crystal Structures. I. Barium Strontium Niobate...Oxford, 1987). 2. C. Kittel, Introduction to Solid State Physics, (Wiley, New York, 1986). 3. P. B. Jamieson, et al, “Ferroelectric Tungsten

  13. Acute barium intoxication following ingestion of soap water solution

    Directory of Open Access Journals (Sweden)

    Nandita Joshi

    2012-01-01

    Full Text Available We present a rare case in which a young girl ingested a solution of a hair-removing soap. The ingestion resulted in profound hypokalemia and severe acidosis leading to flaccid paralysis, respiratory arrest and ventricular arrhythmias. Ultimately the patient made complete recovery. The soapwas found to contain barium sulfide. The degree of paralysis and acidosis appeared to be directly related to serum potassium levels.

  14. Cerium Aryloxides as Precursors for Monopentamethylcyclopentadienyl Organocerium(III) Compounds; X-Ray Crystal Structure of (η5-Pentamethylcyclopentadienyl)bis(2,6-di-t-butylphenoxo)cerium

    NARCIS (Netherlands)

    Heeres, Hero J.; Meetsma, Auke; Teuben, Jan H.

    1988-01-01

    Tris(2,6-di-t-butylphenoxo)cerium reacts with (C5Me5)Li in pentane to form (η5-C5Me5)bis(2,6-di-t-butylphenoxo)cerium, whose structure was established by X-ray crystallography and which, on subsequent reaction with LiCH(SiMe3)2, gives a novel mono(C5Me5)cerium-bisalkyl complex,

  15. 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.

  16. 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 ...

  17. Barium isotopes reveal role of ocean circulation on barium cycling in the Atlantic

    Science.gov (United States)

    Bates, Stephanie L.; Hendry, Katharine R.; Pryer, Helena V.; Kinsley, Christopher W.; Pyle, Kimberley M.; Woodward, E. Malcolm S.; Horner, Tristan J.

    2017-05-01

    We diagnose the relative influences of local-scale biogeochemical cycling and regional-scale ocean circulation on Atlantic barium cycling by analysing four new depth profiles of dissolved Ba concentrations and isotope compositions from the South and tropical North Atlantic. These new profiles exhibit systematic vertical, zonal and meridional variations that reflect the influence of both local-scale barite cycling and large-scale ocean circulation. Epipelagic decoupling of dissolved Ba and Si reported previously in the tropics is also found to be associated with significant Ba isotope heterogeneity. As such, we contend that this decoupling originates from the depth segregation of opal and barite formation but is exacerbated by weak vertical mixing. Zonal influence from isotopically-'heavy' water masses in the western North Atlantic evidence the advective inflow of Ba-depleted Upper Labrador Sea Water, which is not seen in the eastern basin or the South Atlantic. Meridional variations in Atlantic Ba isotope systematics below 2000 m appear entirely controlled by conservative mixing. Using an inverse isotopic mixing model, we calculate the Ba isotope composition of the Ba-poor northern end-member as +0.45 ‰ and the Ba-rich southern end-member +0.26 ‰, relative to NIST SRM 3104a. The near-conservative behaviour of Ba below 2000 m indicates that Ba isotopes can serve as an independent tracer of the provenance of northern- versus southern-sourced water masses in the deep Atlantic Ocean. This finding may prove useful in palaeoceanographic studies, should appropriate sedimentary archives be identified, and offers new insights into the processes that cycle Ba in seawater.

  18. Effects of polyacrylic acid additive on barium sulfate particle morphology

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jie; Liu, Dandan; Jiang, Hongkun; Wang, Jun; Jing, Xiaoyan; Chen, Rongrong [Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Zhu, Wenting [Department of Gastroenterology, Harbin Medical University Cancer Hospital, Harbin 150081 (China); Han, Shihui [Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Li, Wanyou [College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001 (China); Wei, Hao, E-mail: weihao7512@126.com [Key Laboratory of Superlight Material and Surface Technology of Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001 (China)

    2016-06-01

    In this paper, polyacrylic acid (PAA) was used as a growth modifier to control micron-sized barium sulfate particles via a simple precipitation reaction between sodium sulfate and barium chloride at ambient temperature. The barium sulfate particles were exhibited various morphologies, such as monodisperse spheres, ellipsoids, rose-like aggregates, etc. To better understand the formation mechanisms of the various morphologies of these particles, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA) were employed. It was found that the PAA concentration, pH, and Ba{sup 2+} and SO{sub 4}{sup 2−} ions concentrations were the most important parameters controlling the morphology of the BaSO{sub 4} particles. These parameters affected the BaSO{sub 4} morphology by influencing the interactions between the PAA carboxyl groups and inorganic ions and the conformation change of the PAA molecular chains. Moreover, this work attempts to provide a preliminary understanding of the formation of the spherical BaSO{sub 4} particles with the randomly coiled conformation of the polymer. - Highlights: • Polyacrylic acid (PAA) was used as a growth modifier to control micron-sized BaSO{sub 4} particles. • The PAA/BaSO{sub 4} particles were exhibited various morphologies. • Provide a preliminary understanding of the formation mechanism of BaSO{sub 4} particles.

  19. Barium thiolates and selenolates: syntheses and structural principles.

    Science.gov (United States)

    Ruhlandt-Senge, K; Englich, U

    2000-11-17

    The synthesis and structural characterization of a family of barium thiolates and selenolates is described. The thiolates were synthesized by metallation of thiols, the selenolates by reductive insertion of the metal into the selenium-selenium bond of diorganodiselenides. Both reaction sequences were carried out by using barium metal dissolved in ammonia; this afforded barium thiolates and selenolates in good yield and purity. The structural principles displayed in the target compounds span a wide range of solid-state formulations, including monomeric and dimeric species, and separated ion triples, namely [Ba(thf)4(SMes*)2] (1; Mes* = 2,4,6-tBU3C6H2), [Ba(thf)4(SeMes*)2] (2), [Ba([18]crown-6)(hmpa)2][(SeMes*)2] (3), the dimeric [(Ba(py)3(thf)(SeTrip)2)2] (4; py = pyridine, Trip = 2,4.6-iPr3C6H2), and [Ba([18]crown-6)(SeTrip)2] (5). The full range of association modes is completed by [Ba([18]crown-6)(hmpa)SMes*][SMes*] (6) communicated earlier by this group. In the solid state, this compound displays an intermediate ion coordination mode: one anion is bound to the metal, while the second one is unassociated. Together these compounds provide structural information about all three different association modes for alkaline earth metal derivatives. This collection of structural data allows important conclusions about the influence of solvation and ligation on structural trends.

  20. Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Simoes, A.Z., E-mail: alezipo@yahoo.co [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro, Amazonas, CEP 35900-37, Itabira, MG (Brazil); Universidade Estadual Paulista- Unesp - Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Pedregulho, CEP 12516-410 Guaratingueta, SP (Brazil); Moura, F.; Onofre, T.B. [Universidade Federal de Itajuba- Unifei - Campus Itabira, Rua Sao Paulo, 377, Bairro, Amazonas, CEP 35900-37, Itabira, MG (Brazil); Ramirez, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)

    2010-10-22

    Research highlights: {yields} Barium strontium titanate nanoparticles were obtained by the Hydrothemal microwave technique (HTMW) {yields} This is a genuine technique to obtain nanoparticles at low temperature and short times {yields} Barium strontium titanate free of carbonates with tetragonal structure was grown at 130 {sup o}C. - Abstract: Hydrothermal-microwave method (HTMW) was used to synthesize crystalline barium strontium titanate (Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3}) nanoparticles (BST) in the temperature range of 100-130 {sup o}C. The crystallization of BST with tetragonal structure was reached at all the synthesis temperatures along with the formation of BaCO{sub 3} as a minor impurity at lower syntheses temperatures. Typical FT-IR spectra for tetragonal (BST) nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH- groups, commonly found in materials obtained by HTMW process. FE/SEM revealed that lower syntheses temperatures led to a morphology that consisted of uniform grains while higher syntheses temperature consisted of big grains isolated and embedded in a matrix of small grains. TEM has shown BST nanoparticles with diameters between 40 and 80 nm. These results show that the HTMW synthesis route is rapid, cost effective, and could serve as an alternative to obtain BST nanoparticles.

  1. Nanocomposite Lanthanum Zirconate Thermal Barrier Coating Deposited by Suspension Plasma Spray Process

    Science.gov (United States)

    Wang, Chaohui; Wang, You; Wang, Liang; Hao, Guangzhao; Sun, Xiaoguang; Shan, Fan; Zou, Zhiwei

    2014-10-01

    This work seeks to develop an innovative nanocomposite thermal barrier coating (TBC) exhibiting low thermal conductivity and high durability compared with that of current TBCs. To achieve this objective, nanosized lanthanum zirconate particles were selected for the topcoat of the TBC system, and a new process—suspension plasma spray—was employed to produce desirable microstructural features: the nanocomposite lanthanum zirconate TBC contains ultrafine splats and high volume porosity, for lower thermal conductivity, and better durability. The parameters of plasma spray experiment included two main variables: (i) spray distance varying from 40 to 80 mm and (ii) the concentration of suspension 20, 25, and 30 wt.%, respectively. The microstructure of obtained coatings was characterized with scanning electron microscope and x-ray diffraction. The porosity of coatings is in the range of 6-10%, and the single phase in the as-sprayed coatings was pyrochlore lanthanum zirconate.

  2. Lanthanum nitrate genotoxicity evaluation: Ames test, mouse micronucleus assay, and chromosome aberration test.

    Science.gov (United States)

    Yang, Hui; Zhang, Xiaopeng; Liu, Haibo; Cui, Wenming; Zhang, Qiannan; Li, Yongning; Yu, Zhou; Jia, Xudong

    2016-11-01

    The increasing use of rare-earth elements (REE) and their compounds has led to their accumulation in the environment and has raised concern about their safety. The toxic effects of REE such as lanthanum are largely unknown; genotoxicity studies have been limited and results are controversial. We evaluated the genotoxicity of lanthanum nitrate (La(NO3)3) in several in vitro and in vivo tests, including bacterial reverse mutation assay (Ames test), mouse bone marrow micronucleus assay, and chromosome aberration assay. La(NO3)3 was not mutagenic in the Ames test. La(NO3)3 did not increase the frequencies of bone marrow micronuclei or chromosome aberration in the mouse after repeated treatments at oral doses up to 735 (females) and 855mg/kg (males). The compound did not increase the frequency of chromosome aberrations in CHO cells in vitro. These results indicate that lanthanum is not a genotoxic hazard.

  3. Distribution of intravascularly injected lanthanum ions in ganglia of the autonomic nervous system of the rat.

    Science.gov (United States)

    DePace, D M

    1984-12-01

    Intravascular injection of lanthanum revealed that tight junctions of capillaries in sympathetic ganglia are impermeable to small ions and thus behave like capillaries of the blood-brain barrier. The failure of lanthanum to accumulate in the extracellular space suggests that fenestrated capillaries are not as ion-permeable as use of horseradish peroxidase (HRP) by some authors has indicated. A possible toxic action associated with high concentrations of HRP may be responsible for the high permeability of this substance. Testing with lanthanum demonstrated that sympathetic ganglia possess anatomic features that provide a hematic barrier. The blood-ganglion barrier resembles, but has not yet been demonstrated to be as absolute as the blood-brain barrier.

  4. Toxicity of Lanthanum Against Rhizoctonia solani and Its Effect on Disease-Related Enzymes

    Institute of Scientific and Technical Information of China (English)

    Mu Kangguo; Zhang Fusuo; Cui Jianyu; Zhang Wenji; Hu Lin

    2005-01-01

    The inhibition of lanthanum (La) to mycelial growth and three disease-related enzymes of Rhizoctonia solani were studied. The results showed that lanthanum inhibits the growth of Rhizoctonia solani strongly. EC50 and EC95 of La were 171.9 and 667.7 mg · L-1 measured in solid culture media respectively, while 111.4 and 500.7 mg · L-1 measured in liquid culture media respectively. Lanthanum also has activating effects on disease-related enzymes of the fungus such as pectinase, protease and cellulase. However, the quantity or the activity of the total enzymes decreases significantly because of the strong blockage of mycelial growth when the La2O3 concentration is over 50 mg · L-1, and the virulence of pathogen decreases as well.

  5. Fabrication of Nanosized Lanthanum Zirconate Powder and Deposition of Thermal Barrier Coating by Plasma Spray Process

    Science.gov (United States)

    Mishra, S. K.; Jagdeesh, N.; Pathak, L. C.

    2016-07-01

    The present manuscript discusses our findings on fabrication of nanosized lanthanum zirconate powder for thermal barrier coating application and its coating by plasma spray on nickel-based superalloy substrate. Single-phase La2Zr2O7 coating of thickness of the order of 45 µm on the Ni-Cr-Al bond coat coated Ni-based superalloy substrate was deposited by plasma spray process. The layers at the interface did not show spallation and inter diffusion was very less. The microstructure, interface, porosity, and mechanical properties of different layers are investigated. The lanthanum zirconate hardness and modulus were 10.5 and 277 GPa, respectively. The load depth curve for lanthanum zirconate showed good elastic recovery around 74%.

  6. 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.

  7. Preparation of nanosized barium zirconate powder by precipitation in aqueous solution

    OpenAIRE

    Boschini, Frédéric; Guillaume, Bernard; Rulmont, André; Cloots, Rudi

    2004-01-01

    Several ways were explored to synthesize barium zirconate by soft chemistry methods in aqueous solution. In the first method the synthesis of barium zirconate was initiated by urea decomposition, through an homogeneous precipitation of barium and zirconium salts followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that a...

  8. Spectroscopy of Ba and Ba$^+$ deposits in solid xenon for barium tagging in nEXO

    OpenAIRE

    Mong, B.; Cook, S; Walton, T.; Chambers, C.; Craycraft, A.; Benitez-Medina, C.; Hall, K.; Fairbank Jr., W.; Albert, J. B.; Auty, D. J.; Barbeau, P. S.; Basque, V.; Beck, D.; Breidenbach, M.; Brunner, T.

    2014-01-01

    Progress on a method of barium tagging for the nEXO double beta decay experiment is reported. Absorption and emission spectra for deposits of barium atoms and ions in solid xenon matrices are presented. Excitation spectra for prominent emission lines, temperature dependence and bleaching of the fluorescence reveal the existence of different matrix sites. A regular series of sharp lines observed in Ba$^+$ deposits is identified with some type of barium hydride molecule. Lower limits for the fl...

  9. Simplified assessment of segmental gastrointestinal transit time with orally small amount of barium

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Weitang; Zhang, Zhiyong; Liu, Jinbo; Li, Zhen; Song, Junmin; Wu, Changcai [Department of Colorectal Surgery, The First Affiliated Hospital and Institute of Clinical Medicine, Zhengzhou University, 450052 Zhengzhou (China); Wang, Guixian, E-mail: guixianwang@hotmail.com [Department of Colorectal Surgery, The First Affiliated Hospital and Institute of Clinical Medicine, Zhengzhou University, 450052 Zhengzhou (China)

    2012-09-15

    Objective: To determine the effectiveness and advantage of small amount of barium in the measurement of gastrointestinal transmission function in comparison with radio-opaque pallets. Methods: Protocal 1: 8 healthy volunteers (male 6, female 2) with average age 40 ± 6.1 were subjected to the examination of radio-opaque pellets and small amount of barium with the interval of 1 week. Protocol 2: 30 healthy volunteers in group 1 (male 8, female 22) with average age 42.5 ± 8.1 and 50 patients with chronic functional constipation in group 2 (male 11, female 39) with average age 45.7 ± 7.8 were subjected to the small amount of barium examination. The small amount of barium was made by 30 g barium dissolved in 200 ml breakfast. After taking breakfast which contains barium, objectives were followed with abdominal X-ray at 4, 8, 12, 24, 48, 72, 96 h until the barium was evacuated totally. Results: Small amount of barium presented actual chyme or stool transit. The transit time of radio-opaque pallets through the whole gastrointestinal tract was significantly shorter than that of barium (37 ± 8 h vs. 47 ± 10 h, P < 0.05) in healthy people. The transit times of barium in constipation patients were markedly prolonged in colon (61.1 ± 22 vs. 37.3 ± 11, P < 0.01) and rectum (10.8 ± 3.7 vs. 2.3 ± 0.8 h, P < 0.01) compared with unconstipated volunteers. Transit times in individual gastrointestinal segments were also recorded by using small amount of barium, which allowed identifying the subtypes of constipation. Conclusion: The small amount barium examination is a convenient and low cost method to provide the most useful and reliable information on the transmission function of different gastrointestinal segments and able to classify the subtypes of slow transit constipation.

  10. 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.

  11. Geometry of electromechanically active structures in Gadolinium - doped Cerium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuanyuan; Zacharowicz, Renee; Frenkel, Anatoly I., E-mail: igor.lubomirsky@weizmann.ac.il, E-mail: anatoly.frenkel@yu.edu [Physics Department, Yeshiva University, 245 Lexington Avenue, New York, New York 10016 (United States); Kraynis, Olga; Lubomirsky, Igor, E-mail: igor.lubomirsky@weizmann.ac.il, E-mail: anatoly.frenkel@yu.edu [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100 (Israel); Kas, Joshua [Department of Physics, University of Washington, Seattle, Washington 98195 (United States); Weng, Tsu-Chien; Sokaras, Dimosthenis [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2016-05-15

    Local distortions from average structure are important in many functional materials, such as electrostrictors or piezoelectrics, and contain clues about their mechanism of work. However, the geometric attributes of these distortions are exceedingly difficult to measure, leading to a gap in knowledge regarding their roles in electromechanical response. This task is particularly challenging in the case of recently reported non-classical electrostriction in Cerium-Gadolinium oxides (CGO), where only a small population of Ce-O bonds that are located near oxygen ion vacancies responds to external electric field. We used high-energy resolution fluorescence detection (HERFD) technique to collect X-ray absorption spectra in CGO in situ, with and without an external electric field, coupled with theoretical modeling to characterize three-dimensional geometry of electromechanically active units.

  12. 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.

  13. 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].

  14. 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.)

  15. Molecular dynamics simulations of oxygen Frenkel pairs in cerium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Shiiyama, Kenichi, E-mail: shiiyama@nucl.kyushu-u.ac.j [Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Yamamoto, Tomokazu; Takahashi, Tatsuro [Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Guglielmetti, Aurore; Chartier, Alain [CEA-Saclay, DEN/DPC/SCP, 91191 Gif-sur-Yvette (France); Yasuda, Kazuhiro; Matsumura, Syo; Yasunaga, Kazufumi [Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395 (Japan); Meis, Constantin [CEA-Saclay, INSTN, 91191 Gif-sur-Yvette (France)

    2010-10-01

    Molecular dynamics simulations of oxygen Frenkel pairs (FPs) in cerium dioxide (CeO{sub 2}) were carried out in order to understand their kinetic behavior. The results show that an oxygen FP recombine with the vacancy and the interstitial after the vacancy jump preferentially along the <1 0 0> direction. When multiple oxygen FPs are introduced, the interstitials aggregate into a (1 1 1) plate-like cluster at relatively lower temperature lower than 600 K, while they recombine with vacancies at elevated temperatures higher than 900 K within 10 ps. Molecular mechanics calculations of oxygen FPs on a (1 1 1) plane show that the formation energy per a FP decreases with increase of the number of FPs. The theoretical results are consistent with the transmission electron microscopy observations of formation of 1/9<1 1 1>{l_brace}1 1 1{r_brace} oxygen interstitial platelets in CeO{sub 2} under electron irradiation.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Structure and Electronic Properties of Cerium Orthophosphate: Theory and Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Adelstein, Nicole; Mun, B. Simon; Ray, Hannah; Ross Jr, Phillip; Neaton, Jeffrey; De Jonghe, Lutgard

    2010-07-27

    Structural and electronic properties of cerium orthophosphate (CePO{sub 4}) are calculated using density functional theory (DFT) with the local spin-density approximation (LSDA+U), with and without gradient corrections (GGA-(PBE)+U), and compared to X-ray diffraction and photoemission spectroscopy measurements. The density of states is found to change significantly as the Hubbard parameter U, which is applied to the Ce 4f states, is varied from 0 to 5 eV. The calculated structural properties are in good agreement with experiment and do not change significantly with U. Choosing U = 3 eV for LDSA provides the best agreement between the calculated density of states and the experimental photoemission spectra.

  1. 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.

  2. Mechanochemical synthesis and spark plasma sintering of the cerium silicides

    Energy Technology Data Exchange (ETDEWEB)

    Alanko, Gordon A.; Jaques, Brian; Bateman, Allyssa [Department of Materials Science and Engineering, College of Engineering, Boise State University, 1910 University Drive, Boise, ID 83725 (United States); Butt, Darryl P., E-mail: darrylbutt@boisestate.edu [Department of Materials Science and Engineering, College of Engineering, Boise State University, 1910 University Drive, Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Boulevard, Idaho Falls, ID 83401 (United States)

    2014-12-15

    Highlights: • Ce{sub 5}Si{sub 3}, Ce{sub 3}Si{sub 2}, CeSi, CeSi{sub 2−x} and CeSi{sub 2} were mechanochemically synthesized. • Temperature and pressure were monitored to investigate reaction progress. • All syntheses proceeded through a MSR event followed by rapid solid-state diffusion. • Milling time before MSR correlates well with effective heat of formation. • Some synthesized material was densified by spark plasma sintering. - Abstract: The cerium silicides, Ce{sub 5}Si{sub 3}, Ce{sub 3}Si{sub 2}, CeSi, CeSi{sub 2−y}, and CeSi{sub 2−x}, have been prepared from the elements by mechanochemical processing in a planetary ball mill. Preparation of the cerium silicide Ce{sub 5}Si{sub 4} was unsuccessfully attempted and potential reasons for this are discussed. Temperature and pressure of the milling vial were monitored in situ to gain insight into the mechanochemical reaction kinetics, which include a mechanically-induced self-propagating reaction (MSR). Some prepared powders were consolidated by spark plasma sintering to high density. Starting materials, as-milled powders, and consolidated samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results obtained help elucidate key questions in mechanochemical processing of intermetallics, showing first phase formation similar to thin films, MSR ignition times that are composition- and milling speed-dependent, and sensitivity of stable compound formation on the impact pressure. The results demonstrate mechanochemical synthesis as a viable technique for rare earth silicides.

  3. The management of hyperphosphatemia by lanthanum carbonate in chronic kidney disease patients

    Directory of Open Access Journals (Sweden)

    Shigematsu T

    2012-05-01

    Full Text Available Takashi Shigematsu, Yuri Nakashima, Masaki Ohya, Koichi Tatsuta, Daisuke Koreeda, Wataru Yoshimoto, Shintaro Yamanaka, Toshifumi Sakaguchi, Yoshiyuki Hanba, Toru Mima, Shigeo NegiDivision of Nephrology, Department of Internal Medicine, Wakayama Medical University, Wakayama City, Wakayama, JapanAbstract: Hyperphosphatemia has been shown to be involved not only in the onset and progression of secondary hyperparathyroidism but also in vascular calcification. In addition, it influences the clinical course of patients with chronic kidney disease. Phosphate (Pi binder is required in the management of hyperphosphatemia, because dietary Pi restriction and Pi removal by hemodialysis alone are insufficient. Lanthanum carbonate, a powerful Pi binder, has a similar effect to aluminum hydroxide in reducing serum Pi levels. As it is excreted via the liver, lanthanum carbonate has an advantage in patients with renal failure. The effect of lanthanum carbonate on serum Pi levels is almost two times higher than that of calcium (Ca carbonate, which is commonly used. Lanthanum carbonate and Ca carbonate have an additive effect. Worldwide, there is 6 years worth of clinical treatment data on lanthanum carbonate; however, we have 3 years of clinical use in Japanese patients with hyperphosphatemia. No serious side effects have been reported. However, the most important concern is bone toxicity, which has been observed with use of aluminum hydroxide. For this study, clinical research involved analysis of bone biopsies. Although osteomalacia is the most noticeable side effect, this was not observed. Both the high- and the low-turnover bone disease concentrated into a normal bone turnover state. However, as the authors have less than 10 years' clinical experience with lanthanum carbonate, patients should be monitored carefully. In addition, it is necessary to demonstrate whether potent treatment effects on hyperphosphatemia improve the long-term outcome

  4. Effects of powdered versus liquid barium on the viscosity of fluids used in modified swallow studies

    Energy Technology Data Exchange (ETDEWEB)

    Baron, J.; Alexander, T. [Univ. of Alberta, Dept. of Radiology, Edmonton, Alberta (Canada)

    2003-06-01

    To determine if the viscosity of thickened juice mixtures used in modified barium swallow studies significantly changes with the addition of powdered barium. We also describe a test formulation created using liquid barium, which has a negligible effect on juice viscosity. The viscosities of water and standardized honey- and nectar-consistency juices mixed with different amounts of powdered barium were measured by timing the laminar flow of a given initial hydrostatic head of fluid under gravity though an orifice of fixed diameter. Standardized juices were then mixed with a liquid formulation of barium and with measured quantities of water to produce viscosities that more closely equated with those of the standardized juices. With the addition of powdered barium, viscosity increased in all fluids, most markedly with the nectar-consistency juice. Liquid barium formulations maintained the viscosities of the original thickened juices. Rendering juices radio-opaque with barium powder results in dramatic increases in the viscosity of the resulting mixture and compromises diagnostic accuracy. Liquid barium preparations have the advantage that they can be rapidly and accurately dispensed by syringe, and their use does not significantly increase the viscosity of the preparation. (author)

  5. Sponge-associated bacteria mineralize arsenic and barium on intracellular vesicles

    Science.gov (United States)

    Keren, Ray; Mayzel, Boaz; Lavy, Adi; Polishchuk, Iryna; Levy, Davide; Fakra, Sirine C.; Pokroy, Boaz; Ilan, Micha

    2017-01-01

    Arsenic and barium are ubiquitous environmental toxins that accumulate in higher trophic-level organisms. Whereas metazoans have detoxifying organs to cope with toxic metals, sponges lack organs but harbour a symbiotic microbiome performing various functions. Here we examine the potential roles of microorganisms in arsenic and barium cycles in the sponge Theonella swinhoei, known to accumulate high levels of these metals. We show that a single sponge symbiotic bacterium, Entotheonella sp., constitutes the arsenic- and barium-accumulating entity within the host. These bacteria mineralize both arsenic and barium on intracellular vesicles. Our results indicate that Entotheonella sp. may act as a detoxifying organ for its host. PMID:28233852

  6. Lanthanum and Neodymium Doped Barium Ferrite-TiO₂/MCNTs/poly(3-methyl thiophene) Composites with Nest Structures: Preparation, Characterization and Electromagnetic Microwave Absorption Properties.

    Science.gov (United States)

    Zhao, Jie; Yu, Jian; Xie, Yu; Le, Zhanggao; Hong, Xiaowei; Ci, Suqin; Chen, Junhong; Qing, Xiaoyan; Xie, Weijie; Wen, Zhenhai

    2016-02-09

    We report herein the synthesis of a novel nest structured electromagnetic composite through in-situ chemical polymerization of 3-methyl thiophene (3MT) in the presence of the BaFe11.92(LaNd)0.04O19-TiO2 (BFTO) nanoparticles and MCNTs. As an absorbing material, the BFTO/MCNTs/P3MT/wax composites were prepared at various loadings of BFTO/MCNTs/P3MT (0.2:0.10:1.0 ~ 0.2:0.30:1.0), and they exhibited strong microwave absorption properties in the range of 1.0-18 GHz. When the loading of BFTO/MCNTs/P3MT is 0.2:0.30:1.0, the composite has a strongest absorbing peak at 11.04 GHz, and achieves a maximum absorbing value of -21.56 dB. The absorbing peak position moves to higher frequencies with the increase of MCNTs content. The mechanism for microwave absorption of these composites has been explained in detail.

  7. Optimization of the electrochemical pre-concentration of trivalent lanthanum from aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, Jamie L. [Washington State Univ., Pullman, WA (United States). Chemistry Dept.; Clark, Sue B. [Washington State Univ., Pullman, WA (United States). Chemistry Dept.; Pacific Northwest National Laboratory, Richland, WA (United States)

    2016-07-01

    Electrochemical pre-concentration has been shown to effectively increase sample sensitivity and decrease processing time; however, the basic mechanism and optimal conditions of the technique remain unknown, specifically for lanthanides. To gain a better understanding of the mechanism of action, the aqueous solution conditions required to maximize the electrochemical pre-concentration of lanthanum (La) were studied. Parameters investigated included pH, applied potential, and ionic strength. To further optimize and elucidate the mechanism of lanthanide pre-concentration, specific interactions of lanthanum with the mercury film electrode were studied. Three possible mechanisms were proposed based on preliminary observations, including ligand bridging, hydroxide formation, and amalgamation.

  8. [Efficacy and safety of lanthanum carbonate in chronic kidney disease patients with hyperphosphataemia].

    Science.gov (United States)

    Laville, Maurice

    2011-06-01

    Hyperphosphataemia is a frequent complication in patients with chronic kidney disease and is associated with increased cardiovascular morbidity. Lanthanum carbonate is a calcium-free phosphate binder indicated in patients with chronic kidney disease. Its digestive absorption is minimal (carbonate have been assessed in randomized trials. The most common side effects reported were gastrointestinal and occurred with a similar incidence than with placebo and other phosphate binders. Hypercalcemia was less frequent than with calcium carbonate. This review highlights pharmacokinetic, pharmacodynamic and clinical (efficacy and safety) properties of lanthanum carbonate and discusses its place in the management of hyperphosphataemia in patients with chronic kidney disease.

  9. Study of Complexes of Lanthanum with Amino Acids by Titration Calorimeter

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The stability constants and thermodynamic functions for complexes of lanthanum with eight kind of amino acids according to 1:1 and 1:2 in proportion have been determined by titration calorimeter at 298. 15 K. The enthalpy change makes a predominant contribution to the stability of these complexes. The ring in amino acid associated with lanthanum ion helps to enhance the stability of complexes. Steric effectsbetween rings in complexes leads to that the equilibrium constants of reaction of the complexes (1:2) ismuch less than that of the complexes (l:1).

  10. Influence of nimodipine, verapamil and lanthanum on histamine release from human basophils

    DEFF Research Database (Denmark)

    Jensen, C B; Thastrup, Ole; Norn, S;

    1987-01-01

    Our previous studies suggest that the membrane content of sialic acid influences histamine release from human basophils by interfering with the transmembraneous calcium fluxes preceding histamine release. In this study we investigated a possible interaction between membrane sialic acid...... and the calcium channels, using the calcium antagonists nimodipine, verapamil and lanthanum. Anti-IgE-induced histamine release was inhibited by verapamil, nimodipine and lanthanum. When cells were pretreated with sialidase in order to remove sialic acid from the cell membrane, the inhibitory action of nimodipine...

  11. Thermodynamic Assessment of Interaction Relation between Lanthanum and Constituent Elements in Sn-Pb Alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The interaction relation between lanthanum and the constituent elements of Sn-Pb alloy system was analyzed by using the thermodynamic models including Miedema formation energy model for binary system, Tanaka modification by excess entropy and the Chou geometric model for ternary system. The thermodynamic calculaton results show that lanthanum has higher affinity for Sn in the Sn-Pb system. This is an important foundation for the improvement of the metallurgical properties of Sn-Pb solder alloy by adding rare earth elements.

  12. BARIUM SULPHATE ABSORPTION AND THE SERUM DIAGNOSIS OF SYPHILIS.

    Science.gov (United States)

    Noguchi, H; Bronfenbrenner, J

    1911-02-01

    The so-called syphilitic antibodies can be removed from a serum by means of absorption with barium sulphate. The removal is due either to an adsorption or a mechanical absorption. The activity of the syphilitic antibodies is thereby unimpaired. The readiness with which the absorption is accomplished with barium sulphate varies considerably with different syphilitic sera. That barium sulphate exerts the same absorbing effect upon non-syphilitic serum components is made evident by the interfering property which the latter manifest in the absorption experiment of the syphilitic antibodies. The selective removal of the serum components, other than the syphilitic antibodies, by means of barium sulphate absorption is, therefore, impossible. On the other hand, a partial removal of these components, with but little removal of the syphilitic antibodies, may be effected when the content of a given serum is poor in syphilitic antibodies and comparatively rich in the indifferent serum components. But this is impossible if the conditions are reversed. The main reasons why some negative syphilitic sera may be so modified by the barium sulphate treatment as to give positive reactions, are explained below, but these apply only to those methods in which inactivated serum is employed. The inactivation reduces the antibody content to about one-fourth to one-fifth of the original. When the serum is very rich in antibodies, this does not affect the result of the fixation test. But when the amount of the antibodies is small, the process of inactivation creates conditions quite unexpected. It may produce such a condition that a given amount of the serum contains, after inactivation, only one or two antibody units, while the other serum components remain undiminished. Here one must not lose sight of the vital fact that these apparently indifferent serum constituents are not at all indifferent in the fixation processes. They may possess affinities which are similar to those of complement

  13. 铝酸钡与氢氧化钡脱硫过程比较%Comparison of Barium Aluminate and Barium Hydroxide Desulfurization Process

    Institute of Scientific and Technical Information of China (English)

    张念炳; 黎志英; 丁彤

    2012-01-01

    The seed precipitation liquor was desulfurized with barium aluminate and barium hydroxide respectively. The desulfurization slag was characterized by XRD analysis, and the desulfurization process was compared. The results show that barium hydroxide exceeds barium aluminate with better desulfurization in terms of effect, speed and duration. In the desulfurization process with barium aluminate, 2BaO · Al2O3 · 5H2O is firstly produced in the reaction of barium aluminate with alkali, and then it reacts with sodium sulfate and sodium carbonate. To compare, Ba(OH)2 · 8H2O directly reacts with sodium sulfate and sodium carbonate in the desulfurization process with barium hydroxide. Both of desulfurization reaction processes can be described with "shrinking core model".%用铝酸钡和氢氧化钡对种分母液进行脱硫试验,对脱硫渣进行XRD分析,并比较脱硫过程.结果表明,氢氧化钡的脱硫效果更好,脱硫完成时间更短,速率更快;铝酸钡先与碱液反应生成2BaO·Al2O3·5H2O,再与硫碱和碳碱反应,而氢氧化钡直接与硫碱和碳碱反应,脱硫过程均可用未反应核模型描述.

  14. Back bombardment for dispenser and lanthanum hexaboride cathodes

    Directory of Open Access Journals (Sweden)

    Mahmoud Bakr

    2011-06-01

    Full Text Available The back bombardment (BB effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathode’s temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC and lanthanum hexaboride (LaB_{6} thermionic rf gun cathodes. For each, particle simulation codes are used to simulate the BB effect and electron beam dynamics in a thermionic rf gun cathode. A semiempirical equation is also used to investigate the stopping range and deposited heat power of BB electrons in the cathode material. A numerical simulation method is used to calculate the change of the cathode temperature and current density during a single macropulse. This is done by solving two differential equations for the rf gun cavity equivalent circuit and one-dimensional thermal diffusion equation. High electron emission and small beam size are required for generation of a high-brightness electron beam, and so in this work the emission properties of the cathode are taken into account. Simulations of the BB effect show that, for a pulse of 6  μs duration, the DC cathode experiences a large change in the temperature compared with LaB_{6}, and a change in current density 6 times higher. Validation of the simulation results is performed using experimental data for beam current beyond the gun exit. The experimental data is well reproduced using the simulation method.

  15. Lanthanum manganate based cathodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Juhl Joergensen, M.

    2001-07-01

    Composite cathodes for solid oxide fuel cells were investigated using electrochemical impedance spectroscopy and scanning electron microscopy. The aim was to study the oxygen reduction process in the electrode in order to minimise the voltage drop in the cathode. The electrodes contained a composite layer made from lanthanum strontium manganate (LSM) and yttria stabilised zirconia (YSZ) and a layer of pure LSM aimed for current collection. The performance of the composite electrodes was sensitive to microstructure and thickness. Further, the interface between the composite and the current collecting layer proved to affect the performance. In a durability study severe deg-radation of the composite electrodes was found when passing current through the electrode for 2000 hours at 1000 deg. C. This was ascribed to pore formation along the composite interfaces and densification of the composite and current collector microstructure. An evaluation of the measurement approach indicated that impedance spectroscopy is a very sensitive method. This affects the reproducibility, as small undesirable variations in for instance the microstructure from electrode to electrode may change the impedance. At least five processes were found to affect the impedance of LSM/YSZ composite electrodes. Two high frequency processes were ascribed to transport of oxide ions/oxygen intermediates across LSM/YSZ interfaces and through YSZ in the composite. Several competitive elementary reaction steps, which appear as one medium frequency process in the impedance spectra, were observed. A low frequency arc related to gas diffusion limitation in a stagnant gas layer above the composite structure was detected. Finally, an inductive process, assumed to be connected to an activation process involving segregates at the triple phase boundary between electrode, electrolyte and gas phase, was found. (au)

  16. Effect of Lanthanum on Major Microbial Populations in Red Soil

    Institute of Scientific and Technical Information of China (English)

    CHUHAIYAN; WANGJUNHUA; 等

    2001-01-01

    Pure culture and pot culture experiments were carried out to study the effect of lanthanum(La)on bacteria,actinomyces and fungus,and some microbial physiological groups,nitrifir,azotobacter and phos-phobacteria in a red soil taken form the Ecological Experimental Station of Red Soil,the Chinese Academy of Sciences,Jiangxi Province.LaCl3 was added into media at levels of 0,25,50,100,150,200,250 and 500 mg L-1 in the pure culture experiment ,and into soil samples in porcelain pots before rice growing at levles of 0,6,30,150,300,600 and 900 mg kg-1 dry soil in the pot culture experiment.The populations of the three soil microbes in the pure cultre experiment decreased with the addition level of La,indicating that La was toxic to the soil microbes in pure culture ,and the sensitivity of the 3 major mircrobial types to La was in a decreasing order of actinomyces>bacteria>fungus.In the pot experiment,La had slightly stimulaive effect on soil bacteria and actinomyces when applied at olw concentrations while had inhibitory effect on soil bacteria,actinomyces and fungus at high concentrations.When the concentration of La Was low,soil azotobacter was stimulated slightly while soil nitrifier was stimulated strongly and the maximum increase was up to 50%.When the concentration of La was highy,both soil aztobacter and nitrifier ware inhibited ,and the inhibition of La to the nitrifier increased with La conentration,La added at all the levels had stimulative effect on soil inorgaic and organic phosphobacteria.Among the 4 physiological groups,soil nitrifier was most sensitive to La,so,it migh be reasonble to assume that soil nitrifier was a sensitive indicator for evaluating the biological and environmental effects of rare earths.

  17. Effect of Lanthanum on Major Microbial Populationsin Red Soil

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Pure culture and pot culture experiments were carried out to study theeffect of lanthanum (La) on bacteria, actinomyces and fungus, and somemicrobial physiological groups, nitrifier, azotobacter andphosphobacteria, in a red soil taken form the Ecological ExperimentalStation of Red Soil, the Chinese Academy of Sciences, Jiangxi Province.LaCl{3 was added into media at levels of 0, 25, 50, 100, 150,200, 250 and 500 mg L-1 in the pure culture experiment, and intosoil samples in porcelain pots before rice growing at levels of 0, 6,30, 150, 300, 600 and 900 mg kg-1 dry soil in the pot cultureexperiment. Thepopulations of the three soil microbes in the pure culture experimentdecreased with the addition level of La, indicating that La was toxicto the soil microbes in pure culture, and the sensitivity of the 3major microbial types to La was in a decreasing order ofactinomyces > bacteria > fungus. In the pot experiment, Lahad slightly stimulative effect on soil bacteria and actinomyces whenapplied at low concentrations while had inhibitory effect on soilbacteria, actinomyces and fungus at high concentrations. When theconcentration of La was low, soil azotobacter was stimulated slightlywhile soil nitrifier was stimulated strongly and the maximum increasewas up to 50%. When the concentration of La was high, both soilazotobacter and nitrifier were inhibited, and the inhibition of La tothe nitrifier increased with La concentration. La added at all thelevels had stimulative effect on soil inorganic and organicphosphobacteria. Among the 4 physiological groups, soil nitrifier wasmost sensitive to La, so, it might be reasonable to assume that soilnitrifier was a sensitive indicator for evaluating the biological andenvironmental effects of rare earths.

  18. Influence of lanthanum distribution on dielectric and ferroelectric properties of BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Khokhar, Anita [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India); Goyal, Parveen K., E-mail: goyalphy@gmail.com [Department of Physics, ARSD College, University of Delhi, Dhaula Kuan, New Delhi 110 021 (India); Thakur, O.P. [Electroceramics Group, Solid State Physics Laboratory, Lucknow Road, Delhi 110 054 (India); Shukla, A.K. [Department of Physics, Amity Institute of Applied Sciences, Amity University, Noida 201301 (India); Sreenivas, K., E-mail: kondepudysreenivas@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India)

    2015-02-15

    Structural and electrical properties of Lanthanum substituted barium bismuth titanate BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} (0 ≤ x ≤ 0.50) ceramics prepared by conventional solid-state reaction method have been investigated. Raman spectra reveals the distribution of lanthanum into the perovskite layers and (Bi{sub 2}O{sub 2}){sup 2+} layers of BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics. Room temperature dielectric constant (ε′) increases and considerable reduction in the low frequency (10{sup −2} to 10 Hz) dielectric losses and in dc conductivity (σ{sub dc}) are seen with lanthanum substitution. A critical La content of x ∼0.20 in BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} exhibits a well-defined relaxor behavior as seen from the temperature and frequency dependence of the dielectric parameters ε′(T) and ε″(T). The dielectric data fit well to the modified Curie–Weiss law and the Lorentz-type relation and show increasing diffuseness in the phase transition with increasing La content. The temperature dependence of the characteristic relaxation time obtained from the Cole–Cole model shows a good fit to the non-linear Vogel–Fulcher relation. Improvements in the remnant polarization and a stable piezoelectric charge coefficient are seen up to a La content of x ∼0.20. The observed increase in dielectric loss and σ{sub dc} in addition to the diminished ferroelectric/piezoelectric properties for higher La content are explained in terms of changing oxygen vacancy concentration and structural relaxation due to the preferential incorporation of La into the (Bi{sub 2}O{sub 2}){sup 2+} layers as evidenced through the Raman spectroscopy. - Highlights: • La distribution in BaBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} ceramics is analyzed through Raman spectroscopy. • Low and a nearly constant loss over wide frequency range (10{sup −2}–10{sup 7} Hz) obtained. • Critical La content x = 0.2 identified for high resistivity and ideal relaxor

  19. Lanthanum carbonate oral powder: satisfaction, preference and adherence in French and Spanish patients with end-stage renal disease

    Science.gov (United States)

    Keith, Michael; de Sequera, Patricia; Clair, François; Pedersini, Riccardo

    2016-01-01

    Background Phosphate binders, such as lanthanum carbonate, control elevated serum-phosphate levels in patients with end-stage renal disease (ESRD). Lanthanum carbonate is available in oral powder and tablet form. The aim of this survey was to investigate satisfaction with, preference for, and adherence to lanthanum carbonate oral powder in patients with ESRD. Scope Patients from France and Spain who had been taking lanthanum carbonate powder for at least 4 weeks, and who had experience of other phosphate binders of any formulation, were asked to complete an online or telephone survey. Treatment satisfaction was measured using the Treatment Satisfaction Questionnaire for Medication-9; preference was measured using 5-point Likert scale agreement ratings; and adherence was measured using the Morisky Medication Adherence Scale-4. Data were evaluated using bivariate analyses. Findings Overall, 160 patients participated (80 per country). Lanthanum carbonate powder was reported to have a higher effectiveness rating (psubject to change over time. Although most participants completed the online survey in this study, a telephone survey was used for individuals who could not access the online version; if only one method of data recording had been used, there may have been reduced variation in responses. Conclusion Patients with ESRD report increased satisfaction with and preference for lanthanum carbonate powder over other formulations, suggesting that lanthanum carbonate powder is more convenient and easier to use than other formulations. PMID:27803726

  20. 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.

  1. 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...

  2. 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...

  3. Transmittance and Refractive Index of the Lanthanum Strontium Aluminium Tantalum Oxide Crystal

    Institute of Scientific and Technical Information of China (English)

    HU Bo-Qing; WANG Xiao-Ming; ZHOU Tang; ZHAO Zong-Yuan; WU Xing; CHEN Xiao-Long

    2001-01-01

    The lanthanum strontium aluminium tantalum oxide (LSAT) crystal is grown by means of a floating or pulling method. Its optical transmittance, refractive indices in visible and near-infrared areas and its dispersion curve are reported. The transparence range of LSAT is from 0.45 to 4.2μm and its refractive index is 2.0244.

  4. Thermoelectric power and electrical conductivity of strontium-doped lanthanum manganite

    DEFF Research Database (Denmark)

    Ahlgren, E.O.; Poulsen, F.W.

    1996-01-01

    Thermoelectric power and electrical conductivity of pure and 5, 10 and 20% strontium-doped lanthanum manganite are determined as function of temperature in air and of P-O2 at 1000 degrees C. At high temperatures the thermoelectric power is negative. Both thermoelectric power and conductivity...

  5. Synthesis and Characterization of Lanthanum Complexes with Amino Acid Schiff Base

    Institute of Scientific and Technical Information of China (English)

    张秀英; 张有娟; 杨林

    2001-01-01

    Six new complexes of lanthanum with amino acid Schiff base ligands, A-F, were prepared in methanol-aqueous solution. The composition and properties of the title complexes were characterized by elemental analysis, molar conductance, infrared, electronic spectra, 1H NMR, thermogravimetric and differential thermal analysis.

  6. Study on eruption of heat for Escherichia coil B aroused by lanthanum nitrate and its mechanism

    Institute of Scientific and Technical Information of China (English)

    Guosheng LIU; Zhilin RAN; Hailei WANG; Yi LIU; Ping SHEN; Yan LU

    2008-01-01

    Biological effect of rare-earth lanthanum nitrate on the growth of Escherichia coli B was studied using the calorimetric method. There were exceptional changes on the growth thermogenic curves for high concentrations of lanthanum nitrate. For example, the peak high, the total quantity of heat (Q) of cultures and the growth rate constants (k) are evidently increased when compared with normal E. Coli B cultures. When the concentration of lanthanum nitrate was at 300 mg/L and 500 rag/L, the Q of the cultures reached 3.89 and 2.54 times of normal cultures, respectively. The survivability of cells and the biomass of the cultures were measured using biological methods and the results show that the growth and multiplication of cells were inhibited and that the biomass decreased at high concentration of lanthanum nitrate. These revealed that the inhibiting cells discharged more quantity of heat than the normal growing cells. We named this phenomenon as "eruption of heat". It was suggested that the mechanism for the eruption of heat was that La3+ ion damages the outer cell membrane and increases its permeability and the proton-electron poten-tial energy across the cell membrane was reduced or couldn't even be initiated. Energy could not be translated into ATP effectively in the course of oxidative phosphor-ylation resulting in heat release. So, the growth of the cells was inhibited due to scarceness of energy ATP.

  7. Structural characterization and properties of lanthanum 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

    2007-12-30

    Sulfide-stain resistance of La-passivated, unpassivated and Cr-passivated tinplate was measured using a cysteine tarnish test. Corrosion behavior of these tinplates was investigated using electrochemical impedance spectroscopy (EIS) measurement. The morphology, composition and thickness of lanthanum film were studied by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence spectrometry (XRF), respectively. La-passivation treatment remarkably enhances sulfide-stain resistance of tinplate, and sulfide-stain resistance of La-passivated tinplate is slightly higher than that of Cr-passivated tinplate. La-passivation treatment also significantly improves corrosion protection property of tinplate. In contact with 3.5% NaCl solution, corrosion resistance of La-passivated tinplate is close to that of Cr-passivated tinplate, and in contact with 0.1 M citric-citrate buffer solution, corrosion resistance of La-passivated tinplate is higher than that of Cr-passivated tinplate. Lanthanum film is composed of spherical particles about 50-1000 nm in diameter, while most part of tinplate's surface is covered with the small particles about 50-200 nm. The film mainly consists of lanthanum and oxygen, which mainly exist as La{sub 2}O{sub 3} and its hydrates such as La(OH){sub 3} and LaOOH. The amount of lanthanum in the film is about 0.0409 g/m{sup 2}.

  8. Eutrophication management in surface waters using lanthanum modified bentonite: a review

    NARCIS (Netherlands)

    Copetti, D.; Finsterle, K.; Marziali, L.; Stefani, F.; Tartari, G.; Douglas, G.C.; Reitzel, K.; Spears, B.M.; Winfield, I.J.; Crosa, G.; Yasseri, S.; Lurling, M.F.L.L.W.

    2016-01-01

    This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales. The available

  9. Humic substances interfere with phosphate removal by lanthanum modified clay in controlling eutrophication

    NARCIS (Netherlands)

    Lurling, M.F.L.L.W.; Waaijenberg, G.W.A.M.; Oosterhout, J.F.X.

    2014-01-01

    The lanthanum (La) modified bentonite Phoslock® has been proposed as dephosphatisation technique aiming at removing Filterable Reactive Phosphorus (FRP) from the water and blocking the release of FRP from the sediment. In the modified clay La is expected the active ingredient. We conducted controlle

  10. Highly Selective Water Adsorption in a Lanthanum Metal-Organic Framework

    NARCIS (Netherlands)

    Plessius, R.; Kromhout, R.; Dantas Ramos, A.L.; Ferbinteanu, M.; Mittelmeijer-Hazeleger, M.C.; Krishna, R.; Rothenberg, G.; Tanase, S.

    2014-01-01

    We present a new metal-organic framework (MOF) built from lanthanum and pyrazine-2,5-dicarboxylate (pyzdc) ions. This MOF, [La(pyzdc)(1.5)(H2O)(2)]center dot 2H(2)O, is microporous, with 1D channels that easily accommodate water molecules. Its framework is highly robust to dehydration/hydration

  11. Nickel/magnesium-lanthanum mixed oxide catalyst in the Kumada-coupling.

    Science.gov (United States)

    Kiss, Arpád; Hell, Zoltán; Bálint, Mária

    2010-01-21

    A new, heterogeneous, magnesium-lanthanum mixed oxide solid base-supported nickel(ii) catalyst was developed. The catalyst was used successfully in the Kumada coupling of aryl halides, especially aryl bromides. The optimal reaction conditions of the coupling were determined.

  12. The air oxidation behavior of lanthanum ion implanted zirconium at 500 deg. C

    CERN Document Server

    Peng, D Q; Chen, X W; Zhou, Q G

    2003-01-01

    The beneficial effect of lanthanum ion implantation on the oxidation behavior of zirconium at 500 deg. C has been studied. Zirconium specimens were implanted by lanthanum ions using a MEVVA source at energy of 40 keV with a fluence range from 1x10 sup 1 sup 6 to 1x10 sup 1 sup 7 ions/cm sup 2 at maximum temperature of 130 deg. C, The weight gain curves were measured after being oxidized in air at 500 deg. C for 100 min, which showed that a significant improvement was achieved in the oxidation behavior of zirconium ion implanted with lanthanum compared with that of the as-received zirconium. The valence of the oxides in the scale was analyzed by X-ray photoemission spectroscopy; and then the depth distributions of the elements in the surface of the samples were obtained by Auger electron spectroscopy. Glancing angle X-ray diffraction at 0.3 deg. incident angles was employed to examine the modification of its phase transformation because of the lanthanum ion implantation in the oxide films. It was obviously fou...

  13. Humic substances interfere with phosphate removal by lanthanum modified clay in controlling eutrophication

    NARCIS (Netherlands)

    Lurling, M.F.L.L.W.; Waaijenberg, G.W.A.M.; Oosterhout, J.F.X.

    2014-01-01

    The lanthanum (La) modified bentonite Phoslock® has been proposed as dephosphatisation technique aiming at removing Filterable Reactive Phosphorus (FRP) from the water and blocking the release of FRP from the sediment. In the modified clay La is expected the active ingredient. We conducted

  14. Propagation of surface plasmon polariton in the single interface of gallium lanthanum sulfide and silver

    Science.gov (United States)

    Sagor, Rakibul Hasan; Saber, Md. Ghulam; Amin, Md. Ruhul

    2014-03-01

    The propagation characteristics of the surface-plasmon-polariton (SPP) mode in the single interface of silver (Ag) and gallium lanthanum sulfide (GLS) have been studied both analytically and numerically. The obtained numerical results show an excellent agreement with the analytical ones. The locations of the spatial resonance point along the direction of propagation were determined for the dielectric and the metal.

  15. Crystal growth and characterization of LaMAl 11O 19 lanthanum aluminates

    Science.gov (United States)

    Laville, F.; Lejus, A. M.

    1983-10-01

    New magnetoplumbite-type lanthanum aluminates with the formula LaMAl 11O 19 (M 2+ = Ni 2+, Co 2+, Fe 2+, Mg 1- xMn x, 0≤ x ≤1, have been grown as large single crystals using the Verneuil process or the floating zone method. Some characteristics of these crystals are given.

  16. Barium Swallow Findings in the Evaluation of Patients with Dysphagia

    Directory of Open Access Journals (Sweden)

    Amirhosein Hashemi Attar

    2011-05-01

    Full Text Available Background/Objective: Dysphagia is a subjective"nsensation of difficulty in swallowing that has a wide"nrange of etiologies from psychosomatic disorders"nto high grade neoplasms. In this study we evaluated"nbarium swallow findings of patients with dysphagia."nPatients and Methods: We evaluated 200 patients"n(117 men, 83 women; mean age, 49.6 years with"ncomplaint of dysphagia. Fluoroscopic barium"nswallow was done for all the patients and they were"nreviewed for primary peristalsis (presence or absence,"nAbstracts"nS62 Iran J Radiol 2011, 8 (Supp.1"nAbstracts"nimpaired lower esophageal sphincter, esophageal dilatation, delayed emptying of barium, nonperistaltic contractions, stricture and filling defects. Clinical and in some cases endoscopic or manometric follow up was done for all patients."nResults: We had 134 (67% normal barium swallow"nexams with uncomplicated clinical courses. Sixty"nsix patients (33% had abnormal imaging findings"nincluding stricture in 24 patients (12%, filling defect"nin 12 patients (6% and mucosal abnormality in 14"n(7% patients (six cases of mucosal irregularity, three"ncases of mucosal ulceration and five cases of mucosal"nherniation, Bird's beak sign in three patients (1.5%,"ntertiary spasm in six patients (3% and hiatal hernia in"nseven patients (3.5%."nConclusion: In the majority of patients with dysphagia,"nbarium swallow is the only paraclinical study needed"nto plan proper treatment. If radiographic findings are"nequivocal, endoscopy or manometry may be required"nfor more certain diagnosis.

  17. Radiological response of lanthanum guiding seeds in brachytherapy implants; Resposta radiologica de sementes guia de lantanio em implantes braquiterapicos

    Energy Technology Data Exchange (ETDEWEB)

    Silva, L.S.R.; Machado, E.D.P., E-mail: lais26@globo.com [Centro Federal de Educacao Tecnologica de Minas Gerais, Belo Horizonte, MG (Brazil). Departamento de Engenharia de Materiais; Campos, T.P.R. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Roberto, W.S. [Centro Federal de Educacao Tecnologica de Minas Gerais, Belo Horizonte, MG (Brazil). Departamento de Fisica e Matematica

    2013-08-15

    Ceramic seeds with La-139 incorporated were synthesized to be used as radiological guides in brachytherapy implants. The synthesis was performed based on the sol-gel method. The seeds were subjected to characterization by Scanning Electron Microscopy, X-ray diffraction and Energy-Dispersive X-ray Spectroscopy. Furthermore, the contrast from a radiographic film was evaluated to lanthanum, samarium and holmium seeds. Radiological response on a phantom at different depths with lanthanum seeds and metal seeds was also investigated. Based on the values of contrast, the synthesized lanthanum seeds can be considered efficient as radiological guides when implanted together with pure Ho-165 and Sm-152 seeds. (author)

  18. Study on Carbon Nanotubes Prepared from Catalytic Decomposition of CH4 over Lanthanum Containing Ni-Base Catalysts

    Institute of Scientific and Technical Information of China (English)

    Wang Minwei; Li Fengyi

    2004-01-01

    A series of lanthanum containing Ni-base catalysts were prepared by citric acid complex method.Carbon nanotubes (CNT) were synthesized bY catalytic decomposing CH4 over these catalysts and characterized by XRD, TEM and TGA.It is found that the addition of lanthanum can not increase the yield of carbon nanotube, but can make the diameter of carbon nanotube thinner and even.The more the lanthanum addsr, the thinner the diameter of CNTs becomes.With the CNTs prepared on Ni-Mg catalyst, the CNTs prepared on Ni-La-Mg catalyst has better crystallinity and thermal stability.

  19. Investigation on the effects of milling atmosphere on synthesis of barium ferrite/magnetite nanocomposite

    NARCIS (Netherlands)

    Molaei, M.J.; Ataie, A.; Raygan, S.; Picken,n S.J.

    2011-01-01

    In this research, barium ferrite /magnetite nanocomposites synthesized via a mechano-chemical route. Graphite was used in order to reduce hematite content of barium ferrite to magnetite to produce a magnetic nanocomposite. The effects of processing conditions on the powder characteristics were inves

  20. Complete sulphate removal from neutralised acidic mine drainage with barium carbonate

    CSIR Research Space (South Africa)

    Swanepoel, H

    2012-03-01

    Full Text Available -barium-calcium) Desalination process which uses barium salts to further reduce the sulphate concentration to acceptable levels with the added advantage that sulphate removal can be controlled due to the low solubility of BaSO4. This paper reports on the results...

  1. New efficient catalyst for ammonia synthesis: barium-promoted cobalt on carbon

    DEFF Research Database (Denmark)

    Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus

    2002-01-01

    Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia......Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia...

  2. Obtaining of Nanostructured Powders of Barium and Strontium Hexaferrite by the Polymer Precursor Method

    Directory of Open Access Journals (Sweden)

    V.G. Kostishyn

    2015-12-01

    Full Text Available Studied the possibility of obtaining by precursors in the polymer nanostructured powders of barium hexaferrite BaFe12O19 and strontium hexaferrite SrFe12O19. The reagents were used as starting barium nitrate, strontium nitrate and ferric nitrate nonahydrate (III, and polyethylene glycol-400 used this technology as a polymer.

  3. Control on Crystal Forms of Ultrafine Barium Carbonate Particles and Study on its Mechanism

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Barium carbonate particles were prepared by using homogeneous precipitation method and co-precipitation method respectively. Through adding different crystalline controlling modifiers, Barium carbonate particles in five different shapes including linear, needle-like, pillarlike, sphere-like and dumbbell-like were synthesized. These particles were characterized by SEM and XRD, and their synthetic mechanism was discussed in this paper.

  4. Electrical conductivity studies of nanocrystalline lanthanum silicate synthesized by sol-gel route

    Energy Technology Data Exchange (ETDEWEB)

    Nallamuthu, N.; Prakash, I. [Department of Physics, Pondicherry University, Puducherry 605 014 (India); Satyanarayana, N., E-mail: nallanis2000@yahoo.com [Department of Physics, Pondicherry University, Puducherry 605 014 (India); Venkateswarlu, M. [R and D, Amara Raja Batteries Ltd., Tirupati 517520, AP (India)

    2011-01-28

    Research highlights: > Nanocrystalline La{sub 10}Si{sub 6}O{sub 27} material was synthesized by sol-gel method. > TG/DTA curves predicted the thermal behavior of the material. > FTIR spectra confirmed the formation of SiO{sub 4} and La-O network in the La{sub 10}Si{sub 6}O{sub 27}. > XRD patterns confirmed the formation of pure crystalline La{sub 10}Si{sub 6}O{sub 27} phase. > The grain interior and the grain boundary conductivities are evaluated. - Abstract: Nanocrystalline apatite type structured lanthanum silicate (La{sub 10}Si{sub 6}O{sub 27}) sample was synthesized by sol-gel process. Thermal behavior of the dried gel of lanthanum silicate sample was studied using TG/DTA. The structural coordination of the dried gel of lanthanum silicate, calcined at various temperatures, was identified from the observed FTIR spectral results. The observed XRD patterns of the calcined dried gel were compared with the ICDD data and confirmed the formation of crystalline lanthanum silicate phase. The average crystalline size of La{sub 10}Si{sub 6}O{sub 27} was calculated using the Scherrer formula and it is found to be {approx}80 nm. The observed SEM images of the lanthanum silicate indicate the formation of the spherical particles and the existence of O, Si and La in the lanthanum silicate are confirmed from the SEM-EDX spectrum. The grain and grain boundary conductivities are evaluated by analyzing the measured impedance data, using winfit software, obtained at different temperatures, of La{sub 10}Si{sub 6}O{sub 27} sample. Also, the observed grain and grain boundary conductivity behaviors of the La{sub 10}Si{sub 6}O{sub 27} sample are analysed using brick layer model. The electrical permittivity and electrical modulus were calculated from the measured impedance data and were analyzed by fitting through the Havriliak and Negami function to describe the dielectric relaxation behavior of the nanocrystalline lanthanum silicate.

  5. Clinical and pharmacoeconomic profile of lanthanum carbonate treatment of hyperphosphataemia in chronic renal dialysis patients

    Directory of Open Access Journals (Sweden)

    Mario Eandi

    2010-03-01

    Full Text Available Hyperphosphatemia is recognized as a principal mineral disorder in chronic kidney disease (CKD that leads to the development of secondary hyperparathyroidism. Approximately 70% of patients with end-stage renal disease (ESRD and dialysis have hyperphosphataemia, which is associated with renal osteodystrophy, metastatic calcification and increased mortality and morbidity. Despite dietary restriction and dialysis, most patients will require a phosphate-binding agent to treat this condition.Lanthanum carbonate is an new, potent, selective, no-resin, non-calcium phosphate binder that retains high affinity for phosphate over a wide pH range, does not bind bile acids or contribute to metabolic acidosis. Taken with food, it is well tolerated. It is poorly absorbed and does not require functioning kidneys to be removed from the body. There is no evidence from current studies that it accumulates to biologically significant levels in tissues. Lanthanum carbonate has been shown in clinical studies of up to 6 years to be an effective, well-tolerated phosphate binder. Lanthanum carbonate controls hyperphosphataemia without increasing calcium intake above guideline targets and has the potential to reduce pill burden and increase patient compliance compared with other phosphate binders. Reported adverse effects are mainly gastrointestinal, and do not differ from those of calcium carbonate. The new phosphate binders, lanthanum carbonate and sevelamer, have increased the possibilities for serum phosphate control, at the expenses of significant increases in costs. The cost-effectiveness of lanthanum carbonate has been assessed by three different studies. A recent analysis, conducted on the perspective of the UK NHS, shows it is cost-effective to follow current treatment guidelines and treat all patients who are not adequately maintained on calcium carbonate (serum phosphorus above 5.6 mg/dl with second-line lanthanum carbonate. This is particularly the case for

  6. Spectroscopic properties of trivalent praseodymium in barium yttrium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Di Bartolo, B. E-mail: dibartob@bc.edurinodiba@attbi.com; Bowlby, B.E

    2003-05-01

    We have conducted a spectroscopic investigation of Pr{sup 3+} in barium yttrium fluoride (BaY{sub 2}O{sub 8}). Two doping concentrations were used: BaY{sub 2}F{sub 8}:Pr{sup 3+} (0.3%) and BaY{sub 2}F{sub 8}:Pr{sup 3+} (1%). The measurements included absorption, luminescence under continuous and pulsed excitations, and thermal effects on some sharp lines. The experimental results were used to characterize this system.

  7. A barium-rich binary central star in Abell 70

    CERN Document Server

    Boffin, Henri M J; Frew, D J; Acker, A; Köppen, J; Moffat, A F J; Parker, Q A

    2011-01-01

    We have found the central star of Abell 70 (PN G038.1-25.4, hereafter A 70) to be a binary consisting of a G8 IV-V secondary and a hot white dwarf. The secondary shows enhanced Ba II and Sr II features, firmly classifying it as a barium star. The nebula is found to have Type-I chemical abundances with helium and nitrogen enrichment, which combined with future abundance studies of the central star, will establish A 70 as a unique laboratory for studying s-process AGB nucleosynthesis.

  8. Thermochemical Modeling of the Uranium-Cerium-Oxygen System

    Energy Technology Data Exchange (ETDEWEB)

    Voit, Stewart L [ORNL; Besmann, Theodore M [ORNL

    2010-10-01

    with actinide materials, fundamental studies with uranium are performed using surrogate materials as stand-ins for transuranic elements. In most cases, cerium can be used as a suitable substitute for plutonium when performing O:M and sintering kinetics studies because of identical valence states. Differences exist between the magnitude of reported thermodynamic data of (U,Pu)O{sub x} and (U,Ce)O{sub x}, however the change in oxygen potential versus O:M follows the same trend for both systems. Cerium is also a major fission product element, and thus understanding its behavior in fuel is an important issue as well.

  9. Preparation of nanosized barium zirconate powder by thermal decomposition of urea in an aqueous solution containing barium and zirconium, and by calcination of the precipitate

    OpenAIRE

    Boschini, Frédéric; Robertz, B.; Rulmont, André; Cloots, Rudi

    2003-01-01

    The synthesis of barium zirconate was initiated by urea induced homogeneous precipitation followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that an amorphous zirconium hydrated oxide starts to precipitate followed by the precipitation of barium carbonate. A calcination at 1200 degreesC during 2 h gives rise to the for...

  10. Temperature dependence dielectric properties of modified barium titanate-PVB composites

    Science.gov (United States)

    Joshi, N. J.; Rakshit, P. B.; Grewal, G. S.; Shrinet, V.; Pratap, A.

    2013-06-01

    In this work, attempts are made to prepare ceramic polymer-composite followed by characterization of dielectric properties. The Barium Titanate ceramic powders are synthesized using the hydrothermal process. Silane treatment is carried out on Barium Titanate powder to increase its compatibility with polymer, followed with preparation of ceramic-polymer composite. Polyvinyl Butyral (PVB) is used as matrix for preparation of the composites and the concentration of Barium Titanate is increased from 60 to 90 wt%. Dielectric properties such as volume resistivity, dielectric constant, dissipation factor are evaluated. Results indicate that the dielectric constant and dissipation factor vary between 52 to 120 and 0.01 to 0.07; respectively as the relative ratio of polymer and silane modified Barium Titanate is varied. Specifically, at 90 wt% of silane modified Barium Titanate, the highest dielectric constant of 123 along with dissipation factor of 0.07 is obtained.

  11. Barium Tagging in Liquid Xenon for the nEXO Experiment

    Science.gov (United States)

    Kravitz, Scott; nEXO Collaboration

    2016-09-01

    nEXO is a next-generation experiment designed to search for neutrinoless double beta decay of xenon-136 in a liquid xenon time projection chamber. Positive observation of this decay would determine the neutrino to be a MAJORANA particle, as well as measure the absolute neutrino mass scale. In order to greatly reduce background contributions to this search, the collaboration is developing several ``barium tagging'' techniques to recover and identify the decay daughter, barium-136. Barium tagging may be available for a second phase of nEXO operation, allowing for neutrino mass sensitivity beyond the inverted mass hierarchy. Tagging methods for this phase include barium-ion capture on a probe with identification by resonance ionization laser spectroscopy. Inclusion of an argon ion gun in this system allows for improved cleaning and preparation of the barium deposition substrate, with recent results reported in this presentation.

  12. 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.

  13. 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.

  14. 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.

  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. Application of cerium chloride to improve the acid resistance of dentine.

    Science.gov (United States)

    Wegehaupt, Florian J; Sener, Beatrice; Attin, Thomas; Schmidlin, Patrick R

    2010-06-01

    To investigate the effect of cerium chloride, cerium chloride/fluoride and fluoride application on calcium release during erosion of treated dentine. Forty dentine samples were prepared from human premolars and randomly assigned to four groups (1-4). Samples were treated twice a day for 5 days, 30s each, with the following solutions: group 1 placebo, group 2 fluoride (Elmex fluid), group 3 cerium chloride and group 4 combined fluoride and cerium chloride. For the determination of acid resistance, the samples were consecutively eroded six times for 5 min with lactic acid (pH 3.0) and the calcium release in the acid was determined. Furthermore, six additional samples per group were prepared and used for EDS analysis. SEM pictures of these samples of each group were also captured. Samples of group 1 presented the highest calcium release when compared with the samples of groups 2-4. The highest acid resistance was observed for group 2. Calcium release in group 3 was similar to that of group 4 for the first two erosive attacks, after which calcium release in group 4 was lower than that of group 3. Generally, the SEM pictures showed a surface coating for groups 2-4. No deposits were observed in group 1. Although fluoride showed the best protective effect, cerium chloride was also able to reduce the acid susceptibility of dentine significantly, which merits further investigation. Copyright 2010 Elsevier Ltd. All rights reserved.

  17. Anion and cation diffusion in barium titanate and strontium titanate; Anionen- und Kationendiffusion in Barium- und Strontiumtitanat

    Energy Technology Data Exchange (ETDEWEB)

    Kessel, Markus Franz

    2012-12-19

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO{sub 3} single crystals has been studied by means of {sup 18}O{sub 2}/{sup 16}O{sub 2} isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial

  18. 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

  19. Tungsten and Barium Transport in the Internal Plasma of Hollow Cathodes

    Science.gov (United States)

    Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2008-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the flow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushedback to the emitter surface by the electric field and drag from the xenon ion flow. Thisbarium ion flux is sufficient to maintain a barium surface coverage at the downstream endgreater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length,so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollowcathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  20. 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?

  1. 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.

  2. 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.

  3. Antioxidant Cerium Oxide Nanoparticles in Biology and Medicine.

    Science.gov (United States)

    Nelson, Bryant C; Johnson, Monique E; Walker, Marlon L; Riley, Kathryn R; Sims, Christopher M

    2016-05-17

    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.

  4. 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.

  5. Thermal expansion behaviour of barium and strontium zirconium phosphates

    Indian Academy of Sciences (India)

    P Srikari Tantri; K Geetha; A M Umarji; Sheela K Ramasesha

    2000-12-01

    Ba1.5–SrZr4P5SiO24 compounds with = 0, 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5, belonging to the low thermal expansion NZP family were synthesized by the solid state reaction method. The XRD pattern could be completely indexed with respect to R$\\bar{3}$ space group indicating the ordering of vacancy at the divalent cation octahedral sites. The microstructure and bulk thermal expansion coefficient from room temperature to 800°C of the sintered samples have been studied. All the samples show very low coefficient of thermal expansion (CTE), with = 0 samples showing negative expansion. A small substitution of strontium in the pure barium compound changes the sign of CTE. Similarly, = 1.5 sample (pure strontium) shows a positive CTE and a small substitution of barium changes its sign. = 1.0 and 1.25 samples have almost constant CTE over the entire temperature range. The low thermal expansion of these samples can be attributed to the ordering of the ions in the crystal structure of these materials.

  6. Study of barium bismuth titanate prepared by mechanochemical synthesis

    Directory of Open Access Journals (Sweden)

    Lazarević Z.Ž.

    2009-01-01

    Full Text Available Barium-bismuth titanate, BaBi4Ti4O15 (BBT, a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure of BaBi4Ti4O15 ceramic forms at 1100 °C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size.

  7. Liquid-Phase Processing of Barium Titanate Thin Films

    Science.gov (United States)

    Harris, David Thomas

    Processing of thin films introduces strict limits on the thermal budget due to substrate stability and thermal expansion mismatch stresses. Barium titanate serves as a model system for the difficulty in producing high quality thin films because of sensitivity to stress, scale, and crystal quality. Thermal budget restriction leads to reduced crystal quality, density, and grain growth, depressing ferroelectric and nonlinear dielectric properties. Processing of barium titanate is typically performed at temperatures hundreds of degrees above compatibility with metalized substrates. In particular integration with silicon and other low thermal expansion substrates is desirable for reductions in costs and wider availability of technologies. In bulk metal and ceramic systems, sintering behavior has been encouraged by the addition of a liquid forming second phase, improving kinetics and promoting densification and grain growth at lower temperatures. This approach is also widespread in the multilayer ceramic capacitor industry. However only limited exploration of flux processing with refractory thin films has been performed despite offering improved dielectric properties for barium titanate films at lower temperatures. This dissertation explores physical vapor deposition of barium titanate thin films with addition of liquid forming fluxes. Flux systems studied include BaO-B2O3, Bi2O3-BaB2O 4, BaO-V2O5, CuO-BaO-B2O3, and BaO-B2O3 modified by Al, Si, V, and Li. Additions of BaO-B2O3 leads to densification and an increase in average grain size from 50 nm to over 300 nm after annealing at 900 °C. The ability to tune permittivity of the material improved from 20% to 70%. Development of high quality films enables engineering of ferroelectric phase stability using residual thermal expansion mismatch in polycrystalline films. The observed shifts to TC match thermodynamic calculations, expected strain from the thermal expansion coefficients, as well as x-ray diffract measurements

  8. A Nodular Foreign Body Reaction in a Dialysis Patient Receiving Long-term Treatment With Lanthanum Carbonate.

    Science.gov (United States)

    Valika, Aziz K; Jain, Dhanpat; Jaffe, Phillip E; Moeckel, Gilbert; Brewster, Ursula C

    2016-01-01

    A 63-year-old man with HIV (human immunodeficiency virus) infection and end-stage renal disease, treated with lanthanum carbonate phosphate binder for 4 years, presented with anemia and an upper gastrointestinal bleed. Upper endoscopy revealed a nodular hyperplastic epithelium, with an endoscopic ultrasound confirming hyperechoic material within the nodules. Light microscopy showed collections of histiocytes and multinucleated giant cells containing brown granular cytoplasmic material and extracellular crystalline material, a finding confirmed by electron microscopy. Similar pathologic findings associated with lanthanum exposure have been described recently. In our patient, lanthanum carbonate treatment was withdrawn and gastrointestinal bleeding has since ceased. The patient was exposed to a high amount of lanthanum over a long period, which may explain his adverse reaction. However, other contributing factors, such as competing medications or comorbid conditions, also may have increased his sensitivity to the drug.

  9. Lanthanum carbonate vs conventional phosphate binders for the treatment of hyperphosphatemia in maintenance hemodialysis patients: a meta-analysis

    Institute of Scientific and Technical Information of China (English)

    张晓娟

    2013-01-01

    Objective To assess the effect and safety of lanthanum carbonate vs conventional phosphate binders for hyperphosphatemia in patients undergoing maintenance hemodialysis.Methods According to the collaborative search strategy,MEDLINE (1996 to 2012.12) ,EBCO

  10. Solid state interaction studies on binary nitrate mixtures of uranyl nitrate hexahydrate and lanthanum nitrate hexahydrate at elevated temperatures

    Science.gov (United States)

    Kalekar, Bhupesh; Raje, Naina; Reddy, A. V. R.

    2017-02-01

    Interaction behavior of uranyl nitrate hexahydrate (UNH) and lanthanum nitrate hexahydrate (LaNH) have been investigated on the mixtures in different molar ratios of the two precursors and monitoring the reactions at elevated temperatures with thermoanalytical and X-ray diffraction measurement techniques. During the decomposition of equimolar mixture of LaNH and UNH, formation of lanthanum uranate (U0.5La0.5)O2, was seen by the temperature of 500 °C along with lanthanum oxide (La2O3) and uranium trioxide (UO3). By the temperature of 700 °C, the formation of uranium sesquioxide (U3O8) was observed along with (U0.5La0.5)O2 as end products in uranium rich mixtures. Lanthanum rich compositions decomposed by the temperature of 700 °C to give (U0.5La0.5)O2 and La2O3 as end products.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  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. KINETIC AND MECHANISTIC STUDY OF OXIDATION OF ATENOLOL BY CERIUM (IV IN SULPHURIC ACIDIC MEDIUM

    Directory of Open Access Journals (Sweden)

    Fadnis G Anand

    2012-03-01

    Full Text Available The kinetics of oxidation of antihypertensive drug, atenolol by cerium (IV in sulphuric acidic medium has been studied spectrophotometrically at 360 nm. The reaction between cerium (IV and atenolol in acidic medium has exhibited 2:1 stoichiometry. The order of the reaction with respect to atenolol has been found to be one. The observed pseudo first order rate constants kobs increased with sulphuric acid and hydrogen ion concentrations where as decreased bisulphate ion concentration indicating the formation bisulphato reactive species of cerium (IV in the present reaction. The thermodynamic parameters have been evaluated from the temperature variation kinetic data. A possible mechanism is proposed which has been validated by derived rate law. An attempt has been made to use rate data for kinetic estimation of atenolol.KEYWORDS:

  19. 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.

  20. Samarium Doped Cerium Oxide Clusters: a Study on the Modulation of Electronic Structure

    Science.gov (United States)

    Topolski, Josey E.; Kafader, Jared O.; Marrero-Colon, Vicmarie; Chick Jarrold, Caroline

    2017-06-01

    Cerium oxide is known for its use in solid oxide fuel cells due to its high ionic conductivity. The doping of trivalent samarium atoms into cerium oxide is known to enhance the ionic conductivity through the generation of additional oxygen vacancies. This study probes the electronic structure of Sm_{x}Ce_{y}O_{z} (x+y=3, z=2-4) anion and neutral clusters. Anion photoelectron spectra of these mixed metal clusters exhibit additional spectral features not present in the previously studied cerium oxide clusters. Density functional theory calculations have been used to aid interpretation of collected spectra. The results of this work can be used to inform the design of materials used for solid oxide fuel cells.