These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Magnetic properties of nano-clusters lanthanum chromite powders doped with samarium and strontium ions synthesized via a novel combustion method  

SciTech Connect

Graphical abstract: Nanocrystalline Sm{sup 3+} and Sr{sup 2+} doped LaCrO{sub 3} powders have been synthesized through a novel gel combustion synthesis using triethanol amine (TEA). The saturation magnetization of the LaCrO{sub 3} increased with an increase Sm{sup 3+} ion and it decreased with an increase in the Sr{sup 3+} ion to 0.3 at temperature 1000 {sup o}C for 2 h due to the formation of a monodispersed uniform octahedral structure as shown in the Fig. Research highlights: {yields} Single-phase orthorhombic lanthanum chromite LaCrO{sub 3} nanoclusters have been successfully synthesized through a novel gel combustion synthesis using triethanol amine (TEA). {yields} Sr{sup 2+} ions doped LaCrO{sub 3} increased the unit cell volume and the crystallite size whereas Sm{sup 3+} ions doped LaCrO{sub 3} decreased the unit cell volume and the crystallite size. {yields} The saturation magnetization of the LaCrO{sub 3} powders increased continuously with an increase in the Sm concentration and it decreased with an increase in the Sr ion up to 0.3 at annealing temperature of 1000 {sup o}C for 2 h. -- Abstract: A novel approach to synthesize a single-phase orthorhombic perovskite lanthanum chromite LaCrO{sub 3} clusters doped with Sm{sup 3+} and Sr{sup 2+} ions via gel combustion route was reported. The producing materials were synthesized using metal nitrates as oxidizers and triethanol amine (TEA), N-butyl amine (NBA) or ethylene diamine (EDA) as a fuel. The effect of the annealing temperature, type of organic fuel and the variation of the samarium and/or strontium substitution and its impact on crystal structure, crystallite size, microstructure and magnetic properties of the LaCrO{sub 3} powders formed was systematically studied. The results revealed that a well crystalline single phase of pure LaCrO{sub 3} can be achieved at annealing temperature from 800 to 1000 {sup o}C for 2 h. Moreover, each organic carrier materials exhibited a different degree of effectiveness in the synthesis of the mixed oxide powders. The crystal structure was influenced by doped Sm{sup 3+} and/or Sr{sup 2+} ions. The crystallite size of the produced powders was increased with the increase the annealing temperature, increasing the Sm{sup 3+} ion and the decrease of Sr{sup 2+} ion substitution. The microstructures of the produced powders were found to be nanoclusters octahedra-like shaped. The saturation magnetization of the LaCrO{sub 3} powders increased continuously with an increase in the Sm{sup 3+} ion concentration and it decreased with an increase in the Sr{sup 2+} ion up to 0.3 at annealing temperature of 1000 {sup o}C for 2 h. The maximum saturation magnetization (0.279 emu/g) was achieved at the Sm{sup 3+} ion molar ratio 0.3 and annealing temperature 1000 {sup o}C. Moreover, wide coercivities can be obtained at different synthesis conditions (49.25 to 522 Oe).

Rashad, M.M., E-mail: rashad133@yahoo.com [Advanced Materials Department, Central Metallurgical Research and Development Institute CMRDI, P.O. Box 87, Helwan 11421, Cairo (Egypt); El-Sheikh, S.M. [Advanced Materials Department, Central Metallurgical Research and Development Institute CMRDI, P.O. Box 87, Helwan 11421, Cairo (Egypt)] [Advanced Materials Department, Central Metallurgical Research and Development Institute CMRDI, P.O. Box 87, Helwan 11421, Cairo (Egypt)

2011-03-15

2

EXTENT OF PARTICULATE MARKER (SAMARIUM, LANTHANUM AND CERIUM) MOVEMENT FROM ONE DIGESTA PARTICLE TO ANOTHER 1'2  

Microsoft Academic Search

SUMMARY An in vitro and in vivo experiment was performed to determine the extent of move- ment of samarium (Sm), cerium (Ce), and lanthanum (La) from the original feedstuff upon which they were adsorbed to other feed particles. The rare-earth elements were demon- strated to be tenaciously bound to the parti- culate phase, with essentially none of the element occuring

Gary F. Hartnell; Larry D. Satter

3

FTIR and VSM properties of samarium-doped nickel ferrite  

NASA Astrophysics Data System (ADS)

Nickel Ferrite (NiFe2O4) doped with Samarium (Sm) (0.2, 0.3, 0.4, 0.5 mol.%) was prepared by the conventional solid-state reaction. The crystal structure, surface morphology, infrared spectrum of absorption, and magnetic properties of samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and vibrating sample magnetometer (VSM). XRD patterns were indexed with inverse spinel cubic phase with the space group of Fd-3m of nickel ferrite. The average grain size was about 5-10 ?m. FTIR spectral study on the NiFe2O4 ferrite phase was recorded between 350 cm-1 and 4000 cm-1. Two fundamental absorption bands of the ferrites were appeared at 450 cm-1 and 1000 cm-1 characteristic of metal vibrations. VSM measurements show that the NiFe2O4 doped with Sm 0.3% has the highest value of saturation magnetization. It is also easily demagnetized due to the low value of coercivity field it has. Both NiFe2O4 doped with Sm 0.2 mol.% and 0.4 mol.% materials have same values of coercivity field. However, NiFe2O4 doped with Sm 0.4 mol.% material has the comparatively high value of saturation magnetization than NiFe2O4 doped with Sm 0.2%, also this material was hardly demagnetized, and has highest coercivity field.

?abiko?lu, Israfil; Paral?, Levent

2014-05-01

4

Electrical properties of lanthanum doped barium titanate ceramics  

SciTech Connect

Pure and lanthanum doped barium titanate (BT) ceramics were prepared by sintering pellets at 1300 deg. C for 8 h, obtained from nanopowders synthesized by the polymeric precursor method. XRD results showed formation of a tetragonal structure. The presence of dopants changed the tetragonal structure to pseudo-cubic. The polygonal grain size was reduced up to 300 nm with addition of lanthanum as a donor dopant. Determined dielectric properties revealed that lanthanum modified BT ceramics possessed a diffused ferroelectric character in comparison with pure BT that is a classical ferroelectric material. In doped BT phase transition temperatures were shifted to lower temperatures and dielectric constant values were much higher than in pure BT. A modified Currie Weiss law was used to explore the connection between the doping level and degree of diffuseness of phase transitions. Impedance spectroscopy measurements were carried out at different temperatures in order to investigate electrical resistivity of materials and appearance of a PTCR effect. - Highlights: {yields} Pure and lanthanum doped BaTiO{sub 3} were prepared by polymeric precursors method. {yields} Change of structure from tetragonal to pseudo-cubic. {yields} Lanthanum as a donor dopant influenced on change of ferro-para phase transition. {yields} The diffuseness factor indicated the formation of diffuse ferroelectric material. {yields} Lanthanum affected on PTCR effect appearance in BT ceramics.

Vijatovic Petrovic, M.M., E-mail: miravijat@yahoo.com [Institute for Multidisciplinary Research, Belgrade University, Kneza Viseslava 1, Belgrade (Serbia); Bobic, J.D. [Institute for Multidisciplinary Research, Belgrade University, Kneza Viseslava 1, Belgrade (Serbia); Ramoska, T.; Banys, J. [Faculty of Physics, Vilnius University, Sauletekio al. 9, Vilnius (Lithuania); Stojanovic, B.D. [Institute for Multidisciplinary Research, Belgrade University, Kneza Viseslava 1, Belgrade (Serbia)

2011-10-15

5

Optical properties of samarium doped zinc phosphate glasses  

NASA Astrophysics Data System (ADS)

Samarium doped zinc phosphate glasses having composition Sm2O3 (x)ZnO(60-x) P2O5 (40) (where x=0.1 0.5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been calculated. The values of density range from 3.34 to 3.87 gm/cm3 and those of molar volume range from 27.62 to 31.80 cm-3. The optical absorbance studies were carried out on these glasses to measure their energy band gaps. The absorption spectra of these glasses were recorded in UV-visible region. No sharp edges were found in the optical spectra, which verifies the amorphous nature of these glasses. The optical band gap energies for these glasses were found to be in the range of 2.89 4.20 eV. The refractive index and polarizability of oxide ion have been calculated by using Lorentz Lorentz relations. The values of refractive index range from 2.13 to 2.42 and those of polarizability of oxide ion range from 6.51×10-24 to 7.80×10-24 cm3.

Eraiah, B.; Bhat, Sudha G.

2007-04-01

6

Pure and doped lanthanum manganites obtained by combustion method  

Microsoft Academic Search

Pure and strontium-doped lanthanum manganite nanopowders were obtained by solution combustion method using metal nitrates as oxidants and different organic compounds as fuel (?-alanine, glycine, urea and semioxamazide). Different molar ratios, fuel\\/oxidant, were chosen to study the effect of the fuel content on the phase formation and powder properties. The complex precursors isolated before ignition of the system, were characterized

D. Berger; C. Matei; F. Papa; D. Macovei; V. Fruth; J. P. Deloume

2007-01-01

7

Diode pumped white light emission from dysprosium and samarium doped glasses  

NASA Astrophysics Data System (ADS)

Glasses embedded with Dysprosium and Samarium were made by the melt quenching technique. Dy3+ -doped glasses exhibited bright white luminescence under 10 mW of 405 nm diode laser excitation. Color rending index of the glass was improved by adding Sm3+ as a co-dopant to the glass. Spectroscopic results of the glasses are discussed.

Reddy, B. Rami; Edwards, Vernessa M.; Surabhi, Raja

2014-03-01

8

Chemical Preparation of Pure and Strontium-and/or Magnesium-Doped Lanthanum Gallate Powders  

E-print Network

emission spectroscopy, and carbon and nitrogen anal- yses. I. Introduction LANTHANUM GALLATE (LaGaO3Chemical Preparation of Pure and Strontium- and/or Magnesium-Doped Lanthanum Gallate Powders A. Cu mixture of the acetates of lanthanum, strontium, and magnesium, as well as that of gallium nitrate, also

Tas, A. Cuneyt

9

Effect of samarium doping on the dielectric behavior of barium zircomium titanate ceramic  

NASA Astrophysics Data System (ADS)

Samarium doped Barium Zirconium Titanate ceramic with general formula Ba1-xSm2x/3Zr0.05Ti0.95O3 [x=0.0,0.01,0.02,0.03,0.04] has been prepared by high energy ball milling. The X-ray diffraction (XRD) patterns confirmed that these ceramics have a single phase with perovskite-type upto x?0.03 and a small secondary phase exist at x=0.04. The temperature dependent dielectric study shows a ferroelectric phase transition and transition temperature decreases with an increase in the Samarium content.

Badapanda, T.; Sarangi, S.; Behera, B.; Anwar, S.; Sinha, T. P.

2014-04-01

10

Thermal conductivity analysis of lanthanum doped manganites  

NASA Astrophysics Data System (ADS)

The temperature-dependent thermal conductivity of the doped manganites La0.7Ca0.3MnO3 is theoretically analyzed within the framework of Kubo formulae. The Hamiltonian consists of phonon, electron and magnon thermal conductivity contribution term. In this process we took defects, carrier, grain boundary, scattering process term and then calculate phonon, electron and magnon thermal conductivity.

Mansuri, Irfan; Shaikh, M. W.; Khan, E.; Varshney, Dinesh

2014-04-01

11

Cathodoluminescence microanalysis of irradiated microcrystalline and nanocrystalline samarium doped BaFCl.  

PubMed

BaFCl:Sm3+ is an efficient photoluminescent storage phosphor for ionizing radiation. Cathodoluminescence (CL) microanalysis enables the Sm2+ and Sm3+ oxidation states of samarium doped BaFCl to be easily identified, provides information about electron-beam and X-ray induced modification of BaFCl:Sm, and enables the synthesis dependent spatial distribution of samarium dopants of <100 ppm concentration to be determined with sub-100 nm resolution at 295 K. CL spectroscopy of BaFCl:Sm particles reveals broad CL emissions at ? 360 and ?500 nm associated with V k (Cl-) and oxygen-vacancy defects in the BaFCl host lattice and fine structure CL emissions associated with major 4GJ ? 6HJ (Sm3+) and 5DJ ? 7FJ (Sm2+) transitions. CL microanalysis shows samarium dopants are uniformly distributed in conventional sintered microcrystalline BaFCl:Sm. In contrast, CL investigations reveal that for BaFCl:Sm nanoparticles, which have been prepared using a co-precipitation method, with greatly improved Sm3+ ? Sm2+ conversion efficiency, the samarium dopants are concentrated near the particle surface resulting in a BaFCl:Sm3+ shell surrounding the BaFCl core, which is stable to energetic irradiation. PMID:23164246

Stevens-Kalceff, Marion A; Liu, Zhiqiang; Riesen, Hans

2012-12-01

12

Lanthanum  

MedlinePLUS

... and the laboratory. Your doctor will order certain lab tests to check your body's response to lanthanum.Before having any x-rays of your abdominal area, tell your doctor and the x-ray technicians that you are taking lanthanum.Do not let ...

13

Altering the equilibrium condition in Sr-doped lanthanum manganite.  

SciTech Connect

The material of choice for a solid oxide fuel cell cathode based on a yttria-stabilized zirconia (YSZ) electrolyte is doped lanthanum manganite, (La, Sr)MnO{sub 3}. It excels at many of the attributes necessary for a system to work at the required operating temperature and is flexible enough to allow for materials optimization. Although strontium-doping increases the electronic conductivity of the material, the ionic conductivity of the material remains negligible under operating conditions. Studies have shown that the internal equilibrium of the material heavily favors oxidation of the manganese and rather than the loss of lattice oxygen as a charge compensation mechanism. This lack of oxygen vacancies in the structure retards the ability of the material to conduct oxygen ions; thus the optimized system requires a large number of engineered triple point boundary locations to work efficiently. We have successfully doped the host LSM lattice to alter the interred equilibrium of the material to increase its ionic conductivity and thus lower the cathodic overpotential of the system. Our presentation will discuss these new materials, the results of cell tests, and a number of characterization experiments performed.

Carter, J. D.; Krumpelt, M.; Vaughey, J.; Wang, X.

1999-05-28

14

Photoluminescence of samarium-doped TiO{sub 2} nanotubes  

SciTech Connect

Samarium (Sm)-modified TiO{sub 2} nanotubes (TNTs) were synthesized by low-temperature soft chemical processing. X-ray powder diffraction analyses of the synthesized Sm-doped and non-doped TNTs show a broad peak near 2{theta}=10{sup o}, which is typical of TNTs. The binding energy of Sm {sup 3}d{sub 5/2} for 10 mol% Sm-doped TNT (1088.3 eV) was chemically shifted from that of Sm{sub 2}O{sub 3} (1087.5 eV), showing that Sm existed in the TiO{sub 2} lattice. Sm-doped TNTs clearly exhibited red fluorescence, corresponding to the doped Sm{sup 3+} ion in the TNT lattice. The Sm-doped TNT excitation spectrum exhibited a broad curve, which was similar to the UV-vis optical absorption spectrum. Thus, it was considered that the photoluminescence emission of Sm{sup 3+}-doped TNT with UV-light irradiation was caused by the energy transfer from the TNT matrix via the band-to-band excitation of TiO{sub 2} to the Sm{sup 3+} ion. - Graphical Abstract: Samarium-doped TiO{sub 2} nanotubes (TNTs) having a nanotubular structure were synthesized by soft chemical route. It was revealed that the energy associated by the band-to-band excitation of TNT matrix transferred to the doped Sm{sup 3+} ions in the lattice, resulting in emission of strong and visible red fluorescence. Highlights: > Sm-doped TiO{sub 2} nanotubes synthesized by low-temperature soft chemical processing. > Sm{sup 3+} substitutes Ti{sup 4+} ions in the nanotube lattice. > Clear fluorescent emission due to the f-f transition at the Sm{sup 3+} in a crystal field environment. > Band-to-band excitation of TiO{sub 2} and followed energy transfer to Sm{sup 3+} causes the luminescence.

Park, Dong Jin [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Sekino, Tohru, E-mail: sekino@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Tsukuda, Satoshi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Hayashi, Asuka [Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kusunose, Takafumi [Faculty of Engineering, Kagawa University, Hayashi 2217-20, Takamatsu, Kagawa 761-0396 (Japan); Tanaka, Shun-Ichiro [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan)

2011-10-15

15

The evolution mechanism of the dislocation loops in irradiated lanthanum doped cerium oxide  

NASA Astrophysics Data System (ADS)

Cerium dioxide, a non-radioactive surrogate of uranium dioxide, is useful for simulating the radiation responses of uranium dioxide and mixed oxide fuel (MOX). Controlled additions of lanthanum can also be used to form various levels of lattice oxide or anion vacancies. In previous transmission electron microscopy (TEM) experimental studies, the growth rate of dislocation loops in irradiated lanthanum doped ceria was reported to vary with lanthanum concentration. This work reports findings of the evolution mechanisms of the dislocation loops in cerium oxide with and without lanthanum dopants based on a combination of molecular statics and molecular dynamics simulations. These dislocation loops are found to be b=1/3<111> interstitial type Frank loops. Calculations of the defect energy profiles of the dislocation loops with different structural configurations and radii reveal the basis for preference of nucleation as well as the driving force of growth. Frenkel pair evolution simulations and displacement cascade overlaps simulations were conducted for a variety of lanthanum doping conditions. The nucleation and growth processes of the Frank loop were found to be controlled by the mobility of cation interstitials, which is significantly influenced by the lanthanum doping concentration. Competition mechanisms coupled with the mobility of cation point defects were discovered, and can be used to explain the lanthanum effects observed in experiments.

Miao, Yinbin; Aidhy, Dilpuneet; Chen, Wei-Ying; Mo, Kun; Oaks, Aaron; Wolf, Dieter; Stubbins, James F.

2014-02-01

16

Crystal structure of Eu-doped magnetoplumbite-type lanthanum aluminum oxynitride with emission site splitting  

Microsoft Academic Search

Eu-doped lanthanum aluminum oxynitride (LaAl12(O,N)19) with magnetoplumbite structure was prepared by nitridation of the oxide precursor obtained from aluminum glycine gel and subsequent post-annealing. Eu-doped lanthanum aluminum oxynitride exhibited blue light emission at 440nm with a shoulder at 464nm under excitation at 254nm. Isostructural Eu-doped calcium aluminum oxide (CaAl12O19) exhibited a single emission peak at 415nm. Structural refinement using neutron

Yuji Masubuchi; Tomoyuki Hata; Teruki Motohashi; Shinichi Kikkawa

2011-01-01

17

Improved chemical stability and conductivity of barium cerate nanopowders by Lanthanum doping.  

PubMed

Despite of the highest proton conductivity, barium cerate electrolytes are well known for the deficiency of chemical stability at elevated temperature under CO2 atmosphere. This work is focused on improving chemical stability of lanthanum doped barium cerate (BCL) powder for electrolyte. Although lanthanum doping causes distortion of perovskite structure lattice, immoderate doping could stabilize structure due to increasing symmetry of structure lattices. The thermogravimetric analysis and AC impedance measurements revealed that the lanthanum doping suppresses the reaction between barium and carbonate and this effect results in sufficient improvement in ionic conductivity in operating temperatures range. It was confirmed that BaCe0.7La0.3O3-delta (BCL30) was the most stable composition and the conductivity of BCL30 is high as 3.8 S x cm(-1) x K at 700 degrees C. PMID:24205607

Lee, Hunhyeong; Park, Inyu; Shin, Dongwook

2013-09-01

18

Single-Longitudinal-Mode Lanthanum-Codoped Bismuth-Based Erbium Doped Fiber Ring Laser  

E-print Network

wave plates. La-codoped bismuth oxide glass is much more soluble to Er 3+ ions than silicate glass and thus high concentration of Er 3+ ions up to 13000 ppm can be doped in bismuth-based glass withoutSingle-Longitudinal-Mode Lanthanum-Codoped Bismuth-Based Erbium Doped Fiber Ring Laser K. K

Wai, Ping-kong Alexander

19

Crystal structure of Eu-doped magnetoplumbite-type lanthanum aluminum oxynitride with emission site splitting  

SciTech Connect

Eu-doped lanthanum aluminum oxynitride (LaAl{sub 12}(O,N){sub 19}) with magnetoplumbite structure was prepared by nitridation of the oxide precursor obtained from aluminum glycine gel and subsequent post-annealing. Eu-doped lanthanum aluminum oxynitride exhibited blue light emission at 440 nm with a shoulder at 464 nm under excitation at 254 nm. Isostructural Eu-doped calcium aluminum oxide (CaAl{sub 12}O{sub 19}) exhibited a single emission peak at 415 nm. Structural refinement using neutron powder diffraction indicated that the lanthanum site occupied partially by Eu{sup 2+} splits into 2d and 6h sites in the aluminum oxynitride. The longer emission and the shoulder peak in the former aluminum oxynitride were observed in relation to the increasing covalency as well as crystal field splitting around doped Eu{sup 2+} induced by site splitting involved with the two kinds of anions. - Graphical Abstract: Magnetoplumbite type Eu-doped lanthanum aluminum oxynitride has lanthanum site splitting induced by two kinds of anions, causing two emission peaks. Highlights: > Magnetoplumbite type LaAl{sub 12}(O,N){sub 19} doped with Eu shows emission peak splitting. > ND analysis is performed on La{sub 0.97}Eu{sub 0.03}Al{sub 12}(O,N){sub 19} and Ca{sub 0.97}Eu{sub 0.03}Al{sub 12}O{sub 19}. > La{sub 0.97}Eu{sub 0.03}Al{sub 12}(O,N){sub 19} has lanthanum site splitting. > The lanthanum site splitting is induced by coexisting of two kinds of anions.

Masubuchi, Yuji, E-mail: yuji-mas@eng.hokudai.ac.jp [Faculty of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo 060-8628 (Japan); Hata, Tomoyuki; Motohashi, Teruki; Kikkawa, Shinichi [Faculty of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo 060-8628 (Japan)

2011-09-15

20

Enhancement of ferromagnetic and dielectric properties of lanthanum doped bismuth ferrite nanostructures  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Rod shaped lanthanum doped bismuth ferrite was obtained. Black-Right-Pointing-Pointer The diameter of the particles were found to be decreasing on doping with lanthanum. Black-Right-Pointing-Pointer Both ferromagnetic and dielectric properties enhanced. Black-Right-Pointing-Pointer A transition due to spin canting is observed near 550 Degree-Sign C. Black-Right-Pointing-Pointer Electron spin resonance study shows the breakage of spin cycloid due to doping. -- Abstract: Cylindrical-shaped multiferroic Bi{sub 1-x}La{sub x}FeO{sub 3} (x = 0.0, 0.05, 0.1 and 0.15) were synthesized successfully by hydrothermal method. All samples were found to be rhombohedrally distorted perovskite structure. Diameter of the cylindrical particles reduces from {approx}450 nm for x = 0.0 to {approx}100 nm for x = 0.1 prepared under the same conditions. The Neel temperature as well as the dielectric constant was also found to increase with the increase in lanthanum content. Lanthanum doping also enhanced the magnetic properties. Magnetization measurements above room temperature show a significant increase in magnetization at around 400 Degree-Sign C. Enhanced magnetic properties due to lanthanum doping are caused by the breakage of spin cycloid as observed by electron spin resonance study.

Chaudhuri, A., E-mail: arka@bose.res.in [Magnetism Laboratory, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Mandal, K. [Magnetism Laboratory, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India)] [Magnetism Laboratory, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India)

2012-04-15

21

Thermal-expansion behaviors and mechanisms for Ca or Sr-doped lanthanum manganite perovskites under oxidizing atmospheres  

Microsoft Academic Search

The thermal expansion behavior and mechanism of A-site-deficient lanthanum manganite perovskites, La{sub 1-x}MnOâ (0 < x ⤠0.1), and alkaline earth metal (AE)-doped lanthanum manganite perovskites, La{sub 1-x}AEâMnOâ (AE = Ca and Sr, 0 ⤠x ⤠0.4), under oxidizing atmospheres have been investigated. The average linear thermal expansion coefficients of the AE-doped lanthanum manganites decreased with increasing Ca content

Masashi Mori; Yoshiko Hiei; Nigel M. Sammes; Geoff A. Tompsett

2000-01-01

22

Structural and optical study of samarium doped lead zinc phosphate glasses  

NASA Astrophysics Data System (ADS)

Samarium doped lead-zinc-phosphate glasses with composition (60-x)P2O5-20PbO-20ZnO-xSm2O3 (x=0, 0.5, 1.0, 3.0 mol%) were prepared by melt quenching technique. Density, refractive index and polaron radius of Sm3+ ions were calculated. The IR spectra reveal significant structural changes only for high concentration of samarium ions. Differential thermal analysis confirms the large structural changes in the glass due to the decrease of thermal stablility in presence of 3 mol% Sm3+ ions. UV-vis-NIR absorption spectroscopy was carried out and Judd-Ofelt analysis was performed. Radiative rates, branching ratio and lifetime of 4G5/2 were calculated by taking into account both electric and magnetic dipole contributions. Absorption spectra consist of seven absorption peaks corresponding to the transitions from the 6H5/2 ground state to various excited energy levels. Photoluminescence spectra show four prominent emission bands centered at 560, 597, 642 and 700 nm corresponding to the 4G5/2-6HJ (J=5/2, 7/2, 9/2, and 11/2) transitions respectively and the intensities of all bands are enhanced by Sm3+ ions content. The calculated values are compared to other reports, available in literature.

Dousti, M. Reza; Ghoshal, S. K.; Amjad, Raja J.; Sahar, M. R.; Nawaz, Fakhra; Arifin, R.

2013-07-01

23

Luminescence of trivalent samarium ions in silver and tin co-doped aluminophosphate glass  

NASA Astrophysics Data System (ADS)

This work presents the spectroscopic properties of trivalent samarium ions in a melt-quenched aluminophosphate glass containing silver and tin. Addition of 4 mol% of each Ag 2O and SnO into the glass system with 2 mol% Sm 2O 3 results in Sm 3+ ions luminescence under non-resonant UV excitation owing to energy transfer from single silver ions and/or twofold-coordinated Sn centers. Assessment of luminescence spectra and decay dynamics suggest the energy transfer mechanism to be essentially of the resonant radiative type. Moreover, a connection between the luminescent and structural properties of the rare-earth doped glass system was demonstrated. Raman spectroscopy characterization revealed that no significant variation in the glass matrix is induced by Sm 3+ doping at the concentration employed. A comparison was made with a structural study performed on the Eu 3+ doped system (containing 2 mol% Eu 2O 3 along with 4 mol% of each Ag 2O and SnO) where the radiative energy transfer mechanism was previously established. The data appears consistent regarding the lack of variation in glass structure upon the Eu 3+ and Sm 3+ doping in connection with the dominance of the radiative transfer in the matrix. Thermal treatment of the material leads to precipitation of Ag nanoparticles of a broad size range inside the dielectric as observed by transmission electron microspcopy. Assessment of 4G 5/2 excited state decay in Sm 3+ ions shows no influence from the silver particles.

Jiménez, José A.; Lysenko, Sergiy; Liu, Huimin; Sendova, Mariana

2011-06-01

24

Structural and Conductivity Studies on Lanthanum Doped LiNiPO4 Prepared by Polyol Method  

NASA Astrophysics Data System (ADS)

Pure and Lanthanum doped LiNiPO4 (with different Molar concentrations) have been prepared by polyol method using 1,2 propanediol as a polyol medium. XRD analysis reveal that sample calcined at 650°C for 6 hrs shows good crystalline nature with orthorhombic structure and this result is consistent with TG/DTA result. It is found that the conductivity enhances upon doping of Lanthanum while backhoprate decreases compared with pure LiNiPO4. Dielectric studies have also been discussed.

Karthickprabhu, S.; Hirankumar, G.; Maheswaran, A.; Bella, R. S. Daries; Sanjeeviraja, C.

2013-07-01

25

Samarium doped calcium fluoride: A red scintillator and X-ray phosphor  

NASA Astrophysics Data System (ADS)

We report the photoluminescence, X-ray luminescence and scintillation properties of CaF2:Sm2+. Large single crystals of CaF2:Sm2+ were grown by simply slow cooling of the calcium fluorite melt doped with samarium metal. The photoluminescence at room temperature shows a broad red 5d?4f emission band peaked at 725 nm which is well matched to the response of silicon photodetectors, and only a very weak Sm3+ emission is observed. On cooling, the zero phonon lines of the Sm2+ emission can be observed. The lifetime of the broad emission is short at room temperature (46 ns), but temperature dependent, and slows on cooling, reaching a constant value of 1.25 ?s below 180 K. The X-ray luminescence comprises both red Sm2+ and Sm3+ emissions and a blue self-trapped exciton band for low Sm concentrations, but just the broad red emission Sm2+ for highly doped (~1%) samples. The scintillation decay at room temperature shows two components, of 58 ns and 870 ns, in an integrated intensity ratio of 0.7:1 for a 0.1% Sm sample. The light output is around 15,000 photons/MeV when cooled by dry ice, with a scintillation decay time of 1.4 ?s at that temperature. The performance of the material as an X-ray phosphor and scintillator is discussed.

Dixie, Laura Catherine; Edgar, Andrew; Bartle, Colin Murray

2014-07-01

26

Samarium and manganese-doped lead titanate ceramic fiber\\/epoxy 1-3 composite for high-frequency transducer application  

Microsoft Academic Search

Samarium- (Sm) and manganese- (Mn) doped lead titanate ceramic fibers with a diameter of 35 ?m were prepared using a sol-gel method. The X-ray diffraction pattern shows that the fibers have a pure perovskite structure. The 1-3 composite disks with a thickness of 31-41 ?m and with ceramic volume fraction of ?0.68 have been prepared using the samarium and manganese

Kun Li; Helen L. W. Chan; Chung L. Choy

2003-01-01

27

Indexing the structural parameters and investigating the magnetic properties of lanthanum doped strontium hexaferrites  

NASA Astrophysics Data System (ADS)

Sr1-xLaxFe12O19 (x= 0, 0.1, 0.15, 0.2) nano-crystallites were synthesized using a sol-gel based combustion technique. Sintering of the samples at 800 °C helped to develop the stable hexagonal phase. Data received from the X-ray diffraction was used to confirm and determine the crystal structure of the samples by manipulating the lattice parameters, volume of the unit cell, crystallite size, X-ray density and porosity of the samples. Room temperature magnetic measurements were performed using a vibrating sample magnetometer with an applied field of ±10 kOe. The magnetic hysteresis loops reveal that lanthanum doping at Sr-sites has enhanced the coercivity of the samples in the series with some compromise on magnetization while remanence remains almost constant, enabling the lanthanum doped samples appropriate for hard magnetic applications.

Azim, M.; Atiq, S.; Riaz, S.; Naseem, S.

2014-06-01

28

Mechanisms of enhanced sulfur tolerance on samarium (Sm)-doped cerium oxide (CeO2) from first principles.  

PubMed

The role of samarium (Sm) 4f states and Sm-perturbed O 2p states in determining the sulfur tolerance of Sm-doped CeO2 was elucidated by using the density functional theory (DFT) + U calculation. We find that the sulfur tolerance of Sm-doped CeO2 is closely related to the modification of O 2p states by the strong interaction between Sm 4f and O 2p states. In particular, the availability of unoccupied O 2p states near the Fermi level is responsible for enhancing the sulfur tolerance of Sm-doped CeO2 compared to the pure CeO2 by increasing the activity of the surface lattice oxygen toward sulfur adsorption, by weakening the interaction between Sm-O, and by increasing the migration tendency of the subsurface oxygen ion toward the surface. PMID:24756238

Lim, Dong-Hee; Kim, Hee Su; Yoon, Sung Pil; Han, Jonghee; Yoon, Chang Won; Choi, Sun Hee; Nam, Suk Woo; Ham, Hyung Chul

2014-06-14

29

Effect of a-site cation deficiency and YSZ additions on sintering and properties of doped lanthanum manganite  

SciTech Connect

The sintering behavior of Ca- and Sr-doped lanthanum manganite (the preferred SOFC cathode material) is highly dependent on the relative proportion of A and B site cations in the material. In general, A-site cation deficiency increases sintered density. The effect of additions of YSZ to lanthanum manganite (to expand the reactive region at the cathode/electrolyte interface and improve thermal expansion and sintering shrinkage matches) on sintering and other properties will also be reported.

Stevenson, J.W.; Armstrong, T.R.; Weber, W.J.

1995-06-01

30

Characterisation of samarium and nitrogen co-doped TiO2 films prepared by chemical spray pyrolysis  

NASA Astrophysics Data System (ADS)

The sol-gel chemical spray pyrolysis method was used to deposit samarium and nitrogen co-doped TiO2 films onto a quartz substrate at a growth temperature of 450 °C using pulsed spray solution feed, followed by annealing at 500 °C for 2 h in air. The obtained films exhibited anatase structure independent of the doping level. According to XRD analysis, the mean crystallite size of the undoped TiO2, TiO2:N(25) and TiO2:N(5):Sm(5) films was 32, 38 and 20 nm, respectively. According to AFM, the undoped TiO2 film consisted of agglomerates with a size of 30-200 nm. N-doping (25 at%) transformed the agglomerates into individually distinctive grains with a size of ca. 30 nm, while Sm doping (5 at%) caused a significant decrease in the average diameter of the agglomerates to ca. 100 nm. The RMS roughness of the undoped TiO2 film was 1.7 nm; doping resulted in the formation of smoother films with RMS roughness of 0.9-1.4 nm. XPS data indicated that the Sm and N dopants were incorporated into the TiO2 crystal lattice and/or adsorbed on the surface of the film. An increasing nitrogen concentration in the spray solution correlates to a systematic suppressing of the photoluminescence intensity of Sm3+.

Oja Acik, I.; Kiisk, V.; Krunks, M.; Sildos, I.; Junolainen, A.; Danilson, M.; Mere, A.; Mikli, V.

2012-11-01

31

Superstructure ordering in lanthanum-doped lead magnesium niobate  

SciTech Connect

Superstructure reflections of lead magnesium niobate (PMN), Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}, were measured with synchrotron radiation x-ray diffraction. Our data conclusively demonstrate that the (h+(1/2),k+(1/2),l+(1/2))-type reflections are the result of chemical ordering between the Mg and Nb ions in domains of 50 Aa. Structure factor analysis of these peaks reveals an oxygen displacement within the ordered regions of 0.044(3) Aa along a <100> direction towards the Nb ion. Single crystals of La-doped PMN (La-PMN) exhibit much larger chemically ordered regions (up to 900 Aa for 10% La-PMN). Structural analysis of the La-PMN suggests that as the ordered region increases in size, the ordering changes from complete Nb:Mg ordering and approaches Nb:(Mg{sub 2/3}Nb{sub 1/3}) ordering. Although anticipated from electrostatic energy arguments, our conclusions are based on a clear trend in the bond length of the mixed site as a function of La doping. (c) 2000 American Institute of Physics.

Fanning, D. M. [Department of Physics, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States)] [Department of Physics, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States); Robinson, I. K. [Department of Physics, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States)] [Department of Physics, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States); Jung, S. T. [Department of Materials Science and Engineering, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States)] [Department of Materials Science and Engineering, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States); Colla, E. V. [Department of Materials Science and Engineering, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States)] [Department of Materials Science and Engineering, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States); Viehland, D. D. [Department of Materials Science and Engineering, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States)] [Department of Materials Science and Engineering, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States); Payne, D. A. [Department of Materials Science and Engineering, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States)] [Department of Materials Science and Engineering, University of Illinois at Champaign-Urbana, Urbana, Illinois 61801-3080 (United States)

2000-01-15

32

Thermopower studies of rare earth doped lanthanum barium manganites  

NASA Astrophysics Data System (ADS)

Influence of rare earth doping on electrical, magnetic and thermopower studies of La0.34Re0.33Ba0.33MnO3 compound was investigated. Ferro to paramagnetic transition and metal to insulator transition temperatures decrease with decreasing ionic radius of the dopant ion. Electrical resistivity in the entire temperature range is explained by phase separation model. The magnitude of Seebeck coefficient increases with increasing dopant ionic radius. A cross over from negative to positive sign has also been observed in thermopower data with decreasing A site ionic radius (). The low temperature thermopower data has been explained using a qualitative model containing diffusion; magnon drag and phonon drag effects while the paramagnetic insulating part has been analyzed using small polaron hopping mechanism.

Reddy, G. Lalitha; Lakshmi, Y. Kalyana; kumar, N. Pavan; Rao, S. Manjunath; Reddy, P. Venugopal

2014-08-01

33

Optical amplification in Nd3+ doped electro-optic lanthanum lead zirconate titanate ceramics  

NASA Astrophysics Data System (ADS)

As high as 13.0dB single-pass gain was obtained at 1064.4nm in a thin electro-optic ceramic plate of neodymium doped lanthanum-modified lead zirconate titanate (Nd:PLZT). Pumping with a diode laser, gains were achieved in 1.0 and 0.5mol% Nd ion doped samples over a broad seed laser power ranging from tens of nanowatts to tens of milliwatts at room temperature. The broad absorption spectra of Nd:PLZT made it insensitive to the pump wavelength. The Nd:PLZT had a total scattering loss coefficient of less than 0.06cm-1 and exhibited a considerable quadratic electro-optic coefficient greater than 0.30×10-16m2/V2.

Zhang, Jingwen W.; Zou, Yingyin K.; Chen, Qiushui; Zhang, Run; Li, Kewen K.; Jiang, Hua; Huang, Pi-Ling; Chen, Xuesheng

2006-08-01

34

Intrinsic inhomogeneities of low-doped lanthanum manganites in the paramagnetic temperature range  

NASA Astrophysics Data System (ADS)

The nature of the electrical resistivity for low-doped lanthanum manganites is elucidated. The electrical resistivity is described by the Efros-Shklovskii law (ln? ? ( T 0/ T)-1/2, where T 0 ? 1/ R ls) in the temperature range from T* ? 300 K ? T C ( T C is the Curie temperature for conducting manganites) to their T C and is explained by the tunneling of carriers between localized states. The magnetoresistance is explained by a change in the size of localized states R ls in a magnetic field. The patterns of change in R ls with temperature and magnetic field strength determined from magnetotransport properties are satisfactorily described in the model of phase separation into small-radius metallic droplets in a paramagnetic matrix. The sizes R ls and their temperature dependence have been estimated through magnetic measurements. The results confirm the existence of a Griffith phase. The intrinsic inhomogeneities produced by thermodynamic phase separation determine the electrical resistivity and magnetoresistance of lanthanum manganites.

Solin, N. I.

2012-01-01

35

Sintering and thermal expansion characterization of Al-doped and Co-doped lanthanum strontium chromites synthesized by the Pechini method  

Microsoft Academic Search

The air-sintering and thermal expansion characteristics of Al-doped and Co-doped lanthanum strontium chromites synthesized by the Pechini method have been discussed as interconnect materials in high-temperature solid oxide fuel cells (SOFC). Fine perovskite powders with an average particle size of 0.24 ?m, and with a surface area of 3.5 m2\\/g, calcined at 800 °C for 1 h, were obtained. After

Masashi Mori; Nigel M Sammes

2002-01-01

36

Bismuth doped lanthanum ferrite perovskites as novel cathodes for intermediate-temperature solid oxide fuel cells.  

PubMed

Bismuth is doped to lanthanum strontium ferrite to produce ferrite-based perovskites with a composition of La(0.8-x)Bi(x)Sr0.2FeO(3-?) (0 ? x ? 0.8) as novel cathode material for intermediate-temperature solid oxide fuel cells. The perovskite properties including oxygen nonstoichiometry coefficient (?), average valence of Fe, sinterability, thermal expansion coefficient, electrical conductivity (?), oxygen chemical surface exchange coefficient (K(chem)), and chemical diffusion coefficient (D(chem)) are explored as a function of bismuth content. While ? decreases with x due to the reduced Fe(4+) content, D(chem) and K(chem) increase since the oxygen vacancy concentration is increased by Bi doping. Consequently, the electrochemical performance is substantially improved and the interfacial polarization resistance is reduced from 1.0 to 0.10 ? cm(2) at 700 °C with Bi doping. The perovskite with x = 0.4 is suggested as the most promising composition as solid oxide fuel cell cathode material since it has demonstrated high electrical conductivity and low interfacial polarization resistance. PMID:24971668

Li, Mei; Wang, Yao; Wang, Yunlong; Chen, Fanglin; Xia, Changrong

2014-07-23

37

Magnetic phase transition of nanocrystalline Fe-doped samarium oxide (Sm1.90Fe0.10O3)  

NASA Astrophysics Data System (ADS)

Nanocrystalline Fe3+ doped samarium oxide (Sm1.90Fe0.10O3) has been prepared by the co-precipitation method. The as prepared sample has been annealed at 700 °C for 6 h in an argon atmosphere. The pure crystallographic phase as well as the substitution of Fe3+ ions in the lattice of Sm2O3 is confirmed by Rietveld analysis of the X-ray diffraction patterns. The variation of magnetic susceptibility (?) with temperature (T) is recorded by a Faraday Magnetometer in the temperature range of 300-14 K. The variation of ? vs. T down to ~50 K was successfully fitted by the Curie-Weiss law and below this temperature, susceptibility increases very rapidly, which suggests the presence of ordering at low temperature. To explore this, magnetic measurements are also carried out at different temperatures down to 2 K by using a SQUID Magnetometer. No hysteretic behavior is observed down to 50 K, but a feeble ferromagnetic behavior is observed in the magnetization vs. field curve recorded at ~30 K. A clear hysteresis loop is observed at 2 K with a comparatively high value of maximum magnetization (~3.32 emu/gm). The observed magnetic phase transition is analyzed by using the dipole-dipole interaction among the magnetic nanoparticles at low temperature.

Mandal, J.; Sarkar, B. J.; Deb, A. K.; Chakrabarti, P. K.

2014-12-01

38

Crystal structures and magnetic properties of strontium and copper doped lanthanum ferrites  

SciTech Connect

The crystal and magnetic structures of La{sub 0.8}Sr{sub 0.2}Fe{sub 1-x}Cu{sub x}O{sub 3-w} compounds, which exhibit coercive fields larger than any others reported for iron-based perovskites, have been analyzed at room temperature with the neutron powder diffraction technique and the Rietveld method of profile fitting. For x in the range 0.05-0.10 the material is monophasic with orthorhombic symmetry (space group Pnma), and crystallizes in the perovskite-like cell of LaFeO{sub 3}, Fe/Cu cations occupy octahedral sites, La/Sr cations are twelve-fold coordinated. For x=0.20 the material is biphasic, with a main orthorhombic phase (space group Pnma) and a secondary rhombohedral phase with space group R-3c (hexagonal setting). The structural transition from the orthorhombic to the rhombohedral phase reduces the structural distortion of the (Fe/Cu)O{sub 6} octahedron. The average bond distance (Fe/Cu)-O and the pseudo-cubic unit cell volume decrease with increasing Cu content in accordance with the presence of higher valence states of the transition metals. The magnetic structure was modeled for the monophasic samples (x=0.05 and 0.10) assuming an antiferromagnetic interaction between Fe/Cu neighboring cations (G-type): the magnetic moments order antiferromagnetically along the b-axis, with the spin direction along a-axis. The magnetic moments of the Fe/Cu atoms are {mu}{sub x}=2.66(3){mu}{sub B} and 2.43(3){mu}{sub B} for the compositions x=0.05 and 0.10, respectively. By measuring the first magnetization curve and the hysteresis loops, coexisting antiferromagnetic and weak ferromagnetic interactions were observed for all samples. - Graphical abstract: Hysteresis loops measured at room temperature of the sample with x=0.05. Highlights: Black-Right-Pointing-Pointer Iron based perovskites with the largest coercive fields. Black-Right-Pointing-Pointer Sr and Cu lanthanum ferrites as magnetic materials. Black-Right-Pointing-Pointer Doped lanthanum ferrites show antiferromagnetic and weak ferromagnetic interactions. Black-Right-Pointing-Pointer Sr and Cu lanthanum ferrites show distorted perovkite structure.

Sora, Isabella Natali, E-mail: isabella.natali-sora@unibg.it [INSTM R.U. and Department of Industrial Engineering, University of Bergamo, Dalmine, BG, I-24044 (Italy); Caronna, Tullio; Fontana, Francesca [INSTM R.U. and Department of Industrial Engineering, University of Bergamo, Dalmine, BG, I-24044 (Italy); Julian Fernandez, Cesar de [INSTM R.U. Firenze and Department of Chemistry, University of Florence, I-50019 Sesto Fiorentino (Italy); CNR-Istituto di Scienze e Tecnologie Molecolari (ISTM), 20133 Milano (Italy); Caneschi, Andrea [INSTM R.U. Firenze and Department of Chemistry, University of Florence, I-50019 Sesto Fiorentino (Italy); Green, Mark [Center for Neutron Research, NIST, Gaithersburg, MD (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States)

2012-07-15

39

Stability of strontium-doped lanthanum manganite cathode in humidified air  

NASA Astrophysics Data System (ADS)

The stability of strontium-doped lanthanum manganite (LSM) cathode has been studied using symmetric cells (humidified air, LSM/yttria-stabilized zirconia (YSZ)/LSM, humidified air) under a range of humidification levels (0-50%), temperatures (750-850 °C), and cathodic biases (0-0.5 V). Electrochemical impedance spectroscopy revealed an increase in non-ohmic resistance with increasing H2O/O2 ratio, temperature, and cathodic bias. Post-test surface and interface studies showed the segregation of SrO particles on the LSM surface and formation of Mn2O3 and La2Zr2O7 compounds at the cathodic LSM/YSZ interface. The increase in non-ohmic resistance is attributed to surface segregation of SrO and interfacial compound formation, whereas formation and growth of SrO at the LSM surface is attributed to water adsorption. La2Zr2O7 formation is attributed to interfacial reactions.

Hu, Boxun; Keane, Michael; Mahapatra, Manoj K.; Singh, Prabhakar

2014-02-01

40

Exchange bias and its tuning in magnetic compensated Nd doped ferromagnetic samarium metal  

NASA Astrophysics Data System (ADS)

Sm metal is a ferromagnet with a very small net magnetization as it comprises nearly compensated local moment (4f-orbital moment slightly greater than the 4f-spin moment) which is coupled to conduction electrons via RKKY exchange mechanism and results in antiferromagnetically coupled alignment between total local moment and the contribution from conduction electron polarization. Ferromagnetic Sm metal is considered to be in spin surplus state, as it yields magnetic compensation on doping with RE-ions (e.g., Nd) belonging to the first half of 4f-series. The results pertaining to identification and tuning of the exchange bias (EB) field in Nd doped Sm metal are presented.

Pandya, Swati; Ramakrishnan, S.; Grover, A. K.

2013-02-01

41

Solid oxide fuel cells with doped lanthanum gallate electrolyte and LaSrCoOâ cathode, and Ni-samaria-doped ceria cermet anode  

Microsoft Academic Search

The electrode performance of a single solid-oxide fuel cell (SOFC) was evaluated using a 500 μm thick La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}O{sub 0.3} (LSGM) as the electrolyte membrane. A doped lanthanum cobaltite, La{sub 0.6}Sr{sub 0.4}CoO{sub 3-δ} was selected as the cathode material, and a samaria-doped ceria-NiO composite powder was used as the anode material. The spray-pyrolysis method was applied for synthesis

Radenka Maric; Satoshi Ohara; Takehisa Fukui; Hiroyuki Yoshida; Masayoshi Nishimura; Toru Inagaki; Kazuhiro Miura

1999-01-01

42

Spatially resolved measurement of high doses in microbeam radiation therapy using samarium doped fluorophosphate glasses  

SciTech Connect

The measurement of spatially resolved high doses in microbeam radiation therapy has always been a challenging task, where a combination of high dose response and high spatial resolution (microns) is required for synchrotron radiation peaked around 50 keV. The x-ray induced Sm{sup 3+}{yields} Sm{sup 2+} valence conversion in Sm{sup 3+} doped fluorophosphates glasses has been tested for use in x-ray dosimetry for microbeam radiation therapy. The conversion efficiency depends almost linearly on the dose of irradiation up to {approx}5 Gy and saturates at doses exceeding {approx}80 Gy. The conversion shows strong correlation with x-ray induced absorbance of the glass which is related to the formation of phosphorus-oxygen hole centers. When irradiated through a microslit collimator, a good spatial resolution and high ''peak-to-valley'' contrast have been observed by means of confocal photoluminescence microscopy.

Okada, Go; Morrell, Brian; Koughia, Cyril; Kasap, Safa [Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9 (Canada); Edgar, Andy; Varoy, Chris [School of Chemical and Physical Sciences and MacDiarmid Institute, Victoria University of Wellington, Kelburn Parade (New Zealand); Belev, George; Wysokinski, Tomasz [Canadian Light Source Inc., University of Saskatchewan, Saskatoon, SK S7N 0X4 (Canada); Chapman, Dean [Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK S7N 5E5 (Canada)

2011-09-19

43

Optical Characteristic Improvement of Neodymium-Doped Lanthanum Fluoride Thin Films Grown by Pulsed Laser Deposition for Vacuum Ultraviolet Application  

NASA Astrophysics Data System (ADS)

Neodymium-doped lanthanum fluoride (Nd3+:LaF3) thin films were successfully grown on MgF2(001) substrates by pulsed laser deposition. Photoluminescence spectra revealed a dominant peak at 173 nm with a decay time of 7.8 ns, which is similar to the results obtained from a bulk Nd3+:LaF3 crystal. Improvements in crystalline quality and vacuum ultraviolet (VUV) luminescence quantum efficiency were achieved by substrate heating, with optimum results being obtained at 400 °C. These results would open up possibilities in the development of a light-emitting device operating in the VUV region.

Ieda, Mirai; Ishimaru, Tatsuya; Ono, Shingo; Yamanoi, Kohei; Cadatal-Raduban, Marilou; Shimizu, Toshihiko; Sarukura, Nobuhiko; Fukuda, Kentaro; Suyama, Toshihisa; Yokota, Yuui; Yanagida, Takayuki; Yoshikawa, Akira

2012-02-01

44

Doped lanthanum nickelates with a layered perovskite structure as bifunctional cathode catalysts for rechargeable metal-air batteries.  

PubMed

Rechargeable metal-air batteries have attracted a great interest in recent years because of their high energy density. The critical challenges facing these technologies include the sluggish kinetics of the oxygen reduction-evolution reactions on a cathode (air electrode). Here, we report doped lanthanum nickelates (La2NiO4) with a layered perovskite structure that serve as efficient bifunctional electrocatalysts for oxygen reduction and evolution in an aqueous alkaline electrolyte. Rechargeable lithium-air and zinc-air batteries assembled with these catalysts exhibit remarkably reduced discharge-charge voltage gaps (improved round-trip efficiency) as well as high stability during cycling. PMID:24053465

Jung, Kyu-Nam; Jung, Jong-Hyuk; Im, Won Bin; Yoon, Sukeun; Shin, Kyung-Hee; Lee, Jong-Won

2013-10-23

45

[Study on preparation of lanthanum-doped TiO2 nanometer thin film materials and its photocatalytic activity].  

PubMed

In this paper, lanthanum-doped TiO2 nanometer film materials coated on glass were prepared in Ti(OBu)4 precursor solutions by sol-gel processing. Transmittance and photocatalytic activity were respectively investigated and tested for these nanometer thin films prepared with different amount of lanthanum (La), different amount of polyethylene glycol (PEG), and different coating layer times. Some reactive mechanisms were also discussed. For one layer La-addition had little effect on the film transmissivity; but the photocatalytic activity was significantly improved due to La-addition. With increasing PEG, the transmittance of the film decreased for one layer film; but its photocatalytic activity did not rise. Increasing layer number did not affect the transmissivity of multilayer film. After coating two times, increasing layer number did not significantly improve the photocatalytic activity. The highest photocatalytic activity and best transmissivity were obtained for two layer TiO2 film when the dosage of lanthanum was 0.5 g and the dosage of polyethylene was 0.2 g in the precursor solutions. These materials will probably be used in the protection of environment, waste water treatment, and air purification. PMID:12961861

Zheng, Huai-li; Tang, Ming-fang; Gong, Ying-kun; Deng, Xiao-jun; Wu, Bang-hua

2003-04-01

46

Persistent spectral hole burning in europium- and europium, samarium-doped calcium sulphide  

NASA Astrophysics Data System (ADS)

The presented work contains an account of photon-gated spectral hole burning and systematic spectroscopic study of the Eu, and Eu, Sm doped CaS powders. The dependence of the hole burning process and hole parameters on temperature, gating, laser power, exposure time, spectral position, etc. were studied and comprehensive spectroscopic investigation of the samples was accomplished. The high temperature (up to 25 K) and high speed (10 ns, similar to MgS:Eu) hole burning was demonstrated. The readout erasure was shown to be negligible for the powers below 4 ?W, and tuning the burning beam into the vibronic band was shown to efficiently erase holes. The spectral dependence of the erasure for CaS:Eu and CaS:Eu,Sm was shown to follow the absorption profile of the samples. The holes were shown to survive thermal cycling to 230 K. The temperature dependence of the hole width and depth were used to identify thermally induced localized oscillations and ion diffusion as likely mechanisms of the temperature-related hole broadening and erasure. Energies of Eu-localized oscillation modes of CaS:Eu in the temperature range of 3 to 250 K were established to be 2.7, 43, 91 and 153 cm-1. The experimentally determined Debye temperature of CaS:Eu (455 K) was shown to be in a good agreement with theoretical estimates. The dependence of hole burning in CaS:Eu on the Eu2+ concentration was studied and the best concentration of Eu in CaS for the hole burning purposes was found to be 0.01 mol %. The PMMA embedding of CaS:Eu was shown to increase the width of inhomogeneously broadened ZPL four times and to increase the width of a hole 30%. At the same time, PMMA embedding was shown to decrease the maximum thermal cycling temperature of a hole from 230 K to 180 K. Chlorination of CaS:Eu at the sample preparation stage was shown to change the ratio Eu2+/Eu3+ in the sample according to the redox process. The depth of the spectral holes in our samples was shown not to be limited by the concentration of Eu 3+.

Solonenko, Mikhail (Michael)

1999-10-01

47

Dielectric properties and substitution mechanism of samarium-doped Ba{sub 0.68}Sr{sub 0.32}TiO{sub 3} ceramics  

SciTech Connect

Ba{sub 0.68}Sr{sub 0.32}TiO{sub 3} ceramics of perovskite structure are prepared by solid state reaction method with addition of x mol% Sm{sub 2}O{sub 3}, and their dielectric properties are investigated. It is found that, integrating with the lattice parameters and tolerance factor t, there is an alternation of substitution preference of Sm{sup 3+} for the host cations in perovskite lattice. Owing to the replacement of Sm{sup 3+} ions for Ba{sup 2+} ions in the A site, T{sub c} rises with the increase of Sm{sub 2}O{sub 3} doping when the doping content is below 0.1 mol%; meanwhile, when the content is more than 0.1 mol%, Sm{sup 3+} ions tend to occupy the B-site, causing a drop of T{sub c}. Owing to the modifications of Sm{sup 3+} doping, dielectric constant, dissipation factor and temperature stability of dissipation factor are influenced remarkably, making it a superior candidate for environment-friendly applications. Moreover, the creation of oxygen vacancies controls the dielectric constant when the addition is above 0.1 mol%, so the dielectric constant decreases with increasing of samarium.

Li Yuanliang [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)], E-mail: lylll2007@yahoo.cn; Qu Yuanfang [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)

2009-01-08

48

Doped lanthanum ferrite cathode development for use in single-step co-fired solid oxide fuel cells  

NASA Astrophysics Data System (ADS)

A major obstacle to the commercialization of solid oxide fuel cells (SOFCs) is the high operating temperature range (800 to 1000°C). Lowering the operating temperature to approximately 600°C allows for cost reduction through the use of inexpensive stack housing and sealing materials, but conventional SOFC cathode materials have high charge transfer resistance at those temperatures which results in poor performance. This research focused on developing an SOFC cathode material with low charge transfer resistance at low operating temperatures and a porous microstructure that would not impede mass transfer when synthesized using the single-step co-firing process. Towards this goal, mixed ionic and electronic conducting lanthanum ferrite perovskite cathode materials were synthesized using calcium and cerium as dopants. A specific stoichiometry of calcium doped lanthanum ferrite, La0.78Ca0.16FeO3+/-delta (LCF), proved to be a superior cathode compared to state-of-the-art conventional cathode materials across a range of measures. In order to understand the LCF cathode performance, the defect model structure was determined using thermogravimetric (TGA) measurements, oxygen-ion permeability and four-probe conductivity measurements as a function of temperature and oxygen partial pressure (pO2). The results were analyzed to determine defect concentrations and mobility. The electrochemical performance of LCF was characterized using electrochemical impedance spectroscopy measurements on symmetrical cells which compared favorably to conventional lanthanum manganite cathode materials. Reactivity of LCF with yttria-stabilized zirconia (YSZ) electrolyte was confirmed and prevented using a gadolinium doped ceria (GDC) barrier layer. Microstructural analysis showed evidence of a small amount (2--5 wt%) of secondary phase that precipitated from LCF as a liquid during sintering at approximately 1220°C. The secondary phase was a poor n-type oxide (Ca-Fe-O), present within both the LCF cathode and GDC barrier layer microstructures. In spite of the presence of the liquid phase, LCF symmetrical cells yielded adequate microstructures and satisfactory electrochemical performance. To understand the reasons for the superior electrochemical performance of LCF, the chemical oxygen ion diffusivity and surface exchange coefficient were determined using conductivity relaxation measurements. Both of these parameters in LCF were found to be an order of magnitude greater than conventional cathode materials.

Zink, Peter Andrew

49

Photocatalytic performance of novel samarium-doped spherical-like ZnO hierarchical nanostructures under visible light irradiation for 2,4-dichlorophenol degradation.  

PubMed

A novel samarium-doped spherical-like ZnO hierarchical nanostructure (Sm/ZnO) was synthesized via a facile and surfactant-free chemical solution route. The as-synthesized products were characterized by X-ray diffraction, Brunauer-Emmett-Teller surface area analysis, field emission scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy, UV-visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The results revealed that Sm ion was successfully doped into ZnO. It was also observed that the Sm doping increased the visible light absorption ability of Sm/ZnO and a red shift for Sm/ZnO appeared when compared to pure ZnO. The photocatalytic studies revealed that the Sm/ZnO exhibited excellent photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP) compared with the pure ZnO and commercial TiO2 under visible light irradiation. The photocatalytic enhancement of Sm/ZnO products was attributed to their high charge separation efficiency and ·OH generation ability as evidenced by the photoluminescence spectra. The photocatalytic investigation also showed that various parameters exerted their individual influence on the degradation rate of 2,4-DCP. By using a certain of radical scavengers, ·OH was determined to play a pivotal role for the 2,4-DCP degradation. Moreover, the Sm/ZnO could be easily separated and reused, indicating great potential for practical applications in environmental cleanup. PMID:23618322

Sin, Jin-Chung; Lam, Sze-Mun; Lee, Keat-Teong; Mohamed, Abdul Rahman

2013-07-01

50

Preparation and photocatalytic activity of magnetic samarium-doped mesoporous titanium dioxide at the decomposition of methylene blue under visible light  

NASA Astrophysics Data System (ADS)

Preparation of samarium-doped mesoporous titanium dioxide (Sm/MTiO2) coated magnetite (Fe3O4) photocatalysts (Sm/MTiO2/Fe3O4) and their activities under visible light were reported. The catalysts with Sm/MTiO2 shell and a Fe3O4 core were prepared by coating photoactive Sm/MTiO2 onto a magnetic Fe3O4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu)4, TBT) with precursors of Sm(NO3)3 and TBT in the presence of Fe3O4 nanoparticles. The morphological, structural and optical properties of the prepared samples were characterized by BET surface area, transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of Sm ion content on the photocatalytic activity was studied. The photocatalytic activities of obtained photocatalysts under visible light were estimated by measuring the decomposition rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Sm/MTiO2 was tightly bound to Fe3O4 and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.

Shi, Zhongliang; Lai, Hong; Yao, Shuhua

2012-08-01

51

Effects of magnetization on hole localization and MnO{sub 6} octahedra disorder in hole-doped lanthanum manganese perovskites  

SciTech Connect

The authors review the distortions of the MnO{sub 6} octahedra reduced by magnetization in hole-doped lanthanum manganese perovskites. The systems they consider include the colossal magnetoresistance (CMR) samples La{sub 1{minus}x}Ca{sub x}MnO{sub 3} (x = 0.21, 0.25, 0.30), La{sub 0.76}Ba{sub 0.33}MnO{sub 3}, and a poorer quality La{sub 0.76}Pb{sub 0.33}MnO{sub 3} sample. They also report preliminary work on three samples of oxygen-doped LaMnO{sub 3+{delta}} and a lanthanum-deficient La{sub 0.9}MnO{sub 3} sample. They find the same exponential relationship between the removal of the distortion and the sample magnetization in the Ba- and Pb-doped CMR samples as was found previously for the Ca doped samples. The MnO{sub 6} distortion in the oxygen-doped materials is found to slightly reduce below the magnetic transition, although much less so than in the CMR samples. Above T{sub C}, the antiferromagnetic LaMnO{sub 3.006} sample shows a softer temperature dependence of the Mn-O bond length distribution broadening. Surprisingly, even this sample shows deviations from thermal (Debye) behavior near T{sub N}, possibly due to FM coupling within MnO planes.

Booth, C.H.; Brosha, E.L.; Kwei, G.H. [Los Alamos National Lab., NM (United States); Bridges, F. [Univ. of California, Santa Cruz, CA (United States). Physics Dept.; Neumeier, J.J. [Florida Atlanta Univ., Boca Raton, FL (United States). Physics Dept.

1998-12-31

52

Electrical properties and thermal expansion of cobalt doped apatite-type lanthanum silicates based electrolytes for IT-SOFC  

SciTech Connect

Graphical abstract: The figure shows the dependence of conductivity on the Co content. It can be seen that La{sub 10}Si{sub 5.2}Co{sub 0.8}O{sub 26.6} exhibits the highest ionic conductivity of 3.33 Multiplication-Sign 10{sup -2} S/cm at 800 Degree-Sign C. When x {<=} 0.8, as doping Co weakens the binding energy and aids the migration of the interstitial oxide ions, the ionic conductivity improves. On the other hand, excess dopant of Co (0.8 < x {<=} 1.5) can decrease the number of interstitial oxide ions and reduce the ionic conductivity. Highlights: Black-Right-Pointing-Pointer The unit volumes of La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} increase with increasing cobalt content. Black-Right-Pointing-Pointer Doping Co can increase the thermal expansion because of the larger radius of Co{sup 3+} ion. Black-Right-Pointing-Pointer Conductivities of La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} first increase and then decrease with cobalt content. Black-Right-Pointing-Pointer Above 550 Degree-Sign C, La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} shows low activation energies of around 0.7 eV. -- Abstract: The thermal expansion and conductivities have been investigated for Co{sup 3+} doped lanthanum silicates. The apatite-type lanthanum silicates with formula La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} (x = 0.2, 0.4, 0.6, 0.8, 1.0, 1.5) were synthesized by sol-gel process. The thermal expansion coefficient (TEC) of La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} was improved with increasing cobalt content because of the lower valence and larger radius of Co{sup 3+} ion compared to Si{sup 4+}. Analysis of AC impedance spectroscopy showed that conductivity increased first and then decreased with increasing cobalt content. There is an optimum doping amount of cobalt and La{sub 10}Si{sub 5.2}Co{sub 0.8}O{sub 26.6} exhibits the highest conductivity of 3.33 Multiplication-Sign 10{sup -2} S/cm at 800 Degree-Sign C. When x {<=} 0.8, the local distortion caused by doping with Co{sup 3+} can significantly affect the oxygen channels and assist the migration of the interstitial oxide ions, resulting in the improvement of ionic conductivity. However, excess Co{sup 3+} dopant (0.8 < x {<=} 1.5) reduced the number of interstitial oxide ions and decreased the conductivity.

Shi, Qingle; Lu, Lihua; Jin, Hongjian [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China)] [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China); Zhang, Hua, E-mail: huazhang@njut.edu.cn [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China)] [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China); Zeng, Yanwei [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China)] [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China)

2012-03-15

53

Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer  

DOEpatents

A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO{sub 3} particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO{sub 3} particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr{sub 2}O{sub 3} on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO{sub 3} layer coated with CaO and Cr{sub 2}O{sub 3} surface deposit at from about 1,000 C to 1,200 C to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO{sub 3} layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power. 5 figs.

Singh, P.; Ruka, R.J.

1995-02-14

54

Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer  

DOEpatents

A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO.sub.3 particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr.sub.2 O.sub.3 on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO.sub.3 layer coated with CaO and Cr.sub.2 O.sub.3 surface deposit at from about 1000.degree. C. to 1200.degree. C. to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO.sub.3 layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power.

Singh, Prabhakar (Export, PA); Ruka, Roswell J. (Pittsburgh, PA)

1995-01-01

55

Influence of small DC bias field on the electrical behaviour of Sr- and Mg-doped lanthanum gallate  

NASA Astrophysics Data System (ADS)

One of the promising electrolyte materials for solid oxide fuel cells application, Sr- and Mg-doped lanthanum gallate La0.9Sr0.1Ga0.8Mg0.2O3-? (LSGM), is synthesized by conventional solid state ceramic route. X-ray Rietveld analysis confirms the formation of main orthorhombic phase at room temperature along with a few minor secondary phases. SEM micrograph reveals the grain and grainboundary morphology of the system. Electrical conductivity of the LSGM sample is measured in the temperature range 573-873 K and in the frequency range 20 Hz-1 MHz at a few small DC bias fields (at 0.0, 0.5, 1.0, 1.5 and 2.0 V). The conductivity spectra show power-law behaviour. Electrical conductivity of the sample is found to be weakly dependent on DC bias field. This is attributed to field-dependent bulk and grainboundary conduction processes. In the present system, under investigated bias field range, the possibility of formation of Schottky barrier is ruled out. The concept of grainboundary channel (pathway) modulation on the application of bias field is proposed.

Raghvendra; Singh, Rajesh Kumar; Singh, Prabhakar

2014-09-01

56

Characterisation of doped-lanthanum gallates by X-ray diffraction and Raman spectroscopy  

Microsoft Academic Search

La1?xSrxGaO3?z (x=0–0.2) and LaGa1?yMyO3?z (y=0–0.2, M=Cr, Mg) were synthesised using the standard solid state technique. The structural changes, with increase in dopant concentration, were investigated using powder X-ray diffraction and Raman spectroscopy. The X-ray diffraction of Sr-doped LaGaO3 shows a shift in the orthorhombic pattern with increase in dopant concentration. At 20 mol% Sr doped on the A-site of LaGaO3

N. M. Sammes; G. A. Tompsett; R. J. Phillips; A. M. Cartner

1998-01-01

57

Dielectric relaxation and alternating current conductivity of polyvinylidene fluoride doped with lanthanum chloride  

NASA Astrophysics Data System (ADS)

X-ray diffraction (XRD), dielectric constant (?'), dielectric loss factor (??), and ac conductivity (?ac) of pure and LaCl3-doped polyvinylidene fluoride (PVDF) have been carried out. The dielectric properties have been studied in the temperature and frequency ranges; 140-450 K and 0.1-1000 kHz, respectively. XRD results reveal that pure and LaCl3-PVDF samples are in the ?-phase. The incorporation of La3+ ions within the PVDF polymer matrix forms complexes which reduce the order structure of PVDF. Three relaxation processes, namely; ?, ?a, and ?c were observed for pure PVDF. The first relaxation can be explained based on space charge formation or Maxwell-Wagner polarization. The second one occurs around the glass transition temperature, Tg, and is related to the micro-Brownian motion of the main polymer chain. It becomes broad and shifted to higher temperatures with the doping of LaCl3. The third process appears below the melting temperature of PVDF and can be attributed to molecular motions of the main polymer chain. The behavior of the ac conductivity shows that the conduction mechanism of pure, 5 wt. % and 10 wt. % of LaCl3-doped PVDF samples is follows the correlated barrier hopping (CBH) model, while 3 wt. % of LaCl3-doped PVDF exhibits a small polaron tunneling (SPT) conduction.

Hassen, A.; Hanafy, T.; El-Sayed, S.; Himanshu, A.

2011-12-01

58

Electronic structure of doped lanthanum cuprates studied with resonant inelastic x-ray scattering  

NASA Astrophysics Data System (ADS)

We report a comprehensive Cu K-edge resonant inelastic x-ray scattering (RIXS) investigation of La2-xSrxCuO4 (LSCO) for 0?x?0.35, stripe-ordered La1.875Ba0.125CuO4 (LBCO), and La2Cu0.96Ni0.04O4 (LCNO) crystals. The RIXS spectra measured at three high-symmetry momentum-transfer (q) positions are compared as a function of doping and for the different dopants. The spectra in the energy range 1-6 eV can be described with three broad peaks, which evolve systematically with increased doping. The most systematic trend was observed for q=(?,0) corresponding to the zone boundary. As hole doping increased, the spectral weight transfer from high energies to low energies is nearly linear with x at this q. We interpret the peaks as interband transitions in the context of existing band models for this system, assigning them to Zhang-Rice band?upper Hubbard band, lower-lying band?upper Hubbard band, and lower-lying band?Zhang-Rice band transitions. The spectrum of stripe-ordered LBCO was also measured, and found to be identical to the correspondingly doped LSCO, except for a relative enhancement of the near-infrared peak intensity at ~1.5-1.7 eV. The temperature dependence of this near-infrared peak in LBCO was more pronounced than for other parts of the spectrum, continuously decreasing in intensity as the temperature was raised from 25 to 300 K. Finally, we find that 4% Ni substitution in the Cu site has a similar effect on the spectra as does Sr substitution in the La site.

Ellis, D. S.; Kim, Jungho; Zhang, Harry; Hill, J. P.; Gu, Genda; Komiya, Seiki; Ando, Yoichi; Casa, D.; Gog, T.; Kim, Young-June

2011-02-01

59

Electronic Structure of Doped Lanthanum Cuprates Studied with Resonant Inelastic X-Ray Scattering  

SciTech Connect

We report a comprehensive Cu K-edge resonant inelastic x-ray scattering (RIXS) investigation of La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO) for 0 {le} x {le} 0.35, stripe-ordered La{sub 1.875}Ba{sub 0.125}CuO{sub 4} (LBCO), and La{sub 2}Cu{sub 0.96}Ni{sub 0.04}O{sub 4} (LCNO) crystals. The RIXS spectra measured at three high-symmetry momentum-transfer (q) positions are compared as a function of doping and for the different dopants. The spectra in the energy range 1-6 eV can be described with three broad peaks, which evolve systematically with increased doping. The most systematic trend was observed for q = ({pi},0) corresponding to the zone boundary. As hole doping increased, the spectral weight transfer from high energies to low energies is nearly linear with x at this q. We interpret the peaks as interband transitions in the context of existing band models for this system, assigning them to Zhang-Rice band {yields} upper Hubbard band, lower-lying band {yields} upper Hubbard band, and lower-lying band {yields} Zhang-Rice band transitions. The spectrum of stripe-ordered LBCO was also measured, and found to be identical to the correspondingly doped LSCO, except for a relative enhancement of the near-infrared peak intensity at {approx}1.5-1.7 eV. The temperature dependence of this near-infrared peak in LBCO was more pronounced than for other parts of the spectrum, continuously decreasing in intensity as the temperature was raised from 25 to 300 K. Finally, we find that 4% Ni substitution in the Cu site has a similar effect on the spectra as does Sr substitution in the La site.

Hill, J.P.; Ellis, D.S.; Kim, J.; Zhang, H.; Gu, G.; Komiya, S.; Ando, Y.; Casa, D.; Gog, T.; Kim, Y.-J.

2011-02-24

60

Competition between fcc and icosahedral short-range orders in pure and samarium-doped liquid aluminum from first principles  

NASA Astrophysics Data System (ADS)

Development of structural order in liquid aluminum upon rapid cooling is studied by ab initio molecular-dynamics simulations and the recently developed atomistic cluster alignment method. We show that there is a strong competition between icosahedral and fcc short-range orders (SROs) in the system. Although the liquid eventually crystallizes into fcc structure when T ? 800 K, the icosahedral short-range order (ISRO) is found to be much stronger than the fcc SRO in the liquid. Doping of Sm in Al liquid can hinder the fcc crystallization and enhance the ISRO.

Fang, X. W.; Wang, C. Z.; Yao, Y. X.; Ding, Z. J.; Ho, K. M.

2011-06-01

61

Pulsed laser deposition of rare-earth-doped gallium lanthanum sulphide chalcogenide glass thin films  

NASA Astrophysics Data System (ADS)

Amorphous chalcogenide thin films are of high current interest for technological applications as optical storage media or waveguides for photonic integrated circuits. As part of a larger project including fs, ps and ns pulsed laser deposition regimes, Er- and Pr-doped GLS thin films were deposited by ns PLD, and their structural, chemical and optical properties were analyzed by optical and electronic microscopy, stylus profilometry, X-ray diffraction, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), energy-dispersive X-ray spectroscopy, variable-angle spectroscopic ellipsometry and optical transmission. Films deposited at moderate fluence (~4 J/cm2) in UV (266 nm) presented a good surface quality, while exhibiting acceptable composition uniformity and deviations from stoichiometry in line with the literature. Composition and optical properties dependences on the deposition conditions were investigated and discussed with respect to previous studies on similar systems.

Pompilian, O. G.; Dascalu, G.; Mihaila, I.; Gurlui, S.; Olivier, M.; Nemec, P.; Nazabal, V.; Cimpoesu, N.; Focsa, C.

2014-10-01

62

Influence of the lanthanum deficit on electrical resistivity and heat capacity of silver-doped lanthanum manganites La{sub 1-x}Ag{sub y}MnO{sub 3}  

SciTech Connect

The electrical resistivity and heat capacity of the silver-doped lanthanum manganites La{sub 0.80}Ag{sub 0.15}MnO{sub 3} and La{sub 0.85}Ag{sub 0.15}MnO{sub 3} have been investigated. Despite the nonstoichiometry of the composition, the La{sub 0.80}Ag{sub 0.15}MnO{sub 3} manganite exhibits a bulk homogeneity and better physical properties from the applied point of view as compared to the La{sub 0.85}Ag{sub 0.15}MnO{sub 3} manganite, viz., the former compound has a higher spontaneous magnetoresistance and a larger jump of the heat capacity with a small width of the phase transition, and the anomalies of the heat capacity and electrical resistivity in the vicinity of the Curie point of this compound agree with the fluctuation nature of the second-order phase transition. The behavior of the properties of lanthanum-deficient manganites under investigation in the region of the phase transition is consistent with the classical theory of indirect exchange interaction. The behavior of the temperature dependence of the electrical resistivity has been analyzed in terms of two models. One of these models is based on the tunneling of charge carriers between ferrons or polarons, and the other model is based on the polaron hopping conduction. Both approaches lead to consistent results, and their combination has made it possible to estimate the tunneling distance of charge carriers. The origin of the influence of technological parameters characterizing the synthesis of La{sub 1-x}Ag{sub y}MnO{sub 3} ceramic materials on their physical properties has been elucidated.

Abdulvagidov, Sh. B., E-mail: abdulvagidov@iwt.ru; Gamzatov, A. G. [Russian Academy of Sciences, Amirkhanov Institute of Physics, Dagestan Scientific Center (Russian Federation); Mel'nikov, O. V.; Gorbenko, O. Yu. [Moscow State University (Russian Federation)

2009-12-15

63

The Properties Of The Samarium Fibre Laser  

NASA Astrophysics Data System (ADS)

The optical properties of trivalent Samarium doped silica glass fibres are described. This material has a narrow fluorescence of 2.2 nm f.w.h.m. at a wavelength of 650 nm. Visible laser emission is obtained at this wavelength when the fibre is pumped in a Fabry Perot cavity. The performance of the laser in continuous, Q-switched and self mode-locked operation is described.

Farries, Mark C.; Morkel, Paul R.; Townsend, Janet E.

1990-02-01

64

Impact of Thermal Aging on the Microstructure Evolution and Mechanical Properties of Lanthanum-Doped Tin-Silver-Copper Lead-Free Solders  

NASA Astrophysics Data System (ADS)

An extensive study is made to analyze the impact of pure lanthanum on the microstructure and mechanical properties of Sn-Ag-Cu (SAC) alloys at high temperatures. Different compositions are tested; the temperature applied for the isothermal aging is 150°C, and aging times of 10 h, 25 h, 50 h, 100 h, and 200 h are studied. Optical microscopy with cross-polarized light is used to follow the grain size, which is refined from 8 mm to 1 mm for as-cast samples and is maintained during thermal aging. Intermetallic compounds (IMCs) present inside the bulk Sn matrix affect the mechanical properties of the SAC alloys. Due to high-temperature exposure, these IMCs grow and hence their impact on mechanical properties becomes more significant. This growth is followed by scanning electron microscopy, and energy-dispersive spectroscopy is used for elemental mapping of each phase. A significant refinement in the average size of IMCs of up to 40% is identified for the as-cast samples, and the coarsening rate of these IMCs is slowed by up to 70% with no change in the interparticle spacing. Yield stress and tensile strength are determined through tensile testing at 20°C for as-cast samples and after thermal aging at 150°C for 100 h and 200 h. Both yield stress and tensile strength are increased by up to 20% by minute lanthanum doping.

Sadiq, Muhammad; Pesci, Raphaël; Cherkaoui, Mohammed

2013-03-01

65

Metals fact sheet - samarium  

SciTech Connect

The crustal abundance of samarium is 7 ppm, similar to that of praseodymium and gadolinium. About 50 percent of the total samarium oxide produced worldwide comes from the mining of monazite. Bastnasite accounts for approximately 40 percent of samarium oxide production, and the remaining 10 percent is derived from other rare earth minerals such as xenotime, apatite, loparite, and rare earth clays. Monazite is usually found in alluvial or beach deposits associated with other heavy minerals, typically rutile and zircon, and is recovered by suction dredging or bucket wheel excavation. The heavy minerals are subsequently separated by gravity, magnetic, and/or electrostatic means, and the resulting monazite concentrate undergoes a series of caustic and acid leaching steps to isolate the rare earths. Bastnasite, on the other hand, is a fluorocarbonate associated with igneous intrusions in quartzite or epithermal, fluorite-bearing veins, and is mined by open-pit methods. The ore is beneficiated by flotation, then acid-leached, filtered and calcined to produce a rare earth concentrate. Although a light rare earth, samarium oxide is isolated only after about three stages of solvent extraction, together with heavier oxides of gadolinium, terbium, and yttrium.

NONE

1993-10-01

66

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

NASA Astrophysics Data System (ADS)

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.

Sadiq, Muhammad

67

Structure and properties of antimony-doped lanthanum molybdate La{sub 2}Mo{sub 2}O{sub 9}  

SciTech Connect

Polycrystalline samples of the composition La{sub 2}Mo{sub 2-x}Sb{sub x}O{sub 9-y}, where 0 {<=} x {<=} 0.05, were prepared by solid-phase synthesis. Single crystals of La{sub 2}Mo{sub 1.96}Sb{sub 0.04}O{sub 8.17} were obtained by spontaneous crystallization from flux. The structure of the metastable {beta}{sub ms} phase of this compound was determined at room temperature by X-ray diffraction. It was found that the La, Mo, and O1 atoms are displaced from the threefold axis on which they are located in the high-temperature {beta} phase. It was shown that molybdenum atoms in the crystal structure are partially replaced by antimony atoms, which are located on the threefold axis. In antimony-doped crystals, lanthanum atoms partially return to the site on the threefold axis and the coordination environment of molybdenum cations becomes more ordered, thus facilitating the stabilization of the cubic phase at room temperature. Calorimetric measurements (DSC) showed that the introduction of Sb as the dopant into the La{sub 2}Mo{sub 2}O{sub 9} structure leads to a decrease in the temperature of the {alpha} {yields} {beta} phase transition from 570 to 520 Degree-Sign C and to the partial suppression of this transition. The temperature behavior of the conductivity confirms the DSC data. Thus, doping with Sb contributes to the stabilization of the cubic phase at room temperature.

Alekseeva, O. A., E-mail: olalex@ns.crys.ras.ru; Verin, I. A.; Sorokina, N. I. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Kharitonova, E. P.; Voronkova, V. I. [Moscow State University (Russian Federation)

2011-05-15

68

Tape method of forming a thin layer of doped lanthanum chromite particles and of bonding such on an electrode  

DOEpatents

A combustible polymer film, useful for application of an interconnection on an electrode is made by: (1) providing doped LaCro[sub 3] particles; (2) dispersing doped LaCrO[sub 3] particles in a solvent, to provide a dispersion; (3) screening the dispersion to provide particles in the range of from 30 micrometers to 80 micrometers; (4) admixing a fugitive polymer with the particles; (5) casting the dispersion to provide a film; (6) drying the film; and (7) stripping the film. The film can then be applied to a porous, preheated electrode top surface, and then a dense skeletal LaCrO[sub 3] structure is electrochemically vapor deposited between and around the doped LaCrO[sub 3] particles. Additional solid oxide electrolyte and fuel electrode layers can then be added to provide a fuel cell. 4 figs.

Richards, V.L.; Singhal, S.C.; Pal, U.B.

1992-07-21

69

Crystal growth of Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O in aqueous solutions: Film formation and samarium doping  

SciTech Connect

Crystalline cerium oxide carbonate hydrate (Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O) was grown in aqueous solutions at a low temperature of 80 deg. C under ambient pressure. When cerium nitrate was used as a starting material, large Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O particles were precipitated through homogeneous nucleation and subsequent fast crystal growth. In contrast, the usage of cerium chloride was found to promote the preferential precipitation of Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O on foreign substrates through heterogeneous nucleation and slow crystal growth. This phenomenon was applied to a chemical bath deposition of Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O films. Immersion of glass substrates in the solution at 80 deg. C for typically 24h resulted in formation of solid films with a unique morphology like a micrometer-scale brush. It was also found that samarium could be incorporated into Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O during the crystal growth in the solutions, as evidenced by characteristic photoluminescence of Sm{sup 3+} in heating products of CeO{sub 2}. These results suggest that rare-earth oxide carbonate hydrates with a variety of compositions and morphologies can be synthesized from the aqueous solutions.

Oikawa, Masashi [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Fujihara, Shinobu [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)]. E-mail: shinobu@applc.keio.ac.jp

2005-06-15

70

Effect of lanthanum doping on tetragonal-like BiFe O3 with mixed-phase domain structures  

NASA Astrophysics Data System (ADS)

The recent discoveries of both chemical-driven and strain-driven morphotropic phase boundaries (MPBs) in BiFe O3 (BFO) thin films have opened up new horizons in developing high-performance lead-free piezoelectrics. An attempt to bridge these two MPBs is made by doping La into highly strained BFO thin films with the coexistence of tetragonal-like and rhombohedral-like phases. The structural, morphological, and ferroelectric properties of such films are investigated. It is observed that La doping changes the energy landscape between the tetragonal-like and the rhombohedral-like polymorphs due to the chemical pressure imposed by the La substitution. Polar instability is found upon increasing La doping for the in-plane polarization component, which correlates with the vanishing of in-plane ferroelectric domain structures. The transition sequence of the in-plane ferroelectric polarization resembles that previously reported for the bulklike rhombohedral phase of BFO under continuous La doping, indicating the universality of the chemical-alloying effect on the ferroelectric order.

You, Lu; Caesario, Petrus; Fang, Liang; Ren, Peng; Wang, Le; Zhou, Yang; Gruverman, Alexei; Wang, Junling

2014-10-01

71

X-ray radiometric determination of lanthanides (praseodymium, neodymium, and samarium) in soils  

NASA Astrophysics Data System (ADS)

A procedure of the modified energy-dispersive X-ray fluorescence method (X-ray radiometric analysis using a 241Am radionuclide source) was developed for the identification of praseodymium, neodymium, and samarium. The procedure is based on the exclusion of the disturbing effect of barium and lanthanum on the lines of praseodymium and neodymium, as well as the effect of lanthanum and cerium on the lines of samarium. On the basis of the new method, data were obtained on the geochemistry of three lanthanides in soils of the northern taiga. Praseodymium and neodymium were detected by the X-ray radiometric method even in podzols depleted of heavy metals. The method can detect samarium at the levels of the soil clarke and higher. Positive samarium (or, wider, rare-earth) anomalies can be expected in the soils located not far from the deposits of apatite-nephelines, loparites, and phosphorites and in the soils developed on alkaline granites and carbonate weathering crusts.

Savichev, A. T.; Vodyanitskii, Yu. N.

2011-04-01

72

Effect of Hydrogen Anneals on Niobium-Doped Lead Zirconate Titanate Capacitors with Lanthanum Strontium Cobalt Oxide/Platinum Electrodes  

NASA Astrophysics Data System (ADS)

Ferroelectric capacitors, being oxide ceramics, are very sensitive to the effects of hydrogen environments at elevated temperatures [H. Ashida et al..: Integr. Ferroelectr. 21 (1998) 97]. After a capacitor has been exposed directly to a annealing hydrogen environment at low hydrogen partial pressures, the electrical properties of the device can deteriorate and leakage currents can increase. At higher hydrogen concentration gradients, such as the formidable forming gas annealing, physical failure of the inter-layer dielectric (ILD) and/or top electrode adhesion can occur. The authors have examined various structural approaches to mitigate the effects of hydrogen damage on integrated ferroelectric lead zirconate titanate (PZT) capacitors. These approaches, including the use of a titanium dioxide barrier layer above the PZT to impede the reducing effect of hydrogen on the ceramic and the use of electrode layers other than platinum to eliminate the generation of free hydrogen ions by catalyst action [S. Aggarwal et al..: Appl. Phys. Lett. 73 (1998) 1973]. The authors have found that niobium-doped PZT capacitors using LSCO/platinum electrodes passivated with titanium dioxide will recover from 1% forming gas annealing within 30 minutes at 450°C in nitrogen.

Evans, Joe; Jr., Jr.; Boyer, Leonard; Velasquez, Geri; Ramesh, Ramamoorthy; Aggarwal, Sanjeev; Keramidas, Vassillis

1999-09-01

73

Evolution of orientation degree, lattice dynamics and electronic band structure properties in nanocrystalline lanthanum-doped bismuth titanate ferroelectric films by chemical solution deposition.  

PubMed

Ferroelectric lanthanum (La)-substituted bismuth titanate (Bi(4-x)La(x)Ti(3)O(12), BLT) nanocrystalline films with the composition range of 0 ?x? 1 have been directly deposited on n-type Si?(100) substrates by chemical solution deposition. The La substitution effects on the preferred orientation, surface morphology, phonon modes, emission bands and electronic band structures of the BLT films have been investigated by microscopy, Raman scattering, photoluminescence and spectroscopic ellipsometry at room temperature. X-Ray diffraction analysis shows that the films are polycrystalline and exhibit the pure perovskite phase structure. With increasing La composition, the (100)-orientation degree can be enhanced and the root-mean-square roughnesses slightly increase from 6.5 to 8.3 nm. It was found that the Raman-active mode A(1g)[Bi] at about 59 cm(-1) is unchanged while the B(1g) and A(1g)[Ti] phonon modes at about 648 and 853 cm(-1) are shifted towards higher frequency by about 36.6 and 8.4 cm(-1), respectively. Photoluminescence spectra show that the intensity of the peak located at about 2.3 eV increases with the La composition, except for the Bi(3)LaTi(3)O(12) film, due to the smallest grain size and oxygen vacancy defects. The optical constants of the BLT films have been uniquely extracted by fitting the measured ellipsometric spectra with a four-phase layered model (air/surface rough layer/BLT/Si) in the photon energy range of 0.73-4.77 eV. The Adachi dielectric function model has been successfully applied and reasonably describes the optical response behavior of the ferroelectric BLT films. Moreover, the film packing density decreases while the optical band gap linearly increases from 3.610 ± 0.066 to 3.758 ± 0.068 eV with increasing La composition. It is surmised that the phenomena are mainly ascribed to the variations of the electronic structure, especially for the conduction band, which is perturbed by the La doping. PMID:21743909

Zhang, Jinzhong; Chen, Xiangui; Jiang, Kai; Shen, Yude; Li, Yawei; Hu, Zhigao; Chu, Junhao

2011-08-21

74

Soft X-Ray Spectroscopic Study of Dense Strontium-Doped Lanthanum Manganite Cathodes for Solid Oxide Fuel Cell Applications  

SciTech Connect

The modification of the Mn charge-state, chemical composition and electronic structure of La0.8Sr0.2MnO3 (LSMO) cathodes for solid oxide fuel cell (SOFC) applications remains an area of interest, due to the poorly understood enhanced catalytic activity (often referred to as the "burn-in" phenomenon) observed after many hours of operation. Using a combination of core-level X-ray photoemission spectroscopy (XPS), X-ray emission/absorption spectroscopy (XES/XAS), resonant inelastic X-ray scattering (RIXS) and resonant photoemission spectroscopy (RPES), we have monitored the evolution of these properties in LSMO at various stages of fabrication and operation. By rapidly quenching and sealing in vacuum, we were able to directly compare the pristine (as-fabricated) LSMO with both "heat-treated" (800°C in air, and no bias) and "burnt-in" (800°C in air, -1 V bias) LSMO cathodes i.e. before and after the activation observed in our electrochemical impendence spectroscopy measurements. Comparison between the O K-edge XAS/XES and Mn L3,2-edge XAS of pristine and “burnt-in” LSMO cathodes revealed a severe change in the oxygen environment along with a reduced Mn2+ presence near the surface following activation. The change in the oxygen environment is attributed to SrxMnyOz formation, along with possible passive SrO and Mn3O4 species. We present evidence from our “heat-treated” samples that SrxMnyOz regions form at elevated temperatures in air before the application of a cathodic bias. Our core-level XPS, Mn L3,2-edge RIXS and Mn L3 RPES studies of “heat-treated” and pristine LSMO determined that SOFC environments result in La-deficiency (severest near the surface) and stronger Mn4+ contribution, leading to the increased insulating character of the cathode prior to activation. The passive Mn2+ species near the surface and increased hole-doping (>0.6) of the LSMO upon exposure to the operating environment are considered responsible for the initially poor performance of the SOFC. Meanwhile, the improved oxygen reduction following the application of a cathodic bias is considered to be due to enhanced bulk oxygen-ion diffusion resulting from the migration of Mn2+ ions towards the LSMO/electrolyte interface and the SrxMnyOz regions facilitating enhanced bulk oxygen reduction reaction kinetics.

Piper, L.F.J.; Preston, Andrew R.H.; Cho, Sang Wan; DeMasi, Alexander; Chen, Bin; Laverock, J.; Smith, K. E.; Miara, Lincoln J.; Davis, Jacob N.; Basu, Soumendra; Pal, Uday B.; Gopalan, Srikanth; Saraf, Laxmikant V.; Kaspar, Tiffany C.; Matsuura, A. Y.; Glans, P.A.; Guo, Jianzhong

2010-12-02

75

Kinetic study of the formation of oxygen vacancy on lanthanum manganite electrodes  

Microsoft Academic Search

Strontium doped lanthanum manganite (LSM) has been considered one of the most promising cathode materials for solid oxide fuel cells (SOFC). The electrochemical reduction of oxygen on lanthanum manganite (LSM) electrodes has been investigated by cyclic voltammetry, alternating current (ac) impedance, and, in particular, potential step. An emphasis was given to the study of the kinetics of the formation of

Yi Jiang; Shizhong Wang; Yahong Zhang; Jingwang Yan; Wenzhao Li

1998-01-01

76

Novel samarium/erbium and samarium/terbium codoped glass phosphor for application in warm white light-emitting-diode  

NASA Astrophysics Data System (ADS)

Tunable polychromatic light emission within the low color correlated temperature range was produced using terbiumand/ or erbium-samarium co-doped PbGeO3:PbF2:CdF2 glass phosphor. The phosphors were synthesized, and their luminescence characteristics were examined under UV-blue light-emitting-diode laser excitation. Luminescence emission around 490, 545, 600, and 645 nm in Tb3+/Sm3+ and 525, 545, 600, and 645 nm in Er3+/Sm3+ co-doped phosphor was obtained and analyzed as a function of the active ions concentration, and excitation wavelength. Color tunability in the red-orange-yellow-green region was achieved combining of Tb3+, Er3+, and Sm3+ ions contents. Results suggest that the color-tunable polychromatic light emitter phosphor herein reported is a promising novel candidate for application in cold white-light LED-based illumination technology

da Silva, Cosmo M.; Gouveia-Neto, Artur S.; Bueno, Luciano A.

2014-02-01

77

Synthesis and luminescence properties of Ln 3+ (Ln 3+ = Er 3+, Sm 3+)-doped barium lanthanum tungstate BaLa 2WO 7 phosphors  

NASA Astrophysics Data System (ADS)

BaLa 2WO 7 phosphors activated with the trivalent rare-earth Er 3+ and Sm 3+ were synthesized via a solid-state reaction using a vibrating-mill method, and their luminescence properties were investigated. Er 3+-doped BaLa 2WO 7 and Sm 3+-doped BaLa 2WO 7 emit bright green and reddish-orange light, respectively. The photoluminescence investigations revealed that the phosphors exhibit apparent characteristic emissions from the 2H and 4S state, respectively, to the 4I ground state for Er 3+, and 4G to 6H states for Sm 3+ under near-UV excitation. The green emission of the Er 3+-doped BaLa 2WO 7 phosphor had CIE chromaticity coordinates (0.249, 0.717) with a dominant wavelength of 546 nm and a color purity of 92%. The Sm 3+-doped BaLa 2WO 7 phosphor had color coordinates (0.558, 0.441), a dominant wavelength of 606 nm, and 94% color purity. The sharp emission peaks and excellent luminescence properties show that BaLa 2WO 7 is a suitable host for rare-earth-doped phosphors, which may be suitable for optical applications.

Yan, Shao-An; Wang, Jian-Wen; Chang, Yee-Shin; Hwang, Weng-Sing; Chang, Yen-Hwei

2011-11-01

78

Quenching experiments on cobalt-samarium magnets  

Microsoft Academic Search

The purpose of this study was to further elucidate the post-sintering heat treatment response of liquid-phase sintered cobalt-samarium magnets. Specimens water quenched from temperatures between 500°C and the prior sintering temperature, 1117°C, were subjected to magnetic and X-ray diffraction analyses. All specimens contained a mixture of samarium oxides, one of which was cubic Sm2O3. A new and unidentified phase was

F. Jones; H. Lehman; J. Smeggil

1972-01-01

79

Generation and Chemical Reaction of Lanthanum-Carbon Binary Clusters Shigeo MARUYAMA*, Masamichi KOHNO* and Shuhei INOUE**  

E-print Network

* * ** Generation and Chemical Reaction of Lanthanum-Carbon Binary Clusters Shigeo MARUYAMA*, Masamichi KOHNO* and Shuhei INOUE** Lanthanum-carbon binary clusters (LaCn) and carbon clusters (Cn) were doped graphite material, cluster ions with one La atom and even number of carbon atoms starting from La

Maruyama, Shigeo

80

Effect of trace lanthanum ion on dissolution and crystal growth of calcium carbonate  

NASA Astrophysics Data System (ADS)

Impurity effects of trace lanthanum ion (La 3+) on the dissolution and growth of calcium carbonate were studied with in situ observation techniques. Dissolution kinetics of two polymorphs of calcium carbonate, calcite and vaterite, were investigated by monitoring the pH in the solution with laser-induced fluorescence spectroscopy using a pH-sensitive reagent, seminaphthorhodafluors. No effect on dissolution of vaterite was observed with the spectroscopic observations, whereas calcite dissolution was significantly inhibited by lanthanum ion with concentrations higher than 1 ?M. Crystal growth and dissolution processes of calcite under the lanthanum-doped condition were observed by means of atomic force microscopy. Step propagations during crystal growth and dissolution of calcite were inhibited by trace lanthanum ion (5 ?M). An insoluble thin layer of lanthanum carbonate deposited on the step site of the calcite surface could be a possible cause of the inhibitions observed both for dissolution and growth.

Kamiya, Natsumi; Kagi, Hiroyuki; Tsunomori, Fumiaki; Tsuno, Hiroshi; Notsu, Kenji

2004-07-01

81

ZIRCONIA-BASED MIXED POTENTIAL CARBON MONOXIDE/HYDROCARBON SENSORS WITH LANTHANUM MAGNESIUM OXIDE, AND TERBIUM-DOPED YTTRIUM STABILIZED ZIRCONIA ELECTRODES  

SciTech Connect

We have investigated the performance of dual metal oxide electrode mixed potential sensors in an engine-out, dynamometer environment. Sensors were fabricated by sputtering thin films of LaMnO{sub 3} and Tb-doped YSZ onto YSZ electrolyte. Au gauze held onto the metal oxide thin films with Au ink was used for current collection. The exhaust gas from a 4.8L, V8 engine operated in open loop, steady-state mode around stoichiometry at 1500 RPM and 50 Nm. The sensor showed a stable EMF response (with no hysteresis) to varying concentrations of total exhaust gas HC content. The sensor response was measured at 620 and 670 C and shows temperature behavior characteristic of mixed potential-type sensors. The results of these engine-dynamometer tests are encouraging; however, the limitations associated with Au current collection present the biggest impediment to automotive use.

E. L. BROSHA; R. MUKUNDAN; ET AL

2000-10-01

82

Dopant distributions in rare-earth-doped alumina  

Microsoft Academic Search

The distribution of yttrium and lanthanum dopants has been mapped in yttrium- and lanthanum-doped polycrystalline aluminas using imaging secondary-ion mass spectrometry (imaging-SIMS). Both dopants segregate to grain boundaries and pore surfaces. On average, yttrium occupies 7.1%--9.0% of the available grain-boundary cation sites, whereas lanthanum occupies only 2.0%--5.2%. In 1,000-ppm-yttrium-doped alumina, an abundance of yttrium aluminum garnet precipitates also is observed.

A. M. Thompson; H. M. Chan; M. P. Harmer; D. B. Williams; K. K. Soni; J. M. Chabala; R. Levi-Setti

1997-01-01

83

Synthesis and Magnetic Properties of Novel Lanthanide SERIES(2-X) Metal(x) Copper OXYGEN(4+Y) Compositions (lanthanide Series = Lanthanum, Praseodymium, Neodymium, Samarium, Europium, Gadolinium; Metal = Calcium, Strontium, Barium; 0 <= X <= 0.2; -0.5 <= Y <= 0.5)  

NASA Astrophysics Data System (ADS)

Ln_2CuO_4 (Ln = La, Pr, Nd, Sm, Eu, Gd) undergo structural transitions to oxygen-reduced structures Ln_2CuO_{4-d} with Ln = La, d = 1/3 and Ln = Pr, Nd, Sm, Eu, Gd, d = 1/2. The Nd_2CuO_4-type (T^'-phase) La _2CuO_{4+d} is observed after reoxygenation of oxygen-reduced La_2CuO _{3.67} structure below 500 ^circC. The magnetic properties of T/O (K_2NiF_4-type structure) -phase La_2CuO_4 systems show quite different behaviors compared with those of conventional solid state reacted La_2CuO_4 systems. The implications of these nonsuperconducting behaviors within the superconducting carrier concentrations are discussed from the structural point of view. La_{2-x}M_{x }CuO_{4+d} (M = Ca, Sr; x = 0.05, 0.15), synthesized by the low temperature route, also contain excess oxygen and show different physical properties. ^{139 }La NQR measurements of nonsuperconducting La_{1.85}Sr_{0.15 }CuO_{4.04} show metallic properties. The tolerance factor, which is based on ionic radii, is quite successful to describe structural properties of K_2NiF_4 related cuprate compounds. With anisotropic thermal motions of apical oxygens in La_2CuO_4, we discuss the crucial role of out-of-plane oxygens for stabilization of cuprate structures. The magnetic phase diagram and phase separation of La_{2-x}Sr_{x}CuO _{4+delta} system (0.000 <= x<= 0.030, 0.0<=delta) are reported. From the decrease of T_ {c} by doping level, we infer the localization and pair-breaking mechanism induced by doped holes. Phase separation is realized within the appearance of three-dimensional antiferromagnetic order. We also observe scaling properties of susceptibilities versus renormalized temperatures and infer the finite size effects by doped holes from the scaling. ^{139}La NQR spin-lattice relaxation rates vs temperature are presented for La_{2-x}Sr_{x }CuO_4 with x = 0.02 to 0.08. The spin -lattice relaxation rate below ~2 T_{N}(x) shows a power -law critical behavior while above ~2 T_{N}(x) it follows an exponential law with a small x-dependent spin-stiffness constant, where T_{N} is the magnetic ordering temperature. It is argued that the spin-lattice relaxation rate arises from fluctuations of the staggered magnetization in locally ordered mesoscopic domains. We infer that the magnetically ordered state is not a conventional spin glass.

Cho, Jin Hyung

1992-01-01

84

Oxidation of a thin samarium film on iridium  

NASA Astrophysics Data System (ADS)

Thermal desorption spectroscopy has been used to study the interaction of oxygen with a thin (<1 nm) samarium film deposited onto a textured iridium ribbon. Desorption of Sm atoms from Ir surface takes place from various states (chemisorbed, condensed, from compound with iridium, and oxide). The formation of samarium oxide is observed already at room temperature. As the temperature increases to T = 1100 K, a compound of samarium with iridium is formed at the first stage and then oxygen interacts with Sm atoms from this compound and "slow" (compared to the first process) growth of samarium oxide takes place.

Afanas'eva, E. Yu.

2014-06-01

85

Metallic behavior of lanthanum disilicide  

NASA Technical Reports Server (NTRS)

Polycrystalline thin films of LaSi2 were prepared by reaction of sputter-deposited lanthanum layers with silicon wafers. Samples of the low-temperature tetragonal and the high-temperature orthorhombic phases were separately obtained. The room-temperature intrinsic resistivities were 24 and 57 microohm cm for the low- and high-temperature structures, respectively. Although lanthanum disilicide had been previously reported to be a semiconductor, classical metallic behavior was found for both phases.

Long, Robert G.; Bost, M. C.; Mahan, John E.

1988-01-01

86

Structural instabilities in lanthanum cuprate superconductors  

SciTech Connect

Subtle but well characterized structural phase transformations occur at low temperatures in some lanthanum cuprate superconductors. These transformations, which involve collective tilting of the CuO{sub 6} octahedra, have a strong influence on superconducting and normal state properties. Experiments suggest that for a given hole doping the following hierarchy exists for superconductivity in these materials: T{sub c}(HTT)>T{sub c}(LTO)>T{sub c}(LTT), where HTT represents the untilted structure and LTO and LTT are the two limiting low temperature tilted structures. An additional very strong suppression of T{sub c}, suggestive of a competing electronic groundstate, occurs in the LTT phase for a hole to Cu ratio of 1/8. Neither of these effects are understood at present. This paper reviews both the evidence upon which these conclusions are based and some outstanding unanswered questions.

Axe, J.D. [Brookhaven National Lab., Upton, NY (United States); Crawford, M.K. [DuPont, Wilmington, DE (United States)

1994-04-01

87

Lanthanum Bromide Detectors for Safeguards Measurements  

SciTech Connect

Lanthanum bromide has advantages over other popular inorganic scintillator detectors. Lanthanum bromide offers superior resolution, and good efficiency when compared to sodium iodide and lanthanum chloride. It is a good alternative to high purity germanium detectors for some safeguards applications. This paper offers an initial look at lanthanum bromide detectors. Resolution of lanthanum bromide will be compared lanthanum chloride and sodium-iodide detectors through check source measurements. Relative efficiency and angular dependence will be looked at. Nuclear material spectra, to include plutonium and highly enriched uranium, will be compared between detector types.

Wright, J.

2011-05-25

88

Vapor deposited samarium zirconate thermal barrier coatings Hengbei Zhao a,  

E-print Network

Vapor deposited samarium zirconate thermal barrier coatings Hengbei Zhao a, , Carlos G. Levi b form 24 March 2009 Available online 1 April 2009 Keywords: Samarium zirconate Directed-vapor deposition applications. An electron-beam evaporation, directed-vapor deposition (EB-DVD) technique has been used

Wadley, Haydn

89

Ames Lab 101: Lanthanum Decanting  

SciTech Connect

Ames Laboratory scientist Trevor Riedemann explains the process that allows Ames Laboratory to produce some of the purest lanthanum in the world. This and other high-purity rare-earth elements are used to create alloys used in various research projects and play a crucial role in the Planck satellite mission.

Riedemann, Trevor

2010-01-01

90

Ames Lab 101: Lanthanum Decanting  

ScienceCinema

Ames Laboratory scientist Trevor Riedemann explains the process that allows Ames Laboratory to produce some of the purest lanthanum in the world. This and other high-purity rare-earth elements are used to create alloys used in various research projects and play a crucial role in the Planck satellite mission.

Riedemann, Trevor

2012-08-29

91

Initial stages of the interaction with oxygen of samarium thin films grown on the iridium surface  

NASA Astrophysics Data System (ADS)

The interaction of thin (<1 nm) samarium films deposited on a textured iridium ribbon has been investigated by thermal desorption spectrometry. Samarium atoms deposited at T = 300 K desorb in three phases associated with the formation of a submonolayer samarium coverage on iridium, a compound of samarium with iridium, and a multilayer samarium film. The interaction with oxygen leads to the appearance of a new desorption phase, which is associated with the formation of samarium oxide. Oxidation of samarium is observed during exposure in oxygen already at room temperature. An increase in temperature of the iridium ribbon, at which exposure in oxygen occurs, to T = 1100 K leads to the formation of the compound of samarium with iridium. Further, the film of the compound decomposes in the course of interaction with oxygen, and samarium oxide grows on the Ir surface.

Afanas'eva, E. Yu.

2014-08-01

92

Localization of lanthanum in bone of chronic renal failure rats after oral dosing with lanthanum carbonate  

Microsoft Academic Search

Localization of lanthanum in bone of chronic renal failure rats after oral dosing with lanthanum carbonate.BackgroundLanthanum carbonate has been shown to be a safe, effective phosphate-binding agent. We have shown that an impaired mineralization in chronic renal failure rats treated with high doses of lanthanum carbonate develops secondary to phosphate depletion and is therefore pharmacologically mediated rather than a direct

Geert J. Behets; Steven C. Verberckmoes; LINE OSTE; An R. Bervoets; MURIELLE SALOMÉ; Alan G. Cox; JOHN DENTON; Marc E. De Broe; Patrick C. D'Haese

2005-01-01

93

Absolute Bioavailability and Disposition of Lanthanum in Healthy Human Subjects Administered Lanthanum Carbonate  

Microsoft Academic Search

Lanthanum carbonate [La2(CO3)3] is a noncalcium, nonaluminum phosphate binder indicated for hyperphosphatemia treatment in end-stage renal disease. A randomized, open-label, parallel-group, phase I study was conducted to determine absolute bioavailability and investigate excretory routes for systemic lanthanum in healthy subjects. Twenty-four male subjects were randomized to a single lanthanum chloride (LaCl3) intravenous infusion (120 &mgr;g elemental lanthanum over a 4-hour

Michael Pennick; Kerry Dennis; Stephen J. P. Damment

2006-01-01

94

Electromagnetic containerless reaction of samarium with cobalt for the formation of samarium-cobalt alloys  

NASA Technical Reports Server (NTRS)

The electromagnetic levitation technique has been used to obtain nearly stoichiometric SmCo5, with the reaction temperature controlled by a gas jet. The results of several experiments carried out at a 450 kHz, 25 kw RF power levitation facility using different reaction times and cooling rates are presented. It is shown that reaction rates achieved with the levitation technique are larger than the expected diffusion rate in the system liquid samarium-solid cobalt. It is also shown that substantial mixing occurs in the RF-levitated melt.

Chang, C. W.; Das, D. K.; Kumar, K.; Frost, R. T.

1982-01-01

95

Samarium-neodymium direct dating of fluorite mineralization.  

PubMed

The direct dating of many styles of hydrothermal mineralization has proved difficult, limiting understanding of the geological processes that lead to crustal fluid flow and the formation of major ore deposits. The hydrothermal mineral fluorite (CaF(2)) displays large variations in rare earth element (REE) abundance and samarium/neodymium ratios within a single vein. Samarium-neodymium dating of fluorite from the classic granite-hosted tin deposits of southwest England demonstrates its use as a precise chronometer of mineralization. The concentrations of light rare earth elements (LREEs) in the fluorites are highly variable and suggest the coeval precipitation of an LREE-rich phase as the most likely cause of the extreme variation in samarium/neodymium ratios. PMID:17843229

Chesley, J T; Halliday, A N; Scrivener, R C

1991-05-17

96

Samarium Ion Exchanged Montmorillonite for High Temperature Cumene Cracking Reaction  

NASA Astrophysics Data System (ADS)

Montmorillonite clay is cation exchanged with samarium and its catalytic influence in cumene cracking reaction is investigated. Effect of exchange with sodium ions on further exchange with samarium ions is also noted. Acidity measurements are done using Temperature Programmed Desorption (TPD) of ammonia. The retention of basic structure is proved from FTIR spectra and XRD patterns. Elemental analysis result shows that samarium exchange has occurred, which is responsible for the higher catalytic activity. Surface area and pore volume remains more or less unaffected upon exchange. Thermogravimetric analysis indicates the enhanced thermal stability on exchanging. Cumene cracking reaction is carried out at atmospheric pressure in a fixed bed glass reactor at 673 K. The predominance of Brønsted acidity is confirmed from high selectivity to benzene.

Binitha, N. N.; Silija, P. P.; Suraj, V.; Yaakob, Z.; Sugunan, S.

2011-02-01

97

The Basis for Developing Samarium AMS for Fuel Cycle Analysis  

SciTech Connect

Modeling of nuclear reactor fuel burnup indicates that the production of samarium isotopes can vary significantly with reactor type and fuel cycle. The isotopic concentrations of {sup 146}Sm, {sup 149}Sm, and {sup 151}Sm are potential signatures of fuel reprocessing, if analytical techniques can overcome the inherent challenges of lanthanide chemistry, isobaric interferences, and mass/charge interferences. We review the current limitations in measurement of the target samarium isotopes and describe potential approaches for developing Sm-AMS. AMS sample form and preparation chemistry will be discussed as well as possible spectrometer operating conditions.

Buchholz, B A; Biegalski, S R; Whitney, S M; Tumey, S J; Weaver, C J

2008-10-13

98

Samarium-145 and its use as a radiation source  

DOEpatents

The present invention covers a new radiation source, samarium-145, with radiation energies slightly above those of I-125 and a half-life of 340 days. The samarium-145 source is produced by neutron irradiation of SM-144. This new source is useful as the implanted radiation source in photon activation therapy of malignant tumors to activate the stable I-127 contained in the IdUrd accumulated in the tumor, causing radiation sensitization and Auger cascades that irreperably damage the tumor cells. This new source is also useful as a brachytherapy source.

Fairchild, Ralph G. (Setauket, NY); Laster, Brenda H. (Plainview, NY); Packer, Samuel (Great Neck, NY)

1989-01-01

99

Investigation into nanostructured lanthanum halides and CeBr3 for nuclear radiation detection  

Microsoft Academic Search

Nanocomposites may enable the use of scintillator materials such as cerium-doped lanthanum fluoride (LaF3:Ce) and cerium bromide (CeBr3) without requiring the growth of large crystals. Nanostructured detectors may allow us to engineer immensely sized detectors of flexible form factors that will have a broad energy range and an energy resolution sufficient to perform isotopic identification. Furthermore, nanocomposites are easy to

Paul Guss; Ronald Guise; Sanjoy Mukhopadhyay; Ding Yuan

2011-01-01

100

SOLITONS AND OPTICAL FIBERS: Self-Q-switched ytterbium-doped cladding-pumped fibre laser  

NASA Astrophysics Data System (ADS)

A self-Q-switched ytterbium-doped double-clad fibre laser is described. A samarium-doped fibre is used as a filter for protecting a pump source. A fibre coupler is employed to obtain a nonlinear feedback. The mechanism of pulse formation in the laser is considered, and the dependence of its output pulse on the coupler parameters is studied.

Grukh, Dmitrii A.; Kurkov, Andrei S.; Razdobreev, I. M.; Fotiadi, A. A.

2002-11-01

101

Discovery of Samarium, Europium, Gadolinium, and Terbium Isotopes  

E-print Network

Currently, thirty-four samarium, thirty-four europium, thirty-one gadolinium, and thirty-one terbium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

E. May; M. Thoennessen

2012-01-19

102

Discovery of samarium, europium, gadolinium, and terbium isotopes  

SciTech Connect

Currently, thirty-four samarium, thirty-four europium, thirty-one gadolinium, and thirty-one terbium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

May, E.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2013-01-15

103

Reaction, transformation and delamination of samarium zirconate thermal barrier coatings  

E-print Network

Reaction, transformation and delamination of samarium zirconate thermal barrier coatings Hengbei zirconates have attracted interest for thermal barrier coatings (TBCs) because they have very low intrinsic.V. All rights reserved. 1. Introduction Thermal barrier coating (TBC) systems are an enabling materials

Wadley, Haydn

104

Jahn–Teller effect on the structure of the Sm-doped PbTiO 3: A theoretical approach  

Microsoft Academic Search

Samarium doped PbTiO3 (PT:Sm) and pure PbTiO3 (PT) powders were obtained by polymeric precursor method. These powders were characterized by X-ray diffraction (XRD) and theoretical calculations using the CRYSTAL98 program. The effect of the samarium atom is taken into account only indirectly. The experimental models were compared with the cubic (“ideal”) and tetragonal theoretical models. The structure deformations existent in

Maria F. C. Gurgel; Elaine C. Paris; José W. M. Espinosa; Carlos O. Paiva-Santos; Edson R. Leite; Antônio G. Souza; José A. Varela; Elson Longo

2007-01-01

105

Field free, directly heated lanthanum boride cathode  

DOEpatents

A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic fields which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

Leung, Ka-Ngo (Hercules, CA); Moussa, David (San Francisco, CA); Wilde, Stephen B. (Pleasant Hill, CA)

1991-01-01

106

Stabilized lanthanum sulphur compounds. [thermoelectric materials  

NASA Technical Reports Server (NTRS)

Lanthanum sulfide is maintained in the stable cubic phase form over a temperature range of from 500 C to 1500 C by adding to it small amounts of calcium, barium, or strontium. This compound is an excellent thermoelectric material.

Reynolds, G. H.; Elsner, N. B.; Shearer, C. H. (inventors)

1983-01-01

107

Dehydrated Lanthanum-exchanged Type Y Zeolite  

Microsoft Academic Search

Lanthanum atoms occupy different sites in the crystal structure of dehydrated type Y zeolite as the temperature changes, probably because of the absence of residual molecules for bonding at 725° C compared with their presence at lower temperatures.

J. V. Smith; J. M. Bennett; E. M. FLANIGEN

1967-01-01

108

Field free, directly heated lanthanum boride cathode  

DOEpatents

A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic field which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

Leung, Ka-Ngo; Moussa, D.; Wilde, S.B.

1987-02-02

109

Compact lanthanum hexaboride hollow cathode  

NASA Astrophysics Data System (ADS)

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 LaB6 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.

Goebel, Dan M.; Watkins, Ronald M.

2010-08-01

110

Lattice dynamics of the rare-earth element samarium  

NASA Astrophysics Data System (ADS)

The lattice dynamics of samarium is determined by in situ low-temperature nuclear inelastic scattering on a single crystalline (0001)Sm film, a polycrystalline Sm foil, and by first-principles theory. The ab initio calculated phonon dispersion relations and phonon density of states for the Sm-type structure and the double hexagonal-close-packed (dhcp) lattice, characteristic for light lanthanides, are compared. The dhcp unit cell, which is a factor of 2.24 smaller in height, exhibits more pronounced vibrational anisotropy in comparison to the Sm-type structure. The analysis reveals a minor influence of the spin-orbit coupling in the Sm atom on the lattice dynamics. A broadening of the longitudinal peak, not found in the calculations, suggests the influence of electron correlations on lattice dynamics in metallic samarium.

Bauder, Olga; Piekarz, Przemys?aw; Barla, Alessandro; Sergueev, Ilya; Rüffer, Rudolf; ?a?ewski, Jan; Baumbach, Tilo; Parlinski, Krzysztof; Stankov, Svetoslav

2013-12-01

111

Synthesis, structural and spectroscopic investigations of nanostructured samarium oxalate crystals.  

PubMed

Nanostructured samarium oxalate crystals were prepared via microwave assisted co-precipitation method. The crystal structure and morphology of the sample were analyzed using X-ray powder diffraction, Scanning electron microscopy and Transmission electron microscopy. The presence of functional groups is ascertained by Fourier transform infrared spectroscopy. Samarium oxalate nanocrystals of average size 20 nm were aggregated together to form nano-plate structure in sub-microrange. Detailed spectroscopic investigation of the prepared phosphor material was carried out by Judd-Ofelt analysis based on the UV-Visible-NIR absorption spectra and photoluminescence emission spectra. The analysis reveals that the transition from energy level (4)G5/2 to (6)H7/2 of Sm(3+) ion has maximum branching ratio and the corresponding orange emission can be used for display applications. PMID:24334063

Vimal, G; Mani, Kamal P; Biju, P R; Joseph, Cyriac; Unnikrishnan, N V; Ittyachen, M A

2014-03-25

112

Synthesis, structural and spectroscopic investigations of nanostructured samarium oxalate crystals  

NASA Astrophysics Data System (ADS)

Nanostructured samarium oxalate crystals were prepared via microwave assisted co-precipitation method. The crystal structure and morphology of the sample were analyzed using X-ray powder diffraction, Scanning electron microscopy and Transmission electron microscopy. The presence of functional groups is ascertained by Fourier transform infrared spectroscopy. Samarium oxalate nanocrystals of average size 20 nm were aggregated together to form nano-plate structure in sub-microrange. Detailed spectroscopic investigation of the prepared phosphor material was carried out by Judd-Ofelt analysis based on the UV-Visible-NIR absorption spectra and photoluminescence emission spectra. The analysis reveals that the transition from energy level 4G5/2 to 6H7/2 of Sm3+ ion has maximum branching ratio and the corresponding orange emission can be used for display applications.

Vimal, G.; Mani, Kamal P.; Biju, P. R.; Joseph, Cyriac; Unnikrishnan, N. V.; Ittyachen, M. A.

2014-03-01

113

Initial Observations: Cobalt-Mischmetal-Samarium Permanent Magnet Alloys  

Microsoft Academic Search

Several authors have reported successful fabrication of high-energy-product (20 MG Oe) Co5R-type cobalt-samarium permanent magnets. In earlier papers we have described preparation of such magnets by a liquid-phase sintering process sequence which includes powder preparation, magnetic alignment, pressing, sintering, and magnetizing. We have also described preparation of ternary compositions, primarily Co&sngbnd;Sm&sngbnd;Pr, by this process. In an effort to utilize more

M. G. Benz; D. L. Martin

1971-01-01

114

Cobalt-Mischmetal-Samarium Permanent Magnet Alloys: Process and Properties  

Microsoft Academic Search

Several authors have reported successful fabrication of high-energy product (15–20 MGOe) Co5R-type cobalt-samarium permanent magnets. In earlier papers we have described preparation of such magnets by a liquid-phase sintering process sequence which includes powder preparation, magnetic alignment, pressing, sintering, and magnetizing. We have also described preparation of ternary compositions, primarily Co&sngbnd;Sm&sngbnd;Pr, by this process. In an effort to utilize more

M. G. Benz; D. L. Martin

1971-01-01

115

Surface Chemistry of Supported Chromium Oxide on Lanthanum Carbonate  

Microsoft Academic Search

The surface chemistry of supported chromium oxide on lanthanum carbonate has been studied by TPD, FTIR, XPS, and electrophoretic measurement techniques. The active center for the oxidative dehydrogenation of isobutane to isobutylene was identified as a chromate species bound to the surface of lanthanum carbonate. This species was formed as a result of interaction between chromium oxide and lanthanum carbonate

Manh Hoang; Anthony E. Hughes; Joseph F. Mathews; Kerry C. Pratt

1997-01-01

116

Lanthanum carbonate: Time to abandon prejudices?  

Microsoft Academic Search

Since lanthanum carbonate has become available there has been much interest in its use as a non-calcium-containing phosphate binder, but also much speculation among scientists about possible aluminum-like toxicity. This Commentary focuses on the major aspects of this scientific controversy, confirming the safety and efficacy of this new phosphate binder.

D Brancaccio; M Cozzolino

2007-01-01

117

New High-Temperature Superconductors  

E-print Network

in Japan reported the first material, fluorine- doped lanthanum iron arsenic oxide (LaFeAsO(1-x)Fx), which had replaced the lanthanum with elements such as praseodymium and samarium and driven the temperature plenty going for them. They're abundant and carbon-free, and their prices are dropping. But they're part

Heller, Eric

118

Investigation into Nanostructured Lanthanum Halides and CeBr3 for Nuclear Radiation Detection  

SciTech Connect

Nanocomposites may enable the use of scintillator materials such as cerium-doped lanthanum fluoride (LaF3:Ce) and cerium bromide (CeBr3) without requiring the growth of large crystals [1]. Nanostructured detectors may allow us to engineer immensely sized detectors of flexible form factors that will have a broad energy range and an energy resolution sufficient to perform isotopic identification. Furthermore, nanocomposites are easy to prepare and very low in cost. It is much less costly to use nanocomposites rather than grow large whole crystals of scintillator materials; with nanocomposites fabricated on an industrial scale, costs are even less. Nanostructured radiation scintillator detectors may improve quantum efficiency and provide vastly improved detector form factors. Quantum efficiencies up to 60% have been seen in photoluminescence from silicon nanocrystals in a densely-packed ensemble [2]. We have fabricated nanoparticles with sizes <10 nm and characterized their nanocomposite radiation detector properties. This work investigates the properties of the nanostructured radiation scintillator in order to extend the gamma energy response on both low- and high-energy regimes by demonstrating the ability to detect low-energy x-rays and relatively high-energy activation prompt gamma rays simultaneously using nanostructured lanthanum bromide, lanthanum fluoride, or CeBr3. Preliminary results of this investigation are consistent with a significant response of these materials to nuclear radiation.

Guss, P. P., Guise, R., Mukhopadhyay, S., Yuan, D.

2011-07-06

119

Atomic Mass and Nuclear Binding Energy for Sm-171 (Samarium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Sm-171 (Samarium, atomic number Z = 62, mass number A = 171).

Sukhoruchkin, S. I.; Soroko, Z. N.

120

Atomic Mass and Nuclear Binding Energy for Sm-119 (Samarium)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Sm-119 (Samarium, atomic number Z = 62, mass number A = 119).

Sukhoruchkin, S. I.; Soroko, Z. N.

121

REACTIONS OF SAMARIUM IONS WITH ETHYLENEDIAMINETETRA ACETIC ACID  

Microsoft Academic Search

Specific electric conductivity and electromotive forces of isomolar ; serles and series with constant concentrations of samarium were measured in SmCl--; NaâHâY--HâO, SmClâNaâHY--HâO, and Sm(NOâ; )â--NaY--HâO systems. It was found that in acid media the solution ; forms an H (SmY) which dissociates into H\\/sup +\\/ and STASmY!⁻. In alkali ; media a complex anion STASmY!⁻ is formed. The constant

I. V. Tananaev; G. V. Shevchenko

1961-01-01

122

An experimental analysis of a doped lithium fluoride direct absorption solar receiver  

NASA Technical Reports Server (NTRS)

An experimental analysis of two key elements of a direct absorption solar receiver for use with Brayton solar dynamic systems was conducted. Experimental data are presented on LiF crystals doped with dysprosium, samarium, and cobalt fluorides. In addition, a simulation of the cavity/window environment was performed and a posttest inspection was conducted to evaluate chemical reactivity, transmissivity, and condensation rate.

Kesseli, James; Pollak, Tom; Lacy, Dovie

1988-01-01

123

Pure and doped lanthanum cobaltites obtained by combustion method  

Microsoft Academic Search

We report the synthesis of La1?xSrxCoO3 nanopowders by solution combustion method using metal nitrates and ?-alanine (alanine method) or urea (urea method) as fuel. The influence of metal nitrates\\/organic substance molar ratio and the type of fuel was investigated. The isolated complex precursors were characterized by atomic absorption spectroscopy (AAS), FT-IR spectra and DTA–TG analysis. The La1?xSrxCoO3 (x=0–0.3) powders were characterized

D. Berger; C. Matei; F. Papa; G. Voicu; V. Fruth

2007-01-01

124

Biosorption of lanthanum using Sargassum fluitans in batch system  

Microsoft Academic Search

Separation and purification of lanthanum from other rare-earth (RE) elements are highly complex processes comprising several steps of extraction using organic solvents or ion-exchange resins at high costs. In order to study the biosorption process as an alternative for conventional lanthanum recovery, this work investigated some basic aspects of lanthanum–Sargassum biomass interactions in batch equilibrium contact. The dynamics of biosorption,

Mauricio C Palmieri; Bohumil Volesky; Oswaldo Garcia

2002-01-01

125

Electronic structure of Lanthanum-carbon clusters  

Microsoft Academic Search

As the attachment of a metal change the molecular and electronic structure of carbon clusters, the electronic properties as ionization potentials (IP) and electron affinities (EA) for small Lanthanum-carbon clusters $LaC_n$ with $n$=1-6 have been investigated theoretically. They were studied by density-functional-theory (DFT) within LDA and considering Gradient corrections (GC) for the exchange-correlation potential (Becke-Perdew). The results for both quantities

A. Ayuela; G. Seifert; R. Schmidt

1997-01-01

126

Superconductivity in lanthanum cuprates: A layered-electron-gas model  

SciTech Connect

The nature of the superconducting state of lanthanum cuprate superconductor is discussed using strong-coupling theory, when electron-electron, electron-phonon, and electron-plasmon mechanisms are simultaneously present within a layered-electron-gas model. Treating the system as a two-component plasma, the effect of two-dimensional (2D) acoustic phonons as well as plasmons has been investigated. The approach is developed for one conducting copper oxide layer, which is an isolated free-electron layer and is well separated from insulating layers in a unit cell. A pair potential is constructed and the model parameters deduced are used to evaluate the transition temperature ({ital T}{sub {ital c}}) as a function of Ba and Sr doping. The approach is further applied to estimate the oxygen isotope coefficient {alpha} and the energy gap parameter {beta}. From these results it is argued that both 2D acoustic phonons and plasmons generated along the CuO{sub 2} layer play a significant role in copper oxide superconductors. In particular, 2D acoustic plasmons strongly influence {ital T}{sub {ital c}} and there is 60% enhancement over the phonon contribution to {ital T}{sub {ital c}}. The computed values of {ital T}{sub {ital c}}, {alpha}, and {beta} are consistent with the reported experimental data.

Varshney, D. [School of Physics, Devi Ahilya University, Indore 452001 (India)] [School of Physics, Devi Ahilya University, Indore 452001 (India); Singh, R.K. [School of Physics, Barkatullah University, Bhopal 462026 (India)] [School of Physics, Barkatullah University, Bhopal 462026 (India)

1995-09-01

127

Ambi-site substitution of Mn in lanthanum germanate apatites  

SciTech Connect

A neutron diffraction study at 4 K of the Mn doped lanthanum germanate apatite-type oxide ion conductor of nominal starting composition 'La{sub 9.5}Mn{sub 0.5}(GeO{sub 4}){sub 6}O{sub 2.75}' is reported. The structure was refined in space group P6{sub 3}/m, although high thermal displacement parameters were observed for the oxide ion sites (particularly O3, and O4). Reduced thermal displacement parameters were obtained by splitting the O3 site, and allowing the O4 oxygen to move off site, which may indicate local regions of lower symmetry within the structure. In addition, the data suggested ambi-site substitution of Mn, with it being present on both the Ge site and the La site. Assuming no change in La:Mn:Ge ratio, a composition of La{sub 9.18}Mn{sub 0.28}(GeO{sub 4}){sub 5.8}(MnO{sub 4}){sub 0.2}O{sub 2} was determined. As such there are nominally no interstitial oxide ions, but rather cation vacancies on the La site. Therefore, the high conductivity for this sample is most likely related to the introduction of Frenkel-type defects at higher temperature, as previously proposed for other apatite-type systems containing vacancies on the La site.

Kendrick, E. [Chemical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Knight, K.S. [ISIS Facility, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX (United Kingdom); Slater, P.R., E-mail: p.r.slater@bham.ac.uk [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

2009-08-05

128

Samarium-146 in the early solar system - Evidence from neodymiun in the Allende meteorite  

NASA Astrophysics Data System (ADS)

A carbon-chromite fraction from the Allende C3V chondrite shows strikingly large isotopic enrichments of neodymium-142 (0.47 percent) and neodymium-143 (36 percent). Both apparently formed by alpha decay of samarium-146 and samarium-147 (half-lives 1.03 x 10 to the 8th and 1.06 x 10 to the 11th years), but the isotopic enrichment was greatly magnified by recoil of residual nuclei into a carbon film surounding the samarium-bearing grains. These data provide an improved estimate of the original abundance of extinct samarium-146 in the early solar system, Sm-146/Sm-144 = (4.5 + or - 0.5) x 10 to the -3rd, higher than predicted by some models of p-process nucleosynthesis. It may be possible to use this isotopic pair as a chronometer of the early solar system.

Lugmair, G. W.; Shimamura, T.; Lewis, R. S.; Anders, E.

1983-12-01

129

Samarium-146 in the early solar system - Evidence from neodymiun in the Allende meteorite  

NASA Technical Reports Server (NTRS)

A carbon-chromite fraction from the Allende C3V chondrite shows strikingly large isotopic enrichments of neodymium-142 (0.47 percent) and neodymium-143 (36 percent). Both apparently formed by alpha decay of samarium-146 and samarium-147 (half-lives 1.03 x 10 to the 8th and 1.06 x 10 to the 11th years), but the isotopic enrichment was greatly magnified by recoil of residual nuclei into a carbon film surounding the samarium-bearing grains. These data provide an improved estimate of the original abundance of extinct samarium-146 in the early solar system, Sm-146/Sm-144 = (4.5 + or - 0.5) x 10 to the -3rd, higher than predicted by some models of p-process nucleosynthesis. It may be possible to use this isotopic pair as a chronometer of the early solar system.

Lugmair, G. W.; Shimamura, T.; Lewis, R. S.; Anders, E.

1983-01-01

130

Samarium-146 in the early solar system: evidence from neodymium in the allende meteorite.  

PubMed

A carbon-chromite fraction from the Allende C3V chondrite shows strikingly large isotopic enrichments of neodymium-142 (0.47 percent) and neodymium- 143 (36 percent). Both apparently formed by alpha decay of samarium-146 and samarium-147 (half-lives 1.03 x 10(8) and 1.06 x 10(11) years), but the isotopic enrichment was greatly magnified by recoil of residual nuclei into a carbon film surrounding the samarium-bearing grains. These data provide an improved estimate of the original abundance of extinct samarium-146 in the early solar system [(146)Sm/(144)Sm = (4.5 +/- 0.5) x 10(-3)], higher than predicted by some models of pprocess nucleosynthesis. It may be possible to use this isotopic pair as a chronometer of the early solar system. PMID:17776245

Lugmair, G W; Shimamura, T; Lewis, R S; Anders, E

1983-12-01

131

Self-activating and doped tantalate phosphors.  

SciTech Connect

An ideal red phosphor for blue LEDs is one of the biggest challenges for the solid-state lighting industry. The appropriate phosphor material should have good adsorption and emission properties, good thermal and chemical stability, minimal thermal quenching, high quantum yield, and is preferably inexpensive and easy to fabricate. Tantalates possess many of these criteria, and lithium lanthanum tantalate materials warrant thorough investigation. In this study, we investigated red luminescence of two lithium lanthanum tantalates via three mechanisms: (1) Eu-doping, (2) Mn-doping and (3) self-activation of the tantalum polyhedra. Of these three mechanisms, Mn-doping proved to be the most promising. These materials exhibit two very broad adsorption peaks; one in the UV and one in the blue region of the spectrum; both can be exploited in LED applications. Furthermore, Mn-doping can be accomplished in two ways; ion-exchange and direct solid-state synthesis. One of the two lithium lanthanum tantalate phases investigated proved to be a superior host for Mn-luminescence, suggesting the crystal chemistry of the host lattice is important.

Nyman, May Devan; Rohwer, Lauren Elizabeth Shea

2011-01-01

132

Low temperature synthesis of spherical lanthanum aluminate nanoparticles  

Microsoft Academic Search

Lanthanum aluminate powders could be prepared by a novel ultrasonic assisted combined gel synthesis from metal chloride solutions with ammonia destabilization. The decomposition and crystallization behavior of the gel was studied by DTA\\/TGA. The washed and powdered gel was calcined at different temperatures and the phase evolution was studies by X-ray diffractometry. Phase pure lanthanum aluminate was obtained for powders

S. K. Behera; P. K. Sahu; S. K. Pratihar; S. Bhattacharyya

2004-01-01

133

Lanthanum hexaboride (LaB/sub 6/) resistivity measurement  

SciTech Connect

In the development of high-power free-electron lasers, intense electron beams are required. Large area, directly heated lanthanum hexaboride cathodes have been proposed as the electron emitter. To aid in the design of the cathode, the resistivity of lanthanum hexaboride as a function of material density and temperature has been measured.

Williams, M.D.; Jackson, L.T.; Kippenhan, D.O.; Leung, K.N.; West, M.K.; Crawford, C.K.

1987-06-22

134

Preparation of high purity lanthanum compounds for use in fluoride optical fibers  

SciTech Connect

The preparation of ultra-pure lanthanum nitrate by co-precipitation is described. Preparation of high purity lanthanum carbonate from the pure nitrate is also described. Hydrofluorination of pure lanthanum carbonate produces high purity lanthanum fluoride used in the preparation of heavy metal fluoride glasses.

Ewing, K.J.; Buckner, L.; Jaganathan, J.; Ginther, R.; Aggarwal, I.D. (Naval Research Lab., Washington, DC (USA). Optical Sciences Div.)

1989-02-01

135

Co-doped Barium Phosphate Glass  

NASA Astrophysics Data System (ADS)

Co-doping of a P2O5:BaO glass matrix with divalent tin and trivalent samarium ions has been realized by the melt-quenching technique with the purpose of investigating the material's luminescent properties. Photoluminescence excitation spectra obtained by monitoring Sm3+ 4G5/2 emission showed a broad excitation band around 290 nm (absent in a Sm3+-doped reference), typical of donor/acceptor energy transfer. Under such excitation, the material exhibits a reddish-white emission. Time-resolved spectra recorded under the 290-nm excitation (non-resonant with Sm3+ excitation peaks) exposed a broad blue-white band characteristic of twofold-coordinated Sn centers and orange-red emission bands of Sm3+ ions, which appeared well separated in time in accord with their emission decay dynamics. Consequently, the data indicate that light absorption occurs at Sn centers (donors) followed by energy transfer to samarium ions (acceptors) which results in populating the 4G5/2 emitting state in Sm3+. Energy transfer pathways likely resulting in the sensitization of Sm3+ photoluminescence are discussed. Results are put into context in terms of the potential of SnO and rare-earth co-doped barium phosphate glasses for use in white light-emitting devices.

Jiménez, J. A.

2014-09-01

136

Intracellular localization of samarium in the lactating mammary gland cells: ultrastructural and microanalytical study.  

PubMed

The frequent use of some rare earths in the medical and industrial domains make us worry about their intracellular behavior into the body. Reason for which we have investigated the subcellular localization of one of these elements, the samarium, in the mammary gland of lactating female wistar rats using two very sensitive methods of observation and microanalysis, the transmission electron microscopy and the secondary ion mass spectrometry. The ultrastructural study showed the presence of electron dense deposits in the lactating mammary glandular epithelial cell lysosomes of the samarium-treated rats, but no loaded lysosomes were observed in those of control rats. The microanalytical study allowed both the identification of the chemical species present in those deposits as samarium isotopes ((152) Sm(+)) and the cartography of its distribution. Our results confirm the previous ones showing that lysosomes of the glandular epithelial cells are the site of the intracellular concentration of foreign elements such as gallium. The intralysosomal deposits observed in the mammary glandular cells of the samarium-treated rats are similar in their form and density to those observed with the same element in other varieties of cells, such as liver, bone marrow, and spleen cells. Our ultrastructural and microanalytical results and those obtained in previous studies allow deducing that the intralysosomal deposits are very probably composed of an insoluble samarium phosphate salt. PMID:22021164

Ahlem, Ayadi; Samira, Maghraoui; Jean-Nicolas, Audinot; Mohamed-Habib, Jaafoura; Henri-Noël, Migeon; Ali, El Hili; Leila, Tekaya

2012-04-01

137

A new nanosensor composed of laminated samarium borate and immobilized laccase for phenol determination  

PubMed Central

A new nanosensor composed of laminated samarium borate and immobilized laccase was developed for phenol determination. The laminated samarium borate was synthesized by a mild solid-state-hydrothermal (S-S-H) method without any surfactant or Template. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used to characterize the samples. The morphology of the as-prepared materials was characterized by SEM, which shows that laminated samarium borate are uniform nanosheets with a layer-by-layer self-assembled single-crystal structure. These laminated samarium borate have typical diameters of 3?~?5 ?m and the thickness of each layer is in the range of 10?~?80 nm. And then, these SmBO3 multilayers were used to immobilize the laccase. The proposed nanosensor composed of laminated samarium borate and immobilized laccase was successfully developed for phenol determination. Cyclic voltammetry were used to study the nanosensor. The proposed nanosensor displayed high sensitivity toward phenolic compounds. The linearity of the nanosensor for the detection of hydroquinone was obtained from 1 to 50 ?M with a detection limit of 3?×?10-7 M (based on the S/N?=?3). PMID:24528570

2014-01-01

138

Samarium (III) Selective Membrane Sensor Based on Tin (IV) Boratophosphate  

PubMed Central

A number of Sm (III) selective membranes of varying compositions using tin (IV) boratophosphate as electroactive material were prepared. Polyvinyl chloride, polystyrene and epoxy resin were used as binding materials. Membrane having composition of 40% exchanger and 60% epoxy resin exhibited best performance. This membrane worked well over a wide concentration range of 1×10-5M to 1×10-1 M of samarium ions with a Super-Nernstian slope of 40 mV/decade. It has a fast response time of less than 10 seconds and can be used for at least six months without any considerable divergence in potentials. The proposed sensor revealed good selectivities with respect to alkali, alkaline earth, some transition and rare earth metal ions and can be used in the pH range of 4.0-10.0. It was used as an indicator electrode in the potentiometric titration of Sm (III) ions against EDTA. Effect of internal solution was studied and the electrode was successfully used in non-aqueous media, too.

Mittal, Susheel K.; Sharma, Harish Kumar; Kumar, Ashok S. K.

2004-01-01

139

Growth and spectroscopic properties of samarium oxalate single crystals  

NASA Astrophysics Data System (ADS)

Single crystals of samarium oxalate decahydrate were synthesized using single diffusion gel technique and the conditions influencing the size, shape and quality were optimized. Highly transparent crystals of size 3×2×1 mm3 with a well defined hexagonal morphology were grown during a time period of two weeks. X ray powder diffraction analysis revealed that the grown crystals crystallize in the monoclinic system with space group P21/c and the proposed chemical formula and linkage of water molecules were confirmed using thermogravimetric analysis. The various functional groups of the oxalate ligand and the water of crystallization were identified by Fourier transform infrared spectroscopy. Spectroscopic investigations such as electric dipole transition probability, magnetic dipole transition probability and branching ratios of all possible transitions from 4G5/2 level of Sm3+ ions were estimated from the absorption spectra using JO theory. The spectroscopic analysis suggested that the crystal has a strong and efficient orange red emission. This is confirmed from the photoluminescence spectrum with a wavelength peak at 595 nm and hence this promising emission can be effectively used for optical amplification.

Vimal, G.; Mani, Kamal P.; Jose, Gijo; Biju, P. R.; Joseph, Cyriac; Unnikrishnan, N. V.; Ittyachen, M. A.

2014-10-01

140

Calciphylaxis responsive to lanthanum carbonate (FOSRENOL) therapy.  

PubMed

Calciphylaxis is a rare and debilitating vasculopathy predominantly seen in patients with renal failure. The proposed mechanism of injury is active vascular calcification with associated elevated parathyroid hormone, hypercalcemia, or hyperphosphatemia. With improved pharmacologic agents including non-calcium containing phosphate binders, vitamin D analogues, calcimimetics, and bisphosphonates, targeted therapy on the mineralization process has been tried with varied success. We report a case of biopsy-proven calciphylaxis in a patient with acute kidney injury requiring dialysis that had persistently elevated calcium-phosphorus product refractory to treatment. The patient, however, responded rapidly to the initiation of lanthanum carbonate therapy and modified dialysis. This is the first known case reported in the literature utilizing this new non-calcium-based phosphate binder in the setting of calciphylaxis. PMID:19180873

Chan, Micah R; Yevzlin, Alexander S; Hinshaw, Molly; Jaffery, Jonathan B

2008-11-01

141

Diminiode thermionic energy conversion with lanthanum-hexaboride electrodes  

NASA Technical Reports Server (NTRS)

This paper presents thermionic-conversion data obtained from a variable-gap cesium diminiode with a hot-pressed, sintered lanthanum-hexaboride emitter and an arc-melted lanthanum-hexaboride collector. Performance curves cover a range of temperatures: emitter 1500 to 1700 K, collector 750 to 1000 K, and cesium reservoir 370 to 510 K. Calculated values of emitter and collector work functions and barrier index are also given.

Kroeger, E. W.; Bair, V. L.; Morris, J. F.

1978-01-01

142

Lanthanum Oxide Effects on the Structure of Calcium Phosphate Glasses  

Microsoft Academic Search

Calcium phosphate glasses, in which part of calcium oxide was replaced by lanthanum oxide, were prepared by using the conventional melt quench method. The structures of xLa2O3 · (50-x)CaO · 50P2O5 (x = 0, 1, 3, 6, 12 mol%) samples were investigated by X-ray diffraction (XRD), Raman spectrum, Fourier transform infrared spectrum (FTIR), and differential scanning calorimetry (DSC). The results show that lanthanum oxide acts as network

Xiaofeng Liang; Guangfu Yin; Shiyuan Yang; Yuanming Lai; Junxia Wang

2011-01-01

143

Lanthanum zirconate nanofibers with high sintering-resistance  

Microsoft Academic Search

The PVP\\/lanthanum nitrate\\/zirconium oxychloride (PVP-precursor) nanofiber was prepared by electrospinning technique. Lanthanum zirconate (La2Zr2O7, LZ) in the nanofiber is formed after calcination at 800°C and the nanofiber with pyrochlore structure and a diameter of 100–500nm can be obtained by calcination of the above precursor fiber at 1000°C for 12h. The surface of the fiber is rough but the continuous microstructure

J. Y. Li; H. Dai; Q. Li; X. H. Zhong; X. F. Ma; J. Meng; X. Q. Cao

2006-01-01

144

Diminiode thermionic energy conversion with lanthanum-hexaboride electrodes  

NASA Technical Reports Server (NTRS)

Thermionic conversion data obtained from a variable gap cesium diminiode with a hot pressed, sintered lanthanum hexaboride emitter and an arc melted lanthanum hexaboride collector are presented. Performance curves cover a range of temperatures: emitter 1500 to 1700 K, collector 750 to 1000 K, and cesium reservoir 370 to 510 K. Calculated values of emitter and collector work functions and barrier index are also given.

Kroeger, E. W.; Bair, V. L.; Morris, J. F.

1978-01-01

145

Lutetium-doped EuO films grown by molecular-beam epitaxy  

NASA Astrophysics Data System (ADS)

The effect of lutetium doping on the structural, electronic, and magnetic properties of epitaxial EuO thin films grown by reactive molecular-beam epitaxy is experimentally investigated. The behavior of Lu-doped EuO is contrasted with doping by lanthanum and gadolinium. All three dopants are found to behave similarly despite differences in electronic configuration and ionic size. Andreev reflection measurements on Lu-doped EuO reveal a spin-polarization of 96% in the conduction band, despite non-magnetic carriers introduced by 5% lutetium doping.

Melville, A.; Mairoser, T.; Schmehl, A.; Shai, D. E.; Monkman, E. J.; Harter, J. W.; Heeg, T.; Holländer, B.; Schubert, J.; Shen, K. M.; Mannhart, J.; Schlom, D. G.

2012-05-01

146

Lutetium-doped EuO films grown by molecular-beam epitaxy  

SciTech Connect

The effect of lutetium doping on the structural, electronic, and magnetic properties of epitaxial EuO thin films grown by reactive molecular-beam epitaxy is experimentally investigated. The behavior of Lu-doped EuO is contrasted with doping by lanthanum and gadolinium. All three dopants are found to behave similarly despite differences in electronic configuration and ionic size. Andreev reflection measurements on Lu-doped EuO reveal a spin-polarization of 96% in the conduction band, despite non-magnetic carriers introduced by 5% lutetium doping.

Melville, A.; Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Mairoser, T.; Schmehl, A. [Zentrum fuer elektronische Korrelationen und Magnetismus, Universitaet Augsburg, Universitaetsstrasse 1, D-86159 Augsburg (Germany); Shai, D. E.; Monkman, E. J.; Harter, J. W. [Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Hollaender, B.; Schubert, J. [Peter Gruenberg Institute, PGI 9-IT, JARA-FIT, Research Centre Juelich, D-52425 Juelich (Germany); Shen, K. M. [Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States); Mannhart, J. [Max Planck Institute for Solid State Research, D-70569 Stuttgart (Germany); Schlom, D. G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

2012-05-28

147

IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 17, NO. 2, FEBRUARY 2005 297 La-Codoped Bismuth-Based Erbium-Doped Fiber  

E-print Network

IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 17, NO. 2, FEBRUARY 2005 297 La-Codoped Bismuth lasers using 84.6-cm-long lanthanum-codoped bismuth-based erbium doped fiber and a narrow-band tunable)-codoped bismuth-based erbium-doped fiber (Bi-EDF), laser tuning, microelectromechanical system (MEMS) filter. I

Wai, Ping-kong Alexander

148

Thickness of the near-interface regions and central bulk ohmic resistivity in lead lanthanum zirconate titanate ferroelectric thin films  

NASA Astrophysics Data System (ADS)

We have developed a method to separate the low-resistive near-interface regions (NIRs) from the high-resistive central bulk region (CBR) in a ferroelectric thin film. The NIR thickness and the CBR resistivity can thus be accurately determined. Using lanthanum-doped lead zirconate titanate films as an example, we show that the total thickness of the NIRs depends only on the electrode materials in use (Ir and Pt), while the CBR resistivity depends only on the impurity doping levels (La=1.5% and 3%). The fact that the NIR is much narrower when Pt electrodes are used instead of Ir, and that the NIR resistivity is always considerably lower than the central bulk, suggest that the NIRs is probably originated from material nonstoichiometry/defects rather than the band bending at metal/insulator interfaces.

Chu, D. P.; Zhang, Z. G.; Migliorato, P.; McGregor, B. M.; Ohashi, K.; Hasegawa, K.; Shimoda, T.

2002-12-01

149

ppt level detection of samarium(III) with a coated graphite sensor based on an antibiotic.  

PubMed

N-[2-[4-[[[(Cyclohexylamino)carbonyl]amino]sulfonyl]phenyl]ethyl]-5-methyl pyrazine carboxamide (glipizid) was explored as an electro-active material for preparing a polymeric membrane-based sensor selective to samarium ions. The membrane incorporated 30% poly(vinyl chloride) (PVC), 53% benzyl acetate (BA), 11% glipizid and 6% sodium tetraphenyl borate. When coated on the surface of a graphite electrode, it exhibits Nernstian responses in the concentration range of 1.0 x 10(-5) to 1.0 x 10(-10) M, with a detection limit of 8.0 x 10(-11)M samarium. The electrode shows high selectivity towards samarium over several cations (alkali, alkaline earth, transition and heavy metal ions), and specially lanthanide ions. The proposed sensor has a very short response time (< 15 s), and can be used in a wide pH range for at least ten weeks. It was used as an indicator electrode in potentiometric titration of Sm(III) ions with an EDTA solution, and for determination of samarium in binary and ternary mixtures. PMID:15293392

Ganjali, Mohammad Reza; Rezapour, Morteza; Pourjavid, Mohammad Reza; Haghgoo, Soheila

2004-07-01

150

Measurement of lifetimes and tensor polarizabilities of odd parity states of atomic samarium  

E-print Network

1 Measurement of lifetimes and tensor polarizabilities of odd parity states of atomic samarium S for Beam Physics, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 A systematic measurement. The lifetimes were measured by detecting time- resolved fluorescence following pulsed laser excitation of atoms

Pines, Alexander

151

Investigation of the protonic conduction in Sm doped BaCeO 3  

Microsoft Academic Search

In the present work the structural and electrical properties of samarium-doped barium cerate perovskites of BaCe1?xSmxO3?? formula (with x=0–0.2), prepared by following the solid state reaction method, are investigated. The crystal structure and microstructure of the samples is determined by employing the techniques of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). According to the XRD analysis at 0?x?0.2 the

E. Gorbova; V. Maragou; D. Medvedev; A. Demin; P. Tsiakaras

2008-01-01

152

Interaction of lanthanum chloride with human erythrocyte membrane in relation to acetylcholinesterase activity  

Microsoft Academic Search

Lanthanum chloride (1 mM) inhibits the activity of acetylcholinesterasein vitro in the human erythrocyte membrane. Lineweaver-Burk analysis indicates that lanthanum chloride induced inhibition of acetylcholinesterase\\u000a activity is competitive in nature. The Arrhenius plot shows that the transition temperature of erythrocyte membrane-bound\\u000a acetylcholinesterase is significantly reduced in the presence of lanthanum chloride. These results suggest that lanthanum\\u000a chloride increases the fluidity

Sunil Mukhopadhyay; Sila Mukhopadhyay; Dilip K. Bhattacharyya; Gora Chand Chatterjee

1988-01-01

153

Polyhedral arrangements in lanthanum aluminoborate glasses  

SciTech Connect

The authors have used magic-angle spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy to examine the polyhedral arrangements in ternary lanthanum aluminoborate glasses. They have characterized two glass-forming series: xAl{sub 2}O{sub 3}{center_dot}(1{minus}x)LaB{sub 3}O{sub 6} and 0.25 La{sub 2}O{sub 3}{center_dot}yAl{sub 2}O{sub 3}{center_dot}(1{minus}y)-B{sub 2}O{sub 3}. {sup 11}B MAS NMR reveals a decrease in the fraction of four-coordinated boron atoms with increases in the Al{sub 2}O{sub 3} content in both series. {sup 27}Al MAS NMR has detected four-, five- and six-coordinated aluminum atoms in complex aluminoborate networks similar to those reported elsewhere for alkaline-earth aluminoborate glasses. Raman spectroscopy reveals a variety of borate and aluminoborate moieties, including isolated groups as well as methaborate chains and rings. These results indicate that the La{sup 3+} ion acts as a modifier to the aluminoborate network.

Brow, R.K.; Tallant, D.R. [Sandia National Labs., Albuquerque, NM (United States); Turner, G.L. [Spectral Data Services, Champaign, IL (United States)

1997-05-01

154

Water Research 39 (2005) 22292236 Effect of counterions on lanthanum biosorption  

E-print Network

Water Research 39 (2005) 2229­2236 Effect of counterions on lanthanum biosorption by Sargassum on the biosorption of La3+ (Lanthanum) using Sargassum polycystum Ca-loaded biomass was studied in this work: Biosorption; Anions; Lanthanum; Sargassum; Speciation 1. Introduction Biosorption is a process where metal

Volesky, Bohumil

155

Electro-optical polycrystalline barium lanthanum titanium niobate  

SciTech Connect

This patent describes a transparent electro-optic article. It comprises: of a barium lanthanum titanium niobate wherein substantially all grains are of a grain size between about 2 and about 20 micron, the article has a pore volume of less than about 1 percent, and the article has a grain size of between about 2 and about 20 microns. This patent also describes a method of forming transparent electro-optical barium lanthanum titanium niobate. It comprises: providing particles of barium carbonate, lanthanum oxide, titanium oxide, and niobium oxide, calcining the particles, sintering the calcined particles at a temperature of between about 1200{degrees} C and 1300{degrees} C. and a vacuum of between about 10{sup {minus}3} and 10{sup {minus}4} torr while under pressure to form a sintered mass, cooling the sintered mass, slicing the mass to form wafers, heating the wafers in an oxidizing atmosphere.

Mehrotra, A.K.

1991-02-19

156

Effects of doping of metal cations on morphology, activity, and visible light response of photocatalysts  

Microsoft Academic Search

Effects of doping of metal cations into wide band gap semiconductor photocatalysts on morphology, visible light response, and photocatalytic performance were studied. Doping of lanthanide and alkaline earth ions improved activity of a NaTaO3 photocatalyst for water splitting. Lanthanum was the most effective dopant. The NaTaO3:La with a NiO cocatalyst gave 56% of a quantum yield at 270nm. This remarkable

Akihiko Kudo; Ryo Niishiro; Akihide Iwase; Hideki Kato

2007-01-01

157

Computational removal of lanthanum–cerium bromide self-activity  

Microsoft Academic Search

It has been reported that detectors made of lanthanum–cerium halides, such as LaBr3(Ce) and CeBr3 have superior energy resolution for gamma-radiation detection compared to that offered by conventional sodium iodide [NaI(T1)] detectors. However, it has also been observed that the lanthanum–cerium halides contain certain amount of self-activity caused by the radioactive isotope 138La. Additionally, LaBr3(Ce) and CeBr3 crystals have also

Ding Yuan; Paul Guss; Sanjoy Mukhopadhyay

2011-01-01

158

Tuning the architecture and properties of microstructured yttrium tungstate oxide hydroxide and lanthanum tungstate.  

PubMed

In this paper, various microstructures of yttrium and lanthanum tungstates were synthesized under hydrothermal conditions, at pH 5, in a ligand-free environment, and in the presence of a dioctyl sodium sulfosuccinate (DSS) surfactant. It was observed that the shape of the nanobuilding blocks, and therefore the architecture of the microstructures, could be tuned by controlling the reaction conditions, such as the source of the rare earth, the amount of a surfactant and the reaction time. X-ray powder diffraction (XRD), elemental analysis, scanning electron microscopy (SEM), and N2 adsorption were employed to characterize the obtained products. The photoluminescent properties of Eu(3+) and Dy(3+) doped tungstate materials were investigated. Luminescence measurements showed an efficient charge transfer from the WO4(2-) groups to Eu(3+) and Dy(3+) ions. It was found that under UV excitation the Dy(3+) doped Y(WO3)2(OH)3 and La2(WO4)3 precursors exhibit white emission. PMID:23426044

Kaczmarek, Anna M; Liu, Ying-Ya; Van der Voort, Pascal; Van Deun, Rik

2013-04-21

159

Adsorption and desorption of samarium atoms on the surface of pure iridium and iridium covered with a graphite monolayer  

NASA Astrophysics Data System (ADS)

Methods of thermionic emission and thermodesorption spectroscopy (TDS) have been used to study the adsorption and condensation of samarium on the surface of pure iridium and iridium covered with a graphite monolayer (valence-saturated neutral substrate) Ir(111)-C. It is shown that at temperatures of 700 < T a < 1200 K the work function ? decreases monotonically from 5.8 to 2.7 eV and during the subsequent deposition of samarium grows slowly to 2.9 eV. It has been found that in all TDS peaks there were observed several phases of samarium. The deposition of samarium onto an Ir-C surface at 700 < T < 1700 K led to a very weak change in the thermionic current in comparison with pure iridium. At temperatures above ˜700 K, samarium is not condensed on the surface of Ir-C, but it is condensed at lower temperatures. By the method of temperature modulation, the heat of samarium desorption was determined to be E ˜ 1.9 eV upon the desorption from an Ir-C surface (at a small coverage) and ˜6 eV upon the desorption from pure Ir.

Orudzhov, A. K.; Dashdemirov, A. O.

2009-01-01

160

Effect of seeding on the formation of lanthanum hexaaluminates synthesized through advanced sol gel process  

NASA Astrophysics Data System (ADS)

Advanced sol gel processing was used to synthesize high purity lanthanum hexaaluminate powders. The effect of seeding on the formation of lanthanum hexaaluminate was also studied by seeding the gel. Dry gel was calcined at various temperatures starting from 1100 °C to 1600 °C for 2 h to study the phase evolution. The combine effects of advanced sol gel processing and the presence of seeds promoted the formation of lanthanum hexaaluminate phase at lower temperature than the conventional routes. Lanthanum hexaaluminate phase was detected at 1201 °C and 1300 °C in seeded and un-seeded gels, respectively. The presence of seed decreases the temperature of formation of lanthanum hexaaluminate by 99 °C. Single phase lanthanum hexaaluminate was formed at 1600 °C in seeded gel whereas trace of lanthanum monoaluminate phase still present in un-seeded gel even at 1600 °C.

Jana, P.; Jayan, P. S.; Mandal, S.; Biswas, K.

2014-12-01

161

Scintillators with potential to supersede lanthanum bromide  

SciTech Connect

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.

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

162

Growth and characterization of rare earths doped triglycine sulfate crystals  

NASA Astrophysics Data System (ADS)

Ferroelectric triglycine sulfate (TGS) single crystals have been grown by a temperature-lowering technique from the aqueous solution by doping with samarium sulfate, ytterbium sulfate and terbium sulfate in the ferroelectric phase. The effects of these different dopants on the morphology, growth and various properties such as dielectric, pyroelectric and piezoelectric of doped TGS crystals have been investigated. The decrease in values of dielectric constant and pyroelectric coefficient is observed while the dielectric loss has increased. Using these parameters, figure-of-merits for their use in infrared sensors have also been reported and compared with pure TGS crystal. The Vickers's hardness of doped TGS crystals along (0 1 0) crystallographic face has increased.

Batra, A. K.; Guggilla, Padmaja; Cunningham, Dewanna; Aggarwal, M. D.; Lal, R. B.

2006-01-01

163

Anthropogenic dissolved and colloid/nanoparticle-bound samarium, lanthanum and gadolinium in the Rhine River and the impending destruction of the natural rare earth element distribution in rivers  

NASA Astrophysics Data System (ADS)

The strong increase in the consumption of rare earth elements (REE) in high-tech products and processes is accompanied by increasing amounts of REE released into the environment. Following the first report of Gd contamination of the hydrosphere in 1996, anthropogenic Gd originating from contrast agents has now been reported worldwide from river and estuarine waters, coastal seawater, groundwater and tap water. Recently, microcontamination with La, that is derived from a point source where catalysts for petroleum refining are produced, has been detected in the Rhine River in Germany and the Netherlands. Here we report the occurrence of yet another REE microcontamination of river water: in addition to anthropogenic Gd and La, the Rhine River now also shows significant amounts of anthropogenic Sm. The anthropogenic Sm, which enters the Rhine River north of Worms, Germany, with the same industrial wastewater that carries the anthropogenic La, can be traced through the Middle and Lower Rhine to the Netherlands. At Leverkusen, Germany, some 250 km downstream from the point source at Worms, anthropogenic Sm still contributes up to 87% of the total dissolved Sm concentration of the Rhine River. Results from ultrafiltration suggest that while the anthropogenic Gd is not particle-reactive and hence exclusively present in the truly dissolved REE pool (<10 kDa), the anthropogenic La and Sm are also present in the colloidal/nanoparticulate REE pool (between 10 kDa and 0.2 ?m). Though difficult to quantify, our data suggest that the Rhine River may carry up to 5700 kg of anthropogenic La, up to 584 kg of anthropogenic Sm, and up to 730 kg of anthropogenic Gd per year toward the North Sea. There exist no regulatory limits for dissolved REE in natural waters, but total REE and Y (?REY) concentrations of up to 0.14 mg/kg in the plume downstream of and 52.2 mg/kg at the head of an effluent pipe at Rhine-km 447.3 at Worms get close to and well-above, respectively, the levels at which ecotoxicological effects have been documented. Because of the increasing use of REE and other formerly "exotic" trace elements in high-tech applications, these critical metals have now become emerging contaminants that should be monitored, and it appears that studies of their biogeochemical behavior in natural freshwaters might soon no longer be possible.

Kulaks?z, Serkan; Bau, Michael

2013-01-01

164

Thermo-elastic and ductile properties of Samarium chalcogenides at high pressures  

NASA Astrophysics Data System (ADS)

Samarium chalcogenides crystallize in Fm3m space group at ambient condition and transform to Pm3m space group under high pressure. We have investigated the structural and elastic properties of Samarium chalcogenides using modified charge-transfer potential model. This model incorporates long-range Coulomb effects and charge-transfer (Coulomb screening due to f-electrons of Sm) effect modified by covalency and short-range repulsive interaction extended up to next-nearest neighbours. This model is capable of explaining the Cauchy-discrepancy. We have computed elastic constants, Poisson's ratio and its volume derivative, the ratio of volume thermal expansion coefficient to specific heat, Debye temperature and Grüneisen parameter.

Baraiya, A. K.; Raypuria, G. S.; Gupta, D. C.

2013-02-01

165

Discovery of cesium, lanthanum, praseodymium and promethium isotopes  

SciTech Connect

Currently, forty-one cesium, thirty-five lanthanum, thirty-two praseodymium, and thirty-one promethium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

May, E.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2012-09-15

166

Discovery of Cesium, Lanthanum, Praseodymium and Promethium Isotopes  

E-print Network

Currently, forty-one cesium, thirty-five lanthanum, thirty-two praseodymium, and thirty-one promethium, isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

E. May; M. Thoennessen

2011-09-08

167

Ab initio energetics of lanthanum substitution in ferroelectric bismuth titanate.  

PubMed

Using first principles calculations and atomistic thermodynamics the bulk and defect properties of orthorhombic bismuth titanate (Bi?Ti?O??) and bismuth lanthanum titanate (Bi?.??La?.??Ti?O??) have been investigated. Heats of formation, valid chemical conditions for synthesis, lanthanum substitution energies and oxygen and bismuth vacancy formation energies have been computed. The study improves our understanding of how native point defects and substitutional impurities influence the ferroelectric properties of these layered perovskite materials. It is found that lanthanum incorporation could occur on either of the two distinct bismuth sites in the structure and that the effect of substitution is to increase the formation energy of nearby native oxygen vacancies. The results provide direct atomistic evidence over a range of chemical conditions supporting the suggestion that lanthanum incorporation reduces the oxygen vacancy concentration. Oxygen vacancies contribute to ferroelectric fatigue by interacting strongly with domain walls, and therefore a decrease in their concentration is beneficial. The conditions that favor the greatest reduction in oxygen vacancy concentration are described. PMID:21460424

Shah, S H; Bristowe, P D

2011-04-20

168

Structural Characterization of Methanol Substituted Lanthanum Halides  

PubMed Central

The first study into the alcohol solvation of lanthanum halide [LaX3] derivatives as a means to lower the processing temperature for the production of the LaBr3 scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(µ-Br)(H2O)7](Br)2}2 (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H2O)7(MeOH)2](Br)3 (2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH2, crystals of [Ca(MeOH)6](Br)2 (3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr2.75•5.25(MeOH)]+0.25 [LaBr3.25•4.75(MeOH)]?0.25} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr3 in MeOH forming the 8-coordinated [LaBr3(MeOH)5] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX3 derivatives were isolated as [(MeOH)4(Cl)2La(µ-Cl)]2 (6) and [La(MeOH)9](I)3•MeOH (7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR (139La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4 – 6 were slightly higher in comparison to their hydrated counterparts. PMID:20514349

Boyle, Timothy J.; Ottley, Leigh Anna M.; Alam, Todd M.; Rodriguez, Mark A.; Yang, Pin; Mcintyre, Sarah K.

2010-01-01

169

A simplified method of manufacture of sintered samarium cobalt permanent magnets  

Microsoft Academic Search

1.A study was made of a simplified method of manufacture of sintered samarium-cobalt permanent magnets based on the use of “overmilled” starting SmCo5 powders.2.It is shown that the key critical parameter in the simplified process is the total amount of the rare-earth component in the starting charge.3.The process investigated ensures a reliable reproduction of magnetic characteristics of sintered SmCo5 permanent

V. D. Turov; E. S. Lobyntsev; A. V. Starkov

1979-01-01

170

Thermal behaviour of gel-grown pure and mixed rare earth tartrates of yttrium and samarium  

Microsoft Academic Search

Thermal behaviour of gel-grown pure and mixed rare earth tartrates of yttrium and samarium is investigated using thermogravimetric\\u000a analysis (TGA) and differential scanning calorimetry (DSC). The thermal behaviour suggests that the materials are unstable\\u000a at lower energies and pass through various stages of decomposition, decomposing to respective rare earth oxides which remain\\u000a stable on further heating. It is estimated that

Anima Jain; Sushma Bhat; Sanjay Pandita; M L Kaul; P N Kotru

1997-01-01

171

Atomic emission determination of samarium, europium, ytterbium, and lutetium in silicate rocks  

SciTech Connect

A procedure is discussed that has been developed for the atomic emission determination of samarium, europium, ytterbium and lutetium in silicate rocks, using a cooled hollow cathode as the source of spectrum excitation. By using an isotope dilution procedure, the relative standard deviation can be reduced to 0.007 for a range of determined contents of the elements from n ha 10/sup -4/ to n ha 10/sup -3/% by weight.

Drobyshev, A.I.; Turkin, Yu.I.; Yakimova, N.M.

1986-06-01

172

Electronic configuration of samarium sulphide and related compounds: Mössbauer-effect measurements and a model  

Microsoft Academic Search

149Sm Mössbauer spectra have been measured at room temperature for SmS under applied pressures P=0-11 kbar and for Sm1-xYxS, 0<=x<=0.34. There is a sharp increase in isomer shift at P=6 kbar and x=0.15, respectively, accompanying the transformation from the black to the gold phase, but there is no corresponding increase in linewidth. The samarium configuration, assumed to be a mixture

J. M. D. Coey; S. K. Ghatak; M. Avignon; F. Holtzberg

1976-01-01

173

Topological surface state in the Kondo insulator samarium hexaboride  

NASA Astrophysics Data System (ADS)

Topological invariants of electron wavefunctions in condensed matter reveal many intriguing phenomena. A notable example is provided by topological insulators, which are characterized by an insulating bulk coexisting with a metallic boundary state. Although there has been intense interest in Bi-based topological insulators, their behaviour is complicated by the presence of a considerable residual bulk conductivity. Theories predict that the Kondo insulator system SmB6, which is known to undergo a transition from a Kondo lattice metal to a small-gap insulator state with decreasing temperature, could be a topological insulator. Although the insulating bulk and metallic surface separation has been demonstrated in recent transport measurements, these have not demonstrated the topologically protected nature of the metallic surface state. Here we report thickness-dependent transport measurements on doped SmB6, and show that magnetic and non-magnetic doping results in contrasting behaviour that supports the conclusion that SmB6 shows virtually no residual bulk conductivity.

Kim, D. J.; Xia, J.; Fisk, Z.

2014-05-01

174

Combustion synthesis and photoluminescence of Tb3+ doped LaAlO3 nanophosphors  

NASA Astrophysics Data System (ADS)

Terbium doped lanthanum aluminate (LaAlO3) nanophosphors were successfully synthesized by a combustion process using concentrated solution of lanthanum nitrates and aluminate as oxidiser, and glycine acid as fuel. The powders were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence spectroscopy. Pure LaAlO3 phase was obtained at 800 °C heated for 4 h, without formation of any intermediate phase, with an average crystal size, as determined by TEM, of 60 nm. Intense green emission is reported at 542 nm, from the 5D level, which intensity depends on Tb concentration.

Dhahri, A.; Horchani-Naifer, K.; Benedetti, A.; Enrichi, F.; Férid, M.; Riello, P.

2013-04-01

175

Tissue uptake and intracellular distribution of 140-lanthanum after oral intake by the rat  

SciTech Connect

The ability of lanthanum to stabilize hydroxyapatite against acid dissolution is well known. It is possible to use lanthanum to experimentally alter hard tissues in vivo and in vitro. It was, therefore, of interest to determine the tissue distribution of lanthanum following oral ingestion of a LaCl/sub 3/ solution. Oral intake of 140-lanthanum (as LaCl/sub 3/ in drinking water) in adult rats over a 3-d period was voluntary and amounted to 0.27 mmol LaCl/sub 3/ per animal per day. The teeth sowed increases in 140-lanthanum uptake with time. Distribution of 140-lanthanum within the incisors of animals drinking the LaCl/sub 3/ solution showed that the highest specific activity of 140-lanthanum was associated with the outer layer of the tooth (that portion exposed to the oral environment). The soft tissues, such as lung, kidney, and liver, maintained a constant 140-lanthanum concentration after the first day of intake. The intracellular distribution of 140-lanthanum was measured in liver, with the soluble fraction showing the highest content. No histological changes were observed in the rat tissues after 3 d of oral intake (0.27 mmol/d) of lanthanum.

Rabinowitz, J.L.; Fernandez-Gavarron, F.; Brand, J.G.

1988-01-01

176

Adverse Events in the Long-Term Follow-Up of Patients Treated With Samarium Sm 153 Lexidronam for Osseous Metastases  

SciTech Connect

Purpose: To investigate adverse events after samarium Sm 153 lexidronam and the effect of pre- and post-samarium Sm 153 lexidronam external beam radiation therapy (EBRT) and/or chemotherapy on myelosuppression in patients who received samarium Sm 153 lexidronam for osseous metastases. Methods and Materials: We performed a single-institution retrospective review of 139 patients treated with samarium Sm 153 lexidronam between November 1997 and February 2008. New-onset adverse events after samarium Sm 153 lexidronam were reported. The effect of samarium Sm 153 lexidronam on platelet and peripheral white blood cell counts and the duration of myelosuppression after samarium Sm 153 lexidronam plus EBRT and/or chemotherapy were calculated. Differences in the prevalence of adverse events among patients with varying treatment histories were evaluated with the Pearson chi-square test. Results: Hematologic follow-up was available for 103 patients. Chemotherapy and/or EBRT had no effect on the magnitude or duration of myelosuppression. The most common nonhematologic adverse events were acute lower extremity edema (n = 27) and acute and transient neuropathy (n = 29). Patients treated with chemotherapy after samarium Sm 153 lexidronam had a higher prevalence of lower extremity edema (9 of 18 [50%]) than those who were not treated with chemotherapy after samarium Sm 153 lexidronam (18 of 85 [21.2%]) (p = 0.01, chi-square test). No adverse events were correlated with EBRT. Conclusions: Our observation of new-onset, acute and transient edema and neuropathy after samarium Sm 153 lexidronam and of a relationship between edema and post-samarium Sm 153 lexidronam chemotherapy suggests the need for re-examination of patients in past series or for a prospective investigation with nonhematologic adverse events as a primary endpoint.

Paravati, Anthony J., E-mail: Anthony.J.Paravati@dartmouth.edu [Dartmouth Medical School, Hanover, NH (United States); Russo, Andrea L. [Dartmouth Medical School, Hanover, NH (United States); Aitken, Candice [Dartmouth Medical School, Hanover, NH (United States); Department of Medicine, Section of Radiation Oncology, Dartmouth-Hitchcock Medical Center, Lebanon, NH (Lebanon)

2011-10-01

177

Electronic Excitations in Lanthanum Cuprates Measured by Resonant Inelastic X-ray Scattering  

NASA Astrophysics Data System (ADS)

Excitations of the valence electrons in the high-temperature superconducting cuprate La2--xSr xCuO4 were measured by Resonant Inelastic X-ray Scattering (RIXS). Several types of electronic excitations resonant at the Cu 1s?4p transition were studied over a wide range of dopings 0 ? x ? 0.35. A 500 meV excitation was observed at a reduced momentum transfer q=(pi 0) corresponding to the zone boundary, whose temperature and doping dependence was the same as the two-magnon Raman scattering mode. The momentum dependence of this 2-magnon excitation agrees with recent theoretical calculations. Momentum resolved measurements of the x=0 sample revealed a broad range of excitations above and below the main charge transfer peak, and their dispersions were measured across the Brillouin zone. These include a dispersionless ˜1.8 eV peak, which is either a local crystal field ( d-d excitation) or dipole-forbidden charge transfer excitation, and a dispersive 2.2 eV peak identified as a Zhang-Ng type charge-transfer exciton. The 2.2 eV peak was less dispersive than predicted from the theoretical models, due to electron-phonon coupling, as illustrated by the temperature dependent shift in the peak position. With increased hole doping, the RIXS spectral weight transfers from higher to lower energies, analogous to earlier optical conductivity studies. At the finite momentum of q=(pi 0), however, the changes are most systematic: an isosbestic point was observed at 2.2 eV where the spectra of all dopings cross, and spectral weight is transferred from high to low energies, with near-linear dependence on x, in a manner suggesting that the integrated RIXS intensity is preserved. The intensity and energy variations of the spectral peaks, as well as the isosbestic point and possible sum rule, could be explained qualitatively by a rigid three-band model which includes the non-bonding oxygen, upper Hubbard, and Zhang-Rice singlet bands. The estimated properties of the bands, such as width and energy separation, are in reasonably quantitative agreement with current theoretical models and angle-resolved photoemission measurements. Moreover, anomalies in the doping dependence are similar to those observed in other types of spectroscopies. These results underscore the relevance of the RIXS method in understanding the electronic behavior of the Lanthanum cuprates.

Ellis, David Shai

178

Blue-white tunable luminescence for white light-emitting diodes and wideband near-infrared luminescence from Sm3+-doped borophosphate glass  

NASA Astrophysics Data System (ADS)

Highly transparent samarium (Sm3+) doped borophosphate glasses were prepared using the melt-quenching technique. The tunable light emission and wideband near-infrared luminescence properties of Sm3+-doped glasses were investigated systemically. Tuning the Sm3+ concentration and excitation wavelength can generate hues that vary from blue to white. Two wide luminescence bands in the 850 nm to 1070 nm range and in the 1100 nm to 1250 nm range, respectively, were also achieved. The results suggest that Sm3+-doped borophosphate glasses can be used as conversion materials for blue light-emitting diode chips to generate white light-emitting diodes and for optical amplification.

Sheng, Qiuchun; Shen, Yinglong; Liu, Shuang; Li, Wentao; Chen, Danping

2012-08-01

179

Sm3+ doped lithium aluminoborate glasses for orange coloured visible laser host material  

NASA Astrophysics Data System (ADS)

Samarium doped lithium aluminium borate glasses have been prepared by conventional melt quench technique and their detailed spectroscopic analysis has been done. The structural analysis has been done by using FTIR studies and density is measured by Archimedes method. The UV-vis-NIR absorption spectra show an increase in intensity of different transitions from the ground level 6H5/2 to various 2S+1LJ levels with an increase in samarium concentration at the expense of aluminium. The fluorescence spectra show several transitions from 4G5/2 to various 6HJ levels along with 4F3/2 to 6HJ and 4G7/2 to 6H5/2.

Kaur, Parvinder; Kaur, Simranpreet; Singh, Gurinder Pal; Singh, D. P.

2013-10-01

180

Radiotracer study of the preparation of high-purity lanthanum fluoride  

SciTech Connect

This paper reports that the behavior of the impurities iron, cobalt, yttrium, and cerium is determined via radiotracer techniques for the preparation of high-purity lanthanum fluoride. The behavior of nickel and copper during the coprecipitation of a lanthanum nitrate solution is determined by graphite furnace atomic absorption spectrometric (GFAAS) analysis. There is no commercially available radiotracer for neodymium, a key impurity associated with absorption losses in fluoride glasses. However, the chemical behavior of neodymium and that of yttrium are very similar and, therefore, it is reasonable to assume that the behavior of yttrium throughout the processing is indicative of the behavior of neodymium. The concentrations of impurities in lanthanum nitrate, carbonate, and fluoride are estimated using the radiotracer and GFAAS data for each processing step. Results indicate that while high-purity lanthanum carbonate can be prepared, any impurities present in the lanthanum carbonate will be carried quantitatively into lanthanum fluoride upon hydrofluorination.

Ewing, K.J.; Jaganathan, J.; Peitersen, L.; Aggarwal, I.D. (Naval Research Lab., Code 6505, Washington, DC (US)); Sommers, J.A.; Fahey, J.V. (Teledyna Wah Chang Albany, Albany, OR (US))

1992-06-01

181

Fabrication of mesoporous and high specific surface area lanthanum carbide–carbon nanotube composites  

Microsoft Academic Search

Mesoporous lanthanum carbide–carbon nanotube composites were produced by means of carbothermal reaction of lanthanum oxide, graphite and multi-walled carbon nanotube mixtures under high vacuum. Residual gas analysis revealed the higher reactivity of lanthanum oxide towards carbon nanotubes compared to graphite. After sintering, the composites revealed a specific surface area increasing with the amount of carbon nanotubes introduced. The meso-porosity of

L. Biasetto; S. Carturan; G. Maggioni; P. Zanonato; P. Di Bernardo; P. Colombo; A. Andrighetto; G. Prete

2009-01-01

182

Encapsulation of lanthanum carbide in carbon nanotubes and carbon nanoparticles  

Microsoft Academic Search

The morphologies of lanthanum-filled carbon nanotubes and nanoparticles, made by arc-discharging carbon-La2O3 composites, were examined with high-resolution transmission electron microscopy and selected-area electron diffraction technique. The HRTEM images and corresponding SARD patterns obtained from the arc-discharge product confirmed that ?-LaC2 nanocrystals, most of which are single crystals, had been formed within the nanotubes and nanoparticles. The encapsulated ?-LaC2 crystals showed

Mingqui Liu; John M. Cowley

1995-01-01

183

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

PubMed

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 ?-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. PMID:23325290

Hatano, Manabu; Ishihara, Kazuaki

2013-03-11

184

Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires  

NASA Astrophysics Data System (ADS)

Tellurium alloys are characterized by their high performance thermoelectric properties and recent research has shown nanostructured tellurium alloys display even greater performance than bulk equivalents [1-2]. Increased thermoelectric efficiency of nanostructured materials have led to significant interests in developing thin film and nanowire structures. Here, we report on the first successful electrodeposition of lanthanum telluride thin films and nanowires. The electrodeposition of lanthanum telluride thin films is performed in ionic liquids at room temperature. The synthesis of nanowires involves electrodepositing lanthanum telluride arrays into anodic aluminum oxide (AAO) nanoporous membranes. These novel procedures can serve as an alternative means of simple, inexpensive and laboratory-environment friendly methods to synthesize nanostructured thermoelectric materials. The thermoelectric properties of thin films and nanowires will be presented to compare to current state-of-the-art thermoelectric materials. The morphologies and chemical compositions of the deposited films and nanowires are characterized using SEM and EDAX analysis. References: [1] D. M. Rowe, CRC Handbook of Thermoelectrics, CRC Press (1995). [2] A. May et al., Phys. Rev. B 78, 125205 (2008).

Chi, Su; Farias, Stephen; Cammarata, Robert

2013-03-01

185

Nanocomposite structure and reactivity of perovskites based on lanthanum manganites  

NASA Astrophysics Data System (ADS)

Data on the real/defect structure of anion-excess lanthanum manganites are analyzed. It is shown that low-temperature materials, especially those synthesized with the use of organic additives, form nanocomposite structure due to stabilization of manganese and dopant cations in highly charged states (?4+) at anion excess. It is established that domains (layers) with perovskite structure containing point defects are separated/intergrown by extended defect regions enriched with lanthanum or promoter cations. It is noted that the composition and concentration of extended defects are controlled by the conditions of synthesis, the calcination temperature, and the nature of the promoter; these defects, which are partly retained after high-temperature treatment, can affect the functional properties of materials. Features of the cation and anion modification of lanthanum manganites and the reactivity of nanocomposite structures with respect to oxidation reactions are analyzed. It is concluded that at a high content of weakly bound oxygen and a noticeable mobility of the lattice oxygen, the activity of these materials in various oxidation reactions is determined by their defect structure and specificity of the catalytic action.

Kuznetsova, T. G.; Sadykov, V. A.; Lunin, V. V.

2012-04-01

186

Construction of one 2D samarium-organic framework based on 2,4?-biphenyldicarboxylate  

Microsoft Academic Search

A new 2D samarium compound [Sm(2,4?-bpdc)(2,4?-Hbpdc)H2O]n (1) (2,4?-H2bpdc = 2,4?-biphenyldicarboxylic acid) has been successfully constructed by the hydrothermal reaction of Sm2O3 with 2,4?-H2bpdc, and characterized by elemental analysis, IR spectroscopy and thermogravimetric analysis, as well as single-crystal X-ray diffraction. The results reveal that complex 1 possesses a 2D framework with 44 topology constructed from one-dimensional lanthanide-carboxylate meso-helical chains [Sm(O–C–O)2]n (?+?)

Xiao-Yi Yi; Zhi-Gang Gu; Ming-Fang Wang; Hong-Yang Jia; Hui-Min Peng; Yin Ying; Xue Gong; Wei-Shan Li; Feng-Qiang Sun; Yue-Peng Cai

2011-01-01

187

Lead–samarium alloys for positive grids of valve-regulated lead–acid batteries  

Microsoft Academic Search

The influence of the rare earth metal, samarium, as an alloying additive on the electrochemical behaviour of pure lead is studied by means of X-ray diffraction, self-depassivation, linear sweep voltammetry and a.c. impedance spectroscopy in 4.87M H2SO4 at 25°C. Studies on Pb–Sm alloys (Sm=0.02, 0.04, and 0.12wt.%) indicate that the oxide film formed on the alloy surface at 0.9V is

H. Y. Chen; S. Li; A. J. Li; D. Shu; W. S. Li; C. L. Dou; Q. Wang; G. M. Xiao; S. G. Peng; S. Chen; W. Zhang; H. Wang

2007-01-01

188

Chondrite barium, neodymium, and samarium isotopic heterogeneity and early Earth differentiation.  

PubMed

Isotopic variability in barium, neodymium, and samarium in carbonaceous chondrites reflects the distinct stellar nucleosynthetic contributions to the early solar system. We used 148Nd/144Nd to correct for the observed s-process deficiency, which produced a chondrite 146Sm-142Nd isochron consistent with previous estimates of the initial solar system abundance of 146Sm and a 142Nd/144Nd at average chondrite Sm/Nd ratio that is lower than that measured in terrestrial rocks by 21 +/- 3 parts per million. This result strengthens the conclusion that the deficiency in 142Nd in chondrites relative to terrestrial rocks reflects 146Sm decayand earlyplanetary differentiation processes. PMID:17525335

Carlson, Richard W; Boyet, Maud; Horan, Mary

2007-05-25

189

Nano- and microsized Eu(3+) and Tb(3+)-doped lanthanide hydroxycarbonates and oxycarbonates. The influence of glucose and fructose as stabilizing ligands.  

PubMed

Europium and terbium-doped lanthanum hydroxycarbonate and lanthanum oxycarbonate nanoparticles were fabricated under two different reaction conditions using lanthanide acetate and urea as the starting materials. The photoluminescence properties of these hydroxycarbonate and oxycarbonate particles, and of their colloidal suspensions in water, were studied. The Eu(3+) (5)D(0)?(7)F(J) and Tb(3+) (5)D(4)?(7)F(J) emission spectra and the luminescence lifetimes in the two carbonate matrices were measured. Terbium-doped cerium oxycarbonate particles were synthesized, and the energy transfer process from Ce(3+) to Tb(3+) was investigated. The synthesis of lanthanum and cerium oxycarbonates was also carried out in the presence of stabilizing ligands: glucose and fructose. The influence of these ligands on the structure and luminescence was explored. PMID:23361038

Kaczmarek, Anna M; Miermans, Linde; Van Deun, Rik

2013-04-01

190

Dietary administration in rodent studies distorts the tissue deposition profile of lanthanum carbonate; brain deposition is a contamination artefact?  

Microsoft Academic Search

Lanthanum carbonate is a non-calcium phosphate binder used to control hyperphosphataemia in patients with chronic kidney disease who are undergoing dialysis. Ultrastructurally, lanthanum ions are too large to traverse the tight junctions in the blood–brain barrier, yet tissue distribution studies using dietary administration have reported low concentrations in rodent brain, raising concern about accumulation. To investigate this, tissue lanthanum concentrations

Stephen J. P. Damment; Alan G. Cox; Roger Secker

2009-01-01

191

Factors Affecting Lanthanum and Cerium Biosorption on Pinus brutia Leaf Powder  

Microsoft Academic Search

The biosorption behavior of lanthanum and cerium ions from aqueous solution by leaf powder of Pinus brutia was separately studied in a batch system as a function of initial pH, contact time, initial metal ion concentration, temperature, and adsorbent amount. The uptake of lanthanum and cerium was increased when the initial pH of the solution was increased. Thermodynamic parameters such

Ceren Kütahyali; ?enol Sert; Berkan Çetinkaya; Süleyman Inan; Meral Eral

2010-01-01

192

Lanthanum hexaaluminate — novel thermal barrier coatings for gas turbine applications — materials and process development  

Microsoft Academic Search

Lanthanum hexaaluminate (LHA) with a magnetoplumbite structure is a promising competitor to yttria partially stabilized zirconia (Y-PSZ) as a thermal barrier coating (TBC), since most zirconia coatings age significantly, including undesired densification at temperatures exceeding 1100 °C. The microstructure of calcined lanthanum hexaaluminate powders and thermally sprayed coatings show a platelet structure. The magnetoplumbite structure is characterized by the highly

R. Gadow; M. Lischka

2002-01-01

193

Pulsed laser deposition of lanthanum monosulfide thin films on silicon substrates*  

E-print Network

Pulsed laser deposition of lanthanum monosulfide thin films on silicon substrates* S. Fairchilda; accepted 13 December 2004; published 26 January 2005 Thin films of lanthanum monosulfide LaS have beenS generally present in LaS samples using a high- temperature carbon reduction process

Boolchand, Punit

194

Bone-seeking radiopharmaceuticals as targeted agents of osteosarcoma: samarium-153-EDTMP and radium-223.  

PubMed

Osteosarcoma is a cancer characterized by formation of bone by malignant cells. Routine bone scan imaging with Tc-99m-MDP is done at diagnosis to evaluate primary tumor uptake and check for bone metastases. At time of relapse the Tc-99m-MDP bone scan also provides a specific means to assess formation of bone by malignant osteosarcoma cells and the potential for bone-seeking radiopharmaceuticals to deliver radioactivity directly into osteoblastic osteosarcoma lesions. This chapter will review and compare a bone-seeking radiopharmaceutical that emits beta-particles, samarium-153-EDTMP, with an alpha-particle emitter, radium-223. The charged alpha particles from radium-223 have far more mass and energy than beta particles (electrons) from Sm-153-EDTMP. Because radium-223 has less marrow toxicity and more radiobiological effectiveness, especially if inside the bone forming cancer cell than samarium-153-EDTMP, radium-223 may have greater potential to become widely used against osteosarcoma as a targeted therapy. Radium-223 also has more potential to be used with chemotherapy against osteosarcoma and bone metastases. Because osteosarcoma makes bone and radium-223 acts like calcium, this radiopharmaceutical could possibly become a new targeted means to achieve safe and effective reduction of tumor burden as well as facilitate better surgery and/or radiotherapy for difficult to resect large, or metastatic tumors. PMID:24924181

Anderson, Peter M; Subbiah, Vivek; Rohren, Eric

2014-01-01

195

Samarium153-EDTMP:Pharmacokinetic, Toxicity and Pain Response Using an Escalating Dose Schedule in Treatment of Metastatic Bone Cancer  

Microsoft Academic Search

Samarium-153 emitsmedium-energy beta particlesand an imageable gammaphotonwith a physicalhalf-lifeof 46.3hr. Whenchelatedto ethylenediaminetetramethylenephosphonic acid(EDTMP), it is remarkably stablein vitro andin vivo.In this study, we administered escalating amounts of 1@Sm EDTMP, from 0.1 to 1.0 mCi\\/kg (3.7â€\\

Mehdi Farhanghi; Richard A. Holmes; Wynn A. Volkert; K. William Logan; Amolak Singh

196

Novel and facile selective reduction of carboxylic acid with a samarium diiodide–lanthanide triflate–methanol–base system  

Microsoft Academic Search

The facile selective reduction of carboxylic acids in the presence of an aldehyde or that bearing a formyl group proceeded smoothly with a samarium diiodide–lanthanide triflate–methanol–base system at room temperature to give the corresponding alcohols in good to almost quantitative yield.

Yasuko Kamochi; Tadahiro Kudo

2000-01-01

197

Atomic Mass and Nuclear Binding Energy for La-171 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-171 (Lanthanum, atomic number Z = 57, mass number A = 171).

Sukhoruchkin, S. I.; Soroko, Z. N.

198

Calcium Lanthanum Sulfide As A Long Wavelength IR Material  

NASA Astrophysics Data System (ADS)

Calcium lanthanum sulfide (CLS) is under development as a long wavelength infrared (LWIR) window/dome. A coating has been demonstrated to protect CLS from the effects of high humidity and to increase its resistance to rain drop impact damage. Coated CLS exhibits better impact damage resistance than coated ZnS. Processing studies have focussed on improving the optical quality and fracture strength of CLS. Recent work has also concentrated on materials with a molar composition of 90 La2S3 : 10 CaS.

Gentilman, Richard L.; Dekosky, Melissa B.; Wong, Thomas Y.; Tustison, Randal W.; Hills, Marian E.

1988-07-01

199

Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium  

SciTech Connect

The purpose of the present work is to accurately measure the neutron cross sections of samarium. The most significant isotope is {sup 149}Sm, which has a large neutron absorption cross section at thermal energies and is a {sup 235}U fission product with a 1% yield. Its cross sections are thus of concern to reactor neutronics. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic institute (RPI) LINAC facility using metallic and liquid Sm samples. The capture measurements were made at the 25 meter flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at 15- and 25-meter flight stations with {sup 6}Li glass scintillation detectors. Resonance parameters were determined by a combined analysis of six experiments (three capture and three transmission) using the multi-level R-matrix Bayesian code SAMMY version M2. The significant features of this work are as follows. Dilute samples of samarium nitrate in deuterated water (D{sub 2}O) were prepared to measure the strong resonances at 0.1 and 8 eV without saturation. Disk-shaped spectroscopic quartz cells were obtained with parallel inner surfaces to provide a uniform thickness of solution. The diluent feature of the SAMMY program was used to analyze these data. The SAMMY program also includes multiple scattering corrections to capture yield data and resolution functions specific to the RPI facility. Resonance parameters for all stable isotopes of samarium were deduced for all resonances up to 30 eV. Thermal capture cross-section and capture resonance integral calculations were made using the resultant resonance parameters and were compared to results obtained using resonance parameters from ENDF/B-VI updated through release 3. Extending the definition of the capture resonance integral to include the strong 0.1 eV resonance in {sup 149}Sm, present measurements agree within estimated uncertainties with EnDF/B-VI release 3. The thermal capture cross-section was calculated from the present measurements of the resonance parameters and also agrees with ENDF within estimated uncertainties. The present measurements reduce the statistical uncertainties in resonance parameters compared to prior measurements.

G. Leinweber; J.A. Burke; H.D. Knox; N.J. Drindak; D.W. Mesh; W.T. Haines; R.V. Ballad; R.C. Block; R.E. Slovacek; C.J. Werner; M.J. Trbovich; D.P. Barry; T. Sato

2001-07-16

200

Intramolecular nucleophilic acyl substitution reactions mediated by samarium(II) iodide: A convergent approach to the preparation of enantiomerically enriched 4-hydroxy ketones from 3-iodopropyl carboxylates  

SciTech Connect

A combination of samarium(II) iodide and iron(III) catalyst have been investigated with respect to the ability to stereochemically convert carboxylates to ketones. Racemization of centers {alpha} to the carbonyl were observed.

Molander, G.A.; Shakya, S.R. [Univ. of Colorado, Boulder, CO (United States)

1994-06-17

201

Synthesis and crystal structure of a four-coordinate aryloxo samarium complex [Sm(OAr) 3(THF)](THF) (OAr = 2.6-ditertbutyl-4-methylphenoxo)  

Microsoft Academic Search

The aryloxo samarium complex [Sm(ArO)3(THF)](THF) has been prepared by the reaction of SmCl3 with 3 equiv. of NaOAr in THF. An X-ray crystallographic analysis shows the complex to be a four-coordinate aryloxide complex. Three oxygen atoms of aryloxo and one oxygen atom of THF coordinate to the samarium to form a distorted tetrahedron. The average Sm?O(Ar) distance is 2.151(7) Å.

Qi Shen

1995-01-01

202

Radio-opaque fecal impaction and pseudo-occlusion in a dialyzed patient taking lanthanum carbonate.  

PubMed

Lanthanum therapy is an efficient therapy of hyperphosphoremia by chelating phosphore in the digestive tract. Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table. This drug is lightly absorbed and has low water solubility. It should be borne in mind that abdominal X-rays of patients taking lanthanum carbonate may have a radio-opaque appearance typical of imaging agents. This characteristic is suggested to confirm adherence of the patient by doing an abdominal X-ray. We describe in our case a particular good compliant patient with slow digestive transit, which ends by pseudo-occlusion. PMID:22118504

Muller, Clotilde; Muller, Sandrine; Sissoko, Aicha; Klein, Alexandre; Faller, Bernadette; Chantrel, Francois

2012-10-01

203

Samarium solubility in an yttrium- and gadolinium-containing magnesium-based solid solution  

NASA Astrophysics Data System (ADS)

Metallographic, X-ray diffraction, and electron microprobe analyses and electrical resistivity measurements are used to study the samarium solubility in a magnesium-based solid solution containing equal fractions of yttrium and gadolinium at 500, 400, and 300°C. The regions of existence of the magnesium-based solid solution at these temperatures and the phases in equilibrium with this solid solution are determined. The magnesium solid solution is found to be in equilibrium only with the Mg41Sm5 and Mg24(Y, Gd)5 phases, which belong to the binary Mg-Sm and Mg-Y-Gd systems, respectively. These results are used to construct isothermal sections of the Mg-Y-Gd-Sm phase diagram at 500, 400, and 300°C and equal yttrium and gadolinium contents in the region adjacent to the magnesium solid solution.

Luk'yanova, E. A.; Rokhlin, L. L.; Dobatkina, T. V.; Korol'kova, I. G.

2012-07-01

204

Cellulose-lanthanum hydroxide nanocomposite as a selective marker for detection of toxic copper  

NASA Astrophysics Data System (ADS)

In this current report, a simple, reliable, and rapid method based on modifying the cellulose surface by doping it with different percentages of lanthanum hydroxide (i.e., 1% La(OH)3-cellulose (LC), 5% La(OH)3-cellulose (LC2), and 10% La(OH)3-cellulose (LC3)) was proposed as a selective marker for detection of copper (Cu(II)) in aqueous medium. Surface properties of the newly modified cellulose phases were confirmed by Fourier transform infrared spectroscopy, field emission scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopic analysis. The effect of pH on the adsorption of modified cellulose phases for Cu(II) was evaluated, and LC3 was found to be the most selective for Cu(II) at pH 6.0. Other parameters, influencing the maximum uptake of Cu(II) on LC3, were also investigated for a deeper mechanistic understanding of the adsorption phenomena. Results showed that the adsorption capacity for Cu(II) was improved by 211% on the LC3 phase as compared to diethylaminoethyl cellulose phase after only 2 h contact time. Adsorption isotherm data established that the adsorption process nature was monolayer with a homogeneous adsorbent surface. Results displayed that the adsorption of Cu(II) onto the LC3 phase obeyed a pseudo-second-order kinetic model. Selectivity studies toward eight metal ions, i.e., Cd(II), Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Ni(II), and Zn(II), were further performed at the optimized pH value. Based on the selectivity study, it was found that Cu(II) is highly selective toward the LC3 phase. Moreover, the efficiency of the proposed method was supported by implementing it to real environmental water samples with adequate results.

Marwani, Hadi M.; Lodhi, Mazhar Ullah; Khan, Sher Bahadar; Asiri, Abdullah M.

2014-09-01

205

Cellulose-lanthanum hydroxide nanocomposite as a selective marker for detection of toxic copper.  

PubMed

In this current report, a simple, reliable, and rapid method based on modifying the cellulose surface by doping it with different percentages of lanthanum hydroxide (i.e., 1% La(OH)3-cellulose (LC), 5% La(OH)3-cellulose (LC2), and 10% La(OH)3-cellulose (LC3)) was proposed as a selective marker for detection of copper (Cu(II)) in aqueous medium. Surface properties of the newly modified cellulose phases were confirmed by Fourier transform infrared spectroscopy, field emission scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopic analysis. The effect of pH on the adsorption of modified cellulose phases for Cu(II) was evaluated, and LC3 was found to be the most selective for Cu(II) at pH 6.0. Other parameters, influencing the maximum uptake of Cu(II) on LC3, were also investigated for a deeper mechanistic understanding of the adsorption phenomena. Results showed that the adsorption capacity for Cu(II) was improved by 211% on the LC3 phase as compared to diethylaminoethyl cellulose phase after only 2 h contact time. Adsorption isotherm data established that the adsorption process nature was monolayer with a homogeneous adsorbent surface. Results displayed that the adsorption of Cu(II) onto the LC3 phase obeyed a pseudo-second-order kinetic model. Selectivity studies toward eight metal ions, i.e., Cd(II), Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Ni(II), and Zn(II), were further performed at the optimized pH value. Based on the selectivity study, it was found that Cu(II) is highly selective toward the LC3 phase. Moreover, the efficiency of the proposed method was supported by implementing it to real environmental water samples with adequate results. PMID:25258599

Marwani, Hadi M; Lodhi, Mazhar Ullah; Khan, Sher Bahadar; Asiri, Abdullah M

2014-01-01

206

Cellulose-lanthanum hydroxide nanocomposite as a selective marker for detection of toxic copper  

PubMed Central

In this current report, a simple, reliable, and rapid method based on modifying the cellulose surface by doping it with different percentages of lanthanum hydroxide (i.e., 1% La(OH)3-cellulose (LC), 5% La(OH)3-cellulose (LC2), and 10% La(OH)3-cellulose (LC3)) was proposed as a selective marker for detection of copper (Cu(II)) in aqueous medium. Surface properties of the newly modified cellulose phases were confirmed by Fourier transform infrared spectroscopy, field emission scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopic analysis. The effect of pH on the adsorption of modified cellulose phases for Cu(II) was evaluated, and LC3 was found to be the most selective for Cu(II) at pH 6.0. Other parameters, influencing the maximum uptake of Cu(II) on LC3, were also investigated for a deeper mechanistic understanding of the adsorption phenomena. Results showed that the adsorption capacity for Cu(II) was improved by 211% on the LC3 phase as compared to diethylaminoethyl cellulose phase after only 2 h contact time. Adsorption isotherm data established that the adsorption process nature was monolayer with a homogeneous adsorbent surface. Results displayed that the adsorption of Cu(II) onto the LC3 phase obeyed a pseudo-second-order kinetic model. Selectivity studies toward eight metal ions, i.e., Cd(II), Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Ni(II), and Zn(II), were further performed at the optimized pH value. Based on the selectivity study, it was found that Cu(II) is highly selective toward the LC3 phase. Moreover, the efficiency of the proposed method was supported by implementing it to real environmental water samples with adequate results. PMID:25258599

2014-01-01

207

Superparamagnetic properties of La1 - x Sr x Mn0.925Zn0.075O3 ( x = 0.075, 0.095, and 0.115) lanthanum manganites  

NASA Astrophysics Data System (ADS)

Lanthanum-strontium manganites doped with zinc are studied by the method of electron magnetic resonance. Nano-objects with ferromagnetically correlated spins, which behave themselves like superparamagnetic particles in the magnetic resonance spectrum, have been found in the paramagnetic phase. The temperature dependences of the resonance magnetic field and magnetic resonance linewidth for La1 - x Sr x Mn0.925Zn0.075O3 ceramic samples at temperatures ranging from 100 to 340 K have been analyzed on the basis of the Raikher-Stepanov theory of superparamagnetic particles. The magnetic moment, anisotropy field, and characteristic size of the regions of the ferromagnetically correlated spins have been determined.

Eremina, R. M.; Sharipov, K. R.; Mingalieva, L. V.; Badelin, A. G.

2014-02-01

208

Preparation and use of samarium diiodide (SmI(2)) in organic synthesis: the mechanistic role of HMPA and Ni(II) salts in the samarium Barbier reaction.  

PubMed

Although initially considered an esoteric reagent, SmI(2) has become a common tool for synthetic organic chemists. SmI(2) is generated through the addition of molecular iodine to samarium metal in THF.(1,2-3) It is a mild and selective single electron reductant and its versatility is a result of its ability to initiate a wide range of reductions including C-C bond-forming and cascade or sequential reactions. SmI(2) can reduce a variety of functional groups including sulfoxides and sulfones, phosphine oxides, epoxides, alkyl and aryl halides, carbonyls, and conjugated double bonds.(2-12) One of the fascinating features of SmI-(2)-mediated reactions is the ability to manipulate the outcome of reactions through the selective use of cosolvents or additives. In most instances, additives are essential in controlling the rate of reduction and the chemo- or stereoselectivity of reactions.(13-14) Additives commonly utilized to fine tune the reactivity of SmI(2) can be classified into three major groups: (1) Lewis bases (HMPA, other electron-donor ligands, chelating ethers, etc.), (2) proton sources (alcohols, water etc.), and (3) inorganic additives (Ni(acac)(2), FeCl(3), etc).(3) Understanding the mechanism of SmI(2) reactions and the role of the additives enables utilization of the full potential of the reagent in organic synthesis. The Sm-Barbier reaction is chosen to illustrate the synthetic importance and mechanistic role of two common additives: HMPA and Ni(II) in this reaction. The Sm-Barbier reaction is similar to the traditional Grignard reaction with the only difference being that the alkyl halide, carbonyl, and Sm reductant are mixed simultaneously in one pot.(1,15) Examples of Sm-mediated Barbier reactions with a range of coupling partners have been reported,(1,3,7,10,12) and have been utilized in key steps of the synthesis of large natural products.(16,17) Previous studies on the effect of additives on SmI(2) reactions have shown that HMPA enhances the reduction potential of SmI(2) by coordinating to the samarium metal center, producing a more powerful,(13-14,18) sterically encumbered reductant(19-21) and in some cases playing an integral role in post electron-transfer steps facilitating subsequent bond-forming events.(22) In the Sm-Barbier reaction, HMPA has been shown to additionally activate the alkyl halide by forming a complex in a pre-equilibrium step.(23) Ni(II) salts are a catalytic additive used frequently in Sm-mediated transformations.(24-27) Though critical for success, the mechanistic role of Ni(II) was not known in these reactions. Recently it has been shown that SmI(2) reduces Ni(II) to Ni(0), and the reaction is then carried out through organometallic Ni(0) chemistry.(28) These mechanistic studies highlight that although the same Barbier product is obtained, the use of different additives in the SmI(2) reaction drastically alters the mechanistic pathway of the reaction. The protocol for running these SmI(2)-initiated reactions is described. PMID:23407417

Sadasivam, Dhandapani V; Choquette, Kimberly A; Flowers, Robert A

2013-01-01

209

Thermodynamic properties of lanthanum in gallium-indium eutectic based alloys  

NASA Astrophysics Data System (ADS)

Activity and activity coefficients of lanthanum were determined for the first time in gallium-indium eutectic based alloys in a wide temperature range employing electromotive force method. Activity of ?-La and super cooled liquid lanthanum in Ga-In eutectic based alloys between 573 and 1073 K linearly depends on the reciprocal temperature: lga=5.660-{15,352}/{T}±0.093 lga=6.074-{15,839}/{T}±0.093 Activity coefficients of ?-La and super cooled liquid lanthanum in this system at 617-1073 K are described by the following equations: lg?=3.786-{12,216}/{T}±0.171 lg?=4.199-{12,703}/{T}±0.171 In addition activity of lanthanum in alloys with In was also determined in the same temperature range.

Shchetinskiy, A. V.; Dedyukhin, A. S.; Volkovich, V. A.; Yamshchikov, L. F.; Maisheva, A. I.; Osipenko, A. G.; Kormilitsyn, M. V.

2013-04-01

210

High-temperature studies of the magnetic susceptibility of samarium and the Al{sub 2}Sm compound  

SciTech Connect

The magnetic susceptibility of metallic samarium and the Al{sub 2}Sm intermetallic compound has been experimentally studied by the Faraday method in the temperature range of 300-1800 K. It has been shown that the temperature dependences of the magnetic susceptibility of Sm and Al{sub 2}Sm in a crystalline state can be described in the framework of Van Vleck paramagnetism theory taking into account variable valence and the contribution from the conduction electrons. Using this theoretical interpretation of the data, the effective valence of samarium in the metallic state and in the Al{sub 2}Sm intermetallic compound has been estimated as a function of the temperature.

Uporova, N. S., E-mail: fominans@rambler.ru [Ural State Pedagogical University (Russian Federation); Uporov, S. A. [Russian Academy of Sciences, Institute of Metallurgy, Ural Branch (Russian Federation); Sidorov, V. E. [Ural State Pedagogical University (Russian Federation)

2012-02-15

211

Ferroelectric domain structure of lanthanum-modified lead titanate ceramics  

SciTech Connect

The ferroelectric domain configurations in lanthanum-modified lead titanate ceramics have been studied by transmission electron microscopy in conventional, analytical, and high-resolution modes. Results indicate a preponderance of {l brace}101{r brace}, twin-related 90{degrees} domains of equilibrium width 50 to 100 nm. These values are consistent with those derived from consideration of elastic strain energy. Below a critical grain size of approximately 0.3 {mu}m, single-domain grains are found. A domain wall energy of 1 mJ/m{sup 2} was calculated based on this observation. Within such twins are occasionally found ordered domains, displaying little or no misorientation with respect to one another. In addition, {l brace}001{r brace}, 180{degrees} domains were observed.

Demczyk, B.G.; Rai, R.S.; Thomas, G. (California Univ., Berkeley, CA (USA). Dept. of Materials Science and Mineral Engineering)

1990-03-01

212

Domain structure of lanthanum modified lead titanate ceramics  

SciTech Connect

The domain configurations in lanthanum modified lead titanate ferroelectric ceramics have been studied by transmission electron microscopy, in both the conventional and analytical modes. Results indicate a preponderance of (110), twin related 90/sup 0/ domains of equilibrium width approximately 400 A. This value is independent of grain size above a critical value and is consistent with values derived from consideration of elastic strain energy. Below this critical value (approximately 400 A), single domain grains are found. A domain wall energy of 10 ergs/cm/sup 2/ was calculated based on this observation. Such domains also occasionally display multiple twinning, also among (110). In addition, (100), 180/sup 0/ domains are found, which display crystallographic misorientation of less than 0.5/sup 0/. The reversibility and observed microstructure of the paraelectric to ferroelectric phase transformation strongly resembles that observed in martensite.

Demczyk, B.G.

1985-08-01

213

Fabrication of calcium lanthanum sulfide ceramic by carbonate coprecipitating method  

SciTech Connect

Translucent CLS (calcium lanthanum sulfide) pellets were formed by the carbonate coprecipitation method, CS[sub 2] sulfurization, and hot press sintering. For a La/Ca = 2.5 pellet with 1.3 mm in thickness, the transmittance at 13 [mu]m is about 25% after sintering at 1,150 C for 30 minutes and resulfurizing at 950 C for 1 hour. For a La/Ca = 15 pellet with 0.9 mm in thickness the IR transmittance is about 51% at 13 [mu]m after sintering at 1,050 C for 2 hours and resulfurizing at 950 C for 1 hour. Beta-La[sub 2]S[sub 3] is present as a second phase after sintering at 1,150 C for 30 minutes. After resulfurization, the second phase disappears for the La/Ca = 2.5 pellet, but still exists in the La/Ca = 15 pellet.

Tsai, M.S.; Hon, M.H. (National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering)

1995-03-01

214

Novel lanthanum(III) membrane sensor based on a new NS Schiff’s base  

Microsoft Academic Search

A novel lanthanum(III) sensor based on bis(thiophenal)phenylen-1,3-diamine (TPD) is described. The sensor was prepared by incorporating the TPD into plasticized PVC membrane. The sensor displays high selectivity for lanthanum with respect to many common alkali, alkaline earth, transition and heavy metal ions. The effect of membrane composition and pH and influence of additive anionic on the response properties of were

Mohammad Reza Ganjali; Mahnaz Qomi; Azadeh Daftari; Parviz Norouzi; Masoud Salavati-Niasari; Mohammad Rabbani

2004-01-01

215

Thermochemistry of binary alloys of lanthanum with 3 d -transition metals  

Microsoft Academic Search

The enthalpy of mixing for liquid binary alloys of lanthanum with 3d-transition metals (Sc, Ti, V, Cr, and Fe) is determined\\u000a by a calorimetric method within the field of compositions rich in lanthanum. Data for the partial enthalpy of mixing in the\\u000a La-3d-metal system with infinite dilution demonstrates a complex relationship of a change in it in the series of

V. V. Berezutskii; N. I. Usenko; M. I. Ivanov

2006-01-01

216

Long-Term Efficacy and Tolerability of Lanthanum Carbonate: Results from a 3Year Study  

Microsoft Academic Search

Background: Control of serum phosphate over the long term is essential in patients with end-stage renal disease. Six-month and 2-year extensions to a 6-month study evaluated the long-term safety, tolerability and efficacy of the new phosphate binder lanthanum carbonate. Methods: Patients who participated in a 6-month, randomized trial comparing lanthanum carbonate with calcium carbonate were eligible for a 24-week, open-label

Alastair J. Hutchison; Bart Maes; Johan Vanwalleghem; Gernot Asmus; Elfatih Mohamed; Roland Schmieder; Wolfgang Backs; Rene Jamar; Andre Vosskühler

2006-01-01

217

Interaction of Lanthanum with Boron and Carbon: Phase Diagram and1 Structural Chemistry2  

E-print Network

Interaction of Lanthanum with Boron and Carbon: Phase Diagram and1 Structural Chemistry2 3 a broad homogeneity range described by the12 formula La5(BC)x (5.6x8.8). The lanthanum sesquicarbide La2C3 of carbon leads to the14 decrease of the superconducting temperature from 13.4 K for La2C3 to 10.0 K for La2

Paris-Sud XI, Université de

218

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

Microsoft Academic Search

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 detectors self-activity and crystal contamination jointly contribute a significant amount of uncertainties to

Ding Yuan; Paul Guss; Sanjoy Mukhopadhyay

2009-01-01

219

Preliminary investigation of lanthanum-cerium bromide self-activity removal  

Microsoft Academic Search

It has been reported that detectors made of lanthanum-cerium halides (LaBr3:Ce and CeBr3) have superior energy resolution for gamma-radiation detection compared to what is offered by conventional sodium iodide (NaI:T1) detectors. Although superior energy resolution may be observed, one major barrier that has hindered the rapid adaptation of lanthanum halides is their self-activity, due primarily to the presence of isotope

Ding Yuan; Paul Guss

2011-01-01

220

Temperature dependence of the samarium oxidation state in SmB6 and Sm1-xLaxB6  

E-print Network

1141 Temperature dependence of the samarium oxidation state in SmB6 and Sm1-xLaxB6 J. M. Tarascon 1980) Résumé. 2014 La variation thermique du paramètre de la maille cristalline de SmB6 ainsi que des comportement analogue à celui de SmB6 a été observé pour la solution solide Sm0,75La0,25B6. Abstract. 2014

Boyer, Edmond

221

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

PubMed

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. PMID:22723728

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

222

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

PubMed Central

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. PMID:21694915

Persy, Veerle P; Behets, Geert J; De Broe, Marc E; D’Haese, Patrick C

2009-01-01

223

Magnetic transitions and electrical transport in Bi-doped lanthanum strontium manganites  

NASA Astrophysics Data System (ADS)

The temperature dependence of the electrical resistivity ?, thermoelectric power S and the magnetic susceptibility ? of La0.7-xBixSr0.3MnO3 (x = 0.05, 0.10, and 0.15 at. %) manganites were investigated. La0.7-xBixSr0.3MnO3 crystallizes in a single phase rhombohedral structure with parasitic phase inclusions. With increasing Bi concentration, a systematic decrease in the ferromagnetic transition temperature (Tc), the metal-semiconducting transition temperature (Tms1) and also the values of activation energies E? and ES from ?(T) and S(T) were observed. On the other hand, in the high-temperature (T > Tms) paramagnetic semiconductor regime, the adiabatic small polaron hopping model fit well, thereby indicating that polaron hopping might be responsible for the conduction mechanism. In addition, the thermoelectric power data at low temperatures were analyzed by considering both the magnon and the phonon drag concept, while the high-temperature data were confirmed a small polaron hopping conduction mechanism.

Ahmed, A. M.; Mohamed, H. F.; Šoka, Martin

2014-05-01

224

Superior oxygen ion conductivity of lanthanum gallate doped with strontium and magnesium  

Microsoft Academic Search

The solid solution range of the La(Sr)Ga(Mg)Oâ perovskite was investigated and the oxygen ion conductivities of corresponding compositions were measured. The solubility of strontium could be extended by the addition of magnesium ions to establish a balance in the oxygen vacancies associated with A and B sites. In this way, the Sr limit in the solid solution was increased to

Peng-nian Huang; A. Petric

1996-01-01

225

Fabrication and spectral properties of Nd 3+-doped yttrium lanthanum oxide transparent ceramics  

NASA Astrophysics Data System (ADS)

Transparent 1 at% Nd 3+:Y 1.9La 0.1O 3 ceramics were fabricated with nanopowders prepared by carbonate coprecipitation method. The powder compacts were sintered in H 2 atmosphere at 1550 °C for 30 h. The Nd 3+:Y 1.9La 0.1O 3 ceramics display uniform grains of about 50 ?m and high transparency. The highest transmittance of the ceramics reaches 67%. The strongest absorption peak is in the wavelength of 820 nm with absorption cross section of 2.48 × 10 -20 cm 2. The absorption is still high at LD wavelength 806 nm with absorption cross section of 1.78 × 10 -20 cm 2 and broad full width at half maximum (FWHM) of about 6.3 nm. The strongest emission peak was centered at 1078 nm with large stimulated emission cross section of 9.63 × 10 -20 cm 2 and broad FWHM of about 7.8 nm. The broad absorption and emission bandwidth of Nd 3+:Y 1.9La 0.1O 3 transparent ceramics are favorable to achieve the miniaturized LD pumping apparatus and ultrashort modelocked pulse laser output, respectively.

Hu, Xiaoman; Yang, Qiuhong; Dou, Chuanguo; Xu, Jun; Zhou, Hongxu

2008-06-01

226

Observation of d-p hybridized aromaticity in lanthanum-doped boron clusters.  

PubMed

The concept of aromaticity has been advanced beyond the framework of organic chemistry, and multiple aromaticity (?, ?, and ?) has been observed to account for the highly symmetric structures or unusual stability of the clusters. In the present study, the electronic structures and chemical bonding of small monolanthanum boride clusters are investigated using photoelectron imaging spectroscopy and first principles electronic structure calculations. Accurate electron affinities of 1.32 ± 0.04 and 1.13 ± 0.06 eV for the neutral LaB2 and LaB3 clusters are obtained by the vibrationally-resolved photoelectron spectra of the LaB2(-) and LaB3(-) clusters, respectively. It is shown that LaB2(-) and LaB3 exhibit enhanced stability in their respective cluster series, as evidenced from the calculated removal energies and HOMO-LUMO gaps. Molecular orbital analysis discloses that these two clusters possess doubly aromatic characters (? and ?), responsible for their enhanced stability. Interestingly, unlike conventional ?-, ?-, and ?-aromaticity formed by the delocalization of unhybridized p or d orbitals, the ? and ? delocalized molecular orbitals shown here are formed through the effective overlap between the 5d atomic orbital of the La atom and the p orbitals of the remaining boron atoms, representing an intriguing d-p hybridized aromaticity. PMID:24141329

Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A W

2014-01-14

227

Development of mixed conducting dense nickel/Ca-doped lanthanum zirconate cermet for gas separation application  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Phase pure La{sub 1.95}Ca{sub 0.05}Zr{sub 2}O{sub 7-{delta}} (LCZ) material is prepared by combustion synthesis. Black-Right-Pointing-Pointer LCZ and Ni-LCZ bulk samples are prepared with theoretical density close to 100%. Black-Right-Pointing-Pointer Bulk electrical conductivity {approx}400 S/cm is obtained for Ni-LCZ cermet at 750 Degree-Sign C. -- Abstract: La{sub 1.95}Ca{sub 0.05}Zr{sub 2}O{sub 7-{delta}} (LCZ) and Ni-LCZ cermet have been prepared by combustion synthesis and conventional solid state mixing methods respectively. Both the materials are sintered in air and controlled atmosphere (5% H{sub 2} in Ar). The density obtained for the material sintered at 1400 Degree-Sign C in controlled atmosphere is found to be more than 99.5%. This sintering temperature (1400 Degree-Sign C) is considered to be much lower compared to the conventional sintering temperature. The corresponding total conductivity for such Ni-LCZ cermet materials is {approx}400 S/cm measured at 750 Degree-Sign C having 40 vol% of Ni and 60 vol% LCZ.

Nag, S. [CSIR - Central Glass and Ceramic Research Institute, 196 Raja S. C. Mullick Road, Kolkata - 700 032 (India)] [CSIR - Central Glass and Ceramic Research Institute, 196 Raja S. C. Mullick Road, Kolkata - 700 032 (India); Mukhopadhyay, S. [Department of Chemical Technology, Calcutta University, 92 A. P. C. Road, Kolkata - 700 009 (India)] [Department of Chemical Technology, Calcutta University, 92 A. P. C. Road, Kolkata - 700 009 (India); Basu, R.N., E-mail: rajenbasu54@gmail.com [CSIR - Central Glass and Ceramic Research Institute, 196 Raja S. C. Mullick Road, Kolkata - 700 032 (India)

2012-03-15

228

Crystal structures and magnetic properties of strontium and copper doped lanthanum ferrites  

NASA Astrophysics Data System (ADS)

The crystal and magnetic structures of La0.8Sr0.2Fe1-xCuxO3-w compounds, which exhibit coercive fields larger than any others reported for iron-based perovskites, have been analyzed at room temperature with the neutron powder diffraction technique and the Rietveld method of profile fitting. For x in the range 0.05-0.10 the material is monophasic with orthorhombic symmetry (space group Pnma), and crystallizes in the perovskite-like cell of LaFeO3, Fe/Cu cations occupy octahedral sites, La/Sr cations are twelve-fold coordinated. For x=0.20 the material is biphasic, with a main orthorhombic phase (space group Pnma) and a secondary rhombohedral phase with space group R-3c (hexagonal setting). The structural transition from the orthorhombic to the rhombohedral phase reduces the structural distortion of the (Fe/Cu)O6 octahedron. The average bond distance (Fe/Cu)-O and the pseudo-cubic unit cell volume decrease with increasing Cu content in accordance with the presence of higher valence states of the transition metals. The magnetic structure was modeled for the monophasic samples (x=0.05 and 0.10) assuming an antiferromagnetic interaction between Fe/Cu neighboring cations (G-type): the magnetic moments order antiferromagnetically along the b-axis, with the spin direction along a-axis. The magnetic moments of the Fe/Cu atoms are ?x=2.66(3)?B and 2.43(3)?B for the compositions x=0.05 and 0.10, respectively. By measuring the first magnetization curve and the hysteresis loops, coexisting antiferromagnetic and weak ferromagnetic interactions were observed for all samples.

Natali Sora, Isabella; Caronna, Tullio; Fontana, Francesca; de Julián Fernández, César; Caneschi, Andrea; Green, Mark

2012-07-01

229

New Samarium(III), Gadolinium(III), and Dysprosium(III) Complexes of Coumarin-3-Carboxylic Acid as Antiproliferative Agents  

PubMed Central

New complexes of samarium(III), gadolinium(III), and dysprosium(III) with coumarin-3-carboxylic acid (HCCA) were prepared by the reaction of the ligand with respective metal nitrates in ethanol. The structures of the final complexes were determined by means of physicochemical data, elemental analysis, IR and Raman spectra. The metal-ligand binding mode in the new Ln(III) complexes of coumarin-3-carboxylic acid was elucidated. The vibrational study gave evidence for bidentate coordination of CCA? to Ln(III) ions through the carbonylic oxygen and the carboxylic oxygen atoms. The complexes were tested for antiproliferative activitiy on the chronic myeloid leukemia-derived K-562, overexpressing the BCR-ABL fusion protein. Cytotoxicity towards tumor cells was determined for a broad concentration range. The samarium salt exerted a very weak antiproliferative effect on these cells. This is in contrast to the lanthanide complexes, especially samarium complex, which exhibited potent antiproliferative activity. The present study confirms our previous observations that the lanthanide complexes of coumarins exhibit antiproliferative activity towards K-562 cell line. PMID:18274603

Kostova, Irena; Momekov, Georgi; Stancheva, Peya

2007-01-01

230

Interaction of oxygen with samarium on Al2O3 thin film grown on Ni3Al(111).  

PubMed

The interaction between oxygen and samarium (Sm) on the well-ordered thin Al2O3 film grown on Ni3Al(111) has been investigated by X-ray photoelectron spectroscopy and synchrotron radiation photoemission spectroscopy. At Sm coverage higher than one monolayer, exposure of oxygen to the Sm films at room temperature leads to the formation of both samarium peroxide (O2(2-)) states and regular samarium oxide (O(2-)) states. By contrast, when exposing O2 to Sm film less than one monolayer on Al2O3, no O2(2-) can be observed. Upon heating to higher temperatures, these metastable O2(2-) states dissociate, supplying active O atoms which can diffuse through the Al2O3 thin film to further oxidize the underlying Ni3Al(111) substrate, leading to the significant increase of the Al2O3 thin film thickness. Therefore, it can be concluded that Sm, presumably in its peroxide form, acts as a catalyst for the further oxidation of the Ni3Al substrate by supplying the active oxygen species at elevated temperatures. PMID:24606375

Cheng, Dingling; Xu, Qian; Han, Yong; Ye, Yifan; Pan, Haibin; Zhu, Junfa

2014-03-01

231

Synthesis and characterization of lanthanum dicarbide-carbon targets for radioactive ion beams generation via the carbothermal reaction  

Microsoft Academic Search

In this study, we report the synthesis procedure for the attainment of thin pellets composed of lanthanum dicarbide (LaC2) grains and graphite, as a candidate material for the production of targets for the generation of radioactive ion beams (RIBs). The samples were obtained by thermal treatment of green pellets of lanthanum oxide or lanthanum oxalate (La2O3 and La2(C2O4)3, respectively) mixed

S. Carturan; M. Tonezzer; L. Piga; P. Zanonato; P. Colombo; A. Andrighetto; L. Biasetto; P. Di Bernardo; G. Maggioni; F. Gramegna; G. Prete

2007-01-01

232

Lanthanum molybdate nanoparticles from the Bradley reaction: factors influencing their composition, structure, and functional characteristics as potential matrixes for luminescent phosphors.  

PubMed

Interaction of lanthanum isopropoxide with molybdenum(VI) alkoxides in La/Mo ratios varying from 3:1 to 1:1 in acetophenon or allyl alcohol as solvents offers nanosized poorly crystalline products of complex composition, where the precipitation of Mo-rich ones is followed by the formation of La-rich ones with conservation of the reaction stoichiometry in total. Thermal treatment of the precipitates at temperatures over 700 °C leads to the formation of stoichiometric phases of the ?- and ?-La2Mo2O9 compositions. Introduction of smaller Re(3+) cations such as Sm(3+) by doping favors stabilization of the La2-xRExMo2O9 phase with improved crystallinity even after lower-temperature thermal treatment. The doping is successful only when the Re(3+) (Sm(3+), Eu(3+), and Tb(3+)) is introduced as an alkoxide: application of Re(3+)(acac)3 as Re(3+) sources leads to materials free from Re(3+). The produced samples were characterized by XPD, TGA, SEM, and TEM studies as well as the luminescent properties for the Sm(3+)-doped phases. PMID:24392745

Abtmeyer, Sarah; P?zik, Robert; Wiglusz, Rafa? J; Ma?ecka, Ma?gorzata; Seisenbaeva, Gulaim A; Kessler, Vadim G

2014-01-21

233

Lanthanum Molybdate Nanoparticles from the Bradley Reaction: Factors Influencing Their Composition, Structure, and Functional Characteristics as Potential Matrixes for Luminescent Phosphors  

PubMed Central

Interaction of lanthanum isopropoxide with molybdenum(VI) alkoxides in La/Mo ratios varying from 3:1 to 1:1 in acetophenon or allyl alcohol as solvents offers nanosized poorly crystalline products of complex composition, where the precipitation of Mo-rich ones is followed by the formation of La-rich ones with conservation of the reaction stoichiometry in total. Thermal treatment of the precipitates at temperatures over 700 °C leads to the formation of stoichiometric phases of the ?- and ?-La2Mo2O9 compositions. Introduction of smaller Re3+ cations such as Sm3+ by doping favors stabilization of the La2–xRExMo2O9 phase with improved crystallinity even after lower-temperature thermal treatment. The doping is successful only when the Re3+ (Sm3+, Eu3+, and Tb3+) is introduced as an alkoxide: application of Re3+(acac)3 as Re3+ sources leads to materials free from Re3+. The produced samples were characterized by XPD, TGA, SEM, and TEM studies as well as the luminescent properties for the Sm3+-doped phases. PMID:24392745

2014-01-01

234

Transition-metal-doped chalcogenide glasses for broadband near-infrared sources  

NASA Astrophysics Data System (ADS)

In this paper we report the spectroscopic data for samples of 0.031% iron, 0.017% nickel, 0.01% chromium and 0.017% cobalt (molar) doped gallium lanthanum sulphide (GLS) glass. Photoluminescence (PL) with a full width half maximum (FWHM) of around 500 nm and peaking between 1120 nm and 1460 nm is observed when excited using wavelengths of 850 nm and 1064 nm. The emission lifetime for nickel-doped GLS at 300 K was measured to be 40 ?s. Photoluminescence excitation (PLE) peaks for chromium-doped GLS at 700 nm and 1020 nm have been observed. By comparisons of our spectroscopic data to that of transition metals doped into other hosts we determine the oxidation states of the transition metal ions and propose transitions for the observed spectroscopic peaks.

Hughes, Mark A.; Aronson, Jonathan E.; Brocklesby, William S.; Shepherd, David P.; Hewak, Daniel W.; Curry, Richard J.

2004-12-01

235

Structural characteristics and UV-light enhanced gas sensitivity of La-doped ZnO nanoparticles  

Microsoft Academic Search

La-doped ZnO nanoparticles were synthesized by sol–gel method starting from zinc acetate dihydrate, lanthanum sesquioxide, alcohol and nitric acid. The crystal structure and morphology of the nanoparticles were characterized by XRD, FESEM, respectively. The thermal decomposition behavior of the the ZnO-based xerogel was detected by TG-DSC. The results show that as-prepared nanoparticles with the hexagonal wurtzite contain the adsorbed water

Chunqiao Ge; Changsheng Xie; Mulin Hu; Yanghai Gui; Zikui Bai; Dawen Zeng

2007-01-01

236

Doping droops.  

PubMed

Drug abuse is a major concern in the athletic world. The misconception among athletes and their coaches is that when an athlete breaks a record it is due to some "magic ingredient" and not because of training, hard work, mental attitude and championship performance. The personal motivation to win in competitive sports has been intensified by national, political, professional and economic incentives. Under this increased pressure athletes have turned to finding this "magic ingredient". Athlete turns to mechanical (exercise, massage), nutritional (vitamins, minerals), pharmacological (medicines) or gene therapies to have an edge over other players. The World Anti-Doping Agency (WADA) has already asked scientists to help find ways to prevent gene therapy from becoming the newest form of doping. The safety of the life of athletes is compromised with all forms of doping techniques, be it a side effect of a drug or a new technique of gene doping. PMID:18175655

Chaturvedi, Aditi; Chaturvedi, Harish; Kalra, Juhi; Kalra, Sudhanshu

2007-01-01

237

Lanthanum Carbonate Reduces Phosphorus Burden in Patients with CKD Stages 3 and 4: A Randomized Trial  

PubMed Central

Background and objectives: Lanthanum carbonate (FOSRENOL®, Shire Pharmaceuticals) is an effective noncalcium, nonresin phosphate binder for the control of hyperphosphatemia in chronic kidney disease (CKD) stage 5 patients undergoing dialysis. Design, setting, participants and measurements: A Phase 2, randomized, double-blind, placebo-controlled trial evaluating the efficacy and safety of lanthanum carbonate in CKD stage 3 and 4 patients. Of 281 patients screened, 121 were randomized (2:1) to lanthanum carbonate or placebo (80 versus 41). The modified intent-to-treat population included 90 patients (56 versus 34); 71 (43 versus 28) completed the study. After run-in, when any current phosphate binders were discontinued and dietary counseling reinforced, patients with serum phosphorus >4.6 mg/dl received lanthanum carbonate (titrated up to 3000 mg/d) or matching placebo for 8 wk. Results: At the end of treatment, 25 (44.6%) versus nine (26.5%) patients had serum phosphorus ?4.6 mg/dl (difference 18.1%, P = 0.12) in the lanthanum carbonate and placebo groups, respectively. Statistically significant differences were observed between groups in change from baseline to end of treatment for serum phosphorus (P = 0.02), intact parathyroid hormone (P = 0.02), and urinary phosphorus excretion (P = 0.04). The safety profile and tolerability of lanthanum carbonate were similar to that of placebo. Conclusions: Because <1% of phosphorus is in the extracellular fluid, serum measurements may not accurately reflect total body burden in patients with CKD stages 3 and 4. However, lanthanum carbonate is an effective phosphate binder in this patient population, with a safety profile and tolerability similar to that of placebo. PMID:19056618

Sprague, Stuart M.; Abboud, Hanna; Qiu, Ping; Dauphin, Matthew; Zhang, Pinggao; Finn, William

2009-01-01

238

In vitro bioequivalence approach for a locally acting gastrointestinal drug: lanthanum carbonate.  

PubMed

A conventional human pharmacokinetic (PK) in vivo study is often considered as the "gold standard" to determine bioequivalence (BE) of drug products. However, this BE approach is not always applicable to the products not intended to be delivered into the systemic circulation. For locally acting gastrointestinal (GI) products, well designed in vitro approaches might be more practical in that they are able not only to qualitatively predict the presence of the active substance at the site of action but also to specifically assess the performance of the active substance. For example, lanthanum carbonate chewable tablet, a locally acting GI phosphate binder when orally administrated, can release free lanthanum ions in the acid environment of the upper GI tract. The lanthanum ions directly reach the site of action to bind with dietary phosphate released from food to form highly insoluble lanthanum-phosphate complexes. This prevents the absorption of phosphate consequently reducing the serum phosphate. Thus, using a conventional PK approach to demonstrate BE is meaningless since plasma levels are not relevant for local efficacy in the GI tract. Additionally the bioavailability of lanthanum carbonate is less than 0.002%, and therefore, the PK approach is not feasible. Therefore, an alternative assessment method is required. This paper presents an in vitro approach that can be used in lieu of PK or clinical studies to determine the BE of lanthanum carbonate chewable tablets. It is hoped that this information can be used to finalize an in vitro guidance for BE studies of lanthanum carbonate chewable tablets as well as to assist with "in vivo" biowaiver decision making. The scientific information might be useful to the pharmaceutical industry for the purpose of planning and designing future BE studies. PMID:23249191

Yang, Yongsheng; Shah, Rakhi B; Yu, Lawrence X; Khan, Mansoor A

2013-02-01

239

Evolution of bone and plasma concentration of lanthanum in dialysis patients before, during 1 year of treatment with lanthanum carbonate and after 2 years of follow-up  

Microsoft Academic Search

Background. Lanthanum carbonate (LC) has been proposed as a new phosphate binder. Presented here are the results from one centre that participated in a multicentre trial to assess the effect of treatment with LC and calcium carbonate (CC) on the evolution of renal osteodystrophy in dialysis patients. Bone biopsies were performed at baseline, after 1 year of treatment and after

Goce B. Spasovski; Aleksandar Sikole; Saso Gelev; Jelka Masin-Spasovska; Tony Freemont; Isabel Webster; Maggie Gill; Chris Jones; Marc E. De Broe; Patrick C. D'Haese

240

Titania-lanthanum phosphate photoactive and hydrophobic new generation catalyst  

SciTech Connect

Titania-lanthanum phosphate nanocomposites with multifunctional properties have been synthesized by aqueous sol-gel method. The precursor sols with varying TiO{sub 2}:LaPO{sub 4} ratios were applied as thin coating on glass substrates in order to be transparent, hydrophobic, photocatalytically active coatings. The phase compositions of the composite powders were identified by powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The anatase phase of TiO{sub 2} in TiO{sub 2}-LaPO{sub 4} composite precursors was found to be stable even on annealing at 800 deg. C. The glass substrates, coated with TL1 (TiO{sub 2}-LaPO{sub 4} composition with 1 mol% LaPO{sub 4}) and TL50 (composite precursor containing TiO{sub 2} and LaPO{sub 4} with molar ratio 1:1) sols and annealed at 400 deg. C, produced contact angles of 74 deg. and 92 deg., respectively, though it is only 62 deg. for pure TiO{sub 2} coating. The glass substrates, coated with TL50 sol, produced surfaces with relatively high roughness and uneven morphology. The TL1 material, annealed at 800 deg. C, has shown the highest UV photoactivity with an apparent rate constant, k{sub app}=24x10{sup -3} min{sup -1}, which is over five times higher than that observed with standard Hombikat UV 100 (k{sub app}=4x10{sup -3} min{sup -1}). The photoactivity combined with a moderate contact angle (85.3 deg.) shows that this material has a promise as an efficient self-cleaning precursor. - Graphical abstract: Multifunctional TiO{sub 2}-LaPO{sub 4} composite stabilizes anatase phase with enhanced photocatalytic activity, and moderately higher hydrophobicity is a promising material for self-cleaning application. Highlights: > Titania-lanthanum phosphate nanocomposites were synthesized by aqueous sol-gel method. > Transparent, hydrophobic, photoactive coatings were developed on glass substrates. > The glass substrates, coated with TL1 annealed at 400 deg. C, produced a contact angle of 74 deg. > The TL1 material at 800 deg. C has shown the highest UV photoactivity (k{sub app}=24x10{sup -3} min{sup -1}). > Photoactivity and moderate contact angle show that this is an efficient self-cleaning precursor.

Jyothi, Chembolli K.; Jaimy, Kanakkanmavudi B. [National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum 695019 (India); Ghosh, Swapankumar, E-mail: swapankumar.ghosh2@mail.dcu.ie [National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum 695019 (India); Sankar, Sasidharan; Smitha, V.S. [National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum 695019 (India); Warrier, K.G.K., E-mail: wwarrierkgk@yahoo.co.in [National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum 695019 (India)

2011-07-15

241

Cation-deficient lanthanum manganite oxides: Experimental and theoretical studies  

NASA Astrophysics Data System (ADS)

Cation-deficient lanthanum manganite oxides with 0.8 ? La/Mn ? 1.25 were synthesized using a multi-step decomposition of gel precursors and investigated from experimental and theoretical point of view. The XRD (X-Ray Diffraction) analysis of the mixed LaMnO 3 oxide crystal concludes to a hexagonal structure, space group R-3c, excluding the presence of pure oxides such as La 2O 3, Mn 2O 3, or MnO 2 whatever the ratio La/Mn is. Oxides with nominal formulae La 1- xMnO 3+ y and LaMn 1- x' O 3+ y contain more than one defect structure involving valence defect (holes h rad ), anionic vacancies as well as cationic vacancies in A and B sublattices of the perovskite structure. With the increase of La or Mn non-stoichiometry, the oxygen content y decreases more with La-deficient compositions than with Mn-deficient ones. The La/Mn ratio influences strongly the relationship between [h rad ], [V Orad rad ], [V La?] and [V Mn?]. The DFT-GGA (Density functional Theory, Generalized-Gradient Approximation) simulation of these compounds using VASP (Vienna Ab-initio Simulation Package) concludes that the electronic structure for the optimized stoichiometric La 6Mn 6O 18 is not optimal, relative to that expected considering Mn(III) ions with four alpha electrons each. The non-stoichiometry is the easiest way of reducing the Jahn-Teller instability by depopulating the half-filled e g orbitals. A partial oxidation is then stabilizing. Creation of defects, either an O insertion or a cationic vacancy, allows finding an ideal count. In the case of pure cationic defects (missing a La(III) or a Mn(III) cation), the amount of vacancies is one missing cation upon twelve. The compact nature of lanthanum manganite oxide does not allow oxygen insertion within the bulk structure and oxidation can only be achieved at the surface without O penetration. The formation of antisites is endothermic. The creation of mixed vicinal vacancies, one oxygen and one cationic vacancy (La or Mn), is exothermic for a concentration of defects of one defect per twelve cations.

Hammami, Ramzi; Harrouch Batis, Narjes; Batis, Habib; Minot, Christian

2009-04-01

242

Lunar prospector measurements of the distribution of incompatible elements gadolinium, samarium and thorium  

SciTech Connect

Lunar Prospector neutron spectrometer (NS) and gamma ray spectrometer (GRS) observations have been used to map out the distribution of incompatible elements on the lunar surface. Specifically, the GRS data provide maps of the distribution of thorium and potassium while the NS data provide information on the distribution of iron and titanium, and the rare earth elements gadolinium and samarium. Using results of analysis of Celementine spectral reflectance (CSR) data, the Fe- and Ti-contributions to the NS data can be removed, leaving primarily rare earth element contributions from Gd and Sm. The Th and K maps correlate with the inferred Gd and Sm maps (r {approximately} 0.93), but there are regions of significant disagreement. One of these is in the KREEP-rich circum-Imbrium ring. No clear explanation has emerged for this disagreement, though Th, K, Gd and Sm have differing degrees of incompatibility. These results clearly are important to discussions of the geochemistry of the Procellarum-Imbrium Th-rich Terrane and the South-Pole-Aitken Terrane.

Elphic, R.C.; Lawrence, D.J.; Feldman, W.C.; Barraclough, B.L. [Los Alamos National Lab., NM (United States); Maurice, S. [Observatoire Midi-Pyrenees, Toulouse (France); Binder, A.B. [Lunar Research Inst., Gilroy, CA (United States); Lucey, P.G. [Univ. of Hawaii, Manoa, HI (United States). Hawaii Inst. of Geophysics and Planetology

1999-04-01

243

Development and evaluation of copper-67 and samarium-153 labeled conjugates for tumor radioimmunotherapy  

SciTech Connect

The potential of utilizing receptor-specific agents such as monoclonal antibodies (MAb), and MAb-derived smaller molecules, as carriers of radionuclides for the selective destruction of tumors has stimulated much research activity. The success of such applications depends on many factors, especially the tumor binding properties of the antibody reagent, the efficiency of labeling and in-vivo stability of the radioconjugate and, on the careful choice of the radionuclide best suited to treat the tumor under consideration. The radiolabeled antibody technique for radioimmunotherapy (RIT), however, has experienced many limitations, and its success has not matched the expectations that were raised more than a decade ago. The problems that have been identified include: (i) degradation of antibody immunoreactivity resulting from chemical manipulations required for labeling; (ii) lack of suitable radioisotopes and methods for stable attachment of the radiolabel; (iii) in-vivo instability of the radioimmunoconjugates; (iv) excessive accumulation of activity in non-target locations; and (v) lack of radioimmunoconjugate accessibility to cells internal to a tumor mass. A careful choice of the radionuclide(s) best suited to treat the tumor under consideration is one of the most important requirements for successful radioimmunotherapy. This study evaluates copper 67 and samarium 153 for tumor radioimmunotherapy.

Srivastava, S.C.; Mausner, L.F.; Mease, R.C.; Meinken, G.E.; Joshi, V.; Kolsky, K.; Sweet, M.; Steplewski, Z.

1995-02-01

244

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

PubMed

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. PMID:24126694

Fumoto, Toshio; Ito, Masako; Ikeda, Kyoji

2014-09-01

245

Processing Techniques Developed to Fabricate Lanthanum Titanate Piezoceramic Material for High-Temperature Smart Structures  

NASA Technical Reports Server (NTRS)

Piezoelectric ceramic materials are potential candidates for use as actuators and sensors in intelligent gas turbine engines. For piezoceramics to be applied in gas turbine engines, they will have to be able to function in temperatures ranging from 1000 to 2500 F. However, the maximum use temperature for state-of-the-art piezoceramic materials is on the order of 300 to 400 F. Research activities have been initiated to develop high-temperature piezoceramic materials for gas turbine engine applications. Lanthanum titanate has been shown to have high-temperature piezoelectric properties with Curie temperatures of T(sub c) = 1500 C and use temperatures greater than 1000 C. However, the fabrication of lanthanum titanate poses serious challenges because of the very high sintering temperatures required for densification. Two different techniques have been developed at the NASA Glenn Research Center to fabricate dense lanthanum titanate piezoceramic material. In one approach, lower sintering temperatures were achieved by adding yttrium oxide to commercially available lanthanum titanate powder. Addition of only 0.1 mol% yttrium oxide lowered the sintering temperature by as much as 300 C, to just 1100 C, and dense lanthanum titanate was produced by pressure-assisted sintering. The second approach utilized the same commercially available powders but used an innovative sintering approach called differential sintering, which did not require any additive.

Goldsby, Jon C.; Farmer, Serene C.; Sayir, Ali

2004-01-01

246

Corrosion resistance and blood compatibility of lanthanum ion implanted pure iron by MEVVA  

NASA Astrophysics Data System (ADS)

Pure iron is a potential material applying for coronary artery stents based on its biocorrodible and nontoxic properties. However, the degradation characteristics of pure iron in vivo could reduce the mechanical stability of iron stents prematurely. The purpose of this work was to implant the lanthanum ion into pure iron specimens by metal vapor vacuum arc (MEVVA) source at an extracted voltage of 40 kV to improve its corrosion resistance and biocompatibility. The implanted fluence was up to 5 × 10 17 ions/cm 2. The X-ray photoelectron spectroscopy (XPS) was used to characterize the chemical state and depth profiles of La, Fe and O elements. The results showed lanthanum existed in the +3 oxidation state in the surface layer, most of the oxygen combined with lanthanum and form a layer of oxides. The lanthanum ion implantation layer could effectively hold back iron ions into the immersed solution and obviously improved the corrosion resistance of pure iron in simulated body fluids (SBF) solution by the electrochemical measurements and static immersion tests. The systematic evaluation of blood compatibility, including in vitro platelets adhesion, prothrombin time (PT), thrombin time (TT), indicated that the number of platelets adhesion, activation, aggregation and pseudopodium on the surface of the La-implanted samples were remarkably decreased compared with pure iron and 316L stainless steel, the PT and TT were almost the same as the original plasma. It was obviously showed that lanthanum ion implantation could effectively improve the corrosion resistance and blood compatibility of pure iron.

Zhu, Shengfa; Huang, Nan; Shu, Hui; Wu, Yanping; Xu, Li

2009-10-01

247

Influence of lanthanum oxide as quality promoter on cathodes for MCFC  

NASA Astrophysics Data System (ADS)

A novel material based on lithium nickel mixed oxides modified by lanthanum impregnation was investigated as an alternative cathode for molten carbonate fuel cells (MCFCs). The electrochemical behaviour of the new cathode material was evaluated in an eutectic mixture of lithium and potassium (Li:K, 62:38) at 650 °C by electrochemical impedance spectroscopy (EIS) as a function of lanthanum content, immersion time and gas composition. The impedance spectra inform on electrode structural changes during the first 100 h. The loss of lithium and the low dissolution of nickel and lanthanum are responsible of these changes. Later on, the structure reaches a stable state. The lanthanum-impregnated cathodes show higher catalytic activity for oxygen reduction and lower dissolution of nickel oxide than the lanthanum-free sample. The cathode material having 0.3 wt.% of La 2O 3 shows the best behaviour. The loss of lithium was confirmed by X-ray diffraction (XRD) and inductive coupled plasma-atomic emission spectroscopy (ICP-AES).

Escudero, M. J.; Nóvoa, X. R.; Rodrigo, T.; Daza, L.

248

Thermodynamic characteristics of lanthanum, praseodymium, neodymium, and gadolinium monobismuthides  

SciTech Connect

Investigation of the high-temperature behavior in vacuum by the Knudsen effusion method in combination with mass spectrometric, chemical, and x-ray diffraction analyses makes it possible to establish the composition of the vapor, the type of evaporation reaction, and the presence and extent of the area of homogeneity, to determine the partial pressure of the components of the vapor, and to calculate the enthalpy of the reaction and other thermodynamic characteristics related to it. In this work powders of monobismuthides of lanthanum, praseodymium, neodymium, and gadolinium obtained by ampul synthesis from the elements were used. According to the data of chemical analysis the original specimens contained (wt.%): LaBi-39.85 La, 60.05 Bi; PrBi - 40.25 Pr, 59.70 Bi; NdBi - 40.80 Nd, 59.15 Bi; GdBi - 42.93 Gd, 57.04 Bi. X-ray diffraction analysis showed that the test specimens have a NaCl-type cubic lattice with parameters of the elementary cell of a = 0.6577, 0.6460, 0.6424, and 0.6315 nm for LaBi, PrBi, NdBi, and GdBi, respectively.

Viksman, G.Sh.; Gordienko, S.P.

1987-12-01

249

The incorporation of plutonium in lanthanum zirconate pyrochlore  

NASA Astrophysics Data System (ADS)

The incorporation of plutonium (Pu) within lanthanum zirconate pyrochlore was investigated using air, argon, and N2-3.5%H2 sintering atmospheres together with Ca2+ and Sr2+ incorporation for charge compensation. The samples have been characterised in the first instance by X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectroscopy (DRS). The results show Pu can be exchanged for La3+ on the A-site with and without charge compensation and for Zr4+ on the B-site. DRS measurements were made over the wavenumber range of 4000-19,000 cm-1 and the Pu in all air- and argon-sintered samples was found to be present as Pu4+ while that in samples sintered in N2-3.5%H2 was present as Pu3+. The Pu valence was confirmed for three of the samples using X-ray near-edge absorption spectroscopy (XANES). Pu valences >4+ were not observed in any of the samples.

Gregg, Daniel J.; Zhang, Yingjie; Middleburgh, Simon C.; Conradson, Steven D.; Triani, Gerry; Lumpkin, Gregory R.; Vance, Eric R.

2013-11-01

250

Lanthanum Titanate Nanoparticles ER Fluids with High Performance  

NASA Astrophysics Data System (ADS)

A new type of electrorheological (ER) fluid consisting of lanthanum titanate (LTO) nanoparticles is developed. The ER fluids were prepared by suspending LTO powder in silicone oil and the particles were fabricated by wet chemical method. This ER fluid shows excellent ER properties: The static yield stress reaches over 150 kPa under 5 kV/mm with linear dependence on the applied DC electric field, and the current density is below 10 ?A/cm2. In order to investigate the affect factor on the ER behavior, the LTO powder were heated under different temperatures. The ER performances of two particles treated under different temperatures were compared and the composition changes for those particles were analyzed with TG-FTIR technique. It was found that the static yield stress of the suspensions fell from over 150 kPa to about 40 kPa and the current densities decreased prominently as the rise of the heating temperature. TG-FTIR analysis indicated that polar groups remained in the particles such as alkyl group, hydroxyl group and carbonyl group etc., contribute to the ER effect significantly. The experimental results are helpful to understand the mechanism of the high ER effect and to synthesize better ER materials.

Wang, De; Shen, Rong; Wei, Shiqiang; Lu, Kunquan

251

Study of prolonged administration of lanthanum carbonate in dialysis patients.  

PubMed

Data of 36 months were accumulated regarding the effects of lanthanum carbonate (LA) on serum phosphate concentrations in dialysis patients. Fifty-three patients (average age and dialysis history 58.4 years and 9.1 years) were included in this study who have been receiving outpatient treatment since March 2009, and who have been unable to maintain serum phosphate concentrations of ?6.0?mg/dL via traditional therapeutic agents used for hyperphosphatemia. Patients were given dosage of LA in addition to, or instead of, co-hyperphosphatemia treatments already being received. Mean dosages of calcium carbonate (CC) and sevelamer hydrochloride (SH) before starting LA administration were 1301.9?mg and 2462.3?mg, respectively. Dosage of LA for all cases was 750?mg at initial dose; 1528.3?mg at 5 months; and 1416.7?mg at 30 months. Dosage of other phosphate binders were 905.7?mg of CC and 820.8?mg of SH at 5 months; and 687.5?mg of CC and 1031.3?mg of SH at 30 months. Serum phosphorus levels (P levels) were significantly decreased at 1 month of LA administration, and continued until 30 months of La treatment. These results suggest that LA successfully controlled serum P and Ca concentrations simultaneously within target ranges without affecting serum intact parathyroid hormone concentration, although further long-term prospective cohort study on LA would be required. PMID:23586507

Gotoh, Junichi; Kukita, Kazutaka; Tsuchihashi, Seiichiro; Hattori, Masahiro; Iida, Junichi; Horie, Takashi; Onodera, Kazuhiko; Furui, Hidenori; Tamaki, Toru; Meguro, Junichi; Yonekawa, Motoki; Kawamura, Akio

2013-04-01

252

Fabrication of photonic crystals in rare-earth doped chalcogenide glass films for enhanced upconversion  

NASA Astrophysics Data System (ADS)

Gallium lanthanum oxysulfide (GLSO) is a promising host material for observing strong upconversion emission from trivalent rare-earth ions such as erbium (Er3+). Its attractive properties include high rare-earth solubility due to the lanthanum content of the glass former, a high refractive index (n = 2.2 at 550nm) for high radiative efficiency, and a low maximum phonon energy of approximately 425cm -1. Photonic crystals meanwhile can provide controlled light extraction, and may be capable of suppressing unwanted IR emission from lower lying metastable states. Here, we describe the fabrication of photonic crystals in annealed films of Er3+-doped GLSO deposited by RF sputtering. The most intense visible upconversion emission is observed in films annealed at 550°C, close to the bulk glass transition temperature. Hexagonal lattice photonic crystals are subsequently milled into the films using a focused ion beam (FIB). The milling parameters are optimized to produce the most vertical sidewall profile.

Pollard, M. E.; Knight, K. J.; Parker, G. J.; Hewak, D. W.; Charlton, M. D. B.

2012-02-01

253

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

PubMed

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 ClO4(-) which is an increasingly important environmental contaminant. PMID:24872208

Sankar, Sasidharan; Prajeesh, Gangadharan Puthiya Veetil; Anupama, Vijaya Nadaraja; Krishnakumar, Bhaskaran; Hareesh, Padinhattayil; Nair, Balagopal N; Warrier, Krishna Gopakumar; Hareesh, Unnikrishnan Nair Saraswathy

2014-06-30

254

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

255

The extraction of thulium, dysprosium and samarium by di(n-octyl)arsinc acid (HDOAA) in chloroform  

E-print Network

into the organic phase. The maximum E values of 33 for thulium, 15 for dysprosium and a -3 41 for samarium were observed for the 1 x 10 M chloride/1M perchlor- ate, 1 x 10 M chloride/1M nitrate, and 1 x 10 M chloride/1M sulfate systems respectively. The data.../Dy), 30909 (Sm/Tm) and 7. 5 (Dy/Tm). The separation of thulium from dysprosium can be easily achieved in the 1M sodium chloride system. In this system at a pH of 5. 1 the separation coefficient is 385 (Tm/Dy). DEDICATION To Omar Father and Mother...

El Seoud, Monica Irma

2012-06-07

256

Modification of chitosan by using samarium for potential use in drug delivery system.  

PubMed

In the presence of hydroxyl and amine groups, chitosan is highly reactive; therefore, it could be used as a carrier in drug delivery. For this study, chitosan-Sm complexes with different concentrations of samarium from 2.5 to 25 wt.% have been successfully synthesized by the impregnation method. Chitosan combined with Sm3+ ions produced a drug carrier material with fluorescence properties; thus, it could also be used as an indicator of drug release with ibuprofen (IBU) as a model drug. We evaluated the spectroscopic and interaction properties of chitosan and Sm3+ ions, the interaction of chitosan-Sm matrices with IBU as a model drug, and the effect of Sm3+ ions addition on the chitosan ability to adsorb the drug. The result showed that the hypersensitive fluorescence intensity of chitosan-Sm (2.5 wt.%) is higher than the others, even though the adsorption efficiency of chitosan-Sm 2.5wt.% is lower (29.75%) than that of chitosan-Sm 25 wt.% (33.04%). Chitosan-Sm 25 wt.% showed the highest efficiency of adsorption of ibuprofen (33.04%). In the release process of ibuprofen from the chitosan-Sm-IBU matrix, the intensity of orange fluorescent properties in the hypersensitive peak of 4G5/2?6H7/2 transition at 590 nm was observed. Fluorescent intensity increased with the cumulative amount of IBU released; therefore, the release of IBU from the Sm-modified chitosan complex can be monitored by the changes in fluorescent intensity. PMID:24177873

Kusrini, Eny; Arbianti, Rita; Sofyan, Nofrijon; Abdullah, Mohd Aidil A; Andriani, Fika

2014-01-01

257

Gene doping.  

PubMed

Together with the rapidly increasing knowledge on genetic therapies as a promising new branch of regular medicine, the issue has arisen whether these techniques might be abused in the field of sports. Previous experiences have shown that drugs that are still in the experimental phases of research may find their way into the athletic world. Both the World Anti-Doping Agency (WADA) and the International Olympic Committee (IOC) have expressed concerns about this possibility. As a result, the method of gene doping has been included in the list of prohibited classes of substances and prohibited methods. This review addresses the possible ways in which knowledge gained in the field of genetic therapies may be misused in elite sports. Many genes are readily available which may potentially have an effect on athletic performance. The sporting world will eventually be faced with the phenomena of gene doping to improve athletic performance. A combination of developing detection methods based on gene arrays or proteomics and a clear education program on the associated risks seems to be the most promising preventive method to counteract the possible application of gene doping. PMID:16572366

Haisma, H J; de Hon, O

2006-04-01

258

Synthesis and ion-exchange properties of lanthanum tungstate, a new inorganic ion exchanger  

SciTech Connect

Amorphous samples of a new inorganic ion exchanger, lanthanum tungstate, have been prepared under varying conditions. The material prepared by mixing 0.05 M lanthanum nitrate and 0.05 M sodium tungstate in a ratio of 1:2 was studied in detail for its ion-exchange capacity, chemical stability, ir, thermogravimetry, and K/sub d/ values. Its columns have been used for the separation of C/sup 2 +/ from Pd/sup 2 +/, Mn/sup 2 +/, and Cu/sup 2 +/, and Ni/sup 2 +/ from Pd/sup 2 +/. 3 figures, 4 tables.

Husain, S.W.; Rasheedzad, S.; Manzoori, J.L.; Jabbari, Y.

1982-01-01

259

Preparation of yttrium, lanthanum, cerium, and neodymium basic carbonate particles by homogeneous precipitation  

SciTech Connect

Uniform yttrium, lanthanum, cerium, and neodymium basic carbonate particles were prepared by homogeneous precipitation. Powders were characterized with respect to size, shape, crystal structure, and thermal decomposition behavior. Yttria precursor particles were spherical, monosized (0.4 {mu}m), and amorphous; whereas lanthana, neodymia, and ceria precursors were prismatic (ranging from 1 to 6 {mu}m in size) and crystalline. Crystal structure was found to be ancylite-type orthorhombic symmetry in all three cases. Upon heating in air, yttrium, lanthanum, and neodymium precursors underwent two-step decomposition to first form oxycarbonate and then oxide. Cerium hydroxycarbonate decomposed in a single step to form the oxide.

Akinc, M.; Sordelet, D. (Iowa State Univ., Ames (USA))

1987-07-01

260

Near fifty percent sodium substituted lanthanum manganites—A potential magnetic refrigerant for room temperature applications  

NASA Astrophysics Data System (ADS)

Nearly half of lanthanum sites in lanthanum manganites were substituted with monovalent ion-sodium and the compound possessed distorted orthorhombic structure. Ferromagnetic ordering at 300 K and the magnetic isotherms at different temperature ranges were analyzed for estimating magnetic entropy variation. Magnetic entropy change of 1.5 J.kg-1.K-1 was observed near 300 K. An appreciable magnetocaloric effect was also observed for a wide range of temperatures near 300 K for small magnetic field variation. Heat capacity was measured for temperatures lower than 300 K and the adiabatic temperature change increases with increase in temperature with a maximum of 0.62 K at 280 K.

Sethulakshmi, N.; Al-Omari, I. A.; Suresh, K. G.; Anantharaman, M. R.

2014-03-01

261

Enantioselective DNA condensation induced by heptameric lanthanum helical supramolecular enantiomers.  

PubMed

DNA condensation induced by a pair of heptameric La(III) helical enantiomers M-[La7(S-L)6(CO3)(NO3)6(OCH3)(CH3OH)7]·2CH3OH·5H2O and P-[La7(R-L)6(CO3)(NO3)6(OCH3)(CH3OH)5(H2O)2]·2CH3OH·4H2O (M-La and P-La, L=2-(2-hydroxybenzylamino)-3-carbamoylpropanoic acid) has been investigated by UV/vis spectroscopy, fluorescence spectroscopy, CD spectroscopy, EMSA, RALS, DLS, and SEM. The enantiomers M-La and P-La could induce CT-DNA condensation at a low concentration as observed in UV/vis spectroscopy. DNA condensates possessed globular nanoparticles with nearly homogeneous sizes in solid state determined by SEM (ca. 250 nm for M-La and ca. 200 nm for P-La). The enantiomers bound to DNA through electrostatic attraction and hydrogen bond interactions in a major groove, and rapidly condensed free DNA into its compact state. DNA decompaction has been acquired by using EDTA as disassembly agent, and analyzed by UV/vis spectroscopy, CD spectroscopy and EMSA. Moreover, the enantiomers M-La and P-La displayed discernible discrimination in DNA interaction and DNA condensation, as well as DNA decondensation. Our study suggested that lanthanum(III) enantiomers M-La and P-La were efficient DNA packaging agents with potential applications in gene delivery. PMID:24915440

Bao, Fei-Fei; Xu, Xin-Xin; Zhou, Wen; Pang, Chun-Yan; Li, Zaijun; Gu, Zhi-Guo

2014-09-01

262

A new large area lanthanum hexaboride plasma source  

NASA Astrophysics Data System (ADS)

A new 18×18 cm2 active area lanthanum hexaboride (LaB6) plasma source for use in a dc discharge has been developed at UCLA. The cathode consists of four tiled LaB6 pieces indirectly heated to electron emission (1750 °C) by a graphite heater. A molybdenum mesh anode 33 cm in front of the LaB6 accelerates the electrons, ionizing a fill gas to create a 20×20 cm2 nearly square plasma. The source is run in pulsed operation with the anode biased up to +400 V dc with respect to the cathode for up to 100 ms at a 1 Hz repetition rate. Both the cathode and anode "float" electrically with respect to the chamber walls. The source is placed in a toroidal chamber 2 m wide and 3 m tall with a major radius of 5 m. Toroidal and vertical magnetic fields confine the current-free plasma which follows the field in a helix. The plasma starts on the bottom of the machine and spirals around it up to four times (120 m) and can be configured to terminate either on the top wall or on the neutral gas itself. The source typically operates with a discharge current up to 250 A in helium making plasmas with Te<30 eV, Ti<16 eV, and ne<3×1013 cm-3 in a background field of 100 G

Cooper, C. M.; Gekelman, W.; Pribyl, P.; Lucky, Z.

2010-08-01

263

Titania-lanthanum phosphate photoactive and hydrophobic new generation catalyst  

NASA Astrophysics Data System (ADS)

Titania-lanthanum phosphate nanocomposites with multifunctional properties have been synthesized by aqueous sol-gel method. The precursor sols with varying TiO 2:LaPO 4 ratios were applied as thin coating on glass substrates in order to be transparent, hydrophobic, photocatalytically active coatings. The phase compositions of the composite powders were identified by powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The anatase phase of TiO 2 in TiO 2-LaPO 4 composite precursors was found to be stable even on annealing at 800 °C. The glass substrates, coated with TL1 (TiO 2-LaPO 4 composition with 1 mol% LaPO 4) and TL50 (composite precursor containing TiO 2 and LaPO 4 with molar ratio 1:1) sols and annealed at 400 °C, produced contact angles of 74° and 92°, respectively, though it is only 62° for pure TiO 2 coating. The glass substrates, coated with TL50 sol, produced surfaces with relatively high roughness and uneven morphology. The TL1 material, annealed at 800 °C, has shown the highest UV photoactivity with an apparent rate constant, kapp=24×10 -3 min -1, which is over five times higher than that observed with standard Hombikat UV 100 ( kapp=4×10 -3 min -1). The photoactivity combined with a moderate contact angle (85.3°) shows that this material has a promise as an efficient self-cleaning precursor.

Jyothi, Chembolli K.; Jaimy, Kanakkanmavudi B.; Ghosh, Swapankumar; Sankar, Sasidharan; Smitha, V. S.; Warrier, K. G. K.

2011-07-01

264

Lanthanum lead oxide hydroxide nitrates with a nonlinear optical effect.  

PubMed

Two new lanthanum lead oxide hydroxide nitrates with acentric structure, [LaPb8O(OH)10(H2O)](NO3)7 (1) and [LaPb8O(OH)10(H2O)](NO3)7·2H2O (2), have been prepared under subcritical hydrothermal conditions and crystallize in the space groups of Cc and P212121, respectively. The crystal structure of compound 1 consists of the novel [LaPb8O(OH)10(H2O)](7+) clusters regularly arranged along the ab plane with nitrate ions as the counterions around the clusters by Pb-O bonds, developing into a three-dimensional net framework, while the structure of compound 2 is composed of [LaPb8O(OH)10(H2O)](7+) clusters and [NO3](-) groups as the bridging groups, forming a three-dimensional net framework with crystallized water molecules filling in the gaps. The experiments confirmed that compound 1 is the residue of compound 2 after efflorenscence. Besides, the [LaPb8O(OH)10(H2O)](7+) clusters present mirror symmetry in structures of the two compounds. The second-harmonic-generation (SHG) measurements for the two nitrates indicate that the SHG responses for compounds 1 and 2 are 1.3 and 1.1 times that of KH2PO4, respectively. Theoretical calculations confirmed that the SHG efficiency of compounds 1 and 2 mainly arises from the NO3(-) groups in the structure. PMID:25385570

Wang, Genxiang; Luo, Min; Lin, Chensheng; Ye, Ning; Zhou, Yuqiao; Cheng, Wendan

2014-12-01

265

Preparation and Quality Control of the [153Sm]-Samarium Maltolate Complex as a Lanthanide Mobilization Product in Rats  

PubMed Central

Development of lanthanide detoxification agents and protocols is of great importance in management of overdoses. Due to safety of maltol as a detoxifying agent in metal overloads, it can be used as a lanthanide detoxifying agent. In order to demonstrate the biodistribution of final complex, [153Sm]-samarium maltolate was prepared using Sm-153 chloride (radiochemical purity >99.9%; ITLC and specific activity). The stability of the labeled compound was determined in the final solution up to 24h as well as the partition coefficient. Biodistribution studies of Sm-153 chloride, [153Sm]-samarium maltolate were carried out in wild-type rats comparing the critical organ uptakes. Comparative study for Sm3+ cation and the labeled compound was conducted up to 48 h, demonstrating a more rapid wash out for the labeled compound. The effective and biological half lives of 2.3 h and 2.46h were calculated for the complex. The data suggest the detoxification property of maltol formulation for lanthanide overdoses. PMID:21773065

Naseri, Zohreh; Hakimi, Amir; Jalilian, Amir R.; Nemati Kharat, Ali; Bahrami-Samani, Ali; Ghannadi-Maragheh, Mohammad

2011-01-01

266

Valence transition of samarium in hexaboride solid solutions Sm1-xMxB6 (M = Yb2+ , Sr2+ , La3+ , Y3+ , Th4+)  

E-print Network

measurements. J. Physique 41 (1980) 1135-1140 OCTOBRE 1980, Classification Physics Abstracts 78.70D SmB6 occupation of the rare earth ion 4f shell. Thus, SmB6 is a homogeneous mixed-valence com- pound having 4f samarium valence in SmB6. Two kinds of substitution seemed interesting to study : 1) the influence

Boyer, Edmond

267

Influence of samaria doping on the resistance of ceria thin films and its implications to the planar oxygen sensing devices  

SciTech Connect

In order to evaluate and analyze the effect of samarium (Sm) doping on the resistance of cerium oxide, we have grown highly oriented samaria doped ceria (SDC) thin films on sapphire, Al2O3 (0001) substrates by using oxygen plasma-assisted molecular beam epitaxy (OPA-MBE). The film growth was monitored using reflection high-energy electron diffraction (RHEED) which shows two-dimensional growth throughout the deposition. Following growth, the thin films were characterized by X-ray photoelectron spectroscopy (XPS), high-resolution X-ray diffraction (HRXRD), and Rutherford backscattering spectrometry (RBS). XPS depth-profile shows Sm atoms are uniformly distributed in ceria lattice throughout the bulk of the film. The valence states of Ce and Sm in doped thin films are found to be Ce4+ and Sm3+, respectively. HRXRD shows the samaria doped ceria films on Al2O3(0001) exhibit (111) preferred orientation. Ion-channeling in RBS measurements confirms high quality of the thin films. The resistance of the samaria doped ceria films, obtained by two probe measurement capability under various oxygen pressure (1mTorr-100Torr) and temperatures (623K to 973K), is significantly lower than that of pure ceria under same conditions. The 6Sm% doped ceria film is the optimum composition for highest conductivity. This is attributed to the increased oxygen vacant sites in fluorite crystal structure of the epitaxial thin films which facilitate faster oxygen diffusion through hopping process.

Gupta, Shilpi; Kuchibhatla, Satyanarayana V N T; Engelhard, Mark H.; Shutthanandan, V.; Nachimuthu, Ponnusamy; Jiang, Weilin; Saraf, Laxmikant V.; Thevuthasan, Suntharampillai; Prasad, Shalini

2009-05-27

268

Nonisothermal Thermal Decomposition Reaction Kinetics of Double-base Propellant Catalyzed with Lanthanum Citrate  

Microsoft Academic Search

The decomposition reaction kinetics of the double-base (DB) rocket propellant composed of the mixed ester of triethyleneglycol dinitrate (TEGDN) and nitroglycerin (NG), and nitrocellulose (NC) with lanthanum citrate as a combustion catalyst was investigated by thermogravimetry and differential thermogravimetry (TG-DTG), and differential scanning calorimetry (DSC) under atmospheric pressure and flowing nitrogen gas conditions. The results showed that the thermal decomposition

Jianhua Yi; Fengqi Zhao; Siyu Xu; Hongxu Gao; Rongzu Hu; Haixia Hao; Qing Pei; Yin Gao

2007-01-01

269

Oxidation of Carbon in the Presence of Catalysts Based on Cesium Lanthanum Vanadate  

Microsoft Academic Search

Some kinetic aspects of the catalytic oxidation of carbon with atmospheric oxygen and nitrogen oxide NO in the presence of catalysts based of cesium lanthanum vanadate were studied. The influence exerted by a promoter, cesium sulfate, and its content on the course of catalytic reactions was analyzed.

A. A. Ostroushko; A. M. Makarov; V. I. Minyaev

2004-01-01

270

The blood-nerve barrier: an in vivo lanthanum tracer study.  

PubMed

The permeability of the blood-nerve barrier was investigated using ionic lanthanum as an electron-dense tracer. The rat sural nerve was microinjected in vivo with lanthanum nitrate solution either into the endoneurial space or into the epineurium. Five to sixty minutes after injection the sural nerves were fixed by vascular perfusion or immersion. Using electron microscopy, lanthanum tracer was observed to be associated with endoneurial vessels in the perivascular spaces, in the inter-endothelial clefts and within the lumina. Furthermore, tracer was present in the spaces between adjacent endothelial cell layers and within vesicles and caveolae of endothelial cells. Epineurial vessels showed a similar distribution of tracer deposits but in greater quantities in inter-endothelial cell spaces and vessel lumina. The results are considered to demonstrate an absence of a blood-nerve barrier to ions as exemplified by lanthanum and are compatible with data from physiological experiments. The blood-nerve and blood-brain barriers are contrasted in their permeability to ions, their related fine structure and their physiological roles. PMID:3446663

MacKenzie, M L; Ghabriel, M N; Allt, G

1987-10-01

271

Al NMR study of the structure of lanthanum and yttrium based aluminosilicate glasses and melts  

E-print Network

A 27 Al NMR study of the structure of lanthanum and yttrium based aluminosilicate glasses and melts allowed to follow selected samples from 2200°C down to 1700°C and hence to characterize the aluminum of glasses has a large range of applications in modern technology like (a) host materials for laser, optical

Paris-Sud XI, Université de

272

Modeling of Lanthanum Strontium Manganite Ferromagnetic Thin Film Material Tunable Resistance  

Microsoft Academic Search

The knowledge of the electroactive and magnetoactive properties of the lanthanum strontium manganite (LSMO) ferromagnetic thin film materials is essential for modeling and design of their devices. The activity of these materials can be described by their electro- and magnetoresistances. Under electrostatic bias field, it is assumed that induced electric current will modify the electrical behavior of the electrode-manganite interface,

M. Al Ahmad; Eui-Jung Yun; Robert Plana

2008-01-01

273

Structural characterization and properties of lanthanum film as chromate replacement for tinplate  

NASA Astrophysics Data System (ADS)

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 2O 3 and its hydrates such as La(OH) 3 and LaOOH. The amount of lanthanum in the film is about 0.0409 g/m 2.

Huang, Xingqiao; Li, Ning

2007-12-01

274

Development and reversibility of impaired mineralization associated with lanthanum carbonate treatment in chronic renal failure rats  

Microsoft Academic Search

BackgroundWe have previously shown that administration of the new phosphate binder lanthanum (La) carbonate at high doses during 12 weeks induces a mineralization defect (MD) in chronic renal failure (CRF) rats most likely due to the powerful phosphate binding. In this study, we want to investigate the fate and possible biological activities of La once it is accumulated in bone.

An R. J. Bervoets; Line Oste; Geert J. Behets; Geert Dams; Ronny Blust; Rita Marynissen; Hilde Geryl; Marc E. De Broe; Patrick C. D'Haese

2006-01-01

275

Comparative evaluation of the in vitro efficacy of lanthanum carbonate chewable tablets.  

PubMed

The aims of this study were to systematically evaluate the effects of pH levels, phosphate concentrations, and tablet integrity on the phosphate binding profiles of lanthanum carbonate chewable tablets, and to compare the in vitro phosphate binding efficacy of one reference and two test products of lanthanum carbonate chewable tablets. Langmuir equation was utilized to calculate the binding constants k1 and k2 . The phosphate binding to the tablets of lanthanum carbonate product was pH dependent, with a faster binding rate at low pH. The crushed tablets bind phosphate more rapid. Compared with the whole tablets, the kinetic binding profiles from the crushed tablets were less variable under all conditions for both test and reference products. The phosphate level has a significant impact on the phosphate binding for both whole and crushed tablets under all pH conditions, with more binding at higher phosphate concentration. The phosphate binding profiles displayed significant difference among the products. For a crushed tablet, the phosphate binding to lanthanum reached equilibrium within 8 h under all conditions. The 90% confidence interval for the k2 ratio (test/reference) was well within the 80%-125% under all pH conditions. However, the k1 ratio varies from 54% to 144%. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1370-1381, 2013. PMID:23334989

Yang, Yongsheng; Bykadi, Srikant; Carlin, Alan S; Shah, Rakhi B; Yu, Lawrence X; Khan, Mansoor A

2013-04-01

276

First-principles study of the solid solution of hydrogen in lanthanum  

NASA Astrophysics Data System (ADS)

Results from first-principles investigations of the energetical, structural, electronic, and vibrational properties of model structures probing the metal-rich region of the lanthanum-hydrogen system, i.e., the region of the solid solution of hydrogen in lanthanum, are presented. We have studied the site preference and the ordering tendency of hydrogen atoms interstitially bonded in close-packed lanthanum. Spatially separated hydrogen atoms have turned out to exhibit an energetical preference for the occupation of octahedral interstitial sites at low temperature. Indications for a reversal of the site preference in favor of the occupation of tetrahedral interstitial sites at elevated temperature have been found. Linear arrangements consisting of pairs of octahedrally and/or tetrahedrally coordinated hydrogen atoms collinearly bonded to a central lanthanum atom have turned out to be energetically favorable structure elements. Further stabilization is achieved if such hydrogen pairs are in turn linked together so that extended chains of La-H bonds are formed. Pair formation and chain linking counteract the energetical preference for octahedral coordination observed for separated hydrogen atoms.

Schöllhammer, Gunther; Herzig, Peter; Wolf, Walter; Vajda, Peter; Yvon, Klaus

2011-09-01

277

Spectral investigations of Sm3+ doped lead bismuth magnesium borophosphate glasses  

NASA Astrophysics Data System (ADS)

The multicomponent lead bismuth magnesium borophosphate glass systems (LBMBPS) doped with Samarium ions with the molar compositions of (50-x)PbO?xBi2O3?25MgHPO4?24B2O3?1Sm2O3 (where x=10, 20, 30, and 40) were fabricated using conventional melt quenching technique. The amorphous nature of these glass samples was confirmed with XRD studies. The spectral data from the optical absorption studies were employed to compute various spectroscopic parameters such as Judd-Ofelt intensity parameters. The Judd-Ofelt parameterization employed reflects the covalency and vibration frequencies of the ligands with Samarium ions. The radiative parameters such as radiative transition probabilities (A), the total radiative transitional probabilities (AT), radiative life times (?R), branching ratios (?) and absorption cross sections (?) were computed for certain lasing levels. The glass systems thus developed indicate their potential lasing candidature. The emission cross sections (?E) for the significant lasing transitions 4G5/2?6H5/2, 4G5/2?6H7/2, and 4G5/2?6H9/2 evaluated from the photoluminescence spectra were reported. The radiative properties obtained in our investigations suggest their lasing candidature.

Ravi Babu, Y. N. Ch.; Sree Ram Naik, P.; Vijaya Kumar, K.; Rajesh Kumar, N.; Suresh Kumar, A.

2012-09-01

278

REFOS study: efficacy and safety of lanthanum carbonate in clinical practice in Spain.  

PubMed

Lanthanum carbonate is a powerful phosphate binder that has shown efficacy and safety in clinical trials for hyperphosphataemia management, although there are few data in regular clinical practice. The study's objective was to evaluate, in regular clinical practice, its efficacy and safety in patients on dialysis. We retrospectively collected data from 15 months of monitoring, corresponding to 3 months prior to the start of treatment with lanthanum carbonate until 12 months after the start. Results included values of serum calcium, phosphorus, alkaline phosphatase, iPTH, hepatic enzymes and haemogram, as well as the daily-prescribed dose of lanthanum carbonate, the concomitant medication, treatment compliance and adverse events. 647 patients were included of which 522 completed the study. Abandonment, for the most part, was due to gastrointestinal disorders (26%) and hypophosphatemia (19%). Serum phosphorus decreased from 6.4±1.7 mg/dl (start) to 4.9±1.4 mg/dl (12 months) (P<.001). At the end of the monitoring period, 47% were within the desired phosphorus range (3.5-5mg/dl). There were no significant variations in the remaining parameters. Initial dose of lanthanum carbonate: 1900 mg/day; and end dose: 2300 mg/day. The variables independently associated with phosphataemia were baseline serum phosphorus and treatment compliance. In relation to safety, we observed 238 slight or moderate adverse effects in 117 patients, with 88% linked to gastrointestinal abnormalities. In conclusion, lanthanum carbonate reduces the serum phosphorus values in patients on dialysis with a good safety profile and acceptable adherence to that profile, with gastrointestinal disorders being the most frequent adverse effect. PMID:24849057

Torregrosa, José-Vicente; González-Parra, Emilio; González, M Teresa; Cannata-Andía, Jorge

2014-05-21

279

Interstitial doping and oxygen exchange in superconducting La 2CuO 4+ ?  

NASA Astrophysics Data System (ADS)

The oxygen doping of lanthanum cuprate to generate superconductiving La 2CuO 4+ ? (0

Shinn, N. D.; Bartram, M. E.; Schirber, J. E.; Rogers, J. W.; Overmyer, D. L.; Fisk, Z.; Cheong, S.-W.

1991-09-01

280

Combustion synthesis and photoluminescence of Eu3+ doped LaAlO3 nanophosphors  

NASA Astrophysics Data System (ADS)

Eu3+ doped LaAlO3 nanophosphors were successfully synthesized by a combustion process using concentrated solution of lanthanum nitrates and aluminate as oxidiser, and glycine acid as fuel. The powders were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence spectroscopy. Pure LaAlO3 phase was obtained at 800 °C heated for 4 h, without formation of any intermediate phase, with an average crystal size, as determined by TEM, of 60 nm. Intense photoluminescence emission is reported at 616 nm, allowing the use of this material as red phosphor.

Dhahri, A.; Horchani-Naifer, K.; Benedetti, A.; Enrichi, F.; Ferid, M.

2012-09-01

281

Performance Evaluation of an Oxygen Sensor as a Function of the Samaria Doped Ceria Film Thickness  

SciTech Connect

The current demand in the automobile industry is in the control of air-fuel mixture in the combustion engine of automobiles. Oxygen partial pressure can be used as an input parameter for regulating or controlling systems in order to optimize the combustion process. Our goal is to identify and optimize the material system that would potentially function as the active sensing material for such a device that monitors oxygen partial pressure in these systems. We have used thin film samaria doped ceria (SDC) as the sensing material for the sensor operation, exploiting the fact that at high temperatures, oxygen vacancies generated due to samarium doping act as conducting medium for oxygen ions which hop through the vacancies from one side to the other contributing to an electrical signal. We have recently established that 6 atom % Sm doping in ceria films has optimum conductivity. Based on this observation, we have studied the variation in the overall conductivity of 6 atom % samaria doped ceria thin films as a function of thickness in the range of 50 nm to 300 nm at a fixed bias voltage of 2 volts. A direct proportionality in the increase in the overall conductivity is observed with the increase in sensing film thickness. For a range of oxygen pressure values from 1 mTorr to 100 Torr, a tolerable hysteresis error, good dynamic response and a response time of less than 10 seconds was observed

Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Nachimuthu, Ponnusamy; Engelhard, Mark H.; Shutthanandan, V.; Jiang, Weilin; Thevuthasan, Suntharampillai; Kayani, Asghar N.; Prasad, Shalini

2010-12-01

282

Thickness Dependency of Thin Film Samaria Doped Ceria for Oxygen Sensing  

SciTech Connect

High temperature oxygen sensors are widely used for exhaust gas monitoring in automobiles. This particular study explores the use of thin film single crystalline samaria doped ceria as the oxygen sensing material. Desired signal to noise ratio can be achieved in a material system with high conductivity. From previous studies it is established that 6 atomic percent samarium doping is the optimum concentration for thin film samaria doped ceria to achieve high ionic conductivity. In this study, the conductivity of the 6 atomic percent samaria doped ceria thin film is measured as a function of the sensing film thickness. Hysteresis and dynamic response of this sensing platform is tested for a range of oxygen pressures from 0.001 Torr to 100 Torr for temperatures above 673 K. An attempt has been made to understand the physics behind the thickness dependent conductivity behavior of this sensing platform by developing a hypothetical operating model and through COMSOL simulations. This study can be used to identify the parameters required to construct a fast, reliable and compact high temperature oxygen sensor.

Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Jiang, Weilin; Varga, Tamas; Nachimuthu, Ponnusamy; Engelhard, Mark H.; Shutthanandan, V.; Thevuthasan, Suntharampillai; Kayani, Asghar N.; Prasad, Shalini

2011-01-01

283

Self-magnetic compensation and shifted hysteresis loops in ferromagnetic samarium systems  

NASA Astrophysics Data System (ADS)

For Sm3+ ions in a vast majority of metallic systems, the following interesting scenario has been conjured up for long, namely, a magnetic lattice of tiny self- (spin-orbital) compensated 4f -moments exchange coupled (and phase reversed) to the polarization in the conduction band. We report here the identification of a self-compensation behavior in a variety of ferromagnetic Sm intermetallics via the fingerprint of a shift in the magnetic hysteresis (M-H) loop from the origin. Such an attribute, designated as exchange bias in the context of ferromagnetic/antiferromagnetic multilayers, accords these compounds a potential for niche applications in spintronics. We also present results on magnetic compensation behavior on small Gd doping (2.5at.%) in one of the Sm ferromagnets (viz., SmCu4Pd ). The doped system responds like a pseudoferrimagnet and it displays a characteristic left-shifted linear M-H plot for an antiferromagnet.

Kulkarni, P. D.; Dhar, S. K.; Provino, A.; Manfrinetti, P.; Grover, A. K.

2010-10-01

284

Effects of potassium, lanthanum and black widow spider venom on miniature synaptic potentials in the Torpedo electroplax  

Microsoft Academic Search

Using a method of focal drug application it is demonstrated that high potassium concentration, lanthanum, and black widow spider venom accelerate spontaneous transmitter release inTorpedo electric tissue.

Christian Walther; Fachbereich Biologie; UniversitKt Konstanz

1974-01-01

285

The Cost-Effectiveness of Lanthanum Carbonate in the Treatment of Hyperphosphatemia in Patients with End-Stage Renal Disease  

Microsoft Academic Search

ObjectivesTo assess the cost-effectiveness of lanthanum carbonate (LC) as a second-line therapy for hyperphosphatemia in end-stage renal disease (ESRD) patients not achieving target phosphorus levels.

Alan Brennan; Ron Akehurst; Sarah Davis; Hana Sakai; Victoria Abbott

2007-01-01

286

A multicenter study on the effects of lanthanum carbonate (Fosrenol™) and calcium carbonate on renal bone disease in dialysis patients  

Microsoft Academic Search

A multicenter study on the affects of lanthanum carbonate (Fosrenol™) and calcium carbonate on renal bone disease in dialysis patients.BackgroundLanthanum carbonate (LC) (Fosrenol™) is a novel new treatment for hyperphosphatemia. In this phase III, open-label study, we compared the effects of LC and calcium carbonate (CC) on the evolution of renal osteodystrophy (ROD) in dialysis patients.MethodsNinety-eight patients were randomized to

Patrick C. D'Haese; Goce B. Spasovski; Aleksander Sikole; Alastair Hutchison; Tony J. Freemont; Sylvie Sulkova; Charles Swanepoel; Svetlana Pejanovic; Llubica Djukanovic; Alessandro Balducci; Giorgio Coen; Waldysaw Sulowicz; Anibal Ferreira; Armando Torres; Slobodan Curic; Milan Popovic; Nada Dimkovic; Marc E. De Broe

2003-01-01

287

Measurement of hold-up times in a thermal ion source for metallic and monoxide ions of lanthanum and cerium  

Microsoft Academic Search

Hold-up times of ions in a thermal ion source were measured for lanthanum and cerium together with neighboring elements in the periodic table. The hold-up times of metallic and monoxide ions of both lanthanum and cerium were found to be almost the same and much longer than those of cesium, barium, praseodymium and neodymium ions. The observed long hold-up times

S. Ichikawa; T. Sekine; H. Iimura; M. Oshima

1992-01-01

288

Formation and characterization of porous silicon-samarium/gadolinium nanocomposites: effect of substrate oxidation and biosynthesis process  

NASA Astrophysics Data System (ADS)

Samarium and gadolinium nanoparticles synthesized by bioreduction process have been incorporated into nanostructured porous silicon template to form a nanocomposite. The structural and optical properties of PS-Gd and PS-Sm nanocomposites have been studied through TEM, SEM and UV-Vis spectroscopy. Extent of infiltration has been verified through reflectance interference Fourier transform spectroscopy as a function of substrate oxidation conditions. The substrates oxidized at 600 °C showed the maximum infiltration and the corresponding change of optical thickness due to nanoparticles. Such biodegradable nanocomposites in the form of particles can have potential applications in localized drug delivery and enhancement of the image contrast and optoelectronic devices. The results here reported open an energy-cheap procedure to take advantages of small rare earth nanoparticles and produced nanocomposites with their immersion in SiO2 substrates, with the perspective to be replied in other similar substrates under controlled conditions.

Perdigon-Lagunes, P.; Ascencio, J. A.; Agarwal, V.

2014-08-01

289

Concentration dependence of the structure of aqueous solutions of samarium trichloride according to X-ray diffraction  

NASA Astrophysics Data System (ADS)

Aqueous solutions of samarium chloride in a wide range of concentration under ambient conditions are studied by X-ray diffraction analysis. The small-angle peaks in experimental scattering intensity curves are interpreted. It is shown that highly concentrated solutions are characterized by a unique structure that differs heavily from the structure of dilute systems. It is found that small-angle peaks also appear in the intensity curves of dilute solutions, indicating that the so-called long-range order is preserved in these solutions. It is revealed that the contributions to the total scattering pattern that govern the appearance of prepeaks are interionic interactions of different types (e.g., cation-cation, anion-cation, and anion-anion interactions) in concentrated systems and the distances between the cations in dilute solutions.

Smirnov, P. R.; Grechin, O. V.; Trostin, V. N.

2013-05-01

290

Fluorescence properties and electron paramagnetic resonance studies of ?-irradiated Sm3+-doped oxyfluoroborate glasses  

NASA Astrophysics Data System (ADS)

The permanent photoinduced valence manipulation of samarium doped oxyfluoroborate glasses as a function of ?-ray irradiation has been investigated using a steady-state fluorescence and electron paramagnetic resonance techniques. An increase in SrF2 content in the glass led to the red shift of the peaks in as prepared glass, while in irradiated glasses this led to the decrease in defect formation as well as increase in photoreduction of Sm3+ to Sm2+ ion. The energy transfer mechanism of induced permanent photoreduction of Sm3+ to Sm2+ ions in oxyfluoroborate glasses has been discussed. The decay analysis shows exponential behavior before irradiation and non-exponential behavior after irradiation. The energy transfer in irradiated glasses increases with the increase in SrF2 content in the glass and also with the irradiation dose.

Babu, B. Hari; Ravi Kanth Kumar, V. V.

2012-11-01

291

Photoluminescence enhancement and quenching of Sm, Au Co-doped TiO2  

NASA Astrophysics Data System (ADS)

In this study, a novel hybrid nanostructure for enhancing photoluminescence (PL) was prepared by doping samarium (Sm) and gold (Au) into titania (TiO2:Sm3+:Au) via a simple sol-gel method. The X-ray diffraction and PL results indicate that the sample with better crystallinity has better emitting performance. The dependence of the PL intensity was examined as a function of the concentration of Au nanoparticles (NPs) while keeping the Sm content constant at 2%. It is found that PL enhancement and quenching can be obtained by tuning the content of Au NPs. The PL results suggest that the PL emission of this hybrid system relies on the energy (emitting light) transferred from TiO2:Sm3+ to Au NPs. The plasmon state around Au NPs can be excited to bring out PL enhancement only when the intensity of the transferred energy meets the requirement of Au NPs.

An, Guofei; Jin, Shaohu; Yang, Chaoshun; Zhou, Yawei; Zhao, Xiaopeng

2012-11-01

292

Sensitive and reliable ascorbic Acid sensing by lanthanum oxide/reduced graphene oxide nanocomposite.  

PubMed

A simple strategy for the detection and estimation of ascorbic acid (AA), using lanthanum oxide-reduced graphene oxide nanocomposite (LO/RGO) on indium tin oxide (ITO) substrate, is reported. LO/RGO displays high catalytic activity toward the oxidation of AA, and the synergism between lanthanum oxide and reduced graphene oxide was attributed to the successful and efficient detection. Detection mechanism and sensing efficacy of LO/RGO nanocomposite are investigated by electrochemical techniques. Chronoamperometric results under optimal conditions show a linear response range from 14 to 100 ?M for AA detection. Commercially available vitamin C tablets were also analyzed using the proposed LO/RGO sensor, and the remarkable recovery percentage (97.64-99.7) shows the potential application in AA detection. PMID:24879601

Mogha, Navin Kumar; Sahu, Vikrant; Sharma, Meenakshi; Sharma, Raj Kishore; Masram, Dhanraj T

2014-10-01

293

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

SciTech Connect

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.

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

2011-05-01

294

Density functional theory characterization of lanthanum nitride endohedral fullerene: La3N@C92  

NASA Astrophysics Data System (ADS)

Systemic investigations on lanthanum nitride endohedral metallofullerene La3N@C92 are carried out by a hybrid density functional theory technique combined with statistical mechanics treatment. A novel isolated-pentagon-rule (IPR) isomer with C2 symmetry is determined as the most suitable host cage for the encapsulation of La3N with the lowest energy and predominant thermodynamic stability related to fullerene formation. Natural electron configuration analyses reveal that electron transfer between the La3N cluster and C92 cage is mainly contributed by the 6s orbital of lanthanum atoms. The present work may supply some information reliable for synthesis and experimental characterization of large trimetallic nitride endohedral fullerenes.

Zheng, Jiajia; Zhao, Xiang; Dang, Jingshuang; Chen, Yongmei; Xu, Qian; Wang, Weiwei

2011-09-01

295

Ca2+-Doped CeBr3 Scintillating Materials  

SciTech Connect

Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide, their commercial availability and application are limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. This investigation employed aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was used as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were studied using the density functional theory within the generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

Guss, Paul [NSTec; Foster, Michael E. [SNL; Wong, Bryan M. [SNL; Doty, F. Patrick [SNL; Shah, Kanai [RMD; Squillante, Michael R. [RMD; Shirwadkar, Urmila [RMD; Hawrami, Rastgo [RMD; Tower, Josh [RMD; Yuan, Ding [NSTec

2014-01-01

296

Synergistic Effects of Lanthanum Oxide on Magnesium Hydroxide Flame-Retarded Ethylene Propylene Diene Terpolymer Composite  

Microsoft Academic Search

New halogen-free, magnesium hydroxide (MH) flame retarded ethylene propylene diene terpolymer (EPDM) composites have been prepared via melt blending method, using lanthanum oxide (La2O3) as a synergistic agent. Influence of La2O3 on the flame method retardancy and thermal stability of the flame retarded EPDM composites are investigated by limiting oxygen index (LOI), UL94 testing, cone calorimeter and thermogravimetric analysis (TG),

Lei Song; Shun Zhou; Jing Wu; Yuan Hu

2009-01-01

297

Effective Removal of Arsenic with Lanthanum(III)- and Cerium(III)-loaded Orange Waste Gels  

Microsoft Academic Search

Orange waste has been chemically modified and loaded with lanthanum(III) and\\/or cerium(III) to examine its adsorption behavior to both As(V) and As(III). Arsenate removal was found to be favored over a pH range of 6 ? 9.5 while arsenite removal took place at pH values ranging from 9 to 11. The maximum sorption capacity of the gel for As(III) removal was evaluated

Biplob Kumar Biswas; Katsutoshi Inoue; Kedar Nath Ghimire; Hidetaka Kawakita; Keisuke Ohto; Hiroyuki Harada

2008-01-01

298

Room temperature synthesis of high temperature stable lanthanum phosphate–yttria nano composite  

SciTech Connect

Graphical abstract: A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Highlights: ? A novel lanthanum phosphate–Y{sub 2}O{sub 3} nano composite is synthesized for the first time using a modified facile sol gel process. ? The composite becomes crystalline at 600 °C and X-ray diffraction pattern is indexed for monoclinic LaPO{sub 4} and cubic yttria. ? The composite synthesized was tested up to 1300 °C and no reaction between the phases of the constituents is observed with the morphologies of the phases being retained. -- Abstract: A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Lanthanum phosphate (80 wt%)–yttria (20 wt%) nano composite (LaPO{sub 4}–20%Y{sub 2}O{sub 3}), has an average particle size of ?70 nm after heat treatment of precursor at 600 °C. TG–DTA analysis reveals that stable phase of the composite is formed on heating the precursor at 600 °C. The TEM images of the composite show rod shape morphology of LaPO{sub 4} in which yttria is acquiring near spherical shape. Phase identification of the composite as well as the phase stability up to 1300 °C was carried out using X-ray diffraction technique. With the phases being stable at higher temperatures, the composite synthesized should be a potential material for high temperature applications like thermal barrier coatings and metal melting applications.

Sankar, Sasidharan; Raj, Athira N.; Jyothi, C.K. [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India)] [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India); Warrier, K.G.K., E-mail: wwarrierkgk@yahoo.co.in [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India)] [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India); Padmanabhan, P.V.A. [Bhabha Atomic Research Centre, Mumbai 400085 (India)] [Bhabha Atomic Research Centre, Mumbai 400085 (India)

2012-07-15

299

Surface structural investigations on (100) and (110) faces of flux-grown lanthanum borate crystals  

Microsoft Academic Search

Results of topographical studies carried out on (100) and (110) faces of lanthanum borate crystals grown from the PbO-B2O3 flux system are illustrated and discussed. The habit faces display the formation of cavities, microcrystals, elliptical etch pits, elliptical hillocks, circular hillocks and irregular structures. Also described are a various number of elevated structures identified as impurity phases. Energy dispersive X-ray

P. N. Kotru; Anima Jain; Ashok K. Razdan; B. M. Wanklyn

1989-01-01

300

Surface structural investigations on (100) and (110) faces of flux-grown lanthanum borate crystals  

Microsoft Academic Search

Results of topographical studies carried out on (100) and (110) faces of lanthanum borate crystals grown from the PbO-B2O3 flux system are illustrated and discussed. The habit faces display the formation of cavities, microcrystals, elliptical etch\\u000a pits, elliptical hillocks, circular hillocks and irregular structures. Also described are a various number of elevated structures\\u000a identified as impurity phases. Energy dispersive X-ray

P. N. Kotru; Anima Jain; Ashok K. Razdan; B. M. Wanklyn

1989-01-01

301

A nuclear magnetic resonance study of amorphous and crystalline lanthanum-aluminates  

Microsoft Academic Search

Lanthanum-aluminates of the composition (1 - x)AlâOâ·xLaâOâ (0 < x < 0.7) were prepared by sol-gel synthesis. Subsequent heat-treatment temperatures ranging from 200 to 1,200 C were applied. The resulting samples were characterized by X-ray powder diffraction and ²⁷Al MAS NMR. The most complex spectra were analyzed by MQMAS NMR in order to get insight in the number of sites

D. Iuga; S. Simon; E. de Boer; A. P. M. Kentgens

1999-01-01

302

Chromium and copper substituted lanthanum nano-ferrites: Their synthesis, characterization and application studies  

NASA Astrophysics Data System (ADS)

Nano-crystalline lanthanum ferrites substituted by chromium and copper having formula LaMxFe1-xO3 (M = Cr, Cu; 0.0 ? x ? 0.5) were synthesized using sol-gel auto-combustion method. The formation of ferrite particles was confirmed using Fourier Transform Infra-Red (FT-IR) spectra and powder X-ray Diffraction (XRD) techniques. The entire ferrite compositions were found to be pure phased with same symmetry as LaFeO3. The average crystallite size was calculated to be ?60 nm. The ferrite compositions were observed to behave as semi-conductors, as their resistivity decreased with increasing temperature. These ferrite compositions were employed as catalysts in the decomposition of hydrogen peroxide solution (0.17 M). Pure LaFeO3 was found to have a very low catalytic activity towards the decomposition of hydrogen peroxide solution, while presence of copper in the lanthanum ferrite lattice was found to significantly enhance its catalytic activity. The rate constant in case of reactions catalysed by LaCu0.5Fe0.5O3 was nearly 25 times larger than that obtained from reactions catalysed by pure LaFeO3. However, chromium substitution was not found to influence the catalytic activity of lanthanum ferrites as chromium substituted lanthanum ferrites exhibited very low catalytic activity. This was explained on the basis of relative stability of oxidation states of the substituent ions and the presence of defects in the crystal lattice.

Jauhar, Sheenu; Singhal, Sonal

2014-10-01

303

Isolation of hemoglobin from human blood using solid phase extraction with lanthanum(III) modified zeolite  

Microsoft Academic Search

A direct solid-phase extraction procedure for the selective isolation of hemoglobin from complex matrices using lanthanum(III)\\u000a modified zeolite (clinoptilolite) as sorbent was developed. The modified clinoptilolite provides a sorption capacity of 31.8 mg\\u000a g-1 for hemoglobin (Hb). Experimental parameters governing the sorption efficiency, i.e., the pH of sample solution, the ionic\\u000a strength and sorption time, were investigated. A sorption efficiency of

Xuwei Chen; Shuai Chen; Jiawei Liu; Jianhua Wang

2009-01-01

304

Lanthanum carbonate decreases PTH gene expression with no hepatotoxicity in uraemic rats  

Microsoft Academic Search

Background. Lanthanum (La) carbonate is an effective phosphate-binder, used to reverse hyperphosphatae- mia due to chronic kidney disease. Some recent studies in rodents have cast safety uncertainties. The aims of this study were to examine the effects of La on parathyroid hormone (PTH) gene expression and hepatic toxicity. Methods. Uraemia was induced in rats by a 0.3% adenine-containing diet for

Iddo Z. Ben-Dov; Orit Pappo; Miri Sklair-Levy; Hillel Galitzer; Yaron Ilan; Tally Naveh-Many; Justin Silver

2007-01-01

305

Characterization of catalytic lanthanum oxide for double bond isomerization of n-butenes  

E-print Network

Material and Prepared La(OH)3, 2 Temperature Dependence of Surface Area and Phase Composi- tion of Lanthanum Oxide Catalyst. 20 24 3 Initial 1-Butene Reaction Rates at O'C for Successive Experiments Involving No Catalyst Pretreatment between Runs..., 37 LIST OF FIGURES Figure Page Schematic Representation of the Apparatus. . 16 Dependence of initial 1-butene reaction rate on final calcination temperature of La203. Solid points, normal pretreatment; open points, normal pretreatment; open...

Fox, Janan Sherlene

2012-06-07

306

Plastic deformation of piezoelectric lanthanum-gallium tantalate crystals during cyclic mechanical actions  

NASA Astrophysics Data System (ADS)

The microstructure of piezoelectric lanthanum-gallium tantalite single crystals is shown to change substantially during cyclic mechanical actions at room temperature and during thermal shock: the dislocation density increases, twinning takes place, and a mesostructure forms. This effect is related to the appearance of piezoelectric fields, which significantly decrease the temperature of the onset of plastic deformation of these brittle single crystals, during mechanical actions.

Kugaenko, O. M.; Uvarova, S. S.; Petrakov, V. S.; Buzanov, O. A.; Egorov, V. N.; Sakharov, S. A.; Pozdnyakov, M. L.

2013-04-01

307

Effect of chloride incorporation on the crystallization of zirconium-barium-lanthanum-aluminum fluoride glass  

NASA Technical Reports Server (NTRS)

One aspect of the influence of preparation procedure on the crystallization behavior of a zirconium-barium-lanthanum-aluminum fluoride glass was studied. The crystallization pattern of this glass may be affected by the chlorine concentration within it. In particular, when such glasses are heated at low temperatures, the alpha-Ba-Zr-F6 crystalline phase forms only in those glasses which contain chloride.

Neilson, G. F.; Smith, G. L.; Weinberg, M. C.

1985-01-01

308

Deposition of highly oriented lanthanum nickel oxide thin film on silicon wafer by CSD  

Microsoft Academic Search

This paper describes the orientation control and the electrical properties of the chemical solution deposition (CSD) derived LaNiO3 (LNO) thin film. The LNO precursor solutions were prepared using lanthanum nitrate and nickel acetate as La and Ni source, and ethanol or 2-methoxyethanol and 2-aminoethanol mixed solution as solvents. The LNO films were spin-coated using these precursor solutions and annealed at

H. Suzuki; T. Naoe; H. Miyazaki; T. Ota

2007-01-01

309

Thermodynamics and phase relationships of the ternary lanthanum-uranium-oxygen system  

Microsoft Academic Search

In the selected regions La:(La + U) = 0.05 and O:(La + U) = 2.00 of the ternary system lanthanum-uranium-oxygen emf measurements on solid state galvanic cells, coulometric titrations, and X-ray diffraction techniques were used to obtain phase boundaries and thermodynamic data in the temperature range from 600 to 1000°C. For the first time order &rlhar2; disorder transformations of La1-yUyO2+x

E. Stadlbauer; U. Wichmann; U. Lott; C. Keller

1974-01-01

310

Samarium-153-ethylene diamine tetramethylene phosphonate, a beta-emitting bone-targeted radiopharmaceutical, useful for patients with osteoblastic bone metastases  

PubMed Central

Bone metastases are prevalent among cancer patients and frequently cause significant morbidity. Oncology providers must mitigate complications associated with bone metastases while limiting therapy-related adverse effects and their impact on quality of life. Multiple treatment modalities, including chemotherapy, surgery, external beam radiation therapy, and radioisotopes, among others, have been recommended and utilized for palliative treatment of bone metastases. Radioisotopes such as samarium-153 are commonly used in the setting of multifocal bone metastases due to their systemic distribution, affinity for osteoblastic lesions, acceptable toxicity profile, and convenience of administration. This review focuses on samarium-153, first defining its radiobiologic and pharmacokinetic properties before describing many clinical trials that support its use as a safe and effective tool in the palliation of patients with bone metastases. PMID:23976864

Longo, John; Lutz, Stephen; Johnstone, Candice

2013-01-01

311

Lanthanum halide scintillators for time-of-flight 3-D pet  

DOEpatents

A Lanthanum Halide scintillator (for example LaCl.sub.3 and LaBr.sub.3) with fast decay time and good timing resolution, as well as high light output and good energy resolution, is used in the design of a PET scanner. The PET scanner includes a cavity for accepting a patient and a plurality of PET detector modules arranged in an approximately cylindrical configuration about the cavity. Each PET detector includes a Lanthanum Halide scintillator having a plurality of Lanthanum Halide crystals, a light guide, and a plurality of photomultiplier tubes arranged respectively peripherally around the cavity. The good timing resolution enables a time-of-flight (TOF) PET scanner to be developed that exhibits a reduction in noise propagation during image reconstruction and a gain in the signal-to-noise ratio. Such a PET scanner includes a time stamp circuit that records the time of receipt of gamma rays by respective PET detectors and provides timing data outputs that are provided to a processor that, in turn, calculates time-of-flight (TOF) of gamma rays through a patient in the cavity and uses the TOF of gamma rays in the reconstruction of images of the patient.

Karp, Joel S. (Glenside, PA); Surti, Suleman (Philadelphia, PA)

2008-06-03

312

Multicenter study of long-term (two-year) efficacy of lanthanum carbonate.  

PubMed

Long-term efficacy of lanthanum carbonate on hyperphosphatemia was examined in multicenter dialysis patients. Outcome and efficacy after 2 years was investigated in 101 patients who had undergone lanthanum carbonate administration. Thirty-three cases dropped out by the 2-year point; patients undergoing at least 2 years of administration totaled 68. Reasons for dropping out were as follows: improvement of hyperphosphatemia, nine cases; changing hospitals, seven cases; medical complications, five cases; digestive symptoms, four cases; poor compliance, four cases; parathyroidectomy, two cases; death, two cases. The mean dosage was increased from initial daily dosage of 744?mg to 1266?mg after 1 year, and to 1246?mg after 2 years. Serum phosphate concentration decreased significantly from the initial 6.15?mg to 5.57?mg/dL after 1 year, and to 5.45?mg/dL after 2 years. Although a lowering trend was observed in corrected calcium levels, the difference was not significant. Parathyroid hormone was unchanged. Achievement rate of Japanese Society for Dialysis Therapy (JSDT) management target values for both phosphorus and calcium improved from 32.7% to 50.0% after 1 year, and to 56.5% after 2 years. Lanthanum carbonate is useful as a therapeutic tool for hyperphosphatemia over long durations. PMID:23586506

Ando, Ryoichi; Kimura, Hitoshi; Sato, Hidehiko; Iwamoto, Shunsuke; Yoshizaki, Yuki; Chida, Yoshiko; Ishida, Yuji; Takayama, Masanobu; Yamada, Kouei; Tachibana, Ken; Ohtsuka, Masakazu; Kikuchi, Kan; Inoue, Atsushi

2013-04-01

313

Impact of lanthanum carbonate on cortical bone in dialysis patients with adynamic bone disease.  

PubMed

Among the most serious problems in patients with chronic kidney disease (CKD) is fragility of cortical bone caused by cortical thinning and increased cortical porosity; the cortical fragility is sometimes irreversible, with fractures generally initiating from cortical bone. Therefore, development of treatments for problems of cortical bone is urgently desired. Cortical bone has the three surfaces, including the periosteal surface, intracortical spaces and endocortical surface. Bone turnover at the endocortical surface and intracortical resorption spaces are increased as compared with that at cancellous surface. Bone growth sometimes depends on apposition at the periosteal surface. We treated hyperphosphatemia in two hemodialysis patients with adynamic bone disease with 750-1500?mg/day of lanthanum carbonate, which is a non-calcium containing phosphate binder; the treatment resulted in a decrease of the serum phosphorus levels (P levels), without significant change of the serum intact parathyroid hormone levels. We now report that treatment of these patients with lanthanum carbonate increased mineralization of the periosteal surface, increased bone mass within the intracortical resorption spaces and increased mineralization of the minimodeling surface at the endocortical surface. In addition, woven bone volume in cortical bone was decreased and mineralization of bone units, namely, osteons, was increased. Although these findings were not observed across all surfaces of the cortical bone in the patients, it is expected that lanthanum carbonate would increase the cortical stability in CKD patients, with consequent reduction in the fracture rate in these patients. PMID:23586512

Yajima, Aiji; Inaba, Masaaki; Tominaga, Yoshihiro; Tanaka, Motoko; Otsubo, Shigeru; Nitta, Kosaku; Ito, Akemi; Satoh, Shigeru

2013-04-01

314

Efficacy of continuous oral administration of lanthanum carbonate over 24 months.  

PubMed

To examine the efficacy of long-term administration of lanthanum carbonate, changes in serum Ca, phosphate, whole parathyroid hormone (wPTH), and ALP were examined in 40 patients who were able to tolerate dosage of lanthanum carbonate over a continuous period of 24 months. Concurrently, concomitant administration of other phosphate binders, cinacalcet, vitamin D, etc., was also examined. After 24 months, serum phosphorus levels (P levels) had decreased to within management target of guidelines, from 6.16?±?1.44?mg/dL to 5.58?±?1.15?mg/dL, and this effect was maintained for 2 years. There were no changes in Ca level. wPTH did not change significantly but tended to increase at 12 months. The dose of concomitantly administered calcium carbonate and sevelamer hydrochloride was reduced. The P-lowering function of lanthanum carbonate still held steady at 24 months following the start of dosage. Because of the rising trend seen in wPTH, dose of cinacalcet and/or vitamin D need to be modulated. Reducing the number of concomitantly administered phosphate binder tablets was desirable from the standpoint of patient adherence. PMID:23586509

Ishizu, Takashi; Hong, Zhang; Matsunaga, Tsuneaki; Kaneko, Yoko; Taru, Yoshinori

2013-04-01

315

Lanthanum silicate coated magnetic microspheres as a promising affinity material for phosphopeptide enrichment and identification.  

PubMed

Novel Fe(3)O(4)@La(x)Si(y)O(5) affinity microspheres consisting of a superparamagnetic Fe(3)O(4) core and an amorphous lanthanum silicate shell have been synthesized. The core-shell-structured Fe(3)O(4)@La(x)Si(y)O(5) microspheres, with a mean size of ca. 480 nm, had rough lanthanum silicate surfaces and displayed relatively strong magnetism (47.2 emu g(-1)). This novel affinity material can be used for selective capture, rapid magnetic separation, and part dephosphorylation (which plays an important role in identifying phosphopeptides in MS) of the phosphopeptides in a peptide mixture. Its ability to selectively trap and magnetically isolate as well as label the phosphopeptides was evaluated using a standard phosphorylated protein (?-casein) and a real sample (human serum). Phosphopeptides and their corresponding label ions were detected for concentrations of ?-casein as low as 1 × 10(-9) M and in mixtures of ?-casein and BSA with molar ratios as low as 1:50. In addition, this affinity material, with its labeling properties, is superior to commercial TiO(2) beads in terms of interference from non-phosphopeptide molecules. These results reveal that the lanthanum silicate coated magnetic microspheres represent a promising affinity material for the rapid purification and recognition of phosphopeptides. PMID:22722743

Cheng, Gong; Liu, Yan-Lin; Zhang, Ji-Lin; Sun, De-Hui; Ni, Jia-Zuan

2012-08-01

316

Structure of human uridine-cytidine kinase 2 determined by SIRAS using a rotating-anode X-ray generator and a single samarium derivative.  

PubMed

Uridine-cytidine nucleoside kinase 2 (UCK2) is the rate-limiting enzyme in the pyrimidine-nucleotide salvage pathway. UCK2 catalyzes the phosphorylation of the natural ribonucleosides cytidine and uridine to cytidine 5'-monophosphate (CMP) and uridine 5'-monophosphate (UMP), respectively, and activates several important frontline antimetabolite drugs. The present contribution reports the rapid crystal structure determination of human UCK2 complexed with a magnesium ion and the reaction products adenosine 5'-diphosphate (ADP) and CMP. Diffraction data were collected on a copper rotating-anode X-ray generator from one native UCK2 crystal and a single samarium-derivative crystal. Utilizing the relatively high anomalous signal from the samarium derivative at the Cu Kalpha wavelength, the structure was determined by single isomorphous replacement and single anomalous signal (SIRAS) phasing techniques. Two of the four major samarium sites are located in the active sites of the two UCK2 molecules that form the asymmetric unit and appear to displace the magnesium ions present in the native crystals. The crystal structures of UCK2 alone and in complex with various ligands have recently been determined using traditional multiple isomorphous replacement (MIR) phasing techniques and data from three heavy-atom derivatives. The reported structures validate our independently determined structure. Of more than 1000 kinase crystal structure entries in the Protein Data Bank, less than 1% of them have been determined by SIRAS. For the published kinase crystal structures determined by SIRAS, all data were reportedly collected at various synchrotron-radiation facilities. This study demonstrates that diffraction data collected from a single samarium derivative using Cu Kalpha radiation provides sufficient phasing power to determine a novel macromolecular crystal structure. PMID:15735337

Appleby, Todd C; Larson, Gary; Cheney, I Wayne; Walker, Heli; Wu, Jim Z; Zhong, Weidong; Hong, Zhi; Yao, Nanhua

2005-03-01

317

History of Doping and Doping Control  

Microsoft Academic Search

\\u000a Although attempts to enhance athletic performance are probably much older, the word “doping” was first mentioned in 1889 in\\u000a an English dictionary. It described originally a mixed remedy containing opium, which was used to “dope” horses. “Dope” was\\u000a a spirit prepared from the residues of grapes, which Zulu warriors used as a “stimulant” at fights and religious procedures\\u000a and which

Rudhard Klaus Müller

318

The distribution of the lanthanum anomaly in the Dutch branches of the Rhine River  

NASA Astrophysics Data System (ADS)

The elements lanthanum to lutetium, usually referred as the REE, are increasingly used in numerous high technology products and processes. Such products are Gadolinium chelates, used as contrasting agents in medical imaging, and produce positive anthropogenic Gd-anomalies in rare earth shale normalized (Reenasc) patterns in rivers, surface and ground waters and shallow seas. Because of the increased use of the REE, the monitoring program of the Rhine-Meuse branches and surface water influenced by them in the Netherlands was extended from 2008 with the REE. In this monitoring program both the total and dissolved (< 0.45 ?m) fraction are analyzed. At the monitoring station Lobith, where the River Rhine enters the Netherlands, the REEnasc-patterns show beside the well-known Gd-anomaly a distinct La-anomaly. This positive La-anomaly in the Rhine River is recently also reported by Kulaksiz and Bau (2011, sampling was done in 2009) and first occur in the Rhine River north of the city of Worms, 400km upstream of the Dutch-German border. Kulaksiz and Bau could show that this anomaly is of anthropogenic origin and can be traced back to the effluent from a production plant for fluid catalytic cracking catalysts at Rhine river-km 447.4. The amount of anthropogenic lanthanum in the total fraction in Lobith station is an order of magnitude larger than in the dissolved fraction indicating that the suspended matter in the Rhine River is the major carrier of the anthropogenic lanthanum. All REEnasc- patterns of the branches of the Rhine River show in addition to the Gd-anomaly a positive La-anomaly, while in the Meuse River only a Gd-anomaly is observed. In the influenced surface waters of the Rhine and Meuse Rivers always a Gd-anomaly occurs but in those influenced by the Rhine tributaries also the La-anomaly occurs. In the poster the load of lanthanum over the years 2008, 2009 and 2010 in the dissolved and total fraction at Lobith and the distribution of the La anomaly over the branches of the Rhine River in the Netherlands (4 monitoring stations) and influenced surface water (5 monitoring stations) will be shown. The Meuse monitoring stations will be given for comparison. Kulaksiz, S., Bau, M., 2011. Rare earth elements in the Rhine River, Germany: First case of anthropogenic lanthanum as a dissolved microcontaminant in the hydrosphere. Environment International, 37: 973-879.

Verheul, M.; Klaver, G.; Bakker, I.; Petelet-Giraud, E.

2011-12-01

319

Synthesis and dielectric properties of substituted lanthanum aluminate  

SciTech Connect

LaAlO[sub 3] was chemically modified in order to ascertain the effects of substitution of larger cations on the compound's slight rhombohedral distortion from cubic symmetry--a property that often degrades the performance of LaAlO[sub 3] substrates for epitaxial high-temperature superconducting films. La[sub 1[minus]x]Sr[sub x]Al[sub 1[minus]x]Ti[sub x]O[sub 3] (x = 0.05, 0.10, 0.15, 0.25), La[sub 1[minus]x]Sr[sub x]Al[sub 1[minus]x]Zr[sub x]O[sub 3], La[sub 1[minus]x]Sr[sub x]Al[sub 1[minus]x]Mg[sub x]O[sub 3[minus]2x]F[sub 2x] and La[sub 1[minus]x]Sr[sub x]Al[sub 1[minus]x]Sc[sub x]O[sub 3[minus]x]F[sub x] (x = 0.05, 0.10, 0.15) were prepared in polycrystalline form and 1--2 mm single crystals of the Sr, Ti- and Sr,Zr-substituted systems were grown using a PbO-PbF[sub 2]-B[sub 2]O[sub 3]-PbO[sub 2] flux. Shifts in the peak positions of the X-ray powder diffraction patterns confirmed substitution of the larger cations. The diffraction patterns were also typified by line-broadening and a decrease in the rhombohedral splitting at all doping levels. The dielectric constant of LaAlO[sub 3] was unchanged for all of the fluoride-containing systems and for the 5% Sr,Ti- and Sr,Zr-systems.

Vanderah, T.A.; Lowe-Ma, C.K.; Gagnon, D.R. (Naval Air Warfare Center, China Lake, CA (United States))

1994-12-01

320

Optical studies of Sm³? ions doped zinc alumino bismuth borate glasses.  

PubMed

Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of samarium (Sm(3+)) ions were prepared by using melt quenching technique and characterized for their lasing potentialities in visible region by using the techniques such as optical absorption, emission and emission decay measurements. Radiative properties for various fluorescent levels of Sm(3+) ions were estimated from absorption spectral information using Judd-Ofelt (JO) analysis. The emission spectra and con-focal photoluminescence images obtained by 410 nm laser excitation demonstrates very distinct and intense orange-red emission for all the doped glasses. The suitable concentration of Sm(3+) ions in these glasses to act as an efficient lasing material has been discussed by measuring the emission cross-section and branching ratios for the emission transitions. The quantum efficiencies were also been estimated from emission decay measurements recorded for the (4)G5/2 level of Sm(3+) ions. From the measured emission cross-sections, branching ratios, strong photoluminescence features and CIE chromaticity coordinates, it was found that 1 mol% of Sm(3+) ions doped ZnAlBiB glasses are most suitable for the development of visible orange-red lasers. PMID:24530709

Swapna, K; Mahamuda, Sk; Srinivasa Rao, A; Shakya, S; Sasikala, T; Haranath, D; Vijaya Prakash, G

2014-05-01

321

Optical studies of Sm3+ ions doped Zinc Alumino Bismuth Borate glasses  

NASA Astrophysics Data System (ADS)

Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of samarium (Sm3+) ions were prepared by using melt quenching technique and characterized for their lasing potentialities in visible region by using the techniques such as optical absorption, emission and emission decay measurements. Radiative properties for various fluorescent levels of Sm3+ ions were estimated from absorption spectral information using Judd-Ofelt (JO) analysis. The emission spectra and con-focal photoluminescence images obtained by 410 nm laser excitation demonstrates very distinct and intense orange-red emission for all the doped glasses. The suitable concentration of Sm3+ ions in these glasses to act as an efficient lasing material has been discussed by measuring the emission cross-section and branching ratios for the emission transitions. The quantum efficiencies were also been estimated from emission decay measurements recorded for the 4G5/2 level of Sm3+ ions. From the measured emission cross-sections, branching ratios, strong photoluminescence features and CIE chromaticity coordinates, it was found that 1 mol% of Sm3+ ions doped ZnAlBiB glasses are most suitable for the development of visible orange-red lasers.

Swapna, K.; Mahamuda, Sk.; Srinivasa Rao, A.; Shakya, S.; Sasikala, T.; Haranath, D.; Vijaya Prakash, G.

322

Optical Characteristics of La-Doped ZnS Thin Films Prepared by Chemical Bath Deposition  

NASA Astrophysics Data System (ADS)

Undoped and La-doped ZnS thin films are prepared by chemical bath deposition (CBD) process through the co-precipitation reaction of inorganic precursors zinc sulfate, thiosulfate ammonia and La2O3. Composition of the films is analyzed using an energy-dispersive x-ray spectroscopy (EDS). Absorption spectra and spectral transmittances of the films are measured using a double beam UV-VIS spectrophotometer (TU-1901). It is found that significant red shifts in absorption spectra and decrease in absorptivity are obtained with increasing lanthanum. Moreover, optical transmittance is increased as La is doped, with a transmittance of more than 80% for wavelength above 360 nm in La-doped ZnS thin films. Compared to pure ZnS, the band gap decreases and flat-band potential positively shifts to quasi-metal for the La-doped ZnS. These results indicate that La-doped ZnS thin films could be valuably adopted as transparent electrodes.

Xie, Hai-Qing; Chen, Yuan; Huang, Wei-Qing; Huang, Gui-Fang; Peng, Ping; Peng, Li; Wang, Tai-Hong; Zeng, Yun

2011-02-01

323

Diode pumped neodymium doped ASL (Sr1-xLax-yNdyMgxAl12-xO19) laser  

NASA Astrophysics Data System (ADS)

Blue laser based on Neodymium doped strontium lanthanum magnesium aluminoxide (Sr1-xLax-yNdyMgxAl12-xO19) single crystal were constructed by second harmonic generation. Output power of 1.72 W at 900nm was obtained under 792nm laser diode pump. Intra cavity second harmonic generation were performed with non linear crystal LBO leading to output power of 76.6 mW at 450nm with absorbed power of 13.7 W and average absorption efficiency of 61% in Nd:ASL crystal.

Zheng, Lihe; Loiseau, Pascal; Aka, Gérard

2013-07-01

324

Practical Doping Principles  

SciTech Connect

'Theoretical investigations of doping of several wide-gap materials suggest a number of rather general, practical"doping principles" that may help guide experimental strategies of overcoming doping bottlenecks. This paper will be published as a journal article in the future.

Zunger, A.

2003-05-01

325

DETERMINATION OF LEAD AND CADMIUM IN FISH AND CLAM TISSUE BY ATOMIC ABSORPTION SPECTROMETRY WITH A MOLYBDENUM AND LANTHANUM TREATED PYROLYTIC GRAPHITE ATOMIZER  

EPA Science Inventory

A molybdenum and lanthanum treated pyrolytically coated graphite tube is employed for the furnace atomic absorption spectrometric determination of lead and cadmium directly in nitric-perchloric acid tissue digests. Lanthanum tends to promote the formation of a smooth lead atomiza...

326

Nonaqueous synthesis of metal oxide nanoparticles: Short review and doped titanium dioxide as case study for the preparation of transition metal-doped oxide nanoparticles  

SciTech Connect

The liquid-phase synthesis of metal oxide nanoparticles in organic solvents under exclusion of water is nowadays a well-established alternative to aqueous sol-gel chemistry. In this article, we highlight some of the advantages of these routes based on selected examples. The first part reviews some recent developments in the synthesis of ternary metal oxide nanoparticles by surfactant-free nonaqueous sol-gel routes, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the presentation of structural peculiarities of manganese oxide nanoparticles with an ordered Mn vacancy superstructure. These examples show that nonaqueous systems, on the one hand, allow the preparation of compositionally complex oxides, and, on the other hand, make use of the organic components (initially present or formed in situ) in the reaction mixture to tailor the morphology. Furthermore, obviously even the crystal structure can differ from the corresponding bulk material like in the case of MnO nanoparticles. In the second part of the paper we present original results regarding the synthesis of dilute magnetic semiconductor TiO{sub 2} nanoparticles doped with cobalt and iron. The structural characterization as well as the magnetic properties with special attention to the doping efficiency is discussed. - Graphical abstract: In the first part of this article, nonaqueous sol-gel routes to ternary metal oxide nanoparticles are briefly reviewed, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the appearance of an unprecedented superstructure in MnO nanoparticles. In the second part, doping experiments of TiO{sub 2} with Fe and Co are presented, along with their characterization including magnetic measurements.

Djerdj, Igor [ETH Zuerich, Department of Materials, Wolfgang-Pauli-Strasse 10, 8093 Zuerich (Switzerland)], E-mail: igor.djerdj@mat.ethz.ch; Arcon, Denis [Institute Jozef Stefan, Jamova 39, 1000 Ljubljana (Slovenia); Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Jaglicic, Zvonko [Institute of Mathematics, Physics and Mechanics, Jadranska 19, 1000 Ljubljana (Slovenia); Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova 2, 1000 Ljubljana (Slovenia); Niederberger, Markus [ETH Zuerich, Department of Materials, Wolfgang-Pauli-Strasse 10, 8093 Zuerich (Switzerland)], E-mail: markus.niederberger@mat.ethz.ch

2008-07-15

327

[Doping in adolescence].  

PubMed

Doping in sport is often very present in the media. Doping does not only concern top level sports but it also has an impact on sport as a whole. Young athletes may be influenced by its role models. In Switzerland there are no exact data on this influence or on the use of doping by adolescents. In this article, the effects and side-effects especially on adolescents of some current doping substances are discussed. As well, the regulations of the therapeutic use exemptions for doping substances are explained. PMID:17245674

Kamber, M; Mullis, P-E

2007-02-01

328

Effect of Hydrogen Anneals on Niobium-Doped Lead Zirconate Titanate Capacitors with Lanthanum Strontium Cobalt Oxide\\/Platinum Electrodes  

Microsoft Academic Search

Ferroelectric capacitors, being oxide ceramics, are very sensitive to the effects of hydrogen environments at elevated temperatures [H. Ashida et al..: Integr. Ferroelectr. 21 (1998) 97]. After a capacitor has been exposed directly to a annealing hydrogen environment at low hydrogen partial pressures, the electrical properties of the device can deteriorate and leakage currents can increase. At higher hydrogen concentration

Joe T. Evans Jr.; Leonard Boyer; Geri Velasquez; Ramamoorthy Ramesh; Sanjeev Aggarwal; Vassillis Keramidas

1999-01-01

329

Valence electronic structure of Mn in undoped and doped lanthanum manganites from relative K X-ray intensity studies  

Microsoft Academic Search

Relative K X-ray intensities of Mn in Mn, MnO2, LaMnO3 and La0.7B0.3MnO3 (B = Ca, Sr and Ce) systems have been measured following excitation by 59.54 keV ?-rays from a 200 mCi 241Am point-source. The measured results for the compounds deviate significantly from the results of pure Mn. Comparison of the experimental data with the multi-configuration Dirac–Fock (MCDF) effective atomic

S. Raj; H. C. Padhi; P. Raychaudhury; A. K. Nigam; R. Pinto; M. Polasik; F. Pawlowski; D. K. Basa

2001-01-01

330

EFFECT OF CATHODE MICROSTRUCTURE ON CATHODE POLARIZATION IN SINTERED STRONTIUM-DOPED LANTHANUM MANGANITE/YTTRIA STABILIZED  

E-print Network

will ever begin to compare to him. #12;4 ACKNOWLEDGMENTS I acknowledge the Alliance for Graduate Education..................................................................................................................15 1.1 Motivation..........................................................

Florida, University of

331

Preliminary investigation of lanthanum-cerium bromide self-activity removal  

NASA Astrophysics Data System (ADS)

It has been reported that detectors made of lanthanum-cerium halides (LaBr3:Ce and CeBr3) have superior energy resolution for gamma-radiation detection compared to what is offered by conventional sodium iodide (NaI:T1) detectors. Although superior energy resolution may be observed, one major barrier that has hindered the rapid adaptation of lanthanum halides is their self-activity, due primarily to the presence of isotope 138La, and the ? contamination, due to the trace amount of actinides. It has also been observed that the lanthanum-cerium halides contain a substantial amount of self-activity caused by the radioactive isotope 138La. Additionally, LaBr3:Ce spectra are also affected by ? contaminations in the low-energy region. To use either LaBr3:Ce or CeBr3 for high-sensitivity gamma detection, it may be necessary to have the self-activity as well as ? and ? contaminations removed or reduced. This paper describes a novel algorithmic approach for self-activity and contamination reduction for LaBr3:Ce and CeBr3 detectors using a third reference NaI:T1 detector. We present a computational procedure for separating self-activity from the gamma spectra obtained by LaBr3:Ce detectors. With the self-activity spectra precalculated, it is possible to perform real-time self-activity removal. This procedure can be implemented as an automatic self-activity subtraction module for gamma-radiation detectors made of LaBr3:Ce and/or CeBr3 crystals. With this approach, it is possible to develop a new generation of LaBr3:Ce detectors capable of producing spectra as clean as those obtained by conventional NaI:T1 detectors, but with much improved energy resolutions.

Yuan, Ding; Guss, Paul

2011-09-01

332

Signal intensity of lanthanum carbonate on magnetic resonance images: phantom study  

Microsoft Academic Search

Purpose  Lanthanum carbonate (LC) is used to treat hyperphosphatemia. The purpose of this study was to investigate the signal intensity\\u000a (SI) of LC on magnetic resonance imaging (MRI) scans of phantoms.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  LC tablets were thoroughly ground and mixed with distilled water or edible agar (0.05, 0.25, 0.5, and 2.5 mg\\/ml) in plastic\\u000a bottles. Four intact tablets were placed in

Shinichi Nakamura; Kazuo Awai; Masanori Komi; Kosuke Morita; Tomohiro Namimoto; Yumi Yanaga; Daisuke Utsunomiya; Shuji Date; Yasuyuki Yamashita

2011-01-01

333

Temperature-Dependent Electrical and Micromechanical Properties of Lanthanum Titanate with Additions of Yttria  

NASA Technical Reports Server (NTRS)

Temperature-dependent elastic properties were determined by establishing continuous flexural vibrations in the material at its lowest resonance frequency of 31tHz. The imaginary part of the complex impedance plotted as a function of frequency and temperature reveals a thermally activated peak, which decreases in magnitude as the temperature increases. Additions of yttria do not degrade the electromechanical in particularly the elastic and anelastic properties of lanthanum titanate. Y2O3/La2Ti2O7 exhibits extremely low internal friction and hence may be more mechanical fatigue-resistant at low strains.

Goldsby, Jon C.

2010-01-01

334

Temperature Dependent Electrical and Micromechanical Properties of Lanthanum Titanate with Additions of Yttria  

NASA Technical Reports Server (NTRS)

Lanthanum titanate (La2Ti2O7) a layered distorted perovskite (1) with space group Pna2(sub 1) has been shown to have potential as a high temperature piezoelectric (2). However this highly refractory oxide compound must be consolidated at relatively high temperatures approximately 1400 C. Commercial La2Ti207 powders were mechanically alloyed with additions of Y2O3 to lower the consolidation temperature by 300 C and to provide post processing mechanical stability. Temperature dependent electrical, elastic and anelastic behavior were selected as nondestructive means of evaluating the effects of yttria on the properties of this ferroceramic material.

Goldsby, Jon C.

2003-01-01

335

Investigation of the elemental composition of lanthanum-cerium hexaboride crystals  

NASA Astrophysics Data System (ADS)

Crystals of solid solutions of lanthanum-cerium hexaborides (La1-xCex)B6 possess unique thermoelectric properties in the temperature range of 0.3-9 K and they can be used in thermoelectric single-photon detectors as a sensor. One can observe a wide spread in thermoelectric measurement values reported in the literature, which is because of different qualities of studied crystals. The greatest influence on both the Seebeck coefficient and electrical resistivity of samples is exercised by the presence of uncontrolled impurities in crystals and the deviation from stoichiometry. In this work we have studied just the aforementioned parameters of the crystals obtained by three different methods.

Badalyan, Georgi; Kuzanyan, Armen; Petrosyan, Vahagn; Kuzanyan, Vazgen; Gulian, Armen

2010-10-01

336

Lithium lanthanum titanate as an electrolyte for novel lithium ion battery systems  

NASA Astrophysics Data System (ADS)

Solid electrolytes with high lithium conductivity may serve as useful components for enabling novel lithium ion battery system design. This work demonstrates the integration of lithium lanthanum titanate (Li0.29La0.57TiO3) into a battery system separating electrodes based on liquid electrolyte. Specifically, binder free electrodes based on graphite and LiCoO2 were tested against lithium metal in liquid electrolyte with an intermediate solid electrolyte. The system was characterized by cyclic voltammetry, and electrochemical impedance.

Sun, Li; Sun, Ke; Dillon, Shen

2011-06-01

337

Sol-gel preparation and characterization of non-substituted and Sr-substituted lanthanum cobaltates  

Microsoft Academic Search

This paper reports on the results concerning the sol-gel preparation and characterization of Sr-substituted perovskite lanthanum\\u000a cobaltates La1?xSrxCoO3?? (x = 0.0, 0.25, 0.5 and 0.75). The metal ions, generated by dissolving starting materials in diluted acetic acid were complexed\\u000a by 1,2-ethanediol to obtain the precursors for the non-substituted and Sr-substituted LaCoO3. The influence of the synthesis temperature, heating time and

Sigute Cizauskaite; Aivaras Kareiva

2008-01-01

338

Low temperature synthesis of nanocrystalline lanthanum monoaluminate powders by chemical coprecipitation  

Microsoft Academic Search

Nanocrystalline lanthanum monoaluminate (LaAlO3) powders were prepared by chemical coprecipitation using 25vol.% of NH4OH, 0.05M La(NO3)3·6H2O and 0.05M Al(NO3)3·9H2O aqueous solutions as the starting materials. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analyses (TGA\\/DTA), X-ray diffraction (XRD), Raman spectrometry, specific surface area (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) were utilized

Chia-Liang Kuo; Cheng-Li Wang; Te-Yuan Chen; Guo-Ju Chen; I-Ming Hung; Chi-Jen Shih; Kuan-Zong Fung

2007-01-01

339

Crystallization of Lanthanum-Modified Lead Zirconate Titanate (PLZT) Using Coprecipitated Gels  

Microsoft Academic Search

Powders of lanthanum-modified lead zirconate titanate (Pb0.91La0.09)(Zr0.65Ti0.35)0.98O3 (PLZT 9\\/65\\/35) were obtained by calcination of various precursors via chemical coprecipitation methods. The precursors included the coprecipitated gel with the stoichiometric PLZT composition, PbO (powdered chemical reagent)+LZT coprecipitated gel, and mixture of Pb, La, Zr, and Ti individually precipitated gels. Crystallization behaviors of these precursors were examined over the temperature range of

Yao-Jung Lee; Fu-Su Yen; Jong-Ping Wu; Hsing-I Hsiang

1995-01-01

340

Fabrication of Lanthanum Telluride 14-1-11 Zintl High-Temperature Thermoelectric Couple  

NASA Technical Reports Server (NTRS)

The development of more efficient thermoelectric couple technology capable of operating with high-grade heat sources up to 1,275 K is key to improving the performance of radioisotope thermoelectric generators. Lanthanum telluride La3-xTe4 and 14-1-11 Zintls (Yb14MnSb11) have been identified as very promising materials. The fabrication of advanced high-temperature thermoelectric couples requires the joining of several dissimilar materials, typically including a number of diffusion bonding and brazing steps, to achieve a device capable of operating at elevated temperatures across a large temperature differential (up to 900 K). A thermoelectric couple typically comprises a heat collector/ exchanger, metallic interconnects on both hot and cold sides, n-type and ptype conductivity thermoelectric elements, and cold-side hardware to connect to the cold-side heat rejection and provide electrical connections. Differences in the physical, mechanical, and chemical properties of the materials that make up the thermoelectric couple, especially differences in the coefficients of thermal expansion (CTE), result in undesirable interfacial stresses that can lead to mechanical failure of the device. The problem is further complicated by the fact that the thermoelectric materials under consideration have large CTE values, are brittle, and cracks can propagate through them with minimal resistance. The inherent challenge of bonding brittle, high-thermal-expansion thermoelectric materials to a hot shoe material that is thick enough to carry the requisite electrical current was overcome. A critical advantage over prior art is that this device was constructed using all diffusion bonds and a minimum number of assembly steps. The fabrication process and the materials used are described in the following steps: (1) Applying a thin refractory metal foil to both sides of lanthanum telluride. To fabricate the n-type leg of the advanced thermoelectric couple, the pre-synthesized lanthanum telluride coupon was diffusion bonded to the metal foil using a thin adhesion layer. (2) Repeating a similar process for the 14-1-11 Zintl p-type leg of the advanced thermoelectric couple. (3) Bonding thick CTE-matched metal plates on the metallized lanthanum telluride and Yb14MnSb11 to form the hot and cold sides of the thermoelectric couple. The calculated conversion efficiency of such an advanced couple would be about 10.5 percent, about 35 percent better than heritage radioisotope thermoelectric technology that relies on Si-Ge alloys. In addition, unlike Si-Ge alloys, these materials can be combined with many other thermoelectric materials optimized for operation at lower temperatures to achieve conversion efficiency in excess of 15 percent (a factor of 2 increase over heritage technology).

Ravi, Vilupanur A.; Li, Billy Chun-Yip; Fleurial, Pierre; Star, Kurt

2010-01-01

341

Influence of samarium impurity on spectral characteristics of calcium iodide crystals  

NASA Astrophysics Data System (ADS)

The influence of a SmBr3 impurity on optical absorption spectra and x-ray-, photo-, and thermally stimulated luminescence of CaI2 scintillator was studied in the temperature range 90-295 K. Activation of CaI2 from the melt by SmBr3 caused absorption bands related to 4 f 6 ? 4 f 55 d electronic transitions in Sm2+ to appear in the spectra. Excitation and emission spectra of CaI2:SmBr3 (0.01 mol%) were represented mainly by bands characteristic of the matrix. The photoluminescence spectrum at 90 K upon optical excitation of the crystal in the impurity absorption region (?ex = 280 nm) was approximated by individual Gaussian bands with maxima near 345, 395, 430, 470, 500, and 520 nm. The photoluminescence spectrum of CaI2:SmBr3 (0.5 mol%) at 295 K with excitation by radiation from an LGI-21 nitrogen laser (?ex = 337.1 nm) was represented mainly by a band at 465 nm. The intensity of this band weakened, its maximum shifted to 470 nm, luminescence in the 520 nm region increased, and weak emission with a maximum near 585 nm was also observed upon lowering the crystal temperature to 90 K. Doping CaI2 with the Sm impurity decreased the yield and changed the spectral composition of its x-ray-luminescence. CaI2:SmBr3 stored a small light sum in shallow trapping levels upon x-ray excitation at 90 K. The nature of the emission and trapping centers in the investigated crystals was discussed.

Novosad, S. S.; Novosad, I. S.

2013-03-01

342

Effectiveness of Radiation Synovectomy with Samarium-153 Particulate Hydroxyapatite in Rheumatoid Arthritis Patients with Knee Synovitis: A Controlled Randomized Double-Blind Trial  

PubMed Central

OBJECTIVES: The aim of the present study was to investigate the effectiveness of Samarium153-particulate hydroxyapatite radiation synovectomy in rheumatoid arthritis patients with chronic knee synovitis. METHODS: Fifty-eight rheumatoid arthritis patients (60 knees) with chronic knee synovitis participated in a controlled double-blinded trial. Patients were randomized to receive either an intra-articular injection with 40 mg triamcinolone hexacetonide alone (TH group) or 40 mg triamcinolone hexacetonide combined with 15 mCi Samarium153-particulate hydroxyapatite (Sm/TH group). Blinded examination at baseline (T0) and at 1 (T1), 4 (T4), 12 (T12), 32 (T32), and 48 (T48) weeks post-intervention were performed on all patients and included a visual analog scale for joint pain and swelling as well as data on morning stiffness, flexion, extension, knee circumference, Likert scale of improvement, percentage of improvement, SF-36 generic quality of life questionnaire, Stanford Health Assessment Questionnaire (HAQ), Lequesne index, use of non-steroidal anti-inflammatory drugs or oral corticosteroids, events and adverse effects, calls to the physician, and hospital visits. RESULTS: The sample was homogeneous at baseline, and there were no withdrawals. Improvement was observed in both groups in relation to T0, but no statistically significant differences between groups were observed regarding all variables at the time points studied. The Sm/TH group exhibited more adverse effects at T1 (p<0.05), but these were mild and transitory. No severe adverse effects were reported during follow-up. CONCLUSION: Intra-articular injection of Samarium153-particulate hydroxyapatite (15 mCi) with 40 mg of triamcinolone hexacetonide is not superior to triamcinolone hexacetonide alone for the treatment of knee synovitis in patients with rheumatoid arthritis at 1 y of follow-up. PMID:20037706

dos Santos, Marla Francisca; Furtado, Rita Nely Vilar; Konai, Monique Sayuri; Castiglioni, Mario Luiz Vieira; Marchetti, Renata Rosa; Natour, Jamil

2009-01-01

343

Inhibition of transport of 47Ca and 85Sr by lanthanum in canine cortical bone  

PubMed Central

Deposition of 85Sr and 47Ca and blood flow (measured by iodoantipyrine washout) were determined in the tibial cortex of adult dogs after injection of graded doses of lanthanum chloride (LaCl3) and potassium cyanide (KCN) into the right tibial nutrient artery. Deposition of 85Sr and 47Ca, expressed in milliliters per gram of cortical bone in 10 min, was decreased after injections of lanthanum, 0.045 ± 0.008 (mean ± SE) compared to 0.097 ± 0.01 in control experiments (P < 0.005). Blood flow was unchanged. Injection of KCN did not affect the mean value of uptake of mineral (0.108 ± 0.01 vs. 0.097 ± 0.01) over the whole range of KCN dosage. Blood flow tended to be slightly higher with lower doses of KCN. These data support the concept of a transport system in bone for bone-seeking isotopes such as 85Sr and 47Ca. PMID:4811382

Paradis, Gaston R.; Bassingthwaighte, James B.; Kelly, Patrick J.

2010-01-01

344

Equilibrium distribution of lanthanum, neodymium, and thorium between fluoride salt melts and liquid bismuth  

NASA Astrophysics Data System (ADS)

The extraction of lanthanum, neodymium, and thorium from 73LiF-27BeF2, 78LiF-22ThF4, 75LiF-5BeF2-20ThF4, 15LiF-58NaF-27BeF2, and 60LiF-40NaF (mol %) fluoride salt melts into liquid bismuth with admixtures of lithium as a reducing agent was studied at 580-750°C. Equilibrium values of their distribution coefficients were measured. Beryllium as distinct from neodymium and lanthanum almost was not extracted into bismuth from salt beryllium-containing compositions. A decrease in the mole fraction of LiF in LiF-BeF2 melts substantially increased the effectiveness of its purification from lanthanides. The LiF-ThF4 and LiF-BeF2-ThF4 salt mixtures with comparatively high thorium concentrations (?20-22 mol %) could not be used for effective separation of lanthanides and thorium in a system for extraction processing of fuel salts.

Zagnit'ko, A. V.; Ignat'ev, V. V.

2012-04-01

345

Preconcentration of some metal ions with lanthanum-8-hydroxyquinoline co-precipitation system.  

PubMed

A method of separation and preconcentration of cadmium, copper, nickel, lead and zinc at trace level using 8-hydroxyquinoline as a chelating agent and lanthanum(III) as a carrier element is proposed. The heavy metals were determined after preconcentration by inductively coupled plasma optical emission spectrometry (ICP-OES). The results were compared with those obtained using flame atomic absorption spectrometry (F-AAS). The influence of several parameters such as pH, amount of lanthanum(III) as a carrier element, amount of 8-hydroxyquinoline, duration of co-precipitation was examined. Moreover, effects of inorganic matrix on recovery of the determined elements were studied. The detection limits (DL) for ICP-OES were 0.31, 2.9, 1.4, 3.2 and 1.2 ?g L(-1) for Cd, Cu, Ni, Pb and Zn, respectively, whereas for F-AAS DL were 0.63, 1.1, 3.2, 2.7 and 0.74 ?g L(-1). The recovery of the method for the determined elements was better than 94% with relative standard deviation between 0.63% and 2.9%. The preconcentration factor was 60. The proposed method was successfully applied for determination of Cd, Cu, Ni, Pb, and Zn in plant materials. Accuracy of the proposed method was verified using certified reference material (NCS ZC85006 Tomato). PMID:24206710

Feist, Barbara; Mikula, Barbara

2014-03-15

346

Lanthanum chloride impairs spatial learning and memory and downregulates NF-?B signalling pathway in rats.  

PubMed

Exposure to rare earth elements (REEs) is known to impair intelligence in children and cause neurobehavioral abnormalities in animals. However, the mechanisms underlying these phenomena are not clear. Lanthanum is often used to study the effects of REEs. The aim of this study was to investigate the influence of lanthanum chloride (LaCl3) on spatial learning and memory and a possible underlying mechanism involving nuclear factor-kappa B (NF-?B) signalling pathway expression in the hippocampus. The rats were exposed to 0, 0.25, 0.50 or 1.00 % LaCl3 in drinking water during pregnancy and lactation (i.e. while feeding their offspring). After weaning, young rats continued to receive 0, 0.25, 0.50 and 1.00 % LaCl3 in the drinking water for 1 month. LaCl3 exposure impaired the spatial learning and memory of young rats and significantly decreased the expression of phosphorylated I?B kinase complex, phosphorylated I?B?, NF-?B, c-fos, c-jun and brain-derived neurotrophic factor in the hippocampus. These results indicate that LaCl3 exposure impairs spatial learning and memory in rats by inhibiting NF-?B signalling pathway. PMID:23670203

Zheng, Linlin; Yang, Jinghua; Liu, Qiufang; Yu, Fei; Wu, Shengwen; Jin, Cuihong; Lu, Xiaobo; Zhang, Lifeng; Du, Yanqiu; Xi, Qi; Cai, Yuan

2013-12-01

347

Three-year follow-up of lanthanum carbonate therapy in hemodialysis patients.  

PubMed

For 3 years following the start of lanthanum carbonate therapy, effects on other pharmaceutical treatment with sevelamer hydrochloride (SH), calcium carbonate (CC), and vitamin D, and those on clinical condition were examined. Dialysis patients with hyperphosphatemia (89 cases; average age 55.2 years; dialysis history of 10 years; 50 male and 39 female), who agreed to start lanthanum carbonate (LC) administration, were observed for a mean period of 32.6?±?6.2 months. Mean daily dosages of CC and SH before starting LC were 2.68?g and 0.73?g; mean daily dosage amounts of LC, CC, and SH at the time of final evaluation were 0.87?g, 2.30?g, and 0.99?g, respectively. After the application of LC, serum phosphate as well as serum calcium controls were significantly improved, and the amounts of active vitamin D agents applied was significantly increased. In conclusion, LC is useful in managing serum phosphorus levels (P levels), and little incidence of hypercalcemia suggests favorable concomitant use with active vitamin D agents in LC therapy. PMID:23586508

Takeuchi, Kazuhisa; Matsuda, Etsuko; Sekino, Makoto; Hasegawa, Yukiko; Kamo, Yoshie; Kikuchi, Natsue; Sekino, Hiroshi

2013-04-01

348

The theoretical basis and clinical methodology for stereotactic interstitial brain tumor irradiation using iododeoxyuridine as a radiation sensitizer and samarium-145 as a brachytherapy source  

SciTech Connect

High grade astrocytomas have proven resistant to all conventional therapy. A technique to produce radiation enhancement during interstitial brain tumor irradiation by using a radiation sensitizer (IdUrd) and by stimulation of Auger electron cascades through absorption of low energy photons in iodine (Photon activation) is described. Clinical studies using IdUrd, {sup 192}Ir as a brachytherapy source, and external radiation have produced promising results. Substituting samarium-145 for {sup 192}Ir in this protocol is expected to produce enhanced results. 15 refs.

Goodman, J.H.; Gahbauer, R.A.; Kanellitsas, C.; Clendenon, N.R. (Ohio State Univ., Columbus, OH (USA)); Laster, B.H.; Fairchild, R.G. (Brookhaven National Lab., Upton, NY (USA))

1989-01-01

349

Contests with doping  

Microsoft Academic Search

Doping, or the use of illegal performance-enhancing drugs, is an epidemic problem in sports ranging from the Olympics to high school athletics. Sports organizations have been trying numerous approaches to discouraging these activities. This paper presents a theoretical model of doping in a winner-take-all contest environment to help investigate the efficiency of anti-doping enforcement policies. We show that, under fairly

Dmitry Ryvkin

2009-01-01

350

Efficacy, Tolerability, and Safety of Lanthanum Carbonate in Hyperphosphatemia: A 6Month, Randomized, Comparative Trial versus Calcium Carbonate  

Microsoft Academic Search

Background\\/Aims: Hyperphosphatemia is an important clinical consequence of renal failure, and its multiple adverse systemic effects are associated with significantly increased risks of morbidity and mortality in dialysis patients. Existing oral phosphate binders have not permitted control of serum phosphate within currently accepted guidelines. This study compares lanthanum carbonate with calcium carbonate for control of serum phosphate in hemodialysis patients.

A. J. Hutchison; B. Maes; J. Vanwalleghem; G. Asmus; E. Mohamed; R. Schmieder; W. Backs; R. Jamar; A. Vosskühler

2005-01-01

351

Role of intermediate solid phase in the process of magnesium and lanthanum aluminates formation in sub- and supercritical water  

Microsoft Academic Search

The synthesis of inorganic complicated powder oxides is of significant interest owing to wide application of these materials in modem engineering. In this paper the mechanism of fine crystalline magnesium and lanthanum aluminates formation in sub- and supercritical water was investigated. Mechanical mixtures of aluminium hydroxide and magnesia as well as lanthana were used as precursors. The synthesis was carried

S. N. Torbin; M. N. Danchevskaya; L. F. Martynova; G. P. Muravieva

2001-01-01

352

Radioactive synovectomy with (90) yttrium and (153) samarium hydroxyapatite in haemophilic joints: preliminary study on radiation safety.  

PubMed

Most countries still do not achieve 1 IU of factor VIII/capita sufficient for survival. Although primary prophylaxis prevents synovitis, is not universally used. Chronic synovitis is treated with arthroscopy at expense of considerable amount of coagulation factors, and specialized surgeons. Radioactive synovectomy (RS) is a minimally invasive and cost effective alternative to arthroscopy, often considered first the option for persistent synovitis. Even without established causation with cancer, RS is avoided by some, due to this concern. We aim contributing to the understanding of RS safety regarding malignancy, presenting a large number of treated patients, and a single case of cancer. Three centres in Brazil applied RS with (90) Yttrium Citrate, (90) Yttrium hydroxyapatite or (153) Samarium hydroxyapatite in haemophilic joints and performed a survey addressing cancer in these patients. Four hundred and eighty eight patients (ages 3-51) received 1-3 RS (total 842) and follow-up was 6 months to 9 years. One patient aged 14 years presented Ewing sarcoma, 11 months after RS. The tumour was treated successfully with surgery and chemotherapy. Causality of cancer by RS is improbable in this case. Accordingly, latency here is far below minimum 5-10 years for radio-induction of solid tumours. Moreover, ES is not a typically radio-induced tumour, even at high doses. In agreement with others, though recognizing limitations, this study suggests RS is safe regarding cancer induction. Synovitis is a known burden for patients. The decision of making reasonable usage of RS should be outweighed with the risks of leaving synovitis untreated. PMID:23534894

Thomas, S; Mendes, J D; Souza, S A; Lorenzato, C S; Assi, P E; Pacheco, L R L; Gabriel, M B; Bordim, A; Gutfilen, B; da Fonseca, L M B

2013-07-01

353

Phase I Trial of Vertebral Intracavitary Cement and Samarium (VICS): Novel Technique for Treatment of Painful Vertebral Metastasis  

SciTech Connect

Purpose: Kyphoplasty is an effective procedure to alleviate pain in vertebral metastases. However, it has no proven anticancer activity. Samarium-153-ethylene diamine tetramethylene phosphonate ({sup 153}Sm-EDTMP) is used for palliative treatment of bone metastases. A standard dose of 1 mCi/kg is administrated intravenously. The present study was conducted to determine the feasibility of intravertebral administration of {sup 153}Sm with kyphoplasty. Methods and Materials: A total of 33 procedures were performed in 26 patients. Of these 26 patients, 7 underwent procedures performed at two vertebral levels. The mean age of the cohort was 64 years (range, 33-86). The kyphoplasty procedure was performed using a known protocol; 1-4 mCi of {sup 153}Sm was admixed with the bone cement and administered under tight radiation safety measures. Serial nuclear body scans were obtained. Pain assessment was evaluated using a visual analog pain score. Results: All patients tolerated the procedure well. No procedure-related morbidities were noted. No significant change had occurred in the blood counts at 1 month after the procedure. One case was not technically satisfactory. Nuclear scans revealed clear radiotracer uptake in the other 32 vertebrae injected. Except for the first patient, no radiation leakage was encountered. The mean pain score using the visual analog scale improved from 8.6 before to 2.8 after the procedure (p < .0001). Follow-up bone scans demonstrated a 43% decrease in the tracer uptake. Conclusion: The results of our study have shown that the combination of intravertebral administration of {sup 153}Sm and kyphoplasty is well tolerated with adequate pain control. No hematologic adverse effects were found. A reduction of the bone scan tracer uptake was observed in the injected vertebrae. Longer follow-up is needed to study the antineoplastic effect of the procedure.

Ashamalla, Hani, E-mail: haa9002@nyp.or [Department of Radiation Oncology, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Cardoso, Erico [Department of Surgery, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Macedon, Mark; Guirguis, Adel [Department of Radiation Oncology, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Weng Lijun [Department of Nuclear Medicine, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Ali, Shamsah [Department of Surgery, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Mokhtar, Bahaa; Ashamalla, Michael; Panigrahi, Nokul [Department of Radiation Oncology, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States)

2009-11-01

354

Visible light emission and energy transfer processes in Sm-doped nitride films  

SciTech Connect

Even though the great interest in studying the near-infrared light emission due to Er{sup 3+} ions for telecommunication purposes, efficient visible radiation can be achieved from many different rare-earth (RE) ions. In fact, visible and/or near-infrared light emission takes place in RE-doped wide bandgap semiconductors following either photon or electron excitation, suggesting their technological potential in devices such as light-emitting diodes (LED's) and flat-panel displays, for example. Taking into consideration these aspects, the present contribution reports on the investigation of AlN, BeN, GeN, and SiN thin films doped with samarium. The samples were prepared by sputtering and as a result of the deposition method and conditions they present an amorphous structure and Sm concentrations in the low 0.5 at. %. After deposition, the samples were submitted to thermal annealing treatments and investigated by different spectroscopic techniques. A detailed examination of the experimental data allowed to identify optical transitions due to Sm{sup 3+} and Sm{sup 2+} ions as well as differences in their mechanisms of photon excitation and recombination. Moreover, it is shown that the Sm-related spectral features and emission intensity are susceptible, respectively, to the atomic environment the Sm{sup 3+}/Sm{sup 2+} ions experience and to the presence of non-radiative recombination centers.

Zanatta, A. R. [Instituto de Fisica de Sao Carlos - USP, Sao Carlos 13560-250 - SP (Brazil)

2012-06-15

355

Electroinduced structural change- and random walks-based impact on the light emission in Er3+/Yb3+ doped (Pb,La)(Zr,Ti)O3 ceramics  

NASA Astrophysics Data System (ADS)

Remarkable enhancement/reduction of light emission and competition among different wavebands with rare earth doped lanthanum lead zirconate titanate ceramics were observed in a corona atmosphere caused by an externally applied electric field. Quantum-mechanical analyses, based on variation of structural symmetry of the unit cell and hence the crystal field due to electrostriction, were given to elucidate the effect. Apart from the symmetry of crystal field, the obvious contribution from the optoenergy storage and weak localization of light involved were discussed. These results are promising in designing and implementation of lasers and sensors.

Xu, L.; Zhang, J.; Zhang, S.; Xu, C.; Zou, Y. K.; Zhao, H.

2013-06-01

356

Preparation and thermophysical properties of CeO 2 doped La 2Zr 2O 7 ceramic for thermal barrier coatings  

Microsoft Academic Search

Lanthanum zirconate (La2Zr2O7, LZ) and CeO2 doped La2Zr2O7 (LCZ) ceramic were synthesized by the coprecipitation–calcination method. The chemical compositions, phase compositions, thermophysical properties of these materials were investigated. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) and XRD results revealed that the compositions of all prepared ceramic materials were in the range of the synthesis of single La2Zr2O7 with pyrochlore structure. After

Hongming Zhou; Danqing Yi; Zhiming Yu; Lairong Xiao

2007-01-01

357

Synthesis of La and Nb doped PZT powder by the gel-combustion method  

NASA Astrophysics Data System (ADS)

Lanthanum and niobium doped PZT with composition (Pb0.93La0.07)[(Zr0.60Ti0.40)]0.9825Nb0.0175O3 (PZTLN) was prepared by the gel-combustion method. A precursor sol was obtained from lead nitrate, zirconyl nitrate, lanthanum oxide, peroxo-citrato-niobium and a peroxo-citrate complex of titanium isopropoxide as starting precursors. Various molar ratios of citrate/nitrate (CA/NO3- = 1.3, 0.36 and 0.09) were used to prepare very fine powders of PZTLN. The gels resulting from these sols were transformed into powders by an auto-combustion process at <=400 °C. The powders consisted of rhombohedral PZT (PbZr0.60Ti0.40O3), pyrochlore (Pb2Ti2O6) and lead carbonate (Pb2O·CO3) phases. The pure rhombohedral phase is found in PZTLN pellets sintered at 1100 °C for all citrate/nitrate ratios. Titanium and niobium precursors were modified with peroxo radicals. During the gel-combustion reaction, the temperature of the gel increases, leading to lead evaporation. The loss of lead as well as the particle size increases as the CA/NO3- ratio decreases. The smallest grained powder (about 50 nm) was obtained with the ratio CA/NO3- equal to 0.09.

Cernea, M.; Montanari, G.; Galassi, C.; Costa, A. L.

2006-03-01

358

[Doping in sport].  

PubMed

The misuse of therapeutics for doping purposes has always been a serious issue in professional as well as amateur sport. With the introduction of lists containing prohibited substances and methods of doping by international sports federations as well as the International Olympic Committee, doping controls were established that have resulted in numerous adverse analytic findings. Due to the dynamic nature of the pharmaceutical market and constantly growing pool of new therapeutics, sports drug-testing authorities have been urged to expand and improve doping control analytical strategies. Referring to the current list of prohibited substances and methods of doping, effects and side effects of classes of drugs are summarized, and statistics are presented describing positive test results reported during the years 2003-2005. PMID:17694283

Schänzer, Wilhelm; Thevis, Mario

2007-08-15

359

Effect of R(3+) ions on the structure and properties of lanthanum borate glasses  

NASA Technical Reports Server (NTRS)

The present investigation of glass formation in the (mole percent) systems 25La2O3 (x)R2O3 (75-x)B2O3, where R = Al, Ga, and (25-x)La2O3 (x)Ln2O3 75B2O3, where Ln = Gd, Er, Y, notes that up to 25 mol pct Al2O3 or Ga2O3 can be substituted for B2O3, while no more than about 5 mol pct Ln2O3, substituted for La2O3, caused macro-phase separation. The substitution of either R2O3 or Ln2O3 in the lanthanum borate system changes the separation distance between adjacent B3O6 chains. The effect of this structural change on the molar volume, transformation temperature, thermal expansion coefficient, and transformation-range viscosity is discussed.

Chakraborty, I. N.; Day, D. E.

1985-01-01

360

Role of Amorphous Boundary Layer in Enhancing Ionic Conductivity of Lithium–lanthanum–titanate Electrolyte  

SciTech Connect

The low ionic conductivity is a bottleneck of the inorganic solid state electrolyte used for lithium ion battery. In ceramic electrolytes, grain boundary usually dominates the total conductivity. In order to improve the grain boundary effect, an amorphous silica layer is introduced into grain boundary of ceramic electrolytes based on lithium-lanthanum-titanate, as evidenced by electron microscopy. The results showed that the total ionic conductivity could be to be enhanced over 1 x 10{sup -4} S/cm at room temperature. The reasons can be attributed to removing the anisotropy of outer-shell of grains, supplement of lithium ions in various sites in grain boundary and close bindings among grains by the amorphous boundary layer among grains.

Mei, A.; Wang, X.; Lana, J.-L.; Fenga, Y.-C.; Genga, H.-X.; Lina, Y.-H.; Nana, C.-W.

2010-03-01

361

Superconductivity of lanthanum revisited: enhanced critical temperature in the clean limit.  

PubMed

The thickness dependence of the superconducting energy gap ?La of double hexagonally close packed (dhcp) lanthanum islands grown on W(110) is studied by scanning tunneling spectroscopy, from the bulk to the thin-film limit. Superconductivity is suppressed by the boundary conditions for the superconducting wavefunction on the surface and W/La interface, leading to a linear decrease of the critical temperature Tc as a function of the inverse film thickness. For the thick, bulk-like films, ?La and Tc are 40% larger compared to the literature values of dhcp La as measured by other techniques. This finding is reconciled by examining the effects of surface contamination as probed by modifications of the surface state, suggesting that the large Tc originates in the superior purity of the samples investigated here. PMID:25272968

Löptien, P; Zhou, L; Khajetoorians, A A; Wiebe, J; Wiesendanger, R

2014-10-22

362

Effect of Gun Current on Electrical Properties of Atmospheric Plasma-Sprayed Lanthanum Silicate Coatings  

NASA Astrophysics Data System (ADS)

Apatite-type lanthanum silicate (ATLS) electrolyte coatings for use in intermediate-temperature solid oxide fuel cells were deposited by atmospheric plasma spraying (APS). Plasma-sprayed coatings with typical composition La10(SiO4)6O3 exhibiting good densification and high oxide ionic conductivity were obtained by properly adjusting the spraying parameters, particularly the gun current. The highest obtained ionic conductivity value of 3.3 mS/cm at 1,173 K in air is comparable to other ATLS conductors. This work demonstrated empirically that utilization of the APS technique is feasible to synthesize dense La10(SiO4)6O3 electrolyte coatings using gun currents within an unusually broad range.

Gao, Wei; Liao, Han-Lin; Coddet, Christian

2013-10-01

363

Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions and Kinetic Resolution of Resultant ?-Silyloxyketones  

PubMed Central

We report the full account of our efforts on the lanthanum tricyanide-catalyzed acyl silane-ketone benzoin reaction. The reaction exhibits a wide scope in both acyl silane (aryl, alkyl) and ketone (aryl-alkyl, alkyl-alkyl, aryl-aryl, alkenyl-alkyl, alkynyl-alkyl) coupling partners. The diastereoselectivity of the reaction has been examined in both cyclic and acyclic systems. Cyclohexanones give products arising from equatorial attack by the acyl silane. The diastereoselectivity of acyl silane addition to acyclic ?-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant ?-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction. PMID:20392127

Tarr, James C.

2010-01-01

364

Stabilization of ambient sensitive atomic layer deposited lanthanum aluminates by annealing and in situ capping  

NASA Astrophysics Data System (ADS)

We have studied the effect of air exposure on lanthanum aluminates (LaAlOx) deposited by atomic layer deposition. Fourier transform infrared spectroscopy and thermal desorption spectroscopy of as-deposited LaAlOx showed that H2O is absorbed during air exposure and that the amount of absorbed H2O increases with increasing La atomic percent. C was found to be incorporated already during deposition in the form of carbonates. H2O and CO2 are outgassed during postdeposition annealing in an inert atmosphere. After a 700 °C postdeposition anneal, the LaAlOx becomes resistant against H2O absorption due to film densification. Alternatively, in situ capping of the LaAlOx with a ˜2 nm thin Al2O3 film protects the LaAlOx against H2O absorption, but it also hinders the outgassing of the C contaminants during a postdeposition anneal.

Swerts, J.; Gielis, S.; Vereecke, G.; Hardy, A.; Dewulf, D.; Adelmann, C.; Van Bael, M. K.; Van Elshocht, S.

2011-03-01

365

Model-Independent Measurements of Hydrogen Diffusivity in the Lanthanum Dihydride-Trihydride System  

NASA Astrophysics Data System (ADS)

First model-independent measurements of the hydrogen diffusivity D in lanthanum trihydrides LaHx \\(2.00<=x<=3.0\\) have been performed by PFG-NMR. At a fixed concentration x<=2.92, D\\(T\\) shows single Arrhenius behavior over wide temperature ranges. The activation enthalpy decreases with increasing x from 0.55 \\(x = 2.00\\) to 0.17 eV \\(x = 2.92\\), resulting in a strong increase in D. The formation of a hydrogen superstructure associated with the semiconductor-to-metal transition results in a strong reduction in D. It was also observed for the first time that in the stoichiometric limit D depends on the thermal history of the sample.

Majer, G.; Kaess, U.; Barnes, R. G.

1999-07-01

366

Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile  

DOEpatents

A large area directly heated lanthanum hexaboride (LaB/sub 6/) cathode system is disclosed. The system comprises a LaB/sub 6/ cathode element generally circular in shape about a central axis. The cathode element has a head with an upper substantially planar emission surface, and a lower downwardly and an intermediate body portion which diminishes in cross-section from the head towards the base of the cathode element. A central rod is connected to the base of the cathode element and extends along the central axis. Plural upstanding spring fingers are urged against an outer peripheral contact surface of the head end to provide a mechanical and electrical connection to the cathode element. 7 figs

Leung, Ka-Ngo; Gordon, K.C.; Kippenhan, D.O.; Purgalis, P.; Moussa, D.; Williams, M.D.; Wilde, S.B.; West, M.W.

1987-10-16

367

Superconductivity of lanthanum revisited: enhanced critical temperature in the clean limit  

NASA Astrophysics Data System (ADS)

The thickness dependence of the superconducting energy gap ΔLa of double hexagonally close packed (dhcp) lanthanum islands grown on W(110) is studied by scanning tunneling spectroscopy, from the bulk to the thin-film limit. Superconductivity is suppressed by the boundary conditions for the superconducting wavefunction on the surface and W/La interface, leading to a linear decrease of the critical temperature Tc as a function of the inverse film thickness. For the thick, bulk-like films, ΔLa and Tc are 40% larger compared to the literature values of dhcp La as measured by other techniques. This finding is reconciled by examining the effects of surface contamination as probed by modifications of the surface state, suggesting that the large Tc originates in the superior purity of the samples investigated here.

Löptien, P.; Zhou, L.; Khajetoorians, A. A.; Wiebe, J.; Wiesendanger, R.

2014-10-01

368

Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile  

DOEpatents

A large area directly heated lanthanum hexaboride (LaB.sub.6) cathode system (10) is disclosed. The system comprises a LaB.sub.6 cathode element (11) generally circular in shape about a central axis. The cathode element (11) has a head (21) with an upper substantially planar emission surface (23), and a lower downwardly and an intermediate body portion (26) which diminishes in cross-section from the head (21) towards the base (22) of the cathode element (11). A central rod (14) is connected to the base (22) of the cathode element (11) and extends along the central axis. Plural upstanding spring fingers (37) are urged against an outer peripheral contact surface (24) of the head end (21) to provide a mechanical and electrical connection to the cathode element (11).

Leung, Ka-Ngo (Hercules, CA); Gordon, Keith C. (Berkeley, CA); Kippenham, Dean O. (Castro Valley, CA); Purgalis, Peter (San Francisco, CA); Moussa, David (San Francisco, CA); Williams, Malcom D. (Danville, CA); Wilde, Stephen B. (Pleasant Hill, CA); West, Mark W. (Albany, CA)

1989-01-01

369

Photoemission spectroscopy study of the lanthanum lutetium oxide/silicon interface  

SciTech Connect

Rare earth oxides are promising candidates for future integration into nano-electronics. A key property of these oxides is their ability to form silicates in order to replace the interfacial layer in Si-based complementary metal-oxide field effect transistors. In this work a detailed study of lanthanum lutetium oxide based gate stacks is presented. Special attention is given to the silicate formation at temperatures typical for CMOS processing. The experimental analysis is based on hard x-ray photoemission spectroscopy complemented by standard laboratory experiments as Rutherford backscattering spectrometry and high-resolution transmission electron microscopy. Homogenously distributed La silicate and Lu silicate at the Si interface are proven to form already during gate oxide deposition. During the thermal treatment Si atoms diffuse through the oxide layer towards the TiN metal gate. This mechanism is identified to be promoted via Lu-O bonds, whereby the diffusion of La was found to be less important.

Nichau, A.; Schnee, M.; Schubert, J.; Bernardy, P.; Hollaender, B.; Buca, D.; Mantl, S. [Peter Gruenberg Institute 9 (PGI9-IT), Forschungszentrum Juelich, 52425 Juelich (Germany); JARA-Fundamentals of Future Information Technologies, 52425 Juelich (Germany); Besmehn, A.; Breuer, U. [Central Division for Chemical Analysis (ZCH), Forschungszentrum Juelich, 52425 Juelich (Germany); Rubio-Zuazo, J.; Castro, G. R. [Spanish CRG BM25 Beamline-SpLine, European Synchrotron Radiation Facility (ESRF), Rue Jules Horowitz BP 220, F-38043 Grenoble, Cedex 09 (France); Muecklich, A.; Borany, J. von [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum' Dresden-Rossendorf e.V., 01314 Dresden (Germany)

2013-04-21

370

Reducing high phosphate levels in patients with chronic renal failure undergoing dialysis: a 4-week, dose-finding, open-label study with lanthanum carbonate  

Microsoft Academic Search

Background. The majority of patients with end-stage renal disease on dialysis are hyperphosphataemic. Lanthanum carbonate has been shown to be a highly effective phosphate binder in pre-clinical studies. A 4- week, open-label, dose-titration trial was conducted to assess the ability of lanthanum carbonate to control phosphate levels in patients with chronic renal failure. Methods. This preliminary study was of 6

Alastair J. Hutchison; Mary Speake; Fouad Al-Baaj

371

A nuclear magnetic resonance study of amorphous and crystalline lanthanum-aluminates  

SciTech Connect

Lanthanum-aluminates of the composition (1 {minus} x)Al{sub 2}O{sub 3}{center_dot}xLa{sub 2}O{sub 3} (0 < x < 0.7) were prepared by sol-gel synthesis. Subsequent heat-treatment temperatures ranging from 200 to 1,200 C were applied. The resulting samples were characterized by X-ray powder diffraction and {sup 27}Al MAS NMR. The most complex spectra were analyzed by MQMAS NMR in order to get insight in the number of sites and the possible distribution of the NMR parameters in the amorphous samples. Analysis of the MQMAS spectra, taking the efficiency of this experiment for different sites into account, helped to resolve ambiguities in the MAS spectra, which could otherwise not be deconvoluted in a unique way. The analyses show that, except for the sample with the lowest La (x = 0.085) concentration, hardly any pentacoordinated aluminum is observed over the whole temperature treatment range. For all samples the concentration of six-coordinated aluminum decreases as the heating temperature increases until the point where crystallization occurs. The concentration of 4-fold coordinated aluminum shows the opposite behavior. When crystallization occurs, a remarkable transformation between four- and six-coordinated aluminum takes place. Crystallization of the samples occurs at lower temperatures for samples with high amounts of lanthanum. At low La content crystallization is shifted to higher temperatures and thus the lower Al (four and five) coordinations are maintained over a larger temperature range. Storage of the samples in a water-saturated atmosphere leads to a conversion of four- to six-coordinated aluminum. This shows that the low-coordinated Al atoms are accessible to water molecules and must therefore be situated at the surface.

Iuga, D.; Simon, S. [Babes-Bolyai Univ., Cluj-Napoca (Romania)] [Babes-Bolyai Univ., Cluj-Napoca (Romania); Boer, E. de; Kentgens, A.P.M. [Univ. of Nijmegen (Netherlands)] [Univ. of Nijmegen (Netherlands)

1999-09-09

372

Thermionic emission and surface composition of the lanthanum-boron and yttrium-boron systems  

SciTech Connect

At thermionic temperatures, a difference between bulk and surface composition will exist unless the interior happens to be at the congruently vaporizing composition (CVC). Vaporization rates from the surface compete with diffusion rates in the bulk to cause this difference. The surface composition will tend toward the congruently vaporizing composition which is YB/sub 4/ in the yttrium-Boron system and LaB/sub 6/ in the Lanthanum-Boron system. The CVC is also a function of temperature and may vary slightly for the same bulk composition at different temperature. Four Yttrium-Boron (Y-B) compounds, YB/sub 2/ /sub 5/, YB/sub 5/, YB/sub 6/ /sub 4/, YB/sub 14/ and three Lanthanum-Boron (La-B) compounds, LaB/sub 6/ /sub 01/, LaB/sub 8/ /sub 5/ and LaB/sub 5/ /sub 9/ were tested in a variable spacing vacuum emission system with a guard assembly. Emitted current measurements were made with interelctrode potentials between 250 and 1400 volts. Schottky plots were used to extrapolate the zero field currents. When a sample is taken from equilibrium to a new temperature, a definite time lag appears while vaporization rates change to bring about a new equilibrium surface composition. This manifests itself in the recorded emission currents. After thermal equilibrium is reached a distinct change is seen in emission currents. A higher density is measured, reflecting the emission of a surface that has been raised to a higher temperature. But with time, at this temperature, the surface reacts through vaporization and a new composition appears that is closer to the congruently vaporizing composition, and hence, has a work function nearer that of the CVC.

Jaskie, J.E.

1981-12-01

373

Structural and impedance studies of doped LLT materials for electrolytes of lithium-ion batteries  

NASA Astrophysics Data System (ADS)

In order to attain high conductivity, we have to investigate the structural and conductivity studies of novel polycrystalline Lithium Lanthanum Titanate with doping of pentavalent Niobium. The compound Li0.5-xLa0.5NbxTi1-xO3 (x = 0, 0.05, 0.1 and 0.15) (LLTN) having perovskite Cubic structure synthesized by ceramic technology. The crystalline phase identification and determination of lattice parameters of each sample were carried out by X-ray diffraction (XRD) analysis. The Raman Spectra were performed to understand the bonding nature of these materials. The lithium-ion conductivity and dielectric constant of the compound have been determined with AC impedance spectroscopy.

Babu, K. Vijaya; Veeraiah, V.; Rao, P. S. V. Subba

2012-06-01

374

Effects of cation substitution on thermal expansion and electrical properties of lanthanum chromites  

Microsoft Academic Search

The effects of cation substitution on the sintering characteristics, thermal expansion and electrical conductivity properties of La(AE)Cr(M)O3 (AEMg, Ca, Sr, MNi, Cu, Co) were investigated. The sinterability of alkaline metal earth (AE)-doped LaCrO3 increased with AE contents in a sequence of Ca>Sr>Mg. Sr-doped LaCrO3 sample had a TEC compatible with that of 8YSZ electrolyte. The transition metals of Ni, Co

Xifeng Ding; Yingjia Liu; Ling Gao; Lucun Guo

2006-01-01

375

Studies on Ca2+-Doped CeBr3 Scintillating Materials  

SciTech Connect

Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide (LaBr3:Ce), their commercial availability and application is limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. The objective of this investigation was to employ aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was investigated as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were investigated using the density functional theory within generalized gradient approximation. The calculated lattice parameters are in good agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

Guss, P. [NSTec; Foster, M. E. [SNL; Wong, B. M. [SNL; Doty, F. P. [SNL; Shah, K. [RMD; Squillante, M. R. [RMD; Shirwadkar, U. [RMD; Hawrami, R. [RMD; Tower, J. [RMD; Yuan, D. [NSTec

2013-09-01

376

Photometric determination of micro amounts of thiosulphate by means of its cyanolysis with lanthanum(III) as catalyst.  

PubMed

Lanthanum(III) has been found to catalyse the reaction of thiosulphate with cyanide. The effects of pH, reaction time and temperature, amount of cyanide and lanthanum, and order of addition of reagents have been investigated. Temperature has little effect in the range 10-30 degrees , but at both 35 degrees and 40 degrees the rate is noticeably faster. Reaction is complete at room temperature in 1.5 hr at pH 9.3-9.6, and in 3 hr at pH 9.1-9.6. The method can be applied to the determination of 1.0 x 10(-5)-6.0 x 10(-4)M thiosulphate, with a relative standard deviation of 0.3% for 4 x 10(-4)M thiosulphate. PMID:18962194

Koh, T; Miura, Y; Katoh, M

1977-12-01

377

Performance of a Lanthanum Bromide Detector and a New Conception Collimator for Radiopharmaceuticals Molecular Imaging in Oncology  

NASA Astrophysics Data System (ADS)

We have realized and tested a new-design compact gamma camera for high resolution SPET (Single Photon Emission Tomography), and small animals' radio-pharmaceutical molecular imaging. The camera is based on a "continuous" Lanthanum tri-Bromide crystal, and a new Low Energy (LE) collimator. The crystal is interfaced to a 2×2 array of Hamamatsu-H8500 position sensitive photo-multipliers. The lead collimator features parallel hexagonal 1.0 mm holes, 18 mm length, 0.2 mm septa and 10×10 cm2 detection area. It was newly designed to fully exploit the high spatial resolution a Lanthanum crystal may provide. To better evaluate its role, we have compared our camera to three other systems with similar crystals and photomultipliers, but employing traditional collimators, either pinhole or parallel. The new camera seems to be complementary to pinhole systems and shows a very attractive trade-off between spatial resolution and detection area.

Pani, Roberto; Pellegrini, Rosanna; Bennati, Paolo; Cinti, Maria Nerina; Scafè, Raffaele; De Vincentis, Giuseppe; Navarria, Francesco; Moschini, Giuliano; Cencelli, Valentino Orsolini; De Notaristefani, Francesco; Rossi, Paolo

2009-03-01

378

Oxygen vacancy formation and annihilation in lanthanum cerium oxide as a metal reactive oxide on 4H-silicon carbide.  

PubMed

A mechanism regarding the redox reaction in lanthanum cerium oxide (LaxCeyOz) post-deposition annealed in reducing and oxidizing atmosphere was schematized and discussed in association with the presence of lanthanum as a substitutional cation. Analyses have been performed using X-ray diffraction, energy-filtered transmission electron microscopy, scanning transmission electron microscope-energy dispersive spectroscopy line scan, and capacitance-voltage measurements. The results showed the presence of an oxygen vacancy when La(3+) was in its substitution site, while annihilation of oxygen vacancy was accompanied by a displacement of La(3+) from the substitutional site to the interstitial site via a kick-out mechanism prior to its disappearance from the CeO2. PMID:24603767

Lim, Way Foong; Cheong, Kuan Yew

2014-04-21

379

Performance of a Lanthanum Bromide Detector and a New Conception Collimator for Radiopharmaceuticals Molecular Imaging in Oncology  

SciTech Connect

We have realized and tested a new-design compact gamma camera for high resolution SPET (Single Photon Emission Tomography), and small animals' radio-pharmaceutical molecular imaging. The camera is based on a 'continuous' Lanthanum tri-Bromide crystal, and a new Low Energy (LE) collimator. The crystal is interfaced to a 2x2 array of Hamamatsu-H8500 position sensitive photo-multipliers. The lead collimator features parallel hexagonal 1.0 mm holes, 18 mm length, 0.2 mm septa and 10x10 cm{sup 2} detection area. It was newly designed to fully exploit the high spatial resolution a Lanthanum crystal may provide. To better evaluate its role, we have compared our camera to three other systems with similar crystals and photomultipliers, but employing traditional collimators, either pinhole or parallel. The new camera seems to be complementary to pinhole systems and shows a very attractive trade-off between spatial resolution and detection area.

Pani, Roberto; Pellegrini, Rosanna [Dep. of Experimental Medicine, 'Sapienza' University of Rome and INFN, p.le Aldo Moro 5, Rome 00185 (Italy); Bennati, Paolo; Cinti, Maria Nerina [Department of Physics, 'Sapienza' University of Rome and INFN, p.le Aldo Moro 5, Rome 00185 (Italy); Scafe, Raffaele [INFN and ENEA, via Anguillarese 301, Casaccia (Rome) 00060 (Italy); De Vincentis, Giuseppe [Department of Radiology, 'Sapienza' University of Rome, p.le Aldo Moro 5, Rome 00185 (Italy); Navarria, Francesco [Department of Physics, University of Bologna and INFN, via Zamboni, 33, Bologna 40126 (Italy); Moschini, Giuliano; Rossi, Paolo [Department of Physics, University of Padova and INFN, via Marzolo 8, Padova 35131 (Italy); Cencelli, Valentino Orsolini; De Notaristefani, Francesco [Department of Electronic Engineering, University 'Roma 3', via della Vasca Navale 84, Rome 00146 (Italy)

2009-03-10

380

De Haas-van Alphen oscillations in the charge-density wave compound lanthanum tritelluride (LaTe3)  

SciTech Connect

De Haas-van Alphen oscillations were measured in lanthanum tritelluride (LaTe{sub 3}) to probe the partially gapped Fermi surface resulting from charge density wave (CDW) formation. Three distinct frequencies were observed, one of which can be correlated with a FS sheet that is unaltered by CDW formation. The other two frequencies arise from FS sheets that have been reconstructed in the CDW state.

Ru, N.; /Stanford U., Geballe Lab.; Borzi, R.A.; Rost, A.; Mackenzie, A.P.; /St. Andrews U., Phys. Astron.; Laverock, J.; Dugdale, S.B.; /Bristol U.; Fisher, I.R.; /Stanford U., Geballe Lab.

2009-12-14

381

Nickel catalysts promoted with cerium and lanthanum to reduce carbon formation in partial oxidation of methane reactions  

Microsoft Academic Search

Mixed oxides of nickel, magnesium and aluminum were prepared by precursors hydrotalcite type and were substituted by lanthanum or cerium using the method of anion exchange. The catalysts were characterized by X-Ray Photoelectronic Spectroscopy (XPS); Energy Dispersive X-Ray Spectroscopy (EDS); Surface Area Method BET; X-Ray Diffraction (XRD); Temperature Programmed Reduction (TPR) and Catalytic Tests. Analysis of the mixed oxides suggests

Alessandra Fonseca Lucrédio; Gregory Jerkiewickz; Elisabete Moreira Assaf

2007-01-01

382

Long-Term Efficacy and Safety Profile of Lanthanum Carbonate: Results for up to 6 Years of Treatment  

Microsoft Academic Search

Background\\/Aims: Lanthanum carbonate (LC, FOSRENOL®) is an effective phosphate binder for which tolerability and a safety profile have been reported in haemodialysis patients. Patients from previous studies entered a 2-year extension, enabling assessment of efficacy and safety for up to 6 years of LC monotherapy. Methods: Patients from four previous trials entered this study. Results: Ninety-three patients started the extension,

Alastair J. Hutchison; M. Edwina Barnett; Rolfdieter Krause; Jonathan T. C. Kwan; Ghodrat A. Siami

2008-01-01

383

Microstructure and electrical properties of lanthanum nickel oxide thin films deposited by metallo-organic decomposition method  

Microsoft Academic Search

Lanthanum nickel oxide (LaNiO3:LNO) thin films were grown on SiO2\\/Si substrates by a metallo-organic decomposition method, and their crystalline structure, microstructure and electrical properties were investigated. X-ray diffraction analysis indicated that fully (100)-oriented perovskite LaNiO3 films could be obtained by annealing at 600°C. Transmission electron microscopy (TEM) images showed that the films consisted of packed grains with a mean grain

Zhan Jie Wang; Toshihide Kumagai; Hiroyuki Kokawa

2006-01-01

384

Doping and Fair Play  

Microsoft Academic Search

The conventional approach to the economic analysis of doping in sport is that athletes are typically involved in a Prisoner’s Dilemma-type interaction (Breivik 1987, Bird and Wagner 1997, Eber and Thépot 1999, Haugen 2004).1 The idea is straightforward: doping being a dominant strategy (i.e., yielding a preferred outcome regardless of the strategy used by the competitor), each athlete finds it

Nicolas Eber

2009-01-01

385

Enhanced visible light activity of nano-titanium dioxide doped with multiple ions: Effect of crystal defects  

SciTech Connect

Titanium dioxide photocatalysts co-doped with iron(III) and lanthanum(III) have been prepared through a modified sol-gel method. Doping with Fe{sup 3+} resulted in a relatively lower anatase to rutile phase transformation temperature, while La{sup 3+} addition reduced the crystal growth and thus retarded the phase transformation of titania nanoparticles. The presence of Fe{sup 3+} ions shifted the absorption profile of titania to the longer wavelength side of the spectrum and enhanced the visible light activity. On the other hand, La{sup 3+} addition improved the optical absorption of titania nanoparticles. Both the dopants improved the life time of excitons by proper transferring and trapping of photoexcited charges. In the present work, considerable enhancement in photocatalytic activity under visible light was achieved through synergistic effect of optimum concentrations of the two dopants and associated crystal defects. - Graphical abstract: Photocatalytic activity studies indicate a synergistic effect of dopants and crystal defects leading to an enhanced photochemical activity. Highlights: Black-Right-Pointing-Pointer An aqueous sol-gel synthesis of Fe{sup 3+} and La{sup 3+} co-doped TiO{sub 2} is being reported. Black-Right-Pointing-Pointer Optical and microstructural properties of titania were modified by co-doping. Black-Right-Pointing-Pointer Enhanced activity of titania by the crystal defects is being reported.

Jaimy, Kanakkanmavudi B. [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India)] [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India); Ghosh, Swapankumar, E-mail: swapankumar.ghosh2@mail.dcu.ie [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India)] [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India); Gopakumar Warrier, Krishna, E-mail: wwarrierkgk@yahoo.co.in [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India)

2012-12-15

386

Writing of nonlinear optical Sm{sub 2}(MoO{sub 4}){sub 3} crystal lines at the surface of glass by samarium atom heat processing  

SciTech Connect

Some glasses such as 21.25Sm{sub 2}O{sub 3}.63.75MoO{sub 3}.15B{sub 2}O{sub 3} (mol %) giving the formation of nonlinear optical Sm{sub 2}(MoO{sub 4}){sub 3} crystals through conventional crystallization in an electric furnace and through continuous-wave Nd: yttrium aluminum garnet (YAG) laser (wavelength: 1064 nm) irradiation (samarium atom heat processing) have been developed. It is proposed from x-ray diffraction analyses, micro-Raman-scattering spectra, and second-harmonic generation measurements that the crystal structure of Sm{sub 2}(MoO{sub 4}){sub 3} formed by the crystallization is the {beta}{sup '}-phase structure with an orthorhombic (noncentrosymmetric) symmetry. The lines consisting of nonlinear optical {beta}{sup '}-Sm{sub 2}(MoO{sub 4}){sub 3} crystals are written at the surface of glasses by YAG laser irradiation (laser power: P=0.4 W, laser scanning speed: S=1-10 {mu}m/s), and, in particular, homogeneous crystal lines are formed at the laser scanning speed of 1 {mu}m/s. Refractive index changes (not crystallization) are also induced by YAG laser irradiation of P=0.4 W and a high laser scanning speed of S=25 {mu}m/s. The crystallization mechanism in the laser-irradiated region has been proposed. The present study demonstrates that the samarium atom heat processing is a technique for the writing of rare earth containing optical nonlinear/ferroelectric crystal lines in glass.

Abe, M.; Benino, Y.; Fujiwara, T.; Komatsu, T.; Sato, R. [Department of Chemistry, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan); Department of Materials Engineering, Tsuruoka National College of Technology, Tsuruoka 997-8511 (Japan)

2005-06-15

387

Lanthanum carbonate prevents accelerated medial calcification in uremic rats: role of osteoclast-like activity  

PubMed Central

Background Arterial medial calcification (AMC) is frequent prevalence in patients with end stage renal disease. Evidence about hyperphosphatemia induced anabolic crosstalk between osteoblast and osteoclast in AMC of uremia is rare. Lanthanum carbonate as an orally administered phosphate-binding agent to reduce phosphate load and ameliorate AMC, but direct evidence is missing. Methods Detailed time-course studies were conducted of Sprague–Dawley rats fed with adenine and high phosphate diet to imitate the onset and progression of AMC of uremia. Calcification in great arteries was evaluated by VonKossa’s and Masson's trichrome staining. Osteoblast (Runx2, Osteocalcin) and osteoclast (RANKL, Cathepsin K, TRAP) related genes were analyzed by Immunohistochemistry and qRT-PCR. Serum PTH, RANKL and OPG levels were detected by ELISA kit. Results Serum phosphate was markedly increased in CRF group (6.94?±?0.97 mmol/L) and 2%La group (5.12?±?0.84 mmol/L) at week 4, while the latter group diminished significantly (2.92?±?0.73 mmol/L vs CRF Group 3.48?±?0.69, p?Lanthanum carbonate could be mainly due to the decreased phosphate retention and cross-talk between osteoblast and osteoclast-like cell, both of which can be the therapeutic target for uremia associated with AMC. PMID:24330832

2013-01-01

388

Photo-induced self-cleaning and sterilizing activity of Sm3+ doped ZnO nanomaterials.  

PubMed

Highly active samarium doped zinc oxide self-cleaning and biocidal surfaces (x mol% Sm(3+)/ZnO where x=0, 1, 2 and 4 mol%) with crystalline porous structures were synthesized by hydrothermal method. Sm(3+)/ZnO thin films were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive spectroscopic (EDS), UV-visible diffuse reflectance and fluorescence (FL) spectroscopy. The combination between doping and hydrothermal treatments significantly altered the morphology of ZnO into rod and plate-like nanoshapes structure and enhanced its absorption and emission of ultraviolet radiation. The photo-activity in term of quantitative determination of the active oxidative species (()OH) produced on the thin film surfaces was evaluated using fluorescent probe method. The results showed that, the hydrothermally treated 2.0 mol% Sm(3+)/ZnO film (S2) is the highly active one. The optical, structural, morphology and photo-activity properties of the highly active thin film (S2) make it promising surface for self-cleaning and sterilizing applications. PMID:23123120

Saif, M; Hafez, H; Nabeel, A I

2013-01-01

389

Structure and properties of WO3-doped Pb0.97La0.03(Zr0.52Ti0.48)O3 ferroelectric thin films prepared by a sol-gel process  

Microsoft Academic Search

Lanthanum-modified lead zirconate titanate Pb0.97La0.03(Zr0.52Ti0.48)O3 doped with x at. % WO3 (x=0, 0.2, 0.5, 1, and 2) (PLWZT) ferroelectric thin films have been deposited on Pt\\/Ti\\/SiO2\\/Si substrates using a sol-gel spin-coating process. We have demonstrated that WO3 dopant plays a significant role on the structure and electrical properties of the PLWZT films. The x-ray-diffraction analysis shows that the PLWZT films

Santiranjan Shannigrahi; Kui Yao

2005-01-01

390

Micropatterned epitaxial (Pb,La)(Zr,Ti)O3 thin films on Nb-doped SrTiO3 substrates by a chemical solution deposition process with resist molds  

NASA Astrophysics Data System (ADS)

Arrays of lead lanthanum zirconate titanate pillars were fabricated on niobium-doped (001) strontium titanate substrates using a chemical solution deposition method with resist molds. Periodic arrays of submicron ferroelectric pillars with high crystallinity are required to produce high-quality tunable photonic-crystal devices. The relationship between the crystallinity and width of the pillars was investigated. The highest crystallinity was obtained at a width of 0.67?m. All the pillars exhibited ferroelectric strain. Since this width is in the order of that of optical wavelengths, this process and the periodic structures produced have potential applications in fabricating two-dimensional tunable photonic crystals.

Aoki, Tsuyoshi; Kuwabara, Makoto; Kondo, Masao; Tsukada, Mineharu; Kurihara, Kazuaki; Kamehara, Nobuo

2004-09-01

391

[Doping in sports].  

PubMed

The first organized doping controls were carried out in the 1970s. In 1993, the Czech Antidoping Charter was signed and the Antidoping Committee was established. The medical commission of International Olympic Committee decides, which substances and methods are prohibited. The current classification is as follows: I. prohibited classes of substances--stimulants, narcotics, anabolic agents, diuretics and some hormones. II. prohibited methods--blood doping and pharmaceutical, chemical or physical manipulation. III. classes of drugs subject to certain restrictions--alcohol, marijuana, local anesthetics, corticosteroids and beta blockers. All substances are characterized from the ergogenic viewpoint and health risks are particularly emphasized. In practice, doping control starts by drawing the athletes and ends by urine sample analysis in a special laboratory. In case of positive results, the sportsman is banned from sports activity for 3 months, 2 years or for the rest of his life. In 24 worldwide laboratories in 1995 93,938 urine samples were analyzed. 1516 (1.61%) proved to be positive, including 986 anabolic steroid use. In 1997, the Czech laboratory carried out 843 checks, of which 15 (1.7%) were positive. The largest positive doping group were body builders. Doping poses a major risk among junior sportsmen. Prevalence worldwide is estimated at 2-10% of the male population. In the future a severe antidoping attitude, as well as antidoping enlightenment, are certain to continue. By these standards the activity of the Czech Antidoping Committee is on a very high level. PMID:10422337

Jeschke, J; Nekola, J; Chlumský, J

1999-05-10

392

Improvement of MBD parameters in dialysis patients by a switch to, and combined use of lanthanum carbonate: Josai Dialysis Forum collaborative study.  

PubMed

The effects of lanthanum carbonate on MBD parameters were investigated in 59 hemodialysis patients who were taking calcium carbonate. Lanthanum carbonate (initial dosage: 750?mg/day), as a replacement for or in combination with calcium carbonate and/or sevelamer hydrochloride, was administered for 12 months with increase/decrease of dosages. Lanthanum carbonate replaced calcium carbonate for 21 cases and was co-administered in 38 cases. It replaced sevelamer hydrochloride in 20 cases and was co-administered in 10 cases. Both the number of cases to which calcium carbonate was administered and their dosages decreased to about 70-80% 12 months after the initiation, and cases administered sevelamer decreased to about 30%. In the cases for which lanthanum carbonate was co-administered, the dosages of calcium carbonate and sevelamer slightly decreased. A significant decrease in serum calcium level was observed. In the serum phosphorus levels (P levels), significant decrease compared with the initial level was observed only at six and nine months. Intact parathyroid hormone (iPTH) level remained stable at around 230?pg/mL without significant change. The dosage of vitamin D and cinacalcet remained without significant change. The results of this trial suggest that, if dosages of vitamin D and cinacalcet are adequately controlled, a switch to lanthanum carbonate and its concomitant use are effective to control the Ca and P levels without changing iPTH levels. PMID:23586510

Shinoda, Toshio; Yamasaki, Masahiro; Chida, Yoshiko; Takagi, Masao; Tanaka, Yoshiko; Ando, Ryoichi; Suzuki, Toshiaki; Tagawa, Hitoshi

2013-04-01

393

On the polymorphism in lanthanum polysulfide (LaS{sub 2})  

SciTech Connect

The polymorphism in lanthanum polysulfide (LaS{sub 2}) was investigated using X-ray diffraction and vibrational spectroscopy. Samples were prepared by traditional solid state techniques and by a method based on high pressure CS{sub 2} treatment, and then subjected to various heating and cooling schedules. In agreement with previous work, monoclinic ({alpha}) and orthorhombic ({beta}) forms were found, and a new tetragonal polymorph ({gamma}) with the anti-Fe{sub 2}-As structure was obtained in some synthesis runs. Unlike previous findings, no reversible transition between the {alpha} and {beta} phases was observed. The tetragonal {gamma} phase is most likely a spatially averaged disordered structure, with local symmetry lower then tetragonal. The CS{sub 2}, synthesis method gave rise to a disordered version of the monoclinic {alpha} phase, with broadened diffraction peaks. This material was slightly paramagnetic at room temperature and showed evidence for antiferromagnetic ordering below 50 K, unlike the ordered {alpha} and {beta} phases, which were diamagnetic at all temperatures. Low-temperature EPR and Raman spectroscopy indicates that the behavior of the disordered {alpha}-LaS{sub 2} is due to the presence of paramagnetic S{sup {minus}} defects and rapid S-S bond switching in the S-S basal planes.

Le Rolland, B.; Colombet, P. [Groupe Les Ciments Francais-Italcimenti, Guerville (France)] [Groupe Les Ciments Francais-Italcimenti, Guerville (France); Molinie, P. [CNRS, Nantes (France)] [CNRS, Nantes (France); McMillan, P.F. [Arizona State Univ., Tempe, AZ (United States)] [Arizona State Univ., Tempe, AZ (United States)

1994-12-01

394

The interfaces of lanthanum oxide-based subnanometer EOT gate dielectrics  

NASA Astrophysics Data System (ADS)

When pushing the gate dielectric thickness of metal-oxide-semiconductor (MOS) devices down to the subnanometer scale, the most challenging issue is the interface. The interfacial transition layers between the high- k dielectric/Si and between the high- k dielectric/gate metal become the critical constraints for the smallest achievable film thickness. This work presents a detailed study on the interface bonding structures of the tungsten/lanthanum oxide/silicon (W/La2O3/Si) MOS structure. We found that both W/La2O3 and La2O3/Si are thermally unstable. Thermal annealing can lead to W oxidation and the forming of a complex oxide layer at the W/La2O3 interface. For the La2O3/Si interface, thermal annealing leads to a thick low- k silicate layer. These interface layers do not only cause significant device performance degradation, but also impose a limit on the thinnest equivalent oxide thickness (EOT) to be achievable which may be well above the requirements of our future technology nodes.

Wong, Hei; Zhou, Jian; Zhang, Jieqiong; Jin, Hao; Kakushima, Kuniyuki; Iwai, Hiroshi

2014-09-01

395

Experimental and theoretical study on interaction between lanthanum and nitrogen during plasma rare earth nitriding  

NASA Astrophysics Data System (ADS)

In present work, the interaction between lanthanum (La) and nitrogen (N) during plasma rare earth nitriding of M50NiL martensitic steel is analyzed. Phase compositions, elemental contents as well as microhardness profiles of surface layers are investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and microhardness tester to observe the changes of the N contents in treated layers. The results of microhardness, XRD and EDS indicate that the addition of pure La can speed up the denitriding rate compared with the case without La addition. The XPS results reveal that the presence of the Lasbnd O and Lasbnd N bond reduces the peak intensity of the Mesbnd N bond, which indicates that the addition of La element can reduce the N contents in nitrided layers through the surface oxidation and the attraction of La atoms. The theoretical thermodynamic calculations are employed to further clarify the denitriding function of the surface oxidation and the attraction between La and N atoms.

Zhang, C. S.; Yan, M. F.; Sun, Z.

2013-12-01

396

Highly selective water adsorption in a lanthanum metal-organic framework.  

PubMed

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]?2?H2O, is microporous, with 1D channels that easily accommodate water molecules. Its framework is highly robust to dehydration/hydration cycles. Unusually for a MOF, it also features a high hydrothermal stability. This makes it an ideal candidate for air drying as well as for separating water/alcohol mixtures. The ability of the activated MOF to adsorb water selectively was evaluated by means of thermogravimetric analysis, powder and single-crystal X-ray diffraction and adsorption studies, indicating a maximum uptake of 1.2?mmol?g(-1) MOF. These results are in agreement with the microporous structure, which permits only water molecules to enter the channels (alcohols, including methanol, are simply too large). Transient breakthrough simulations using water/methanol mixtures confirm that such mixtures can be separated cleanly using this new MOF. PMID:24867871

Plessius, Raoul; Kromhout, Rosa; Ramos, André Luis Dantas; Ferbinteanu, Marilena; Mittelmeijer-Hazeleger, Marjo C; Krishna, Rajamani; Rothenberg, Gadi; Tanase, Stefania

2014-06-23

397

Multicenter study on the long-term (3-year) efficacy of lanthanum carbonate in dialysis patients.  

PubMed

We previously conducted a multicenter study enrolling 101 dialysis patients with hyperphosphatemia in which lanthanum carbonate (LC) was administered for 2 years. In this study, the administration has been continued for an additional year, and we have evaluated the long-term (a total of 3 years) effects of LC. The average serum phosphorus (P) level was 6.05 mg/dL at the start and decreased to 5.84 mg/dL after 3 years, but no significant differences were observed at both points. The average serum corrected calcium (Ca) level significantly reduced after 3 years (P < 0.001). As results of evaluating the achievement rates with the management target values of serum P, Ca and intact parathyroid hormone (PTH) stated in the Japanese guideline, the achievement rates increased after 3 years. From these results, LC is considered to be a useful P binder that can be used for long-term treatment of hyperphosphatemia, without causing a Ca load. PMID:24953759

Ando, Ryoichi; Yama, Satomi; Ohnishi, Tsuyoshi; Iwamoto, Shunsuke; Kimura, Hitoshi; Chida, Yoshiko; Ishida, Yuji; Yamada, Kouei; Inagaki, Yuichiro; Takayama, Masanobu; Tachibana, Ken; Kikuchi, Kan; Inoue, Atsushi; Ohtsuka, Masakazu

2014-06-01

398

Synthesis, characterization, and catalytic activity of Rh-based lanthanum zirconate pyrochlores for higher alcohol synthesis  

SciTech Connect

Two lanthanum zirconate pyrochlores (La{sub 2}Zr{sub 2}O{sub 7}; LZ) were prepared by Pechini method and tested for higher alcohols selectivity. In one, Rh was substituted into the pyrochlore lattice (LRZ, 1.7 wt%) while for the second, Rh was supported on an unsubstituted La{sub 2}Zr{sub 2}O{sub 7} (R/LZ, 1.8 wt%). X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR) results show that the surface reducibility depends on whether the Rh is in (or supported on) the LZ pyrochlore. Rhodium in the LRZ is more reducible than rhodium supported on the R/LZ pyrochlore, likely due to the presence of a perovskite phase (LaRhO{sub 3}; identified by XRD), in which rhodium is more reducible. The formation of the perovskite accompanies that of the pyrochlore. CO hydrogenation results show higher ethanol selectivity for R/LZ than LRZ, possibly due to the strong interaction between Rh and LZ on the R/LZ, forming atomically close Rh{sup +}/Rh{sup 0} sites, which have been suggested to favor ethanol production.

Abdelsayed, Victor; Shekhawat, Dushyant; Poston, James A., Jr.; Spivey, James J.

2013-05-01

399

Electric-field-temperature phase diagram of the relaxor ferroelectric lanthanum-modified lead zirconate titanate  

NASA Astrophysics Data System (ADS)

Transition lines between various phases in the electric-field-temperature phase diagram of 9/65/35 lanthanum-modified lead zirconate titanate ceramics were determined by measurements of the temperature and electric-field-dependent dielectric constant. Above a critical field (EC) the dc bias electric field induces a transition from the relaxor (R) to the long-range ferroelectric (FE) phase. In the temperature direction of the approach to the FE phase the R-FE transition line was determined from the field-cooled-field-heated dielectric susceptibilities, while depolarization temperatures were obtained from the field-cooled-zero-field-heated dielectric susceptibilities. A considerably large shift was found for the above two R-FE transition lines demonstrating the strong impact of the electric field on the stability of the FE phase with increasing temperature. It was found that below EC ergodicity is broken due to the divergence of the longest relaxation time at the freezing temperature T0=259 K. Hence the system exhibits a transition line between the ergodic (ER) and nonergodic (NR) relaxor state. In the dc bias field direction of the approach to the FE phase, the temperature dependence of EC, i.e., the transition lines between ER or NR and FE phases were studied by measurements of the complex dielectric constant as a function of a dc bias field at several fixed temperatures. The experimental results are compared with the results of a spherical random bond-random field model of relaxor ferroelectrics.

Bobnar, Vid; Kutnjak, Zdravko; Pirc, Raša.; Levstik, Adrijan

1999-09-01

400

Additional reduction in serum phosphorus levels by pulverized lanthanum carbonate chewable in hemodialysis patients.  

PubMed

Lanthanum carbonate (LC) is one of the relatively new phosphate binders. The general LC dosage form is a chewable pharmaceutical preparation. This investigation was targeted to subjects who do not chew LC chewable preparations adequately, for the purpose of studying the clinical efficacy of changing to pulverized prescriptions, such as changes in serum phosphorus levels (P levels). The study took place at Minamisenju Hospital in October 2011, with 41 subjects on maintenance hemodialysis. We pulverized all of the LC chewable medicines of the LC insufficient mastication group (non-chewing: NC group, n?=?18) using a crusher, and changed them to pulverized prescriptions. The testing period was set at 10 weeks. In the NC group, there was a significant lowering of P levels from 5.86?±?1.31?mg/dL before pulverization of the LC chewable preparation (week 0) to 5.38?±?1.26?mg/dL after 2 weeks of administration of the pulverized medication (P?=?0.0310), 5.20?±?1.25?mg/dL after 4 weeks (P?=?0.0077), and 5.12?±?1.34?mg/dL after 6 weeks (P?=?0.0167). P levels in other patients than NC group showed no significant change. In this study, the P levels in the NC group was lowered significantly by changing the LC chewable to the pulverized prescription, and the residual LC images on the abdominal X-rays disappeared to the point where they could barely be confirmed. PMID:23586514

Yamashita, Tetsuri; Ogawa, Tetsuya; Takahashi, Masaki; Mitsuhashi, Tetsuya; Shizuku, Junichi; Takahashi, Naoshi; Ohba, Takashi; Miyajima, Sayako; Kabaya, Takashi; Otsuka, Kuniaki; Nitta, Kosaku

2013-04-01

401

Vibrational Spectroscopy of Adsorbates on the (111) and (100) Surfaces of Lanthanum Hexaboride  

NASA Astrophysics Data System (ADS)

Reflection absorption infrared spectroscopy has been used to study the adsorption of carbon monoxide, oxygen, and decaborane on the (100) and (111)adsorption of carbon monoxide, oxygen, and decaborane on the (100) and (111) surfaces of lanthanum hexaboride. Exposure of the surface at temperatures of 95 K and above to O2 produces atomic oxygen on the surface and yields vibrational peaks in good agreement with those observed previously with the technique of high resolution electron energy loss spectroscopy (HREELS). As in the previous HREELS studies, the peaks observed in response to oxygen adsorption are assigned to vibrations of the B6 octahedra that gain intensity due to a decrease in electronic screening of surface dipoles. In the case of CO, molecular adsorption occurs at 95 K and gives rise to a variety of C-O stretch peaks, depending on adsorption site.Decaborane adsorbs molecularly at 95 K and gives rise to intense peaks in the B-H stretch region that evolve with annealing temperature into a single peak at 2571cm-1 due to an unidentified surface intermediate possessing BH bonds.

Yorisaki, Thomas; Tillekaratne, Aashani; Moriya, Yukihiro; Oshima, Chuhei; Otani, Shigeki; Trenary, Michael

402

Is granular formulation of lanthanum carbonate more effective than chewable tablets?  

PubMed

Maintenance dialysis patients at our hospital who had been receiving lanthanum carbonate (LC) chewable tablets were switched to the same dosage of the granules, and the differences in serum phosphorus (P) levels were compared, together with stratifying patients at the baseline characteristics. Compared to average serum P level of 5.48 mg/dL for 2 months prior to switching, the average level for 2 months after switching was 4.99 mg/dL (P = 0.049). For patients who were under 60, serum P levels were significantly improved after switching (P = 0.016), and for patients who were concomitantly taking many kinds of medications, a correlation to high reductions of serum P level after switching was shown (R = -0.635, P = 0.015). In order to maximize pharmaceutical potential of LC, we think that it is not only necessary to provide patients with how to take the medication, but it is also important to take into consideration the patients' baseline characteristics. PMID:24953763

Okamoto, Hidekazu; Haruhara, Koutarou; Kamejima, Sahoko; Mafune, Hana; Manabe, Mayumi; Kanzaki, Goh; Mashiko, Hiroshi; Yokoo, Takashi

2014-06-01

403

Effects of change in the formulation of lanthanum carbonate on laboratory parameters.  

PubMed

Lanthanum carbonate (LC) is available in the two formulations of chewable tablets and granules. In this study, we changed the formulation of LC from chewable tablet to granules, and compared the laboratory parameters for 3 months before and after changing formulation in 58 hemodialysis (HD) patients. We also surveyed patients about their preferences for the two formulations. The mean serum phosphorus (P) levels decreased significantly (P < 0.01) from 6.7 mg/dL to 6.4 mg/dL after the change. The levels for serum albumin and geriatric nutritional risk index increased significantly (P < 0.01). Serum calcium levels also increased significantly (P < 0.01), while serum intact parathyroid hormone levels decreased significantly (P < 0.01). In the survey, approximately half of the patients responded that the granules were easier to take than the chewable tablets. These findings suggest that changing the formulation of LC to granules may reduce serum P levels of the HD patients in clinical practices. PMID:24953762

Takita, Takako; Furuhashi, Mitsuyoshi; Fujimoto, Taiki; Suzuki, Hiroo; Harada, Masaki; Maruyama, Satoshi; Tamiya, Rika; Kamiya, Eri; Okamoto, Mari; Tukada, Atsuyo; Furuhashi, Mikako; Kato, Akihiko

2014-06-01

404

Effects of switching from calcium carbonate to lanthanum carbonate on bone mineral metabolism in hemodialysis patients.  

PubMed

Phosphate binders are useful for the treatment of hyperphosphatemia in hemodialysis (HD) patients. This study was performed to examine the effects of switching from calcium carbonate (CC) to lanthanum carbonate (LC) on bone mineral metabolism and inflammatory markers in HD patients. We conducted 29 stable HD patients receiving CC, which was replaced by LC and followed-up for 12 weeks. Patients underwent determinants of blood chemistries such as serum calcium (Ca), phosphorus, parathyroid hormone (PTH) and vitamin D status, and interleukin-6 (IL-6) mRNA levels in whole blood cells were evaluated by real-time PCR just before and after the treatment with LC. Corrected Ca [corrected] levels were significantly reduced, but serum phosphorus levels (P levels) were unchanged after LC treatment. Switching to LC increased whole-PTH, osteocalcin, 1,25(OH)(2) D(3) levels and 1,25(OH)(2) D(3)/25(OH)D(3) ratio. 1,25(OH)(2) D(3)/25(OH)D(3) ratio was negatively correlated with HD duration. Furthermore, whole blood cell IL-6 mRNA levels were significantly reduced by LC treatment. We provided that the switching from CC to LC improved Ca overload and ameliorated vitamin D and inflammatory status in HD patients. These observations suggest that LC may play a protective role for the progression of atherosclerosis and vascular calcification in these patients. PMID:23586511

Manabe, Rie; Fukami, Kei; Ando, Ryotaro; Sakai, Kazuko; Kusumoto, Takuo; Hazama, Takuma; Adachi, Takeki; Kaida, Yusuke; Nakayama, Yosuke; Ueda, Seiji; Kohno, Keisuke; Wada, Yoshifumi; Yamagishi, Sho-ichi; Okuda, Seiya

2013-04-01

405

Formation and stability of lanthanum oxide thin films deposited from ?-diketonate precursor  

NASA Astrophysics Data System (ADS)

Lanthanum oxide thin film deposition by atomic layer epitaxy (ALE) was studied at 180-425°C on soda-lime glass and Si(1 0 0) substrates using a ?-diketonate type precursor La(thd) 3 and ozone. The chemical constituents of the films were analyzed by TOF-ERDA, RBS and FTIR while XRD and AFM were used to determine the crystallinity and surface morphology. Films grown below 275°C were amorphous La 2O 2CO 3, while at deposition temperatures above 300°C XRD patterns indicated that cubic La 2O 3 phase was formed. All the films were transparent and uniform with only small thickness variations. Carbonate type impurity was found in all films, but the carbon content of the films decreased with growth temperature being 3 at.% in films grown above 400°C. Hexagonal La 2O 3 was obtained when the films grown on silicon substrates were annealed at 800°C or above in a nitrogen flow. The as-deposited cubic and annealed hexagonal La 2O 3 films were found to be chemically unstable in ambient air since a transformation to monoclinic LaO(OH) and hexagonal La(OH) 3 was detected, respectively.

Nieminen, Minna; Putkonen, Matti; Niinistö, Lauri

2001-04-01

406

Clinical effects of long-term (36-month) lanthanum carbonate administration in hemodialysis patients in Japan.  

PubMed

In this study, we investigated the clinical effects of long-term administration of the phosphorus (P) binder lanthanum carbonate (LC), which was launched in Japan in 2009. The subjects were 58 dialysis patients who began receiving LC, and we evaluated the clinical effects for up to 36 months after treatment initiation. The average serum P concentration remained low during the 36-month study period, with a significant reduction from 6.25 mg/dL at the start of the study to 4.94 mg/dL after 36 months (P < 0.001). A significant reduction was also observed in the average serum calcium concentration after 36 months (P < 0.05), but not in the serum intact parathyroid hormone concentration. Significant reductions were also observed in the average serum total protein, albumin and potassium concentrations (P < 0.05). The dosages of LC increased by approximately 1.9-fold after 36 months, in contrast, the dosages of concomitantly used sevelamer hydrochloride and Ca carbonate preparations decreased. These results indicate that LC could be used to treat hyperphosphatemia without causing hypercalcemia, and would be useful for long-term treatment with hemodialysis patients. PMID:24953760

Kishi, Yuichiro; Obara, Yoshihiro; Hara, Keiko; Yamashiro, Hiromitsu; Kurosawa, Norio; Takada, Daisuke

2014-06-01

407

Lanthanum manganite-based air electrode for solid oxide fuel cells  

DOEpatents

An air electrode material for a solid oxide fuel cell is disclosed. The electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO[sub 3]. The A-site of the air electrode material preferably comprises La, Ca, Ce and at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd. The B-site of the electrode material comprises Mn with substantially no dopants. The ratio of A:B is preferably slightly above 1. A preferred air electrode composition is of the formula La[sub w]Ca[sub x]Ln[sub y]Ce[sub z]MnO[sub 3], wherein Ln comprises at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd, w is from about 0.55 to about 0.56, x is from about 0.255 to about 0.265, y is from about 0.175 to about 0.185, and z is from about 0.005 to about 0.02. The air electrode material possesses advantageous chemical and electrical properties as well as favorable thermal expansion and thermal cycle shrinkage characteristics. 10 figs.

Ruka, R.J.; Kuo, L.; Li, B.

1999-06-29

408

Lanthanum manganite-based air electrode for solid oxide fuel cells  

DOEpatents

An air electrode material for a solid oxide fuel cell is disclosed. The electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode material preferably comprises La, Ca, Ce and at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd. The B-site of the electrode material comprises Mn with substantially no dopants. The ratio of A:B is preferably slightly above 1. A preferred air electrode composition is of the formula La.sub.w Ca.sub.x Ln.sub.y Ce.sub.z MnO.sub.3, wherein Ln comprises at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd, w is from about 0.55 to about 0.56, x is from about 0.255 to about 0.265, y is from about 0.175 to about 0.185, and z is from about 0.005 to about 0.02. The air electrode material possesses advantageous chemical and electrical properties as well as favorable thermal expansion and thermal cycle shrinkage characteristics.

Ruka, Roswell J. (Pittsburgh, PA); Kuo, Lewis (Monroeville, PA); Li, Baozhen (Essex Junction, VT)

1999-01-01

409

Stability of manganese-oxide-modified lanthanum strontium cobaltite in the presence of chromia  

NASA Astrophysics Data System (ADS)

In order to restrain the decomposition and conductivity degradation of perovskite-type conductive material in the presence of chromia, manganese oxide modification of lanthanum strontium cobaltite has been studied. La0.7Sr0.3CoO3-? (LSC) and MnO2-modified LSC coatings are applied onto Ni-Cr alloy and exposed to long-term oxidation text to examine their chemical stability. In a LSC coating, chromium species migrating from the Ni-Cr alloy could induce the decomposition of LSC and produce SrCrO4 and Co-Cr spinel oxides. In contrast, in the MnO2-modified LSC, Sr is stable and the low-conductivity phase SrCrO4 phase is rarely seen even the coated alloy has gone through 1000 h of oxidation tests at 800 °C. It highlights that MnO2 modification could greatly improve the stability of LSC under Cr-rich conditions. The study of solid state reactions reveals that the influence of MnO2 is mainly due to the reaction between MnO2 and LSC, instead of the direct reaction between MnO2 and chromium oxides.

Ou, Ding Rong; Cheng, Mojie

2014-12-01

410

A Piezoelectric Plethysmograph Sensor Based on a Pt Wire Implanted Lead Lanthanum Zirconate Titanate Bulk Ceramic  

PubMed Central

This work reports on the development of a Lead Lanthanum Zirconate Titanate (PLZT) bulk ferroelectric poled ceramic structure as a Piezoelectric Plethysmograph (PZPG) sensor. The ceramic was implanted during its fabrication with a platinum (Pt) wire which works as an internal electrode. The ceramic was then submitted to an experimental setup in order to validate and determine the Pt-wire mechanical effects. This PZPG sensor was also mounted on a finger splint in order to measure the blood flow that results from the pulsations of blood occurring with each heartbeat. Fingertip pulses were recorded jointly with an ECG signal from a 25 year old male to compare the time shift; the PZPG sensor guarantees the electrical isolation of the patient. The proposed PZPG has several advantages: it can be adjusted for fingertip measurements, but it can easily be extended by means of spare bands, therefore making possible PZPG measurements from different body locations, e.g., forehead, forearm, knee, neck, etc. PMID:22163596

Gonzalez-Moran, Carlos O.; Flores-Cuautle, J.J. Agustin; Suaste-Gomez, Ernesto

2010-01-01

411

Photoluminescence and energy transfer properties of Sm 3+ doped CFB glasses  

NASA Astrophysics Data System (ADS)

The present paper describes the optical absorption, photoluminescence and lifetime measurements of trivalent samarium doped calcium fluoroborate (CFB) glasses. From the observed energy levels, the free-ion energy level parameters for the 4f 5 electronic configuration of Sm 3+ ion have been evaluated using H FI model. The experimental oscillator strengths of absorption bands have been analyzed to determine the Judd-Ofelt (J-O) parameters. From the evaluated J-O parameters and luminescence data, the radiative parameters such as AR, ?R and ?e values were obtained from the excited 4G 5/2 level to different lower energy levels. The decay curves of 4G 5/2 ? 6H 7/2 transition were analyzed by the Inokuti-Hirayama model assuming dipole-dipole interaction between the dopant ions. The decrease of fluorescence intensities as well as measured lifetimes at higher concentrations has been explained based on energy transfer process through cross-relaxation between Sm 3+ ions.

Suresh Kumar, J.; Pavani, K.; Sasikala, T.; Sreenivasa Rao, A.; Giri, Neeraj Kumar; Rai, S. B.; Rama Moorthy, L.

2011-08-01

412

Optical Investigation of Sm3+ Doped Zinc-Lead-Phosphate Glass  

NASA Astrophysics Data System (ADS)

Samarium doped lead-zinc-phosphate glasses having composition (60-x)P2O5-20PbO-20ZnO-xSm2O3 where x=0, 0.5, 1.0, 3.0mol% were prepared by using the melt quenching technique. The Archimedes method was used to measure their densities, which are used to calculate the molar volumes. The values of densities lie in the range 3.698-4.090 gm/cm3 whereas those of molar volume lie in the range of 37.24-40.00 cm-3. UV-vis-NIR absorption spectroscopy in the wavelength range 200-2000 nm was carried out. Absorption spectra consist of seven absorption peaks corresponding to the transitions from the 6H5/2 ground state to various excited energy levels. The energy band gap measured from the optical absorbance is found to be in the range of 3.88-4.43 eV and 3.68-4.33 eV for direct and indirect transitions, respectively. In addition, the photoluminescence spectrum shows four prominent emission bands centered at 560, 597, 642 and 700 nm corresponding to the 4G5/2-6HJ (J=5/2, 7/2, 9/2, 11/2) transitions respectively and the intensity of all the bands are enhanced as the concentration of Sm3+ ions increases.

Raja, J. Amjad; R. Sahar, M.; K. Ghoshal, S.; R. Dousti, M.; Riaz, S.; A. Tahir, B.

2012-08-01

413

Transport model for the adsorption of oxyanions of selenium (IV) and arsenic (V) from water onto lanthanum- and aluminum-based oxides  

SciTech Connect

A model for the adsorption of oxyanions of selenium (IV) and arsenic (V) as a function of time and pH was developed and tested on LA (10% lanthanum oxide/90% activated {gamma}-alumina mixed-oxide), lanthanum oxide, activated {gamma}-alumina, and activated {alpha}-alumina. A good correlation between the transport model and experimental results were observed. The model showed strong evidence that the adsorption of oxyanions of selenium and arsenic at the oxide-water interface is governed by three gradients: concentration, potential, and ionic size. Lanthanum oxide was observed to be a better absorbent for selenium than activated {gamma}-alumina and {alpha}-alumina. At the same initial selenium concentration, {gamma}-alumina was a better adsorbent for selenium as compared to {alpha}-alumina.

Davis, S.A.; Misra, M. [Univ. of Nevada, Reno, NV (United States). Dept. of Chemical and Metallurgical Engineering] [Univ. of Nevada, Reno, NV (United States). Dept. of Chemical and Metallurgical Engineering

1997-04-15

414

Ag-doped manganite nanoparticles: new materials for temperature-controlled medical hyperthermia.  

PubMed

The purpose of this study was to introduce newly synthesized nanomaterials as an alternative to superparamagnetic ironoxide based particles (SPIO) and thus to launch a new platform for highly controllable hyperthermia cancer therapy and imaging. The new material that forms the basis for this article is lanthanum manganite particles with silver ions inserted into the perovskite lattice: La(1-x)Ag(x)MnO(3+delta). Adjusting the silver doping level, it is possible to control the Curie temperature (T(c)) in the hyperthermia range of interest (41-44 degrees C). A new class of nanoparticles based on silver-doped manganites La(1-x)Ag(x)MnO(3+delta) is suggested. New nanoparticles are stable, and their properties were not affected by the typical ambient conditions in the living tissue. It is possible to monitor the particle uptake and retention by MRI. When these particles are placed into an alternating magnetic field, their temperature increases to the definite value near T(c) and then remains constant if the magnetic field is maintained. During the hyperthermia procedure, the temperature can be restricted, thereby preventing the necrosis of normal tissue. A new class of nanoparticles based on silver-doped manganites La(1-x)Ag(x)MnO(3+delta) was suggested. Ag-doped perovskite manganites particles clearly demonstrated the effect of adjustable Curie temperature necessary for highly controllable cellular hyperthermia. The magnetic relaxation properties of the particles are comparable with that of SPIO, and so we were able to monitor the particle movement and retention by MRI. Thus, the new material combines the MRI contrast enhancement capability with targeted hyperthermia treatment. PMID:19127514

Melnikov, O V; Gorbenko, O Yu; Markelova, M N; Kaul, A R; Atsarkin, V A; Demidov, V V; Soto, C; Roy, E J; Odintsov, B M

2009-12-15

415

Nutritional Supplements and Doping  

Microsoft Academic Search

Context: The problems of doping in sport and the increasing use of nutritional supplements by athletes are issues that inter- sect to the degree that a large number of supplements may contain substances that are banned in sport. Many supplements contain substances that are associated with significant health hazards. Athletes consuming such supplement products may jeopardize their sporting status, and

Andrew Pipe; Christiane Ayotte

416

Doped zinc oxide microspheres  

DOEpatents

A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

Arnold, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

1993-01-01

417

Doped zinc oxide microspheres  

DOEpatents

A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

1993-12-14

418

Samarium and yttrium codoped BaCeO? proton conductor with improved sinterability and higher electrical conductivity.  

PubMed

Acceptor-doped barium cerate is considered as one of the state-of-the-art high temperature proton conductors (HTPCs), and the proton conductivity of such HTPCs is heavily dependent on the dopant. In this work, a codoping strategy is employed to improve the electrical conductivity and sinterability of BaCeO3-based HTPC. BaCe0.8Sm(x)Y(0.2-x)O(3-?) (0 ? x ? 0.2) powders are synthesized by a typical citrate-nitrate combustion method. The XRD and Raman spectra reveal all the compounds have an orthorhombic perovskite structure. The effects of Sm and/or Y doping on the sinterability and electrical conductivity under different atmospheres are carefully investigated. The SEM results of the sintered BaCe0.8Sm(x)Y(0.2-x)O(3-?) pellets indicate a significant sintering enhancement with increasing Sm concentration. BaCe0.8Sm0.1Y0.1O(3-?) exhibits the highest electrical conductivity in hydrogen among the BaCe0.8Sm(x)Y(0.2-x)O(3-?) pellets. Anode-supported BaCe0.8Sm0.1Y0.1O(3-?) electrolyte membranes are also fabricated via a drop-coating process, and the corresponding single cell exhibits desirable power performance and durability at low temperatures. The results demonstrate that BaCe0.8Sm0.1Y0.1O(3-?) is a promising proton conductor with high conductivity and sufficient sinterability for proton-conducting solid oxide fuel cells operating at reduced temperatures. PMID:24646030

Shi, Zhen; Sun, Wenping; Wang, Zhongtao; Qian, Jing; Liu, Wei

2014-04-01

419

Theoretical determination of K X-ray transition energy and probability values for highly charged ions of lanthanum and cerium  

NASA Astrophysics Data System (ADS)

We provide, for the first time to our knowledge, accurate theoretical data for the the transition energy and probability values related to the decay of the most important excited states in He- through C-like lanthanum and cerium ions leading to the emission of K X-ray lines. We employed the multiconfiguration Dirac-Fock method, including QED corrections, to obtain the wave functions and energy values of each level involved in the X-ray analyzed transitions. The presented data may be used, among others, in the diagnostic of laboratory plasmas, such as the ones obtained in EBIT and ECRIS sources.

Santos, Jose Paulo; Conceição Martins, Maria; Costa, Ana Maria; Pires Marques, José; Indelicato, Paul; Parente, Fernando

2014-09-01

420

CRADA (AL-C-2009-02) Final Report: Phase I. Lanthanum-based Start Materials for Hydride Batteries  

SciTech Connect

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 (La{sub 1-x}R{sub x})(Ni{sub 1-y}M{sub y})(Si{sub z}), 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.

Gschneidner, Jr., Karl [Ames Laboratory; Schmidt, Frederick [Ames Laboratory] [Ames Laboratory; Frerichs, A.E. [Ames Laboratory] [Ames Laboratory; Ament, Katherine A. [Ames Laboratory] [Ames Laboratory

2013-05-01

421

Shear strain mediated magneto-electric effects in composites of piezoelectric lanthanum gallium silicate or tantalate and ferromagnetic alloys  

NASA Astrophysics Data System (ADS)

Shear strain mediated magneto-electric (ME) coupling is studied in composites of piezoelectric Y-cut lanthanum gallium silicate (LGS) or tantalate (LGT) and ferromagnetic Fe-Co-V alloys. It is shown that extensional strain does not result in ME effects in these layered composites. Under shear strain generated by an ac and dc bias magnetic fields along the length and width of the sample, respectively, strong ME coupling is measured at low-frequencies and at mechanical resonance. A model is discussed for the ME effects. These composites of Y-cut piezoelectrics and ferromagnetic alloys are of importance for shear strain based magnetic field sensors.

Sreenivasulu, G.; Qu, P.; Piskulich, E.; Petrov, V. M.; Fetisov, Y. K.; Nosov, A. P.; Qu, Hongwei; Srinivasan, G.

2014-07-01

422

Suppression of experimental atherosclerosis by the Ca++-antagonist lanthanum. Possible role of calcium in atherogenesis.  

PubMed Central

Agents inhibiting calcium deposition into arteries are known to suppress atherosclerosis in animals. However, the precise role of calcium in atherogenesis is unknown. In this study, the specific Ca2+-antagonist lanthanum was used to attempt suppression of experimental atherosclerosis and to gain more insight into the possible effects of calcium on atherogenesis. Rabbits were fed an atherogenic diet with and without increasing doses of LaCl3. All cholesterol-fed rabbits showed marked increases in serum cholesterol and ca2+. Untreated atherogenic animals revealed pronounced gross and microscopic atherosclerosis and striking increases in the aortic content of cholesterol, collagen, "elastin," and calcium as well as of elastin calcium, polar amino acids, and cholesterol. With increasing LaCl3 dosage these abnormalities progressively decreased and were completely abolished at the highest dose. The ingested La3+ was absorbed only in small quantities and had no discernible effect on the calcium and connective tissue content of bone, skin, lung, heart, and skeletal muscle nor on myocardial function (left ventricle pressure and left ventricle dp/dt) or myocardial and muscle content in ATP and creatine phosphate. The data suggest that shifts in arterial Ca2+-distribution may play a decisive part in atherogenesis, and provision of arterial calcium homeostasis by La3+ a pivotal role in its prevention, despite hypercholesteremia. Other inhibitors of calcium deposition into arteries may exert their protective effect by similar mechanisms. However, a direct inhibition of atherogenesis by La3+ cannot entirely be ruled out in this study, although no direct effects of La3+ on tissue metabolism have as yet been reported. Images PMID:7364947

Kramsch, D M; Aspen, A J; Apstein, C S

1980-01-01

423

A comparison of the use of sodium iodide and lanthanum bromide scintillation crystals for airborne surveys  

NASA Astrophysics Data System (ADS)

The Environmental Protection Agency (EPA) Aerial Spectral Environmental Collection Technology (ASPECT) program performs aerial radiological and chemical characterization of geographical regions of interest. Airborne surveys are performed to characterize environmental radionuclide content, for mineral exploration, as well as for emergency scenarios such as major releases or lost sources. Two radiological detection systems are used by the ASPECT team for gamma-ray detection and characterization: lanthanum bromide [LaBr 3(Ce)] and sodium iodide [NaI(Tl)] scintillation systems. An aerial survey of a uranium mine in the western United States was performed using both NaI(Tl) and LaBr3(Ce) detection systems. Analyses of the survey data were performed with RadAssist software and applying International Atomic Energy Agency (IAEA) airborne gamma ray mapping guidelines. The data for the survey were corrected for cross-over, which is spectral interference from higher energy photons as a result of Compton scattering, height attenuation, cosmic ray contribution to signal, and Radon contribution to signal. Two radiation survey contours were generated from each discrete data set. Based on analysis of the uranium mine survey results, LaBr3(Ce) produced a product comparable to that of NaI(Tl). The LaBr3(Ce) detection system contained 1/16th the scintillating volume and had a total system weight that was 1/4th that of the NaI(Tl) system. LaBr3(Ce) demonstrated a clear advantage over NaI(Tl) detectors in system mobility, and weight factors in airborne gamma ray spectroscopy.

Bailey, Derek M.

424

Effects of Lanthanum and Cerium on the Growth and Mineral Nutrition of Corn and Mungbean  

PubMed Central

Background and Aims Plant growth responses to the rare earth elements lanthanum (La) and cerium (Ce) have been reported, but little is known about the effects of these two elements on plant mineral nutrition. Methods Corn (Zea mays ‘Hycorn 82’) and mungbean (Vigna radiata ‘Berken’) were grown in continuous flowing nutrient solutions containing 0, 0·2, 1·0 and 5·0 µm La or Ce. At harvest plants were divided into roots and shoots, dried, weighed and analysed for macro- and micronutrients, as well as for La and Ce. Key Results La and Ce did not increase the growth of corn or mungbean. The dry weight of corn shoots was decreased by 32 % in the presence of 5·0 µm Ce; the other La and Ce concentrations had no effect. La and Ce concentrations of 0·9 and 5·0 µm decreased the shoot dry weight of mungbean by 75 or 95 %, the two elements having closely similar effects. Decreases in the uptake of Ca, Na, Zn and Mn by corn were observed with increases in solution La and Ce. For mungbean, the uptake rates of all measured elements decreased with increases in solution La and Ce. The concentrations of La and Ce in the roots of both species were higher than in the shoots and increased strongly with increasing concentrations of La or Ce in solution. The La and Ce concentrations in mungbean shoots were always higher than in corn shoots. Conclusions La and Ce did not enhance the growth of corn or mungbean, but decreased the growth, root function and consequently the nutritional status of mungbean at concentrations >0·2 µm in solution. It is concluded that if La or Ce have positive effects on corn and mungbean growth, they can only occur at solution concentrations below 0·2 µm. PMID:18292604

Diatloff, Eugene; Smith, Frank W.; Asher, Colin J.

2008-01-01

425

Growth of ferroelectric bismuth lanthanum nickel titanate thin films by rf magnetron sputtering  

SciTech Connect

The epitaxial growth, structural properties, and ferroelectric properties of bismuth lanthanum nickel titanate (Bi{sub 1-x}La{sub x}) (Ni{sub 0.5}Ti{sub 0.5})O{sub 3} (BLNT) thin films deposited on Pt(100)/MgO(100) substrates by rf magnetron sputtering have been investigated using x-ray diffraction, transmission electron microscope, and polarization-electric field hysteresis loop measurements. The ferroelectric BLNT(00l) phase with c-axis orientation and a single-phase tetragonal perovskite structure appeared at x{>=}0.3. The tetragonality (c/a) increased significantly from 1.004 to 1.028 with increasing La content. The fabricated BLNT films of x{>=}0.3 indicated the apparent fourfold rotational symmetry observed for a MgO(202) substrate, a bottom Pt(202) electrode, and a BLNT(101) ferroelectric film, based on {phi} scan measurements. These results imply that the present La-substituted BLNT films are grown heteroepitaxially at x{>=}0.3. It was confirmed that Bi in the BLNT films is in a trivalent state at A sites in the perovskite crystal, based on x-ray anomalous diffraction measurements and x-ray absorption near edge structure spectra. The sputtering technique using compacted powder targets designed by taking the bond dissociation energy of metal oxides into account provided epitaxial perovskite-structured BLNT thin films on Pt(100)/MgO(100) substrates. It is shown that the c-axis oriented epitaxial BLNT film exhibits a hysteresis loop shape with a P{sub r} value of 12 {mu}C/cm{sup 2} that is comparable to typical high-performance Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} (BLT) film.

Kobune, Masafumi; Fukushima, Koji; Yamaji, Toru; Tada, Hideto; Yazawa, Tetsuo; Fujisawa, Hironori; Shimizu, Masaru; Nishihata, Yasuo; Matsumura, Daiju; Mizuki, Jun'ichiro; Yamaguchi, Hideshi; Kotaka, Yasutoshi; Honda, Koichiro [Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2201 (Japan); Department of Electrical Engineering and Computer Sciences, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2201 (Japan); Synchrotron Radiation Research Center, Japan Atomic Energy Agency, Mikazuki, Sayo, Hyogo 679-5148 (Japan); Device and Materials Laboratories, Fujitsu Laboratories Ltd., 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0197 (Japan)

2007-04-01

426

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

PubMed

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 controlled laboratory experiments to measure the FRP removal by Phoslock(®) in the presence and absence of humic substances, as La complexation with humic substances might lower the effectiveness of La (Phoslock(®)) to bind FRP. The results of our study support the hypothesis that the presence of humic substances can interfere with the FRP removal by the La-modified bentonite. Both a short-term (1 d) and long-term (42 d) experiment were in agreement with predictions derived from chemical equilibrium modelling and showed lower FRP removal in presence of humic substances. This implies that in DOC-rich inland waters the applicability of exclusively Phoslock(®) as FRP binder should be met critically. In addition, we observed a strong increase of filterable La in presence of humic substances reaching in a week more than 270 ?g La l(-1) that would infer a violation of the Dutch La standard for surface water, which is 10.1 ?g La l(-1). Hence, humic substances are an important factor that should be given attention when considering chemical FRP inactivation as they might play a substantial role in lowering the efficacy of metal-based FRP-sorbents, which makes measurements of humic substances (DOC) as well as controlled experiments vital. PMID:24565799

Lürling, Miquel; Waajen, Guido; van Oosterhout, Frank

2014-05-01

427

Manganese Oxide Formation in Lanthanum Strontium Manganite-Yttria-Stabilized Zirconia SOFC Cathodes  

NASA Astrophysics Data System (ADS)

Microstructural changes in the cathode adjacent to the cathode-electrolyte interface were studied in SOFCs with lanthanum strontium manganite (LSM)/Y2O3-stabilized ZrO2 (YSZ) composite cathodes after long-term operation (1.3 to 2.0 kh) with steam (1 to 3 pct H2O) added to the cathode gas. We specifically sought to understand why the degradation rate (the increase of area specific resistance with time) was markedly higher at lower temperatures ( e.g., 1073 K (800 °C)) than at higher temperatures ( e.g., 1198 K (925 °C)). Transmission electron microscopy, combined with X-ray energy-dispersive spectroscopy and electron energy-loss spectroscopy, was used to detect and identify submicron MnxOy precipitates. The particles were shown to be Mn3O4 in cells operated at 1198 K (925 °C), and both Mn3O4 and Mn2O3 in cells operated at 1073 K (800 °C). In a cell exposed for 5 kh at 1198 K (925 °C) to a cathode atmosphere of 1.1 pct H2O at 4 bara, MnxOy precipitates were uniformly distributed across the cathode. On the other hand, in an identical cell exposed to the same conditions but operated continuously at 380 mA cm-2, MnxOy precipitates were observed almost exclusively within about 3 µm of the electrolyte/cathode interface. Whether MnxOy formation is causative or simply correlative with the steam effect remains an important question for future work.

Wang, Hsiang-Jen; De Guire, Mark R.; Xing, Zhengliang; Agnew, Gerry; Goettler, Richard; Liu, Zhien; Heuer, Arthur H.

2014-09-01

428

Efficacy of oral powder compared with chewable tablets for lanthanum carbonate administration in hemodialysis patients.  

PubMed

Lanthanum carbonate (LC) has been administered in a chewable tablet form for patients with hyperphosphatemia undergoing dialysis. However, some patients have difficulty chewing the tablets. LC oral powder has recently been released in Japan. The purpose of this study was to clarify the efficacy of LC oral powder form compared with that of chewable tablet form. The efficacy and safety of LC oral powder was retrospectively assessed in hemodialysis patients who switched from chewable tablet form to oral powder form without dose modification. Thirty-six patients (mean age, 66.8 ± 10.5 years; male, 64%; 39% with diabetes; mean duration of dialysis treatment, 99.2 ± 95.6 months) were enrolled in this study between June and July of 2012. Changes in clinical data and adverse events after the switch to oral powder form were investigated. The average dose of LC was 1180 ± 520 mg/day. Serum phosphorus levels were significantly decreased after the switch from chewable tablet form to oral powder form (5.3 ± 1.7 mg/dL at baseline vs. 4.9 ± 1.2 mg/dL at after 1 month after, P = 0.038). In contrast, no significant differences were observed in serum calcium and parathyroid hormone levels. Furthermore, no significant differences were evident in weight gain after the switch to oral powder form (2.5 ± 1.2 kg at baseline vs. 2.4 ± 1.1 kg at 1 month after the switch, P = 0.29). No serious adverse events were recorded. Our results suggest that LC is more effective in oral powder form than chewable tablet form for hemodialysis patients. PMID:24134326

Sakurada, Tsutomu; Oishi, Daisuke; Shibagaki, Yugo; Yasuda, Takashi; Kimura, Kenjiro

2013-10-01

429

Effects of switch from sevelamer hydrochloride to lanthanum carbonate on serum K and bone metabolic turnover.  

PubMed

Effects of switch from sevelamer hydrochloride (Sev) to lanthanum carbonate (La) on serum potassium (K) and bone metabolic markers in maintenance dialysis patients were examined. A switch from Sev to La was made for 14 dialysis patients (mean dialysis period and age: 65.3 months and 58.5 years old) to examine changes of biochemical and bone metabolic markers after 8 weeks. The Sev dosage immediately before the switch was 1857?±?1325?mg/day, and the La dosage 8 weeks after the switch was 821?±?301?mg/day. The serum calcium (Ca) level, which was 8.9?mg/dL before the switch, increased to 9.5?mg/dL after the switch (P?

Ota, Satoshi; Hirose, Masayo; Izumiya, Yoshiaki; Ishida, Yoichi

2013-04-01

430

Dielectric, piezoelectric, and ferroelectric properties of lanthanum-modified PZTFN ceramics  

NASA Astrophysics Data System (ADS)

Specimens of Pb1-1.5 x La x (Zr0.53Ti0.47)1- y- z Fe y Nb z O3 ( x = 0, 0.004, 0.008, 0.012, and 0.016, y = z = 0.01) (PZTFN) ceramics were synthesized by a semi-wet route. In the present study, the effect of La doping was investigated on the structural, microstructural, dielectric, piezoelectric, and ferroelectric properties of the ceramics. The results show that, the tetragonal (space group P4 mm) and rhombohedral (space group R3 c) phases are observed to coexist in the sample at x = 0.012. Microstructural investigations of all the samples reveal that La doping inhibits grain growth. Doping of La into PZTFN improves the dielectric, ferroelectric, and piezoelectric properties of the ceramics. The hysteresis loops of all specimens exhibit nonlinear behavior. The dielectric, piezoelectric and ferroelectric properties show a maximum response at x ? 0.012, which corresponds to the morphotropic phase boundary (MPB).

Kumar, Arvind; Mishra, S. K.

2014-10-01

431

High Performance Ceramic Interconnect Material for Solid Oxide Fuel Cells (SOFCs): Ca- and Transition Metal-doped Yttrium Chromite  

SciTech Connect

The effect of transition metal substitution on thermal and electrical properties of Ca-doped yttrium chromite was investigated in relation to use as a ceramic interconnect in high temperature solid oxide fuel cells (SOFCs). 10 at% Co, 4 at% Ni, and 1 at% Cu substitution on B-site of 20 at% Ca-doped yttrium chromite led to a close match of thermal expansion coefficient (TEC) with that of 8 mol% yttria-stabilized zirconia (YSZ), and a single phase Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 remained stable between 25 and 1100 degree C over a wide oxygen partial pressure range. Doping with Cu significantly facilitated densification of yttrium chromite. Ni dopant improved both electrical conductivity and dimensional s