Study on mechanisms of different sulfuric acid leaching technologies of chromite

NASA Astrophysics Data System (ADS)

Shi, Pei-yang; Liu, Cheng-jun; Zhao, Qing; Shi, Hao-nan

2017-09-01

The extraction of chromate from chromite via the sulfuric acid leaching process has strong potential for practical use because it is a simple and environmentally friendly process. This paper aims to study the sulfuric acid leaching process using chromite as a raw material via either microwave irradiation or in the presence of an oxidizing agent. The results show that the main phases in Pakistan chromite are ferrichromspinel, chrompicotite, hortonolite, and silicate embedded around the spinel phases. Compared with the process with an oxidizing agent, the process involving microwaves has a higher leaching efficiency. When the mass fraction of sulfuric acid was 80% and the leaching time was 20 min, the efficiency could exceed 85%. In addition, the mechanisms of these two technologies fundamentally differ. When the leaching was processed in the presence of an oxidizing agent, the silicate was leached first and then expanded. By contrast, in the case of leaching under microwave irradiation, the chromite was dissolved layer by layer and numerous cracks appeared at the particle surface because of thermal shock. In addition, the silicate phase shrunk instead of expanding.

Complete zircon and chromite digestion by sintering of granite, rhyolite, andesite and harzburgite rock reference materials for geochronological purposes

NASA Astrophysics Data System (ADS)

Bokhari, Syed Nadeem H.; Meisel, Thomas

2014-05-01

Zircon (ZrSiO4) is a common accessory mineral in nature that occurs in a wide variety of sedimentary, igneous, and metamorphic rocks. Zircon has the ability to retain substantial chemical and isotopic information that are used in range of geochemical and geo- chronological investigations. Sample digestion of such rock types is a limiting factor due to the chemical inertness of zircon (ZrSiO4) tourmaline, chromite, barite, monazite, sphene, xenotime etc. as the accuracy of results relies mainly on recovery of analytes from these minerals. Dissolution by wet acid digestions are often incomplete and high blank and total dissolved solids (TDS) contents with alkali fusions lead to an underestimation of analyte concentrations. Hence an effective analytical procedure, that successfully dissolves refractory minerals such as zircon is needed to be employed for reliable analytical results. Na2O2 digestion [1] was applied in characterisation of granite (G-3), rhyolite (MRH), andesite (MGL-AND) and harzburgite (MUH-1) powdered reference material with solution based ICP-MS analysis. In this study we undertake a systematic evaluation of decomposition time and sample:Na2O2 ratio and test portion size after minimising effect of all other constraints that makes homogeneity ambiguous. In recovering zircon and chromite 100 mg test portion was mixed with different amounts of Na2O2 i.e. 100-600 mg. Impact of decomposition time was observed by systematically increasing heating time from 30-45 minutes to 90-120 minutes at 480°C. Different test portion sizes 100-500 mg of samples were digested to control variance of inhomogeneity. An improved recovery of zirconium in zircon in granite (G-3), rhyolite MRH), andesite (MGL-AND) and chromite in harzburgite (MUH-1) was obtained by increasing heating time (2h) at 480°C and by keeping (1:6) ratio of sample:Na2O2. Through this work it has been established that due to presence of zircon and chromite, decomposition time and sample:Na2O2 ratio has

Calcium and lanthanum solid base catalysts for transesterification

DOEpatents

Ng, K. Y. Simon; Yan, Shuli; Salley, Steven O.

2015-07-28

In one aspect, a heterogeneous catalyst comprises calcium hydroxide and lanthanum hydroxide, wherein the catalyst has a specific surface area of more than about 10 m.sup.2/g. In another aspect, a heterogeneous catalyst comprises a calcium compound and a lanthanum compound, wherein the catalyst has a specific surface area of more than about 10 m.sup.2/g, and a total basicity of about 13.6 mmol/g. In further another aspect, a heterogeneous catalyst comprises calcium oxide and lanthanum oxide, wherein the catalyst has a specific surface area of more than about 10 m.sup.2/g. In still another aspect, a process for preparing a catalyst comprises introducing a base precipitant, a neutral precipitant, and an acid precipitant to a solution comprising a first metal ion and a second metal ion to form a precipitate. The process further comprises calcining the precipitate to provide the catalyst.

Fuel cells with doped lanthanum gallate electrolyte

NASA Astrophysics Data System (ADS)

Feng, Man; Goodenough, John B.; Huang, Keqin; Milliken, Christopher

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

Chromite deposits of the north-central Zambales Range, Luzon, Philippines

USGS Publications Warehouse

Rossman, D.L.

1970-01-01

Peridotite and gabbro form an intrusive complex which is exposed over an area about 35 km wide and 150 km long in the center of the Zambales Range of western Luzon. The Zambales Complex is remarkable for its total known resources, mined and still remaining, of about 15 million metric tons of chromite ore. Twenty percent of Free World production was obtained from this area between 1950 and the end of 1964; in 1960 production reached a high of 606,103 metric tons of refractory-grade ore, mostly from the Coto mine near Masinloc, and 128,426 metric tons of metallurgical ore from the Acoje mine. The United States imports 80 to 90 percent of its refractory-grade chromite from the Philippines, and its basic refractory technology has been designed upon the chemical and physical characteristics of Coto high-alumina chromite ore. Continuation of this pattern will depend upon discovery of additional ore reserves to replace those depleted by mining. The Zambales Ultramafic Complex is of the alpine type in which lenticular or podiform deposits of chromite lie in peridotite or dunite, mostly near Contacts with gabbroic rocks. Layered structures, foliation, and lineation commonly are well developed and transect boundaries between major rock units, including chromite deposits, at any angle. Accordingly, these structures cannot be used as guides in exploration and mining as they are used in stratiform complexes such as the Bushveld, where chromite layers extend for many miles. Probably 90 percent of the known deposits in the Zambales Complex are located in two belts in its northern part. One zone containing high-aluminua refractory-grade deposits extends northeast from the Coto mine and Chromite Reservation No. I along a peridotite contact with olivine gabbro, and another of high-chromium metallurgical grade chromite extends south through the Zambales and Acoje properties, and swings westward around the south side of Mount Lanai along a peridotite contact with norite. The textures

Chromite from the Blue Ridge province of North Carolina.

USGS Publications Warehouse

Lipin, B.R.

1984-01-01

Chromite is found as ubiquitous accessory grains and occasional segregations within dunite bodies. Results of analysis of chromite textures and chemistry and estimation of equilibration T of olivine-chromite pairs are cited as evidence that the dunites are metamorphic rocks rather than primary mantle peridotites. They are considered to be disrupted fragments of ophiolites that were emplaced before or during the peak of Ordovician metamorphism which was responsible for dehydration of serpentine-bearing rocks and alteration of chromite compositions and textures.-M.S.

Decomposition mechanism of chromite in sulfuric acid-dichromic acid solution

NASA Astrophysics Data System (ADS)

Zhao, Qing; Liu, Cheng-jun; Li, Bao-kuan; Jiang, Mao-fa

2017-12-01

The sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly understood. In this work, binary spinels of Mg-Al, Mg-Fe, and Mg-Cr in the powdered and lump states were synthesized and used as raw materials to investigate the decomposition mechanism of chromite in sulfuric acid-dichromic acid solution. The leaching yields of metallic elements and the changes in morphology of the spinel were studied. The experimental results showed that the three spinels were stable in sulfuric acid solution and that dichromic acid had little influence on the decomposition behavior of the Mg-Al spinel and Mg-Fe spinel because Mg2+, Al3+, and Fe3+ in spinels cannot be oxidized by Cr6+. However, in the case of the Mg-Cr spinel, dichromic acid substantially promoted the decomposition efficiency and functioned as a catalyst. The decomposition mechanism of chromite in sulfuric acid-dichromic acid solution was illustrated on the basis of the findings of this study.

Thermoelectric properties of non-stoichiometric lanthanum sulfides

NASA Technical Reports Server (NTRS)

Shapiro, E.; Danielson, L. R.

1983-01-01

The lanthanum sulfides are promising candidate materials for high-efficiency thermoelectric applications at temperatures up to 1300 C. The non-stoichiometric lanthanum sulfides (LaS(x), where x is in the range 1.33-1.50) appear to possess the most favorable thermoelectric properties. The Seebeck coefficient and resistivity vary significantly with composition, so that an optimum value of alpha sq/rho (where alpha is the Seebeck coefficient and rho is the resistivity) can be chosen. The thermal conductivity remains approximately constant with stoichiometry, so a material with an optimum value of alpha sq/rho should possess the optimum figure-of-merit. Data for the Seebeck coefficient and electrical resistivity of non-stoichiometric lanthanum sulfides will be pressed, together with structural properties of these materials.

Chromite in komatiites: 3D morphologies with implications for crystallization mechanisms

NASA Astrophysics Data System (ADS)

Godel, Bélinda; Barnes, Stephen J.; Gürer, Derya; Austin, Peter; Fiorentini, Marco L.

2013-01-01

High-resolution X-ray computed tomography has been carried out on a suite of komatiite samples representing a range of volcanic facies, chromite contents and degrees of alteration and metamorphism, to reveal the wide range of sizes, shapes and degrees of clustering that chromite grains display as a function of cooling history. Dendrites are spectacularly skeletal chromite grains formed during very rapid crystallization of supercooled melt in spinifex zones close to flow tops. At slower cooling rates in the interiors of thick flows, chromite forms predominantly euhedral grains. Large clusters (up to a dozen of grains) are characteristic of liquidus chromite, whereas fine dustings of mostly individual ~20-μm grains form by in situ crystallization from trapped intercumulus liquid. Chromite in coarse-grained olivine cumulates from komatiitic dunite bodies occurs in two forms: as clusters or chains of euhedral crystals, developing into "chicken-wire" texture where chromite is present in supra-cotectic proportions; and as strongly dendritic, semi-poikilitic grains. These dendritic grains are likely to have formed by rapid crescumulate growth from magma that was close to its liquidus temperature but supersaturated with chromite. In some cases, this process seems to have been favoured by nucleation of chromite on the margins of sulphide liquid blebs. This texture is a good evidence for the predominantly cumulus origin of oikocrysts and in situ origin of heteradcumulate textures. Our 3D textural analysis confirms that the morphology of chromite crystals is a distinctive indicator of crystallization environment even in highly altered rocks.

Study of lanthanum aluminate for cost effective electrolyte material for SOFC

NASA Astrophysics Data System (ADS)

Verma, O. N.; Shahi, A. K.; Singh, P.

2018-05-01

The perovskite type electrolyte material LaAlO3 (abbreviated LAO) has been prepared by easy processing of auto-combustion synthesis using lanthanum nitrate and aluminium nitrate salts as precursors and citric acid as the fuel. The XRD analysis reveals that as synthesized material exhibits only single phase having rhombohedral structure. The measured density and theoretical density have been deliberated. The temperature dependent electrical conductivity of LAO increases with increasing the temperature which leads to increased mobility of oxide ion. The major contribution of such a significant value of ionic conductivity of LAO can be inferred to grain boundary resistance.

Compaction of Chromite Cumulates applying a Centrifuging Piston-Cylinder

NASA Astrophysics Data System (ADS)

Manoochehri, S.; Schmidt, M. W.

2012-12-01

Stratiform accumulations of chromite cumulates, such as the UG2 chromitite layer in the Bushveld Complex, is a common feature in most of the large layered mafic intrusions. The time scales and mechanics of gravitationally driven crystal settling and compaction and the feasibility of these processes for the formation of such cumulate layers is investigated through a series of high temperature (1280-1300 °C) centrifuge-assisted experiments at 100-2000 g, 0.4-0.6 GPa. A mixture of natural chromite, with defined grain sizes (means of 5 μm, 13 μm, and 52 μm), and a melt with a composition thought to represent the parental magma of the Bushveld Complex, was first chemically and texturally equilibrated at static conditions and then centrifuged. Centrifugation leads to a single cumulate layer formed at the gravitational bottom of the capsule. This layer was analysed for porosity, mean grain size, size distribution and also travelling distance of chromite crystals. The experimentally observed mechanical settling velocity of chromite grains in a suspension with ~ 24 vol% crystals is calculated to be about half (~ 0.53) of the Stokes settling velocity, consistent with a sedimentation exponent n of 2.35±0.3. The settling leads to a porosity of about 52 % in the chromite layer. Formation times of chromite orthocumulates with initial crystal content in the melt of 1 % and grain sizes of 2 mm are thus around 0.6 m/day. To achieve more compacted chromite piles, centrifugation times and acceleration were increased. Within each experiment the crystal content of the cumulate layer increases downward almost linearly at least in the lower 2/3 of the cumulate pile. Although porosity in the lowermost segment of the chromite layer decreases with increasing effective stress integrated over time, the absolute decrease is smaller than for experiments with olivine (from a previous study). Formation times of a ½ meter single chromite layer with 70 vol% chromite, is calculated to be

Crystal-Chemical Correlations in Chromites from Kimberlitic and Non-Kimberlitic Sources.

NASA Astrophysics Data System (ADS)

Freckelton, C. N.; Flemming, R. L.

2009-05-01

This study explores the utility of micro X-ray diffraction (μXRD) as a tool for diamond exploration, as a compliment to current industry-standard techniques such as electron probe microanalysis (EPMA). Here we examine chromite. As one of the first phases to crystallize in mantle rocks, it is a useful indicator of upper mantle magmatic conditions in rocks that have been sampled by kimberlites. In addition, chromite does not alter easily from chemical and physical weathering processes. As such, chromite is a useful kimberlite indicator mineral in diamond exploration. We present correlations between crystal structure (unit cell) and chemical composition of chromite, (Fe,Mg)[Cr, Al]2O4, using correlated μXRD and EPMA data for 133 chromites from a three source locations: Two kimberlite sources and one non-kimberlitic source from an Archean granite/greenstone terrain. Quantitative analysis was performed using Electron Probe Microanalysis (EPMA) at Mineral Services, South Africa, prior to the loan of the samples. Randomly-oriented chromite grains, approximately 500 μm in diameter, were analyzed as previously mounted for EPMA. Micro X-ray-diffraction was performed using a Bruker D8-Discover Diffractometer, with θ-θ geometry, with CuKα radiation, operating at 40 kV and 40 mA, with nominal beam diameter of 500 μm. The data were collected in omega scan mode. Two dimensional General Area Detector Diffraction System (GADDS) images were collected for 20 minutes per image, and integrated to produce one-dimensional plots of intensity versus 2θ, for subsequent unit cell refinement using CELREF. Although all samples in this study were considered to be 'chromite', a plot of Cr/(Cr+Al) versus Fe2+/(Fe2++Mg) shows extensive substitution among four dominant members: chromite (FeCr2O4), magnesio-chromite (MgCr2O4), spinel (MgAl2O4), and hercynite (FeAl2O4), where Mg and Fe2+ substitute for one another on the tetrahedral site, and Cr and Al substitute for one another on the

Occurrence and mineral chemistry of chromite and related silicates from the Hongshishan mafic-ultramafic complex, NW China with petrogenetic implications

NASA Astrophysics Data System (ADS)

Ruan, Banxiao; Yu, Yingmin; Lv, Xinbiao; Feng, Jing; Wei, Wei; Wu, Chunming; Wang, Heng

2017-10-01

The Hongshishan mafic-ultramafic complex is located in the western Beishan Terrane, NW China, and hosts an economic Ni-Cu deposit. Chromite as accessory mineral from the complex is divided into three types based on its occurrence and morphology. Quantitative electron probe microanalysis (EPMA) have been conducted on the different types of chromites. Type 1 chromite occurs as inclusions within silicate minerals and has relatively homogeneous composition. Type 2 chromite occurs among serpentine, as interstitial phase. Type 3 chromite is zoned and exhibits a sudden change in compositions from core to rim. Type 1 chromite occurs in olivine gabbro and troctolite showing homogeneous composition. This chromite is more likely primary. Interstitial type 2 and zoned type 3 chromite has compositional variation from core to rim and is more likely modified. Abundant inclusions of orthopyroxene, phlogopite and hornblende occur within type 2 and type 3 chromites. The parental melt of type 1 chromite has an estimated composition of 14.5 wt% MgO, 12.3 wt% Al2O3 and 1.9 wt% TiO2 and is characterized by high temperature, picritic affinity, hydrous nature and high Mg and Ti contents. Compositions of chromite and clinopyroxene are distinct from those of Alaskan-type complexes and imply that the subduction-related environment is not reasonable. Post orogenic extension and the early Permian mantle plume are responsible for the emplacement of mafic-ultramafic complexes in the Beishan Terrane. The cores of zoned chromites are classified as ferrous chromite and the rims as ferrian chromite. The formation of ferrian rim involves reaction of ferrous chromite, forsterite and magnetite to produce ferrian chromite and chlorite, or alternaively, the rim can be simply envisioned as the result of external addition of magnetite in solution to the already formed ferrous chromite.

Chromite Ore from the Transvaal Region of South Africa

EPA Pesticide Factsheets

In 2001, EPA finalized a rule to to delete both chromite ore mined in the Transvaal Region of South Africa and the unreacted ore component of the chromite ore processing residue (COPR) from TRI reporting requirements.

Lanthanum manganite-based air electrode for solid oxide fuel cells

DOEpatents

Ruka, Roswell J.; Kuo, Lewis; Li, Baozhen

1999-01-01

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.

Typology of mafic-ultramafic complexes in Hoggar, Algeria: Implications for PGE, chromite and base-metal sulphide mineralisation

NASA Astrophysics Data System (ADS)

Augé, Thierry; Joubert, Marc; Bailly, Laurent

2012-02-01

With the aims to bring new information about the typology and mineral potential of mafic-ultramafic complexes of the Hoggar, detailed petrological and chemical characterisation were performed on serpentinite bands and layered intrusions. The serpentinite bands locally contain pods, layers and disseminations of chromite showing all the characteristics (mode of occurrence, composition, nature and composition of silicate inclusions, etc.) of an "ophiolite" chromite. Some chromite concentrations in the serpentinite bands also contain inclusions of platinum-group minerals (described for the first time in the Hoggar) such as ruarsite (RuAsS), an Os, Ru, Ir alloy, and complex Os, Ir, Ru sulfarsenides and arsenides. The serpentinite probably corresponds to remnants of oceanic lithosphere—more specifically from the upper part of the mantle sequence, generally where chromitite pods are most abundant, and the basal part of the cumulate series with stratiform chromite concentrations—and marks suture zones; the rest of the oceanic crust has not been preserved. Considering the typology of the serpentinites bands, their potential for precious- and base-metals is suspected to be low. Of the two layered mafic-ultramafic intrusions that were studied, the In Tedeini intrusion has a wehrlite core intruded by olivine gabbronorite and surrounded by an olivine gabbro aureole; three orthocumulate units, containing disseminated magmatic base-metal sulphides and with a plagioclase composition varying around An 58.1 and An 63.3, that could have been derived from a single magma. The East Laouni intrusion has a basal unit of olivine gabbronorite with specific silicate oxide intergrowths, and an upper unit of more differentiated gabbro, both units containing disseminated magmatic Ni-Cu sulphides indicative of early sulphide immiscibility; the mineral composition of these two cumulate units indicates that they also could have been derived from a single magmatic episode. The characteristic of

Stabilized Lanthanum Sulphur Compounds

NASA Technical Reports Server (NTRS)

Reynolds, George H. (Inventor); Elsner, Norbert B. (Inventor); Shearer, Clyde H. (Inventor)

1985-01-01

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 novel compound is an excellent thermoelectric material.

Materiais a base de oxidos com estrutura do tipo perovskite e compositos como anodos de PCES: Propriedades Funcionais e Comportamento Eletroquimico em Celulas com Eletrolitos Solidos a Base de Galatos e Silicatos

NASA Astrophysics Data System (ADS)

Kolotygin, Vladislav

This work was focused on the analysis of transport, thermomechanical and electrochemical properties of a series of perovskite-like oxide materials and composites for potential applications as anodes of intermediate-temperature solid oxide fuel cells (SOFCs) with lanthanum gallate and silicate solid electrolytes. The primary attention was centered on A(Mn,Nb)O3-delta (A = Sr, Ca) and (La,Sr)(Mn,Ti)O3-based systems, lanthanum chromite substituted with acceptor-type and variable-valence cations, and various Ni-containing cermets. Emphasis was given to phase stability of the materials, their crystal structure, microstructure of porous electrode layers and dense ceramics, electronic conductivity, Seebeck coefficient, oxygen permeability, thermal and chemical induced expansion, and anodic overpotentials of the electrodes deposited onto (La,Sr)(Ga,Mg)O3- and La10(Si,Al)6O27-based electrolyte membranes. In selected cases, roles of oxygen diffusivity, states of the transition metal cations relevant for the electronic transport, catalytically active additives and doped ceria protective interlayers introduced in the model electrochemical cells were assessed. The correlations between transport properties of the electrode materials and electrochemical behavior of porous electrodes showed that the principal factors governing anode performance include, in particular, electronic conduction of the anode compositions and cation interdiffusion between the electrodes and solid electrolytes. The latter is critically important for the silicatebased electrolyte membranes, leading to substantially worse anode properties compared to the electrochemical cells with lanthanum gallate solid electrolyte. The results made it possible to select several anode compositions exhibiting lower area-specific electrode resistivity compared to known analogues, such as (La,Sr)(Cr,Mn)O3-delta.

Dissolution Behavior of Mg from Magnesia-Chromite Refractory into Al-killed Molten Steel

NASA Astrophysics Data System (ADS)

Liu, Chunyang; Yagi, Motoki; Gao, Xu; Kim, Sun-Joong; Huang, Fuxiang; Ueda, Shigeru; Kitamura, Shin-ya

2018-06-01

Magnesia-chromite refractory materials are widely employed in steel production, and are considered a potential MgO source for the generation of MgO·Al2O3 spinel inclusions in steel melts. In this study, a square magnesia-chromite refractory rod was immersed into molten steel of various compositions held in an Al2O3 crucibles. As the immersion time was extended, Mg and Cr gradually dissolved from the magnesia-chromite refractory, and the Mg and Cr contents of the steel melts increased. However, it was found that the inclusions in the steel melts remained as almost pure Al2O3 because the Mg content of the steel melts was low, approximately 1 ppm. On the surface of the magnesia-chromite refractory, an MgO·Al2O3 spinel layer with a variable composition was formed, and the thickness of the MgO·Al2O3 spinel layer increased with the immersion time and the Al content of the steel melts. At the rod interface, the formed layer consisted of MgO-saturated MgO·Al2O3 spinel. The MgO content decreased along the thickness direction of the layer, and at the steel melts interface, the formed layer consisted of Al2O3-saturated MgO·Al2O3 spinel. Therefore, the low content of Mg in steel melts and the unchanged inclusions were because of the equilibrium between Al2O3-saturated MgO·Al2O3 layer and Al2O3. In addition, the effects of the Al and Cr contents of the steel melts on the dissolution of Mg from the magnesia-chromite refractory are insignificant.

Lanthanum manganite-based air electrode for solid oxide fuel cells

DOEpatents

Ruka, R.J.; Kuo, L.; Li, B.

1999-06-29

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.

Comparative Planetary Mineralogy: V/(Cr+Al) Systematics in Chromites as an Indicator of Relative Oxygen Fugacity

NASA Technical Reports Server (NTRS)

Papike, J. J.; Kamer, J. M.; Shearer, C. K.

2004-01-01

As our contribution to the new "Oxygen in the Solar System" initiative of the Lunar and Planetary Institute and the NASA Cosmochemistry Program, we have been developing oxygen barometers based largely on behavior of V which can occur in four valence states V2+, V3+, V4+, and V5+, and record at least 8 orders of magnitude of fO2. Our first efforts in measuring these valence proportions were by XANES techniques in basaltic glasses from Earth, Moon, and Mars. We now address the behavior of V valence states in chromite in basalts from Earth, Moon, and Mars. We have been looking for a "V in chromite oxybarometer" that works with data collected by the electron microprobe and thus is readily accessible to a large segment of the planetary materials community. This paper describes very early results that will be refined over the next two years.

Palladium, platinum, rhodium, iridium and ruthenium in chromite- rich rocks from the Samail ophiolite, Oman.

USGS Publications Warehouse

Page, N.J.; Pallister, J.S.; Brown, M.A.; Smewing, J.D.; Haffty, J.

1982-01-01

30 samples of chromitite and chromite-rich rocks from two stratigraphic sections, 250 km apart, through the basal ultramafic member of the Samail ophiolite were spectrographically analysed for platinum-group elements (PGE) and for Co, Cu, Ni and V. These data are reported as are Cr/(Cr + Al), Mg/(Mg + Fe) and wt.% TiO2 for most samples. The chromitite occurs as pods or lenses in rocks of mantle origin or as discontinuous layers at the base of the overlying cumulus sequence. PGE abundances in both sections are similar, with average contents in chromite-rich rocks: Pd 8 ppb, Pt 14 ppb, Rh 6 ppb, Ir 48 ppb and Ru 135 ppb. The PGE data, combined with major-element and petrographic data on the chromitite, suggest: 1) relatively larger Ir and Ru contents and highest total PGE in the middle part of each section; 2) PGE concentrations and ratios do not correlate with coexisting silicate and chromite abundances or chromite compositions; 3) Pd/PGE, on average, increases upward in each section; 4) Samail PGE concentrations, particularly Rh, Pt and Pd, are lower than the average values for chromite-rich rocks in stratiform intrusions. 2) suggests that PGEs occur in discrete alloy or sulphide phases rather than in the major oxides or silicates, and 4) suggests that chromite-rich rocks from the oceanic upper mantle are depleted in PGE with respect to chondrites. L.C.C.

Sediment-dispersed extraterrestrial chromite traces a major asteroid disruption event.

PubMed

Schmitz, Birger; Häggström, Therese; Tassinari, Mario

2003-05-09

Abundant extraterrestrial chromite grains from decomposed meteorites occur in middle Ordovician (480 million years ago) marine limestone over an area of approximately 250,000 square kilometers in southern Sweden. The chromite anomaly gives support for an increase of two orders of magnitude in the influx of meteorites to Earth during the mid-Ordovician, as previously indicated by fossil meteorites. Extraterrestrial chromite grains in mid-Ordovician limestone can be used to constrain in detail the temporal variations in flux of extraterrestrial matter after one of the largest asteroid disruption events in the asteroid belt in late solar-system history.

Occupational health assessment of chromite toxicity among Indian miners

PubMed Central

Das, Alok Prasad; Singh, Shikha

2011-01-01

Elevated concentration of hexavalent chromium pollution and contamination has contributed a major health hazard affecting more than 2 lakh mine workers and inhabitants residing in the Sukinda chromite mine of Odisha, India. Despite people suffering from several forms of ill health, physical and mental deformities, constant exposure to toxic wastes and chronic diseases as a result of chromite mining, there is a tragic gap in the availability of 'scientific’ studies and data on the health hazards of mining in India. Occupational Safety and Health Administration, Odisha State Pollution Control Board and the Odisha Voluntary Health Association data were used to compile the possible occupational health hazards, hexavalent chromium exposure and diseases among Sukinda chromite mines workers. Studies were reviewed to determine the routes of exposure and possible mechanism of chromium induced carcinogenicity among the workers. Our studies suggest all forms of hexavalent chromium are regarded as carcinogenic to workers however the most important routes of occupational exposure to Cr (VI) are inhalation and dermal contact. This review article outlines the physical, chemical, biological and psychosocial occupational health hazards of chromite mining and associated metallurgical processes to monitor the mining environment as well as the miners exposed to these toxicants to foster a safe work environment. The authors anticipate that the outcome of this manuscript will have an impact on Indian chromite mining industry that will subsequently bring about improvements in work conditions, develop intervention experiments in occupational health and safety programs. PMID:21808494

Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires

NASA Astrophysics Data System (ADS)

Chi, Su (Ike); Farias, Stephen; Cammarata, Robert

2013-03-01

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. 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.

Platinum-bearing chromite layers are caused by pressure reduction during magma ascent.

PubMed

Latypov, Rais; Costin, Gelu; Chistyakova, Sofya; Hunt, Emma J; Mukherjee, Ria; Naldrett, Tony

2018-01-31

Platinum-bearing chromitites in mafic-ultramafic intrusions such as the Bushveld Complex are key repositories of strategically important metals for human society. Basaltic melts saturated in chromite alone are crucial to their generation, but the origin of such melts is controversial. One concept holds that they are produced by processes operating within the magma chamber, whereas another argues that melts entering the chamber were already saturated in chromite. Here we address the problem by examining the pressure-related changes in the topology of a Mg 2 SiO 4 -CaAl 2 Si 2 O 8 -SiO 2 -MgCr 2 O 4 quaternary system and by thermodynamic modelling of crystallisation sequences of basaltic melts at 1-10 kbar pressures. We show that basaltic melts located adjacent to a so-called chromite topological trough in deep-seated reservoirs become saturated in chromite alone upon their ascent towards the Earth's surface and subsequent cooling in shallow-level chambers. Large volumes of these chromite-only-saturated melts replenishing these chambers are responsible for monomineralic layers of massive chromitites with associated platinum-group elements.

Natural occurrence and synthesis of two new postspinel polymorphs of chromite.

PubMed

Chen, Ming; Shu, Jinfu; Mao, Ho-kwang; Xie, Xiande; Hemley, Russell J

2003-12-09

A high-pressure polymorph of chromite, the first natural sample with the calcium ferrite structure, has been discovered in the shock veins of the Suizhou meteorite. Synchrotron x-ray diffraction analyses reveal an orthorhombic CaFe2O4-type (CF) structure. The unit-cell parameters are a = 8.954(7) A, b = 2.986(2) A, c = 9.891(7) A, V = 264.5(4) A3 (Z = 4) with space group Pnma. The new phase has a density of 5.62 g/cm3, which is 9.4% denser than chromite-spinel. We performed laser-heated diamond anvil cell experiments to establish that chromite-spinel transforms to CF at 12.5 GPa and then to the recently discovered CaTi2O4-type (CT) structure above 20 GPa. With the ubiquitous presence of chromite, the CF and CT phases may be among the important index minerals for natural transition sequence and pressure and temperature conditions in mantle rocks, shock-metamorphosed terrestrial rocks, and meteorites.

Chromite symplectites in Mg-suite troctolite 76535 as evidence for infiltration metasomatism of a lunar layered intrusion

NASA Astrophysics Data System (ADS)

Elardo, Stephen M.; McCubbin, Francis M.; Shearer, Charles K.

2012-06-01

Despite the very low chromium concentrations in its cumulus olivine (˜140 ppm), lunar troctolite 76535 contains large amounts of Cr sporadically, but highly concentrated, in symplectite assemblages consisting of Mg-Al-chromite and two pyroxenes. Previously proposed symplectite formation mechanisms include crystallization of trapped interstitial melt, diffusion of Cr from cumulus olivine, and/or remobilization of cumulus chromite grains. These mechanisms would imply that the highly Cr-depleted nature of Mg-suite parental magmas and their source materials inferred from cumulus olivine may be illusory. We have conducted a detailed petrologic and textural study of symplectites, as well as chromite veins, intercumulus assemblages, olivine-hosted melt inclusions and clinopyroxene-troilite veins in 76535 with the goals of constraining the origin of the symplectites, and the degree of Cr-depletion in Mg-suite magmas relative to other lunar basalts. Orthopyroxene and clinopyroxene in melt inclusions are depleted in Cr relative to their symplectite counterparts, averaging 900 and 1200 ppm vs. 7400 and 8100 ppm Cr2O3, respectively. Olivine in contact with symplectite assemblages may exhibit a diffusion profile of Cr going into olivine, whereas olivine boundaries away from symplectites show no diffusion profile. There is also a distinct lack of primary chromite as inclusions in cumulus phases and melt inclusions. Multiple textural observations, melt inclusion chemistry, and modeling of chromite-olivine equilibrium rule out previously proposed symplectite formation mechanisms, and strongly suggest that chromite was not a primary crystallization product of the 76535 parental magma. Accordingly, the post-cumulus addition of Cr and Fe is required to produce the symplectites. After considering multiple models, the addition of Cr and Fe to 76535 via infiltration metasomatism by an exogenous chromite-saturated melt is the model most consistent with multiple textural and geochemical

Messengers from the deep: Fossil wadsleyite-chromite microstructures from the Mantle Transition Zone.

PubMed

Satsukawa, Takako; Griffin, William L; Piazolo, Sandra; O'Reilly, Suzanne Y

2015-11-13

Investigations of the Mantle Transition Zone (MTZ; 410-660 km deep) by deformation experiments and geophysical methods suggest that the MTZ has distinct rheological properties, but their exact cause is still unclear due to the lack of natural samples. Here we present the first direct evidence for crystal-plastic deformation by dislocation creep in the MTZ using a chromitite from the Luobusa peridotite (E. Tibet). Chromite grains show exsolution of diopside and SiO2, suggesting previous equilibration in the MTZ. Electron backscattered diffraction (EBSD) analysis reveals that olivine grains co-existing with exsolved phases inside chromite grains and occurring on chromite grain boundaries have a single pronounced crystallographic preferred orientation (CPO). This suggests that olivine preserves the CPO of a high-pressure polymorph (wadsleyite) before the high-pressure polymorph of chromite began to invert and exsolve. Chromite also shows a significant CPO. Thus, the fine-grained high-pressure phases were deformed by dislocation creep in the MTZ. Grain growth in inverted chromite produced an equilibrated microstructure during exhumation to the surface, masking at first sight its MTZ deformation history. These unique observations provide a window into the deep Earth, and constraints for interpreting geophysical signals and their geodynamic implications in a geologically robust context.

The origin of chromitic chondrules and the volatility of Cr under a range of nebular conditions

NASA Technical Reports Server (NTRS)

Krot, Alexander; Ivanova, Marina A.; Wasson, John T.

1993-01-01

We characterize ten chromatic chondrules, two spinelian chondrules andd one spinel-bearing chondrule and summarize data for 120 chromitic inclusions discovered in an extensive survey of ordinary chondrites. Compositional and petrographic evidence suggests that chromitic chondrules and inclusions are closely related. The Cr/(Cr + Al) ratios in the spinal of these objects range from 0.5 to 0.9 and bulk Al2O3 contents are uniformly high (greater than 10 wt%, except for one with 8 wt%). No other elements having comparable solar abundances are so stongly enriched, and alkali feldspar and merrillite are more common than in normal chondrules. The Cr/Mg ratios in chromitic chondrules are 180-750 times the ratios in the bulk chondrite. With the possible exception of magnetic clumping of chromite in the presolar cloud, mechanical processes cannot account for this enrichment. Examination of nebular equilibrium processes shows that 50%-condensation temperatures of Cr at pH2/pH2O of 1500 are several tens of degrees below those of Mg as Mg2SiO4; the condensation of Cr is primarily as MgCr2O4 dissolved in MgAl2O4 at nebular pressures of 10(exp -4) atm or below. At pH2 = 10(exp -3) atm condesation as Cr in Fe-Ni is favored. Making the nebula much more oxidizing reduces the difference in condensation temperatures but Mg remains more refractory. We conclude that nebular equilibrium processes are not responsible for the enhanced Cr/Mg ratios. We propose that both Cr and Al became enriched in residues formed by incomplete evaporation of presolar lumps. We suggest that spinals remained as solid phases when the bulk of the silicates were incorporated into the evaporating melt; vaporization of Al and Cr were inhibited by the slow kinetics of diffusion. Subsequent melting and crystallization of these residues fractionated Cr from Al. The resulting materials constituted major components in the precursors of chromitic chondrules. Our model implies that chromitic chondrules and inclusions

Encephalopathy caused by lanthanum carbonate.

PubMed

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

2011-06-01

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

Petrology of chromite in ureilites: Deconvolution of primary oxidation states and secondary reduction processes

NASA Astrophysics Data System (ADS)

Goodrich, Cyrena Anne; Harlow, George E.; Van Orman, James A.; Sutton, Stephen R.; Jercinovic, Michael J.; Mikouchi, Takashi

2014-06-01

Ureilites are ultramafic achondrites thought to be residues of partial melting on a carbon-rich asteroid. They show a trend of FeO-variation (olivine Fo from ∼74 to 95) that suggests variation in oxidation state. Whether this variation was established during high-temperature igneous processing on the ureilite parent body (UPB), or preserved from nebular precursors, is a subject of debate. The behavior of chromium in ureilites offers a way to assess redox conditions during their formation and address this issue, independent of Fo. We conducted a petrographic and mineral compositional study of occurrences of chromite (Cr-rich spinel) in ureilites, aimed at determining the origin of the chromite in each occurrence and using primary occurrences to constrain models of ureilite petrogenesis. Chromite was studied in LEW 88774 (Fo 74.2), NWA 766 (Fo 76.7), NWA 3109 (Fo 76.3), HaH 064 (Fo 77.5), LAP 03587 (Fo 74.9), CMS 04048 (Fo 76.4), LAP 02382 (Fo 78.6) and EET 96328 (Fo 85.2). Chromite occurs in LEW 88774 (∼5 vol.%), NWA 766 (<1 vol.%), NWA 3109 (<1 vol.%) and HaH 064 (<1 vol.%) as subhedral to anhedral grains comparable in size (∼30 μm to 1 mm) and/or textural setting to the major silicates (olivine and pyroxenes[s]) in each rock, indicating that it is a primary phase. The most FeO-rich chromites in these sample (rare grain cores or chadocrysts in silicates) are the most primitive compositions preserved (fe# = 0.55-0.6; Cr# varying from 0.65 to 0.72 among samples). They record olivine-chromite equilibration temperatures of ∼1040-1050 °C, reflecting subsolidus Fe/Mg reequilibration during slow cooling from ∼1200 to 1300 °C. All other chromite in these samples is reduced. Three types of zones are observed. (1) Inclusion-free interior zones showing reduction of FeO (fe# ∼0.4 → 0.28); (2) Outer zones showing further reduction of FeO (fe# ∼0.28 → 0.15) and containing abundant laths of eskolaite-corundum (Cr2O3-Al2O3); (3) Outermost zones showing extreme

Chromite oxidation by manganese oxides in subseafloor basalts and the presence of putative fossilized microorganisms.

PubMed

Ivarsson, Magnus; Broman, Curt; Holm, Nils G

2011-06-03

Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite. In the presence of Mn(IV) oxides, Cr(III) will oxidise to Cr(VI), which is more soluble than Cr(III), and thus easier to be removed. Here we report of chromite phenocrysts that are replaced by rhodochrosite (Mn(II) carbonate) in subseafloor basalts from the Koko Seamount, Pacific Ocean, that were drilled and collected during the Ocean Drilling Program (ODP) Leg 197. The mineral succession chromite-rhodochrosite-saponite in the phenocrysts is interpreted as the result of chromite oxidation by manganese oxides. Putative fossilized microorganisms are abundant in the rhodochrosite and we suggest that the oxidation of chromite has been mediated by microbial activity. It has previously been shown in soils and in laboratory experiments that chromium oxidation is indirectly mediated by microbial formation of manganese oxides. Here we suggest a similar process in subseafloor basalts.

Chromite oxidation by manganese oxides in subseafloor basalts and the presence of putative fossilized microorganisms

PubMed Central

2011-01-01

Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite. In the presence of Mn(IV) oxides, Cr(III) will oxidise to Cr(VI), which is more soluble than Cr(III), and thus easier to be removed. Here we report of chromite phenocrysts that are replaced by rhodochrosite (Mn(II) carbonate) in subseafloor basalts from the Koko Seamount, Pacific Ocean, that were drilled and collected during the Ocean Drilling Program (ODP) Leg 197. The mineral succession chromite-rhodochrosite-saponite in the phenocrysts is interpreted as the result of chromite oxidation by manganese oxides. Putative fossilized microorganisms are abundant in the rhodochrosite and we suggest that the oxidation of chromite has been mediated by microbial activity. It has previously been shown in soils and in laboratory experiments that chromium oxidation is indirectly mediated by microbial formation of manganese oxides. Here we suggest a similar process in subseafloor basalts. PMID:21639896

Reduction of Chromite in Liquid Fe-Cr-C-Si Alloys

NASA Astrophysics Data System (ADS)

Demir, Orhan; Eric, R. Hurman

1994-08-01

The kinetics and the mechanism of the reduction of chromite in Fe-Cr-C-Si alloys were studied in the temperature range of 1534 °C to 1702 °C under an inert argon atmosphere. The rotating cylinder technique was used. The melt consisted of 10 and 20 wt Pct chromium, the carbon content varied from 2.8 wt Pct to saturation, and the silicon content varied from 0 to 2 wt Pct. The rotational speed of the chromite cylinder ranged from 100 to 1000 rpm. The initial chromium to iron ratios of the melts varied between 0.11 and 0.26. In Fe-C melts, the effect of rotational speed on the reduction of chromite was very limited. Carbon saturation (5.4 wt Pct) of the alloy caused the reduction to increase 1.5 times over the reduction observed in the unsaturated (4.87 wt Pct) alloy at a given rotational speed. The addition of chromium to the carbon-saturated Fe-C alloy increased the reduction rate. The addition of silicon to the liquid phase increased the reduction rate drastically. The reduction of chromite in Fe-Cr-C melts is hindered because of the formation of, approximately, a 1.5-mm-thick M7C3-type carbide layer around the chromite cylinders. This carbide layer did not form when silicon was present in the melt. It was found that the reduction rate is controlled by the liquid-state mass transfer of oxygen. The calculated apparent activation energies for diffusion were 102.9 and 92.9 kJ/mol of oxygen in the Si-O and C-O systems, respectively.

Cytocompatibility of a free machining titanium alloy containing lanthanum.

PubMed

Feyerabend, Frank; Siemers, Carsten; Willumeit, Regine; Rösler, Joachim

2009-09-01

Titanium alloys like Ti6Al4V are widely used in medical engineering. However, the mechanical and chemical properties of titanium alloys lead to poor machinability, resulting in high production costs of medical products. To improve the machinability of Ti6Al4V, 0.9% of the rare earth element lanthanum (La) was added. The microstructure, the mechanical, and the corrosion properties were determined. Lanthanum containing alloys exhibited discrete particles of cubic lanthanum. The mechanical properties and corrosion resistance were slightly decreased but are still sufficient for many applications in the field of medical engineering. In vitro experiments with mouse macrophages (RAW 264.7) and human bone-derived cells (MG-63, HBDC) were performed and revealed that macrophages showed a dose response below and above a LaCl3 concentration of 200 microM, while MG-63 and HBDC tolerated three times higher concentrations without reduction of viability. The viability of cells cultured on disks of the materials showed no differences between the reference and the lanthanum containing alloy. We therefore propose that lanthanum containing alloy appears to be a good alternative for biomedical applications, where machining of parts is necessary.

The reduction mechanism of a natural chromite at 1416 °C

NASA Astrophysics Data System (ADS)

Soykan, O.; Eric, R. H.; King, R. P.

1991-02-01

The behavior of a natural chromite from the Bushveld Complex, Transvaal, South Africa, during reduction at 1416 °C by graphite was studied by means of thermogravimetric analysis, X-ray diffraction (XRD) analysis, energy-dispersive X-ray analysis (EDAX), and metallographic analysis. Experimental runs were allowed to proceed up to 120 minutes, resulting in 99 pct reduction. The specific objective of this study was to delineate the reduction mechanism of chromite by graphite. Zoning was observed in partially reduced chromites with degrees of reduction of up to about 70 pct. The inner cores were rich in iron, while the outer cores were depleted of iron. Energy-dispersive X-ray analysis revealed that Fe2+ and Cr3+ ions had diffused outward, whereas Cr2+, Al3+, and Mg2+ ions had diffused inward. The following mechanism of reduction, which is based on the assumption that the composition of the spinel phase remains stoichiometric with increasing degree of reduction, is proposed, (a) Initially, Fe3+ and Fe2+ ions at the surface of the chromite particle are reduced to the metallic state. This is followed immediately by the reduction of Cr3+ ions to the divalent state, (b) Cr2+ ions diffusing toward the center of the particle reduce the Fe3+ ions in the spinel under the surface of the particle to Fe2+ at the interface between the inner and outer cores. Fe2+ ions diffuse toward the surface, where they are reduced to metallic iron, (c) After the iron has been completely reduced, Cr3+ and any Cr2+ that is present are reduced to the metallic state, leaving an iron- and chromium-free spinel, MgAl2O4.

Adsorption and mineralization of REE-lanthanum onto bacterial cell surface.

PubMed

Cheng, Yangjian; Zhang, Li; Bian, Xiaojing; Zuo, Hongyang; Dong, Hailiang

2017-07-11

A large number of rare earth element mining and application resulted in a series of problems of soil and water pollution. Environmental remediation of these REE-contaminated sites has become a top priority. This paper explores the use of Bacillus licheniformis to adsorb lanthanum and subsequent mineralization process in contaminated water. The maximum adsorption capacity of lanthanum on bacteria was 113.98 mg/g (dry weight) biomass. X-ray diffraction (XRD) and transmission electron microscopy (TEM) data indicated that adsorbed lanthanum on bacterial cell surface occurred in an amorphous form at the initial stage. Scanning electron microscopy with X-ray energy-dispersive spectroscopy (SEM/EDS) results indicated that lanthanum adsorption was correlated with phosphate. The amorphous material was converted into scorpion-like monazite (LaPO 4 nanoparticles) in a month. The above results provide a method of using bacterial surface as adsorption and nucleation sites to treat REE-contaminated water.

Potentiometric measurement of polymer-membrane electrodes based on lanthanum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saefurohman, Asep, E-mail: saefurohman.asep78@Gmail.com; Buchari,, E-mail: saefurohman.asep78@Gmail.com; Noviandri, Indra, E-mail: saefurohman.asep78@Gmail.com

2014-03-24

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

Modified Ion-Conducting Ceramics Based on Lanthanum Gallate: Synthesis, Structure, and Properties

NASA Astrophysics Data System (ADS)

Kaleva, G. M.; Politova, E. D.; Mosunov, A. V.; Sadovskaya, N. V.

2018-06-01

A review is presented of the synthesis and complex investigation of modified ion-conducting ceramics based on heterosubstituted lanthanum gallate as a promising electrolyte material for solid oxide fuel cells. The effect the composition of multicomponent complex oxides has on the structure, microstructure, and electrophysical properties of ceramics is examined. Samples of ceramics with new compositions are produced via solid-state synthesis and modified with lithium fluoride. A drop is observed in the sintering temperature of the ceramics, caused by the liquid phase mechanism of sintering as a result of the low-melting superstoichiometric quantities of the additive. The effect lithium fluoride has on the process of phase formation, microstructure, and conductivity of the ceramics is investigated. It is found that samples modified with lithium fluoride display high density, dense grain packing, and high values of electrical conductivity at high temperatures.

Platinum-group element abundance and distribution in chromite deposits of the Acoje Block, Zambales Ophiolite Complex, Philippines

USGS Publications Warehouse

Bacuta, G.C.; Kay, R.W.; Gibbs, A.K.; Lipin, B.R.

1990-01-01

Platinum-group elements (PGE) occur in ore-grade concentration in some of the chromite deposits related to the ultramafic section of the Acoje Block of the Zambales Ophiolite Complex. The deposits are of three types: Type 1 - associated with cumulate peridotites at the base of the crust; Type 2 - in dunite pods from the top 1 km of mantle harzburgite; and Type 3 - like Type 2, but in deeper levels of the harzburgite. Most of the deposites have chromite compositions that are high in Cr with Cr/(Cr + Al) (expressed as chromium index, Cr#) > 0.6; high-Al (Cr# Pd, thought to be characteristic of PGE-barren deposits) and positive slope (Ir < Pd, characteristic of PGE-rich deposits). Iridium, Ru and Os commonly occur as micron-size laurite (sulfide) inclusions in unfractured chromite. Laurite and native Os are also found as inclusions in interstitial sulfides. Platinum and Pd occur as alloy inclusions (and possibly as solid solution) in interstitial Ni-Cu sulfides and as tellurobismuthides in serpentine and altered sulfides. Variability of PGE distribution may be explained by alteration, crystal fractionation or partial melting processes. Alteration and metamorphism were ruled out, because PGE contents do not correlate with degree of serpentinization or the abundance and type (hydroxyl versus non-hydroxyl) of silicate inclusions in chromite. Preliminary Os isotopic data do not support crustal contamination as a source of the PGEs in the Acoje deposits. The anomalous PGE concentrations in Type 1 high-Cr chromite deposits are attributed to two stages of enrichment: an early enrichment of their mantle source from previous melting events and a later stage of sulfide segregation accompanying chromite crystallization. High-Al chromite deposits which crystallized from basalts derived from relatively low degrees of melting owe their low PGE content to partitioning of PGEs in sulfides and alloys that remain in the mantle. High-Cr deposits crystallized from melts that were

Kinetics of the reduction of bushveld complex chromite ore at 1416 °C

NASA Astrophysics Data System (ADS)

Soykan, O.; Eric, R. H.; King, R. P.

1991-12-01

The kinetics of the reduction of chromite ore from the LG-6 layer of the Bushveld Complex of the Transvaal in South Africa were studied at 1416 °C by the thermogravimetric analysis (TGA) technique. Spectroscopic graphite powder was employed as the reductant. The aim of this article is to present a kinetic model that satisfactorily describes the solid-state carbothermic reduction of chromite. A generalized rate model based on an ionic diffusion mechanism was developed. The model included the contribution of the interfacial area between partially reduced and unreduced zones in chromite particles and diffusion. The kinetic model described the process for degrees of reduction from 10 to 75 pet satisfactorily. It was observed that at a given particle size, the rate of reduction was controlled mainly by interfacial area up to about 40 pet reduction, after which the rate was dominated by diffusion. On the other hand, for a given degree of reduction, the contribution of the interfacial area to the rate increased, while that of diffusion decreased, with a decrease in the particle size. The value of the diffusion coefficient for the Fe2+ species at 1416 °C was calculated to be 2.63 x 10-2 cm2/s.

Thermoelectric Properties of Lanthanum Sulfide

NASA Technical Reports Server (NTRS)

Wood, C.; Lockwood, R.; Parker, J. B.; Zoltan, A.; Zoltan, L. D.; Danielson, L.; Raag, V.

1987-01-01

Report describes measurement of Seebeck coefficient, electrical resistivity, thermal conductivity, and Hall effect in gamma-phase lanthanum sulfide with composition of La3-x S4. Results of study, part of search for high-temperature thermoelectric energy-conversion materials, indicate this sulfide behaves like extrinsic semiconductor over temperature range of 300 to 1,400 K, with degenerate carrier concentration controlled by stoichiometric ratio of La to S.

Chemistry of chromites from Arroio Grande Ophiolite (Dom Feliciano Belt, Brazil) and their possible connection with the Nama Group (Namibia)

NASA Astrophysics Data System (ADS)

Ramos, Rodrigo Chaves; Koester, Edinei; Porcher, Carla Cristine

2017-12-01

The present paper shows a mineral chemistry study in chromites found in serpentine-talc schists of the Arroio Grande Ophiolite, located in the southeastern Dom Feliciano Belt, near the Brazil/Uruguay border. Using electron microscope scanning and electron microprobe techniques, this study found a supra-subduction zone signature in the chromites, together with evidence of metasomatism. It corroborates previous hypothesis that suggested a supra-subduction zone origin for the protoliths of the Arroio Grande meta-igneous rocks and a metasomatic origin for the chromite-bearing magnesian schists. The studied chromites present high Cr# (0.65-0.77) and Fe2+# (0.88-0.95), low MgO (0.85-2.47 wt%) and TiO2 (0.01-0.19 wt%) and anomalous high concentration of ZnO (up to 1.97 wt%). The results were compared with chemical data from detrital chromites from the Schwarzrand and Fish River Subgroups of the Nama Group (Namibia), demonstrating that they are compositionally similar with those found in the latter. These chromites, in turn, are believed to have been derived from the oceanic Marmora Terrane (Gariep Belt) in the west (present-day coordinates). Taking into consideration that oceanic metamafites from both the latter and the Arroio Grande Ophiolite share common bulk-rock geochemical features (in this paper interpreted as fragments of the same paleo-ocean floor - the Marmora back-arc basin), it is possible to raise the hypothesis that detrital material derived from the studied ophiolite might also be found in Nama Group. It is reinforced by the fact that sediments (related to the Pelotas-Aiguá Batholith granitoids) derived from the easternmost Dom Feliciano Belt, i.e. the region where Arroio Grande Ophiolite is located, is found in both Schwarzrand and Fish River Subgroups. Thus, we suggest that Arroio Grande Ophiolite detrital sediments might also have contributed to the Nama Basin infilling during Late Ediacaran-Lower Cambrian.

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

NASA Astrophysics Data System (ADS)

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

2009-10-01

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.

Stratiform chromite deposit model: Chapter E in Mineral deposit models for resource assessment

USGS Publications Warehouse

Schulte, Ruth F.; Taylor, Ryan D.; Piatak, Nadine M.; Seal, Robert R.

2012-01-01

Most environmental concerns associated with the mining and processing of chromite ore focus on the solubility of chromium and its oxidation state. Although trivalent chromium (Cr3+) is an essential micronutrient for humans, hexavalent chromium (Cr6+) is highly toxic. Chromium-bearing solid phases that occur in the chromite ore-processing residue, for example, can effect the geochemical behavior and oxidation state of chromium in the environment.

Fluoride removal in water by a hybrid adsorbent lanthanum-carbon.

PubMed

Vences-Alvarez, Esmeralda; Velazquez-Jimenez, Litza Halla; Chazaro-Ruiz, Luis Felipe; Diaz-Flores, Paola E; Rangel-Mendez, Jose Rene

2015-10-01

Various health problems associated with drinking water containing high fluoride levels, have motivated researchers to develop more efficient adsorbents to remove fluoride from water for beneficial concentrations to human health. The objective of this research was to anchor lanthanum oxyhydroxides on a commercial granular activated carbon (GAC) to remove fluoride from water considering the effect of the solution pH, and the presence of co-existing anions and organic matter. The activated carbon was modified with lanthanum oxyhydroxides by impregnation. SEM and XRD were performed in order to determine the crystal structure and morphology of the La(III) particles anchored on the GAC surface. FT-IR and pK(a)'s distribution were determined in order to elucidate both the possible mechanism of the lanthanum anchorage on the activated carbon surface and the fluoride adsorption mechanism on the modified material. The results showed that lanthanum ions prefer binding to carboxyl and phenolic groups on the activated carbon surface. Potentiometric titrations revealed that the modified carbon (GAC-La) possesses positive charge at a pH lower than 9. The adsorption capacity of the modified GAC increased five times in contrast to an unmodified GAC adsorption capacity at an initial F(-) concentration of 20 mg L(-1). Moreover, the presence of co-existing anions had no effect on the fluoride adsorption capacity at concentrations below 30 mg L(-1), that indicated high F(-) affinity by the modified adsorbent material (GAG-La). Copyright © 2015 Elsevier Inc. All rights reserved.

Lanthanum

MedlinePlus

... levels of phosphate in the blood can cause bone problems. Lanthanum is in a clsas of medications ... to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in ...

Investigation of nanocrystalline zinc chromite obtained by two soft chemical routes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gingasu, Dana; Mindru, Ioana, E-mail: imandru@yahoo.com; Culita, Daniela C.

2014-01-01

Graphical abstract: - Highlights: • Two soft chemical routes to synthesize zinc chromites are described. • Glycine is used as chelating agent (precursor method) and fuel (solution combustion method). • The synthesized chromites have crystallite size in the range of 18–27 nm. • An antiferromagnetic (AFM) transition is observed at about T{sub N} ∼ 18 K. - Abstract: Zinc chromite (ZnCr{sub 2}O{sub 4}) nanocrystalline powders were obtained by two different chemical routes: the precursor method and the solution combustion method involving glycine-nitrates. The complex compound precursors, [ZnCr{sub 2}(NH{sub 2}CH{sub 2}COO){sub 8}]·9H{sub 2}O and [ZnCr{sub 2}(NH{sub 2}CH{sub 2}COOH){sub 4.5}]·(NO{sub 3}){sub 8}·6H{submore » 2}O, were characterized by chemical analysis, infrared spectroscopy (IR), ultraviolet–visible spectroscopy (UV–vis) and thermal analysis. The structure, morphology, surface chemistry and magnetic properties of ZnCr{sub 2}O{sub 4} powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), infrared and Raman spectroscopy (RS), ultraviolet–visible spectroscopy (UV–vis) and magnetic measurements. X-ray diffraction patterns indicated the chromite spinel phase with good crystallinity and an average crystallite size of approximately 18–27 nm. The band gap values ranged between 3.31 and 3.33 eV. The magnetic measurements indicated an antiferromagnetic transition at T{sub N} ∼ 17.5/18 K.« less

Orthophosphate sorption onto lanthanum-treated lignocellulosic sorbents

Treesearch

Eun Woo Shin; K. G. Karthikeyan; Mandla A. Tshabalala

2005-01-01

Inorganic/organic hybrid adsorbents for removing orthophosphate from water were prepared by lanthanum (La) treatment of bark fiber, a lignocellulosic material obtained from juniper (Juniperusmonosperma). The La was anchored to the juniper bark (JB) fiber by ion exchange with Ca in the bark and was responsible for removing orthophosphate. Two La concentrations (0.01 and...

Catalytic asymmetric Michael reactions promoted by a lithium-free lanthanum-BINOL complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sasai, Hiroaki; Arai, Takayoshi; Shibasaki, Masakatsu

1994-02-23

In this communication, we report about a new lithium-free BINOL-lanthanum complex, which is quite effective in catalytic asymmetric Michael reaction. We have succeeded in developing effective asymmetric base catalysts, in particular, asymmetric ester enolate catalysts for asymmetric Michael reactions. Two asymmetric lanthanum complexes are now available, namely, BINOL-lanthanum-lithium complex, which is quite effective in catalytic asymmetric nitrosaldol reactions, and a new lithium-free BINOL-lanthanum ester enolate complex, that is very effective in catalytic asymmetric Michael reactions. The two complexes complement each other in their ability to catalyze asymmetric nitroaldol and asymmetric Michael reactions. 14 refs., 1 fig., 2 tabs.

Leaching behavior of lanthanum, nickel and iron from spent catalyst using inorganic acids

NASA Astrophysics Data System (ADS)

Astuti, W.; Prilitasari, N. M.; Iskandar, Y.; Bratakusuma, D.; Petrus, H. T. B. M.

2018-01-01

Highly technological applications of rare earth metals (REs) and scarcity of supply have become an incentive torecover the REs from various resources, which include high grade and low grade ores, as well as recycledwaste materials. Spent hydrocracking catalyst contain lanthanum and a variety of valuable metals such as nickel and iron. This study investigated the recovery of lanthanum, nickel and iron from spent hydrocracking catalyst by leaching using various inorganic acid (sulfuric acid, hydrochloric acid, and nitric acid). The effect of acid concentration, type of acid and leaching temperature was conducted to study the leaching behavior of each valuable metal from spent-catalyst. It has been shown that it is possible to recover more than 90% of lanthanum, however the leaching efficiency of nickel and iron in this process was very low. It can be concluded that the leaching process is selective for lanthanum recovery from hydrocracking spent-catalyst.

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

DTIC Science & Technology

2014-11-01

Thangadurai V, Weppner W. Lithium lanthanum titanates: a review. Chemistry of Materials. 2003;15:3974–3990. 4. Knauth P. Inorganic solid Li ion conductors...an overview. Solid State Ionics. 2009;180:911–916. 5. Ban CW, Choi GM. The effect of sintering on the grain boundary conductivity of lithium ...lanthanum titanates. Solid State Ionics. 2001;140:285–292. 6. Inada R, Kimura K, Kusakabe K, Tojo T, Sakurai Y. Synthesis and lithium -ion conductivity

The Effect of Carbonaceous Reductant Selection on Chromite Pre-reduction

NASA Astrophysics Data System (ADS)

Kleynhans, E. L. J.; Beukes, J. P.; Van Zyl, P. G.; Bunt, J. R.; Nkosi, N. S. B.; Venter, M.

2017-04-01

Ferrochrome (FeCr) production is an energy-intensive process. Currently, the pelletized chromite pre-reduction process, also referred to as solid-state reduction of chromite, is most likely the FeCr production process with the lowest specific electricity consumption, i.e., MWh/t FeCr produced. In this study, the effects of carbonaceous reductant selection on chromite pre-reduction and cured pellet strength were investigated. Multiple linear regression analysis was employed to evaluate the effect of reductant characteristics on the aforementioned two parameters. This yielded mathematical solutions that can be used by FeCr producers to select reductants more optimally in future. Additionally, the results indicated that hydrogen (H)- (24 pct) and volatile content (45.8 pct) were the most significant contributors for predicting variance in pre-reduction and compressive strength, respectively. The role of H within this context is postulated to be linked to the ability of a reductant to release H that can induce reduction. Therefore, contrary to the current operational selection criteria, the authors believe that thermally untreated reductants ( e.g., anthracite, as opposed to coke or char), with volatile contents close to the currently applied specification (to ensure pellet strength), would be optimal, since it would maximize H content that would enhance pre-reduction.

Trace-element fingerprints of chromite, magnetite and sulfides from the 3.1 Ga ultramafic-mafic rocks of the Nuggihalli greenstone belt, Western Dharwar craton (India)

NASA Astrophysics Data System (ADS)

Mukherjee, Ria; Mondal, Sisir K.; González-Jiménez, José M.; Griffin, William L.; Pearson, Norman J.; O'Reilly, Suzanne Y.

2015-06-01

The 3.1 Ga Nuggihalli greenstone belt in the Western Dharwar craton is comprised of chromitite-bearing sill-like ultramafic-mafic rocks that are surrounded by metavolcanic schists (compositionally komatiitic to komatiitic basalts) and a suite of tonalite-trondhjemite-granodiorite gneissic rocks. The sill-like plutonic unit consists of a succession of serpentinite (after dunite)-peridotite-pyroxenite and gabbro with bands of titaniferous magnetite ore. The chromitite ore-bodies (length ≈30-500 m; width ≈2-15 m) are hosted by the serpentinite-peridotite unit. Unaltered chromites from massive chromitites (>80 % modal chromite) of the Byrapur and Bhaktarhalli chromite mines in the greenstone belt are characterized by high Cr# (100Cr/(Cr + Al)) of 78-86 and moderate Mg# (100 Mg/(Mg + Fe2+)) of 45-55. In situ trace-element analysis (LA-ICPMS) of unaltered chromites indicates that the parental magma of the chromitite ore-bodies was a komatiite lacking nickel-sulfide mineralization. In the Ga/Fe3+# versus Ti/Fe3+# diagram, the Byrapur chromites plot in the field of suprasubduction zone (SSZ) chromites while those from Bhaktarhalli lie in the MOR field. The above results corroborate our previous results based on major-element characteristics of the chromites, where the calculated parental melt of the Byrapur chromites was komatiitic to komatiitic basalt, and the Bhaktarhalli chromite was derived from Archean high-Mg basalt. The major-element chromite data hinted at the possibility of a SSZ environment existing in the Archean. Altered and compositionally zoned chromite grains in our study show a decrease in Ga, V, Co, Zn, Mn and enrichments of Ni and Ti in the ferritchromit rims. Trace-element heterogeneity in the altered chromites is attributed to serpentinization. The trace-element patterns of magnetite from the massive magnetite bands in the greenstone belt are similar to those from magmatic Fe-Ti-V-rich magnetite bands in layered intrusions, and magnetites from

Lanthanum-hexaboride carbon composition for use in corrosive hydrogen-fluorine environments

DOEpatents

Holcombe, Cressie E.; Kovach, Louis; Taylor, Albert J.

1981-01-01

The present invention relates to a structural composition useful in corrosive hydrogen-fluorine environments at temperatures in excess of 1400.degree. K. The composition is formed of a isostatically pressed and sintered or a hot-pressed mixture of lanthanum hexaboride particles and about 10-30 vol. % carbon. The lanthanum-hexaboride reacts with the high-temperature fluorine-containing bases to form an adherent layer of corrosion-inhibiting lanthanum trifluoride on exposed surfaces of the composition. The carbon in the composite significantly strengthens the composite, enhances thermal shock resistance, and significantly facilitates the machining of the composition.

METHOD FOR DISSOLVING LANTHANUM FLUORIDE CARRIER FOR PLUTONIUM

DOEpatents

Koshland, D.E. Jr.; Willard, J.E.

1961-08-01

A method is described for dissolving lanthanum fluoride precipitates which is applicable to lanthanum fluoride carrier precipitation processes for recovery of plutonium values from aqueous solutions. The lanthanum fluoride precipitate is contacted with an aqueous acidic solution containing dissolved zirconium in the tetravalent oxidation state. The presence of the zirconium increases the lanthanum fluoride dissolved and makes any tetravalent plutonium present more readily oxidizable to the hexavalent state. (AEC)

Lanthanum fluoride nanoparticles for radiosensitization of tumors

NASA Astrophysics Data System (ADS)

Kudinov, Konstantin; Bekah, Devesh; Cooper, Daniel; Shastry, Sathvik; Hill, Colin; Bradforth, Stephen; Nadeau, Jay

2016-03-01

Dense inorganic nanoparticles have recently been identified as promising radiosensitizers. In addition to dose enhancement through increased attenuation of ionizing radiation relative to biological tissue, scintillating nanoparticles can transfer energy to coupled photosensitizers to amplify production of reactive oxygen species, as well as provide UVvisible emission for optical imaging. Lanthanum fluoride is a transparent material that is easily prepared as nanocrystals, and which can provide radioluminescence at a number of wavelengths through simple substitution of lanthanum ions with other luminescent lanthanides. We have prepared lanthanum fluoride nanoparticles doped with cerium, terbium, or both, that have good spectral overlap with chlorine6 or Rose Bengal photosensitizer molecules. We have also developed a strategy for stable conjugation of the photosensitizers to the nanoparticle surface, allowing for high energy transfer efficiencies on a per molecule basis. Additionally, we have succeeded in making our conjugates colloidally stable under physiological conditions. Here we present our latest results, using nanoparticles and nanoparticle-photosensitizer conjugates to demonstrate radiation dose enhancement in B16 melanoma cells. The effects of nanoparticle treatment prior to 250 kVp x-ray irradiation were investigated through clonogenic survival assays and cell cycle analysis. Using a custom apparatus, we have also observed scintillation of the nanoparticles and conjugates under the same conditions that the cell samples are irradiated.

Superconductivity of lanthanum revisited

NASA Astrophysics Data System (ADS)

Loeptien, Peter; Zhou, Lihui; Wiebe, Jens; Khajetoorians, Alexander Ako; Wiesendanger, Roland

2014-03-01

The thickness dependence of the superconductivity in clean hexagonal lanthanum films grown on tungsten (110) is studied by means of scanning tunneling microscopy (STM) and spectroscopy (STS). Fitting of the measured spectra to BCS theory yields the superconducting energy gaps from which the critical temperatures are determined. For the case of thick, bulk-like films, the bulk energy gap and critical temperature of dhcp lanthanum turn out to be considerably higher as compared to values from the literature measured by other techniques. In thin films the superconductivity is quenched by the boundary condition for the superconducting wavefunction imposed by the substrate and surface, leading to a linear decrease of the superconducting transition temperature as a function of the inverse film thickness. This opens up the possibility to grow lanthanum films with defined superconducting properties.

Conditional estimates of the number of podiform chromite deposits

USGS Publications Warehouse

Singer, D.A.

1994-01-01

A desirable guide for estimating the number of undiscovered mineral deposits is the number of known deposits per unit area from another well-explored permissive terrain. An analysis of the distribution of 805 podiform chromite deposits among ultramafic rocks in 12 subareas of Oregon and 27 counties of California is used to examine and extend this guide. The average number of deposits in this sample of 39 areas is 0.225 deposits per km2 of ultramafic rock; the frequency distribution is significantly skewed to the right. Probabilistic estimates can be made by using the observation that the lognormal distribution fits the distribution of deposits per unit area. A further improvement in the estimates is available by using the relationship between the area of ultramafic rock and the number of deposits. The number (N) of exposed podiform chromite deposits can be estimated by the following relationship: log10(N)=-0.194+0.577 log10(area of ultramafic rock). The slope is significantly different from both 0.0 and 1.0. Because the slope is less than 1.0, the ratio of deposits to area of permissive rock is a biased estimator when the area of ultramafic rock is different from the median 93 km2. Unbiased estimates of the number of podiform chromite deposits can be made with the regression equation and 80 percent confidence limits presented herein. ?? 1994 Oxford University Press.

Lanthanum carbonate: safety data after 10 years.

PubMed

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

2016-12-01

Despite 10 years of post-marketing safety monitoring of the phosphate binder lanthanum carbonate, concerns about aluminium-like accumulation and toxicity persist. Here, we present a concise overview of the safety profile of lanthanum carbonate and interim results from a 5-year observational database study (SPD405-404; ClinicalTrials.gov identifier: NCT00567723). The pharmacokinetic paradigms of lanthanum and aluminium are different in that lanthanum is minimally absorbed and eliminated via the hepatobiliary pathway, whereas aluminium shows appreciable absorption and is eliminated by the kidneys. Randomised prospective studies of paired bone biopsies revealed no evidence of accumulation or toxicity in patients treated with lanthanum carbonate. Patients treated with lanthanum carbonate for up to 6 years showed no clinically relevant changes in liver enzyme or bilirubin levels. Lanthanum does not cross the intact blood-brain barrier. The most common adverse effects are mild/moderate nausea, diarrhoea and flatulence. An interim Kaplan-Meier analysis of SPD405-404 data from the United States Renal Data System revealed that the median 5-year survival was 51.6 months (95% CI: 49.1, 54.2) in patients who received lanthanum carbonate (test group), 48.9 months (95% CI: 47.3, 50.5) in patients treated with other phosphate binders (concomitant therapy control group) and 40.3 months (95% CI: 38.9, 41.5) in patients before the availability of lanthanum carbonate (historical control group). Bone fracture rates were 5.9%, 6.7% and 6.4%, respectively. After more than 850 000 person-years of worldwide patient exposure, there is no evidence that lanthanum carbonate is associated with adverse safety outcomes in patients with end-stage renal disease. © 2016 Shire Development LLC. Nephrology published by John Wiley & Sons Australia, Ltd on behalf of Asian Pacific Society of Nephrology.

Chromite and other mineral deposits in serpentine rocks of the Piedmont Upland, Maryland, Pennsylvania, and Delaware

USGS Publications Warehouse

Pearre, Nancy C.; Heyl, Allen V.

1960-01-01

The Piedmont Upland in Maryland, Pennsylvania, and Delaware is about 160 miles long and at the most 50 miles wide. Rocks that underlie the province are the Baltimore gneiss of Precambrian age and quartzite, gneiss, schist, marble, phyllite, and greenstone, which make up the Glenarm series of early Paleozoic (?) age. These are intruded by granitic, gabbroic, and ultramaflc igneous rocks. Most of the ultramaflc rocks, originally peridotite, pyroxenite, and dunite, have been partly or completely altered to serpentine and talc; they are all designated by the general term serpentine. The bodies of serpentine are commonly elongate and conformable with the enclosing rocks. Many have been extensively quarried for building, decorative, and crushed stone. In addition, chromite, titaniferous magnetite, rutile, talc and soapstone, amphibole asbestos, magnesite, sodium- rich feldspar (commercially known as soda spar), and corundum have been mined or prospected for in the serpentine. Both high-grade massive chromite and lower grade disseminated chromite occur in very irregular and unpredictable form in the serpentine, and placer deposits of chromite are in and near streams that drain areas underlain by serpentine. A group of unusual minerals, among them kammererite, are typical associates of high-grade massive chromite but are rare in lower grade deposits. Chromite was first discovered in the United States at Bare Hills, Md., around 1810. Between 1820 and 1850, additional deposits were discovered and mined in Maryland and Pennsylvania, including the largest deposit of massive chromite ever found in the United States the Wood deposit, in the State Line district. A second period of extensive chromite mining came during the late 1860's and early 1870's. Production figures are incomplete and conflicting. Estimates from the available data indicate that the aggregate production from 27 of 40 known mines before 1900 totaled between 250,000 and 280,000 tons of lode-chromite ore

Geology and economic potential for chromite in the Zhob Valley ultramafic rock complex, Hindubagh, Quetta division, West Pakistan

USGS Publications Warehouse

Rossman, D.L.; Ahmad, Zaki; Rahman, Hamidur

1971-01-01

The ultramafic rocks making up the Zhob Valley igneous complex have yielded small amounts of metallurgical-grade chromite since the early part of the century. From 1968-1970 a cooperative study undertaken by the Geological Survey of Pakistan and the U. S. Geological Survey, under the auspices of the Government of Pakistan and the Agency for International Development, evaluated the chromite potential of the Zhob Valley area and provided data for effective exploration. The Jung Tor Ghar ultramafic rock mass, covering an area of about 45 square miles, is a thrust-fault block completely surrounded and underlain (?) by sedimentary rocks as young as Late Cretaceous in age. The igneous rocks were thrust from the northwest along an east-trending, north-dipping fault in Late Cretaceous or Paleocene time and were peneplaned, dissected, and deeply laterized by mid-Eocene time. The ultramafic rocks consist of interlayered harzburgite and dunite and a cross-cutting dunite here called transgressive dunite. Layered structure passes without discernible deviation from the interlayered harzburgite-dunite through the transgressive dunite. The lowest rocks in the mass, composed mainly of transgressive dunite, grade upward into the interlayered rock about 3,000 feet above the fault block base. The upper transgressive dunites tend to form interconnecting linear networks and probably a few pipe-like structures. The transgressive dunite is thought to have formed by action of water derived from the underlying sedimentary rocks; the water heated by the hot ultramafic rock (at the time of emplacement) altered the pyroxene to olivine and talc, and, with lowering temperature, to serpentine. Other interpretations are possible. Virtually all the chromite in the Jung Tor Ghar lies in or immediately above the masses of transgressive dunite. This fact provides a key to chromite exploration: The most favorable zone for prospecting lies in the vicinity of the upper contacts of the transgressive

Pharmacology of the Phosphate Binder, Lanthanum Carbonate

PubMed Central

Damment, Stephen JP

2011-01-01

Studies were conducted to compare the phosphate-binding efficacy of lanthanum carbonate directly with other clinically used phosphate binders and to evaluate any potential adverse pharmacology. To examine the phosphate-binding efficacy, rats with normal renal function and chronic renal failure received lanthanum carbonate, aluminum hydroxide, calcium carbonate, or sevelamer hydrochloride in several experimental models. Lanthanum carbonate and aluminum hydroxide markedly increased excretion of [32P]-phosphate in feces and reduced excretion in urine in rats with normal renal function (p < 0.05), indicating good dietary phosphate-binding efficacy. In rats with chronic renal failure, lanthanum carbonate and aluminum hydroxide reduced urinary phosphate excretion to a greater degree and more rapidly than calcium carbonate, which in turn was more effective than sevelamer hydrochloride. The potential to induce adverse pharmacological effects was assessed systematically in mice, rats, and dogs with normal renal function using standard in vivo models. There was no evidence of any adverse secondary pharmacological effects of lanthanum carbonate on the central nervous, cardiovascular, respiratory, or gastrointestinal systems. These studies indicate that lanthanum carbonate is the more potent of the currently available dietary phosphate binders. No adverse secondary pharmacological actions were observed in vivo in a systematic evaluation at high doses. PMID:21332344

Anomalous Hall effect in calcium-doped lanthanum cobaltite and gadolinium

NASA Astrophysics Data System (ADS)

Baily, Scott Alan

The physical origin of the anomalous (proportional to magnetization) Hall effect is not very well understood. While many theories account for a Hall effect proportional to the magnetization of a material, these theories often predict effects significantly smaller than those found in ferromagnetic materials. An even more significant deficiency of the conventional theories is that they predict an anomalous Hall resistivity that is proportional to a power of the resistivity, and in the absence of a metal insulator transition cannot account for the anomalous Hall effect that peaks near TC. Recent models based on a geometric, or Berry, phase have had a great deal of success describing the anomalous Hall effect in double-exchange systems (e.g., lanthanum manganite and chromium dioxide). In gadolinium, as in double-exchange magnets, the exchange interaction is mediated by the conduction electrons and the anomalous Hall effect may therefore resemble that of CrO2 and other metallic double-exchange ferromagnets. Lanthanum cobaltite is similar to manganite in many ways, but a strong double-exchange interaction is not present. Calcium-doped lanthanum cobaltite films were found to have the largest anomalous Hall effect of any ferromagnetic metal. The primary purpose of this study is to gain insight into the origin of the anomalous Hall effect with the hope that these theories can be extended to account for the effect in other materials. The Hall resistivity, magnetoresistance, and magnetization of a Gadolinium single crystal were measured in fields up to 30 T. Cobaltite films were grown via laser ablation and characterized by a variety of techniques. Hall resistivity, magnetoresistance, magnetization, and magnetothermopower of L 1-xCaxCoO3 samples with 0.15 < x < 0.4 were measured in fields up to 7 T. The Gd results suggest that Berry's phase contributes partially to the Hall effect near TC. Berry's phase theories hold promise for explaining the large anomalous Hall effect in

Field free, directly heated lanthanum boride cathode

DOEpatents

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

1987-02-02

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.

Recent advances of lanthanum-based perovskite oxides for catalysis

DOE PAGES

Zhu, Huiyuan; Zhang, Pengfei; Dai, Sheng

2015-09-21

There is a need to reduce the use of noble metal elements especially in the field of catalysis, where noble metals are ubiquitously applied. To this end, perovskite oxides, an important class of mixed oxide, have been attracting increasing attention for decades as potential replacements. Benefiting from the extraordinary tunability of their compositions and structures, perovskite oxides can be rationally tailored and equipped with targeted physical and chemical properties e.g. redox behavior, oxygen mobility, and ion conductivity for enhanced catalysis. Recently, the development of highly efficient perovskite oxide catalysts has been extensively studied. This review article summarizes the recent developmentmore » of lanthanum-based perovskite oxides as advanced catalysts for both energy conversion applications and traditional heterogeneous reactions.« less

Compositional variations in the Mesoarchean chromites of the Nuggihalli schist belt, Western Dharwar Craton (India): potential parental melts and implications for tectonic setting

NASA Astrophysics Data System (ADS)

Mukherjee, Ria; Mondal, Sisir K.; Rosing, Minik T.; Frei, Robert

2010-12-01

The chromite deposits in the Archean Nuggihalli schist belt are part of a layered ultramafic-mafic sequence within the Western Dharwar Craton of the Indian shield. The 3.1-Ga ultramafic-mafic units occur as sill-like intrusions within the volcano-sedimentary sequences of the Nuggihalli greenstone belt that are surrounded by the tonalite-trondhjemite-granodiorite (TTG) suite of rocks. The entire succession is exposed in the Tagdur mining district. The succession has been divided into the lower and the upper ultramafic units, separated by a middle gabbro unit. The ultramafic units comprise of deformed massive chromitite bodies that are hosted within chromite-bearing serpentinites. The chromitite bodies occur in the form of pods and elongated lenses (~60-500 m by ~15 m). Detailed electron microprobe studies reveal intense compositional variability of the chromite grains in silicate-rich chromitite (~50% modal chromite) and serpentinite (~2% modal chromite) throughout the entire ultramafic sequence. However, the primary composition of chromite is preserved in the massive chromitites (~60-75% modal chromite) from the Byrapur and the Bhaktarhalli mining district of the Nuggihalli schist belt. These are characterized by high Cr-ratios (Cr/(Cr + Al) = 0.78-0.86) and moderate Mg-ratios (Mg/(Mg + Fe2+) = 0.38-0.58). The compositional variability occurs due to sub-solidus re-equilibration in the accessory chromite in the serpentinite (Mg-ratio = 0.01-0.38; Cr-ratio = 0.02-0.99) and in silicate-rich chromitite (Mg-ratio = 0.06-0.48; Cr-ratio = 0.60-0.99). In the massive chromitites, the sub-solidus re-equilibration for chromite is less or absent. However, the re-equilibration is prominent in the co-existing interstitial and included olivine (Fo96-98) and pyroxene grains (Mg-numbers = 97-99). Compositional variability on the scale of a single chromite grain occurs in the form of zoning, and it is common in the accessory chromite grains in serpentinite and in the altered grains

Nanoscale assembly of lanthanum silica with dense and porous interfacial structures.

PubMed

Ballinger, Benjamin; Motuzas, Julius; Miller, Christopher R; Smart, Simon; Diniz da Costa, João C

2015-02-03

This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a predominantly mesoporous structure above a critical lanthanum concentration. This change manifests itself by the formation of a lanthanum silicate phase, which results from the reaction of lanthanum oxide nanoparticles with the silica matrix. This process converts the microporous silica into the denser silicate phase. Above a lanthanum to silica ratio of 0.15, the combination of growth and microporous silica consumption results in the formation of nanoscale hybrid lanthanum oxides, with the inter-nano-domain spacing forming mesoporous volume. As the size of these nano-domains increases with concentration, so does the mesoporous volume. The absence of lanthanum hydroxide (La(OH)3) suggests the formation of La2O3 surrounded by lanthanum silicate.

Thermodynamic properties of lanthanum in gallium-zinc alloys

NASA Astrophysics Data System (ADS)

Dedyukhin, A. S.; Shepin, I. E.; Kharina, E. A.; Shchetinskiy, A. V.; Volkovich, V. A.; Yamshchikov, L. F.

2016-09-01

Thermodynamic properties of lanthanum were determined in gallium-zinc alloys of the eutectic and over-eutectic compositions. The electromotive force measurements were used to determine thermodynamic activity and sedimentation technique to measure solubility of lanthanum in liquid metal alloys. Temperature dependencies of lanthanum activity, solubility and activity coefficients in alloys with Ga-Zn mixtures containing 3.64, 15 and 50 wt. % zinc were obtained.

Lanthanum deposition corresponds to white lesions in the stomach.

PubMed

Iwamuro, Masaya; Urata, Haruo; Tanaka, Takehiro; Kawano, Seiji; Kawahara, Yoshiro; Kimoto, Katsuhiko; Okada, Hiroyuki

2018-05-23

Although lanthanum deposition in the stomach has been most frequently reported to occur as white lesions, no study has investigated whether the white lesions observed during esophagogastroduodenoscopy are truly lanthanum-related. Here, we retrospectively investigated the amount of lanthanum in endoscopic biopsy specimens. We reviewed four patients showing gastric white spots or annular whitish mucosa in the gastric white lesions (Bw) and peripheral mucosa where the white substance was not endoscopically observed (Bp) during biopsy. We also reviewed three patients with diffuse whitish mucosa and three patients with no whitish lesions. We performed scanning electron microscopy and energy dispersive X-ray spectrometry to quantify the lanthanum elements (wt%) in the biopsy specimens. The amount of lanthanum in the Bw ranged from 0.15-0.31 wt%, whereas that of Bp was 0.00-0.13 wt%. The difference was statistically significant (P < 0.05). The amount of lanthanum in the Bw, endoscopically presented with white spots or annular whitish mucosa, was significantly higher than that of no whitish lesions (0.05-0.14 wt%, P < 0.05). The amount of lanthanum was also higher in the diffuse whitish mucosa (0.21-0.23 wt%) compared with no whitish lesions (P < 0.01). This study is the first to reveal that pathological lanthanum deposition corresponds to the endoscopically observed white lesions in the gastric mucosa. Therefore, during esophagogastroduodenoscopy, physicians should pay attention to possible presence of white lesions in patients treated with oral lanthanum carbonate to ensure prompt identification of associated issues. Copyright © 2018 Elsevier GmbH. All rights reserved.

Comparative Planetary Mineralogy: Co, Ni Systematics in Chromite from Planetary Basalts

NASA Technical Reports Server (NTRS)

Karner, J. M.; Shearer, C. K.; Papike, J. J.; Righter,K.

2005-01-01

Spinel is a minor but important phase in planetary basalts because its variable composition often reflects basalt petrogenesis. For example, complicated zoning trends in spinel can give clues to melt evolution [1], and V concentrations in chromite lend insight into magma oxygen fugacity (fO2) conditions [2]. Nickel and Co are two elements that are commonly used as a measure of melt fractionation, and their partitioning between olivine and melt is fairly well understood. Less clear is their partitioning into spinel, although [3] has explored Ni and Co systematics in experimental charges. This study documents Ni and Co behavior in early crystallizing spinel (chromite) from several planetary basalts in an attempt to compare our results with [3], and also gain insight into basalt evolution on the three planets.

Metallic behavior of lanthanum disilicide

NASA Technical Reports Server (NTRS)

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

1988-01-01

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.

Chromite and olivine in type II chondrules in carbonaceous and ordinary chondrites - Implications for thermal histories and group differences

NASA Technical Reports Server (NTRS)

Johnson, Craig A.; Prinz, Martin

1991-01-01

Unequilibrated chromite and olivine margin compositions in type II chondrules are noted to differ systematically among three of the chondrite groups, suggesting that type II liquids differed in composition among the groups. These differences may be interpreted as indicators of different chemical compositions of the precursor solids which underwent melting, or, perhaps, as differences in the extent to which immiscible metal sulfide droplets were lost during chondrule formation. Because zinc is detectable only in type II chromites which have undergone reequilibration, the high zinc contents reported for chondritic chromites in other studies probably reflect redistribution during thermal metamorphism.

Cost-Effectiveness of First-Line Sevelamer and Lanthanum versus Calcium-Based Binders for Hyperphosphatemia of Chronic Kidney Disease.

PubMed

Habbous, Steven; Przech, Sebastian; Martin, Janet; Garg, Amit X; Sarma, Sisira

2018-03-01

Phosphate binders are used to treat hyperphosphatemia among patients with chronic kidney disease (CKD). To conduct an economic evaluation comparing calcium-free binders sevelamer and lanthanum with calcium-based binders for patients with CKD. Effectiveness data were obtained from a recent meta-analysis of randomized trials. Effectiveness was measured as life-years gained and translated to quality-adjusted life-years (QALYs) using utility weights from the literature. A Markov model consisting of non-dialysis-dependent (NDD)-CKD, dialysis-dependent (DD)-CKD, and death was developed to estimate the incremental costs and effects of sevelamer and lanthanum versus those of calcium-based binders. A lifetime horizon was used and both costs and effects were discounted at 1.5%. All costs are presented in 2015 Canadian dollars from the Canadian public payer perspective. Results of probabilistic sensitivity analysis were presented using cost-effectiveness acceptability curves. Sensitivity analyses were conducted for risk pooling methods, omission of dialysis costs, and persistence of drug effects on mortality. Sevelamer resulted in an incremental cost-effectiveness ratio of $106,522/QALY for NDD-CKD and $133,847/QALY for DD-CKD cohorts. Excluding dialysis costs, sevelamer was cost-effective in the NDD-CKD cohort ($5,847/QALY) and the DD-CKD cohort ($11,178/QALY). Lanthanum was dominated regardless of whether dialysis costs were included. Existing evidence does not clearly support the cost-effectiveness of non-calcium-containing phosphate binders (sevelamer and lanthanum) relative to calcium-containing phosphate binders in DD-CKD patients. Our study suggests that sevelamer may be cost-effective before dialysis onset. Because of the remaining uncertainty in several clinically relevant outcomes over time in DD-CKD and NDD-CKD patients, further research is encouraged. Copyright © 2018 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier

Crystallization of high-Ca chromium garnet upon interaction of serpentine, chromite, and Ca-bearing hydrous fluid

NASA Astrophysics Data System (ADS)

Chepurov, A. A.; Turkin, A. I.; Pokhilenko, N. P.

2017-10-01

The results of experimental modeling of the conditions of crystallization of high-Ca chromium garnets in the system serpentine-chromite-Ca-Cr-bearing hydrous fluid at a pressure of 5 GPa and temperature of 1300°C are reported. The mineral association including quantitatively predominant high-Mg olivine and diopside-rich clinopyroxene, bright-green garnet, and newly formed chrome spinel was formed. Garnet mostly crystallized around primary chromite grains and was characterized by a high concentration of CaO and Cr2O3. According to the chemical composition, garnets obtained are close to the uvarovite-pyrope varieties, which enter the composition of relatively rare natural paragenesis of garnet wehrlite. The experimental data obtained clearly show that high-Ca chromium garnets are formed in the reaction of chromite-bearing peridotite and Ca-rich fluid at high P-T parameters.

Fabrication of Lanthanum Telluride 14-1-11 Zintl High-Temperature Thermoelectric Couple

NASA Technical Reports Server (NTRS)

Ravi, Vilupanur A.; Li, Billy Chun-Yip; Fleurial, Pierre; Star, Kurt

2010-01-01

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

The reduction mechanism of chromite in the presence of a silica flux

NASA Astrophysics Data System (ADS)

Weber, P.; Eric, R. H.

1993-12-01

The reduction behavior of a natural chromite from the Bushveld Complex of South Africa was studied at 1300 °C to 1500 °C. Reduction was by graphite in the presence of silica. Thermo-gravimetric analysis, X-ray diffraction (XRD) analysis, energy-dispersive X-ray analysis (EDAX), and metallographic analysis were the experimental techniques used. Silica affected the reduction at and above 1400 °C. A two-stage reduction mechanism was established. The first stage, up to a reduction level of about 40 pct, is primarily confined to iron metallization, and zoning is observed in partially reduced chromites. In this stage, silica does not interfere with the reduction, which proceeds by an outward diffusion of Fe2+ ions and an inward diffusion of Mg2+ and Cr2+ ions. The second stage is primarily confined to chromium metallization, and formation of a silicate slag alters the reduction mechanism. The slag phase agglomerates and even embeds partially reduced chromite particles. An ion-exchange reaction between the re-ducible cations (Cr3+ and Fe2+) in the spinel and the dissolved cations (Al3+ and Mg2+) in the slag allows further reduction. Once the reducible cations are dissolved in the slag phase, they are reduced to the metallic state at sites where there is contact with the reductant.

Phosphate-binding efficacy of crushed vs. chewed lanthanum carbonate in hemodialysis patients.

PubMed

How, Priscilla P; Anattiwong, Prathana; Mason, Darius L; Arruda, Jose A; Lau, Alan H

2011-01-01

Lanthanum carbonate, a chewable noncalcium-containing phosphorus (P) binder, is useful for treating secondary hyperparathyroidism in patients who have hypercalcemia and cannot swallow whole tablets. However, some patients cannot chew tablets or prefer to crush and mix them with food. This study was conducted to determine the P-binding efficacy of crushed lanthanum and compare it with chewed lanthanum in hemodialysis (HD) patients. After a 1-week washout period, 11 hemodialysis patients (7 men, 4 women) were randomized to receive, in a crossover fashion, lanthanum 1000 mg 3 times daily chewed with meals and lanthanum 1000 mg 3 times daily crushed into a fine powder, mixed with applesauce and taken with meals, for 4 weeks each. Serum P was measured at the end of each washout (baseline) and weekly during treatment. Changes in serum P from baseline for crushed lanthanum were compared with chewed lanthanum using paired sample t test. Administration of crushed lanthanum resulted in a significant reduction in serum P from baseline (P reduction [mg/dL] for crushed lanthanum in week 1: 2.1 ± 0.4, week 2: 1.7 ± 0.5, week 3: 1.7 ± 0.5, week 4: 1.7 ± 0.4, P<0.05). No statistically significant differences were observed in serum P reduction from baseline and serum P attained during treatment with crushed when compared with chewed lanthanum. Crushed lanthanum is effective in reducing serum P and have similar P-binding efficacy to chewed lanthanum. Crushing lanthanum and mixing it with food can thus be an option for patients who are unable to chew or swallow whole tablets. © 2010 The Authors. Hemodialysis International © 2010 International Society for Hemodialysis.

Intermediate temperature solid oxide fuel cell based on lanthanum gallate electrolyte

NASA Astrophysics Data System (ADS)

Inagaki, Toru; Nishiwaki, Futoshi; Yamasaki, Satoru; Akbay, Taner; Hosoi, Kei

The Kansai Electric Power Co. Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been developing intermediate temperature solid oxide fuel cells (IT-SOFCs) which are operable at a temperature range between 600 and 800 °C. There are some significant features in IT-SOFC of KEPCO-MMC: (1) highly conductive lanthanum gallate-based oxide is adopted as an electrolyte to realize high-performance disk-type electrolyte-supported cells; (2) the cell-stacks with seal-less structure using metallic separators allow residual fuel to burn around the stack and the combustion heat is utilized for thermally self-sustainable operation; (3) the separators have flexible arms by which separate compressive forces can be applied for manifold parts and interconnection parts. We are currently participating in the project by New Energy and Industrial Technology Development Organization (NEDO) to develop 10 kW-class combined heat and power (CHP) systems. In FY2006, a 10 kW-class module was developed, with which the electrical efficiency of 50%HHV was obtained based on DC 12.6 kW. In the first quarter of FY2007, the 10 kW-class CHP system using the module gave the electrical efficiency of 41%HHV on AC 10 kW and the overall efficiency of 82%HHV when exhaust heat was recovered as 60 °C hot water. Currently, the operation has been accumulated for about 2500 h to evaluate the long-term stability of the system.

Preparation of thin ceramic films via an aqueous solution route

DOEpatents

Pederson, Larry R.; Chick, Lawrence A.; Exarhos, Gregory J.

1989-01-01

A new chemical method of forming thin ceramic films has been developed. An aqueous solution of metal nitrates or other soluble metal salts and a low molecular weight amino acid is coated onto a substrate and pyrolyzed. The amino acid serves to prevent precipitation of individual solution components, forming a very viscous, glass-like material as excess water is evaporated. Using metal nitrates and glycine, the method has been demonstrated for zirconia with various levels of yttria stabilization, for lanthanum-strontium chromites, and for yttrium-barium-copper oxide superconductors on various substrates.

Polarization study on doped lanthanum gallate electrolyte using impedance spectroscopy

NASA Astrophysics Data System (ADS)

Gong, Wenquan; Gopalan, Srikanth; Pal, Uday B.

2004-06-01

Alternating current complex impedance spectroscopy studies were conducted on symmetrical cells of the type [gas, electrode/La1-x Sr x Ga1-y Mg y O3 (LSGM) electrolyte/electrode, gas]. The electrode materials were slurry-coated on both sides of the LSGM electrolyte support. The electrodes selected for this investigation are candidate materials for solid oxide fuel cell (SOFC) electrodes. Cathode materials include La1-x Sr x MnO3 (LSM), La1-x Sr x Co y Fe1-y O3 (LSCF), a two-phase particulate composite consisting of LSM and doped-lanthanum gallate (LSGM), and LSCF + LSGM. Pt metal electrodes were also used for the purpose of comparison. Anode material investigated was the Ni + Ce0.85Gd0.15O2 composite. The study revealed important details pertaining to the charge-transfer reactions that occur in such electrodes. The information obtained can be used to design electrodes for intermediate temperature SOFCs based on LSGM electrolytes.

DFT Studies on Interaction between Lanthanum and Hydroxyamide

NASA Astrophysics Data System (ADS)

Pati, Anindita; Kundu, T. K.; Pal, Snehanshu

2018-03-01

Extraction and separation of individual rare earth elements has been a challenge as they are chemically very similar. Solvent extraction is the most suitable way for extraction of rare earth elements. Acidic, basic, neutral, chelating are the major classes of extractants for solvent extraction of rare earth elements. The coordination complex of chelating extractants is very selective with positively charged metal ion. Hence they are widely used. Hydroxyamide is capable of forming chelates with metal cations. In this present study interactions of hydroxyamide ligand with lanthanum have been investigated using density functional theory (DFT). Two different functional such as raB97XD and B3LYP are applied along with 6-31+G(d,p) basis set for carbon, nitrogen, hydrogen and SDD basis set for lanthanum. Stability of formed complexes has been evaluated based on calculated interaction energies and solvation energies. Frontier orbital (highest occupied molecular orbital or HOMO and lowest unoccupied molecular orbital or LUMO) energies of the molecule have also been calculated. Electronegativity, chemical hardness, chemical softness and chemical potential are also determined for these complexes to get an idea about the reactivity. From the partial charge distribution it is seen that oxygen atoms in hydroxyamide have higher negative charge. The double bonded oxygen atom present in the hydroxyamide structure has higher electron density and so it forms bond with lanthanum but the singly bonded oxygen atom in the hydroxyamide structure is weaker donor atom and so it is less available for interaction with lanthanum.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menaka; Patra, Rajkumar; Ghosh, Santanu

2012-10-15

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

Toward laser cooling and trapping lanthanum ions

NASA Astrophysics Data System (ADS)

Olmschenk, Steven; Banner, Patrick; Hankes, Jessie; Nelson, Amanda

2017-04-01

Trapped atomic ions are a leading candidate for applications in quantum information. For scalability and applications in quantum communication, it would be advantageous to interface ions with telecom light. We present progress toward laser cooling doubly-ionized lanthanum, which should require only infrared, telecom-compatible light. Since the hyperfine structure of this ion has not been measured, we are using optogalavanic spectroscopy in a hollow cathode lamp to measure the hyperfine spectrum of transitions in lanthanum. Using laser ablation to directly produce ions from a solid target, we laser cool and trap barium ions, and explore extending this technique to lanthanum ions. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

SEM, optical, and Moessbauer studies of submicrometer chromite in Allende

NASA Technical Reports Server (NTRS)

Housley, R. M.

1982-01-01

New scanning electron and optical microscope results are presented showing that sub-micrometer chromite is abundant along healed cracks and grain boundaries in Allende chondrule olivine. Some wider healed cracks also contain pentlandite and euhedral Ni3Fe grains. Also reported are Moessbauer measurements on Allende HF-HCl residues confirming a high Fe(+++)/Fe(++) ratio.

The structure of and origin of nodular chromite from the Troodos ophiolite, Cyprus, revealed using high-resolution X-ray computed tomography and electron backscatter diffraction

NASA Astrophysics Data System (ADS)

Prichard, H. M.; Barnes, S. J.; Godel, B.; Reddy, S. M.; Vukmanovic, Z.; Halfpenny, A.; Neary, C. R.; Fisher, P. C.

2015-03-01

Nodular chromite is a characteristic feature of ophiolitic podiform chromitite and there has been much debate about how it forms. Nodular chromite from the Troodos ophiolite in Cyprus is unusual in that it contains skeletal crystals enclosed within the centres of the nodules and interstitial to them. 3D imaging and electron backscatter diffraction have shown that the skeletal crystals within the nodules are single crystals that are surrounded by a rim of polycrystalline chromite. 3D analysis reveals that the skeletal crystals are partially or completely formed cage or hopper structures elongated along the < 111 > axis. The rim is composed of a patchwork of chromite grains that are truncated on the outer edge of the rim. The skeletal crystals formed first from a magma supersaturated in chromite and silicate minerals crystallised from melt trapped between the chromite skeletal crystal blades as they grew. The formation of skeletal crystals was followed by a crystallisation event which formed a silicate-poor rim of chromite grains around the skeletal crystals. These crystals show a weak preferred orientation related to the orientation of the core skeletal crystal implying that they formed by nucleation and growth on this core, and did not form by random mechanical aggregation. Patches of equilibrium adcumulate textures within the rim attest to in situ development of such textures. The nodules were subsequently exposed to chromite undersaturated magma resulting in dissolution, recorded by truncated grain boundaries in the rim and a smooth outer surface to the nodule. None of these stages of formation require a turbulent magma. Lastly the nodules impinged on each other causing local deformation at points of contact.

Multifunctionality of nanocrystalline lanthanum ferrite

NASA Astrophysics Data System (ADS)

Rai, Atma; Thakur, Awalendra K.

2016-05-01

Nanocrystalline lanthanum ferrite has been synthesized by adopting modified Pechini route. No evidence of impurity or secondary phase has been detected up to the detection of error limit of X-ray diffractometer (XRD). Rietveld refinement of X-ray diffraction pattern reveals orthorhombic crystal system with space group Pnma (62).Crystallite size and lattice strain was found to be ˜42.8nm and 0.306% respectively. Optical band gap was found to be 2.109 eV, by UV-Visible diffused reflectance spectrum (DRS). Brunauer-Emmet-Teller (BET) surface area was found to be ˜3.45 m2/g. Magnetization-hysteresis (M-H) loop was recorded at room temperature (300K) reveals weak ferromagnetism in Nanocrystalline lanthanum ferrite. The weak ferromagnetism in lanthanum ferrite is due to the uncompensated antiferromagnetic spin ordering. Ferroelectric loop hysteresis observed at room temperature at 100Hz depicts the presence of ferroelectric ordering in LaFeO3.Simultanious presence of magnetic and ferroelectric ordering at room temperature makes it suitable candidate of Multiferroic family.

Mineralogy and origin of stichtite in chromite-bearing serpentinites

NASA Astrophysics Data System (ADS)

Ashwal, Lewis D.; Cairncross, Bruce

Stichtite, a rare (14 known localities worldwide) hydrated carbonate-hydroxide of Mg and Cr with ideal formula Mg6Cr2 (OH)16 CO3 . 4H2O, occurs exclusively in Cr-rich serpentinites of ophiolites or greenstone belts. Physical properties (hardness=1.5-2, specific gravity=2.16-2.2, perfect basal [0001] cleavage, grain size commonly < 100 μm) resemble talc, but the mineral has an attractive purple to lilac color; chemical analyses demonstrate it to be a non-silicate. Stichtite generally occurs as irregular to rounded masses (< 1 cm - 30 cm across) and as veinlets (< 1 mm - > 2 cm wide) within serpentinite. Macroscopic and microscopic textures, such as crosscutting veinlets and stringers, demonstrate that stichtite formation invariably post-dated serpentinization. In some specimens stichtite surrounds relict grains of Cr-rich spinel; in others stichtite has completely replaced euhedral or subhedral chromites. Chemical analyses of stichtites reveal substantial substitution of Al and Fe3+ for Cr in specimens from many localities, reflecting a possible compositional continuum between stichtite and rhombohedral polymorphs hydrotalcite (Mg6Al2 (OH)16 CO3 . 4H2O) and pyroaurite (Mg6Fe2 (OH)16 CO3 . 4H2O). We report the first electron microprobe analyses of stichtites from seven localities, and summarize all available published chemical data. Stichtites very likely inherited part of their trivalent cation chemistry from precursor Cr-rich spinels, but stichtite growth apparently post-dated characteristic ``ferritchromit'' alteration, as demonstrated by the depletion of Al and enrichment in Fe3+ in stichtite relative to primary chromite core compositions. Stichtite appears to form by reaction between serpentine and altered chromite, during addition of substantial fluid, either as separate H2O and CO2 phases, or as a mixed volatile phase. Such reactions must involve removal of substantial SiO2, possibly by transport and remote deposition of silica by throughgoing aqueous and

Optical characteristics of novel bulk and nanoengineered laser host materials

NASA Astrophysics Data System (ADS)

Prasad, Narasimha S.; Sova, Stacey; Kelly, Lisa; Bevan, Talon; Arnold, Bradley; Cooper, Christopher; Choa, Fow-Sen; Singh, N. B.

2018-02-01

The hexagonal apatite single crystals have been investigated for their applications as laser host materials. Czochralksi and flux growth methods have been utilized to obtain single crystals. For low temperature processing (<100 0C), several techniques for crystal growth have been developed. The hexagonal apatite structure (space group P63/m) is characteristic of several compounds, some of which have extremely interesting and useful properties as laser hosts and bone materials. Calcium lanthanum silicate (Nd-doped) and lanthanum aluminate material systems were studied in detail. Nanoengineered calcium and lanthanum based silicates were synthesized by a solution method and their optical and morphological characteristics were compared with Czochralski grown bulk hydroxyapatite single crystals. Materials were evaluated by absorbance, fluorescence and Raman characteristics. Neodymium, iron and chromium doped crystals grown by a solution method showed weak but similar optical properties to that of Czochralski grown single crystals.

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

NASA Astrophysics Data System (ADS)

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

2016-07-01

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

Detoxification and immobilization of chromite ore processing residue in spinel-based glass-ceramic.

PubMed

Liao, Chang-Zhong; Tang, Yuanyuan; Lee, Po-Heng; Liu, Chengshuai; Shih, Kaimin; Li, Fangbai

2017-01-05

A promising strategy for the detoxification and immobilization of chromite ore processing residue (COPR) in a spinel-based glass-ceramic matrix is reported in this study. In the search for a more chemically durable matrix for COPR, the most critical crystalline phase for Cr immobilization was found to be a spinel solid solution with a chemical composition of MgCr 1.32 Fe 0.19 Al 0.49 O 4 . Using Rietveld quantitative X-ray diffraction analysis, we identified this final product is with the phases of spinel (3.5wt.%), diopside (5.2wt.%), and some amorphous contents (91.2wt.%). The partitioning ratio of Cr reveals that about 77% of the Cr was incorporated into the more chemically durable spinel phase. The results of Cr K-edge X-ray absorption near-edge spectroscopy show that no Cr(VI) was observed after conversion of COPR into a glass-ceramic, which indicates successful detoxification of Cr(VI) into Cr(III) in the COPR-incorporated glass-ceramic. The leaching performances of Cr 2 O 3 and COPR-incorporated glass-ceramic were compared with a prolonged acid-leaching test, and the results demonstrate the superiority of the COPR-incorporated glass-ceramic matrix in the immobilization of Cr. The overall results suggest that the use of affordable additives has potential in more reliably immobilizing COPR with a spinel-based glass-ceramic for safer disposal of this hazardous waste. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation and Characterization of Lanthanum-Incorporated Hydroxyapatite Coatings on Titanium Substrates

PubMed Central

Lou, Weiwei; Dong, Yiwen; Zhang, Hualin; Jin, Yifan; Hu, Xiaohui; Ma, Jianfeng; Liu, Jinsong; Wu, Gang

2015-01-01

Titanium (Ti) has been widely used in clinical applications for its excellent biocompatibility and mechanical properties. However, the bioinertness of the surface of Ti has motivated researchers to improve the physicochemical and biological properties of the implants through various surface modifications, such as coatings. For this purpose, we prepared a novel bioactive material, a lanthanum-incorporated hydroxyapatite (La-HA) coating, using a dip-coating technique with a La-HA sol along with post-heat treatment. The XRD, FTIR and EDX results presented in this paper confirmed that lanthanum was successfully incorporated into the structure of HA. The La-HA coating was composed of rod-like particles which densely compacted together without microcracks. The results of the interfacial shear strength test indicated that the incorporation of lanthanum increased the bonding strength of the HA coating. The mass loss ratios under acidic conditions (pH = 5.5) suggested that the La-HA coatings have better acid resistance. The cytocompatibility of the La-HA coating was also revealed by the relative activity of alkaline phosphatase, cellular morphology and cell proliferation assay in vitro. The present study suggested that La-HA coated on Ti has promising potential for applications in the development of a new type of bioactive coating for metal implants. PMID:26404255

Textile Dye Removal from Aqueous Solution using Modified Graphite Waste/Lanthanum/Chitosan Composite

NASA Astrophysics Data System (ADS)

Kusrini, E.; Wicaksono, B.; Yulizar, Y.; Prasetyanto, EA; Gunawan, C.

2018-03-01

We investigated various pre-treatment processes of graphite waste using thermal, mechanical and chemical methods. The aim of this work is to study the performance of modified graphite waste/lanthanum/chitosan composite (MG) as adsorbent for textile dye removal from aqueous solution. Effect of graphite waste resources, adsorbent size and lanthanum concentration on the dye removal were studied in batch experiments. Selectivity of MG was also investigated. Pre-heated graphite waste (NMG) was conducted at 80°C for 1 h, followed by mechanical crushing of the resultant graphite to 75 μm particle size, giving adsorption performance of ˜58%, ˜67%, ˜93% and ˜98% of the model dye rhodamine B (concentration determined by UV-vis spectroscopy at 554 nm), methyl orange (464 nm), methylene blue (664 nm) and methyl violet (580 nm), respectively from aqueous solution. For this process, the system required less than ˜5 min for adsorbent material to be completely saturated with the adsorbate. Further chemical modification of the pre-treated graphite waste (MG) with lanthanum (0.01 – V 0.03 M) and chitosan (0.5% w/w) did not improve the performance of dye adsorption. Under comparable experimental conditions, as those of the ‘thermal-mechanical-pre-treated-only’ (NMG), modification of graphite waste (MG) with 0.03 M lanthanum and 0.5% w/w chitosan resulted in ˜14%, ˜47%, ˜72% and ˜85% adsorption of rhodamine B, methyl orange, methylene blue and methyl violet, respectively. Selective adsorption of methylene blue at most to ˜79%, followed by methyl orange, methyl violet and rhodamine B with adsorption efficiency ˜67, ˜38, and ˜9% sequentially using MG with 0.03 M lanthanum and 0.5% w/w chitosan.

Development of advanced thermoelectric materials

NASA Technical Reports Server (NTRS)

1984-01-01

The development of an advanced thermoelectric material for radioisotope thermoelectric generator (RTG) applications is reported. A number of materials were explored. The bulk of the effort, however, was devoted to improving silicon germanium alloys by the addition of gallium phosphide, the synthesis and evaluation of lanthanum chrome sulfide and the formulation of various mixtures of lanthanum sulfide and chrome sulfide. It is found that each of these materials exhibits promise as a thermoelectric material.

Image-based multi-scale simulation and experimental validation of thermal conductivity of lanthanum zirconate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Xingye; Hu, Bin; Wei, Changdong

Lanthanum zirconate (La2Zr2O7) is a promising candidate material for thermal barrier coating (TBC) applications due to its low thermal conductivity and high-temperature phase stability. In this work, a novel image-based multi-scale simulation framework combining molecular dynamics (MD) and finite element (FE) calculations is proposed to study the thermal conductivity of La2Zr2O7 coatings. Since there is no experimental data of single crystal La2Zr2O7 thermal conductivity, a reverse non-equilibrium molecular dynamics (reverse NEMD) approach is first employed to compute the temperature-dependent thermal conductivity of single crystal La2Zr2O7. The single crystal data is then passed to a FE model which takes into accountmore » of realistic thermal barrier coating microstructures. The predicted thermal conductivities from the FE model are in good agreement with experimental validations using both flash laser technique and pulsed thermal imaging-multilayer analysis. The framework proposed in this work provides a powerful tool for future design of advanced coating systems. (C) 2016 Elsevier Ltd. All rights reserved.« less

An Exercise in X-Ray Diffraction Using the Polymorphic Transition of Nickel Chromite.

ERIC Educational Resources Information Center

Chipman, David W.

1980-01-01

Describes a laboratory experiment appropriate for a course in either x-ray crystallography or mineralogy. The experiment permits the direct observation of a polymorphic transition in nickel chromite without the use of a special heating stage or heating camera. (Author/GS)

Co-settling of Chromite and Sulfide Melt Droplets and Trace Element Partitioning between Sulfide and Silicate Melts

NASA Astrophysics Data System (ADS)

Manoochehri, S.; Schmidt, M. W.; Guenther, D.

2013-12-01

Gravitational settling of immiscible, dense sulfide melt droplets together with other cumulate phases such as chromite, combined with downward percolation of these droplets through a cumulate pile, is thought to be one of the possible processes leading to the formation of PGE rich sulfide deposits in layered mafic intrusions. Furthermore some chromitite seams in the Merensky Reef (Bushveld Complex) are considered to be acting as a filter or barrier for further downward percolation of sulfide melts into footwall layers. To investigate the feasibility of such mechanical processes and to study the partitioning behavior of 50 elements including transition metals and REEs (but not PGEs) between a silicate and a sulfide melt, two separate series of high temperature (1250-1380 °C) centrifuge-assisted experiments at 1000 g, 0.4-0.6 GPa were conducted. A synthetic silicate glass with a composition representative of the parental magma of the Bushveld Complex (~ 55 wt% SiO2) was mixed with pure FeS powder. For the first series of experiments, 15 or 25 wt% natural chromite with average grain sizes of ~ 5 or 31 μm were added to a mixture of silicate glass and FeS (10 wt%) adding 1 wt% water. For the second series, a mixture of the same glass and FeS was doped with 50 trace elements. These mixtures were first statically equilibrated and then centrifuged. In the first experimental series, sulfide melt droplets settled together with, but did not segregate from chromite grains even after centrifugation at 1000 g for 12 hours. A change in initial chromite grain size and proportions didn't have any effect on segregation. Without chromite, the starting mixture resulted in the formation of large sulfide melt pools together with finer droplets still disseminated through the silicate glass and both at the bottom of the capsule. The incomplete segregation of sulfide melt is interpreted as being due to high interfacial energies between sulfide and silicate melts/crystals which hinder

Developmental status and system studies of the monolithic solid oxide fuel cell

NASA Astrophysics Data System (ADS)

Myles, K. M.

The monolithic solid oxide fuel cell (MSOFC) was invented at the Argonne National Laboratory in 1983 and is currently being developed by a team consisting of Argonne National Laboratory and Allied-Signal Aerospace/AiResearch. The MSOFC is an oxide ceramic structure in which appropriate electronic and ionic conductors are fabricated in a honeycomb shape similar to a block of corrugated paperboard. The electrolyte, which conducts oxygens ions from the air side to the fuel side, is yttria-stabilized zirconia (YSZ). All the other materials, that is, the nickel-YSZ anode, the strontium-doped lanthanum manganite cathode, and the doped lanthanum chromite interconnect (bipolar plate), are electronic conductors. These electronic and ionic conductors are arranged to provide short conduction paths to minimize resistive losses. The power density achievable with the MSOFC is expected to be about 8 kW/kg or 4 kW/l at fuel efficiencies over 50 percent, because of small cell size and low resistive losses in the materials. These performances have been approached in laboratory test fuel cell stacks of nominal 125-W capacities.

Diminiode thermionic energy conversion with lanthanum-hexaboride electrodes

NASA Technical Reports Server (NTRS)

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

1978-01-01

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.

Clinical Characteristics of Seven Patients with Lanthanum Phosphate Deposition in the Stomach.

PubMed

Murakami, Naoko; Yoshioka, Masao; Iwamuro, Masaya; Nasu, Junichirou; Nose, Soichiro; Shiode, Junji; Okada, Hiroyuki; Yamamoto, Kazuhide

2017-08-15

Objective To analyze the clinical characteristics and endoscopic features of patients with lanthanum deposition in the stomach. Patients We retrospectively reviewed seven patients with lanthanum deposition in the stomach who were diagnosed at Okayama Saiseikai General Hospital. We investigated the patient sex, age at diagnosis, medical and medication histories, gastrointestinal symptoms, complications, presence or absence of gastric atrophy, and outcome. We also investigated any changes in the endoscopic features if previous endoscopic images were available. Results Seven patients (six males and one female) had lanthanum deposition. The median age was 65 years (range, 50-79 years). All patients had been undergoing dialysis (continuous ambulatory peritoneal dialysis in one patient, hemodialysis in six patients). The dialysis period ranged from 16 to 73 months (median, 52 months). The patients had all been taking lanthanum carbonate for a period ranging from 5 to 45 months (median, 27 months). Gastric atrophy was noted in 6 patients (85.7%). One patient had difficulty swallowing, and 1 other patient had appetite loss. The other 5 patients were asymptomatic. Endoscopic features included annular whitish mucosa (n = 4), diffuse whitish mucosa (n = 3), and whitish spots (n = 2). Five patients underwent multiple esophagogastroduodenoscopy. The endoscopic features were unchanged in 2 patients, whereas the whitish mucosa became apparent and spread during the course in 3 patients. Conclusion We identified 7 patients with lanthanum deposition in the stomach. All patients showed whitish lesions macroscopically. Although the pathogenicity of gastric lanthanum deposition is uncertain, lanthanum-related lesions in the stomach progressed during continuous lanthanum phosphate intake in several patients.

Efficacy of chewed vs. crushed lanthanum on phosphorus binding in healthy volunteers.

PubMed

How, P P; Mason, D L; Arruda, J A; Lau, A H

2010-05-01

For effective dietary phosphorous (P) binding, patients are recommended to chew lanthanum tablets completely before swallowing, with or immediately after meals. However, some patients are unable to chew the tablets. It is not known if crushing the tablets prior to taking them with food is as efficacious as chewing them. This study was conducted to compare the efficacy of chewed vs. crushed lanthanum on P binding. 12 healthy subjects were randomized and crossed-over to receive: (A) a standardized meal containing 1 g (32 mmol) of elemental P; (B) a single 1 g oral dose of lanthanum, chewed and taken with the standardized meal; (C) a single 1 g oral dose of lanthanum, crushed into a fine powder using a pestle and mortar, mixed with applesauce, and taken with the standardized meal. Blood and urine samples were collected from baseline to 8 hours after meal completion. The changes in serum P, urinary P excretion and fractional excretion of P (FePi) were compared among treatment arms using ANOVA. Co-administration of lanthanum with meal resulted in a smaller increase in serum P, compared with meal alone (p < 0.05). The smaller increase in serum P was similar for both chewed and crushed lanthanum. The amount of P excreted and FePi were also lower when chewed or crushed lanthanum was administered with meal, compared with meal alone (p = n.s. and p < 0.05, respectively). Both chewed and crushed lanthanum are effective in lowering P absorption after a dietary P load.

Nutritional status and survival of maintenance hemodialysis patients receiving lanthanum carbonate.

PubMed

Komaba, Hirotaka; Kakuta, Takatoshi; Wada, Takehiko; Hida, Miho; Suga, Takao; Fukagawa, Masafumi

2018-04-16

Hyperphosphatemia and poor nutritional status are associated with increased mortality. Lanthanum carbonate is an effective, calcium-free phosphate binder, but little is known about the long-term impact on mineral metabolism, nutritional status and survival. We extended the follow-up period of a historical cohort of 2292 maintenance hemodialysis patients that was formed in late 2008. We examined 7-year all-cause mortality according to the serum phosphate levels and nutritional indicators in the entire cohort and then compared the mortality rate of the 562 patients who initiated lanthanum with that of the 562 propensity score-matched patients who were not treated with lanthanum. During a mean ± SD follow-up of 4.9 ± 2.3 years, 679 patients died in the entire cohort. Higher serum phosphorus levels and lower nutritional indicators (body mass index, albumin and creatinine) were each independently associated with an increased risk of death. In the propensity score-matched analysis, patients who initiated lanthanum had a 23% lower risk for mortality compared with the matched controls. During the follow-up period, the serum phosphorus levels tended to decrease comparably in both groups, but the lanthanum group maintained a better nutritional status than the control group. The survival benefit associated with lanthanum was unchanged after adjustment for time-varying phosphorus or other mineral metabolism parameters, but was attenuated by adjustments for time-varying indicators of nutritional status. Treatment with lanthanum is associated with improved survival in hemodialysis patients. This effect may be partially mediated by relaxation of dietary phosphate restriction and improved nutritional status.

Development of advanced thermoelectric materials, phase A

NASA Technical Reports Server (NTRS)

1980-01-01

Work performed on the chemical system characterized by chrome sulfide, chrome selenide, lanthanum selenide, and lanthanum sulfide is described. Most materials within the chemical systems possess the requisites for attractive thermoelectric materials. The preparation of the alloys is discussed. Graphs show the Seebeck coefficient, electrical resistivity, and thermal conductivity of various materials within the chemical systems. The results of selected doping are included.

The Preparation and Characterization of Materials.

ERIC Educational Resources Information Center

Wold, Aaron

1980-01-01

Presents several examples illustrating different aspects of materials problems, including problems associated with solid-solid reactions, sintering and crystal growth, characterization of materials, preparation and characterization of stoichiometric ferrites and chromites, copper-sulfur systems, growth of single crystals by chemical vapor…

Orientation and faulted structure of γ'-phases in lanthanum-alloyed Ni-Al-Cr superalloy

NASA Astrophysics Data System (ADS)

Nikonenko, Elena; Shergaeva, Lyubov'; Popova, Natalya; Koneva, Nina; Qin, Rongshan; Gromov, Victor; Fedorischeva, Marina

2017-12-01

The paper presents the transmission and the scanning electron microscope investigations of thin foils of Ni-Al-Cr-based superalloy, which is obtained by the directional crystallization technique. This superalloy contains γ'- and γ- phases. Additionally, lanthanum is introduced in the superalloy in 0.015, 0.10 and 0.30 wt % concentrations. The superalloy specimens are then subjected to 1273 K annealing during 10 and 25 h. It is shown that γ'-phase is major. In the superalloy, lanthanides La2Ni3 and Al2La are detected along with carbide La2C3 particles located on dislocations of the major phase. The amount of phases in the superalloy depends on its thermal treatment and lanthanum concentration. The investigations include the effect of annealing on scalar density of dislocations in γ'-phase. It is demonstrated that lanthanum alloying modifies the preferred orientation of γ'-phase. Annealing of lanthanum-alloyed superalloy causes the orientation dispersion. In γ'-phase, the correlation is observed between the degree of heterogeneity of solid solution and scalar dislocation density. It is shown that this heterogeneity results in the formation of high-density dislocations in γ'- phase.

Melt/mantle interaction and melt evolution in the Sartohay high-Al chromite deposits of the Dalabute ophiolite (NW China)

NASA Astrophysics Data System (ADS)

Zhou, M.-F.; Robinson, P. T.; Malpas, J.; Aitchison, J.; Sun, M.; Bai, W.-J.; Hu, X.-F.; Yang, J.-S.

2001-06-01

The Sartohay block of the Dalabute ophiolite consists chiefly of mantle harzburgite and lherzolite with minor dunite. These rocks host voluminous chromite deposits with lenticular or vein-like shapes. The podiform chromitites are associated with, and cross-cut by, numerous troctolite dykes. Chromite in the chromitites has Al 2O 3 (23-31 wt%), TiO 2 (0.29-0.44 wt%), and Cr 2O 3 contents (<45 wt%) with Cr#s [100Cr/(Cr+Al)] (<60), typical of high-Al chromite deposits. The host peridotites in Sartohay have been texturally and geochemically modified by magmas from which the high-Al chromitites and mafic dykes formed. Dunites commonly envelop the podiform chromite bodies and show transitional contacts with the peridotites. Some of the peridotites and chromitites contain plagioclase that crystallized from impregnated melts. The dunite locally grades into troctolite with increasing plagioclase contents. As a result of melt impregnation, peridotites and dunites show variable Ca and Al contents and LREE enrichment. The parental magma of the chromitites was likely tholeiitic in composition, derived from partial melting of the asthenospheric mantle in a rising diapir. The interaction between this magma and pre-existing lithospheric mantle, composed of depleted lherzolite, would have formed a more silicic, tholeiitic magma from which high-Al chromitites crystallized. During this interaction, harzburgite and dunite were depleted in modal pyroxene and enriched in some incompatible elements (such as Al, Ca and LREE) due to melt impregnation.

40 CFR 721.10370 - Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphonic acid, p-octyl-, lanthanum... New Uses for Specific Chemical Substances § 721.10370 Phosphonic acid, p-octyl-, lanthanum (3+) salt... substance identified as phosphinic acid, p-octyl-, lanthanum (3+) salt (2:1) (PMN P-10-99; CAS No. 1186211...

40 CFR 721.10370 - Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphonic acid, p-octyl-, lanthanum... New Uses for Specific Chemical Substances § 721.10370 Phosphonic acid, p-octyl-, lanthanum (3+) salt... substance identified as phosphinic acid, p-octyl-, lanthanum (3+) salt (2:1) (PMN P-10-99; CAS No. 1186211...

40 CFR 721.10370 - Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphonic acid, p-octyl-, lanthanum... New Uses for Specific Chemical Substances § 721.10370 Phosphonic acid, p-octyl-, lanthanum (3+) salt... substance identified as phosphinic acid, p-octyl-, lanthanum (3+) salt (2:1) (PMN P-10-99; CAS No. 1186211...

Dipicolinate Complexes of Gallium(III) and Lanthanum(III).

PubMed

Weekes, David M; Ramogida, Caterina F; Jaraquemada-Peláez, Maria de Guadalupe; Patrick, Brian O; Apte, Chirag; Kostelnik, Thomas I; Cawthray, Jacqueline F; Murphy, Lisa; Orvig, Chris

2016-12-19

Three dipicolinic acid amine-derived compounds functionalized with a carboxylate (H 3 dpaa), phosphonate (H 4 dppa), and bisphosphonate (H 7 dpbpa), as well as their nonfunctionalized analogue (H 2 dpa), were successfully synthesized and characterized. The 1:1 lanthanum(III) complexes of H 2 dpa, H 3 dpaa, and H 4 dppa, the 1:2 lanthanum(III) complex of H 2 dpa, and the 1:1 gallium(III) complex of H 3 dpaa were characterized, including via X-ray crystallography for [La 4 (dppa) 4 (H 2 O) 2 ] and [Ga(dpaa)(H 2 O)]. H 2 dpa, H 3 dpaa, and H 4 dppa were evaluated for their thermodynamic stability with lanthanum(III) via potentiometric and either UV-vis spectrophotometric (H 3 dpaa) or NMR spectrometric (H 2 dpa and H 4 dppa) titrations, which showed that the carboxylate (H 3 dpaa) and phosphonate (H 4 dppa) containing ligands enhanced the lanthanum(III) complex stability by 3-4 orders of magnitude relative to the unfunctionalized ligand (comparing log β ML and pM values) at physiological pH. In addition, potentiometric titrations with H 3 dpaa and gallium(III) were performed, which gave significantly (8 orders of magnitude) higher thermodynamic stability constants than with lanthanum(III). This was predicted to be a consequence of better size matching between the dipicolinate cavity and gallium(III), which was also evident in the aforementioned crystal structures. Because of a potential link between lanthanum(III) and osteoporosis, the ligands were tested for their bone-directing properties via a hydroxyapatite (HAP) binding assay, which showed that either a phosphonate or bisphosphonate moiety was necessary in order to elicit a chemical binding interaction with HAP. The oral activity of the ligands and their metal complexes was also assessed by experimentally measuring log P o/w values using the shake-flask method, and these were compared to a currently prescribed osteoporosis drug (alendronate). Because of the potential therapeutic applications of the radionuclides

DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

DOEpatents

Fries, B.A.

1959-11-10

A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

Raman spectroscopic features of Al- Fe3+- poor magnesiochromite and Fe2+- Fe3+- rich ferrian chromite solid solutions

NASA Astrophysics Data System (ADS)

Kharbish, Sherif

2018-04-01

Naturally occurring Al- Fe3 +- poor magnesiochromite and Fe2+- Fe3 +- rich ferrian chromite solid solutions have been analyzed by micro-Raman spectroscopy. The results reflect a strong positive correlation between the Fe3 + # [Fe3+/(Fe3 ++Cr + Al)] and the positions of all Raman bands. A positive correlation of the Raman band positions with Mg# [Mg/(Mg + Fe2 +)] is less stringent. Raman spectra of magnesiochromite and ferrian chromite show seven and six bands, respectively, in the spectral region of 800 - 100 cm- 1. The most intense band in both minerals is identified as symmetric stretching vibrational mode, ν 1( A 1 g ). In the intermediate Raman-shift region (400-600 cm- 1), the significant bands are attributed to the ν 3( F 2 g ) > ν 4( F 2 g ) > ν 2( E g ) modes. The bands with the lowest Raman shifts (< 200 cm- 1) are assigned to F 2 g ( trans) translatory lattice modes. Extra bands in magnesiochromite (two bands) and in ferrian chromite (one weak band) are attributed to lowering in local symmetry and order/disorder effects.

Enhancement of Superconductivity of Lanthanum and Yttrium Sesquicarbide

DOEpatents

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

1972-06-22

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

Enhancement of superconductivity of lanthanum and yttrium sesquicarbide

DOEpatents

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

1971-06-22

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

Solution processed lanthanum aluminate gate dielectrics for use in metal oxide-based thin film transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esro, M.; Adamopoulos, G., E-mail: g.adamopoulos@lancaster.ac.uk; Mazzocco, R.

2015-05-18

We report on ZnO-based thin-film transistors (TFTs) employing lanthanum aluminate gate dielectrics (La{sub x}Al{sub 1−x}O{sub y}) grown by spray pyrolysis in ambient atmosphere at 440 °C. The structural, electronic, optical, morphological, and electrical properties of the La{sub x}Al{sub 1−x}O{sub y} films and devices as a function of the lanthanum to aluminium atomic ratio were investigated using a wide range of characterization techniques such as UV-visible absorption spectroscopy, impedance spectroscopy, spectroscopic ellipsometry, atomic force microscopy, x-ray diffraction, and field-effect measurements. As-deposited LaAlO{sub y} dielectrics exhibit a wide band gap (∼6.18 eV), high dielectric constant (k ∼ 16), low roughness (∼1.9 nm), and very low leakage currentsmore » (<3 nA/cm{sup 2}). TFTs employing solution processed LaAlO{sub y} gate dielectrics and ZnO semiconducting channels exhibit excellent electron transport characteristics with hysteresis-free operation, low operation voltages (∼10 V), high on/off current modulation ratio of >10{sup 6}, subthreshold swing of ∼650 mV dec{sup −1}, and electron mobility of ∼12 cm{sup 2} V{sup −1} s{sup −1}.« less

SEPARATION OF PLUTONIUM FROM LANTHANUM BY CHELATION-EXTRACTION

DOEpatents

James, R.A.; Thompson, S.G.

1958-12-01

Plutonium can be separated from a mixture of plutonlum and lanthanum in which the lanthanum to plutonium molal ratio ls at least five by adding the ammonium salt of N-nitrosoarylhydroxylamine to an aqueous solution having a pH between about 3 and 0.2 and containing the plutonium in a valence state of at least +3, to form a plutonium chelate compound of N-nitrosoarylhydroxylamine. The plutonium chelate compound may be recovered from the solution by extracting with an immiscible organic solvent such as chloroform.

Effect of basicity on beneficiated chromite sand smelting process using submerged arc furnace

NASA Astrophysics Data System (ADS)

Nurjaman, F.; Subandrio, S.; Ferdian, D.; Suharno, Bambang

2018-05-01

Ferrochrome is an important alloy in stainless steel making due to its contribution to high strength and corrosion resistance. In this present study, ferrochrome was derived from Indonesian chromite sand with low-grade Cr/Fe ratio. In order to improve the ratio, beneficiation process such as pre-magnetic separation and reduction process at 1000°C for 60 minutes was required. The process followed by another magnetic separation, thus the Cr/Fe ratio was increased from 0.9 to 1.6. The reduction process used coconut shell charcoal as reductant and limestone as an additive. The beneficiated sand chromite was briquette using bentonite as a binder in 2 wt.% before it was smelted in a submerged electric arc furnace to produce ferrochrome. Basicity was controlled by the addition of limestone and it was varied from 0.4-1.6. Furthermore, the composition of ferrochrome was analyzed by using X-Ray Fluorescence. From this experiment, the result showed that chromium recovery and specific energy was decreased with the increasing of slag basicity.

Microbial leaching of chromite overburden from Sukinda mines, Orissa, India using Aspergillus niger

NASA Astrophysics Data System (ADS)

Biswas, Supratim; Samanta, Saikat; Dey, Rajib; Mukherjee, Siddhartha; Banerjee, Pataki C.

2013-08-01

Leaching of nickel and cobalt from two physical grades (S1, 125-190 μm, coarser and S3, 53-75 μm, finer) of chromite overburden was achieved by treating the overburden (2% pulp density) with 21-d culture filtrate of an Aspergillus niger strain grown in sucrose medium. Metal dissolution increases with ore roasting at 600°C and decreasing particle size due to the alteration of microstructural properties involving the conversion of goethite to hematite and the increase in surface area and porosity as evident from X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (DT-TGA), and field emission scanning electron microscopy (FESEM). About 65% Ni and 59% Co were recovered from the roasted S3 ore employing bioleaching against 26.87% Ni and 31.3% Co using an equivalent amount of synthetic oxalic acid under identical conditions. The results suggest that other fungal metabolites in the culture filtrate played a positive role in the bioleaching process, making it an efficient green approach in Ni and Co recovery from lateritic chromite overburden.

Lanthanum-hexaboride carbon composition for use in corrosive hydrogen-fluorine environments

DOEpatents

Holcombe, C.E. Jr.; Kovach, L.; Taylor, A.J.

1980-01-22

The present invention relates to a structural composition useful in corrosive hydrogen-fluorine environments at temperatures in excess of 1400/sup 0/K. The composition is formed of a isostatically pressed and sintered or a hot-pressed mixture of lanthanum hexaboride particles and about 10 to 30 vol% carbon. The lanthanum-hexaboride reacts with the high-temperature fluorine-containing gases to form an adherent layer of corrosion-inhibiting lanthanum trifluoride on exposed surfaces of the composition. The carbon in the composite significantly strengthens the composite, enhances thermal shock resistance, and significantly facilitates the machining of the composition.

Determination of Aluminum in Dialysis Concentrates by Atomic Absorption Spectrometry after Coprecipitation with Lanthanum Phosphate.

PubMed

Selvi, Emine Kılıçkaya; Şahin, Uğur; Şahan, Serkan

2017-01-01

This method was developed for the determination of trace amounts of aluminum(III) in dialysis concentrates using atomic absorption spectrometry after coprecipitation with lanthanum phosphate. The analytical parameters that influenced the quantitative coprecipitation of analyte including amount of lanthanum, amount of phosfate, pH and duration time were optimized. The % recoveries of the analyte ion were in the range of 95-105 % with limit of detection (3s) of 0.5 µg l -1 . Preconcentration factor was found as 1000 and Relative Standard Deviation (RSD) % value obtained from model solutions was 2.5% for 0.02 mg L -1 . The accuracy of the method was evaluated with standard reference material (CWW-TMD Waste Water). The method was also applied to most concentrated acidic and basic dialysis concentrates with satisfactory results.

Thermodynamic stability of perovskite and lanthanum nickelate-type cathode materials for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Cetin, Deniz

The need for cleaner and more efficient alternative energy sources is becoming urgent as concerns mount about climate change wrought by greenhouse gas emissions. Solid oxide fuel cells (SOFCs) are one of the most efficient options if the goal is to reduce emissions while still operating on fossil energy resources. One of the foremost problems in SOFCs that causes efficiency loss is the polarization resistance associated with the oxygen reduction reaction(ORR) at the cathodes. Hence, improving the cathode design will greatly enhance the overall performance of SOFCs. Lanthanum nickelate, La2NiO4+delta (LNO), is a mixed ionic and electronic conductor that has competitive surface oxygen exchange and transport properties and excellent electrical conductivity compared to perovskite-type oxides. This makes it an excellent candidate for solid oxide fuel cell (SOFC) applications. It has been previously shown that composites of LNO with Sm0.2Ce0.8O2-delta (SDC20) as cathode materials lead to higher performance than standalone LNO. However, in contact with lanthanide-doped ceria, LNO decomposes resulting in free NiO and ceria with higher lanthanide dopant concentration. In this study, the aforementioned instability of LNO has been addressed by compositional tailoring of LNO: lanthanide doped ceria (LnxCe 1-xO2,LnDC)composite. By increasing the lanthanide dopant concentration in the ceria phase close to its solubility limit, the LNO phase has been stabilized in the LNO:LnDC composites. Electrical conductivity of the composites as a function of LNO volume fraction and temperature has been measured, and analyzed using a resistive network model which allows the identification of a percolation threshold for the LNO phase. The thermomechanical compatibility of these composites has been investigated with SOFC systems through measurement of the coefficients of thermal expansion. LNO:LDC40 composites containing LNO lower than 50 vol%and higher than 40 vol% were identified as being

Lanthanum gallate substrates for epitaxial high-temperature superconducting thin films

NASA Astrophysics Data System (ADS)

Sandstrom, R. L.; Giess, E. A.; Gallagher, W. J.; Segmuller, A.; Cooper, E. I.

1988-11-01

It is demonstrated that lanthanum gallate (LaGaO3) has considerable potential as an electronic substrate material for high-temperature superconducting films. It provides a good lattice and thermal expansion match to YBa2Cu3O(7-x), can be grown in large crystal sizes, is compatible with high-temperature film processing, and has a reasonably low dielectric constant and low dielectric losses. Epitaxial YBa2Cu3O(7-x) films grown on LaGaO3 single-crystal substrates by three techniques have zero resistance between 87 and 91 K.

In vitro anticancer activities of Schiff base and its lanthanum complex

NASA Astrophysics Data System (ADS)

Neelima; Poonia, Kavita; Siddiqui, Sahabjada; Arshad, Md; Kumar, Dinesh

2016-02-01

Schiff base metal complexes are well-known to intercalate DNA. The La(III) complexes have been synthesized such that they hinder with the role of the topoisomerases, which control the topology of DNA during the cell-division cycle. Although several promising chemotherapeutics have been developed, on the basis of Schiff base metal complex DNA intercalating system they did not proceed past clinical trials due to their dose-limiting toxicity. Herein, we discuss an alternative compound, the La(III) complex, [La(L1)2Cl3]·7H2O based on a Schiff base ligand 2,3-dihydro-1H-indolo-[2,3-b]-phenazin-4(5H)-ylidene)benzothiazole-2-amine (L1), and report in vitro cell studies. Results of antitumor activity using cell viability assay, reactive oxygen species (ROS) generation and nuclear condensation in PC-3 (Human, prostate carcinoma) cells show that the metal complex is more potent than ligand. La(III) complexes have been synthesized by reaction of lanthanum(III) salt in 1:2 M ratio with ligands L1 and 3-(ethoxymethylene)-2,3-dihydro-1H-indolo[2,3-b]-phenazin-4(5H)-ylidene)benzathiazole-2-amine (L2) in methanol. The ligands and their La(III) complexes were characterized by molar conductance, magnetic susceptibility, elemental analyses, FT-IR, UV-Vis, 1H/13C NMR, thermogravimetric, XRD, and SEM analysis.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schoellhammer, Gunther; Herzig, Peter; Wolf, Walter

2011-09-01

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. Linearmore » 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.« less

Effects of anode material on arcjet performance

NASA Technical Reports Server (NTRS)

Sankovic, John M.; Curran, Frank M.; Larson, C. A.

1992-01-01

Anodes fabricated from four different materials were tested in a modular arcjet thruster at 1 kW power level on nitrogen/hydrogen mixtures. A two-percent thoriated tungsten anode served as the control. Graphite was chosen for its ease in fabrication, but experienced severe erosion in the constrictor and diverging side. Hafnium carbide and lanthanum hexaboride were chosen for their low work functions but failed due to thermal stress and reacted with the propellant. When compared to the thoriated tungsten nozzle, thruster performance was significantly lower for the lanthanum hexaboride insert and the graphite nozzle, but was slightly higher for the hafnium carbide nozzle. Both the lanthanum hexaboride and hafnium carbide nozzle operated at higher voltages. An attempt was made to duplicate higher performance hafnium carbide results, but repeated attempts at machining a second anode insert were unsuccessful. Graphite, hafnium carbide, and lanthanum hexaboride do not appear viable anode materials for low power arcjet thrusters.

Ames Lab 101: Lanthanum Decanting

ScienceCinema

Riedemann, Trevor

2018-04-27

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.

Revised energy levels of singly ionized lanthanum

NASA Astrophysics Data System (ADS)

Güzelçimen, Feyza; Tonka, Mehdi; Uddin, Zaheer; Bhatti, Naveed Anjum; Windholz, Laurentius; Kröger, Sophie; Başar, Gönül

2018-05-01

Based on the experimental wavenumbers of 344 spectral lines from calibrated Fourier transform (FT) spectra as well as wavenumbers of 81 lines from the wavelength tables from literature, the energy of 115 fine structure levels of singly ionized lanthanum has been revised by weighted global fits. The classifications of the lines are provided by numerous previous investigations of lanthanum by different spectroscopic methods and authors. For the high accurate determination of the center of gravity wavenumbers from the experimental spectrum, the hyperfine constants of the involved levels have been taken into account, if possible. For the 94 levels with known hyperfine constants the accuracy of energy values is better than 0.01 cm-1. For 34 levels the magnetic dipole hyperfine constants A have been determined from FT spectra as part of this work. For four of these 34 levels even electric quadrupole hyperfine constants B could be estimated. For levels, which have experimentally unknown hyperfine constants and which are connected only by lines not found in the FT spectra but taken from literature, the uncertainties of energy values are about a factor of 10 higher. A list of all revised level energies together with a compilation of hyperfine structure data is given as well as a list of all lines used.

The origin of current blocking in interfacial conduction in Sr-doped lanthanum gallates

NASA Astrophysics Data System (ADS)

Park, Hee Jung

2018-02-01

The grain boundary transport of lanthanum gallate has been studied with various doping concentrations, and the origins of blocking on the grain boundary are compared. La1-xSrxGaO3 samples (x = 0.005, 0.01, 0.05 and 0.1) have been prepared and their bulk (grain) and grain boundary resistances been experimentally measured as a function of temperature (T: 200-550 °C) and oxygen partial pressure (Po2) using ac-impedance measurements. In addition, Hebb-Wagner polarization measurements have been conducted to investigate the electrical conductivity of minor charge carriers in the lanthanum gallates. The grain boundary resistance in the low-doped materials (x = 0.005 and 0.01) increases with increasing Po2 while in the highly-doped materials (x = 0.05, 0.1) it hardly depended on Po2. At lower concentrations conduction is mixed and at higher concentrations is found to be predominantly ionic conductivity. The space charge model successfully describes the mixed conduction at the grain boundary at low-doping, but does not explain the predominant ionic conductivity at high-doping. The origin of blocking at high-doping is explained by the crystallographic asymmetry of the grain boundary with respect to the bulk and/or Sr-segregation.

The effect of physiologic aqueous solutions on the perovskite material lead-lanthanum-zirconium titanate (PLZT)

PubMed Central

Foster, William J.; Meen, James K.; Fox, Donald A.

2016-01-01

Context Perovskite compounds, including Lead-Lanthanum-Zirconium Titanate (PLZT), have wide technological application because of their unique physical properties. The use of PLZT in neuro-prosthetic systems, such as retinal implants, have been discussed in a number of publications. Since inorganic lead is a retinotoxic compound that produces retinal degeneration, the long-term stability of PLZT in aqueous biological solutions must be determined. Objective We evaluated the stability and effects of prolonged immersion of a PLZT-coated crystal in a buffered balanced salt solution. Materials and Methods Scanning Electron Microscopy and Electron Dispersive Spectroscopy (EDS) using a JEOL JSM 5410 microscope equipped with EDS were utilized to evaluate the samples before and after prolonged immersion. Results We found that lead and other constituents of PLZT leached into the surrounding aqueous medium. Discussion By comparing the unit cell of PLZT with that of CaTiO3, which has been found to react with aqueous fluids, Lead is in the same site in PLZT as Ca is in CaTiO3. It is thus reasonable that PLZT will react with aqueous solutions. Conclusion The results suggest that PLZT must either be coated with a protective layer or is not appropriate for long-term in vivo or in vitro biological applications. PMID:22697294

Elucidation of structural, vibrational and dielectric properties of transition metal (Co2+) doped spinel Mg-Zn chromites

NASA Astrophysics Data System (ADS)

Choudhary, Pankaj; Varshney, Dinesh

2018-05-01

Co2+ doped Mg-Zn spinel chromite compositions Mg0.5Zn0.5-xCoxCr2O4 (0.0 ≤ x ≤ 0.5) have been synthesized by the high-temperature solid state method. Synchrotron and X-ray diffraction (XRD) studies show single-phase crystalline nature. The structural analysis is validated by Rietveld refinement confirms the cubic structure with space group Fd3m. Crystallite size is estimated from Synchrotron XRD which was found to be 30-34 nm. Energy dispersive analysis confirms stoichiometric Mg0.5Zn0.5-xCoxCr2O4 composition. Average crystallite size distribution is estimated from imaging software (Image - J) of SEM is in the range of 100-250 nm. Raman spectroscopy reveals four active phonon modes, and a pronounced red shift is due to enhanced Co2+ concentration. Increased Co2+ concentration in Mg-Zn chromites shows a prominent narrowing of band gap from 3.46 to 2.97 eV. The dielectric response is attributed to the interfacial polarization, and the electrical modulus study supports non-Debye type of dielectric relaxation. Ohmic junctions (minimum potential drop) at electrode interface are active at lower levels of doping (x < 0.2) give rise to a low-frequency semicircle as evidenced from the complex impedance analysis. The low dielectric loss and high ac conductivity of Co2+ doped Mg-Zn spinel chromites are suitable for power transformer applications at high frequencies.

Multifunctionality of nanocrystalline lanthanum ferrite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rai, Atma, E-mail: atma@iitp.ac.in; Thakur, Awalendra K.; Centre for Energy and Environment, Indian Institute of Technology Patna 800013 India

2016-05-06

Nanocrystalline lanthanum ferrite has been synthesized by adopting modified Pechini route. No evidence of impurity or secondary phase has been detected up to the detection of error limit of X-ray diffractometer (XRD). Rietveld refinement of X-ray diffraction pattern reveals orthorhombic crystal system with space group Pnma (62).Crystallite size and lattice strain was found to be ∼42.8nm and 0.306% respectively. Optical band gap was found to be 2.109 eV, by UV-Visible diffused reflectance spectrum (DRS). Brunauer-Emmet-Teller (BET) surface area was found to be ∼3.45 m{sup 2}/g. Magnetization-hysteresis (M-H) loop was recorded at room temperature (300K) reveals weak ferromagnetism in Nanocrystalline lanthanummore » ferrite. The weak ferromagnetism in lanthanum ferrite is due to the uncompensated antiferromagnetic spin ordering. Ferroelectric loop hysteresis observed at room temperature at 100Hz depicts the presence of ferroelectric ordering in LaFeO{sub 3}.Simultanious presence of magnetic and ferroelectric ordering at room temperature makes it suitable candidate of Multiferroic family.« less

Application of Sequential Extractions and X-ray Absorption Spectroscopy to Determine the Speciation of Chromium in Northern New Jersey Marsh Soils Developed in Chromite ore Processing Residue (COPR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elzinga, E.; Cirmo, A

2010-01-01

The Cr speciation in marsh soils developed in weathering chromite ore processing residue (COPR) was characterized using sequential extractions and synchrotron microbeam and bulk X-ray absorption spectroscopic (XAS) analyses. The sequential extractions suggested substantial Cr associated with reducible and oxidizable soil components, and significant non-extractable residual Cr. Notable differences in Cr speciation estimates from three extraction schemes underscore the operationally defined nature of Cr speciation provided by these methods. Micro X-ray fluorescence maps and {mu}-XAS data indicated the presence of {micro}m-sized chromite particles scattered throughout the weathered COPR matrix. These particles derive from the original COPR material, and have relativelymore » high resistance towards weathering, and therefore persist even after prolonged leaching. Bulk XAS data further indicated Cr(III) incorporated in Fe(OH){sub 3}, and Cr(III) associated with organic matter. The low Cr contents of the weathered material (200-850 ppm) compared to unweathered COPR (20,000-60,000 ppm) point to substantial Cr leaching during COPR weathering, with partial repartitioning of released Cr into secondary Fe(OH){sub 3} phases and organics. The effects of anoxia on Cr speciation, and the potential of active COPR weathering releasing Cr(VI) deeper in the profile require further study.« less

Barium strontium titanate thin film growth with variation of lanthanum dopant compatibility as sensor prototype in the satellite technology

NASA Astrophysics Data System (ADS)

Mulyadi; Wahyuni, Rika; Hardhienata, Hendradi; Irzaman

2018-05-01

Electrical properties of barium strontium titanate thin films were investigated. Three layers of barium strontium titanate thin films have been prepared by chemical solution deposition method and spin coating technique at 8000 rpm rotational speed for 30 seconds and temperature of annealing at 850°C for eight hours with temperature increment of 1.67°C/minute. Materials produced by the process of lanthanum dopant with doping variations of 2%, 4% and 6% above type-p silicon (100) substrates. Film obtained was then carried out the characterization using USB 2000 VIS-NIR and tauc plot method. As a result, the barium strontium titanate thin film has the value of band gap energy of 1.58 eV, 1.92 eV and 2.24 eV respectively. The characterization of electrical properties shows that the band gap value of barium strontium titanate thin film with lanthanum dopant was in the range of semiconductor value. Barium strontium titanate thin films with lanthanum dopant are sensitive to temperature changes, so it potentially to be applied to temperature monitoring on satellite technology.

A MIXED CHEMICAL REDUCTANT FOR TREATING HEXAVALENT CHROMIUM IN A CHROMITE ORE PROCESSING SOLID WASTE

EPA Science Inventory

We evaluated a method for delivering ferrous iron into the subsurface to enhance chemical reduction of Cr(VI) in a chromite ore processing solid waste (COPSW). The COPSW is characterized by high pH (8.5 -11.5), high Cr(VI) concentrations in the solid phase (up to 550 mg kg-1) and...

Dielectric properties and activation behavior of gadolinium doped nanocrystalline yttrium chromite

NASA Astrophysics Data System (ADS)

Sinha, R.; Basu, S.; Meikap, A. K.

2018-04-01

Gadolinium doped Yttrium Chromite nanoparticles are synthesized following sol-gel method. The formation of the nanoparticles are confirmed by XRD and TEM measurements. Dielectric permittivity and dielectric loss are estimated within the temperature range 298K to 523K and in the frequency range 20 Hz to 1 MHz. Dielectric permittivity follows the power law ɛ'(f) ∝ Tm. It is observed that the temperature exponent m increases with the decreasing frequency. The temperature variation of resistivity shows that the samples have semiconducting behavior. The activation energy is also measured.

Catalytic properties of new anode materials for solid oxide fuel cells operated under methane at intermediary temperature

NASA Astrophysics Data System (ADS)

Sauvet, A.-L.; Fouletier, J.

The recent trend in solid oxide fuel cell concerns the use of natural gas as fuel. Steam reforming of methane is a well-established process for producing hydrogen directly at the anode side. In order to develop new anode materials, the catalytic activities of several oxides for the steam reforming of methane were characterized by gas chromatography. We studied the catalytic activity as a function of steam/carbon ratios r. The methane and the steam content were varied between 5 and 30% and between 1.5 and 3.5%, respectively, corresponding to r-values between 0.07 and 0.7. Catalyst (ruthenium and vanadium)-doped lanthanum chromites substituted with strontium, gadolinium-doped ceria (Ce 0.9Gd 0.1O 2) referred as to CeGdO 2, praseodymium oxide, molybdenum oxide and copper oxide were tested. The working temperature was fixed at 850°C, except for 5% ruthenium-doped La 1- xSr xCrO 3 where the temperature was varied between 700 and 850°C. Two types of behavior were observed as a function of the activity of the catalyst. The higher steam reforming efficiency was observed with 5% of ruthenium above 750°C.

Enhancing the stability of copper chromite catalysts for the selective hydrogenation of furfural with ALD overcoating (II) – Comparison between TiO2 and Al2O3 overcoatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Hongbo; Canlas, Christian; Kropf, A. Jeremy

2015-01-01

TiO2 atomic layer deposition (ALD) overcoatings were applied to copper chromite catalysts to increase the stability for 2-furfuraldehyde (“furfural”) hydrogenation. After overcoating, about 75% activity was preserved compared to neat copper chromite: much higher activity than an alumina ALD overcoated catalyst with a similar number of ALD cycles. The effects of ALD TiO2 on the active Cu nanoparticles were studied extensively using both in-situ TPR/isothermal-oxidation and in-situ furfural hydrogenation via Cu XAFS. The redox properties of Cu were modified only slightly by the TiO2 ALD overcoat. However, a subtle electronic interaction was observed between the TiO2 ALD layers and themore » Cu nanoparticles. With calcination at 500 °C the interaction between the TiO2 overcoat and the underlying catalyst is strong enough to inhibit migration and site blocking by chromite, but is sufficiently weaker than the interaction between the Al2O3 overcoat and copper chromite that it does not strongly inhibit the catalytic activity of the copper nanoparticles.« less

Formulation and Assessment of a Wash-Primer Containing Lanthanum "Tannate" for Steel Temporary Protection

NASA Astrophysics Data System (ADS)

D'Alessandro, Oriana; Selmi, Gonzalo J.; Deyá, Cecilia; Di Sarli, Alejandro; Romagnoli, Roberto

2018-02-01

Tannins are polyphenols synthesized by plants and useful for the coating industry as corrosion inhibitors. In addition, lanthanum salts have a great inhibitory effect on steel corrosion. The aim of this study was to obtain lanthanum "tannate" with adequate solubility to be incorporated as the corrosion inhibitor in a wash-primer. The "tannate" was obtained from commercial "Quebracho" tannin and 0.1 M La(NO3)3. The soluble tannin was determined by the Folin-Denis reagent, while the concentration of Lanthanum was obtained by a gravimetric procedure. The protective action of "tannate" on SAE 1010 steel was evaluated by linear polarization curves and corrosion potential measurements. Lanthanum "tannate" was incorporated in a wash-primer formulation and tested by corrosion potential and ionic resistance measurements. The corrosion rate was also determined by the polarization resistance technique. Besides, the primer was incorporated in an alkyd paint system and its anticorrosion performance assessed in the salt spray cabinet and by electrochemical impedance spectroscopy. Results showed that lanthanum "tannate" primer inhibits the development of deleterious iron oxyhydroxides on the steel substrate and incorporated into a paint system had a similar behavior to the primer formulated with zinc tetroxychromate.

Effect of crystal size distribution on thermoelectric performance for Lanthanum-doped strontium titanate bulk material

NASA Astrophysics Data System (ADS)

Zhang, Boyu; Wang, Jun; Yaer, Xinba; Huo, Zhenzhen; Wu, Yin; Li, Yan; Miao, Lei; Liu, Chengyan; Zou, Tao; Ma, Wen

2015-07-01

Effect of crystal size distribution on thermoelectric performance of Lanthanum-doped strontium titanate (La-SrTiO3) ceramics are investigated in this study. Thermoelectric performance measurement, coupled with microstructure studies, shows that the electrical conductivity strongly depends on the crystal size, potential barrier on the grain boundary and porosity. Meantime, because the average potential barriers height are increased along with the reduction of crystal size, the Seebeck coefficients are increased by energy filtering effect at the large number of grain boundaries. As a result, by controlling of crystal size distribution, ZT value of La-SrTiO3 is improved.

Synthesis and characterization of lanthanum doped zinc oxide nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Vinod; Sonia,; Suman,

La doped ZnO (Zn{sub 1-x}La{sub x}O, x = 0, 3, 6 and 9) were prepared via chemical co-precipitation method using Zinc Acetate, Lanthanum Acetate and Sodium Hydroxide at 50°C. Hydrate nanoparticles were annealed in air at 300°C for 3 hours. The synthesized samples have been characterized by powder X-ray diffraction and UV–Visible spectrophotometer. The XRD measurement revealsthat the prepared nanoparticles have different microstructure without changing a hexagonal wurtzite structure. The result shows the change in nanoparticles size with the increment of lanthanum concentration for lower concentration for x = 0 to 6 and decreases at x = 9.

Performance of planar single cell lanthanum gallate based solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Maffei, N.; Kuriakose, A. K.

A novel synthesis of high purity, single phase strontium-magnesium doped lanthanum gallate through a nitrate route is described. The prepared powder is formed into planar monolithic elements by uniaxial pressing followed by isostatic pressing and sintering. XRD analysis of the sintered elements reveal no detectable secondary phases. The performance of the electrolyte in solid oxide fuel cells (SOFC) with three different anode/cathode combinations tested at 700°C with respect to the J- V and power density is reported. The data show that the characteristics of this SOFC are strongly dependent on the particular anode/cathode system chosen.

Suspension plasma spraying of La0.6Sr0.4Co0.2Fe0.8O3-δ cathodes: Influence of carbon black pore former on performance and degradation

NASA Astrophysics Data System (ADS)

Fan, E. S. C.; Kuhn, J.; Kesler, O.

2016-06-01

Suspension plasma spray deposition is utilized to fabricate solid oxide fuel cell cathodes with minimal material decomposition. Adding carbon black as a pore former to the feedstock suspension results in smoother and more porous coatings, but over the range of carbon black concentrations studied, has little impact on the overall symmetrical cell performance. The cathode made with a suspension containing 25 wt% carbon has the highest deposition efficiency and a polarization resistance of 0.062 Ωcm2 at 744 °C. This cathode is tested for 500 h, and it is observed that adding an SDC interlayer between the YSZ electrolyte and the cathode(s) and/or coating the metal substrate with lanthanum chromite decrease the rate of performance degradation.

Lanthanum tricyanide-catalyzed acyl silane-ketone benzoin additions.

PubMed

Tarr, James C; Johnson, Jeffrey S

2009-09-03

Lanthanum tricyanide efficiently catalyzes a benzoin-type coupling between acyl silanes and ketones. Yields range from moderate to excellent over a broad substrate scope encompassing aryl, alkyl, electron-rich, and sterically hindered ketones.

Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions

PubMed Central

Tarr, James C.; Johnson, Jeffrey S.

2009-01-01

Lanthanum tricyanide efficiently catalyzes a benzoin-type coupling between acyl silanes and ketones. Yields range from moderate to excellent over a broad substrate scope encompassing aryl, alkyl, electron-rich, and sterically hindered ketones. PMID:19655731

Glass-Like Thermal Conductivity of (010)-Textured Lanthanum-Doped Strontium Niobate Synthesized with Wet Chemical Deposition

DOE PAGES

Foley, Brian M.; Brown-Shaklee, Harlan J.; Campion, Michael J.; ...

2014-11-08

We have measured the cross-plane thermal conductivity (κ) of (010)-textured, undoped, and lanthanum-doped strontium niobate (Sr 2-xLa xNb 2O 7-δ) thin films via time-domain thermoreflectance. Then the thin films were deposited on (001)-oriented SrTiO 3 substrates via the highly-scalable technique of chemical solution deposition. We find that both film thickness and lanthanum doping have little effect on κ, suggesting that there is a more dominant phonon scattering mechanism present in the system; namely the weak interlayer-bonding along the b-axis in the Sr 2Nb 2O 7 parent structure. We also compare our experimental results with two variations of the minimum-limit modelmore » for κ and discuss the nature of transport in material systems with weakly-bonded layers. The low cross-plane κ of these scalably-fabricated films is comparable to that of similarly layered niobate structures grown epitaxially.« less

Lanthanum Nitrate As Electrolyte Additive To Stabilize the Surface Morphology of Lithium Anode for Lithium-Sulfur Battery.

PubMed

Liu, Sheng; Li, Guo-Ran; Gao, Xue-Ping

2016-03-01

Lithium-sulfur (Li-S) battery is regarded as one of the most promising candidates beyond conventional lithium ion batteries. However, the instability of the metallic lithium anode during lithium electrochemical dissolution/deposition is still a major barrier for the practical application of Li-S battery. In this work, lanthanum nitrate, as electrolyte additive, is introduced into Li-S battery to stabilize the surface of lithium anode. By introducing lanthanum nitrate into electrolyte, a composite passivation film of lanthanum/lithium sulfides can be formed on metallic lithium anode, which is beneficial to decrease the reducibility of metallic lithium and slow down the electrochemical dissolution/deposition reaction on lithium anode for stabilizing the surface morphology of metallic Li anode in lithium-sulfur battery. Meanwhile, the cycle stability of the fabricated Li-S cell is improved by introducing lanthanum nitrate into electrolyte. Apparently, lanthanum nitrate is an effective additive for the protection of lithium anode and the cycling stability of Li-S battery.

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

NASA Technical Reports Server (NTRS)

Goldsby, Jon C.

2010-01-01

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.

Influence of tellurite on lifetime for samarium doped lanthanum lead borate glass

NASA Astrophysics Data System (ADS)

Madhu, A.; Eraiah, B.

2018-04-01

Samarium substituted tellurium lanthanum lead borate glass is prepared using melt quenching technique. Luminescence spectra have been recorded upon excitation with 402 nm various transitions from 4G5/2 level, for samarium doped tellurite glasses are studied and also lifetime for all the samples exhibit single exponential behaviour of decay curve. Luminescence spectra of present glasses show quenching effect due to cross-relation channels of samarium ions. The lifetime of glass samples decrease as the tellurite concentration is decreased. So, it evidences that to attain longer lifetime for lasing material one can tune the host by selecting concentration of tellurite.

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

DOEpatents

Karp, Joel S [Glenside, PA; Surti, Suleman [Philadelphia, PA

2008-06-03

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.

High-efficiency, low-temperature cesium diodes with lanthanum-hexaboride electrodes

NASA Technical Reports Server (NTRS)

Morris, J. F.

1974-01-01

Lanthanum hexaboride electrodes in 1700 K cesium diodes may triple power outputs compared with those demonstrated for nuclear thermionic space applications. Still greater relative gains seem possible for emitters below 1700 K. Further improvements in cesium diode performance should result from the lower collector temperatures allowed for earth and low power space duties. Decreased temperatures will lessen thermal transport losses that attend thermionic conversion mechanisms. Such advantages will add to those from collector Carnot and electrode effects. If plasma ignition difficulties impede diode temperature reductions, recycling small fractions of the output power could provide ionization. So high efficiency, low temperature cesium diodes with lanthanum hexaboride electrodes appear feasible.

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

DOEpatents

Singh, Prabhakar; Ruka, Roswell J.

1995-01-01

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.

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

DOEpatents

Singh, P.; Ruka, R.J.

1995-02-14

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.

Structural, dielectric and impedance characteristics of lanthanum-modified BiFeO3-PbTiO3 electronic system

NASA Astrophysics Data System (ADS)

Pradhan, S. K.; Das, S. N.; Bhuyan, S.; Behera, C.; Padhee, R.; Choudhary, R. N. P.

2016-06-01

A lanthanum-modified BiFeO3-PbTiO3 binary electronic system has been fabricated by a high-temperature solid-state reaction technique. The structural, dielectric and electrical properties of a single phase of multicomponent system are investigated to understand its ferroelectrics as well as relaxation behavior. The X-ray diffraction structural analysis substantiates the formation of a new stable phase of tetragonal system (with a large c/a ratio 1.23) without any trace of impurity phase. The electrical behavior of the processed material is characterized through impedance spectroscopy in a wide frequency range (1 kHz-1 MHz) over a temperature range of 25-500 °C. It is observed that the substitution of lanthanum-modified PbTiO3 (PT) into BiFeO3 (BFO) reveals enviable multiferroic property which is evident from the ME coefficient measurement and ferroelectric loop. It also reduces the electrical leakage current or tangent loss. The ac conductivity of the solid solution increases with increase in frequency in the low-temperature region. The impedance spectroscopy of the synthesized material reflects the dielectric relaxation of non-Debye type.

Scintillator materials containing lanthanum fluorides

DOEpatents

Moses, William W.

1991-01-01

An improved radiation detector containing a crystalline mixture of LaF.sub.3 and CeF.sub.3 as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF.sub.3 and the remainder CeF.sub.3 have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography.

Scintillator materials containing lanthanum fluorides

DOEpatents

Moses, W.W.

1991-05-14

An improved radiation detector containing a crystalline mixture of LaF[sub 3] and CeF[sub 3] as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF[sub 3] and the remainder CeF[sub 3] have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography. 2 figures.

Room-Temperature Fabricated Thin-Film Transistors Based on Compounds with Lanthanum and Main Family Element Boron.

PubMed

Xiao, Peng; Huang, Junhua; Dong, Ting; Xie, Jianing; Yuan, Jian; Luo, Dongxiang; Liu, Baiquan

2018-06-06

For the first time, compounds with lanthanum from the main family element Boron (LaB x ) were investigated as an active layer for thin-film transistors (TFTs). Detailed studies showed that the room-temperature fabricated LaB x thin film was in the crystalline state with a relatively narrow optical band gap of 2.28 eV. The atom ration of La/B was related to the working pressure during the sputtering process and the atom ration of La/B increased with the increase of the working pressure, which will result in the freer electrons in the LaB x thin film. LaB x -TFT without any intentionally annealing steps exhibited a saturation mobility of 0.44 cm²·V −1 ·s −1 , which is a subthreshold swing ( SS ) of 0.26 V/decade and a I on / I off ratio larger than 10⁴. The room-temperature process is attractive for its compatibility with almost all kinds of flexible substrates and the LaB x semiconductor may be a new choice for the channel materials in TFTs.

New Scintillator Materials (K2CeBr5) and (Cs2CeBr5)

NASA Technical Reports Server (NTRS)

Hawrami, R.; Volz, M. P.; Batra, A. K.; Aggarwal, M. D.; Roy, U. N.; Groza, M.; Burger, A.; Cherepy, Nerine; Niedermayr, Thomas; Payne, Stephen A.

2008-01-01

Cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5) are new scintillator materials for X-ray and gamma ray detector applications. Recently halide scintillator materials, such as Ce doped lanthanum bromide has been proved to be very important material for the same purpose. These materials are highly hygroscopic; a search for high light yield non-hygroscopic materials was highly desirable to advance the scintillator technology. In this paper, we are reporting the crystal growth of novel scintillator materials, cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5). Crystals were successfully grown from the melt using the vertical Bridgman-Stockbarger technique, in a comparison with the high performance LaBr3 or LaCl3 crystals, cerium based alkali halides crystals, (Cs2CeBr5) and (K2CeBr5) have similar scintillation properties, while being much less hygroscopic. Furthermore, cesium based compounds will not suffer from the self-activity present in potassium and lanthanum compounds. However the Cs2CeBr5 crystals did not grow properly probably due to non-congruent melting or to some phase transition during cooling. Keywords." Scintillator materials; Ce3+; Energy resolution; Light yield; K2CeBr5

Environmental status of groundwater affected by chromite ore processing residue (COPR) dumpsites during pre-monsoon and monsoon seasons.

PubMed

Matern, Katrin; Weigand, Harald; Singh, Abhas; Mansfeldt, Tim

2017-02-01

Chromite ore processing residue (COPR) is generated by the roasting of chromite ores for the extraction of chromium. Leaching of carcinogenic hexavalent chromium (Cr(VI)) from COPR dumpsites and contamination of groundwater is a key environmental risk. The objective of the study was to evaluate Cr(VI) contamination in groundwater in the vicinity of three COPR disposal sites in Uttar Pradesh, India, in the pre-monsoon and monsoon seasons. Groundwater samples (n = 57 pre-monsoon, n = 70 monsoon) were taken in 2014 and analyzed for Cr(VI) and relevant hydrochemical parameters. The site-specific ranges of Cr(VI) concentrations in groundwater were <0.005 to 34.8 mg L -1 (Rania), <0.005 to 115 mg L -1 (Chhiwali), and <0.005 to 2.0 mg L -1 (Godhrauli). Maximum levels of Cr(VI) were found close to the COPR dumpsites and significantly exceeded safe drinking water limits (0.05 mg L -1 ). No significant dependence of Cr(VI) concentration on monsoons was observed.

Spectral studies on the interaction between lanthanum ion and the ligand: N,N'-ethylenebis-[2-(o-hydroxyphenolic)glycine].

PubMed

Yaqin, Zhao; Binsheng, Yang

2005-11-01

The interaction between N,N'-ethylenebis-[2-(o-hydroxyphenolic)glycine] (EHPG) and lanthanum was studied by the difference UV spectra and fluorescence spectra. At pH 7.4, 0.01 M N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid (Hepes), with the addition of 1.0 x 10(-3)M lanthanum, two new peaks were observed at 238 nm and 294 nm by absorptivity spectroscopy compared with blank solution EHPG suggesting the interaction of lanthanum and EHPG. At the same time, the reaction could be measured by fluorescence spectra. The fluorescence intensity of EHPG at 310 nm was significantly decreased in the presence of lanthanum. The 1:1 stoichiometric ratio of EHPG to lanthanum was confirmed by both fluorescence and UV titration curves. In addition, the molar absorptivity of La-EHPG at 238 nm is (1.23+/-0.01)x10(4)cm(-1)M(-1). The conditional binding constant was calculated to be log K(La-EHPG)=12.09+/-0.37 on the basis of the result of UV titration curves.

Order parameters in lanthanum gallate lightly doped with manganese and paramagnetic resonance

NASA Astrophysics Data System (ADS)

Vazhenin, V. A.; Potapov, A. P.; Artyomov, M. Yu.; Guseva, V. B.

2010-09-01

The Cr3+ centers have been revealed, transitions at room temperature have been identified, and spin Hamiltonian parameters have been determined for the Cr3+ and Fe3+ triclinic centers in lanthanum gallate lightly doped with manganese. The principal axes of the fourth-rank fine-structure tensor for the Fe3+ triclinic centers have been established and used to determine the order parameters, i.e., the angles of rotation of oxygen octahedra of lanthanum gallate with respect to the perovskite structure. The order parameter in the rhombohedral phase has been estimated.

Origins of chromite and magnetite in sedimentary rocks deposited in a shallow water environment in the 3.2 Ga Moodies Group, South Africa

NASA Astrophysics Data System (ADS)

Otake, T.; Sakamoto, Y.; Itoh, S.; Yurimoto, H.; Kakegawa, T.

2012-12-01

*Otake, T. totake@eng.hokudai.ac.jp Div. of Sustainable Resources Engineering, Hokkaido Univ., Sapporo, Japan Sakamoto, Y. yu.sakamoto12@gmail.com Dep. of Earth Science, Tohoku Univ., Sendai, Japan Itoh, S. sitoh@ep.sci.hokudai.ac.jp Dep. of Natural History Sciences, Hokkaido Univ., Sapporo, Japan Yurimoto. H. yuri@ep.sci.hokudai.ac.jp Dep. of Natural History Sciences, Hokkaido Univ., Sapporo, Japan Kakegawa, T. kakegawa@m.tohoku.ac.jp Dep. of Earth Science, Tohoku Univ., Sendai, Japan Geochemical data from ferruginous chemical sedimentary rocks (e.g., Banded Iron Formation: BIF) have been used to reconstruct the surface environments of early Earth. However, only a few studies have investigated the geochemical characteristics of BIFs deposited in a shallow water environment during the Archean, which may have differed from those deposited in a deep water environment. Therefore, we investigated geological, petrographic and geochemical characteristics of ferruginous rocks deposited in a shallow water environment in the Moodies group, in the Barberton Greenstone Belt, South Africa. We obtained ferruginous rock samples in the Moodies group from both an outcrop and underground gold mine, and compared the characteristics of these samples. The 70 sedimentary rock samples were divided into groups based on the dominant Fe minerals they contain: Hematite-rich jaspilite (HM group), Magnetite-rich iron formation/shale/sandstone (MT group), and Siderite-rich sandstone (SD group). Samples in the HM group are predominantly composed of fine-grained quartz (< 20 μm) and hematite (< 5 μm), which are interpreted to be chemical precipitates. Samples in the MT group contain quartz, magnetite, siderite, ankerite, chlorite, biotite and chromite. The grain size of magnetite is much larger (20-150 μm) than that of hematite in the HM group. The magnetite is interpreted as a secondary mineral transformed from hematite during early diagenesis. Results of in situ oxygen isotope analysis by

Accomplishment of highly porous-lithium lanthanum titanate through microwave treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lakshmi, D.; Nalini, B., E-mail: jyothsnalalin99@gmail.com; Abhilash, K. P.

Perovskite structured (ABO{sub 3}) lithium lanthanum titanate (LLTO) is a successful electrolyte reported by several scientists in the recent past. It is believed that intercalation and de-intercalation of Li ions inside solid electrolyte can be improved by increasing the porosity of the material. Hence in this research work, an attempt is made to increase the porosity of the LLTO electrolyte by rapid-microwave synthesis route. The microwave prepared LLTO is compared with the sol-gel synthesized LLTO. The prepared samples are analyzed with XRD, SEM, PL and cyclic Voltammetry studies. Morphological analysis proves that microwave synthesized LLTO contains much pores compared tomore » the Sol-gel LLTO. A remarkable difference in its electrochemical property is also demonstrated and analysed with cyclic voltammetric studies and the results are presented.« less

Lanthanum Deposition in the Stomach in the Absence of Helicobacter pylori Infection.

PubMed

Iwamuro, Masaya; Urata, Haruo; Tanaka, Takehiro; Kawano, Seiji; Kawahara, Yoshiro; Kimoto, Katsuhiko; Okada, Hiroyuki

2018-03-15

In this case report, we describe two patients who showed a diffusely whitish mucosa in the posterior wall and the lesser curvature of the gastric body. The patients were serologically- and histopathologically-negative for Helicobacter pylori. Random biopsy specimens from the stomach revealed no regenerative changes, intestinal metaplasia, and/or foveolar hyperplasia in either of the patients. Although lanthanum deposition in the gastric mucosa has been reported to occur in close association with H. pylori-associated gastritis, our patients tested negative for H. pylori. These cases suggest that lanthanum deposition presents as whitish lesions in the gastric body in H. pylori-negative patients.

The effect of lanthanum on the fabrication of ZrB{sub 2}-ZrC composites by spark plasma sintering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Kyoung Hun; Shim, Kwang Bo

2003-01-15

The effect of the addition of the rare earth element, lanthanum, on the sintering characteristics of ZrB{sub 2}-ZrC composites has been analyzed during a spark plasma sintering (SPS) process. Microscopic observation confirmed that lanthanum accelerated mass transport by the formation of the liquid phase between the particles induced by the spark plasma in the initial stage of the SPS process, and then these were recrystallized to form a lanthanum-containing secondary phase at the grain boundaries and at the grain boundary triple junctions. In spite of the strong covalent bonding characteristics of the ZrB{sub 2}-ZrC composite there are many well-developed dislocationmore » structures observed. The fracture toughness of the lanthanum-containing ZrB{sub 2}-ZrC is about 2.56 MPa m{sup 1/2}, which is comparable to that of the pure composite. Therefore, it is concluded that lanthanum is very effective as a sintering aid for the ZrB{sub 2}-ZrC composite without any degradation of the mechanical properties.« less

Development and understanding of La0.85Sr0.15Cr1-xNixO3-δ anodes for La5.6WO11.4-δ-based Proton Conducting Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Solís, Cecilia; Navarrete, Laura; Balaguer, María; Serra, José M.

2014-07-01

Porous electrodes based on the system La0.85Sr0.15Cr1-xNixO3-δ (x = 0.1 and 0.2) have been investigated as anodes for proton conducting solid oxide fuel cells based on the La5.6WO11.4-δ (LWO) electrolyte material. The microstructure of the anodes was optimized by varying both the starting powder morphology and the final anode sintering temperature. Two different electrode thicknesses were studied, i.e. 15 and 30 μm. The importance of the catalytic role of Ni was also studied by using different concentrations of Ni (10% and 20%) in the chromite and by tuning the Ni particle sizes through the control of the reduction temperature. Additionally, a ceramic-ceramic (cer-cer) composite electrode comprising a physical mixture of the optimized chromite and LWO phase was also considered. Finally, a kinetics study and modeling based on Langmuir-Hinshelwood mechanism was carried out in order to quantitatively describe the rate of dissociative adsorption of H2 on the Ni particles spread on the chromite surface.

TREATMENT OF HEXAVALENT CHROMIUM IN CHROMITE ORE PROCESSING SOLID WASTE USING A MIXED REDUCTANT SOLUTION OF FERROUS SULFATE AND SODIUM DITHIONITE

EPA Science Inventory

We developed a method for disseminating ferrous iron in the subsurface to enhance chemical reduction of hexavalent chromium (Cr(VI)) in a chromite ore processing solid waste derived from the production of ferrochrome alloy. The method utilizes ferrous sulfate (FeSO4) in combinati...

Electrochemical preparation of nanostructured lanthanum using lanthanum chloride as a precursor in 1-butyl-3-methylimidazolium dicyanamide ionic liquid.

PubMed

Zhang, Q B; Yang, C; Hua, Y X; Li, Y; Dong, P

2015-02-14

Nanostructured lanthanum was electrochemically prepared on a platinum (Pt) substrate in the room temperature ionic liquid 1-butyl-3-methylimidazolium dicyanamide (BMI-DCA) containing anhydrous LaCl3 at 333 K. The electrochemical reduction behavior of La(iii) was investigated using cyclic voltammetry and chronoamperometry techniques. Cyclic voltammogram revealed that the reduction of La(iii) in BMI-DCA involved an irreversible process controlled by diffusion. Chronoamperometric transient analysis confirmed the diffusion controlled electrodeposition process with the diffusion coefficient of La(iii) species in the range of 10(-10) cm(2) s(-1). The strong complexing capability of DCA(-) anions facilitated the displacement of chloride ligands and induced the solubility of LaCl3. The subsequent coordination of La(iii) and DCA(-) anions forming [La(DCA)4](-) complex anions was monitored by designing amperometric titration experiments. Potentiostatically deposited La-deposits with different nanostructures were characterized by SEM, XRD and XPS analyses. The electrodeposition potential was found to play an important role in controlling the nucleation and growth kinetics of the nanocrystal during the electrodeposition process. Depending on the deposition potential, metallic lanthanum with either nanoparticles or nanoporous structures was obtained.

Fabrication of solid oxide fuel cell by electrochemical vapor deposition

DOEpatents

Riley, B.; Szreders, B.E.

1988-04-26

In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (/approximately/1100/degree/ /minus/ 1300/degree/C) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20--50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

Fabrication of solid oxide fuel cell by electrochemical vapor deposition

DOEpatents

Brian, Riley; Szreders, Bernard E.

1989-01-01

In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (approximately 1100.degree.-1300.degree. C.) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20-50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

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

NASA Technical Reports Server (NTRS)

Goldsby, Jon C.

2003-01-01

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.

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

PubMed Central

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

2016-01-01

Water pollution caused by the highly toxic metal hexavalent chromium (Cr(VI)) creates significant human health and ecological risks. In this study, a novel adsorbent was used to treat Cr(VI)-containing wastewater; the adsorbent was prepared using red mud (RM) generated from the alumina production industry and the rare earth element lanthanum. This study explored adsorption performance, kinetics, and mechanisms. Results showed that the adsorption kinetics of the RM modified by lanthanum (La-RM), followed the pseudo-second-order model, with a rapid adsorption rate. Cr(VI) adsorption was positively associated with the absorbent dose, pH, temperature, and initial Cr(VI) concentration; coexisting anions had little impact. The maximum Cr(VI) adsorption capacity was 17.35 mg/g. Cr(VI) adsorption on La-RM was a mono-layer adsorption pattern, following the Langmuir isotherm model. Thermodynamic parameters showed the adsorption was spontaneous and endothermic. The adsorption of Cr(VI) on La-RM occurred as a result of LaOCl formation on the RM surface, which in turn further reacted with Cr(VI) in the wastewater. This study highlighted a method for converting industrial waste into a valuable material for wastewater treatment. The novel absorbent could be used as a potential adsorbent for treating Cr(VI)-contaminating wastewater, due to its cost-effectiveness and high adsorption capability. PMID:27658113

Antioxidant protection mechanism of chick hepatic mitochondria exposed to lanthanum chloride & neodymium chloride treatment.

PubMed

Ghosh, N; Chattopadhyay, D; Chatterjee, G C

1991-05-01

Acute lanthanum chloride (250 mg/kg body wt) and neodymium chloride (200 mg/kg body wt) administrations resulted in significant enhancement of glutathione level in chick hepatic mitochondria. However, glutathione-s-transferase activity was depressed. There was no alteration in the activity of glutathione reductase. Activity of glucose-6-phosphate dehydrogenase was not altered under lanthanum and neodymium treatment. There was a significant enhancement of intramitochondrial glutathione peroxidase and superoxide dismutase. Lipid peroxidation remains the same as control group of animals.

Production of Chromium Oxide from Turkish Chromite Concentrate Using Ethanol

NASA Astrophysics Data System (ADS)

Aktas, S.; Eyuboglu, C.; Morcali, M. H.; Özbey, S.; Sucuoglu, Y.

2015-05-01

In this study, the possibility of chromium extraction from Turkish chromite concentrate and the production of chromium oxide were investigated. For the conversion of chromium(III) into chromium(VI), NaOH was employed, as well as air with a rate of 20 L/min. The effects of the base amount, fusing temperature, and fusing time on the chromium conversion percentage were investigated in detail. The conversion kinetics of chromium(III) to chromium(VI) was also undertaken. Following the steps of dissolving the sodium chromate in water and filtering, aluminum hydroxide was precipitated by adjusting the pH level of the solution. The chromium(VI) solution was subsequently converted to Cr(III) by the combination of sulfuric acid and ethanol. Interestingly, it was observed that ethanol precipitated chromium as chromium(VI) at mildly acidic pH levels, although this effect is more pronounced for K2Cr2O7 than Na2Cr2O7. On the other hand, in the strongly acidic regime, ethanol acted as a reducing agent role in that chromium(VI) was converted into Cr(III) whereas ethanol itself was oxidized to carbon dioxide and water. Subsequently, chromium hydroxide was obtained by the help of sodium hydroxide and converted to chromium oxide by heating at 800 °C, as indicated in thermo gravimetric analysis (TGA).

Chemical and mineralogical characterization of chromite ore processing residue from two recent Indian disposal sites.

PubMed

Matern, Katrin; Kletti, Holger; Mansfeldt, Tim

2016-07-01

Chromite ore processing residue (COPR) is a hazardous waste. Nevertheless, deposition of COPR in uncontrolled surface landfills is still common practice in some countries. Whereas old (between at least 40 and 180 years) COPR from the temperate zone has been intensively investigated, information on COPR in other regions is restricted. Relatively young (<25 years) COPR samples obtained from two abandoned landfill sites in India were investigated by a modified total microwave digestion method, X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM) in order to determine their chemical and mineralogical nature. By the use of microwave digestion with acid mixtures of HNO3, H3PO4, and HBF4 (5:3:2 vol), COPR was completely dissolved and element contents similar to those obtained by X-ray fluorescence were found. Total Cr contents of the two COPR accounted for 81 and 74 g kg(-1), of which 20 and 13% were present in the carcinogenic hexavalent form (CrVI). Apart from the common major mineral phases present in COPR reported earlier, a further Cr host mineral, grimaldiite [CrO(OH)], could be identified by XRPD and SEM. Additionally, well soluble Na2CrO4 was present. Improving the effectiveness of chromite ore processing and preventing the migration of Cr(VI) into water bodies are the main challenges when dealing with these COPR. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and Stability of Lanthanum Superhydrides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geballe, Zachary M.; Liu, Hanyu; Mishra, Ajay K.

Recent theoretical calculations predict that megabar pressure stabilizes very hydrogen-rich simple compounds having new clathrate-like structures and remarkable electronic properties including room-temperature superconductivity. X-ray diffraction and optical studies demonstrate that superhydrides of lanthanum can be synthesized with La atoms in an fcc lattice at 170 GPa upon heating to about 1000 K. The results match the predicted cubic metallic phase of LaH10 having cages of thirty-two hydrogen atoms surrounding each La atom. Upon decompression, the fcc-based structure undergoes a rhombohedral distortion of the La sublattice. The superhydride phases consist of an atomic hydrogen sublattice with H-H distances of about 1.1more » Å, which are close to predictions for solid atomic metallic hydrogen at these pressures. With stability below 200 GPa, the superhydride is thus the closest analogue to solid atomic metallic hydrogen yet to be synthesized and characterized.« less

Eucalyptus tolerance mechanisms to lanthanum and cerium: subcellular distribution, antioxidant system and thiol pools.

PubMed

Shen, Yichang; Zhang, Shirong; Li, Sen; Xu, Xiaoxun; Jia, Yongxia; Gong, Guoshu

2014-12-01

Guanglin 9 (Eucalyptus grandis × Eucalyptus urophlla) and Eucalyptus grandis 5 are two eucalyptus species which have been found to grow normally in soils contaminated with lanthanum and cerium, but the tolerance mechanisms are not clear yet. In this study, a pot experiment was conducted to investigate the tolerance mechanisms of the eucalyptus to lanthanum and cerium. Cell walls stored 45.40-63.44% of the metals under lanthanum or cerium stress. Peroxidase and catalase activities enhanced with increasing soil La or Ce concentrations up to 200 mg kg(-1), while there were no obvious changes in glutathione and ascorbate concentrations. Non-protein thiols concentrations increased with increasing treatment levels up to 200 mg kg(-1), and then decreased. Phytochelatins concentrations continued to increase under La or Ce stress. Therefore, the two eucalyptus species are La and Ce tolerant plants, and the tolerance mechanisms include cell wall deposition, antioxidant system response, and thiol compound synthesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Assessment of ferrous chloride and Portland cement for the remediation of chromite ore processing residue.

PubMed

Jagupilla, Santhi C; Wazne, Mahmoud; Moon, Deok Hyun

2015-10-01

Chromite Ore Processing Residue (COPR) is an industrial waste containing up to 7% chromium (Cr) including up to 5% hexavalent chromium [Cr(VI)]. The remediation of COPR has been challenging due to the slow release of Cr(VI) from a clinker like material and thereby the incomplete detoxification of Cr(VI) by chemical reagents. The use of sulfur based reagents such as ferrous sulfate and calcium polysulfide to detoxify Cr(VI) has exasperated the swell potential of COPR upon treatment. This study investigated the use of ferrous chloride alone and in combination with Portland cement to address the detoxification of Cr(VI) in COPR and the potential swell of COPR. Chromium regulatory tests, X-ray powder diffraction (XRPD) analyses and X-ray absorption near edge structure (XANES) analyses were used to assess the treatment results. The treatment results indicated that Cr(VI) concentrations for the acid pretreated micronized COPR as measured by XANES analyses were below the New Jersey Department of Environmental Protection (NJDEP) standard of 20 mg kg(-1). The Toxicity characteristic leaching procedure (TCLP) Cr concentrations for all acid pretreated samples also were reduced below the TCLP regulatory limit of 5 mg L(-1). Moreover, the TCLP Cr concentration for the acid pretreated COPR with particle size ⩽0.010 mm were less than the universal treatment standard (UTS) of 0.6 mg L(-1). The treatment appears to have destabilized all COPR potential swell causing minerals. The unconfined compressive strength (UCS) for the treated samples increased significantly upon treatment with Portland cement. Copyright © 2015 Elsevier Ltd. All rights reserved.

Phonons and superconductivity in fcc and dhcp lanthanum

NASA Astrophysics Data System (ADS)

Baǧcı, S.; Tütüncü, H. M.; Duman, S.; Srivastava, G. P.

2010-04-01

We have investigated the structural and electronic properties of lanthanum in the face-centered-cubic (fcc) and double hexagonal-close-packed (dhcp) phases using a generalized gradient approximation of the density functional theory and the ab initio pseudopotential method. It is found that double hexagonal-close-packed is the more stable phase for lanthanum. Differences in the density of states at the Fermi level between these two phases are pointed out and discussed in detail. Using the calculated lattice constant and electronic band structure for both phases, a linear response approach based on the density functional theory has been applied to study phonon modes, polarization characteristics of phonon modes, and electron-phonon interaction. Our phonon results show a softening behavior of the transverse acoustic branch along the Γ-L direction and the Γ-M direction for face-centered-cubic and double hexagonal-close-packed phases, respectively. Thus, the transverse-phonon linewidth shows a maximum at the zone boundary M(L) for the double hexagonal-close-packed phase (face-centered-cubic phase), where the transverse-phonon branch exhibits a dip. The electron-phonon coupling parameter λ is found to be 0.97 (1.06) for the double hexagonal-close-packed phase (face-centered-cubic phase), and the superconducting critical temperature is estimated to be 4.87 (dhcp) and 5.88 K (fcc), in good agreement with experimental values of around 5.0 (dhcp) and 6.0 K (fcc). A few superconducting parameters for the double hexagonal-close-packed phase have been calculated and compared with available theoretical and experimental results. Furthermore, the calculated superconducting parameters for both phases are compared between each other in detail.

Enhancement of thermal shock resistance of reaction sintered mullite–zirconia composites in the presence of lanthanum oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, P.; Nath, M.; Ghosh, A.

2015-03-15

Mullite–zirconia composites containing 20 wt.% zirconia were prepared by reaction sintering of zircon flour, sillimanite beach sand and calcined alumina. 0 to 8 mol% of La{sub 2}O{sub 3} with respect to zirconia was used as sintering aid. The effect of additive on the various physical, microstructures, mechanical and thermo-mechanical properties was studied. Quantitative phase analysis shows the change in tetragonal zirconia content with incorporation of lanthanum oxide. La{sub 2}O{sub 3} addition has significantly improved the thermal shock resistance of the samples. Samples without additive retained only 20% of initial flexural strength after 5 cycles, whereas samples containing 5 mol% La{submore » 2}O{sub 3} retained almost 78% of its initial flexural strength even after 15 thermal shock cycles. - Highlights: • Mullite–zirconia composites were prepared by reaction sintering route utilizing zircon and sillimanite beach sand. • Lanthanum oxide was used as sintering aid. • The presence of lanthanum oxide decreased the densification temperature. • Lanthanum oxide significantly improved the thermal shock resistance of the composites.« less

Study of the Effect on Ionic Conductivity and Structral Morphology of the SR Doped Lanthanum Gallate Solid Electrolyte

NASA Astrophysics Data System (ADS)

Sood, Kapil; Singh, K.; Pandey, O. P.

2013-07-01

In the present study, lanthanum gallate and Sr-doped lanthanum gallate samples were prepared by conventional solid state reaction method. The phase conformation has been performed by using X-ray diffraction (XRD) study. The elemental composition has been confirmed using energy dispersive spectroscopy (EDS) analysis. Ac conductivity of the samples has been measured in the frequency range 0.1-106 Hz and from 50-800 °C. The impedance plots among real and complex impedances at particular temperature have been discussed. The behavior shows the effect of bulk and grain boundary effects of the doped sample. The impedance plots with frequency have been analyzed. The plots have been well fitted to equivalent circuit model. The conductivity shows the Arrhenius type of behavior. The activation energy has been calculated from the plots and represents that the conductivity through the material is mainly ionic. The structural morphology of the samples has been investigated using scanning electron microscope (SEM). The micrograph shows that the porosity and grain size both decreases with Sr-doping.

MATERIAL AND PROCESS DEVELOPMENT LEADING TO ECONOMICAL HIGH-PERFORMANCE THIN-FILM SOLID OXIDE FUEL CELLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jie Guan; Atul Verma; Nguyen Minh

2003-04-01

This document summarizes the technical progress from September 2002 to March 2003 for the program, Material and Process Development Leading to Economical High-Performance Thin-Film Solid Oxide Fuel Cells, contract number DE-AC26-00NT40711. The causes have been identified for the unstable open circuit voltage (OCV) and low performance exhibited by the anode-supported lanthanum gallate based cells from the earlier development. Promising results have been obtained in the area of synthesis of electrolyte and cathode powders, which showed excellent sintering and densification at low temperatures. The fabrication of cells using tapecalendering process for anode-supported thin lanthanum gallate electrolyte cells and their performance optimizationmore » is in progress.« less

Delayed gamma-ray spectroscopy with lanthanum bromide detector for non-destructive assay of nuclear material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Favalli, Andrea; Iliev, Metodi; Ianakiev, Kiril

High-energy delayed γ-ray spectroscopy is a potential technique for directly assaying spent fuel assemblies and achieving the safeguards goal of quantifying nuclear material inventories for spent fuel handling, interim storage, reprocessing facilities, repository sites, and final disposal. Requirements for the γ-ray detection system, up to ~6 MeV, can be summarized as follows: high efficiency at high γ-ray energies, high energy resolution, good linearity between γ-ray energy and output signal amplitude, ability to operate at very high count rates, and ease of use in industrial environments such as nuclear facilities. High Purity Germanium Detectors (HPGe) are the state of the artmore » and provide excellent energy resolution but are limited in their count rate capability. Lanthanum Bromide (LaBr 3) scintillation detectors offer significantly higher count rate capabilities at lower energy resolution. Thus, LaBr 3 detectors may be an effective alternative for nuclear spent-fuel applications, where count-rate capability is a requirement. This paper documents the measured performance of a 2” (length) × 2” (diameter) of LaBr3 scintillation detector system, coupled to a negatively biased PMT and a tapered active high voltage divider, with count-rates up to ~3 Mcps. An experimental methodology was developed that uses the average current from the PMT’s anode and a dual source method to characterize the detector system at specific very high count rate values. Delayed γ-ray spectra were acquired with the LaBr 3 detector system at the Idaho Accelerator Center, Idaho State University, where samples of ~3g of 235U were irradiated with moderated neutrons from a photo-neutron source. Results of the spectroscopy characterization and analysis of the delayed γ-ray spectra acquired indicate the possible use of LaBr3 scintillation detectors when high count rate capability may outweigh the lower energy resolution.« less

Delayed gamma-ray spectroscopy with lanthanum bromide detector for non-destructive assay of nuclear material

DOE PAGES

Favalli, Andrea; Iliev, Metodi; Ianakiev, Kiril; ...

2017-10-09

High-energy delayed γ-ray spectroscopy is a potential technique for directly assaying spent fuel assemblies and achieving the safeguards goal of quantifying nuclear material inventories for spent fuel handling, interim storage, reprocessing facilities, repository sites, and final disposal. Requirements for the γ-ray detection system, up to ~6 MeV, can be summarized as follows: high efficiency at high γ-ray energies, high energy resolution, good linearity between γ-ray energy and output signal amplitude, ability to operate at very high count rates, and ease of use in industrial environments such as nuclear facilities. High Purity Germanium Detectors (HPGe) are the state of the artmore » and provide excellent energy resolution but are limited in their count rate capability. Lanthanum Bromide (LaBr 3) scintillation detectors offer significantly higher count rate capabilities at lower energy resolution. Thus, LaBr 3 detectors may be an effective alternative for nuclear spent-fuel applications, where count-rate capability is a requirement. This paper documents the measured performance of a 2” (length) × 2” (diameter) of LaBr3 scintillation detector system, coupled to a negatively biased PMT and a tapered active high voltage divider, with count-rates up to ~3 Mcps. An experimental methodology was developed that uses the average current from the PMT’s anode and a dual source method to characterize the detector system at specific very high count rate values. Delayed γ-ray spectra were acquired with the LaBr 3 detector system at the Idaho Accelerator Center, Idaho State University, where samples of ~3g of 235U were irradiated with moderated neutrons from a photo-neutron source. Results of the spectroscopy characterization and analysis of the delayed γ-ray spectra acquired indicate the possible use of LaBr3 scintillation detectors when high count rate capability may outweigh the lower energy resolution.« less

Delayed gamma-ray spectroscopy with lanthanum bromide detector for non-destructive assay of nuclear material

NASA Astrophysics Data System (ADS)

Favalli, Andrea; Iliev, Metodi; Ianakiev, Kiril; Hunt, Alan W.; Ludewigt, Bernhard

2018-01-01

High-energy delayed γ-ray spectroscopy is a potential technique for directly assaying spent fuel assemblies and achieving the safeguards goal of quantifying nuclear material inventories for spent fuel handling, interim storage, reprocessing facilities, repository sites, and final disposal. Requirements for the γ-ray detection system, up to ∼6 MeV, can be summarized as follows: high efficiency at high γ-ray energies, high energy resolution, good linearity between γ-ray energy and output signal amplitude, ability to operate at very high count rates, and ease of use in industrial environments such as nuclear facilities. High Purity Germanium Detectors (HPGe) are the state of the art and provide excellent energy resolution but are limited in their count rate capability. Lanthanum Bromide (LaBr3) scintillation detectors offer significantly higher count rate capabilities at lower energy resolution. Thus, LaBr3 detectors may be an effective alternative for nuclear spent-fuel applications, where count-rate capability is a requirement. This paper documents the measured performance of a 2" (length) × 2" (diameter) of LaBr3 scintillation detector system, coupled to a negatively biased PMT and a tapered active high voltage divider, with count-rates up to ∼3 Mcps. An experimental methodology was developed that uses the average current from the PMT's anode and a dual source method to characterize the detector system at specific very high count rate values. Delayed γ-ray spectra were acquired with the LaBr3 detector system at the Idaho Accelerator Center, Idaho State University, where samples of ∼3g of 235U were irradiated with moderated neutrons from a photo-neutron source. Results of the spectroscopy characterization and analysis of the delayed γ-ray spectra acquired indicate the possible use of LaBr3 scintillation detectors when high count rate capability may outweigh the lower energy resolution.

Method for producing dense lithium lanthanum tantalate lithium-ion conducting ceramics

DOEpatents

Brown-Shaklee, Harlan James; Ihlefeld, Jon; Spoerke, Erik David; Blea-Kirby, Mia Angelica

2018-05-08

A method to produce high density, uniform lithium lanthanum tantalate lithium-ion conducting ceramics uses small particles that are sintered in a pressureless crucible that limits loss of Li₂O.

Direct observation of local magnetic properties in strain engineered lanthanum cobaltate thin films

NASA Astrophysics Data System (ADS)

Park, S.; Wu, Weida; Freeland, J. W.; Ma, J. X.; Shi, J.

2009-03-01

Strain engineered thin film devices with emergent properties have significant impacts on both technical application and material science. We studied strain-induced modification of magnetic properties (Co spin state) in epitaxially grown lanthanum cobaltate (LaCoO3) thin films with a variable temperature magnetic force microscopy (VT-MFM). The real space observation confirms long range magnetic ordering on a tensile-strained film and non-magnetic low-spin configuration on a low-strained film at low temperature. Detailed study of local magnetic properties of these films under various external magnetic fields will be discussed. Our results also demonstrate that VT-MFM is a very sensitive tool to detect the nanoscale strain induced magnetic defects.

The rare earth element (REE) lanthanum (La) induces hormesis in plants.

PubMed

Agathokleous, Evgenios; Kitao, Mitsutoshi; Calabrese, Edward J

2018-07-01

Lanthanum is a rare earth element (REE) which has been extensively studied due to its wide application in numerous fields with a potential accumulation in the environment. It has long been known for its potential to stimulate plant growth within a hormetic-biphasic dose response framework. This article provides evidence from a series of high resolution studies published within the last two decades demonstrating a substantial and significant occurrence of lanthanum-induced hormesis in plants. These findings suggest that hormetic responses should be built into the study design of hazard assessment study protocols and included in the risk assessment process. Hormesis also offers the opportunity to substantially improve cost benefit estimates for environmental contaminants, which have the potential to induce beneficial/desirable effects at low doses. Copyright © 2018 Elsevier Ltd. All rights reserved.

Optogalvanic spectroscopy of lanthanum hyperfine structure

NASA Astrophysics Data System (ADS)

Nelson, Amanda; Hankes, Jessie; Banner, Patrick; Olmschenk, Steven

2017-04-01

Optogalvanic spectroscopy is a sensitive technique to measure optical transitions of atoms and ions produced in a high voltage discharge. Advantages of this technique include a comparatively simple optical setup and the ability to interrogate excited state transitions. Here, we use optogalavanic spectroscopy in a hollow cathode lamp to measure the hyperfine spectrum of several transitions in lanthanum. Hyperfine coefficients are determined for the corresponding energy levels and compared to available previous measurements. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

Amorphous lithium lanthanum titanate for solid-state microbatteries

DOE PAGES

Lee, Jungwoo Z.; Wang, Ziying; Xin, Huolin L.; ...

2016-12-16

Lithium lanthanum titanate (LLTO) is a promising solid state electrolyte for solid state batteries due to its demonstrated high bulk ionic conductivity. However, crystalline LLTO has a relatively low grain boundary conductivity, limiting the overall material conductivity. In this work, we investigate amorphous LLTO (a-LLTO) thin films grown by pulsed laser deposition (PLD). By controlling the background pressure and temperature we are able to optimize the ionic conductivity to 3 × 10 –4 S/cm and electronic conductivity to 5 × 10 –11 S/cm. XRD, TEM, and STEM/EELS analysis confirm that the films are amorphous and indicate that oxygen background gasmore » is necessary during the PLD process to decrease the oxygen vacancy concentration, decreasing the electrical conductivity. Amorphous LLTO is deposited onto high voltage LiNi 0.5Mn 1.5O 4 (LNMO) spinel cathode thin films and cycled up to 4.8 V vs. Li showing excellent capacity retention. Finally, these results demonstrate that a-LLTO has the potential to be integrated into high voltage thin film batteries.« less

Preferable adsorption of phosphate using lanthanum-incorporated porous zeolite: Characteristics and mechanism

NASA Astrophysics Data System (ADS)

He, Yinhai; Lin, Hai; Dong, Yingbo; Wang, Liang

2017-12-01

The adsorbent, where lanthanum oxide was incorporated onto porous zeolite (La-Z), of preferable adsorption towards phosphate was prepared by hydrothermal synthesis. Based on pH effect results, La-Z would effectively sequestrate phosphate over wider pH range of 3.0-7.0, alkaline conditions were unfavorable for phosphate. The adsorption of phosphate was not significantly influenced by ionic strength and by coexisting anions of chloride, nitrate and sulfate but bicarbonate showed slightly greater negative effects, indicating La-Z possessed highly selectivity to phosphate. Adsorption of phosphate could be well fitted by pseudo-second-order model and the process was mainly controlled by intra-particle diffusion. Equilibrium adsorption demonstrated that Langmuir model was more suitable than Freundlich model for description phosphate adsorption and the adsorption capacity was 17.2 mg P g-1, which exhibited 95% utilization of incorporated La. Over 95% phosphate was eliminated in real effluent treatment when the dose was 2 g L-1. The underlying mechanism for phosphate capture was probed with Zeta potential and X-ray photoelectron spectroscope analysis, and the formation of La-P inner-sphere complexation was testified to be the dominant pathway. All the results suggested that the porous zeolite-supported lanthanum oxide can serve as a promising adsorbent for phosphate removal in realistic application.

Comprehensive Study of Lanthanum Aluminate High-Dielectric-Constant Gate Oxides for AdvancedCMOS Devices

PubMed Central

Suzuki, Masamichi

2012-01-01

A comprehensive study of the electrical and physical characteristics of Lanthanum Aluminate (LaAlO3) high-dielectric-constant gate oxides for advanced CMOS devices was performed. The most distinctive feature of LaAlO3 as compared with Hf-based high-k materials is the thermal stability at the interface with Si, which suppresses the formation of a low-permittivity Si oxide interfacial layer. Careful selection of the film deposition conditions has enabled successful deposition of an LaAlO3 gate dielectric film with an equivalent oxide thickness (EOT) of 0.31 nm. Direct contact with Si has been revealed to cause significant tensile strain to the Si in the interface region. The high stability of the effective work function with respect to the annealing conditions has been demonstrated through comparison with Hf-based dielectrics. It has also been shown that the effective work function can be tuned over a wide range by controlling the La/(La + Al) atomic ratio. In addition, gate-first n-MOSFETs with ultrathin EOT that use sulfur-implanted Schottky source/drain technology have been fabricated using a low-temperature process. PMID:28817057

Ceramic component for electrodes

DOEpatents

Marchant, David D.; Bates, J. Lambert

1980-01-01

A ceramic component suitable for preparing MHD generator electrodes having the compositional formula: Y.sub.x (Mg.sub.y Cr.sub.z).sub.w Al.sub.(1-w) O.sub.3 where x=0.9 to 1.05, y=0.02 to 0.2, z=0.8 to 1.05 and w=1.0 to 0.5. The component is resistant to the formation of hydration products in an MHD environment, has good electrical conductivity and exhibits a lower electrochemical corrosion rate than do comparable compositions of lanthanum chromite.

Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

NASA Astrophysics Data System (ADS)

Fan, E. S. C.; Kesler, O.

2015-08-01

Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

The special features of the crystal structure and properties of oxides with mixed conductivity based on lanthanum gallate

NASA Astrophysics Data System (ADS)

Politova, E. D.; Ivanov, S. A.; Kaleva, G. M.; Mosunov, A. V.; Rusakov, V. S.

2008-10-01

The paper presents a review of works on the synthesis, structural composition effects, phase transitions, and electrical conductivity properties of multicomponent solid solutions based on heterosubstituted lanthanum gallate (La,A)(Ga,M)O3 - y . High-temperature phase transitions and structural and charge ordering effects were studied. The presence of iron cations in different valence states was proved; the relative contents of these cations depended on the x parameter and nonstoichiometry parameter y of the base composition. For M = Fe, antiferromagnetic ordering was observed; its temperature interval was determined by the concentration of iron cations in the high-spin state. The total conductivity was found to increase as the concentration of transition metal cations grew because of an increase in the electronic conductivity component. The data on structural parameters and dc and ac conductivity substantiated the conclusion that the highest ionic conductivity and permeability to oxygen were characteristic of iron-containing oxides. The results obtained are evidence that crystal chemical factors play a determining role in the formation of the ion-conducting properties of anion-deficient perovskite-like oxides.

Comparison of dietary phosphate absorption after single doses of lanthanum carbonate and sevelamer carbonate in healthy volunteers: a balance study.

PubMed

Martin, Patrick; Wang, Phillip; Robinson, Antoine; Poole, Lynne; Dragone, Jeffrey; Smyth, Michael; Pratt, Raymond

2011-05-01

Lanthanum carbonate and sevelamer carbonate are noncalcium phosphate binders used to treat hyperphosphatemia in patients with chronic kidney disease. This is the first study to compare phosphate absorption from a standardized meal ingested with a typical clinical dose of these binders. Randomized open-label crossover study. Healthy volunteers were confined to a clinical research center during 4 study periods. Of 31 volunteers randomly assigned, 19 completed all treatments and 18 were analyzed in the pharmacodynamic set (1 was excluded because of vomiting). Participants were assigned in random order to meal alone, meal plus lanthanum carbonate (1 tablet containing 1,000 mg of elemental lanthanum), and meal plus sevelamer carbonate (three 800-mg tablets). The gastrointestinal tract was cleared, the meal was ingested (± treatment), and rectal effluent was collected. In a fourth period, volunteers repeated the study procedures while fasting. The primary end point, net phosphate absorption, was analyzed using a mixed-effect linear model. Phosphorus content of effluent and duplicate meal samples were measured using inductively coupled plasma-optical emission spectroscopy. The standard meal contained ∼375 mg of phosphate, 75% of which was absorbed (net absorption, 281.7 ± 14.1 mg [adjusted mean ± standard error]). Lanthanum carbonate decreased net phosphate absorption by 45% (net absorption, 156.0 ± 14.2 mg) compared with 21% (net absorption, 221.8 ± 14.1 mg) for sevelamer carbonate (P < 0.001). Lanthanum carbonate bound 135.1 ± 12.3 mg of phosphate, whereas sevelamer carbonate bound 63.2 ± 12.3 mg, a 71.9-mg difference (95% CI, 40.0-103.8; P < 0.001). Per tablet, this equates to 135 mg of phosphate bound with lanthanum carbonate versus 21 mg with sevelamer carbonate. A single-dose study. In healthy volunteers, 1,000 mg of lanthanum carbonate decreased phosphate absorption by 45% compared with a 21% decrease with 2,400 mg of sevelamer carbonate. Copyright © 2011

Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

DOEpatents

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

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

Magnetoresistance measurements in Ferro -- Antiferromagnetic bilayers based on the Ca-doped lanthanum manganite system

NASA Astrophysics Data System (ADS)

Gomez, M. E.; Marin, L.; Ramirez, G.; Prieto, P.

2011-03-01

We studied the isothermal magnetic field dependence of the resistance behavior in ferromagnetic--antiferromagnetic interface based on the Ca-doped lanthanum manganite system at temperatures below Neel temperature of the antiferromagnetic layer. We studied the influence of the thickness of the AF-layer, tAF , and F-layer, tF , on the ZFC and FC magnetoresistance (MR) in La 2/3 Ca 1/3 Mn O3 (tF) / La 1/3 Ca 2(3 Mn O3 (tAF) bilayers. HFC was 400 Oe and the applied magnetic field, H. We systematically varied the tF and tAF thickness, maintaining constant the total bilayer thickness (d = tF +tAF) . We found that MR has hysteretic behavior as observed in [ La 2/3 Ca 1/3 Mn O3 (tF) / La 1/3 Ca 2(3 Mn O3 (tAF) ]N superlattices, but; MR increases with the increasing field from H=0 to a maximum and then decreases continuously. This behavior also appears for negative fields in both ZFC and FC loops. The position and magnitude of the maximum is not symmetric with respect to the axis H=0. Work supported by CENM-COLCIENCIAS contract RC-0043-(2005).

Glass formation and crystallization in the alumina-silica-lanthanum phosphate system for ceramics composites

NASA Astrophysics Data System (ADS)

Guo, Shuling

The formation, structure, and dynamics of glasses in the alumina-silica-lanthanum phosphate system and their crystallization were investigated as a function of composition. These are of interest because of their potential as precursors for synthesizing ceramic-matrix-composites via co-crystallization of lanthanum monazite and either mullite or alumina into finely mixed microstructures. The glasses were characterized by X-Ray Diffraction (XRD), Raman spectroscopy, Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Electron Energy Loss Spectrometry (EELS). Glass formation from rapidly quenched liquids was easiest and most consistent for compositions containing silica, such as for mullitemonazite compositions, and more difficult for alumina-monazite compositions. For mullite-monazite glasses, the glass transition temperatures increased linearly from 845°C to 906°C with increasing mullite content. An analysis of the glass structure indicated a network consisting of corner-linked aluminate, silicate and phosphate tetrahedra where aluminum played a central role of separating silicon and phosphorous. It was hypothesized that the glass network consisted of domains of aluminum silicate network edged by phosphate tetrahedra. A maximum in the crystallization temperature was attributed to the complexity of the glass network. At relatively mullite-rich compositions, simultaneous and cooperative crystallization of lanthanum phosphate and mullite correlated with the highest crystallization temperatures, and the lowest activation energies of crystallization. This was preceded by amorphous phase segregation in the glass at lower temperatures. An intermediate phase of lanthanum phosphate was discovered with an orthorhombic unit cell. For compositions of high phosphate contents, lanthanum phosphate precipitated first at about 900°C leaving an essentially pure mullite glass

Growth, structural, optical, thermal and dielectric properties of lanthanum chloride—thiourea—L tartaric acid coordinated complex

NASA Astrophysics Data System (ADS)

Slathia, Goldy; Bamzai, K. K.

2017-11-01

Lanthanum chloride—thiourea—l tartaric acid coordinated complex was grown in the form of single crystal by slow evaporation of supersaturated solutions at room temperature. This coordinated complex crystallizes in orthorhombic crystal system having space group P nma. The crystallinity and purity was tested by powder x-ray diffraction. Fourier transform infra red and Raman spectroscopy analysis provide the evidences on structure and mode of coordination. The scanning electron microscopy (SEM) analysis shows the morphology evolution as brought by the increase in composition of lanthanum chloride. The band transitions due to C=O and C=S chromophores remain active in grown complexes and are recorded in the UV-vis optical spectrum. The thermal effects such as dehydration, melting and decomposition were observed by the thermogravimetric and differential thermo analytical (TGA/DTA) analysis. Electrical properties were studied by dielectric analysis in frequency range 100-30 MHz at various temperatures. Increase in values of dielectric constant was observed with change in lanthanum concentration in the coordinated complex.

Sorption of noble gases by solids, with reference to meteorites. II - Chromite and carbon. III - Sulfides, spinels, and other substances; on the origin of planetary gases

NASA Technical Reports Server (NTRS)

Yang, J.; Anders, E.

1982-01-01

The trapping of noble gases by chromite and carbon, two putative carriers of primordial noble gases in meteorites, was studied by synthesizing 19 samples in a Ne-Ar-Kr-Xe atmosphere at 440-720 K. Noble gas contents are found to approximately obey Henry's Law, but only slight correlations are found with composition, surface area, or adsorption temperature. Geometric mean distribution coefficients for bulk samples and HCl residues in 10 cu cm STP/g atm are: Xe 100, Kr 15, Ar 3.5, and Ne 0.62. Elemental fractionation data support the suggestion of Lewis et al. (1977) that chromite and carbon in C2 and C3 chondrites were formed by the reaction: Fe, Cr + 4CO yields (Fe, Cr)3O4 + 4C + carbides. In contrast to meteoritic minerals, the synthetic specimens show no isotopic fractionation of noble gases. In a subsequent study, attention is given to the cases of sulfides and spinels, on the way to consideration of the origin of planetary gases. Sulfides showed three distinctive trends relative to chromite or magnetite. The elemental fractionation pattern of Ar, Kr and Xe in meteorites, terrestrial rocks and planets resembles the adsorption patterns on the carbons, spinels, sulfides, and other solids studied. The high release temperature of meteoritic noble gases may be explained by transformation of the physisorbed or chemisorbed gas. The ready loss of meteoritic heavy gases on surficial oxidation is consistent with adsorption, as is the high abundance.

The combination of lanthanum chloride and the calcimimetic calindol delays the progression of vascular smooth muscle cells calcification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciceri, Paola; Volpi, Elisa; Brenna, Irene

2012-02-24

Highlights: Black-Right-Pointing-Pointer Lanthanum reduces the progression of high phosphate-induced calcium deposition. Black-Right-Pointing-Pointer Calcium receptor agonists and the calcimimetic calindol reduce calcium deposition. Black-Right-Pointing-Pointer Lanthanum and calindol cooperate on reducing calcium deposition. Black-Right-Pointing-Pointer Lanthanum and calindol may interact with the same receptor. -- Abstract: Phosphate (Pi)-binders are commonly used in dialysis patients to control high Pi levels, that associated with vascular calcification (VC). The aim of this study was to investigate the effects of lanthanum chloride (LaCl{sub 3}) on the progression of high Pi-induced VC, in rat vascular smooth muscle cells (VSMCs). Pi-induced Ca deposition was inhibited by LaCl{sub 3}, withmore » a maximal effect at 100 {mu}M (59.0 {+-} 2.5% inhibition). Furthermore, we studied the effects on VC of calcium sensing receptor (CaSR) agonists. Gadolinium chloride, neomycin, spermine, and the calcimimetic calindol significantly inhibited Pi-induced VC (55.9 {+-} 2.2%, 37.3 {+-} 4.7%, 30.2 {+-} 5.7%, and 63.8 {+-} 5.7%, respectively). To investigate the hypothesis that LaCl{sub 3} reduces the progression of VC by interacting with the CaSR, we performed a concentration-response curve of LaCl{sub 3} in presence of a sub-effective concentration of calindol (10 nM). Interestingly, this curve was shifted to the left (IC{sub 50} 9.6 {+-} 2.6 {mu}M), compared to the curve in the presence of LaCl{sub 3} alone (IC{sub 50} 19.0 {+-} 4.8 {mu}M). In conclusion, we demonstrated that lanthanum chloride effectively reduces the progression of high phosphate-induced vascular calcification. In addition, LaCl{sub 3} cooperates with the calcimimetic calindol in decreasing Ca deposition in this in vitro model. These results suggest the potential role of lanthanum in the treatment of VC induced by high Pi.« less

Hearing Threshold, Loss, Noise Levels and Worker's Profiles of an Open Cast Chromite Mines in Odisha, India.

PubMed

Kerketta, Sunamani; Gartia, Rajendra; Bagh, Somanath

2012-10-01

The aims of the study were to describe the noise levels at an open cast chromite mine in Odisha, India, and the hearing threshold of its workers and to associate their hearing loss with their age, work station and length of employment at the mine. We performed a cross-sectional study of the hearing threshold of chromite mine workers. Audiometric data from 500 subjects was collected at the mines' hospital in the Sukinda Valley of Jajpur, Odisha, India. The latest audiometry data available for the period 2002 to 2008 was used in the analysis. Audiometric screening was performed using an audiometer (TRIVENI TAM-25 6025A) in a quiet environment by qualified technicians, audiologists or physicians. Tests were conducted on the subjects after they had completely rested for 16 hours or more after their day shift. A maximum of 262 subjects (52.4%) were employed in the work zone area and a minimum of 2 subjects (0.4%) had less than 5 years working experience. The age of the subjects ranged from 29 to 59 years and their working experience ranged from 4 to 37 years. The subjects' average mean hearing thresholds at 4, 6 and 8 kHz were 21.53 dBA, 23.40 dBA and 21.90 dBA, respectively. The maximum Leq and L90 levels exceeded the prescribed limits for commercial, residential and silence zones. The maximum Leq levels exceeded 95 dBA for large and medium heavy earth moving machineries (HEMMs), both outside and at the operator's position. Hearing loss due to the subjects' work experience was found to be greater than that attributable to age and workstation. In our study population, the maximum noise levels for large and medium HEMMs and inside the cabins of HEMMs were found to be more than 95 dBA. This indicates that operators in this particular chromite mine at Odisha, India were exposed to noise levels exceeding 95 dBA for more than 10% of the monitoring time. The subjects' hearing loss was also found to increase for every 10-year age interval and that for every 5 years of work

Preparation and electrochemical characterization of ionic-conducting lithium lanthanum titanate oxide/polyacrylonitrile submicron composite fiber-based lithium-ion battery separators

NASA Astrophysics Data System (ADS)

Liang, Yinzheng; Ji, Liwen; Guo, Bingkun; Lin, Zhan; Yao, Yingfang; Li, Ying; Alcoutlabi, Mataz; Qiu, Yiping; Zhang, Xiangwu

Lithium lanthanum titanate oxide (LLTO)/polyacrylonitrile (PAN) submicron composite fiber-based membranes were prepared by electrospinning dispersions of LLTO ceramic particles in PAN solutions. These ionic-conducting LLTO/PAN composite fiber-based membranes can be directly used as lithium-ion battery separators due to their unique porous structure. Ionic conductivities were evaluated after soaking the electrospun LLTO/PAN composite fiber-based membranes in a liquid electrolyte, 1 M lithium hexafluorophosphate (LiPF 6) in ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (1:1 vol). It was found that, among membranes with various LLTO contents, 15 wt.% LLTO/PAN composite fiber-based membranes provided the highest ionic conductivity, 1.95 × 10 -3 S cm -1. Compared with pure PAN fiber membranes, LLTO/PAN composite fiber-based membranes had greater liquid electrolyte uptake, higher electrochemical stability window, and lower interfacial resistance with lithium. In addition, lithium//1 M LiPF 6/EC/EMC//lithium iron phosphate cells containing LLTO/PAN composite fiber-based membranes as the separator exhibited high discharge specific capacity of 162 mAh g -1 and good cycling performance at 0.2 C rate at room temperature.

[Pathways of lanthanum ion transport across the posterior epithelium of the cornea in rabbits].

PubMed

Virnik, V L

1985-11-01

Morphological estimation of the barrier-transport properties of the posterior epithelium in the donor cornea has been performed in the most early time of fanoxic lesions of the cells. Ionized lanthanum, as an effective inhibitor of oxidative phosphorylation and simultaneously--as a marker of transport pathways for particles similar in their size to water molecule, is used in the investigation. The concentration gradient of rare-earth ions is produced by vital injection of lanthanum trichloride into the proper substance (stroma) of the cornea. From the microinjection focus the electron opaque marker is transported through the substrate of the basal substance of the stroma to the posterior epithelium and further along its intercellular and transcellular pathways into the anterior chamber of the eye. The rare-earth ions freely penetrate through the gap and tight junctions. Transcellular transport of lanthanum in the contents of the plasmolemmal microvesicles, vital absorption of the marker on the lateral and luminal parts of the plasmolemma and on the intracellular membranes, lesions of mitochondria and canaliculi of the endoplasmic reticulum of the anoxic character are stated. A suggestion is made on structural preservation of the pathways of convective and dissipative transition of the substance through the posterior epithelium of the cornea during the earliest time of the experimental anoxia.

Reversible Adhesion with Polyelectrolyte Brushes Tailored via the Uptake and Release of Trivalent Lanthanum Ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farina, Robert; Laugel, Nicolas; Yu, Jing

Applications of end-tethered polyelectrolyte “brushes” to modify solid surfaces have been developed and studied for their colloidal stabilization and high lubrication properties. Current efforts have expanded into biological realms and stimuli-responsive materials. Our work explores responsive and reversible aspects of polyelectrolyte brush behavior when polyelectrolyte chains interact with oppositely charged multivalent ions and complexes, which act as counterions. There is a significant void in the polyelectrolyte literature regarding interactions with multivalent species. This paper demonstrates that interactions between solid surfaces bearing negatively charged polyelectrolyte brushes are highly sensitive to the presence of trivalent lanthanum, La3+. Lanthanum cations have unique interactionsmore » with polyelectrolyte chains, in part due to their small size and hydration radius which results in a high local charge density. Using La3+ in conjunction with the surface forces apparatus (SFA), adhesion has been observed to reversibly appear and disappear upon the uptake and release, respectively, of these multivalent cations acting as counterions. In media of fixed ionic strength set by monovalent sodium salt, at I0 = 0.003 M and I0 = 0.3 M, the sign of the interaction forces between overlapping brushes changes from repulsive to attractive when La3+ concentrations reach 0.1 mol % of the total ion concentration. These results are also shown to be generally consistent with, but subtlety different from, previous polyelectrolyte brush experiments using trivalent ruthenium hexamine in the role of the multivalent counterion.« less

Hearing Threshold, Loss, Noise Levels and Worker’s Profiles of an Open Cast Chromite Mines in Odisha, India

PubMed Central

Kerketta, Sunamani; Gartia, Rajendra; Bagh, Somanath

2012-01-01

Objectives: The aims of the study were to describe the noise levels at an open cast chromite mine in Odisha, India, and the hearing threshold of its workers and to associate their hearing loss with their age, work station and length of employment at the mine. Methods: We performed a cross-sectional study of the hearing threshold of chromite mine workers. Audiometric data from 500 subjects was collected at the mines’ hospital in the Sukinda Valley of Jajpur, Odisha, India. The latest audiometry data available for the period 2002 to 2008 was used in the analysis. Audiometric screening was performed using an audiometer (TRIVENI TAM-25 6025A) in a quiet environment by qualified technicians, audiologists or physicians. Tests were conducted on the subjects after they had completely rested for 16 hours or more after their day shift. Results: A maximum of 262 subjects (52.4%) were employed in the work zone area and a minimum of 2 subjects (0.4%) had less than 5 years working experience. The age of the subjects ranged from 29 to 59 years and their working experience ranged from 4 to 37 years. The subjects’ average mean hearing thresholds at 4, 6 and 8 kHz were 21.53 dBA, 23.40 dBA and 21.90 dBA, respectively. The maximum Leq and L90 levels exceeded the prescribed limits for commercial, residential and silence zones. The maximum Leq levels exceeded 95 dBA for large and medium heavy earth moving machineries (HEMMs), both outside and at the operator’s position. Hearing loss due to the subjects’ work experience was found to be greater than that attributable to age and workstation. Conclusion: In our study population, the maximum noise levels for large and medium HEMMs and inside the cabins of HEMMs were found to be more than 95 dBA. This indicates that operators in this particular chromite mine at Odisha, India were exposed to noise levels exceeding 95 dBA for more than 10% of the monitoring time. The subjects’ hearing loss was also found to increase for every 10-year

Lanthanum-silicon-substituted hydroxyapatite: Mechanochemical synthesis and prospects for medical applications

NASA Astrophysics Data System (ADS)

Chaikina, M. V.; Komarova, E. G.; Sharkeev, Yu. P.; Bulina, N. V.; Prosanov, I. Yu.

2016-08-01

The paper presents the results of mechanochemical synthesis of hydroxyapatite (HAP) with simultaneous substitutions of lanthanum (La3+) for calcium ions and silicate ((SiO4)4--group) for the phosphate group with the substituent concentrations in the range 0.2-2.0 mol per HAP mol. The use of Si-substituted HAP as a coating material promotes accelerated osteosynthesis and osteointegration of implants into the bone tissue. The replacement of calcium ions by La3+ in the HAP structure plays an antimicrobial role preventing inflammatory processes. Annealing-induced variations in the lattice parameters of synthesized samples indicate the substituent incorporation into the HAP structure. It is known that complex compounds with lanthanides are used for cancer chemotherapy. In particular, La plays a key role in the course of treatment of injured defects of bone tissue. In addition, La-substituted HAP can be used for filling bone defects and coating implants in postoperational areas affected by bone cancer.

Phase equilibrium and preparation, crystallization and viscous sintering of glass in the alumina-silica-lanthanum phosphate system

NASA Astrophysics Data System (ADS)

He, Feng

The phase equilibrium, viscosity of melt-quenched glasses, and processing of sol-gel glasses of the alumina-silica-lanthanum phosphate system were studied. These investigations were directed towards serving the objective of synthesizing nano-structured ceramic-matrix-composites via controlled crystallization of glass precursors. The thermal stability, phase equilibrium, and liquidus temperatures of the alumina- and mullite-lanthanum phosphate systems are determined. An iridium wire heater was constructed to anneal samples up to 2200°C. Phosphorus evaporation losses were significant at high temperatures, especially over 1800°C. The tentative phase diagrams of the two quasi-binary systems were presented. The viscosity of the melt-quenched mullite-lanthanum phosphate glasses was measured by three different methods, including viscous sintering of glass powder compacts, neck formation between two Frenkel glass beads, and thermal analysis of the glass transition. Improved methodologies were developed for applying the interpretative mathematical models to the results of the sintered powder and thermal analytical experiments. Good agreement was found between all three methods for both absolute values and temperature dependence. A sol-gel process was developed as a low temperature route to producing glasses. A unique, single phase mullite gel capable of low temperature (575°C) mullitization was made from tetraethoxysilane and aluminum isopropoxide at room temperature in three days. Low temperature crystallization was attributed to the avoidance of phase segregation during gel formation and annealing. This was greatly enhanced by a combination of low temperature preheating in the amorphous state, a high heating rate during crystallization and low water content. The Al2O3 content in mullite (61-68 mol%) depended on the highest annealing temperature. Two mullite-lanthanum phosphate gels were made based upon modifying the chemical procedures used for the homogeneous single

Paramagnetic resonance of Mn4+ and Mn2+ centers in lanthanum gallate single crystals

NASA Astrophysics Data System (ADS)

Vazhenin, V. A.; Potapov, A. P.; Guseva, V. B.; Artyomov, M. Yu.

2010-03-01

An increase in the manganese concentration in lanthanum gallate in the range 0.5-5.0% has been found to result in a complete replacement of individual Mn4+ ions by Mn2+ ions. The relative concentrations and binding energies of individual Mn4+, Mn3+, and Mn2+ ions have been determined. The spin Hamiltonians of the Mn2+ and Mn4+ centers in the rhombohedral and orthorhombic phases, respectively, have been constructed and the orientation of the principal axes of the fine-structure tensor of Mn4+ at room temperature has been found. The possibility of using electron paramagnetic resonance for determining the rotation angles of oxygen octahedra of lanthanum gallate with respect to the perovskite structure has been discussed.

Pressure increases, the for­mation of chromite seams, and the development of the ultramafic series in the Stillwater Complex, Montana

USGS Publications Warehouse

Lipin, Bruce R.

1993-01-01

This paper explores the hypothesis that chromite seams in the Stillwater Complex formed in response to periodic increases in total pressure in the chamber. Total pressure increased because of the positive δV of nucleation of CO2 bubbles in the melt and their subsequent rise through the magma chamber, during which the bubbles increased in volume by a factor of 4–6. By analogy with the pressure changes in the summit chambers of Kilauea and Krafla volcanoes, the maximum variation was 0⋅2–0⋅25 kbar, or 5–10% of the total pressure in the Stillwater chamber. An evaluation of the likelihood of fountaining and mixing of a new, primitive liquid that entered the chamber with the somewhat more evolved liquid already in the chamber is based upon calculations using observed and inferred velocities and flow rates of basaltic magmas moving through volcanic fissures. The calculations indicate that hot, dense magma would have oozed, rather than fountained into the chamber, and early mixing of the new and residual magmas that could have resulted in chromite crystallizing alone did not take place.Mixing was an important process in the Stillwater magma chamber, however. After the new magma in the chamber underwent ˜5% fractional crystallization, its composition, temperature, and density approached those of the overlying liquid in the chamber and the liquids then mixed. If this process occurred many times over the course of the development of the Ultramafic series, a thick column of magma with orthopyroxene on its liquidus would have been the result. Thus, the sequence of multiple injections, fractionation, and mixing with previously fractionated magma could have been the mechanism that produced the thick bronzite cumulate layer (the Bronzitite zone) above the cyclic units.

Determination of in vitro lung solubility and intake-to-dose conversion factor for tritiated lanthanum nickel aluminum alloy.

PubMed

Farfán, Eduardo B; Labone, Thomas R; Staack, Gregory C; Cheng, Yung-Sung; Zhou, Yue; Varallo, Thomas P

2012-09-01

A sample of tritiated lanthanum nickel aluminum alloy (LaNi4.25Al0.75 or LANA.75) similar to that used at the Savannah River Site Tritium Facilities was analyzed to estimate the particle size distribution of this metal tritide powder and the rate at which this material dissolves in the human respiratory tract after it is inhaled. This information is used to calculate the committed effective dose received by a worker after inhaling the material. These doses, which were calculated using the same methodology given in the U.S. Department of Energy Tritium Handbook, are presented as inhalation intake-to-dose conversion factors (DCF). The DCF for this metal tritide was determined to be 9.4 × 10 Sv Bq, which is less than the DCF for tritiated water. Therefore, the radiation worker bioassay programs designed for tritiated water are adequate to monitor for intakes of this material.

Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

DOEpatents

Leung, Ka-Ngo; Gordon, Keith C.; Kippenham, Dean O.; Purgalis, Peter; Moussa, David; Williams, Malcom D.; Wilde, Stephen B.; West, Mark W.

1989-01-01

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).

Intracavity frequency doubling of a continuous-wave, diode-laser-pumped neodymium lanthanum scandium borate laser.

PubMed

Meyn, J P; Huber, G

1994-09-15

Neodymium-doped lanthanum scandium borate [Nd:LaSc(3)(BO(3))(4)] is a new material for efficient and compact diode-pumped solid-state lasers. A simple plane-plane 3-mm-long resonator is formed by a coated Nd(10%):LaSc(3)(BO(3))(4) crystal and a coated potassium titanyl phosphate (KTP) crystal. The second-harmonic output power at 531 nm is 522 mW at 2.05-W incident pump power of the diode laser. The corresponding optical efficiency is 25%, and the conversion efficiency from the fundamental to the second harmonic is 55%. The wellknown chaotic power fluctuations of intracavity frequency-doubled lasers (green problem) are avoided by use of a short KTP crystal, between 0.5 and 2 mm in length.

The Bayo Canyon/radioactive lanthanum (RaLa) program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dummer, J.E.; Taschner, J.C.; Courtright, C.C.

1996-04-01

LANL conducted 254 radioactive lanthanum (RaLa) implosion experiments Sept. 1944-March 1962, in order to test implosion designs for nuclear weapons. High explosives surrounding common metals (surrogates for Pu) and a radioactive source containing up to several thousand curies of La, were involved in each experiment. The resulting cloud was deposited as fallout, often to distances of several miles. This report was prepared to summarize existing records as an aid in evaluating the off-site impact, if any, of this 18-year program. The report provides a historical setting for the program, which was conducted in Technical Area 10, Bayo Canyon about 3more » miles east of Los Alamos. A description of the site is followed by a discussion of collateral experiments conducted in 1950 by US Air Force for developing an airborne detector for tracking atmospheric nuclear weapons tests. All known off-site data from the RaLa program are tabulated and discussed. Besides the radiolanthanum, other potential trace radioactive material that may have been present in the fallout is discussed and amounts estimated. Off-site safety considerations are discussed; a preliminary off-site dose assessment is made. Bibliographical data on 33 persons important to the program are presented as footnotes.« less

Higher Strength Lanthanum Carbonate Provides Serum Phosphorus Control With a Low Tablet Burden and Is Preferred by Patients and Physicians: A Multicenter Study

PubMed Central

Mehrotra, Rajnish; Martin, Kevin J.; Fishbane, Steven; Sprague, Stuart M.; Zeig, Steven; Anger, Michael

2008-01-01

Background and objectives: Management of hyperphosphatemia, a predictor of mortality in chronic kidney disease, is challenging. Nonadherence to dietary phosphate binders, in part, contributes to uncontrolled serum phosphorus levels. This phase IIIb trial assessed the efficacy of increased dosages (3000 to 4500 mg/d) of reformulated lanthanum carbonate (500-, 750-, and 1000-mg tablets) in nonresponders to dosages of up to 3000 mg/d. Design, setting, participants, & measurements: This 8-wk study with a 4-mo open-label extension enrolled 513 patients who were undergoing maintenance hemodialysis. Patients who achieved serum phosphorus control at week 4 with ≤3000 mg/d lanthanum carbonate entered cohort A; nonresponders were randomly assigned to receive 3000, 3750, or 4500 mg/d (cohort B). The primary outcome measure was the control rate for predialysis serum phosphorus levels at the end of week 8, among patients in cohort B. Results: At the end of week 4, 54% of patients achieved serum phosphorus control at dosages ≤3000 mg/d administered as one tablet per meal. Among patients who entered cohort B, control rates of 25, 38, and 32% for patients who were randomly assigned to 3000, 3750, or 4500 mg/d lanthanum carbonate, respectively, were achieved, with no increase in adverse events. Patients and physicians reported significantly higher levels of satisfaction with reformulated lanthanum carbonate compared with previous phosphate binders, partly because of reduced tablet burden with higher dosage strengths. Physicians and patients also expressed a preference for lanthanum carbonate over previous medication. Conclusions: Reformulated lanthanum carbonate is an effective phosphate binder that may reduce daily tablet burden. PMID:18579668

METHOD OF SEPARATING PLUTONIUM FROM LANTHANUM FLUORIDE CARRIER

DOEpatents

Watt, G.W.; Goeckermann, R.H.

1958-06-10

An improvement in oxidation-reduction type methods of separating plutoniunn from elements associated with it in a neutron-irradiated uranium solution is described. The method relates to the separating of plutonium from lanthanum ions in an aqueous 0.5 to 2.5 N nitric acid solution by 'treating the solution, at room temperature, with ammonium sulfite in an amount sufficient to reduce the hexavalent plutonium present to a lower valence state, and then treating the solution with H/sub 2/O/sub 2/ thereby forming a tetravalent plutonium peroxide precipitate.

Health risk assessment from contaminated foodstuffs: a field study in chromite mining-affected areas northern Pakistan.

PubMed

Nawab, Javed; Li, Gang; Khan, Sardar; Sher, Hassan; Aamir, Muhammad; Shamshad, Isha; Khan, Anwarzeb; Khan, Muhammad Amjad

2016-06-01

This study aimed to investigate the potential health risk associated with toxic metals in contaminated foodstuffs (fruits, vegetables, and cereals) collected from various agriculture fields present in chromite mining-affected areas of mafic and ultramafic terrains (northern Pakistan). The concentrations of Cr, Ni, Zn, Cd, and Pb were quantified in both soil and food samples. The soil samples were highly contaminated with Cr (320 mg/kg), Ni (108 mg/kg), and Cd (2.55 mg/kg), which exceeded their respective safe limits set by FAO/WHO. Heavy metal concentrations in soil were found in the order of Cr>Ni>Pb>Zn>Cd and showed significantly (p < 0.001) higher concentrations as compared to reference soil. The integrated pollution load index (PLI) value was observed greater than three indicating high level of contamination in the study area. The concentrations of Cr (1.80-6.99 mg/kg) and Cd (0.21-0.90 mg/kg) in foodstuffs exceeded their safe limits, while Zn, Pb, and Ni concentrations were observed within their safe limits. In all foodstuffs, the selected heavy metal concentrations were accumulated significantly (p < 0.001) higher as compared to the reference, while some heavy metals were observed higher but not significant like Zn in pear, persimmon, white mulberry, and date-plum; Cd in pear, fig and white mulberry; and Pb in walnut, fig, and pumpkin. The health risk assessment revealed no potential risk for both adults and children for the majority of heavy metals, except Cd, which showed health risk index (HRI) >1 for children and can pose potential health threats for local inhabitants. Graphical Abstract Heavy metals released from chromite mining lead to soil and foodstuff contamination and human health risk.

Protonation of a lanthanum phosphide-alkyl occurs at the P-La not the C-La bond: isolation of a cationic lanthanum alkyl complex.

PubMed

Izod, Keith; Liddle, Stephen T; Clegg, William

2004-08-07

Protonation of the heteroleptic, cyclometalated lanthanum phosphide complex [((Me3Si)2CH)(C6H4-2-CH2NMe2)P]La(THF)[P(C6H4-2-CH2NMe2)(CH(SiMe3)(SiMe2CH2))] with [Et3NH][BPh4] yields the cationic alkyllanthanum complex [(THF)4La[P(C6H4-2-CH2NMe2)(CH(SiMe3)(SiMe2CH2))

Chromium valences in ureilite olivine and implications for ureilite petrogenesis

NASA Astrophysics Data System (ADS)

Goodrich, C. A.; Sutton, S. R.; Wirick, S.; Jercinovic, M. J.

2013-12-01

basaltic melt composition), consistent with fO2 values obtained by assuming olivine-silica-iron metal (OSI) equilibrium. For the primary chromite-bearing-ureilites, the corresponding fO2 were estimated (again, assuming basaltic melt composition) to be ∼IW to IW+1.0, i.e., several orders of magnitude more oxidizing than the conditions estimated for the chromite-free ureilites. In terms of Fo and Cr valence properties, ureilites appear to form two groups rather than a single “Cr-valence (or fO2) vs. Fo” trend. The chromite-bearing ureilites show little variation in Fo (∼74-76) but significant variation in Cr valence, while the non-chromite-bearing ureilites show significant variation in Fo (∼77-95) and little variation in Cr valence. These groups are unrelated to petrologic type (i.e., olivine-pigeonite, olivine-orthopyroxene, or augite-bearing). The chromite-bearing ureilites also have lower contents of Cr in olivine than most non-chromite-bearing ureilites, consistent with predictions based on Cr olivine/melt partitioning in spinel saturated vs. non-spinel-saturated systems. Under the assumption that at magmatic temperatures graphite-gas equilibria controlled fO2 at all depths on the ureilite parent body, we conclude: (1) that ureilite precursor materials having the Fo and Cr valence properties now observed in ureilites are unlikely to have been preserved during planetary processing; and (2) that the Fo and Cr valence properties now observed in ureilites are consistent with having been established by high-temperature carbon redox control over a range of depths on a plausible-sized ureilite parent body. The apparent limit on ureilite Fo values around 74-76 suggests that the precursor material(s) had bulk mg# ⩾ that of LL chondrites.

Characterization of Materials by Raman Scattering

NASA Astrophysics Data System (ADS)

Kozielski, M.

2007-03-01

The paper reports on the use of phonon spectra obtained with the Raman spectroscopy for characterization of different materials. The Raman scattering spectra obtained for zinc selenide crystals, mixed crystals zinc selenide admixtured with magnesium or beryllium, oxide crystals including strontium lanthanum gallate, molecular crystals of triammonium hydrogen diseleniate and a homologous series of polyoxyethylene glycols are analysed.

Evaluating the use of electronegativity in band alignment models through the experimental slope parameter of lanthanum aluminate heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Z. Q.; Chim, W. K.; Chiam, S. Y

2011-11-01

In this work, photoelectron spectroscopy is used to characterize the band alignment of lanthanum aluminate heterostructures which possess a wide range of potential applications. It is found that our experimental slope parameter agrees with theory using the metal-induced gap states model while the interface induced gap states (IFIGS) model yields unsatisfactory results. We show that this discrepancy can be attributed to the correlation between the dielectric work function and the electronegativity in the IFIGS model. It is found that the original trend, as established largely by metals, may not be accurate for larger band gap materials. By using a newmore » correlation, our experimental data shows good agreement of the slope parameter using the IFIGS model. This correlation, therefore, plays a crucial role in heterostructures involving wider bandgap materials for accurate band alignment prediction using the IFIGS model.« less

Investigation on the co-luminescence effect of europium (III)-lanthanum(III)-dopamine-sodium dodecylbenzene sulfonate system and its application.

PubMed

Si, Hailin; Zhao, Fang; Cai, Huan

2013-01-01

A novel luminescence, enhancement phenomenon in the europium(III)-dopamine-sodium dodecylbenzene sulfonate system was observed when lanthanum(III) was added. Based on this, a sensitive co-luminescence method was established for the determination of dopamine. The luminescence signal for the europium (III)-lanthanum(III)-dopamine-sodium dodecylbenzene sulfonate system was monitored at λ(ex) = 300 nm, λ(em) = 618 nm and pH 8.3. Under optimized conditions, the enhanced luminescence signal responded linearly to the concentration of dopamine in the range 1.0 × 10(-10)-5.0 × 10(-7) mol/L with a correlation coefficient of 0.9993 (n = 11). The detection limit (3σ) was 2.7 × 10(-11) mol/L and the relative standard deviation for 11 parallel measurements of 3.0 × 10(-8) mol/L dopamine was 1.9%. The presented method was successfully applied for the estimation of dopamine in samples of pharmaceutical preparations, human serum and urine. The possible luminescence enhancement mechanism of the system is discussed briefly. Copyright © 2013 John Wiley & Sons, Ltd.

Electronic structure and properties of lanthanum

NASA Astrophysics Data System (ADS)

Nixon, Lane; Papaconstantopoulos, Dimitrios

2008-03-01

The total energy and electronic structure of lanthanum have been calculated in the bcc, fcc, hcp and dhcp structures for pressures up to 50 GPa. The full potential linearized-augmented-planewave method was used with both the local-density and general-gradient approximations. The correct phase ordering has been found, with lattice parameters and bulk moduli in good agreement with experimental data. The GGA method shows excellent agreement overall while the LDA results show larger discrepancies. The calculated strain energies for the fcc and bcc structures demonstrate the respective stable and unstable configurations at ambient conditions. The calculated superconductivity properties under pressure for the fcc structure are also found to agree well with measurements. Both LDA and GGA, with minor differences, reproduce well the experimental results for Tc.

XPS and STEM studies of Allende acid insoluble residues

NASA Technical Reports Server (NTRS)

Housley, R. M.; Clarke, D. R.

1980-01-01

Data on Allende acid residues obtained both before and after etching with hot HNO3 are presented. X-ray photoelectron spectra show predominantly carbonaceous material plus Fe-deficient chromite in both cases. The HNO3 oxidizes the carbonaceous material to some extent. The small chromites in these residues have a wide range of compositions somewhat paralleling those observed in larger Allende chromites and in Murchison chromites, especially in the high Al contents; however, they are deficient in divalent cations, which makes them metastable and indicates that they must have formed at relatively low temperatures. It is suggested that they formed by precipitation of Cr(3+) and Fe(3+) from olivine at low temperature or during rapid cooling.

PROCESS USING POTASSIUM LANTHANUM SULFATE FOR FORMING A CARRIER PRECIPITATE FOR PLUTONIUM VALUES

DOEpatents

Angerman, A.A.

1958-10-21

A process is presented for recovering plutonium values in an oxidation state not greater than +4 from fluoride-soluble fission products. The process consists of adding to an aqueous acidic solution of such plutonium values a crystalline potassium lanthanum sulfate precipitate which carries the plutonium values from the solution.

Effect of heterovalent substitutions in yttrium chromite on the hyperfine interactions of {sup 119}Sn{sup 4+} studied by Mössbauer spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fabritchnyi, Pavel B., E-mail: pf_1404@yahoo.fr; Afanasov, Mikhail I.; Mezhuev, Evgeny M.

2016-03-15

In order to develop the {sup 119}Sn Mössbauer spectroscopic probe technique to study magnetically ordered materials, three Ca-substituted yttrium chromites, i.e. Y{sub 0.9}Ca{sub 0.1}CrO{sub 3}, Y{sub 0.9}Ca{sub 0.1}Cr{sub 0.9}Ti{sub 0.1}O{sub 3} and Y{sub 0.8}Ca{sub 0.2}Cr{sub 0.8}Ti{sub 0.2}O{sub 3}, doped with 0.3 atom-% Sn{sup 4+}, were for the first time investigated. {sup 119}Sn Mössbauer spectra, recorded at 4.2 K, have allowed, through analysis of the magnetic hyperfine field values, probed by {sup 119}Sn nuclei, to gain insight into the local magnetically active surrounding of different Sn{sup 4+} ions. In all of these compounds, partial segregation of Sn{sup 4+} ions is revealed.more » In the case of Y{sub 0.9}Ca{sub 0.1}CrO{sub 3}, neither highly oxidized Cr{sup 4+} nor Cr{sup 6+} species, expected to compensate for the Ca{sup 2+} positive charge deficit, is found in the vicinity of the {sup 119}Sn{sup 4+} probe. In the case of both studied Ti-containing chromites, {sup 119}Sn Mössbauer spectra have provided the original indirect evidence for the statistical distribution of Cr{sup 3+} and Ti{sup 4+} ions over the octahedral sites and permitted characterization of the occurring associates of Sn{sup 4+}. - Graphical abstract: Two kinds of Sn{sup 4+} associates allowing {sup 119}Sn Mössbauer spectra of tin-doped Y{sub 0.9}Ca{sub 0.1}Cr{sub 0.9}Ti{sub 0.1}O{sub 3} and Y{sub 0.8}Ca{sub 0.2}Cr{sub 0.8}Ti{sub 0.2}O{sub 3} to be accounted for. - Highlights: • {sup 119}Sn probe is tested as a source of information on the B-sublattice of AF perovskites. • Neither Cr{sup 3+} nor Cr{sup 6+} is detected nearby {sup 119}Sn{sup 4+} ions in Y{sub 0.9}Ca{sub 0.1}CrO{sub 3}. • Cr{sup 3+} and Ti{sup 4+} are found to be randomly distributed in Y{sub 1−x}Ca{sub x}Cr{sub 1−x}Ti{sub x}O{sub 3} (x=0.1 or 0.2). • Sn{sup 4+} dopant segregations are revealed in all of the studied materials.« less

Effects of lanthanum carbonate and calcium carbonate on fibroblast growth factor 23 and hepcidin levels in chronic hemodialysis patients.

PubMed

Chang, Yu-Ming; Tsai, Shih-Ching; Shiao, Chih-Chung; Liou, Hung-Hsiang; Yang, Chuan-Lan; Tung, Nai-Yu; Hsu, Kua-Sui; Chen, I-Ling; Liu, Mei-Chyn; Kao, Jsun-Liang; Jhen, Rong-Na; Huang, Ya-Ting

2017-10-01

Phosphate binders have an impact on fibroblast growth factor 23 (FGF23); however, the effect of phosphate binders on serum hepcidin has not been explored. We conducted a 24-week multicenter randomized controlled trial to investigate the effects of lanthanum carbonate or calcium carbonate monotherapy on serum phosphate, FGF23, and hepcidin levels in chronic hemodialysis patients. Forty-six patients were recruited, and daily dietary phosphorus was controlled between 600-800 mg. Serum calcium, phosphate, albumin, alkaline phosphatase (ALP), FGF23, intact parathyroid hormone (iPTH), hepcidin, high-sensitivity CRP (hsCRP), 25(OH)D, 1,25(OH) 2 D, fetuin-A, and osteopontin were checked as scheduled. Twenty-five patients completed the study. Mean serum FGF23 level was significantly decreased after a 24-week treatment with lanthanum (8677.5 ± 7490.0 vs. 4692.8 ± 5348.3 pg/mL, p = 0.013, n = 13), but not with calcium (n = 12). The reduction of serum hepcidin in lanthanum group was positively correlated with the decrement of serum phosphate (r = 0.631, p = 0.021) and serum hsCRP (r = 0.670, p = 0.012) levels, respectively. Serum ALP, iPTH, vitamin D, fetuin-A, and osteopontin revealed no significant inter- or intragroup differences. In summary, a decrease in serum FGF23 levels and a trend of decline in hepcidin levels were observed only in lanthanum group.

Highly enhanced adsorption of Congo red by functionalized finger-citron-leaf-based porous carbon.

PubMed

Zhao, Gui-Hua; Fang, Yao-Yao; Dai, Wei; Ma, Na

2018-01-01

A novel high-performance porous carbon material, lanthanum(III)-doped finger-citron-leaf-based porous carbon (La/FPC), has been synthesized and used as an adsorbent for anion dye Congo red (CR). The La/FPC was characterized by nitrogen adsorption and desorption isotherms, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The adsorption performance of CR by the FPC and La/FPC composites with different contents of lanthanum(III) were evaluated in fixed-bed breakthrough experiments and batch tests at room temperature (298 K). The La/FPC had a high CR uptake capacity, which was superior to those previously reported for other adsorbents. The La/FPC sorbents can be easily regenerated using an ethanol elution technique, and after five cycles the reused La/FPC maintained about 98% of its original CR adsorption capacity. The adsorption kinetics of CR onto the lanthanum(III)-doped FPCs followed a pseudo-second-order kinetic model and fitted well with a Langmuir adsorption isotherm. La/FPC is a promising adsorbent for the removal of the anionic dyes from wastewater.

Thermoelectric Power Generation from Lanthanum Strontium Titanium Oxide at Room Temperature through the Addition of Graphene.

PubMed

Lin, Yue; Norman, Colin; Srivastava, Deepanshu; Azough, Feridoon; Wang, Li; Robbins, Mark; Simpson, Kevin; Freer, Robert; Kinloch, Ian A

2015-07-29

The applications of strontium titanium oxide based thermoelectric materials are currently limited by their high operating temperatures of >700 °C. Herein, we show that the thermal operating window of lanthanum strontium titanium oxide (LSTO) can be reduced to room temperature by the addition of a small amount of graphene. This increase in operating performance will enable future applications such as generators in vehicles and other sectors. The LSTO composites incorporated one percent or less of graphene and were sintered under an argon/hydrogen atmosphere. The resultant materials were reduced and possessed a multiphase structure with nanosized grains. The thermal conductivity of the nanocomposites decreased upon the addition of graphene, whereas the electrical conductivity and power factor both increased significantly. These factors, together with a moderate Seebeck coefficient, meant that a high power factor of ∼2500 μWm(-1)K(-2) was reached at room temperature at a loading of 0.6 wt % graphene. The highest thermoelectric figure of merit (ZT) was achieved when 0.6 wt % graphene was added (ZT = 0.42 at room temperature and 0.36 at 750 °C), with >280% enhancement compared to that of pure LSTO. A preliminary 7-couple device was produced using bismuth strontium cobalt oxide/graphene-LSTO pucks. This device had a Seebeck coefficient of ∼1500 μV/K and an open voltage of 600 mV at a mean temperature of 219 °C.

Some metal-graphite and metal-ceramic composites for use as high energy brake lining materials

NASA Technical Reports Server (NTRS)

Bill, R. C.

1974-01-01

Materials were studied as candidates for development as potential new aircraft brake lining materials. These families were (1) copper-graphite composites; (2) nickel-graphite composites; (3) copper - rare-earth-oxide (gadolinium oxide (Gd2O3) or lanthanum oxide (La2O3)) composites and copper - rare-earth-oxide (La2O3) - rare-earth-fluoride (lanthanum fluoride (LaF3)) composites; (4) nickel - rare-earth-oxide composites and nickel - rare-earth-oxide - rare-earth-fluoride composites. For comparison purposes, a currently used metal-ceramic composite was also studied. Results showed that the nickel-Gd2O3 and nickel-La2O3-LaF3 composites were comparable or superior in friction and wear performance to the currently used composite and therefore deserve to be considered for further development.

Pressure increases, the formation of chromite seams, and the development of the ultramafic series in the Stillwater Complex, Montana

USGS Publications Warehouse

Lipin, B.R.

1993-01-01

This paper explores the hypothesis that chromate seams in the Stillwater Complex formed in response to periodic increases in total pressure in the chamber. Total pressure increased because of the positive ??V of nucleation of CO2 bubbles in the melt and their subsequent rise through the magma chamber, during which the bubbles increased in volume by a factor of 4-6. By analogy with the pressure changes in the summit chambers of Kilauea and Krafla volcanoes, the maximum variation was 0.2-0.25 kbar, or 5-10% of the total pressure in the Stillwater chamber. An evaluation of the likelihood of fountaining and mixing of a new, primitive liquid that entered the chamber with the somewhat more evolved liquid already in the chamber is based upon calculations using observed and inferred velocities and flow rates of basaltic magmas moving through volcanic fissures. The calculations indicate that hot, dense magma would have oozed, rather than fountained into the chamber, and early mixing of the new and residual magmas that could have resulted in chromite crystallizing alone did not take place. -from Author

Electrochemical performance of LiCoO 2 cathodes by surface modification using lanthanum aluminum garnet

NASA Astrophysics Data System (ADS)

Lu, Cheng-Zhang; Chen, Jin-Ming; Cho, Yung-Da; Hsu, Wen-Hsiang; Muralidharan, P.; Fey, George Ting-Kuo

LiCoO 2 particles were coated with various wt.% of lanthanum aluminum garnets (3LaAlO 3:Al 2O 3) by an in situ sol-gel process, followed by calcination at 1123 K for 12 h in air. X-ray diffraction (XRD) patterns confirmed the formation of a 3LaAlO 3:Al 2O 3 compound and the in situ sol-gel process synthesized 3LaAlO 3:Al 2O 3-coated LiCoO 2 was a single-phase hexagonal α-NaFeO 2-type structure of the core material without any modification. Scanning electron microscope (SEM) images revealed a modification of the surface of the cathode particles. Transmission electron microscope (TEM) images exposed that the surface of the core material was coated with a uniform compact layer of 3LaAlO 3:Al 2O 3, which had an average thickness of 40 nm. Galvanostatic cycling studies demonstrated that the 1.0 wt.% 3LaAlO 3:Al 2O 3-coated LiCoO 2 cathode showed excellent cycle stability of 182 cycles, which was much higher than the 38 cycles sustained by the pristine LiCoO 2 cathode material when it was charged at 4.4 V.

Magnetocaloric effect in potassium doped lanthanum manganite perovskites prepared by a pyrophoric method

NASA Astrophysics Data System (ADS)

Das, Soma; Dey, T. K.

2006-08-01

The magnetocaloric effect (MCE) in fine grained perovskite manganites of the type La1-xKxMnO3 (0lanthanum manganite enhances the Curie temperature (TC) of the system from 260.4 K (x = 0.05) to 309.7 K (x = 0.15). A large magnetic entropy change associated with the ferromagnetic-paramagnetic transition has been observed. The maximum entropy change |ΔSMMax| in an applied field of 1 T shows an enhancement by ~10% with increase in K content up to x = 0.15. La0.85K0.15MnO3 exhibits the largest |ΔSMMax| value of 3.00 J kg-1 K-1 at 310 K amongst the compounds investigated. Moreover, the maximum magnetic entropy change exhibits a linear dependence with applied magnetic field. The estimated adiabatic temperature change at TC and at 1 T field also increases with K doping, being a maximum of 2.1 K for the La0.85K0.15MnO3 compound. The relative cooling power (RCP) of La1-xKxMnO3 compounds is estimated to be about one-third of that of the prototype magnetic refrigerant material (pure Gd). However, La1-xKxMnO3 compounds possess an MCE around room temperature, which is comparable to that of Gd. Further, tailoring of their TC, higher chemical stability, lower eddy current heating and lower cost of synthesis are some of the attractive features of K doped lanthanum manganites that are advantageous for a magnetic refrigerant. The temperature dependence of the magnetic entropy change (ΔSM) measured under various magnetic fields is explained fairly well using the Landau theory of phase transitions. Contributions of magnetoelastic and electron interaction are found to have a strong influence in the magnetocaloric effect of manganites.

Effect of Organic Manures on the Growth of Cymbopogon citratus and Chrysopogon zizanioides for the Phytoremediation of Chromite-Asbestos Mine Waste: A Pot Scale Experiment.

PubMed

Kumar, Adarsh; Maiti, Subodh Kumar

2015-01-01

The abandoned chromite-asbestos mines are located in the Roro hills, West Singhbhum, Jharkhand, India, where mining operation ceased in 1983, and since then these mines are causing environmental pollution. The present study was planned to phytoremediate these metalloid and metal contaminated mine waste by using two aromatic grasses, Cymbopogon citratus and Chrysopogon zizanioides by applying different proportions of amendments (chicken manure, farmyard manure and garden soil). Mine waste has neutral pH, low electrical conductivity and organic carbon with higher concentration of total metals (Cr and Ni) as compared to soil. Application of manures resulted significant improvements of mine waste characteristics and plant growth, reduction in the availability of total extractable toxic metals (Cr, Ni) and increase in Mn, Zn and Cu concentration in the substrate. The maximum growth and biomass production for C. citratus and C. zizanioides were found in T-IV combination comprising of mine waste (90%), chicken manure (2.5%), farmyard manure (2.5%) and garden soil (5%). Addition of T-IV combination also resulted in low Cr and Ni accumulation in roots and reduction in translocation to shoots. Study indicates that C. citratus and C. zizanioides can be used for phytostabilization of abandoned chromite-asbestos mine waste with amendments.

Chlorination of lanthanum oxide.

PubMed

Gaviría, Juan P; Navarro, Lucas G; Bohé, Ana E

2012-03-08

The reactive system La(2)O(3)(s)-Cl(2)(g) was studied in the temperature range 260-950 °C. The reaction course was followed by thermogravimetry, and the solids involved were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the reaction leads to the formation of solid LaOCl, and for temperatures above 850 °C, the lanthanum oxychloride is chlorinated, producing LaCl(3)(l). The formation of the oxychloride progresses through a nucleation and growth mechanism, and the kinetic analysis showed that at temperatures below 325 °C the system is under chemical control. The influence of diffusive processes on the kinetics of production of LaOCl was evaluated by studying the effect of the reactive gas flow rate, the mass of the sample, and the chlorine diffusion through the boundary layer surrounding the solid sample. The conversion curves were analyzed and fitted according to the Johnson-Mehl-Avrami description, and the reaction order with respect to the chlorine partial pressure was obtained by varying this partial pressure between 10 and 70 kPa. The rate equation was obtained, which includes the influence of the temperature, chlorine partial pressure, and reaction degree.

Paramagnetic centers in two phases of manganese-doped lanthanum gallate

NASA Astrophysics Data System (ADS)

Vazhenin, V. A.; Potapov, A. P.; Guseva, V. B.; Artyomov, M. Yu.

2009-05-01

An EPR study of two phases of manganese-doped lanthanum gallate (with a first-order structural transition occurring at 430 K) has revealed Gd3+, Fe3+, and Mn4+ centers at room temperature and 438 K. The parameters of spin Hamiltonians are determined for the Gd3+, Fe3+, and Mn4+ rhombohedral centers in the high-temperature phase (with no other centers found here) and for the monoclinic center Gd3+ in the low-temperature phase. Both in the orthorhombic and in the rhombohedral phase, crystallographic twins (or ferroelastic domains) are observed.

The effect of physiologic aqueous solutions on the perovskite material lead-lanthanum-zirconium titanate (PLZT): potential retinotoxicity.

PubMed

Foster, William J; Meen, James K; Fox, Donald A

2013-03-01

Perovskite compounds, including lead-lanthanum-zirconium titanate (PLZT), have wide technological application because of their unique physical properties. The use of PLZT in neuro-prosthetic systems, such as retinal implants, has been discussed in a number of publications. Since inorganic lead is a retinotoxic compound that produces retinal degeneration, the long-term stability of PLZT in aqueous biological solutions must be determined. We evaluated the stability and effects of prolonged immersion of a PLZT-coated crystal in a buffered balanced salt solution. Scanning Electron Microscopy and Electron Dispersive Spectroscopy (EDS) using a JEOL JSM 5410 microscope equipped with EDS were utilized to evaluate the samples before and after prolonged immersion. We found that lead and other constituents of PLZT leached into the surrounding aqueous medium. By comparing the unit cell of PLZT with that of CaTiO(3), which has been found to react with aqueous fluids, Lead is in the same site in PLZT as Ca is in CaTiO(3). It is thus reasonable that PLZT will react with aqueous solutions. The results suggest that PLZT must either be coated with a protective layer or is not appropriate for long-term in vivo or in vitro biological applications.

Low cost stable air electrode material for high temperature solid oxide electrolyte electrochemical cells

DOEpatents

Kuo, Lewis J. H.; Singh, Prabhakar; Ruka, Roswell J.; Vasilow, Theodore R.; Bratton, Raymond J.

1997-01-01

A low cost, lanthanide-substituted, dimensionally and thermally stable, gas permeable, electrically conductive, porous ceramic air electrode composition of lanthanide-substituted doped lanthanum manganite is provided which is used as the cathode in high temperature, solid oxide electrolyte fuel cells and generators. The air electrode composition of this invention has a much lower fabrication cost as a result of using a lower cost lanthanide mixture, either a natural mixture or an unfinished lanthanide concentrate obtained from a natural mixture subjected to incomplete purification, as the raw material in place of part or all of the higher cost individual lanthanum. The mixed lanthanide primarily contains a mixture of at least La, Ce, Pr, and Nd, or at least La, Ce, Pr, Nd and Sm in its lanthanide content, but can also include minor amounts of other lanthanides and trace impurities. The use of lanthanides in place of some or all of the lanthanum also increases the dimensional stability of the air electrode. This low cost air electrode can be fabricated as a cathode for use in high temperature, solid oxide fuel cells and generators.

High-temperature superconductivity in space-charge regions of lanthanum cuprate induced by two-dimensional doping

PubMed Central

Baiutti, F.; Logvenov, G.; Gregori, G.; Cristiani, G.; Wang, Y.; Sigle, W.; van Aken, P. A.; Maier, J.

2015-01-01

The exploitation of interface effects turned out to be a powerful tool for generating exciting material properties. Such properties include magnetism, electronic and ionic transport and even superconductivity. Here, instead of using conventional homogeneous doping to enhance the hole concentration in lanthanum cuprate and achieve superconductivity, we replace single LaO planes with SrO dopant planes using atomic-layer-by-layer molecular beam epitaxy (two-dimensional doping). Electron spectroscopy and microscopy, conductivity measurements and zinc tomography reveal such negatively charged interfaces to induce layer-dependent superconductivity (Tc up to 35 K) in the space-charge zone at the side of the planes facing the substrate, where the strontium (Sr) profile is abrupt. Owing to the growth conditions, the other side exhibits instead a Sr redistribution resulting in superconductivity due to conventional doping. The present study represents a successful example of two-dimensional doping of superconducting oxide systems and demonstrates its power in this field. PMID:26481902

Effect of sputtered lanthanum hexaboride film thickness on field emission from metallic knife edge cathodes

NASA Astrophysics Data System (ADS)

Kirley, M. P.; Novakovic, B.; Sule, N.; Weber, M. J.; Knezevic, I.; Booske, J. H.

2012-03-01

We report experiments and analysis of field emission from metallic knife-edge cathodes, which are sputter-coated with thin films of lanthanum hexaboride (LaB6), a low-work function material. The emission current is found to depend sensitively on the thickness of the LaB6 layer. We find that films thinner than 10 nm greatly enhance the emitted current. However, cathodes coated with a thicker layer of LaB6 are observed to emit less current than the uncoated metallic cathode. This result is unexpected due to the higher work function of the bare metal cathode. We show, based on numerical calculation of the electrostatic potential throughout the structure, that the external (LaB6/vacuum) barrier is reduced with respect to uncoated samples for both thin and thick coatings. However, this behavior is not exhibited at the internal (metal/LaB6) barrier. In thinly coated samples, electrons tunnel efficiently through both the internal and external barrier, resulting in current enhancement with respect to the uncoated case. In contrast, the thick internal barrier in thickly coated samples suppresses current below the value for uncoated samples in spite of the lowered external barrier. We argue that this coating thickness variation stems from a relatively low (no higher than 1018 cm-3) free carrier density in the sputtered polycrystalline LaB6.

Integration of PLZT and BST family oxides with GaN[Lead Lanthanum Zirconate Titanate, Barium Strontium Titanate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osinsky, A.V.; Fuflyigin, V.N.; Wang, F.

2000-07-01

Recent advances in the processing of complex-oxide materials has allowed the authors to monolithically grow ferroelectrics of lead lanthanum zirconate titanate (PLZT) and barium strontium titanate (BST) systems on a GaN/sapphire structure. High quality films of PLZT and BST were grown on GaN/c-Al{sub 2}O{sub 3} in a thickness range of 0.3--5 {micro}m by a sol-gel technique. Field-induced birefringence, as large as 0.02, was measured from a PLZT layer grown on a buffered GaN/sapphire structure. UV illumination was found to result in more symmetrical electrooptic hysteresis loop. BST films on GaN demonstrated a low frequency dielectric constant of up to 800more » with leakage current density as low as 5.5 {center_dot} 10{sup {minus}8} A/cm{sup 2}.« less

White light emission of dysprosium doped lanthanum calcium phosphate oxide and oxyfluoride glasses

NASA Astrophysics Data System (ADS)

Luewarasirikul, N.; Kim, H. J.; Meejitpaisan, P.; Kaewkhao, J.

2017-04-01

Lanthanum calcium phosphate oxide and oxyfluoride glasses doped with dysprosium oxide were prepared by melt-quenching technique with chemical composition 20La2O3:10CaO:69P2O5:1Dy2O3 and 20La2O3:10CaF2:69P2O5:1Dy2O3. The physical, optical and luminescence properties of the glass samples were studied to evaluate their potential to using as luminescence materials for solid-state lighting applications. The density, molar volume and refractive index of the glass samples were carried out. The optical and luminescence properties were studied by investigating absorption, excitation, and emission spectra of the glass samples. The absorption spectra were investigated in the UV-Vis-NIR region from 300 to 2000 nm. The excitation spectra observed under 574 nm emission wavelength showed the highest peak centered at 349 nm (6H15/2 → 6P7/2). The emission spectra, excited with 349 nm excitation wavelength showed two major peaks corresponding to 482 nm blue emission (4F9/2 → 6H15/2) and 574 nm yellow emission (4F9/2 → 6H13/2). The experimental lifetime were found to be 0.539 and 0.540 for oxide and oxyfluoride glass sample, respectively. The x,y color coordinates under 349 nm excitation wavelength were (0.38, 0.43) for both glass samples, that be plotted in white region of CIE 1931 chromaticity diagram. The CCT values obtained from the glass samples are 4204 K for oxide glass and 4228 K for oxyfluoride glass corresponding to the commercial cool white light (3100-4500 K). Judd-Ofelt theory had also been employed to obtain the J-O parameters (Ω2, Ω4 and Ω6), oscillator strength, radiative transition possibility, stimulated emission cross section and branching ratio. The Ω2 > Ω4 > Ω6 trend of J-O parameters of both glass samples may indicate the good quality of a glass host for using as optical device application. Temperature dependence of emission spectra was studied from 300 K to 10 K and found that the intensity of the emission peak was found to be increased with

Grain Boundary Engineering of Lithium-Ion-Conducting Lithium Lanthanum Titanate for Lithium-Air Batteries

DTIC Science & Technology

2016-01-01

release; distribution is unlimited. 1 1. Introduction Lithium (Li)- ion batteries are currently one of the leading energy storage device technologies...ARL-TR-7584 ● JAN 2016 US Army Research Laboratory Grain Boundary Engineering of Lithium - Ion - Conducting Lithium Lanthanum...Titanate for Lithium -Air Batteries by Victoria L Blair, Claire V Weiss Brennan, and Joseph M Marsico Approved for public

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

NASA Technical Reports Server (NTRS)

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

1985-01-01

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.

Selective dehydration of bio-ethanol to ethylene catalyzed by lanthanum-phosphorous-modified HZSM-5: influence of the fusel.

PubMed

Hu, Yaochi; Zhan, Nina; Dou, Chang; Huang, He; Han, Yuwang; Yu, Dinghua; Hu, Yi

2010-11-01

Bio-ethanol dehydration to ethylene is an attractive alternative to oil-based ethylene. The influence of fusel, main byproducts in the fermentation process of bio-ethanol production, on the bio-ethanol dehydration should not be ignored. We studied the catalytic dehydration of bio-ethanol to ethylene over parent and modified HZSM-5 at 250°C, with weight hourly space velocity (WHSV) equal to 2.0/h. The influences of a series of fusel, such as isopropanol, isobutanol and isopentanol, on the ethanol dehydration over the catalysts were investigated. The 0.5%La-2%PHZSM-5 catalyst exhibited higher ethanol conversion (100%), ethylene selectivity (99%), and especially enhanced stability (more than 70 h) than the parent and other modified HZSM-5. We demonstrated that the introduction of lanthanum and phosphorous to HZSM-5 could weaken the negative influence of fusel on the formation of ethylene. The physicochemical properties of the catalysts were characterized by ammonia temperature-programmed desorption (NH(3)-TPD), nitrogen adsorption and thermogravimetry (TG)/differential thermogravimetry (DTG)/differential thermal analysis (DTA) (TG/DTG/DTA) techniques. The results indicated that the introduction of lanthanum and phosphorous to HZSM-5 could inhibit the formation of coking during the ethanol dehydration to ethylene in the presence of fusel. The development of an efficient catalyst is one of the key technologies for the industrialization of bio-ethylene.

Chemical synthesis and supercapacitive properties of lanthanum telluride thin film.

PubMed

Patil, S J; Lokhande, A C; Lee, D-W; Kim, J H; Lokhande, C D

2017-03-15

Lanthanum telluride (La 2 Te 3 ) thin films are synthesized via a successive ionic layer adsorption and reaction (SILAR) method. The crystal structure, surface morphology and surface wettability properties are investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM) and contact angle goniometer techniques, respectively. The La 2 Te 3 material exhibits a specific surface area of 51m 2 g -1 determined by Brunauer-Emmett-Teller (BET) method. La 2 Te 3 thin film electrode has a hydrophilic surface which consists of interconnected pine leaf-like flaky arrays that affect the performance of the supercapacitor. The supercapacitive performance of La 2 Te 3 film electrode is evaluated in 1M LiClO 4 /PC electrolyte using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy techniques. La 2 Te 3 film electrode exhibits a specific capacitance of 194Fg -1 at a scan rate of 5mVs -1 and stored energy density of 60Whkg -1 with delivering power density of 7.22kWkg -1 . La 2 Te 3 film electrode showed capacitive retention of 82% over 1000cycles at a scan rate of 100mVs -1 . Further, flexible La 2 Te 3 |LiClO 4 -PVA|La 2 Te 3 supercapacitor cell is fabricated. Copyright © 2016 Elsevier Inc. All rights reserved.

[An investigation of lanthanum and other metals levels in blood, urine and hair among residents in the rare earth mining area of a city in China].

PubMed

Bao, T M; Tian, Y; Wang, L X; Wu, T; Lu, L N; Ma, H Y; Wang, L

2018-02-20

Objective: To investigate the levels of lanthanum, cerium, praseodymium, and neodymium in the blood, urine, and hair samples from residents in the rare earth mining area of a city in China, and to provide a scientific basis for the control of rare earth pollution and the protection of population health. Methods: A total of 147 residents who had lived in the rare earth mining area of a city for a long time were selected as the exposure group, and 108 residents in Guyang County of this city who lived 91 km away from the rare earth mining area were selected as the control group. Blood, urine, and hair samples were collected from the residents in both groups. Inductively coupled plasma mass spectrometry was used to determine the content of lanthanum, cerium, praseodymium, and neodymium in blood, urine, and hair samples. Results: In the exposure group, the median levels of lanthanum, cerium, praseodymium, and neodymium were 0.854, 1.724, 0.132, and 0.839 μg/L, respectively, in blood samples, 0.420, 0.920, 0.055, and 0.337 μg/L, respectively, in urine samples, and 0.052, 0.106, 0.012, and 0.045 μg/g, respectively, in hair samples. The exposure group had significantly higher levels of the four rare earth elements in blood, urine, and hair samples than the control group ( P <0.01) . Conclusion: The residents in the rare earth mining area of this city have higher content of lanthanum, cerium, praseodymium, and neodymium in blood, urine, and hair than those in the non-mining area; the content of cerium is highest, followed by lanthanum, neodymium, and praseodymium.

Angle resolved x-ray photoelectron spectroscopy (ARXPS) analysis of lanthanum oxide for micro-flexography printing

NASA Astrophysics Data System (ADS)

Hassan, S.; Yusof, M. S.; Embong, Z.; Maksud, M. I.

2016-01-01

Micro-flexography printing was developed in patterning technique from micron to nano scale range to be used for graphic, electronic and bio-medical device on variable substrates. In this work, lanthanum oxide (La2O3) has been used as a rare earth metal candidate as depositing agent. This metal deposit was embedded on Carbon (C) and Silica (Si) wafer substrate using Magnetron Sputtering technique. The choose of Lanthanum as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La2O3 deposited on the surface of Si wafer substrate was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). The La 3d narrow scan revealed that the oxide species of this particular metal is mainly contributed by La2O3 and La(OH)3. The information of oxygen species, O2- component from O 1s narrow scan indicated that there are four types of species which are contributed from the bulk (O2-), two chemisorb component (La2O3) and La(OH)3 and physisorp component (OH). Here, it is proposed that from the adhesive and surface chemical properties of La, it is suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal for use in of micro-flexography printing practice. The review of other parameters contributing to print fine lines will also be described later.

Angle resolved x-ray photoelectron spectroscopy (ARXPS) analysis of lanthanum oxide for micro-flexography printing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hassan, S., E-mail: suhaimihas@uthm.edu.my; Yusof, M. S., E-mail: mdsalleh@uthm.edu.my; Maksud, M. I., E-mail: midris1973@gmail.com

2016-01-22

Micro-flexography printing was developed in patterning technique from micron to nano scale range to be used for graphic, electronic and bio-medical device on variable substrates. In this work, lanthanum oxide (La{sub 2}O{sub 3}) has been used as a rare earth metal candidate as depositing agent. This metal deposit was embedded on Carbon (C) and Silica (Si) wafer substrate using Magnetron Sputtering technique. The choose of Lanthanum as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La{sub 2}O{sub 3} deposited on the surface of Si wafer substratemore » was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). The La 3d narrow scan revealed that the oxide species of this particular metal is mainly contributed by La{sub 2}O{sub 3} and La(OH){sub 3}. The information of oxygen species, O{sup 2-} component from O 1s narrow scan indicated that there are four types of species which are contributed from the bulk (O{sup 2−}), two chemisorb component (La{sub 2}O{sub 3}) and La(OH){sub 3} and physisorp component (OH). Here, it is proposed that from the adhesive and surface chemical properties of La, it is suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal for use in of micro-flexography printing practice. The review of other parameters contributing to print fine lines will also be described later.« less

Novel multifunctional titania-silica-lanthanum phosphate nanocomposite coatings through an all aqueous sol-gel process.

PubMed

Smitha, Venu Sreekala; Jyothi, Chembolli Kunhatta; Peer, Mohamed A; Pillai, Saju; Warrier, Krishna Gopakumar

2013-04-07

A novel nanocomposite coating containing titania, silica and lanthanum phosphate prepared through an all aqueous sol-gel route exhibits excellent self-cleaning ability arising from the synergistic effect of the constituents in the nanocomposite. A highly stable titania-silica-lanthanum phosphate nanocomposite sol having particle size in the range of 30-50 nm has been synthesized starting from a titanyl sulphate precursor, which was further used for the development of photocatalytically active composite coatings on glass. The coatings prepared by the dip coating technique as well as the nanocomposite powders are heat treated and characterized further for their morphology and multifunctionality. The nanocomposite containing 1.5 wt% LaPO4 has shown a surface area as high as 138 m(2) g(-1) and a methylene blue degradation efficiency of 94% in two hours of UV exposure. The composite coating has shown very good homogeneity evidenced by transparency as high as 99.5% and low wetting behaviour. The present novel approach for energy conserving, aqueous derived, self-cleaning coatings may be suitable for large scale industrial applications.

Development of a standard reference material for Cr(vi) in contaminated soil

USGS Publications Warehouse

Nagourney, S.J.; Wilson, S.A.; Buckley, B.; Kingston, H.M.S.; Yang, S.-Y.; Long, S.E.

2008-01-01

Over the last several decades, considerable contamination by hexavalent chromium has resulted from the land disposal of Chromite Ore Processing Residue (COPR). COPR contains a number of hexavalent chromium-bearing compounds that were produced in high temperature industrial processes. Concern over the carcinogenic potential of this chromium species, and its environmental mobility, has resulted in efforts to remediate these waste sites. To provide support to analytical measurements of hexavalent chromium, a candidate National Institute of Standards and Technology (NIST) Standard Reference Material?? (SRM 2701), having a hexavalent chromium content of approximately 500 mg kg -1, has been developed using material collected from a waste site in Hudson County, New Jersey, USA. The collection, processing, preparation and preliminary physico-chemical characterization of the material are discussed. A two-phase multi-laboratory testing study was carried out to provide data on material homogeneity and to assess the stability of the material over the duration of the study. The study was designed to incorporate several United States Environmental Protection Agency (USEPA) determinative methods for hexavalent chromium, including Method 6800 which is based on speciated isotope dilution mass spectrometry (SIDMS), an approach which can account for chromium species inter-conversion during the extraction and measurement sequence. This journal is ?? The Royal Society of Chemistry 2008.

Efficiency of Cs-free materials for negative ion production in H2 and D2 plasmas

NASA Astrophysics Data System (ADS)

Friedl, R.; Kurutz, U.; Fantz, U.

2017-08-01

High power negative ion sources use caesium to reduce the work function of the converter surface which significantly increases the negative ion yield. Caesium, however, is a very reactive alkali-metal and shows complex redistribution dynamics in consequence of plasma-surface-interaction. Thus, maintaining a stable and homogenous low work function surface is a demanding task, which is not easily compatible with the RAMI issues (reliability, availability, maintainability, inspectability) for a future DEMO fusion reactor. Hence, Cs-free alternative materials for efficient negative ion formation are desirable. At the laboratory experiment HOMER materials which are referred to as promising are investigated under identical and ion source relevant parameters: the refractory metals Ta and W, non-doped and boron-doped diamond as well as materials with inherent low work function (lanthanum-doped molybdenum, MoLa and lanthanum hexaboride, LaB6). The results are compared to the effect of in-situ caesiation, which at HOMER leads to a maximal increase of the negative ion density by a factor of 2.5. Among the examined samples low work function materials are most efficient. In particular, MoLa leads to an increase of almost 50 % compared to pure volume formation. The difference to a caesiated surface can be attributed to the still higher work function of MoLa, which is expected to be slightly below 3 eV. Using deuterium instead of hydrogen leads to increased atomic and positive ion densities, while comparable negative ion densities are achieved. In contrast to the low work function materials, bulk samples of the refractory metals as well as carbon based materials have no enhancing effect on H-, where the latter materials furthermore show severe erosion due to the hydrogen plasma.

Application of far infrared rare earth mineral composite materials to liquefied petroleum gas.

PubMed

Zhu, Dongbin; Liang, Jinsheng; Ding, Yan; Xu, Anping

2010-03-01

Far infrared rare earth mineral composite materials were prepared by the coprecipitation method using tourmaline, cerium acetate, and lanthanum acetate as raw materials. The results of Fourier transform infrared spectroscopy show that tourmaline modified with the rare earths La and Ce has a better far infrared emitting performance. Through XRD analysis, we attribute the improved far infrared emission properties of the tourmaline to the unit cell shrinkage of the tourmaline arising from La enhancing the redox properties of nano-CeO2. The effect of the composite materials on the combustion of liquefied petroleum gas (LPG) was studied by the flue gas analysis and water boiling test. Based on the results, it was found that the composite materials could accelerate the combustion of LPG, and that the higher the emissivity of the rare earth mineral composite materials, the better the effects on combustion of LPG. In all activation styles, both air and LPG to be activated has a best effect, indicating the activations having a cumulative effect.

Synthesis, characterization, and catalytic activity of Rh-based lanthanum zirconate pyrochlores for higher alcohol synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdelsayed, Victor; Shekhawat, Dushyant; Poston, James A.

2013-05-01

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 phasemore » (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.« less

Sub-nanometer surface chemistry and orbital hybridization in lanthanum-doped ceria nano-catalysts revealed by 3D electron microscopy.

PubMed

Collins, Sean M; Fernandez-Garcia, Susana; Calvino, José J; Midgley, Paul A

2017-07-14

Surface chemical composition, electronic structure, and bonding characteristics determine catalytic activity but are not resolved for individual catalyst particles by conventional spectroscopy. In particular, the nano-scale three-dimensional distribution of aliovalent lanthanide dopants in ceria catalysts and their effect on the surface electronic structure remains unclear. Here, we reveal the surface segregation of dopant cations and oxygen vacancies and observe bonding changes in lanthanum-doped ceria catalyst particle aggregates with sub-nanometer precision using a new model-based spectroscopic tomography approach. These findings refine our understanding of the spatially varying electronic structure and bonding in ceria-based nanoparticle aggregates with aliovalent cation concentrations and identify new strategies for advancing high efficiency doped ceria nano-catalysts.

Methanol synthesis using a catalyst combination of alkali or alkaline earth salts and reduced copper chromite

DOEpatents

Tierney, J.W.; Wender, I.; Palekar, V.M.

1995-01-24

The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a catalyst combination comprising reduced copper chromite and basic alkali salts or alkaline earth salts. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100--160 C and the pressure range of 40--65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H[sub 2]/CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

Methanol synthesis using a catalyst combination of alkali or alkaline earth salts and reduced copper chromite

DOEpatents

Tierney, John W.; Wender, Irving; Palekar, Vishwesh M.

1995-01-01

The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a catalyst combination comprising reduced copper chromite and basic alkali salts or alkaline earth salts. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100.degree.-160.degree. C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H.sub.2 /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

Investigation of La xSr 1-xCo yM 1-yO 3-δ (M = Mn Fe) perovskite materials as thermochemical energy storage media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babiniec, Sean Michael; Coker, Eric Nicholas; Miller, James E.

2015-06-23

Materials in the La xSr 1–xCo yMn 1–yO 3–δ (LSCM) and La xSr 1–xCo yFe 1–yO 3–δ (LSCF) families are candidates for high-temperature thermochemical energy storage due to their facility for cyclic endothermic reduction and exothermic oxidation. A set of 16 LSCM and 21 LSCF compositions were synthesized by a modified Pechini method and characterized by powder X-ray diffraction and thermogravimetric analysis. All materials were found to be various symmetries of the perovskite phase. LSCM was indexed as tetragonal, cubic, rhombohedral, or orthorhombic as a function of increased lanthanum content. For LSCF, compositions containing low lanthanum content were indexed asmore » cubic while materials with high lanthanum content were indexed as rhombohedral. An initial screening of redox activity was completed by thermogravimetric analysis for each composition. The top three compositions with the greatest recoverable redox capacity for each family were further characterized in equilibrium thermogravimetric experiments over a range of temperatures and oxygen partial pressures. As a result, these equilibrium experiments allowed the extraction of thermodynamic parameters for LSCM and LSCF compositions operated in thermochemical energy storage conditions.« less

Work function determination of promising electrode materials for thermionic converters

NASA Technical Reports Server (NTRS)

Jacobson, D.

1977-01-01

Work performed on this contract was primarily for the evaluation of selected electrode materials for thermionic energy converters. The original objective was to characterize selected nickel based superalloys up to temperatures of 1400 K. It was found that an early selection, Inconel 800 produced a high vapor pressure which interfered with the vacuum emission measurements. The program then shifted to two other areas. The first area was to obtain emission from the superalloys in a cesiated atmosphere. The cesium plasma helps to suppress the vaporization interference. The second area involved characterization of the Lanthanum-Boron series as thermionic emitters. These final two areas resulted in three journal publications which are attached to this report.

Microstructural analyses of Cr(VI) speciation in chromite ore processing Residue (COPR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

CHRYSOCHOOU, MARIA; FAKRA, SIRINE C .; Marcus, Matthew A.

2010-03-01

The speciation and distribution of Cr(VI) in the solid phase was investigated for two types of chromite ore processing residue (COPR) found at two deposition sites in the United States: gray-black (GB) granular and hard brown (HB) cemented COPR. COPR chemistry and mineralogy were investigated using micro-X-ray absorption spectroscopy and micro-X-ray diffraction, complemented by laboratory analyses. GB COPR contained 30percent of its total Cr(VI) (6000 mg/kg) as large crystals(>20 ?m diameter) of a previously unreported Na-rich analog of calcium aluminum chromate hydrates. These Cr(VI)-rich phases are thought to be vulnerable to reductive and pH treatments. More than 50percent of themore » Cr(VI) was located within nodules, not easily accessible to dissolved reductants, and bound to Fe-rich hydrogarnet, hydrotalcite, and possibly brucite. These phases are stable over a large pH range, thus harder to dissolve. Brownmilleritewasalso likely associated with physical entrapment of Cr(VI) in the interior of nodules. HB COPR contained no Cr(VI)-rich phases; all Cr(VI) was diffuse within the nodules and absent from the cementing matrix, with hydrogarnet and hydrotalcite being the main Cr(VI) binding phases. Treatment ofHBCOPRis challenging in terms of dissolving the acidity-resistant, inaccessible Cr(VI) compounds; the same applies to ~;;50percent of Cr(VI) in GB COPR.« less

Low cost stable air electrode material for high temperature solid oxide electrolyte electrochemical cells

DOEpatents

Kuo, L.J.H.; Singh, P.; Ruka, R.J.; Vasilow, T.R.; Bratton, R.J.

1997-11-11

A low cost, lanthanide-substituted, dimensionally and thermally stable, gas permeable, electrically conductive, porous ceramic air electrode composition of lanthanide-substituted doped lanthanum manganite is provided which is used as the cathode in high temperature, solid oxide electrolyte fuel cells and generators. The air electrode composition of this invention has a much lower fabrication cost as a result of using a lower cost lanthanide mixture, either a natural mixture or an unfinished lanthanide concentrate obtained from a natural mixture subjected to incomplete purification, as the raw material in place of part or all of the higher cost individual lanthanum. The mixed lanthanide primarily contains a mixture of at least La, Ce, Pr, and Nd, or at least La, Ce, Pr, Nd and Sm in its lanthanide content, but can also include minor amounts of other lanthanides and trace impurities. The use of lanthanides in place of some or all of the lanthanum also increases the dimensional stability of the air electrode. This low cost air electrode can be fabricated as a cathode for use in high temperature, solid oxide fuel cells and generators. 4 figs.

Europium-Doped Lanthanum Hafnate Nanoparticles: Structure, Photoluminescence, and Radioluminescence

NASA Astrophysics Data System (ADS)

Wahid, Kareem; Pokhrel, Madhab; Mao, Yuanbing

Due to their novel physical properties, nanostructured phosphors are of interest for radiation-based imaging and therapeutics. Herein, the structural and luminescent properties of europium-doped lanthanum hafnate (La2Hf2O7:xmol%Eu3+, x = 0 - 35) nanoparticles are investigated for use as scintillators. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy confirm samples prepared through a combined co-precipitation and low-temperature molten salt synthetic process homogenously form spherical nanocrystals of 36 nm in the ordered pyrochlore phase. Ultraviolet and X-ray excitation of these samples induce strong red emissions in the 580 - 590 and 612 - 630 nm range corresponding to the 5D0->7 F1 magnetic dipole and 5D0->7 F2 electric dipole transitions of Eu3+. Optical response and quantum yield are optimized at 5% Eu3+; a proposed trade-off between quenching mechanisms (defect-states/cross-relaxation) and dopant concentration is discussed. Owing to their high density, large effective atomic number, and bright luminescence, these La2Hf2O7:xmol%Eu3+ nanoparticles warrant further investigation for scintillator applications. The authors thank the support from the Defense Threat Reduction Agency of the U.S. Department of Defense (award #HDTRA1- 10-1-0114).

First-principles Investigation of the Structure, Mobility and Optical Properties of Self-Trapped Excitons in Alkali Metal, Lanthanum and Barium Halide Scintillators

NASA Astrophysics Data System (ADS)

Bizarri, Gregory; Del Ben, Mauro; Bourret, Edith; Canning, Andrew

The performance of new and improved materials for gamma ray scintillator detectors is dependant on multiple factors such as quantum efficiency, energy transport etc. In halide scintillator materials the energy transport is often impacted by self-trapped exciton (STE) formation and mobility. We present first-principles calculations at the hybrid density functional theory level for the structure, mobility and optical properties of STEs and their associated lattice defects (VK centers) in two important families of scintillator materials, alkali metal and lanthanum halides (AX and LaX). AX and LaX have been extensively characterized by experiments and serve as benchmark systems to assess the accuracy of our theoretical procedure. We show that hydrid functionals accurately predict the different types of self-trapped excitons (on and off-center) found in AX and LX materials in agreement with EPR experiments. We then applied this approach to perform preliminary studies on classes of new scintillator materials including the barium mixed halides and compared with our new experimental results. These studies have the potential to benefit the development of improved scintillator materials tailored for specific applications. This work is supported by the U.S. Department of Energy/NNSA/DNN R&D and is carried out at Lawrence Berkeley National Laboratory under Contract No. AC02-05CH11231.

Comparison between methods using copper, lanthanum, and colorimetry for the determination of the cation exchange capacity of plant cell walls.

PubMed

Wehr, J Bernhard; Blamey, F Pax C; Menzies, Neal W

2010-04-28

The determination of the cation exchange capacity (CEC) of plant cell walls is important for many physiological studies. We describe the determination of cell wall CEC by cation binding, using either copper (Cu) or lanthanum (La) ions, and by colorimetry. Both cations are strongly bound by cell walls, permitting fast and reproducible determinations of the CEC of small samples. However, the dye binding methods using two cationic dyes, Methylene Blue and Toluidine Blue, overestimated the CEC several-fold. Column and centrifugation methods are proposed for CEC determination by Cu or La binding; both provide similar results. The column method involves packing plant material (2-10 mg dry mass) in a chromatography column (10 mL) and percolating with 20 bed volumes of 1 mM La or Cu solution, followed by washing with deionized water. The centrifugation method uses a suspension of plant material (1-2 mL) that is centrifuged, and the pellet is mixed three times with 10 pellet volumes of 1 mM La or Cu solution followed by centrifugation and final washing with deionized water. In both methods the amount of La or Cu bound to the material was determined by spectroscopic methods.

Aquatic ecotoxicity of lanthanum - A review and an attempt to derive water and sediment quality criteria.

PubMed

Herrmann, Henning; Nolde, Jürgen; Berger, Svend; Heise, Susanne

2016-02-01

Rare earth elements (REE) used to be taken as tracers of geological origin for fluvial transport. Nowadays their increased applications in innovative environmental-friendly technology (e.g. in catalysts, superconductors, lasers, batteries) and medical applications (e.g. MRI contrast agent) lead to man-made, elevated levels in the environment. So far, no regulatory thresholds for REE concentrations and emissions to the environment have been set because information on risks from REE is scarce. However, evidence gathers that REE have to be acknowledged as new, emerging contaminants with manifold ways of entry into the environment, e.g. through waste water from hospitals or through industrial effluents. This paper reviews existing information on bioaccumulation and ecotoxicity of lanthanum in the aquatic environment. Lanthanum is of specific interest as one of the major lanthanides in industrial effluents. This review focuses on the freshwater and the marine environment, and tackles the water column and sediments. From these data, methods to derive quality criteria for sediment and water are discussed and preliminary suggestions are made. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

[La(UO{sub 2})V{sub 2}O{sub 7}][(UO{sub 2})(VO{sub 4})] the first lanthanum uranyl-vanadate with structure built from two types of sheets based upon the uranophane anion-topology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mer, A.; Obbade, S.; Rivenet, M.

2012-01-15

The new lanthanum uranyl vanadate divanadate, [La(UO{sub 2})V{sub 2}O{sub 7}][(UO{sub 2})(VO{sub 4})] was obtained by reaction at 800 Degree-Sign C between lanthanum chloride, uranium oxide (U{sub 3}O{sub 8}) and vanadium oxide (V{sub 2}O{sub 5}) and the structure was determined from single-crystal X-ray diffraction data. This compound crystallizes in the orthorhombic system with space group P2{sub 1}2{sub 1}2{sub 1} and unit-cell parameters a=6.9470(2) A, b=7.0934(2) A, c=25.7464(6) A, V=1268.73(5) A{sup 3}, Z=4. A full matrix least-squares refinement yielded R{sub 1}=0.0219 for 5493 independent reflections. The crystal structure is characterized by the stacking of uranophane-type sheets {sup 2}{sub {infinity}}[(UO{sub 2})(VO{sub 4})]{sup -}more » and double layers {sup 2}{sub {infinity}}[La(UO{sub 2})(V{sub 2}O{sub 7})]{sup +} connected through La-O bonds involving the uranyl oxygen of the uranyl-vanadate sheets. The double layers result from the connection of two {sup 2}{sub {infinity}}[La(UO{sub 2})(VO{sub 4}){sub 2}]{sup -} sheets derived from the uranophane anion-topology by replacing half of the uranyl ions by lanthanum atoms and connected through the formation of divanadate entities. - Graphical abstract: A view of the three-dimensional structure of [La(UO{sub 2})V{sub 2}O{sub 7}][(UO{sub 2})(VO{sub 4})]. Highlights: Black-Right-Pointing-Pointer New lanthanum uranyl vanadate divanadate has been synthesized. Black-Right-Pointing-Pointer Structure was determined from single-crystal X-ray diffraction data. Black-Right-Pointing-Pointer Structure is characterized by uranophane-type sheets and double layers {sup 2}{sub {infinity}}[La(UO{sub 2})(V{sub 2}O{sub 7})]{sup +}.« less

Kinetics of thermolysis of lanthanum nitrate with hexamethylenetetramine: Crystal structure, TG-DSC, impact and friction sensitivity studies, Part-96

NASA Astrophysics Data System (ADS)

Nibha; Baranwal, B. P.; Singh, Gurdip; Singh, C. P.; Daniliuc, Constantin G.; Soni, P. K.; Nath, Yogeshwar

2014-11-01

The development of high energetic materials includes process ability and the ability to attain insensitive munitions (IM). This paper investigates the preparation of lanthanum metal nitrate complex of hexamethylenetetramine in water at room temperature. This complex of molecular formulae [La (NO3)2(H2O)6] (2HMTA) (NO3-) (H2O) was characterized by X-ray crystallography. Thermal decomposition was investigated using TG, TG-DSC and ignition delay measurements. Kinetic analysis of isothermal TG data has been investigated using model fitting methods as well as model free isoconversional methods. The sensitivity measurements towards mechanical destructive stimuli such as impact and friction were carried out and the complex was found to be insensitive. In order to identify the end product of thermolysis, X-ray diffraction patterns of end product was carried out which proves the formation of La2O3.

Solid oxide fuel cells with apatite-type lanthanum silicate-based electrolyte films deposited by radio frequency magnetron sputtering

NASA Astrophysics Data System (ADS)

Liu, Yi-Xin; Wang, Sea-Fue; Hsu, Yung-Fu; Wang, Chi-Hua

2018-03-01

In this study, solid oxide fuel cells (SOFCs) containing high-quality apatite-type magnesium doped lanthanum silicate-based electrolyte films (LSMO) deposited by RF magnetron sputtering are successfully fabricated. The LSMO film deposited at an Ar:O2 ratio of 6:4 on an anode supported NiO/Sm0.2Ce0·8O2-δ (SDC) substrate followed by post-annealing at 1000 °C reveals a uniform and dense c-axis oriented polycrystalline structure, which is well adhered to the anode substrate. A composite SDC/La0·6Sr0·4Co0·2Fe0·8O3-δ cathode layer is subsequently screen-printed on the LSMO deposited anode substrate and fired. The SOFC fabricated with the LSMO film exhibits good mechanical integrity. The single cell with the LSMO layer of ≈2.8 μm thickness reports a total cell resistance of 1.156 and 0.163 Ωcm2, open circuit voltage of 1.051 and 0.982 V, and maximum power densities of 0.212 and 1.490 Wcm-2 at measurement temperatures of 700 and 850 °C, respectively, which are comparable or superior to those of previously reported SOFCs with yttria stabilized zirconia electrolyte films. The results of the present study demonstrate the feasibility of deposition of high-quality LSMO films by RF magnetron sputtering on NiO-SDC anode substrates for the fabrication of SOFCs with good cell performance.

Electrochemical fluorination of La(2)CuO(4): a mild "chimie douce" route to superconducting oxyfluoride materials.

PubMed

Delville, M H; Barbut, D; Wattiaux, A; Bassat, J M; Ménétrier, M; Labrugère, C; Grenier, J C; Etourneau, J

2009-08-17

The fluorination of La(2)CuO(4) was achieved for the first time under normal conditions of pressure and temperature (1 MPa and 298 K) via electrochemical insertion in organic fluorinated electrolytes and led to lanthanum oxyfluorides of general formula La(2)CuO(4)F(x). Analyses showed that, underneath a very thin layer of LaF(3) (a few atomic layers), fluorine is effectively inserted in the material's structure. The fluorination strongly modifies the lanthanum environment, whereas very little modification is observed on copper, suggesting an insertion in the La(2)O(2) blocks of the structure. In all cases, fluorine insertion breaks the translation symmetry and introduces a long-distance disorder, as shown by electron spin resonance. These results highlight the efficiency of electrochemistry as a new "chimie douce" type fluorination technique for solid-state materials. Performed at room temperature, it additionally does not require any specific experimental care. The choice of the electrolytic medium is crucial with regard to the fluorine insertion rate as well as the material deterioration. Successful application of this technique to the well-known La(2)CuO(4) material provides a basis for further syntheses from other oxides.

Energy transfer driven tunable emission of Tb/Eu co-doped lanthanum molybdate nanophosphors

NASA Astrophysics Data System (ADS)

Thomas, Kukku; Alexander, Dinu; Sisira, S.; Gopi, Subash; Biju, P. R.; Unnikrishnan, N. V.; Joseph, Cyriac

2018-06-01

Tb3+/Eu3+ co-doped lanthanum molybdate nanophosphors were synthesized by conventional co-precipitation method. The Powder X-ray diffractogram revealed the formation of highly crystalline tetragonal nanocrystals with space group I41/a and the detailed analysis of the small variation of lattice parameters with Tb/Eu co-doping on the host lattice were carried out based on the ionic radii of the dopants. The FTIR spectra is employed to identify the fundamental vibrational modes in La2-x-y (MoO4)3:xTb, yEu nanocrystals. The formation of nanocrystals by oriented attachment was recognized from the HR TEM images and the d-spacing calculated was in accordance with that corresponding to highest intensity diffraction peak in the XRD patterns. The constituent elements present in the samples were identified with the aid of EDAX and elemental mapping analysis. The broad Mo6+- O2- CTB and the sharp excitation peaks of Tb and Eu identified from the UV-Vis absorption spectra facilitates the suitability of exciting the phosphors effectively over NUV and visible region of the spectra. The possibility of energy transfer from host to Tb3+/Eu3+ ions and from Tb3+ to Eu3+ ions were confirmed from the PL excitation spectra monitoring 5D0→7F2 transition of Eu3+ ions around 615 nm. The correlated analysis of PL emission spectra, life time measurements and CIE diagram, upon different excitation channels elucidate the excellent luminescent properties of La2-x-y (MoO4)3:xTb, yEu nanophosphors with tunable emission colours in a wide range varying from yellow green region to reddish orange region and the efficient energy transfer from Tb3+ to Eu3+ ions in lanthanum molybdate host lattice. The Tb→Eu energy transfer efficiency and probability were calculated from the decay measurements and the values were found to be satisfactory for exploiting the prepared nanophosphors for the development of multifunctional luminescent nanophosphors.

IN SITU SOURCE TREATMENT OF CR(VI) USING A FE(II)-BASED REDUCTANT BLEND: LONG-TERM MONITORING AND EVALUATION

EPA Science Inventory

The long-term effectiveness of a FeSO4 + Na2S2O4 reductant solution blend for in situ saturated zone treatment of dissolved and solid phase Cr(VI) in a high pH chromite ore processing solid waste (COPSW) fill material was investigated. Two field pilot injection studies were cond...

Effect of dissimilatory Fe(III) reducers on bio-reduction and nickel-cobalt recovery from Sukinda chromite-overburden.

PubMed

Esther, Jacintha; Panda, Sandeep; Behera, Sunil K; Sukla, Lala B; Pradhan, Nilotpala; Mishra, Barada K

2013-10-01

The effect of an adapted dissimilatory iron reducing bacterial consortium (DIRB) towards bio-reduction of Sukinda chromite overburden (COB) with enhanced recovery of nickel and cobalt is being reported for the first time. The remarkable ability of DIRB to utilize Fe(III) as terminal electron acceptor reducing it to Fe(II) proved beneficial for treatment of COB as compared to previous reports for nickel leaching. XRD studies showed goethite as the major iron-bearing phase in COB. Under facultative anaerobic conditions, goethite was reduced to hematite and magnetite with the exposure of nickel oxide. FESEM studies showed DIRB to be associated with COB through biofilm formation with secondary mineral precipitates of magnetite deposited as tiny globular clusters on the extra polymeric substances. The morphological and mineralogical changes in COB, post DIRB application, yielded a maximum of 68.5% nickel and 80.98% cobalt in 10 days using 8M H2SO4. Copyright © 2013 Elsevier Ltd. All rights reserved.

Stress-dependent crystal structure of lanthanum strontium cobalt ferrite by in situ synchrotron X-ray diffraction

NASA Astrophysics Data System (ADS)

Geiger, Philipp T.; Khansur, Neamul H.; Riess, Kevin; Martin, Alexander; Hinterstein, Manuel; Webber, Kyle G.

2018-02-01

Lanthanum strontium cobalt ferrite La1-xSrxCo1-yFeyO3-δ (LSCF) is one of the most studied mixed ionic-electronic conductor materials due to electrical and transport properties, which are attractive for intermediate temperature solid oxide fuel cells (SOFCs), oxygen permeation membranes, and catalysis. The integration of such materials, however, depends on the thermal as well as mechanical behavior. LSCF exhibits nonlinear hysteresis during compressive stress-strain measurements, marked by a remanent strain and coercive stress, i.e., ferroelasticity. However, the origin of ferroelastic behavior has not been investigated under high compressive stress. This study, therefore, investigates the microscopic origin of stress-induced mechanical behavior in polycrystalline (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ using in situ synchrotron x-ray diffraction. The data presented here reveals that the strain response originates from the intrinsic lattice strain as well as the extrinsic domain switching strain without any apparent change in crystallographic symmetry. A comparison of the calculated microscopic strain contribution with that of a macroscopic measurement indicates a significant change in the relative contributions of intrinsic and extrinsic strain depending on the applied stress state, i.e., under maximum stress and after unloading. Direct evidence of the microscopic origin of stress-strain response outlined in this paper may assist in guiding materials design with the improved mechanical reliability of SOFCs.

Enhanced electrocaloric analysis and energy-storage performance of lanthanum modified lead titanate ceramics for potential solid-state refrigeration applications.

PubMed

Zhang, Tian-Fu; Huang, Xian-Xiong; Tang, Xin-Gui; Jiang, Yan-Ping; Liu, Qiu-Xiang; Lu, Biao; Lu, Sheng-Guo

2018-01-10

The unique properties and great variety of relaxer ferroelectrics make them highly attractive in energy-storage and solid-state refrigeration technologies. In this work, lanthanum modified lead titanate ceramics are prepared and studied. The giant electrocaloric effect in lanthanum modified lead titanate ceramics is revealed for the first time. Large refrigeration efficiency (27.4) and high adiabatic temperature change (1.67 K) are achieved by indirect analysis. Direct measurements of electrocaloric effect show that reversible adiabatic temperature change is also about 1.67 K, which exceeds many electrocaloric effect values in current direct measured electrocaloric studies. Both theoretical calculated and direct measured electrocaloric effects are in good agreements in high temperatures. Temperature and electric field related energy storage properties are also analyzed, maximum energy-storage density and energy-storage efficiency are about 0.31 J/cm 3 and 91.2%, respectively.

Electronic Conductivity of Doped-Lanthanum Gallate Electrolytes

NASA Astrophysics Data System (ADS)

Yamaji, Katsuhiko; Xiong, Yue Ping; Kishimoto, Haruo; Horita, Teruhisa; Sakai, Natsuko; Brito, Manuel E.; Yokokawa, Harumi

Electronic conductivity of doped lanthanum gallate electrolytes were determined by using a Hebb-Wagner type polarization cell. Electronic conductivity of cobalt-doped, La0.8Sr0.2Ga0.8Mg0.15Co0.5O3-δ (LSGMC), and non cobalt-doped, La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM8282), were measured as a function of oxygen partial pressures. The electronic conductivity of LSGM8282 showed a linear dependence on p(O2)1/4 in the higher p(O2) region, which is attributed to the electronic hole conductivity. The electronic conductivity of LSGMC showed a linear dependence on p(O2)1/6 in the higher p(O2) region. LSGMC has higher electronic conductivity than LSGM, and the conductivity was not clearly changed with temperatures between 600 and 800 °C. In lower p(O2) region, the electronic conductivity data have poor reproducibility and did not show any dependence on p(O2) because of the degradation of the electrolytes in severe reducing atmospheres.

Crystallization of lanthanum and yttrium aluminosilicate glasses

NASA Astrophysics Data System (ADS)

Sadiki, Najim; Coutures, Jean Pierre; Fillet, Catherine; Dussossoy, Jean Luc

2006-01-01

The crystallization behaviour of aluminosilicate glasses of lanthanum (LAS) and yttrium (YAS) containing 2-8 mol% of Ln 2O 3 (Ln = La or Y), 12-30 mol% of Al 2O 3, and 64-80 mol% of SiO 2 has been studied by DTA, XRD and SEM-EDX analysis. X-ray diffraction results indicate the presence of the mullite phase and La 2Si 2O 7 in the monoclinic high-temperature G form (group space P2 1/c) for the LAS glasses, and mullite y-Y 2Si 2O 7 in the monoclinic structure (group space C2/m) and a small amount of β-Y 2Si 2O 7 in the orthorhombic structure (space group Pna2) for the YAS. For both cases, very little tridymite phase is observed. The results also show that the values of Tg for YAS are higher than those for LAS glasses. The crystallization of LAS glasses is more difficult than that of YAS. For all samples, we observed only one kind of mullite (Al/Si = 3.14).

Effects of soil lanthanum on growth and elemental composition of plants

NASA Astrophysics Data System (ADS)

Fastovets, Ilya; Kotelnikova, Anna; Olga, Rogova; Nikolai, Sushkov; Elena, Pashkevich

2017-04-01

Effects of soil lanthanum on growth and elemental composition of plants In recent years, lanthanum (La) has been found effective in increasing crop productivity. This results in its growing application in agriculture. However, it is controversial whether lanthanum has beneficial or negative impact on plants (Kabata-Pendias, 2011). In the present study we carried out a pot experiment to understand how soil La affects barley (Hordeum vulgare L., 'Mikhaylovsky' cv.) growth and elemental composition. The pot experiment was conducted in a growbox under artificial light in sod-podzolic soil. The soil was sprayed with LaCl3 solutions to achieve the following concentrations of exogenous La: 0 (control), 10, 20, 50, 100, and 200 mg/kg. The plants were grown for 40 days in 2-litre pots, 6 plants in each pot, with 4 replications per group (24 pots total), and were irrigated with distilled water. Fresh aboveground biomass was weighed, chlorophylls α and β and carotenoids were measured in fresh leaves. Dry leaves, stems and soil were subject to atomic emission (ICP-AES) elemental analysis. Statistical computations involved simulated Kruskal-Wallis and Jonckheere-Terpstra tests as well as Gao modification of Campbell-Skillings test for nonparametric multiple comparisons. Multiple regression and correlation analyzes were also performed. All differences were considered significant at α=0.05. Our results indicate that both leaves and stems of barley readily accumulate La. Leaves accumulate up to 1.2% of soil La concentration, and significantly more La than stems. Significant accumulation of La by stems and leaves was observed in pots with La soil concentrations higher than 50 and 20 mg/kg, respectively. Plant biomass uniformly increases up to 13.5 % compared to the control, and significant increase in plant biomass was observed at concentrations 100 and 200 mg/kg La. Chlorophyll α and β and carotenoid content decrease significantly at 100 mg/kg La compared to the control group

Ionic liquid-mediated synthesis of meso-scale porous lanthanum-transition-metal perovskites with high CO oxidation performance

DOE PAGES

Lu, Hanfeng; Zhang, Pengfei; Qiao, Zhen-An; ...

2015-02-19

Lanthanum-transition-metal perovskites with robust meso-scale porous frameworks (meso-LaMO 3) are synthesized through use of ionic liquids. The resultant samples demonstrate a rather high activity for CO oxidation, by taking advantage of unique nanostructure-derived benefits. This synthesis strategy opens up a new opportunity for preparing functional mesoporous complex oxides of various compositions.

Ionic liquid-mediated synthesis of meso-scale porous lanthanum-transition-metal perovskites with high CO oxidation performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Hanfeng; Zhang, Pengfei; Qiao, Zhen-An

Lanthanum-transition-metal perovskites with robust meso-scale porous frameworks (meso-LaMO 3) are synthesized through use of ionic liquids. The resultant samples demonstrate a rather high activity for CO oxidation, by taking advantage of unique nanostructure-derived benefits. This synthesis strategy opens up a new opportunity for preparing functional mesoporous complex oxides of various compositions.

Recycling of crustal materials through study of ultrahigh-pressure minerals in collisional orogens, ophiolites, and mantle xenoliths: A review

NASA Astrophysics Data System (ADS)

Liou, Juhn G.; Tsujimori, Tatsuki; Yang, Jingsui; Zhang, R. Y.; Ernst, W. G.

2014-12-01

Newly recognized occurrences of ultrahigh-pressure (UHP) minerals including diamonds in ultrahigh-temperature (UHT) felsic granulites of orogenic belts, in chromitites associated with ophiolitic complexes, and in mantle xenoliths suggest the recycling of crustal materials through deep subduction, mantle upwelling, and return to the Earth's surface. This circulation process is supported by crust-derived mineral inclusions in deep-seated zircons, chromites, and diamonds from collision-type orogens, from eclogitic xenoliths in kimberlites, and from chromitities of several Alpine-Himalayan and Polar Ural ophiolites; some of these minerals contain low-atomic number elements typified by crustal isotopic signatures. Ophiolite-type diamonds in placer deposits and as inclusions in chromitites together with numerous highly reduced minerals and alloys appear to have formed near the mantle transition zone. In addition to ringwoodite and inferred stishovite, a number of nanometric minerals have been identified as inclusions employing state-of-the-art analytical tools. Reconstitution of now-exsolved precursor UHP phases and recognition of subtle decompression microstructures produced during exhumation reflect earlier UHP conditions. For example, Tibetan chromites containing exsolution lamellae of coesite + diopside suggest that the original chromitites formed at P > 9-10 GPa at depths of >250-300 km. The precursor phase most likely had a Ca-ferrite or a Ca-titanite structure; both are polymorphs of chromite and (at 2000 °C) would have formed at minimum pressures of P > 12.5 or 20 GPa respectively. Some podiform chromitites and host peridotites contain rare minerals of undoubted crustal origin, including zircon, feldspars, garnet, kyanite, andalusite, quartz, and rutile; the zircons possess much older U-Pb ages than the time of ophiolite formation. These UHP mineral-bearing chromitite hosts evidently had a deep-seated evolution prior to extensional mantle upwelling and partial

Boron ion beam generation utilizing lanthanum hexaboride cathodes: Comparison of vacuum arc and planar magnetron glow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikolaev, A. G.; Vizir, A. V.; Yushkov, G. Yu., E-mail: gyushkov@mail.ru

Boron ion beams are widely used for semiconductor ion implantation and for surface modification for improving the operating parameters and increasing the lifetime of machine parts and tools. For the latter application, the purity requirements of boron ion beams are not as stringent as for semiconductor technology, and a composite cathode of lanthanum hexaboride may be suitable for the production of boron ions. We have explored the use of two different approaches to boron plasma production: vacuum arc and planar high power impulse magnetron in self-sputtering mode. For the arc discharge, the boron plasma is generated at cathode spots, whereasmore » for the magnetron discharge, the main process is sputtering of cathode material. We present here the results of comparative test experiments for both kinds of discharge, aimed at determining the optimal discharge parameters for maximum yield of boron ions. For both discharges, the extracted ion beam current reaches hundreds of milliamps and the fraction of boron ions in the total extracted ion beam is as high as 80%.« less

The incorporation of plutonium in lanthanum zirconate pyrochlore

NASA Astrophysics Data System (ADS)

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

2013-11-01

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.

Lanthanum chloride impairs spatial memory through ERK/MSK1 signaling pathway of hippocampus in rats.

PubMed

Liu, Huiying; Yang, Jinghua; Liu, Qiufang; Jin, Cuihong; Wu, Shengwen; Lu, Xiaobo; Zheng, Linlin; Xi, Qi; Cai, Yuan

2014-12-01

Rare earth elements (REEs) are used in many fields for their diverse physical and chemical properties. Surveys have shown that REEs can impair learning and memory in children and cause neurobehavioral defects in animals. However, the mechanism underlying these impairments has not yet been completely elucidated. Lanthanum (La) is often selected to study the effects of REEs. The aim of this study was to investigate the spatial memory impairments induced by lanthanum chloride (LaCl3) and the probable underlying mechanism. Wistar rats were exposed to LaCl3 in drinking water at 0 % (control, 0 mM), 0.25 % (18 mM), 0.50 % (36 mM), and 1.00 % (72 mM) from birth to 2 months after weaning. LaCl3 considerably impaired the spatial learning and memory of rats in the Morris water maze test, damaged the synaptic ultrastructure and downregulated the expression of p-MEK1/2, p-ERK1/2, p-MSK1, p-CREB, c-FOS and BDNF in the hippocampus. These results indicate that LaCl3 exposure impairs the spatial learning and memory of rats, which may be attributed to disruption of the synaptic ultrastructure and inhibition of the ERK/MSK1 signaling pathway in the hippocampus.

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

PubMed

Spears, Bryan M; Lürling, Miquel; Yasseri, Said; Castro-Castellon, Ana T; Gibbs, Max; Meis, Sebastian; McDonald, Claire; McIntosh, John; Sleep, Darren; Van Oosterhout, Frank

2013-10-01

Phoslock(®) is a lanthanum (La) modified bentonite clay that is being increasingly used as a geo-engineering tool for the control of legacy phosphorus (P) release from lake bed sediments to overlying waters. This study investigates the potential for negative ecological impacts from elevated La concentrations associated with the use of Phoslock(®) across 16 case study lakes. Impact-recovery trajectories associated with total lanthanum (TLa) and filterable La (FLa) concentrations in surface and bottom waters were quantified over a period of up to 60 months following Phoslock(®) application. Both surface and bottom water TLa and FLa concentrations were <0.001 mg L(-1) in all lakes prior to the application of Phoslock(®). The effects of Phoslock(®) application were evident in the post-application maximum TLa and FLa concentrations reported for surface waters between 0.026 mg L(-1)-2.30 mg L(-1) and 0.002 mg L(-1) to 0.14 mg L(-1), respectively. Results of generalised additive modelling indicated that recovery trajectories for TLa and FLa in surface and bottom waters in lakes were represented by 2nd order decay relationships, with time, and that recovery reached an end-point between 3 and 12 months post-application. Recovery in bottom water was slower (11-12 months) than surface waters (3-8 months), most probably as a result of variation in physicochemical conditions of the receiving waters and associated effects on product settling rates and processes relating to the disturbance of bed sediments. CHEAQS PRO modelling was also undertaken on 11 of the treated lakes in order to predict concentrations of La(3+) ions and the potential for negative ecological impacts. This modelling indicated that the concentrations of La(3+) ions will be very low (<0.0004 mg L(-1)) in lakes of moderately low to high alkalinity (>0.8 mEq L(-1)), but higher (up to 0.12 mg L(-1)) in lakes characterised by very low alkalinity. The effects of elevated La(3+) concentrations following

Antiferroelectricity in lanthanum doped zirconia without metallic capping layers and post-deposition/-metallization anneals

NASA Astrophysics Data System (ADS)

Wang, Zheng; Gaskell, Anthony Arthur; Dopita, Milan; Kriegner, Dominik; Tasneem, Nujhat; Mack, Jerry; Mukherjee, Niloy; Karim, Zia; Khan, Asif Islam

2018-05-01

We report the effects of lanthanum doping/alloying on antiferroelectric (AFE) properties of ZrO2. Starting with pure ZrO2, an increase in La doping leads to the narrowing of the AFE double hysteresis loops and an increase in the critical voltage/electric field for AFE → ferroelectric transition. At higher La contents, the polarization-voltage characteristics of doped/alloyed ZrO2 resemble that of a non-linear dielectric without any discernible AFE-type hysteresis. X-ray diffraction based analysis indicates that the increased La content while preserving the non-polar, parent AFE, tetragonal P42/nmc phase leads to a decrease in tetragonality and the (nano-)crystallite size and an increase in the unit cell volume. Furthermore, antiferroelectric behavior is obtained in the as-deposited thin films without requiring any capping metallic layers and post-deposition/-metallization anneals due to which our specific atomic layer deposition system configuration crystallizes and stabilizes the AFE tetragonal phase during growth.

Ternary lanthanum sulfide selenides {alpha}-LaS{sub 2-x}Se{sub x} (0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartsch, Christian; Doert, Thomas, E-mail: thomas.doert@chemie.tu-dresden.de

2012-01-15

Mixed lanthanum sulfide selenides LaS{sub 2-x}Se{sub x} (0lanthanum chloride and alkali metal polychalcogenides. The LaS{sub 2-x}Se{sub x} compounds crystallize in space group P2{sub 1}/a, no. 14, and adopt the {alpha}-LnS{sub 2} (Ln=Y, La-Lu) structure type with a pronounced site preference for the chalcogen atoms. The mixed chalcogenides form a complete miscible series with lattice parameters a=820-849 pm, b=413-425 pm and c=822-857 pm ({beta} Almost-Equal-To 90 Degree-Sign) following Vegard's rule. Raman signals indicate the presence of mixed X{sub 2}{sup 2-} dianions, a species rarely evidenced in literature, besides the well known anionsmore » S{sub 2}{sup 2-} and Se{sub 2}{sup 2-}. The band gaps of the LaS{sub 2-x}Se{sub x} compounds, determined by optical spectroscopy, decrease nearly linearly with increasing amount of selenium. - Graphical abstract: Raman spectra and site occupancies in the structures of selected lanthanum sulfide selenides. Highlights: Black-Right-Pointing-Pointer Vegard series of mixed lanthanum sulfide selenides LaS{sub 2-x}Se{sub x} (0

Benzimidazole Based Aerogel Materials

NASA Technical Reports Server (NTRS)

Rhine, Wendell E. (Inventor); Mihalcik, David (Inventor)

2016-01-01

The present invention provides aerogel materials based on imidazoles and polyimidazoles. The polyimidazole based aerogel materials can be thermally stable up to 500 C or more, and can be carbonized to produce a carbon aerogel having a char yield of 60% or more, specifically 70% or more. The present invention also provides methods of producing polyimidazole based aerogel materials by reacting at least one monomer in a suitable solvent to form a polybenzimidazole gel precursor solution, casting the polybenzimidazole gel precursor solution into a fiber reinforcement phase, allowing the at least one gel precursor in the precursor solution to transition into a gel material, and drying the gel materials to remove at least a portion of the solvent, to obtain an polybenzimidazole-based aerogel material.

LDEF materials data bases

NASA Technical Reports Server (NTRS)

Funk, Joan G.; Strickland, John W.; Davis, John M.

1993-01-01

The Long Duration Exposure Facility (LDEF) and the accompanying experiments were composed of and contained a wide variety of materials representing the largest collection of materials flown in low Earth orbit (LEO) and retrieved for ground based analysis to date. The results and implications of the mechanical, thermal, optical, and electrical data from these materials are the foundation on which future LEO space missions will be built. The LDEF Materials Special Investigation Group (MSIG) has been charged with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the spacecraft user community in an easily accessed, user-friendly form. This paper discusses the format and content of the three data bases developed or being developed to accomplish this task. The hardware and software requirements for each of these three data bases are discussed along with current availability of the data bases. This paper also serves as a user's guide to the MAPTIS LDEF Materials Data Base.

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior.

PubMed

Zhang, Da-Lei; Zhang, Mei-Yi; Zhang, Chu-Hui; Sun, Ying-Jie; Sun, Xiao; Yuan, Xian-Zheng

2016-03-15

The pyrolysis treatment with biomass is a promising technology for the remediation of chromite-ore-processing residue (COPR). However, the mechanism of this process is still unclear. In this study, the behavior of pyrolysis reduction of Cr(VI) by cellulose, the main component of biomass, was elucidated. The results showed that the volatile fraction (VF) of cellulose, ie. gas and tar, was responsible for Cr(VI) reduction. All organic compounds, as well as CO and H2 in VF, potentially reduced Cr(VI). X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine-structure (EXAFS) spectroscopy confirmed the reduction of Cr(VI) to Cr(III) and the formation of amorphous Cr2O3. The remnant Cr(VI) content in COPR can be reduced below the detection limit (2 mg/kg) by the reduction of COPR particle and extension of reaction time between VF and COPR. This study provided a deep insight on the co-pyrolysis of cellulose with Cr(VI) in COPR and an ideal approach by which to characterize and optimize the pyrolysis treatment for COPR by other organics.

Grain Boundary Engineering of Lithium-Ion-Conducting Lithium Lanthanum Titanate for Lithium-Air Batteries

DTIC Science & Technology

2015-01-01

Tojo T, Sakurai Y. Synthesis and lithium - ion conductivity for perovskite-type Li3/8Sr7/16Ta3/4Zr1/4O3 solid electrolyte by powder-bed sintering...battery performance is limited by the electrolytic membrane, which needs high Li-ionic conductivity. Lithium lanthanum titanate (Li3xLa(2/3)-xTiO3, or...of the A-site ions and lithium ion conductivity in the perovskite solid solution La0.67-xLi3xTiO3 (x=0.11). Journal of Solid State Ionics. 1999;121

Methanol synthesis using a catalyst combination of alkali or alkaline earth salts and reduced copper chromite for methanol synthesis

DOEpatents

Tierney, John W.; Wender, Irving; Palekar, Vishwesh M.

1993-01-01

The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a catalyst combination comprising reduced copper chromite and basic alkali salts or alkaline earth salts. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100.degree.-160.degree. C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H.sub.2 /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

Advanced Sensor Arrays and Packaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryter, John Wesley; Romero, Christopher J.; Ramaiyan, Kannan

2016-08-11

Novel sensor packaging elements were designed, fabricated, and tested in order to facilitate the transition of electrochemical mixed-potential sensors toward commercialization. Of the two designs completed, the first is currently undergoing field trials, taking direct measurements within vehicle exhaust streams, while the second is undergoing preliminary laboratory testing. The sensors’ optimal operating conditions, sensitivity to hydrogen, and long-­term baseline stability were also investigated. The sensing capabilities of lanthanum chromite (La 0.8Sr 0.2CrO 3) and indium-­doped tin oxide (ITO) working electrodes were compared, and the ITO devices were selected for pre-­commercial field trials testing at a hydrogen fuel cell vehicle fuelingmore » station in California. Previous data from that fueling station were also analyzed, and the causes of anomalous baseline drift were identified.« less

THORIUM OXALATE-URANYL ACETATE COUPLED PROCEDURE FOR THE SEPARATION OF RADIOACTIVE MATERIALS

DOEpatents

Gofman, J.W.

1959-08-11

The recovery of fission products from neutronirradiated uranium is described. The neutron-irradiated uranium is dissolved in acid and thorium oxalate is precipitated in ihe solution formed, whereby the fission products are carried on the thorium oxalate. The separated thorium oxalate precipitate is then dissolved in an aqueous oxalate solution and the solution formed is acidified, limiting ihe excess acidity to a maximum of 2 N, whereby thorium oxalate precipitates and carries lanthanum-rareearth- and alkaline-earth-metal fission products while the zirconium-fission-product remains in solution. This precipitate, too, is dissolved in an aqaeous oxalate solution at elevated temperature, and lanthanum-rare-earth ions are added to the solution whereby lanthanum-rare-earth oxalate forms and the lanthanum-rare-earth-type and alkalineearth-metal-type fission products are carried on the oxalate. The precipitate is separated from the solution.

Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

PubMed

Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

2015-01-01

Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis and characterization of UV-treated Fe-doped bismuth lanthanum titanate-doped TiO2 layers in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Song, Myoung Geun; Bark, Chung Wung

2016-06-01

Dye-sensitized solar cells (DSSCs) based on titanium dioxide (TiO2) have been extensively studied because they constitute promising low-cost alternatives to their conventional semiconductor-based counterparts. However, much of the effort aimed at achieving high conversion efficiencies has focused on dye and liquid electrolytes. In this work, we report the photovoltaic characteristics of DSSCs fabricated by mixing TiO2 with Fe-doped bismuth lanthanum titanate (Fe-BLT). These nanosized Fe-BLT powders were prepared by using a high-energy ball-milling process. In addition, we used a UV radiation-ozone (UV-O3) treatment to change the surface wettability of TiO2 from hydrophobic to hydrophilic and thereby prevented the easy separation of the Fe-BLT-mixed TiO2 from the fluorine-doped tin-oxide (FTO) coating glass.

Structural Characterization of Methanol Substituted Lanthanum Halides

PubMed Central

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

2010-01-01

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

Intrinsic Studies of Materials.

DTIC Science & Technology

RELAXATION TIME , CRYSTAL LATTICES), (*RARE EARTH ELEMENTS, *ELECTRON TRANSITIONS), (*CRYSTAL DEFECTS, INTERACTIONS), EXCITATION, DOPING, LANTHANUM COMPOUNDS, PHONONS, ATOMIC ENERGY LEVELS, HOLMIUM, CHLORIDES, PRASEODYMIUM

Graphene-based smart materials

NASA Astrophysics Data System (ADS)

Yu, Xiaowen; Cheng, Huhu; Zhang, Miao; Zhao, Yang; Qu, Liangti; Shi, Gaoquan

2017-09-01

The high specific surface area and the excellent mechanical, electrical, optical and thermal properties of graphene make it an attractive component for high-performance stimuli-responsive or 'smart' materials. Complementary to these inherent properties, functionalization or hybridization can substantially improve the performance of these materials. Typical graphene-based smart materials include mechanically exfoliated perfect graphene, chemical vapour deposited high-quality graphene, chemically modified graphene (for example, graphene oxide and reduced graphene oxide) and their macroscopic assemblies or composites. These materials are sensitive to a range of stimuli, including gas molecules or biomolecules, pH value, mechanical strain, electrical field, and thermal or optical excitation. In this Review, we outline different graphene-based smart materials and their potential applications in actuators, chemical or strain sensors, self-healing materials, photothermal therapy and controlled drug delivery. We also introduce the working mechanisms of graphene-based smart materials and discuss the challenges facing the realization of their practical applications.

A microporous lanthanum metal-organic framework as a bi-functional chemosensor for the detection of picric acid and Fe(3+) ions.

PubMed

Zhang, Chuanqi; Yan, Yan; Pan, Qinhe; Sun, Libo; He, Hongming; Liu, Yunling; Liang, Zhiqiang; Li, Jiyang

2015-08-07

A microporous lanthanum metal-organic framework [La(TPT)(DMSO)2]·H2O (La-MOF ()), has been synthesized using a rigid unsymmetrical tricarboxylate ligand of p-terphenyl-3,4'',5-tricarboxylic acid (H3TPT). The structure of is constructed by bi-nuclear lanthanum clusters and fully deprotonated TPT(3-) ligands, which can be simplified into a 3,6-connected flu-3,6-C2/c topology with a point symbol of (4(4)·6)2(4·6(2)·8(7)·10(2)). The π-electron rich ligand H3TPT enables to have blue luminescence when excited at 342 nm at ambient temperature. Meanwhile, exhibits the selective detection of picric acid (PA) and Fe(3+) ions in ethanol solution over other nitroaromatic compounds and metal ions. The high quenching efficiency and selectivity of makes it a potential bi-functional chemosensor for both PA and Fe(3+) ions.

Superconductivity of lanthanum revisited: enhanced critical temperature in the clean limit.

PubMed

Löptien, P; Zhou, L; Khajetoorians, A A; Wiebe, J; Wiesendanger, R

2014-10-22

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.

Superconductivity of lanthanum revisited: enhanced critical temperature in the clean limit

NASA Astrophysics Data System (ADS)

Löptien, P.; Zhou, L.; Khajetoorians, A. A.; Wiebe, J.; Wiesendanger, R.

2014-10-01

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.

Effect of ‘A’-site non stoichiometry in strontium doped lanthanum ferrite based solid oxide fuel cell cathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, Koyel; Mukhopadhyay, Jayanta, E-mail: jayanta_mu@cgcri.res.in; Barman, Madhurima

2015-12-15

Highlights: • La{sub 1−x}Sr{sub x}Co{sub y}Fe{sub 1−y}O{sub 3−δ}, x = 0.4; y = 0.2 system varying La-site (0.6–0.54) are studied. • Combustion synthesis technique is used to prepare the powder samples. • Highest electrical conductivity observed with largest A-site deficit composition. • Lowest cathode polarization is found with the same composition (0.02 Ω cm{sup 2}). • Composition with largest A-site deficiency exhibits best performance (2.84 A cm{sup −2}). - Abstract: Effect of A-site non-stoichiometry in strontium doped lanthanum cobalt ferrite (La{sub 1−x}Sr{sub x}Co{sub y}Fe{sub 1−y}O{sub 3−δ}, x = 0.4; y = 0.2) is studied in a systematic manner with variationmore » of ‘A’ site stoichiometry from 1 to 0.94. The perovskite based cathode compositions are synthesized by combustion synthesis. Powder characterizations reveal rhombohedral crystal structure with crystallite size ranging from 29 to 34 nm with minimum lattice spacing of 0.271 nm. Detailed sintering studies along with total DC electrical conductivities are evaluated in the bulk form with variation of sintering temperatures. The electrode polarizations are measured in the symmetric cell configuration by impedance spectroscopy which is found to be the lowest (0.02 Ω cm{sup 2} at 800 °C) for cathode having highest degree of ‘A’-site deficiency. The same cathode composition exhibits a current density of 2.84 A cm{sup −2} (at 0.7 V, 800 °C) in anode-supported single cell. An attempt has been made to correlate the trend of electrical behaviour with increasing ‘A’-site deficiency for such cathode compositions.« less

Hydrothermal synthesis of doped lanthanum zirconate nanomaterials and the effect of V–Ge substitution on their structural, electrical and dielectric properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farid, Muhammad Asim; Asghar, Muhammad Adnan; Ashiq, Muhammad Naeem, E-mail: naeemashiqqau@yahoo.com

2014-11-15

Graphical abstract: Variation of dielectric constant with frequency for all the synthesized materials. - Highlights: • Hydrothermal method has been successfully employed to synthesize the zirconates. • XRD confirmed the formation of required phase. • Increased electrical resistivity makes these materials useful for microwave devices. • Dielectric parameters of zirconates decrease with increasing frequency. • Dielectric constant decreases with increasing substituents concentration. - Abstract: A hydrothermal method was successfully employed for the synthesis of a series of vanadium and germanium co-doped pyrochlore lanthanum zirconates with composition La{sub 2−x}V{sub x}Zr{sub 2−y}Ge{sub y}O{sub 7} (where x, y = 0.0, 0.25, 0.50, 0.75more » and 1.0). The XRD and FTIR analyses confirmed the formation of single phase except vanadium and germanium substituted samples and the crystallite sizes are in the range of 7–31 nm for V{sup 3+}–Ge{sup 4+} substituted samples. The theoretical compositions are confirmed by the ED-XRF studies. The room temperature electrical resistivity increase with the substituents concentration which suggests that the synthesized materials can be used for microwave devices as such devices required highly resistive materials. Dielectric properties were measured in the frequency range of 6 kHz to 1 MHz. The dielectric parameters decrease with increase in frequency. The DC resistivity data is in good agreement with the dielectric data.« less

Grain boundary stability and influence on ionic conductivity in a disordered perovskite -- a first-principles investigation of lithium lanthanum titanate

DOE PAGES

Alexander, Kathleen C.; Ganesh, P.; Chi, Miaofang; ...

2016-12-01

The origin of ionic conductivity in bulk lithium lanthanum titanate, a promising solid electrolyte for Li-ion batteries, has long been under debate, with experiments showing lower conductivity than predictions. Recent microscopy images show Type I and Type II grain boundaries. Using first-principles based calculations we find that experimentally observed Type I boundaries are more stable compared to the Type II grain boundaries, consistent with their observed relative abundance. Grain boundary stability appears to strongly anti-correlate with the field strength as well as the spatial extent of the space charge region. Ion migration is faster along Type II grain boundaries thanmore » across, consistent with recent experiments of increased conductivity when Type II densities were increased.« less

Vanadium based materials as electrode materials for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Yan, Yan; Li, Bing; Guo, Wei; Pang, Huan; Xue, Huaiguo

2016-10-01

As a kind of supercapacitors, pseudocapacitors have attracted wide attention in recent years. The capacitance of the electrochemical capacitors based on pseudocapacitance arises mainly from redox reactions between electrolytes and active materials. These materials usually have several oxidation states for oxidation and reduction. Many research teams have focused on the development of an alternative material for electrochemical capacitors. Many transition metal oxides have been shown to be suitable as electrode materials of electrochemical capacitors. Among them, vanadium based materials are being developed for this purpose. Vanadium based materials are known as one of the best active materials for high power/energy density electrochemical capacitors due to its outstanding specific capacitance and long cycle life, high conductivity and good electrochemical reversibility. There are different kinds of synthetic methods such as sol-gel hydrothermal/solvothermal method, template method, electrospinning method, atomic layer deposition, and electrodeposition method that have been successfully applied to prepare vanadium based electrode materials. In our review, we give an overall summary and evaluation of the recent progress in the research of vanadium based materials for electrochemical capacitors that include synthesis methods, the electrochemical performances of the electrode materials and the devices.

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

NASA Astrophysics Data System (ADS)

Raghvendra; Singh, Rajesh Kumar; Singh, Prabhakar

2014-09-01

One of the promising electrolyte materials for solid oxide fuel cells application, Sr- and Mg-doped lanthanum gallate La0.9Sr0.1Ga0.8Mg0.2O3-δ (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.

Simultaneous removal of ammonium and phosphate by alkaline-activated and lanthanum-impregnated zeolite.

PubMed

He, Yinhai; Lin, Hai; Dong, Yingbo; Liu, Quanli; Wang, Liang

2016-12-01

Simultaneous ammonium and phosphate removal characteristics and mechanism, as well as the major influencing factors, such as pH, temperature and co-existing ions, onto NaOH-activated and lanthanum-impregnated zeolite (NLZ) were investigated. The phosphate adsorption increases from 0.2 mg g -1 for natural zeolite up to 8.96 mg g -1 for NLZ, while only a slight decrease on the ammonium adsorption capacity from 23.9 mg g -1 for NaOH-activated zeolite to 21.2 mg g -1 for NLZ was observed. The ammonium and phosphate adsorption showed little pH dependence in the range from pH 3 to 7, while it decreased sharply with the pH increased above pH 7. Adsorption of ammonium and phosphate could be well described by the pseudo-second-order model and the process was mainly governed by intra-particle diffusion. The Langmuir and Freundlich model can be acceptably applied to fit the experimental data, which suggested that adsorption was caused by both the monolayer and homogeneous coverage at specific and equal affinity sites available NLZ. The underlying mechanism for the specific adsorption of phosphate by NLZ was revealed with the aid of SEM-EDS, XPS, and FTIR analysis, and the formation of (LaO)(OH)PO 2 was verified to be the dominant pathway for selective phosphate adsorption by lanthanum-impregnated zeolite. While the removal mechanism of ammonium could be well interpreted by SEM-EDS, FTIR and ICP analysis, and ion-exchange was expected to be the main removal process for ammonium. The results indicate that NLZ could efficiently and simultaneously remove low concentration of ammonium and phosphate from contaminated waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of Lanthanum Doping on the Structural and Optical Properties of Hematite Nanopowders

NASA Astrophysics Data System (ADS)

Justus, J. Sharmila; Dharma Roy, S. Dawn; Raj, A. Moses Ezhil

2016-10-01

Rare-earth elements are an attractive class of dopant elements, as they give easily trivalent cations that possibly altering the structure and other properties of the parent nanoparticles and creating multifunctional materials because of their f-electronic configurations. Herein, experimental evidence has been given for a better understanding of the factors that dictate the interactions of La doping on the structure and optical properties of iron oxide nanoparticles. For that, lanthanum doped hematite (α-Fe2O3) nanoparticles were prepared by a facile solution method using iron (III) chloride (FeCl3) as starting precursor and sodium hydroxide (NaOH) as reducing agent without templates at low temperature. As-prepared powders were subsequently calcined in air for 3 hr at 800 °C. Xray diffraction (XRD) technique was used to study the nanocrystal formation of α-Fe2O3 and Fourier Transform Raman (FT-Raman) spectral information identified the chemical bond structure of the nanoparticles. Morphology study of the nanoparticles was identified using Scanning Electron Microscope (SEM) and the incorporated La content was recognized from the Energy Dispersive X-ray Spectroscopy (EDS) analysis. The optical absorption spectrum was recorded in the wavelength range of 200-2000 nm and the optical parameters such as absorption coefficient and optical band gap energy of pure and doped Fe2O3 nanoparticles were determined. Obtained results are interpreted by considering the impregnation of trivalent La cations that replaced Fe cations of the host structure.

Mobilization of Cr(VI) from chromite ore processing residue through acid treatment.

PubMed

Tinjum, James M; Benson, Craig H; Edil, Tuncer B

2008-02-25

Batch leaching studies on chromite ore processing residue (COPR) were performed using acids to investigate leaching of hexavalent chromium, Cr(VI), with respect to particle size, reaction time, and type of acid (HNO(3) and H(2)SO(4)). Aqueous Cr(VI) is maximized at approximately 0.04 mol Cr(VI) per kg of dry COPR at pH 7.6-8.1. Cr(VI) mobilized more slowly for larger particles, and the pH increased with time and increased more rapidly for smaller particles, suggesting that rate limitations occur in the solid phase. With H(2)SO(4), the pH stabilized at a higher value (8.8 for H(2)SO(4) vs. 8.0 for HNO(3)) and more rapidly (16 h vs. 30 h), and the differences in pH for different particle sizes were smaller. The acid neutralization capacity (ANC) of COPR is very large (8 mol HNO(3) per kg of dry COPR for a stable eluate pH of 7.5). Changes to the elemental and mineralogical composition and distribution in COPR particles after mixing with acid indicate that Cr(VI)-bearing solids dissolved. However, concentrations of Cr(VI) >2800 mg kg(-1) (>50% of the pre-treatment concentration) were still found after mixing with acid, regardless of the particle size, reaction time, or type of acid used. The residual Cr(VI) appears to be partially associated with poorly-ordered Fe and Al oxyhydroxides that precipitated in the interstitial areas of COPR particles. Remediation strategies that use HNO(3) or H(2)SO(4) to neutralize COPR or to maximize Cr(VI) in solution are likely to require extensive amounts of acid, may not mobilize all of the Cr(VI), and may require extended contact time, even under well-mixed conditions.

Accumulation, elimination and neuro-oxidative damage under lanthanum exposure in glass eels (Anguilla anguilla).

PubMed

Figueiredo, Cátia; Grilo, Tiago F; Lopes, Clara; Brito, Pedro; Diniz, Mário; Caetano, Miguel; Rosa, Rui; Raimundo, Joana

2018-05-07

Rare earth elements (REEs) comprise elements from lanthanum to lutetium that together with yttrium and scandium are emergent contaminants of critical importance for numerous groundbreaking environmental technologies. Transfer to aquatic ecosystems is expected to increase, however, little information is known about their potential impacts in marine biota. Considering the endangered conservation status of the European eel (Anguilla anguilla) and the vulnerability of early fish life stages to contaminants, we exposed glass eels, through water, to an environmentally relevant concentration (120 ng.L - 1 ) of lanthanum (La) for 7 days (plus 7 days of depuration). The aim was to study the accumulation and elimination of La in eel's body and subsequent quantification of acetylcholinesterase (AchE), lipid peroxidation and antioxidant enzymatic machinery. Accumulation peaked after 72 h-exposure to La, decreasing afterwards, even in continuous exposure. Accumulation was higher in the viscera, followed by the skinless body and ultimately in the head, possibly as a protective mechanism to cope with La neurotoxicity. A significant increase in AChE activity was observed in La-exposed glass eels, suggesting that La 3+ may inhibit the binding of acetylcholine. A depression in lipid peroxidation was registered under La exposure, possibly indicating that La 3+ may play physiological activities and functions as a free radical scavenger. Catalase activity was significantly inhibited in La-exposed glass eels after 72 h, indicating that the availability of La may induce physiological impairment. The quantification of Glutathione S-Transferase activity revealed no differences between control and La-exposed organisms. Further investigation is needed towards understanding the biological effects of REEs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrochemical Investigation of DA and UA on Carboxylated Graphene Oxide/lanthanum Electrodes with Sundry Content of Ctab

NASA Astrophysics Data System (ADS)

Jiang, J.; Zhu, L.; Qian, W.; Chen, H.; Feng, C.; Han, S.; Lin, H.; Ye, F. Y.

Glassy carbon electrodes (GCE) were modified by carboxylated graphene oxide/lanthanum with various concentrations of hexadecyl trimethyl ammonium bromide (CTAB), and the treated electrodes, called CTAB/GO-COOLa/GCE, were prepared for the detection of uric acid (UA) and dopamine (DA) by using the differential pulse voltammetry (DPV) and the cyclic voltammetry (CV). The results show that the modified electrode’s electrocatalytic activity could be affected by several factors in the examination, they are the pH value of the system, the main content of CTAB, various concentrations and rates of scan. With a combination of carboxylated graphene oxide/lanthanum and CTAB, the resulted CTAB/GO-COOLa/GCE sensors showed preeminent selectivity and obvious catalytic property toward the electro-oxidation of UA and DA. In optimized conditions, the response of the CTAB/GO-COOLa/GCE electrode for DA was linear in the region of 0.03-500.0μM with detection limits of 0.036μM (S/N=3). Two linear response ranges for the determination UA were obtained from ranges of 1 to 200μM and 200 to 1300μM with a detection limit of 0.42μM (S/N=3). Moreover, the refined electrode was used in the inspection of DA and UA in real samples of serum and urine successfully, displaying its potential application of real samples involved in electroanalysis.

Electron-microprobe study of chromitites associated with alpine ultramafic complexes and some genetic implications

USGS Publications Warehouse

Bird, M.L.

1978-01-01

Electron-microprobe and petrographic studies of alpine chromite deposits from around the world demonstrate that they are bimodal with respect to the chromic oxide content of their chromite. The two modes occur at 54 ? 4 and 37 ? 3 weight per cent chromic oxide corresponding to chromite designated as high-chromium and high-aluminum chromite respectively. The high-chromium chromite occurs exclusively with highly magnesian olivine (Fo92-97) and some interstitial diopside. The high-aluminum chromite is associated with more ferrous olivine (Fo88-92), diopside, enstatite, and feldspar. The plot of the mole ratios Cr/(Cr+Al+Fe3+) vs. Mg/(Mg+Fe2+) usually presented for alpine chromite is shown to have a high-chromium, high-iron to low-chromium, low-iron trend contrary to that shown by stratiform chromite. This trend is characteristic of alpine type chromite and is termed the alpine trend. However, a trend similar to that for startiform chromite is discernable on the graph for the high-chromium chromite data. This latter trend is well-developed at Red Mountain, Seldovia, Alaska. Analysis of the iron-magnesium distribution coefficient, Kd=(Fe/Mg)ol/(Fe/Mg)ch, between olivine and chromite shows that Kd for the high-chromium chromite from all ultramafic complexes has essentially the same constant value of .05 while the distribution coefficient for the high-aluminum chromite varies with composition of the chromite. These distribution coefficients are also characteristic of alpine-type chromites. The constant value for Kd for the high-chromium chromite and associated high-magnesium olivine in all alpine complexes suggests that they all crystallized under similar physico-chemical conditions. The two types of massive chromite and their associations of silicate minerals suggest the possibility of two populations with different origins. Recrystallization textures associated with the high-aluminum chromite together with field relationships between the gabbro and the chromite pods

Materials And Processes Technical Information System (MAPTIS) LDEF materials data base

NASA Technical Reports Server (NTRS)

Funk, Joan G.; Strickland, John W.; Davis, John M.

1993-01-01

A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated from LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux) and author(s) or principal investigator(s). Tne LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which has been computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. The LDEF Materials Data Base is described and step-by-step example searches using the data base are included. Information on how to become an authorized user of the system is included.

Editors' Choice—Field Trials Testing of Mixed Potential Electrochemical Hydrogen Safety Sensors at Commercial California Hydrogen Filling Stations

DOE PAGES

Brosha, Eric Lanich; Romero, Christopher Jesse; Poppe, Daniel; ...

2017-10-27

Hydrogen safety sensors must meet specific performance requirements, mandated by the U.S. Department of Energy, for hydrogen fueling station monitoring. Here, we describe the long-term performance of two zirconia-based mixed potential electrochemical hydrogen gas sensors, developed specifically with a high sensitivity to hydrogen, low cross-sensitivity, and fast response time. Over a two-year period, sensors with tin-doped indium oxide and strontium doped lanthanum chromite electrodes were deployed at two stations in four field trials tests conducted in Los Angeles. The sensors documented the existence of hydrogen plumes ranging in concentration from 100 to as high as 2700 ppm in the areamore » surrounding the dispenser, consistent with depressurization from 700 bar following vehicle refueling. As expected, the hydrogen concentration reported by the mixed potential sensors was influenced by wind direction. Baseline stability testing at a Chino, CA station showed no measureable baseline drift throughout 206 days of uninterrupted data acquisition. The high baseline stability, excellent correlation with logged fueling/depressurization events, and absence of false alarms suggest that the zirconia-based mixed potential sensor platform is a good candidate for protecting hydrogen infrastructure where frequent calibrations or sensor replacement to reduce the false alarm frequency have been shown to be cost prohibitive.« less

Editors' Choice—Field Trials Testing of Mixed Potential Electrochemical Hydrogen Safety Sensors at Commercial California Hydrogen Filling Stations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brosha, Eric Lanich; Romero, Christopher Jesse; Poppe, Daniel

Hydrogen safety sensors must meet specific performance requirements, mandated by the U.S. Department of Energy, for hydrogen fueling station monitoring. Here, we describe the long-term performance of two zirconia-based mixed potential electrochemical hydrogen gas sensors, developed specifically with a high sensitivity to hydrogen, low cross-sensitivity, and fast response time. Over a two-year period, sensors with tin-doped indium oxide and strontium doped lanthanum chromite electrodes were deployed at two stations in four field trials tests conducted in Los Angeles. The sensors documented the existence of hydrogen plumes ranging in concentration from 100 to as high as 2700 ppm in the areamore » surrounding the dispenser, consistent with depressurization from 700 bar following vehicle refueling. As expected, the hydrogen concentration reported by the mixed potential sensors was influenced by wind direction. Baseline stability testing at a Chino, CA station showed no measureable baseline drift throughout 206 days of uninterrupted data acquisition. The high baseline stability, excellent correlation with logged fueling/depressurization events, and absence of false alarms suggest that the zirconia-based mixed potential sensor platform is a good candidate for protecting hydrogen infrastructure where frequent calibrations or sensor replacement to reduce the false alarm frequency have been shown to be cost prohibitive.« less

Oral supplementation of Lanthanum Zirconate nanoparticles moderately affected behavior but drastically disturbed leukocyte count, serum cholesterol levels and antioxidant parameters from vital organs of albino mice in a gender specific manner.

PubMed

Aftab, Muhammad Nazar; Akram, Irum Naz; Khosa, Tafheem; Zahra, Syeda Qandeel; Bashir, Irum; Ashiq, Muhammad Naeem; Iqbal, Furhan

2018-05-21

Lanthanum Zirconate nanoparticles (NPs) are used in blades of gas turbine engines to thermally insulate them and to protect them against hot and corrosive gas streams. However, the information regarding their biocompatibility is limited. The present study was aimed to report the effect of Lanthanum Zirconate NPs on selected aspects of behavior, serum biochemistry, complete blood count and antioxidant parameters from vital organs of albino mice in a gender specific manner. Albino mice, seven weeks old, were orally treated with 75 mg/ml solvent/Kg body weight of Lanthanum Zirconate nanoparticles for consecutive 22 days. Saline treated control groups were maintained in parallel. It was observed that rearing frequency was significantly decreased (P = 0.01) in NPs treated male mice. Complete blood count analysis indicated that NPs treated female mice had significantly reduced white blood cells (P = 0.05) and lymphocytes count (P = 0.03). NPs treated male had significantly reduced serum cholesterol levels (P = 0.05) than control group. It was observed that Superoxide dismutase concentrations in liver (P = 0.025) and kidney (P = 0.008), Malondialdehyde concentrations in liver (P = 0.044) of female and Malondialdehyde concentrations in kidney (P < 0.001) and brain (P < 0.001) and catalase concentrations in liver (P = 0.05) of NPs treated male mice were significantly higher than their respective control groups.. In conclusion, we are reporting that oral supplementation with 75 mg/ml solvent/Kg body weight of Lanthanum Zirconate nanoparticles can affect the behavior, leukocyte count, serum cholesterol and antioxidant metabolites from vital organs of albino mice in a gender specific manner.

Phytotoxic Effects of Lanthanum Oxide Nanoparticles on Maize (Zea mays L.)

NASA Astrophysics Data System (ADS)

Liu, Yinglin; Xu, Lina; Dai, Yanhui

2018-02-01

The use of lanthanum oxide nanoparticles (La2O3 NPs) in life products have increased dramatically in the past decades, which are inevitable released into natural environment. In this study, we determined the phytotoxicity of La2O3 NPs to maize (Zea mays L.) grown in one-fourth strength Hoagland solution. After being exposed for two weeks, the biomass, roots length and the relative chlorophyll content were measured. La2O3 NPs had phytotoxicity to maize at 5 mg/L. La2O3 NPs decreased shoot biomass (≥10 mg/L), the root biomass and length (≥5 mg/L). Moreover, La2O3 NPs had adverse effects on the chlorophyll content (≥10 mg/L). The decreased chlorophyll content may reduce net photosynthetic rate. This research offers vital information about the phytotoxicity of La2O3 NPs.

EPR-based material modelling of soils

NASA Astrophysics Data System (ADS)

Faramarzi, Asaad; Alani, Amir M.

2013-04-01

In the past few decades, as a result of the rapid developments in computational software and hardware, alternative computer aided pattern recognition approaches have been introduced to modelling many engineering problems, including constitutive modelling of materials. The main idea behind pattern recognition systems is that they learn adaptively from experience and extract various discriminants, each appropriate for its purpose. In this work an approach is presented for developing material models for soils based on evolutionary polynomial regression (EPR). EPR is a recently developed hybrid data mining technique that searches for structured mathematical equations (representing the behaviour of a system) using genetic algorithm and the least squares method. Stress-strain data from triaxial tests are used to train and develop EPR-based material models for soil. The developed models are compared with some of the well-known conventional material models and it is shown that EPR-based models can provide a better prediction for the behaviour of soils. The main benefits of using EPR-based material models are that it provides a unified approach to constitutive modelling of all materials (i.e., all aspects of material behaviour can be implemented within a unified environment of an EPR model); it does not require any arbitrary choice of constitutive (mathematical) models. In EPR-based material models there are no material parameters to be identified. As the model is trained directly from experimental data therefore, EPR-based material models are the shortest route from experimental research (data) to numerical modelling. Another advantage of EPR-based constitutive model is that as more experimental data become available, the quality of the EPR prediction can be improved by learning from the additional data, and therefore, the EPR model can become more effective and robust. The developed EPR-based material models can be incorporated in finite element (FE) analysis.

The feasibility of in vivo detection of lanthanum using a 241Am K x-ray fluorescence system.

PubMed

Nguyen, Joanna; Keldani, Zaid; Da Silva, Eric; Pejović-Milić, Ana; Gräfe, James L

2017-08-21

Lanthanum (La) is commonly used in phosphate binders in the form of lanthanum carbonate in patients with end-stage kidney disease undergoing hemodialysis treatments. With this administration, there is the potential for La storage in the body with bone being the main site of concern. However, the long-term effects of residual La in the body on bone health are not yet known. In this work, we investigate the feasibility of using a K x-ray fluorescence (K-XRF) spectroscopy system to measure bone La in vivo. A series of hydroxyapatite (HAp) bone mineral phantoms were created to represent human bone. A 1.09 GBq 241 Am source was used to excite the HAp phantoms doped with various known concentrations of La placed in a 90° geometry relative to the photon source and high-purity germanium (HPGe) detector. For a detector live time of 2000 s, the minimum detection limit was calculated to be 1.7 µg La g -1 Ca or 0.7 µg La g -1 HAp and is comparable to previously reported in vivo bone La concentrations. The technique developed in this study shows promising results and provides an alternative method to invasive biopsy sampling techniques to monitor the accumulation of bone La. To the best of our knowledge, this is the first reported work that seeks to non-invasively measure bone La via in vivo XRF.

Mineral resource of the month: Chromium

USGS Publications Warehouse

Schulte, Ruth

2018-01-01

Although chromium is a metal, it does not occur naturally in metallic form. Chromium can be found in many minerals, but the only economically significant chromium-bearing mineral is chromite. Chromite has been mined from four different deposit types: stratiform chromite, podiform chromite, placer chromite, and laterite deposits. Most of the world's resources, however, are located in stratiform chromite deposits, such as the Bushveld Complex in South Africa. The economic potential of chromite resources depends on the thickness and continuity of the deposit and on the grade of the ore. Many of the major stratiform chromite deposits also contain economic levels of platinum, paladium, rhodium, osmium, iridium, and ruthenium.

New Materials for Smart Structures: a US: Japan Global Initiative

DTIC Science & Technology

2004-03-01

realization of the MPB in the Gallate:Scandate system and in the modified bismuth lanthanum ferrate lead titanate systems. A major puzzle in BiFeO3 which has...magnetization. A new major clue as to the origin of the high switchable polarization is provided by our most recent work on the modified bismuth lanthanum ...ferrate: gallate solid solutions with MPBs. In suitable composition switchability is only possible with limited electrode in a larger disk, and the fully

Biogenic nano-magnetite and nano-zero valent iron treatment of alkaline Cr(VI) leachate and chromite ore processing residue

PubMed Central

Watts, Mathew P.; Coker, Victoria S.; Parry, Stephen A.; Pattrick, Richard A.D.; Thomas, Russell A.P.; Kalin, Robert; Lloyd, Jonathan R.

2015-01-01

Highly reactive nano-scale biogenic magnetite (BnM), synthesized by the Fe(III)-reducing bacterium Geobacter sulfurreducens, was tested for the potential to remediate alkaline Cr(VI) contaminated waters associated with chromite ore processing residue (COPR). The performance of this biomaterial, targeting aqueous Cr(VI) removal, was compared to a synthetic alternative, nano-scale zero valent iron (nZVI). Samples of highly contaminated alkaline groundwater and COPR solid waste were obtained from a contaminated site in Glasgow, UK. During batch reactivity tests, Cr(VI) removal from groundwater was inhibited by ∼25% (BnM) and ∼50% (nZVI) when compared to the treatment of less chemically complex model pH 12 Cr(VI) solutions. In both the model Cr(VI) solutions and contaminated groundwater experiments the surface of the nanoparticles became passivated, preventing complete coupling of their available electrons to Cr(VI) reduction. To investigate this process, the surfaces of the reacted samples were analyzed by TEM-EDX, XAS and XPS, confirming Cr(VI) reduction to the less soluble Cr(III) on the nanoparticle surface. In groundwater reacted samples the presence of Ca, Si and S was also noted on the surface of the nanoparticles, and is likely responsible for earlier onset of passivation. Treatment of the solid COPR material in contact with water, by addition of increasing weight % of the nanoparticles, resulted in a decrease in aqueous Cr(VI) concentrations to below detection limits, via the addition of ⩾5% w/w BnM or ⩾1% w/w nZVI. XANES analysis of the Cr K edge, showed that the % Cr(VI) in the COPR dropped from 26% to a minimum of 4–7% by the addition of 5% w/w BnM or 2% w/w nZVI, with higher additions unable to reduce the remaining Cr(VI). The treated materials exhibited minimal re-mobilization of soluble Cr(VI) by re-equilibration with atmospheric oxygen, with the bulk of the Cr remaining in the solid fraction. Both nanoparticles exhibited a considerable

Biogenic nano-magnetite and nano-zero valent iron treatment of alkaline Cr(VI) leachate and chromite ore processing residue

DOE PAGES

Watts, Mathew P.; Coker, Victoria S.; Parry, Stephen A.; ...

2014-12-11

Highly reactive nano-scale biogenic magnetite (BnM), synthesized by the Fe(III)-reducing bacterium Geobacter sulfurreducens, was tested for the potential to remediate alkaline Cr(VI) contaminated waters associated with chromite ore processing residue (COPR). The performance of this biomaterial, targeting aqueous Cr(VI) removal, was compared to a synthetic alternative, nano-scale zero valent iron (nZVI). Samples of highly contaminated alkaline groundwater and COPR solid waste were obtained from a contaminated site in Glasgow, UK. During batch reactivity tests, Cr(VI) removal from groundwater was inhibited by ~25% (BnM) and ~50% (nZVI) when compared to the treatment of less chemically complex model pH 12 Cr(VI) solutions.more » In both the model Cr(VI) solutions and contaminated groundwater experiments the surface of the nanoparticles became passivated, preventing complete coupling of their available electrons to Cr(VI) reduction. To investigate this process, the surfaces of the reacted samples were analyzed by TEM-EDX, XAS and XPS, confirming Cr(VI) reduction to the less soluble Cr(III) on the nanoparticle surface. In groundwater reacted samples the presence of Ca, Si and S was also noted on the surface of the nanoparticles, and is likely responsible for earlier onset of passivation. Treatment of the solid COPR material in contact with water, by addition of increasing weight % of the nanoparticles, resulted in a decrease in aqueous Cr(VI) concentrations to below detection limits, via the addition of ≥5% w/w BnM or ≥1% w/w nZVI. XANES analysis of the Cr K edge, showed that the % Cr(VI) in the COPR dropped from 26% to a minimum of 4–7% by the addition of 5% w/w BnM or 2% w/w nZVI, with higher additions unable to reduce the remaining Cr(VI). The treated materials exhibited minimal re-mobilization of soluble Cr(VI) by re-equilibration with atmospheric oxygen, with the bulk of the Cr remaining in the solid fraction. Both nanoparticles exhibited a considerable

Influence of crystal phases on electro-optic properties of epitaxially grown lanthanum-modified lead zirconate titanate films

NASA Astrophysics Data System (ADS)

Masuda, Shin; Seki, Atsushi; Masuda, Yoichiro

2010-02-01

We describe here how we have improved the crystal qualities and controlled the crystal phase of the lanthanum-modified lead zirconate titanate (PLZT) film without changing the composition ratio using an oxygen-pressure crystallization process. A PLZT film deposited on a SrTiO3 substrate with the largest electro-optic (EO) coefficient of 498 pm/V has been achieved by controlling the crystal phase of the film. Additionally, a fatigue-free lead zirconate titanate (PZT) capacitor with platinum electrodes has been realized by reducing the oxygen vacancies in the films.

Effects of lanthanum and acid rain stress on the bio-sequestration of lanthanum in phytoliths in germinated rice seeds

PubMed Central

Si, Yong; Wang, Lihong; Huang, Xiaohua

2018-01-01

REEs in the environment can be absorbed by plants and sequestered by plant phytoliths. Acid rain can directly or indirectly affect plant physiological functions. Currently, the effects of REEs and acid rain on phytolith-REEs complex in plants are not yet fully understood. In this study, a high-silicon accumulation crop, rice (Oryza sativa L.), was selected as a representative of plants, and orthogonal experiments were conducted under various levels of lanthanum [La(III)] and pH. The results showed that various La(III) concentrations could significantly improve the efficiency and sequestration of phytolith La(III) in germinated rice seeds. A pH of 4.5 promoted phytolith La(III) sequestration, while a pH of 3.5 inhibited sequestration. Compared with the single treatment with La(III), the combination of La(III) and acid rain inhibited the efficiency and sequestration of phytolith La(III). Correlation analysis showed that the efficiency of phytolith La(III) sequestration had no correlation with the production of phytolith but was closely correlated with the sequestration of phytolith La(III) and the physiological changes of germinated rice seeds. Phytolith morphology was an important factor affecting phytolith La(III) sequestration in germinated rice seeds, and the effect of tubes on sequestration was more significant than that of dumbbells. This study demonstrated that the formation of the phytolith and La(III) complex could be affected by exogenous La(III) and acid rain in germinated rice seeds. PMID:29763463

Catalytic bipolar interconnection plate for use in a fuel cell

DOEpatents

Lessing, Paul A.

1996-01-01

A bipolar interconnection plate for use between adjacent fuel cell units in a stacked fuel cell assembly. Each plate is manufactured from an intermetallic composition, examples of which include NiAl or Ni.sub.3 Al which can catalyze steam reforming of hydrocarbons. Distributed within the intermetallic structure of the plate is a ceramic filler composition. The plate includes a first side with gas flow channels therein and a second side with fuel flow channels therein. A protective coating is applied to the first side, with exemplary coatings including strontium-doped or calcium-doped lanthanum chromite. To produce the plate, Ni and Al powders are combined with the filler composition, compressed at a pressure of about 10,000-30,000 psi, and heated to about 600.degree.-1000.degree. C. The coating is then applied to the first side of the completed plate using liquid injection plasma deposition or other deposition techniques.

Catalytic bipolar interconnection plate for use in a fuel cell

DOEpatents

Lessing, P.A.

1996-03-05

A bipolar interconnection plate is described for use between adjacent fuel cell units in a stacked fuel cell assembly. Each plate is manufactured from an intermetallic composition, examples of which include NiAl or Ni{sub 3}Al which can catalyze steam reforming of hydrocarbons. Distributed within the intermetallic structure of the plate is a ceramic filler composition. The plate includes a first side with gas flow channels therein and a second side with fuel flow channels therein. A protective coating is applied to the first side, with exemplary coatings including strontium-doped or calcium-doped lanthanum chromite. To produce the plate, Ni and Al powders are combined with the filler composition, compressed at a pressure of about 10,000--30,000 psi, and heated to about 600--1000 C. The coating is then applied to the first side of the completed plate using liquid injection plasma deposition or other deposition techniques. 6 figs.

The soda-ash roasting of chromite ore processing residue for the reclamation of chromium

NASA Astrophysics Data System (ADS)

Antony, M. P.; Tathavadkar, V. D.; Calvert, C. C.; Jha, A.

2001-12-01

Sodium chromate is produced via the soda-ash roasting of chromite ore with sodium carbonate. After the reaction, nearly 15 pct of the chromium oxide remains unreacted and ends up in the waste stream, for landfills. In recent years, the concern over environmental pollution from hexavalent chromium (Cr6+) from the waste residue has become a major problem for the chromium chemical industry. The main purpose of this investigation is to recover chromium oxide present in the waste residue as sodium chromate. Cr2O3 in the residue is distributed between the two spinel solid solutions, Mg(Al,Cr)2O4 and γ-Fe2O3. The residue from the sodium chromate production process was analyzed both physically and chemically. The compositions of the mineral phases were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). The influence of alkali addition on the overall reaction rate is examined. The kinetics of the chromium extraction reaction resulting from the residue of the soda-ash roasting process under an oxidizing atmosphere is also investigated. It is shown that the experimental results for the roasting reaction can be best described by the Ginstling and Brounshtein (GB) equation for diffusion-controlled kinetics. The apparent activation energy for the roasting reaction was calculated to be between 85 and 90 kJ·mol-1 in the temperature range 1223 to 1473 K. The kinetics of leaching of Cr3+ ions using the aqueous phase from the process residue is also studied by treating the waste into acid solutions with different concentrations.

Graphene-based materials for tissue engineering.

PubMed

Shin, Su Ryon; Li, Yi-Chen; Jang, Hae Lin; Khoshakhlagh, Parastoo; Akbari, Mohsen; Nasajpour, Amir; Zhang, Yu Shrike; Tamayol, Ali; Khademhosseini, Ali

2016-10-01

Graphene and its chemical derivatives have been a pivotal new class of nanomaterials and a model system for quantum behavior. The material's excellent electrical conductivity, biocompatibility, surface area and thermal properties are of much interest to the scientific community. Two-dimensional graphene materials have been widely used in various biomedical research areas such as bioelectronics, imaging, drug delivery, and tissue engineering. In this review, we will highlight the recent applications of graphene-based materials in tissue engineering and regenerative medicine. In particular, we will discuss the application of graphene-based materials in cardiac, neural, bone, cartilage, skeletal muscle, and skin/adipose tissue engineering. We will also discuss the potential risk factors of graphene-based materials in tissue engineering. In conclusion, we will outline the opportunities in the usage of graphene-based materials for clinical applications. Published by Elsevier B.V.

Biocompatibility of Resin-based Dental Materials

PubMed Central

Moharamzadeh, Keyvan; Brook, Ian M.; Van Noort, Richard

2009-01-01

Oral and mucosal adverse reactions to resin-based dental materials have been reported. Numerous studies have examined the biocompatibility of restorative dental materials and their components, and a wide range of test systems for the evaluation of the biological effects of these materials have been developed. This article reviews the biological aspects of resin-based dental materials and discusses the conventional as well as the new techniques used for biocompatibility assessment of dental materials.

Design, Fabrication, Characterization and Modeling of Integrated Functional Materials

DTIC Science & Technology

2012-10-01

films. The successful optimization of the PZT thin film growth parameters allowed us to set the stage for doping PZT with rare earth elements...Lanthanum (La)-doped PZT (PLZT) (where Pb2+ is substituted by La3+), has a dramatic enhancement in the piezoelectric properties. There have been only a...few recent reports on the growth of La- PZT films. However, most of the reports were based on chemical routes such as metal organic decomposition

High-performance ferroelectric and magnetoresistive materials for next-generation thermal detector arrays

NASA Astrophysics Data System (ADS)

Todd, Michael A.; Donohue, Paul P.; Watton, Rex; Williams, Dennis J.; Anthony, Carl J.; Blamire, Mark G.

2002-12-01

This paper discusses the potential thermal imaging performance achievable from thermal detector arrays and concludes that the current generation of thin-film ferroelectric and resistance bolometer based detector arrays are limited by the detector materials used. It is proposed that the next generation of large uncooled focal plane arrays will need to look towards higher performance detector materials - particularly if they aim to approach the fundamental performance limits and compete with cooled photon detector arrays. Two examples of bolometer thin-film materials are described that achieve high performance from operating around phase transitions. The material Lead Scandium Tantalate (PST) has a paraelectric-to-ferroelectric phase transition around room temperature and is used with an applied field in the dielectric bolometer mode for thermal imaging. PST films grown by sputtering and liquid-source CVD have shown merit figures for thermal imaging a factor of 2 to 3 times higher than PZT-based pyroelectric thin films. The material Lanthanum Calcium Manganite (LCMO) has a paramagnetic to ferromagnetic phase transition around -20oC. This paper describes recent measurements of TCR and 1/f noise in pulsed laser-deposited LCMO films on Neodymium Gallate substrates. These results show that LCMO not only has high TCR's - up to 30%/K - but also low 1/f excess noise, with bolometer merit figures at least an order of magnitude higher than Vanadium Oxide, making it ideal for the next generation of microbolometer arrays. These high performance properties come at the expense of processing complexities and novel device designs will need to be introduced to realize the potential of these materials in the next generation of thermal detectors.

Passive Sensor Materials Based on Liquid Crystals

DTIC Science & Technology

2011-03-12

REPORT Passive Sensor Materials based on Liquid Crystals 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Research supported by this grant entitled “Passive...Sensor Materials Based on Liquid Crystals” revolved around an investigation of liquid crystalline materials for use in passive sensors for chemical... based on Liquid Crystals Report Title ABSTRACT Research supported by this grant entitled “Passive Sensor Materials Based on Liquid Crystals” revolved

Silk Fibroin Based Porous Materials

PubMed Central

Zhang, Qiang; Yan, Shuqin; Li, Mingzhong

2009-01-01

Silk from the Bombyx mori silkworm is a protein-based fiber. Bombyx mori silk fibroin (SF) is one of the most important candidates for biomedical porous material based on its superior machinability, biocompatibility, biodegradation, bioresorbability, and so on. In this paper, we have reviewed the key features of SF. Moreover we have focused on the morphous, technical processing, and biocompatibility of SF porous materials, followed by the application research. Finally, we provide a perspective the potential and problems of SF porous materials.

Process for production of solution-derived (Pb,La)(Nb,Sn,Zr,Ti)O.sub.3 thin films and powders

DOEpatents

Boyle, Timothy J.

1999-01-01

A simple and rapid process for synthesizing (Pb,La)(Nb,Sn,Zr,Ti)O.sub.3 precursor solutions and subsequent ferroelectric thin films and powders of the perovskite phase of these materials has been developed. This process offers advantages over standard methods, including: rapid solution synthesis (<10 minutes), use of commercially available materials, film production under ambient conditions, ease of lanthanum dissolution at high concentrations, and no heating requirements during solution synthesis. For lanthanum-doped ferroelectric materials, the lanthanum source can be added with total synthesis time less than 10 minutes. Films and powders are crystallized at approximately 650.degree. C. and exhibit ferroelectric properties comparable to films and powders produced by other techniques which require higher crystallization temperatures.

Influence of La/W ratio on electrical conductivity of lanthanum tungstate with high La/W ratio

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kojo, Gen; Shono, Yohei; Ushiyama, Hiroshi

The proton-conducting properties of lanthanum tungstates (LWOs) with high La/W ratios were investigated using electrochemical measurements and quantum chemical calculations. Single phases of LWOs with high La/W ratios (6.3≤La/W≤6.7) were synthesized by high-temperature sintering at around 1700 °C. The electrical conductivity of LWO increased with increasing La/W ratio in the single-phase region. The LWO synthesized at the optimum sintering temperature and time, and with the optimum La/W ratio gave the maximum conductivity, i.e., 2.7×10{sup −3} S cm{sup −1} with La/W=6.7 at 500 °C. Density functional theory calculations, using the nudged elastic band method, were performed to investigate the proton diffusionmore » barrier. The results suggest that the proton diffusion paths around La sites have the lowest proton diffusion barrier. These findings improve our understanding of LWO synthesis and the proton-conducting mechanism and provide a strategy for improving proton conduction in LWOs. - Graphical abstract: The LWOs with high La/W ratios were synthesized for the first time. The optimum La/W ratio gave the maximum conductivity with La/W=6.7 at 500 °C. The proton diffusion paths were also considered with density functional theory calculations. - Highlights: • The proton-conducting properties of lanthanum tungstates (LWOs) were investigated. • Single phase LWOs with high La/W ratios (6.3≤La/W≤6.7) were synthesized successfully. • LWOs with the high La/W ratios showed high proton conductivity. • The DFT calculation suggested the lowest proton diffusion barrier in the path around La sites.« less

MICROBIALLY MEDIATED LEACHING OF RARE EARTH ELEMENTS FROM RECYCLABLE MATERIALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, D. W.; Fujita, Y.; Daubaras, D. L.

2016-09-01

Bioleaching offers a potential approach for recovery of rare earth elements (REE) from recyclable materials, such as fluorescent lamp phosphors or degraded industrial catalysts. Microorganisms were enriched from REE-containing ores and recyclable materials with the goal of identifying strains capable of extracting REE from solid materials. Over 100 heterotrophic microorganisms were isolated and screened for their ability to produce organic acids capable of leaching REE. The ten most promising isolates were most closely related to Pseudomonas, Acinetobacter and Talaromyces. Of the acids produced, gluconic acid appeared to be the most effective at leaching REE (yttrium, lanthanum, cerium, europium, and terbium)more » from retorted phosphor powders (RPP), fluidized cracking catalyst (FCC), and europium-doped yttrium oxide (YOEu). We found that an Acinetobacter isolates, BH1, was the most capable strain and able to leach 33% of the total REE content from the FCC material. These results support the continuing evaluation of gluconic acid-producing microbes for large-scale REE recovery from recyclable materials.« less

Polyphosphazine-based polymer materials

DOEpatents

Fox, Robert V.; Avci, Recep; Groenewold, Gary S.

2010-05-25

Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

The influence of lake water alkalinity and humic substances on particle dispersion and lanthanum desorption from a lanthanum modified bentonite.

PubMed

Reitzel, Kasper; Balslev, Kristiane Astrid; Jensen, Henning S

2017-11-15

A 12 days laboratory study on potential desorption of Lanthanum (La) from a commercial La modified clay (Phoslock) was conducted using lake water from 17 Danish lakes with alkalinities between 0.02 and 3.7 meq L -1 and varying concentrations of DOC and humic acids (HA's). A similar study was conducted in artificial lake water with alkalinities from 0 to 2.5 meq L -1 in order to exclude interference from dissolved HA's. To test if La in solution (FLa) was associated with fine particles, the water samples were filtered sequentially through three filter sizes (1.2 μm, 0.45 μm and 0.2 μm), and finally, ultracentrifugation was used in an attempt to separate colloidal La from dissolved La. The study showed that higher FLa (up to 2.5 mg L -1 or 14% of the total La in the Phoslock) concentrations were found in soft water lakes compared to hard water lakes, probably due to dispersion of the clay at low alkalinities. In addition, this study showed that HA's seem to increase the FLa concentrations in soft water lakes, most likely through complexation of La retained in the Phoslock matrix. In summary, we conclude that elevated La concentrations in lake water after a Phoslock treatment should only be expected in soft water lakes rich in DOC and HA's. Copyright © 2017 Elsevier Ltd. All rights reserved.

Striped lanthanum cobaltite films: how strain orders oxygen defects

NASA Astrophysics Data System (ADS)

Birenbaum, Axiel Yael; Biegalski, Michael D.; Qiao, Liang; Cooper, Valentino R.; Borisevich, Albina

Oxygen-deficient metal cobalt oxides have been widely studied for solid oxide fuel cell cathode applications. In order to predict atomic-scale transport pathways, a thorough understanding of its defect properties is crucial. Previous studies, including Scanning Transmission Electron Microscopy (STEM), demonstrate lanthanum cobaltite, grown as thin films on [100]pc oriented perovskites, spontaneously order its oxygen vacancies. In this work, we investigate the behavior of LaCoO3 - δ thin films grown on SrTiO3 [111] surface to determine if orientation can be used to shape the anisotropy of oxygen transport. For these films, STEM studies reveal ordered vacancy arrangements. We do so by establishing the structural and electronic properties of LaCoO3 - δ on SrTiO3, using ab initio electronic structure calculations. We then treat how epitaxial strain leads to oxygen vacancies forming these distinctive stripe patterns. The impact of different substrates is addressed. In addition, this leads to an opportunity to discuss the effect of reduced symmetry in oxygen deficient compounds on cobalt oxide behavior compared to the ideal perovskite environment. Research was sponsored by the US DoE, Office of Science, BES, MSED, and used resources at NERSC and OLCF.

DFT calculations in the assignment of solid-state NMR and crystal structure elucidation of a lanthanum(iii) complex with dithiocarbamate and phenanthroline.

PubMed

Gowda, Vasantha; Laitinen, Risto S; Telkki, Ville-Veikko; Larsson, Anna-Carin; Antzutkin, Oleg N; Lantto, Perttu

2016-12-06

The molecular, crystal, and electronic structures as well as spectroscopic properties of a mononuclear heteroleptic lanthanum(iii) complex with diethyldithiocarbamate and 1,10-phenanthroline ligands (3 : 1) were studied by solid-state 13 C and 15 N cross-polarisation (CP) magic-angle-spinning (MAS) NMR, X-ray diffraction (XRD), and first principles density functional theory (DFT) calculations. A substantially different powder XRD pattern and 13 C and 15 N CP-MAS NMR spectra indicated that the title compound is not isostructural to the previously reported analogous rare earth complexes with the space group P2 1 /n. Both 13 C and 15 N CP-MAS NMR revealed the presence of six structurally different dithiocarbamate groups in the asymmetric unit cell, implying a non-centrosymmetric packing arrangement of molecules. This was supported by single-crystal X-ray crystallography showing that the title compound crystallised in the triclinic space group P1[combining macron]. In addition, the crystal structure also revealed that one of the dithiocarbamate ligands has a conformational disorder. NMR chemical shift calculations employing the periodic gauge including projector augmented wave (GIPAW) approach supported the assignment of the experimental 13 C and 15 N NMR spectra. However, the best correspondences were obtained with the structure where the atomic positions in the X-ray unit cell were optimised at the DFT level. The roles of the scalar and spin-orbit relativistic effects on NMR shielding were investigated using the zeroth-order regular approximation (ZORA) method with the outcome that already the scalar relativistic level qualitatively reproduces the experimental chemical shifts. The electronic properties of the complex were evaluated based on the results of the natural bond orbital (NBO) and topology of the electron density analyses. Overall, we apply a multidisciplinary approach acquiring comprehensive information about the solid-state structure and the metal

Investigation of the performances of PZT vs rare earth (BaLaTiO3) vibration based energy harvester

NASA Astrophysics Data System (ADS)

Pak, Nehemiah; Aris, Hasnizah; Nadia Taib, Bibi

2017-11-01

This study proposes the investigation of two piezoelectric material namely PZT and Lanthanum Doped Barium Titanate (BaLaTiO3) performance as a vibration based energy harvester. The piezoelectric material when applied mechanical stress or strain produces electricity through the piezoelectric effect. The vibration energy would exude mechanical energy and thus apply mechanical force on the energy harvester. The energy harvester would be designed and simulated using the piezoelectric material individually. The studied outputs are divided to frequency response, the load dependence, and the acceleration dependence whereby measurement are observed and taken at maximum power output. The simulation is done using the cantilevers design which employs d31 type of constants. Three different simulations to study the dependence of output power on the resonant frequency response, load and acceleration have found that material that exhibit highest power generation was the BaLaTiO3.

Lanthanum hexaboride for solar energy applications.

PubMed

Sani, Elisa; Mercatelli, Luca; Meucci, Marco; Zoli, Luca; Sciti, Diletta

2017-04-06

We investigate the optical properties of LaB 6 - based materials, as possible candidates for solid absorbers in Concentrating Solar Power (CSP) systems. Bulk LaB 6 materials were thermally consolidated by hot pressing starting from commercial powders. To assess the solar absorbance and spectral selectivity properties, room-temperature hemispherical reflectance spectra were measured from the ultraviolet to the mid-infrared, considering different compositions, porosities and surface roughnesses. Thermal emittance at around 1100 K has been measured. Experimental results showed that LaB 6 can have a solar absorbance comparable to that of the most advanced solar absorber material in actual plants such as Silicon Carbide, with a higher spectral selectivity. Moreover, LaB 6 has also the appealing characteristics to be a thermionic material, so that it could act at the same time both as direct high-temperature solar absorber and as electron source, significantly reducing system complexity in future concentrating solar thermionic systems and bringing a real innovation in this field.

Performance Improvement of V-Fe-Cr-Ti Solid State Hydrogen Storage Materials in Impure Hydrogen Gas.

PubMed

Ulmer, Ulrich; Oertel, Daria; Diemant, Thomas; Bonatto Minella, Christian; Bergfeldt, Thomas; Dittmeyer, Roland; Behm, R Jürgen; Fichtner, Maximilian

2018-01-17

Two approaches of engineering surface structures of V-Ti-based solid solution hydrogen storage alloys are presented, which enable improved tolerance toward gaseous oxygen (O 2 ) impurities in hydrogen (H 2 ) gas. Surface modification is achieved through engineering lanthanum (La)- or nickel (Ni)-rich surface layers with enhanced cyclic stability in an H 2 /O 2 mixture. The formation of a Ni-rich surface layer does not improve the cycling stability in H 2 /O 2 mixtures. Mischmetal (Mm, a mixture of La and Ce) agglomerates are observed within the bulk and surface of the alloy when small amounts of this material are added during arc melting synthesis. These agglomerates provide hydrogen-transparent diffusion pathways into the bulk of the V-Ti-Cr-Fe hydrogen storage alloy when the remaining oxidized surface is already nontransparent for hydrogen. Thus, the cycling stability of the alloy is improved in an O 2 -containing hydrogen environment as compared to the same alloy without addition of Mm. The obtained surface-engineered storage material still absorbs hydrogen after 20 cycles in a hydrogen-oxygen mixture, while the original material is already deactivated after 4 cycles.

Reduced conductivity and enhancement of Debye orientational polarization in lanthanum doped cobalt ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Rahman, Atta ur; Rafiq, M. A.; Karim, S.; Maaz, K.; Siddique, M.; Hasan, M. M.

2011-12-01

In this work we have investigated the conductivity and dielectric properties of CoLaxFe2-xO4 (x=0.0, 0.03, 0.05, and 0.07) nanoparticles synthesized by chemical co-precipitation route. X-ray diffraction analysis confirms the inverse spinal structure of nanoparticles with slight increase in the lattice constant as La concentration increases. Transmission electron microscopy shows spherical nanoparticles with sizes of ∼20 nm. Impedance spectroscopy of the samples was performed in the frequency range 20 Hz-2 MHz at room temperature. The resistance of the grains and grain boundaries was found to increase with lanthanum concentration while the AC conductivity of the samples was observed to decrease with increasing La concentration. Dipolar orientational polarization was found to play an important role in determining dielectric properties of the samples.

The preparation of large surface area lanthanum based perovskite supports for AuPt nanoparticles: tuning the glycerol oxidation reaction pathway by switching the perovskite B site

PubMed Central

Evans, Christopher D.; Smith, Paul J.; Manning, Troy D.; Miedziak, Peter J.; Brett, Gemma L.; Armstrong, Robert D.; Bartley, Jonathan K.; Taylor, Stuart H.; Rosseinsky, Matthew J.; Hutchings, Graham J.

2016-01-01

Gold and gold alloys, in the form of supported nanoparticles, have been shown over the last three decades to be highly effective oxidation catalysts. Mixed metal oxide perovskites, with their high structural tolerance, are ideal for investigating how changes in the chemical composition of supports affect the catalysts' properties, while retaining similar surface areas, morphologies and metal co-ordinations. However, a significant disadvantage of using perovskites as supports is their high crystallinity and small surface area. We report the use of a supercritical carbon dioxide anti-solvent precipitation methodology to prepare large surface area lanthanum based perovskites, making the deposition of 1 wt% AuPt nanoparticles feasible. These catalysts were used for the selective oxidation of glycerol. By changing the elemental composition of the perovskite B site, we dramatically altered the reaction pathway between a sequential oxidation route to glyceric or tartronic acid and a dehydration reaction pathway to lactic acid. Selectivity profiles were correlated to reported oxygen adsorption capacities of the perovskite supports and also to changes in the AuPt nanoparticle morphologies. Extended time on line analysis using the best oxidation catalyst (AuPt/LaMnO3) produced an exceptionally high tartronic acid yield. LaMnO3 produced from alternative preparation methods was found to have lower activities, but gave comparable selectivity profiles to that produced using the supercritical carbon dioxide anti-solvent precipitation methodology. PMID:27074316

The preparation of large surface area lanthanum based perovskite supports for AuPt nanoparticles: tuning the glycerol oxidation reaction pathway by switching the perovskite B site.

PubMed

Evans, Christopher D; Kondrat, Simon A; Smith, Paul J; Manning, Troy D; Miedziak, Peter J; Brett, Gemma L; Armstrong, Robert D; Bartley, Jonathan K; Taylor, Stuart H; Rosseinsky, Matthew J; Hutchings, Graham J

2016-07-04

Gold and gold alloys, in the form of supported nanoparticles, have been shown over the last three decades to be highly effective oxidation catalysts. Mixed metal oxide perovskites, with their high structural tolerance, are ideal for investigating how changes in the chemical composition of supports affect the catalysts' properties, while retaining similar surface areas, morphologies and metal co-ordinations. However, a significant disadvantage of using perovskites as supports is their high crystallinity and small surface area. We report the use of a supercritical carbon dioxide anti-solvent precipitation methodology to prepare large surface area lanthanum based perovskites, making the deposition of 1 wt% AuPt nanoparticles feasible. These catalysts were used for the selective oxidation of glycerol. By changing the elemental composition of the perovskite B site, we dramatically altered the reaction pathway between a sequential oxidation route to glyceric or tartronic acid and a dehydration reaction pathway to lactic acid. Selectivity profiles were correlated to reported oxygen adsorption capacities of the perovskite supports and also to changes in the AuPt nanoparticle morphologies. Extended time on line analysis using the best oxidation catalyst (AuPt/LaMnO3) produced an exceptionally high tartronic acid yield. LaMnO3 produced from alternative preparation methods was found to have lower activities, but gave comparable selectivity profiles to that produced using the supercritical carbon dioxide anti-solvent precipitation methodology.

Future perspectives of resin-based dental materials.

PubMed

Jandt, Klaus D; Sigusch, Bernd W

2009-08-01

This concise review and outlook paper gives a view of selected potential future developments in the area of resin-based biomaterials with an emphasis on dental composites. A selection of key publications (1 book, 35 scientific original publications and 1 website source) covering the areas nanotechnology, antimicrobial materials, stimuli responsive materials, self-repairing materials and materials for tissue engineering with direct or indirect relations and/or implications to resin-based dental materials is critically reviewed and discussed. Connections between these fields and their potential for resin-based dental materials are highlighted and put in perspective. The need to improve shrinkage properties and wear resistance is obvious for dental composites, and a vast number of attempts have been made to accomplish these aims. Future resin-based materials may be further improved in this respect if, for example nanotechnology is applied. Dental composites may, however, reach a completely new quality by utilizing new trends from materials science, such as introducing nanostructures, antimicrobial properties, stimuli responsive capabilities, the ability to promote tissue regeneration or repair of dental tissues if the composites were able to repair themselves. This paper shows selected potential future developments in the area of resin-based dental materials, gives basic and industrial researchers in dental materials science, and dental practitioners a glance into the potential future of these materials, and should stimulate discussion about needs and future developments in the area.

New Cork-Based Materials and Applications.

PubMed

Gil, Luís

2015-02-10

This review work is an update of a previous work reporting the new cork based materials and new applications of cork based materials. Cork is a material which has been used for multiple applications. The most known uses of cork are in stoppers (natural and agglomerated cork) for alcoholic beverages, classic floor covering with composite cork tiles (made by the binding of cork particles with different binders), and thermal/acoustic/vibration insulation with expanded corkboard in buildings and some other industrial fields. Many recent developments have been made leading to new cork based materials. Most of these newly developed cork materials are not yet on the market, but they represent new possibilities for engineers, architects, designers and other professionals which must be known and considered, potentially leading to their industrialization. This paper is a review covering the last five years of innovative cork materials and applications also mentioning previous work not reported before.

New Cork-Based Materials and Applications

PubMed Central

Gil, Luís

2015-01-01

This review work is an update of a previous work reporting the new cork based materials and new applications of cork based materials. Cork is a material which has been used for multiple applications. The most known uses of cork are in stoppers (natural and agglomerated cork) for alcoholic beverages, classic floor covering with composite cork tiles (made by the binding of cork particles with different binders), and thermal/acoustic/vibration insulation with expanded corkboard in buildings and some other industrial fields. Many recent developments have been made leading to new cork based materials. Most of these newly developed cork materials are not yet on the market, but they represent new possibilities for engineers, architects, designers and other professionals which must be known and considered, potentially leading to their industrialization. This paper is a review covering the last five years of innovative cork materials and applications also mentioning previous work not reported before. PMID:28787962

Process for production of solution-derived (Pb,La)(Nb,Sn,Zr,Ti)O{sub 3} thin films and powders

DOEpatents

Boyle, T.J.

1999-01-12

A simple and rapid process for synthesizing (Pb,La)(Nb,Sn,Zr,Ti)O{sub 3} precursor solutions and subsequent ferroelectric thin films and powders of the perovskite phase of these materials has been developed. This process offers advantages over standard methods, including: rapid solution synthesis (<10 minutes), use of commercially available materials, film production under ambient conditions, ease of lanthanum dissolution at high concentrations, and no heating requirements during solution synthesis. For lanthanum-doped ferroelectric materials, the lanthanum source can be added with total synthesis time less than 10 minutes. Films and powders are crystallized at approximately 650 C and exhibit ferroelectric properties comparable to films and powders produced by other techniques which require higher crystallization temperatures. 2 figs.

Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions and Kinetic Resolution of Resultant α-Silyloxyketones

PubMed Central

Tarr, James C.

2010-01-01

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 α-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant α-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction. PMID:20392127

Lanthanum tricyanide-catalyzed acyl silane-ketone benzoin additions and kinetic resolution of resultant alpha-silyloxyketones.

PubMed

Tarr, James C; Johnson, Jeffrey S

2010-05-21

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 alpha-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant alpha-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction.

Lanthanum doped titania decorated with silver plasmonic nanoparticles with enhanced photocatalytic activity under UV-visible light

NASA Astrophysics Data System (ADS)

Dal'Toé, Adrieli T. O.; Colpani, Gustavo Lopes; Padoin, Natan; Fiori, Márcio Antônio; Soares, Cíntia

2018-05-01

Lanthanum doped titanium dioxide decorated with silver plasmonic nanoparticles (Ag-La/TiO2 NPs) materials were prepared using a simple ultrasound-assisted wet impregnation method followed by silver photodeposition. The obtained photocatalysts with different Ag contents were characterized by XRD, FE-SEM, EDX, TEM, BET, XPS, DRS and PL techniques. Moreover, the size distribution of the nanoparticles aggregates was assessed. The characterization analysis revealed that La doping slightly changed the crystalline phase of TiO2, increased the amount of surface hydroxyl groups and interacted with TiO2 nanoparticles via Ti-O-La bond, while Ag photodeposition enhanced the absorption of visible light due to the effects of localized surface plamon resonance and significantly decreased electronic recombination rate by the Schottky junction. Furthermore, the combination of Ag-La induced the formation of oxygen vacancies, which increased the amount of adsorbed surface hydroxyl groups in Ag-La/TiO2. In addition, Ag-La possibly decreased the semiconductor surface energy, which acted positively in the reduction of NPs aggregation. These features along with better textural properties (greater surface areas) played a fundamental role in the enhancement of the photocatalytic activity of Ag-La/TiO2 composites for the decolorization of methylene blue under UV-visible irradiation compared to the mono-metallic (La/TiO2 and Ag/TiO2) modified photocatalysts. Finally, a mechanism for the transfer of charge carriers in Ag-La/TiO2 photocatalyst under UV-visible irradiation was proposed.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ianculescu, Adelina Carmen; Vasilescu, Catalina Andreea, E-mail: katyvasilescu85@yahoo.com; National Institute for Lasers, Plasma and Radiation Physics, P.O. Box MG54, 077125 Magurele

2015-08-15

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

Tungsten - Yttrium Based Nuclear Structural Materials

NASA Astrophysics Data System (ADS)

Ramana, Chintalapalle; Chessa, Jack; Martinenz, Gustavo

2013-04-01

The challenging problem currently facing the nuclear science community in this 21st century is design and development of novel structural materials, which will have an impact on the next-generation nuclear reactors. The materials available at present include reduced activation ferritic/martensitic steels, dispersion strengthened reduced activation ferritic steels, and vanadium- or tungsten-based alloys. These materials exhibit one or more specific problems, which are either intrinsic or caused by reactors. This work is focussed towards tungsten-yttrium (W-Y) based alloys and oxide ceramics, which can be utilized in nuclear applications. The goal is to derive a fundamental scientific understanding of W-Y-based materials. In collaboration with University of Califonia -- Davis, the project is designated to demonstrate the W-Y based alloys, ceramics and composites with enhanced physical, mechanical, thermo-chemical properties and higher radiation resistance. Efforts are focussed on understanding the microstructure, manipulating materials behavior under charged-particle and neutron irradiation, and create a knowledge database of defects, elemental diffusion/segregation, and defect trapping along grain boundaries and interfaces. Preliminary results will be discussed.

Niobium Doped Lanthanum Strontium Ferrite as A Redox-Stable and Sulfur-Tolerant Anode for Solid Oxide Fuel Cells.

PubMed

Li, Jingwei; Wei, Bo; Cao, Zhiqun; Yue, Xing; Zhang, Yaxin; Lü, Zhe

2018-01-10

The Nb-doped lanthanum strontium ferrite perovskite oxide La 0.8 Sr 0.2 Fe 0.9 Nb 0.1 O 3-δ (LSFNb) is evaluated as an anode material in a solid oxide fuel cell (SOFC). The effects of Nb partial substitution in the crystal structure, the electrical conductivity, and the valence of Fe ions are studied. LSFNb exhibits good structural stability in a severe reducing atmosphere at 800 °C, suggesting that high-valent Nb can effectively promote the stability of the lattice structure. The concentration of Fe 2+ increases after Nb doping, as confirmed by X-ray photoelectron spectroscopy. The maximum power density of a thick Sc-stabilized zirconia (ScSZ) electrolyte-supported single cell reached 241.6 mW cm -2 at 800 °C with H 2 as fuel. The cell exhibited excellent stability for 100 h continuous operation without detectable degeneration. Scanning electron microscopy clearly revealed exsolution on the LSFNb surface after operation. Meanwhile, LSFNb particles agglomerated significantly during long-term stability testing. Impedance spectra suggested that both the LSFNb anode and the (La 0.75 Sr 0.25 ) 0.95 MnO 3-δ /ScSZ cathode underwent an activation process during long-term testing, through which the charge transfer ability increased significantly. Meanwhile, low-frequency resistance (R L ) mainly attributed to the anode (80 %) significantly increased, probably due to the agglomeration of LSFNb particles. The LSFNb anode exhibits excellent anti-sulfuring poisoning ability and redox stability. These results demonstrate that LSFNb is a promising anode material for SOFCs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanocellulose based polymer composite for acoustical materials

NASA Astrophysics Data System (ADS)

Farid, Mohammad; Purniawan, Agung; Susanti, Diah; Priyono, Slamet; Ardhyananta, Hosta; Rahmasita, Mutia E.

2018-04-01

Natural fibers are biodegradable materials that are innovatively and widely used for composite reinforcement in automotive components. Nanocellulose derived from natural fibers oil palm empty bunches have properties that are remarkable for use as a composite reinforcement. However, there have not been many investigations related to the use of nanocellulose-based composites for wideband sound absorption materials. The specimens of nanocellulose-based polyester composite were prepared using a spray method. An impedance tube method was used to measure the sound absorption coefficient of this composite material. To reveal the characteristics of the nanocellulose-based polyester composite material, SEM (scanning electron microscope), TEM (Transmission Electron Microscope), FTIR (Fourier Transform Infra Red), TGA (Thermogravimetric Analysis), and density tests were performed. Sound absorption test results showed the average value of sound absorption coefficient of 0.36 to 0,46 for frequency between 500 and 4000 Hz indicating that this nanocellulose-based polyester composite materials had a tendency to wideband sound absorption materials and potentially used as automotive interior materials.

LDEF materials special investigation group's data bases

NASA Technical Reports Server (NTRS)

Strickland, John W.; Funk, Joan G.; Davis, John M.

1993-01-01

The Long Duration Exposure Facility (LDEF) was composed of and contained a wide array of materials, representing the largest collection of materials flown for space exposure and returned for ground-based analyses to date. The results and implications of the data from these materials are the foundation on which future space missions will be built. The LDEF Materials Special Investigation Group (MSIG) has been tasked with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the space user community in an easily accessed, user-friendly form. The format and content of the data bases developed or being developed to accomplish this task are discussed. The hardware and software requirements for each of the three data bases are discussed along with current availability of the data bases.

Data for effects of lanthanum complex on the thermo-oxidative aging of natural rubber.

PubMed

Zheng, Wei; Liu, Li; Zhao, Xiuying; He, Jingwei; Wang, Ao; Chan, Tung W; Wu, Sizhu

2015-12-01

Novel mixed antioxidants composed of antioxidant IPPD and lanthanum (La) complex were added as a filler to form natural rubber (NR) composites. By mechanical testing, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and thermogravimetric analysis (TGA), a string of data, including the mechanical properties, the variation of internal groups and the thermal and thermo-oxidative decompositions of NR, was presented in this data article. The data accompanying its research article [1] studied the thermo-oxidative aging properties of NR in detail. The density function theoretical (DFT) calculations were also used as an assistant to study the thermo-oxidative aging mechanism of NR. The data revealed that this new rare-earth antioxidant could indeed enhance the thermo-oxidative aging resistance of NR, which is associated with its different function mechanism from that of the pure antioxidant IPPD.

Lanthanum induced B-to-Z transition in self-assembled Y-shaped branched DNA structure

PubMed Central

Nayak, Ashok K.; Mishra, Aseem; Jena, Bhabani S.; Mishra, Barada K.; Subudhi, Umakanta

2016-01-01

Controlled conversion of right-handed B-DNA to left-handed Z-DNA is one of the greatest conformational transitions in biology. Recently, the B-Z transition has been explored from nanotechnological points of view and used as the driving machinery of many nanomechanical devices. Using a combination of CD spectroscopy, fluorescence spectroscopy, and PAGE, we demonstrate that low concentration of lanthanum chloride can mediate B-to-Z transition in self-assembled Y-shaped branched DNA (bDNA) structure. The transition is sensitive to the sequence and structure of the bDNA. Thermal melting and competitive dye binding experiments suggest that La3+ ions are loaded to the major and minor grooves of DNA and stabilize the Z-conformation. Our studies also show that EDTA and EtBr play an active role in reversing the transition from Z-to-B DNA. PMID:27241949

Lanthanum induced B-to-Z transition in self-assembled Y-shaped branched DNA structure

NASA Astrophysics Data System (ADS)

Nayak, Ashok K.; Mishra, Aseem; Jena, Bhabani S.; Mishra, Barada K.; Subudhi, Umakanta

2016-05-01

Controlled conversion of right-handed B-DNA to left-handed Z-DNA is one of the greatest conformational transitions in biology. Recently, the B-Z transition has been explored from nanotechnological points of view and used as the driving machinery of many nanomechanical devices. Using a combination of CD spectroscopy, fluorescence spectroscopy, and PAGE, we demonstrate that low concentration of lanthanum chloride can mediate B-to-Z transition in self-assembled Y-shaped branched DNA (bDNA) structure. The transition is sensitive to the sequence and structure of the bDNA. Thermal melting and competitive dye binding experiments suggest that La3+ ions are loaded to the major and minor grooves of DNA and stabilize the Z-conformation. Our studies also show that EDTA and EtBr play an active role in reversing the transition from Z-to-B DNA.

Data for effects of lanthanum complex on the thermo-oxidative aging of natural rubber

PubMed Central

Zheng, Wei; Liu, Li; Zhao, Xiuying; He, Jingwei; Wang, Ao; Chan, Tung W.; Wu, Sizhu

2015-01-01

Novel mixed antioxidants composed of antioxidant IPPD and lanthanum (La) complex were added as a filler to form natural rubber (NR) composites. By mechanical testing, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and thermogravimetric analysis (TGA), a string of data, including the mechanical properties, the variation of internal groups and the thermal and thermo-oxidative decompositions of NR, was presented in this data article. The data accompanying its research article [1] studied the thermo-oxidative aging properties of NR in detail. The density function theoretical (DFT) calculations were also used as an assistant to study the thermo-oxidative aging mechanism of NR. The data revealed that this new rare-earth antioxidant could indeed enhance the thermo-oxidative aging resistance of NR, which is associated with its different function mechanism from that of the pure antioxidant IPPD. PMID:26693513

Material Characterization of Microsphere-Based Scaffolds with Encapsulated Raw Materials

PubMed Central

Sridharan, BanuPriya; Mohan, Neethu; Berkland, Cory J.; Detamore, Michael S.

2016-01-01

“Raw materials,” or materials capable of serving both as building blocks and as signals, which are often but not always natural materials, are taking center stage in biomaterials for contemporary regenerative medicine. In osteochondral tissue engineering, a field leveraging the underlying bone to facilitate cartilage regeneration, common raw materials include chondroitin sulfate (CS) for cartilage and β-tricalcium phosphate (TCP) for bone. Building on our previous work with gradient scaffolds based on microspheres, here we delved deeper into the characterization of individual components. In the current study, the release of CS and TCP from poly(D,L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds was evaluated over a time period of 4 weeks. Raw material encapsulated groups were compared to ‘blank’ groups and evaluated for surface topology, molecular weight, and mechanical performance as a function of time. The CS group may have led to increased surface porosity, and the addition of CS improved the mechanical performance of the scaffold. The finding that CS was completely released into the surrounding media by 4 weeks has a significant impact on future in vivo studies, given rapid bioavailability. The addition of TCP seemed to contribute to the rough external appearance of the scaffold. The current study provides an introduction to degradation patterns of homogenous raw material encapsulated scaffolds, providing characterization data to advance the field of microsphere-based scaffolds in tissue engineering. PMID:27040236

Fluoride glass starting materials - Characterization and effects of thermal treatment

NASA Technical Reports Server (NTRS)

Chen, William; Dunn, Bruce; Shlichta, Paul; Neilson, George F.; Weinberg, Michael C.

1987-01-01

The production of heavy metal fluoride (HMF) glasses, and the effects of thermal treatments on the HMF glasses are investigated. ZrF4, BaF2, AlF3, LaF3, and NaF were utilized in the synthesis of zirconium-barium-lanthanum-aluminum-sodium fluoride glass. The purity of these starting materials, in particular ZrF4, is evaluated using XRD analysis. The data reveal that low temperature heating of ZrF4-H2O is effective in removing the water of hydration, but causes the production of ZrF4 and oxyfluorides; however, dehydration followed by sublimation results in the production of monoclinic ZrFe without water or oxyfluoride contaminants.

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)

Sadiq, Muhammad; Pesci, Raphaël; Cherkaoui, Mohammed

2013-03-01

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.

1-dimension nano-material-based flexible device

NASA Astrophysics Data System (ADS)

Yang, Xing; Zhou, Zhaoying; Zheng, Fuzhong

2009-11-01

1D nano-material-based flexible devices has attracted considerable attention owing to the growing need of the high-sensitivity flexible sensor, portable consumer electronics etc.. In this paper, the 1D nano-materials-based flexible device on polyimide substrate was proposed. The bottom-up and top-down combined process were used for constructing the ZnO nanowire and the CNT-based flexible devices. Their electrical characteristics were also investigated. The measurement results demonstrate that the flexible device covered with a layer of Al2O3 has good ohm electrical contact behavior between the nano-material and micro-electrodes. The proposed 1D nano-material-based flexible device shows the application potential in the sensing fields.

Neoproterozoic chromite-bearing high-Mg diorites in the western part of the Jiangnan orogen, southern China: Geochemistry, petrogenesis and tectonic implications

NASA Astrophysics Data System (ADS)

Chen, Xin; Wang, Di; Wang, Xiao-Lei; Gao, Jian-Feng; Shu, Xu-Jie; Zhou, Jin-Cheng; Qi, Liang

2014-07-01

High-Mg diorites were discovered in the southern part of the ca. 830 Ma Dongma Pluton, northern Guangxi Province of southern China. The diorites (SiO2 = 59-65 wt%) are characterized by high MgO (6.7-8.9 wt%) contents and Mg-number [Mg# = 100 × Mg/(Mg + Fe)] (69-73), in contrary to the associated medium-Mg (MgO = 3.4-3.8 wt%, Mg# = 59-63) granodiorites in the Dongma main body and the low-Mg (MgO = 1.4-1.9 wt%, Mg# = 46-51) granodiorites in the Bendong Pluton to the north. Moreover, the high-Mg diorites show surprisingly high Cr (595-640 ppm) and Ni (171-194 ppm) concentrations, which are beyond the ranges of most coeval mafic rocks in the study area. Correspondingly, chromite crystals were separated from the high-Mg diorites and some of the medium-Mg granodiorites, and they show high Cr# [100 × Cr/(Cr + Al)] (average of 75), but low Mg# (0.34-2.51) and low Fe3 +. The decoupling of Cr# and Mg# and the existence of quartz + apatite mineral inclusion in chromites suggest Mg-Fe exchange that may be facilitated by the disequilibrium resulted from magma mixing. The high-Mg diorites show low La/Yb (6.8-8.5) and Sr/Y (2.1-3.1) ratios, significant negative anomalies of Nb and Ti and positive anomaly of Pb, resembling the Setouchi high-Mg andesites, despite of their relatively low Sr (71-100 ppm). All of the studied diorites and granodiorites show enriched Nd isotope compositions, with εNd(t) values (- 3.2 to - 5.9) a bit higher than some of the associated mafic rocks. Some of the high-Mg diorites show whole-rock εHf(t) (- 6.0 to - 6.2) coupled with Nd isotopes, similar to the associated mafic-ultramafic rocks in northern Guangxi, suggesting the metasomatism by melts of subducting sediments in the mantle source. Whereas, others show decoupled Nd-Hf isotopes that are similar to the medium- and low-Mg granodiorites [εHf(t) = - 1.8 to + 0.05], probably indicating the late magma mixing with granitic magmas at a crustal level for the dioritic magmas. We propose a two

A multi-scale study of the adsorption of lanthanum on the (110) surface of tungsten

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samin, Adib J.; Zhang, Jinsuo

In this study, we utilize a multi-scale approach to studying lanthanum adsorption on the (110) plane of tungsten. The energy of the system is described from density functional theory calculations within the framework of the cluster expansion method. It is found that including two-body figures up to the sixth nearest neighbor yielded a reasonable agreement with density functional theory calculations as evidenced by the reported cross validation score. The results indicate that the interaction between the adsorbate atoms in the adlayer is important and cannot be ignored. The parameterized cluster expansion expression is used in a lattice gas Monte Carlomore » simulation in the grand canonical ensemble at 773 K and the adsorption isotherm is recorded. Implications of the obtained results for the pyroprocessing application are discussed.« less

A multi-scale study of the adsorption of lanthanum on the (110) surface of tungsten

NASA Astrophysics Data System (ADS)

Samin, Adib J.; Zhang, Jinsuo

2016-07-01

In this study, we utilize a multi-scale approach to studying lanthanum adsorption on the (110) plane of tungsten. The energy of the system is described from density functional theory calculations within the framework of the cluster expansion method. It is found that including two-body figures up to the sixth nearest neighbor yielded a reasonable agreement with density functional theory calculations as evidenced by the reported cross validation score. The results indicate that the interaction between the adsorbate atoms in the adlayer is important and cannot be ignored. The parameterized cluster expansion expression is used in a lattice gas Monte Carlo simulation in the grand canonical ensemble at 773 K and the adsorption isotherm is recorded. Implications of the obtained results for the pyroprocessing application are discussed.

Learning material recommendation based on case-based reasoning similarity scores

NASA Astrophysics Data System (ADS)

Masood, Mona; Mokmin, Nur Azlina Mohamed

2017-10-01

A personalized learning material recommendation is important in any Intelligent Tutoring System (ITS). Case-based Reasoning (CBR) is an Artificial Intelligent Algorithm that has been widely used in the development of ITS applications. This study has developed an ITS application that applied the CBR algorithm in the development process. The application has the ability to recommend the most suitable learning material to the specific student based on information in the student profile. In order to test the ability of the application in recommending learning material, two versions of the application were created. The first version displayed the most suitable learning material and the second version displayed the least preferable learning material. The results show the application has successfully assigned the students to the most suitable learning material.

Atmospheric Plasma Spraying Low-Temperature Cathode Materials for Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Harris, J.; Kesler, O.

2010-01-01

Atmospheric plasma spraying (APS) is attractive for manufacturing solid oxide fuel cells (SOFCs) because it allows functional layers to be built rapidly with controlled microstructures. The technique allows SOFCs that operate at low temperatures (500-700 °C) to be fabricated by spraying directly onto robust and inexpensive metallic supports. However, standard cathode materials used in commercial SOFCs exhibit high polarization resistances at low operating temperatures. Therefore, alternative cathode materials with high performance at low temperatures are essential to facilitate the use of metallic supports. Coatings of lanthanum strontium cobalt ferrite (LSCF) were fabricated on steel substrates using axial-injection APS. The thickness and microstructure of the coating layers were evaluated, and x-ray diffraction analysis was performed on the coatings to detect material decomposition and the formation of undesired phases in the plasma. These results determined the envelope of plasma spray parameters in which coatings of LSCF can be manufactured, and the range of conditions in which composite cathode coatings could potentially be manufactured.

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

PubMed Central

2014-01-01

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

Triarylborane-Based Materials for OLED Applications.

PubMed

Turkoglu, Gulsen; Cinar, M Emin; Ozturk, Turan

2017-09-13

Multidisciplinary research on organic fluorescent molecules has been attracting great interest owing to their potential applications in biomedical and material sciences. In recent years, electron deficient systems have been increasingly incorporated into fluorescent materials. Triarylboranes with the empty p orbital of their boron centres are electron deficient and can be used as strong electron acceptors in conjugated organic fluorescent materials. Moreover, their applications in optoelectronic devices, energy harvesting materials and anion sensing, due to their natural Lewis acidity and remarkable solid-state fluorescence properties, have also been investigated. Furthermore, fluorescent triarylborane-based materials have been commonly utilized as emitters and electron transporters in organic light emitting diode (OLED) applications. In this review, triarylborane-based small molecules and polymers will be surveyed, covering their structure-property relationships, intramolecular charge transfer properties and solid-state fluorescence quantum yields as functional emissive materials in OLEDs. Also, the importance of the boron atom in triarylborane compounds is emphasized to address the key issues of both fluorescent emitters and their host materials for the construction of high-performance OLEDs.

Material-based figure of merit for caloric materials

DOE PAGES

Griffith, L. D.; Mudryk, Y.; Slaughter, J.; ...

2018-01-21

Efficient use of reversible thermal effects in magnetocaloric, electrocaloric, and elastocaloric materials is a promising avenue that can lead to a substantially increased efficiency of refrigeration and heat pumping devices, most importantly those used in household and commercial cooling applications near ambient temperature. A proliferation in caloric materials research has resulted in a wide array of materials where only the isothermal change in entropy in response to a handful of different field strengths over a limited range of temperatures has been evaluated and reported. Given the abundance of such data, there is a clear need for a simple and reliablemore » figure of merit enabling fast screening and down-selection to justify further detailed characterization of those materials systems that hold the greatest promise. Based on the analysis of several well-known materials that exhibit vastly different magnetocaloric effects, the Temperature averaged Entropy Change (TEC) is introduced as a suitable early indicator of the material’s utility for magnetocaloric cooling applications, and its adoption by the caloric community is recommended.« less

Material-based figure of merit for caloric materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffith, L. D.; Mudryk, Y.; Slaughter, J.

Efficient use of reversible thermal effects in magnetocaloric, electrocaloric, and elastocaloric materials is a promising avenue that can lead to a substantially increased efficiency of refrigeration and heat pumping devices, most importantly those used in household and commercial cooling applications near ambient temperature. A proliferation in caloric materials research has resulted in a wide array of materials where only the isothermal change in entropy in response to a handful of different field strengths over a limited range of temperatures has been evaluated and reported. Given the abundance of such data, there is a clear need for a simple and reliablemore » figure of merit enabling fast screening and down-selection to justify further detailed characterization of those materials systems that hold the greatest promise. Based on the analysis of several well-known materials that exhibit vastly different magnetocaloric effects, the Temperature averaged Entropy Change (TEC) is introduced as a suitable early indicator of the material’s utility for magnetocaloric cooling applications, and its adoption by the caloric community is recommended.« less

Effect of R(3+) ions on the structure and properties of lanthanum borate glasses

NASA Technical Reports Server (NTRS)

Chakraborty, I. N.; Day, D. E.

1985-01-01

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.

Novel GO-LaSmO2 Nanocomposite as an Effective Electrode Material for Hydrogen Fuel Cells

NASA Astrophysics Data System (ADS)

El-Amin, Ayman A.; Othman, Abdelhameed M.

2016-04-01

Nano-composites of lanthanum-samarium oxide (LaSmO2) were prepared in the absence and presence of graphene oxide (GO) and characterized as an effective electrode material for hydrogen fuel cells. X-ray and scanning electron microscope investigations revealed grain sizes of 8 nm for LaSmO2 and 12 nm for GO-LaSmO2 composites. The x-ray diffraction pattern showed sharp peaks, indicating a well-crystallized phase indexable to a rhombohedral structure with space group R 3 C , and their structural refinement performed in the hexagonal mode. The ionic conductivity of LaSmO2 was found to be 4.12 × 10-5 S/cm, while in the presence of GO it was enhanced to 5.32 × 10-5 S/cm. The mechanism of conduction in the proposed nano-materials was investigated based on frequency exponent S. The values of S were observed to decrease with increasing temperature. This result was found to be in good agreement with the correlated barrier hopping (CBH) model. The present work revealed GO to be a conductivity enhancer that caused the GO-LaSmO2 composite to be an effective electrode material for hydrogen fuel cells.

Phonon characteristics of high {Tc} superconductors from neutron Doppler broadening measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trela, W.J.; Kwei, G.H.; Lynn, J.E.

Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La{sub 2{minus}x}Ba{sub x}CuO{sub 4}. Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phononsmore » carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra.« less

Effect of cobalt doping on structural and dielectric properties of nanocrystalline LaCrO3

NASA Astrophysics Data System (ADS)

Zarrin, Naima; Husain, Shahid

2018-05-01

Pure and Co doped Lanthanum chromite (LaCrO3) nanoparticles, LaCr1-xCoxO3 (0≤x≤0.3), have been synthesized through sol-gel process and their structural, morphological and dielectric properties have been studied. X ray diffraction patterns reveal that the samples are in single phase having orthorhombic structure with Pnma space group. Structural parameters are refined by Rietveld refinement using Fullprof software. Lattice parameters and unit cell volume are found to decrease with increase in Co doping. Crystallite size is calculated using Scherrer equation and is also found to decrease with increase in Co concentration. Surface morphology is examined using SEM-EDX analysis, which confirms the formation of regular and homogeneous samples without any impurities. The value of dielectric constant (ɛ') decreases with the increase in frequency while it enhances with the increase in Co concentration. The log (ɛ'×f) versus log (f) graphs have been plotted to verify the universal dielectric response (UDR) model. All the samples follow UDR model in the low frequency range.

Emerging terahertz photodetectors based on two-dimensional materials

NASA Astrophysics Data System (ADS)

Yang, Jie; Qin, Hua; Zhang, Kai

2018-01-01

Inspired by the innovations in photonics and nanotechnology, the remarkable properties of two-dimensional (2D) materials have renewed interest for the development of terahertz (THz) photodetectors. The versatility of these materials enables ultrafast and ultrasensitive photodetection of THz radiation at room temperature. The atomically thin characteristic together with van der Waals interactions among the layers make it easy to scaling down and integrate with other 2D materials based devices, as well as silicon chips. Efforts have increased fast in the past decade in developing proof-of-concept and the further prospective THz photodetectors based on 2D materials. Here, the recent progress on the exploring of THz photodetectors based on 2D materials is reviewed. We summarized the THz photodetectors under different physical mechanism and introduced the state-of-the-art THz photodetectors based on various promising 2D materials, such as graphene, transition metal dichalcogenides (TMDCs), black phosphorus (BP) and topological insulators (TIs). A brief discussion on the remaining challenges and a perspective of the 2D materials based THz photodetectors are also given.

Identification of lanthanum-specific peptides for future recycling of rare earth elements from compact fluorescent lamps.

PubMed

Lederer, Franziska L; Curtis, Susan B; Bachmann, Stefanie; Dunbar, W Scott; MacGillivray, Ross T A

2017-05-01

As components of electronic scrap, rare earth minerals are an interesting but little used source of raw materials that are highly important for the recycling industry. Currently, there exists no cost-efficient technology to separate rare earth minerals from an electronic scrap mixture. In this study, phage surface display has been used as a key method to develop peptides with high specificity for particular inorganic targets in electronic scrap. Lanthanum phosphate doped with cerium and terbium as part of the fluorescent phosphors of spent compact fluorescent lamps (CFL) was used as a target material of economic interest to test the suitability of the phage display method to the separation of rare earth minerals. One random pVIII phage library was screened for peptide sequences that bind specifically to the fluorescent phosphor LaPO 4 :Ce 3+ ,Tb 3+ (LAP). The library contained at least 100 binding pVIII peptides per phage particle with a diversity of 1 × 10 9 different phage per library. After three rounds of enrichment, a phage clone containing the surface peptide loop RCQYPLCS was found to bind specifically to LAP. Specificity and affinity of the identified phage bound peptide was confirmed by using binding and competition assays, immunofluorescence assays, and zeta potential measurements. Binding and immunofluorescence assays identified the peptide's affinity for the fluorescent phosphor components CAT (CeMgAl 11 O 19 :Tb 3+ ) and BAM (BaMgAl 10 O 17 :Eu 2+ ). No affinity was found for other fluorescent phosphor components such as YOX (Y 2 O 3 :Eu 3+ ). The binding specificity of the RCQYPLCS peptide loop was improved 3-51-fold by using alanine scanning mutagenesis. The identification of peptides with high specificity and affinity for special components in the fluorescent phosphor in CFLs provides a potentially new strategic approach to rare earth recycling. Biotechnol. Bioeng. 2017;114: 1016-1024. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals

DNA-based nonlinear photonic materials

NASA Astrophysics Data System (ADS)

Heckman, Emily M.; Grote, James G.; Yaney, Perry P.; Hopkins, F. K.

2004-10-01

Deoxyribonucleic acid (DNA), extracted from salmon sperm through an enzyme isolation process, is a by-product of Japan"s fishing industry. To make DNA a suitable material for nonlinear optic (NLO) applications, it is precipitated with a surfactant complex, hexadecyltrimethlammonium chloride (CTMA). Preliminary characterization studies suggest DNA-CTMA may be a suitable host material for guest-host NLO polymer based electro-optic (EO) waveguide devices. The optical and electromagnetic properties of DNA-CTMA, as well as the development and EO measurement of a disperse red 1 (DR1) guest / DNA/CTMA host NLO material, are reported. Comparisons to a DR1 guest / poly(methyl methacrylate) (PMMA) host NLO material are made.

Manganese oxide-based materials as electrochemical supercapacitor electrodes.

PubMed

Wei, Weifeng; Cui, Xinwei; Chen, Weixing; Ivey, Douglas G

2011-03-01

Electrochemical supercapacitors (ECs), characteristic of high power and reasonably high energy densities, have become a versatile solution to various emerging energy applications. This critical review describes some materials science aspects on manganese oxide-based materials for these applications, primarily including the strategic design and fabrication of these electrode materials. Nanostructurization, chemical modification and incorporation with high surface area, conductive nanoarchitectures are the three major strategies in the development of high-performance manganese oxide-based electrodes for EC applications. Numerous works reviewed herein have shown enhanced electrochemical performance in the manganese oxide-based electrode materials. However, many fundamental questions remain unanswered, particularly with respect to characterization and understanding of electron transfer and atomic transport of the electrochemical interface processes within the manganese oxide-based electrodes. In order to fully exploit the potential of manganese oxide-based electrode materials, an unambiguous appreciation of these basic questions and optimization of synthesis parameters and material properties are critical for the further development of EC devices (233 references).

Molten carbonate fuel cell matrices

DOEpatents

Vogel, Wolfgang M.; Smith, Stanley W.

1985-04-16

A molten carbonate fuel cell including a cathode electrode of electrically conducting or semiconducting lanthanum containing material and an electrolyte containing matrix of an electrically insulating lanthanum perovskite. In addition, in an embodiment where the cathode electrode is LaMnO.sub.3, the matrix may include LaAlO.sub.3 or a lithium containing material such as LiAlO.sub.2 or Li.sub.2 TiO.sub.3.

Nanoporous sorbent material as an oral phosphate binder and for aqueous phosphate, chromate, and arsenate removal

PubMed Central

Sangvanich, Thanapon; Ngamcherdtrakul, Worapol; Lee, Richard; Morry, Jingga; Castro, David; Fryxell, Glen E.; Yantasee, Wassana

2014-01-01

Phosphate removal is both biologically and environmentally important. Biologically, hyperphosphatemia is a critical condition in end-stage chronic kidney disease patients. Patients with hyperphosphatemia are treated long-term with oral phosphate binders to prevent phosphate absorption to the body by capturing phosphate in the gastrointestinal (GI) tract followed by fecal excretion. Environmentally, phosphate levels in natural water resources must be regulated according to limits set forth by the US Environmental Protection Agency. By utilizing nanotechnology and ligand design, we developed a new material to overcome limitations of traditional sorbent materials such as low phosphate binding capacity, slow binding kinetics, and negative interference by other anions. A phosphate binder based on iron-ethylenediamine on nanoporous silica (Fe-EDA-SAMMS) has been optimized for substrates and Fe(III) deposition methods. The Fe-EDA-SAMMS material had a 4-fold increase in phosphate binding capacity and a broader operating pH window compared to other reports. The material had a faster phosphate binding rate and was significantly less affected by other anions than Sevelamer HCl, the gold standard oral phosphate binder, and AG® 1-X8, a commercially available anion exchanger. It had less cytotoxicity to Caco-2 cells than lanthanum carbonate, another prescribed oral phosphate binder. The Fe-EDA-SAMMS also had high capacity for arsenate and chromate, two of the most toxic anions in natural water. PMID:25554735

Resilient Modulus Characterization of Alaskan Granular Base Materials

DOT National Transportation Integrated Search

2010-08-01

Resilient modulus (MR) of base course material is an important material input for : pavement design. In Alaska, due to distinctiveness of local climate, material source, : fines content and groundwater level, resilient properties of D-1 granular base...

Recent progress in graphene-material-based optical sensors.

PubMed

Deng, Xianghua; Tang, Hao; Jiang, Jianhui

2014-11-01

Graphene material has been widely used for optical sensors owing to its excellent properties, including high-energy transfer efficiency, large surface area, and great biocompatibility. Different analytes such as nucleic acids, proteins, and small molecules can be detected by graphene-material-based optical sensors. This review provides a comprehensive discussion of graphene-material-based optical sensors focusing on detection mechanisms and biosensor designs. Challenges and future perspectives for graphene-material-based optical sensors are also presented.

Oriented conductive oxide electrodes on SiO2/Si and glass

DOEpatents

Jia, Quanxi; Arendt, Paul N.

2001-01-01

A thin film structure is provided including a silicon substrate with a layer of silicon dioxide on a surface thereof, and a layer of cubic oxide material deposited upon the layer of silicon dioxide by ion-beam-assisted-deposition, said layer of cubic oxide material characterized as biaxially oriented. Preferably, the cubic oxide material is yttria-stabilized zirconia. Additional thin layers of biaxially oriented ruthenium oxide or lanthanum strontium cobalt oxide are deposited upon the layer of yttria-stabilized zirconia. An intermediate layer of cerium oxide is employed between the yttria-stabilized zirconia layer and the lanthanum strontium cobalt oxide layer. Also, a layer of barium strontium titanium oxide can be upon the layer of biaxially oriented ruthenium oxide or lanthanum strontium cobalt oxide. Also, a method of forming such thin film structures, including a low temperature deposition of a layer of a biaxially oriented cubic oxide material upon the silicon dioxide surface of a silicon dioxide/silicon substrate is provided.

[Preface for special issue on bio-based materials (2016)].

PubMed

Weng, Yunxuan

2016-06-25

Bio-based materials are new materials or chemicals with renewable biomass as raw materials such as grain, legume, straw, bamboo and wood powder. This class of materials includes bio-based polymer, biobased fiber, glycotechnology products, biobased rubber and plastics produced by biomass thermoplastic processing and basic biobased chemicals, for instance, bio-alcohols, organic acids, alkanes, and alkenes, obtained by bio-synthesis, bio-processing and bio-refinery. Owing to its environmental friendly and resource conservation, bio-based materials are becoming a new dominant industry taking the lead in the world scientific and technological innovation and economic development. An overview of bio-based materials development is reported in this special issue, and the industrial status and research progress of the following aspects, including biobased fiber, polyhydroxyalkanoates, biodegradable mulching film, bio-based polyamide, protein based biomedical materials, bio-based polyurethane, and modification and processing of poly(lactic acid), are introduced.

Protein-Based Drug-Delivery Materials

PubMed Central

Jao, Dave; Xue, Ye; Medina, Jethro; Hu, Xiao

2017-01-01

There is a pressing need for long-term, controlled drug release for sustained treatment of chronic or persistent medical conditions and diseases. Guided drug delivery is difficult because therapeutic compounds need to survive numerous transport barriers and binding targets throughout the body. Nanoscale protein-based polymers are increasingly used for drug and vaccine delivery to cross these biological barriers and through blood circulation to their molecular site of action. Protein-based polymers compared to synthetic polymers have the advantages of good biocompatibility, biodegradability, environmental sustainability, cost effectiveness and availability. This review addresses the sources of protein-based polymers, compares the similarity and differences, and highlights characteristic properties and functionality of these protein materials for sustained and controlled drug release. Targeted drug delivery using highly functional multicomponent protein composites to guide active drugs to the site of interest will also be discussed. A systematical elucidation of drug-delivery efficiency in the case of molecular weight, particle size, shape, morphology, and porosity of materials will then be demonstrated to achieve increased drug absorption. Finally, several important biomedical applications of protein-based materials with drug-delivery function—including bone healing, antibiotic release, wound healing, and corneal regeneration, as well as diabetes, neuroinflammation and cancer treatments—are summarized at the end of this review. PMID:28772877

Protein-Based Drug-Delivery Materials.

PubMed

Jao, Dave; Xue, Ye; Medina, Jethro; Hu, Xiao

2017-05-09

There is a pressing need for long-term, controlled drug release for sustained treatment of chronic or persistent medical conditions and diseases. Guided drug delivery is difficult because therapeutic compounds need to survive numerous transport barriers and binding targets throughout the body. Nanoscale protein-based polymers are increasingly used for drug and vaccine delivery to cross these biological barriers and through blood circulation to their molecular site of action. Protein-based polymers compared to synthetic polymers have the advantages of good biocompatibility, biodegradability, environmental sustainability, cost effectiveness and availability. This review addresses the sources of protein-based polymers, compares the similarity and differences, and highlights characteristic properties and functionality of these protein materials for sustained and controlled drug release. Targeted drug delivery using highly functional multicomponent protein composites to guide active drugs to the site of interest will also be discussed. A systematical elucidation of drug-delivery efficiency in the case of molecular weight, particle size, shape, morphology, and porosity of materials will then be demonstrated to achieve increased drug absorption. Finally, several important biomedical applications of protein-based materials with drug-delivery function-including bone healing, antibiotic release, wound healing, and corneal regeneration, as well as diabetes, neuroinflammation and cancer treatments-are summarized at the end of this review.

Gamma ray induced decomposition of double nitrates of lanthanum and cerium with some mono and bivalent cations in solid state

NASA Astrophysics Data System (ADS)

Kulkarni, S. P.; Garg, A. N.

Gamma ray induced decomposition of two series of double nitrates; 2M INO 3⋯Ln(NO 3) 3⋯ x H 2O (where MI = NH+4, Na+, K+, Rb+, Cs+; LnIII = La3+, Ce3+ and x = 2 or 4) and 3M II(NO 3) 2·2Ln III(NO 3) 3⋯24H 2O (where MII = Mg2+, Co2+, Zn2+; LnIII = La3+, Ce3+) has been studied in solid state over a wide absorbed dose range at room temperature. G(NO -2) values have been found to depend on the absorbed dose and the nature of cation in both the series of double salts. Radiation sensitivity of lanthanum double nitrates with monovalent cations at an absorbed dose of 158 kGy follows the order NH +4 < Rb + ≅ Cs + < Na + < K + and those of cerium NH +4 < Rb + lanthanum double nitrates with bivalent cations at an absorbed dose of 206 kGy range from 0.22 to 1.05 and follow the order Zn 2+ < Co 2+ < Mg 2+ while for cerium salts are in the range 0.62-0.91 in the order Zn 2+ ≅ Co 2+ < Mg 2+. In fact double nitrates of cerium with Zn 2+ and Co 2+ exhibit almost similar G(NO -2) values over the dose range 5-640 kGy. X-ray powder diffraction patterns of the irradiated Mg-La double salt indicate the possibility of structural phase transformation at certain doses.

Structural transition in lanthanum gallate and transformation of the fine structure of the EPR spectrum of a Gd3+ impurity center

NASA Astrophysics Data System (ADS)

Vazhenin, V. A.; Guseva, V. B.; Fokin, A. V.; Potapov, A. P.; Artyomov, M. Yu.

2011-04-01

Abrupt changes in resonance positions, hysteretic temperature behavior, and coexistence of phases, which indicate a first-order phase transition, have been revealed from measurements of temperature dependences of the EPR spectra of Gd3+ and Mn4+ centers in the vicinity of the structural transition of lanthanum gallate. The transformation of monoclinic Gd3+ centers into trigonal Gd3+ centers upon the phase transition has been used to estimate the adequacy of two approximations of the superposition model for parameters of the zero-field splitting of the ground state.

FeOx‐Based Materials for Electrochemical Energy Storage

PubMed Central

Ma, Jingyi; Guo, Xiaotian; Yan, Yan; Xue, Huaiguo

2018-01-01

Abstract Iron oxides (FeOx), such as Fe2O3 and Fe3O4 materials, have attracted much attention because of their rich abundance, low cost, and environmental friendliness. However, FeOx, which is similar to most transition metal oxides, possesses a poor rate capability and cycling life. Thus, FeOx‐based materials consisting of FeOx, carbon, and metal‐based materials have been widely explored. This article mainly discusses FeOx‐based materials (Fe2O3 and Fe3O4) for electrochemical energy storage applications, including supercapacitors and rechargeable batteries (e.g., lithium‐ion batteries and sodium‐ion batteries). Furthermore, future perspectives and challenges of FeOx‐based materials for electrochemical energy storage are briefly discussed.

Photodiodes based in La0.7Sr0.3MnO3/single layer MoS2 hybrid vertical heterostructures

NASA Astrophysics Data System (ADS)

Niu, Yue; Frisenda, Riccardo; Svatek, Simon A.; Orfila, Gloria; Gallego, Fernando; Gant, Patricia; Agraït, Nicolás; Leon, Carlos; Rivera-Calzada, Alberto; Pérez De Lara, David; Santamaria, Jacobo; Castellanos-Gomez, Andres

2017-09-01

The fabrication of artificial materials by stacking of individual two-dimensional (2D) materials is amongst one of the most promising research avenues in the field of 2D materials. Moreover, this strategy to fabricate new man-made materials can be further extended by fabricating hybrid stacks between 2D materials and other functional materials with different dimensionality making the potential number of combinations almost infinite. Among all these possible combinations, mixing 2D materials with transition metal oxides can result especially useful because of the large amount of interesting physical phenomena displayed separately by these two material families. We present a hybrid device based on the stacking of a single layer MoS2 onto a lanthanum strontium manganite (La0.7Sr0.3MnO3) thin film, creating an atomically thin device. It shows a rectifying electrical transport with a ratio of 103, and a photovoltaic effect with V oc up to 0.4 V. The photodiode behaviour arises as a consequence of the different doping character of these two materials. This result paves the way towards combining the efforts of these two large materials science communities.

Biodegradable soy protein isolate-based materials: a review.

PubMed

Song, Fei; Tang, Dao-Lu; Wang, Xiu-Li; Wang, Yu-Zhong

2011-10-10

Recently, there is an increasing interest of using bio-based polymers instead of conventional petroleum-based polymers to fabricate biodegradable materials. Soy protein isolate (SPI), a protein with reproducible resource, good biocompatibility, biodegradability, and processability, has a significant potential in the food industry, agriculture, bioscience, and biotechnology. Up to now, several technologies have been applied to prepare SPI-based materials with equivalent or superior physical and mechanical properties compared with petroleum-based materials. The aim of this review is focused on discussion of the advantages and limitations of native SPI as well as the bulk and surface modification strategies for SPI. Moreover, some applications of SPI-based materials, especially for food preservation and packaging technology, were discussed.

Air electrode composition for solid oxide fuel cell

DOEpatents

Kuo, Lewis; Ruka, Roswell J.; Singhal, Subhash C.

1999-01-01

An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell.

Electrical characteristics of paraelectric lead lanthanum zirconium titanate thin films for dynamic random access memory applications

NASA Astrophysics Data System (ADS)

Jones, R. E., Jr.; Maniar, P. D.; Olowolafe, J. O.; Campbell, A. C.; Mogab, C. J.

1992-02-01

Paraelectric lead lanthanum zirconium titanate (PLZT) films, 150 nm thick, were deposited using a spin-coat, sol-gel process followed by a 650 °C oxygen anneal. X-ray diffraction indicated complete conversion to the perovskite phase. Sputter-deposited platinum electrodes were employed with the PLZT films to form thin-film capacitors with the best combination of high charge storage density (26.1 μC/cm2 at 3 V and 36.4 μC/cm2 at 5 V) and leakage current density (0.2 μA/cm2 at 3 V and 0.5 μA/cm2 at 5 V ) reported to date. The electrical characteristics of these thin-film capacitors meet the requirements for a planar bit cell capacitor for 64-Mbit dynamic random access memories.

Functional materials based on nanocrystalline cellulose

NASA Astrophysics Data System (ADS)

Surov, O. V.; Voronova, M. I.; Zakharov, A. G.

2017-10-01

The data on the synthesis of functional materials based on nanocrystalline cellulose (NCC) published over the past 10 years are analyzed. The liquid-crystal properties of NCC suspensions, methods of investigation of NCC suspensions and films, conditions for preserving chiral nematic structure in the NCC films after removal of the solvent and features of templated sol-gel synthesis of functional materials based on NCC are considered. The bibliography includes 106 references.

Conductive polymer-based material

DOEpatents

McDonald, William F [Utica, OH; Koren, Amy B [Lansing, MI; Dourado, Sunil K [Ann Arbor, MI; Dulebohn, Joel I [Lansing, MI; Hanchar, Robert J [Charlotte, MI

2007-04-17

Disclosed are polymer-based coatings and materials comprising (i) a polymeric composition including a polymer having side chains along a backbone forming the polymer, at least two of the side chains being substituted with a heteroatom selected from oxygen, nitrogen, sulfur, and phosphorus and combinations thereof; and (ii) a plurality of metal species distributed within the polymer. At least a portion of the heteroatoms may form part of a chelation complex with some or all of the metal species. In many embodiments, the metal species are present in a sufficient concentration to provide a conductive material, e.g., as a conductive coating on a substrate. The conductive materials may be useful as the thin film conducting or semi-conducting layers in organic electronic devices such as organic electroluminescent devices and organic thin film transistors.

Optical and magnetic properties of zinc oxide quantum dots doped with cobalt and lanthanum.

PubMed

Yu, Shiyong; Zhao, Jing; Su, Hai-Quan

2013-06-01

Cobalt and Lanthanum-doped ZnO QDs are synthesized by a modified sol-gel method under atmospheric conditions. The as-prepared quantum dots are characterized by X-ray powder diffraction (XRD), energy dispersive X-ray (EDX) analysis and high resolution transmission electron microscopy (HRTEM). The optical properties of the products are studied by fluorescent spectroscopy. With a proper Co and La doping, these nanoparticles possess exceptionally small size and enhanced fluorescence. Hysteresis loops of un-doped ZnO QDs and Co and La-doped ZnO QDs indicate that both the samples show ferromagnetic behavior at room temperature. Finally, these nanoparticles can label the BGC 803 cells successfully in short time and present no evidence of toxicity or adverse affect on cell growth even at the concentration up to 1 mM. We expect that the as-prepared Co and La-doped ZnO QDs can provide a better reliability of the collected data and find promising applications in biological, medical and other fields.

Simple preparation of fluorescent composite films based on cerium and europium doped LaF3 nanoparticles

NASA Astrophysics Data System (ADS)

Secco, Henrique de L.; Ferreira, Fabio F.; Péres, Laura O.

2018-03-01

The combination of materials to form hybrids with unique properties, different from those of the isolated components, is a strategy used to prepare functional materials with improved properties aiming to allow their application in specific fields. The doping of lanthanum fluoride with other rare earth elements is used to obtain luminescent particles, which may be useful to the manufacturing of electronic devices' displays and biological markers, for instance. The application of the powder of nanoparticles has limitations in some fields; to overcome this, the powder may be incorporated in a suitable polymeric matrix. In this work, lanthanum fluoride nanoparticles, undoped and doped with cerium and europium, were synthesized through the co-precipitation method in aqueous solution. Aiming the formation of solid state films, composites of nanoparticles in an elastomeric matrix, the nitrile rubber (NBR), were prepared. The flexibility and the transparency of the matrix in the regions of interest are advantages for the application of the luminescent composites. The composites were applied as films using the casting and the spin coating techniques and luminescent materials were obtained in the samples doped with europium and cerium. Scanning electron microscopy images showed an adequate dispersion of the particles in the matrix in both film formation techniques. Aggregates of the particles were detected in the samples which may affect the uniformity of the emission of the composites.

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

PubMed

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

2011-06-01

Lanthanum carbonate (LC) is used to treat hyperphosphatemia. The purpose of this study was to investigate the signal intensity (SI) of LC on magnetic resonance imaging (MRI) scans of phantoms. 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 bottles. Four intact tablets were placed in plastic bottles that did or did not contain distilled water or agar. Two radiologists consensually evaluated T1- and T2-weighted images (WIs) obtained with 1.5- and 3.0-T MRI systems for the SI of unground and ground tablets. On T1- and T2WI, the SIs of the LC suspensions and the solvents alone were similar; the SIs of unground tablets alone and of the air were also similar. Unground tablets in phantoms filled with solvent exhibited lower SI than the solvent. Ground tablets in suspension were not visualized on MRI or computed tomography. These results remained unchanged regardless of differences in magnetic field strength or the solvent used. Ground LC had no contrast enhancement effect on T1WI; on T2WI it did not affect the SI of the solvent. Unground LC tablets may be visualized as a "filling defect" on MRI.

A Russian record of a Middle Ordovician meteorite shower: Extraterrestrial chromite at Lynna River, St. Petersburg region

NASA Astrophysics Data System (ADS)

Lindskog, Anders; Schmitz, Birger; Cronholm, Anders; Dronov, Andrei

2012-08-01

Numerous fossil meteorites and high concentrations of sediment-dispersed extraterrestrial chromite (EC) grains with ordinary chondritic composition have previously been documented from 467 ± 1.6 Ma Middle Ordovician (Darriwilian) strata. These finds probably reflect a temporarily enhanced influx of L-chondritic matter, following the disruption of the L-chondrite parent body in the asteroid belt 470 ± 6 Ma. In this study, a Volkhovian-Kundan limestone/marl succession at Lynna River, northwestern Russia, has been searched for EC grains (>63 μm). Eight samples, forming two separate sample sets, were collected. Five samples from strata around the Asaphus expansus-A. raniceps trilobite Zone boundary, in the lower-middle Kundan, yielded a total of 496 EC grains in 65.5 kg of rock (average 7.6 EC grains kg-1, but up to 10.2 grains kg-1). These are extremely high concentrations, three orders of magnitude higher than "background" levels in similar condensed sediment from other periods. EC grains are typically about 50 times more abundant than terrestrial chrome spinel in the samples and about as common as terrestrial ilmenite. Three stratigraphically lower lying samples, close to the A. lepidurus-A. expansus trilobite Zone boundary, at the Volkhov-Kunda boundary, yielded only two EC grains in 38.2 kg of rock (0.05 grains kg-1). The lack of commonly occurring EC grains in the lower interval probably reflects that these strata formed before the disruption of the L-chondrite parent body. The great similarity in EC chemical composition between this and other comparable studies indicates that all or most EC grains in these Russian mid-Ordovician strata share a common source--the L-chondrite parent body.

Inhibition mechanism of lanthanum ion on the activity of horseradish peroxidase in vitro

NASA Astrophysics Data System (ADS)

Guo, Shaofen; Wang, Lihong; Lu, Aihua; Lu, Tianhong; Ding, Xiaolan; Huang, Xiaohua

2010-02-01

In order to understand the inhibition mechanism of lanthanum ion (La 3+) on the activity of horseradish peroxidase (HRP), the effects of La 3+ on the activity, electron transfer and conformation of HRP in vitro were investigated by using cyclic voltammetry (CV), atomic force microscopy (AFM), circular dichroism (CD), high performance liquid chromatography (HPLC), matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF/MS) and inductively coupled plasma mass spectrometry (ICP-MS). It was found that La 3+ can combine with the amide groups of the polypeptide chain in HRP molecule, forming the complex of La 3+ and HRP (La-HRP). The formation of the La-HRP complex causes the destruction of the native structure of HRP molecule, leading to the decrease in the non-planarity of the porphyrin ring in the heme group of HRP molecule, and then in the exposure extent of active center, Fe(III) of the porphyrin ring of HRP molecule. Thus, the direct electrochemical and catalytic activities of HRP are decreased. It is a possible inhibition mechanism of La 3+ on the activity of peroxidase.

High-resolution analyses reveal structural diversity patterns of microbial communities in Chromite Ore Processing Residue (COPR) contaminated soils.

PubMed

Min, Xiaobo; Wang, Yangyang; Chai, Liyuan; Yang, Zhihui; Liao, Qi

2017-09-01

To explore how heavy metal contamination in Chromite Ore Processing Residue (COPR) disposal sites determine the dissimilarities of indigenous microbial communities, 16S rRNA gene MiSeq sequencing and advanced statistical methods were applied. 13 soil samples were collected from three COPR disposal sites in Mouding of southwestern, Shangnan of northwestern and Yima of central China. The results of analyses of variance (ANOVA), similarities (ANOSIM), and non-metric multidimensional scaling (NMDS) showed that the structural diversity of the microbial communities in the samples with high total chromium (Cr) content (more than 300 mg kg -1 ; High group) were significantly lesser than in the Low group (less than 90 mg kg -1 ) regardless of their geographical distribution. But their diversity had virtually rehabilitated under the pressures of long-term metal contamination. Furthermore, the similarity percentage (SIMPER) analysis indicated that the major dissimilarity contributors Micrococcaceae, Delftia, and Streptophyta, possibly having Cr(VI)-resistant and/or Cr(VI)-reducing capability, were dominant in the High group, while Ramlibacter and Gemmatimonas with potential resistances to other heavy metals were prevalent in the Low group. In addition, the multivariate regression tree (MRT), aggregated boosted tree (ABT), and Mantel test revealed that total Cr content affiliated with Cr(VI) was the principal factor shaping the dissimilarities between the soil microbial communities in the COPR sites. Our findings provide a deep insight of the influence of these heavy metals on the microbial communities in the COPR disposal sites and will facilitate bioremediation on such site. Copyright © 2017 Elsevier Ltd. All rights reserved.

Local structure and oxide-ion conduction mechanism in apatite-type lanthanum silicates.

PubMed

Masson, Olivier; Berghout, Abid; Béchade, Emilie; Jouin, Jenny; Thomas, Philippe; Asaka, Toru; Fukuda, Koichiro

2017-01-01

The local structure of apatite-type lanthanum silicates of general formula La 9.33+x (SiO 4 ) 6 O 2+3x/2 has been investigated by combining the atomic pair distribution function (PDF) method, conventional X-ray and neutron powder diffraction (NPD) data and density functional theory (DFT) calculations. DFT was used to build structure models with stable positions of excess oxide ions within the conduction channel. Two stable interstitial positions were obtained in accordance with literature, the first one located at the very periphery of the conduction channel, neighbouring the SiO 4 tetrahedral units, and the second one closer to the channel axis. The corresponding PDFs and average structures were then calculated and tested against experimental PDFs obtained by X-ray total scattering and NPD Rietveld refinements results gathered from literature. It was shown that of the two stable interstitial positions obtained with DFT only the second one located within the channel is consistent with experimental data. This result consolidates one of the two main conduction mechanisms along the c-axis reported in the literature, namely the one involving cooperative movement of O4 and Oi ions.

Local structure and oxide-ion conduction mechanism in apatite-type lanthanum silicates

PubMed Central

Masson, Olivier; Berghout, Abid; Béchade, Emilie; Jouin, Jenny; Thomas, Philippe; Asaka, Toru; Fukuda, Koichiro

2017-01-01

Abstract The local structure of apatite-type lanthanum silicates of general formula La9.33+x(SiO4)6O2+3x/2 has been investigated by combining the atomic pair distribution function (PDF) method, conventional X-ray and neutron powder diffraction (NPD) data and density functional theory (DFT) calculations. DFT was used to build structure models with stable positions of excess oxide ions within the conduction channel. Two stable interstitial positions were obtained in accordance with literature, the first one located at the very periphery of the conduction channel, neighbouring the SiO4 tetrahedral units, and the second one closer to the channel axis. The corresponding PDFs and average structures were then calculated and tested against experimental PDFs obtained by X-ray total scattering and NPD Rietveld refinements results gathered from literature. It was shown that of the two stable interstitial positions obtained with DFT only the second one located within the channel is consistent with experimental data. This result consolidates one of the two main conduction mechanisms along the c-axis reported in the literature, namely the one involving cooperative movement of O4 and Oi ions. PMID:28970872

Local structure and oxide-ion conduction mechanism in apatite-type lanthanum silicates

NASA Astrophysics Data System (ADS)

Masson, Olivier; Berghout, Abid; Béchade, Emilie; Jouin, Jenny; Thomas, Philippe; Asaka, Toru; Fukuda, Koichiro

2017-12-01

The local structure of apatite-type lanthanum silicates of general formula La9.33+x(SiO4)6O2+3x/2 has been investigated by combining the atomic pair distribution function (PDF) method, conventional X-ray and neutron powder diffraction (NPD) data and density functional theory (DFT) calculations. DFT was used to build structure models with stable positions of excess oxide ions within the conduction channel. Two stable interstitial positions were obtained in accordance with literature, the first one located at the very periphery of the conduction channel, neighbouring the SiO4 tetrahedral units, and the second one closer to the channel axis. The corresponding PDFs and average structures were then calculated and tested against experimental PDFs obtained by X-ray total scattering and NPD Rietveld refinements results gathered from literature. It was shown that of the two stable interstitial positions obtained with DFT only the second one located within the channel is consistent with experimental data. This result consolidates one of the two main conduction mechanisms along the c-axis reported in the literature, namely the one involving cooperative movement of O4 and Oi ions.

Cement-based materials' characterization using ultrasonic attenuation

NASA Astrophysics Data System (ADS)

Punurai, Wonsiri

The quantitative nondestructive evaluation (NDE) of cement-based materials is a critical area of research that is leading to advances in the health monitoring and condition assessment of the civil infrastructure. Ultrasonic NDE has been implemented with varying levels of success to characterize cement-based materials with complex microstructure and damage. A major issue with the application of ultrasonic techniques to characterize cement-based materials is their inherent inhomogeneity at multiple length scales. Ultrasonic waves propagating in these materials exhibit a high degree of attenuation losses, making quantitative interpretations difficult. Physically, these attenuation losses are a combination of internal friction in a viscoelastic material (ultrasonic absorption), and the scattering losses due to the material heterogeneity. The objective of this research is to use ultrasonic attenuation to characterize the microstructure of heterogeneous cement-based materials. The study considers a real, but simplified cement-based material, cement paste---a common bonding matrix of all cement-based composites. Cement paste consists of Portland cement and water but does not include aggregates. First, this research presents the findings of a theoretical study that uses a set of existing acoustics models to quantify the scattered ultrasonic wavefield from a known distribution of entrained air voids. These attenuation results are then coupled with experimental measurements to develop an inversion procedure that directly predicts the size and volume fraction of entrained air voids in a cement paste specimen. Optical studies verify the accuracy of the proposed inversion scheme. These results demonstrate the effectiveness of using attenuation to measure the average size, volume fraction of entrained air voids and the existence of additional larger entrapped air voids in hardened cement paste. Finally, coherent and diffuse ultrasonic waves are used to develop a direct

Ternary Sulfide Infrared Window Materials.

DTIC Science & Technology

1981-10-10

results. Oxalates of the two cations can also be used for those combinations where oxalates of good purity are available. The reaction is: CaCO3 + 2La(OH... hydrothermal condi- tions. At 3000C and 300 bars pressure, CaLa2S4 breaks down completely into a mixture of calcium and lanthanum hydroxides. 3.0 CERAMIC

Ag-doped manganite nanoparticles: new materials for temperature-controlled medical hyperthermia.

PubMed

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

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.

Photocatalytic degradation and photo-Fenton oxidation of Congo red dye pollutants in water using natural chromite—response surface optimization

NASA Astrophysics Data System (ADS)

Shaban, Mohamed; Abukhadra, Mostafa R.; Ibrahim, Suzan S.; Shahien, Mohamed. G.

2017-12-01

Refined natural Fe-chromite was characterized by XRD, FT-IR, reflected polarized microscope, XRF and UV spectrophotometer. Photocatalytic degradation and photo-Fenton oxidation of Congo red dye by Fe-chromite was investigated using 1 mL H2O2. The degradation of dye was studied as a function of illumination time, chromite mass, initial dye concentration, and pH. Fe-chromite acts as binary oxide system from chromium oxide and ferrous oxide. Thus, it exhibits photocatalytic properties under UV illumination and photo-Fenton oxidation after addition of H2O2. The degradation in the presence of H2O2 reached the equilibrium stage after 8 h (59.4%) but in the absence of H2O2 continued to 12 h (54.6%). Photocatalytic degradation results fitted well with zero, first order and second order kinetic model but it represented by second order rather than by the other models. While the photo-Fenton oxidation show medium fitting with the second order kinetic model only. The values of kinetic rate constants for the photo-Fenton oxidation were greater than those for the photocatalytic degradation. Thus, degradation of Congo red dye using chromite as catalyst is more efficient by photo-Fenton oxidation. Based on the response surface analysis, the predicted optimal conditions for maximum removal of Congo red dye by photocatalytic degradation (100%) were 12 mg/l, 0.14 g, 3, and 11 h for dye concentration, chromite mass, pH, and illumination time, respectively. Moreover, the optimum condition for photo-Fenton oxidation of dye (100%) is 13.5 mg/l, 0.10 g, 4, and 10 h, respectively.

Developing Novel Protein-based Materials using Ultrabithorax: Production, Characterization, and Functionalization

NASA Astrophysics Data System (ADS)

Huang, Zhao

2011-12-01

Compared to 'conventional' materials made from metal, glass, or ceramics, protein-based materials have unique mechanical properties. Furthermore, the morphology, mechanical properties, and functionality of protein-based materials may be optimized via sequence engineering for use in a variety of applications, including textile materials, biosensors, and tissue engineering scaffolds. The development of recombinant DNA technology has enabled the production and engineering of protein-based materials ex vivo. However, harsh production conditions can compromise the mechanical properties of protein-based materials and diminish their ability to incorporate functional proteins. Developing a new generation of protein-based materials is crucial to (i) improve materials assembly conditions, (ii) create novel mechanical properties, and (iii) expand the capacity to carry functional protein/peptide sequences. This thesis describes development of novel protein-based materials using Ultrabithorax, a member of the Hox family of proteins that regulate developmental pathways in Drosophila melanogaster. The experiments presented (i) establish the conditions required for the assembly of Ubx-based materials, (ii) generate a wide range of Ubx morphologies, (iii) examine the mechanical properties of Ubx fibers, (iv) incorporate protein functions to Ubx-based materials via gene fusion, (v) pattern protein functions within the Ubx materials, and (vi) examine the biocompatibility of Ubx materials in vitro. Ubx-based materials assemble at mild conditions compatible with protein folding and activity, which enables Ubx chimeric materials to retain the function of appended proteins in spatial patterns determined by materials assembly. Ubx-based materials also display mechanical properties comparable to existing protein-based materials and demonstrate good biocompatibility with living cells in vitro. Taken together, this research demonstrates the unique features and future potential of novel Ubx-based

Superconductivity in dense carbon-based materials

DOE PAGES

Lu, Siyu; Liu, Hanyu; Naumov, Ivan I.; ...

2016-03-08

Guided by a simple strategy in searching of new superconducting materials we predict that high temperature superconductivity can be realized in classes of high-density materials having strong sp 3 chemical bonding and high lattice symmetry. Here, we examine in detail sodalite carbon frameworks doped with simple metals such as Li, Na, and Al. Though such materials share some common features with doped diamond, their doping level is not limited and the density of states at the Fermi level in them can be as high as that in the renowned MgB 2. Altogether, with other factors, this boosts the superconducting temperaturemore » (T c) in the materials investigated to higher levels compared to doped diamond. For example, the superconducting T c of sodalite-like NaC 6 is predicted to be above 100 K. This phase and a series of other sodalite-based superconductors are predicted to be metastable phases but are dynamically stable. In owing to the rigid carbon framework of these and related dense carbon-materials, these doped sodalite-based structures could be recoverable as potentially useful superconductors.« less

Powder based superdielectric materials for novel Capacitor design

DTIC Science & Technology

2017-06-01

SUPERDIELECTRIC MATERIALS FOR NOVEL CAPACITOR DESIGN by Clayton W. Petty June 2017 Thesis Advisor: Jonathan Phillips Second Reader: Anthony...thesis 4. TITLE AND SUBTITLE POWDER-BASED SUPERDIELECTRIC MATERIALS FOR NOVEL CAPACITOR DESIGN 5. FUNDING NUMBERS 6. AUTHOR(S) Clayton W...unlimited. POWDER-BASED SUPERDIELECTRIC MATERIALS FOR NOVEL CAPACITOR DESIGN Clayton W. Petty Lieutenant, Junior Grade, United States Navy B.S

Gas-to-particle conversion in the particle precipitation-aided chemical vapor deposition process II. Synthesis of the perovskite oxide yttrium chromite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dieten, V.E.J. van; Dekker, J.P.; Hurkmans, E.J.

1993-11-01

In the particle precipitation-aided chemical vapor deposition process, an aerosol is formed in the gas phase at elevated temperatures. The particles are deposited on a cooled substrate. Coherent layers with a controlled porosity can be obtained by a simultaneous heterogeneous reaction, which interconnects the deposited particles. The synthesis of submicrometer powder of the perovskite oxide yttrium chromite (YCrO[sub 3]) by gas to particle conversion, which is the first step of the PP-CVD process, has been investigated, and preliminary results are shown. The powders have been synthesized using yttrium trichloride vapor (YCl[sub 3]), chromium trichloride vapor (CrCl[sub 3]), and steam andmore » oxygen as reactants. The influence of the input molar ratio of the elements on the composition and characteristics of the powders has been investigated. Phase composition has been determined by X-ray diffraction (XRD). The powders have been characterized by transmission electron microscopy (TEM) and sedimentation field flow fractionation (SF[sup 3]). At a reaction temperature of 1283 K the powders consist of the chromium sesquioxide (Cr[sub 2]O[sub 3]), or a mixture of Cr[sub 2]O[sub 3] and YCrO[sub 3]. At stoichiometeric input amounts of metal chlorides and steam the formation of YCrO[sub 3] seems to be favored. 19 refs., 6 figs., 3 tabs.« less

Hexa-μ-chlorido-hexa­chlorido(η6-hexa­methyl­benzene)trialuminium(III)lanthanum(III) benzene solvate

PubMed Central

Filatov, Alexander S.; Gifford, Sarah N.; Kumar, D. Krishna; Petrukhina, Marina A.

2009-01-01

In the title compound, [Al3LaCl12(C12H18)]·C6H6, all mol­ecules are located on a mirror plane. Three chloridoaluminate groups and a hexa­methyl­benzene mol­ecule are bound to the central lanthanum(III) ion, forming a distorted penta­gonal bipyramid with the η6-coordinated arene located at the apical position. The hexa­methyl­benzene ligand disordered between two orientations in a 1:1 ratio is also involved in parallel-slipped π–π stacking inter­molecular inter­actions with a benzene solvent mol­ecule [centroid–centroid distance 3.612 (4) Å]. PMID:21582071

[Current status of bio-based materials industry in China].

PubMed

Diao, Xiaoqian; Weng, Yunxuan; Huang, Zhigang; Yang, Nan; Wang, Xiyuan; Zhang, Min; Jin, Yujuan

2016-06-25

In recent years, bio-based materials are becoming a new dominant industry leading the scientific and technological innovation, and economic development of the world. We reviewed the new development of bio-based materials industry in China, analyzed the entire market of bio-based materials products comprehensively, and also stated the industry status of bio-based chemicals, such as lactic acid, 1,3-propanediol, and succinic acid; biodegradable bio-based polymers, such as co-polyester of diacid and diol, polylactic acid, carbon dioxide based copolymer, polyhydroxyalknoates, polycaprolactone, and thermoplastic bio-based plastics; non-biodegradable bio-based polymers, such as bio-based polyamide, polytrimethylene terephthalate, bio-based polyurethane, and bio-based fibers.

Lanthanum(III)-catalyzed disproportionation of hydrogen peroxide: a heterogeneous generator of singlet molecular oxygen-1O2 (1Deltag)-in near-neutral aqueous and organic media for peroxidation of electron-rich substrates.

PubMed

Nardello, Véronique; Barbillat, Jacques; Marko, Jean; Witte, Peter T; Alsters, Paul L; Aubry, Jean-Marie

2003-01-20

The decomposition of hydrogen peroxide into singlet molecular oxygen-(1)O(2) ((1)Delta(g))-in the presence of lanthanum(iii) salts was studied by monitoring its characteristic IR luminescence at 1270 nm. The process was found to be heterogeneously catalyzed by La(III), provided that the heterogeneous catalyst is generated in situ. The yield of (1)O(2) generation was assessed as 45+/-5 % both in water and in methanol. The pH-dependence on the rate of (1)O(2) generation corresponds to a bell-shaped curve from pH 4.5 to 13 with a maximum around pH 8. The study of the influence of H(2)O(2) showed that the formation of (1)O(2) begins as soon as one equivalent of H(2)O(2) is introduced. It then increases drastically up to two equivalents and more smoothly above. Unlike all other metal salt catalyst systems known to date for H(2)O(2) disproportionation, this chemical source of (1)O(2) is able to generate (1)O(2) not only in basic media, but also under neutral and slightly acidic conditions. In addition, this La-based catalyst system has a very low tendency to induce unwanted oxygenating side reactions, such as epoxidation of alkenes. These two characteristics of the heterogeneous lanthanum catalyst system allow non-photochemical (i.e., "dark") singlet oxygenation of substrate classes that cannot be peroxidized successfully with conventional molybdate catalysts, such as allylic alcohols and alkenyl amines.

Application of graphene oxide/lanthanum-modified carbon paste electrode for the selective determination of dopamine

NASA Astrophysics Data System (ADS)

Ye, Fengying; Feng, Chenqi; Fu, Ning; Wu, Huihui; Jiang, Jibo; Han, Sheng

2015-12-01

A home-made carbon paste electrode (CPE) was reformed by graphene oxide (GO)/lanthanum (La) complexes, and a modified electrode, called GO-La/CPE, was fabricated for the selective determination of dopamine (DA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several factors affecting the electrocatalytic performance of the modified sensor were investigated. Owning to the combination of GO and La ions, the GO-La/CPE sensor exhibited large surface area, well selectivity, good repeatability and stability in the oxidation reaction of DA. At optimal conditions, the response of the GO-La/CPE electrode for determining DA was linear in the region of 0.01-0.1 μM and 0.1-400.0 μM. The limit of detection was down to 0.32 nM (S/N = 3). In addition, this modified electrode was successfully applied to the detection of DA in real urine and serum samples by using standard adding method, showing its promising application in the electroanalysis of real samples.

Dynamic Nuclear Polarization in Samarium Doped Lanthanum Magnesium Nitrate. Ph.D. Thesis - Va. Polytechnic Inst.

NASA Technical Reports Server (NTRS)

Byvik, C. E.

1971-01-01

The dynamic nuclear polarization of hydrogen nuclei by the solid effect in single crystals of samarium doped lanthanum magnesium nitrate (Sm:LMN) was studied theoretically and experimentally. The equations of evolution governing the dynamic nuclear polarization by the solid effect were derived in detail using the spin temperature theory and the complete expression for the steady state enhancement of the nuclear polarization was calculated. Experimental enhancements of the proton polarization were obtained for eight crystals at 9.2 GHz and liquid helium temperatures. The samarium concentration ranged from 0.1 percent to 1.1 percent as determined by X-ray fluorescence. A peak enhancement of 181 was measured for a 1.1 percent Sm:LMN crystal at 3.0 K. The maximum enhancements extrapolated with the theory using the experimental data for peak enhancement versus microwave power and correcting for leakage, agree with the ideal enhancement (240 in this experiment) within experimental error for three of the crystals.

Water vapor movement in freezing aggregate base materials.

DOT National Transportation Integrated Search

2014-06-01

The objectives of this research were to 1) measure the extent to which water vapor movement results in : water accumulation in freezing base materials; 2) evaluate the effect of soil stabilization on water vapor movement : in freezing base materials;...

Magnetization reversal behavior and magnetocaloric effect in SmCr0.85Mn0.15O3 chromites

NASA Astrophysics Data System (ADS)

Kumar, Surendra; Coondoo, Indrani; Vasundhara, M.; Patra, Ajit K.; Kholkin, Andrei L.; Panwar, Neeraj

2017-01-01

We have synthesized SmCr0.85Mn0.15O3 (SCMO) chromites through the ceramic route. The compound crystallized into a distorted orthorhombic structure with the Pnma space group, which was confirmed from the Rietveld refinement of x-ray powder diffraction patterns. Neel temperature, noticed at 168 K from the temperature variation of magnetisation, smaller than that reported for SmCrO3, indicated the influence of Mn3+ substitution on decreasing the antiferromagnetic ordering. A phenomenon of magnetization reversal was observed in the SCMO compound. At low magnetic fields, i.e., 500 Oe, a single compensation temperature (defined as the temperature where magnetization became zero) around 106 K was observed in the field cooled magnetization curve. However, with the application of higher magnetic fields, i.e., under an applied field of 1000 Oe, a second compensation temperature was noticed around 8 K. With a further increase in the magnetic field, the magnetization remained positive in both field cooled and zero field cooled protocols. A normal magnetocaloric effect was observed through an indirect method of field dependence of magnetisation measured in the temperature range of 2-152 K. The magnetic entropy change (-ΔS) of ˜11.36 J kg-1 K-1 along with the relative cooling power (RCP) of ˜175.89 J kg-1 was obtained in the temperature range of 10-20 K for an applied field of 90 kOe, and their values at 50 kOe applied field were, respectively, almost twenty and forty times larger in magnitude in comparison to those for the SmCrO3 compound. The relatively large values of ΔS and RCP make the studied compound a potential candidate for magnetic refrigeration applications at low temperatures.

Materiality in a Practice-Based Approach

ERIC Educational Resources Information Center

Svabo, Connie

2009-01-01

Purpose: The paper aims to provide an overview of the vocabulary for materiality which is used by practice-based approaches to organizational knowing. Design/methodology/approach: The overview is theoretically generated and is based on the anthology Knowing in Organizations: A Practice-based Approach edited by Nicolini, Gherardi and Yanow. The…

The preliminary Long Duration Exposure Facility (LDEF) materials data base

NASA Technical Reports Server (NTRS)

Funk, Joan G.; Strickland, John W.; Davis, John M.

1992-01-01

A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated for LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux), and author(s) or principal investigator(s). The LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which was computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. This paper describes the LDEF Materials Data Base and includes step-by-step example searches using the data base. Information on how to become an authorized user of the system is included.

Computational design of materials for solar hydrogen generation

NASA Astrophysics Data System (ADS)

Umezawa, Naoto

Photocatalysis has a great potential for the production of hydrogen from aquerous solution under solar light. In this talk, two different approaches toward the computational materials desing for solar hydrogen generation will be presented. Tin (Sn), which has two major oxidation states, Sn2+ and Sn4+, is abundant on the earth's crust. Recently, visible-light responsive photocatalytc H2 evolution reaction was identified over a mixed valence tin oxide Sn3O4. We have carried out crystal structure prediction for mixed valence tin oxides in different atomic compositions under ambient pressure condition using advanced computational methods based on the evolutionary crystal-structure search and density-functional theory. The predicted novel crystal structures realize the desirable band gaps and band edge positions for H2 evolution under visible light irradiation. It is concluded that multivalent tin oxides have a great potential as an abundant, cheap and environmentally-benign solar-energy conversion photofunctional materials. Transition metal doping is effective for sensitizing SrTiO3 under visible light. We have theoretically investigated the roles of the doped Cr in STO based on hybrid density-functional calculations. Cr atoms are preferably substituting for Ti under any equilibrium growth conditions. The lower oxidation state Cr3+, which is stabilized under an n-type condition of STO, is found to be advantageous for the photocatalytic performance. It is firther predicted that lanthanum is the best codopant for stabilizing the favorable oxidation state, Cr3+. The prediction was validated by our experiments that La and Cr co-doped STO shows the best performance among examined samples. This work was supported by the Japan Science and Technology Agency (JST) Precursory Research for Embryonic Science and Technology (PRESTO) and International Research Fellow program of Japan Society for the Promotion of Science (JSPS) through project P14207.

RIM as the data base management system for a material properties data base

NASA Technical Reports Server (NTRS)

Karr, P. H.; Wilson, D. J.

1984-01-01

Relational Information Management (RIM) was selected as the data base management system for a prototype engineering materials data base. The data base provides a central repository for engineering material properties data, which facilitates their control. Numerous RIM capabilities are exploited to satisfy prototype data base requirements. Numerical, text, tabular, and graphical data and references are being stored for five material types. Data retrieval will be accomplished both interactively and through a FORTRAN interface. The experience gained in creating and exercising the prototype will be used in specifying requirements for a production system.

Biodegradation of the metallic carcinogen hexavalent chromium Cr(VI) by an indigenously isolated bacterial strain

PubMed Central

Mishra, Susmita

2010-01-01

Background: Hexavalent chromium [Cr(VI)], a potential mutagen and carcinogen, is regularly introduced into the environment through diverse anthropogenic activities, including electroplating, leather tanning, and pigment manufacturing. Human exposure to this toxic metal ion not only causes potential human health hazards but also affects other life forms. The World Health Organization, the International Agency for Research on Cancer, and the Environmental Protection Agency have determined that Cr(VI) compounds are known human carcinogens. The Sukinda valley in Jajpur District, Orissa, is known for its deposit of chromite ore, producing nearly 98% of the chromite ore in India and one of the prime open cast chromite ore mines in the world (CES, Orissa Newsletter). Materials and Methods: Our investigation involved microbial remediation of Cr(VI) without producing any byproduct. Bacterial cultures tolerating high concentrations of Cr were isolated from the soil sample collected from the chromite-contaminated sites of Sukinda, and their bioaccumulation properties were investigated. Strains capable of growing at 250 mg/L Cr(VI) were considered as Cr resistant. Results: The experimental investigation showed the maximum specific Cr uptake at pH 7 and temperature 30°C. At about 50 mg/L initial Cr(VI) concentrations, uptake of the selected potential strain exceeded 98% within 12 h of incubation. The bacterial isolate was identified by 16S rRNA sequencing as Brevebacterium casei. Conclusion: Results indicated promising approach for microbial remediation of effluents containing elevated levels of Cr(VI). PMID:20976016

Carbon-Nanotube-Based Thermoelectric Materials and Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blackburn, Jeffrey L.; Ferguson, Andrew J.; Cho, Chungyeon

Conversion of waste heat to voltage has the potential to significantly reduce the carbon footprint of a number of critical energy sectors, such as the transportation and electricity-generation sectors, and manufacturing processes. Thermal energy is also an abundant low-flux source that can be harnessed to power portable/wearable electronic devices and critical components in remote off-grid locations. As such, a number of different inorganic and organic materials are being explored for their potential in thermoelectric-energy-harvesting devices. Carbon-based thermoelectric materials are particularly attractive due to their use of nontoxic, abundant source-materials, their amenability to high-throughput solution-phase fabrication routes, and the high specificmore » energy (i.e., W g-1) enabled by their low mass. Single-walled carbon nanotubes (SWCNTs) represent a unique 1D carbon allotrope with structural, electrical, and thermal properties that enable efficient thermoelectric-energy conversion. Here, the progress made toward understanding the fundamental thermoelectric properties of SWCNTs, nanotube-based composites, and thermoelectric devices prepared from these materials is reviewed in detail. This progress illuminates the tremendous potential that carbon-nanotube-based materials and composites have for producing high-performance next-generation devices for thermoelectric-energy harvesting.« less

Carbon-Nanotube-Based Thermoelectric Materials and Devices

DOE PAGES

Blackburn, Jeffrey L.; Ferguson, Andrew J.; Cho, Chungyeon; ...

2018-01-22

Conversion of waste heat to voltage has the potential to significantly reduce the carbon footprint of a number of critical energy sectors, such as the transportation and electricity-generation sectors, and manufacturing processes. Thermal energy is also an abundant low-flux source that can be harnessed to power portable/wearable electronic devices and critical components in remote off-grid locations. As such, a number of different inorganic and organic materials are being explored for their potential in thermoelectric-energy-harvesting devices. Carbon-based thermoelectric materials are particularly attractive due to their use of nontoxic, abundant source-materials, their amenability to high-throughput solution-phase fabrication routes, and the high specificmore » energy (i.e., W g-1) enabled by their low mass. Single-walled carbon nanotubes (SWCNTs) represent a unique 1D carbon allotrope with structural, electrical, and thermal properties that enable efficient thermoelectric-energy conversion. Here, the progress made toward understanding the fundamental thermoelectric properties of SWCNTs, nanotube-based composites, and thermoelectric devices prepared from these materials is reviewed in detail. This progress illuminates the tremendous potential that carbon-nanotube-based materials and composites have for producing high-performance next-generation devices for thermoelectric-energy harvesting.« less

Carbon-Nanotube-Based Thermoelectric Materials and Devices.

PubMed

Blackburn, Jeffrey L; Ferguson, Andrew J; Cho, Chungyeon; Grunlan, Jaime C

2018-03-01

Conversion of waste heat to voltage has the potential to significantly reduce the carbon footprint of a number of critical energy sectors, such as the transportation and electricity-generation sectors, and manufacturing processes. Thermal energy is also an abundant low-flux source that can be harnessed to power portable/wearable electronic devices and critical components in remote off-grid locations. As such, a number of different inorganic and organic materials are being explored for their potential in thermoelectric-energy-harvesting devices. Carbon-based thermoelectric materials are particularly attractive due to their use of nontoxic, abundant source-materials, their amenability to high-throughput solution-phase fabrication routes, and the high specific energy (i.e., W g -1 ) enabled by their low mass. Single-walled carbon nanotubes (SWCNTs) represent a unique 1D carbon allotrope with structural, electrical, and thermal properties that enable efficient thermoelectric-energy conversion. Here, the progress made toward understanding the fundamental thermoelectric properties of SWCNTs, nanotube-based composites, and thermoelectric devices prepared from these materials is reviewed in detail. This progress illuminates the tremendous potential that carbon-nanotube-based materials and composites have for producing high-performance next-generation devices for thermoelectric-energy harvesting. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chromium speciation and fractionation in ground and surface waters in the vicinity of chromite ore processing residue disposal sites.

PubMed

Farmer, John G; Thomas, Rhodri P; Graham, Margaret C; Geelhoed, Jeanine S; Lumsdon, David G; Paterson, Edward

2002-04-01

Chromium concentrations of up to 91 mg l(-1) were found by ICP-OES for ground water from nine boreholes at four landfill sites in an area of S.E. Glasgow/S. Lanarkshire where high-lime chromite ore processing residue (COPR) from a local chemical works had been deposited from 1830 to 1968. Surface water concentrations of up to 6.7 mg l(-1) in a local tributary stream fell to 0.11 mg l(-1) in the River Clyde. Two independent techniques of complexation/colorimetry and speciated isotope dilution mass spectrometry (SIDMS) showed that Cr was predominantly (>90%) in hexavalent form (CrVI) as CrO4(2-), as anticipated at the high pH (7.5-12.5) of the sites. Some differences between the implied and directly determined concentrations of dissolved CrIII, however, appeared related to the total organic carbon (TOC) content. This was most significant for the ground water from one borehole that had the highest TOC concentration of 300 mg l(-1) and at which < 3% of Cr was in the form of CrVI. Subsequent ultrafiltration produced significant decreases in Cr concentration with decreasing size fractions, e.g. <0.45 microm, < 100 kDa, <30 kDa and < 1 kDa by the tangential-flow method. As this appeared related more to concentrations of humic substances than of TOC per se, horizontal bed gel electrophoresis of freeze-dried ultrafilter retentates was carried out to further characterise the CrIII-organic complex. This showed for the main Cr-containing fraction, 100 kDa-0.45 microm, that the Cr was associated with a dark brown band characteristic of organic (humic) matter. Comparison of gel electrophoresis and FTIR results for ultrafilter retentates of ground water from this borehole with those for a borehole at another site where CrVI predominated suggested the influence of carboxylate groups, both in reducing CrVI and in forming soluble CrIII-humic complexes. The implications of this for remediation strategies (especially those based on the addition of organic matter) designed to reduce

Wearable energy sources based on 2D materials.

PubMed

Yi, Fang; Ren, Huaying; Shan, Jingyuan; Sun, Xiao; Wei, Di; Liu, Zhongfan

2018-05-08

Wearable energy sources are in urgent demand due to the rapid development of wearable electronics. Besides flexibility and ultrathin thickness, emerging 2D materials present certain extraordinary properties that surpass the properties of conventional materials, which make them advantageous for high-performance wearable energy sources. Here, we provide a comprehensive review of recent advances in 2D material based wearable energy sources including wearable batteries, supercapacitors, and different types of energy harvesters. The crucial roles of 2D materials in the wearable energy sources are highlighted. Based on the current progress, the existing challenges and future prospects are outlined and discussed.

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

DOEpatents

Richards, Von L.; Singhal, Subhash C.; Pal, Uday B.

1992-01-01

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 electrochemical vapor depositing a dense skeletal LaCrO.sub.3 structure, 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.

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

DOEpatents

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

1992-07-21

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.

Molecular Design of Benzodithiophene-Based Organic Photovoltaic Materials.

PubMed

Yao, Huifeng; Ye, Long; Zhang, Hao; Li, Sunsun; Zhang, Shaoqing; Hou, Jianhui

2016-06-22

Advances in the design and application of highly efficient conjugated polymers and small molecules over the past years have enabled the rapid progress in the development of organic photovoltaic (OPV) technology as a promising alternative to conventional solar cells. Among the numerous OPV materials, benzodithiophene (BDT)-based polymers and small molecules have come to the fore in achieving outstanding power conversion efficiency (PCE) and breaking 10% efficiency barrier in the single junction OPV devices. Remarkably, the OPV device featured by BDT-based polymer has recently demonstrated an impressive PCE of 11.21%, indicating the great potential of this class of materials in commercial photovoltaic applications. In this review, we offered an overview of the organic photovoltaic materials based on BDT from the aspects of backbones, functional groups, alkyl chains, and device performance, trying to provide a guideline about the structure-performance relationship. We believe more exciting BDT-based photovoltaic materials and devices will be developed in the near future.

Microstructure evolution and electrical characterization of Lanthanum doped Barium Titanate (BaTiO{sub 3}) ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Billah, Masum, E-mail: masum.buet09@gmail.com; Ahmed, A., E-mail: jhinukbuetmme@gmail.com; Rahman, Md. Miftaur, E-mail: miftaurrahman@mme.buet.ac.bd

2016-07-12

In the current work, we investigated the structural and dielectric properties of Lanthanum oxide (La{sub 2}O{sub 3}) doped Barium Titanate (BaTiO{sub 3}) ceramics and established a correlation between them. Solid state sintering method was used to dope BaTiO{sub 3} with 0.3, 0.5 and 0.7 mole% La{sub 2}O{sub 3} under different sintering parameters. The raw materials used were La{sub 2}O{sub 3} nano powder of ~80 nm grain size and 99.995% purity and BaTiO{sub 3} nano powder of 100 nm grain size and 99.99% purity. Grain size distribution and morphology of fracture surface of sintered pellets were examined by Field Emission Scanningmore » Electron Microscope and X-Ray Diffraction analysis was conducted to confirm the formation of desired crystal structure. The research result reveal that grain size and electrical properties of BaTiO{sub 3} ceramic significantly enhanced for small amount of doping (up to 0.5 mole% La{sub 2}O{sub 3}) and then decreased with increasing doping concentration. Desired grain growth (0.80-1.3 µm) and high densification (<90% theoretical density) were found by proper combination of temperature, sintering parameters and doping concentration. We found the resultant stable value of dielectric constant was 10000-12000 at 100-300 Hz in the temperature range of 30°-50° C for 0.5 mole% La{sub 2}O{sub 3} with corresponding shift of curie temperature around 30° C. So overall this research showed that proper La{sup 3+} concentration can control the grain size, increase density, lower curie temperature and hence significantly improve the electrical properties of BaTiO{sub 3} ceramics.« less

Air electrode composition for solid oxide fuel cell

DOEpatents

Kuo, L.; Ruka, R.J.; Singhal, S.C.

1999-08-03

An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO{sub 3}. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell. 3 figs.

Proceedings of the symposium on Nuclear Radiation Detection Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perry, D.L.; Burger, A.; Franks, L.

2008-07-01

This symposium provides a venue for the presentation of the latest results and discussion of radiation detection materials from both experimental and theoretical standpoints. As advances are made in this area of materials, additional experimental and theoretical approaches are used to both guide the growth of materials and to characterize the materials that have a wide array of applications for detecting different types of radiation. The types of detector materials for semiconductors and scintillators include a variety of molecular compounds such as lanthanum halides (LaX{sub 3}), zinc oxide (ZnO), lead iodide (PbI{sub 2}), cadmium telluride (CdTe), mercuric iodide (HgI{sub 2}),more » thallium bromide (TlBr), as well as others, such as cadmium zinc telluride (CZT). An additional class of scintillators includes those based on organic compounds and glasses. Ideally, desired materials used for radiation detection have attributes such as appropriate-range band-gaps, high atomic numbers of the central element, high densities, performance at room temperature, and strong mechanical properties, and are low cost in terms of their production. There are significant gaps in the knowledge related to these materials that are very important in making radiation detector materials that are higher quality in terms of their reproducible purity, homogeneity, and mechanical integrity. The topics that are the focal point of this symposium address these issues so that much better detectors may be made in the future. Topics cover the following areas: - Material growth: on-going developments regarding cadmium telluride (CdTe), cadmium zinc telluride (CZT), mercuric iodide (HgI{sub 2}), cadmium manganese telluride (CMT), LaX{sub 3}, and all other detector materials; new materials with potential for radiation detection (II-VI, III-VI, III-VII compounds, neutron detectors, nano-materials, and ceramic scintillators); purification techniques; and growth methods; - Characterization

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

NASA Astrophysics Data System (ADS)

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

2015-07-01

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

Poly[[tetra-μ3-acetato-hexa-μ2-acetato­diaqua-μ2-oxalato-tetra­lanthanum(III)] dihydrate

PubMed Central

Di, Wen-Jing; Lan, Shao-Min; Zhang, Qun; Liang, Yun-Xiao

2011-01-01

The title compound, {[La4(CH3CO2)10(C2O4)(H2O)2]·2H2O}n, exhibits a two-dimensional layered structure with the oxalate and acetate ligands acting as bridges. The asymmetric unit contains two crystallographically independent lanthanum(III) ions, half of an oxalate ligand, five acetate ligands, one coordinated water mol­ecule and one uncoordinated water mol­ecule. The coordination numbers of the two La ions are 9 and 10. Adjacent layers of the structure, which extend parallel to (100), are linked by O–H⋯O hydrogen bonds and are also held together by van der Waals inter­actions between the CH3 groups of the acetate anions. PMID:22064832

Graphene-based two-dimensional Janus materials

NASA Astrophysics Data System (ADS)

Ng, Sze-Wing; Noor, Nuruzzaman; Zheng, Zijian

2018-04-01

Two-dimensional (2D) Janus materials with opposing components and properties on two sides have recently attracted fevered attention from various research fields for use as, for example, oil/water separating membranes, interfacial layers for mass transfer, 2D sensors and actuators. The Janus structure allows for a unidirectional transportation system and programmed response to certain stimuli to be achieved. Graphene, the 2D honeycomb network formed from one atomic layer of carbon atoms, has also received substantial research interest because of its intriguing structure and fascinating properties. The high mechanical strength, flexibility and optical transparency make graphene a unique candidate as a building block of 2D Janus materials through asymmetric modification with different functional groups on the graphene surfaces. This article reviews graphene-based 2D Janus materials, starting with a theoretical understanding of the behavior of Janus graphene. Then, different strategies for fabricating Janus graphene and its derivatives are reviewed in detail according to the chemical strategies of the modification methods. The applications of graphene-based Janus materials are discussed with a specific focus on the Janus structures that lead to bandgap engineering, as well as the construction of a responsive system on graphene.

Characterization of asphalt treated base course material

DOT National Transportation Integrated Search

2010-06-01

Asphalt-treated bases are often used in new pavements; the materials are available and low-cost, but there is little data on how these materials perform in cold regions. : This study investigated four ATB types (hot asphalt, emulsion, foamed asphalt,...

Application of Fe-Ti oxide dissolution experiments to the petrogenesis of the Ekati Diamond Mine kimberlites, Northwest Territories, Canada

NASA Astrophysics Data System (ADS)

Kressall, R.; Fedortchouk, Y.; McCammon, C. A.

2015-12-01

Composition of kimberlites is ambiguous due to assimilation and fractional crystallization. We propose that the evolution history of minerals can be used to decipher the magmatic history of kimberlites. We use Fe-Ti oxides (chromite and ilmenite) from six kimberlites from the Ekati Diamond Mine and dissolution experiments to elucidate the petrogenesis of kimberlites. Experiments at 0.1 MPa and variable ƒO2s in a diopside-anorthite melt show that the dissolution rate of ilmenite is highly sensitive to ƒO2. No significant difference was observed in chromite. Zoning in chromite is related to the Fe-content and oxidation state of the melt. Experiments at 1 GPa explore the development of chromite surface resorption features in the system Ca-Mg-Si-H-C-O. Five kimberlites contain a low abundance of ilmenite, owing to a relatively high ƒO2, though ilmenite constituted 65% of oxide macocrysts in one kimberlite. Chromite compositions evolve from Mg-chromite to magnesio-ulvöspinel-magnetite (MUM) in all but one kimberlite where chromite evolves to a pleonaste composition perhaps as a result of rapid emplacement. The high abundance of MUM spinel and low abundance of ilmenite in the matrix could be related to the change in the stable Ti-phase with increasing ƒO2. Core compositions of macrocrysts vary for different mantle sources but rims converge to a composition slightly more oxidized and Mg-rich than chromite from depleted peridotite. Ilmenite commonly has rims composed of perovskite, titanite and MUM. We suggest a model where the kimberlite melt composition is controlled by the co-dissolution and co-precipitation of silicates (predominantly orthopyroxene and olivine) to explain chromite evolution in kimberlites. Resorption-related surface features on chromite macrocrysts show trigon protrusions-depressions on {111} faces and step-like features along the crystal edges resembling products of experiments in H2O fluid. We propose predominantly H2O magmatic fluid in Ekati

Material recognition based on thermal cues: Mechanisms and applications

PubMed Central

Ho, Hsin-Ni

2018-01-01

ABSTRACT Some materials feel colder to the touch than others, and we can use this difference in perceived coldness for material recognition. This review focuses on the mechanisms underlying material recognition based on thermal cues. It provides an overview of the physical, perceptual, and cognitive processes involved in material recognition. It also describes engineering domains in which material recognition based on thermal cues have been applied. This includes haptic interfaces that seek to reproduce the sensations associated with contact in virtual environments and tactile sensors aim for automatic material recognition. The review concludes by considering the contributions of this line of research in both science and engineering. PMID:29687043

Material recognition based on thermal cues: Mechanisms and applications.

PubMed

Ho, Hsin-Ni

2018-01-01

Some materials feel colder to the touch than others, and we can use this difference in perceived coldness for material recognition. This review focuses on the mechanisms underlying material recognition based on thermal cues. It provides an overview of the physical, perceptual, and cognitive processes involved in material recognition. It also describes engineering domains in which material recognition based on thermal cues have been applied. This includes haptic interfaces that seek to reproduce the sensations associated with contact in virtual environments and tactile sensors aim for automatic material recognition. The review concludes by considering the contributions of this line of research in both science and engineering.

Polyazulene based materials for heavy metal ions detection

NASA Astrophysics Data System (ADS)

Oprisanu, A.; Ungureanu, E. M.; Isopescu, R.; Birzan, L.; Mihai, M.; Vasiliu, C.

2017-06-01

Azulene is a special monomer used to functionalize electrodes, due to its spontaneous electron drift from the seven-membered ring to the five-membered ring. The seven-membered ring of the molecule may act as electron acceptor, while the five-membered ring - as electron donor. This leads to very attractive properties for the synthesis of functional advanced materials like: materials with nonlinear optical and photorefractive properties, cathode materials for lithium batteries, or light emitting diodes based on organic materials. Azulene derivatives have been used rarely to the metal ions electroanalysis. Our study concerns the synthesis and electrochemical characterization of a new azulene based monomer 4-(azulen-1-yl)-2,6-bis((E)-2-(thiophen-3-yl)vinyl)pyridine (L). L has been used to obtain modified electrodes by electrochemical polymerization. PolyL films modified electrodes have been characterized by cyclic voltammetry in ferrocene solutions. The complexing properties of polyL based functional materials have been investigated towards heavy metals (Pb, Cd Hg, Cu) by preconcentration - anodic stripping technique in order to analyze the content of these cations from water samples.

Pseudomorphic 2A--> 2M--> 2H phase transitions in lanthanum strontium germanate electrolyte apatites.

PubMed

Pramana, Stevin S; White, T J; Schreyer, Martin K; Ferraris, Cristiano; Slater, Peter R; Orera, Alodia; Bastow, T J; Mangold, Stefan; Doyle, Stephen; Liu, Tao; Fajar, Andika; Srinivasan, Madhavi; Baikie, Tom

2009-10-21

Apatite-like materials are of considerable interest as potential solid oxide fuel cell electrolytes, although their structural vagaries continue to attract significant discussion. Understanding these features is crucial both to explain the oxide ion conduction process and to optimise it. As the composition of putative P6(3)/m apatites with ideal formula [A(I)(4)][A(II)(6)][(BO(4))(6)][X](2) is varied the [A(I)(4)(BO(4))(6)] framework will flex to better accommodate the [A(II)(6)X(2)] tunnel component through adjustment of the A(I)O(6) metaprism twist angle (varphi). The space group theory prescribes that framework adaptation during phase changes must lead to one of the maximal non-isomorphic subgroups of P6(3)/m (P2(1), P2(1)/m, P1[combining macron]). These adaptations correlate with oxygen ion conduction, and become crucial especially when the tunnels are filled by relatively small ions and/or partially occupied, and if interstitial oxygens are located in the framework. Detecting and completely describing these lower symmetry structures can be challenging, as it is difficult to precisely control apatite stoichiometry and small departures from the hexagonal metric may be near the limits of detection. Using a combination of diffraction and spectroscopic techniques it is shown that lanthanum strontium germanate oxide electrolytes crystallise as triclinic (A), monoclinic (M) and hexagonal (H) bi-layer pseudomorphs with the composition ranges: [La(10-x)Sr(x)][(GeO(4))(5+x/2)(GeO(5))(1-x/2)][O(2)] (0

Thermoelectric properties of rare earth chalcogenides

NASA Technical Reports Server (NTRS)

Danielson, L. R.; Raag, V.; Wood, C.

1985-01-01

The rare earth chalcogenides are important thermoelectric materials due to their high melting points, self-doping capabilities, and low thermal conductivities. Lanthanum sulfides and lanthanum tellurides have been synthesized in quartz ampules, hot-pressed into samples, and measured. The n-type Seebeck coefficients, electrical resistivities, and power factors generally all increased as the temperature increased from 200 to 1000 C. The figure-of-merit for nonstoichiometric lanthanum telluride was 0.001/deg C at 1000 C, considerably higher than for silicon-germanium. Thermoelectric measurements were made for LaTe(2) and YbS(1.4), and p-type behavior was observed for these compounds from 300 to 1100 C.

Optimization of the gypsum-based materials by the sequential simplex method

NASA Astrophysics Data System (ADS)

Doleželová, Magdalena; Vimmrová, Alena

2017-11-01

The application of the sequential simplex optimization method for the design of gypsum based materials is described. The principles of simplex method are explained and several examples of the method usage for the optimization of lightweight gypsum and ternary gypsum based materials are given. By this method lightweight gypsum based materials with desired properties and ternary gypsum based material with higher strength (16 MPa) were successfully developed. Simplex method is a useful tool for optimizing of gypsum based materials, but the objective of the optimization has to be formulated appropriately.

[Evidence-based management of medical disposable materials].

PubMed

Yang, Hai

2009-03-01

Evidence-based management of medical disposable materials pays attention to collect evidence comprehensively and systematically, accumulate and create evidence through its own work and also evaluate evidence strictly. This can be used as a function to guide out job. Medical disposable materials evidence system contains product register qualification, product quality certification, supplier's behavior, internal and external communication evidence. Managers can find different ways in creating and using evidence referring to specific inside and outside condition. Evidence-based management can help accelerating the development of management of medical disposable materials from traditional experience pattern to a systematic and scientific pattern. It also has the very important meaning to improve medical quality, control the unreasonable growth of medical expense and make purchase and supply chain be more efficient.

MARS-MD: rejection based image domain material decomposition

NASA Astrophysics Data System (ADS)

Bateman, C. J.; Knight, D.; Brandwacht, B.; McMahon, J.; Healy, J.; Panta, R.; Aamir, R.; Rajendran, K.; Moghiseh, M.; Ramyar, M.; Rundle, D.; Bennett, J.; de Ruiter, N.; Smithies, D.; Bell, S. T.; Doesburg, R.; Chernoglazov, A.; Mandalika, V. B. H.; Walsh, M.; Shamshad, M.; Anjomrouz, M.; Atharifard, A.; Vanden Broeke, L.; Bheesette, S.; Kirkbride, T.; Anderson, N. G.; Gieseg, S. P.; Woodfield, T.; Renaud, P. F.; Butler, A. P. H.; Butler, P. H.

2018-05-01

This paper outlines image domain material decomposition algorithms that have been routinely used in MARS spectral CT systems. These algorithms (known collectively as MARS-MD) are based on a pragmatic heuristic for solving the under-determined problem where there are more materials than energy bins. This heuristic contains three parts: (1) splitting the problem into a number of possible sub-problems, each containing fewer materials; (2) solving each sub-problem; and (3) applying rejection criteria to eliminate all but one sub-problem's solution. An advantage of this process is that different constraints can be applied to each sub-problem if necessary. In addition, the result of this process is that solutions will be sparse in the material domain, which reduces crossover of signal between material images. Two algorithms based on this process are presented: the Segmentation variant, which uses segmented material classes to define each sub-problem; and the Angular Rejection variant, which defines the rejection criteria using the angle between reconstructed attenuation vectors.

Protective interlayer for high temperature solid electrolyte electrochemical cells

DOEpatents

Singh, P.; Vasilow, T.R.; Richards, V.L.

1996-05-14

The invention is comprised of an electrically conducting doped or admixed cerium oxide composition with niobium oxide and/or tantalum oxide for electrochemical devices, characterized by the general formula: Nb{sub x}Ta{sub y}Ce{sub 1{minus}x{minus}y}O{sub 2} where x is about 0.0 to 0.05, y is about 0.0 to 0.05, and x+y is about 0.02 to 0.05, and where x is preferably about 0.02 to 0.05 and y is 0, and a method of making the same is also described. This novel composition is particularly applicable in forming a protective interlayer of a high temperature, solid electrolyte electrochemical cell, characterized by a first electrode; an electrically conductive interlayer of niobium and/or tantalum doped cerium oxide deposited over at least a first portion of the first electrode; an interconnect deposited over the interlayer; a solid electrolyte deposited over a second portion of the first electrode, the first portion being discontinuous from the second portion; and, a second electrode deposited over the solid electrolyte. The interlayer is characterized as being porous and selected from the group consisting of niobium doped cerium oxide, tantalum doped cerium oxide, and niobium and tantalum doped cerium oxide or admixtures of the same. The first electrode, an air electrode, is a porous layer of doped lanthanum manganite, the solid electrolyte layer is a dense yttria stabilized zirconium oxide, the interconnect layer is a dense, doped lanthanum chromite, and the second electrode, a fuel electrode, is a porous layer of nickel-zirconium oxide cermet. The electrochemical cell can take on a plurality of shapes such as annular, planar, etc. and can be connected to a plurality of electrochemical cells in series and/or in parallel to generate electrical energy. 5 figs.

Protective interlayer for high temperature solid electrolyte electrochemical cells

DOEpatents

Singh, Prabhakar; Vasilow, Theodore R.; Richards, Von L.

1996-01-01

The invention comprises of an electrically conducting doped or admixed cerium oxide composition with niobium oxide and/or tantalum oxide for electrochemical devices, characterized by the general formula: Nb.sub.x Ta.sub.y Ce.sub.1-x-y O.sub.2 where x is about 0.0 to 0.05, y is about 0.0 to 0.05, and x+y is about 0.02 to 0.05, and where x is preferably about 0.02 to 0.05 and y is 0, and a method of making the same. This novel composition is particularly applicable in forming a protective interlayer of a high temperature, solid electrolyte electrochemical cell (10), characterized by a first electrode (12); an electrically conductive interlayer (14) of niobium and/or tantalum doped cerium oxide deposited over at least a first portion (R) of the first electrode; an interconnect (16) deposited over the interlayer; a solid electrolyte (18) deposited over a second portion of the first electrode, the first portion being discontinuous from the second portion; and, a second electrode (20) deposited over the solid electrolyte. The interlayer (14) is characterized as being porous and selected from the group consisting of niobium doped cerium oxide, tantalum doped cerium oxide, and niobium and tantalum doped cerium oxide or admixtures of the same. The first electrode (12), an air electrode, is a porous layer of doped lanthanum manganite, the solid electrolyte layer (18) is a dense yttria stabilized zirconium oxide, the interconnect layer (16) is a dense, doped lanthanum chromite, and the second electrode (20), a fuel electrode, is a porous layer of nickel-zirconium oxide cermet. The electrochemical cell (10) can take on a plurality of shapes such as annular, planar, etc. and can be connected to a plurality of electrochemical cells in series and/or in parallel to generate electrical energy.

Room temperature ferromagnetism in a phthalocyanine based carbon material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Honda, Z., E-mail: honda@fms.saitama-u.ac.jp; Sato, K.; Sakai, M.

2014-02-07

We report on a simple method to fabricate a magnetic carbon material that contains nitrogen-coordinated transition metals and has a large magnetic moment. Highly chlorinated iron phthalocyanine was used as building blocks and potassium as a coupling reagent to uniformly disperse nitrogen-coordinated iron atoms on the phthalocyanine based carbon material. The iron phthalocyanine based carbon material exhibits ferromagnetic properties at room temperature and the ferromagnetic phase transition occurs at T{sub c} = 490 ± 10 K. Transmission electron microscopy observation, X-ray diffraction analysis, and the temperature dependence of magnetization suggest that the phthalocyanine molecules form three-dimensional random networks in the iron phthalocyanine based carbon material.

An Efficacy Trial of Research-Based Curriculum Materials with Curriculum-Based Professional Development

ERIC Educational Resources Information Center

Taylor, Joseph A.; Getty, Stephen R.; Kowalski, Susan M.; Wilson, Christopher D.; Carlson, Janet; Van Scotter, Pamela

2015-01-01

This study examined the efficacy of a curriculum-based intervention for high school science students. Specifically, the intervention was two years of research-based, multidisciplinary curriculum materials for science supported by comprehensive professional development for teachers that focused on those materials. A modest positive effect was…

Petrology and geochemistry of meta-ultramafic rocks in the Paleozoic Granjeno Schist, northeastern Mexico: Remnants of Pangaea ocean floor

NASA Astrophysics Data System (ADS)

Torres-Sánchez, Sonia Alejandra; Augustsson, Carita; Jenchen, Uwe; Rafael Barboza-Gudiño, J.; Alemán Gallardo, Eduardo; Ramírez Fernández, Juan Alonso; Torres-Sánchez, Darío; Abratis, Michael

2017-08-01

The Granjeno Schist is a meta-volcanosedimentary upper Paleozoic complex in northeastern Mexico. We suggest different tectonic settings for metamorphism of its serpentinite and talc-bearing rocks based on petrographic and geochemical compositions. According to the REE ratios (LaN/YbN = 0.51 -20.0 and LaN/SmN = 0.72-9.1) and the enrichment in the highly incompatible elements Cs (0.1 ppm), U (2.8 ppm), and Zr (60 ppm) as well as depletion in Ba (1 - 15 ppm), Sr (1 -184 ppm), Pb (0.1 -14 ppm), and Ce (0.1 -1.9 ppm) the rocks have mid-ocean ridge and subduction zones characteristics. The serpentinite contains Al-chromite, ferrian chromite and magnetite. The Al-chromite is characterized by Cr# of 0.48 to 0.55 suggesting a MORB origin, and Cr# of 0.93 to 1.00 for the ferrian chromite indicates a prograde metamorphism. We propose at least two serpentinization stages of lithospheric mantle for the ultramafic rock of the Granjeno Schist, (1) a first in an ocean-floor environment at sub-greenschist to greenschist facies conditions and (2) later a serpentinization phase related to the progressive replacement of spinel by ferrian chromite and magnetite at greenschist to low amphibolite facies conditions during regional metamorphism. The second serpentinization phase took place in an active continental margin during the Pennsylvanian. We propose that the origin of the ultramafic rocks is related to an obduction and accretional event at the western margin of Pangea.

Mechanical properties of wood-based composite materials

Treesearch

Zhiyong Cai; Robert J. Ross

2010-01-01

The term composite is used to describe any wood material bonded together with adhesives. The current product mix ranges from fiberboard to laminated beams and components. In this chapter, wood-based composite materials are classified into the following categories: panel products (plywood, oriented strandboard (OSB), particleboard, fiberboard, medium-density fiberboard...

Evaluation of a single cell and candidate materials with high water content hydrogen in a generic solid oxide fuel cell stack test fixture, Part II: materials and interface characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chou, Y. S.; Stevenson, Jeffry W.; Choi, Jung-Pyung

2013-01-01

A generic solid oxide fuel cell (SOFC) test fixture was developed to evaluate candidate materials under realistic conditions. A commerical 50 mm x 50 mm NiO-YSZ anode supported thin YSZ electrolyte cell with lanthanum strontium manganite (LSM) cathode was tested to evaluate the stability of candidate materials. The cell was tested in two stages at 800oC: stage I of low (~3% H2O) humidity and stage II of high (~30% H2O) humidity hydrogen fuel at constant voltage or constant current mode. Part I of the work was published earlier with information of the generic test fixture design, materials, cell performance, andmore » optical post-mortem analysis. In part II, detailed microstructure and interfacial characterizations are reported regarding the SOFC candidate materials: (Mn,Co)-spinel conductive coating, alumina coating for sealing area, ferritic stainless steel interconnect, refractory sealing glass, and their interactions with each other. Overall, the (Mn,Co)-spinel coating was very effective in minimizing Cr migration. No Cr was identified in the cathode after 1720h at 800oC. Aluminization of metallic interconnect also proved to be chemically compatible with alkaline-earth silicate sealing glass. The details of interfacial reaction and microstructure development are discussed.« less

Mineral resource potential map of the Mount Eddy and Castle Crags Roadless Areas, Shasta, Siskiyou, and Trinity counties, California

USGS Publications Warehouse

Peterson, Jocelyn A.; Caress, Mary E.; Denton, David K.; Spear, James M.

1983-01-01

Although ultramafic terranes such as that underlying the Mount Eddy and Castle Crags Roadless Areas may contain chromite, nickel, platinum-group metals, cobalt, and asbestos, there are no significant identified concentrations of these resources within the roadless areas. Platinum-group metals were sought but not detected in stream-sediment concentrates, although this does not rule out their possible occurrence. Nickel and cobalt did not occur in anomalous amounts although slightly higher nickel values in the northern part of the Mount Eddy Roadless Area may indicate low-grade mineralization within small dunite bodies, if the nickel occurs in sulfide phases rather than in olivine. The region has been examined on the surface for chromite and asbestos. Although both minerals are ubiquitous there is probably only a low potential for asbestos on the basis of the small size of veins at the surface. Only a few small areas of chromite were noted in the Mount Eddy Roadless Area; without subsurface data, however, any dunite body must be considered to have potential for chromite. The geochemical data for boron, barium, and mercury plus abundant quartz veining in gabbro and hornblende diorite suggest pervasive hydrothermal alteration, which could have formed mercury or vein gold deposits. Sand and gravel deposits occur in the Castle Crags Roadless Area but they cannot compete with superior deposits closer to markets. At a borrow pit northwest of the Mount Eddy Roadless Area, sheared serpentinite is quarried for road metal; similar rock occurs in the roadless area; however, better material is more readily available elsewhere.

L-cysteine capped lanthanum hydroxide nanostructures for non-invasive detection of oral cancer biomarker.

PubMed

Tiwari, Sachchidanand; Gupta, Pramod K; Bagbi, Yana; Sarkar, Tamal; Solanki, Pratima R

2017-03-15

In this paper, we present the result of studies related to the in situ synthesis of amino acid (L-Cysteine) capped lanthanum hydroxide nanoparticles [Cys-La(OH) 3 NPs] towards the fabrication of efficient immunosensor for non-invasive detection of oral cancer. The characterization of Cys-La(OH) 3 NPs was carried out by different techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy and electrochemical techniques. These Cys-La(OH) 3 NPs were electrophoretically deposited onto an indium-tin-oxide glass substrate and used for immobilization of anti-cytokeratin fragment-21-1 (anti-Cyfra-21-1) for the electrochemical detection of Cyfra-21-1. This immunosensor shows a broad detection range of 0.001-10.2ngmL -1 , the low detection limit of 0.001ngmL -1 , and high sensitivity of 12.044µA (ng per mL cm -2 ) -1 with a response time of 5min. This immunosensor was found to be more advanced in terms of high sensitivity and low detection limit as compared to previously reported biosensors and commercially available ELISA kit (Kinesis DX). Copyright © 2016 Elsevier B.V. All rights reserved.