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Sample records for gadolinium tungstates

  1. Steady-state Raman gain coefficients of potassium-gadolinium tungstate at the wavelength of 532 nm

    NASA Astrophysics Data System (ADS)

    Chulkov, R.; Markevich, V.; Orlovich, V.; El-Desouki, M.

    2015-12-01

    Stokes generation has been considered under the Fourier-limited nanosecond pulse excitation to find Raman gain coefficients in potassium-gadolinium tungstate. Data of numerical simulation under spontaneous Stokes initiation, light diffraction, and optical feedback have been compared with experimental results to reveal coefficient values of 14 ± 3 and 11 ± 3 cm/GW for the p[mm]p and p[gg]p sample orientations, respectively, at 532 nm wavelength.

  2. Efficient potassium gadolinium tungstate Raman lasers generating single or multiple wavelengths spanning the green to red

    NASA Astrophysics Data System (ADS)

    Mildren, Richard P.; Pask, H. M.; McKay, T.; Piper, J. A.

    2005-01-01

    We review our recent studies into external cavity and intracavity potassium gadolinium tungstate Raman lasers generating output wavelengths in the range 555 nm to 669 nm. We have characterised the performance external cavity Raman lasers pumped by Q-switched 532 nm pump lasers at 5-10 kHz pulse repetition rates generating either single output wavelengths or multiple wavelengths simultaneously. Single output wavelengths are obtained with slope efficiencies up to 68% and maximum output powers ~0.5 W. Simultaneous output at 5 wavelengths (eg., 532 nm, 559 nm, 589 nm, 622 nm and 658 nm) is demonstrated with ~100 mW output power for at least 3 lines. Using the intracavity Raman laser scheme, we demonstrate a 0.3-1.8 W laser that is "user switchable" amongst wavelengths spanning the green to red eg., 532 nm - 555 nm - 579 nm - 606 nm, the wavelengths corresponding to frequency sums and mixing of Stokes and fundamental intra-cavity fields.

  3. Enhanced Quantum Cutting via Li(+) Doping from a Bi(3+)/Yb(3+)-Codoped Gadolinium Tungstate Phosphor.

    PubMed

    Yadav, Ran Vijay; Yadav, Ram Sagar; Bahadur, Amresh; Singh, Akhilesh Kumar; Rai, Shyam Bahadur

    2016-11-07

    The Bi(3+)/Yb(3+)-codoped gadolinium tungstate phosphor has been synthesized through a solid-state reaction method. The structural characterization reveals the crystalline nature of the phosphor. The Bi(3+)-doped phosphor emits visible radiation from the blue to red regions upon excitation with 330 and 355 nm. The addition of Yb(3+) to the Bi(3+)-doped phosphor reduces the emission intensity in the visible region and emits an intense near-infrared (NIR) photon centered at 976 nm through a quantum-cutting (QC) phenomenon. This is due to cooperative energy transfer (CET) from the (3)P1 level of Bi(3+) to the (2)F5/2 level of Yb(3+). The presence of Li(+) ions in the Bi(3+)/Yb(3+)-codoped phosphor enhances the emission intensity in the NIR region up to by 3 times, whereas the emission intensity in the visible region is significantly reduced. The energy transfer (ET) from the Bi(3+) ions to the Yb(3+) ions is confirmed by lifetime measurements, and the lifetime for the (3)P1 level of Bi(3+) decreases continuously with increasing Yb(3+) concentration. The ET efficiency (ηETE) and corresponding QC efficiency (ηQE) are calculated and found to be 29% and 129%, respectively. The presence of Li(+) enhances the QC efficiency of the phosphor up to 43%. Thus, the Bi(3+)/Yb(3+)/Li(+)-codoped phosphor is a promising candidate to enhance the efficiency of a crystalline-silicon-based solar cell through spectral conversion.

  4. Slurry sampling ETAAS determination of sodium impurities in optical crystals of potassium titanyl phosphate and potassium gadolinium tungstate.

    PubMed

    Detcheva, Albena; Gentscheva, Galia; Havezov, Ivan; Ivanova, Elisaveta

    2002-09-12

    Slurry sampling ETAAS was successfully applied to the determination of sodium impurities in single crystals of potassium titanyl phosphate (KTP) and potassium gadolinium tungstate (KGW). Platform atomizers coated with titanium carbide or tungsten carbide, respectively, were used in order to avoid sensitivity drift due to the changes in the composition and the structure of the platform surface. Calibration curves with aqueous standards could be used for the KGW slurry (no matrix effects); analysis of KTP slurry required the standard additions method. The precision of the proposed method was better than 3% R.S.D. The results obtained by the present method showed a good agreement with those obtained by an independent method-flame AAS after sample digestion, which is an evidence for the good accuracy of the proposed method.

  5. Lasing properties of sodium-gadolinium tungstate NaGd(WO{sub 4}){sub 2} crystals doped with Tm{sup 3+} ions

    SciTech Connect

    Zharikov, Evgeny V; Lis, Denis A; Popov, A V; Subbotin, Kirill A; Ushakov, S N; Shestakov, A V; Razdobreev, I M

    2006-06-30

    Lasing is obtained in Tm{sup 3+}-doped sodium-gadolinium tungstate NaGd(WO{sub 4}){sub 2} crystals longitudinally pumped by pulses from a laser diode bar. The slope lasing efficiency is 16%. Lasing was observed at wavelengths of 1957, 1944, 1936, and 1901 nm for the transmission coefficients of the output mirror T{sub out} = 0.3%, 1.4%, 3.3%, and 8.5%, respectively. (lasers)

  6. Random lasing in Nd{sup 3+} doped potassium gadolinium tungstate crystal powder

    SciTech Connect

    Moura, André L.; Fewo, Serge I.; Carvalho, Mariana T.; Gomes, Anderson S. L.; Araújo, Cid B. de; Kuzmin, Andrey N.; Prasad, Paras N.

    2015-02-28

    Random laser (RL) emission in Nd{sup 3+} doped potassium gadolinium tungstate—KGd(WO{sub 4}){sub 2}:Nd{sup 3+}—crystal powder is demonstrated. The powder was excited at 813 nm in resonance with the Nd{sup 3+} transition {sup 4}I{sub 9/2}→{sup 4}F{sub 5/2}. RL emission at 1067 nm due to the {sup 4}F{sub 3/2}→{sup 4}I{sub 11/2} transition was observed and characterized. An intensity threshold dependent on the laser spot area and bandwidth narrowing from ≈2.20 nm to ≈0.40 nm were observed and measured. For a beam spot area of 0.4 mm{sup 2}, a RL threshold of 6.5 mJ/mm{sup 2} (90 MW/cm{sup 2}) was determined. For excitation intensity smaller than the RL threshold, only spontaneous emission from level {sup 4}F{sub 3/2} with decay time in the tens microsecond range was observed, but for excitation above the RL threshold, significant shortening of excited level lifetime, characteristic of a stimulated process was found. The overall characteristics measured show that KGd(WO{sub 4}){sub 2}:Nd{sup 3+} is an efficient material for operation of solid state RLs in the near-infrared.

  7. Tunable quasi-cw two-micron lasing in diode-pumped crystals of mixed Tm{sup 3+}-doped sodium - lanthanum - gadolinium molybdates and tungstates

    SciTech Connect

    Bol'shchikov, F A; Ryabochkina, P A; Zharikov, Evgeny V; Lis, Denis A; Subbotin, Kirill A; Zakharov, N G; Antipov, Oleg L

    2010-12-09

    Two-micron lasing is obtained for the first time on the {sup 3}F{sub 4} {yields} {sup 3}H{sub 6} transition of Tm{sup 3+} ions in diode-pumped crystals of mixed sodium - lanthanum - gadolinium tungstate Tm:NaLa{sub 1/2}Gd{sub 1/2}(WO{sub 4}){sub 2} (C{sub Tm} = 3.6 at %) (3.6Tm : NLGW) and molybdate Tm:NaLa{sub 1/3}Gd{sub 2/3}(MoO{sub 4}){sub 2} (C{sub Tm} = 4.8 at %) (4.8Tm : NLGM). For the 3.6Tm : NLGW crystal, the quasi-cw laser output power exceeded 200 mW and the slope efficiency (with respect to absorbed pump power) for the {pi}- and {sigma}-polarisations at wavelengths of 1908 and 1918 nm was 34% and 30%, respectively. The laser wavelength of this crystal was continuously tuned within the spectral range of 1860 - 1935 nm. For the 4.8Tm : NLGM crystal, the slope efficiency for the {pi}- and {sigma}-polarisations at wavelengths of 1910 and 1918 nm was 27% and 23%, respectively, and the laser wavelength was tunable within the spectral range of 1870 - 1950 nm. (lasers)

  8. Three-color vibrational CARS thermometry of fuel-rich ethylene/air flames using a potassium gadolinium tungstate Raman-active crystal as a source of narrowband probe radiation.

    PubMed

    Meißner, Christian; Tröger, Johannes W; Kozlov, Dimitrii N; Beyrau, Frank; Seeger, Thomas

    2017-04-10

    Three-color broadband vibrational coherent anti-Stokes Raman scattering (CARS) temperature measurements were carried out in laminar fuel-rich sooting ethylene/air flames. Stimulated Raman scattering (SRS) of a picosecond pump laser pulse in a Raman-active potassium gadolinium tungstate [KGd(WO4)2] crystal was employed as a source of narrowband probe radiation. In the three-color CARS experiment, this wavelength-shifted radiation enables N2-based vibrational CARS temperature measurements in sooting flames free of the signal interference with the absorption/emission bands of the flame intermediate radicals C2. Spatial temperature profiles for different fuel-rich atmospheric pressure ethylene/air flames are presented in comparison with the results of two-color broadband vibrational and dual-broadband pure rotational CARS temperature measurements. The comparison shows the suitability of the three-color CARS measurement technique employing the KGd(WO4)2 crystal for accurate, C2 interference-free, temperature measurements in sooting flames.

  9. Synthesis, structural and vibrational studies on mixed alkali metal gadolinium double tungstate, K1-xNaxGd(WO4)2

    NASA Astrophysics Data System (ADS)

    Durairajan, A.; Thangaraju, D.; Moorthy Babu, S.

    2013-02-01

    Mixed alkali double tungstates K1-xNaxGd(WO4)2 (KNGW) (0 ⩽ x ⩽ 1) were synthesized by solid state reaction using sodium doped monoclinic KGd(WO4)2 (KGW). Synthesized KNGW powders were characterized using powder X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM) and Raman analysis. DTA analysis confirms that the melting point of the KGW matrix increases from 1063 °C to 1255 °C with increasing sodium content. The Powder XRD analyses reveal that mixed phases were observed up to 40 wt.% of Na in the KGW matrix above that percentage there is domination of scheelite structure in the synthesized powder. Polyhedral type, bi-pyramidal shape and spheroid shape morphology was observed for KGW, NKGW and NGW powders respectively. The Raman analysis was carried out to understand the vibrational characteristic changes with mixing of sodium ions in the KGW matrix.

  10. Uranyl tungstate and zirconium tungstate in salt melts

    SciTech Connect

    Kryukova, A.I.; Bragina, R.A.; Kazantsev, G.N.; Korshunov, I.A.

    1988-05-01

    The article discusses the preparation, properties, and behavior of uranyl tungstate and zirconium tungstate in salt melts. Procedures for their preparation are presented. The radiographic and IR spectroscopic characteristics, the thermal stability, and solubility and stability in chloride-tungstate melts of different composition have been studied.

  11. Spectroscopy of erbium-doped potassium double tungstate waveguides

    NASA Astrophysics Data System (ADS)

    Vázquez-Córdova, Sergio A.; Aravazhi, Shanmugam; Grivas, Christos; Heuer, Alexander M.; Kränkel, Christian; Yong, Yean-Sheng; García-Blanco, Sonia M.; Herek, Jennifer L.; Pollnau, Markus

    2017-02-01

    We report the spectroscopy of crystalline waveguide amplifiers operating in the telecom C-band. Thin films of erbiumdoped gadolinium lutetium potassium double tungstate, KGdxLuyEr1-x-y (WO4)2, are grown by liquid- phase epitaxy onto undoped potassium yttrium double tungstate (KYW) substrates and micro-structured by Ar+- beam etching. Channel waveguides with erbium concentrations between 0.45-6.35 × 1020 cm-3 are characterized. The transition cross-sections of interest are estimated. The effect of energy-transfer up-conversion (ETU) is experimentally investigated. Microscopic and macroscopic ETU parameters are extracted from a simultaneous analysis of 20 decay curves of luminescence on the transition 4I13/2 -> 4I13/2. The correlation between ETU and the doping concentration is studied. Pump excited-state absorption (ESA) on the transition 4I11/2 -> 4F7/2 is investigated via a direct ESA measurement using a double-modulation pump-probe technique. The effect of ESA is studied for different pump wavelengths. The pump wavelength of 984.5 nm is found to be favorable for the complete range of erbium concentrations.

  12. High power tungstate-crystal Raman laser operating in the strong thermal lensing regime.

    PubMed

    McKay, Aaron; Kitzler, Ondrej; Mildren, Richard P

    2014-01-13

    We report an investigation into a double metal tungstate Raman laser when pumped at elevated average powers. Potassium gadolinium tungstate (KGW) was placed in an external cavity configured for second-Stokes output and pumped at pulse repetition rate of 38 kHz with up to 46 W of average power. For output powers above 3 W, we observe preferential excitation of Hermite-Gaussian transverse modes whose order in the X(1)(') principal direction of the thermal expansion tensor scales linearly with Raman power. We deduce that strong astigmatic thermal lensing is induced in the Raman crystal with a negative component in the X(1)(') direction. At maximum pump power, 8.3 W of output power was obtained at a conversion efficiency of 18%.

  13. Morphology Tuning of Strontium Tungstate Nanoparticles

    SciTech Connect

    Joseph, S.; George, T.; George, K. C.; Sunny, A. T.; Mathew, S.

    2007-08-22

    Strontium tungstate nanocrystals in two different morphologies are successfully synthesized by controlled precipitation in aqueous and in poly vinyl alcohol (PVA) medium. Structural characterizations are carried out by XRD and SEM. The average particle size calculated for the SrWO4 prepared in the two different solvents ranges 20-24 nm. The SEM pictures show that the surface morphologies of the SrWO4 nanoparticles in aqueous medium resemble mushroom and the SrWO4 nanoparticles in PVA medium resemble cauliflower. Investigations on the room temperature luminescent properties of the strontium tungstate nanoparticles prepared in aqueous and PVA medium shows strong emissions around 425 nm.

  14. A high-resolution tungstate membrane label

    SciTech Connect

    Hainfeld, J.F.; Quaite, F.E. ); Lipka, J.J. )

    1990-01-01

    A new class of membrane labels was synthesized which contain a tungstate cluster (having 11 tungsten atoms) and an aliphatic organo-tin moiety with various chain lengths (C{sub 4}, C{sub 8}, C{sub 12}, C{sub 18}, C{sub 22}). These molecules were found to insert into synthetic phospholipid vesicles and biological membranes (human red blood cell membranes). The tungstate clusters can be individually visualized in the high resolution STEM or seen en mass in thin-sectioned labeled membranes in the CTEM. These new labels should provide a means for direct high-resolution imaging of lipid-phase systems.

  15. Gadolinium photoionization process

    DOEpatents

    Paisner, Jeffrey A.; Comaskey, Brian J.; Haynam, Christopher A.; Eggert, Jon H.

    1993-01-01

    A method is provided for selective photoionization of the odd-numbered atomic mass gadolinium isotopes 155 and 157. The selective photoionization is accomplished by circular or linear parallel polarized laser beam energy effecting a three-step photoionization pathway.

  16. Gadolinium photoionization process

    DOEpatents

    Paisner, J.A.; Comaskey, B.J.; Haynam, C.A.; Eggert, J.H.

    1993-04-13

    A method is provided for selective photoionization of the odd-numbered atomic mass gadolinium isotopes 155 and 157. The selective photoionization is accomplished by circular or linear parallel polarized laser beam energy effecting a three-step photoionization pathway.

  17. Sodium tungstate modulates ATM function upon DNA damage.

    PubMed

    Rodriguez-Hernandez, C J; Llorens-Agost, M; Calbó, J; Murguia, J R; Guinovart, J J

    2013-05-21

    Both radiotherapy and most effective chemotherapeutic agents induce different types of DNA damage. Here we show that tungstate modulates cell response to DNA damaging agents. Cells treated with tungstate were more sensitive to etoposide, phleomycin and ionizing radiation (IR), all of which induce DNA double-strand breaks (DSBs). Tungstate also modulated the activation of the central DSB signalling kinase, ATM, in response to these agents. These effects required the functionality of the Mre11-Nbs1-Rad50 (MRN) complex and were mimicked by the inhibition of PP2A phosphatase. Therefore, tungstate may have adjuvant activity when combined with DNA-damaging agents in the treatment of several malignancies.

  18. Modulation of glucose transporters in rat diaphragm by sodium tungstate.

    PubMed

    Girón, M D; Caballero, J J; Vargas, A M; Suárez, M D; Guinovart, J J; Salto, R

    2003-05-08

    Oral administration of sodium tungstate is an effective treatment for diabetes in animal models. We examined the effects of 6 weeks of oral administration of tungstate on glucose transporters (GLUT) in streptozotocin-induced diabetic rat diaphragm. Diabetes decreased GLUT4 expression while tungstate treatment normalized not only GLUT4 protein but also GLUT4 mRNA in the diabetic rats. Furthermore, treatment increased GLUT4 protein in plasma and internal membranes, suggesting a stimulation of its translocation to the plasma membrane. Tungstate had no effect on healthy animals. There were no differences in the total amount of GLUT1 transporter in any group. We conclude that the normoglycemic effect of tungstate may be partly due to a normalization of the levels and subcellular localization of GLUT4, which should result in an increase in muscle glucose uptake.

  19. Gadolinium induces macrophage apoptosis.

    PubMed

    Mizgerd, J P; Molina, R M; Stearns, R C; Brain, J D; Warner, A E

    1996-02-01

    Gadolinium (Gd) suppresses reticuloendothelial functions in vivo by unknown mechanisms. In vitro exposure of rat alveolar macrophages to GdCl3.6H20 caused cell death, as measured by trypan blue permeability, in both dose- and time-dependent fashions. Even a 10-min exposure to Gd caused significant cell death by 24 h. The morphology of Gd-treated cells, pyknosis and karyorrhexis prior to loss of membrane integrity, suggested apoptosis. Upon flow cytometric examination, Gd-treated propidium iodide-excluding cells demonstrated light scatter changes characteristic of apoptotic cells (decreased forward and increased right angle scatter). Gel electrophoresis of DNA from Gd-treated macrophages clearly showed the ladder pattern unique to apoptotic cells. Electron-dense structures containing Gd were observed via electron spectroscopic imaging within phagosomes and also within nuclei (associated with condensed chromatin). Gadolinium, endocytosed by macrophages and distributed to nuclei, causes apoptosis of macrophages in vitro.

  20. Gadolinium-Induced Fibrosis.

    PubMed

    Todd, Derrick J; Kay, Jonathan

    2016-01-01

    Gadolinium-based contrast agents (GBCAs), once believed to be safe for patients with renal disease, have been strongly associated with nephrogenic systemic fibrosis (NSF), a severe systemic fibrosing disorder that predominantly afflicts individuals with advanced renal dysfunction. We provide a historical perspective on the appearance and disappearance of NSF, including its initial recognition as a discrete clinical entity, its association with GBCA exposure, and the data supporting a causative relationship between GBCA exposure and NSF. On the basis of this body of evidence, we propose that the name gadolinium-induced fibrosis (GIF) more accurately reflects the totality of knowledge regarding this disease. Use of high-risk GBCAs, such as formulated gadodiamide, should be avoided in patients with renal disease. Restriction of GBCA use in this population has almost completely eradicated new cases of this debilitating condition. Emerging antifibrotic therapies may be useful for patients who suffer from GIF.

  1. Interaction of rat liver glucocorticoid receptor with sodium tungstate.

    PubMed

    Murakami, N; Healy, S P; Moudgil, V K

    1982-06-15

    Effects of sodium tungstate on various properties of rat liver glucocorticoid receptor were examined at pH7 and pH 8. At pH 7, [3H]triamcinolone acetonide binding in rat liver cytosol preparations was completely blocked in the presence of 10--20 mM-sodium tungstate at 4 degrees C, whereas at 37 degrees C a 30 min incubation of cytosol receptor preparation with 1 mM-sodium tungstate reduced the loss of unoccupied receptor by 50%. At pH 8.0, tungstate presence during the 37 degrees C incubation maintained the steroid-binding capacity of unoccupied glucocorticoid receptor at control (4 degrees C) levels. In addition, heat-activation of cytosolic glucocorticoid-receptor complex was blocked by 1 mM- and 10 mM-sodium tungstate at pH 7 and pH 8 respectively. The DNA-cellulose binding by activated receptor was also inhibited completely and irreversibly by 5 mM-tungstate at pH 7, whereas at pH 8 no significant effect was observed with up to 20 mM-tungstate. The entire DNA-cellulose-bound glucocorticoid-receptor complex from control samples could be extracted by incubation with 1 mM- and 20 mM-tungstate at pH 7 and pH 8 respectively, and appeared to sediment as a 4.3--4.6 S molecule, both in 0.01 M- and 0.3 M-KCl-containing sucrose gradients. Tungstate effects are, therefore, pH-dependent and appear to involve an interaction with both the non-activated and the activated forms of the glucocorticoid receptor.

  2. Temperature-dependent absorption and gain of ytterbium-doped potassium double tungstates for chip-scale amplifiers and lasers

    NASA Astrophysics Data System (ADS)

    Yong, Yean-Sheng; Aravazhi, Shanmugam; Vázquez-Córdova, Sergio A.; Herek, Jennifer L.; García-Blanco, Sonia M.; Pollnau, Markus

    2017-02-01

    Ytterbium-doped potassium rare-earth double tungstate thin films are excellent candidates for highly efficient waveguide lasers, as well as high-gain waveguide amplifiers, with a record-high optical gain per unit length of 935 dB/cm recently demonstrated. However, the spectroscopic properties of these highly ytterbium-doped thin films and, in particular, their temperature dependence are not well investigated. These characteristics are required for the understanding of the behavior of the fabricated optical devices and crucial for further device optimization. We experimentally determined the absorption cross-sections for a potassium ytterbium gadolinium double tungstate, KYb0.57Gd0.43(WO4)2, thin film grown lattice matched onto an undoped KY(WO4)2 substrate. At room temperature, the peak cross-section value at 981 nm and the overall absorption spectrum are very similar to those of Yb-doped bulk potassium double tungstate crystals, although Yb is now the dominating rare-earth content. The temperature-dependent study shows a significant decrease of the absorption cross-section values at 933 nm and 981 nm with increasing temperature. We verify theoretically that this is due to the temperature dependence of fractional populations in the individual Stark levels of the absorbing crystal-field multiplet, in combination with the linewidth broadening with increasing temperature. Further investigations suggest that the broadening of absorption linewidth at 981 nm originates in the intra-manifold relaxation between the two lowest Stark levels of the ground state. Finally, the implications of the spectroscopic findings on the operating characteristics of waveguide amplifiers are investigated. Amplifiers operating at 80 °C are expected to exhibit only 67% of the maximum theoretical gain at room temperature.

  3. Niobium hyperfine structure in crystal calcium tungstate

    NASA Technical Reports Server (NTRS)

    Tseng, D. L.; Kikuchi, C.

    1972-01-01

    A study of the niobium hyperfine structure in single crystal calcium tungstate was made by the combination of the technique of electron paramagnetic resonance and electron nuclear double resonance (EPR/ENDOR). The microwave frequency was about 9.4 GHz and the radio frequency from 20MHz to 70 MHz. The rare earth ions Nd(3+), U(3+), or Tm(3+) were added as the charge compensator for Nb(5+). To create niobium paramagnetic centers, the sample was irradiated at 77 deg K with a 10 thousand curie Co-60 gamma source for 1 to 2 hours at a dose rate of 200 K rads per hour and then transferred quickly into the cavity. In a general direction of magnetic field, the spectra showed 4 sets of 10 main lines corresponding to 4 nonequivalent sites of niobium with I = 9/2. These 4 sets of lines coalesced into 2 sets of 10 in the ab-plane and into a single set of 10 along the c-axis. This symmetry suggested that the tungsten ions are substituted by the niobium ions in the crystal.

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

    PubMed

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

    2013-04-21

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

  5. Synchrotron-based far-infrared spectroscopy of nickel tungstate

    NASA Astrophysics Data System (ADS)

    Kalinko, A.; Kuzmin, A.; Roy, P.; Evarestov, R. A.

    2016-07-01

    Monoclinic antiferromagnetic NiWO4 was studied by far-infrared (30-600 cm-1) absorption spectroscopy in the temperature range of 5-300 K using the synchrotron radiation from SOLEIL source. Two isomorphous CoWO4 and ZnWO4 tungstates were investigated for comparison. The phonon contributions in the far-infrared range of tungstates were interpreted using the first-principles spin-polarized linear combination of atomic orbital calculations. No contributions from magnetic excitations were found in NiWO4 and CoWO4 below their Neel temperatures down to 5 K.

  6. Effects of sodium tungstate on oxidative stress enzymes in rats.

    PubMed

    Sachdeva, Sherry; Kushwaha, Pramod; Flora, S J S

    2013-09-01

    Tungsten, due to its distinguished physical properties, has wide industrial and military applications. Environmental exposure to tungsten, which mainly occurs through various sources like food, water, soil, etc., is of growing concern as various toxic effects have recently been reported. In this study, we investigated the effects of oral and intraperitoneal (i.p.) administration of sodium tungstate on various biochemical variables indicative of oxidative stress in erythrocytes and soft tissue damage in rats. Male rats were administered to 119 mg, 238 mg/kg of sodium tungstate orally or 20 mg and 41 mg/kg through i.p. route, for 14 consecutive days. The results demonstrated a significant increase in Reactive Oxygen Species (ROS) and an increase in catalase and glutathione peroxidase antioxidant enzymes activities in erythrocytes. Erythrocyte glutathione-S-transferase (GST) activity showed significant inhibition, while tissue ROS and thiobarbituric acid reactive substance levels increased accompanied by a decreased reduced glutathione, oxidized glutathione (GSH:GSSG) ratio. These changes were supported by an increase in plasma transaminases activities, creatinine, and urea levels, suggesting hepatic and renal injury. These biochemical alterations were prominent in rats intraperitoneally administrated with sodium tungstate than oral administration, suggesting more pronounced toxicity. The study also suggests oxidative stress as one of the major mechanism involved in the toxic manifestations of sodium tungstate.

  7. Effects of sodium tungstate on insulin and glucagon secretion in the perfused rat pancreas.

    PubMed

    Rodríguez-Gallardo, J; Silvestre, R A; Egido, E M; Marco, J

    2000-08-18

    Both the direct effect of sodium tungstate on insulin and glucagon secretion in the perfused rat pancreas, and the insulin response to glucose and arginine in pancreases isolated from tungstate-pretreated rats were studied. Infusion of tungstate stimulated insulin output in a dose-dependent manner. The insulinotropic effect of tungstate was observed at normal (5.5 mM), and moderately high (9 mM) glucose concentrations, but not at a low glucose concentration (3.2 mM). Tungstate-induced insulin output was blocked by diazoxide, somatostatin, and amylin, suggesting several targets for tungstate at the B-cell secretory machinery. Glucagon release was not modified by tungstate. Pancreases from chronically tungstate-treated rats showed an enhanced response to glucose but not to arginine. Our results indicate that the reported reduction of glycemia caused by tungstate administration is, at least in part, due to its direct insulinotropic activity. Furthermore, chronic tungstate treatment may prime the B-cell, leading to over-response to a glucose stimulus.

  8. Thermodynamic properties of gadolinium disilicide

    SciTech Connect

    Lukashenko, G.M.; Polotskaya, R.I.

    1986-11-01

    The authors determine the Gibbs energy, enthalpy, formation heat, and other thermodynamic properties of gadolinium disilicide by measuring the electromotive force in the 830-960 K temperature range in electrolytes consisting of molten tin and various chlorides. The relationship of these properties to crystal structure is briefly discussed.

  9. Experience with gadolinium at yankee

    SciTech Connect

    Cacciapouti, R.J.; Sironen, M.A.; Kaptiz, D.M.; Potter, R.C.

    1985-11-01

    The Vermont Yankee nuclear power station, a boiling water reactor, has been operating with gadolinium in the fuel bundles since 1973. The gadolinium has ranged from 2.0 to 4.0 wt% in 7 x 7, 8 x 8, and retrofit 8 x 8 bundle designs. When Yankee Atomic Electric Company initiated its program in 1978 to perform reload licensing analysis, these bundles and the core designs had to be modeled accurately. The basic calculational model consists of the cross section generation code, CASMO, and the three-dimensional nodal code, SIMULATE. The gadolinium cross sections for use in CASMO were generated using MICBURN to model each gadolinium pin individually. This combination of codes has been used to calculate 11 cycles of operation at Vermont Yankee. The model has been depleted each cycle using explicit plant conditions at equilibrium xenon. At various state points, the eigenvalues, hot and cold, were calculated and tabulated for each cycle. Comparisons were made between plant-measured and SIMULATE-calculated TIP values and between process computer and SIMULATE thermal margins. The model is also used to predict future cycle operating conditions and thermal margins based on past comparisons.

  10. Tungstate sulfuric acid (TSA)/KMnO4 as a novel heterogeneous system for rapid deoximation.

    PubMed

    Karami, Bahador; Montazerozohori, Morteza

    2006-09-28

    Neat chlorosulfonic acid reacts with anhydrous sodium tungstate to give tungstate sulfuric acid (TSA), a new dibasic inorganic solid acid in which two sulfuric acid molecules connect to a tungstate moiety via a covalent bond. A variety of oximes were oxidized to their parent carbonyl compounds under mild conditions with excellent yields in short times by a heterogeneous wet TSA/KMnO4 in dichloromethane system.

  11. Anti-obesity sodium tungstate treatment triggers axonal and glial plasticity in hypothalamic feeding centers.

    PubMed

    Amigó-Correig, Marta; Barceló-Batllori, Sílvia; Soria, Guadalupe; Krezymon, Alice; Benani, Alexandre; Pénicaud, Luc; Tudela, Raúl; Planas, Anna Maria; Fernández, Eduardo; Carmona, Maria del Carmen; Gomis, Ramon

    2012-01-01

    This study aims at exploring the effects of sodium tungstate treatment on hypothalamic plasticity, which is known to have an important role in the control of energy metabolism. Adult lean and high-fat diet-induced obese mice were orally treated with sodium tungstate. Arcuate and paraventricular nuclei and lateral hypothalamus were separated and subjected to proteomic analysis by DIGE and mass spectrometry. Immunohistochemistry and in vivo magnetic resonance imaging were also performed. Sodium tungstate treatment reduced body weight gain, food intake, and blood glucose and triglyceride levels. These effects were associated with transcriptional and functional changes in the hypothalamus. Proteomic analysis revealed that sodium tungstate modified the expression levels of proteins involved in cell morphology, axonal growth, and tissue remodeling, such as actin, CRMP2 and neurofilaments, and of proteins related to energy metabolism. Moreover, immunohistochemistry studies confirmed results for some targets and further revealed tungstate-dependent regulation of SNAP25 and HPC-1 proteins, suggesting an effect on synaptogenesis as well. Functional test for cell activity based on c-fos-positive cell counting also suggested that sodium tungstate modified hypothalamic basal activity. Finally, in vivo magnetic resonance imaging showed that tungstate treatment can affect neuronal organization in the hypothalamus. Altogether, these results suggest that sodium tungstate regulates proteins involved in axonal and glial plasticity. The fact that sodium tungstate could modulate hypothalamic plasticity and networks in adulthood makes it a possible and interesting therapeutic strategy not only for obesity management, but also for other neurodegenerative illnesses like Alzheimer's disease.

  12. Solubility of sodium tungstate in nitrate-nitrite melts

    SciTech Connect

    Yurkinskii, V.P.; Firsova, E.G.; Morachevskii, A.G.; Sazanova, O.B.

    1988-10-10

    Nitrate melts are employed as electrolytes for the electrochemical oxidation of tungsten. The authors studied the solubility of sodium tungstate in a number of nitrate-nitrite melts. The investigations were carried out in individual melts of NaNO/sub 3/ and NaNO/sub 2/ and in LiNO/sub 3/-NaNO/sub 3/-KNO/sub 3/ and NaNO/sub 3/-KNO/sub 3/ eutectic mixtures in the 440-690 K temperature range in an atmosphere of argon. The solubility of sodium tungstate increases slightly upon the transition from an LiNO/sub 3/-NaNO/sub 3/-KNO/sub 3/ melt to an NaNO/sub 3/-KNO/sub 3/ melt. The solubility of Na/sub 2/WO/sub 4/ in sodium nitrite is considerably higher than that in sodium nitrate.

  13. Synthesis of europium- or terbium-activated calcium tungstate phosphors

    NASA Astrophysics Data System (ADS)

    Forgaciu, Flavia; Popovici, Elisabeth-Jeanne; Ungur, Laura; Vadan, Maria; Vasilescu, Marilena; Nazarov, Mihail

    2001-06-01

    Utilization of luminescent substances in various optoelectronic devices depends on their luminescent properties and sensitivity to various excitation radiation as well as on particle size distribution and crystalline structure of luminous powders. Calcium tungstate phosphors are well excited with roentgen radiation, so that they are largely used for manufacture of x-ray intensifying screens. Being sensitive to short UV-radiation as well, they could be utilized in Plasma Display Panels or in advertising signs fluorescent tubes. In order to diversify the utilization possibilities of this tungstate class, luminescent powders based on CaWO4:Eu3+ and CaWO4:Tb3+ were synthesized and characterized. As compared with the starting self-activated phosphor, larger excitation wavelength domain and emission colors from blue-to-green-to- yellow-to-red were obtained. The good UV excitability and variable luminescence color recommend these phosphors for optoelectronic device manufacture.

  14. Polaron formation, native defects, and electronic conduction in metal tungstates

    NASA Astrophysics Data System (ADS)

    Hoang, Khang

    2017-07-01

    Iron tungstate (FeWO4 ) and manganese tungstate (MnWO4 ) belong to a family of wolframite-type materials that has applications in various areas, including supercapacitors, batteries, and multiferroics. A detailed understanding of bulk properties and defect physics in these transition-metal tungstates has been lacking, however, impeding possible improvement of their functional properties. Here, we report a first-principles study of FeWO4 and MnWO4 using screened hybrid density-functional calculations. We find that in both compounds the electronic structures near the band edges are predominantly the highly localized transition-metal d states, which allows for the formation of both hole polarons at the Fe (Mn) sites and electron polarons at the W sites. The dominant native point defects in FeWO4 (MnWO4 ) under realistic synthesis conditions are, however, the hole polarons at the Fe (Mn) sites and negatively charged Fe (Mn) vacancies. The presence of low-energy and highly mobile polarons provides an explanation for the good p -type conductivity observed in experiments and the ability of the materials to store energy via a pseudocapacitive mechanism.

  15. Polyimide nanocomposites based on cubic zirconium tungstate

    NASA Astrophysics Data System (ADS)

    Ramasubramanian Sharma, Gayathri

    2009-12-01

    In this research, cubic zirconium tungstate (ZrW2O8) was used as a filler to reduce the CTE of polyimides (PI), and the effect of ZrW2O8 nanoparticles on the bulk polymer properties was studied. Polyimides are high performance polymers with exceptional thermal stability, and there is a need for PIs with low CTEs for high temperature applications. The nanofiller, cubic ZrW2O8, is well known for its isotropic negative thermal expansion (NTE) over a wide temperature range from -272.7 to 777°C. The preparation of nanocomposites involved the synthesis of ZrW 2O8 nanofiller, engineering the polymer-filler interface using linker groups and optimization of processing strategies to prepare free-standing PI nanocomposite films. A hydrothermal method was used to synthesize ZrW 2O8 nanoparticles. Polyimide-ZrW2O8 interface interaction was enhanced by covalently bonding linker moieties to the surface of ZrW2O8 nanoparticles. Specifically, ZrW 2O8 nanoparticles were functionalized with two different linker groups: (1) a short aliphatic silane, and (2) low molecular weight PI. The surface functionalization was confirmed using X-ray photoelectron spectroscopy and thermal gravimetric analysis (TGA). Reprecipitation blending was used to prepare the freestanding PI-ZrW2O8 nanocomposite films with up to 15 volume% filler loading. SEM images showed the improvements in polymer-filler wetting behavior achieved using interface engineering. SEM images indicated that there was better filler dispersion in the PI matrix using reprecipitation blending, compared to the filler dispersion achieved in the nanocomposites prepared using conventional blending technique. The structure-property relationships in PI-ZrW2O8 nanocomposites were investigated by studying the thermal degradation, glass transition, tensile and thermal expansion properties of the nanocomposites. The properties were studied as a function of filler loading and interface linker groups. Addition of ZrW2O8 nanoparticles did not

  16. Tumor growth suppression by gadolinium-neutron capture therapy using gadolinium-entrapped liposome as gadolinium delivery agent.

    PubMed

    Dewi, Novriana; Yanagie, Hironobu; Zhu, Haito; Demachi, Kazuyuki; Shinohara, Atsuko; Yokoyama, Kazuhito; Sekino, Masaki; Sakurai, Yuriko; Morishita, Yasuyuki; Iyomoto, Naoko; Nagasaki, Takeshi; Horiguchi, Yukichi; Nagasaki, Yukio; Nakajima, Jun; Ono, Minoru; Kakimi, Kazuhiro; Takahashi, Hiroyuki

    2013-07-01

    Neutron capture therapy (NCT) is a promising non-invasive cancer therapy approach and some recent NCT research has focused on using compounds containing gadolinium as an alternative to currently used boron-10 considering several advantages that gadolinium offers compared to those of boron. In this study, we evaluated gadolinium-entrapped liposome compound as neutron capture therapy agent by in vivo experiment on colon-26 tumor-bearing mice. Gadolinium compound were injected intravenously via tail vein and allowed to accumulate into tumor site. Tumor samples were taken for quantitative analysis by ICP-MS at 2, 12, and 24 h after gadolinium compound injection. Highest gadolinium concentration was observed at about 2 h after gadolinium compound injection with an average of 40.3 μg/g of wet tumor tissue. We performed neutron irradiation at JRR-4 reactor facility of Japan Atomic Energy Research Institute in Tokaimura with average neutron fluence of 2×10¹² n/cm². The experimental results showed that the tumor growth suppression of gadolinium-injected irradiated group was revealed until about four times higher compared to the control group, and no significant weight loss were observed after treatment suggesting low systemic toxicity of this compound. The gadolinium-entrapped liposome will become one of the candidates for Gd delivery system on NCT.

  17. Anti-diabetic and anti-obesity agent sodium tungstate enhances GCN pathway activation through Glc7p inhibition.

    PubMed

    Rodriguez-Hernandez, C J; Guinovart, J J; Murguia, J R

    2012-02-03

    Tungstate counteracts diabetes and obesity in animal models, but its molecular mechanisms remain elusive. Our Saccharomyces cerevisiae-based approach has found that tungstate alleviated the growth defect induced by nutrient stress and enhanced the activation of the GCN pathway. Tungstate relieved the sensitivity to starvation of a gcn2-507 yeast hypomorphic mutant, indicating that tungstate modulated the GCN pathway downstream of Gcn2p. Interestingly, tungstate inhibited Glc7p and PP1 phosphatase activity, both negative regulators of the GCN pathway in yeast and humans, respectively. Accordingly, overexpression of a dominant-negative Glc7p mutant in yeast mimicked tungstate effects. Therefore tungstate alleviates nutrient stress in yeast by in vivo inhibition of Glc7p. These data uncover a potential role for tungstate in the treatment of PP1 and GCN related diseases.

  18. Gadolinium periconceptional exposure: pregnancy and neonatal outcome.

    PubMed

    De Santis, M; Straface, G; Cavaliere, A F; Carducci, B; Caruso, A

    2007-01-01

    Gadolinium derivatives are ionic paramagnetic contrast agents used to enhance magnetic resonance images, labeled as a pregnancy category C by the Food and Drug Administration because of a lack of epidemiological studies concerning first-trimester exposure. Prospective cohort study to determine whether gadolinium derivatives exposure in periconceptional period is a risk factor for pregnancy or fetal development. We report the outcome of 26 pregnant women exposed to gadolinium derivatives in the first trimester without adverse effect on pregnancy and neonatal outcome. Currently, this study represents the only prospective investigation of gadolinium derivatives in pregnancy, but more data are necessary to exclude a teratogenic risk.

  19. A functional leptin system is essential for sodium tungstate antiobesity action.

    PubMed

    Canals, Ignasi; Carmona, María C; Amigó, Marta; Barbera, Albert; Bortolozzi, Analía; Artigas, Francesc; Gomis, Ramon

    2009-02-01

    Sodium tungstate is a novel agent in the treatment of obesity. In diet-induced obese rats, it is able to reduce body weight gain by increasing energy expenditure. This study evaluated the role of leptin, a key regulator of energy homeostasis, in the tungstate antiobesity effect. Leptin receptor-deficient Zucker fa/fa rats and leptin-deficient ob/ob mice were treated with tungstate. In lean animals, tungstate administration reduced body weight gain and food intake and increased energy expenditure. However, in animals with deficiencies in the leptin system, treatment did not modify these parameters. In ob/ob mice in which leptin deficiency was restored through adipose tissue transplantation, treatment restored the tungstate-induced body weight gain and food intake reduction as well as energy expenditure increase. Furthermore, in animals in which tungstate administration increased energy expenditure, changes in the expression of key genes involved in brown adipose tissue thermogenesis were detected. Finally, the gene expression of the hypothalamic neuropeptides, Npy, Agrp, and Cart, involved in the leptin regulation of energy homeostasis, was also modified by tungstate in a leptin-dependent manner. In summary, the results indicate that the effectiveness of tungstate in reducing body weight gain is completely dependent on a functional leptin system.

  20. Sodium tungstate alleviates biomechanical properties of diabetic rat femur via modulation of oxidative stress.

    PubMed

    Donmez, Baris O; Ozturk, Nihal; Sarikanat, Mehmet; Oguz, Nurettin; Sari, Ramazan; Ozdemir, Semir

    2014-01-01

    Diabetes mellitus leads to bone disorders such as osteopenia and osteoporosis that can increase fracture risk. On the other hand, sodium tungstate is an inorganic compound which exerts anti-diabetic activity in experimental studies due to its suggested insulin-mimetic or antioxidant activity. Therefore this study was designed to investigate the effect of tungstate on bone quality in diabetic rat femurs. The rats were divided into four groups: Control (C), tungstate-treated control (C+Tung), diabetes (STZ-D) and tungstate-treated diabetes (STZ-D+Tung). Diabetes mellitus was induced by single injection of streptozotocin (50 mg/kg). The treated rats received 150 mg/kg/day of sodium tungstate for 12 weeks. Sodium tungstate achieved a little (17%) but significant reduction on blood glucose levels, while it didn't recover the reduced body weights of diabetic rats. In addition, impaired bone mechanical quality was reversed, despite the unchanged mineral density. Sodium tungstate administration significantly lowered the 2-thiobarbituric acid reactive substances and restored the activity of tissue antioxidant enzymes such as glutathione peroxidase, catalase and superoxide dismutase in diabetic rats. On the other hand, glutathione levels didn't change in either case. These findings indicate that tungstate can improve the reduced mechanical quality of diabetic rat femurs due probably to reduction of reactive oxygen species and modulation of antioxidant enzymes as well as reduction in blood glucose levels.

  1. GADOLINIUM SOLUBILITY AND VOLATILITY DURING DWPF PROCESSING

    SciTech Connect

    Reboul, S

    2008-01-30

    Understanding of gadolinium behavior, as it relates to potential neutron poisoning applications at the DWPF, has increased over the past several years as process specific data have been generated. Of primary importance are phenomena related to gadolinium solubility and volatility, which introduce the potential for gadolinium to be separated from fissile materials during Chemical Process Cell (CPC) and Melter operations. Existing data indicate that gadolinium solubilities under moderately low pH conditions can vary over several orders of magnitude, depending on the quantities of other constituents that are present. With respect to sludge batching processes, the gadolinium solubility appears to be highly affected by iron. In cases where the mass ratio of Fe:Gd is 300 or more, the gadolinium solubility has been observed to be low, one milligram per liter or less. In contrast, when the ratio of Fe:Gd is 20 or less, the gadolinium solubility has been found to be relatively high, several thousands of milligrams per liter. For gadolinium to serve as an effective neutron poison in CPC operations, the solubility needs to be limited to approximately 100 mg/L. Unfortunately, the Fe:Gd ratio that corresponds to this solubility limit has not been identified. Existing data suggest gadolinium and plutonium are not volatile during melter operations. However, the data are subject to inherent uncertainties preventing definitive conclusions on this matter. In order to determine if gadolinium offers a practical means of poisoning waste in DWPF operations, generation of additional data is recommended. This includes: Gd solubility testing under conditions where the Fe:Gd ratio varies from 50 to 150; and Gd and Pu volatility studies tailored to quantifying high temperature partitioning. Additional tests focusing on crystal aging of Gd/Pu precipitates should be pursued if receipt of gadolinium-poisoned waste into the Tank Farm becomes routine.

  2. Molecular mechanisms of tungstate-induced pancreatic plasticity: a transcriptomics approach

    PubMed Central

    Altirriba, Jordi; Barbera, Albert; Del Zotto, Héctor; Nadal, Belen; Piquer, Sandra; Sánchez-Pla, Alex; Gagliardino, Juan J; Gomis, Ramon

    2009-01-01

    Background Sodium tungstate is known to be an effective anti-diabetic agent, able to increase beta cell mass in animal models of diabetes, although the molecular mechanisms of this treatment and the genes that control pancreas plasticity are yet to be identified. Using a transcriptomics approach, the aim of the study is to unravel the molecular mechanisms which participate in the recovery of exocrine and endocrine function of streptozotocin (STZ) diabetic rats treated with tungstate, determining the hyperglycemia contribution and the direct effect of tungstate. Results Streptozotocin (STZ)-diabetic rats were treated orally with tungstate for five weeks. Treated (STZ)-diabetic rats showed a partial recovery of exocrine and endocrine function, with lower glycemia, increased insulinemia and amylasemia, and increased beta cell mass achieved by reducing beta cell apoptosis and raising beta cell proliferation. The microarray analysis of the pancreases led to the identification of three groups of differentially expressed genes: genes altered due to diabetes, genes restored by the treatment, and genes specifically induced by tungstate in the diabetic animals. The results were corroborated by quantitative PCR. A detailed description of the pathways involved in the pancreatic effects of tungstate is provided in this paper. Hyperglycemia contribution was studied in STZ-diabetic rats treated with phloridzin, and the direct effect of tungstate was determined in INS-1E cells treated with tungstate or serum from untreated or treated STZ-rats, observing that tungstate action in the pancreas takes places via hyperglycemia-independent pathways and via a combination of tungstate direct and indirect (through the serum profile modification) effects. Finally, the MAPK pathway was evaluated, observing that it has a key role in the tungstate-induced increase of beta cell proliferation as tungstate activates the mitogen-activated protein kinase (MAPK) pathway directly by increasing p42/p44

  3. Gadolinium Deposition in Humans: When Did We Learn That Gadolinium Was Deposited In Vivo?

    PubMed

    Huckle, James E; Altun, Ersan; Jay, Michael; Semelka, Richard C

    2016-04-01

    Recently, there have been numerous major peer-reviewed publications reporting deposition of gadolinium in the dentate nucleus and globus pallidus in subjects with normal renal function. This review takes a retrospective look back through the development of gadolinium-based contrast agents to describe the historical evidence of gadolinium deposition in vivo and shows that deposition in the basal ganglia should come as no surprise. Evidence for gadolinium deposition in both animal models and human patients is described. Stability differences among gadolinium contrast agents have long been recognized in vitro, and deposition of gadolinium in tissues has been described in animal models since at least 1984. The first major study that showed deposition in humans appeared in 1998 regarding patients with renal failure and in 2004 in patients with normal renal function. The historical literature indicates that gadolinium retention in healthy patients is occurring, although the clinical consequences of deposition remain unknown.

  4. Sodium tungstate (Na2WO4) exposure increases apoptosis in human peripheral blood lymphocytes.

    PubMed

    Osterburg, Andrew R; Robinson, Chad T; Schwemberger, Sandy; Mokashi, Vishwesh; Stockelman, Michael; Babcock, George F

    2010-01-01

    The potential for adverse health effects of using tungsten and its alloys in military munitions are an important concern to both civilians and the US military. The toxicological implications of exposure to tungsten, its alloys, and the soluble tungstate (Na(2)WO(4)) are currently under investigation. To examine tungstate toxicity, a series of experiments to determine its in vitro effects on cells of the immune system were performed. We identified alterations in isolated human peripheral blood lymphocytes (PBL) treated in vitro with sodium tungstate (0.01, 0.1, 1.0, and 10 mM). Analyses of apoptosis with annexin V and propidium iodide revealed a dose- and time-dependent increase in the quantity of cells in early apoptosis after tungstate exposure. Reductions in the number of cells entering into the cell cycle were also noted. Exposure of PBL to tungstate (1 mM) and Concanavalin A (ConA) for 72 h reduced the number of cells in S and G(2)/M phases of the cell cycle. There were alterations in the numbers of cells in G(0)/G(1), S, and G(2)/M phases of the cell cycle in long-term THP-1 (acute leukemic monocytes) cultures treated with tungstate (0.01, 0.1, 1.0, and 10 mM). Gel electrophoresis, silver staining, and LC-MS/MS showed the cytoplasmic presence of histone H1b and H1d after 72 h of tungstate exposure. The addition of tungstate to cultures resulted in significant reductions in the quantity of interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha), and IL-6 produced by stimulated [CD3/CD28, ConA, or lipopolysaccharide (LPS)] and tungstate-treated lymphocytes. Taken together, these data indicate that tungstate increases apoptosis of PBL, alters cell cycle progression, reduces cytokine production, and therefore warrants further investigation.

  5. Gadolinium deposition in nephrogenic fibrosing dermopathy.

    PubMed

    Boyd, Alan S; Zic, John A; Abraham, Jerrold L

    2007-01-01

    There is growing recognition of the association between the use of gadolinium-containing radiocontrast agents for magnetic resonance imaging and the serious dermal and systemic disease nephrogenic fibrosing dermopathy/nephrogenic systemic fibrosis (NFD/NSF). The pathogenesis of this entity remains unclear; however, our recent observations suggest a likely mechanism for the initial dermal manifestations of this gadolinium toxicity.

  6. Metals Fact Sheet: Gadolinium GD

    SciTech Connect

    1992-10-01

    Gadolinium is a silvery-white, malleable, ductile metallic element used to improve the high-temperature characteristics of iron, chromium, and related metallic alloys. It was named after the French chemist, Gadolin, discoverer of yttrium. This article discusses sources of the element, the world supply and demand, and also a number of applications. With the largest thermal neutron absorption cross section of any element, one of these applications is as a burnable poison in reactors and as neutron absorbers in other nuclear devices.

  7. Development of metal tungstate alloys for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Prasher, D.; Chong, M.; Chang, Y.; Sarker, P.; Huda, M. N.; Gaillard, N.

    2013-09-01

    In the present paper, we report our efforts on the development of metal tungstate alloys for efficient and economical photoelectrochemical water splitting. As suggested by density functional theory (DFT), the addition of copper to the host tungsten trioxide improves the visible light absorption. Past studies at the Hawaii Natural Energy Institute have demonstrated that water splitting with co-sputtered and spray-deposited CuWO4 with 2.2 eV band gap was feasible, although the efficiency of the process was severely limited by charge carrier recombination. Density functional theory calculation showed that CuWO4 contains unfilled mid-gap states and high electron effective mass. To improve transport properties of CuWO4, we hypothesized that copper tungstate (CuWO4) hollow nanospheres could improve holes transfer to the electrolyte and reduce recombination, improving the water splitting efficiency. Nanospheres were synthesized by sonochemical technique in which the precursors used were copper acetate, ammonium meta-tungstate and thiourea (used as a fuel to complete the reaction). All chemicals undergo a high-energy sonication by using ethylene glycol as a solvent. Preliminary linear scan voltammetry (LSV) performed for annealed CuWO4 under front side and back side simulated AM-1.5 illumination demonstrated that the CuWO4 hollow nanospheres were photoactive. Subsequent scanning (SEM) and transmission (TEM) electron microscopy studies revealed the clear formation of nano sized hollow spherical shaped CuWO4 particles. X-ray diffraction analysis showed a clear formation of triclinic CuWO4 structure during the sonochemical process.

  8. Extraction of DNA-cellulose-bound glucocorticoid-receptor complexes with sodium tungstate.

    PubMed

    Murakami, N; Moudgil, V K

    1981-09-04

    Glucocorticoid-receptor complex from rat liver cytosol, activated by warming at 23 degrees C or fractionation with (NH4)2SO4, was adsorbed over DNA-cellulose. This DNA-cellulose-bound [3H]triamcinolone acetonide-receptor complex was extracted in a dose-dependent manner by incubation with different concentrations of sodium tungstate. A 50% recovery of receptor was achieved with 5 mM sodium tungstate. Almost the entire glucocorticoid-receptor complex bound to DNA-cellulose could be extracted with 20 mM sodium tungstate. The [3H]triamcinolone acetonide released from DNA-cellulose following tungstate and molybdate treatment was found to be associated with a macromolecule, as seen by analysis on a Sephadex G-75 column. The glucocorticoid-receptor complex extracted by both the compounds sedimented as a 4 S entity of 5-20% sucrose gradients under low- and high-salt conditions. Addition of tungstate or molybdate to the preparations containing activated receptor had no effect on the sedimentation rate of receptor. However, addition of tungstate to non-activated receptor preparation caused aggregates of larger size. The tungstate-extracted glucocorticoid-receptor complex failed to rebind to DNA-cellulose even after extensive dialysis, whereas receptor in molybdate-extract retained its DNA-cellulose binding capacity.

  9. Oral administration of sodium tungstate improves cardiac performance in streptozotocin-induced diabetic rats.

    PubMed

    Nagareddy, Prabhakara Reddy; Vasudevan, Harish; McNeill, John H

    2005-05-01

    Normalization of hyperglycemia and hyperlipidemia is an important objective in preventing diabetes-induced cardiac dysfunction. Our study investigated the effects of sodium tungstate on cardiac performance in streptozotocin-induced (STZ) diabetic rats based on its potential antidiabetic and antioxidant activity. Male Wistar rats were made STZ-diabetic and then treated with tungstate in their drinking water for 9 weeks. Body mass, food and fluid intake, plasma glucose, insulin, triglyceride, and free fatty acids levels were measured. At the termination of the study period, an oral glucose tolerance test (OGTT) was performed, and cardiac performance was evaluated using an isolated working heart apparatus. Tungstate-treated STZ-diabetic rats showed a significant reduction in fluid and food intake, plasma glucose, triglycerides, and free fatty acid levels, and improved tolerance to glucose in OGTT, owing to tungstate-mediated enhancement of insulin activity rather than increased insulin levels. Left ventricular pressure development, the rate of contraction (+dP/dT), and the rate of relaxation (-dP/dT) were significantly improved in tungstate-treated diabetic rats. Apart from a decreased rate of body mass gain, no other signs of toxicity or hypoglycemic episodes were observed in tungstate-treated rats. This study extends previous observations on the antidiabetic activities of tungstate, and also reports for the first time the salutary effects in preventing diabetic cardiomyopathy.

  10. Toxicity of sodium tungstate to earthworm, oat, radish, and lettuce.

    PubMed

    Bamford, Josie E; Butler, Alicia D; Heim, Katherine E; Pittinger, Charles A; Lemus, Ranulfo; Staveley, Jane P; Lee, K Brian; Venezia, Carmen; Pardus, Michael J

    2011-10-01

    Due to unknown effects of the potential exposure of the terrestrial environment to tungsten substances, a series of toxicity studies of sodium tungstate (Na(2) WO(4) ) was conducted. The effect on earthworm (Eisenia fetida) survival and reproduction was examined using Organisation for Economic Co-operation and Development (OECD) Guideline 222. No effect on either endpoint was seen at the highest concentration tested, resulting in a 56-d no-observed-effect concentration (NOEC) of ≥586 mg tungsten/kg dry soil (nominal concentrations). The effect of sodium tungstate on emergence and growth of plant species was examined according to OECD Guideline 208: oat (Avena sativa), radish (Raphanus sativus), and lettuce (Lactuca sativa). No effects on emergence, shoot height, and dry shoot weight were observed in oats exposed to the highest concentration, resulting in a 21-d NOEC of ≥586 mg tungsten/kg dry soil. The NOECs for radish and lettuce were 65 and 21.7 mg tungsten/kg dry soil (nominal concentrations), respectively. Respective 21-d median effective concentration values (EC50) for radish and lettuce were >586 and 313 mg tungsten/kg dry soil (based on shoot height) (confidence level [CL] -8.5-615); EC25 values were 152 (CL 0-331) and 55 (CL 0-114) mg tungsten/kg dry soil. Results are consistent with the few other tungsten substance terrestrial toxicity studies in the literature.

  11. Femtosecond laser ablation of cadmium tungstate for scintillator arrays

    NASA Astrophysics Data System (ADS)

    Richards, S.; Baker, M. A.; Wilson, M. D.; Lohstroh, A.; Seller, P.

    2016-08-01

    Ultrafast pulsed laser ablation has been investigated as a technique to machine CdWO4 single crystal scintillator and segment it into small blocks with the aim of fabricating a 2D high energy X-ray imaging array. Cadmium tungstate (CdWO4) is a brittle transparent scintillator used for the detection of high energy X-rays and γ-rays. A 6 W Yb:KGW Pharos-SP pulsed laser of wavelength 1028 nm was used with a tuneable pulse duration of 10 ps to 190 fs, repetition rate of up to 600 kHz and pulse energies of up to 1 mJ was employed. The effect of varying the pulse duration, pulse energy, pulse overlap and scan pattern on the laser induced damage to the crystals was investigated. A pulse duration of ≥500 fs was found to induce substantial cracking in the material. The laser induced damage was minimised using the following operating parameters: a pulse duration of 190 fs, fluence of 15.3 J cm-2 and employing a serpentine scan pattern with a normalised pulse overlap of 0.8. The surface of the ablated surfaces was studied using scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. Ablation products were found to contain cadmium tungstate together with different cadmium and tungsten oxides. These laser ablation products could be removed using an ammonium hydroxide treatment.

  12. Anti-Obesity Sodium Tungstate Treatment Triggers Axonal and Glial Plasticity in Hypothalamic Feeding Centers

    PubMed Central

    Amigó-Correig, Marta; Barceló-Batllori, Sílvia; Soria, Guadalupe; Krezymon, Alice; Benani, Alexandre; Pénicaud, Luc; Tudela, Raúl; Planas, Anna Maria; Fernández, Eduardo

    2012-01-01

    Objective This study aims at exploring the effects of sodium tungstate treatment on hypothalamic plasticity, which is known to have an important role in the control of energy metabolism. Methods Adult lean and high-fat diet-induced obese mice were orally treated with sodium tungstate. Arcuate and paraventricular nuclei and lateral hypothalamus were separated and subjected to proteomic analysis by DIGE and mass spectrometry. Immunohistochemistry and in vivo magnetic resonance imaging were also performed. Results Sodium tungstate treatment reduced body weight gain, food intake, and blood glucose and triglyceride levels. These effects were associated with transcriptional and functional changes in the hypothalamus. Proteomic analysis revealed that sodium tungstate modified the expression levels of proteins involved in cell morphology, axonal growth, and tissue remodeling, such as actin, CRMP2 and neurofilaments, and of proteins related to energy metabolism. Moreover, immunohistochemistry studies confirmed results for some targets and further revealed tungstate-dependent regulation of SNAP25 and HPC-1 proteins, suggesting an effect on synaptogenesis as well. Functional test for cell activity based on c-fos-positive cell counting also suggested that sodium tungstate modified hypothalamic basal activity. Finally, in vivo magnetic resonance imaging showed that tungstate treatment can affect neuronal organization in the hypothalamus. Conclusions Altogether, these results suggest that sodium tungstate regulates proteins involved in axonal and glial plasticity. The fact that sodium tungstate could modulate hypothalamic plasticity and networks in adulthood makes it a possible and interesting therapeutic strategy not only for obesity management, but also for other neurodegenerative illnesses like Alzheimer’s disease. PMID:22802935

  13. Sodium tungstate activates glycogen synthesis through a non-canonical mechanism involving G-proteins.

    PubMed

    Zafra, Delia; Nocito, Laura; Domínguez, Jorge; Guinovart, Joan J

    2013-01-31

    Tungstate treatment ameliorates experimental diabetes by increasing liver glycogen deposition through an as yet unidentified mechanism. The signalling mechanism of tungstate was studied in CHOIR cells and primary cultured hepatocytes. This compound exerted its pro-glycogenic effects through a new G-protein-dependent and Tyr-Kinase Receptor-independent mechanism. Chemical or genetic disruption of G-protein signalling prevented the activation of the Ras/ERK cascade and the downstream induction of glycogen synthesis caused by tungstate. Thus, these findings unveil a novel non-canonical signalling pathway that leads to the activation of glycogen synthesis and that could be exploited as an approach to treat diabetes.

  14. Neurobehavioral Effects of Sodium Tungstate Exposure on Rats and Their Progeny

    DTIC Science & Technology

    2007-06-30

    Neurobehavioral Effects of Sodium Tungstate Expo sure on Rats and Their Progeny S.M. McInturf ALYNV. Bekkedal A. Olabisi D. Arfsten E. Wilfong IL...20071116226 Neurobehavioral Effects of Sodium Tungstate Exposure on Rats and. Their Progeny S.M. McInturf M.Y.V. Bekkedal A. Olabisi D. Arfsten E...days of daily tungsten exposure via drinking water. Sprague-Dawley rats were orally dosed with diH20 vehicle, 5 or 125 mg/kg/day of sodium tungstate for

  15. Status of gadolinium enrichment technology at LLNL

    SciTech Connect

    Haynam, C.; Comaskey, B.; Conway, J.; Eggert, J.; Glaser, J.; Ng, E.; Paisner, J.; Solarz, R.; Worden, E.

    1993-01-01

    A method based on,polarization selectivity and three step laser photoionization is presented for separation of the odd isotopes of gadolinium. Measurements of the spectroscopic parameters needed to quantify the excitation pathway are discussed. Model results are presented for the efficiency of photoionization. The vapor properties of electron beam vaporized gadolinium are presented which show dramatic cooling during the expansion of the hot dense vapor into a vacuum. This results in a significant increase in the efficiency of conversion of natural feed into enriched product in the AVLIS process. Production of enriched gadolinium for use in commercial power reactors appears to be economically viable using technology in use at LLNL.

  16. Brain gadolinium deposition after administration of gadolinium-based contrast agents.

    PubMed

    Kanda, Tomonori; Oba, Hiroshi; Toyoda, Keiko; Kitajima, Kazuhiro; Furui, Shigeru

    2016-01-01

    Gadolinium-based contrast agents (GBCAs) consist of gadolinium ions and a chelating agent that binds the gadolinium ion tightly so that its toxicity is not manifested. However, in 2013, an association between brain MRI abnormalities and a history of GBCA administration was first reported. Even in patients with normal renal function, increased signal intensity in the dentate nucleus and globus pallidus on unenhanced T1-weighted images showed a positive correlation with previous exposure to linear chelate type GBCAs, but not to macrocyclic chelate type ones. This difference of GBCAs is speculated to reflect the stability of GBCAs, and de-chelated gadolinium deposition has been strongly suspected. Using inductively coupled plasma mass spectroscopy, gadolinium was detected from patients' brains with a history of repeated GBCA administration. In some cases, the gadolinium concentration of a patient's brain with normal renal function exceeded the gadolinium concentration of the skin in nephrogenic systemic fibrosis patients, but without any histological change. The actual risk has not been documented yet, but it seems important to consider the potential unknown risks of residual gadolinium in our decisions regarding GBCA administration, and to make efforts to minimize any residual gadolinium in the patient's body.

  17. Theoretical calculations of emission of wolframite and scheelite-type tungstate crystals

    SciTech Connect

    Nikolaenko, T.; Hizhnyi, Y.; Nedilko, S.

    2009-01-21

    Tungstate crystals AWO{sub 4} (A = Zn,Cd,Pb) are well-known scintillation materials for various applications in science and technology. In recent years the optical properties of these crystals were intensively studied experimentally and theoretically. However, the origin of luminescence in lead, cadmium and zinc tungstates is still the subject of discussion. According to generally accepted view, the centers of luminescence in AWO{sub 4} crystals are in some or other way related to the tungstate anionic groups. We developed a cluster approach in theoretical investigation of the electronic structure of AWO{sub 4} tungstate crystals based on the configuration interaction (CI) computation in which the lattice vibrations were taken into account.

  18. Vibrational Spectroscopic Studies on Some Double Alkali Tungstates Belonging to Orthorhombic Class at Room Temperature

    SciTech Connect

    Sharaff, Usha; Bajpai, P. K.; Choudhary, R. N. P.

    2011-11-22

    Room temperature IR and Raman spectra of rubidium lithium tungstate and sodium lithium tungstates belonging to double alkali tungstate family are investigated using group theoretical methods. Observed internal and lattice modes in both systems studied are assigned. Analysis of spectral behavior reveals that the effect of site potential around tungstates ion is weak and the factor group splitting is operative. Differences in the lattice mode mixing and splitting of internal modes is influenced by the statistical ordering between two alkali ions having large and small ionic radii and is explained using size and charge effect observed earlier in scheelite type of structure. Thus, vibrational spectroscopic analysis may be a tool to understand the alkali ion ordering in double alkali systems.

  19. Ultrafine silver nanoparticles obtained from ethylene glycol at room temperature: catalyzed by tungstate ions.

    PubMed

    Li, Jin; Zhu, Junwu; Liu, Xiaoheng

    2014-01-07

    Ethylene glycol (EG) has been widely utilized to fabricate silver nanoparticles with uniform size and morphology. However, the majority of the work reported to date using EG routinely require not only heating, but also a surfactant. In the present paper, we report a surfactant-free and facile method for the synthesis of fairly monodisperse smaller silver nanoparticles (~6 nm) through the reaction of silver ions with EG by using tungstates (such as potassium tungstate, sodium tungstate) as catalysts at room temperature. Particularly, in this method, tungstates as catalysts can dramatically speed up the reduction of silver ions, and EG acts as both a solvent and a reducing agent to reduce silver ions to Ag metal. Meantime, we have carried out a series of experiments to investigate the performance of the as-prepared silver nanoparticles. It was found that the silver nanoparticles show excellent catalytic activity for the reduction of 4-nitrophenol in the presence of NaBH4.

  20. Molybdate and tungstate act like vanadate on glucose metabolism in isolated hepatocytes.

    PubMed Central

    Fillat, C; Rodríguez-Gil, J E; Guinovart, J J

    1992-01-01

    In rat hepatocytes, molybdate and tungstate inactivate glycogen synthase by a mechanism independent of Ca2+ and activate glycogen phosphorylase by a Ca(2+)-dependent mechanism. On the other hand, both molybdate and tungstate increase fructose 2,6-bisphosphate levels and counteract the decrease in this metabolite induced by glucagon. These effectors do not directly modify 6-phosphofructo-2-kinase activity, even though they partially counteract the inactivation of this enzyme induced by glucagon. These effects are related to an increase on the glycolytic flux, as indicated by the increase in L-lactate and CO2 production and the decrease in glucose 6-phosphate levels in the presence of glucose. All these effects are similar to those previously reported for vanadate, although molybdate and tungstate are less effective than vanadate. These results could indicate that molybdate, tungstate and vanadate act on glucose metabolism in isolated hepatocytes by a similar mechanism of action. PMID:1313228

  1. Raman studies of A2MWO6 tungstate double perovskites.

    PubMed

    Andrews, R L; Heyns, A M; Woodward, P M

    2015-06-21

    The Raman spectra of seven A(2)MWO(6) tungstate double perovskites are analysed. Ba(2)MgWO(6) is a cubic double perovskite with Fm3[combining macron]m symmetry and its Raman spectrum contain three modes that can be assigned in a straightforward manner. A fourth mode, the asymmetric stretch of the [WO(6)](6-) octahedron, is too weak to be observed. The symmetry of Ba(2)CaWO(6) is lowered to tetragonal I4/m due to octahedral tilting, but the distortion is sufficiently subtle that the extra bands predicted to appear in the Raman spectrum are not observed. The remaining five compounds have additional octahedral tilts that lower the symmetry to monoclinic P2(1)/n. The further reduction of symmetry leads to the appearance of additional lattice modes involving translations of the A-site cations and librations of the octahedra. Comparing the Raman spectra of fourteen different A(2)MWO(6) tungstate double perovskites shows that the frequency of the symmetric stretch (ν(1)) of the [WO(6)](6-) octahedron is relatively low for cubic perovskites with tolerance factors greater than one due to underbonding of the tungsten and/or M cation. The frequency of this mode increases rapidly as the tolerance factor drops below one, before decreasing gradually as the octahedral tilting gets larger. The frequency of the oxygen bending mode (ν(5)) is shown to be dependent on the mass of the A-site cation due to coupling of the internal bending mode with external A-site cation translation modes.

  2. Phosphorylation events implicating p38 and PI3K mediate tungstate-effects in MIN6 beta cells.

    PubMed

    Piquer, Sandra; Barceló-Batllori, Sílvia; Julià, Marta; Marzo, Nuria; Nadal, Belen; Guinovart, Joan J; Gomis, Ramon

    2007-06-29

    Oral administration of sodium tungstate is an effective treatment for diabetes in animal models. Several lines of evidence indicate the pancreatic beta cell as one of the targets of tungstate action. Here, we examined the molecular mechanism by which this compound exerts its effects on the beta cell line MIN6. Tungstate treatment induced phosphorylation and subsequent activation of p38 and PI3K which in turn are implicated in tungstate PDX-1 nuclear localization and activation. Although no effect was observed in glucose-induced insulin secretion we found that tungstate activates basal insulin release, a process driven, at least in part, by activation of p38. These results show a direct involvement of p38 and PI3K phosphorylation in the mechanism of action of tungstate in the beta cell.

  3. Phosphorylation events implicating p38 and PI3K mediate tungstate-effects in MIN6 beta cells

    SciTech Connect

    Piquer, Sandra; Gomis, Ramon . E-mail: rgomis@clinic.ub.es

    2007-06-29

    Oral administration of sodium tungstate is an effective treatment for diabetes in animal models. Several lines of evidence indicate the pancreatic beta cell as one of the targets of tungstate action. Here, we examined the molecular mechanism by which this compound exerts its effects on the beta cell line MIN6. Tungstate treatment induced phosphorylation and subsequent activation of p38 and PI3K which in turn are implicated in tungstate PDX-1 nuclear localization and activation. Although no effect was observed in glucose-induced insulin secretion we found that tungstate activates basal insulin release, a process driven, at least in part, by activation of p38. These results show a direct involvement of p38 and PI3K phosphorylation in the mechanism of action of tungstate in the beta cell.

  4. Sodium tungstate decreases sucrase and Na+/D-glucose cotransporter in the jejunum of diabetic rats.

    PubMed

    Miró-Queralt, Montserrat; Guinovart, Joan J; Planas, Joana M

    2008-09-01

    Sodium tungstate reduces glycemia and reverts the diabetic phenotype in several induced and genetic animal models of diabetes. Oral administration of this compound has recently emerged as an effective treatment for diabetes. Here we examined the effects of 30 days of oral administration of tungstate on disaccharidase and Na+/D-glucose cotransporter (SGLT1) activity in the jejunum of control and streptozotocin-induced diabetic rats. Diabetes increased sucrase-specific activity in the jejunal mucosa but did not affect the activity of lactase, maltase, or trehalase. The abundance and the maximal rate of transport of SGLT1 in isolated brush-border membrane vesicles also increased. Tungstate decreased sucrase activity and normalized SGLT1 expression and activity in the jejunum of diabetic rats. Furthermore, tungstate did not change the affinity of SGLT1 for d-glucose and had no effect on the diffusional component. In control animals, tungstate had no effect on disaccharidases or SGLT1 expression. Northern blot analysis showed that the amount of specific SGLT1 mRNA was the same in the jejunum from all experimental groups, thereby indicating that changes in SGLT1 abundance are due to posttranscriptional mechanisms. We conclude that the antidiabetic effect of tungstate is partly due to normalization of the activity of sucrase and SGLT1 in the brush-border membrane of enterocytes.

  5. Sodium tungstate induced neurological alterations in rat brain regions and their response to antioxidants.

    PubMed

    Sachdeva, Sherry; Pant, Satish C; Kushwaha, Pramod; Bhargava, Rakesh; Flora, Swaran J S

    2015-08-01

    Tungsten, recognized recently as an environmental contaminant, is being used in arms and ammunitions as substitute to depleted uranium. We studied the effects of sodium tungstate on oxidative stress, few selected neurological variables like acetylcholinesterase, biogenic amines in rat brain regions (cerebral cortex, hippocampus and cerebellum) and their prevention following co-administration of N-acetylcysteine (NAC), naringenin and quercetin. Animals were sub-chronically exposed to sodium tungstate (100 ppm in drinking water) and orally co-supplemented with different antioxidants (0.30 mM) for three months. Sodium tungstate significantly decreased the activity of acetylcholinesterase, dopamine, nor-epinephrine and 5-hydroxytryptamine levels while it increased monoamine oxidase activity in different brain regions. Tungstate exposure produced a significant increase in biochemical variables indicative of oxidative stress while, neurological alterations were more pronounced in the cerebral cortex compared to other regions. Co-administration of NAC and flavonoids with sodium tungstate significantly restored glutathione, prevented changes in the brain biogenic amines, reactive oxygen species (ROS) and TBARS levels in the different brain regions. The protection was more prominent in the animals co-administered with NAC. We can thus conclude that sodium tungstate induced brain oxidative stress and the alterations in some neurological variables can effectively be reduced by co-supplementation of NAC. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Effect of sodium tungstate on visual evoked potentials in diabetic rats

    PubMed Central

    Bulut, Mehmet; Dönmez, Barış Özgür; Öztürk, Nihal; Başaranlar, Göksun; Kencebay Manas, Ceren; Derin, Narin; Özdemir, Semir

    2016-01-01

    AIM To evaluate the effect of sodium tungstate on visual evoked potentials (VEPs) in diabetic rats. METHODS Wistar rats were randomly divided into three groups as normal control, diabetic control and diabetic rats treated with sodium tungstate. Diabetes was induced by single intraperitoneal injection of streptozotocin (50 mg/kg). Sodium tungstate [40 mg/(kg·d)] was administered for 12wk and then VEPs were recorded. Additionally, thiobarbituric acid reactive substance (TBARS) levels were measured in brain tissues. RESULTS The latencies of P1, N1, P2, N2 and P3 waves were significantly prolonged in diabetic rats compared with control group. Diabetes mellitus caused an increase in the lipid peroxidation process that was accompanied by changes in VEPs. However, prolonged latencies of VEPs for all components returned to control levels in sodium tungstate-treated group. The treatment of sodium tungstate significantly decreased brain TBARS levels and depleted the prolonged latencies of VEP components compared with diabetic control group. CONCLUSION Sodium tungstate shows protective effects on visual pathway in diabetic rats, and it can be worthy of further study for potential use. PMID:27275420

  7. Are gadolinium contrast agents suitable for gadolinium neutron capture therapy?

    PubMed

    De Stasio, Gelsomina; Rajesh, Deepika; Casalbore, Patrizia; Daniels, Matthew J; Erhardt, Robert J; Frazer, Bradley H; Wiese, Lisa M; Richter, Katherine L; Sonderegger, Brandon R; Gilbert, Benjamin; Schaub, Sebastien; Cannara, Rachel J; Crawford, John F; Gilles, Mary K; Tyliszczak, Tolek; Fowler, John F; Larocca, Luigi M; Howard, Steven P; Mercanti, Delio; Mehta, Minesh P; Pallini, Roberto

    2005-06-01

    Gadolinium neutron capture therapy (GdNCT) is a potential treatment for malignant tumors based on two steps: (1) injection of a tumor-specific (157)Gd compound; (2) tumor irradiation with thermal neutrons. The GdNC reaction can induce cell death provided that Gd is proximate to DNA. Here, we studied the nuclear uptake of Gd by glioblastoma (GBM) tumor cells after treatment with two Gd compounds commonly used for magnetic resonance imaging, to evaluate their potential as GdNCT agents. Using synchrotron X-ray spectromicroscopy, we analyzed the Gd distribution at the subcellular level in: (1) human cultured GBM cells exposed to Gd-DTPA or Gd-DOTA for 0-72 hours; (2) intracerebrally implanted C6 glioma tumors in rats injected with one or two doses of Gd-DOTA, and (3) tumor samples from GBM patients injected with Gd-DTPA. In cell cultures, Gd-DTPA and Gd-DOTA were found in 84% and 56% of the cell nuclei, respectively. In rat tumors, Gd penetrated the nuclei of 47% and 85% of the tumor cells, after single and double injection of Gd-DOTA, respectively. In contrast, in human GBM tumors 6.1% of the cell nuclei contained Gd-DTPA. Efficacy of Gd-DTPA and Gd-DOTA as GdNCT agents is predicted to be low, due to the insufficient number of tumor cell nuclei incorporating Gd. Although multiple administration schedules in vivo might induce Gd penetration into more tumor cell nuclei, a search for new Gd compounds with higher nuclear affinity is warranted before planning GdNCT in animal models or clinical trials.

  8. Evaluation of absorbed dose in Gadolinium neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Abdullaeva, Gayane; Djuraeva, Gulnara; Kim, Andrey; Koblik, Yuriy; Kulabdullaev, Gairatulla; Rakhmonov, Turdimukhammad; Saytjanov, Shavkat

    2015-02-01

    Gadolinium neutron capture therapy (GdNCT) is used for treatment of radioresistant malignant tumors. The absorbed dose in GdNCT can be divided into four primary dose components: thermal neutron, fast neutron, photon and natural gadolinium doses. The most significant is the dose created by natural gadolinium. The amount of gadolinium at the irradiated region is changeable and depends on the gadolinium delivery agent and on the structure of the location where the agent is injected. To de- fine the time dependence of the gadolinium concentration ρ(t) in the irradiated region the pharmacokinetics of gadolinium delivery agent (Magnevist) was studied at intratumoral injection in mice and intramuscular injection in rats. A polynomial approximation was applied to the experimental data and the influence of ρ(t) on the relative change of the absorbed dose of gadolinium was studied.

  9. Sodium tungstate attenuate oxidative stress in brain tissue of streptozotocin-induced diabetic rats.

    PubMed

    Nakhaee, Alireza; Bokaeian, Mohammad; Akbarzadeh, Azim; Hashemi, Mohammad

    2010-08-01

    High blood glucose concentration in diabetes induces free radical production and, thus, causes oxidative stress. Damage of cellular structures by free radicals play an important role in development of diabetic complications. In this study, we evaluated effects of sodium tungstate on enzymatic and nonenzymatic markers of oxidative stress in brain of streptozotocin (STZ)-induced diabetic rats. Rats were divided into four groups (ten rats in each group): untreated control, sodium tungstate-treated control, untreated diabetic, and sodium tungstate-treated diabetic. Diabetes was induced with an intraperitoneal STZ injection (65 mg/kg body weight), and sodium tungstate with concentration of 2 g/L was added to drinking water of treated animals for 4 weeks. Diabetes caused a significant increase in the brain thiobarbituric acid reactive substances (P < 0.01) and protein carbonyl levels (P < 0.01) and a decrease in ferric reducing antioxidant power (P < 0.01). Moreover, diabetic rats presented a reduction in brain glucose-6-phosphate dehydrogenase (21%), superoxide dismutase (41%), glutathione peroxidase (19%), and glutathione reductase (36%) activities. Sodium tungstate reduced the hyperglycemia and restored the diabetes-induced changes in all mentioned markers of oxidative stress. However, catalase activity was not significantly affected by diabetes (P = 0.4), while sodium tungstate caused a significant increase in enzyme activity of treated animals (P < 0.05). Data of present study indicated that sodium tungstate can ameliorate brain oxidative stress in STZ-induced diabetic rats, probably by reducing of the high glucose-induced oxidative stress and/or increasing of the antioxidant defense mechanisms.

  10. Structural, optical and magnetic properties of gadolinium sesquioxide nanobars synthesized via thermal decomposition of gadolinium oxalate

    SciTech Connect

    Manigandan, R.; Giribabu, K.; Suresh, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2013-10-15

    Graphical abstract: - Highlights: • The cubic Gd{sub 2}O{sub 3} nanobars are synthesized by decomposition of C{sub 6}H{sub 20}Gd{sub 2}O{sub 22}. • The nanoparticles are rectangular bar shape with high porous surface. • The combination of magnetic and optical properties within a single particle. • The Gd{sub 2}O{sub 3} nanobars have tailorable nanostructure, wide bandgap and are paramagnetic. - Abstract: Gadolinium oxide nanobars were obtained by thermal decomposition of gadolinium oxalate, which was synthesized by the chemical precipitation method along with glycerol. The functional group analysis and formation of gadolinium oxide from gadolinium oxalate were characterized by the Fourier transform infrared spectroscopy and thermo gravimetric analyzer. The crystal structure, average crystallite size, and lattice parameter were analyzed by X-ray diffraction technique. Moreover, Raman shifts, elemental composition and morphology of the gadolinium oxide was widely investigated by the laser Raman microscope, X-ray photoelectron spectroscopy, FE-SEM-EDAX and HR-TEM, respectively. Furthermore, the optical properties like band gap, absorbance measurement of the gadolinium oxide were extensively examined. In addition, the paramagnetic property of gadolinium oxide nanobars was explored by the vibrating sample magnetometer.

  11. Incidence of immediate gadolinium contrast media reactions.

    PubMed

    Prince, Martin R; Zhang, Honglei; Zou, Zhitong; Staron, Ronald B; Brill, Paula W

    2011-02-01

    Our objective was to determine the incidence of immediate adverse events for gadolinium-based contrast agents. All gadolinium-based contrast agent adverse events reported to radiology quality assurance committees were graded according to American College of Radiology criteria and divided by the total number of injections to determine incidence during the past 10 years. For each event, an age- and examination-matched control patient was identified to compare sex, weight, creatinine, eosinophil count, allergic history and gadolinium-based contrast agent dose differences. The U.S. Food and Drug Administration (FDA) Adverse Event Reporting System (AERS) database was analyzed to compare local experience to national trends. Abdominal MRI had the highest rates of adverse events, 0.013% compared with brain (0.0045%, p < 0.001) or spine (0.0034%, p < 0.001). Adverse events were more likely in women, with a female to male ratio of 3.3, and in patients with history of prior allergic reactions (p < 0.001). Immediate adverse events rates were 0.2, 0.5, 1.2, and 3.3 per 1,000 injections for gadodiamide, gadopentetate dimeglumine, gadobenate dimeglumine, and gadoteridol, respectively. Gadobenate dimeglumine had more severe patient reactions, including three patients who arrested (defined as the patient becoming unresponsive and the code team being called), one of whom died. From 2004 to 2009, the FDA received reports on 40 gadolinium-based contrast agent U.S. deaths unrelated to nephrogenic systemic fibrosis, with an incidence per million doses of 0.15, 0.19, 0.97, 2.7, and 0.7 for gadodiamide, gadoversetimide, gadopentetate dimeglumine, gadobenate dimeglumine, and gadoteridol, respectively. This limited retrospective analysis shows that gadolinium-based contrast agents are very safe, with only rare reports of death, and raises the possibility that nonionic linear gadolinium-based contrast agents and gadopentetate dimeglumine may have fewer severe immediate adverse events

  12. Enhancement of the electron electric dipole moment in gadolinium garnets

    SciTech Connect

    Mukhamedjanov, T.N.; Dzuba, V.A.; Sushkov, O.P.

    2003-10-01

    Effects caused by the electron electric dipole moment (EDM) in gadolinium garnets are considered. Experimental studies of these effects could improve the current upper limit on the electron EDM by several orders of magnitude. We suggest a consistent theoretical model and perform calculations of observable effects in gadolinium gallium garnet and gadolinium iron garnet. Our calculation accounts for both direct and exchange diagrams.

  13. Amorphous tungstate precursor route to nanostructured tungsten oxide film with electrochromic property.

    PubMed

    Jeon, Ie-Rang; Kang, Joo-Hee; Paek, Seung-Min; Hwang, Seong-Ju; Choy, Jin-Ho

    2011-07-01

    Electrochromic tungsten oxide (WO3) films on ITO glass were fabricated by spin-coating with a tungsten peroxy acid solution, which was prepared by adding an equivolume mixture of hydrogen peroxide and glacial acetic acid to tungsten metal powder. The structural evolution of the tungstate precursor upon heat treatment was studied by X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) analyses, which indicated that the as-synthesized tungstate transformed into nanocrystalline WO3 upon heating. It is, therefore, quite clear that as-synthesized tungstate can be a good precursor for electrochromic WO3 films. A series of WO3 thin films were prepared on ITO glass by spin-coating with different concentrations of tungsten peroxy acid solution and then post-annealing at various temperatures. Depending on the concentration of the tungstate coating solution (200-500 mg mL(-1)) and the annealing temperature (100-300 degrees C), the thickness and WO3 content as well as the electrochromic properties of WO3 films can be controlled. As a result, the optimum fabrication conditions were determined to be a tungstate solution concentration of 300-400 mg mL(-1) and a post-annealing temperature of 200 degrees C. Finally, an inorganic-inorganic hybrid electrochromic device (ECD) composed of optimized WO3 and Prussian Blue (PB) with desirable coloration efficiency was successfully developed.

  14. The antidiabetic agent sodium tungstate activates glycogen synthesis through an insulin receptor-independent pathway.

    PubMed

    Domínguez, Jorge E; Muñoz, M Carmen; Zafra, Delia; Sanchez-Perez, Isabel; Baqué, Susanna; Caron, Martine; Mercurio, Ciro; Barberà, Albert; Perona, Rosario; Gomis, Ramon; Guinovart, Joan J

    2003-10-31

    Sodium tungstate is a powerful antidiabetic agent when administered orally. In primary cultured hepatocytes, tungstate showed insulin-like actions, which led to an increase in glycogen synthesis and accumulation. However, this compound did not significantly alter the insulin receptor activation state or dephosphorylation rate in cultured cells (CHO-R) or in primary hepatocytes, in either short or long term treatments. In contrast, at low concentrations, tungstate induced a transient strong activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) after 5-10 min of treatment, in a similar way to insulin. Moreover, this compound did not significantly delay or inhibit the dephosphorylation of ERK1/2. ERK1/2 activation triggered a cascade of downstream events, which included the phosphorylation of p90rsk and glycogen synthase-kinase 3beta. Experiments with a specific inhibitor of ERK1/2 activation and kinase assays indicate that these proteins were directly involved in the stimulation of glycogen synthase and glycogen synthesis induced by tungstate without a direct involvement of protein kinase B (PKB/Akt). These results show a direct involvement of ERK1/2 in the mechanism of action of tungstate at the hepatic level.

  15. Tungstate stimulates insulin release and inhibits somatostatin output in the perfused rat pancreas.

    PubMed

    Silvestre, Ramona A; Egido, Eva M; Hernández, Raquel; Marco, José

    2005-09-05

    In the rat pancreas, infusion of sodium-tungstate stimulates basal insulin release in a dose-dependent manner. We have studied tungstate's effects on the insulin secretion elicited by various B-cell secretagogues. Somatostatin output was also measured. The study was performed in the perfused pancreas isolated from normal or somatostatin-depleted pancreases as induced by cysteamine pre-treatment. In control rats, tungstate co-infusion (5 mM) potentiated the insulin secretory responses to glucose (2.7-fold; P<0.01), arginine (2-fold; P<0.01), exendin-4 (3-fold; P<0.01), glucagon (4-fold; P<0.05), and tolbutamide (2-fold; P<0.01). It also inhibited the somatostatin secretory responses to glucose (90%; P<0.01), arginine (95%; P<0.01), glucagon (80%; P<0.025), exendin-4 (80%; P<0.05) and tolbutamide (85%; P<0.01). In somatostatin-depleted pancreases, the stimulatory effect of tungstate on basal insulin secretion and its potentiation of arginine-induced insulin output were comparable to those found in control rats. Our observations suggest an amplifying effect of tungstate on a common step in the insulin stimulus/secretion coupling process, and would rule out a paracrine effect mediated by the inhibition of somatostatin secretion induced by this compound.

  16. Tungstate treatment improves Leydig cell function in streptozotocin-diabetic rats.

    PubMed

    Ballester, Joan; Domínguez, Jorge; Muñoz, M Carmen; Sensat, Meritxell; Rigau, Teresa; Guinovart, Joan J; Rodríguez-Gil, Joan E

    2005-01-01

    Oral administration of sodium tungstate to adult male streptozotocin-diabetic rats for 3 months normalized serum levels of glucose, insulin, luteinizing hormone, and follicle-stimulating hormone. These effects were accompanied by an increase in reproductive performance, which was related to a strong improvement in Leydig cell function markers, such as the recovery of the number of Leydig cells and serum testosterone levels. Moreover, this in vivo recovery was related to a concomitant increase in the cell expression of insulin receptors. Tungstate treatment did not modify Leydig cell function in healthy rats. Furthermore, the addition of tungstate or insulin to the mTLC-1 cell line from Leydig cell origin increased the phosphorylation states of MAP-kinase and glycogen synthase kinase-3. Our results indicate that tungstate treatment in diabetic rats leads to a recovery of reproductive performance by increasing the number of Leydig cells. This increase contributes to the recovery of their functionality, thereby improving the overall function of these cells. We propose that this improvement is caused by the combined effect of the tungstate-induced normalization of insulin glucose and luteinizing hormone serum levels and a direct action of the effector on Leydig cells through modulation of at least MAP-kinase and glycogen synthase kinase-3 activities.

  17. Motexafin gadolinium: gadolinium (III) texaphyrin, gadolinium texaphyrin, Gd-Tex, GdT2B2, PCI 0120.

    PubMed

    2004-01-01

    Motexafin gadolinium [gadolinium (III) texaphyrin, gadolinium texaphyrin, Gd-Tex, GdT2B2, PCI 0120] is a radiosensitising agent developed for use in cancer therapy. It is cytotoxic in haematological malignancies by selectively localising in cancer cells that have high rates of metabolism. Motexafin gadolinium inhibits cellular respiration resulting in the production of reactive oxygen species and inducing apoptosis. It is being developed by Pharmacyclics in the US. Bulk motexafin gadolinium is supplied to Pharmacyclics by the US company, Celanese, through a manufacturing and supply agreement between the two companies. In June 2003, at the 39th Annual Meeting of the American Society of Clinical Oncology (ASCO-2003), the importance of having an agent for the treatment of brain metastases from lung cancer was highlighted. Results of a phase III study were presented that showed that motexafin gadolinium treatment was associated with a delay in time to neurological and neurocognitive progression in lung cancer patients. This was an important finding, as 46.6% of lung cancer patients already have brain metastases at the time of initial diagnosis, compared with only 2.7% of breast cancer patients. Brain metastases are also often the only site of metastatic disease in patients with lung cancer. In December 2002, Pharmacyclics began a phase III trial of motexafin gadolinium in patients with brain metastases (brain cancer in phase table) from lung cancer in the US, Europe, Canada and Australia. The trial is known as the Study of neurologic progression with Motexafin gadolinium And Radiation Therapy (SMART) and will compare whole-brain irradiation with whole-brain irradiation plus motexafin gadolinium in 550 patients. The primary efficacy endpoint is time to neurological progression and the secondary endpoints are survival and neurocognitive function. In January 2003, the US FDA completed its Special Protocol Assessment (SPA) of the SMART trial with a positive result and by

  18. Synthesis and Characterization of Zirconium Tungstate Ultra-Thin Fibers

    SciTech Connect

    Zhang, Lifeng; Howe, Jane Y; Fong, Hao; Zhang, Yan

    2009-01-01

    This study reports an innovative method of electrospinning followed by pyrolysis to synthesize zirconium tungstate (ZrW2O8), a material with negative coefficient of thermal expansion (CTE), in ultra-thin fiber form. Morphologies and microstructures of the as-electrospun precursor fibers, the heat-treated intermediate fibers, and the final ZrW2O8 ultra-thin fibers were characterized by SEM, XRD, and TEM. The ZrW2O8 ultra-thin fibers had diameters in the sub-micrometer range with aspect ratios larger than 100; these fibers were polycrystalline, and consisted of single crystalline ZrW2O8 crystallites with sizes of 30-50 nm and surface roughness of several nanometers. The ZrW2O8 ultra-thin fibers are expected to outperform spherically, cylindrically, and/or irregularly shaped polycrystalline ZrW2O8 particles for the development of composites with precisely controlled CTEs. Additionally, this reported method could be utilized as a general approach to convert nano-scaled inorganic particles into fibers.

  19. Preclinical and Clinical Studies for Sodium Tungstate: Application in Humans.

    PubMed

    Bertinat, Romina; Nualart, Francisco; Li, Xuhang; Yáñez, Alejandro J; Gomis, Ramón

    2015-02-01

    Diabetes is a complex metabolic disorder triggered by the deficient secretion of insulin by the pancreatic β-cell or the resistance of peripheral tissues to the action of the hormone. Chronic hyperglycemia is the major consequence of this failure, and also the main cause of diabetic problems. Indeed, several clinical trials have agreed in that tight glycemic control is the best way to stop progression of the disease. Many anti-diabetic drugs for treatment of type 2 diabetes are commercially available, but no ideal normoglycemic agent has been developed yet. Moreover, weight gain is the most common side effect of many oral anti-diabetic agents and insulin, and increased weight has been shown to worsen glycemic control and increase the risk of diabetes progression. In this sense, the inorganic salt sodium tungstate (NaW) has been studied in different animal models of metabolic syndrome and diabetes, proving to have a potent effect on normalizing blood glucose levels and reducing body weight, without any hypoglycemic action. Although the liver has been studied as the main site of NaW action, positive effects have been also addressed in muscle, pancreas, brain, adipose tissue and intestine, explaining the effective anti-diabetic action of this salt. Here, we review NaW research to date in these different target organs. We believe that NaW deserves more attention, since all available anti-diabetic treatments remain suboptimal and new therapeutics are urgently needed.

  20. Preclinical and Clinical Studies for Sodium Tungstate: Application in Humans

    PubMed Central

    Bertinat, Romina; Nualart, Francisco; Li, Xuhang; Yáñez, Alejandro J.; Gomis, Ramón

    2015-01-01

    Diabetes is a complex metabolic disorder triggered by the deficient secretion of insulin by the pancreatic β-cell or the resistance of peripheral tissues to the action of the hormone. Chronic hyperglycemia is the major consequence of this failure, and also the main cause of diabetic problems. Indeed, several clinical trials have agreed in that tight glycemic control is the best way to stop progression of the disease. Many anti-diabetic drugs for treatment of type 2 diabetes are commercially available, but no ideal normoglycemic agent has been developed yet. Moreover, weight gain is the most common side effect of many oral anti-diabetic agents and insulin, and increased weight has been shown to worsen glycemic control and increase the risk of diabetes progression. In this sense, the inorganic salt sodium tungstate (NaW) has been studied in different animal models of metabolic syndrome and diabetes, proving to have a potent effect on normalizing blood glucose levels and reducing body weight, without any hypoglycemic action. Although the liver has been studied as the main site of NaW action, positive effects have been also addressed in muscle, pancreas, brain, adipose tissue and intestine, explaining the effective anti-diabetic action of this salt. Here, we review NaW research to date in these different target organs. We believe that NaW deserves more attention, since all available anti-diabetic treatments remain suboptimal and new therapeutics are urgently needed. PMID:25995968

  1. Characterization and Recovery of Lead Tungstate (PWO4) Crystals

    NASA Astrophysics Data System (ADS)

    McShane, Abigail; Griggs, Dannie

    2016-09-01

    The potential of Lead Tungstate (PWO) crystals in EM calorimeters like the Neutral Particle Spectrometer at 12 GeV JLab and future particle identification detectors of the Electron Ion Collider has been researched extensively. The small Moliere radius of PWO crystals make them ideal for use in a compact detector and their light yield outperforms that of other heavy crystals. Recent measurements have shown large variations in crystal properties. This is a major concern for the construction of particle identification detectors. Testing of the crystal uniformity and understanding the origin of the variation have thus become necessary. The characterization of PWO includes measurements of the crystal dimensions, optical transmittance, both longitudinal and transverse, the light yield and decay kinetics to identify slow luminescence components, as well as tests of radiation hardness. Optical clarity after radiation damage can in principle be restored by stimulated recovery with light. Optical bleaching with blue light is the default method, but curing at longer wavelength may be possible. The results of crystal characterization and effects of radiation on optical properties, as well as the effectiveness and practicality of the LED curing system will be discussed. This work was supported in part by NSF Grant PHY-1306227.

  2. pH-dependent effects of sodium tungstate on the steroid-binding properties of the hen oviduct progesterone receptor.

    PubMed

    Murakami, N; Quattrociocchi, T M; Szocik, J F; Moudgil, V K

    1982-11-24

    Effects of sodium tungstate on the steroid-binding properties of hen oviduct progesterone receptor were examined and were found to be pH-dependent. When freshly prepared hen oviduct cytosol containing progesterone receptor was heated at 37 degrees C for 20 min, its ability to bind [3H]progesterone decreased to 20% level of unheated samples. At pH 7, presence of 2-3 mM tungstate during the above incubation period reduced this loss of binding. At higher tungstate concentrations (greater than 5 mM), this stabilizing effect was gradually abolished. Similar results were obtained with preparations that contained [3H]progesterone-receptor complexes; 70-80% of which remained after a 20 min incubation at 37 degrees C in the presence of 2-3 mM tungstate at pH 7. At pH 8, presence of tungstate (1-10 mM) during the 37 degrees C incubation stabilized both the steroid-bound and the unoccupied progesterone receptor in a concentration-dependent manner. The extent of steroid binding by the receptor at 4 degrees C remained unchanged in the presence of up to 10 mM tungstate at both pH 7 and pH 8 assay conditions while presence of 20 mM tungstate lowered this binding capacity. These results indicate that tungstate effects may be mediated via its interaction with the progesterone receptor.

  3. A toxicological study of gadolinium nitrate

    SciTech Connect

    London, J.E.

    1988-05-01

    The sensitization study in the guinea pig did not show gadolinium nitrate to have potential sensitizing properties. Skin application studies in the rabbit demonstrated that it was cutaneously a severe irritant. This material was considered an irritant in the rabbit eye application studies. 3 refs., 1 tab.

  4. Gadolinium: Central Metal of the Lanthanoids

    ERIC Educational Resources Information Center

    Laing, Michael

    2009-01-01

    The physical and chemical properties of gadolinium are compared with those of the other lanthanoids. Some properties are intermediate between those of lanthanum and lutetium; some between those of barium and hafnium; and others (unexpectedly) between those of ytterbium and lutetium. Both the remarkably high molar heat capacity of the metal and the…

  5. Gadolinium: Central Metal of the Lanthanoids

    ERIC Educational Resources Information Center

    Laing, Michael

    2009-01-01

    The physical and chemical properties of gadolinium are compared with those of the other lanthanoids. Some properties are intermediate between those of lanthanum and lutetium; some between those of barium and hafnium; and others (unexpectedly) between those of ytterbium and lutetium. Both the remarkably high molar heat capacity of the metal and the…

  6. Sodium tungstate decreases the phosphorylation of tau through GSK3 inactivation.

    PubMed

    Gómez-Ramos, Alberto; Domínguez, Jorge; Zafra, Delia; Corominola, Helena; Gomis, Ramon; Guinovart, Joan J; Avila, Jesús

    2006-02-01

    Tungstate treatment increases the phosphorylation of glycogen synthase kinase-3beta (GSK3beta) at serine 9, which triggers its inactivation both in cultured neural cells and in vivo. GSK3 phosphorylation is dependent on the activation of extracellular signal-regulated kinases 1/2 (ERK1/2) induced by tungstate. As a consequence of GSK3 inactivation, the phosphorylation of several GSK3-dependent sites of the microtubule-associated protein tau decreases. Tungstate reduces tau phosphorylation only in primed sequences, namely, those prephosphorylated by other kinases before GSK3beta modification, which are serines 198, 199, or 202 and threonine 231. The phosphorylation at these sites is involved in reduction of the interaction of tau with microtubules that occurs in Alzheimer's disease.

  7. The effects of molybate, tungstate and lxd on aldehyde oxidase and xanthine dehydrogenase in Drosophila melanogaster.

    PubMed

    Bentley, M M; Williamson, J H; Oliver, M J

    1981-01-01

    The effects of dietary sodium molybdate and sodium tungstate on eye color and aldehyde oxidase and xanthine dehydrogenase activities have been determined in Drosophila melanogaster. Dietary sodium tungstate administration has been used as a screening procedure to identify two new lxd alleles. Tungstate administration results in increased frequencies of "brown-eyed" flies in lxd stocks and a coordinate decrease in AO and XDH activities in all genotypes tested. The two new lxd alleles affect AO and XDH in a qualitatively but not quantitatively similar fashion to the original lxd allele. AO and XDH activity and AO-CRM levels appear much more sensitive to mutational perturbations of this gene-enzyme than do XDH-CRM levels in the genotypes tested.

  8. Low-temperature synthesis of metal tungstates nanocrystallites in ethylene glycol

    SciTech Connect

    Chen Di; Shen Guozhen; Tang Kaibin; Zheng Huagui; Qian Yitai

    2003-11-26

    In this paper, we report the low-temperature synthesis of metal tungstate, MWO{sub 4} (M=Ca, Sr, Ba, Cd, Zn, Pb) nanocrystallites. By reaction between metal chloride and sodium tungstate in ethylene glycol at 180 deg. C for 10 h, well-crystallized tungstate particles were successfully obtained. Characterization by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) shows that the product powders consist of nanosize particles. Photoluminescence measurement reveals that the as-obtained CaWO{sub 4}, CdWO{sub 4}, and PbWO{sub 4} show excitonic peaks at about 430, 500 and 500 nm, respectively. The solvent and reaction conditions are important in the formation of the products.

  9. Oral tungstate treatment improves only transiently alteration of glucose metabolism in a new rat model of type 2 diabetes.

    PubMed

    Fierabracci, Vanna; De Tata, Vincenzo; Pocai, Alessandro; Novelli, Michela; Barberà, Albert; Masiello, Pellegrino

    2002-11-01

    It has been shown that tungstate is an effective hypoglycemic agent in several animal models of diabetes. In this study, we examined the effectiveness of oral tungstate treatment in a new experimental diabetic syndrome, induced by streptozotocin (STZ) and nicotinamide in adult rats, that shares several features with human type 2 diabetes. Sodium tungstate was administered in the drinking water (2 mg/mL) of control and diabetic rats for 15, 30, 60, and 90 d. Glucose metabolism was explored in vivo by intravenous glucose tolerance test. Insulin secretion and action were assessed in vitro in the isolated perfused pancreas and isolated adipocytes, respectively. Two weeks of tungstate treatment did not modify the moderate hyperglycemia of diabetic rats but reduced their intolerance to glucose, owing to an enhancement of postloading insulin secretion. However, this effect was transient, since it declined after 30 d and vanished after 60 and 90 d of tungstate administration, whereas a trend toward a reduction in basal hyperglycemia was observed on prolonged treatment. Oral tungstate was unable to modify glucose-stimulated insulin secretion in the isolated perfused pancreas, as well as muscle glycogen levels, hepatic glucose metabolism, and insulin-stimulated lipogenesis in isolated adipocytes. Nevertheless, the decreased insulin content of pancreatic islets of diabetic rats was partially restored on prolonged tungstate treatment. In conclusion, in the STZ-nicotinamide model of diabetes, tungstate was unable to permanently correct the alterations in glucose metabolism, despite some indirect evidence of a trophic effect on beta-cells. The ineffectiveness of tungstate could be related to the absence, in this diabetic syndrome, of relevant metabolic alterations in the liver, which thus appear to constitute the major target of tungstate action.

  10. Tungsten speciation and toxicity: acute toxicity of mono- and poly-tungstates to fish.

    PubMed

    Strigul, Nikolay; Koutsospyros, Agamemnon; Christodoulatos, Christos

    2010-02-01

    Tungsten is a widely used transition metal for which very limited information on environmental and toxicological effects is available. Of particular interest is the lack of information linking tungsten speciation and environmental effects. Tungsten anions may polymerize (depending upon concentration, pH, and aquatic geochemistry) in aquatic and soil systems. However, to this date, of all soluble tungstate species only monotungstates have been scrutinized to a fair extent in toxicological studies. The objective of this work is a comparative assessment of the acute toxicity of monotungstates (sodium tungstate, Na(2)WO(4)) and polytungstates (sodium metatungstate, 3Na(2)WO(4).9WO(3)) to Poecilia reticulate. The experiments have been performed according to the OEDC protocols 203 and 204. LD50 values for 1-14 days show that sodium metatungstate is significantly more toxic to fish than sodium tungstate. Based on LD50 (0.86-3.88gL(-1) or 4.67-21.1x10(-3)molNa(2)WO(4)L(-1)), sodium tungstate may be classified as a chemical of low toxicity to fish. Sodium metatungstate caused similar fish mortality to sodium tungstate when it was introduced in 55-80 times lower concentrations (in terms of molL(-1)) than sodium tungstate. LD50 values for sodium metatungstate range from 0.13 to 0.85gWL(-1) or 5.69 to 38.71x10(-5)mol 3Na(2)WO(4).9WO(3)L(-1). Based on these values sodium metatungstate can be classified as a moderate toxic agent to fish.

  11. Neurobehavioral effects of sodium tungstate exposure on rats and their progeny.

    PubMed

    McInturf, Shawn M; Bekkedal, Marni Y-V; Wilfong, Erin; Arfsten, Darryl; Gunasekar, Palur G; Chapman, Gail D

    2008-01-01

    The use of tungsten as a replacement for lead and depleted uranium in munitions began in the mid 1990's. Recent reports demonstrate tungsten solubilizes in soil and can migrate into drinking water supplies and therefore is a potential health risk to humans. This study evaluated the reproductive and neurobehavioral effects of sodium tungstate in Sprague-Dawley rats following 70 days of daily pre- and postnatal exposure. Adult male and female rats were orally dosed with diH(2)O vehicle, 5 or 125 mg/kg/day of sodium tungstate through mating, gestation, and weaning (PND 0-20). Daily administration of sodium tungstate produced no overt evidence of toxicity and had no apparent effect on mating success or offspring physical development. Distress vocalizations were elevated in the highest dose group. There was no treatment related effect on righting reflex latencies, however, the males had significantly shorter latencies than the females. Locomotor activity was affected in both the low and high dose groups of F0 females. Those in the low dose group showed increased distance traveled, more time in ambulatory movements, and less time in stereotypic behavior than controls or high dose animals. The high dose group had more time in stereotypical movements than controls, and less time resting than controls and the lowest exposure group. Maternal retrieval was not affected by sodium tungstate exposure and there were no apparent effects of treatment on F1 acoustic startle response or water maze navigation. Overall, the results of this study suggest pre- and postnatal oral exposure to sodium tungstate may produce subtle neurobehavioral effects in offspring related to motor activity and emotionality. These findings warrant further investigation to characterize the neurotoxicity of sodium tungstate on dams and their developing pups.

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

    SciTech Connect

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

    1982-01-01

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

  13. Hydrothermal synthesis of sodium tungstate nanorods and nanobundles in the presence of sodium sulfate

    SciTech Connect

    Cao Guangxiang; Song Xinyu; Yu Haiyun; Fan Chunhua; Yin Zhilei; Sun Sixiu . E-mail: ssx@sdu.edu.cn

    2006-02-02

    Sodium tungstate nanorods and nanobundles have been successfully prepared, for the first time, through a simple salt-assisted hydrothermal route based on the reaction between Na{sub 2}WO{sub 4} and HCl in aqueous solution. The resultant sodium tungstate nanorods and nanobundles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electronic diffraction (SAED) techniques. The ingredients of the sample have been detected by energy-dispersive spectrum (EDS) method. It is found that hydrothermal temperature and time play important roles in the control of the morphology and size of the products.

  14. Sodium Tungstate for Promoting Mesenchymal Stem Cell Chondrogenesis.

    PubMed

    Khader, Ateka; Sherman, Lauren S; Rameshwar, Pranela; Arinzeh, Treena L

    2016-12-15

    Articular cartilage has a limited ability to heal. Mesenchymal stem cells (MSCs) derived from the bone marrow have shown promise as a cell type for cartilage regeneration strategies. In this study, sodium tungstate (Na2WO4), which is an insulin mimetic, was evaluated for the first time as an inductive factor to enhance human MSC chondrogenesis. MSCs were seeded onto three-dimensional electrospun scaffolds in growth medium (GM), complete chondrogenic induction medium (CCM) containing insulin, and CCM without insulin. Na2WO4 was added to the media leading to final concentrations of 0, 0.01, 0.1, and 1 mM. Chondrogenic differentiation was assessed by biochemical analyses, immunostaining, and gene expression. Cytotoxicity using human peripheral blood mononuclear cells (PBMCS) was also investigated. The chondrogenic differentiation of MSCs was enhanced in the presence of low concentrations of Na2WO4 compared to control, without Na2WO4. In the induction medium containing insulin, cells in 0.01 mM Na2WO4 produced significantly higher sulfated glycosaminoglycans, collagen type II, and chondrogenic gene expression than all other groups at day 28. Cells in 0.1 mM Na2WO4 had significantly higher collagen II production and significantly higher sox-9 and aggrecan gene expression compared to control at day 28. Cells in GM and induction medium without insulin containing low concentrations of Na2WO4 also expressed chondrogenic markers. Na2WO4 did not stimulate PBMC proliferation or apoptosis. The results demonstrate that Na2WO4 enhances chondrogenic differentiation of MSCs, does not have a toxic effect, and may be useful for MSC-based approaches for cartilage repair.

  15. Study of tungstate-protein interaction in human serum by LC-ICP-MS and MALDI-TOF.

    PubMed

    Rodríguez-Fariñas, Nuria; Gomez-Gomez, M Milagros; Camara-Rica, Carmen

    2008-01-01

    Oral administration of sodium tungstate is an effective treatment for type 1 and 2 diabetes in animal models; it does not incur significant side effects, and it may constitute an alternative to insulin. However, the mechanism by which tungstate exerts its observed metabolic effects in vivo is still not completely understood. In this work, serum-containing proteins which bind tungstate have been characterized. Size exclusion chromatography (SEC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) with a Phenomenex Bio-Sep-S 2000 column and 20 mM HEPES and 150 mM NaCl at pH 7.4 as the mobile phase was chosen as the most appropriate methodology to screen for tungsten-protein complexes. When human serum was incubated with tungstate, three analytical peaks were observed, one related to tungstate-albumin binding, one to free tungstate, and one to an unknown protein binding (MW higher than 300 kDa). Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometric analysis of the tungsten-containing fractions collected from SEC-ICP-MS chromatograms, after desalting and preconcentration processes, confirmed the association of tungstate with albumin and the other unknown protein. [figure: see text

  16. Sodium tungstate administration ameliorated diabetes-induced electrical and contractile remodeling of rat heart without normalization of hyperglycemia.

    PubMed

    Aydemir, Mustafa; Ozturk, Nihal; Dogan, Serdar; Aslan, Mutay; Olgar, Yusuf; Ozdemir, Semir

    2012-08-01

    Recently, sodium tungstate was suggested to improve cardiac performance of diabetic rats in perfused hearts based on its insulinomimetic activity. In this study, we aimed to investigate the cellular and molecular mechanisms underlying this beneficial effect of sodium tungstate. Tungstate was administered (100 mg/kg/day) to diabetic and control rats intragastrically for 6 weeks. Blood glucose levels increased, whereas body weight, heart weight and plasma insulin levels decreased significantly in diabetic animals. Interestingly, none of these parameters was changed by tungstate treatment. On the other hand, fractional shortening and accompanying intracellular Ca(2+) [Ca(2+)](i) transients of isolated ventricular myocytes were measured, and sodium tungstate was found to improve the peak shortening and the amplitude of [Ca(2+)](i) transients in diabetic cardiomyocytes. Potassium and L-type Ca(2+) currents were also recorded in isolated ventricular cells. Significant restoration of suppressed I (to) and I (ss) was achieved by tungstate administration. Nevertheless, L-type calcium currents did not change either in untreated or treated diabetic rats. Tissue biochemical parameters including TBARS, protein carbonyl content, xanthine oxidase (XO) and xanthine dehydogenase (XDH) were also determined, and diabetes revealed a marked increase in TBARS and carbonyl content which were decreased significantly by tungstate treatment. Conversely, although XO and XDH activities didn't change in untreated diabetic rats, a remarkable but insignificant decrease was detected in treated animals. In conclusion, tungstate treatment improved diabetes-induced contractile abnormalities via restoration of dysregulated [Ca(2+)](i) and altered ionic currents. This beneficial effect is due to antioxidant property of sodium tungstate rather than normalization of hyperglycemia.

  17. Method of separating and purifying gadolinium-153

    DOEpatents

    Bray, Lane A [Richland, WA; Corneillie, Todd M [Davis, CA

    2001-01-01

    The present invention is an improvement to the method of separating and purifying gadolinium from a mixture of gadolinium and europium having the steps of (a) dissolving the mixture in an acid; (b) reducing europium+3 to europium+2; and (c) precipitating the europium+2 with a sulfate ion in a superstoichiometric amount; wherein the improvement is achieved by using one or more of the following: (i) the acid is an anoic acid; (ii) the reducing is with zinc metal in the absence of a second metal or with an amount of the second metal that is ineffective in the reducing; (iii) adding a group IIA element after step (c) for precipitating the excess sulfate prior to repeating step (c); (iv) the sulfate is a sulfate salt with a monovalent cation; (v) adding cold europium+3 prior to repeating step (c).

  18. Distorted octahedral coordination of tungstate in a subfamily of specific binding proteins.

    PubMed

    Hollenstein, Kaspar; Comellas-Bigler, Mireia; Bevers, Loes E; Feiters, Martin C; Meyer-Klaucke, Wolfram; Hagedoorn, Peter-Leon; Locher, Kaspar P

    2009-06-01

    Bacteria and archaea import molybdenum and tungsten from the environment in the form of the oxyanions molybdate (MoO(4) (2-)) and tungstate (WO(4) (2-)). These substrates are captured by an external, high-affinity binding protein, and delivered to ATP binding cassette transporters, which move them across the cell membrane. We have recently reported a crystal structure of the molybdate/tungstate binding protein ModA/WtpA from Archaeoglobus fulgidus, which revealed an octahedrally coordinated central metal atom. By contrast, the previously determined structures of three bacterial homologs showed tetracoordinate molybdenum and tungsten atoms in their binding pockets. Until then, coordination numbers above four had only been found for molybdenum/tungsten in metalloenzymes where these metal atoms are part of the catalytic cofactors and coordinated by mostly non-oxygen ligands. We now report a high-resolution structure of A. fulgidus ModA/WtpA, as well as crystal structures of four additional homologs, all bound to tungstate. These crystal structures match X-ray absorption spectroscopy measurements from soluble, tungstate-bound protein, and reveal the details of the distorted octahedral coordination. Our results demonstrate that the distorted octahedral geometry is not an exclusive feature of the A. fulgidus protein, and suggest distinct binding modes of the binding proteins from archaea and bacteria.

  19. Preparation of ammonium paratungstate from a sodium tungstate-sodium chloride phase

    SciTech Connect

    Raddatz, A.E.; Gomes, J.M.; Carnahan, T.G.

    1988-01-01

    The objective of this work was to demonstrate that the tungstate-bearing sodium chloride phase can be a suitable feed material for preparing ammonium paratungstate (APT) by a modification to the present industrial solvent extraction process. A combined crossflow-countercurrent flow solvent extraction technique to extract tungsten is presented.

  20. Equilibrium diagrams at 27 [degree]C of the water + sodium tungstate + dodecylamine chloride system

    SciTech Connect

    Dantas Neto, A.A.; Castro Dantas, T.N. de; Duarte, M.M.L.; Avelino, S. . Programa de Pos-Graduacao em Engenharia Quimica)

    1993-01-01

    Amines are usually used in extracting tungsten from scheelite. Dodecylamine chloride in kerosene and octanol was used as an extracting agent in order to establish the phase diagram at 27C for water + sodium tungstate + dodecylamine chloride. Acetone was used to prevent emulsion formation. This procedure made it possible to achieve better partition coefficients; however, there appears to be a saturation region.

  1. Influence of food and diabetes on pharmacokinetics of sodium tungstate in rat.

    PubMed

    Le Lamer-Déchamps, S; Poucheret, P; Cros, G; Bressolle, F

    2002-11-06

    In this paper, the influence of food and diabetes on the pharmacokinetics of sodium tungstate in rat was investigated. The compound was administered intravenously (9 mg/kg) and orally in the form of solution (36 mg/kg). An empirical Bayes methodology was used to compute individual pharmacokinetic parameters. Sodium tungstate followed first-order kinetics, and plasma concentration versus time data were described by a two-compartment model. A significant relationship was found between the bioavailability and the status of the animals. Total plasma clearance and elimination half-life averaged 3.1 ml/min/kg and 1.6 h, respectively. Food had some effects on the extent of sodium tungstate absorption. After oral administration, the bioavailability (0.67 versus 0.85), C(max) (6.10 versus 15.2 microg/ml) and AUC (70.7 versus 105 mgh/l) were 20, 60 and 32% lower in fed than in fasted rats, respectively. The presence of cellulose and sulphate anions in rat chow could partially explain the fed state-associated reduction of tungstate bioavailability. In streptozotocin-induced diabetic fed rats, a 25% decrease occurred in AUC and F, and a 14% increase occurred in the elimination rate constant compared with healthy fed rats. These changes could be explain on the one hand, by the increase of liquid consumption and food intake, and on the other hand, by a gastroparesis in the early diabetic rats.

  2. Direct Hydrothermal Precipitation of Pyrochlore-Type Tungsten Trioxide Hemihydrate from Alkaline Sodium Tungstate Solution

    NASA Astrophysics Data System (ADS)

    Li, Xiaobin; Li, Jianpu; Zhou, Qiusheng; Peng, Zhihong; Liu, Guihua; Qi, Tiangui

    2012-04-01

    Pyrochlore-type tungsten trioxide hemihydrate (WO3·0.5H2O) powder with the average particle size of 0.5 μm was prepared successfully from the weak alkaline sodium tungstate solution by using organic substances of sucrose or cisbutenedioic acid as the acidification agent. The influences of solution pH and acidification agents on the precipitation process were investigated. The results showed that organic acidification agents such as sucrose and cisbutenedioic acid could improve the precipitation of pyrochlore WO3·0.5H2O greatly from sodium tungstate solution compared with the traditional acidification agent of hydrochloric acid. In addition, the pH value of the hydrothermal system played a critical role in the precipitation process of WO3·0.5H2O, and WO3·0.5H2O precipitation mainly occured in the pH range of 7.0 to 8.5. The precipitation rate of tungsten species in the sodium tungstate solution could reach up to 98 pct under the optimized hydrothermal conditions. This article proposed also the hydrothermal precipitation mechanism of WO3·0.5H2O from the weak alkaline sodium tungstate solution. The novel method reported in this study has a great potential to improve the efficiency of advanced tungsten trioxide-based functional material preparation, as well as for the pollution-reducing and energy-saving tungsten extractive metallurgy.

  3. Cycloidal magnetism driven ferroelectricity in double tungstate LiFe (WO4)2

    NASA Astrophysics Data System (ADS)

    Liu, Meifeng; Lin, Lingfang; Zhang, Yang; Li, Shaozhen; Huang, Qingzhen; Garlea, V. Ovidiu; Zou, Tao; Xie, Yunlong; Wang, Yu; Lu, Chengliang; Yang, Lin; Yan, Zhibo; Wang, Xiuzhang; Dong, Shuai; Liu, Jun-Ming

    2017-05-01

    Tungstates A WO4 with the wolframite structure characterized by the A O6 octahedral zigzag chains along the c axis can be magnetic if A =Mn , Fe, Co, Cu, Ni. Among them, MnWO4 is a unique member with a cycloid Mn2 + spin order developed at low temperature, leading to an interesting type-II multiferroic behavior. However, so far no other multiferroic material in the tungstate family has been found. In this work, we present the synthesis and the systematic study of the double tungstate LiFe (WO4)2 . Experimental characterizations including structural, thermodynamic, magnetic, neutron powder diffraction, and pyroelectric measurements unambiguously confirm that LiFe (WO4)2 is the secondly found multiferroic system in the tungstate family. The cycloidal magnetism driven ferroelectricity is also verified by density functional theory calculations. Although here the magnetic couplings between Fe ions are indirect, namely via the so-called super-super-exchanges, the temperatures of magnetic and ferroelectric transitions are surprisingly much higher than those of MnWO4.

  4. Sodium tungstate and vanadyl sulfate effects on blood pressure and vascular prostanoids production in fructose-overloaded rats.

    PubMed

    Peredo, Horatio A; Zabalza, Maria; Mayer, Marcos A; Carranza, Andrea; Puyó, Ana M

    2010-01-01

    This study analyzes the effects of sodium tungstate and vanadyl sulphate in the fructose-overloaded rat, a model of metabolic syndrome. Fructose (9 weeks) increased blood pressure, triglycerydemia, glycemia, and reduced release of vasodilator prostaglandins (prostacyclin and prostaglandin E2 ) in the mesenteric vascular bed. Sodium tungstate prevented those alterations; meanwhile vanadyl sulfate only prevented the increase in glycemia. In conclusion, the present experiments showed that sodium tungstate is more effective than vanadyl sulfate for the treatment of experimental metabolic syndrome in rats.

  5. Role of sodium tungstate as a potential antiplatelet agent.

    PubMed

    Fernández-Ruiz, Rebeca; Pino, Marc; Hurtado, Begoña; García de Frutos, Pablo; Caballo, Carolina; Escolar, Ginés; Gomis, Ramón; Diaz-Ricart, Maribel

    2015-01-01

    Platelet inhibition is a key strategy in the management of atherothrombosis. However, the large variability in response to current strategies leads to the search for alternative inhibitors. The antiplatelet effect of the inorganic salt sodium tungstate (Na2O4W), a protein tyrosine phosphatase 1B (PTP1B) inhibitor, has been investigated in this study. Wild-type (WT) and PTP1B knockout (PTP1B(-/-)) mice were treated for 1 week with Na2O4W to study platelet function with the platelet function analyzer PFA-100, a cone-and-plate analyzer, a flat perfusion chamber, and thrombus formation in vivo. Human blood aliquots were incubated with Na2O4W for 1 hour to measure platelet function using the PFA-100 and the annular perfusion chamber. Aggregometry and thromboelastometry were also performed. In WT mice, Na2O4W treatment prolonged closure times in the PFA-100 and decreased the surface covered (%SC) by platelets on collagen. Thrombi formed in a thrombosis mice model were smaller in animals treated with Na2O4W (4.6±0.7 mg vs 8.9±0.7 mg; P<0.001). Results with Na2O4W were similar to those in untreated PTP1B(-)/(-) mice (5.0±0.3 mg). Treatment of the PTP1B(-)/(-) mice with Na2O4W modified only slightly this response. In human blood, a dose-dependent effect was observed. At 200 μM, closure times in the PFA-100 were prolonged. On denuded vessels, %SC and thrombi formation (%T) decreased with Na2O4W. Neither the aggregating response nor the viscoelastic clot properties were affected. Na2O4W decreases consistently the hemostatic capacity of platelets, inhibiting their adhesive and cohesive properties under flow conditions in mice and in human blood, resulting in smaller thrombi. Although Na2O4W may be acting on platelet PTP1B, other potential targets should not be disregarded.

  6. Role of sodium tungstate as a potential antiplatelet agent

    PubMed Central

    Fernández-Ruiz, Rebeca; Pino, Marc; Hurtado, Begoña; García de Frutos, Pablo; Caballo, Carolina; Escolar, Ginés; Gomis, Ramón; Diaz-Ricart, Maribel

    2015-01-01

    Purpose Platelet inhibition is a key strategy in the management of atherothrombosis. However, the large variability in response to current strategies leads to the search for alternative inhibitors. The antiplatelet effect of the inorganic salt sodium tungstate (Na2O4W), a protein tyrosine phosphatase 1B (PTP1B) inhibitor, has been investigated in this study. Methods Wild-type (WT) and PTP1B knockout (PTP1B−/−) mice were treated for 1 week with Na2O4W to study platelet function with the platelet function analyzer PFA-100, a cone-and-plate analyzer, a flat perfusion chamber, and thrombus formation in vivo. Human blood aliquots were incubated with Na2O4W for 1 hour to measure platelet function using the PFA-100 and the annular perfusion chamber. Aggregometry and thromboelastometry were also performed. Results In WT mice, Na2O4W treatment prolonged closure times in the PFA-100 and decreased the surface covered (%SC) by platelets on collagen. Thrombi formed in a thrombosis mice model were smaller in animals treated with Na2O4W (4.6±0.7 mg vs 8.9±0.7 mg; P<0.001). Results with Na2O4W were similar to those in untreated PTP1B−/− mice (5.0±0.3 mg). Treatment of the PTP1B−/− mice with Na2O4W modified only slightly this response. In human blood, a dose-dependent effect was observed. At 200 μM, closure times in the PFA-100 were prolonged. On denuded vessels, %SC and thrombi formation (%T) decreased with Na2O4W. Neither the aggregating response nor the viscoelastic clot properties were affected. Conclusion Na2O4W decreases consistently the hemostatic capacity of platelets, inhibiting their adhesive and cohesive properties under flow conditions in mice and in human blood, resulting in smaller thrombi. Although Na2O4W may be acting on platelet PTP1B, other potential targets should not be disregarded. PMID:26060394

  7. New Family of Tungstate-Responsive Transcriptional Regulators in Sulfate-Reducing Bacteria

    PubMed Central

    Rajeev, Lara; Luning, Eric G.; Zane, Grant M.; Siddartha, Kavya; Rodionov, Dmitry A.; Dubchak, Inna; Arkin, Adam P.; Wall, Judy D.; Mukhopadhyay, Aindrila

    2013-01-01

    The trace elements molybdenum and tungsten are essential components of cofactors of many metalloenzymes. However, in sulfate-reducing bacteria, high concentrations of molybdate and tungstate oxyanions inhibit growth, thus requiring the tight regulation of their homeostasis. By a combination of bioinformatic and experimental techniques, we identified a novel regulator family, tungstate-responsive regulator (TunR), controlling the homeostasis of tungstate and molybdate in sulfate-reducing deltaproteobacteria. The effector-sensing domains of these regulators are similar to those of the known molybdate-responsive regulator ModE, while their DNA-binding domains are homologous to XerC/XerD site-specific recombinases. Using a comparative genomics approach, we identified DNA motifs and reconstructed regulons for 40 TunR family members. Positional analysis of TunR sites and putative promoters allowed us to classify most TunR proteins into two groups: (i) activators of modABC genes encoding a high-affinity molybdenum and tungsten transporting system and (ii) repressors of genes for toluene sulfonate uptake (TSUP) family transporters. The activation of modA and modBC genes by TunR in Desulfovibrio vulgaris Hildenborough was confirmed in vivo, and we discovered that the activation was diminished in the presence of tungstate. A predicted 30-bp TunR-binding motif was confirmed by in vitro binding assays. A novel TunR family of bacterial transcriptional factors controls tungstate and molybdate homeostasis in sulfate-reducing deltaproteobacteria. We proposed that TunR proteins participate in protection of the cells from the inhibition by these oxyanions. To our knowledge, this is a unique case of a family of bacterial transcriptional factors evolved from site-specific recombinases. PMID:23913324

  8. Tungstate Uptake by a highly specific ABC transporter in Eubacterium acidaminophilum.

    PubMed

    Makdessi, K; Andreesen, J R; Pich, A

    2001-07-06

    The Gram-positive anaerobe Eubacterium acidaminophilum contains at least two tungsten-dependent enzymes: viologen-dependent formate dehydrogenase and aldehyde dehydrogenase. (185)W-Labeled tungstate was taken up by this organism with a maximum rate of 0.53 pmol min(-)1 mg(-)1 of protein at 36 degrees C. The uptake was not affected by equimolar amounts of molybdate. The genes tupABC coding for an ABC transporter specific for tungstate were cloned in the downstream region of genes encoding a tungsten-containing formate dehydrogenase. The substrate-binding protein, TupA, of this putative transporter was overexpressed in Escherichia coli, and its binding properties toward oxyanions were determined by a native polyacrylamide gel retardation assay. Only tungstate induced a shift of TupA mobility, suggesting that only this anion was specifically bound by TupA. If molybdate and sulfate were added in high molar excess (>1000-fold), they were also slightly bound by TupA. The K(d) value for tungstate was determined to be 0.5 microm. The genes encoding the tungstate-specific ABC transporter exhibited highest similarities to putative transporters from Methanobacterium thermoautotrophicum, Haloferax volcanii, Vibrio cholerae, and Campylobacter jejuni. These five transporters represent a separate phylogenetic group of oxyanion ABC transporters as evident from analysis of the deduced amino acid sequences of the binding proteins. Downstream of the tupABC genes, the genes moeA, moeA-1, moaA, and a truncated moaC have been identified by sequence comparison of the deduced amino acid sequences. They should participate in the biosynthesis of the pterin cofactor that is present in molybdenum- and tungsten-containing enzymes except nitrogenase.

  9. New family of tungstate-responsive transcriptional regulators in sulfate-reducing bacteria.

    PubMed

    Kazakov, Alexey E; Rajeev, Lara; Luning, Eric G; Zane, Grant M; Siddartha, Kavya; Rodionov, Dmitry A; Dubchak, Inna; Arkin, Adam P; Wall, Judy D; Mukhopadhyay, Aindrila; Novichkov, Pavel S

    2013-10-01

    The trace elements molybdenum and tungsten are essential components of cofactors of many metalloenzymes. However, in sulfate-reducing bacteria, high concentrations of molybdate and tungstate oxyanions inhibit growth, thus requiring the tight regulation of their homeostasis. By a combination of bioinformatic and experimental techniques, we identified a novel regulator family, tungstate-responsive regulator (TunR), controlling the homeostasis of tungstate and molybdate in sulfate-reducing deltaproteobacteria. The effector-sensing domains of these regulators are similar to those of the known molybdate-responsive regulator ModE, while their DNA-binding domains are homologous to XerC/XerD site-specific recombinases. Using a comparative genomics approach, we identified DNA motifs and reconstructed regulons for 40 TunR family members. Positional analysis of TunR sites and putative promoters allowed us to classify most TunR proteins into two groups: (i) activators of modABC genes encoding a high-affinity molybdenum and tungsten transporting system and (ii) repressors of genes for toluene sulfonate uptake (TSUP) family transporters. The activation of modA and modBC genes by TunR in Desulfovibrio vulgaris Hildenborough was confirmed in vivo, and we discovered that the activation was diminished in the presence of tungstate. A predicted 30-bp TunR-binding motif was confirmed by in vitro binding assays. A novel TunR family of bacterial transcriptional factors controls tungstate and molybdate homeostasis in sulfate-reducing deltaproteobacteria. We proposed that TunR proteins participate in protection of the cells from the inhibition by these oxyanions. To our knowledge, this is a unique case of a family of bacterial transcriptional factors evolved from site-specific recombinases.

  10. Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Ratova, Marina; Kelly, Peter J.; West, Glen T.; Tosheva, Lubomira; Edge, Michele

    2017-01-01

    Titanium dioxide - bismuth tungstate composite materials were prepared by pulsed DC reactive magnetron sputtering of bismuth and tungsten metallic targets in argon/oxygen atmosphere onto anatase and rutile titania nanoparticles. The use of an oscillating bowl placed beneath the two magnetrons arranged in a co-planar closed field configuration enabled the deposition of bismuth tungstate onto loose powders, rather than a solid substrate. The atomic ratio of the bismuth/tungsten coatings was controlled by varying the power applied to each target. The effect of the bismuth tungstate coatings on the phase, optical and photocatalytic properties of titania was investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area measurements, transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy and an acetone degradation test. The latter involved measurements of the rate of CO2 evolution under visible light irradiation of the photocatalysts, which indicated that the deposition of bismuth tungstate resulted in a significant enhancement of visible light activity, for both anatase and rutile titania particles. The best results were achieved for coatings with a bismuth to tungsten atomic ratio of 2:1. In addition, the mechanism by which the photocatalytic activity of the TiO2 nanoparticles was enhanced by compounding it with bismuth tungstate was studied by microwave cavity perturbation. The results of these tests confirmed that such enhancement of the photocatalytic properties is due to more efficient photogenerated charge carrier separation, as well as to the contribution of the intrinsic photocatalytic properties of Bi2WO6.

  11. Tungsten transport protein A (WtpA) in Pyrococcus furiosus: the first member of a new class of tungstate and molybdate transporters.

    PubMed

    Bevers, Loes E; Hagedoorn, Peter-Leon; Krijger, Gerard C; Hagen, Wilfred R

    2006-09-01

    A novel tungstate and molybdate binding protein has been discovered from the hyperthermophilic archaeon Pyrococcus furiosus. This tungstate transport protein A (WtpA) is part of a new ABC transporter system selective for tungstate and molybdate. WtpA has very low sequence similarity with the earlier-characterized transport proteins ModA for molybdate and TupA for tungstate. Its structural gene is present in the genome of numerous archaea and some bacteria. The identification of this new tungstate and molybdate binding protein clarifies the mechanism of tungstate and molybdate transport in organisms that lack the known uptake systems associated with the ModA and TupA proteins, like many archaea. The periplasmic protein of this ABC transporter, WtpA (PF0080), was cloned and expressed in Escherichia coli. Using isothermal titration calorimetry, WtpA was observed to bind tungstate (dissociation constant [K(D)] of 17 +/- 7 pM) and molybdate (K(D) of 11 +/- 5 nM) with a stoichiometry of 1.0 mol oxoanion per mole of protein. These low K(D) values indicate that WtpA has a higher affinity for tungstate than do ModA and TupA and an affinity for molybdate similar to that of ModA. A displacement titration of molybdate-saturated WtpA with tungstate showed that the tungstate effectively replaced the molybdate in the binding site of the protein.

  12. Time- and energy-efficient solution combustion synthesis of binary metal tungstate nanoparticles with enhanced photocatalytic activity.

    PubMed

    Thomas, Abegayl; Janáky, Csaba; Samu, Gergely F; Huda, Muhammad N; Sarker, Pranab; Liu, J Ping; van Nguyen, Vuong; Wang, Evelyn H; Schug, Kevin A; Rajeshwar, Krishnan

    2015-05-22

    In the search for stable and efficient photocatalysts beyond TiO2 , the tungsten-based oxide semiconductors silver tungstate (Ag2 WO4 ), copper tungstate (CuWO4 ), and zinc tungstate (ZnWO4 ) were prepared using solution combustion synthesis (SCS). The tungsten precursor's influence on the product was of particular relevance to this study, and the most significant effects are highlighted. Each sample's photocatalytic activity towards methyl orange degradation was studied and benchmarked against their respective commercial oxide sample obtained by solid-state ceramic synthesis. Based on the results herein, we conclude that SCS is a time- and energy-efficient method to synthesize crystalline binary tungstate nanomaterials even without additional excessive heat treatment. As many of these photocatalysts possess excellent photocatalytic activity, the discussed synthetic strategy may open sustainable materials chemistry avenues to solar energy conversion and environmental remediation.

  13. Cost and availability of gadolinium for nuclear fuel reprocessing plants

    SciTech Connect

    Klepper, O.H.

    1985-06-01

    Gadolinium is currently planned for use as a soluble neutron poison in nuclear fuel reprocessing plants to prevent criticality of solutions of spent fuel. Gadolinium is relatively rare and expensive. The present study was undertaken therefore to estimate whether this material is likely to be available in quantities sufficient for fuel reprocessing and at reasonable prices. It was found that gadolinium, one of 16 rare earth elements, appears in the marketplace as a by-product and that its present supply is a function of the production rate of other more prevalent rare earths. The potential demand for gadolinium in a fuel reprocessing facility serving a future fast reactor industry amounts to only a small fraction of the supply. At the present rate of consumption, domestic supplies of rare earths containing gadolinium are adequate to meet national needs (including fuel reprocessing) for over 100 years. With access to foreign sources, US demands can be met well beyond the 21st century. It is concluded therefore that the supply of gadolinium will quite likely be more than adequate for reprocessing spent fuel for the early generation of fast reactors. The current price of 99.99% pure gadolinium oxide lies in the range $50/lb to $65/lb (1984 dollars). By the year 2020, in time for reprocessing spent fuel from an early generation of large fast reactors, the corresponding values are expected to lie in the $60/lb to $75/lb (1984 dollars) price range. This increase is modest and its economic impact on nuclear fuel reprocessing would be minor. The economic potential for recovering gadolinium from the wastes of nuclear fuel reprocessing plants (which use gadolinium neutron poison) was also investigated. The cost of recycled gadolinium was estimated at over twelve times the cost of fresh gadolinium, and thus recycle using current recovery technology is not economical. 15 refs., 4 figs., 11 tabs.

  14. Resonance parameter measurements and analysis of gadolinium

    SciTech Connect

    Leinweber, G.; Barry, D. P.; Trbovich, M. J.; Burke, J. A.; Drindak, N. J.; Knox, H. D.; Ballad, R. V.; Block, R. C.; Danon, Y.; Severnyak, L. I.

    2006-07-01

    The purpose of the present work is to measure the neutron cross sections of gadolinium accurately. Gd has the highest thermal absorption cross section of any natural element. Therefore it is an important element for thermal reactor applications Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Inst. (RPI) LINAC facility using metallic and liquid Gd samples. The liquid samples were isotopically-enriched in either {sup 155}Gd or {sup 157}Gd. The capture measurements were made at the 25-m flight station with a sodium iodide detector, and the transmission measurements were performed at 15- and 25-m flight stations with {sup 6}Li glass scintillation detectors. The multilevel R-matrix Bayesian code SAMMY was used to extract resonance parameters. The results of the thermal region analysis are significant. Resonance parameters for the low energy doublet, at 0.025 and 0.032 eV, are presented. The thermal (2200 m/s) capture cross section of {sup 157}Gd has been measured to be 11% smaller than that calculated from ENDF/B-VI updated through release 8. Thermal capture cross sections and capture resonance integrals for each isotope as well as elemental gadolinium are presented. In the epithermal region, natural metal samples were measured in capture and transmission. Neutron interaction data up to 300 eV have been analyzed. Substantial improvement to the understanding of gadolinium cross sections is presented, particularly above 180 eV where the ENDF resolved region for {sup 155}Gd ends. (authors)

  15. Extraction-chromatographic affinage in gadolinium-153 preparation production technology

    SciTech Connect

    Melnik, M.I.; Karelin, E.A.; Kuznetsov, R.A.

    1993-12-31

    The gadolinium 153 preparation is used for production of medical gamma-sources which are applicable in bone densimeters for early diagnostics of osteoporosis. This preparation must meet strict requirements with respect to the content of europium radionuclides and specific activity. In The Research Institute of Atomic Reactors (RIAR) the gadolinium 153 is produced by neutron irradiation of Europium 151. This process is described.

  16. Substitution of gadolinium ethylenediaminetetraacetate with phosphites: towards gadolinium deposit in nephrogenic systemic fibrosis.

    PubMed

    Gao, Song; Chen, Mao-Long; Zhou, Zhao-Hui

    2014-01-14

    In neutral media, reactions of gadolinium ethylenediaminetetraacetates with phosphorous acid result in the formation of the mixed-ligand polymeric complex K3n[Gd(EDTA)(HPO3)]n·7nH2O () and dimeric complex Na6[Gd2(EDTA)2(HPO3)2]·2.5NaCl·21H2O () (H4EDTA = ethylenediaminetetraacetic acid) in warm solution. Further substitution with citric acid gives the monomeric gadolinium citrate with EDTA (NH4)2Na[Gd(EDTA)(H2cit)]·4H2O (). The compounds were characterized by elemental analysis, single crystal X-ray diffraction, FT-IR, ESI-MS and thermogravimetric analysis. Structural analysis indicates that three coordinated water molecules in the gadolinium ethylenediaminetetraacetate trihydrates are replaced by phosphite ions (HPO3(2-)) in the compounds and . Gadolinium atoms are octa-coordinated by EDTA and the phosphite ion, the latter links adjacent Gd-EDTA units to generate an infinite one-dimensional chain in compound and a dimeric octatomic ring in . In complex , coordinated water molecules were substituted by the α-hydroxy, α-carboxy and β-carboxy groups of citrate. Citrate is favourable for inhibiting the formation of Gd-EDTA phosphite. All the complexes are very easily soluble in water. The solution behavior of the isostructural lanthanum complexes was probed with (13)C and (31)P NMR spectra in D2O for comparison. ESI-MS analysis and recrystallization proved that complexes and dissociate to the monomeric unit of Gd-EDTA and free HPO3(2-) in aqueous solution. Substitutions of gadolinium ethylenediaminetetraacetates to and are attributed to be the cause of nephrogenic systemic fibrosis in some way.

  17. Towards modeling gadolinium-lead-borate glasses

    SciTech Connect

    Rada, S.; Ristoiu, T.; Rada, M.; Coroiu, I.; Maties, V.; Culea, E.

    2010-01-15

    Infrared spectra of gadolinium-lead-borate glasses of the xGd{sub 2}O{sub 3}.(100 - x)[3B{sub 2}O{sub 3}.PbO] system, where x = 0, 5, 10, 15, 25, 35 and 50 mol.%, have been recorded to explore the role of content of gadolinium ions behaving as glass modifier. The FTIR spectroscopy data for the xGd{sub 2}O{sub 3}.(1 - x)[3B{sub 2}O{sub 3}.PbO] glasses show the structural role of lead ions as a network-formers and of the gadolinium ions network modifiers. Adding of the rare earth ion up to 35 mol.% into the glass matrix, the IR bands characteristic to the studied glasses become sharper and more pronounced. Structural changes, as recognized by analyzing band shapes of IR spectra, revealed that Gd{sub 2}O{sub 3} causes a change from the continuous borate network to the continuous lead-borate network interconnected through Pb-O-B and B-O-B bridges and the transformation of some tetrahedral [BO{sub 4}] units into trigonal [BO{sub 3}] units. Then, gadolinium ions have affinity towards [BO{sub 3}] structural units which contain non-bridging oxygens necessary for the charge compensation because the more electronegative [BO{sub 3}] structural units were implied in the formation of B-O-Gd bonds and the transformation of glass network into a glass ceramic. We propose a possible structural model of building blocks for the formation of continuous random 3B{sub 2}O{sub 3}.PbO network glass used by density functional theory (DFT) calculations. DFT calculations show that lead atoms occupy three different sites in the proposed model. The first is coordinated with six oxygen atoms forming distorted octahedral geometries. The second lead atom has an octahedral oxygen environment and the five longer Pb-O bonds are considered as participating in the metal coordination scheme. The third lead atom has ionic character. In agreement with the results offered by the experimental FTIR data, the theoretical IR data confirm that our proposed structure is highly possible.

  18. Light deflection in gadolinium molybdate ferroelastic crystals

    NASA Astrophysics Data System (ADS)

    Staniorowski, Piotr; Bornarel, Jean

    2000-02-01

    The deflection of a He-Ne light beam by polydomain gadolinium molybdate (GMO) crystals has been studied with respect to incidence angle icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> i on the sample at room temperature. The A and B deflected beams do not cross each other during the icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> i variation, in contrast to results and calculations previously published. The model using the Fresnel equation confirms this result. The model presented is more accurate for numerical calculation than that using the Huygens construction.

  19. Neutron Detection with Lithium Gadolinium Borate

    SciTech Connect

    J. Bart Czirr

    2000-11-12

    With the advent of a highly efficient, neutron-sensitive inorganic crystal scintillator, a new class of neutron spectrometers and dosimeters becomes feasible. The new material, lithium gadolinium borate, incorporates the three primary neutron-capturing nuclei utilized in solid-state neutron detectors. Eight isotopic permutations of the three capturing elements permit a wide range of applications throughout the neutron energy range from thermal to several MeV. The transparent inorganic crystals may be incorporated in organic plastic matrices to enhance the detection efficiency for neutrons of all energies. This summary describes a number of applications of the new scintillator in several areas of neutron detection.

  20. The Phase Transitions in Double Tungstate in Extremely Low-Dimensional and Low-Symmetry Compounds with Cooperative Jahn-Teller Effect

    DTIC Science & Technology

    2001-01-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO 11897 TITLE: The Phase Transitions in Double Tungstate in Extremely...report: ADP011865 thru ADP011937 UNCLASSIFIED Invited Paper The phase transitions in double tungstate - in extremely low-dimensional and low-symmetry...Warsaw, Poland ABSTRACT The rare earth double tungstates are of special interest because of manifestation of cooperative Jahn-Teller effect (CJTE) for low

  1. Kinetics of a first-order crystalline-amorphous transformation in zirconium tungstate

    NASA Astrophysics Data System (ADS)

    Yan, Xiaozhi; Ren, Xiangting; Sun, Guangai; Li, Dong; Li, Xin; He, Duanwei; Yang, Wenge

    2017-06-01

    A combination of in situ volumetric measurements, Raman spectroscopy, x-ray diffraction, differential thermal analysis, and transmission electron microscopy was used to investigate the crystalline-amorphous transformation of zirconium tungstate at high pressure and room temperature. Zirconium tungstate transformed at about 1.2 GPa to an amorphous phase which was recoverable to ambient conditions. The volume contraction and temperature increase in the sample during pressure-induced amorphization indicate that it was a first-order phase transition. The kinetics data are consistent with a model where an amorphous phase occurs by the formation of nuclei without noticeable growth. However, our results conflict with the three-dimensional interface-controlled growth of a new phase in conventional solid-state polymorphic changes.

  2. Distribution of tungstate in pregnant mice and effects on embryonic cells in vitro.

    PubMed

    Wide, M; Danielsson, B R; Dencker, L

    1986-08-01

    Whole-body autoradiography and impulse counting experiments were used to study the distribution and retention of radioactivity in the pregnant mouse after administration of [185W]tungstate. A rapid uptake was found in a number of tissues--skeleton, red pulp of the spleen, adrenal, liver, thyroid, pituitary, and ovary--and in the intestine and kidneys, through which it was rapidly excreted. 185W was also readily transported from mother to fetus, although more in late than in early gestation. The largest metal retention was found in the maternal skeleton, kidneys, and spleen and in the visceral yolk sac epithelium and the skeleton of the fetus. Furthermore, in vitro cytotoxicity experiments showed inhibition by tungstate of cartilage production in limb bud mesenchymal cultures at concentrations similar to those found in vivo.

  3. Influence of chromate, molybdate and tungstate on pit formation in chloride medium

    NASA Astrophysics Data System (ADS)

    Silva, J. W. J.; Codaro, E. N.; Nakazato, R. Z.; Hein, L. R. O.

    2005-11-01

    It has been characterized and evaluated the 2024-T351 and 7050-T7451 aluminum alloys pitting corrosion in naturally aerated chloride aqueous solutions containing chromate, molybdate and tungstate. It has been carried out electrochemical and non-electrochemical immersion corrosion tests accompanied by surface metallography analysis using an optical microscopy. Chromate for the two alloys and in molybdate for 7050 has corrosion inhibiting effects, whereas tungstate promotes the pitting corrosion for these alloys. Quantitative surface analysis upon the alloys after immersion has indicated that pits are predominantly conical or quasi-conical and irregular. In general, pits have been wider than deep and the widest have been also the deepest. Despite inhibitor presence, when pits have been nucleated, they grow with the same intensity.

  4. Oral tungstate (Na2WO4) exposure reduces adaptive immune responses in mice after challenge.

    PubMed

    Osterburg, Andrew R; Robinson, Chad T; Mokashi, Vishwesh; Stockelman, Michael; Schwemberger, Sandy J; Chapman, Gail; Babcock, George F

    2014-01-01

    Tungstate (WO²⁻₄) has been identified as a ground water contaminant at military firing ranges and can be absorbed by ingestion. In this study, C57BL6 mice were exposed to sodium tungstate (Na2WO4·2H2O) (0, 2, 62.5, 125, and 200 mg/kg/day) in their drinking water for an initial 28-day screen and in a one-generation (one-gen) model. Twenty-four hours prior to euthanasia, mice were intraperitoneally injected with Staphylococcal enterotoxin B (SEB) (20 μg/mouse) or saline as controls. After euthanasia, splenocytes and blood were collected and stained with lymphocyte and/or myeloid immunophenotyping panels and analyzed by flow cytometry. In the 28-day and one-gen exposure, statistically significant reductions were observed in the quantities of activated cytotoxic T-cells (TCTL; CD3(+)CD8(+)CD71(+)) and helper T-cells (TH; CD3(+)CD4(+)CD71(+)) from spleens of SEB-treated mice. In the 28-day exposures, CD71(+) TCTL cells were 12.87 ± 2.05% (SE) in the 0 tungstate (control) group compared to 4.44 ± 1.42% in the 200 mg/kg/day (p < 0.001) group. TH cells were 4.85 ± 1.23% in controls and 2.76 ± 0.51% in the 200 mg/kg/day (p < 0.003) group. In the one-gen exposures, TCTL cells were 7.98 ± 0.49% and 6.33 ± 0.49% for P and F1 mice after 0 mg/kg/day tungstate vs 1.58 ± 0.23% and 2.52 ± 0.25% after 200 mg/kg/day of tungstate (p < 0.001). Similarly, TH cells were reduced to 6.21 ± 0.39% and 7.20 ± 0.76%, respectively, for the 0 mg/kg/day P and F1 mice, and 2.28 ± 0.41% and 2.85 ± 0.53%, respectively, for the 200 mg/kg/day tungstate P and F1 groups (p < 0.001). In delayed-type hypersensitivity Type IV experiments, tungstate exposure prior to primary and secondary antigen challenge significantly reduced footpad swelling at 20 and 200 mg/kg/day. These data indicate that exposure to tungstate can result in immune suppression that may, in turn, reduce host defense against

  5. Optical Properties of Potassium Erbium Double Tungstate KEr(WO4)2

    DTIC Science & Technology

    2001-01-01

    possible application of rare earth double tungstates is using them as cooling agents in an adiabatic demagnetization method for obtaining very low...means of the Czochralski technique despite their congruent melting. To lower the temperature of crystallisation below the temperature of the phase...of flat surface. The orientation of plates was established by the X-ray diffraction method . Optical spectra were determined in two different cryogenic

  6. A photon calorimeter using lead tungstate crystals for the CEBAF HAll A Compton polarimeter

    SciTech Connect

    D. Neyret; T. Pussieux; T. Auger; M. Baylac; E. Burtin; C. Cavata; R. Chipaux; S. Escoffier; N. Falletto; J. Jardillier; S. Kerhoas; D. Lhuillier; F. Marie; C. Veyssiere; J. Ahrens; R. Beck; M. Lang

    2000-05-01

    A new Compton polarimeter is built on the CEBAF Hall A electron beam line. Performances of 10% resolution and 1% calibration are required for the photon calorimeter of this polarimeter. This calorimeter is built with lead tungstate scintillators coming from the CMS electromagnetic calorimeter R&D. Beam tests of this detector have been made using the tagged photon beam line at MAMI, Mainz, and a resolution of 1.76%+2.75%/v+0.41%/E has been measured.

  7. Electrodeposition of single-crystalline molybdenum layers from tungstate-molybdate melts

    SciTech Connect

    Esina, N.O.; Tarasova, K.P.; Baraboshkin, A.N.

    1987-07-01

    The structure and growth rates of single-crystalline molybdenum layers produced by electrolysis of tungstate-molybdate melts on single-crystalline substrates with the orientations (110), (112), (100), and (111) were investigated. Growth pyramids having a symmetry coincident with that of the substrate plane were revealed as the characteristic feature of surface structure of these layers. The change from single- to polycrystalline molybdenum structure occurs via the development of twinning defects.

  8. An electric sensor based on the electrogyration effect in a lead tungstate crystal

    NASA Astrophysics Data System (ADS)

    Novikov, M. A.; Stepanov, A. A.; Khyshov, A. A.

    2017-04-01

    We present original results of an investigation of the specific features of optical electrochirality (electrogyration) in a lead tungstate crystal. Since this crystal exhibits neither the Pockels effect nor the inverse piezoelectric effect, the electrogyration effect can be used to create a fast-response electric sensor for remote monitoring of high-speed processes in high-voltage electric networks. A fiber-optic sensor prototype has been manufactured using optical elements intended for fiber communications.

  9. Specific adsorption of tungstate by cell surface display of the newly designed ModE mutant.

    PubMed

    Kuroda, Kouichi; Nishitani, Takashi; Ueda, Mitsuyoshi

    2012-10-01

    By cell surface display of ModE protein that is a transcriptional regulator of operons involved in the molybdenum metabolism in Escherichia coli, we have constructed a molybdate-binding yeast (Nishitani et al., Appl Microbiol Biotechnol 86:641-648, 2010). In this study, the binding specificity of the molybdate-binding domain of the ModE protein displayed on yeast cell surface was improved by substituting the amino acids involved in oxyanion binding with other amino acids. Although the displayed S126T, R128E, and T163S mutant proteins adsorbed neither molybdate nor tungstate, the displayed ModE mutant protein (T163Y) abolished only molybdate adsorption, exhibiting the specific adsorption of tungstate. The specificity of the displayed ModE mutant protein (T163Y) for tungstate was increased by approximately 9.31-fold compared to the displayed wild-type ModE protein at pH 5.4. Therefore, the strategy of protein design and its cell surface display is effective for the molecular breeding of bioadsorbents with metal-specific adsorption ability based on a single species of microorganism without isolation from nature.

  10. THE EFFECT OF TUNGSTATE NANOPARTICLES ON REACTIVE OXYGEN SPECIES AND CYTOTOXICITY IN RAW 264.7 MOUSE MONOCYTE MACROPHAGE CELLS

    PubMed Central

    Dunnick, Katherine M.; Badding, Melissa A.; Schwegler-Berry, Diane; Patete, Jonathan M.; Koenigsmann, Christopher; Wong, Stanislaus S.; Leonard, Stephen S.

    2015-01-01

    Due to their unique size, surface area, and chemical characteristics, nanoparticles’ use in consumer products has increased. However, the toxicity of nanoparticle (NP) exposure during the manufacturing process has not been fully assessed. Tungstate NP are used in numerous products, including but not limited to scintillator detectors and fluorescent lighting. As with many NP, no apparent toxicity studies have been completed with tungstate NP. The hypothesis that tungstate NP in vitro exposure results in reactive oxygen species (ROS) formation and cytotoxicity was examined. Differences in toxicity based on tungstate NP size, shape (sphere vs. wire), and chemical characteristics were determined. RAW 264.7 mouse monocyte macrophages were exposed to tungstate NP, and ROS formation was assessed via electron spin resonance (ESR), and several assays including hydrogen peroxide, intracellular ROS, and Comet. Results showed ROS production induced by tungstate nanowire exposure, but this exposure did not result in oxidative DNA damage. Nanospheres showed neither ROS nor DNA damage following cellular exposure. Cells were exposed over 72 h to assess cytotoxicity using an MTT (tetrazolium compound) assay. Results showed that differences in cell death between wires and spheres occurred at 24 h but were minimal at both 48 and 72 h. The present results indicate that tungstate nanowires are more reactive and produce cell death within 24 h of exposure, whereas nanospheres are less reactive and did not produce cell death. Results suggest that differences in shape may affect reactivity. However, regardless of the differences in reactivity, in general both shapes produced mild ROS and resulted in minimal cell death at 48 and 72 h in RAW 264.7 cells. PMID:25208664

  11. Alkali metal and alkali earth metal gadolinium halide scintillators

    DOEpatents

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

    2016-08-02

    The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  12. Comparison of gadolinium depletion in CASMO-4 and CASMO-3

    SciTech Connect

    Knott, D.; Edenius, M.

    1995-12-31

    Since the mid-1980s, CASMO-3 has been used to generate two-group nodal data for SIMULATE-3. Development of CASMO-3 was based on the accuracy needed to analyze {approximately} 12-month cycle lengths. Fuel designs for these annual cycles contained low gadolinium loadings in only a few pins. As cycle lengths increased from 12 to 24 months, gadolinium loadings doubled and tripled, as did the number of pins containing gadolinium. The use of heavy burnable absorber loadings has been a driving force behind the development of CASMO-4.

  13. Removal of gadolinium nitrate from heavy water

    SciTech Connect

    Wilde, E.W.

    2000-03-22

    Work was conducted to develop a cost-effective process to purify 181 55-gallon drums containing spent heavy water moderator (D2O) contaminated with high concentrations of gadolinium nitrate, a chemical used as a neutron poison during former nuclear reactor operations at the Savannah River Site (SRS). These drums also contain low level radioactive contamination, including tritium, which complicates treatment options. Presently, the drums of degraded moderator are being stored on site. It was suggested that a process utilizing biological mechanisms could potentially lower the total cost of heavy water purification by allowing the use of smaller equipment with less product loss and a reduction in the quantity of secondary waste materials produced by the current baseline process (ion exchange).

  14. A quantitative study of sodium tungstate protective effect on pancreatic beta cells in streptozotocin-induced diabetic rats.

    PubMed

    Heidari, Zahra; Mahmoudzadeh-Sagheb, Hamidreza; Moudi, Bita

    2008-12-01

    Diabetes is a major public health problem. Development of new therapies that are able to improve glycemia management, cure diabetes, and can even protect from it, are of great interest. This study investigated the protective effect of sodium tungstate against STZ-induced beta-cell damages by means of stereological methods. Sixty rats were divided into six groups: control (C), tungstate-treated control (TC), STZ-induced diabetic (D), STZ-induced diabetic rats were treated by sodium tungstate from 1 week before STZ injection (TDB), food-restricted diabetic (FRD), and diabetic rats treated with sodium tungstate 1 week after STZ administration (TDA). Stereological estimation of pancreas volume, islets volume density, volume-weighted mean islets volume and mass of beta cells, islets, and pancreas and total number of islets were done. Islets volume density, volume-weighted mean islets volume, and mass of beta cells, islets, and pancreas of TDB group was significantly higher than D, FRD and TDA groups (P<0.001) and was comparable to controls (C and TC groups). Total number of islets, pancreas wet weight and volume did not show any significant changes between these groups (P>0.05). Results suggested that sodium tungstate preserves pancreatic beta cells from STZ-induced damages and diabetes induction in rats.

  15. Tungstate-induced color-pattern modifications of butterfly wings are independent of stress response and ecdysteroid effect.

    PubMed

    Otaki, Joji M; Ogasawara, Tsuyoshi; Yamamoto, Haruhiko

    2005-06-01

    Systemic injections of sodium tungstate, a protein-tyrosine phosphatase (PTPase) inhibitor, to pupae immediately after pupation have been shown to efficiently produce characteristic color-pattern modifications on the wings of many species of butterflies. Here we demonstrated that the tungstate-induced modification pattern was entirely different from other chemically-induced ones in a species of nymphalid butterfly Junonia (Precis) orithya. In this species, the systemic injections of tungstate produced characteristic expansion of black area and shrinkage of white area together with the move of parafocal elements toward the wing base. Overall, pattern boundaries became obscure. In contrast, an entirely different modification pattern, overall darkening of wings, was observed by the injections of stress-inducing chemicals, thapsigargin, ionomycin, or geldanamycin, to pupae under the rearing conditions for the adult summer form. On the ventral wings, this darkening was due to an increase of the proportion of peppered dark scales, which was reminiscent of the natural fall form of this species. Under the same rearing conditions, the injections of ecdysteroid, which is a well-known hormone being responsible for the seasonal polyphenism of nymphalid butterflies, yielded overall expansion of orange area especially around eyespots. Taken together, we conclude that the tungstate-induced modifications are clearly distinguishable from those of stress response and ecdysteroid effect. This conclusion then suggests that the putative PTPase signaling pathway that is sensitive to tungstate uniquely contributes to the wing-wide color-pattern development in butterflies.

  16. Efficacy of some antioxidants supplementation in reducing oxidative stress post sodium tungstate exposure in male wistar rats.

    PubMed

    Sachdeva, S; Flora, S J S

    2014-04-01

    This study aimed to evaluate the protective efficacy of some antioxidants against sodium tungstate induced oxidative stress in male wistar rats. Animals were sub-chronically exposed to sodium tungstate (100ppm in drinking water) for three months except for control group. In the same time, many rats were supplemented orally with different antioxidants (alpha-lipoic acid (ALA), n-acetylcysteine (NAC), quercetin or naringenin (0.30mM)) for five consecutive days a week for the same mentioned period before. Exposure to sodium tungstate significantly (P<0.05) inhibit blood δ-aminolevulinic acid dehydratase (ALAD) activity, liver and blood reduced glutathione (GSH) levels and an increase in oxidized glutathione (GSSG) and thiobarbituric acid reactive species (TBARS) levels in tissues. ALA acid and NAC supplementation post sodium tungstate exposure increased GSH and also, was beneficial in the recovery of altered superoxide dismutase and catalase activity, besides, significantly reducing blood and tissue reactive oxygen species and TBARS levels. The results suggest a more pronounced efficacy of ALA acid and NAC supplementation than quercetin or naringenin supplementation post sodium tungstate exposure in preventing induced oxidative stress in rats.

  17. Atomistic simulation of ferroelectric-ferroelastic gadolinium molybdate

    NASA Astrophysics Data System (ADS)

    Dudnikova, V. B.; Zharikov, E. V.

    2017-05-01

    Gadolinium molybdate Gd2(MoO4)3 orthorhombic ferroelectric ferroelastic (β'-phase) is simulated by the method of interatomic potentials. The simulation is performed using the GULP 4.0.1 code (General Utility Lattice Program), which is based on the minimization of the energy of the crystal structure. Parameters of the gadolinium-oxygen interatomic interaction potentials are determined by fitting to the experimental structural data and elastic constants by a procedure available in the GULP code. Atomistic modeling using the effective atomic charges and the system of interatomic potentials made it possible to obtain reasonable estimates of structural parameters, atomic coordinates, and the most important physical, mechanical, and thermodynamic properties of these crystals. Temperature dependences of the heat capacity and vibrational entropy of the crystal are obtained. The calculated parameters of gadolinium-oxygen interaction potentials can be used to simulate more complex gadolinium-containing compounds.

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

    NASA Astrophysics Data System (ADS)

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

    2002-05-01

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

  19. Gadolinium loaded plastic scintillators for high efficiency neutron detection

    NASA Astrophysics Data System (ADS)

    Ovechkina, Lena; Riley, Kent; Miller, Stuart; Bell, Zane; Nagarkar, Vivek

    2009-08-01

    Gadolinium has the highest thermal neutron absorption cross section of any naturally occurring element, and emits conversion electrons as well as atomic X-rays in over 50% of its neutron captures, which makes it a useful dopant in scintillators for detecting thermal neutrons. Gadolinium isopropoxide was studied as a possible dopant for styrene-based plastic scintillators as a convenient and inexpensive method to produce high-efficiency thermal neutron detectors. Plastic scintillators with gadolinium weight concentrations of up to 3% were transparent, uniform and defect-free and were characterized with spectral measurements performed under x-ray and neutron irradiation. The new material has the same characteristic emission of styrene with a maximum at approximately 425 nm, and a light output of 76% relative to the undoped plastic. A 13 mm thick sample containing 0.5% gadolinium by weight detected 46% of incident thermal neutrons, which makes this an attractive material for a variety of applications.

  20. Gadolinium-DTPA enhancement of lung radiation fibrosis

    SciTech Connect

    Werthmuller, W.C.; Schiebler, M.L.; Whaley, R.A.; Mauro, M.A.; McCartney, W.H. )

    1989-11-01

    Gadolinium-diethylenetriamine pentaacetic acid (DTPA) enhancement of radiation-induced apical pulmonary fibrosis was observed in two patients previously treated for breast cancer. In one case the fibrosis was biopsied twice, with no change in its CT appearance over 3 years. Gadolinium-DTPA may enhance benign apical fibrosis after radiation therapy and should not, in and of itself, be used as evidence of recurrent malignancy.

  1. Comparison of the local and the average crystal structure of proton conducting lanthanum tungstate and the influence of molybdenum substitution.

    PubMed

    Magrasó, Anna; Frontera, Carlos

    2016-03-07

    We report on the comparison of the local and average structure reported recently for proton conducting lanthanum tungstate, of general formula La28-xW4+xO54+δv2-δ, and the impact of molybdenum-substitution on the crystal structure of the material. Partial replacement of W with 10 and 30 mol% Mo is investigated here, i.e. La27(W1-xMox)5O55.5 for x = 0.1 and 0.3. This study addresses the interpretation and the description of a disordered cation and anion sublattice in this material, which enables the understanding of the fundamental properties related to hydration, transport properties and degradation in lanthanum tungstate. The report shows that Mo-substituted lanthanum tungstate is a promising material as a dense oxide membrane for hydrogen separation at intermediate temperatures.

  2. Phase equilibria diagrams, crystal growth peculiarities and Raman investigations of lead and sodium-bismuth tungstate-molybdate solid solutions

    NASA Astrophysics Data System (ADS)

    Lebedev, Andrei V.; Avanesov, Samvel A.; Yunalan, Tyliay M.; Klimenko, Valeriy A.; Ignatyev, Boris V.; Isaev, Vladislav A.

    2016-02-01

    In this paper a comprehensive study of lead and sodium-bismuth tungstate-molybdate solid solutions was carried out, including the clarification of their structural peculiarities and phase diagrams of PbMoO4-PbWO4 and NaBi(MoO4)2-NaBi(WO4)2 systems, the study of spontaneous Raman spectra of these compounds, as well as preliminary experiments on single crystals growth of lead tungstate-molybdate. The linewidths, peak and integral intensities of the totally symmetric Raman vibrations of solid solutions were estimated in comparison with known SRS-active crystals. The conditions of the Czochralski growth of optically transparent lead tungstate-molybdate mixed crystals were found and SRS effect was observed in these crystals when pumping by 12 ns 1064 nm laser pulses.

  3. Activation of ERK by sodium tungstate induces protein synthesis and prevents protein degradation in rat L6 myotubes.

    PubMed

    Salto, Rafael; Vílchez, José D; Cabrera, Elena; Guinovart, Joan J; Girón, María D

    2014-06-27

    The balance between the rates of protein synthesis and degradation in muscle is regulated by PI3K/Akt signaling. Here we addressed the effect of ERK activation by sodium tungstate on protein turnover in rat L6 myotubes. Phosphorylation of ERK by this compound increased protein synthesis by activating MTOR and prevented dexamethasone-induced protein degradation by blocking FoxO3a activity, but it did not alter Akt phosphorylation. Thus, activation of ERK by tungstate improves protein turnover in dexamethasone-treated cells. On the basis of our results, we propose that tungstate be considered an alternative to IGF-I and its analogs in the prevention of skeletal muscle atrophy.

  4. TupA: a tungstate binding protein in the periplasm of Desulfovibrio alaskensis G20.

    PubMed

    Otrelo-Cardoso, Ana Rita; Nair, Rashmi R; Correia, Márcia A S; Rivas, Maria G; Santos-Silva, Teresa

    2014-07-02

    The TupABC system is involved in the cellular uptake of tungsten and belongs to the ABC (ATP binding cassette)-type transporter systems. The TupA component is a periplasmic protein that binds tungstate anions, which are then transported through the membrane by the TupB component using ATP hydrolysis as the energy source (the reaction catalyzed by the ModC component). We report the heterologous expression, purification, determination of affinity binding constants and crystallization of the Desulfovibrio alaskensis G20 TupA. The tupA gene (locus tag Dde_0234) was cloned in the pET46 Enterokinase/Ligation-Independent Cloning (LIC) expression vector, and the construct was used to transform BL21 (DE3) cells. TupA expression and purification were optimized to a final yield of 10 mg of soluble pure protein per liter of culture medium. Native polyacrylamide gel electrophoresis was carried out showing that TupA binds both tungstate and molybdate ions and has no significant interaction with sulfate, phosphate or perchlorate. Quantitative analysis of metal binding by isothermal titration calorimetry was in agreement with these results, but in addition, shows that TupA has higher affinity to tungstate than molybdate. The protein crystallizes in the presence of 30% (w/v) polyethylene glycol 3350 using the hanging-drop vapor diffusion method. The crystals diffract X-rays beyond 1.4 Å resolution and belong to the P21 space group, with cell parameters a = 52.25 Å, b = 42.50 Å, c = 54.71 Å, β = 95.43°. A molecular replacement solution was found, and the structure is currently under refinement.

  5. Tissue distribution of tungsten in mice following oral exposure to sodium tungstate.

    PubMed

    Guandalini, Gustavo S; Zhang, Lingsu; Fornero, Elisa; Centeno, Jose A; Mokashi, Vishwesh P; Ortiz, Pedro A; Stockelman, Michael D; Osterburg, Andrew R; Chapman, Gail G

    2011-04-18

    Heavy metal tungsten alloys have replaced lead and depleted uranium in many munitions applications, due to public perception of these elements as environmentally unsafe. Tungsten materials left in the environment may become bioaccessible as tungstate, which might lead to population exposure through water and soil contamination. Although tungsten had been considered a relatively inert and toxicologically safe material, recent research findings have raised concerns about possible deleterious health effects after acute and chronic exposure to this metal. This investigation describes tissue distribution of tungsten in mice following oral exposure to sodium tungstate. Twenty-four 6-9 weeks-old C57BL/6 laboratory mice were exposed to different oral doses of sodium tungstate (0, 62.5, 125, and 200 mg/kg/d) for 28 days, and after one day, six organs were harvested for trace element analysis with inductively coupled plasma mass spectrometry (ICP-MS). Kidney, liver, colon, bone, brain, and spleen were analyzed by sector-field high-resolution ICP-MS. The results showed increasing tungsten levels in all organs with increased dose of exposure, with the highest concentration found in the bones and the lowest concentration found in brain tissue. Gender differences were noticed only in the spleen (higher concentration of tungsten in female animals), and increasing tungsten levels in this organ were correlated with increased iron levels, something that was not observed for any other organ or either of the two other metals analyzed (nickel and cobalt). These findings confirmed most of what has been published on tungsten tissue distribution; they also showed that the brain is relatively protected from oral exposure. Further studies are necessary to clarify the findings in splenic tissue, focusing on possible immunological effects of tungsten exposure.

  6. Pharmacokinetics of sodium tungstate in rat and dog: a population approach.

    PubMed

    Le Lamer, S; Poucheret, P; Cros, G; de Richter, R K; Bonnet, P A; Bressolle, F

    2000-08-01

    Sodium tungstate has been found to correct hyperglycemia in insulin- and noninsulin-dependent models of diabetes when administered in drinking fluid with a low degree of toxicity; thus, it provides a potential treatment for diabetes. In the present report, pharmacokinetic studies with sodium tungstate were carried out in the Sprague-Dawley rat and beagle dog. This drug was administered either i.v. (8.97 mg/kg in rat; 25 and 50 mg/kg in dog) or orally in the form of solution (35.9 and 107.7 mg/kg in rat; 25 and 50 mg/kg in dog). Tungsten was quantified using an inductively coupled plasma method. Pharmacokinetic parameters were estimated using a population approach. Sodium tungstate followed first order kinetics, and plasma concentration-versus-time data were adequately described by a two-compartment model. In rat, bioavailability was high (92%), whereas it was lower in dog (approximately 65%). The total volume of distribution expressed by unit of body weight was much higher when the animal was smaller (0.46 l/kg in rat versus 0.23 l/kg in dog). The total body clearance normalized by weight, 0.19 l/h/kg in rat versus 0.043 l/h/kg in dog, changed as for the volume of distribution. The elimination half-life was two times higher in dog (approximately 4 h) than in rat (approximately 1.7 h). In the range of 35.9 to 107.7 mg/kg after oral administration in rat and 25 to 50 mg/kg after oral and i.v. administration in dog, tungsten plasma concentrations increased in proportion to dose.

  7. Analysis of solid solutions stability in scheelite-type molybdates and tungstates

    SciTech Connect

    Zhuravlev, V.D.; Reznitskikh, O.G.; Velikodnyi, Yu.A.; Patrusheva, T.A.; Sivtsova, O.V.

    2011-10-15

    Mutual solubility of bivalent metal molybdates and tungstates with scheelite structure was theoretically estimated by calculating formation enthalpies and the maximal decomposition temperatures of solid solutions at different temperatures. The theoretical stability of continuous solid solutions in binary systems of bivalent metal molybdates and tungstates was found to be higher than reported literature data. After cooling down continuous substitution solid solution should remain in following systems: CaMoO{sub 4}-CdMoO{sub 4}, SrMoO{sub 4}-MMoO{sub 4} (M=Ba, Pb), BaMoO{sub 4}-PbMoO{sub 4}, SrWO{sub 4}-MWO{sub 4} (M=Ca, Pb), and BaWO{sub 4}-PbWO{sub 4}. There is a probability that at room temperature in systems CaMoO{sub 4}-SrMoO{sub 4,} CaWO{sub 4}-PbWO{sub 4}, and BaWO{sub 4}-SrWO{sub 4} the single homogeneity region may decompose to limited solid solutions. It was shown experimentally that a continuous series of scheelite-structure solid solutions M{sub 1-x}M{sup I}{sub x}TO{sub 4} can be formed via citrate synthesis at temperatures below 500 deg. S. - Graphical abstract: Calculated boundaries of solid solutions in BaWO{sub 4}-CaWO{sub 4} (1) and PbMoO{sub 4}-CaMoO{sub 4} (2) systems. Highlights: > Stability of solid solutions molybdates and tungstates has been investigated. > The ionic model for isovalent substitutions was used. > In 'polyhedral substitution model' enthalphies of mixing were calculated. > Most of the examined series of solid solutions is stable at room temperatures. > Solid solutions M{sub 1-x}M{sup I}{sub x}Mo(W)O{sub 4} (x=0-1) were formed via citrate synthesis below 500 S.

  8. Special features in the electroreduction of oxidic molybdenum(VI) forms in tungstate melt

    SciTech Connect

    Shapoval, V.I.; Baraboshkin, A.N.; Kushkhov, K.B.; Malyshev, V.V.

    1988-01-01

    The electrochemical behavior of oxidic molybdenum in tungstate melt was studied under equilibrium and nonequilibrium conditions. Chronovoltammetry and transient polarization was used. The current-voltage curves were recorded with a pulse potentiostat and the experiments were performed in a quartz reactor with platinum and molybdenum electrodes and a platinum crucible served as the melt container and anode. The end product of the oxidic molybdenum forms were shown to depend on the acid-base properties of the melt which allows for choosing the properties and controlling the electrode process.

  9. Comparison of radiation damage in lead tungstate crystals under pion and gamma irradiation

    SciTech Connect

    Batarin, V.A.; Butler, J.; Davidenko, A.M.; Derevschikov, A.A.; Goncharenko, Y.M.; Grishin, V.N.; Kachanov, V.A.; Khodyrev, V.Y.; Konstantinov, A.S.; Kravtsov, V.I.; Kubota, Y.; Lukanin, V.S.; Matulenko, Y.A.; Melnick, Y.M.; Meschanin, A.P.; Mikhalin, N.E.; Minaev, N.G.; Mochalov, V.V.; Morozov, D.A.; Nogach, L.V.; Ryazantsev, A.V.; /Serpukhov, IHEP /Fermilab /Minnesota U. /Syracuse U. /Nanjing U.

    2003-12-01

    Studies of the radiation hardness of lead tungstate crystals produced by the Bogoroditsk Techno-Chemical Plant in Russia and the Shanghai Institute of Ceramics in China have been carried out at IHEP, Protvino. The crystals were irradiated by a 40 GeV pion beam. After full recovery, the same crystals were irradiated using a {sup 137}Cs {gamma}-ray source. The dose rate profiles along the crystal length were observed to be quite similar. We compare the effects of the two types of radiation on the crystals light output.

  10. High Performance Anion Chromatography of Gadolinium Chelates.

    PubMed

    Hajós, Peter; Lukács, Diana; Farsang, Evelin; Horváth, Krisztian

    2016-11-01

    High performance anion chromatography (HPIC) method to separate ionic Gd chelates, [Formula: see text], [Formula: see text], [Formula: see text] and free matrix anions was developed. At alkaline pHs, polydentate complexing agents such as ethylene-diamine-tetraacetate, diethylene-triamine pentaacetate and trans-1,2-diamine-cyclohexane-tetraacetate tend to form stable Gd chelate anions and can be separated by anion exchange. Separations were studied in the simple isocratic chromatographic run over the wide range of pH and concentration of carbonate eluent using suppressed conductivity detection. The ion exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity of Gd chelates. Parameters of optimized resolution between concurrent ions were presented on a 3D resolution surface. The applicability of the developed method is represented by the simultaneous analysis of Gd chelates and organic/inorganic anions. Inductively coupled plasma atomic emission spectroscopy  (ICP-AES) analysis was used for confirmation of HPIC results for Gd. Collection protocols for the heart-cutting procedure of chromatograms were applied. SPE procedures were also developed not only to extract traces of free gadolinium ions from samples, but also to remove the high level of interfering anions of the complex matrices. The limit of detection, the recoverability and the linearity of the method were also presented. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Nonaqueous Synthesis of Gadolinium and Neodymium Nanoparticles

    NASA Astrophysics Data System (ADS)

    Fukuda, R.; Castro, M.; Ho, P.-C.; Attar, S.; Golden, M.; Margosan, D.

    2014-03-01

    Nanoparticles are of great interest due to their magnetic properties, such as superparamagnetism, that are not exhibited by their bulk counterparts. Gd and Nd are being tested by applying the reverse micelle method. The reverse micelle method consists of using a surfactant with a large nonpolar solvent to polar solvent ratio to form spherical cages that control the size of the products. Many studies involving the reverse micelle method employ water as the polar solvent. Since Gd and Nd are highly reactive to water, methanol is used as a replacement with hexane or heptane as the nonpolar solvent. Gadolinium chloride or neodymium nitrate are reduced using sodium borohydride after the reverse micelles encapsulate the rare earth compound. Scanning electron microscopy (SEM) and light microscopy show small, spherical clusters with diameters in the micron range. Higher magnification of the SEM melted the clusters, even after cooling the sample to 87 K. The sample was coated with Pt to prevent melting. Energy dispersive x-ray measurements were conducted to find the chemical composition of the clusters, but the sample signals were too small to make a conclusion. Future growths will use the surfactant DDAB instead of AOT since DDAB is more stable when examined with SEM. Research at California State University-Fresno is supported by NSF DMR-1104544.

  12. Studies of narrow autoionizing resonances in gadolinium

    SciTech Connect

    Bushaw, Bruce A.; Nortershauser, W.; Blaum, K.; Wendt, Klaus

    2003-06-30

    The autoionization (AI) spectrum of gadolinium between the first and second limits has been investigated by triple-resonance excitation with high-resolution cw lasers. A large number of narrow AI resonances have been observed and assigned total angular momentum J values. The resonances are further divided into members of AI Rydberg series converging to the second limit or other ''interloping'' levels. Fine structure in the Rydberg series has been identified and interpreted in terms of Jc j coupling. A number of detailed studies have been performed on the interloping resonances: These include lifetime determination by lineshape analysis, isotope shifts, hyperfine structure, and photoionization saturation parameters. The electronic structure of the interloping levels is discussed in terms of these studies. Linewidths generally decrease with increasing total angular momentum and the J = 7 resonances are extremely narrow with Lorentzian widths ranging from < 1 MHz up to 157 MHz. The strongest resonances are found to have cross-sections of {approx}10-12 cm{sup 2} and photoionization can be saturated with powers available from cw diode lasers.

  13. Distribution profile of gadolinium in gadolinium chelate-treated renally-impaired rats: role of pharmaceutical formulation.

    PubMed

    Fretellier, Nathalie; Salhi, Mariem; Schroeder, Josef; Siegmund, Heiko; Chevalier, Thibaut; Bruneval, Patrick; Jestin-Mayer, Gaëlle; Delaloge, Francette; Factor, Cécile; Mayer, Jean-François; Fabicki, Jean-Michel; Robic, Caroline; Bonnemain, Bruno; Idée, Jean-Marc; Corot, Claire

    2015-05-25

    While not acutely toxic, chronic hepatic effect of certain gadolinium chelates (GC), used as contrast agent for magnetic resonance imaging, might represent a risk in renally-impaired patients due to free gadolinium accumulation in the liver. To answer this question, this study investigated the consequences of the presence of small amounts of either a soluble gadolinium salt ("free" Gd) or low-stability chelating impurity in the pharmaceutical solution of gadoteric acid, a macrocyclic GC with high thermodynamic and kinetic stabilities, were investigated in renally-impaired rats. Renal failure was induced by adding 0.75% adenine in the diet for three weeks. The pharmaceutical and commercial solution of gadoteric acid was administered (5 daily intravenous injections of 2.5 mmol Gd/kg) either alone or after being spiked with either "free" gadolinium (i.e., 0.04% w/v) or low-stability impurity (i.e., 0.06 w/v). Another GC, gadodiamide (low thermodynamic and kinetic stabilities) was given as its commercial solution at a similar dose. Non-chelated gadolinium was tested at two doses (0.005 and 0.01 mmol Gd/kg) as acetate salt. Gadodiamide induced systemic toxicity (mortality, severe epidermal and dermal lesions) and substantial tissue Gd retention. The addition of very low amounts of "free", non-chelated gadolinium or low thermodynamic stability impurity to the pharmaceutical solution of the thermodynamically stable GC gadoteric acid resulted in substantial capture of metal by the liver, similar to what was observed in "free" gadolinium salt-treated rats. Relaxometry studies strongly suggested the presence of free and soluble gadolinium in the liver. Electron microscopy examinations revealed the presence of free and insoluble gadolinium deposits in hepatocytes and Kupffer cells of rats treated with gadoteric acid solution spiked with low-stability impurity, free gadolinium and gadodiamide, but not in rats treated with the pharmaceutical solution of gadoteric acid. The

  14. Use of a Mixture of Gadolinium and Iodinated Contrast for Angiography

    SciTech Connect

    Badiola, Carlos M.

    2004-03-15

    The purpose of this study was to determine if the image quality of gadolinium digital subtraction angiography (DSA) can be improved by the addition of small quantities of iodinated contrast to gadolinium. The optical density (OD) of a mixture of four parts gadolinium-based contrast to one part iodinated contrast was measured through a phantom study and compared to that of full-strength gadolinium, full strength iodinated contrast, and a 20% solution of iodinated contrast. We also compared the clinical image quality of the mixture of gadolinium-based contrast and iodinated contrast relative to full-strength gadolinium and full strength iodinated contrast during DSA. The DSA image quality of the gadolinium-iodinated contrast mixture was significantly improved relative to images obtained with full-strength gadolinium and compared favorably to that obtained with full-strength iodinated contrast. The phantom data showed that the OD of the gadolinium-iodinated contrast mixture was much greater than that of full strength gadolinium and the 20% iodinated contrast solution. The increase in OD was greater than that expected from a simple additive effect of the OD of the contrast agents. Adding a small amount of iodinated contrast to gadolinium results in a significant improvement in the radiographic density and DSA image quality of gadolinium. This simple technique appears to overcome one of the major limitations of gadolinium-based angiography-poor radiographic density-while continuing to minimize the volume of administered iodinated contrast.

  15. Deposition of Highly Luminescent Zinc Tungstate Thin Films on Various Substrates

    NASA Astrophysics Data System (ADS)

    Farrakhan, Rashad

    Zinc tungstate films have promising applications in small form factor backscatter electron detectors. We are developing a multistep technology for synthesis of these films. Zinc and tungsten were co-sputtered onto substrates through the process of magnetron sputtering. The metallic films were oxidized in a vacuum sealed tube furnace in controlled flow of argon and oxygen at 800 °C. The chemical composition of the film was characterized by Energy-Dispersive X-Ray Spectroscopy (EDS). The structure of the film was investigated by Raman Spectroscopy. The photoluminescence quantum efficiency of the films was found to be 60%. Process parameters for obtaining the desired 1-1 ratio of zinc to tungsten in the film is explored through varying factors such as: the composition of the target used in the sputtering, the power and or voltage used in the sputtering process. Our experiments show that zinc tungstate thin films can be deposited on various substrates with good adhesion and mechanical integrity, and still be efficient light emitters.

  16. Adsorptional removal of methylene blue by guar gum-cerium (IV) tungstate hybrid cationic exchanger.

    PubMed

    Gupta, V K; Pathania, Deepak; Singh, Pardeep; Kumar, Amit; Rathore, B S

    2014-01-30

    Guar gum-cerium (IV) tungstate nanocomposite (GG/CTNC) cationic exchanger was synthesized using simple sol gel method. The GG/CTNC was characterized using X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectrophotometer (EDX). The XRD studies confirmed amorphous and fibrous in nature of GG/CTNC. The high percentage of oxygen in the nanocomposite material confirmed the functionality tungstate (WO4(-)). The ion exchange capacity of GG/CTNC for Na(+) ion was observed to be 1.30 mequivg(-1). The hybrid exchanger was used as potential adsorbent for the removal of methylene blue (MB) from aqueous system. The correlation coefficients value indicated a good fit of monolayer Langmuir model to the adsorption of methylene blue onto GG/CTNC. The adsorption kinetic study revealed that the adsorption process followed the pseudo second order kinetic. The Gibbs free energy (ΔG) values confirmed the spontaneous nature of adsorption process. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Synthesis and characterization of lead iron tungstate ceramics obtained by two preparation methods

    SciTech Connect

    Zhou, L.; Vilarinho, P.M.; Baptista, J.L. . Dept. de Engenharia Ceramica e do Vidro)

    1994-11-01

    Lead iron tungstate (Pb(Fe[sub 2/3]W[sub 1/3])O[sub 3]) is difficult to sinter as a single phase perovskite ceramic. Side reactions lead to undesirable second phases damaging the dielectric properties of the sintered material. Understanding these reaction routes is necessary to eliminate them and to improve on the properties of these ceramics. Lead iron tungstate ceramics were sintered from powders prepared by reaction of mixtures of the three oxides, or by reaction of prereacted iron oxide and tungsten oxide with lead oxide, in an attempt to control the formation of the perovskite phase. The reaction sequences, different in both cases, lead to a higher yield of the perovskite phase when the prereacted powders were used, avoiding therefore the presence of undesirable phases. The microstructures and dielectric properties of the sintered ceramics obtained by both methodologies are reported and compared. The prereacted intermediate phase method leads to a more ordered perovskite structure with better dielectric characteristics.

  18. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    NASA Astrophysics Data System (ADS)

    Yoshida, K.; Shiju, N. R.; Brown, D. R.; Boyes, E. D.; Gai, P. L.

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 Å = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  19. Structure of the molybdate/tungstate binding protein mop from Sporomusa ovata.

    PubMed

    Wagner, U G; Stupperich, E; Kratky, C

    2000-11-15

    Transport of molybdenum into bacteria involves a high-affinity ABC transporter system whose expression is controlled by a repressor protein called ModE. While molybdate transport is tightly coupled to utilization in some bacteria, other organisms have molybdenum storage proteins. One class of putative molybdate storage proteins is characterized by a sequence consisting of about 70 amino acids (Mop). A tandem repeat of Mop sequences also constitutes the molybdate binding domain of ModE. We have determined the crystal structure of the 7 kDa Mop protein from the methanol-utilizing anaerobic eubacterium Sporomusa ovata grown in the presence of molybdate and tungstate. The protein occurs as highly symmetric hexamers binding eight oxyanions. Each peptide assumes a so-called OB fold, which has previously also been observed in ModE. There are two types of oxyanion binding sites in Mo at the interface between two or three peptides. All oxyanion binding sites were found to be occupied by WO(4) rather than MoO(4). The biological function of proteins containing only Mop sequences is unknown, but they have been implicated in molybdate homeostasis and molybdopterin cofactor biosynthesis. While there are few indications that the S. ovata Mop binds pterin, the structure suggests that only the type-1 oxyanion binding sites would be sufficiently accessible to bind a cofactor. The observed occupation of the oxyanion binding sites by WO(4) indicates that Mop might also be involved in controlling intracellular tungstate levels.

  20. Two-Dimensional Iron Tungstate: A Ternary Oxide Layer With Honeycomb Geometry

    PubMed Central

    2016-01-01

    The exceptional physical properties of graphene have sparked tremendous interests toward two-dimensional (2D) materials with honeycomb structure. We report here the successful fabrication of 2D iron tungstate (FeWOx) layers with honeycomb geometry on a Pt(111) surface, using the solid-state reaction of (WO3)3 clusters with a FeO(111) monolayer on Pt(111). The formation process and the atomic structure of two commensurate FeWOx phases, with (2 × 2) and (6 × 6) periodicities, have been characterized experimentally by combination of scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption (TPD) and understood theoretically by density functional theory (DFT) modeling. The thermodynamically most stable (2 × 2) phase has a formal FeWO3 stoichiometry and corresponds to a buckled Fe2+/W4+ layer arranged in a honeycomb lattice, terminated by oxygen atoms in Fe–W bridging positions. This 2D FeWO3 layer has a novel structure and stoichiometry and has no analogues to known bulk iron tungstate phases. It is theoretically predicted to exhibit a ferromagnetic electronic ground state with a Curie temperature of 95 K, as opposed to the antiferromagnetic behavior of bulk FeWO4 materials. PMID:27110319

  1. PARTITIONING OF GADOLINIUM IN THE CHEMICAL PROCESSING CELL

    SciTech Connect

    Reboul, S.; Best, D.; Stone, M.; Click, D.

    2011-04-27

    A combination of short-term beaker tests and longer-duration Sludge Receipt and Adjustment Tank (SRAT) simulations were performed to investigate the relative partitioning behaviors of gadolinium and iron under conditions applicable to the Chemical Processing Cell (CPC). The testing was performed utilizing non-radioactive simple Fe-Gd slurries, non-radioactive Sludge Batch 6 simulant slurries, and a radioactive real-waste slurry representative of Sludge Batch 7 material. The testing focused on the following range of conditions: (a) Fe:Gd ratios of 25-100; (b) pH values of 2-6; (c) acidification via addition of nitric, formic, and glycolic acids; (d) temperatures of {approx}93 C and {approx}22 C; and (e) oxalate concentrations of <100 mg/kg and {approx}10,000 mg/kg. The purpose of the testing was to provide data for assessing the potential use of gadolinium as a supplemental neutron poison when dispositioning excess plutonium. Understanding of the partitioning behavior of gadolinium in the CPC was the first step in assessing gadolinium's potential applicability. Significant fractions of gadolinium partitioned to the liquid-phase at pH values of 4.0 and below, regardless of the Fe:Gd ratio. In SRAT simulations targeting nitric and formic acid additions of 150% acid stoichiometry, the pH dropped to a minimum of 3.5-4.0, and the maximum fractions of gadolinium and iron partitioning to solution were both {approx}20%. In contrast, in a SRAT simulation utilizing a nitric and formic acid addition under atypical conditions (due to an anomalously low insoluble solids content), the pH dropped to a minimum of 3.7, and the maximum fractions of gadolinium and iron partitioning to solution were {approx}60% and {approx}70%, respectively. When glycolic acid was used in combination with nitric and formic acids at 100% acid stoichiometry, the pH dropped to a minimum of 3.6-4.0, and the maximum fractions of gadolinium and iron partitioning to solution were 60-80% and 3-5%, respectively

  2. Simultaneous speciation analysis of chromate, molybdate, tungstate and vanadate in welding fume alkaline extracts by HPLC-ICP-MS.

    PubMed

    Ščančar, Janez; Berlinger, Balázs; Thomassen, Yngvar; Milačič, Radmila

    2015-09-01

    A novel analytical procedure was developed for the simultaneous speciation analysis of chromate, molybdate, tungstate and vanadate by anion-exchange high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Linear gradient elution from 100% water to 100% 0.7 M NaCl was applied for chromatographic separation of metal species. In standard aqueous solution at neutral pH molybdate, tungstate and vanadate exist in several aqueous species, while chromate is present as a single CrO4(2-) species. Consequently, only chromate can be separated from this solution in a sharp chromatographic peak. For obtaining sharp chromatographic peaks for molybdate, tungstate and vanadate, the pH of aqueous standard solutions was raised to 12. At highly alkaline conditions single CrO4(2-), MoO4(2-) and WO4(2-) are present and were eluted in sharp chromatographic peaks, while VO4(3-) species, which predominates at pH 12 was eluted in slightly broaden peak. In a mixture of aqueous standard solutions (pH 12) chromate, molybdate, tungstate and vanadate were eluted at retention times from 380 to 420 s, 320 to 370 s, 300 to 350 s and 240 to 360 s, respectively. Eluted species were simultaneously detected on-line by ICP-MS recording m/z 52, 95, 182 and 51. The developed procedure was successfully applied to the analysis of leachable concentrations of chromate, molybdate, tungstate and vanadate in alkaline extracts (2% NaOH+3% Na2CO3) of manual metal arc (MMA) welding fumes loaded on filters. Good repeatability and reproducibility of measurement (RSD±3.0%) for the investigated species were obtained in both aqueous standard solutions (pH 12) and in alkaline extracts of welding fumes. Low limits of detection (LODs) were found for chromate (0.02 ng Cr mL(-1)), molybdate (0.1 ng Mo mL(-1)), tungstate (0.1 ng W mL(-1)) and vanadate (0.2 ng V mL(-1)). The accuracy of analytical procedure for the determination of chromate was checked by analysis of

  3. Gadolinium metallo nanocongregates as potential magnetosensors for detecting early stage cancers

    SciTech Connect

    Dutta, Ranu; Pandey, Avinash C.

    2015-04-27

    Gadolinium chelates and gadolinium based inorganic nanoparticles have been extensively studied, because of the high magnetic moment of gadolinium. Here, metallic gadolinium nanocongregates have been developed. Upon injecting these nanoparticles in the mice, they initially circulate in the blood stream and are localized at the cancer site, which could be visualized upon application of magnetic field hence acting as small magnetic nanosensors searching for even small cancers, detecting cancers at a very early stage.

  4. Toxicological and pharmacological effects of gadolinium and samarium chlorides

    PubMed Central

    Haley, T. J.; Raymond, K.; Komesu, N.; Upham, H. C.

    1961-01-01

    A study has been made of the toxicology and pharmacology of gadolinium and samarium chlorides. The symptoms of acute toxicity following intraperitoneal injection are described. The chronic oral ingestion of both chemicals for 12 weeks produced no effects on growth or the blood picture, and only the male rats receiving gadolinium chloride showed liver damage. The pharmacological responses to both chemicals were mainly depressant on all systems studied, and death was associated with cardiovascular collapse coupled with respiratory paralysis. The greatest damage seen was on abraded skin, where non-healing ulcers were produced by both chemicals, whereas irritation of intact skin and ocular tissues was only transient in nature. PMID:13903826

  5. Gadolinium accumulation in organs of Sprague-Dawley® rats after implantation of a biodegradable magnesium-gadolinium alloy.

    PubMed

    Myrissa, Anastasia; Braeuer, Simone; Martinelli, Elisabeth; Willumeit-Römer, Regine; Goessler, Walter; Weinberg, Annelie Martina

    2017-01-15

    Biodegradable magnesium implants are under investigation because of their promising properties as medical devices. For enhancing the mechanical properties and the degradation resistance, rare earth elements are often used as alloying elements. In this study Mg10Gd pins were implanted into Sprague-Dawley® rats. The pin volume loss and a possible accumulation of magnesium and gadolinium in the rats' organs and blood were investigated in a long-term study over 36weeks. The results showed that Mg10Gd is a fast disintegrating material. Already 12weeks after implantation the alloy is fragmented to smaller particles, which can be found within the intramedullary cavity and the cortical bones. They disturbed the bone remodeling until the end of the study. The results concerning the elements' distribution in the animals' bodies were even more striking, since an accumulation of gadolinium could be observed in the investigated organs over the whole time span. The most affected tissue was the spleen, with up to 3240μgGd/kg wet mass, followed by the lung, liver and kidney (up to 1040, 685 and 207μgGd/kg). In the brain, muscle and heart, the gadolinium concentrations were much smaller (less than 20μg/kg), but an accumulation could still be detected. Interestingly, blood serum samples showed no accumulation of magnesium and gadolinium. This is the first time that an accumulation of gadolinium in animal organs was observed after the application of a gadolinium-containing degradable magnesium implant. These findings demonstrate the importance of future investigations concerning the distribution of the constituents of new biodegradable materials in the body, to ensure the patients' safety.

  6. Corrosion of nickel metal by hydrothermal sodium tungstate solution observed by in-situ infrared spectroscopy

    SciTech Connect

    Hoffmann, M.M.; Fulton, J.L.

    2000-05-01

    Corrosion of nickel metal in a high-temperature aqueous tungstate solution was described. The corrosion altered the solution's pH, which affected the equilibrium of the solution chemistry. These secondary effects of the corrosion process were observed with in-situ infrared (IR) spectroscopy, demonstrating that important information on corrosion phenomena at the solid-fluid interface may be obtained from in-situ spectroscopic studies of the fluid phase. Subsequent scanning electron microscopy (SEM) analysis of the corroded nickel metal and solid corrosion products support conclusions drawn from solution chemistry measurements. The presented findings are of interest to researchers and engineers that use pure nickel or nickel-bearing alloys as a material for high-temperature, high-pressure applications in aqueous solutions.

  7. Enzymatic activities in brains of diabetic rats treated with vanadyl sulphate and sodium tungstate.

    PubMed

    Lemberg, A; Fernández, M A; Ouviña, G; Rodríguez, R R; Peredo, H A; Susemihl, C; Villarreal, I; Filinger, E J

    2007-12-01

    The hypothesis of the present study was that diabetes mellitus might affect brain metabolism. Streptozotocin (STZ)-induced diabetic rats, treated with vanadyl sulphate (V) and sodium tungstate (T) were employed to observe the aspartate aminotransferase (AST), alanine aminotransferase (ALT) and creatine kinase (CK) activities in brain homogenates. Significant increases in AST, ALT and CK activities were found in diabetic brain homogenates against controls, suggesting increments of transamination in brain and/or increases in cell membrane permeability to these enzymes. The increase in brain CK possibly expresses alterations in energy production. The decrease in CK activity caused by V and T treatment in diabetic rats suggests that both agents tend to normalize energy consumption. It is also possible that V and T-induced hypoglycemic effects cause metabolic alterations in brain.

  8. An efficient bismuth tungstate visible-light-driven photocatalyst for breaking down nitric oxide.

    PubMed

    Li, Guisheng; Zhang, Dieqing; Yu, Jimmy C; Leung, Michael K H

    2010-06-01

    This paper reports a photocatalytic removal of 400 ppb level of NO in air under visible light irradiation by utilizing three-dimensional (3D) hierarchical bismuth tungstate (Bi(2)WO(6)) microspheres. A facile microwave-assisted hydrothermal method involving bismuth nitrate and sodium wolframate was developed to synthesize the photocatalyst. The Bi(2)WO(6) samples were characterized by using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Raman and ultraviolet-visible reflectance (UV-vis) spectroscopy. The relationship between the physicochemical property and the photocatalytic performance of the as prepared samples is discussed. The present work demonstrates that the 3D hierarchical Bi(2)WO(6) microspheres are effective visible-light-driven photocatalytic functional materials for air purification.

  9. On the influence of crystal structure on the electromagnetic shower development in the lead tungstate crystals

    NASA Astrophysics Data System (ADS)

    Baryshevsky, V. G.; Haurylavets, V. V.; Korjik, M. V.; Lobko, A. S.; Mechinsky, V. A.; Sytov, A. I.; Tikhomirov, V. V.; Uglov, V. V.

    2017-07-01

    The development of high-energy electromagnetic showers in long oriented lead tungstate crystals, accelerated by the effects induced by the strong field of atomic strings, is simulated for the first time. For that the characteristics of pair production and gamma-radiation by electrons or positrons were first simulated by the direct application of Baier-Katkov formulae in a thin PWO crystal to derive the scaling coefficients of the corresponding Bethe-Heitler cross sections to be incorporated into GEANT4 for the simulation of the electromagnetic shower development in a long crystal. Simulation results demonstrate the significant influence of the crystal structure on the e± and gamma-quanta registration processes in the existing homogeneous electromagnetic calorimeters and gamma-telescopes as well as wide possibilities of improving their performance in future developments.

  10. Scintillation of lead tungstate crystal studied with single-electron beam from KUFEL

    SciTech Connect

    Rizwan, Mohamad Uozumi, Yusuke; Matsuo, Kazuki; Ohgaki, Hideaki; Kii, Toshiteru; Zen, Heishun; Tsamalaidze, Zviadi; Evtoukhovitch, Petr; Valentin, Samoilov

    2015-04-29

    Lead tungstate (PWO) crystal has a very fast response, high atomic density and high radiation hardness. Therefore, they are suitable to be used for high-energy nuclear data measurements under high-background circumstances. Although a good electron-ion separation with a pulse shape analysis technique is essential, scintillation pulse shapes have not been observed with electron beams of a wide energy range. A single-electron beam technique has been developed at Kyoto University Free Electron Laser (KUFEL), and electron beams of 4-38 MeV are available. During the experiments, single electron beams bombarded a PWO crystal. By using oscilloscope we observed scintillation pulses of a PWO crystal coupled with a photomultiplier tube. Measured spectra were compared with the simulation code of EGS5 to analyze scattering effects. As the result, the pulse amplitudes show good linearity and the pulse shapes are almost constant in the observed energy range.

  11. Specific directions of ultrasound propagation in double potassium tungstates for light modulation.

    PubMed

    Mazur, M M; Mazur, L I; Pozhar, V E

    2017-01-01

    Acousto-optical characteristics of double potassium tungstates are analyzed and specific directions for light modulation are found. First, an important subgroup of elasto-optic coefficients of KYb(WO4)2 and KLu(WO4)2 crystals are calculated with use of experimental data. It is revealed that with proper choice of ultrasound direction the acousto-optical figure-of-merit approximately 2 times exceeds the maximum value detected in previous experiments. Another unique direction is determined, which permits modulation of randomly polarized light. The elasto-optic characteristics of KYb(WO4)2 and KLu(WO4)2 crystals are compared to those of previously investigated materials of the same crystal group: KY(WO4)2, KGd(WO4)2.

  12. High-pressure phase transitions and compressibility of wolframite-type tungstates

    NASA Astrophysics Data System (ADS)

    Ruiz-Fuertes, J.; López-Moreno, S.; Errandonea, D.; Pellicer-Porres, J.; Lacomba-Perales, R.; Segura, A.; Rodríguez-Hernández, P.; Muñoz, A.; Romero, A. H.; González, J.

    2010-04-01

    This paper reports an investigation on the phase diagram and compressibility of wolframite-type tungstates by means of x-ray powder diffraction and absorption in a diamond-anvil cell and ab initio calculations. X-ray diffraction experiments show that monoclinic wolframite-type MgWO4 suffers at least two phase transitions, the first one being to a triclinic polymorph with a structure similar to that of CuWO4 and FeMoO4-II. The onset of each transition is detected at 17.1 and 31 GPa. In ZnWO4 the onset of the monoclinic-triclinic transition has been also found at 16.7 GPa. This transition does not involve any change in the atomic coordination as confirmed by x-ray absorption measurements. These findings are supported by density-functional theory calculations, which predict the occurrence of additional transitions upon further compression. Calculations have been also performed for wolframite-type MnWO4, which is found to have an antiferromagnetic configuration. In addition, our study reveals details of the local-atomic compression in MgWO4 and ZnWO4. In particular, below the transition pressure the ZnO6 and equivalent polyhedra tend to become more regular, whereas, the WO6 octahedra remain almost unchanged. Fitting the pressure-volume data we obtained the equation of state for the low-pressure phase of MgWO4 and ZnWO4. These and previous results on MnWO4 and CdWO4 are compared with the calculations. The compressibility of wolframite-type tungstates is also systematically discussed. Finally Raman spectroscopy measurements and lattice dynamics calculations are presented for MgWO4.

  13. A study of the optical and radiation damage properties of lead tungstate crystals

    SciTech Connect

    Woody, C.L.; Kierstead, J.A.; Stoll, S.P.; Zhu, R.Y.; Ma, D.A.; Newman, H.B.

    1995-12-31

    Lead tungstate (PbWO{sub 4}) is a new scintillating material which is of great interest for use in high energy electromagnetic calorimeters. It has a very high density, short radiation length and small Moliere radius and has a scintillation light output which peaks between 450--550 nm with a decay time in the range from 5--15 ns. It is presently being considered for use in two large, high resolution electromagnetic calorimeters, one for the CMS experiment and the other for the ALICE experiment, at the Large Hadron Collider at CERN. In order to meet the stringent demands of these two experiments, the crystals are required to be of high purity, produced uniform light output, and, in the case of CMS, be resistant to radiation damage up to several megarads. Here, a study has been made of the optical and radiation damage properties of undoped and niobium doped lead tungstate crystals. Data were obtained on the optical absorbance, the intensity and decay time of the scintillation light output, and the radioluminescence and photoluminescence emission spectra. Radiation damage was studied in several undoped and niobium doped samples using {sup 60}Co gamma ray irradiation. The change in optical absorption and observed scintillation light output was measured as a function of dose up to total cumulative doses on the order of 800 krad. The radiation induced phosphorescence and thermoluminescence was also measured, as well as recovery from damage by optical bleaching and thermal annealing. An investigation was also made to determine trace element impurities in several samples.

  14. Tungstate (VI) sorption on hematite: An in situ ATR-FTIR probe on the mechanism.

    PubMed

    Rakshit, Sudipta; Sallman, Bryan; Davantés, Athénais; Lefèvre, Grégory

    2017-02-01

    Owing to the suspected toxicity and carcinogenicity of tungstate (VI) oxyanions [i.e. mono tungstate and several polytungstate, generally represented by W (VI)], the environmental fate of W (VI) has been widely studied. Sorption is regarded as a major mechanism by which W (VI) species are retained in the solid/water interface. Iron (hydr)oxides have been considered important environmental sinks for W (VI) species. Here we report sorption mechanisms of W (VI) on a common iron oxide mineral-hematite under environmentally relevant solution properties using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic probes. Initial W (VI) loadings varied from 10 to 200 μM at fixed pH values ranged from 4.6 to 8.1. For pH envelop (pHs = 4.6, 5.0, 5.5, 6.0, 6.5, 7.5, and 8.1) experiments, fixed W (VI) concentrations (i.e. 10 & 200 μM) were used to understand the effects of pH. The results indicated that at acidic pH values (pH < 6.0) the sorbed polytungstate surface species are prominent at 200 μM initial W (VI) conc. The pH envelop experiments revealed that sorbed polytungstates can be present even at lower initial W (VI) conc. (i.e. 10 μM) at pH values <5.5. Overall, our in situ ATR-FTIR experiments indicated that W (VI) forms inner-sphere type bonds on hematite surface and the strength of the interaction increases with decreasing pH. In addition, initial W (VI) concentration affected the sorption mechanisms of W (VI) on hematite. Our study will aid the molecular level understanding of W (VI) retention on iron oxide surfaces. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Lasing properties of new Nd 3+-doped tungstate, molybdate, and fluoride materials under selective optical pumping

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Jelínkova, Helena; Basiev, Tolstoban T.; Doroschenko, Maxim E.; Ivleva, Ludmila I.; Osiko, Vyacheslav V.; Zverev, Peter G.

    2006-02-01

    The purpose of this work was to determine the relative efficiencies of new Nd 3+-doped laser active/Raman - tungstate, molybdate, and fluoride - materials (SrWO 4, PbWO 4, BaWO 4, SrMoO 4, PbMoO 4, SrF II, and LaF 3) under selective longitudinal optical pumping by the alexandrite (~750nm), or diode (~800nm) laser. Crystals with various length, orientations and active ions concentrations were tested. To optimize the output of the tested lasers a set of input dichroic and output dielectric mirrors with different reflectivities were used. For realized lasers operating at pulsed free-running regime, threshold energy, slope efficiency, emission wavelength, and radiation polarization were determined. For each crystal, fluorescence lifetime and absorption coefficient under given pumping were established. The slope efficiency in case of Nd 3+:PbMoO 4 laser at wavelength 1054nm was measured to be 54.3% with total efficiency of 46% which is the best result obtained for all new tested crystals. For Nd 3+ doped SrWO 4, PbWO 4, and BaWO 4 crystals simultaneous laser and self-Raman emission were demonstrated in Q-switched regime. Thus newly proposed laser Raman crystals demonstrate high efficiency for Nd 3+ laser oscillations comparable with well known and widely used Nd:KGW crystal. Further improvement in the quality of tungstate and molybdate type crystals should result in further increase in lasing efficiency at 1.06μm wavelength. Self Raman frequency conversion of Nd 3+-laser oscillations in these crystals should result in high efficient pulse shortening, high peak power and new wavelengths in 1.2-1.5μm wavelength region.

  16. Effect of tungstate on acetate and ethanol production by the electrosynthetic bacterium Sporomusa ovata.

    PubMed

    Ammam, Fariza; Tremblay, Pier-Luc; Lizak, Dawid M; Zhang, Tian

    2016-01-01

    Microbial electrosynthesis (MES) and gas fermentation are bioenergy technologies in which a microbial catalyst reduces CO2 into organic carbon molecules with electrons from the cathode of a bioelectrochemical system or from gases such as H2. The acetogen Sporomusa ovata has the capacity of reducing CO2 into commodity chemicals by both gas fermentation and MES. Acetate is often the only product generated by S. ovata during autotrophic growth. In this study, trace elements in S. ovata growth medium were optimized to improve MES and gas fermentation productivity. Augmenting tungstate concentration resulted in a 2.9-fold increase in ethanol production by S. ovata during H2:CO2-dependent growth. It also promoted electrosynthesis of ethanol in a S. ovata-driven MES reactor and increased acetate production 4.4-fold compared to unmodified medium. Furthermore, fatty acids propionate and butyrate were successfully converted to their corresponding alcohols 1-propanol and 1-butanol by S. ovata during gas fermentation. Increasing tungstate concentration enhanced conversion efficiency for both propionate and butyrate. Gene expression analysis suggested that tungsten-containing aldehyde ferredoxin oxidoreductases (AORs) and a tungsten-containing formate dehydrogenase (FDH) were involved in the improved biosynthesis of acetate, ethanol, 1-propanol, and 1-butanol. AORs and FDH contribute to the fatty acids re-assimilation pathway and the Wood-Ljungdahl pathway, respectively. This study presented here shows that optimization of microbial catalyst growth medium can improve productivity and lead to the biosynthesis of different products by gas fermentation and MES. It also provides insights on the metabolism of biofuels production in acetogens and demonstrates that S. ovata has an important untapped metabolic potential for the production of other chemicals than acetate via CO2-converting bioprocesses including MES.

  17. Neutron Detection Utilizing Gadolinium Doped Hafnium Oxide Films

    DTIC Science & Technology

    2008-03-01

    emit low energy gamma rays, alpha particles, and neutron radiation . Many instruments capable of gamma detection have been available for decades...neutron detection because its interaction with neutrons creates fast electrons and gamma rays. Therefore, background gamma radiation causes a more...NEUTRON DETECTION UTILIZING GADOLINIUM DOPED HAFNIUM OXIDE FILMS THESIS Bryan D. Blasy, 2Lt

  18. Discovery of samarium, europium, gadolinium, and terbium isotopes

    SciTech Connect

    May, E.; Thoennessen, M.

    2013-01-15

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

  19. Gadolinium chloride pretreatment ameliorates acute cadmium-induced hepatotoxicity.

    PubMed

    Kyriakou, Loukas G; Tzirogiannis, Konstantinos N; Demonakou, Maria D; Kourentzi, Kalliopi T; Mykoniatis, Michael G; Panoutsopoulos, Georgios I

    2013-08-01

    Cadmium is a known industrial and environmental pollutant. It causes hepatotoxicity upon acute administration. Features of cadmium-induced acute hepatoxicity encompass necrosis, apoptosis, peliosis and inflammatory infiltration. Gadolinium chloride (GdCl3) may prevent cadmium-induced hepatotoxicity by suppressing Kupffer cells. The effect of GdCl3 pretreatment on a model of acute cadmium-induced liver injury was investigated. Male Wistar rats 4-5 months old were injected intraperitoneally with normal saline followed by cadmium chloride (CdCl2; 6.5 mg/kg) or GdCl3 (10 mg/kg) followed by CdCl2 (6.5 mg/kg; groups I and II, respectively). Rats of both the groups were killed at 9, 12, 16, 24, 48 and 60 h after cadmium intoxication. Liver sections were analyzed for necrosis, apoptosis, peliosis and mitoses. Liver regeneration was also evaluated by tritiated thymidine incorporation into hepatic DNA. Serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were also determined. Hepatic necrosis, hepatocyte and nonparenchymal cell apoptosis and macroscopic and microscopic types of peliosis hepatis were minimized by gadolinium pretreatment. Serum levels of AST and ALT were also greatly diminished in rats of group II. Tritiated thymidine incorporation into hepatic DNA was increased in gadolinium pretreatment rats. Kupffer cell activation was minimal in both the groups of rats. Gadolinium pretreatment attenuates acute cadmium-induced liver injury in young Wistar rats, with mechanisms other than Kupffer cell elimination.

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

    NASA Astrophysics Data System (ADS)

    Boiko, R. S.; Barabash, A. S.; Belli, P.; Bernabei, R.; Cappella, F.; Cerulli, R.; Danevich, F. A.; Incicchitti, A.; Laubenstein, M.; Mokina, V. M.; Nisi, S.; Poda, D. V.; Polischuk, O. G.; Tretyak, V. I.

    2014-01-01

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

  1. Layered gadolinium hydroxides for low-temperature magnetic cooling.

    PubMed

    Abellán, Gonzalo; Espallargas, Guillermo Mínguez; Lorusso, Giulia; Evangelisti, Marco; Coronado, Eugenio

    2015-09-28

    Layered gadolinium hydroxides have revealed to be excellent candidates for cryogenic magnetic refrigeration. These materials behave as pure 2D magnetic systems with a Heisenberg-Ising critical crossover, induced by dipolar interactions. This 2D character and the possibility offered by these materials to be delaminated open the possibility of rapid heat dissipation upon substrate deposition.

  2. Structural and magnetic phase transitions in gadolinium under high pressures and low temperatures

    DOE PAGES

    Samudrala, Gopi K.; Tsoi, Georgiy M.; Weir, Samuel T.; ...

    2014-11-07

    High pressure structural transition studies have been carried out on rare earth metal gadolinium in a diamond anvil cell at room temperature to 169 GPa. Gadolinium has been compressed to 38% of its initial volume at this pressure. With increasing pressure, a crystal structure sequence of hcp → Smtype→ dhcp → fcc → dfcc → monoclinic has been observed in our studies on gadolinium. The measured equation of state of gadolinium is presented to 169 GPa at ambient temperature. Magnetic ordering temperature of gadolinium has been studied using designer diamond anvils to a pressure of 25 GP and a temperaturemore » of 10 K. The magnetic ordering temperature has been determined from the four-point electrical resistivity measurements carried out on gadolinium. Furthermore, our experiments show that the magnetic transition temperature decreases with increasing pressure to 19 GPa and then increases when gadolinium is subjected to higher pressures.« less

  3. Structural and magnetic phase transitions in gadolinium under high pressures and low temperatures

    SciTech Connect

    Samudrala, Gopi K.; Tsoi, Georgiy M.; Weir, Samuel T.; Vohra, Yogesh K.

    2014-11-07

    High pressure structural transition studies have been carried out on rare earth metal gadolinium in a diamond anvil cell at room temperature to 169 GPa. Gadolinium has been compressed to 38% of its initial volume at this pressure. With increasing pressure, a crystal structure sequence of hcp → Smtype→ dhcp → fcc → dfcc → monoclinic has been observed in our studies on gadolinium. The measured equation of state of gadolinium is presented to 169 GPa at ambient temperature. Magnetic ordering temperature of gadolinium has been studied using designer diamond anvils to a pressure of 25 GP and a temperature of 10 K. The magnetic ordering temperature has been determined from the four-point electrical resistivity measurements carried out on gadolinium. Furthermore, our experiments show that the magnetic transition temperature decreases with increasing pressure to 19 GPa and then increases when gadolinium is subjected to higher pressures.

  4. Magnetic resonance characteristics and susceptibility weighted imaging of the brain in gadolinium encephalopathy.

    PubMed

    Samardzic, Dejan; Thamburaj, Krishnamoorthy

    2015-01-01

    To report the brain imaging features on magnetic resonance imaging (MRI) in inadvertent intrathecal gadolinium administration. A 67-year-old female with gadolinium encephalopathy from inadvertent high dose intrathecal gadolinium administration during an epidural steroid injection was studied with multisequence 3T MRI. T1-weighted imaging shows pseudo-T2 appearance with diffusion of gadolinium into the brain parenchyma, olivary bodies, and membranous labyrinth. Nulling of cerebrospinal fluid (CSF) signal is absent on fluid attenuation recovery (FLAIR). Susceptibility-weighted imaging (SWI) demonstrates features similar to subarachnoid hemorrhage. CT may demonstrate a pseudo-cerebral edema pattern given the high attenuation characteristics of gadolinium. Intrathecal gadolinium demonstrates characteristic imaging features on MRI of the brain and may mimic subarachnoid hemorrhage on susceptibility-weighted imaging. Identifying high dose gadolinium within the CSF spaces on MRI is essential to avoid diagnostic and therapeutic errors. Copyright © 2013 by the American Society of Neuroimaging.

  5. Gadolinium Brain Deposition after Macrocyclic Gadolinium Administration: A Pediatric Case-Control Study.

    PubMed

    Tibussek, Daniel; Rademacher, Christin; Caspers, Julian; Turowski, Bernd; Schaper, Jörg; Antoch, Gerald; Klee, Dirk

    2017-10-01

    Purpose To determine whether signal intensity (SI) in T1 sequences as a potential indicator of gadolinium deposition increases after repeated administration of the macrocyclic gadolinium-based contrast agents (GBCAs) gadoteridol and gadoterate meglumine in a pediatric cohort. Materials and Methods This retrospective case-control study of children with brain tumors who underwent nine or more contrast material-enhanced brain magnetic resonance (MR) imaging studies from 2008 to 2015 was approved by the local ethics board. Informed consent was obtained for MR imaging. Twenty-four case patients aged 5-18 years and appropriate control patients with nonpathologic MR neuroimaging findings (and no GBCA administration), matched for age and sex, were inculded. SI was measured on unenhanced T1-weighted MR images for the following five regions of interest (ROIs): the dentate nucleus (DN), pons, substantia nigra (SN), pulvinar thalami, and globus pallidus (GP). Paired t tests were used to compare SI and SI ratios (DN to pons, GP to thalamus) between case patients and control patients. Pearson correlations between relative signal changes and the number of GBCA administrations and total GBCA dose were calculated. Results The mean number of GBCA administrations was 14.2. No significant differences in mean SI for any ROI and no group differences were found when DN-to-pons and GP-to-pulvinar ratios were compared (DN-to-pons ratio in case patients: mean, 1.0083 ± 0.0373 [standard deviation]; DN-to-pons ratio in control patients: mean, 1.0183 ± 0.01917; P = .37; GP-to-pulvinar ratio in case patients: mean, 1.1335 ± 0.04528; and GP-to-pulvinar ratio in control patients: mean, 1.1141 ± 0.07058; P = .29). No correlation was found between the number of GBCA administrations or the total amount of GBCA administered and signal change for any ROI. (Number of GBCA applications: DN: r = -0.254, P = .31; pons: r = -0.097, P = .65; SN: r = -0.194, P = .38; GP: r = -0.175, P = .41; pulvinar: r

  6. Linear Gadolinium-Based Contrast Agents Are Associated With Brain Gadolinium Retention in Healthy Rats

    PubMed Central

    Robert, Philippe; Violas, Xavier; Grand, Sylvie; Lehericy, Stéphane; Idée, Jean-Marc; Ballet, Sébastien; Corot, Claire

    2016-01-01

    Objectives The aim of this study was to evaluate Gd retention in the deep cerebellar nuclei (DCN) of linear gadolinium-based contrast agents (GBCAs) compared with a macrocyclic contrast agent. Materials and Methods The brain tissue retention of Gd of 3 linear GBCAs (gadobenate dimeglumine, gadopentetate dimeglumine, and gadodiamide) and a macrocyclic GBCA (gadoterate meglumine) was compared in healthy rats (n = 8 per group) that received 20 intravenous injections of 0.6 mmol Gd/kg (4 injections per week for 5 weeks). An additional control group with saline was included. T1-weighted magnetic resonance imaging was performed before injection and once a week during the 5 weeks of injections and for another 4 additional weeks after contrast period. Total gadolinium concentration was measured with inductively coupled plasma mass spectrometry. Blinded qualitative and quantitative evaluations of the T1 signal intensity in DCN were performed, as well as a statistical analysis on quantitative data. Results At completion of the injection period, all the linear contrast agents (gadobenate dimeglumine, gadopentetate dimeglumine, and gadodiamide) induced a significant increase in signal intensity in DCN, unlike the macrocyclic GBCA (gadoterate meglumine) or saline. The T1 hypersignal enhancement kinetic was fast for gadodiamide. Total Gd concentrations for the 3 linear GBCAs groups at week 10 were significantly higher in the cerebellum (1.21 ± 0.48, 1.67 ± 0.17, and 3.75 ± 0.18 nmol/g for gadobenate dimeglumine, gadopentetate dimeglumine, and gadodiamide, respectively) than with the gadoterate meglumine (0.27 ± 0.16 nmol/g, P < 0.05) and saline (0.09 ± 0.12 nmol/g, P < 0.05). No significant difference was observed between the macrocyclic agent and saline. Conclusions Repeated administrations of the linear GBCAs gadodiamide, gadobenate dimeglumine, and gadopentetate dimeglumine to healthy rats were associated with progressive and significant T1 signal hyperintensity in the

  7. Linear Gadolinium-Based Contrast Agents Are Associated With Brain Gadolinium Retention in Healthy Rats.

    PubMed

    Robert, Philippe; Violas, Xavier; Grand, Sylvie; Lehericy, Stéphane; Idée, Jean-Marc; Ballet, Sébastien; Corot, Claire

    2016-02-01

    The aim of this study was to evaluate Gd retention in the deep cerebellar nuclei (DCN) of linear gadolinium-based contrast agents (GBCAs) compared with a macrocyclic contrast agent. The brain tissue retention of Gd of 3 linear GBCAs (gadobenate dimeglumine, gadopentetate dimeglumine, and gadodiamide) and a macrocyclic GBCA (gadoterate meglumine) was compared in healthy rats (n = 8 per group) that received 20 intravenous injections of 0.6 mmol Gd/kg (4 injections per week for 5 weeks). An additional control group with saline was included. T1-weighted magnetic resonance imaging was performed before injection and once a week during the 5 weeks of injections and for another 4 additional weeks after contrast period. Total gadolinium concentration was measured with inductively coupled plasma mass spectrometry. Blinded qualitative and quantitative evaluations of the T1 signal intensity in DCN were performed, as well as a statistical analysis on quantitative data. At completion of the injection period, all the linear contrast agents (gadobenate dimeglumine, gadopentetate dimeglumine, and gadodiamide) induced a significant increase in signal intensity in DCN, unlike the macrocyclic GBCA (gadoterate meglumine) or saline. The T1 hypersignal enhancement kinetic was fast for gadodiamide. Total Gd concentrations for the 3 linear GBCAs groups at week 10 were significantly higher in the cerebellum (1.21 ± 0.48, 1.67 ± 0.17, and 3.75 ± 0.18 nmol/g for gadobenate dimeglumine, gadopentetate dimeglumine, and gadodiamide, respectively) than with the gadoterate meglumine (0.27 ± 0.16 nmol/g, P < 0.05) and saline (0.09 ± 0.12 nmol/g, P < 0.05). No significant difference was observed between the macrocyclic agent and saline. Repeated administrations of the linear GBCAs gadodiamide, gadobenate dimeglumine, and gadopentetate dimeglumine to healthy rats were associated with progressive and significant T1 signal hyperintensity in the DCN, along with Gd deposition in the cerebellum. This

  8. On the nature of defect states in tungstate nanoflake arrays as promising photoanodes in solar fuel cells.

    PubMed

    Mohamed, Aya M; Amer, Ahmad W; AlQaradawi, Siham Y; Allam, Nageh K

    2016-08-10

    An electrochemical method is presented to study the nature of the defect states in sub-stoichiometric tungsten oxide nanoflake photoanodes used in water splitting. First, stoichiometric/sub-stoichiometric tungstate nanoflake arrays were deliberately developed via annealing under different atmospheres (air, O2, and H2) in different sequences. UV-Vis diffuse reflectance spectra and Tauc analysis indicated the presence of oxygen vacancies, which was also confirmed via XRD and Raman analysis, with samples annealed in an air/O2 sequence resulting in the most stoichiometric monoclinic structures. A defect sensitivity factor was proposed to explain the nature of defects whether they are deep or shallow. Mott-Schottky analysis was used to confirm the expected defect donor densities, as well as to confirm the nature of the developed oxygen vacancy defect states. The tungstate photoanodes were tested in photoelectrochemical water splitting cells and their photoconversion efficiency was demonstrated and discussed in detail.

  9. Dinuclear Face-Sharing Bi-octahedral Tungsten(VI) Core and Unusual Thermal Behavior in Complex Th Tungstates.

    PubMed

    Xiao, Bin; Gesing, Thorsten M; Robben, Lars; Bosbach, Dirk; Alekseev, Evgeny V

    2015-05-18

    Invited for the cover of this issue are the groups of Evgeny V. Alekseev at the Forchungszentrum Jülich and Thorstem M. Gesing at the University of Bremen. The image depicts the complex thorium tungstate polyanions, having a six-leafed lily cross-section, containing a rare confacial [W2 O9 ](6-) bioctahedral core. Read the full text of the article at 10.1002/chem.201500500.

  10. Estimation of pharmacokinetic parameters of sodium tungstate after multiple-dose during preclinical studies in beagle dogs.

    PubMed

    Le Lamer, S; Cros, G; Serrano, J J; Piñol, C; Fernändez-Alvarez, J; Bressolle, F

    2001-12-01

    In this paper, an empirical Bayes methodology was used to determine the pharmacokinetic profile of sodium tungstate in beagle dogs after multiple oral dosing using the P-PHARM computer program. The population estimation algorithm used in P-PHARM is an EM-type procedure. Sodium tungstate was administered orally, three times a day, (i) for 11 days (21 and 42 mg/kg per day) to 18 dogs (nine males and nine females) and (ii) for 13 weeks (15, 30 and 60 mg/kg per day) to 28 dogs (14 males, 14 females). Six other dogs received the compound intravenously (25 and 50 mg/kg). Plasma concentration profiles versus time were compatible with a two-compartment model and first-order kinetics. After oral administration, F (0.61+/-0.086 vs. 0.48+/-0.093), and normalized (to a 7-mg/kg dose of sodium tungstate) AUC (54+/-8.4 vs. 41.2+/-8.5 mg/l x h), C(max) (10.6+/-0.49 vs. 8.5+/-0.57 microg/ml) and C(min) (3.04+/-0.23 vs. 2.04+/-0.22 microg/ml), were higher in male than in female dogs. However, the introduction of the gender in the final model did not contribute statistically to an improvement of the fit of the population pharmacokinetic model. In males, t(1/2) elimination averaged 3.1+/-0.56 vs. 2.6+/-0.18 h in females. The duration of treatment did not modify statistically the pharmacokinetic parameters. After repeated multiple oral administration of 15-60 mg/kg per day of sodium tungstate, tungsten plasma concentrations increased in proportion to dose. No dose-dependent changes in pharmacokinetic parameters occurred.

  11. Assessing the performance under ionising radiation of lead tungstate scintillators for EM calorimetry in the CLAS12 Forward Tagger

    NASA Astrophysics Data System (ADS)

    Fegan, S.; Auffray, E.; Battaglieri, M.; Buchanan, E.; Caiffi, B.; Celentano, A.; Colaneri, L.; D`Angelo, A.; De Vita, R.; Dormenev, V.; Fanchini, E.; Lanza, L.; Novotny, R. W.; Parodi, F.; Rizzo, A.; Sokhan, D.; Tarasov, I.; Zonta, I.

    2015-07-01

    The well-established technology of electromagnetic calorimetry using Lead Tungstate crystals has recently seen an upheaval, with the closure of one of the most experienced large-scale suppliers of such crystals, the Bogoroditsk Technical Chemical Plant (BTCP), which was instrumental in the development of mass production procedures for PWO-II, the current benchmark for this scintillator. Obtaining alternative supplies of Lead Tungstate crystals matching the demanding specifications of contemporary calorimeter devices now presents a significant challenge to detector research and development programmes. In this paper we describe a programme of assessment carried out for the selection, based upon the performance under irradiation, of Lead Tungstate crystals for use in the Forward Tagger device, part of the CLAS12 detector in Hall B at Jefferson Lab. The crystals tested were acquired from SICCAS, the Shanghai Institute of Ceramics, Chinese Academy of Sciences. The tests performed are intended to maximise the performance of the detector within the practicalities of the crystal manufacturing process. Results of light transmission, before and after gamma ray irradiation, are presented and used to calculate dk, the induced radiation absorption coefficient, at 420 nm, the peak of the Lead Tungstate emission spectrum. Results for the SICCAS crystals are compared with identical measurements carried out on Bogoroditsk samples, which were acquired for the Forward Tagger development program before the closure of the facility. Also presented are a series of tests performed to determine the feasibility of recovering radiation damage to the crystals using illumination from an LED, with such illumination available in the Forward Tagger from a light monitoring system integral to the detector.

  12. Gadolinium Chelate Safety in Pregnancy: Barely Detectable Gadolinium Levels in the Juvenile Nonhuman Primate after in Utero Exposure.

    PubMed

    Prola-Netto, Joao; Woods, Mark; Roberts, Victoria H J; Sullivan, Elinor L; Miller, Christina Ann; Frias, Antonio E; Oh, Karen Y

    2017-09-04

    Purpose To determine whether gadolinium remains in juvenile nonhuman primate tissue after maternal exposure to intravenous gadoteridol during pregnancy. Materials and Methods Gravid rhesus macaques and their offspring (n = 10) were maintained, as approved by the institutional animal care and utilization committee. They were prospectively studied as part of a pre-existing ongoing research protocol to evaluate the effects of maternal malnutrition on placental and fetal development. On gestational days 85 and 135, they underwent placental magnetic resonance imaging after intravenous gadoteridol administration. Amniocentesis was performed on day 135 prior to administration of the second dose of gadoteridol. After delivery, the offspring were followed for 7 months. Tissue samples from eight different organs and from blood were harvested from each juvenile macaque. Gadolinium levels were measured by using inductively coupled plasma mass spectrometry. Results Gadolinium concentration in the amniotic fluid was 0.028 × 10(-5) %ID/g (percentage injected dose per gram of tissue) 50 days after administration of one gadoteridol dose. Gadolinium was most consistently detected in the femur (mean, 2.5 × 10(-5) %ID/g; range, [0.81-4.1] × 10(-5) %ID/g) and liver (mean, 0.15 × 10(-5) %ID/g; range, [0-0.26] × 10(-5) %ID/g). Levels were undetectable in the remaining sampled tissues, with the exception of one juvenile skin sample (0.07 × 10(-5) %ID/g), one juvenile spleen sample (0.039 × 10(-5) %ID/g), and one juvenile brain (0.095 × 10(-5) %ID/g) and kidney (0.13 × 10(-5) %ID/g) sample. Conclusion The presence of gadoteridol in the amniotic fluid after maternal injection enables confirmation that it crosses the placenta. Extremely low levels of gadolinium are found in juvenile macaque tissues after in utero exposure to two doses of gadoteridol, indicating that a very small amount of gadolinium persists after delivery. (©) RSNA, 2017.

  13. About a Gadolinium-doped Water Cherenkov LAGUNA Detector

    NASA Astrophysics Data System (ADS)

    Labarga, Luis

    2010-11-01

    Water Cherenkov (wC) detectors are extremely powerful apparatuses for scientific research. Nevertheless they lack of neutron tagging capabilities, which translates, mainly, into an inability to identify the anti-matter nature of the reacting incoming anti-neutrino particles. A solution was proposed by R. Beacon and M. Vagins back in 2004: by dissolving in the water a compound with nucleus with very large cross section for neutron capture like the Gadolinium, with a corresponding emission of photons of enough energy to be detected, they can tag thermal neutrons with an efficiency larger than 80%. In this talk we detail the technique and its implications in the measurement capabilities and, as well, the new backgrounds induced. We discuss the improvement on their physics program, also for the case of LAGUNA type detectors. We comment shortly the status of the pioneering R&D program of the Super-Kamiokande Collaboration towards dissolving a Gadolinium compound in its water.

  14. [Gadolinium-based contrast agents for magnetic resonance imaging].

    PubMed

    Carrasco Muñoz, S; Calles Blanco, C; Marcin, Javier; Fernández Álvarez, C; Lafuente Martínez, J

    2014-06-01

    Gadolinium-based contrast agents are increasingly being used in magnetic resonance imaging. These agents can improve the contrast in images and provide information about function and metabolism, increasing both sensitivity and specificity. We describe the gadolinium-based contrast agents that have been approved for clinical use, detailing their main characteristics based on their chemical structure, stability, and safety. In general terms, these compounds are safe. Nevertheless, adverse reactions, the possibility of nephrotoxicity from these compounds, and the possibility of developing nephrogenic systemic fibrosis will be covered in this article. Lastly, the article will discuss the current guidelines, recommendations, and contraindications for their clinical use, including the management of pregnant and breast-feeding patients.

  15. Temperature responsive gadolinium oxide nanoparticles for hyperthermia application

    NASA Astrophysics Data System (ADS)

    Paul, Nibedita; Borah, J. P.; Mohanta, Dambarudhar

    2017-05-01

    In this work we synthesized gadolinium oxide (Gd2O3) nanoparticles by a simple physico-chemical route. X-ray diffractogram (XRD) reveals cubic phase of Gd2O3 with preferred crystallographic orientation along (222) plane. The average crystallite size is found to be ˜ 3.5 nm. High resolution transmission electron microscopy (HRTEM) reveals particle size ˜9nm. UV-Vis spectra reveals two absorption peaks. The peak positioned at ˜285 and 350 nm is attributed to 8S7/2 → 6I7/2 transition of gadolinium (Gd) and the peak oxygen vacancy respectively. Room temperature PL spectra reveals various defect related emission. The prepared nanoparticles are also subjected to hyperthermia (cancer therapy) studies.

  16. About a Gadolinium-doped Water Cherenkov LAGUNA Detector

    SciTech Connect

    Labarga, Luis

    2010-11-24

    Water Cherenkov (wC) detectors are extremely powerful apparatuses for scientific research. Nevertheless they lack of neutron tagging capabilities, which translates, mainly, into an inability to identify the anti-matter nature of the reacting incoming anti-neutrino particles. A solution was proposed by R. Beacon and M. Vagins back in 2004: by dissolving in the water a compound with nucleus with very large cross section for neutron capture like the Gadolinium, with a corresponding emission of photons of enough energy to be detected, they can tag thermal neutrons with an efficiency larger than 80%. In this talk we detail the technique and its implications in the measurement capabilities and, as well, the new backgrounds induced. We discuss the improvement on their physics program, also for the case of LAGUNA type detectors. We comment shortly the status of the pioneering R and D program of the Super-Kamiokande Collaboration towards dissolving a Gadolinium compound in its water.

  17. Gadolinium-enhanced magnetic resonance angiography in brain death

    NASA Astrophysics Data System (ADS)

    Luchtmann, M.; Beuing, O.; Skalej, M.; Kohl, J.; Serowy, S.; Bernarding, J.; Firsching, R.

    2014-01-01

    Confirmatory tests for the diagnosis of brain death in addition to clinical findings may shorten observation time required in some countries and may add certainty to the diagnosis under specific circumstances. The practicability of Gadolinium-enhanced magnetic resonance angiography to confirm cerebral circulatory arrest was assessed after the diagnosis of brain death in 15 patients using a 1.5 Tesla MRI scanner. In all 15 patients extracranial blood flow distal to the external carotid arteries was undisturbed. In 14 patients no contrast medium was noted within intracerebral vessels above the proximal level of the intracerebral arteries. In one patient more distal segments of the anterior and middle cerebral arteries (A3 and M3) were filled with contrast medium. Gadolinium-enhanced MRA may be considered conclusive evidence of cerebral circulatory arrest, when major intracranial vessels fail to fill with contrast medium while extracranial vessels show normal blood flow.

  18. Magnons as a Bose-Einstein Condensate in Nanocrystalline Gadolinium

    SciTech Connect

    Kaul, S. N.; Mathew, S. P.

    2011-06-17

    The recent observation [S. P. Mathew et al., J. Phys. Conf. Ser. 200, 072047 (2010)] of the anomalous softening of spin-wave modes at low temperatures in nanocrystalline gadolinium is interpreted as a Bose-Einstein condensation (BEC) of magnons. A self-consistent calculation, based on the BEC picture, is shown to closely reproduce the observed temperature variations of magnetization and specific heat at constant magnetic fields.

  19. Dressler's syndrome demonstrated by late gadolinium enhancement cardiovascular magnetic resonance

    PubMed Central

    Steadman, Christopher D; Khoo, Jeffrey; Kovac, Jan; McCann, Gerry P

    2009-01-01

    A 49-year old patient presented late with an anterolateral ST-elevation myocardial infarction and was treated with rescue angioplasty to an occluded left anterior descending artery. Her recovery was complicated by low-grade pyrexia and raised inflammatory markers. Cardiovascular magnetic resonance 5 weeks after the acute presentation showed transmural infarction and global late gadolinium enhancement of the pericardium in keeping with Dressler's syndrome. PMID:19627595

  20. Characteristics of Gadolinium Oxide Nanoparticles Using Terahertz Spectroscopy

    SciTech Connect

    Lee, Dongkyu; Maeng, Inhee; Son, Joo-Hiuk; Oh, Seung Jae; Kim, Taekhoon; Cho, Byung Kyu; Lee, Kwangyeol

    2009-04-19

    The penetration property of the terahertz electromagnetic (THz) wave is relevant to its use. We used the THz wave spectroscopy system which easily penetrates some materials that do not contain water, e.g., plastic and ceramics. The system has been developed for several purposes, including measuring the properties of semiconductors and bio-materials, and detecting plastic bombs and ceramic knives at airports. It is also used for medical imaging systems, such as magnetic resonance imaging (MRI), at some research institutes. It can show not only the difference in amplitude, but also the difference of the phase of each point of sample. MRI technology usually uses contrast agents to enhance the quality of the image. Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), made with a heavy metal ion, is commonly used as a clinical MRI contrast agent. Gadolinium oxide (Gd{sub 2}O{sub 3}) nanoparticle is a new contrast agent. It serves to equip the core of each particle with antibodies or ligands. It can freely circulate in blood vessels without amassing in the liver or lungs. This study shows the characteristics of gadolinium oxide nanoparticles to further advance terahertz medical imaging.

  1. Magnetization of 2.6 T in gadolinium thin films

    NASA Astrophysics Data System (ADS)

    Scheunert, G.; Hendren, W. R.; Ward, C.; Bowman, R. M.

    2012-10-01

    There is renewed interest in rare-earth elements and gadolinium in particular for a range of studies in coupling physics and applications. However, it is still apparent that synthesis impacts understanding of the intrinsic magnetic properties of thin gadolinium films, particularly for thicknesses of topicality. We report studies on 50 nm thick nanogranular polycrystalline gadolinium thin films on SiO2 wafers that demonstrate single-crystal like behavior. The maximum in-plane saturation magnetization at 4 K was found to be 4πMS4 K = (2.61 ± 0.26) T with a coercivity of HC4 K = (160 ± 5) Oe. A maximum Curie point of TC = (293 ± 2) K was measured via zero-field-cooled-field-cooled magnetization measurements in close agreement with values reported in bulk single crystals. Our measurements revealed magnetic transitions at T1 = (12 ± 2) K (as deposited samples) and T2 = (22 ± 2) K (depositions on heated substrates) possibly arising from the interaction of paramagnetic face-centred cubic grains with their ferromagnetic hexagonal close-packed counterparts.

  2. Type of MRI contrast, tissue gadolinium, and fibrosis.

    PubMed

    Do, Catherine; Barnes, Jeffrey L; Tan, Chunyan; Wagner, Brent

    2014-10-01

    It has been presupposed that the thermodynamic stability constant (K(therm)) of gadolinium-based MRI chelates relate to the risk of precipitating nephrogenic systemic fibrosis. The present study compared low-K(therm) gadodiamide with high-K(therm) gadoteridol in cultured fibroblasts and rats with uninephrectomies. Gadolinium content was assessed using scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy in paraffin-embedded tissues. In vitro, fibroblasts demonstrated dose-dependent fibronectin generation, transforming growth factor-β production, and expression of activated myofibroblast stress fiber protein α-smooth muscle actin. There were negligible differences with respect to toxicity or proliferation between the two contrast agents. In the rodent model, gadodiamide treatment led to greater skin fibrosis and dermal cellularity than gadoteridol. In the kidney, both contrast agents led to proximal tubule vacuolization and increased fibronectin accumulation. Despite large detectable gadolinium signals in the spleen, skin, muscle, and liver from the gadodiamide-treated group, contrast-induced fibrosis appeared to be limited to the skin and kidney. These findings support the hypothesis that low-K(therm) chelates have a greater propensity to elicit nephrogenic systemic fibrosis and demonstrate that certain tissues are resistant to these effects.

  3. Progress in the use of gadolinium for NCT.

    PubMed

    Cerullo, N; Bufalino, D; Daquino, G

    2009-07-01

    The evaluation of possible improvement in the use of Gd in cancer therapy, in reference to gadolinium in cancer therapy (GdNCT), has been analysed. At first the problem of the gadolinium compounds toxicity was reviewed identifying the Motexafin Gadolinium as the best. Afterwards, the spectrum of IC and Auger electrons was calculated using a special method. Afterwards, this electron source has been used as input of the PENELOPE code and the energy deposit in DNA was well defined. Taking into account that the electron yield and energy distribution are related to the neutron beam spectrum and intensity, the shaping assembly architecture was optimised through computational investigations. Finally the study of GdNCT was performed from two different points of view: macrodosimetry using MCNPX, with calculation of absorbed doses both in tumour and healthy tissues, and microdosimetry using PENELOPE, with the determination of electron RBE through the energy deposit. The equivalent doses were determined combining these two kinds of data, introducing specific figures of merit to be used in treatment planning system (TPS). According to these results, the GdNCT appears to be a fairly possible tumour therapy.

  4. Nephrogenic systemic fibrosis and the role of gadolinium contrast media.

    PubMed

    van der Molen, A J

    2008-08-01

    Nephrogenic system fibrosis is a rare disease affecting patients with severe renal insufficiency or dialysis. Its aetiology is incompletely understood. Evidence is growing that gadolinium contrast media is a major risk factor, whereby risk increases with larger cumulative doses. The role of other risk factors, such as inflammation or electrolyte disturbances, is less clear. All published cases to date received gadodiamide, gadopentetate or gadoversetamide, which are considered to be less stable due to a linear molecular structure. The aetiological significance of stability differences between the non-ionic linear, ionic linear and macrocyclic agents remains to be shown. For prevention, strict indications for MRI in risk patients can be combined with Food and Drug Administration (FDA) or European Medicines Agency (EMEA) guidelines. These recommend checking for renal impairment by history or laboratory tests. The FDA recommends avoidance of all gadolinium contrast media in patients with renal insufficiency grades 4 and 5 (glomerular filtration rate <30 mL/min per 1.73 m(2)) or any grade of acute renal failure in liver transplantation patients or candidates. The EMEA differentiates between agents and advises avoidance of only gadodiamide and gadopentetate in the same patient categories. Other gadolinium contrast media should only be used after careful consideration of risks versus benefits. Post-procedural haemodialysis is only indicated in patients on regular dialysis.

  5. Characteristics of Gadolinium Oxide Nanoparticles Using Terahertz Spectroscopy (abstract)

    NASA Astrophysics Data System (ADS)

    Lee, Dongkyu; Maeng, Inhee; Oh, Seung Jae; Kim, Taekhoon; Cho, Byung Kyu; Lee, Kwangyeol; Son, Joo-Hiuk

    2009-04-01

    The penetration property of the terahertz electromagnetic (THz) wave is relevant to its use. We used the THz wave spectroscopy system which easily penetrates some materials that do not contain water, e.g., plastic and ceramics. The system has been developed for several purposes, including measuring the properties of semiconductors and bio-materials, and detecting plastic bombs and ceramic knives at airports. It is also used for medical imaging systems, such as magnetic resonance imaging (MRI), at some research institutes. It can show not only the difference in amplitude, but also the difference of the phase of each point of sample. MRI technology usually uses contrast agents to enhance the quality of the image. Gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), made with a heavy metal ion, is commonly used as a clinical MRI contrast agent. Gadolinium oxide (Gd2O3) nanoparticle is a new contrast agent. It serves to equip the core of each particle with antibodies or ligands. It can freely circulate in blood vessels without amassing in the liver or lungs. This study shows the characteristics of gadolinium oxide nanoparticles to further advance terahertz medical imaging.

  6. Synergism in insulin-like effects of molybdate plus H2O2 or tungstate plus H2O2 on glucose transport by isolated rat adipocytes.

    PubMed

    Goto, Y; Kida, K; Ikeuchi, M; Kaino, Y; Matsuda, H

    1992-07-07

    The effect of molybdate, tungstate, molybdate plus H2O2 or tungstate plus H2O2 on 3-O-methylglucose (3-O-MG) uptake was studied in isolated rat adipocytes to investigate whether these agents possess an insulin-like action. High concentrations (10-30 mM) of molybdate or tungstate significantly stimulated the uptake of 3-O-MG while 1 mM of the metaloxides did not. The combination of 1 mM molybdate and 1 mM H2O2, or 1 mM tungstate and 1 mM H2O2 induced striking stimulation of the uptake of 3-O-MG in a synergistic manner, whereas 1 mM H2O2 alone showed only a small effect. The effect of metaloxides plus H2O2 (1 mM) and the effect of insulin (20 nM) were not additive, and both effects were ATP or energy dependent based on experiments using KCN. These results indicate that a weak insulin-like effect of molybdate or tungstate is potentiated synergistically with H2O2, presumably by producing peroxocompounds. Based on the present findings, these new agents may be useful for investigating the mechanism of insulin action and may indicate a new class of drugs for diabetes mellitus.

  7. Sodium tungstate on some biochemical parameters of the parotid salivary gland of streptozotocin-induced diabetic rats: a short-term study.

    PubMed

    Leite, Mariana Ferreira; Nicolau, José

    2009-02-01

    Several studies have shown the antidiabetic properties of sodium tungstate. In this study, we evaluated some biochemical parameters of the parotid salivary gland of streptozotocin-induced diabetic rats treated with sodium tungstate solution (2 mg/ml). The studied groups were: untreated control (UC), treated control (TC), untreated diabetic (UD), and treated diabetic (TD). After 2 and 6 weeks of treatment, parotid gland was removed and total protein and sialic acid (free and total) concentration and amylase and peroxidase activities were determined. Data were compared by variance analysis and Tukey test (p < 0.05). The sodium tungstate treatment modestly decreased the glycemia of streptozotocin-induced diabetic rats. At week 2 of the study, parotid gland of diabetic rats presented a reduction of total protein concentration (55%) and an increase of amylase (120%) and peroxidase (160%) activities, free (150%) and total (170%) sialic acid concentration. No alteration in the evaluated parameters at week 6 of the study was observed. Sodium tungstate presented no significant effect in parotid gland. Our results suggest that diabetes causes initial modification in biochemical composition of parotid. However, this gland showed a recovery capacity after 6 week of the experimental time. Sodium tungstate has no effect in peripheral tissues, such as salivary glands.

  8. [CT contrast administration of iodine, gadolinium and ytterbium. In-vitro studies and animal experiments].

    PubMed

    Zwicker, C; Langer, M; Urich, V; Felix, R

    1993-03-01

    The absorption of the elements iodine, gadolinium and ytterbium in various dilutions was studied in relation to CT. Regression analysis and specific CT density measurements showed that absorption decreases from gadolinium to ytterbium and iodine. These results were confirmed by experiments using ten dogs. Boli of 0.5 molar gadolinium used for angio-CT without table movement showed the largest increase in density in the aorta and liver with an average of 190HU and 21HU respectively compared with iodine which gave 157HU and 12HU respectively. The animal experimental studies suggest that gadolinium and ytterbium are suitable contrast media for dynamic CT investigations.

  9. Gadolinium-based contrast agents: did we miss something in the last 25 years?

    PubMed

    Beomonte Zobel, Bruno; Quattrocchi, Carlo Cosimo; Errante, Yuri; Grasso, Rosario Francesco

    2016-06-01

    In the last 24 months, several clinical and experimental studies, suggested first and demonstrated later, a progressive concentration of Gadolinium in the brain of normal renal function patients, following repeated injections of some of the commercially approved Gadolinium-Based Contrast Agents. Although, till now, Gadolinium brain deposits have not been associated to any kind of neurological signs or symptoms, they oblige the radiology community to modify the actual approach in using Gadolinium contrast media in daily practice, to reduce unknown possible risks for patients.

  10. Combination of boron and gadolinium compounds for neutron capture therapy. An in vitro study.

    PubMed

    Matsumura, A; Zhang, T; Nakai, K; Endo, K; Kumada, H; Yamamoto, T; Yoshida, F; Sakurai, Y; Yamamoto, K; Nose, T

    2005-03-01

    In neutron capture therapy, the therapeutic effect of the boron compound is based on alpha particles produced by the B(n, alpha) reaction while with the gadolinium compound the main radiation effect is from gamma rays derived from the Gd(n, gamma) reaction. The uptake and distribution within the tumor may be different among these compounds. Thus, the combination of the boron and gadolinium compounds may be beneficial for enhancing the radiation dose to the tumor. Chinese hamster fibroblast V79 cells were used. For the neutron targeting compounds, 10B (BSH) at 0, 5, 10, and 15 ppm, and 157Gd (Gd-BOPTA) at 0, 800, 1600, 2400, 3200, and 4800 ppm, were combined. The neutron irradiation was performed with thermal neutrons for 30 min. (neutron flux: 0.84 x 10(8) n/cm2/s in free air). The combination of the boron and gadolinium compounds showed an additive effect when the gadolinium concentration was lower than 1600 ppm. This additive effect decreased as a function of gadolinium concentration at 2400 ppm and resulted in no additive effect at more than 3200 ppm of gadolinium. In conclusion, the combination of the boron and gadolinium compounds can enhance the therapeutic effect with an optimum concentration ratio. When the gadolinium concentration is too high, it may weaken the boron neutron capture reaction due to the high cross-section of gadolinium compound against neutrons.

  11. Thermodynamic properties of gadolinium in Ga-Sn and Ga-Zn eutectic based alloys

    NASA Astrophysics Data System (ADS)

    Maltsev, Dmitry S.; Volkovich, Vladimir A.; Yamshchikov, Leonid F.; Chukin, Andrey V.

    2016-09-01

    Thermodynamic properties of gadolinium in Ga-Sn and Ga-Zn eutectic based alloys were studied. Temperature dependences of gadolinium activity in the studied alloys were determined at 573-1073 K employing the EMF method. Solubility of gadolinium in the Ga-Sn and Ga-Zn alloys was measured at 462-1073 K using IMCs sedimentation method. Activity coefficients as well as partial and excess thermodynamic functions of gadolinium in the studied alloys were calculated on the basis of the obtained experimental data.

  12. Thermal stress and end-bulging in monoclinic crystals: the case study of double tungstates.

    PubMed

    Yumashev, Konstantin; Loiko, Pavel

    2017-05-01

    An analytical description of the thermal stress and end-bulging component of thermal lensing is presented for monoclinic laser crystals, taking into account the anisotropy of their optical, thermal, and elastic properties for the first time, to the best of our knowledge. The geometry of longitudinal diode-pumping (plane stress approximation) is considered. The developed approach is applied to the monoclinic double tungstates (MDTs), Yb:KGW, Yb:KYW, and Yb:KLuW, yielding values of normal and shear stresses, tensile stress, and the end-bulging term. We show that for low-symmetry crystals, end-bulging is responsible for the astigmatism of the thermal lens. The geometry of this astigmatism is explained in terms of the principal meridional planes. We show that the crystal cut of the MDTs along the optical indicatrix axis Ng (propagation direction) provides low thermal stress and a purely positive and weakly astigmatic thermal lens, which is a key condition for power scaling and diffraction-limited laser output.

  13. Two-photon interband absorption coefficients in tungstate and molybdate crystals

    NASA Astrophysics Data System (ADS)

    Lukanin, V. I.; Karasik, A. Ya.

    2015-02-01

    Two-photon absorption (TPA) coefficients were measured in tungstate and molybdate crystals - BaWO4, KGW, CaMoO4, BaMoO4, CaWO4, PbWO4 and ZnWO4 upon different orientations of excitation polarization with respect to the crystallographic axes. Trains of 25 ps pulses with variable radiation intensities of third (349 nm) harmonics of passively mode-locked 1047 nm Nd:YLF laser were used for interband two-photon excitation of the crystals. It was suggested that in the case, when 349 nm radiation pumping energy exceeds the bandgap width (hν>Eg), the nonlinear excitation process can be considered as two-step absorption. The interband two-photon absorption in all the studied crystals induces the following one-photon absorption from the exited states, which affects the nonlinear process dynamics and leads to a hysteresis in the dependence of the transmission on the excitation intensity. This fact was taken into account under analysis of the experimental dependences of the reciprocal transmission on the excitation intensity. Laser excitation in the transparency region of the crystals caused stimulated Raman scattering (SRS) not for all the crystals studied. The measured nonlinear coefficients allowed us to explain the suppression of SRS in crystals as a result of competition between the SRS and TPA.

  14. Photo- and electroluminescence properties of lanthanide tungstate-doped porous anodic aluminum oxide

    NASA Astrophysics Data System (ADS)

    Staninski, Krzysztof; Piskuła, Zbigniew; Kaczmarek, Małgorzata

    2017-02-01

    A new cathode material for the potential use in light-emitting devices, based on porous anodic alumina (PAA), aluminum and ITO layers has been synthesized. Porous alumina samples with ordered pore arrays were prepared electrochemically from high purity Al sheet in H2SO4 and H3PO4. To be able to apply the matrix obtained in the electroluminescence cell, the thickness of the barrier layer of aluminum oxide was decreased by slow reduction of the anodization voltage to zero. The luminescence and electroluminescence (EL) properties of the Al2O3 matrix admixtured with Eu3+ and Tb3+ ions as well as europium and terbium tungstates, were determined. The particles of inorganic luminophore were synthesized on the walls of the matrix cylindrical nanopores in the two-step process of immersion in solutions of TbCl3 or EuCl3 and Na2WO4. The effect of the nanopores diameter and the thickness of the porous Al2O3 layer on the intensity and relative yield of electroluminescence was analyzed, the best results were obtained for 80-90 μm PAA layers with 140 nm nanopores.

  15. Investigation of the kinetics of reduction of nickel tungstate by hydrogen

    SciTech Connect

    Sridhar, S. . Dept. of Materials Science and Engineering); Du Sichen; Seetharaman, S. . Dept. of Metallurgy)

    1994-06-01

    In the present work, the kinetics of reduction of nickel tungstate, NiWO[sub 4], by hydrogen was investigated by a thermogravimetric method in the temperature range 891 to 1,141 K. The experiments were conducted under both isothermal and nonisothermal conditions. The products were examined by X-ray diffraction analysis. The results indicate that the reduction reaction proceeds in two steps; first, reduction of NiWO[sub 4] to nickel as well as WO[sub 2] and then WO[sub 2] to tungsten. From the isothermal experiments, the activation energies of the two reaction steps were calculated to be 95.3 [+-] 4.9 and 80.8 [+-] 6.4 kJ [center dot] mol[sup [minus]1], respectively. The activation energy value obtained from nonisothermal experiments for the first step is in agreement with the isothermal experiments. The values are compared with the activation energies reported in other literature for the individual oxides.

  16. Zirconium tungstate/epoxy nanocomposites: effect of nanoparticle morphology and negative thermal expansivity.

    PubMed

    Wu, Hongchao; Rogalski, Mark; Kessler, Michael R

    2013-10-09

    The ability to tailor the coefficient of thermal expansion (CTE) of a polymer is essential for mitigating thermal residual stress and reducing microcracks caused by CTE mismatch of different components in electronic applications. This work studies the effect of morphology and thermal expansivity of zirconium tungstate nanoparticles on the rheological, thermo-mechanical, dynamic-mechanical, and dielectric properties of ZrW2O8/epoxy nanocomposites. Three types of ZrW2O8 nanoparticles were synthesized under different hydrothermal conditions and their distinct properties were characterized, including morphology, particle size, aspect ratio, surface area, and CTE. Nanoparticles with a smaller particle size and larger surface area led to a more significant reduction in gel-time and glass transition temperature of the epoxy nanocomposites, while a higher initial viscosity and significant shear thinning behavior was found in prepolymer suspensions containing ZrW2O8 with larger particle sizes and aspect ratios. The thermo- and dynamic-mechanical properties of epoxy-based nanocomposites improved with increasing loadings of the three types of ZrW2O8 nanoparticles. In addition, the introduced ZrW2O8 nanoparticles did not negatively affect the dielectric constant or the breakdown strength of the epoxy resin, suggesting potential applications of ZrW2O8/epoxy nanocomposites in the microelectronic insulation industry.

  17. Efficient photodegradation of methylthioninium chloride dye in aqueous using barium tungstate nanoparticles

    NASA Astrophysics Data System (ADS)

    AlShehri, Saad M.; Ahmed, Jahangeer; Ahamad, Tansir; Almaswari, Basheer M.; Khan, Aslam

    2017-08-01

    BaWO4 nanoparticles were successfully used as the photocatalysts in the degradation of methylthioninium chloride (MTC) dye at different pH levels of aqueous solution. Pure phase of barium tungstate (BaWO4) nanoparticles was synthesized by modified molten salt process at 500 °C for 6 h. Structural and morphological characterizations of BaWO4 nanoparticles (average particle size of 40 nm) were studied in details using powder x-ray diffraction (XRD), FTIR, Raman, energy-dispersive, electron microscopic, and x-ray photoelectron spectroscopy (XPS) techniques. Direct band gap energy of BaWO4 nanoparticles was found to be 3.06 eV from the UV-visible absorption spectroscopy followed by Tauc's model. Photocatalytic properties of the nanoparticles were also investigated systematically for the degradation of MTC dye solution in various mediums. BaWO4 nanoparticles claim the significant enhancement of the photocatalytic degradation of aqueous MTC dye to non-hazardous inorganic constitutes under alkaline, neutral, and acidic mediums. [Figure not available: see fulltext.

  18. Efficient photo-catalytic degradation of malachite green using nickel tungstate material as photo-catalyst.

    PubMed

    Helaïli, N; Boudjamaa, A; Kebir, M; Bachari, K

    2017-03-01

    The present study focused on the evaluation of photo-catalytic and photo-electrochemical properties of the photo-catalyst based on nickel tungstate material prepared by a nitrate method through the degradation of malachite green (MG) dye's. The effect of catalyst loading and dye concentration was examined. Physico-chemical, optical, electrical, electrochemical, and photo-electrochemical properties of the prepared material were analyzed by X-ray diffraction (XRD), fourier transform-infrared spectroscopy (FTIR), BET analysis, optical reflectance diffuse (DR), scanning electron microscopy (SEM/EDX), electrical conductivity, cyclic voltammetry (CV), current intensity, mott-shottky, and nyquist. XRD revealed the formation of monoclinic structure with a small particle size. BET surface area of the sample was around 10 m(2)/g. The results show that the degradation of MG was more than 80%, achieved after 3 h of irradiation at pH 4.6 and with a catalyst loading of 75 mg. Also, it was found that the dye photo-degradation obeyed the pseudo-first order kinetic via Langmuir Hinshelwood model.

  19. Photocatalytic generation of syngas using combustion-synthesized silver bismuth tungstate.

    PubMed

    de Tacconi, Norma R; Timmaji, Hari Krishna; Chanmanee, Wilaiwan; Huda, Muhammad N; Sarker, Pranab; Janáky, Csaba; Rajeshwar, Krishnan

    2012-08-27

    Silver bismuth tungstate (AgBiW(2)O(8)) nanoparticles were prepared for the first time by solution combustion synthesis by using the corresponding metal nitrates as the precursor and urea as the fuel. These nanoparticles were subsequently modified with Pt catalyst islands using a photocatalytic procedure and used for the photogeneration of syngas (CO+H(2)). Formic acid was used for this purpose for the in situ generation of CO(2) and its subsequent reduction to CO. In the absence of Pt modification, H(2) was not obtained in the gas products evolved. These results were compared with those obtained with acetic acid in place of formic acid. The combustion process was simulated by thermogravimetry and the synthesized powder was characterized using transmission electron microscopy, diffuse reflectance UV/Vis spectroscopy, X-ray diffraction, surface area measurements, and X-ray photoelectron spectroscopy. Tauc plots derived from the diffuse reflectance data yielded an optical band gap of 2.74 eV. The photocatalytic activity of these nanoparticles was superior to a sample prepared by solid-state synthesis. Mechanistic aspects are finally presented, as are structural models and electronic calculations, using density functional theory (DFT). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Tungstate-ferrates of some alkali and alkaline-earth metals

    SciTech Connect

    Gruba, A.I.; Danileiko, L.A.; Moroz, Ya.A.; Zyats, M.N.

    1988-02-01

    Tungstate-ferrates of some alkali and alkaline-earth metals with the ratio Fe:W = 2:11, the iron ions in which are found in two types of coordination, tetrahedral and octahedral, were synthesized. The similarity of the IR spectra of the compounds obtained and known compounds with the anion structure of the Keggin type with the composition M/sub X/(XZW/sub 11/O/sub 40/H/sub m/) x nH/sub 2/O indicates that their heteropolyanions are isostructural. The thermal stability of the compounds studied and the structure of the products of thermolysis depend on the charge and radius of the extrasphere cation. When the ratio of the radii of the extrasphere cation of the alkali or alkaline-earth metal to the radius of the ion of the central 3d element, appearing in the coordination sphere of the heteropolytungstates, exceeds 1.6, the most likely products of thermolysis of heteropolycompounds are the compounds of the pyrochlore family and tungsten bronzes.

  1. Subchronic Oral Toxicity of Sodium Tungstate in Sprague-Dawley Rats.

    PubMed

    McCain, Wilfred C; Crouse, Lee C B; Bazar, Mathew A; Roszell, Laurie E; Leach, Glenn J; Middleton, John R; Reddy, Gunda

    2015-01-01

    The subchronic toxicity of sodium tungstate dihydrate aqueous solution in male and female Sprague-Dawley rats was evaluated by daily oral gavage of 0, 10, 75, 125, or 200 mg/kg/d for 90 days. Measured parameters included food consumption, body weight measurements, hematology, clinical chemistry, and histopathological changes. There was a significant decrease in food consumption and body weight gain in males at 200 mg/kg/d from days 77 to 90; however, there was no effect in food consumption and body weights in females. There were no changes in the hematological and clinical parameters studied. Histopathological changes were seen in kidney of male and female and epididymis of male rats. Histopathological changes were observed in the kidneys of male and female rats dosed at 125 or 200 mg/k/d consisting of mild to severe cortical tubule basophilia in 2 high-dose groups. Histological changes in epididymides included intraluminal hypospermia with cell debris in the 200 mg/kg/d dosed male rats. Histopathological changes were observed in the glandular stomach including inflammation and metaplasia in the high-dose groups (125 or 200 mg/kg/d) of both sexes of rats. Based on histopathology effects seen in the kidneys, the lowest observable adverse effect level was 125 mg/kg/d and the no observable adverse effect level was 75 mg/kg/d in both sexes of rats for oral subchronic toxicity.

  2. Synthesis and characterization of silver tungstate/iron phthalocyanine nanocomposite for electronic applications

    NASA Astrophysics Data System (ADS)

    Sreedevi, Aikkara; Priyanka, Karathan Parakkandi; Babitha, Kurup Kuniyil; Sankararaman, Sankaranarayana Iyer; Thomas, Varghese

    2017-06-01

    Silver tungstate/iron phthalocyanine nanocomposite (Ag2WO4/FePc) was prepared by simple solvent evaporation method. Thermodynamic stability of the synthesized nanocomposite was studied by thermogravimetric analysis. The nanocomposite was structurally characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. The results confirm the formation of Ag2WO4/FePc nanocomposite. The size and morphology of the prepared nanocomposite were analyzed by scanning electron microscopy and high-resolution transmission electron microscopy. The optical properties were analyzed by ultraviolet-visible and photoluminescence spectroscopic techniques. UV-visible absorption studies indicate that Ag2WO4/FePc nanocomposite has extended visible absorption in the wavelength range 662 to 782 nm. The nanocomposite shows high emission intensity and greenish-blue emission when excited with near-ultraviolet light. The resistivity of the sample was measured at different temperatures. The dielectric constant, dielectric loss and AC conductivity values were measured in the frequency range 100 Hz-20 MHz. The results obtained from thermal, structural, optical and electrical characterization suggests that the synthesized Ag2WO4/FePc nanocomposite can be used as a potential material for varied optoelectronic and solid state applications. The present study constitutes the first report for the synthesis and characterization of Ag2WO4/FePc nanocomposite.

  3. Investigation of oxygen vacancy and photoluminescence in calcium tungstate nanophosphors with different particle sizes

    SciTech Connect

    Li, Yezhou; Wang, Zhaofeng; Sun, Luyi; Wang, Zhilong; Wang, Shiqin; Liu, Xiong; Wang, Yuhua

    2014-02-01

    Highlights: • CaWO{sub 4} nanophosphors with different particle sizes were prepared by hydrothermal processes through controlling the concentration of surfactant. • Green emission band of oxygen vacancy in CaWO{sub 4} nanophosphor was clearly observed upon the irradiation of 350 nm excitation. • The concentration of oxygen vacancy in CaWO{sub 4} nanophosphor could be increased by reducing its size. - Abstract: Calcium tungstate (CaWO{sub 4}) nanophosphors with the particle sizes from 35 to 90 nm were synthesized by a hydrothermal process through exactly controlling the pre-treated conditions. The influence of particle size on oxygen vacancy and photoluminescence properties in CaWO{sub 4} nanophosphors was investigated and discussed. The crystal structure of the CaWO{sub 4} nanophosphors presented a certain level of distortion due to the high concentration of oxygen vacancy. Under 350 nm excitation, a clear green emission aroused by oxygen vacancy was observed. The possible luminescence processes for the matrix and oxygen vacancy were proposed. The luminescence spectra of the nanophosphors revealed that the emission and absorption intensity aroused by oxygen vacancy were both enhanced when the size is decreased. On the basis of the above results, the essential relationship between particle size and oxygen vacancy in CaWO{sub 4} nanophosphors was concluded that the concentration of oxygen vacancy could be increased by reducing its size, which was further confirmed by decay lifetimes.

  4. Monitoring and Correcting for Response Changes in the CMS Lead-tungstate Electromagnetic Calorimeter

    NASA Astrophysics Data System (ADS)

    Ferri, Federico

    2012-12-01

    The CMS Electromagnetic Calorimeter (ECAL) comprises 75848 lead-tungstate scintillating crystals. Changes in the ECAL response, due to crystal radiation damage or changes in photo-detector output, are monitored in real time with a sophisticated system of lasers to allow corrections to the energy measurements to be calculated and used. The excellent intrinsic resolution of the CMS ECAL requires the monitoring system itself to be calibrated to a high precision and its stability to be controlled and understood. The components of the CMS ECAL monitoring system, and how it has evolved to include modern solid-state lasers, are described. Several physics channels are exploited to normalise the ECAL response to the changes measured by the monitoring system. These include low energy diphoton resonances, electrons from W and Z decays (using shower energy versus track momentum measurements), and the azimuthal symmetry of low energy deposits in minimum bias events. This paper describes how the monitoring system is operated, how the corrections are obtained, and the resulting ECAL performance.

  5. Numerical simulation of photonic-crystal tellurite-tungstate glass fibres used in parametric fibre devices

    SciTech Connect

    Sokolov, V O; Plotnichenko, V G; Nazaryants, V O; Dianov, Evgenii M

    2006-01-31

    Using the MIT Photonic-Bands Package to calculate fully vectorial definite-mode eigenmodes of Maxwell's equations with periodic boundary conditions in a plane-wave basis, light propagation is simulated in fibres formed by point defects in two-dimensional periodic lattices of cylindrical holes in a glass or of glass tubes. The holes and gaps between tubes are assumed filled with air. Single-site hexagonal and square lattices are considered, which were most often studied both theoretically and experimentally and are used to fabricate silica photonic-crystal fibres. As a defect, a single vacancy is studied - the absent lattice site (one hole in a glass or one of the tubes are filled with the same glass) and a similar vacancy with nearest neighbours representing holes of a larger diameter. The obtained solutions are analysed by the method of effective mode area. The dependences of the effective refractive index and dispersion of the fundamental mode on the geometrical parameters of a fibre are found. The calculations are performed for tellurite-tungstate 80TeO{sub 2}-20WO{sub 3} glass fibres taking into account the frequency dispersion of the refractive index. (optical fibres)

  6. ROLE OF TUNGSTEN IN THE AQUEOUS PHASE HYDRODEOXYGENATION OF ETHYLENE GLYCOL ON TUNGSTATED ZIRCONIA SUPPORTED PALLADIUM

    SciTech Connect

    Marin-Flores, Oscar G.; Karim, Ayman M.; Wang, Yong

    2014-11-15

    The focus of the present work was specifically on the elucidation of the role played by tungsten on the catalytic activity and selectivity of tungstated zirconia supported palladium (Pd-mWZ) for the aqueous phase hydrodeoxygenation (APHDO) of ethylene glycol (EG). Zirconia supported palladium (Pd-mZ) was used as reference. The catalysts were prepared via incipient wet impregnation and characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR), CO pulse chemisorption, CO-DRIFTS, ammonia temperature-programmed desorption (NH3-TPD) and pyridine adsorption. The presence of W results in larger Pd particles on supported Pd catalysts, i.e., 0.9 and 6.1 nm Pd particles are for Pd-mZ and Pd-mWZ, respectively. For comparison purposes, the activity of the catalytic materials used in this work was obtained using a well-defined set of operating conditions. The catalytic activity measurements show that the overall intrinsic activity of Pd particles on mWZ is 1.9 times higher than on mZ. APHDO process appears to be highly favored on Pd-mWZ whereas Pd-mZ exhibits a higher selectivity for reforming. This difference in terms of selectivity seems to be related to the high concentration of Brønsted acid sites and electron-deficient Pd species present on Pd-mWZ.

  7. Lattice dynamics study of scheelite tungstates under high pressure I. BaWO4

    NASA Astrophysics Data System (ADS)

    Manjón, F. J.; Errandonea, D.; Garro, N.; Pellicer-Porres, J.; Rodríguez-Hernández, P.; Radescu, S.; López-Solano, J.; Mujica, A.; Muñoz, A.

    2006-10-01

    Room-temperature Raman scattering has been measured in barium tungstate (BaWO4) up to 16GPa . We report the pressure dependence of all the Raman active first-order phonons of the tetragonal scheelite phase ( BaWO4-I , space group I41/a ), which is stable at normal conditions. As pressure increases the Raman spectrum undergoes significant changes around 6.9GPa due to the onset of the structural phase transition to the monoclinic BaWO4-II phase (space group P21/n ). This transition is only completed above 9.5GPa . A further change in the spectrum is observed at 7.5GPa related to a scheelite-to-fergusonite transition. The scheelite, BaWO4-II , and fergusonite phases coexist up to 9.0GPa due to the sluggishness of the I→II phase transition. Further to the experimental study, we have performed ab initio lattice dynamics calculations that have greatly helped us in assigning and discussing the pressure behavior of the observed Raman modes of the three phases.

  8. Lattice dynamics study of scheelite tungstates under high pressure II. PbWO4

    NASA Astrophysics Data System (ADS)

    Manjon, F. J.; Errandonea, D.; Garro, N.; Pellicer-Porres, J.; López-Solano, J.; Rodríguez-Hernández, P.; Radescu, S.; Mujica, A.; Muñoz, A.

    2006-10-01

    Room-temperature Raman scattering has been measured in lead tungstate up to 17GPa . We report the pressure dependence of all the Raman modes of the tetragonal scheelite phase ( PbWO4-I or stolzite, space group I41/a ), which is stable at ambient conditions. Upon compression the Raman spectrum undergoes significant changes around 6.2GPa due to the onset of a partial structural phase transition to the monoclinic PbWO4-III phase (space group P21/n ). Further changes in the spectrum occur at 7.9GPa , related to a scheelite-to-fergusonite transition. This transition is observed due to the sluggishness and kinetic hindrance of the I→III transition. Consequently, we found the coexistence of the scheelite, PbWO4-III , and fergusonite phases from 7.9to9GPa , and of the last two phases up to 14.6GPa . We have performed ab initio lattice-dynamics calculations, which have greatly helped us in assigning the Raman modes of the three phases and discussing their pressure dependence. The Raman modes of the free WO4 molecule are discussed.

  9. Simple and rapid determination of hydrogen peroxide using phosphine-based fluorescent reagents with sodium tungstate dihydrate.

    PubMed

    Onoda, Maki; Uchiyama, Takefumi; Mawatari, Ken-Ichi; Kaneko, Kiyoko; Nakagomi, Kazuya

    2006-06-01

    A simple batch method for the fluorometric determination of hydrogen peroxide using phosphine-based fluorescent reagents has been developed. A rapid, mild and selective derivatization reaction was achieved by adding sodium tungstate dihydrate to the reaction mixture of hydrogen peroxide and a phosphine-based fluorescent reagent. When 4-diphenylphosphino-7-methylthio-2,1,3-benzoxadiazole was used as a reagent, the derivatization reaction was completed after 2 min at room temperature. The calibration curve was linear between 12.5 and 500 ng hydrogen peroxide in a 10 microL sample solution. This method is accurate and has potential for on-line applications.

  10. Preparation, characterization, dielectric properties and diffusion studies of styrene butadiene rubber (SBR)/manganous tungstate (MnWO4) nanocomposites

    NASA Astrophysics Data System (ADS)

    Jasna, V. C.; Ramesan, M. T.

    2017-06-01

    Nanocomposites based on SBR with different content of manganous tungstate nanoparticles were prepared and characterized by FTIR, UV-visible spectroscopy, XRD, SEM, TGA, DSC and impedance analysis. The interaction between nanoparticles and the elastomer was clear from the shift in peaks of UV and FTIR. XRD and SEM analysis showed the uniform arrangement of nanoparticles in SBR matrix. Glass transition temperature, thermal stability and dielectric properties of composites were enhanced by the addition of nanoparticles. Sorption studies of nanocomposites were done in aromatic solvents at different temperature. Sorption data obtained were used to estimate the thermodynamic properties.

  11. Acrylonitrile butadiene rubber (NBR)/manganous tungstate (MnWO4) nanocomposites: Characterization, mechanical and electrical properties

    NASA Astrophysics Data System (ADS)

    Ramesan, M. T.; Abdu Raheem V., P.; Jayakrishnan, P.; Pradyumnan, P. P.

    2014-10-01

    Nanocomposites of NBR with manganous-tungstate nanoparticles were prepared through vulcanization process. The extent of interaction of nanoparticles with the polymer was studied by FTIR, SEM, XRD, TGA and AC conductivity. FTIR and XRD ascertain the interaction of NBR with MnWO4 nanoparticles. SEM analysis established that the nanopartilces were well dispersed in the macromolecular chain of NBR. The mechanical properties of the nanocomposites were studied as a function of filler loading. The nanocomposites exhibited enhanced thermal stability as seen in TGA. Conductivity and dielectric properties of nanocomposites increase with increase in concentration of MnWO4 nanoparticles (7phr) and thereafter the value decreases.

  12. Cation–cation interactions and cation exchange in a series of isostructural framework uranyl tungstates

    SciTech Connect

    Balboni, Enrica; Burns, Peter C.

    2014-05-01

    treatments. The framework of these compounds is robust to cation exchange and heat. (yellow polyhedra=uranium pentagonal bipyramids; blue polyhedra=tungsten octahedral, purple balls=K; yellow balls=Na; grey balls=Tl). - Highlights: • Five isostructural uranyl tungstates compounds were synthesized hydrothermally. • The structures consist of a chains of uranium and tungstate polyhedral. • Chains are connected into a framework by cation–cation interactions. • Cation exchange does not alter the structural integrity of the compounds. • Cation exchange was successful at room temperature and mild hydrothermal conditions.

  13. Sarcoplasmic reticulum calcium ATPase interactions with decaniobate, decavanadate, vanadate, tungstate and molybdate.

    PubMed

    Fraqueza, Gil; Ohlin, C André; Casey, William H; Aureliano, Manuel

    2012-02-01

    Over the last few decades there has been increasing interest in oxometalate and polyoxometalate applications to medicine and pharmacology. This interest arose, at least in part, due to the properties of these classes of compounds as anti-cancer, anti-diabetic agents, and also for treatment of neurodegenerative diseases, among others. However, our understanding of the mechanism of action would be improved if biological models could be used to clarify potential toxicological effects in main cellular processes. Sarcoplasmic reticulum (SR) vesicles, containing a large amount of Ca(2+)-ATPase, an enzyme that accumulates calcium by active transport using ATP, have been suggested as a useful model to study the effects of oxometalates on calcium homeostasis. In the present article, it is shown that decavanadate, decaniobate, vanadate, tungstate and molybdate, all inhibited SR Ca(2+)-ATPase, with the following IC(50) values: 15, 35, 50, 400 μM and 45 mM, respectively. Decaniobate (Nb(10)), is the strongest P-type enzyme inhibitor, after decavanadate (V(10)). Atomic-absorption spectroscopy (AAS) analysis, indicates that decavanadate binds to the protein with a 1:1 decavanadate:Ca(2+)-ATPase stoichiometry. Furthermore, V(10) binds with similar extension to all the protein conformations, which occur during calcium translocation by active transport, namely E1, E1P, E2 and E2P, as analysed by AAS. In contrast, it was confirmed that the binding of monomeric vanadate (H(2)VO(4)(2-); V(1)) to the calcium pump is favoured only for the E2 and E2P conformations of the ATPase, whereas no significant amount of vanadate is bound to the E1 and E1P conformations. Scatchard plot analysis, confirmed a 1:1 ratio for decavanadate-Ca(2+)-ATPase, with a dissociation constant, k(d) of 1 μM(-1). The interaction of decavanadate V(10)O(28)(6-) (V(10)) with Ca(2+)-ATPase is prevented by the isostructural and isoelectronic decaniobate Nb(10)O(28)(6-) (Nb(10)), whereas no significant effects were

  14. Use of Gadolinium as a Primary Criticality Control in Disposing Waste Containing Plutonium at SRS

    SciTech Connect

    Andrew, Vincent

    2005-01-04

    Use of gadolinium as a neutron poison has been proposed for disposing of several metric tons of excess plutonium at the Savannah River Site (SRS). The plutonium will first be dissolved in nitric acid in small batches. Gadolinium nitrate will then be added to the plutonium nitrate solution. The Gd-poisoned plutonium solution will be neutralized and transferred to large under-ground tanks. The pH of small batches of neutralized plutonium solution will be adjusted prior to addition of the glass frit for eventual production as glass logs. The use of gadolinium as the neutron poison would minimize the number of glass logs generated from this disposition. The primary criticality safety concerns regarding the disposal process are: (1) maintaining neutron moderation under all processing conditions since gadolinium has a very large absorption cross section for thermal neutrons, (2) characteristics of plutonium and gadolinium precipitation during the neutralization process, (3) mixing characteristics of the precipitate to ensure that plutonium would remain homogeneously mixed with gadolinium, and (4) potential separation of plutonium and gadolinium during nitric and formic acids addition. A number of experiments were conducted at the Savannah River National Laboratory to study the behavior of plutonium and gadolinium at various stages of the disposition process.

  15. Dual-Energy X-Radiography With Gadolinium Filter

    NASA Technical Reports Server (NTRS)

    Rutt, Brian

    1987-01-01

    Image resolution increased, and cost reduced. Proposed dual-energy x-ray imaging system, continuous bremsstrahlung spectrum from x-ray tube filtered by foil of nonradioactive gadolinium or another rare-earth metal to form two-peaked energy spectrum. After passing through patient or object under examination, filtered radiation detected by array of energy-discriminating, photon-counting detectors. Detector outputs processed to form x-ray image for each peak and possibly enhanced image based on data taken at both peaks.

  16. Gadolinium-based nanoparticles for theranostic MRI-radiosensitization.

    PubMed

    Lux, François; Sancey, Lucie; Bianchi, Andrea; Crémillieux, Yannick; Roux, Stéphane; Tillement, Olivier

    2015-01-01

    A rapid development of gadolinium-based nanoparticles is observed due to their attractive properties as MRI-positive contrast agents. Indeed, they display high relaxivity, adapted biodistribution and passive uptake in the tumor thanks to enhanced permeability and retention effect. In addition to these imaging properties, it has been recently shown that they can act as effective radiosensitizers under different types of irradiation (radiotherapy, neutron therapy or hadron therapy). These new therapeutic modalities pave the way to therapy guided by imaging and to personalized medicine.

  17. Magnetoresistance of polycrystalline gadolinium with varying grain size

    SciTech Connect

    Chakravorty, Manotosh Raychaudhuri, A. K.

    2015-01-21

    In this paper, we report a study of evolution of low field magnetoresistance (MR) of Gadolinium as the grain size in the sample is changed from few microns (∼4 μm) to the nanoscopic regime (∼35 nm). The low field MR has a clear effect on varying grain size. In large grain sample (few μm), the magnetic domains are controlled by local anisotropy field determined mainly by the magnetocrystalline anisotropy. The low field MR clearly reflects the temperature dependence of the magnetocrystalline anisotropy. For decreasing gain size, the contribution of spin disorder at the grain boundary increases and enhances the local anisotropy field.

  18. Visualization of denervated muscle by gadolinium-enhanced MRI.

    PubMed

    Bendszus, M; Koltzenburg, M

    2001-11-13

    Thirty patients presenting with foot drop due to lesions of the peroneal nerve or L5 spinal root were investigated with gadolinium (Gd)-enhanced MRI of the lower leg. Significant enhancement was only seen in the denervated muscles in a pattern appropriate for the distribution of the nerve or root. In a rat model, identical changes in the denervated muscle were reproduced and seen as early as 24 hours after sciatic nerve transection. Thus, Gd-enhanced MRI is a new and sensitive technique to visualize denervated muscle.

  19. Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles

    SciTech Connect

    Mukherjee, A. Banerjee, M. Basu, S.; Pal, M.

    2014-04-24

    Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

  20. Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Mukherjee, A.; Banerjee, M.; Basu, S.; Pal, M.

    2014-04-01

    Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

  1. Structural, microstructural and vibrational analyses of the monoclinic tungstate BiLuWO{sub 6}

    SciTech Connect

    Ait Ahsaine, H.; Taoufyq, A.; Patout, L.; Ezahri, M.; Benlhachemi, A.; Bakiz, B.; Villain, S.; Guinneton, F.; Gavarri, J.-R.

    2014-10-15

    The bismuth lutetium tungstate phase BiLuWO{sub 6} has been prepared using a solid state route with stoichiometric mixtures of oxide precursors. The obtained polycrystalline phase has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. In the first step, the crystal structure has been refined using Rietveld method: the crystal cell was resolved using monoclinic system (parameters a, b, c, β) with space group A2/m. SEM images showed the presence of large crystallites with a constant local nominal composition (BiLuW). TEM analyses showed that the actual local structure could be better represented by a superlattice (a, 2b, c, β) associated with space groups P2 or P2/m. The Raman spectroscopy showed the presence of vibrational bands similar to those observed in the compounds BiREWO{sub 6} with RE=Y, Gd, Nd. However, these vibrational bands were characterized by large full width at half maximum, probably resulting from the long range Bi/Lu disorder and local WO{sub 6} octahedron distortions in the structure. - Graphical abstract: The average structure of BiLuWO{sub 6} determined from X-ray diffraction data can be represented by A2/m space group. Experimental Electron Diffraction patterns along the [0vw] zone axes of the monoclinic structure and associated simulated patterns show the existence of a monoclinic superstructure with space group P2 or P2/m. - Highlights: • A new monoclinic BiLuWO{sub 6} phase has been elaborated from solid-state reaction. • The space group of the monoclinic disordered average structure should be A2/m. • Transmission electron microscopy leads to a superlattice with P2/m space group. • Raman spectroscopy suggests existence of local disorder.

  2. In-situ growth of zinc tungstate nanorods on graphene for enhanced photocatalytic performance

    SciTech Connect

    Rao, Lei; Xu, Junling; Ao, Yanhui; Wang, Peifang

    2014-09-15

    Graphical abstract: Graphene/ZnWO{sub 4} (G–ZnWO{sub 4}) nanorod composite photocatalysts were prepared by a simple one-step method. Namely, the reduction of graphene oxide and the growth of ZnWO{sub 4} nanorod occurred simultaneously in one single process. An enhancement in the photocatalytic activities were observed in G–ZnWO{sub 4} composites compared with pure ZnWO{sub 4} under UV light irradiation. - Highlights: • Graphene–ZnWO{sub 4} composite photocatalyst was prepared for the first time. • The as-prepared composite photocatalysts show high activity for dye degradation. • Effect of graphene amount on the photocatalytic activity was investigated. - Abstract: Graphene–zinc tungstate (G–ZnWO{sub 4}) hybrid photocatalysts were prepared by an in-situ growth method in which the reduction of graphene oxide (GO) and the growth of ZnWO{sub 4} crystals occurred simultaneously. The materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic activity was investigated by the degradation of dye methylene blue (MB). An enhancement in the photocatalytic activity was observed for G–ZnWO{sub 4} hybrids compared with pure ZnWO{sub 4} under UV light. This improvement was attributed to the following two reasons: increased migration efficiency of photo-induced electrons and increased adsorption activity for dye molecules. The effect of the amount of graphene on the photocatalytic activity was also investigated. Results showed that there was an optimum amount of 2%.

  3. In-situ non-ambient X-ray diffraction studies of indium tungstate

    SciTech Connect

    Baiz, Tamam I.; Heinrich, Christophe P.; Banek, Nathan A.; Vivekens, Boris L.; Lind, Cora

    2012-03-15

    In situ variable temperature and high pressure X-ray diffraction studies were carried out on indium tungstate (In{sub 2}W{sub 3}O{sub 12}). This material displays positive volume expansion in both its low temperature monoclinic and high temperature orthorhombic phases, with negative thermal expansion along the a axis and positive thermal expansion along the b and c axes. Upon hydrostatic compression in a diamond anvil cell, one crystalline to crystalline phase transition is observed in the range 1.9 to 2.7 GPa, and progressive irreversible amorphization occurs at pressures above 4.3 GPa. The crystalline high pressure phase appears to be isostructural to previously observed high pressure phases in other A{sub 2}M{sub 3}O{sub 12} compounds. - Graphical abstract: Variable pressure X-ray diffraction patterns of In{sub 2}W{sub 3}O{sub 12} collected in a diamond anvil cell. A phase transition is clearly observed between 2.2 and 2.7 GPa, followed by irreversible amorphization. Highlights: Black-Right-Pointing-Pointer The structure of In{sub 2}W{sub 3}O{sub 12} was studied as a function of temperature and pressure. Black-Right-Pointing-Pointer Uniaxial negative thermal expansion was observed above 250 Degree-Sign C. Black-Right-Pointing-Pointer A pressure-induced phase transition occurred between 2.2 and 2.7 GPa. Black-Right-Pointing-Pointer Pressure-induced irreversible amorphization was observed above 4.3 GPa.

  4. Performance characterization of a MVCT scanner using multislice thick, segmented cadmium tungstate-photodiode detectors

    SciTech Connect

    Kirvan, P. F.; Monajemi, T. T.; Fallone, B. G.; Rathee, S.

    2010-01-15

    Purpose: Megavoltage computed tomography (MVCT) and megavoltage cone beam computed tomography (MVCBCT) can be used for visualizing anatomical structures prior to radiation therapy treatments to assist in patient setup and target localization. These systems are less susceptible to metal artifacts and provide better CT number linearity than conventional CT scanners. However, their contrast is limited by the properties of the megavoltage photons and the low detective quantum efficiency (DQE) of flat panel detector systems currently available. By using higher DQE, thick, segmented cadmium tungstate detectors, the authors can improve the low contrast detectability of a MVCT system. This in turn would permit greater soft tissue visualization for a given radiation dose, allowing MVCT to be used in more clinical situations. Methods: This article describes the evaluation of our prototype system that uses thick, segmented detectors. In order to create images using a dose that would be acceptable for day to day patient imaging, the authors evaluated their system using the low intensity bremsstrahlung component of a 6 MeV electron beam. The system was evaluated for its uniformity, high contrast resolution, low contrast detectability, signal to noise ratio, contrast to noise ratio, and CT number linearity. Results: The prototype system was found to have a high contrast spatial resolution of about 5 line pairs per cm, and to be able to visualize a 15 mm 1.5% contrast target with 2 cGy of radiation dose delivered. SNR{sup 2} vs radiation dose and mean pixel value vs electron density curves were linear. Conclusions: This prototype system shows a large improvement in low contrast detectability over current MVCBCT systems.

  5. Sensitivity of alanine dosimeters with gadolinium exposed to 6 MV photons at clinical doses.

    PubMed

    Marrale, M; Longo, A; Spanò, M; Bartolotta, A; D'Oca, M C; Brai, M

    2011-12-01

    In this study we analyzed the ESR signal of alanine dosimeters with gadolinium exposed to 6 MV linear accelerator photons. We observed that the addition of gadolinium brings about an improvement in the sensitivity to photons because of its high atomic number. The experimental data indicated that the addition of gadolinium increases the sensitivity of the alanine to 6 MV photons. This enhancement was better observed at high gadolinium concentrations for which the tissue equivalence is heavily reduced. However, information about the irradiation setup and of the radiation beam features allows one to correct for this difference. Monte Carlo simulations were carried out to obtain information on the expected effect of the addition of gadolinium on the dose absorbed by the alanine molecules inside the pellets. These results are compared with the experimental values, and the agreement is discussed.

  6. Gadolinium Thin Foils in a Plasma Panel Sensor as an Alternative to 3He

    SciTech Connect

    Varner Jr, Robert L; Beene, James R; Friedman, Dr. Peter S.

    2010-01-01

    Gadolinium has long been investigated as a detector for neutrons. It has a thermal neutron capture cross-section that is unparalleled among stable elements, because of the isotopes $^{155,157}$Gd. As a replacement for $^3$He, gadolinium has a significant defect, it produces many gamma-rays with an energy sum of 8 MeV. It also produces conversion electrons, mostly 29 keV in energy. The key to replacing $^3$He with gadolinium is using a gamma-blind electron detector to detect the conversion electrons. We suggest that coupling a layer of gadolinium to a Plasma Panel Sensor (PPS) can provide highly efficient, nearly gamma-blind detection of the conversion. The PPS is a proposed detector under development as a dense array of avalanche counters based on plasma display technology. We will present simulations of the response of prototypes of this detector and considerations of the use of gadolinium in the PPS.

  7. Gadolinium-hydrogen ion exchange of zirconium phosphate

    NASA Technical Reports Server (NTRS)

    Liu, D. C.; Power, J. L.

    1972-01-01

    The Gd(+3)/H(+) ion exchange on a commercial zirconium phosphate ion exchanger was investigated in chloride, sulfate, and phosphate solutions of Gd(+3) at gadolinium concentrations of 0.001 to 1 millimole per cc and in the pH range of 0 to 3.5. Relatively low Gd(+3) capacities, in the range of 0.01 to 0.1 millimole per g of ion exchanger were found at room temperature. A significant difference in Gd(+3) sorption was observed, depending on whether the ion exchanger was converted from initial conditions of greater or lesser Gd(+3) sorption than the specific final conditions. Correlations were found between decrease in Gd(+3) capacity and loss of exchanger phosphate groups due to hydrolysis during washing and between increase in capacity and treatment with H3PO4. Fitting of the experimental data to ideal ion exchange equilibrium expressions indicated that each Gd(+3) ion is sorbed on only one site of the ion exchanger. The selectivity quotient was determined to be 2.5 + or - 0.4 at room temperature on gadolinium desorption in chloride solutions.

  8. Dielectric and magnetic properties of some gadolinium silica nanoceramics

    SciTech Connect

    Coroiu, I. Pascuta, P. Bosca, M. Culea, E.

    2013-11-13

    Some nanostructure gadolinium silica glass-ceramics were obtained undergoing a sol gel method and a heat-treatment at 1000°C about two hours. The magnetic and dielectric properties of these samples were studied. The magnetic properties were evidenced performing susceptibility measurements in the 80-300K temperature range. A Curie-Weiss behavior has acquired. The values estimated for paramagnetic Curie temperature being small and positive suggest the presence of weak ferromagnetic interactions between Gd{sup 3+} ions. The dielectric properties were evaluated from dielectric permittivity (ε{sub r}) and dielectric loss (tanδ) measurements at the frequency 1 kHz, 10 kHz and 100 kHz, in the 25-225°C temperature range and dielectric dispersion at room temperature for 79.5 kHz - 1GHz frequency area. The dielectric properties suggest that the main polarization mechanism corresponds to interfacial polarization, characteristic for polycrystalline-structured dielectrics. The polycrystalline structure of the samples is due to the polymorphous transformations of the nanostructure silica crystallites in the presence of gadolinium oxide. They were highlighted by SEM micrographs.

  9. MRI gadolinium enhancement precedes neuroradiological findings in acute necrotizing encephalopathy.

    PubMed

    Yoshida, Takeshi; Tamura, Takuya; Nagai, Yuhki; Ueda, Hiroyuki; Awaya, Tomonari; Shibata, Minoru; Kato, Takeo; Heike, Toshio

    2013-11-01

    We report a 2-year-old Japanese boy with acute necrotizing encephalopathy (ANE) triggered by human herpes virus-6, who presented insightful magnetic resonance imaging (MRI) findings. He was admitted due to impaired consciousness and a convulsion, 2 days after the onset of an upper respiratory infection. At admission, cranial MRI showed marked gadolinium enhancement at the bilateral thalami, brainstem and periventricular white matter without abnormal findings in noncontrast MRI sequences. On the following day, noncontrast computed tomography demonstrated homogeneous low-density lesions in the bilateral thalami and severe diffuse brain edema. The patient progressively deteriorated and died on the 18th day of admission. The pathogenesis of ANE remains mostly unknown, but it has been suggested that hypercytokinemia may play a major role. Overproduced cytokines cause vascular endothelial damage and alter the permeability of the vessel wall in the multiple organs, including the brain. The MRI findings in our case demonstrate that blood-brain barrier permeability was altered prior to the appearance of typical neuroradiological findings. This suggests that alteration of blood-brain barrier permeability is the first step in the development of the brain lesions in ANE, and supports the proposed mechanism whereby hypercytokinemia causes necrotic brain lesions. This is the first report demonstrating MRI gadolinium enhancement antecedent to typical neuroradiological findings in ANE.

  10. Selection and preliminary evaluation of three structures as potential solid conductors of alkali ions: Two hollandites, a titanate, and a tungstate

    NASA Technical Reports Server (NTRS)

    Singer, J.; Kautz, H. E.; Fielder, W. L.; Fordyce, J. S.

    1973-01-01

    Utilization of crystal-chemical criteria has suggested three structure types in which alkali ions may be mobile: (1)hollandites K(x)Mg(x/2)Ti(8-x/2)O16 and K(x)Al(x)Ti(8-x)O16 for 1.6 less than or equal to x less than or equal to 2.0 tungstate K2W4013; and (3) sodium hexatitante Na2Ti6O13. Each is a tunnel structure. An electrical screening procedure, previously tested on beta-alumina, has indicated high K(+) ion mobility in the hollandites and in the tungstate, but not in the hexatitanate. Specimens were polycrystalline disks near 90 percent of theoretical density. The ac conductivity calculated from dielectric and capacitance measurements has been attributed to ion mobility. This ac conductivity was up to 0.01/ohm-cm for hollandites and about 0.0001/ohm-cm for the tungstate, with approximate activation energies of 21 to 25 and 16 kJ/mole (5 to 6 and 4 kcal/mole), respectively. Electronic conduction and chemical reactivity have eliminated the tungstate from further consideration. The hollandites have been considered worthy of further development and evaluation.

  11. Novel inducers of the envelope stress response BaeSR in Salmonella Typhimurium: BaeR is critically required for tungstate waste disposal.

    PubMed

    Appia-Ayme, Corinne; Patrick, Elaine; Sullivan, Matthew J; Alston, Mark J; Field, Sarah J; AbuOun, Manal; Anjum, Muna F; Rowley, Gary

    2011-01-01

    The RpoE and CpxR regulated envelope stress responses are extremely important for Salmonella Typhimurium to cause infection in a range of hosts. Until now the role for BaeSR in both the Salmonella Typhimurium response to stress and its contribution to infection have not been fully elucidated. Here we demonstrate stationary phase growth, iron and sodium tungstate as novel inducers of the BaeRregulon, with BaeR critically required for Salmonella resistance to sodium tungstate. We show that functional overlap between the resistance nodulation-cell division (RND) multidrug transporters, MdtA, AcrD and AcrB exists for the waste disposal of tungstate from the cell. We also point to a role for enterobactinsiderophores in the protection of enteric organisms from tungstate, akin to the scenario in nitrogen fixing bacteria. Surprisingly, BaeR is the first envelope stress response pathway investigated in S. Typhimurium that is not required for murine typhoid in either ity(S) or ity(R) mouse backgrounds. BaeR is therefore either required for survival in larger mammals such as pigs or calves, an avian host such as chickens, or survival out with the host altogether where Salmonella and related enterics must survive in soil and water.

  12. Growth Control in Colon Epithelial Cells: Gadolinium Enhances Calcium-Mediated Growth Regulation

    PubMed Central

    Attili, Durga; Jenkins, Brian; Aslam, Muhammad Nadeem; Dame, Michael K.

    2013-01-01

    Gadolinium, a member of the lanthanoid family of transition metals, interacts with calcium-binding sites on proteins and other biological molecules. The overall goal of the present investigation was to determine if gadolinium could enhance calcium-induced epithelial cell growth inhibition in the colon. Gadolinium at concentrations as low as 1–5 µM combined with calcium inhibits proliferation of human colonic epithelial cells more effectively than calcium alone. Gadolinium had no detectable effect on calcium-induced differentiation in the same cells based on change in cell morphology, induction of E-cadherin synthesis, and translocation of E-cadherin from the cytosol to the cell surface. When the colon epithelial cells were treated with gadolinium and then exposed to increased calcium concentrations, movement of extracellular calcium into the cell was suppressed. In contrast, gadolinium treatment had no effect on ionomycin-induced release of stored intracellular calcium into the cytoplasm. Whether these in vitro observations can be translated into an approach for reducing abnormal proliferation in the colonic mucosa (including polyp formation) is not known. These results do, however, provide an explanation for our recent findings that a multi-mineral supplement containing all of the naturally occurring lanthanoid metals including gadolinium are more effective than calcium alone in preventing colon polyp formation in mice on a high-fat diet. PMID:23008064

  13. Growth control in colon epithelial cells: gadolinium enhances calcium-mediated growth regulation.

    PubMed

    Attili, Durga; Jenkins, Brian; Aslam, Muhammad Nadeem; Dame, Michael K; Varani, James

    2012-12-01

    Gadolinium, a member of the lanthanoid family of transition metals, interacts with calcium-binding sites on proteins and other biological molecules. The overall goal of the present investigation was to determine if gadolinium could enhance calcium-induced epithelial cell growth inhibition in the colon. Gadolinium at concentrations as low as 1-5 μM combined with calcium inhibits proliferation of human colonic epithelial cells more effectively than calcium alone. Gadolinium had no detectable effect on calcium-induced differentiation in the same cells based on change in cell morphology, induction of E-cadherin synthesis, and translocation of E-cadherin from the cytosol to the cell surface. When the colon epithelial cells were treated with gadolinium and then exposed to increased calcium concentrations, movement of extracellular calcium into the cell was suppressed. In contrast, gadolinium treatment had no effect on ionomycin-induced release of stored intracellular calcium into the cytoplasm. Whether these in vitro observations can be translated into an approach for reducing abnormal proliferation in the colonic mucosa (including polyp formation) is not known. These results do, however, provide an explanation for our recent findings that a multi-mineral supplement containing all of the naturally occurring lanthanoid metals including gadolinium are more effective than calcium alone in preventing colon polyp formation in mice on a high-fat diet.

  14. Gadolinium nanoparticles and contrast agent as radiation sensitizers.

    PubMed

    Taupin, Florence; Flaender, Mélanie; Delorme, Rachel; Brochard, Thierry; Mayol, Jean-François; Arnaud, Josiane; Perriat, Pascal; Sancey, Lucie; Lux, François; Barth, Rolf F; Carrière, Marie; Ravanat, Jean-Luc; Elleaume, Hélène

    2015-06-07

    The goal of the present study was to evaluate and compare the radiosensitizing properties of gadolinium nanoparticles (NPs) with the gadolinium contrast agent (GdCA) Magnevist(®) in order to better understand the mechanisms by which they act as radiation sensitizers. This was determined following either low energy synchrotron irradiation or high energy gamma irradiation of F98 rat glioma cells exposed to ultrasmall gadolinium NPs (GdNPs, hydrodynamic diameter of 3 nm) or GdCA. Clonogenic assays were used to quantify cell survival after irradiation in the presence of Gd using monochromatic x-rays with energies in the 25 keV-80 keV range from a synchrotron and 1.25 MeV gamma photons from a cobalt-60 source. Radiosensitization was demonstrated with both agents in combination with X-irradiation. At the same concentration (2.1 mg mL(-1)), GdNPS had a greater effect than GdCA. The maximum sensitization-enhancement ratio at 4 Gy (SER4Gy) was observed at an energy of 65 keV for both the nanoparticles and the contrast agent (2.44   ±   0.33 and 1.50   ±   0.20, for GdNPs and GdCA, respectively). At a higher energy (1.25 MeV), radiosensitization only was observed with GdNPs (1.66   ±   0.17 and 1.01   ±   0.11, for GdNPs and GdCA, respectively). The radiation dose enhancements were highly 'energy dependent' for both agents. Secondary-electron-emission generated after photoelectric events appeared to be the primary mechanism by which Gd contrast agents functioned as radiosensitizers. On the other hand, other biological mechanisms, such as alterations in the cell cycle may explain the enhanced radiosensitizing properties of GdNPs.

  15. Gadolinium nanoparticles and contrast agent as radiation sensitizers

    NASA Astrophysics Data System (ADS)

    Taupin, Florence; Flaender, Mélanie; Delorme, Rachel; Brochard, Thierry; Mayol, Jean-François; Arnaud, Josiane; Perriat, Pascal; Sancey, Lucie; Lux, François; Barth, Rolf F.; Carrière, Marie; Ravanat, Jean-Luc; Elleaume, Hélène

    2015-06-01

    The goal of the present study was to evaluate and compare the radiosensitizing properties of gadolinium nanoparticles (NPs) with the gadolinium contrast agent (GdCA) Magnevist® in order to better understand the mechanisms by which they act as radiation sensitizers. This was determined following either low energy synchrotron irradiation or high energy gamma irradiation of F98 rat glioma cells exposed to ultrasmall gadolinium NPs (GdNPs, hydrodynamic diameter of 3 nm) or GdCA. Clonogenic assays were used to quantify cell survival after irradiation in the presence of Gd using monochromatic x-rays with energies in the 25 keV-80 keV range from a synchrotron and 1.25 MeV gamma photons from a cobalt-60 source. Radiosensitization was demonstrated with both agents in combination with X-irradiation. At the same concentration (2.1 mg mL-1), GdNPS had a greater effect than GdCA. The maximum sensitization-enhancement ratio at 4 Gy (SER4Gy) was observed at an energy of 65 keV for both the nanoparticles and the contrast agent (2.44   ±   0.33 and 1.50   ±   0.20, for GdNPs and GdCA, respectively). At a higher energy (1.25 MeV), radiosensitization only was observed with GdNPs (1.66   ±   0.17 and 1.01   ±   0.11, for GdNPs and GdCA, respectively). The radiation dose enhancements were highly ‘energy dependent’ for both agents. Secondary-electron-emission generated after photoelectric events appeared to be the primary mechanism by which Gd contrast agents functioned as radiosensitizers. On the other hand, other biological mechanisms, such as alterations in the cell cycle may explain the enhanced radiosensitizing properties of GdNPs.

  16. Nephrogenic systemic fibrosis and gadolinium-based contrast media: updated ESUR Contrast Medium Safety Committee guidelines.

    PubMed

    Thomsen, Henrik S; Morcos, Sameh K; Almén, Torsten; Bellin, Marie-France; Bertolotto, Michele; Bongartz, Georg; Clement, Olivier; Leander, Peter; Heinz-Peer, Gertraud; Reimer, Peter; Stacul, Fulvio; van der Molen, Aart; Webb, Judith A W

    2013-02-01

    To update the guidelines of the Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) on nephrogenic systemic fibrosis and gadolinium-based contrast media. Topics reviewed include the history, clinical features and prevalence of nephrogenic systemic fibrosis and the current understanding of its pathophysiology. The risk factors for NSF are discussed and prophylactic measures are recommended. The stability of the different gadolinium-based contrast media and the potential long-term effects of gadolinium in the body have also been reviewed.

  17. Gadolinium doped Ceria nanocrystals synthesized from mesoporous silica

    NASA Astrophysics Data System (ADS)

    Rossinyol, Emma; Pellicer, Eva; Prim, Anna; Estradé, Sònia; Arbiol, Jordi; Peiró, Francesca; Cornet, Albert; Morante, Joan Ramon

    2008-02-01

    Highly crystalline and thermally stable gadolinium doped ceria (GDC) particles have been synthesized by hard template route for the first time. This oxide is being recognized as an intermediate temperature (500-700 °C) electrolyte material for applications in solid-oxide fuel cells. The GDC particles show high crystallinity and nanometric size (2.83 ± 0.05 nm in diameter) and Raman analyses confirm the formation of the solid solution instead of a CeO2 and Gd2O3 mixture. EDX and EELS studies indicate a stoichiometry coherent with the Gd0.2Ce0.8O1.9 phase. The synthesized nanometric powder is expected to be used in solid oxide fuel cells as well as in the catalytic treatment of automobile exhaust fumes.

  18. Sintering and mechanical properties of gadolinium-doped ceria ceramics

    NASA Astrophysics Data System (ADS)

    Yasuda, K.; Uemura, K.; Shiota, T.

    2012-01-01

    Gadolinium-doped ceria (GDC) ceramics were made by sintering at various temperatures from 1000°C to 1400°C in air. The true density and apparent density were measured to calculate the relative density of GDC ceramics. The change in relative density revealed that densification of GDC ceramics increased up to 1200°C, and thereafter turned downward. It was suggested that pores were formed at 1300°C and 1400°C due to non-stoichiometry of ceria. JIS-type specimens were cut from the sintered body and tested by 4-point bending. Young's modulus and bending strength decreased with increasing the sintering temperature from 1200°C to 1400°C, corresponding to the change in the relative density.

  19. Densification Dynamics of Gadolinium-Doped Ceria upon Sintering

    NASA Astrophysics Data System (ADS)

    Sato, Kiminori

    2012-07-01

    Densification behavior upon sintering is studied for gadolinium-doped ceria (GDC) by making use of X-ray diffraction, Archimedes method, high-resolution dilatometry (DLT), and element-specific positron annihilation spectroscopy. We found high concentration of vacancy-like nano-defects at GDC-crystallite interfaces participating in densification. Time-resolved length change and positron lifetime measurements enable to discuss the densification dynamics at the particle boundary relevant to a sintering neck and inside the particles. The particle boundary largely contributes to densification at the initial stage of sintering, whereas the crystallite interface gets to be responsible for prolonged densification. The densification inside the particle is developed by the growth of the crystallites followed by the transfer of Gd atoms from the interfaces to the crystallites.

  20. The structural response of gadolinium phosphate to pressure

    SciTech Connect

    Heffernan, Karina M.; Ross, Nancy L.; Spencer, Elinor C.; Boatner, Lynn A.

    2016-06-16

    In this study, accurate elastic constants for gadolinium phosphate (GdPO4) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO4 determined under hydrostatic conditions, 128.1(8) GPa (K'=5.8(2)), is markedly different from that obtained with GdPO4 under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. Finally, high pressure Raman and diffraction analysis indicate that the PO4 tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO4 structure is facilitated by bending/twisting of the Gd–O–P links that result in increased distortion in the GdO9 polyhedra.

  1. The structural response of gadolinium phosphate to pressure

    DOE PAGES

    Heffernan, Karina M.; Ross, Nancy L.; Spencer, Elinor C.; ...

    2016-06-16

    In this study, accurate elastic constants for gadolinium phosphate (GdPO4) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO4 determined under hydrostatic conditions, 128.1(8) GPa (K'=5.8(2)), is markedly different from that obtained with GdPO4 under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. Finally, high pressure Raman and diffraction analysis indicate that the PO4 tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO4 structure is facilitated by bending/twisting of the Gd–O–P links that result in increased distortion in the GdO9more » polyhedra.« less

  2. The structural response of gadolinium phosphate to pressure

    SciTech Connect

    Heffernan, Karina M.; Ross, Nancy L.; Spencer, Elinor C.; Boatner, Lynn A.

    2016-06-16

    In this study, accurate elastic constants for gadolinium phosphate (GdPO4) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO4 determined under hydrostatic conditions, 128.1(8) GPa (K'=5.8(2)), is markedly different from that obtained with GdPO4 under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. Finally, high pressure Raman and diffraction analysis indicate that the PO4 tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO4 structure is facilitated by bending/twisting of the Gd–O–P links that result in increased distortion in the GdO9 polyhedra.

  3. Defect induced mobility enhancement: Gadolinium oxide (100) on Si(100)

    SciTech Connect

    Sitaputra, W.; Tsu, R.

    2012-11-26

    Growth of predominantly single crystal (100)-oriented gadolinium oxide (Gd{sub 2}O{sub 3}) on a p-type Si(100) and growth of a polycrystal with a predominant Gd{sub 2}O{sub 3}(100) crystallite on a n-type Si(100) was performed using molecular beam epitaxy. Despite a poorer crystal structure than Gd{sub 2}O{sub 3}(110), an enhancement in carrier mobility can be found only from the Gd{sub 2}O{sub 3}(100)/n-type Si(100) interface. The mobility of 1715-1780 cm{sup 2}/V {center_dot} s was observed at room temperature, for carrier concentration >10{sup 20} cm{sup -3}. This accumulation of the electrons and the mobility enhancement may arise from the two-dimensional confinement due to charge transfer across the interface similar to transfer doping.

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

    DOE PAGES

    Li, Yuanyuan; Kraynis, Olga; Kas, Joshua; ...

    2016-05-20

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

  5. Mechanism of inhibition of ribonucleotide reductase with motexafin gadolinium (MGd)

    SciTech Connect

    Zahedi Avval, Farnaz; Berndt, Carsten; Pramanik, Aladdin; Holmgren, Arne

    2009-02-13

    Motexafin gadolinium (MGd) is an expanded porphyrin anticancer agent which selectively targets tumor cells and works as a radiation enhancer, with promising results in clinical trials. Its mechanism of action is oxidation of intracellular reducing molecules and acting as a direct inhibitor of mammalian ribonucleotide reductase (RNR). This paper focuses on the mechanism of inhibition of RNR by MGd. Our experimental data present at least two pathways for inhibition of RNR; one precluding subunits oligomerization and the other direct inhibition of the large catalytic subunit of the enzyme. Co-localization of MGd and RNR in the cytoplasm particularly in the S-phase may account for its inhibitory properties. These data can elucidate an important effect of MGd on the cancer cells with overproduction of RNR and its efficacy as an anticancer agent and not only as a general radiosensitizer.

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

    SciTech Connect

    Li, Yuanyuan; Zacharowicz, Renee; Frenkel, Anatoly I. E-mail: anatoly.frenkel@yu.edu; Kraynis, Olga; Lubomirsky, Igor E-mail: anatoly.frenkel@yu.edu; Kas, Joshua; Weng, Tsu-Chien; Sokaras, Dimosthenis

    2016-05-15

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

  7. Epiphyseal and physeal cartilage: normal gadolinium-enhanced MR imaging.

    PubMed

    Li, Xiaoming; Wang, Renfa; Li, Yonggang; Tang, Lihua; Hu, Junwu; Xu, Anhui

    2005-01-01

    To evaluate the normal appearance of epiphyseal and physeal cartilage on Gadolinium (Gd)-enhanced MR imaging. The appearance and enhancement ratios of 20 proximal and distal femoral epiphyses in 10 normal piglets were analyzed on Gd-enhanced MR images. The correlation of the MR imaging appearance with corresponding histological findings of immature epiphyses was examined. Our results showed that Gd-enhanced MRI could differentiate the differences in enhancement between physeal and epiphyseal cartilage and show vascular canals within the epiphyseal cartilage. Enhanced ratios in the physeal were greater than those in the epiphyseal cartilage (P < 0.005). It is concluded that Gd-enhanced MR imaging reveals epiphyseal vascular canals and shows difference in enhancement of physeal and epiphyseal cartilage.

  8. Fabrication and Characterization of Gadolinium Phosphate Neutron Absorber

    SciTech Connect

    Lessing, Paul Alan; Erickson, Arnold Wendell

    2003-12-01

    Hydrated gadolinium phosphate (GdPO4·1H2O) was synthesized by reacting high purity dissolved salts (gadolinium nitrates or chlorides) with phosphoric acid. The hydrated powders were shown to be extremely insoluble in water with a Ksp measured to be between 2.07 E-14 and 4.76 E-13. Calcination to between 800 and 1000 °C resulted in the formation of GdPO4 in a monazite (monoclinic) crystal structure. This was correlated with the first exothermic differential thermal analysis (DTA) peak (864.9–883.4 °C). The DTA also showed small peaks in the 1200–1250 °C range, that could be associated with a change from the monazite (monoclinic) crystal structure to the xenotime (tetragonal) crystal structure. However, calcination of a sample to 1400 °C, followed by relatively rapid cooling and XRD, showed the structure was still monazite (monoclinic). DTA results showed a melting point at 1899–1920 °C (endothermic peak). It was therefore concluded that the melting point probably was the melting of the monazite (monoclinic) phase, but may have been xenotime if a phase change at 1200–1250 °C was reversible and very rapid. The higher part of the melting range was achieved with material derived using the slightly higher purity nitrate salt. The results show that GdPO4 is an excellent candidate for a chemically stable, water-insoluble neutron absorber for inclusion in spent nuclear fuel canisters.

  9. Immediate hypersensitivity reaction to gadolinium-based MR contrast media.

    PubMed

    Jung, Jae-Woo; Kang, Hye-Ryun; Kim, Min-Hye; Lee, Whal; Min, Kyung-Up; Han, Moon-Hee; Cho, Sang-Heon

    2012-08-01

    To determine the incidence and risk factors of immediate hypersensitivity reactions to gadolinium-based magnetic resonance (MR) contrast agents. Institutional review board approval and a waiver of informed consent were obtained. A retrospective study of patients who had been given gadolinium-based MR contrast media between August 2004 and July 2010 was performed by reviewing their electronic medical records. In addition to data on immediate hypersensitivity reaction, the kinds of MR contrast media and demographic data including age, sex, and comorbidity were collected. To compare the groups, the χ(2) test, Fisher exact test, χ(2) test for trend, Student t test, analysis of variance test, and multiple logistic regression test were performed. A total of 112 immediate hypersensitivity reactions (0.079% of 141 623 total doses) were identified in 102 patients (0.121% of 84 367 total patients). Among the six evaluated MR contrast media, gadodiamide had the lowest rate (0.013%) of immediate hypersensitivity reactions, while gadobenate dimeglumine had the highest rate (0.22%). The rate for immediate hypersensitivity reactions was significantly higher in female patients (odds ratio = 1.687; 95% confidence interval: 1.143, 2.491) and in patients with allergies and asthma (odds ratio = 2.829; 95% confidence interval: 1.427, 5.610). Patients with a previous history of immediate hypersensitivity reactions had a higher rate of recurrence after reexposure to MR contrast media (30%) compared with the incidence rate in total patients (P < .0001). The incidence of immediate hypersensitivity reactions increased depending on the number of times patients were exposed to MR contrast media (P for trend = .036). The most common symptom was urticaria (91.1%), and anaphylaxis occurred in 11 cases (9.8%). The mortality rate was 0.0007% because of one fatality. The incidence of immediate hypersensitivity reactions to MR contrast media was 0.079%, and the recurrence rate of hypersensitivity

  10. Biospeciation of tungsten in the serum of diabetic and healthy rats treated with the antidiabetic agent sodium tungstate.

    PubMed

    Gómez-Gómez, M Milagros; Rodríguez-Fariñas, Nuria; Cañas-Montalvo, Benito; Domínguez, Jorge; Guinovart, Joan; Cámara-Rica, Carmen

    2011-05-30

    It is known that oral administration of sodium tungstate preserves the pancreatic beta cell function in diabetic rats. Healthy and streptozotocin-induced diabetic rats were treated with sodium tungstate for one, three or six weeks, after which the species of W in serum, were analysed. An increase in serum W with treatment time was observed. After six weeks, the serum W concentration in diabetic rats (70 mg L(-1)) was about 4.6 times higher than in healthy specimens. This different behaviour was also observed for Cu accumulation, while the Zn pattern follows the contrary. The patterns observed in the retention of Cu and Zn may be attributable to a normalization of glycaemia. The speciation analysis of W was performed using 2D separations, including an immunoaffinity packing and a SEC (Size Exclusion Chromatography) column coupled to an ICP-MS (Inductively Coupled Plasma Mass Spectrometry) for elemental detection. Ultrafiltration data together with SEC-ICP-MS results proved that around 80% of serum W was bound to proteins, the diabetic rats registering a higher W content than their healthy counterparts. Most of the protein-bound W was due to a complex with albumin. An unknown protein with a molecular weight higher than 100 kDa was also found to bind a small amount of W (about 2%). MALDI-TOF (Matrix-Assisted Laser Desorption Ionization Time-of-Flight) analysis of the desalted and concentrated chromatographic fractions confirmed albumin as the main protein bound to tungstate in rat serum, while no binding to transferrin (Tf) was detected. The interaction between glutathione and W was also evaluated using standard solutions; however, the formation of complexes was not observed. The stability of the complexes between W and proteins when subjected to more stringent procedures, like those used in proteomic methodologies (denaturing with urea or SDS, boiling, sonication, acid media, reduction with β-mercaptoethanol (BME) or DTT (dithiotreitol) and alkylation with

  11. Insights into the use of gadolinium and gadolinium/boron-based agents in imaging-guided neutron capture therapy applications.

    PubMed

    Deagostino, Annamaria; Protti, Nicoletta; Alberti, Diego; Boggio, Paolo; Bortolussi, Silva; Altieri, Saverio; Crich, Simonetta Geninatti

    2016-05-01

    Gadolinium neutron capture therapy (Gd-NCT) is currently under development as an alternative approach for cancer therapy. All of the clinical experience to date with NCT is done with (10)B, known as boron neutron capture therapy (BNCT), a binary treatment combining neutron irradiation with the delivery of boron-containing compounds to tumors. Currently, the use of Gd for NCT has been getting more attention because of its highest neutron cross-section. Although Gd-NCT was first proposed many years ago, its development has suffered due to lack of appropriate tumor-selective Gd agents. This review aims to highlight the recent advances for the design, synthesis and biological testing of new Gd- and B-Gd-containing compounds with the task of finding the best systems able to improve the NCT clinical outcome.

  12. Theoretical study of structure and stability of small gadolinium carboxylate complexes in liquid scintillator solvents.

    PubMed

    Huang, Pin-Wen

    2014-09-01

    The structural properties of three small gadolinium carboxylate complexes in three liquid scintillator solvents (pseudocumene, linear alkylbenzene, and phenyl xylylethane) were theoretically investigated using density functional theory (B3LYP/LC-RECP) and polarizable continuum model (PCM). The average interaction energy between gadolinium atom and carboxylate ligand (E(int)) and the energy difference of the highest singly occupied molecular orbital and lowest unoccupied molecular orbital (Δ(SL)) were calculated to evaluate and compare the relative stability of these complexes in solvents. The calculation results show that the larger (with a longer alkyl chain) gadolinium carboxylate complex has greater stability than the smaller one, while these gadolinium carboxylates in linear alkylbenzene were found to have greater stability than those in the other two solvents.

  13. Characteristics of gadolinium-DTPA complex: a potential NMR contrast agent

    SciTech Connect

    Weinmann, H.J.; Brasch, R.C.; Press, W.R.; Wesbey, G.E.

    1984-03-01

    Chelation of the rare-earth element gadolinium (Gd) with diethylenetriaminepentaacetic acid (DTPA) results in a strongly paramagnetic, stable complex that is well tolerated in animals. The strongly paramagnetic gadolinium complex reduces hydrogen-proton relaxation times even in low concentrations (less than 0.01 mmol/L). The pharmacokinetic behavior of intravenously delivered Gd-DTPA is similar to the well known iodinated contrast agents used in urography and angiography; excretion is predominately through the kidneys with greater than 90% recovery in 24 hr. The intravenous LD/sub 50/ of the meglumine salt of Gd-DTPA is 10 mmol/kg for the rat; in vivo there is no evidence of dissociation of the gadolinium ion from the DTPA ligand. The combination of strong proton relaxation, in-vivo stability, rapid urinary excretion, and high tolerance favors the further development and the potential clinical application of gadolinium-DTPA as a contrast enhancer in magnetic resonance imaging.

  14. Thyroid xanthine oxidase and its role in thyroid iodine metabolism in the rat: difference between effects of allopurinol and tungstate.

    PubMed

    Kawada, J; Shirakawa, Y; Yoshimura, Y; Nishida, M

    1982-10-01

    The role of xanthine oxidase in thyroid function was studied in the rat in vivo by different approaches. Allopurinol, an inhibitor of xanthine oxidase, was administered by mixing it with a powdered diet (16 mg/100 g body wt per day for 10 days). This treatment significantly reduced the total uptake of iodide and inhibited the organification of iodide in the rat thyroid gland. Thyroid xanthine oxidase and dehydrogenase were almost completely inactivated by tungstate, which was given to rats (100 p.p.m./animal per day in drinking water for 10 days) maintained on a purified diet containing low levels of molybdenum. Under these conditions, no inhibitory effect was observed on synthesis of thyroid hormones. It therefore seemed reasonable to assume that the suppressive effect of allopurinol on the biosynthesis of thyroid hormones is not mediated by xanthine oxidase.

  15. The use of a sodium tungstate developer markedly improves the electron microscopic localization of zinc by the Timm method.

    PubMed

    Seress, L; Gallyas, F

    2000-07-31

    The Timm's sulfide-silver method is frequently used for the demonstration of the mossy fiber bundle or sprouted mossy fibers in the normal or epileptic hippocampal dentate gyrus. Under the light microscope the results are excellent, but the ultrastructure is considerably impaired and the silver grains produced are too large as compared to the sizes of intra-synaptic structures. The present study was meant to test a series of physical developers containing, instead of gum arabic, sodium tungstate as protective colloid. One of them left the ultrastructure fairly intact and produced small, round silver grains, making it possible to precisely locate zinc in mossy terminals. With this method, it could be demonstrated that zinc is contained inside synaptic vesicles in the resting axon terminals of granule cells. As a consequence of prolonged sodium sulfide perfusion, zinc is released from synaptic vesicles and enters the synaptic cleft.

  16. Luminescence properties of alkali europium double tungstates and molybdates AEuM/sub 2/O/sub 8/

    SciTech Connect

    van Vliet, J.P.M.; Blasse, G.; Brixner, L.H.

    1988-09-01

    The luminescence properties of AEuW/sub 2/O/sub 8/ and AEuMo/sub 2/O/sub 8/ (A/sup +/ = alkali metal ion) are reported. These properties depend on the crystal structure type. Vibronic coupling between the electronic transitions of the Eu/sup 3 +/ ion and the vibrational transitions of the tungstate of molybdate group is observed. The concentration quenching of the Eu/sup 3 +/ luminescence is weak. The analysis of the Eu/sup 3 +/ decay curves points to energy migration and shows the two-dimensionality of the Eu/sup 3 +/ sublattice in KEuMo/sub 2/O/sub 8/ and the one-dimensionality of the Eu/sup 3 +/ sublattice in KEuW/sub 2/O/sub 8/ and RbEuW/sub 2/O/sub 8/.

  17. Specific recognition of guanines in non-duplex regions of nucleic acids with potassium tungstate and hydrogen peroxide

    PubMed Central

    Mao, Wuxiang; Xu, Xiaowei; He, Huan; Huang, Rong; Chen, Xi; Xiao, Heng; Yu, Zhenduo; Liu, Yi; Zhou, Xiang

    2015-01-01

    Structural features of nucleic acids have become an integral part of current biomedical research. Highly selective and readily performed methods with little toxicity that target guanosines in non-duplex nucleic acids are needed, which led us to search for an effective agent for guanosine sequencing. Treatment of DNA or RNA with potassium tungstate and hydrogen peroxide produced damaged guanosines in DNA or RNA sequences. The damaged guanosines in non-duplex DNA could be cleaved by hot piperidine. Similarly, damaged guanosines in non-duplex RNA could be cleaved by aniline acetate. We could identify structural features of nucleic acid using this strategy instead of dimethyl sulphate and Ribonuclease T1. PMID:25355517

  18. Density of Gadolinium Nitrate Solutions for the High Flux Isotope Reactor

    SciTech Connect

    Taylor, Paul Allen; Lee, Denise L

    2009-05-01

    In late 1992, the High Flux Isotope Reactor (HFIR) was planning to switch the solution contained in the poison injection tank from cadmium nitrate to gadolinium nitrate. The poison injection system is an emergency system used to shut down the reactor by adding a neutron poison to the cooling water. This system must be able to supply a minimum of 69 pounds of gadolinium to the reactor coolant system in order to guarantee that the reactor would become subcritical. A graph of the density of gadolinium nitrate solutions over a concentration range of 5 to 30 wt% and a temperature range of 15 to 40{sup o}C was prepared. Routine density measurements of the solution in the poison injection tank are made by HFIR personnel, and an adaptation of the original graph is used to determine the gadolinium nitrate concentration. In late 2008, HFIR personnel decided that the heat tracing that was present on the piping for the poison injection system could be removed without any danger of freezing the solution; however, the gadolinium nitrate solution might get as cold as 5{sup o}C. This was outside the range of the current density-concentration correlation, so the range needed to be expanded. This report supplies a new density-concentration correlation that covers the extended temperature range. The correlation is given in new units, which greatly simplifies the calculation that is required to determine the pounds of gadolinium in the tank solution. The procedure for calculating the amount of gadolinium in the HFIR poison injection system is as follows: (1) Calculate the usable volume in the system; (2) Measure the density of the solution; (3) Calculate the gadolinium concentration using the following equation: Gd(lb/ft{sup 3}) = measured density (g/mL) x 34.681 - 34.785; (4) Calculate the amount of gadolinium in the system using the following equation: Amount of Gd(lb) = Gd concentration (lb/ft{sup 3}) x usable volume (ft{sup 3}). The equation in step 3 is exact for a temperature of

  19. Gadolinium Use in Spine Pain Management Procedures for Patients with Contrast Allergies: Results in 527 Procedures

    SciTech Connect

    Safriel, Yair Ang, Roberto; Ali, Muhammed

    2008-03-15

    Introduction. To review the safety and efficacy of gadolinium in spine pain management procedures in patients at high risk for a contrast reaction and who are not suitable candidates for the use of standard non-ionic contrast. Methods. We reviewed records over a 61-month period of all image-guided spinal pain management procedures where patients had allergies making them unsuitable candidates for standard non-ionic contrast and where gadolinium was used to confirm needle tip placement prior to injection of medication. Results. Three hundred and four outpatients underwent 527 procedures. A spinal needle was used in all but 41 procedures. Gadolinium was visualized using portable C-arm fluoroscopy in vivo allowing for confirmation of needle tip location. The gadolinium dose ranged from 0.2 to 10 ml per level. The highest dose received by one patient was 15.83 ml intradiscally during a three-level discogram. Three hundred and one patients were discharged without complication or known delayed complications. One patient had documented intrathecal injection but without sequelae and 2 patients who underwent cervical procedures experienced seizures requiring admission to the intensive care unit. Both the latter patients were discharged without any further complications. Conclusion. Based on our experience we recommend using gadolinium judiciously for needle tip confirmation. We feel more confident using gadolinium in the lumbar spine and in cervical nerve blocks. Gadolinium should probably not be used as an injectate volume expander. The indications for gadolinium use in cervical needle-guided spine procedures are less clear and use of a blunt-tipped needle should be considered.

  20. Pharmacokinetics of radiolabeled tungsten ((188)W) in male Sprague-Dawley rats following acute sodium tungstate inhalation.

    PubMed

    Radcliffe, Pheona M; Leavens, Teresa L; Wagner, Dean J; Olabisi, Ayodele O; Struve, Melanie F; Wong, Brian A; Tewksbury, Earl; Chapman, Gail D; Dorman, David C

    2010-01-01

    Aerosol cloud formation may occur when certain tungsten munitions strike hard targets, placing military personnel at increased risk of exposure. Although the pharmacokinetics of various forms of tungsten have been studied in animals following intravenous and oral administration, tungsten disposition following inhalation remains incompletely characterized. The objective of this study was to evaluate the pharmacokinetics of inhaled tungstate (WO(4)) in rats. Male, 16-wk-old, CD rats (n = 7 rats/time point) underwent a single, 90-min, nose-only exposure to an aerosol (mass median aerodynamic diameter [MMAD] 1.50 mum ) containing 256 mg W/m(3) as radiolabeled sodium tungstate (Na(2)(188)WO(4)). (188)W tissue concentrations were determined at 0, 1, 3, 7, and 21 days postexposure by gamma spectrometry. The thyroid and urine had the highest (188)W levels postexposure, and urinary excretion was the primary route of (188)W elimination. The pharmacokinetics of tungsten in most tissues was best described with a two-compartment pharmacokinetic model with initial phase half-lives of approximately 4 to 6 h and a longer terminal phase with half-lives of approximately 6 to 67 days. The kidney, adrenal, spleen, femur, lymph nodes, and brain continued to accumulate small amounts of tungsten as reflected by tissue:blood activity ratios that increased throughout the 21-day period. At day 21 all tissues except the thyroid, urine, lung, femur, and spleen had only trace levels of (188)W. Data from this study can be used for development and refinement of pharmacokinetic models for tungsten inhalation exposure in environmental and occupational settings.

  1. Application of extracellular gadolinium-based MRI contrast agents and the risk of nephrogenic systemic fibrosis.

    PubMed

    Heverhagen, J T; Krombach, G A; Gizewski, E

    2014-07-01

    Nephrogenic systemic fibrosis (NSF) is a serious, sometimes fatal disease. Findings in recent years have shown that a causal association between gadolinium containing contrast media and NSF is most likely. Therefore, the regulatory authorities have issued guidelines on the use of gadolinium-containing contrast media which have reduced the number of new cases of NSF to almost zero. However, it is for precisely this reason that the greatest care must still be taken to ensure that these guidelines are complied with. The most important factors are renal function, the quantity of gadolinium administered and coexisting diseases such as inflammation. All of these factors crucially influence the quantity of gadolinium released from the chelat in the body. This free gadolinium is thought to be the trigger for NSF. Other important factors are the stability of the gadolinium complex and furthermore the route of its elimination from the body. Partial elimination via the liver might be an additional protective mechanism. In conclusion, despite the NSF risk, contrast-enhanced MRI is a safe diagnostic procedure which can be used reliably and safely even in patients with severe renal failure, and does not necessarily have to be replaced by other methods.

  2. Gadolinium contrast agent-induced CD163+ ferroportin+ osteogenic cells in nephrogenic systemic fibrosis.

    PubMed

    Swaminathan, Sundararaman; Bose, Chhanda; Shah, Sudhir V; Hall, Kimberly A; Hiatt, Kim M

    2013-09-01

    Gadolinium-based contrast agents are linked to nephrogenic systemic fibrosis in patients with renal insufficiency. The pathology of nephrogenic systemic fibrosis is characterized by abnormal tissue repair: fibrosis and ectopic ossification. The mechanisms by which gadolinium could induce fibrosis and ossification are not known. We examined in vitro the effect of a gadolinium-based contrast agent on human peripheral blood mononuclear cells for phenotype and function relevant to the pathology of nephrogenic systemic fibrosis using immunofluorescence, flow cytometry, real-time PCR, and osteogenic assays. We also examined tissues from patients with nephrogenic systemic fibrosis, using IHC to identify the presence of cells with phenotype induced by gadolinium. Gadolinium contrast induced differentiation of human peripheral blood mononuclear cells into a unique cellular phenotype--CD163(+) cells expressing proteins involved in fibrosis and bone formation. These cells express fibroblast growth factor (FGF)23, osteoblast transcription factors Runt-related transcription factor 2, and osterix, and show an osteogenic phenotype in in vitro assays. We show in vivo the presence of CD163(+)/procollagen-1(+)/osteocalcin(+) cells in the fibrotic and calcified tissues of nephrogenic systemic fibrosis patients. Gadolinium contrast-induced CD163(+)/ferroportin(+)/FGF23(+) cells with osteogenic potential may play a role in systemic fibrosis and ectopic ossification in nephrogenic systemic fibrosis.

  3. Improvement of ESR dosimetry for thermal neutron beams through the addition of gadolinium.

    PubMed

    Brai, M; Marrale, M; Gennaro, G; Bartolotta, A; D'Oca, M C; Rosi, G

    2007-09-07

    In this paper, the addition of gadolinium is proposed as a useful tool to enhance the electron spin resonance (ESR) sensitivity of organic compounds to thermal neutrons. The target of this work is the detection, through the ESR technique, of the thermal neutron fluence in a mixed field of photons and neutrons. Gadolinium was chosen because it has a very high capture cross section to thermal neutrons; its nuclear reaction with thermal neutrons induces complex inner shell transitions that generate, besides other particles, Auger electrons, which in turn release their energy in the neighborhood (only several nanometers) of the place of reaction. Gadolinium was added to two organic molecules: alanine and ammonium tartrate. The main result obtained was a greater neutron sensitivity for dosimeters with gadolinium than for those without gadolinium for both organic molecules used. Since a dosimeter pair is required to discriminate between the two components of a mixed field, we studied the response of each dosimeter pair irradiated in a mixed field. Through a blind test we verified the usefulness of this dosimetric system and we obtained an estimate of the fluence in the mixed field with a relative uncertainty of 3%, when the pair composed of an alanine dosimeter and a dosimeter with alanine and gadolinium is used.

  4. Allergic-like breakthrough reactions to gadolinium contrast agents after corticosteroid and antihistamine premedication.

    PubMed

    Dillman, Jonathan R; Ellis, James H; Cohan, Richard H; Strouse, Peter J; Jan, Sophia C

    2008-01-01

    The objective of our study was to determine the number and severity of allergic-like breakthrough reactions to i.v. gadolinium-containing contrast agents in children and adults after premedication with corticosteroids and antihistamines. Contrast material reaction forms from the department of radiology for pediatric (under 19 years old) and adult patients were reviewed for the time period from January 1, 2001, through December 31, 2006. All documented allergic-like reactions to i.v. gadolinium-containing contrast media after premedication with corticosteroids and antihistamines were identified. Forms were evaluated for reaction manifestations, management, and patient outcome. Our institutional electronic medical record system was accessed for each individual patient to identify pertinent medical history, including demographic information, history of allergic-like reaction to contrast media (gadolinium- or iodine-containing), and additional factors that led to prophylactic premedication. Eight patients experienced nine allergic-like reactions after the i.v. administration of gadolinium-containing contrast media despite premedication. A single patient had two breakthrough reactions. Six breakthrough reactions were mild, and three were moderate. No severe or fatal breakthrough reaction occurred. Eight of nine breakthrough reactions occurred in adults. All patients who experienced breakthrough reactions had a history of allergic-like reaction to either gadolinium- or iodine-containing contrast media. Allergic-like reactions to gadolinium-containing contrast media can occur despite premedication with corticosteroids and antihistamines.

  5. High Levels of Gadolinium Deposition in the Skin of a Patient With Normal Renal Function.

    PubMed

    Roberts, Donna R; Lindhorst, Scott M; Welsh, Cynthia T; Maravilla, Kenneth R; Herring, Mary N; Braun, K Adam; Thiers, Bruce H; Davis, W Clay

    2016-05-01

    The aim of this study was to assess gadolinium deposition in the skin of a patient with normal renal function, based on estimated glomerular filtration rate values greater than 59 mL/min/1.73 m(2) after exposure to large cumulative doses of gadolinium-based contrast agents (GBCAs). The patient underwent 61 contrasted brain MRI scans over the course of 11 years. Skin biopsies from the forearm and lower extremity were analyzed with inductively coupled plasma mass spectrometry (ICP-MS), laser ablation ICP-MS, and hydrophilic interaction liquid chromatography ICP-MS. The ICP-MS demonstrated high levels of gadolinium deposition (14.5 ± 0.4 μg/g), similar to previously reported gadolinium levels within the skin of patients with nephrogenic systemic fibrosis. The laser ablation ICP-MS demonstrated deposition of gadolinium within the deep layers of skin. Speciation analysis using hydrophilic interaction liquid chromatography ICP-MS demonstrated the presence of intact gadolinium-chelate species, although most of the gadolinium present could not be further characterized. Light microscopy demonstrated increased CD34 immunoreactivity in the connective tissue septations of the subcutaneous adipose tissue. The patient had no history of skin disorders and did not have a history of nephrogenic systemic fibrosis but did have severe joint contractures of unknown etiology. Our results, in contradiction to published literature, suggest that in patients with normal renal function, exposure to GBCAs in extremely high cumulative doses can lead to significant gadolinium deposition in the skin. This finding is in line with more recent reports of gadolinium deposition in the brain of patients with normal renal function. Future studies are required to address possible clinical consequences of gadolinium deposition in the skin, brain, and potentially other organs in patients with normal renal function. We recommend, in addition to following current US Food and Drug Administration and

  6. Chemical and mass spectrographic analysis of nuclear-grade gadolinium oxide (Gd/sub 2/O/sub 3/) powder

    SciTech Connect

    Not Available

    1981-01-01

    Analytical procedures to determine compliance of gadolinium oxide powders with specifications are presented. The following methods are described in detail: carbon by direct combustion - thermal conductivity method; total chlorine and fluorine by pyrohydrolysis ion-selective electrode method; loss of weight on ignition; sulfur by combustion - iodometric titration method; impurity elements by a spark-source mass spectrographic method; and gadolinium content in gadolinium oxide by impurity correction method. (JMT)

  7. X-Ray Fluorescence Analysis of Yttrium-Iron-Gadolinium Solutions Used to Prepare Spray Dried Powders.

    DTIC Science & Technology

    IRON, * GADOLINIUM , *X RAY SPECTROSCOPY, *YTTRIUM, COMPUTER PROGRAMS, SOLUTIONS(MIXTURES), QUALITY CONTROL, NITRIC ACID, RARE EARTH ELEMENTS, CHEMICAL ANALYSIS, FERRITES , PHASE SHIFT CIRCUITS, YTTRIUM IRON GARNET.

  8. Gadolinium oxide nanoparticles as potential multimodal imaging and therapeutic agents.

    PubMed

    Kim, Tae Jeong; Chae, Kwon Seok; Chang, Yongmin; Lee, Gang Ho

    2013-01-01

    Potentials of hydrophilic and biocompatible ligand coated gadolinium oxide nanoparticles as multimodal imaging agents, drug carriers, and therapeutic agents are reviewed. First of all, they can be used as advanced T1 magnetic resonance imaging (MRI) contrast agents because they have r1 larger than those of Gd(III)-chelates due to a high density of Gd(III) per nanoparticle. They can be further functionalized by conjugating other imaging agents such as fluorescent imaging (FI), X-ray computed tomography (CT), positron emission tomography (PET), and single photon emission tomography (SPECT) agents. They can be also useful for drug carriers through morphology modifications. They themselves are also potential CT and ultrasound imaging (USI) contrast and thermal neutron capture therapeutic (NCT) agents, which are superior to commercial iodine compounds, air-filled albumin microspheres, and boron ((10)B) compounds, respectively. They, when conjugated with targeting agents such as antibodies and peptides, will provide enhanced images and be also very useful for diagnosis and therapy of diseases (so called theragnosis).

  9. Nanocrystalline gadolinium doped ceria: combustion synthesis and electrical characterization.

    PubMed

    Dutta, Atanu; Patra, Saheli; Bedekar, Vinila; Tyagi, A K; Basu, R N

    2009-05-01

    Twenty mol% gadolinium doped ceria powders were prepared by citrate-nitrate combustion synthesis technique. Two different sources of cerium viz. cerium nitrate and ammonium ceric nitrate were used in different oxidant-to-fuel ratios. The crystallite size of the synthesized powders ranged 5-27 nm was obtained depending on the preparation conditions with average particle size in the range 0.64-1.26 microm. Although, the powders were found to be agglomerated in nature, these powders were highly sinter-active as they showed very high sintered density (> or = 95%) when sintered at 1250 degrees C having grain size in the range of 200-500 nm. The electrical conductivity was found to depend on the temperature with two distinct regimes at a transition point of 350 degrees C. The grain boundary showed a significant role in the total conductivity with its activation energy dependent on the material preparation conditions. The activation energy of total conduction was found to be significantly low (-0.5 eV) in the temperature range of 400-700 degrees C, this property is unique for application as an electrolyte for solid oxide fuel cell operating in the low temperature range. It was found that a fuel-deficient combustion reaction using cerium nitrate as the oxidant yielded the best quality powder which showed a maximum electrical conductivity of -1.74 x 10(-2) S/cm at 600 degrees C.

  10. Ordered structures of defect clusters in gadolinium-doped ceria.

    PubMed

    Li, Zhi-Peng; Mori, Toshiyuki; Ye, Fei; Ou, Dingrong; Zou, Jin; Drennan, John

    2011-06-14

    The nano-domain, with short-range ordered structure, has been widely observed in rare-earth-doped ceria. Atomistic simulation has been employed to investigate the ordering structure of the nano-domain, as a result of aggregation and segregation of dopant cations and the associated oxygen vacancies in gadolinium-doped ceria. It is found that the binding energy of defect cluster increases as a function of cluster size, which provides the intrinsic driving force for the defect cluster growth. However, the ordered structures of the defect clusters are different from the chain model as previously reported. Adjacent oxygen vacancies prefer to locate along <110>/2 lattice vector, which results in a unique stable structure (isosceles triangle) formation. Such isosceles triangle structure can act as the smallest unit of cluster growth to form a symmetric dumbbell structure. This unique dumbbell structure is hence considered as a building block for the development of larger defect clusters, leading to nano-domain formation in rare-earth-doped ceria.

  11. Ordered structures of defect clusters in gadolinium-doped ceria

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Peng; Mori, Toshiyuki; Ye, Fei; Ou, Dingrong; Zou, Jin; Drennan, John

    2011-06-01

    The nano-domain, with short-range ordered structure, has been widely observed in rare-earth-doped ceria. Atomistic simulation has been employed to investigate the ordering structure of the nano-domain, as a result of aggregation and segregation of dopant cations and the associated oxygen vacancies in gadolinium-doped ceria. It is found that the binding energy of defect cluster increases as a function of cluster size, which provides the intrinsic driving force for the defect cluster growth. However, the ordered structures of the defect clusters are different from the chain model as previously reported. Adjacent oxygen vacancies prefer to locate along <110>/2 lattice vector, which results in a unique stable structure (isosceles triangle) formation. Such isosceles triangle structure can act as the smallest unit of cluster growth to form a symmetric dumbbell structure. This unique dumbbell structure is hence considered as a building block for the development of larger defect clusters, leading to nano-domain formation in rare-earth-doped ceria.

  12. Gadolinium-loaded gel scintillators for neutron and antineutrino detection

    SciTech Connect

    Riddle, Catherine Lynn; Akers, Douglas William; Demmer, Ricky Lynn; Paviet, Patricia Denise; Drigert, Mark William

    2016-11-29

    A gadolinium (Gd) loaded scintillation gel (Gd-ScintGel) compound allows for neutron and gamma-ray detection. The unique gel scintillator encompasses some of the best features of both liquid and solid scintillators, yet without many of the disadvantages associated therewith. Preferably, the gel scintillator is a water soluble Gd-DTPA compound and water soluble fluorophores such as: CdSe/ZnS (or ZnS) quantum dot (Q-dot) nanoparticles, coumarin derivatives 7-hydroxy-4-methylcoumarin, 7-hydroxy-4-methylcoumarin-3-acetic acid, 7-hydroxycoumarin-3-carboxylic acid, and Alexa Fluor 350 as well as a carbostyril compound, carbostyril 124 in a stable water-based gel, such as methylcellulose or polyacrylamide polymers. The Gd-loaded ScintGel allows for a homogenious distribution of the Gd-DTPA and the fluorophores, and yields clean fluorescent emission peaks. A moderator, such as deuterium or a water-based clear polymer, can be incorporated in the Gd-ScintGel. The gel scintillators can be used in compact detectors, including neutron and antineutrino detectors.

  13. Late Gadolinium Enhancement in Patients with Nonischemic Dilated Cardiomyopathy.

    PubMed

    Memon, Sarfaraz; Ganga, Harsha V; Kluger, Jeffrey

    2016-07-01

    One-third of all patients with heart failure have nonischemic dilated cardiomyopathy (NIDM). Five-year mortality from NIDM is as high as 20% with sudden cardiac death (SCD) as the cause in 30% of the deaths. Currently, the left ventricular ejection fraction (LVEF) is used as the main criteria to risk stratify patients requiring an implantable cardioverter defibrillator (ICD) to prevent SCD. However, LVEF does not necessarily reflect myocardial propensity for electrical instability leading to ventricular tachycardia (VT) or ventricular fibrillation (VF). Due to the differential risk in various subgroups of patients for arrhythmic death, it is important to identify appropriate patients for ICD implantation so that we can optimize healthcare resources and avoid the complications of ICDs in individuals who are unlikely to benefit. We performed a systematic search and review of clinical trials of NIDM and the use of ICDs and cardiac magnetic resonance imaging with late gadolinium enhancement (LGE) for risk stratification. LGE identifies patients with NIDM who are at high risk for SCD and enables optimized patient selection for ICD placement, while the absence of LGE may reduce the need for ICD implantation in patients with NIDM who are at low risk for future VF/VT or SCD.

  14. Impedance spectroscopic characterization of gadolinium substituted cobalt ferrite ceramics

    SciTech Connect

    Rahman, Md. T. Ramana, C. V.

    2014-10-28

    Gadolinium (Gd) substituted cobalt ferrites (CoFe{sub 2−x}Gd{sub x}O{sub 4}, referred to CFGO) with variable Gd content (x = 0.0–0.4) have been synthesized by solid state ceramic method. The crystal structure and impedance properties of CFGO compounds have been evaluated. X-ray diffraction measurements indicate that CFGO crystallize in the inverse spinel phase. The CFGO compounds exhibit lattice expansion due to substitution of larger Gd ions into the crystal lattice. Impedance spectroscopy analysis was performed under a wide range of frequency (f = 20 Hz–1 MHz) and temperature (T = 303–573 K). Electrical properties of Gd incorporated Co ferrite ceramics are enhanced compared to pure CoFe{sub 2}O{sub 4} due to the lattice distortion. Impedance spectroscopic analysis illustrates the variation of bulk grain and grain-boundary contributions towards the electrical resistance and capacitance of CFGO materials with temperature. A two-layer heterogeneous model consisting of moderately conducting grain interior (ferrite-phase) regions separated by insulating grain boundaries (resistive-phase) accurately account for the observed temperature and frequency dependent electrical characteristic of CFGO ceramics.

  15. Electronic transport in gadolinium atomic-size contacts

    NASA Astrophysics Data System (ADS)

    Olivera, B.; Salgado, C.; Lado, J. L.; Karimi, A.; Henkel, V.; Scheer, E.; Fernández-Rossier, J.; Palacios, J. J.; Untiedt, C.

    2017-02-01

    We report on the fabrication, transport measurements, and density functional theory (DFT) calculations of atomic-size contacts made of gadolinium (Gd). Gd is known to have local moments mainly associated with f electrons. These coexist with itinerant s and d bands that account for its metallic character. Here we explore whether and how the local moments influence electronic transport properties at the atomic scale. Using both scanning tunneling microscope and lithographic mechanically controllable break junction techniques under cryogenic conditions, we study the conductance of Gd when only few atoms form the junction between bulk electrodes made of the very same material. Thousands of measurements show that Gd has an average lowest conductance, attributed to single-atom contact, below 2/e2 h . Our DFT calculations for monostrand chains anticipate that the f bands are fully spin polarized and insulating and that the conduction may be dominated by s , p , and d bands. We also analyze the electronic transport for model nanocontacts using the nonequilibrium Green's function formalism in combination with DFT. We obtain an overall good agreement with the experimental results for zero bias and show that the contribution to the electronic transport from the f channels is negligible and that from the d channels is marginal.

  16. Gadolinium-Based Contrast Agents for MR Cancer Imaging

    PubMed Central

    Zhou, Zhuxian; Lu, Zheng-Rong

    2013-01-01

    Magnetic resonance imaging (MRI) is a clinical imaging modality effective for anatomical and functional imaging of diseased soft tissues, including solid tumors. MRI contrast agents have been routinely used for detecting tumor at an early stage. Gadolinium based contrast agents are the most commonly used contrast agents in clinical MRI. There have been significant efforts to design and develop novel Gd(III) contrast agents with high relaxivity, low toxicity and specific tumor binding. The relaxivity of the Gd(III) contrast agents can be increased by proper chemical modification. The toxicity of Gd(III) contrast agents can be reduced by increasing the agents’ thermodynamic and kinetic stability, as well as optimizing their pharmacokinetic properties. The increasing knowledge in the field of cancer genomics and biology provides an opportunity for designing tumor-specific contrast agents. Various new Gd(III) chelates have been designed and evaluated in animal models for more effective cancer MRI. This review outlines the design and development, physicochemical properties, and in vivo properties of several classes of Gd(III)-based MR contrast agents for tumor imaging. PMID:23047730

  17. DNA surface modified gadolinium phosphate nanoparticles as MRI contrast agents.

    PubMed

    Dumont, Matthieu F; Baligand, Celine; Li, Yichen; Knowles, Elisabeth S; Meisel, Mark W; Walter, Glenn A; Talham, Daniel R

    2012-05-16

    Oligonucleotide modified gadolinium phosphate nanoparticles have been prepared and their magnetic resonance relaxivity properties measured. Nanoparticles of GdPO4·H2O were synthesized in a water/oil microemulsion using IGEPAL CO-520 as surfactant, resulting in 50 to 100 nm particles that are highly dispersible and stable in water. Using surface modification chemistry previously established for zirconium phosphonate surfaces, the particles are directly modified with 5'-phosphate terminated oligonucleotides, and the specific interaction of the divalent phosphate with Gd(3+) sites at the surface is demonstrated. The ability of the modified nanoparticles to act as MRI contrast agents was determined by performing MR relaxivity measurements at 14.1 T. Solutions of nanopure water, Feridex, and Omniscan (FDA approved contrast agents) in 0.25% agarose were used for comparison and control purposes. MRI data confirm that GdPO4·H2O nanoparticles have relaxivities (r1, r2) comparable to those of commercially available contrast agents. In addition, the data suggest that biofunctionalization of the surface of the nanoparticles does not prevent their function as MRI contrast agents.

  18. Analytical Interference in Serum Iron Determination Reveals Iron Versus Gadolinium Transmetallation With Linear Gadolinium-Based Contrast Agents

    PubMed Central

    Fretellier, Nathalie; Poteau, Nathalie; Factor, Cécile; Mayer, Jean-François; Medina, Christelle; Port, Marc; Idée, Jean-Marc; Corot, Claire

    2014-01-01

    Objectives The purposes of this study were to evaluate the risk for analytical interference with gadolinium-based contrast agents (GBCAs) for the colorimetric measurement of serum iron (Fe3+) and to investigate the mechanisms involved. Materials and Methods Rat serum was spiked with several concentrations of all molecular categories of GBCAs, ligands, or “free” soluble gadolinium (Gd3+). Serum iron concentration was determined by 2 different colorimetric methods at pH 4.0 (with a Vitros DT60 analyzer or a Cobas Integra 400 analyzer). Secondly, the cause of interference was investigated by (a) adding free soluble Gd3+ or Mn2+ to serum in the presence of gadobenic acid or gadodiamide and (b) electrospray ionization mass spectrometry. Results Spurious decrease in serum Fe3+ concentration was observed with all linear GBCAs (only with the Vitros DT60 technique occurring at pH 4.0) but not with macrocyclic GBCAs or with free soluble Gd3+. Spurious hyposideremia was also observed with the free ligands present in the pharmaceutical solutions of the linear GBCAs gadopentetic acid and gadodiamide (ie, diethylene triamine pentaacetic acid and calcium-diethylene triamine pentaacetic acid bismethylamide, respectively), suggesting the formation of Fe-ligand chelate. Gadobenic acid-induced interference was blocked in a concentration-dependent fashion by adding a free soluble Gd3+ salt. Conversely, Mn2+, which has a lower affinity than Gd3+ and Fe3+ for the ligand of gadobenic acid (ie, benzyloxypropionic diethylenetriamine tetraacetic acid), was less effective (interference was only partially blocked), suggesting an Fe3+ versus Gd3+ transmetallation phenomenon at pH 4.0. Similar results were observed with gadodiamide. Mass spectrometry detected the formation of Fe-ligand with all linear GBCAs tested in the presence of Fe3+ and the disappearance of Fe-ligand after the addition of free soluble Gd3+. No Fe-ligand chelate was found in the case of the macrocyclic GBCA gadoteric

  19. Serum netrin-1 in relation to gadolinium-enhanced magnetic resonance imaging in early multiple sclerosis.

    PubMed

    Voortman, M M; Pekar, T; Bachmayer, D; Archelos, J-J; Stojakovic, T; Scharnagl, H; Ropele, S; Pichler, A; Enzinger, C; Fuchs, S; Fazekas, F; Seifert-Held, T; Khalil, M

    2017-01-01

    Netrin-1, a secreted laminin-related protein, is known to regulate not only axonal guidance and neuronal cell migration, but also blood-brain barrier integrity and inflammation. Two preliminary studies reported altered serum netrin-1 levels in multiple sclerosis; however, associations with longitudinal clinical and magnetic resonance imaging activity have not been investigated. We aimed to assess serum netrin-1 in multiple sclerosis and controls with respect to disease activity and its temporal dynamics. Serum netrin-1 was assessed by enzyme-linked immunosorbent assay in 79 patients with clinically isolated syndrome or multiple sclerosis, and 30 non-inflammatory neurological disease controls. In patients, serum samples were collected immediately prior to gadolinium-enhanced 3 T magnetic resonance imaging at two time points (initial contrast-enhancing gadolinium+ n = 47, non-enhancing gadolinium- n = 32; reference gadolinium- n = 70; median time-lag 1.4, interquartile range 1.0-2.3 years). Serum netrin-1 levels were similar in clinically isolated syndrome, multiple sclerosis and controls, and gadolinium+ and gadolinium- patients. Among gadolinium+ patients, serum netrin-1 was decreased in clinically active (n = 8) vs non-active patients (n = 39; p = 0.041). Serum netrin-1 showed no temporal dynamics in multiple sclerosis and was unrelated to clinical data. Serum netrin-1 levels show no multiple sclerosis specific changes and are not sensitive for detection of subclinical disease activity. Netrin-1 changes during relapses may deserve further examination.

  20. Surfactant-assisted hydrothermal synthesis of Eu(3+)-doped white light hydroxyl sodium yttrium tungstate microspheres and their conversion to NaY(WO(4))(2).

    PubMed

    Lei, Fang; Yan, Bing; Chen, Hao Hong; Zhao, Jing Tai

    2009-08-17

    In this work, large-scale three-dimensional "flake-ball" microarchitectures of Eu(3+) doped white light hydroxyl sodium yttrium tungstate were prepared by the well-known hydrothermal approach at 180 degrees C for 48 h in the presence of triblock-copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123). NaY(WO(4))(2):Eu(3+) phosphor was formed by annealing the hydrothermal product at approximately 630 degrees C for 2 h. A time-dependent microstructure evolution study was performed under hydrothermal reaction. The evolution process is the self-assembly process of P123, and the effects of other reaction parameters, such as influence of the concentration of P123 on morphology, and the influence of temperature on PL. The mechanism by which the "flake-ball" particles are formed is discussed in detail. The PL spectra of Eu(3+)-doped hydroxyl sodium yttrium tungstate phosphor contain two parts: the broad blue-green band and the (5)D(0)-->(7)F(J) (J = 1, and 2) characteristic transition of Eu(3+). This approach provides a facile route for the production of high-quality hydroxyl sodium yttrium tungstate microstructures with an interesting optical property.

  1. The presence of the gadolinium-based contrast agent depositions in the brain and symptoms of gadolinium neurotoxicity - A systematic review

    PubMed Central

    Olchowy, Cyprian; Cebulski, Kamil; Łasecki, Mateusz; Chaber, Radosław; Olchowy, Anna; Kałwak, Krzysztof; Zaleska-Dorobisz, Urszula

    2017-01-01

    Background and purpose Gadolinium based contrast agents (GBCAs) are widely used in magnetic resonance imaging, but recently, high signal intensity in the cerebellum structures was reported after repeated administrations of contrast- enhanced magnetic resonance images. The aim of this systematic review was to investigate the association between increased signal intensity in the dentate nucleus and globus pallidus in the brain and repeated administrations of GBCAs. Additionally, we focused on possible short- and long-term consequences of gadolinium use in those patients. Methods Systematic review of retrospective investigations in PubMed and Medline was performed in July 2016. Primary outcomes included the presence of increased signal intensity within the dentate nucleus and globus pallidus on unenhanced T1-weighted MR images in patients following administrations of GBCAs. Two independent reviewers were responsible for search and data extraction. Results 25 publications satisfied inclusion criteria (19 magnetic resonance images analyses, 3 case reports; 3 autopsy studies). Magnetic resonance images of 1247 patients with increased signal intensity on unenhanced T1-weighted MR images were analyzed as well as tissue specimens from 27 patients. Signal intensity correlated positively with the exposure to GBCAs and was greater after serial administrations of linear nonionic than cyclic contrast agents. Gadolinium was detected in all tissue examinations. Conclusions High signal intensity in the dentate nucleus and globus pallidus on unenhanced T1-weighted magnetic resonance images were associated with previous administration of GBCAs. Signal intensity correlated negatively with stability of contrast agents. Clinical significance of gadolinium deposition in the brain remains unclear. There is a strong need for further research to identify type of gadolinium deposited in the brain as well as to gather knowledge about long-term consequences. PMID:28187173

  2. Separation of bone from iodine- and gadolinium-based contrast agents using dual energy CT

    NASA Astrophysics Data System (ADS)

    Chong, Daniel Y.; Angel, Erin; Kim, Hyun J.; Cole, Graham B.; Boyadzhyan, Lousine; Panknin, Christoph; Gomez, Ana M.; Goldin, Jonathan G.; Brown, Matthew S.; McNitt-Gray, Michael F.

    2008-03-01

    This study aims to evaluate the separability of bone from iodine- and gadolinium-based intravenous contrast agents using dual energy CT techniques in a phantom. The phantom was prepared containing varying concentrations of iodine-based contrast, gadolinium-based contrast, and calcium hydroxyapatite (to simulate bone). Thirteen iodine concentrations from 0.1 to 12 mg/mL, twelve gadolinium concentrations from 0.72 to 34.42 mg/mL, and four calcium concentrations from 0 to 200 mg/mL were used. These phantoms were scanned on a dual source CT using two different source spectra, producing one set of data at 80 kVp and another at 140 kVp. On each resulting image, the mean HU was measured at every concentration level for iodine, gadolinium, and calcium, and plotted on a graph of HU value at 80 versus 140 kVp. Linear regression was used to produce a best-fit line for each material. These lines were compared to test for a difference of slopes between calcium and iodine as well as between calcium and gadolinium. Each material exhibited a linear relationship between the HU values at 140 and 80 kVp (R2 = 0.99) and demonstrated a unique slope to this line. The slope for iodine was 2.00, for gadolinium was 1.63, and for calcium was 1.55. The slopes of the calcium and iodine lines were significantly different (p < 0.05), while the slopes of the calcium and gadolinium lines were not significantly different (p > 0.05). Our results suggest that while it is technically feasible to separate iodine from bone, gadolinium-based contrast does not appear to be as readily separable from bone as iodine. This result is surprising as the atomic number and k-edge of calcium (Z = 20, k-edge = 4 keV) are closer to iodine (Z = 53, k-edge = 33 keV) than to gadolinium (Z = 64, k-edge = 50 keV).

  3. The dosimetric impact of gadolinium-based contrast media in GBM brain patient plans for a MRI-Linac

    NASA Astrophysics Data System (ADS)

    Bilal Ahmad, Syed; Paudel, Moti Raj; Sarfehnia, Arman; Kim, Anthony; Pang, Geordi; Ruschin, Mark; Sahgal, Arjun; Keller, Brian M.

    2017-08-01

    Dosimetric effects of gadolinium based contrast media (Gadovist) were evaluated for the Elekta MRI linear accelerator using the research version of the Monaco treatment planning system (TPS). In order to represent a gadolinium uptake, the contrast was manually assigned to a phantom as well as to the gross tumour volume (GTV) of 6 glioblastoma multiforme (GBM) patients. A preliminary estimate of the dose enhancement, due to gadolinium, was performed using the phantom irradiated with a single beam. A more complicated assessment was performed for the GBM patients using a 7 field IMRT technique. The material table in Monaco was modified in order to identify the presence of a non-biological material. The dose distribution was modelled using GPUMCD (MC algorithm in Monaco) for an unmodified (or default) material table (DMT) as well as for a modified (or custom) material table (CMT) for both the phantom and patients. Various concentrations ranging between 8 and 157 mg ml-1 were used to represent the gadolinium uptake in the patient’s GTV. It was assumed that the gadolinium concentration remained the same for the entire course of radiation treatment. Results showed that at the tissue-Gadovist interface, inside the phantom, dose scored using the DMT was 7% lower compared to that using the CMT for 157 mg ml-1 concentration of gadolinium. Dosimetric differences in the case of the patient study were measured using the DVH parameters. D 50% was higher by 6% when the DMT was used compared to the CMT for dose modelling for a gadolinium concentration of 157 mg ml-1. This difference decreased gradually with decreasing concentration of gadolinium. It was concluded that dosimetric differences can be quantified in Monaco if the tumour-gadolinium concentration is more than 23 mg ml-1. If the gadolinium concentration is lower than 23 mg ml-1, then a correction for the presence of gadolinium may not be necessary in the TPS.

  4. Compensated gadolinium-loaded plastic scintillators for thermal neutron detection (and counting)

    SciTech Connect

    Dumazert, Jonathan; Coulon, Romain; Bertrand, Guillaume H. V.; Hamel, Matthieu; Sguerra, Fabien; Dehe-Pittance, Chrystele; Normand, Stephane; Mechin, Laurence

    2015-07-01

    Plastic scintillator loading with gadolinium-rich organometallic complexes shows a high potential for the deployment of efficient and cost-effective neutron detectors. Due to the low-energy photon and electron signature of thermal neutron capture by gadolinium-155 and gadolinium-157, alternative treatment to Pulse Shape Discrimination has to be proposed in order to display a trustable count rate. This paper discloses the principle of a compensation method applied to a two-scintillator system: a detection scintillator interacts with photon radiation and is loaded with gadolinium organometallic compound to become a thermal neutron absorber, while a non-gadolinium loaded compensation scintillator solely interacts with the photon part of the incident radiation. Posterior to the nonlinear smoothing of the counting signals, a hypothesis test determines whether the resulting count rate after photon response compensation falls into statistical fluctuations or provides a robust image of a neutron activity. A laboratory prototype is tested under both photon and neutron irradiations, allowing us to investigate the performance of the overall compensation system in terms of neutron detection, especially with regards to a commercial helium-3 counter. The study reveals satisfactory results in terms of sensitivity and orientates future investigation toward promising axes. (authors)

  5. The use of iodinated and gadolinium contrast media during pregnancy and lactation.

    PubMed

    Webb, Judith A W; Thomsen, Henrik S; Morcos, Sameh K

    2005-06-01

    The use of iodinated or gadolinium-based contrast media in pregnant or lactating women often causes concerns in the radiology department because of the principle of not exposing a fetus or neonate to any drugs. Because of the uncertainty about the use of contrast media during pregnancy and lactation, the Contrast Media Safety Committee of the European Society of Urogenital Radiology decided to review the literature and draw up guidelines. An extensive literature search was carried out and summarized in a report. Based on the limited information available, simple guidelines have been drawn up. The report and guidelines were discussed at the 11th European Symposium on Urogenital Radiology in Santiago de Compostela, Spain. Mutagenic and teratogenic effects have not been described after administration of gadolinium or iodinated contrast media. Free iodide in radiographic contrast medium given to the mother has the potential to depress fetal/neonatal thyroid function. Neonatal thyroid function should be checked during the 1st week if iodinated contrast media have been given during pregnancy. No effect on the fetus has been seen after gadolinium contrast media. Only tiny amounts of iodinated or gadolinium-based contrast medium given to a lactating mother reach the milk, and only a minute proportion entering the baby's gut is absorbed. The very small potential risk associated with absorption of contrast medium may be considered insufficient to warrant stopping breast-feeding for 24 h following either iodinated or gadolinium contrast agents.

  6. Tumor-induced lymph node alterations detected by MRI lymphography using gadolinium nanoparticles.

    PubMed

    Partridge, S C; Kurland, B F; Liu, C-L; Ho, R J Y; Ruddell, A

    2015-10-26

    Contrast-enhanced MRI lymphography shows potential to identify alterations in lymph drainage through lymph nodes (LNs) in cancer and other diseases. MRI studies have typically used low molecular weight gadolinium contrast agents, however larger gadolinium-loaded nanoparticles possess characteristics that could improve the specificity and sensitivity of lymphography. The performance of three gadolinium contrast agents with different sizes and properties was compared by 3T MRI after subcutaneous injection. Mice bearing B16-F10 melanoma footpad tumors were imaged to assess tumor-induced alterations in lymph drainage through tumor-draining popliteal and inguinal LNs versus contralateral uninvolved drainage. Gadolinium lipid nanoparticles were able to identify tumor-induced alterations in contrast agent drainage into the popliteal LN, while lower molecular weight or albumin-binding gadolinium agents were less effective. All of the contrast agents distributed in foci around the cortex and medulla of tumor-draining popliteal LNs, while they were restricted to the cortex of non-draining LNs. Surprisingly, second-tier tumor-draining inguinal LNs exhibited reduced uptake, indicating that tumors can also divert LN drainage. These characteristics of tumor-induced lymph drainage could be useful for diagnosis of LN pathology in cancer and other diseases. The preferential uptake of nanoparticle contrasts into tumor-draining LNs could also allow selective targeting of therapies to tumor-draining LNs.

  7. Extraction of gadolinium from high flux isotope reactor control plates. [Alternative method

    SciTech Connect

    Kohring, M.W.

    1987-04-01

    Gadolinium-153 is an important radioisotope used in the diagnosis of various bone disorders. Recent medical and technical developments in the detection and cure of osteoporosis, a bone disease affecting an estimated 50 million people, have greatly increased the demand for this isotope. The Oak Ridge National Laboratory (ORNL) has produced /sup 153/Gd since 1980 primarily through the irradiation of a natural europium-oxide powder followed by the chemical separation of the gadolinium fraction from the europium material. Due to the higher demand for /sup 153/Gd, an alternative production method to supplement this process has been investigated. This process involves the extraction of gadolinium from the europium-bearing region of highly radioactive, spent control plates used at the High Flux Isotope Reactor (HFIR) with a subsequent re-irradiation of the extracted material for the production of the /sup 153/Gd. Based on the results of experimental and calculational analyses, up to 25 grams of valuable gadolinium (greater than or equal to60% enriched in /sup 152/Gd) resides in the europium-bearing region of the HFIR control components of which 70% is recoverable. At a specific activity yield of 40 curies of /sup 153/Gd for each gram of gadolinium re-irradiated, 700 one-curie sources can be produced from each control plate assayed.

  8. Tumor-induced lymph node alterations detected by MRI lymphography using gadolinium nanoparticles

    PubMed Central

    Partridge, S. C.; Kurland, B. F.; Liu, C.-L.; Ho, R. J. Y.; Ruddell, A.

    2015-01-01

    Contrast-enhanced MRI lymphography shows potential to identify alterations in lymph drainage through lymph nodes (LNs) in cancer and other diseases. MRI studies have typically used low molecular weight gadolinium contrast agents, however larger gadolinium-loaded nanoparticles possess characteristics that could improve the specificity and sensitivity of lymphography. The performance of three gadolinium contrast agents with different sizes and properties was compared by 3T MRI after subcutaneous injection. Mice bearing B16-F10 melanoma footpad tumors were imaged to assess tumor-induced alterations in lymph drainage through tumor-draining popliteal and inguinal LNs versus contralateral uninvolved drainage. Gadolinium lipid nanoparticles were able to identify tumor-induced alterations in contrast agent drainage into the popliteal LN, while lower molecular weight or albumin-binding gadolinium agents were less effective. All of the contrast agents distributed in foci around the cortex and medulla of tumor-draining popliteal LNs, while they were restricted to the cortex of non-draining LNs. Surprisingly, second-tier tumor-draining inguinal LNs exhibited reduced uptake, indicating that tumors can also divert LN drainage. These characteristics of tumor-induced lymph drainage could be useful for diagnosis of LN pathology in cancer and other diseases. The preferential uptake of nanoparticle contrasts into tumor-draining LNs could also allow selective targeting of therapies to tumor-draining LNs. PMID:26497382

  9. CHARACTERIZATION OF AN ADVANCED GADOLINIUM NEUTRON ABSORBER ALLOY BY MEANS OF NEUTRON TRANSMISSION

    SciTech Connect

    Gregg W. Wachs

    2007-09-01

    Neutron transmission experiments were performed on samples of an advanced nickel-chromium-molybdenum-gadolinium (Ni-Cr-Mo-Gd) neutron absorber alloy. The primary purpose of the experiments was to demonstrate the thermal neutron absorbing capability of the alloy at specific gadolinium dopant levels. The new alloy is to be deployed for criticality control of highly enriched DOE SNF. For the transmission experiments, alloy test samples were fabricated with 0.0, 1.58 and 2.1 wt% natural gadolinium dispersed in a Ni-Cr-Mo base alloy. The transmission experiments were successfully carried out at the Los Alamos Neutron Science Center (LANSCE). Measured data from the neutron transmission experiments were compared to calculated results derived from a simple exponential transmission formula using only radiative capture cross sections. Excellent agreement between the measured and calculated results demonstrated the expected strong thermal absorption capability of the gadolinium poison and in addition, verified the measured elemental composition of the alloy test samples. The good agreement also indirectly confirmed that the gadolinium was dispersed fairly uniformly in the alloy and the ENDF VII radiative capture cross section data were accurate.

  10. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    SciTech Connect

    Pierce, R. A.

    2012-03-12

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 °C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. At 25 °C, for 6 M HNO{sub 3}, 11 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2.5 g/L and 0.8 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}. The solubility of Gd in 4 M HNO{sub 3} with 0.15 M oxalate at 10 °C is about 1.5 g/L. For 6 M HNO{sub 3} with 0.15 M oxalate, the solubility of Gd at 10

  11. Magnetization and coercivity of nanocrystalline gadolinium iron garnet

    NASA Astrophysics Data System (ADS)

    Nguyet, Dao Thi Thuy; Duong, Nguyen Phuc; Satoh, Takuya; Anh, Luong Ngoc; Hien, Than Duc

    2013-04-01

    Gadolinium iron garnet (GdIG) nanoparticles with mean particle size of about 37 nm have been synthesized by citrate precursor gel formation followed by annealing at 800 °C for 2 hours. Magnetic behavior of clustered GdIG nanoparticles was studied in temperature range from 5 K to above Curie temperature. The sample shows a magnetization compensation temperature Tcomp˜286.5 K and a Curie temperature TC˜560 K. In comparison with the bulk saturation magnetization, the sample exhibits lower spontaneous magnetization in the temperature region from 5 K to Tcomp whereas higher spontaneous magnetization is observed at higher temperatures up to near the Curie point. The magnetization curves show a differential susceptibility in high fields which increases sharply below 50 K. At very low temperatures, irreversibility was observed in the magnetization loops, enduring in the fields up to ˜12.5 kOe. The spontaneous magnetization, high-field susceptibility and low-temperature irreversible effect were discussed based on a model for the interacting particles consisting of ferrimagnetically aligned core spins and disordered spins in surface layer which become frozen at low temperatures. We proposed a mechanism for the enhancement of the spontaneous magnetization above Tcomp in which the Gd and Fe spins in the surface layer are largely decoupled at high temperatures and the surface Fe spins realign to the magnetic moment of the core. The magnetic coercivity Hc at low temperatures is governed by the effective anisotropy whereas in the vicinity of the compensation point a peak in the coercive force shows up as a result of the so-called paraprocess with the maximum value of 1.2 kOe at Tcomp and by further increasing temperature the coercivity decreases and eventually vanishes at about 500 K. The interparticle interactions were found to play an important role in the hysteresis behavior of the sample.

  12. Gadolinium-Enhanced Magnetic Resonance Angiography for Pulmonary Embolism

    PubMed Central

    Stein, Paul D.; Chenevert, Thomas L.; Fowler, Sarah E.; Goodman, Lawrence R.; Gottschalk, Alexander; Hales, Charles A.; Hull, Russell D.; Jablonski, Kathleen A.; Leeper, Kenneth V.; Naidich, David P.; Sak, Daniel J.; Sostman, H. Dirk; Tapson, Victor F.; Weg, John G.; Woodard, Pamela K.

    2011-01-01

    Background The accuracy of gadolinium-enhanced magnetic resonance pulmonary angiography and magnetic resonance venography for diagnosing pulmonary embolism has not been determined conclusively. Objective To investigate performance characteristics of magnetic resonance angiography, with or without magnetic resonance venography, for diagnosing pulmonary embolism. Design Prospective, multicenter study from 10 April 2006 to 30 September 2008. (ClinicalTrials.gov registration number: NCT00241826) Setting 7 hospitals and their emergency services. Patients 371 adults with diagnosed or excluded pulmonary embolism. Measurements Sensitivity, specificity, and likelihood ratios were measured by comparing independently read magnetic resonance imaging with the reference standard for diagnosing pulmonary embolism. Reference standard diagnosis or exclusion was made by using various tests, including computed tomographic angiography and venography, ventilation–perfusion lung scan, venous ultra-sonography, D-dimer assay, and clinical assessment. Results Magnetic resonance angiography, averaged across centers, was technically inadequate in 25% of patients (92 of 371). The proportion of technically inadequate images ranged from 11% to 52% at various centers. Including patients with technically inadequate images, magnetic resonance angiography identified 57% (59 of 104) with pulmonary embolism. Technically adequate magnetic resonance angiography had a sensitivity of 78% and a specificity of 99%. Technically adequate magnetic resonance angiography and venography had a sensitivity of 92% and a specificity of 96%, but 52% of patients (194 of 370) had technically inadequate results. Limitation A high proportion of patients with suspected embolism was not eligible or declined to participate. Conclusion Magnetic resonance pulmonary angiography should be considered only at centers that routinely perform it well and only for patients for whom standard tests are contraindicated. Magnetic

  13. The structural response of gadolinium phosphate to pressure

    SciTech Connect

    Heffernan, Karina M.; Ross, Nancy L.; Spencer, Elinor C.; Boatner, Lynn A.

    2016-09-15

    Accurate elastic constants for gadolinium phosphate (GdPO{sub 4}) have been measured by single-crystal high-pressure diffraction methods. The bulk modulus of GdPO{sub 4} determined under hydrostatic conditions, 128.1(8) GPa (K′=5.8(2)), is markedly different from that obtained with GdPO{sub 4} under non-hydrostatic conditions (160(2) GPa), which indicates the importance of shear stresses on the elastic response of this phosphate. High pressure Raman and diffraction analysis indicate that the PO{sub 4} tetrahedra behave as rigid units in response to pressure and that contraction of the GdPO{sub 4} structure is facilitated by bending/twisting of the Gd–O–P links that result in increased distortion in the GdO{sub 9} polyhedra. - Graphical abstract: A high-pressure single crystal diffraction study of GdPO{sub 4} with the monazite structure is presented. The elastic behaviour of rare-earth phosphates are believed to be sensitive to shear forces. The bulk modulus of GdPO{sub 4} measured under hydrostatic conditions is 128.1(8) GPa. Compression of the structure is facilitated by bending/twisting of the Gd−O−P links that result in increased distortion in the GdO{sub 9} polyhedra. Display Omitted - Highlights: • The elastic responses of rare-earth phosphates are sensitive to shear forces. • The bulk modulus of GdPO{sub 4} measured under hydrostatic conditions is 128.1(8) GPa. • Twisting of the inter-polyhedral links allows compression of the GdPO{sub 4} structure. • Changes to the GdO{sub 9} polyhedra occur in response to pressure (<7.0 GPa).

  14. Biodistribution of ultra small gadolinium-based nanoparticles as theranostic agent: application to brain tumors.

    PubMed

    Miladi, Imen; Duc, Géraldine Le; Kryza, David; Berniard, Aurélie; Mowat, Pierre; Roux, Stéphane; Taleb, Jacqueline; Bonazza, Pauline; Perriat, Pascal; Lux, François; Tillement, Olivier; Billotey, Claire; Janier, Marc

    2013-09-01

    Gadolinium-based nanoparticles are novel objects with interesting physical properties, allowing their use for diagnostic and therapeutic applications. Gadolinium-based nanoparticles were imaged following intravenous injection in healthy rats and rats grafted with 9L gliosarcoma tumors using magnetic resonance imaging and scintigraphic imaging. Quantitative biodistribution using gamma-counting of each sampled organ confirmed that these nanoparticles were rapidly cleared essentially by renal excretion. Accumulation of these nanoparticles in 9L gliosarcoma tumors implanted in the rat brain was quantitated. This passive and long-duration accumulation of gadolinium-based nanoparticles in tumor, which is related to disruption of the blood-brain barrier, is in good agreement with the use of these nanoparticles as radiosensitizers for brain tumors.

  15. Measurement of gamma-ray production from thermal neutron capture on gadolinium for neutrino experiments

    NASA Astrophysics Data System (ADS)

    Yano, Takatomi

    2017-02-01

    Recently, several scientific applications of gadolinium are found in neutrino physics experiments. Gadolinium-157 is the nucleus, which has the largest thermal neutron capture cross-section among all stable nuclei. Gadolinium-155 also has the large cross-section. These neutron capture reactions provide the gamma-ray cascade with the total energy of about 8 MeV. This reaction is applied for several neutrino experiments, e.g. reactor neutrino experiments and Gd doped large water Cherenkov detector experiments, to recognize inverse-beta-decay reaction. A good Gd(n,γ) simulation model is needed to evaluate the detection efficiency of the neutron capture reaction, i.e. the efficiency of IBD detection. In this presentation, we will report the development and study status of a Gd(n,γ) calculation model and comparison with our experimental data taken at ANNRI/MLF beam line, J-PARC.

  16. The High Radiosensitizing Efficiency of a Trace of Gadolinium-Based Nanoparticles in Tumors

    PubMed Central

    Dufort, Sandrine; Le Duc, Géraldine; Salomé, Murielle; Bentivegna, Valerie; Sancey, Lucie; Bräuer-Krisch, Elke; Requardt, Herwig; Lux, François; Coll, Jean-Luc; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier

    2016-01-01

    We recently developed the synthesis of ultrasmall gadolinium-based nanoparticles (GBN), (hydrodynamic diameter <5 nm) characterized by a safe behavior after intravenous injection (renal clearance, preferential accumulation in tumors). Owing to the presence of gadolinium ions, GBN can be used as contrast agents for magnetic resonance imaging (MRI) and as radiosensitizers. The attempt to determine the most opportune delay between the intravenous injection of GBN and the irradiation showed that a very low content of radiosensitizing nanoparticles in the tumor area is sufficient (0.1 μg/g of particles, i.e. 15 ppb of gadolinium) for an important increase of the therapeutic effect of irradiation. Such a promising and unexpected result is assigned to a suited distribution of GBN within the tumor, as revealed by the X-ray fluorescence (XRF) maps. PMID:27411781

  17. Modeling gadolinium-bearing fuel in Ringhals PWRs using CASMO/SIMULATE

    SciTech Connect

    Kurcyusz, E. )

    1993-01-01

    Ringhals units 2, 3, and 4 are Westinghouse three-loop, 157-assembly pressurized water reactors (PWRs) operated by Vattenfall. Originally, all three reactors were loaded in an out-in scheme using reload fuel without burnable poisons. In recent cycles, gadolinium-bearing fuel was introduced to enable a low-leakage loading pattern and minimize fuel cycle costs. This paper focuses on the Fragema 17 x 17 AFA design with peripheral gadolinium rods loaded in units 3 and 4. The Ringhals units are modeled using the Studsvik core management system, consisting of the CASMO-3 transport theory lattice physics code,and the SIMULATE-3 advanced nodal reactor analysis code. The results of the studies verifying the accuracy of CASMO-3/SIMULATE-3 on the assemblies with peripheral gadolinium rods are presented in this paper. The verification was carried out against CASMO-3 color-set calculations and measured reactor data.

  18. The High Radiosensitizing Efficiency of a Trace of Gadolinium-Based Nanoparticles in Tumors

    NASA Astrophysics Data System (ADS)

    Dufort, Sandrine; Le Duc, Géraldine; Salomé, Murielle; Bentivegna, Valerie; Sancey, Lucie; Bräuer-Krisch, Elke; Requardt, Herwig; Lux, François; Coll, Jean-Luc; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier

    2016-07-01

    We recently developed the synthesis of ultrasmall gadolinium-based nanoparticles (GBN), (hydrodynamic diameter <5 nm) characterized by a safe behavior after intravenous injection (renal clearance, preferential accumulation in tumors). Owing to the presence of gadolinium ions, GBN can be used as contrast agents for magnetic resonance imaging (MRI) and as radiosensitizers. The attempt to determine the most opportune delay between the intravenous injection of GBN and the irradiation showed that a very low content of radiosensitizing nanoparticles in the tumor area is sufficient (0.1 μg/g of particles, i.e. 15 ppb of gadolinium) for an important increase of the therapeutic effect of irradiation. Such a promising and unexpected result is assigned to a suited distribution of GBN within the tumor, as revealed by the X-ray fluorescence (XRF) maps.

  19. A role for tungsten in the biology of Campylobacter jejuni: tungstate stimulates formate dehydrogenase activity and is transported via an ultra-high affinity ABC system distinct from the molybdate transporter.

    PubMed

    Smart, Jonathan P; Cliff, Matthew J; Kelly, David J

    2009-11-01

    The food-borne pathogen Campylobacter jejuni possesses no known tungstoenzymes, yet encodes two ABC transporters (Cj0300-0303 and Cj1538-1540) homologous to bacterial molybdate (ModABC) uptake systems and the tungstate transporter (TupABC) of Eubacterium acidaminophilum respectively. The actual substrates and physiological role of these transporters were investigated. Tryptophan fluorescence spectroscopy and isothermal titration calorimetry of the purified periplasmic binding proteins of each system revealed that while Cj0303 is unable to discriminate between molybdate and tungstate (K(D) values for both ligands of 4-8 nM), Cj1540 binds tungstate with a K(D) of 1.0 +/- 0.2 pM; 50 000-fold more tightly than molybdate. Induction-coupled plasma mass spectroscopy of single and double mutants showed that this large difference in affinity is reflected in a lower cellular tungsten content in a cj1540 (tupA) mutant compared with a cj0303c (modA) mutant. Surprisingly, formate dehydrogenase (FDH) activity was decreased approximately 50% in the tupA strain, and supplementation of the growth medium with tungstate significantly increased FDH activity in the wild type, while inhibiting known molybdoenzymes. Our data suggest that C. jejuni possesses a specific, ultra-high affinity tungstate transporter that supplies tungsten for incorporation into FDH. Furthermore, possession of two MoeA paralogues may explain the formation of both molybdopterin and tungstopterin in this bacterium.

  20. Photoluminescence in solid solutions and thin films of tungstates CaWO{sub 4}-CdWO{sub 4}

    SciTech Connect

    Taoufyq, A.; Mauroy, V.; Guinneton, F.; Valmalette, J-C.; Fiorido, T.; Benlhachemi, A.; Lyoussi, A.; Nolibe, G.; Gavarri, J-R.

    2015-07-01

    In this study, we present two types of studies on the luminescence properties under UV and X-ray excitations of solid solutions Ca{sub 1-x}Cd{sub x}WO{sub 4} and of thin layers of CaWO{sub 4} and CdWO{sub 4}. These tungstate based solid solutions are susceptible to be integrated into new radiation sensors, in order to be used in different fields of applications such as reactor measurements, safeguards, homeland security, nuclear nondestructive assays, LINAC emission radiation measurement. However these complex materials were rarely investigated in the literature. One first objective of our studies was to establish correlations between luminescence efficiency, chemical substitution and the degree of crystallization resulting from elaboration conditions. A second objective will be to determine the efficiency of luminescence properties of thin layers of these materials. In the present work, we focus our attention on the role of chemical substitution on photon emissions under UV and X-ray irradiations. The luminescence spectra of Ca{sub 1-x}Cd{sub x}WO{sub 4} polycrystalline materials have been investigated at room temperature as a function of composition (0≤x≤1). In addition, we present a preliminary study of the luminescence of CaWO{sub 4} and CdWO{sub 4} thin layers: oscillations observed in the case of X-ray excitations in the luminescence spectra are discussed. (authors)

  1. Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal

    PubMed Central

    Osewski, Pawel; Belardini, Alessandro; Petronijevic, Emilija; Centini, Marco; Leahu, Grigore; Diduszko, Ryszard; Pawlak, Dorota A.; Sibilia, Concita

    2017-01-01

    Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities. PMID:28338074

  2. Enhanced structural and optical properties of the polyaniline-calcium tungstate (PANI-CaWO4 nanocomposite for electronics applications

    NASA Astrophysics Data System (ADS)

    Sabu, N. Aloysius; Francis, Xavier; Anjaly, Jose; Sankararaman, S.; Varghese, Thomas

    2017-06-01

    In this article, we report the synthesis and characterization of polyaniline-calcium tungstate nanocomposite, a novel material for potential applications. The PANI-CaWO4 nanocomposite was prepared by in situ oxidative polymerization of aniline in the presence of CaWO4 nanoparticles dispersed in ethanol. Investigations using X-ray diffraction, Fourier-transformed infrared spectroscopy, UV-visible, photoluminescence and Raman spectroscopy confirmed the formation of the nanocomposite of PANI with CaWO4 nanoparticles. Scanning electron microscopy revealed almost uniform distribution of CaWO4 nanoparticles in the polyaniline matrix. These studies also confirmed electronic structure modification as a result of incorporating CaWO4 nanoparticles in PANI. Composite formation resulted in large decrease in the optical band gap and enhanced photoluminescence. The augmented structural, optical and photoluminescence properties of the PANI-CaWO4 nanocomposite can be used to explore potential applications in micro- and optoelectronics. This is the first report presenting synthesis and characterization of the PANI-CaWO4 nanocomposite.

  3. Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal

    NASA Astrophysics Data System (ADS)

    Osewski, Pawel; Belardini, Alessandro; Petronijevic, Emilija; Centini, Marco; Leahu, Grigore; Diduszko, Ryszard; Pawlak, Dorota A.; Sibilia, Concita

    2017-03-01

    Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities.

  4. Zirconium(IV) tungstate nanoparticles prepared through chemical co-precipitation method and its function as solid acid catalyst

    NASA Astrophysics Data System (ADS)

    Sadanandan, Manoj; Bhaskaran, Beena

    2014-08-01

    In this paper, we report the synthesis of zirconium(IV) tungstate nanoparticles, a new and efficient catalyst for the oxidation of benzyl alcohol and esterification of acetic acid with various alcohols. The nanoparticle catalyst was prepared using the room temperature chemical co-precipitation method. The catalyst was characterized with thermogravimetric and differential thermal analysis, elemental analysis, X-ray diffraction analysis (XRD), fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and the Brunauer-Emmett-Teller (BET) surface area. The crystallite size was found to be ~20 nm as revealed by XRD, HRTEM and AFM. The Na+ exchange capacity was found to be 2.76 meq g-1 and the surface area of the compound measured using BET method was found to be 250-265 m2 g-1. The high value of ion exchange capacity indicates the presence of surface hydroxyl groups. The prepared nanoparticles have proven to be excellent catalysts for both oxidation and ester synthesis under mild reaction conditions. The mechanism of the catalytic reaction was studied as well.

  5. Self-Phase-Matched Second-Harmonic and White-Light Generation in a Biaxial Zinc Tungstate Single Crystal.

    PubMed

    Osewski, Pawel; Belardini, Alessandro; Petronijevic, Emilija; Centini, Marco; Leahu, Grigore; Diduszko, Ryszard; Pawlak, Dorota A; Sibilia, Concita

    2017-03-24

    Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities.

  6. Radioprotective effects of sodium tungstate on hematopoietic injury by exposure to 60Co gamma-rays in Wistar rats.

    PubMed

    Sato, K; Ichimasa, M; Miyahara, K; Shiomi, M; Nishimura, Y; Ichimasa, Y

    1999-06-01

    Radioprotective effects of sodium tungstate (ST) on 60Co gamma-ray induced decrease in hematocrit value and in survival rate in Wistar strain male rats were examined. A long-term administration of ST (less than 150 mg/kg body weight/day) for 60-300 days had no significant effects on body and organs weights and survival days. The LD50/60 in 20 weeks old rats was 220 mg/kg body weight/day. Daily administration of 38, 75 or 150 mg from 7 days before and after irradiation to 60 days significantly mitigated the decrease in hematocrit values, especially at 23 days after irradiation (P < 0.05). The highest mitigation rate of the decrease in hematocrit value was observed in rats administered at a dose of 38 mg ST/day. Simultaneously, a dose of 38 mg ST/day inhibited lethal effect of 60Co gamma-rays significantly. The dose-reduction factor for survival of 38 mg ST administered rats was 1.14.

  7. Synthesis of bismuth tungstate (Bi{sub 2}WO{sub 6}) nanoflakes and their field emission investigation

    SciTech Connect

    Kolhe, P. S.; Sonawane, K. M.; Bankar, P. K.; Gavhane, D. S.; More, M. A.; Maiti, N.

    2016-05-23

    The nanoflakes of Bismuth Tungstate (Bi{sub 2}WO{sub 6}) were successfully synthesized by a one-step facile hydrothermal route without using any templates or surfactants and field emission investigations of the Bi{sub 2}WO{sub 6} nanoflakes emitter are reported. Structural and morphological analysis of as-synthesized Bi{sub 2}WO{sub 6} nanoflakes has been carried out using X-ray diffraction (XRD) and scanning electron microscope (SEM). Moreover, the field emission characteristics of the Bi{sub 2}WO{sub 6} nanoflakes are found to be superior to the other semiconductor emitters. The synthesized Bi{sub 2}WO{sub 6} nanoflakes emitter delivers current density of ~222.35 μA/cm{sup 2} at an applied electric field of ~7.2 V/μm. The emission current stability investigated at pre-set value of ~2 μA is observed to be fairly good. These observed results demonstrate potential candidate of the Bi{sub 2}WO{sub 6} cathode as an electron source for practical applications in vacuum microelectronic device.

  8. Lasing properties of selectively pumped Raman-active Nd{sup 3+}-doped molybdate and tungstate crystals

    SciTech Connect

    Basiev, Tasoltan T; Doroshenko, Maxim E; Ivleva, Lyudmila I; Osiko, Vyacheslav V; Kosmyna, M B; Komar', V K; Sulc, J; Jelinkova, H

    2006-08-31

    The lasing efficiency of Nd{sup 3+} ions is studied in laser materials capable of self-Raman frequency conversion. The lasing properties of tungstate and molybdate crystals with the scheelite structure (SrWO{sub 4}, BaWO{sub 4}, PbWO{sub 4}, SrMoO{sub 4}, PbMoO{sub 4}) activated with neodymium ions are investigated upon longitudinal pumping by a 750-nm alexandrite laser or a 800-nm diode laser. The slope lasing efficiency obtained for a Nd{sup 3+}:PbMoO{sub 4} laser emitting at 1054 nm is 54.3% for the total lasing efficiency of 46%, which is the best result for all the crystals with the scheelite structure studied so far. The simultaneous Q-switched lasing and self-Raman frequency conversion were demonstrated in neodymium-doped SrWO{sub 4}, PbWO{sub 4}, and BaWO{sub 4} crystals. (papers devoted to the 90th anniversary of a.m.prokhorov)

  9. Zirconium tungstate/epoxy resin nanocomposites with negative coefficient of thermal expansion for all-dielectric cryogenic temperature sensors

    NASA Astrophysics Data System (ADS)

    See, Erich; Kochergin, Vladimir; Neely, Lauren; Zayetnikov, Madrakhim; Ciovati, Gianluigi; Robinson, Hans

    2012-02-01

    The α-phase of zirconium tungstate (ZrW2O8) has the remarkable property that its coefficient of thermal expansion (CTE) is negative over its entire range of thermal stability (0-1050K), and through this range it has a nearly constant negative CTE. When ZrW2O8 nanoparticles are mixed into a polymer resin, the resulting composite has a reduced CTE when compared with that of the pure polymer. However, previous research on such composites has occurred only near room temperature. We show that at cryogenic temperatures, it is possible to make ZrW2O8/resin nanocomposites with negative CTE. By coating a fiber-optic Bragg grating with such a composite, we were able to create an all-optical temperature sensor without the use of metals, which would be of particular use in superconducting RF cavities. The sensor has sensitivity down to at least 2 K, six times lower than previous fiber-optic temperature sensors.

  10. Influence of La/W ratio on electrical conductivity of lanthanum tungstate with high La/W ratio

    NASA Astrophysics Data System (ADS)

    Kojo, Gen; Shono, Yohei; Ushiyama, Hiroshi; Oshima, Yoshito; Otomo, Junichiro

    2017-04-01

    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., 2.7×10-3 S cm-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 diffusion 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.

  11. Non-thermal damage to lead tungstate induced by intense short-wavelength laser radiation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Vozda, Vojtech; Boháček, Pavel; Burian, Tomáš; Chalupský, Jaromir; Hájková, Vera; Juha, Libor; Vyšín, Ludek; Gaudin, Jérôme; Heimann, Philip A.; Hau-Riege, Stefan P.; Jurek, Marek; Klinger, Dorota; Krzywinski, Jacek; Messerschmidt, Marc; Moeller, Stefan P.; Nagler, Robert; Pelka, Jerzy B.; Rowen, Michael; Schlotter, William F.; Swiggers, Michele L.; Sinn, Harald; Sobierajski, Ryszard; Tiedtke, Kai; Toleikis, Sven; Tschentscher, Thomas; Turner, Joshua J.; Wabnitz, Hubertus; Nelson, Art J.; Kozlova, Maria V.; Vinko, Sam M.; Whitcher, Thomas; Dzelzainis, Thomas; Renner, Oldrich; Saksl, Karel; Fäustlin, Roland R.; Khorsand, Ali R.; Fajardo, Marta; Iwan, Bianca S.; Andreasson, Jakob; Hajdu, Janos; Timneanu, Nicusor; Wark, Justin S.; Riley, David; Lee, Richard W.; Nagasono, Mitsuru; Yabashi, Makina

    2017-05-01

    Interaction of short-wavelength free-electron laser (FEL) beams with matter is undoubtedly a subject to extensive investigation in last decade. During the interaction various exotic states of matter, such as warm dense matter, may exist for a split second. Prior to irreversible damage or ablative removal of the target material, complicated electronic processes at the atomic level occur. As energetic photons impact the target, electrons from inner atomic shells are almost instantly photo-ionized, which may, in some special cases, cause bond weakening, even breaking of the covalent bonds, subsequently result to so-called non-thermal melting. The subject of our research is ablative damage to lead tungstate (PbWO4) induced by focused short-wavelength FEL pulses at different photon energies. Post-mortem analysis of complex damage patterns using the Raman spectroscopy, atomic-force (AFM) and Nomarski (DIC) microscopy confirms an existence of non-thermal melting induced by high-energy photons in the ionic monocrystalline target. Results obtained at Linac Coherent Light Source (LCLS), Free-electron in Hamburg (FLASH), and SPring-8 Compact SASE Source (SCSS) are presented in this Paper.

  12. Contrasting behaviour of anthropogenic gadolinium and natural rare earth elements in estuaries and the gadolinium input into the North Sea

    NASA Astrophysics Data System (ADS)

    Kulaksız, Serkan; Bau, Michael

    2007-08-01

    All major rivers in northwestern Germany that flow into the North Sea, including the Weser River, display rare earth element (REE) patterns with large positive gadolinium (Gd) anomalies that indicate the presence of anthropogenic Gd derived from contrast agents used in magnetic resonance imaging. This microcontaminant cannot be removed by common sewage treatment technology and enters rivers and lakes with the discharge from waste water treatment plants. As elsewhere, a large fraction of the natural dissolved REE in the Weser River are associated with colloids. These colloids aggregate during mixing of freshwater and seawater in the low-salinity part of the Weser Estuary and the dissolved REE are partially removed from the river water together with the colloids. In marked contrast to the natural REE, the anthropogenic Gd behaves conservatively during this estuarine mixing and transits through the Weser Estuary almost unaffected. This indicates that the speciation of anthropogenic Gd is different from that of natural Gd and suggests a long environmental half-life of the anthropogenic Gd complexes used as contrast agents. The amount of anthropogenic Gd introduced into seawater via rivers is significant and produces anthropogenic positive Gd anomalies in coastal seawater. This is observed in the southwestern North Sea, off the coast of the East Frisian Islands, where anthropogenic Gd is mostly derived from the rivers Rhine and Thames. Its long environmental half-life and conservative estuarine behaviour suggest that anthropogenic Gd might be utilized as a pseudo-natural far-field tracer for truly dissolved riverine REE input into seawater and for discharge from waste water treatment plants and for sewage in river, ground and drinking water. The widespread distribution of anthropogenic Gd is an example of how the increasing use of "exotic" (ultra)trace elements in high-tech processes will in the future significantly hamper studies of the distribution and geochemical

  13. Dislocation associated incubational domain formation in lightly gadolinium-doped ceria.

    PubMed

    Li, Zhi-Peng; Mori, Toshiyuki; Ye, Fei; Ou, Ding Rong; Zou, Jin; Drennan, John

    2011-02-01

    Nanosized incubational domain was observed in 10 at.% gadolinium-doped ceria (GDC) using high-resolution transmission electron microscopy. Dislocations were extensively observed in 10 at.% GDC instead of heavily doped 25 at.% GDC. By Fast Fourier Transform and Inverse Fast Fourier Transform analysis, it was noticed that the incubational domain existing in 10 at.% GDC has different lattice spacing and orientation from the neighboring ceria matrix. Furthermore, dislocations were usually observed in the interface region between the incubational domain and the ceria matrix. Based on experimental results, the formation mechanism of dislocation associated incubational domain in lightly gadolinium-doped ceria is rationalized.

  14. Structural, morphological and optical investigations on Sm{sup 3+} doped gadolinium oxide nanorods

    SciTech Connect

    Boopathi, G.; Mohan, R.; Raj, S. Gokul; Kumar, G. Ramesh

    2014-04-24

    One dimensional uniform Sm{sup 3+} doped gadolinium hydroxide nanorods have been prepared via simple co– precipitation technique at 60 °C temperature for 1 hour. The samples were calcinated at 750 °C to obtain Sm{sup 3+} doped gadolinium oxide nanorods. The 1D nanorods were then subjected to different characterization techniques to ascertain its structural stability and its morphology were investigated using high–resolution transmission electron microscopy. Photoluminescence (PL) spectrophotometry was investigated and the obtained results were discussed in detail.

  15. Misconnections in the Critically Ill: Injection of High-Dose Gadolinium into an External Ventricular Drain.

    PubMed

    Singh, Sumit; Rejai, Sepehr; Antongiorgi, Zarah; Gonzalez, Nestor; Stelzner, Matthias

    2016-03-01

    We report an unfortunate case of accidental administration of intrathecal gadolinium through an external ventricular drain in a postcraniotomy patient during magnetic resonance imaging of the brain. The incident occurred after the venous contrast line was connected mistakenly to the ventricular drainage catheter. The patient subsequently developed confusion, aphasia, and right facial droop with new computed tomography evidence of diffuse cerebral edema and stroke. Review of the magnetic resonance image revealed the inappropriate presence of subarachnoid gadolinium. Despite all interventions, the patient developed irreversible neurologic disability. We address the clinical sequelae, management strategies, and factors contributing to the catheter misconnection that led to this event.

  16. Gadolinium-conjugated gold nanoshells for multimodal diagnostic imaging and photothermal cancer therapy.

    PubMed

    Coughlin, Andrew J; Ananta, Jeyarama S; Deng, Nanfu; Larina, Irina V; Decuzzi, Paolo; West, Jennifer L

    2014-02-12

    Multimodal imaging offers the potential to improve diagnosis and enhance the specificity of photothermal cancer therapy. Toward this goal, gadolinium-conjugated gold nanoshells are engineered and it is demonstrated that they enhance contrast for magnetic resonance imaging, X-ray, optical coherence tomography, reflectance confocal microscopy, and two-photon luminescence. Additionally, these particles effectively convert near-infrared light to heat, which can be used to ablate cancer cells. Ultimately, these studies demonstrate the potential of gadolinium-nanoshells for image-guided photothermal ablation.

  17. Structural and optical properties of Nd{sup 3+} doped gadolinium oxide 1D nanorods

    SciTech Connect

    Boopathi, G. Mohan, R.; Raj, S. Gokul; Kumar, G. Ramesh

    2014-04-24

    Neodymium doped gadolinium hydroxide [Nd:Gd(OH)3] nanorods were successfully synthesized at 60 °C through co-precipitation method. The dopant percentage was maintained at 5% and calcination was done at 750 °C temperature for 1 hour to form the respective neodymium doped gadolinium oxide [Nd:Gd{sub 2}O{sub 3}] nanorods. The as-formed and annealed products were investigated in detail by using powder X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM) with an energy dispersive X-ray spectrum (EDX), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) spectrophotometry.

  18. Gadolinium-Conjugated Gold Nanoshells for Multimodal Diagnostic Imaging and Photothermal Cancer Therapy

    PubMed Central

    Coughlin, Andrew J.; Ananta, Jeyarama S.; Deng, Nanfu; Larina, Irina V.; Decuzzi, Paolo

    2014-01-01

    Multimodal imaging offers the potential to improve diagnosis and enhance the specificity of photothermal cancer therapy. Toward this goal, we have engineered gadolinium-conjugated gold nanoshells and demonstrated that they enhance contrast for magnetic resonance imaging, X-Ray, optical coherence tomography, reflectance confocal microscopy, and two-photon luminescence. Additionally, these particles effectively convert near-infrared light to heat, which can be used to ablate cancer cells. Ultimately, these studies demonstrate the potential of gadolinium-nanoshells for image-guided photothermal ablation. PMID:24115690

  19. Magnetic studies of a detonation nanodiamond with the surface modified by gadolinium ions

    NASA Astrophysics Data System (ADS)

    Osipov, V. Yu.; Aleksenskiy, A. E.; Takai, K.; Vul', A. Ya.

    2015-11-01

    The diamond nanoparticle surface is modified with Gd(III) ions by ion exchange with carboxyl group protons during the reaction of nanodiamond hydrosol with an aqueous solution of gadolinium nitrate. The results of the study by electron paramagnetic resonance and static magnetization measurements at low temperatures confirm the attachment of gadolinium ions to the surface of the diamond particle ˜5 nm in size. A spatial model of the arrangement of ions, in which the ion is located away from the surface by no more than 0.4 nm, is proposed.

  20. Dark-blood late gadolinium enhancement without additional magnetization preparation.

    PubMed

    Holtackers, Robert J; Chiribiri, Amedeo; Schneider, Torben; Higgins, David M; Botnar, René M

    2017-08-23

    This study evaluates a novel dark-blood late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) method, without using additional magnetization preparation, and compares it to conventional bright-blood LGE, for the detection of ischaemic myocardial scar. LGE is able to clearly depict myocardial infarction and macroscopic scarring from viable myocardium. However, due to the bright signal of adjacent left ventricular blood, the apparent volume of scar tissue can be significantly reduced, or even completely obscured. In addition, blood pool signal can mimic scar tissue and lead to false positive observations. Simply nulling the blood magnetization by choosing shorter inversion times, leads to a negative viable myocardium signal that appears equally as bright as scar due to the magnitude image reconstruction. However, by combining blood magnetization nulling with the extended grayscale range of phase-sensitive inversion-recovery (PSIR), a darker blood signal can be achieved whilst a dark myocardium and bright scar signal is preserved. LGE was performed in nine male patients (63 ± 11y) using a PSIR pulse sequence, with both conventional viable myocardium nulling and left ventricular blood nulling, in a randomized order. Regions of interest were drawn in the left ventricular blood, viable myocardium, and scar tissue, to assess contrast-to-noise ratios. Maximum scar transmurality, scar size, circumferential scar angle, and a confidence score for scar detection and maximum transmurality were also assessed. Bloch simulations were performed to simulate the magnetization levels of the left ventricular blood, viable myocardium, and scar tissue. Average scar-to-blood contrast was significantly (p < 0.001) increased by 99% when nulling left ventricular blood instead of viable myocardium, while scar-to-myocardium contrast was maintained. Nulling left ventricular blood also led to significantly (p = 0.038) higher expert confidence in scar detection

  1. A Manganese Alternative to Gadolinium for MRI Contrast.

    PubMed

    Gale, Eric M; Atanasova, Iliyana P; Blasi, Francesco; Ay, Ilknur; Caravan, Peter

    2015-12-16

    Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) are routinely used to diagnose soft tissue and vascular abnormalities. However, safety concerns limit the use of iodinated and gadolinium (Gd)-based CT and MRI contrast media in renally compromised patients. With an estimated 14% of the US population suffering from chronic kidney disease (CKD), contrast media compatible with renal impairment is sorely needed. We present the new manganese(II) complex [Mn(PyC3A)(H2O)](-) as a Gd alternative. [Mn(PyC3A)(H2O)](-) is among the most stable Mn(II) complexes at pH 7.4 (log KML = 11.40). In the presence of 25 mol equiv of Zn at pH 6.0, 37 °C, [Mn(PyC3A)(H2O)](-) is 20-fold more resistant to dissociation than [Gd(DTPA)(H2O)](2-). Relaxivity of [Mn(PyC3A)(H2O)](-) in blood plasma is comparable to commercial Gd contrast agents. Biodistribution analysis confirms that [Mn(PyC3A)(H2O)](-) clears via a mixed renal/hepatobiliary pathway with >99% elimination by 24 h. [Mn(PyC3A)(H2O)](-) was modified to form a bifunctional chelator and 4 chelates were conjugated to a fibrin-specific peptide to give Mn-FBP. Mn-FBP binds the soluble fibrin fragment DD(E) with Kd = 110 nM. Per Mn relaxivity of Mn-FBP is 4-fold greater than [Mn(PyC3A)(H2O)](-) and increases 60% in the presence of fibrin, consistent with binding. Mn-FBP provided equivalent thrombus enhancement to the state of the art Gd analogue, EP-2104R, in a rat model of arterial thrombosis. Mn metabolite analysis reveals no evidence of dechelation and the probe was >99% eliminated after 24 h. [Mn(PyC3A)(H2O)](-) is a lead development candidate for an imaging probe that is compatible with renally compromised patients.

  2. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    SciTech Connect

    Pierce, R.

    2012-02-22

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. For 6 M HNO{sub 3}, 10.5 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2 g/L and 0.25 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}.

  3. Syntheses, structures, magnetism, and optical properties of gadolinium scandium chalcogenides

    SciTech Connect

    Jin Gengbang; Choi, Eun Sang; Albrecht-Schmitt, Thomas E.

    2009-05-15

    Three gadolinium scandium chalcogenides have been synthesized using Sb{sub 2}Q{sub 3} (Q=S, Se) fluxes at 975 deg. C. Gd{sub 3.04}Sc{sub 0.96}S{sub 6}, GdScS{sub 3}, and Gd{sub 1.05}Sc{sub 0.95}Se{sub 3} are crystallized in U{sub 3}ScS{sub 6} type, GdFeO{sub 3} type, and UFeS{sub 3} type structures, respectively. The magnetic susceptibilities for these compounds follow the Curie-Weiss law above their transition temperatures. The effective magnetic moments are close to calculated values for free Gd{sup 3+} ions. The Weiss constants for Gd{sub 3.04}Sc{sub 0.96}S{sub 6}, GdScS{sub 3}, and Gd{sub 1.05}Sc{sub 0.95}Se{sub 3} are determined to be -3.3(1), -4.5(4), and 1.5(1) K, respectively. Gd{sub 3.04}Sc{sub 0.96}S{sub 6} orders antiferromagnetically below 9 K. GdScS{sub 3} exhibits an antiferromagnetic ordering below 3 K with a weak ferromagnetism. Gd{sub 1.05}Sc{sub 0.95}Se{sub 3} undergoes a ferromagnetic transition around 5 K. The optical band gaps for Gd{sub 3.04}Sc{sub 0.96}S{sub 6}, GdScS{sub 3}, and Gd{sub 1.05}Sc{sub 0.95}Se{sub 3} are 1.5, 2.1, and 1.2 eV, respectively. - Graphical abstract: A view of the three-dimensional structure of Gd{sub 3.04}Sc{sub 0.96}S{sub 6} along the c axis.

  4. A Manganese Alternative to Gadolinium for MRI Contrast

    PubMed Central

    Gale, Eric M.; Atanasova, Iliyana P.; Blasi, Francesco; Ay, Ilknur; Caravan, Peter

    2016-01-01

    Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) are routinely used to diagnose soft tissue and vascular abnormalities. However safety concerns limit the use of iodinated and gadolinium- (Gd) based CT and MRI contrast media in renally compromised patients. With an estimated 14% of the US population suffering from chronic kidney disease (CKD), contrast media compatible with renal impairment is sorely needed. We present the new manganese(II) complex [Mn(PyC3A)(H2O)]- as a Gd alternative. [Mn(PyC3A)(H2O)]- is amongst the most stable Mn(II) complexes at pH 7.4 (log KML = 11.40). In the presence of 25 mol equiv. Zn at pH 6.0, 37 °C, [Mn(PyC3A)(H2O)]- is 20-fold more resistant to dissociation than [Gd(DTPA)(H2O)]2-. Relaxivity of [Mn(PyC3A)(H2O)]- in blood plasma is comparable to commercial Gd contrast agents. Biodistribution analysis confirms that [Mn(PyC3A)(H2O)]- clears via a mixed renal/ hepatobiliary pathway with >99% elimination by 24h. [Mn(PyC3A)(H2O)]- was modified to form a bifunctional chelator and 4 chelates were conjugated to a fibrin-specific peptide to give Mn-FBP. Mn-FBP binds the soluble fibrin fragment DD(E) with Kd = 110 nM. Per Mn relaxivity of Mn-FBP is 4-fold greater than [Mn(PyC3A)(H2O)]- and increases 60% in the presence of fibrin, consistent with binding. Mn-FBP provided equivalent thrombus enhancement to the state of the art Gd analog, EP-2104R, in a rat model of arterial thrombosis. Mn metabolite analysis reveals no evidence of dechelation and the probe was >99% eliminated after 24 hr. [Mn(PyC3A)(H2O)]- is a lead development candidate for an imaging probe that is compatible with renally compromised patients. PMID:26588204

  5. Immunotoxic effects of sodium tungstate dihydrate on female B6C3F1/N mice when administered in drinking water.

    PubMed

    Frawley, Rachel P; Smith, Matthew J; White, Kimber L; Elmore, Susan A; Herbert, Ron; Moore, Rebecca; Staska, Lauren M; Behl, Mamta; Hooth, Michelle J; Kissling, Grace E; Germolec, Dori R

    2016-09-01

    Tungsten is a naturally occurring, high-tensile strength element that has been used in a number of consumer products. Tungsten has been detected in soil, waterways, groundwater, and human tissue and body fluids. Elevated levels of tungsten in urine were reported for populations exposed to tungstate in drinking water in areas where natural tungsten formations were prevalent. Published reports indicated that sodium tungstate may modulate hematopoiesis, immune cell populations, and immune responses in rodent models. The objective of this study was to assess potential immunotoxicity of sodium tungstate dihydrate (STD), a drinking water contaminant. Female B6C3F1/N mice received 0-2000 mg STD/L in their drinking water for 28 d, and were evaluated for effects on immune cell populations in spleen and bone marrow, and humoral-mediated, cell-mediated, and innate immunity. Three different parameters of cell-mediated immunity were similarly affected at 1000 mg STD/L. T-cell proliferative responses against allogeneic leukocytes and anti-CD3 were decreased 32%, and 21%, respectively. Cytotoxic T-lymphocyte activity was decreased at all effector:target cell ratios examined. At 2000 mg STD/L, the absolute numbers of CD3(+) T-cell progenitor cells in bone marrow were increased 86%, but the alterations in B-lymphocyte and other progenitor cells were not significant. There were no effects on bone marrow DNA synthesis or colony forming capabilities. STD-induced effects on humoral-mediated immunity, innate immunity, and splenocyte sub-populations were limited. Enhanced histopathology did not detect treatment-related lesions in any of the immune tissues. These data suggest exposure to STD in drinking water may adversely affect cell-mediated immunity.

  6. Tissue deposition of gadolinium and development of NSF: a convergence of factors.

    PubMed

    Perazella, Mark A

    2008-01-01

    Gadolinium-based contrast (GBC) exposure has recently been linked to the development of nephrogenic systemic fibrosis (NSF) in patients with underlying kidney disease and may in fact be the previously unrecognized trigger for the fibrosing process. As NSF is fairly rare in this patient population, a number of permissive factors are likely required for GBC exposure to initiate fibrosis. Advanced kidney disease is an absolute requirement whereas vascular injury and an inflammatory state, and a mix of co-factors including increased serum phosphate and calcium concentrations and iron overload further enhance risk. The combination of these events allows excess circulating gadolinium, which dissociates from its chelate to leak out of vessels and deposit in tissues. Free or bound tissue gadolinium, a rare earth metal of the lanthanoid series, promotes fibrosis via either direct binding to the collagen helix or, once the metal has been engulfed by macrophages, through the production of free oxygen radicals, cytokines, and other profibrotic factors that attract circulating fibrocytes to tissues. These fibrocytes then differentiate into fibroblast-like spindle cells that produce connective tissue matrix and other angiogenic and growth factors that further enhance tissue fibrosis. Direct gadolinium activation of transglutaminases on these tissue fibroblast-like cells may also promote fibrosis.

  7. A Polymeric Fastener can Easily Functionalize Liposome Surfaces with Gadolinium for Enhanced Magnetic Resonance Imaging

    PubMed Central

    Smith, Cartney E.; Shkumatov, Artem; Withers, Sarah G.; Glockner, James F.; Misra, Sanjay; Roy, Edward J.; Wong, Chun-Ho; Zimmerman, Steven C.; Kong, Hyunjoon

    2013-01-01

    Common methods of loading magnetic resonance imaging (MRI) contrast agents into nanoparticles often suffer from challenges related to particle formation, complex chemical modification/purification steps, and reduced contrast efficiency. This study presents a simple, yet advanced process to address these issues by loading gadolinium, an MRI contrast agent, exclusively on a liposome surface using a polymeric fastener. The fastener, so named for its ability to physically link the two functional components together, consisted of chitosan substituted with diethylenetriaminepentaacetic acid (DTPA) to chelate gadolinium, as well as octadecyl chains to stabilize the modified chitosan on the liposome surface. The assembly strategy, mimicking the mechanisms by which viruses and proteins naturally anchor to a cell, provided greater T1 relaxivity than liposomes loaded with gadolinium in both the interior and outer leaflet. Gadolinium-coated liposomes were ultimately evaluated in vivo using murine ischemia models to highlight the diagnostic capability of the system. Taken together, this process decouples particle assembly and functionalization, and therefore has considerable potential to enhance imaging quality while alleviating many of the difficulties associated with multifunctional particle fabrication. PMID:24083377

  8. [Physico-chemical and toxicological profile of gadolinium chelates as contrast agents for magnetic resonance imaging].

    PubMed

    Idée, J-M; Fretellier, N; Thurnher, M M; Bonnemain, B; Corot, C

    2015-07-01

    Gadolinium chelates (GC) are contrast agents widely used to facilitate or to enable diagnosis using magnetic resonance imaging (MRI). From a regulatory viewpoint, GC are drugs. GC have largely contributed to the success of MRI, which has become a major component of clinician's diagnostic armamentarium. GC are not metabolised and are excreted by the kidneys. They distribute into the extracellular compartment. Because of its high intrinsic toxicity, gadolinium must be administered as a chelate. GC can be classified according to two key molecular features: (a) nature of the chelating moiety: either macrocyclic molecules in which gadolinium is caged in the pre-organized cavity of the ligand, or linear, open-chain molecules, (b) ionicity: Gd chelates can be ionic (meglumine or sodium salts) or non-ionic. The thermodynamic and kinetic stabilities of the various GCs differ according to these structural characteristics. The kinetic stability of macrocyclic GCs is much higher than that of linear GCs and the thermodynamic stability of ionic GCs is generally higher than that of non-ionic GC, thus leading to a lower risk of gadolinium dissociation. This class of drugs has enjoyed an excellent reputation in terms of safety for a long time, until a causal link with a recently-described serious disease, nephrogenic systemic fibrosis (NSF), was evidenced. It is acknowledged that the vast majority of NSF cases are related to the administration of some linear CG in renally-impaired patients. Health authorities, worldwide, released recommendations which drastically reduced the occurrence of new cases.

  9. Gadolinium chloride as a contrast agent for imaging wood composite components by magnetic resonance

    Treesearch

    Thomas L. Eberhardt; Chi-Leung So; Andrea Protti; Po-Wah So

    2009-01-01

    Although paramagnetic contrast agents have an established track record in medical uses of magnetic resonance imaging (MRI), only recently has a contrast agent been used for enhancing MRI images of solid wood specimens. Expanding on this concept, wood veneers were treated with a gadolinium-based contrast agent and used in a model system comprising three-ply plywood...

  10. Use of gadolinium chloride as a contrast agent for imaging spruce knots by magnetic resonance

    Treesearch

    Thomas L. Eberhardt; Chi-Leung So; Amy H. Herlihy; Po-Wah So

    2006-01-01

    Treatments of knot-containing spruce wood blocks with a paramagnetic salt, gadolinium (III) chloride, in combination with solvent pretreatments, were evaluated as strategies to enhance the visualization of wood features by magnetic resonance imaging (MRI). Initial experiments with clear wood and excised knot samples showed differences in moisture uptake after...

  11. Gadolinium-enhanced computed tomography cystogram to diagnose bladder augment rupture in patients with iodine sensitivity.

    PubMed

    Newport, John Paul; Dusseault, Beau N; Butler, Carina; Pais, Vernon M

    2008-05-01

    Anaphylactic reaction to iodinated contrast is a potentially life-threatening complication of diagnostic imaging studies. We report the successful use of gadolinium as an alternative contrast agent for computed tomography cystogram in a patient with a history of anaphylactic reaction to iodinated contrast. This technique allowed us rapidly to diagnose a rupture of her bladder augmentation and pursue operative repair.

  12. Gadolinium-labeled quantum dots for molecular magnetic resonance imaging: R1 versus R2 mapping.

    PubMed

    Oostendorp, Marlies; Douma, Kim; Hackeng, Tilman M; Post, Mark J; van Zandvoort, Marc A M J; Backes, Walter H

    2010-07-01

    Quantum dots labeled with paramagnetic gadolinium chelates can be applied as contrast agent for preclinical molecular MRI combined with fluorescence microscopy. Besides increasing the longitudinal relaxation rate, gadolinium-labeled quantum dots may increase the transverse relaxation rate, which might be related to their magnetic properties. Furthermore, molecular MRI experiments are primarily conducted at high magnetic fields, where longitudinal relaxation rate becomes less effective, and the use of transverse relaxation rate as a source of contrast may become attractive. Consequently, the optimal method of contrast enhancement using gadolinium-labeled quantum dots is a priori unknown. The objective of this study was to compare longitudinal relaxation rate- and transverse relaxation rate-based contrast enhancement, proton visibility, and changes thereof induced by gadolinium-labeled quantum dots targeted to the angiogenic vasculature of murine tumors, using in vivo longitudinal and transverse relaxation rate mapping. At a field strength of 7 T, longitudinal relaxation rate-based measures were superior to transverse relaxation rate-based measures in detecting both the level and spatial extent of contrast agent-induced relaxation rate changes. (c) 2010 Wiley-Liss, Inc.

  13. Removal of gadolinium, a neutron poison from the moderator system of nuclear reactors.

    PubMed

    Rufus, A L; Kumar, Padma S; Jeena, K; Velmurugan, S

    2017-08-03

    Gadolinium as gadolinium nitrate is used as neutron poison in the moderator system for regulating and controlling the power generation of Pressurized Heavy Water Reactors (PHWR) and proposed to be used in Advanced Heavy Water Reactors (AHWR) owing to its high neutron absorption cross section. Removal of the added gadolinium nitrate (Gd(3+) and NO3(-)) from the system after its intended use is done using ion exchange resins. In the present investigation, attempts have been made to optimize the ion exchange process for generation of low radioactive waste and maximize utilization of the ion exchange resins by employing different types of resins and different modes of operation. The investigations revealed that use of mixed bed (MB) resin column consisting of Strong Acid Cation (SAC) resin and Strong Base Anion (SBA) resin followed by SAC resin column is efficient in removing the Gd(3+) and NO3(-) from the system besides maintaining the pH of the moderator system in the desirable regime, where gadolinium does not get precipitated as its hydroxide. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Preparation of 152Gd targets from a small quantity of gadolinium oxide in a pyrochemical reaction

    NASA Astrophysics Data System (ADS)

    Lipski, A. R.

    1995-02-01

    A simple method utilizing small amounts (< 5 mg) of isotopically enriched material for the production of gadolinium targets is discussed. An electrostatically focused e-gun is used in the procedure in which 152Gd 2O 3 powder undergoes reduction-distillation and deposition onto an Fe foil.

  15. Myocardial late gadolinium enhancement in specific cardiomyopathies by cardiovascular magnetic resonance: a preliminary experience.

    PubMed

    Silva, Caterina; Moon, James C; Elkington, Andrew G; John, Anna S; Mohiaddin, Raad H; Pennell, Dudley J

    2007-12-01

    Late gadolinium enhancement cardiovascular magnetic resonance (CMR) can visualize myocardial interstitial abnormalities. The aim of this study was to assess whether regions of abnormal myocardium can also be visualized by late enhancement gadolinium CMR in the specific cardiomyopathies. A retrospective review of all referrals for gadolinium CMR with specific cardiomyopathy over 20 months. Nine patients with different specific cardiomyopathies were identified. Late enhancement was demonstrated in all patients, with a mean signal intensity of 390 +/- 220% compared with normal regions. The distribution pattern of late enhancement was unlike the subendocardial late enhancement related to coronary territories found in myocardial infarction. The affected areas included papillary muscles (sarcoid), the mid-myocardium (Anderson-Fabry disease, glycogen storage disease, myocarditis, Becker muscular dystrophy) and the global sub-endocardium (systemic sclerosis, Loeffler's endocarditis, amyloid, Churg-Strauss). Focal myocardial late gadolinium enhancement is found in the specific cardiomyopathies, and the pattern is distinct from that seen in infarction. Further systematic studies are warranted to assess whether the pattern and extent of late enhancement may aid diagnosis and prognostic assessment.

  16. Criticality experiments with low enriched UO/sub 2/ fuel rods in water containing dissolved gadolinium

    SciTech Connect

    Bierman, S.R.; Murphy, E.S.; Clayton, E.D.; Keay, R.T.

    1984-02-01

    The results obtained in a criticality experiments program performed for British Nuclear Fuels, Ltd. (BNFL) under contract with the United States Department of Energy (USDOE) are presented in this report along with a complete description of the experiments. The experiments involved low enriched UO/sub 2/ and PuO/sub 2/-UO/sub 2/ fuel rods in water containing dissolved gadolinium, and are in direct support of BNFL plans to use soluble compounds of the neutron poison gadolinium as a primary criticality safeguard in the reprocessing of low enriched nuclear fuels. The experiments were designed primarily to provide data for validating a calculation method being developed for BNFL design and safety assessments, and to obtain data for the use of gadolinium as a neutron poison in nuclear chemical plant operations - particularly fuel dissolution. The experiments program covers a wide range of neutron moderation (near optimum to very under-moderated) and a wide range of gadolinium concentration (zero to about 2.5 g Gd/l). The measurements provide critical and subcritical k/sub eff/ data (1 greater than or equal to k/sub eff/ greater than or equal to 0.87) on fuel-water assemblies of UO/sub 2/ rods at two enrichments (2.35 wt % and 4.31 wt % /sup 235/U) and on mixed fuel-water assemblies of UO/sub 2/ and PuO/sub 2/-UO/sub 2/ rods containing 4.31 wt % /sup 235/U and 2 wt % PuO/sub 2/ in natural UO/sub 2/ respectively. Critical size of the lattices was determined with water containing no gadolinium and with water containing dissolved gadolinium nitrate. Pulsed neutron source measurements were performed to determine subcritical k/sub eff/ values as additional amounts of gadolinium were successively dissolved in the water of each critical assembly. Fission rate measurements in /sup 235/U using solid state track recorders were made in each of the three unpoisoned critical assemblies, and in the near-optimum moderated and the close-packed poisoned assemblies of this fuel.

  17. Development of radiopure cadmium tungstate crystal scintillators from enriched {sup 106}Cd and {sup 116}Cd to search for double beta decay

    SciTech Connect

    Danevich, F. A.; Boiko, R. S.; Chernyak, D. M.; Kobychev, V. V.; Kropivyansky, B. N.; Mokina, V. M.; Nikolaiko, A. S.; Poda, D. V.; Podviyanuk, R. B.; Tretyak, V. I.; Barabash, A. S.; Konovalov, S. I.; Umatov, V. I.; Belli, P.; Bernabei, R.; D'Angelo, S.; Brudanin, V. B.; Cappella, F.; Incicchitti, A.; Caracciolo, V.; and others

    2013-08-08

    Cadmium tungstate crystal scintillators enriched in {sup 106}Cd up to 66% ({sup 106}CdWO{sub 4}) and in {sup 116}Cd up to 82% ({sup 116}CdWO{sub 4}) have been developed. The low radioactive contamination of the crystals measured on the level of ≤ 1.5 mBq/kg ({sup 40}K), ≤ 0.005 - 0.012 mBq/kg ({sup 226}Ra), 0.04 - 0.07 mBq/kg ({sup 228}Th) allows to carry out high sensitivity experiments to search for double beta processes in {sup 106}Cd and {sup 116}Cd.

  18. Decavanadate, decaniobate, tungstate and molybdate interactions with sarcoplasmic reticulum Ca(2+)-ATPase: quercetin prevents cysteine oxidation by vanadate but does not reverse ATPase inhibition.

    PubMed

    Fraqueza, Gil; Batista de Carvalho, Luís A E; Marques, M Paula M; Maia, Luisa; Ohlin, C André; Casey, William H; Aureliano, Manuel

    2012-11-07

    Recently we demonstrated that the decavanadate (V(10)) ion is a stronger Ca(2+)-ATPase inhibitor than other oxometalates, such as the isoelectronic and isostructural decaniobate ion, and the tungstate and molybdate monomer ions, and that it binds to this protein with a 1 : 1 stoichiometry. The V(10) interaction is not affected by any of the protein conformations that occur during the process of calcium translocation (i.e. E1, E1P, E2 and E2P) (Fraqueza et al., J. Inorg. Biochem., 2012). In the present study, we further explore this subject, and we can now show that the decaniobate ion, [Nb(10) = Nb(10)O(28)](6-), is a useful tool in deducing the interaction and the non-competitive Ca(2+)-ATPase inhibition by the decavanadate ion [V(10) = V(10)O(28)](6-). Moreover, decavanadate and vanadate induce protein cysteine oxidation whereas no effects were detected for the decaniobate, tungstate or molybdate ions. The presence of the antioxidant quercetin prevents cysteine oxidation, but not ATPase inhibition, by vanadate or decavanadate. Definitive V(IV) EPR spectra were observed for decavanadate in the presence of sarcoplasmic reticulum Ca(2+)-ATPase, indicating a vanadate reduction at some stage of the protein interaction. Raman spectroscopy clearly shows that the protein conformation changes that are induced by V(10), Nb(10) and vanadate are different from the ones induced by molybdate and tungstate monomer ions. Here, Mo and W cause changes similar to those by phosphate, yielding changes similar to the E1P protein conformation. The putative reduction of vanadium(V) to vanadium(IV) and the non-competitive binding of the V(10) and Nb(10) decametalates may explain the differences in the Raman spectra compared to those seen in the presence of molybdate or tungstate. Putting it all together, we suggest that the ability of V(10) to inhibit the Ca(2+)-ATPase may be at least in part due to the process of vanadate reduction and associated protein cysteine oxidation. These

  19. High sensitivity of late gadolinium enhancement for predicting microscopic myocardial scarring in biopsied specimens in hypertrophic cardiomyopathy.

    PubMed

    Konno, Tetsuo; Hayashi, Kenshi; Fujino, Noboru; Nagata, Yoji; Hodatsu, Akihiko; Masuta, Eiichi; Sakata, Kenji; Nakamura, Hiroyuki; Kawashiri, Masa-aki; Yamagishi, Masakazu

    2014-01-01

    Myocardial scarring can be assessed by cardiac magnetic resonance imaging with late gadolinium enhancement and by endomyocardial biopsy. However, accuracy of late gadolinium enhancement for predicting microscopic myocardial scarring in biopsied specimens remains unknown in hypertrophic cardiomyopathy. We investigated whether late gadolinium enhancement in the whole heart reflects microscopic myocardial scarring in the small biopsied specimens in hypertrophic cardiomyopathy. Twenty-one consecutive patients with hypertrophic cardiomyopathy who were examined both by cardiac magnetic resonance imaging and by endomyocardial biopsy were retrospectively studied. The right interventricular septum was the target site for endomyocardial biopsy in all patients. Late gadolinium enhancement in the ventricular septum had an excellent sensitivity (100%) with a low specificity (40%) for predicting microscopic myocardial scarring in biopsied specimens. The sensitivity of late gadolinium enhancement in the whole heart remained 100% with a specificity of 27% for predicting microscopic myocardial scarring in biopsied specimens. Quantitative assessments of fibrosis revealed that the extent of late gadolinium enhancement in the whole heart was the only independent variable related to the microscopic collagen fraction in biopsied specimens (β  =  0.59, 95% confident interval: 0.15 - 1.0, p  =  0.012). Although there was a compromise in the specificity, the sensitivity of late gadolinium enhancement was excellent for prediction of microscopic myocardial scarring in hypertrophic cardiomyopathy. Moreover, the severity of late gadolinium enhancement was independently associated with the quantitative collagen fraction in biopsied specimens in hypertrophic cardiomyopathy. These findings indicate that late gadolinium enhancement can reflect both the presence and the extent of microscopic myocardial scarring in the small biopsied specimens in hypertrophic cardiomyopathy.

  20. High Sensitivity of Late Gadolinium Enhancement for Predicting Microscopic Myocardial Scarring in Biopsied Specimens in Hypertrophic Cardiomyopathy

    PubMed Central

    Konno, Tetsuo; Hayashi, Kenshi; Fujino, Noboru; Nagata, Yoji; Hodatsu, Akihiko; Masuta, Eiichi; Sakata, Kenji; Nakamura, Hiroyuki; Kawashiri, Masa-aki; Yamagishi, Masakazu

    2014-01-01

    Background Myocardial scarring can be assessed by cardiac magnetic resonance imaging with late gadolinium enhancement and by endomyocardial biopsy. However, accuracy of late gadolinium enhancement for predicting microscopic myocardial scarring in biopsied specimens remains unknown in hypertrophic cardiomyopathy. We investigated whether late gadolinium enhancement in the whole heart reflects microscopic myocardial scarring in the small biopsied specimens in hypertrophic cardiomyopathy. Methods and Results Twenty-one consecutive patients with hypertrophic cardiomyopathy who were examined both by cardiac magnetic resonance imaging and by endomyocardial biopsy were retrospectively studied. The right interventricular septum was the target site for endomyocardial biopsy in all patients. Late gadolinium enhancement in the ventricular septum had an excellent sensitivity (100%) with a low specificity (40%) for predicting microscopic myocardial scarring in biopsied specimens. The sensitivity of late gadolinium enhancement in the whole heart remained 100% with a specificity of 27% for predicting microscopic myocardial scarring in biopsied specimens. Quantitative assessments of fibrosis revealed that the extent of late gadolinium enhancement in the whole heart was the only independent variable related to the microscopic collagen fraction in biopsied specimens (β  =  0.59, 95% confident interval: 0.15 – 1.0, p  =  0.012). Conclusions Although there was a compromise in the specificity, the sensitivity of late gadolinium enhancement was excellent for prediction of microscopic myocardial scarring in hypertrophic cardiomyopathy. Moreover, the severity of late gadolinium enhancement was independently associated with the quantitative collagen fraction in biopsied specimens in hypertrophic cardiomyopathy. These findings indicate that late gadolinium enhancement can reflect both the presence and the extent of microscopic myocardial scarring in the small biopsied specimens in

  1. In vivo sodium tungstate treatment prevents E-cadherin loss induced by diabetic serum in HK-2 cell line.

    PubMed

    Bertinat, Romina; Silva, Pamela; Mann, Elizabeth; Li, Xuhang; Nualart, Francisco; Yáñez, Alejandro J

    2015-10-01

    Diabetic nephropathy (DN) is characterized by interstitial inflammation and fibrosis, which is the result of chronic accumulation of extracellular matrix produced by activated fibroblasts in the renal tubulointerstitium. Renal proximal tubular epithelial cells (PTECs), through the process of epithelial-to-mesenchymal transition (EMT), are the source of fibroblasts within the interstitial space, and loss of E-cadherin has shown to be one of the earliest steps in this event. Here, we studied the effect of the anti-diabetic agent sodium tungstate (NaW) in the loss of E-cadherin induced by transforming growth factor (TGF) β-1, the best-characterized in vitro EMT promoter, and serum from untreated or NaW-treated diabetic rats in HK-2 cell line, a model of human kidney PTEC. Our results showed that both TGFβ-1 and serum from diabetic rat induced a similar reduction in E-cadherin expression. However, E-cadherin loss induced by TGFβ-1 was not reversed by NaW, whereas sera from NaW-treated rats were able to protect HK-2 cells. Searching for soluble mediators of NaW effect, we compared secretion of TGFβ isoforms and vascular endothelial growth factor (VEGF)-A, which have opposite actions on EMT. One millimolar NaW alone reduced secretion of both TGFβ-1 and -2, and stimulated secretion of VEGF-A after 48 h. However, these patterns of secretion were not observed after diabetic rat serum treatment, suggesting that protection from E-cadherin loss by serum from NaW-treated diabetic rats originates from an indirect rather than a direct effect of this salt on HK-2 cells, via a mechanism independent of TGFβ and VEGF-A functions.

  2. Crystal structures of deuterated sodium molybdate dihydrate and sodium tungstate dihydrate from time-of-flight neutron powder diffraction.

    PubMed

    Fortes, A Dominic

    2015-07-01

    Time-of-flight neutron powder diffraction data have been measured from ∼90 mol% deuterated isotopologues of Na2MoO4·2H2O and Na2WO4·2H2O at 295 K to a resolution of sin (θ)/λ = 0.77 Å(-1). The use of neutrons has allowed refinement of structural parameters with a precision that varies by a factor of two from the heaviest to the lightest atoms; this contrasts with the X-ray based refinements where precision may be > 20× poorer for O atoms in the presence of atoms such as Mo and W. The accuracy and precision of inter-atomic distances and angles are in excellent agreement with recent X-ray single-crystal structure refinements whilst also completing our view of the hydrogen-bond geometry to the same degree of statistical certainty. The two structures are isotypic, space-group Pbca, with all atoms occupying general positions, being comprised of edge- and corner-sharing NaO5 and NaO6 polyhedra that form layers parallel with (010) inter-leaved with planes of XO4 (X = Mo, W) tetra-hedra that are linked by chains of water mol-ecules along [100] and [001]. The complete structure is identical with the previously described molybdate [Capitelli et al. (2006 ▸). Asian J. Chem. 18, 2856-2860] but shows that the purported three-centred inter-action involving one of the water mol-ecules in the tungstate [Farrugia (2007 ▸). Acta Cryst. E63, i142] is in fact an ordinary two-centred 'linear' hydrogen bond.

  3. The potential reproductive, neurobehavioral and systemic effects of soluble sodium tungstate exposure in Sprague-Dawley rats.

    PubMed

    McInturf, S M; Bekkedal, M Y V; Wilfong, E; Arfsten, D; Chapman, G; Gunasekar, P G

    2011-07-15

    The debate on tungsten (W) is fostered by its continuous usage in military munitions. Reports demonstrate W solubilizes in soil and can migrate into drinking water supplies and, therefore, is a potential health risk to humans. This study evaluated the reproductive, systemic and neurobehavioral effects of sodium tungstate (NaW) in rats following 70 days of daily pre-and postnatal exposure via oral gavage to 5, 62.5 and 125 mg/kg/day of NaW through mating, gestation and weaning (PND 0-20). Daily administration of NaW produced no overt evidence of toxicity and had no apparent effect on mating success or offspring physical development. Distress vocalizations were elevated in F(1) offspring from the high dose group, whereas righting reflex showed unexpected sex differences where males demonstrated faster righting than females; however, the effects were not dose-dependent. Locomotor activity was affected in both low and high-dose groups of F(1) females. Low-dose group showed increased distance traveled, more time in ambulatory movements and less time in stereotypic behavior than controls or high dose animals. The high-dose group had more time in stereotypical movements than controls, and less time resting than controls and the lowest exposure group. Maternal retrieval was not affected by NaW exposure. Tungsten analysis showed a systemic distribution of NaW in both parents and offspring, with preferential uptake within the immune organs, including the femur, spleen and thymus. Histopathological evidence suggested no severe chronic injury or loss of function in these organs. However, the heart showed histological lesions, histiocytic inflammation from minimal to mild with cardiomyocyte degeneration and necrosis in several P(0) animals of 125 mg NaW dose group. The result of this study suggests that pre and postnatal exposure to NaW may produce subtle neurobehavioral effects in offspring related to motor activity and emotionality.

  4. The potential reproductive, neurobehavioral and systemic effects of soluble sodium tungstate exposure in Sprague-Dawley rats

    SciTech Connect

    McInturf, S.M.; Bekkedal, M.Y.V.; Wilfong, E.; Arfsten, D.; Chapman, G.; Gunasekar, P.G.

    2011-07-15

    The debate on tungsten (W) is fostered by its continuous usage in military munitions. Reports demonstrate W solubilizes in soil and can migrate into drinking water supplies and, therefore, is a potential health risk to humans. This study evaluated the reproductive, systemic and neurobehavioral effects of sodium tungstate (NaW) in rats following 70 days of daily pre-and postnatal exposure via oral gavage to 5, 62.5 and 125 mg/kg/day of NaW through mating, gestation and weaning (PND 0-20). Daily administration of NaW produced no overt evidence of toxicity and had no apparent effect on mating success or offspring physical development. Distress vocalizations were elevated in F{sub 1} offspring from the high dose group, whereas righting reflex showed unexpected sex differences where males demonstrated faster righting than females; however, the effects were not dose-dependent. Locomotor activity was affected in both low and high-dose groups of F{sub 1} females. Low-dose group showed increased distance traveled, more time in ambulatory movements and less time in stereotypic behavior than controls or high dose animals. The high-dose group had more time in stereotypical movements than controls, and less time resting than controls and the lowest exposure group. Maternal retrieval was not affected by NaW exposure. Tungsten analysis showed a systemic distribution of NaW in both parents and offspring, with preferential uptake within the immune organs, including the femur, spleen and thymus. Histopathological evidence suggested no severe chronic injury or loss of function in these organs. However, the heart showed histological lesions, histiocytic inflammation from minimal to mild with cardiomyocyte degeneration and necrosis in several P{sub 0} animals of 125 mg NaW dose group. The result of this study suggests that pre and postnatal exposure to NaW may produce subtle neurobehavioral effects in offspring related to motor activity and emotionality.

  5. Anti-Diabetic Agent Sodium Tungstate Induces the Secretion of Pro- and Anti-Inflammatory Cytokines by Human Kidney Cells.

    PubMed

    Bertinat, Romina; Westermeier, Francisco; Silva, Pamela; Shi, Jie; Nualart, Francisco; Li, Xuhang; Yáñez, Alejandro J

    2017-02-01

    Diabetic kidney disease (DKD) is the major cause of end stage renal disease. Sodium tungstate (NaW) exerts anti-diabetic and immunomodulatory activities in diabetic animal models. Here, we used primary cultures of renal proximal tubule epithelial cells derived from type-2-diabetic (D-RPTEC) and non-diabetic (N-RPTEC) subjects as in vitro models to study the effects of NaW on cytokine secretion, as these factors participate in intercellular regulation of inflammation, cell growth and death, differentiation, angiogenesis, development, and repair, all processes that are dysregulated during DKD. In basal conditions, D-RPTEC cells secreted higher levels of prototypical pro-inflammatory IL-6, IL-8, and MCP-1 than N-RPTEC cells, in agreement with their diabetic phenotype. Unexpectedly, NaW further induced IL-6, IL-8, and MCP-1 secretion in both N- and D-RPTEC, together with lower levels of IL-1 RA, IL-4, IL-10, and GM-CSF, suggesting that it may contribute to the extent of renal damage/repair during DKD. Besides, NaW induced the accumulation of IκBα, the main inhibitor protein of one major pathway involved in cytokine production, suggesting further anti-inflammatory effect in the long-term. A better understanding of the mechanisms involved in the interplay between the anti-diabetic and immunomodulatory properties of NaW will facilitate future studies about its clinical relevance. J. Cell. Physiol. 232: 355-362, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  6. Crystal structures of deuterated sodium molybdate dihydrate and sodium tungstate dihydrate from time-of-flight neutron powder diffraction

    PubMed Central

    Fortes, A. Dominic

    2015-01-01

    Time-of-flight neutron powder diffraction data have been measured from ∼90 mol% deuterated isotopologues of Na2MoO4·2H2O and Na2WO4·2H2O at 295 K to a resolution of sin (θ)/λ = 0.77 Å−1. The use of neutrons has allowed refinement of structural parameters with a precision that varies by a factor of two from the heaviest to the lightest atoms; this contrasts with the X-ray based refinements where precision may be > 20× poorer for O atoms in the presence of atoms such as Mo and W. The accuracy and precision of inter­atomic distances and angles are in excellent agreement with recent X-ray single-crystal structure refinements whilst also completing our view of the hydrogen-bond geometry to the same degree of statistical certainty. The two structures are isotypic, space-group Pbca, with all atoms occupying general positions, being comprised of edge- and corner-sharing NaO5 and NaO6 polyhedra that form layers parallel with (010) inter­leaved with planes of XO4 (X = Mo, W) tetra­hedra that are linked by chains of water mol­ecules along [100] and [001]. The complete structure is identical with the previously described molybdate [Capitelli et al. (2006 ▸). Asian J. Chem. 18, 2856–2860] but shows that the purported three-centred inter­action involving one of the water mol­ecules in the tungstate [Farrugia (2007 ▸). Acta Cryst. E63, i142] is in fact an ordinary two-centred ‘linear’ hydrogen bond. PMID:26279871

  7. Nickel-based Gadolinium Alloy for Neutron Adsorption Application in Ram Packages

    SciTech Connect

    Gregg Wachs; James Sterbentz; William Hurt; P. E. McConnell; C. V. Robino; F. Tovesson; T. S. Hill

    2007-10-01

    Neutron transmission experiments were performed on samples of an advanced nickel-chromium-molybdenum-gadolinium (Ni-Cr-Mo-Gd) neutron absorber alloy and chromium-nickel (Cr-Ni) stainless steel, modified by the addition of boron. The primary purpose of the experiments was to demonstrate the thermal neutron absorbing capability of the materials at specific gadolinium and boron dopant levels. The Ni-Cr-Mo-Gd alloy is envisioned to be deployed for criticality control of highly enriched U.S. Department of Energy (DOE)-owned spent nuclear fuel (SNF). For these transmission experiments, test samples were fabricated with 0.0, 1.58 and 2.1 wt% natural gadolinium dispersed in a Ni-Cr-Mo base alloy and 1.16 wt% boron in stainless steel. The transmission experiments were successfully carried out at the Los Alamos Neutron Science Center (LANSCE). Measured data from the neutron transmission experiments were compared to calculated results derived from a simple exponential transmission formula using total neutron cross sections. Excellent agreement between the measured and calculated results demonstrated the expected strong thermal absorption capability of the gadolinium and boron elements and in addition, verified the measured elemental composition of the Ni-Cr-Mo-Gd alloy and borated stainless steel test samples. The good agreement also indirectly confirmed that the size and distribution of the gadolinium in both the hot-top (as-cast) and Ni-Cr-Mo-Gd converted to plate was not a discriminator related to neutron absorption. Moreover, the Evaluated Nuclear Data File (ENDF VII) total neutron cross section data were accurate.

  8. Acute adverse reactions to magnetic resonance contrast media--gadolinium chelates.

    PubMed

    Li, A; Wong, C S; Wong, M K; Lee, C M; Au Yeung, M C

    2006-05-01

    The objective of this study was to evaluate the clinical safety of intravenous gadolinium-based contrast media used in patients who underwent MRI at a single institution. Acute adverse reactions to intravenous gadolinium-based contrast media used for MRI at the Princess Margaret Hospital, Hong Kong, SAR, from January 1999 to November 2004 were recorded in an incidence log book. The medical records of patients' demographics were retrospectively reviewed and the nature, frequency and severity of the adverse reactions were investigated and documented. The incidence of acute adverse reactions to intravenous gadolinium-based contrast media was 0.48% (45 patients with 46 adverse reactions). The severity of these adverse reactions were 96% mild, 2% moderate (one patient developed shortness of breath that required oxygen supplementation and intravenous steroidal management) and 2% severe (one patient developed an anaphylactoid reaction, but successfully recovered through timely resuscitation). No patients were recorded as having contrast extravasation and none died as a result of any adverse reaction. Among the 45 patients who developed adverse reactions, three patients (6.7%) had prior adverse reactions to iodinated contrast media, three (6.7%) had prior reactions to a different gadolinium-based contrast agent, one (2%) had asthma and nine (20%) had a history of drug/food allergy. Overall, 41% of the adverse reactions were not documented in the final MRI report or the clinical medical records. Gadolinium-based contrast media are safe and well tolerated by the vast majority of patients. In our study, the adverse reaction rate (0.48%) and the incidence of severe anaphylactoid reaction (0.01%) concur with those reported in the literature. Although most of the symptoms are mild and transient, these adverse reactions must be accurately documented and managed.

  9. Impact of gadolinium-157 containing nanoscale magnetosensitive composites on morfofunctional properties of cells in vitro.

    PubMed

    Lavrenchuk, H Y; Shevchenko, Y B; Petranovska, A L; Asmolkova, V S; Oksamytnyi, V M; Kozlovska, I V; Yavorska, O H

    2014-09-01

    Objective - to investigate the morphofunctional cells properties under the action of magneticallybased nanocomposites containing gadolinium-157. Materials and methods. Experimental studies are performed in cell culture line L929 Nanocomposites based on magnetite modified by functional amino groups chemically fixed by diethylenetriaminepentaacetic acid (DTPA) and gadolinium - (Fe3O4/γ-APS/DTPA-Gd) were studied (1), also by meso-2,3-dimercaptosuccinic acid (DMSA) - (Fe3O4/DMSA-Gd), which binds to the hydroxyl group of magnetite surface (2); gadolinium was adsorbed from a solution of gadolinium sulfate. Reagent 3 - magnetic substance Fe3O4 with sodium oleate. Morphofunctional characteristics of cell culture were evaluated in various terms by standard indicators of sustainability: proliferative and mitotic activity and the number of giant multinuclear cells, apoptosis. Results and conclusions. We established that magnetdriven nanocomposites with gadolinium modified by DTPA and DMSA, were more biocompatibile to cells: incubation of cells with neutron capture agents (NCA) in the studied range of concentrations showed no toxicity, except maximum concentration, while decreasing cells adhesive properties. For all nanocomposites we observed decrease in mitotic activity in the background of the control cell population density, which may indicate synchronization of cell division. We found that the stabilized by sodium oleate ferrite caused destructive changes in cell culture only at concentrations of 500 μg / ml, but reduced mitotic activity in cell culture in 3-5 times in the whole range of concentrations. It is shown that magnetdriven nanocomposites induce different levels of apoptosis in cultured cells depending on the concentration of the reactants.

  10. Pressure-Induced Phase Transitions In Gadolinium Iron Borate

    NASA Astrophysics Data System (ADS)

    Kharlamova, S. A.; Struzhkin, V. V.; Sinogeikin, S. V.; Gavriliuk, A. G.; Brown, D.; Toellner, T.; Zhao, J.; Lerche, M.; Lyubutin, I. S.; Ovchinnikov, S. G.; Alp, E. E.; Sturhahn, W.

    2007-12-01

    An understanding of spin crossover (SC) dynamics is relevant to understanding of a role or participation of SC in natural systems including lower Mantle minerals, heme proteins as well as from fundamental science of view. For example, pressure-induced electronic spin transitions of Fe2+ and Fe3+ iron occur in magnesiowustite, silicate perovskite and post-perovskite which are abundant minerals in the Earth's lower mantle [1-3]. Such a SC phenomenon has recently been observed in a number of magnetic minerals FeBO3 [4, 5], BiFeO3 [6], Fe2O3 [7], and Y3Fe5O12 [8], (La, Pr)FeO3 [9, 10]. In those cases, iron ions are in the trivalent state Fe3+ and the high-spin-low-spin (HS-LS) crossover is manifested as the collapse of the local magnetic moment and as the transition of the antiferromagnet to a paramagnetic state. For example, in FeBO3 at low temperatures a spin-crossover and some magnetic transitions with two triple points were found [4, 5]. Gadolinium iron borate, GdFe3(BO3)4 is also a system with SEC and recently, we have reported on phase transitions induced by high pressures in this material [11, 12]. We studied the structural and magnetic behavior of GdFe573(BO3)4 at high pressures and temperatures using a diamond anvil cell and a Synchrotron Mossbauer Spectroscopy technique. The hyperfine parameters and results obtained from the experiments are discussed. Based on our experimental data and theoretical calculation a tentative magnetic P-T phase diagram and an equation of states of GdFe573(BO3)4 are proposed. Important features of the phase diagram are a spin crossover, insulator-semiconductor transition and possible presence of two triple points where magnetic and paramagnetic phases of the high-spin and low-spin states coexist. 1. J. Badro, J.-P. Rueff, G. Vankó, et al., Science 305, 383 (2004). 2. J. M. Jackson, W. Sturhahn, G. Shen, et al., American Mineralogist 90, 199 (2005). 3. J.Li, V.V. Struzhkin, H.-K. Mao, et al., PNAS 101, 14027 (2004). 4. I.A. Troyan

  11. Reactive-oxygen-species-mediated Cdc25C degradation results in differential antiproliferative activities of vanadate, tungstate, and molybdate in the PC-3 human prostate cancer cell line.

    PubMed

    Liu, Tong-Tong; Liu, Yan-Jun; Wang, Qin; Yang, Xiao-Gai; Wang, Kui

    2012-02-01

    The differential antiproliferative effects of vanadate, tungstate, and molybdate on human prostate cancer cell line PC-3 were compared and the underlying mechanisms were investigated. The results demonstrate that all of the three oxoanions can cause G(2)/M cell cycle arrest, which is evidenced by the increase in the level of phosphorylated Cdc2 at its inactive Tyr-15 site. Moreover, even if the difference in cellular uptake among the three oxoanions is excluded from the possible factors affecting their antiproliferative activity, vanadate exerted a much more potent effect in PC-3 cells than the other two oxoanions. Our results also reveal that reactive oxygen species (ROS)-mediated degradation of Cdc25C rather than Cdc25A or Cdc25B is responsible for vanadate-induced G(2)/M cell cycle arrest. We propose a possible mechanism to clarify the differential effect of the three oxoanions in biological systems beyond just considering that they are structural analogs of phosphate. We suggest that ROS formation is unlikely to be involved in the biological function of tungstate and molybdate, whereas the redox properties of vanadium may be important factors for it to exert pharmacological effects. Further, given the evidence from epidemiology studies of the association between diabetes and prostate cancer, the possibility of vanadate as a good candidate as both an antidiabetic and an anticancer agent or a chemopreventive agent is indicated.

  12. Effects of Molybdate and Tungstate on Expression Levels and Biochemical Characteristics of Formate Dehydrogenases Produced by Desulfovibrio alaskensis NCIMB 13491 ▿

    PubMed Central

    Mota, Cristiano S.; Valette, Odile; González, Pablo J.; Brondino, Carlos D.; Moura, José J. G.; Moura, Isabel; Dolla, Alain; Rivas, Maria G.

    2011-01-01

    Formate dehydrogenases (FDHs) are enzymes that catalyze the formate oxidation to carbon dioxide and that contain either Mo or W in a mononuclear form in the active site. In the present work, the influence of Mo and W salts on the production of FDH by Desulfovibrio alaskensis NCIMB 13491 was studied. Two different FDHs, one containing W (W-FDH) and a second incorporating either Mo or W (Mo/W-FDH), were purified. Both enzymes were isolated from cells grown in a medium supplemented with 1 μM molybdate, whereas only the W-FDH was purified from cells cultured in medium supplemented with 10 μM tungstate. We demonstrated that the genes encoding the Mo/W-FDH are strongly downregulated by W and slightly upregulated by Mo. Metal effects on the expression level of the genes encoding the W-FDH were less significant. Furthermore, the expression levels of the genes encoding proteins involved in molybdate and tungstate transport are downregulated under the experimental conditions evaluated in this work. The molecular and biochemical properties of these enzymes and the selective incorporation of either Mo or W are discussed. PMID:21478344

  13. Size- and shape-controlled conversion of tungstate-based inorganic-organic hybrid belts to WO3 nanoplates with high specific surface areas.

    PubMed

    Chen, Deliang; Gao, Lian; Yasumori, Atsuo; Kuroda, Kazuyuki; Sugahara, Yoshiyuki

    2008-10-01

    Two-dimensional monoclinic WO(3) nanoplates with high specific surface areas are synthesized through a novel conversion process using tungstate-based inorganic-organic hybrid micro/nanobelts as precursors. The process developed involves a topochemical transformation of tungstate-based inorganic-organic hybrid belts into WO(3) nanoplates via an intermediate product of H(2)WO(4) nanoplates, utilizing the similarity of the W-O octahedral layers in both H(2)WO(4) and WO(3). The as-obtained WO(3) nanoplates show a single-crystalline nanostructure with the smallest side along the [001] direction. The WO(3) nanoplates are 200-500 nm x 200-500 nm x 10-30 nm in size, and their specific surface areas are up to 180 m(2) g(-1). Photocatalytic measurements of visible-light-driven oxidation of water for O(2) generation in the presence of Ag(+) ions indicate that the activity of the as-obtained WO(3) nanoplates is one order of magnitude higher than that of commercially available WO(3) powders.

  14. Tracing gadolinium-based contrast agents from surface water to drinking water by means of speciation analysis.

    PubMed

    Birka, Marvin; Wehe, Christoph A; Hachmöller, Oliver; Sperling, Michael; Karst, Uwe

    2016-04-01

    In recent decades, a significant amount of anthropogenic gadolinium has been released into the environment as a result of the broad application of contrast agents for magnetic resonance imaging (MRI). Since this anthropogenic gadolinium anomaly has also been detected in drinking water, it has become necessary to investigate the possible effect of drinking water purification on these highly polar microcontaminats. Therefore, a novel highly sensitive method for speciation analysis of gadolinium is presented. For that purpose, the hyphenation of hydrophilic interaction liquid chromatography (HILIC) and inductively coupled plasma-mass spectrometry (ICP-MS) was employed. In order to enhance the detection power, sample introduction was carried out by ultrasonic nebulization. In combination with a novel HILIC method using a diol-based stationary phase, it was possible to achieve superior limits of detection for frequently applied gadolinium-based contrast agents below 20pmol/L. With this method, the contrast agents Gd-DTPA, Gd-DOTA and Gd-BT-DO3A were determined in concentrations up to 159pmol/L in samples from several waterworks in a densely populated region of Germany alongside the river Ruhr as well as from a waterworks near a catchment lake. Thereby, the direct impact of anthropogenic gadolinium species being present in the surface water on the amount of anthropogenic gadolinium in drinking water was shown. There was no evidence for the degradation of contrast agents, the release of Gd(3+) or the presence of further Gd species.

  15. Thermodynamic property evaluation and magnetic refrigeration cycle analysis for gadolinium gallium garnet

    SciTech Connect

    Murphy, R.W.

    1994-12-01

    Based on relevant material property data and previous model formulations, a magnetothermodynamic property map for gadolinium gallium garnet (Gd{sub 3}Ga{sub 5}O{sub 12}) was adapted for refrigeration cycle analysis in the temperature range 4-40 K and the magnetic field range 0-6 T. Employing methods similar to those previously developed for other materials and temperature ranges, assessments of limitations and relative performance were made for Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. It was found that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as the limitations for materials previously examined, considerable improvement in cooling capacity and temperature lift combinations can be achieved by using regenerative cycles if serious loss mechanisms are avoided.

  16. Nanoamplifiers synthesized from gadolinium and gold nanocomposites for magnetic resonance imaging.

    PubMed

    Tian, Xiumei; Shao, Yuanzhi; He, Haoqiang; Liu, Huan; Shen, Yingying; Huang, Wenlin; Li, Li

    2013-04-21

    We have synthesized an efficient and highly sensitive nanoamplifier composed of gadolinium-doped silica nanoparticles and gold nanoparticles (AuNPs). Magnetic resonance imaging (MRI) in vitro and in vivo assays revealed enhancement of signal sensitivity, which may be explained by electron transfer between water and gadolinium-doped nanoparticles, apparent in the presence of gold. In vitro and in vivo evaluation demonstrated nanoamplifier incurred minimal cytotoxicity and immunotoxicity, increased stability, and gradual excretion patterns. Tumor targeted properties were preliminarily determined when the nanoamplifier was injected into mouse models of colon cancer liver metastasis. Furthermore, although AuNPs departed from the nanoamplifiers in specific mice tissues, optical and magnetic resonance imaging was efficient, especially in metastatic tumors. These assays validate our nanoamplifier as an effective MRI signal enhancer with sensitive cancer diagnosis potential.

  17. Frontiers of X-ray spectromicroscopy in biology and medicine: Gadolinium in brain cancer

    NASA Astrophysics Data System (ADS)

    De Stasio, Gelsomina; Gilbert, B.; Perfetti, P.; Margaritondo, G.; Mercanti, D.; Ciotti, M. T.; Casalbore, P.; Larocca, L. M.; Rinelli, A.; Pallini, R.

    2000-02-01

    We present the first feasibility test of spectromicroscopy on the microlocalization of gadolinium in brain cancer tissue. A gadolinium compound was injected to the patients before the brain tumor was extracted with surgery, and we looked for Gd in the tumor tissue. The goal of the experiment was to understand if Gd Neutron Capture Therapy (GdNCT) is viable for clinical tests, i.e. if there is enough Gd, and it is localized near the nuclei of tumor cells. The experiments were performed using the MEPHISTO X-ray PhotoElectron Emission Microscope (X-PEEM) at the Wisconsin Synchrotron Radiation Center. The present results demonstrate the feasibility of the experiment, and suggest how to improve the sample preparation and data acquisition to achieve the goal.

  18. Biocompatible Polyhydroxyethylaspartamide-based Micelles with Gadolinium for MRI Contrast Agents

    NASA Astrophysics Data System (ADS)

    Jeong, Sang Young; Kim, Hyo Jeong; Kwak, Byung-Kook; Lee, Ha-Young; Seong, Hasoo; Shin, Byung Cheol; Yuk, Soon Hong; Hwang, Sung-Joo; Cho, Sun Hang

    2010-12-01

    Biocompatible poly-[ N-(2-hydroxyethyl)- d, l-aspartamide]-methoxypoly(ethyleneglycol)-hexadecylamine (PHEA-mPEG-C16) conjugated with 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid-gadolinium (DOTA-Gd) via ethylenediamine (ED) was synthesized as a magnetic resonance imaging (MRI) contrast agent. Amphiphilic PHEA-mPEG-C16-ED-DOTA-Gd forms micelle in aqueous solution. All the synthesized materials were characterized by proton nuclear magnetic resonance (1H NMR). Micelle size and shape were examined by dynamic light scattering (DLS) and atomic force microscopy (AFM). Micelles with PHEA-mPEG-C16-ED-DOTA-Gd showed higher relaxivities than the commercially available gadolinium contrast agent. Moreover, the signal intensity of a rabbit liver was effectively increased after intravenous injection of PHEA-mPEG-C16-ED-DOTA-Gd.

  19. Renal function, nephrogenic systemic fibrosis and other adverse reactions associated with gadolinium-based contrast media.

    PubMed

    Canga, Ana; Kislikova, Maria; Martínez-Gálvez, María; Arias, Mercedes; Fraga-Rivas, Patricia; Poyatos, Cecilio; de Francisco, Angel L M

    2014-01-01

    Nephrogenic systemic fibrosis is a fibrosing disorder that affects patients with impaired renal function and is associated with the administration of gadolinium-based contrast media used in MRI. Despite being in a group of drugs that were considered safe, report about this potentially serious adverse reaction was a turning point in the administration guidelines of these contrast media. There has been an attempt to establish safety parameters to identify patients with risk factors of renal failure. The close pharmacovigilance and strict observation of current regulations, with special attention being paid to the value of glomerular filtration, have reduced the published cases involving the use of gadolinium-based contrast media. In a meeting between radiologists and nephrologists we reviewed the most relevant aspects currently and recommendations for its prevention.

  20. Regression of gadolinium-enhanced lesions in patients affected by neurofibromatosis type 1.

    PubMed

    Lucchetta, Marta; Manara, Renzo; Perilongo, Giorgio; Clementi, Maurizio; Trevisson, Eva

    2016-03-01

    Neurofibromatosis type I is a genetic condition with an autosomal dominant transmission characterized by neurocutaneous involvement and a predisposition to tumor development. Central nervous system manifestations include benign areas of dysmyelination and possibly hazardous glial tumors whose clinical management may result challenging. Here, we report on three patients diagnosed with Neurofibromatosis type I whose brain MRI follow-up showed the presence of gadolinium-enhancing lesions which spontaneously regressed. In none of the three cases, the lesions showed any clinical correlate and eventually presented a striking reduction in size while gadolinium enhancement disappeared despite no specific therapy administration during the follow-up. Although their nature remains undetermined, these lesions presented a benign evolution. However, they might be misdiagnosed as potentially life-threatening tumors. Hitherto, a similar behavior has been described only in scattered cases and we believe these findings may be of particular interest for the clinical management of patients affected by neurofibromatosis type I.

  1. The role of gadolinium chelates in the mechanism of nephrogenic systemic fibrosis: A critical update.

    PubMed

    Idée, Jean-Marc; Fretellier, Nathalie; Robic, Caroline; Corot, Claire

    2014-11-01

    Nephrogenic systemic fibrosis (NSF) is an iatrogenic scleroderma-like fibrosing systemic disorder occurring in patients with severe or end-stage renal disease. It was established as a new clinical entity in the year 2000. A causal role for gadolinium chelates (GC), widely used as contrast agents for magnetic resonance imaging, was suggested six years later. It rapidly appeared that the occurrence of NSF was associated with prior administration of GCs with lower thermodynamic stability, leading to warnings being published by health authorities and learned societies worldwide. Although a role for the chelated form of the less stable GCs has been proposed, the most commonly accepted hypothesis involves the gradual release of dissociated gadolinium in the body, leading to systemic fibrosis. However, the entire chain of events is still not fully understood in a causal way and many uncertainties remain.

  2. The performance of hafnium and gadolinium self powered neutron detectors in the TREAT reactor

    NASA Astrophysics Data System (ADS)

    Imel, G. R.; Hart, P. R.

    1996-05-01

    The use of gadolinium and hafnium self powered neutron detectors in a transient reactor is described in this paper. The detectors were calibrated to the fission rate of U-235 using calibrated fission chambers; the calibration factors were tested in two reactors in steady state and found to be consistent. Calibration of the detectors in transient reactor conditions was done by using uranium wires that were analyzed by radiochemistry techniques to determine total fissions during the transient. This was correlated to the time-integrated current of the detectors during the transient. A temperature correction factor was derived to account for self-shielding effects in the hafnium and gadolinium detectors. The dynamic response of the detectors under transient conditions was studied, and found to be excellent.

  3. A new gadolinium-loaded liquid scintillator for reactor neutrino detection

    NASA Astrophysics Data System (ADS)

    Ding, Yayun; Zhang, Zhiyong; Liu, Jinchang; Wang, Zhimin; Zhou, Pengju; Zhao, Yuliang

    2008-01-01

    A high flash point, low toxicity gadolinium-loaded liquid scintillator (Gd-LS) has been developed for the detection of reactor neutrino. Carboxylic acid 3,5,5-trimethylhexanoic acid is used as complexing ligand to form organo-complex with gadolinium chloride, and 2,5-diphenyloxazole (PPO), and 1,4-bis[2-methylstyryl]benzene (bis-MSB) are used as primary fluor and wavelength shifter, respectively. The scintillator base is linear alkyl benzene (LAB). The Gd-LS prepared with such recipe has long attenuation length, high light yield and long-term stability. Eight hundred liters of Gd-LS (1 g/L Gd) was synthesized and tested in a prototype detector at Institute of High Energy Physics. Preliminary results of the obviously peaks corresponding to neutron captured by H and Gd give an additional evidence that such Gd-LS are very promising for anti-neutrino detection.

  4. The evolution of gadolinium based contrast agents: from single-modality to multi-modality

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Liu, Ruiqing; Peng, Hui; Li, Penghui; Xu, Zushun; Whittaker, Andrew K.

    2016-05-01

    Gadolinium-based contrast agents are extensively used as magnetic resonance imaging (MRI) contrast agents due to their outstanding signal enhancement and ease of chemical modification. However, it is increasingly recognized that information obtained from single modal molecular imaging cannot satisfy the higher requirements on the efficiency and accuracy for clinical diagnosis and medical research, due to its limitation and default rooted in single molecular imaging technique itself. To compensate for the deficiencies of single function magnetic resonance imaging contrast agents, the combination of multi-modality imaging has turned to be the research hotpot in recent years. This review presents an overview on the recent developments of the functionalization of gadolinium-based contrast agents, and their application in biomedicine applications.

  5. First measurements with new high-resolution gadolinium-GEM neutron detectors

    NASA Astrophysics Data System (ADS)

    Pfeiffer, D.; Resnati, F.; Birch, J.; Etxegarai, M.; Hall-Wilton, R.; Höglund, C.; Hultman, L.; Llamas-Jansa, I.; Oliveri, E.; Oksanen, E.; Robinson, L.; Ropelewski, L.; Schmidt, S.; Streli, C.; Thuiner, P.

    2016-05-01

    European Spallation Source instruments like the macromolecular diffractometer (NMX) require an excellent neutron detection efficiency, high-rate capabilities, time resolution, and an unprecedented spatial resolution in the order of a few hundred micrometers over a wide angular range of the incoming neutrons. For these instruments solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are a promising option. A GEM detector with gadolinium converter was tested on a cold neutron beam at the IFE research reactor in Norway. The μTPC analysis, proven to improve the spatial resolution in the case of 10B converters, is extended to gadolinium based detectors. For the first time, a Gd-GEM was successfully operated to detect neutrons with a measured efficiency of 11.8% at a wavelength of 2 Åand a position resolution better than 250 μm.

  6. The statistical decay properties of Gadolinium isotopes using the DANCE array

    NASA Astrophysics Data System (ADS)

    Dashdorj, D.; Mitchell, G.; Baramsai, B.; Chankova, R.; Chyzh, A.; Walker, C.

    2008-10-01

    The gadolinium isotopes are interesting for reactor applications as well as for medicine and astrophysics. There are seven stable isotopes of gadolinium with varying deformation. Decay γ rays following neutron capture on Gd isotopes are detected by the DANCE array, which is located at flight path 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation and close packing of the detector array enable γ-ray multiplicity measurements. The calorimetric property of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a specific isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles γ-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. Various photon strength function models are used for comparison with experimentally measured DANCE data and provide insight for understanding the statistical decay properties of deformed nuclei.

  7. Gadolinium/terbium hybrid macromolecular complexes for bimodal imaging of atherothrombosis

    NASA Astrophysics Data System (ADS)

    Nghĩa, Nguyen Tráeng; Tinet, Eric; Ettori, Dominique; Beilvert, Anne; Pavon-Djavid, Graciela; Maire, Murielle; Ou, Phalla; Tualle, Jean-Michel; Chaubet, Frédéric

    2017-07-01

    We developed a fluorescence imaging microscope system intended for the localization within artery slices of a gadolinium-based macromolecular biospecific magnetic resonance (MR) contrast agent used for the visualization of atherothrombosis. As the contrast agent is not initially fluorescent, we substitute some gadolinium ions for terbium ions to make them fluorescent while preserving their chemical characteristics. A long fluorescence emission time constant enables us to have a suitable signal-to-noise ratio, despite a low intensity, using pulsed illumination and time-gated imaging. Images of rat arteries show that the contrast agent is indeed localized on the specific regions of the tissues. We currently have a tool that allows us to understand and optimize the MR contrast agent.

  8. Macroscopic and Microscopic Investigation of Densification Behavior for Gadolinium-doped Ceria upon Sintering

    NASA Astrophysics Data System (ADS)

    Kosaka, T.; Sato, K.

    2011-10-01

    The densification behaviour of Gadolinium-doped ceria (GDC) upon sintering is investigated from macroscopic and microscopic points of view. The time-resolved length-change measurement with high-resolution dilatometry and positron lifetime spectroscopy are conducted. Positron lifetime spectroscopy reveals the presence of nanovoids at grain boundaries in GDC. Time-dependent length-change measurement reveals that particle rearrangement occurs at the initial stage of sintering. Densifications at the sintering neck and inside the particle grain are discussed.

  9. Gadolinium uptake by brain cancer cells: Quantitative analysis with X-PEEM spectromicroscopy for cancer therapy

    NASA Astrophysics Data System (ADS)

    De Stasio, Gelsomina; Gilbert, B.; Perfetti, P.; Margaritondo, G.; Mercanti, D.; Ciotti, M. T.; Casalbore, P.; Larocca, L. M.; Rinelli, A.; Pallini, R.

    2000-05-01

    We present the first X-PEEM spectromicroscopy semi-quantitative data, acquired on Gd in glioblastoma cell cultures from human brain cancer. The cells were treated with a Gd compound for the optimization of GdNCT (Gadolinium Neutron Capture Therapy). We analyzed the kinetics of Gd uptake as a function of exposure time, and verified that a quantitative analytical technique gives the same results as our MEPHISTO X-PEEM, demonstrating the feasibility of semi-quantitative spectromicroscopy.

  10. Proposed experiment to measure {gamma}-rays from the thermal neutron capture of gadolinium

    SciTech Connect

    Yano, Takatomi; Ou, I.; Izumi, T.; Yamaguchi, R.; Mori, T.; Sakuda, M.

    2012-11-12

    Gadolinium-157 ({sup 157}Gd) has the largest thermal neutron capture cross section among any stable nuclei. The thermal neutron capture yields {gamma}-ray cascade with total energy of about 8 MeV. Because of these characteristics, Gd is applied for the recent neutrino detectors. Here, we propose an experiment to measure the multiplicity and the angular correlation of {gamma}-rays from the Gd neutron capture. With these information, we expect the improved identification of the Gd neutron capture.

  11. Sensitive and transportable gadolinium-core plastic scintillator sphere for neutron detection and counting

    NASA Astrophysics Data System (ADS)

    Dumazert, Jonathan; Coulon, Romain; Carrel, Frédérick; Corre, Gwenolé; Normand, Stéphane; Méchin, Laurence; Hamel, Matthieu

    2016-08-01

    Neutron detection forms a critical branch of nuclear-related issues, currently driven by the search for competitive alternative technologies to neutron counters based on the helium-3 isotope. The deployment of plastic scintillators shows a high potential for efficient detectors, safer and more reliable than liquids, more easily scalable and cost-effective than inorganic. In the meantime, natural gadolinium, through its 155 and mostly 157 isotopes, presents an exceptionally high interaction probability with thermal neutrons. This paper introduces a dual system including a metal gadolinium core inserted at the center of a high-scale plastic scintillator sphere. Incident fast neutrons are thermalized by the scintillator shell and then may be captured with a significant probability by gadolinium 155 and 157 nuclei in the core. The deposition of a sufficient fraction of the capture high-energy prompt gamma signature inside the scintillator shell will then allow discrimination from background radiations by energy threshold, and therefore neutron detection. The scaling of the system with the Monte Carlo MCNPX2.7 code was carried out according to a tradeoff between the moderation of incident fast neutrons and the probability of slow neutron capture by a moderate-cost metal gadolinium core. Based on the parameters extracted from simulation, a first laboratory prototype for the assessment of the detection method principle has been synthetized. The robustness and sensitivity of the neutron detection principle are then assessed by counting measurement experiments. Experimental results confirm the potential for a stable, highly sensitive, transportable and cost-efficient neutron detector and orientate future investigation toward promising axes.

  12. Gadolinium neutron capture brachytherapy (GdNCB), a new treatment method for intravascular brachytherapy

    SciTech Connect

    Enger, Shirin A.; Rezaei, Arash; Munck af Rosenschoeld, Per; Lundqvist, Hans

    2006-01-15

    Restenosis is a major problem after balloon angioplasty and stent implantation. The aim of this study is to introduce gadolinium neutron capture brachytherapy (GdNCB) as a suitable modality for treatment of stenosis. The utility of GdNCB in intravascular brachytherapy (IVBT) of stent stenosis is investigated by using the GEANT4 and MCNP4B Monte Carlo radiation transport codes. To study capture rate, Kerma, absorbed dose and absorbed dose rate around a Gd-containing stent activated with neutrons, a 30 mm long, 5 mm diameter gadolinium foil is chosen. The input data is a neutron spectrum used for clinical neutron capture therapy in Studsvik, Sweden. Thermal neutron capture in gadolinium yields a spectrum of high-energy gamma photons, which due to the build-up effect gives an almost flat dose delivery pattern to the first 4 mm around the stent. The absorbed dose rate is 1.33 Gy/min, 0.25 mm from the stent surface while the dose to normal tissue is in order of 0.22 Gy/min, i.e., a factor of 6 lower. To spare normal tissue further fractionation of the dose is also possible. The capture rate is relatively high at both ends of the foil. The dose distribution from gamma and charge particle radiation at the edges and inside the stent contributes to a nonuniform dose distribution. This will lead to higher doses to the surrounding tissue and may prevent stent edge and in-stent restenosis. The position of the stent can be verified and corrected by the treatment plan prior to activation. Activation of the stent by an external neutron field can be performed days after catherization when the target cells start to proliferate and can be expected to be more radiation sensitive. Another advantage of the nonradioactive gadolinium stent is the possibility to avoid radiation hazard to personnel.

  13. Highly absorbing gadolinium test device to characterize the performance of neutron imaging detector systems

    SciTech Connect

    Gruenzweig, C.; Frei, G.; Lehmann, E.; Kuehne, G.; David, C.

    2007-05-15

    We report on the fabrication and application of a novel neutron imaging test device made of gadolinium. It is designed for a real time evaluation of the spatial resolution, resolution direction, and distortions of a neutron imaging detector system. Measurements of the spatial resolution of {sup 6}LiF doped ZnS scintillator screens with different thicknesses and of imaging plates were performed. The obtained results are in good agreement with comparison measurements using the standard knife edge detection method.

  14. Hearing function after intratympanic application of gadolinium-based contrast agent: A long-term evaluation.

    PubMed

    Louza, Julia; Krause, Eike; Gürkov, Robert

    2015-10-01

    The aim of this study was to evaluate the long-term influence of intratympanic gadolinium-based contrast agent on hearing function in patients with possible Ménière's disease and normal auditory thresholds who were undergoing locally enhanced magnetic resonance imaging scans. Prospective observational cohort study in a tertiary referral university hospital ear, nose, and throat department. Between 2009 and 2012, 17 patients with possible or probable Ménière's disease and a four-tone pure-tone average baseline of <25 dB were recruited for our study. Before undergoing intratympanic injection of gadolinium-based contrast agent, all patients underwent a complete audiological evaluation. The study population was then invited back after at least 6 months postinjection for a follow-up auditory evaluation. This consisted of comprehensive clinical and audiological tests on both sides and were evaluated according to the ototoxicity guidelines. A long-term evaluation of our study group revealed no significant difference in the air-conduction pure-tone average. Furthermore, no statistical difference at individual frequencies compared to baseline was found. There was no evidence of ototoxicity in the injected ear. Long-term hearing function assessment after intratympanic application of gadolinium-based agent showed no evidence of ototoxicity. The use of intratympanic gadolinium-based agent in the diagnosis of Ménièrés disease is currently a helpful tool, and seems to be a safe method, especially with regard to auditory function. 4. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  15. Nanoamplifiers synthesized from gadolinium and gold nanocomposites for magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Tian, Xiumei; Shao, Yuanzhi; He, Haoqiang; Liu, Huan; Shen, Yingying; Huang, Wenlin; Li, Li

    2013-03-01

    We have synthesized an efficient and highly sensitive nanoamplifier composed of gadolinium-doped silica nanoparticles and gold nanoparticles (AuNPs). Magnetic resonance imaging (MRI) in vitro and in vivo assays revealed enhancement of signal sensitivity, which may be explained by electron transfer between water and gadolinium-doped nanoparticles, apparent in the presence of gold. In vitro and in vivo evaluation demonstrated nanoamplifier incurred minimal cytotoxicity and immunotoxicity, increased stability, and gradual excretion patterns. Tumor targeted properties were preliminarily determined when the nanoamplifier was injected into mouse models of colon cancer liver metastasis. Furthermore, although AuNPs departed from the nanoamplifiers in specific mice tissues, optical and magnetic resonance imaging was efficient, especially in metastatic tumors. These assays validate our nanoamplifier as an effective MRI signal enhancer with sensitive cancer diagnosis potential.We have synthesized an efficient and highly sensitive nanoamplifier composed of gadolinium-doped silica nanoparticles and gold nanoparticles (AuNPs). Magnetic resonance imaging (MRI) in vitro and in vivo assays revealed enhancement of signal sensitivity, which may be explained by electron transfer between water and gadolinium-doped nanoparticles, apparent in the presence of gold. In vitro and in vivo evaluation demonstrated nanoamplifier incurred minimal cytotoxicity and immunotoxicity, increased stability, and gradual excretion patterns. Tumor targeted properties were preliminarily determined when the nanoamplifier was injected into mouse models of colon cancer liver metastasis. Furthermore, although AuNPs departed from the nanoamplifiers in specific mice tissues, optical and magnetic resonance imaging was efficient, especially in metastatic tumors. These assays validate our nanoamplifier as an effective MRI signal enhancer with sensitive cancer diagnosis potential. Electronic supplementary information

  16. Gadolinium thin films as benchmark for magneto-caloric thin films

    NASA Astrophysics Data System (ADS)

    Helmich, Lars; Bartke, Marianne; Teichert, Niclas; Schleicher, Benjamin; Fähler, Sebastian; Hütten, Andreas

    2017-05-01

    We report on the preparation of Gadolinium thin films by means of sputter deposition on Silicon Oxide wafers. A series of samples with different buffer layers and various substrate temperatures has been produced. The film on an amorphous Tantalum buffer deposited at 773 K shows the highest increase of magnetization during the phase transition at the Curie temperature. Further detailed analysis of the magnetic properties has been conducted by VSM.

  17. Study of the Photon Strength Functions for Gadolinium Isotopes with the DANCE Array

    SciTech Connect

    Dashdorj, D.; Mitchell, G. E.; Baramsai, B.; Chankova, R.; Chyzh, A.; Walker, C.; Agvaanluvsan, U.; Becker, J. A.; Parker, W.; Sleaford, B.; Wu, C. Y.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.; Krticka, M.

    2009-03-10

    The gadolinium isotopes are interesting for reactor applications as well as for medicine and astrophysics. The gadolinium isotopes have some of the largest neutron capture cross sections. As a consequence they are used in the control rod in reactor fuel assembly. From the basic science point of view, there are seven stable isotopes of gadolinium with varying degrees of deformation. Therefore they provide a good testing ground for the study of deformation dependent structure such as the scissors mode. Decay gamma rays following neutron capture on Gd isotopes are detected by the DANCE array, which is located at flight path 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation and close packing of the detector array enable gamma-ray multiplicity measurements. The calorimetric properties of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a specific isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles gamma-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. Various photon strength function models are used for comparison with experimentally measured DANCE data and provide insight for understanding the statistical decay properties of deformed nuclei.

  18. Selective Filtration of Gadolinium Trichloride for Use in Neutron Detection in Large Water Cherenkov Detectors

    SciTech Connect

    Vagins, Mark R.

    2013-04-10

    Water Cherenkov detectors have been used for many years as inexpensive, effective detectors for neutrino interactions and nucleon decay searches. While many important measurements have been made with these detectors a major drawback has been their inability to detect the absorption of thermal neutrons. We believe an inexpensive, effective technique could be developed to overcome this situation via the addition to water of a solute with a large neutron cross section and energetic gamma daughters which would make neutrons detectable. Gadolinium seems an excellent candidate especially since in recent years it has become very inexpensive, now less than $8 per kilogram in the form of commercially-available gadolinium trichloride, GdCl{sub 3}. This non-toxic, non-reactive substance is highly soluble in water. Neutron capture on gadolinium yields a gamma cascade which would be easily seen in detectors like Super-Kamiokande. We have been investigating the use of GdCl{sub 3} as a possible upgrade for the Super-Kamiokande detector with a view toward improving its performance as a detector for atmospheric neutrinos, supernova neutrinos, wrong-sign solar neutrinos, reactor neutrinos, proton decay, and also as a target for the coming T2K long-baseline neutrino experiment. This focused study of selective water filtration and GdCl{sub 3} extraction techniques, conducted at UC Irvine, followed up on highly promising benchtop-scale and kiloton-scale work previously carried out with the assistance of 2003 and 2005 Advanced Detector Research Program grants.

  19. Pulmonary vein inflow artifact reduction for free-breathing left atrium late gadolinium enhancement.

    PubMed

    Moghari, Mehdi H; Peters, Dana C; Smink, Jouke; Goepfert, Lois; Kissinger, Kraig V; Goddu, Beth; Hauser, Thomas H; Josephson, Mark E; Manning, Warren J; Nezafat, Reza

    2011-07-01

    Two-dimensional "pencil-beam" navigator, placed on the right hemidiaphragm, is used for free-breathing late gadolinium enhancement of the left atrium in patients with atrial fibrillation. The pencil-beam navigator creates an inflow artifact in the right pulmonary veins and atrial wall that may obscure local pulmonary vein and left atrium scars. To reduce this artifact, we propose a large slab right hemidiaphragm projection navigator that measures the respiratory motion while reducing the associated inflow artifact. Eighteen subjects underwent pulmonary vein late gadolinium enhancement using the pencil-beam and projection navigator. Subjective inflow and respiratory motion artifact scores (1 = severe, 2 = moderate, 3 = mild, and 4 = none) from two blinded readers were compared. The artifact scores were 3.8 ± 0.4 and 2.1 ± 0.7 for the projection and pencil-beam navigators, respectively (P < 0.001). Respiratory motion artifact scores were similar between the two techniques (3.0 ± 0.5 vs. 3.1 ± 0.5 for projection vs. pencil-beam navigator). The proposed method greatly reduces the inflow artifact in free-breathing pulmonary vein late gadolinium enhancement while allowing adequate respiratory motion compensation. Copyright © 2011 Wiley-Liss, Inc.

  20. Specific lipase-responsive polymer-coated gadolinium nanoparticles for MR imaging of early acute pancreatitis.

    PubMed

    Zhang, Hong-Wu; Wang, Li-Qin; Xiang, Qing-Feng; Zhong, Qian; Chen, Lu-Ming; Xu, Cai-Xia; Xiang, Xian-Hong; Xu, Bo; Meng, Fei; Wan, Yi-Qian; Deng, David Y B

    2014-01-01

    Currently, available methods for diagnosis of acute pancreatitis (AP) are mainly dependent on serum enzyme analysis and imaging techniques that are too low in sensitivity and specificity to accurately and promptly diagnose AP. The lack of early diagnostic tools highlights the need to search for a highly effective and specific diagnostic method. In this study, we synthesized a conditionally activated, gadolinium-containing, nanoparticle-based MRI nanoprobe as a diagnostic tool for the early identification of AP. Gadolinium diethylenetriaminepentaacetic fatty acid (Gd-DTPA-FA) nanoparticles were synthesized by conjugation of DTPA-FA ligand and gadolinium acetate. Gd-DTPA-FA exhibited low cytotoxicity and excellent biocompatibility when characterized in vitro and in vivo studies. L-arginine induced a gradual increase in the intensity of the T1-weighted MRI signal from 1 h to 36 h in AP rat models. The increase in signal intensity was most significant at 1 h, 6 h and 12 h. These results suggest that the Gd-DTPA-FA as an MRI contrast agent is highly efficient and specific to detect early AP.

  1. Gadolinium prevents high airway pressure-induced permeability increases in isolated rat lungs.

    PubMed

    Parker, J C; Ivey, C L; Tucker, J A

    1998-04-01

    To determine the initial signaling event in the vascular permeability increase after high airway pressure injury, we compared groups of lungs ventilated at different peak inflation pressures (PIPs) with (gadolinium group) and without (control group) infusion of 20 microM gadolinium chloride, an inhibitor of endothelial stretch-activated cation channels. Microvascular permeability was assessed by using the capillary filtration coefficient (Kfc), a measure of capillary hydraulic conductivity. Kfc was measured after ventilation for 30-min periods with 7, 20, and 30 cmH2O PIP with 3 cmH2O positive end-expiratory pressure and with 35 cmH2O PIP with 8 cmH2O positive end-expiratory pressure. In control lungs, Kfc increased significantly to 1.8 and 3.7 times baseline after 30 and 35 cmH2O PIP, respectively. In the gadolinium group, Kfc was unchanged from baseline (0.060 +/- 0.010 ml . min-1 . cmH2O-1 . 100 g-1) after any PIP ventilation period. Pulmonary vascular resistance increased significantly from baseline in both groups before the last Kfc measurement but was not different between groups. These results suggest that microvascular permeability is actively modulated by a cellular response to mechanical injury and that stretch-activated cation channels may initiate this response through increases in intracellular calcium concentration.

  2. [Dixon's technic for fat suppression. Its potential applications in combination with gadolinium-DTPA].

    PubMed

    Mascalchi, M; Battolla, L; Zampa, V; Falaschi, F; Caramella, D; Bartolozzi, C

    1994-01-01

    Modification of the Dixon technique enables the reconstruction of water and fat images operating at midfield strength. The technique was combined with intravenous administration of gadolinium-DTPA in five patients with lumbosacral spine conditions, four patients with soft tissue neoplasms and three with skeletal neoplasms; all patients were examined at 0.5 T. Mean attenuation of fat signal in T1-weighted images was 85% and implied a redistribution of the gray-scale dynamic range. This allowed easier appreciation of normal and abnormal enhancement in both areas containing fat tissue and areas without it. This was useful in the evaluation of fresh scars in two patients recently submitted to lamino-discectomy and of the prevertebral extension of the inflammatory process in one patient with spondylodiscitis. In the patients with soft tissue neoplasms the combination of fat suppression and Gadolinium was helpful to assess lesion size. Finally, in the patients with skeletal neoplasms fat-suppressed images obviated for the lesion disappearance observed on conventional T1-weighted SE images after contrast administration. The combination of intravenous administration of gadolinium-DPTA with Dixon's fat-suppression technique is a new promising capability of midfield MRI.

  3. [Natural history of lumbar disc hernias: does gadolinium enhancement have any prognostic value?].

    PubMed

    Ramos Amador, A; Alcaraz Mexía, M; González Preciado, J L; Fernández Zapardiel, S; Salgado, R; Páez, A

    2013-09-01

    To evaluate the percentage of disc hernias that have disappeared after one year of follow-up and the time to disappearance. To determine whether gadolinium enhancement is useful for predicting whether the hernia will disappear. To analyze whether the pattern of enhancement can help predict whether the fragment will disappear. This prospective study included 118 patients with acute symptoms of lumbosciatica and a herniated disc diagnosed by CT. In 72 patients, we performed gadolinium-enhanced MRI every 6 months for one year or until the herniation disappeared; we related the findings of protrusion, extrusion, and the enhancement pattern with the disappearance or persistence of herniated disc material. We analyzed the results with univariate and multivariate statistics. The 59% of the hernias disappeared within 1 year of follow-up and 66% disappeared within the first 8 months of follow-up. The 83% of the extruded hernias disappeared, and this was significant in the multivariate analysis (P<.005). The absence of enhancement was significantly associated with the persistence of the hernia in the univariate analysis. The enhancement pattern was not useful for predicting whether the hernia would disappear. Five hernias disappeared within the first two months. A high percentage of disc hernias disappear. We found a significant association between extrusion and disappearance but no correlation between the pattern of gadolinium uptake and the disappearance of the hernia. Copyright © 2010 SERAM. Published by Elsevier Espana. All rights reserved.

  4. Breakthrough reactions of iodinated and gadolinium contrast media after oral steroid premedication protocol

    PubMed Central

    2014-01-01

    Background Adverse reactions to iodinated and gadolinium contrast media are an important clinical issue. Although some guidelines have proposed oral steroid premedication protocols to prevent adverse reactions, some patients may have reactions to contrast media in spite of premedication (breakthrough reaction; BTR). The purpose of this study was to assess the frequency, type and severity of BTR when following an oral steroid premedication protocol. Methods All iodinated and gadolinium contrast-enhanced radiologic examinations between August 2011 and February 2013 for which the premedication protocol was applied in our institution were assessed for BTRs. Results The protocol was applied to a total of 252 examinations (153 patients, ages 15–87 years; 63 males, 90 females). Of these, 152 were for prior acute adverse reactions to contrast media, 85 were for a history of bronchial asthma, and 15 were for other reasons. There were 198 contrast enhanced CTs and 54 contrast enhanced MRIs. There were nine BTR (4.5%) for iodinated contrast media, and only one BTR (1.9%) for gadolinium contrast media: eight were mild and one was moderate. No patient who had a mild index reaction (IR) had a severe BTR. Conclusion Incidence of BTRs when following the premedication protocol was low. This study by no means proves the efficacy of premedication, but provides some support for following a premedication protocol to improve safety of contrast-enhanced examinations when prior adverse reactions are mild, or when there is a history of asthma. PMID:25287952

  5. Breakthrough reactions of iodinated and gadolinium contrast media after oral steroid premedication protocol.

    PubMed

    Jingu, Akiko; Fukuda, Junya; Taketomi-Takahashi, Ayako; Tsushima, Yoshito

    2014-10-06

    Adverse reactions to iodinated and gadolinium contrast media are an important clinical issue. Although some guidelines have proposed oral steroid premedication protocols to prevent adverse reactions, some patients may have reactions to contrast media in spite of premedication (breakthrough reaction; BTR).The purpose of this study was to assess the frequency, type and severity of BTR when following an oral steroid premedication protocol. All iodinated and gadolinium contrast-enhanced radiologic examinations between August 2011 and February 2013 for which the premedication protocol was applied in our institution were assessed for BTRs. The protocol was applied to a total of 252 examinations (153 patients, ages 15-87 years; 63 males, 90 females). Of these, 152 were for prior acute adverse reactions to contrast media, 85 were for a history of bronchial asthma, and 15 were for other reasons. There were 198 contrast enhanced CTs and 54 contrast enhanced MRIs. There were nine BTR (4.5%) for iodinated contrast media, and only one BTR (1.9%) for gadolinium contrast media: eight were mild and one was moderate. No patient who had a mild index reaction (IR) had a severe BTR. Incidence of BTRs when following the premedication protocol was low. This study by no means proves the efficacy of premedication, but provides some support for following a premedication protocol to improve safety of contrast-enhanced examinations when prior adverse reactions are mild, or when there is a history of asthma.

  6. Large Scale Testing and Development of Gadolinium Trichloride for Use in Neutron Detection in Large Water

    SciTech Connect

    Mark Vagine

    2007-09-18

    Water Cherenkov detectors have been used for many years as inexpensive, effective detectors for neutrino interactions and nucleon decay searches. While many important measurements have been made with these detectors a major drawback has been their inability to detect the absorption of thermal neutrons. We believe an inexpensive, effective technique could be developed to overcome this situation via the addition to water of a solute with a large neutron cross section and energetic gamma daughters which would make neutrons detectable. Gadolinium seems an excellent candidate especially since in recent years it has become very inexpensive, now less than $8 per kilogram in the form of commercially-available gadolinium trichloride, GdCl{sub 3}. This non-toxic, non-reactive substance is highly soluble in water. Neutron capture on gadolinium yields a gamma cascade which would be easily seen in detectors like Super-Kamiokande. We have begun to investigate the use of GdCl{sub 3} as a possible upgrade for the Super-Kamiokande detector with a view toward improving its performance as a detector for atmospheric neutrinos, supernova neutrinos, wrong-sign solar neutrinos, reactor neutrinos, proton decay, and also as a target for the coming T2K long-baseline neutrino experiment. This large-scale investigation, conducted in the one kiloton water Cherenkov detector built for the K2K long-baseline experiment, follows up on highly promising benchtop-scale work previously carried out with the assistance of a 2003 Advanced Detector Research Program grant.

  7. Thermal Excitation of Gadolinium-Based Contrast Agents Using Spin Resonance

    PubMed Central

    Fridjhon, Peter; Rubin, David M.

    2016-01-01

    Theoretical and experimental investigations into the thermal excitation of liquid paramagnetic contrast agents using the spin resonance relaxation mechanism are presented. The electronic spin-lattice relaxation time τ1e of gadolinium-based contrast agents, which is estimated at 0.1 ns, is ten orders of magnitude faster than the relaxation time of protons in water. The shorter relaxation time is found to significantly increase the rate of thermal energy deposition. To the authors’ knowledge this is the first study of gadolinium based contrast agents in a liquid state used as thermal agents. Analysis shows that when τ1e and other experimental parameters are optimally selected, a maximum theoretical heating rate of 29.4 °C.s−1 could be achieved which would suffice for clinical thermal ablation of neoplasms. The experimental results show a statistically significant thermal response for two out of the four contrast agents tested. The results are compared to the simulated estimates via analysis of a detailed model of the system. While these experimentally determined temperature rises are small and thus of no clinical utility, their presence supports the theoretical analysis and strongly suggests that the chemical structure of the selected compounds plays an important role in this mechanism of heat deposition. There exists an opportunity for the development of alternative gadolinium-based compounds with an order of magnitude longer τ1e in a diluted form to be used as an efficient hyperthermia agent for clinical use. PMID:27341338

  8. Study of the Photon Strength Functions for Gadolinium Isotopes with the DANCE Array

    NASA Astrophysics Data System (ADS)

    Dashdorj, D.; Mitchell, G. E.; Baramsai, B.; Chankova, R.; Chyzh, A.; Walker, C.; Agvaanluvsan, U.; Becker, J. A.; Parker, W.; Sleaford, B.; Wu, C. Y.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.; Krtička, M.; Bečvář, F.

    2009-03-01

    The gadolinium isotopes are interesting for reactor applications as well as for medicine and astrophysics. The gadolinium isotopes have some of the largest neutron capture cross sections. As a consequence they are used in the control rod in reactor fuel assembly. From the basic science point of view, there are seven stable isotopes of gadolinium with varying degrees of deformation. Therefore they provide a good testing ground for the study of deformation dependent structure such as the scissors mode. Decay gamma rays following neutron capture on Gd isotopes are detected by the DANCE array, which is located at flight path 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation and close packing of the detector array enable gamma-ray multiplicity measurements. The calorimetric properties of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a specific isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles gamma-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. Various photon strength function models are used for comparison with experimentally measured DANCE data and provide insight for understanding the statistical decay properties of deformed nuclei.

  9. Acute and chronic effects of sodium tungstate on an aquatic invertebrate (Daphnia magna), green alga (Pseudokirchneriella subcapitata), and zebrafish (Danio rerio).

    PubMed

    Clements, Leslie N; Lemus, Ranulfo; Butler, Alicia D; Heim, Kate; Rebstock, Matthew R; Venezia, Carmen; Pardus, Michael

    2012-10-01

    Although aquatic toxicity data exists for tungstate substances, insufficient data of high quality and relevancy are available for conducting an adequate risk assessment. Therefore, a series of acute and chronic toxicity tests with sodium tungstate (Na(2)WO(4)) were conducted on an aquatic invertebrate (Daphnia magna), green alga (Pseudokirchneriella subcapitata), and zebrafish (Danio rerio). Collectively, the data from these studies suggest that sodium tungstate exhibits a relatively low toxicity to these taxa under these test conditions. All studies were conducted in the same laboratory under good laboratory practice standards using Organisation for Economic Co-operation and Development guidelines with the same stock of test material and the same analytical methods. All results are reported as mg W/L. The following toxicity values were based on mean measured concentrations. For D. magna, the 21 day test no-observable effect concentration (NOEC) was 25.9 mg W/L, and the 48-h median effective concentration (EC(50)) from the acute test was >95.5 mg W/L (the highest concentration tested). The P. subcapitata test yielded an ErC(50) of 31 mg W/L. A 38-day test with zebrafish resulted in an NOEC ≥5.74 mg W/L with no effects at any concentration. The 96-h LC(50) from the acute test with zebrafish was >106 mg W/L. The results of the current acute study for daphnids and fish are consistent with published literature, whereas the algae results are different from previously reported values. Transformation/dissolution (T/D) studies, which were conducted according to United Nations Globally Harmonized System of Classification and Labelling of Chemicals protocol, confirmed that the WO (4) (-2) anion accounted for most of the tungsten in solution. For classification purposes, the algae ecotoxity reference value was then compared with T/D data and would not classify Na(2)WO(4) as an aquatic toxicant under the European Union Classification, Labelling and Packaging scheme.

  10. Incorporation of Integral Fuel Burnable Absorbers Boron and Gadolinium into Zirconium-Alloy Fuel Clad Material

    SciTech Connect

    Sridharan, K.; Renk, T.J.; Lahoda, E.J.; Corradini, M.L

    2004-12-14

    Long-lived fuels require the use of higher enrichments of 235U or other fissile materials. Such high levels of fissile material lead to excessive fuel activity at the beginning of life. To counteract this excessive activity, integral fuel burnable absorbers (IFBA) are added to some rods in the fuel assembly. The two commonly used IFBA elements are gadolinium, which is added as gadolinium-oxide to the UO2 powder, and boron, which is applied as a zirconium-diboride coating on the UO2 pellets using plasma spraying or chemical vapor deposition techniques. The incorporation of IFBA into the fuel has to be performed in a nuclear-regulated facility that is physically separated from the main plant. These operations tend to be very costly because of their small volume and can add from 20 to 30% to the manufacturing cost of the fuel. Other manufacturing issues that impact cost and performance are maintaining the correct levels of dosing, the reduction in fuel melting point due to gadolinium-oxide additions, and parasitic neutron absorption at fuel's end-of-life. The goal of the proposed research is to develop an alternative approach that involves incorporation of boron or gadolinium into the outer surface of the fuel cladding material rather than as an additive to the fuel pellets. This paradigm shift will allow for the introduction of the IFBA in a non-nuclear regulated environment and will obviate the necessity of additional handling and processing of the fuel pellets. This could represent significant cost savings and potentially lead to greater reproducibility and control of the burnable fuel in the early stages of the reactor operation. The surface alloying is being performed using the IBEST (Ion Beam Surface Treatment) process developed at Sandia National Laboratories. IBEST involves the delivery of energetic ion beam pulses onto the surface of a material, near-surface melting, and rapid solidification. The non-equilibrium nature of such processing allows for surface

  11. Gadolinium-148 and other spallation production cross section measurements for accelerator target facilities

    NASA Astrophysics Data System (ADS)

    Kelley, Karen Corzine

    At the Los Alamos Neutron Science Center accelerator complex, protons are accelerated to 800 MeV and directed to two tungsten targets, Target 4 at the Weapons Neutron Research facility and the 1L target at the Lujan Center. The Department of Energy requires hazard classification analyses to be performed on these targets and places limits on certain radionuclide inventories in the targets to avoid characterizing the facilities as "nuclear facilities." Gadolinium-148 is a radionuclide created from the spallation of tungsten. Allowed isotopic inventories are particularly low for this isotope because it is an alpha-particle emitter with a 75-year half-life. The activity level of Gadolinium-148 is low, but it encompasses almost two-thirds of the total dose burden for the two tungsten targets based on present yield estimates. From a hazard classification standpoint, this severely limits the lifetime of these tungsten targets. The cross section is not well-established experimentally and this is the motivation for measuring the Gadolinium-148 production cross section from tungsten. In a series of experiments at the Weapons Neutron Research facility, Gadolinium-148 production was measured for 600- and 800-MeV protons on tungsten, tantalum, and gold. These experiments used 3 mum thin tungsten, tantalum, and gold foils and 10 mum thin aluminum activation foils. In addition, spallation yields were determined for many short-lived and long-lived spallation products with these foils using gamma and alpha spectroscopy and compared with predictions of the Los Alamos National Laboratory codes CEM2k+GEM2 and MCNPX. The cumulative Gadolinium-148 production cross section measured from tantalum, tungsten, and gold for incident 600-MeV protons were 15.2 +/- 4.0, 8.31 +/- 0.92, and 0.591 +/- 0.155, respectively. The average production cross sections measured at 800 MeV were 28.6 +/- 3.5, 19.4 +/- 1.8, and 3.69 +/- 0.50 for tantalum, tungsten, and gold, respectively. These cumulative

  12. A study of high-energy proton induced damage in cerium fluoride in comparison with measurements in lead tungstate calorimeter crystals

    NASA Astrophysics Data System (ADS)

    Dissertori, G.; Lecomte, P.; Luckey, D.; Nessi-Tedaldi, F.; Pauss, F.; Otto, Th.; Roesler, S.; Urscheler, Ch.

    2010-10-01

    A CeF3 crystal produced during early R&D studies for calorimetry at the CERN Large Hadron Collider was exposed to a 24 GeV/c proton fluence Φp=(2.78±0.20)×1013 cm-2 and, after one year of measurements tracking its recovery, to a fluence Φp=(2.12±0.15)×1014 cm-2. Results on proton-induced damage in the crystal and its spontaneous recovery after both irradiations are presented here, along with some new, complementary data on proton-damage in lead tungstate. A comparison with FLUKA Monte Carlo simulation results is performed and a qualitative understanding of high-energy damage mechanism is attempted.

  13. Morphological evolution and visible light-induced degradation of Rhodamine 6G by nanocrystalline bismuth tungstate prepared using a template-based approach

    NASA Astrophysics Data System (ADS)

    Silva, Raissa Mendes; Batista Barbosa, Diego Augusto; de Jesus Silva Mendonça, Caritas; de Oliveira Lima, José Renato; Silva, Fernando Carvalho; Longo, Elson; Maciel, Adeilton Pereira; de Araujo Paschoal, Carlos William; Almeida, Marcio Aurélio Pinheiro

    2016-09-01

    The cleaning of water contaminated with organic dyes is a crucial problem nowadays. The search for good catalysts is intense, and bismuth tungstates have attracted a lot of attention because of their catalytic properties which are related to their crystal structure and morphology. In this study, we show that Bi2WO6 (BWO) crystals synthesized by the surfactant-assisted hydrothermal method create a different morphology than non-assisted crystals. With the assistance of the PVP surfactant, even the BWO crystalline structure could change, crystallizing into a high-symmetry metastable phase. These changes in morphology imply a decrease in BWO catalytic activity, which shows that insightful control of BWO synthesis is necessary to improve the BWO properties.

  14. Use of sodium tungstate as a permanent chemical modifier for slurry sampling electrothermal atomic absorption spectrometric determination of indium in soils.

    PubMed

    López-García, Ignacio; Rivas, Ricardo E; Hernández-Córdoba, Manuel

    2008-06-01

    A number of chemical modifiers have been assessed for the direct determination of indium in soils using electrothermal atomic absorption spectrometry and slurry sampling. The best results were obtained when the graphite atomizer was impregnated with sodium tungstate, which acts as a permanent chemical modifier. Slurries were prepared by suspending 100 mg sample in a solution containing 1% (v/v) concentrated nitric acid and 10% (v/v) concentrated hydrofluoric acid and then 15-microL aliquots were directly introduced into the atomizer. Standard indium solutions prepared in the suspension medium in the range 4-80 microg L(-1) indium were used for calibration. The relative standard deviation for ten consecutive measurements of a 40 microg L(-1) indium solution was 2.8%. The limit of detection in soils was 0.1 microg g(-1). The reliability of the procedures was confirmed by analysing two standard reference materials and by using an alternative procedure.

  15. PAPERS DEVOTED TO THE 90TH ANNIVERSARY OF A.M.PROKHOROV: Lasing properties of selectively pumped Raman-active Nd3+-doped molybdate and tungstate crystals

    NASA Astrophysics Data System (ADS)

    Basiev, Tasoltan T.; Doroshenko, Maxim E.; Ivleva, Lyudmila I.; Osiko, Vyacheslav V.; Kosmyna, M. B.; Komar', V. K.; Sulc, J.; Jelinkova, H.

    2006-08-01

    The lasing efficiency of Nd3+ ions is studied in laser materials capable of self-Raman frequency conversion. The lasing properties of tungstate and molybdate crystals with the scheelite structure (SrWO4, BaWO4, PbWO4, SrMoO4, PbMoO4) activated with neodymium ions are investigated upon longitudinal pumping by a 750-nm alexandrite laser or a 800-nm diode laser. The slope lasing efficiency obtained for a Nd3+:PbMoO4 laser emitting at 1054 nm is 54.3% for the total lasing efficiency of 46%, which is the best result for all the crystals with the scheelite structure studied so far. The simultaneous Q-switched lasing and self-Raman frequency conversion were demonstrated in neodymium-doped SrWO4, PbWO4, and BaWO4 crystals.

  16. Does gadolinium-based contrast material improve diagnostic accuracy of local invasion in rectal cancer MRI? A multireader study.

    PubMed

    Gollub, Marc J; Lakhman, Yulia; McGinty, Katrina; Weiser, Martin R; Sohn, Michael; Zheng, Junting; Shia, Jinru

    2015-02-01

    OBJECTIVE. The purpose of this study was to compare reader accuracy and agreement on rectal MRI with and without gadolinium administration in the detection of T4 rectal cancer. MATERIALS AND METHODS. In this study, two radiologists and one fellow independently interpreted all posttreatment MRI studies for patients with locally advanced or recurrent rectal cancer using unenhanced images alone or combined with contrast-enhanced images, with a minimum interval of 4 weeks. Readers evaluated involvement of surrounding structures on a 5-point scale and were blinded to pathology and disease stage. Sensitivity, specificity, negative predictive value, positive predictive value, and AUC were calculated and kappa statistics were used to describe interreader agreement. RESULTS. Seventy-two patients (38 men and 34 women) with a mean age of 61 years (range, 32-86 years) were evaluated. Fifteen patients had 32 organs invaded. Global AUCs without and with gadolinium administration were 0.79 and 0.77, 0.91 and 0.86, and 0.83 and 0.78 for readers 1, 2, and 3, respectively. AUCs before and after gadolinium administration were similar. Kappa values before and after gadolinium administration for pairs of readers ranged from 0.5 to 0.7. CONCLUSION. On the basis of pathology as a reference standard, the use of gadolinium during rectal MRI did not significantly improve radiologists' agreement or ability to detect T4 disease.

  17. The Effect of gadolinium on the ESR response of alanine and ammonium tartrate exposed to thermal neutrons.

    PubMed

    Marrale, Maurizio; Brai, Maria; Gennaro, Gaetano; Bartolotta, Antonio; D'Oca, Maria Cristina

    2008-02-01

    Many efforts have been made to develop neutron capture therapy (NCT) for cancer treatment. Among the challenges in using NCT is the characterization of the features of the mixed radiation field and of its components. In this study, we examined the enhancement of the ESR response of pellets of alanine and ammonium tartrate with gadolinium oxide exposed to a thermal neutron beam. In particular, the ESR response of these dosimeters as a function of the gadolinium content inside the dosimeter was analyzed. We found that the addition of gadolinium improves the sensitivity of both alanine and ammonium tartrate. However, the use of gadolinium reduces or abolishes tissue equivalence because of its high atomic number (Z(Gd) = 64). Therefore, it is necessary to find the optimum compromise between the sensitivity to thermal neutrons and the reduction of tissue equivalence. Our analysis showed that a low concentration of gadolinium oxide (of the order of 5% of the total mass of the dosimeter) can enhance the thermal neutron sensitivity more than 13 times with an insignificant reduction of tissue equivalence.

  18. Characterization of the reaction products and precipitates at the interface of carbon fiber reinforced magnesium–gadolinium composite

    SciTech Connect

    Wang, Yaping; Jiang, Longtao; Chen, Guoqin; Lin, Xiu; Zhang, Shaofeng; Pei, Risheng; Wu, Gaohui

    2016-03-15

    In the present work, carbon fiber reinforced magnesium-gadolinium composite was fabricated by pressure infiltration method. The phase composition, micro-morphology, and crystal structure of reaction products and precipitates at the interface of the composite were investigated. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed the segregation of gadolinium element at the interface between carbon fiber and matrix alloy. It was shown that block-shaped Gd4C5, GdC2 and nano-sized Gd2O3 were formed at the interface during the fabrication process due to the interfacial reaction. Furthermore, magnesium-gadolinium precipitates including needle-like Mg5Gd (or Mg24Gd5) and thin plate-shaped long period stacking-ordered phase, were also observed at the interface and in the matrix near the interface. The interfacial microstructure and bonding mode were influenced by these interfacial products, which were beneficial for the improvement of the interfacial bonding strength. - Highlights: • Gadolinium element segregated on the surface of carbon fibers. • Block-shaped Gd{sub 4}C{sub 5} and GdC{sub 2} were formed at the interface via chemical reaction. • Gadolinium and oxygen reacted at the interface and formed nano-scaled Gd{sub 2}O{sub 3}. • The precipitates formed in the interface were identified to be Mg{sub 5}Gd (or Mg{sub 24}Gd{sub 5}) and plate-shaped long period stacking-ordered phase.

  19. Positive gadolinium anomalies in wastewater treatment plant effluents and aquatic environment in the Hérault watershed (South France).

    PubMed

    Rabiet, M; Brissaud, F; Seidel, J L; Pistre, S; Elbaz-Poulichet, F

    2009-05-01

    Anthropogenic gadolinium (Gd), used as a contrast agent in magnetic resonance imaging, may enter rivers and groundwaters with the effluents of wastewater treatment plant (WWTP). Such contaminations, which are mainly found in densely populated areas with highly developed medical systems, induce positive gadolinium anomalies in waters. This study reports on the occurrence of positive Gd anomaly in wastewaters, surface and groundwaters in a slightly populated Mediterranean watershed. Water samples have been collected along the Hérault River, in its tributaries, in wells and springs supplying drinking water and in WWTP effluents during two sampling campaigns in February and July 2003. Systematically pronounced positive gadolinium anomalies (Gd/Gd( *)) were observed in WWTP effluents with values reaching 306. These observations have shown that Gd/Gd( *) can also be found in wastewater drained from rural communities, not equipped with MRI facilities. Positive gadolinium anomalies were detected in two tributaries of the Hérault River and in some wells supplying drinking water, corresponding to an excess of anthropogenic Gd in water up to 15.4pM. A monthly monitoring on one well has confirmed the persistence of gadolinium anomalies all along the year, suggesting a continual wastewater contamination on this site. A spatial monitoring on one tributary showed that wastewater contribution modifies completely the normalized REE pattern of river water, resulting in a decrease of REE amount correlated to the Gd anomaly appearance.

  20. A feasibility study to determine the potential of in vivo detection of gadolinium by x-ray fluorescence (XRF) following gadolinium-based contrast-enhanced MRI.

    PubMed

    Mostafaei, F; McNeill, F E; Chettle, D R; Noseworthy, M D

    2015-01-01

    The feasibility of using a (109)Cd γ-ray induced K x-ray fluorescence (K-XRF) system for the in vivo detection of gadolinium (Gd) in bone has been investigated. The K-XRF bone measurement system employs an array of four detectors, and is normally used for the non-invasive study of bone lead levels. The system was used to measure bone simulating phantoms doped with varying levels of gadolinium and fixed amounts of sodium (Na), chlorine (Cl) and calcium (Ca). The detection limits for bare bone phantoms, using a source of activity 0.17 GBq, were determined to be 3.9 ppm and 6.5 ppm (µg Gd per gram phantom) for the Kα1 and Kα2 Gd x-ray peaks, respectively. This leads to an overall detection limit of 3.3 ppm (µg Gd per gram phantom). Layers of plastic were used to simulate overlying soft tissue and this permitted prediction of a detection limit, using the current strength of our radioisotope source, of 6.1 ppm to 8.6 ppm (µg Gd per gram phantom) for fingers with 2-4 mm of overlying tissue. With a new source of activity 5 GBq, we predict that this system could achieve a detection limit of 4-5.6 µg Gd g(-1) Ca. This is within the range of levels (2-30 µg Gd g(-1) Ca) previously found in the bone of patients receiving Gd based contrast imaging agents. The technique is promising and warrants further investigation.

  1. Nephrogenic systemic fibrosis: change in incidence following a switch in gadolinium agents and adoption of a gadolinium policy--report from two U.S. universities.

    PubMed

    Altun, Ersan; Martin, Diego R; Wertman, Rebecca; Lugo-Somolinos, Aida; Fuller, Edwin R; Semelka, Richard C

    2009-12-01

    To determine the incidence of nephrogenic systemic fibrosis (NSF) in tertiary care centers of two U.S. universities following the switch from the use of gadodiamide to gadobenate dimeglumine and gadopentetate dimeglumine, and the adoption of restrictive gadolinium-based contrast agent (GBCA) policies. Institutional review board approval with waiver of informed consent was obtained for this Health Insurance Portability and Accountability Act-compliant retrospective study. NSF patients were identified between January 2000 and December 2006 at center A and between October 2003 and February 2007 at center B (preadoption periods); and from June 2007 to June 2008 at both centers (postadoption period). The numbers of patients who underwent gadolinium-enhanced magnetic resonance at each center, patients at risk for NSF at center A, and dialysis patients at center B were identified in the pre- and postadoption periods. Gadodiamide was the only agent used in the preadoption period. Gadobenate dimeglumine and gadopentetate dimeglumine were the agents used in the postadoption period. A restrictive GBCA policy that limits the use and dose of GBCAs in patients with risk factors was adopted in the postadoption period. Follow-up lasted 9 months from July 2008 to March 2009. Corresponding incidences were determined and compared with the Fisher exact test. Respective total benchmark incidence of NSF at both centers, at-risk incidence of NSF at center A, and dialysis incidence of NSF at center B were 37 of 65 240, 28 of 925, and nine of 312 in the preadoption period and zero of 25 167, zero of 147, and zero of 402 in the postadoption period. All three incidences demonstrated significant differences (P < .0001, .024, and .001, respectively) between the pre- and postadoption periods. Following the switch from gadodiamide to gadobenate dimeglumine and gadopentetate dimeglumine, and the adoption of restrictive GBCA policies, no NSF cases were observed at either center.

  2. Relaxometric studies of gadolinium-functionalized perfluorocarbon nanoparticles for MR imaging.

    PubMed

    de Vries, Anke; Moonen, Rik; Yildirim, Muhammed; Langereis, Sander; Lamerichs, Rolf; Pikkemaat, Jeroen A; Baroni, Simona; Terreno, Enzo; Nicolay, Klaas; Strijkers, Gustav J; Grüll, Holger

    2014-01-01

    Fluorine MRI ((19) F MRI) is receiving an increasing attention as a viable alternative to proton-based MRI ((1) H MRI) for dedicated application in molecular imaging. The (19) F nucleus has a high gyromagnetic ratio, a 100% natural abundance and is furthermore hardly present in human tissues allowing for hot spot MR imaging. The applicability of (19) F MRI as a molecular and cellular imaging technique has been exploited, ranging from cell tracking to detection and imaging of tumors in preclinical studies. In addition to applications, developing new contrast materials with improved relaxation properties has also been a core research topic in the field, since the inherently low longitudinal relaxation rates of perfluorocarbon compounds result in relatively low imaging efficiency. Borrowed from (1) H MRI, the incorporation of lanthanides, specifically Gd(III) complexes, as signal modulating ingredients in the nanoparticle formulation has emerged as a promising approach to improvement of the fluorine signal. Three different perfluorocarbon emulsions were investigated at five different magnetic field strengths. Perfluoro-15-crown-5-ether was used as the core material and Gd(III)DOTA-DSPE, Gd(III)DOTA-C6-DSPE and Gd(III)DTPA-BSA as the relaxation altering components. While Gd(III)DOTA-DSPE and Gd(III)DOTA-C6-DSPE were favorable constructs for (1) H NMR, Gd(III)DTPA-BSA showed the strongest increase in (19F) R(1). These results show the potential of the use of paramagnetic lipids to increase (19F) R(1) at clinical field strengths (1.5-3 T). At higher field strengths (6.3-14 T), gadolinium does not lead to an increase in (19F) R(1) compared with emulsions without gadolinium, but leads to an significant increase in (19F) R(2). Our data therefore suggest that the most favorable situation for fluorine measurements is at high magnetic fields without the inclusion of gadolinium constructs.

  3. Effects of gadolinium oxide nanoparticles on the oxidative burst from human neutrophil granulocytes

    NASA Astrophysics Data System (ADS)

    Abrikossova, Natalia; Skoglund, Caroline; Ahrén, Maria; Bengtsson, Torbjörn; Uvdal, Kajsa

    2012-07-01

    We have previously shown that gadolinium oxide (Gd2O3) nanoparticles are promising candidates to be used as contrast agents in magnetic resonance (MR) imaging applications. In this study, these nanoparticles were investigated in a cellular system, as possible probes for visualization and targeting intended for bioimaging applications. We evaluated the impact of the presence of Gd2O3 nanoparticles on the production of reactive oxygen species (ROS) from human neutrophils, by means of luminol-dependent chemiluminescence. Three sets of Gd2O3 nanoparticles were studied, i.e. as synthesized, dialyzed and both PEG-functionalized and dialyzed Gd2O3 nanoparticles. In addition, neutrophil morphology was evaluated by fluorescent staining of the actin cytoskeleton and fluorescence microscopy. We show that surface modification of these nanoparticles with polyethylene glycol (PEG) is essential in order to increase their biocompatibility. We observed that the as synthesized nanoparticles markedly decreased the ROS production from neutrophils challenged with prey (opsonized yeast particles) compared to controls without nanoparticles. After functionalization and dialysis, more moderate inhibitory effects were observed at a corresponding concentration of gadolinium. At lower gadolinium concentration the response was similar to that of the control cells. We suggest that the diethylene glycol (DEG) present in the as synthesized nanoparticle preparation is responsible for the inhibitory effects on the neutrophil oxidative burst. Indeed, in the present study we also show that even a low concentration of DEG, 0.3%, severely inhibits neutrophil function. In summary, the low cellular response upon PEG-functionalized Gd2O3 nanoparticle exposure indicates that these nanoparticles are promising candidates for MR-imaging purposes.

  4. Toward modeling phosphate tellurate glasses: the devitrification and addition of gadolinium ions behavior.

    PubMed

    Rada, S; Culea, M; Culea, E

    2008-11-06

    Glasses in the xGd2O3 x (100 - x)[7TeO2 x 3P2O5] system with 0 < or = x < or = 20 mol % have been prepared using the melt quenching method. The influence of gadolinium ions on structural behavior of the phosphate tellurate glass has been investigated using infrared spectroscopy and density functional theory (DFT) calculations. The addition of gadolinium ions into the host glass matrix leads to an increase of the glass network polymerization due to the replacement of P-O-P bonds by the more resistant P-O-Te bonds having as result the improvement of the chemical durability of the glass. The structural evolution of the studied glasses with the gradual increase of the gadolinium oxide content up to 20 mol % could be explained by considering that the excess of oxygen may be accommodated by the conversion of some orthophosphate structural units into metaphosphate or/and pyrophosphate units. X-ray diffraction and IR spectra revealed that heat treatment of the samples also causes an increase of the glass network polymerization for heat treatment times, t, up to 36 h, while for 36 h > t > or = 48 h showed a drastic structural modification which lead to the apparition of the Te4P2O13 crystalline phase. DFT calculations show that tellurium atoms occupy two different sites in the proposed model. In the first case the tellurium atom is coordinated with four oxygen atoms giving a trigonal bipyramide arrangement, while in the second case the tellurium atom is coordinated with three O atoms. The calculated IR absorption spectrum of the proposed model for phosphotellurite glasses is in good agreement with the experimental absorption data.

  5. Quantitative assessment of the rheumatoid synovial microvascular bed by gadolinium-DTPA enhanced magnetic resonance imaging

    PubMed Central

    Gaffney, K.; Cookson, J.; Blades, S.; Coumbe, A.; Blake, D.

    1998-01-01

    OBJECTIVE—To examine the relation between rate of synovial membrane enhancement, intra-articular pressure (IAP), and histologically determined synovial vascularity in rheumatoid arthritis, using gadolinium-DTPA enhanced magnetic resonance imaging (MRI).
METHODS—Dynamic gadolinium-DTPA enhanced MRI was performed in 31 patients with knee synovitis (10 patients IAP study, 21 patients vascular morphometry study). Rate of synovial membrane enhancement was quantified by line profile analysis using the image processing package ANALYZE. IAP was measured using an intra-compartmental pressure monitor system. Multiple synovial biopsy specimens were obtained by a blind biopsy technique. Blood vessels were identified immunohistochemically using the endothelial cell marker QBend30 and quantified (blood vessel numerical density and fractional area).
RESULTS—Median blood vessel numerical density and fractional area were 77.5/mm2 (IQR; 69.3-110.7) and 5.6% (IQR; 3.4-8.5) respectively. The rate of synovial membrane enhancement (median 2.74 signal intensity units/s, IQR 2.0-3.8) correlated with both blood vessel numerical density (r = 0.46, p < 0.05) and blood vessel fractional area (r = 0.55, p < 0.02). IAP did not influence the rate of enhancement.
CONCLUSIONS—Gadolinium-DTPA enhanced MRI may prove to be a valuable technique for evaluating drugs that influence angiogenesis.

 Keywords: magnetic resonance imaging; rheumatoid arthritis; synovitis; vascularity PMID:9640130

  6. Influence of acquired obesity on coronary vessel wall late gadolinium enhancement in discordant monozygote twins.

    PubMed

    Makowski, Marcus R; Jansen, Christian H P; Ebersberger, Ullrich; Schaeffter, Tobias; Razavi, Reza; Mangino, Massimo; Spector, Tim D; Botnar, Rene M; Greil, Gerald F

    2016-10-14

    The aim of this study was to investigate the impact of BMI on late gadolinium enhancement (LGE) of the coronary artery wall in identical monozygous twins discordant for BMI. Coronary LGE represents a useful parameter for the detection and quantification of atherosclerotic coronary vessel wall disease. Thirteen monozygote female twin pairs (n = 26) with significantly different BMIs (>1.6 kg/m2) were recruited out of >10,000 twin pairs (TwinsUK Registry). A coronary 3D-T2prep-TFE MR angiogram and 3D-IR-TFE vessel wall scan were performed prior to and following the administration of 0.2 mmol/kg of Gd-DTPA on a 1.5 T MR scanner. The number of enhancing coronary segments and contrast to noise ratios (CNRs) of the coronary wall were quantified. An increase in BMI was associated with an increased number of enhancing coronary segments (5.3 ± 1.5 vs. 3.5 ± 1.6, p < 0.0001) and increased coronary wall enhancement (6.1 ± 1.1 vs. 4.8 ± 0.9, p = 0.0027) compared to matched twins with lower BMI. This study in monozygous twins indicates that acquired factors predisposing to obesity, including lifestyle and environmental factors, result in increased LGE of the coronary arteries, potentially reflecting an increase in coronary atherosclerosis in this female study population. • BMI-discordant twins allow the investigation of the influence of lifestyle factors independent from genetic confounders. • Only thirteen obesity-discordant twins were identified underlining the strong genetic component of BMI. • In female twins, a BMI increase is associated with increased coronary late gadolinium enhancement. • Increased late gadolinium enhancement in the coronary vessel wall potentially reflects increased atherosclerosis.

  7. Size-dependent Strain in Epitaxial (001) Gadolinium-doped Ceria Nanoislands

    SciTech Connect

    Solovyov, V.F.; Gibert, M.; Puig, T.; Obradors, X.

    2010-12-06

    We report size-dependent strain in epitaxial gadolinium doped ceria nanoislands, which was determined by synchrotron x-ray diffraction. Reciprocal space sections of symmetric, (004) and asymmetric, (224) reflections are approximated by a model assuming size-dependent strain of the islands using real-space size distribution obtained by atomic force microscopy. We show that the islands smaller than 40 nm are subjected to a high level of lateral tensile strain and normal compression. The lateral to normal strain ratio determined from the reciprocal map analysis suggests that lateral tension is the primary stress generator, possibly due to oxygen vacancy ordering on the island-substrate interface.

  8. Size-dependent Strain in Epitaxial (001)Gadolinium-doped Ceria Nanoislands

    SciTech Connect

    V Solovyov; M Gibert; T Puig; X Obradors

    2011-12-31

    We report size-dependent strain in epitaxial gadolinium doped ceria nanoislands, which was determined by synchrotron x-ray diffraction. Reciprocal space sections of symmetric, (004) and asymmetric, (224) reflections are approximated by a model assuming size-dependent strain of the islands using real-space size distribution obtained by atomic force microscopy. We show that the islands smaller than 40 nm are subjected to a high level of lateral tensile strain and normal compression. The lateral to normal strain ratio determined from the reciprocal map analysis suggests that lateral tension is the primary stress generator, possibly due to oxygen vacancy ordering on the island-substrate interface.

  9. Size-dependent strain in epitaxial (001) gadolinium-doped ceria nanoislands

    NASA Astrophysics Data System (ADS)

    Solovyov, Vyacheslav F.; Gibert, Marta; Puig, Teresa; Obradors, Xavier

    2010-12-01

    We report size-dependent strain in epitaxial gadolinium doped ceria nanoislands, which was determined by synchrotron x-ray diffraction. Reciprocal space sections of symmetric, (004) and asymmetric, (224) reflections are approximated by a model assuming size-dependent strain of the islands using real-space size distribution obtained by atomic force microscopy. We show that the islands smaller than 40 nm are subjected to a high level of lateral tensile strain and normal compression. The lateral to normal strain ratio determined from the reciprocal map analysis suggests that lateral tension is the primary stress generator, possibly due to oxygen vacancy ordering on the island-substrate interface.

  10. Structural and chemical analysis of gadolinium halides encapsulated within WS2 nanotubes

    NASA Astrophysics Data System (ADS)

    Anumol, E. A.; Enyashin, Andrey N.; Batra, Nitin M.; Costa, Pedro M. F. J.; Deepak, Francis Leonard

    2016-06-01

    The hollow cavities of nanotubes serve as templates for the growth of size- and shape-confined functional nanostructures, giving rise to novel materials and properties. In this work, considering their potential application as MRI contrast agents, gadolinium halides are encapsulated within the hollow cavities of WS2 nanotubes by capillary filling to obtain GdX3@WS2 nanotubes (where X = Cl, Br or I and @ means encapsulated in). Aberration corrected scanning/transmission electron microscopy (S/TEM) and spectroscopy is employed to understand the morphology and composition of the GdI3@WS2 nanotubes. The three dimensional morphology is studied with STEM tomography but understanding the compositional information is non-trivial due to the presence of multiple high atomic number elements. Therefore, energy dispersive X-ray spectroscopy (EDS) tomography was employed revealing the three dimensional chemical composition. Molecular dynamics simulations of the filling procedure shed light into the mechanics behind the formation of the confined gadolinium halide crystals. The quasi-1D system employed here serves as an example of a TEM-based chemical nanotomography method that could be extended to other materials, including beam-sensitive soft materials.The hollow cavities of nanotubes serve as templates for the growth of size- and shape-confined functional nanostructures, giving rise to novel materials and properties. In this work, considering their potential application as MRI contrast agents, gadolinium halides are encapsulated within the hollow cavities of WS2 nanotubes by capillary filling to obtain GdX3@WS2 nanotubes (where X = Cl, Br or I and @ means encapsulated in). Aberration corrected scanning/transmission electron microscopy (S/TEM) and spectroscopy is employed to understand the morphology and composition of the GdI3@WS2 nanotubes. The three dimensional morphology is studied with STEM tomography but understanding the compositional information is non-trivial due to the

  11. Active extravasation of gadolinium-based contrast agent into the subdural space following lumbar puncture.

    PubMed

    Kothari, Pranay D; Hanser, Evelyn M; Wang, Harrison; Farid, Nikdokht

    2016-01-01

    A 38year-old male presented with cauda equina syndrome following multiple lumbar puncture attempts. Lumbar spine magnetic resonance imaging (MRI) showed a subdural hematoma and an area of apparent contrast enhancement in the spinal canal on sagittal post-contrast images. Axial post-contrast images obtained seven minutes later demonstrated an increase in size and change in shape of the region of apparent contrast enhancement, indicating active extravasation of the contrast agent. This is the first reported case of active extravasation of gadolinium-based contrast agent in the spine.

  12. Modification of the crystal structure of gadolinium gallium garnet by helium ion irradiation

    SciTech Connect

    Ostafiychuk, B. K.; Yaremiy, I. P. Yaremiy, S. I.; Fedoriv, V. D.; Tomyn, U. O.; Umantsiv, M. M.; Fodchuk, I. M.; Kladko, V. P.

    2013-12-15

    The structure of gadolinium gallium garnet (GGG) single crystals before and after implantation by He{sup +} ions has been investigated using high-resolution X-ray diffraction methods and the generalized dynamic theory of X-ray scattering. The main types of growth defects in GGG single crystals and radiation-induced defects in the ion-implanted layer have been determined. It is established that the concentration of dislocation loops in the GGG surface layer modified by ion implantation increases and their radius decreases with an increase in the implantation dose.

  13. Safety Evaluation and Imaging Properties of Gadolinium-Based Nanoparticles in nonhuman primates

    PubMed Central

    Kotb, Shady; Piraquive, Joao; Lamberton, Franck; Lux, François; Verset, Michael; Di Cataldo, Vanessa; Contamin, Hugues; Tillement, Olivier; Canet-Soulas, Emmanuelle; Sancey, Lucie

    2016-01-01

    In this article, we report the safety evaluation of gadolinium-based nanoparticles in nonhuman primates (NHP) in the context of magnetic resonance imaging (MRI) studies in atherosclerosis bearing animals and healthy controls. In healthy NHP, the pharmacokinetics and toxicity profiles demonstrated the absence of dose, time, and sex-effects, as well as a suitable tolerance of intravenous administration of the nanoparticles. We investigated their imaging properties for arterial plaque imaging in a standard diet or a high cholesterol diet NHP, and compared their characteristics with clinically applied Gd-chelate. This preliminary investigation reports the efficient and safe imaging of atherosclerotic plaques. PMID:27725693

  14. The developmental history of the gadolinium chelates as intravenous contrast media for magnetic resonance.

    PubMed

    Runge, Val M; Ai, Tao; Hao, Dapeng; Hu, Xuemei

    2011-12-01

    The developmental history of the gadolinium chelates, which spans 30 years, is described, focusing, in part, on the seminal work with each of the major agents in use today. By examining this history, insight is gained into important issues of efficacy and safety, with valuable lessons to be learned from the mistakes made during this period. An overview of physicochemical characteristics and chemical structures is also provided. The review concludes with a discussion of current research directions involving this field, which is that of the intravenous contrast media for magnetic resonance, in the past 5 years.

  15. Gadolinium(III)-sensitized fluorescence of europium in its mixed-metal compounds with trifluroacetate

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.; Zadorozhnaya, A. N.

    2017-04-01

    The fluorescence properties of mixed-metal compounds of Eu(III) and Gd(III) with trifluoroacetic acid, Eu1-xGdx(C2F3O2)3·yD·zH2O, where D - 1,10-phenanthroline, 2,2-dipyridil, diphenylguanidine, x = 0, 0.25, 0.5, or 0.7, were studied. Luminescence spectroscopic evidence and the examination of excitation spectra indicate the occurrence of efficient energy transfer from the gadolinium to the europium ion. The greatest promotion of Eu3+ photoluminescence at 615 nm is observed when Eu:Gd = 1:1.

  16. Geometrically confined ultrasmall gadolinium oxide nanoparticles boost the T1 contrast ability

    NASA Astrophysics Data System (ADS)

    Ni, Kaiyuan; Zhao, Zhenghuan; Zhang, Zongjun; Zhou, Zijian; Yang, Li; Wang, Lirong; Ai, Hua; Gao, Jinhao

    2016-02-01

    High-performance magnetic resonance imaging (MRI) contrast agents and novel contrast enhancement strategies are urgently needed for sensitive and accurate diagnosis. Here we report a strategy to construct a new T1 contrast agent based on the Solomon-Bloembergen-Morgan (SBM) theory. We loaded the ultrasmall gadolinium oxide nanoparticles into worm-like interior channels of mesoporous silica nanospheres (Gd2O3@MSN nanocomposites). This unique structure endows the nanocomposites with geometrical confinement, high molecular tumbling time, and a large coordinated number of water molecules, which results in a significant enhancement of the T1 contrast with longitudinal proton relaxivity (r1) as high as 45.08 mM-1 s-1. Such a high r1 value of Gd2O3@MSN, compared to those of ultrasmall Gd2O3 nanoparticles and gadolinium-based clinical contrast agents, is mainly attributed to the strong geometrical confinement effect. This strategy provides new guidance for developing various high-performance T1 contrast agents for sensitive imaging and disease diagnosis.High-performance magnetic resonance imaging (MRI) contrast agents and novel contrast enhancement strategies are urgently needed for sensitive and accurate diagnosis. Here we report a strategy to construct a new T1 contrast agent based on the Solomon-Bloembergen-Morgan (SBM) theory. We loaded the ultrasmall gadolinium oxide nanoparticles into worm-like interior channels of mesoporous silica nanospheres (Gd2O3@MSN nanocomposites). This unique structure endows the nanocomposites with geometrical confinement, high molecular tumbling time, and a large coordinated number of water molecules, which results in a significant enhancement of the T1 contrast with longitudinal proton relaxivity (r1) as high as 45.08 mM-1 s-1. Such a high r1 value of Gd2O3@MSN, compared to those of ultrasmall Gd2O3 nanoparticles and gadolinium-based clinical contrast agents, is mainly attributed to the strong geometrical confinement effect. This strategy

  17. Controlled manipulation of gadolinium-coordinated supramolecules by low-temperature scanning tunneling microscopy.

    PubMed

    Urgel, José I; Ecija, David; Auwärter, Willi; Barth, Johannes V

    2014-03-12

    Coordination bonding between para-quarterphenyl-dicarbonitrile linkers and gadolinium on Ag(111) has been exploited to construct pentameric mononuclear supramolecules, consisting of a rare-earth center surrounded by five molecular linkers. By employing a scanning tunneling microscope tip, a manipulation protocol was developed to position individual pentamers on the surface. In addition, the tip was used to extract and replace individual linkers yielding tetrameric, pentameric, nonameric, and dodecameric metallosupramolecular arrangements. These results open new avenues toward advanced nanofabrication methods and rare-earth nanochemistry by combining the versatility of metal-ligand interactions and atomistic manipulation capabilities.

  18. Fragmenting gadolinium: mononuclear polyoxometalate-based magnetic coolers for ultra-low temperatures.

    PubMed

    Martínez-Pérez, María-José; Montero, Oscar; Evangelisti, Marco; Luis, Fernando; Sesé, Javier; Cardona-Serra, Salvador; Coronado, Eugenio

    2012-08-16

    The polyoxometalate clusters with formula [Gd(W(5) O(18) )(2) ](9-) and [Gd(P(5) W(30) O(110) )](12-) each carry a single magnetic ion of gadolinium, which is the most widespread element among magnetic refrigerant materials. In an adiabatic demagnetization, the lowest attainable temperature is limited by the presence of magnetic interactions that bring about magnetic order below a critical temperature. We demonstrate that this limitation can be overcome by chemically engineering the molecules in such a way to effectively screen all magnetic interactions, suggesting their use as ultra-low-temperature coolers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Caustic Precipitation of Plutonium Using Gadolinium as the Neutron Poison for Disposition to High Level Waste

    SciTech Connect

    Bronikowski, M.G.

    2002-06-24

    Nuclear Materials Management Division (NMMD) has proposed that up to 100 kg of the plutonium (Pu) solutions stored in H-Canyon be precipitated with a nuclear poison and dispositioned to H-Area Tank Farm. The use of gadolinium (Gd) as the poison would greatly reduce the number of additional glass logs resulting from this disposition. This report summarizes the characteristics of the precipitation process and addresses criticality concerns in the Nuclear Criticality Safety Evaluation. No problems were found with the nature of the precipitate or the neutralization process.

  20. Gadolinium-Enhanced Angiography for Diagnosis and Interventional Treatment of Subclavian Artery Stenosis Prior to Fistula Creation

    SciTech Connect

    Termote, Bruno; Maleux, Geert Heye, Sam; Fourneau, Inge; Claes, Kathleen

    2008-07-15

    We report the use of gadolinium-based contrast agent for both diagnostic and interventional subclavian angiography in two azotemic patients, presenting with an asymptomatic, high-grade stenosis of the left subclavian artery, ipsilateral to the site of choice for native fistula creation. Angiographic imaging performed with diluted gadolinium-based contrast material was clear enough to perform successful subclavian artery stenting, resulting in normalization of the arterial blood pressure in the afferent artery of the dialysis fistula. Clinically, no decrease in residual renal function and no other complication were noted immediately or a longer period after the interventional treatment.

  1. Microstructural Anisotropy of Magnetocaloric Gadolinium Cylinders: Effect on the Mechanical Properties of the Material.

    PubMed

    Petrovič, Darja Steiner; Šturm, Roman; Naglič, Iztok; Markoli, Boštjan; Pepelnjak, Tomaž

    2016-05-17

    The development of advanced materials and technologies based on magnetocaloric Gd and its compounds requires an understanding of the dependency of mechanical properties on their underlying microstructure. Therefore, the aim of the study was to characterize microstructural inhomogeneities in the gadolinium that can be used in magnetocaloric refrigeration systems. Microstructures of magnetocaloric gadolinium cylinders were investigated by light microscopy and FE-SEM (Field Emission Scanning Electron Microscopy), EDS (Energy-dispersive X-ray Spectroscopy), and BSE (Back-scattered Electrons) in both the extrusion and the extrusion-transversal directions. XRD (X-ray Diffraction) analyses were performed to reveal the presence of calcium- and fluorine-based compounds. Metallographic characterization showed an oxidized and inhomogeneous microstructure of the cross-sections. The edges and the outer parts of the cylinders were oxidized more intensively on the surfaces directly exposed to the processing tools. Moreover, a significant morphological anisotropy of the non-metallic inclusions was observed. CaF inclusions act as active nucleation sites for internal oxidation. The non-metallic, Ca- and F-containing inclusions can be classified as complex calciumoxyfluorides. The solubility of Er and Yb in the CaF was negligible compared to the Gd matrix and/or the oxide phase. Lower mechanical properties of the material are a consequence of the lower structural integrity due to selective oxidation of surfaces and interfaces.

  2. Microstructural Anisotropy of Magnetocaloric Gadolinium Cylinders: Effect on the Mechanical Properties of the Material

    PubMed Central

    Petrovič, Darja Steiner; Šturm, Roman; Naglič, Iztok; Markoli, Boštjan; Pepelnjak, Tomaž

    2016-01-01

    The development of advanced materials and technologies based on magnetocaloric Gd and its compounds requires an understanding of the dependency of mechanical properties on their underlying microstructure. Therefore, the aim of the study was to characterize microstructural inhomogeneities in the gadolinium that can be used in magnetocaloric refrigeration systems. Microstructures of magnetocaloric gadolinium cylinders were investigated by light microscopy and FE-SEM (Field Emission Scanning Electron Microscopy), EDS (Energy-dispersive X-ray Spectroscopy), and BSE (Back-scattered Electrons) in both the extrusion and the extrusion-transversal directions. XRD (X-ray Diffraction) analyses were performed to reveal the presence of calcium- and fluorine-based compounds. Metallographic characterization showed an oxidized and inhomogeneous microstructure of the cross-sections. The edges and the outer parts of the cylinders were oxidized more intensively on the surfaces directly exposed to the processing tools. Moreover, a significant morphological anisotropy of the non-metallic inclusions was observed. CaF inclusions act as active nucleation sites for internal oxidation. The non-metallic, Ca- and F-containing inclusions can be classified as complex calciumoxyfluorides. The solubility of Er and Yb in the CaF was negligible compared to the Gd matrix and/or the oxide phase. Lower mechanical properties of the material are a consequence of the lower structural integrity due to selective oxidation of surfaces and interfaces. PMID:28773502

  3. Microemulsion-made gadolinium carbonate hollow nanospheres showing magnetothermal heating and drug release.

    PubMed

    Jung-König, J; Sanhaji, M; Popescu, R; Seidl, C; Zittel, E; Schepers, U; Gerthsen, D; Hilger, I; Feldmann, C

    2017-06-22

    Gadolinium carbonate (Gd2(CO3)3) hollow nanospheres and their suitability for drug transport and magnetothermally-induced drug release are presented. The hollow nanospheres are prepared via a microemulsion-based synthesis using tris(tetramethylcyclopentadienyl)gadolinium(iii) and CO2 as the starting materials. Size, structure and composition of the as-prepared Gd2(CO3)3 hollow nanospheres are comprehensively validated by several independent analytical methods (HRTEM, HAADF-STEM, DLS, EDXS, XRD, FT-IR, DTA-TG). Accordingly, they exhibit an outer diameter of 26 ± 4 nm, an inner cavity of 7 ± 2 nm, and a wall thickness of 9 ± 3 nm. As a conceptual study, the nanocontainer-functionality of the Gd2(CO3)3 hollow nanospheres is validated upon filling with the anti-cancerogenic agent doxorubicin (DOX), which is straightforward via the microemulsion (ME) strategy. The resulting DOX@Gd2(CO3)3 nanocontainers provide the option of multimodal imaging including optical and magnetic resonance imaging (OI, MRI) as well as magnetothermal heating and drug release. As a proof-of-concept, we could already prove the intrinsic DOX-based fluorescence, a low systemic toxicity according to in vitro studies as well as the magnetothermal effect and a magnetothermally-induced DOX release. In particular, the latter is new for Gd-containing nanoparticles and highly promising in view of theranostic nanocontainers and synergistic physical and chemical tumor treatment.

  4. Structural and chemical analysis of gadolinium halides encapsulated within WS2 nanotubes.

    PubMed

    Anumol, E A; Enyashin, Andrey N; Batra, Nitin M; Costa, Pedro M F J; Deepak, Francis Leonard

    2016-06-16

    The hollow cavities of nanotubes serve as templates for the growth of size- and shape-confined functional nanostructures, giving rise to novel materials and properties. In this work, considering their potential application as MRI contrast agents, gadolinium halides are encapsulated within the hollow cavities of WS2 nanotubes by capillary filling to obtain GdX3@WS2 nanotubes (where X = Cl, Br or I and @ means encapsulated in). Aberration corrected scanning/transmission electron microscopy (S/TEM) and spectroscopy is employed to understand the morphology and composition of the GdI3@WS2 nanotubes. The three dimensional morphology is studied with STEM tomography but understanding the compositional information is non-trivial due to the presence of multiple high atomic number elements. Therefore, energy dispersive X-ray spectroscopy (EDS) tomography was employed revealing the three dimensional chemical composition. Molecular dynamics simulations of the filling procedure shed light into the mechanics behind the formation of the confined gadolinium halide crystals. The quasi-1D system employed here serves as an example of a TEM-based chemical nanotomography method that could be extended to other materials, including beam-sensitive soft materials.

  5. Modulation of channel activity and gadolinium block of MscL by static magnetic fields.

    PubMed

    Petrov, Evgeny; Martinac, Boris

    2007-02-01

    The magnetic field of the Earth has for long been known to influence the behaviour and orientation of a variety of living organisms. Experimental studies of the magnetic sense have, however, been impaired by the lack of a plausible cellular and/or molecular mechanism providing meaningful explanation for detection of magnetic fields by these organisms. Recently, mechanosensitive (MS) ion channels have been implied to play a role in magnetoreception. In this study we have investigated the effect of static magnetic fields (SMFs) of moderate intensity on the activity and gadolinium block of MscL, the bacterial MS channel of large conductance, which has served as a model channel to study the basic physical principles of mechanosensory transduction in living cells. In addition to showing that direct application of the magnetic field decreased the activity of the MscL channel, our study demonstrates for the first time that SMFs can reverse the effect of gadolinium, a well-known blocker of MS channels. The results of our study are consistent with a notion that (1) the effects of SMFs on the MscL channels may result from changes in physical properties of the lipid bilayer due to diamagnetic anisotropy of phospholipid molecules and consequently (2) cooperative superdiamagnetism of phospholipid molecules under influence of SMFs could cause displacement of Gd(3+) ions from the membrane bilayer and thus remove the MscL channel block.

  6. Effects of Polyethyleneimine on the Sonochemical Synthesis of Gadolinium Ion-Modified ZnO Nanorods.

    PubMed

    Choi, Seok Cheol; Yun, Won Suk; Sohn, Sang Ho

    2015-01-01

    We prepared gadolinium (Gd) ion-modified ZnO nanorods by a sonochemical decomposition of zinc acetate dehydrate and gadolinium acetate hydrate precursor solutions with and without polyethyleneimine (PEI). We investigated the effects of PEI on the sonochemical synthesis of ZnO nanorods with and without Gd ion modifications. In the case of nascent ZnO nanorods, PEI in the precursor solutions can prohibit radial growth but allow axial growth, resulting in changes in the degree of preferred crystal orientations, and in the PL properties of the resulting nanorods. In the case of Gd ion-modified ZnO nanorods, we observed that the ZnO nanorods, fabricated sonochemically in the precursor solutions with PEI, exhibited a peak broadening of the ZnO(002) crystal plane and decreasing crystal orientation with respect to the c plane. We note that PEI can negatively affect the crystal orientation and crystallinity of Gd ion-modified ZnO nanorods, even though it cannot affect the lattice constant.

  7. Bioconjugation of luminescent silicon quantum dots to gadolinium ions for bioimaging applications.

    PubMed

    Erogbogbo, Folarin; Chang, Ching-Wen; May, Jasmine L; Liu, Liwei; Kumar, Rajiv; Law, Wing-Cheung; Ding, Hong; Yong, Ken Tye; Roy, Indrajit; Sheshadri, Mukund; Swihart, Mark T; Prasad, Paras N

    2012-09-07

    Luminescent imaging agents and MRI contrast agents are desirable components in the rational design of multifunctional nanoconstructs for biological imaging applications. Luminescent biocompatible silicon quantum dots (SiQDs) and gadolinium chelates can be applied for fluorescence microscopy and MRI, respectively. Here, we report the first synthesis of a nanocomplex incorporating SiQDs and gadolinium ions (Gd³⁺) for biological applications. The nanoconstruct is composed of a PEGylated micelle, with hydrophobic SiQDs in its core, covalently bound to DOTA-chelated Gd³⁺. Dynamic light scattering reveals a radius of 85 nm for these nanoconstructs, which is consistent with the electron microscopy results depicting radii ranging from 25 to 60 nm. Cellular uptake of the probes verified that they maintain their optical properties within the intracellular environment. The magnetic resonance relaxivity of the nanoconstruct was 2.4 mM⁻¹ s⁻¹ (in terms of Gd³⁺ concentration), calculated to be around 6000 mM⁻¹ s⁻¹ per nanoconstruct. These desirable optical and relaxivity properties of the newly developed probe open the door for use of SiQDs in future multimodal applications such as tumour imaging.

  8. Geometrically confined ultrasmall gadolinium oxide nanoparticles boost the T(1) contrast ability.

    PubMed

    Ni, Kaiyuan; Zhao, Zhenghuan; Zhang, Zongjun; Zhou, Zijian; Yang, Li; Wang, Lirong; Ai, Hua; Gao, Jinhao

    2016-02-14

    High-performance magnetic resonance imaging (MRI) contrast agents and novel contrast enhancement strategies are urgently needed for sensitive and accurate diagnosis. Here we report a strategy to construct a new T1 contrast agent based on the Solomon-Bloembergen-Morgan (SBM) theory. We loaded the ultrasmall gadolinium oxide nanoparticles into worm-like interior channels of mesoporous silica nanospheres (Gd2O3@MSN nanocomposites). This unique structure endows the nanocomposites with geometrical confinement, high molecular tumbling time, and a large coordinated number of water molecules, which results in a significant enhancement of the T1 contrast with longitudinal proton relaxivity (r1) as high as 45.08 mM(-1) s(-1). Such a high r1 value of Gd2O3@MSN, compared to those of ultrasmall Gd2O3 nanoparticles and gadolinium-based clinical contrast agents, is mainly attributed to the strong geometrical confinement effect. This strategy provides new guidance for developing various high-performance T1 contrast agents for sensitive imaging and disease diagnosis.

  9. Microcalorimetric studies on the energy release of isolated rat mitochondria under different concentrations of gadolinium (III).

    PubMed

    Zhao, Jie; Ma, Long; Xiang, Xun; Guo, Qing-Lian; Jiang, Feng-Lei; Liu, Yi

    2016-06-01

    Gadolinium-based compounds are most widely utilized for paramagnetic contrast agents, but, the toxicological mechanism of gadolinium (Gd) had not been fully elucidated since the first report about Gd anomaly. In this work, we analyzed the effect of Gd(3+) on mitochondria in vitro by microcalorimetry. Microcalorimetry can provide detailed kinetic and thermodynamic information from thermogenic curve. At the tested concentration, Gd(3+) induced the increase of growth rate constant (k1). At high concentration (100-500 μM), the maximum power output time (tm), the decline rate constant (-k2) and the time of activity recovery phase (tR) decreased with the addition of Gd(3+) and the maximum power output (Pm) increased. At low concentration (0-100 μM), the changes were different from high concentration. From the results we concluded that the effect of different concentrations of Gd(3+) had a relationship with time, high concentration of Gd(3+) induced mitochondrial energy metabolism disturb however low concentration may promote mitochondrial adaption to physiological stresses. The effect of low concentration of Gd(3+) need more work to elucidate the mechanism. The results of total heat output (Q) and mitochondrial respiratory activities suggested high concentrations of Gd(3+) could accelerate adenosine triphosphate (ATP) consumption under respiratory system damaged.

  10. Density functional calculations for structural, electronic, and magnetic properties of gadolinium-oxide clusters

    SciTech Connect

    Yuan, H. K.; Chen, H. Tian, C. L.; Kuang, A. L.; Wang, J. Z.

    2014-04-21

    Gadolinium-oxide clusters in various sizes and stoichiometries have been systematically studied by employing the density functional theory with the generalized gradient approximation. The clusters in bulk stoichiometry are relatively more stable and their binding energies increase with the increasing size. Stoichiometric (Gd{sub 2}O{sub 3}){sub n} clusters of n = 1–3 prefer cage-like structures, whereas the clusters of n = 4–30 prefer compact structures layered by wedge-like units and exhibit a rough feature toward the bulk-like arrangement with small disorders of atomic positions. The polyhedral-cages analogous to carbon-fullerenes are stable isomers yet not the minimum energy configurations. Their stabilities can be improved by embedding one oxygen atom or a suitable cage to form core-shell configurations. The mostly favored antiferromagnetic couplings between adjacent Gd atoms are nearly degenerated in energy with their ferromagnetic couplings, resulting in super-paramagnetic characters of gadolinium-oxide clusters. The Ruderman-Kittel-Kasuya-Yosida (RKKY)-type mechanism together with the superexchange-type mechanism plays cooperation role for the magnetic interactions in clusters. We present, as a function of n, calculated binding energies, ionization potential, electron affinity, and electronic dipole moment.

  11. Effect of solid-phase amorphization on the spectral characteristics of europium-doped gadolinium molybdate

    NASA Astrophysics Data System (ADS)

    Shmurak, S. Z.; Kiselev, A. P.; Kurmasheva, D. M.; Red'Kin, B. S.; Sinitsyn, V. V.

    2010-05-01

    A method is proposed for detecting spectral characteristics of optically inactive molybdates of rare-earth elements by their doping with rare-earth ions whose luminescence lies in the transparency region of all structural modifications of the sample. Gadolinium molybdate is chosen as the object of investigations, while europium ions are used as an optically active and structurally sensitive admixture. It is shown that after the action of a high pressure under which gadolinium molybdate passes to the amorphous state, the spectral characteristics of Gd1.99Eu0.01(MoO4)3 (GMO:Eu) change radically; namely, considerable line broadening is observed in the luminescence spectra and the luminescence excitation spectra, while the long-wave threshold of optical absorption is shifted considerably (by approximately 1.1 eV) towards lower energies. It is found that by changing the structural state of GMO:Eu by solid-state amorphization followed by annealing, the spectral characteristics of the sample can be purposefully changed. This is extremely important for solving the urgent problem of designing high-efficiency light-emitting diodes producing “white” light.

  12. Development of a gadolinium-loaded liquid scintillator for the Hanaro short baseline prototype detector

    NASA Astrophysics Data System (ADS)

    Yeo, In Sung; Joo, Kyung Kwang; So, Sun Heang; Song, Sook Hyung; Kim, Hong Joo; So, Jung Ho; Park, Kang Soon; Ma, Kyung Ju; Jeon, Eun Ju; Kim, Jin Yu; Kim, Young Duk; Lee, Jason; Lee, Jeong-Yeon; Sun, Gwang-Min

    2014-02-01

    We propose a new experiment on the site of the Korea Atomic Energy Research Institute (KAERI) located at Daejeon, Korea. The Hanaro short baseline (SBL) nuclear reactor with a thermal power output 30 MW is used to investigate a reactor neutrino anomaly. A Hanaro SBL prototype detector having a 60- l volume has been constructed ˜6 m away from the reactor core. A gadolinium (Gd)-loaded liquid scintillator (LS) is used as an active material to trigger events. The selection of the LS is guided by physical and technical requirements, as well as safety considerations. A linear alkyl benzene (LAB) is used as a base solvent of the Hanaro SBL prototype detector. Three g/ l of PPO and 30 mg/ l of bis-MSB are dissolved to formulate the LAB-based LS. Then, a 0.5% gadolinium (Gd) complex with carboxylic acid is loaded into the LAB-based LS by using the liquidliquid extraction method. In this paper, we will summarize all the characteristics of the Gd-loaded LAB-based LS for the Hanaro prototype detector.

  13. Energy-Discriminating Gadolinium K-Edge X-ray Computed Tomography System

    NASA Astrophysics Data System (ADS)

    Matsukiyo, Hiroshi; Watanabe, Manabu; Sato, Eiichi; Osawa, Akihiro; Enomoto, Toshiyuki; Nagao, Jiro; Abderyim, Purkhet; AIzawa, Katsuo; Hitomi, Keitaro; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ogawa, Akira; Takahashi, Kiyomi; Sato, Shigehiro; Onagawa, Jun

    2010-02-01

    An energy-discriminating K-edge X-ray computed tomography (CT) system is useful for increasing the contrast resolution of a target region utilizing contrast media and for reducing the absorbed dose for patients. The CT system is of the first-generation type of detector using cadmium telluride (CdTe). CT is performed by repeated translations and rotations of an object. Penetrating X-ray photons from the object are detected by a CdTe detector, and event signals of X-ray photons are produced using charge-sensitive and shaping amplifiers. Both photon energy and energy width are selected out using a multichannel analyzer, and the number of photons is counted by a countercard. To perform energy discrimination, a low-dose-rate X-ray generator for photon counting was developed. Its maximum tube voltage and minimum tube current were 110 kV and 1 µA, respectively. In energy-discriminating CT, the tube voltage and tube current were 100 kV and 20 µA, respectively, and the X-ray intensity was 2.98 µGy/s at a distance of 1.0 m from the source and a tube voltage of 100 kV. The demonstration of enhanced gadolinium K-edge X-ray CT was carried out by selecting photons with energies just beyond the gadolinium K-edge energy of 50.3 keV.

  14. Energy-Discriminating Gadolinium K-Edge X-ray Computed Tomography System

    NASA Astrophysics Data System (ADS)

    Hiroshi Matsukiyo,; Manabu Watanabe,; Eiichi Sato,; Akihiro Osawa,; Toshiyuki Enomoto,; Jiro Nagao,; Purkhet Abderyim,; Katsuo AIzawa,; Keitaro Hitomi,; Etsuro Tanaka,; Hidezo Mori,; Toshiaki Kawai,; Akira Ogawa,; Kiyomi Takahashi,; Shigehiro Sato,; Jun Onagawa,

    2010-02-01

    An energy-discriminating K-edge X-ray computed tomography (CT) system is useful for increasing the contrast resolution of a target region utilizing contrast media and for reducing the absorbed dose for patients. The CT system is of the first-generation type of detector using cadmium telluride (CdTe). CT is performed by repeated translations and rotations of an object. Penetrating X-ray photons from the object are detected by a CdTe detector, and event signals of X-ray photons are produced using charge-sensitive and shaping amplifiers. Both photon energy and energy width are selected out using a multichannel analyzer, and the number of photons is counted by a countercard. To perform energy discrimination, a low-dose-rate X-ray generator for photon counting was developed. Its maximum tube voltage and minimum tube current were 110 kV and 1 μA, respectively. In energy-discriminating CT, the tube voltage and tube current were 100 kV and 20 μA, respectively, and the X-ray intensity was 2.98 μGy/s at a distance of 1.0 m from the source and a tube voltage of 100 kV. The demonstration of enhanced gadolinium K-edge X-ray CT was carried out by selecting photons with energies just beyond the gadolinium K-edge energy of 50.3 keV.

  15. Gadolinium-Based Contrast Agents for Vessel Wall Magnetic Resonance Imaging (MRI) of Atherosclerosis

    PubMed Central

    Calcagno, Claudia; Ramachandran, Sarayu; Millon, Antoine; Robson, Philip M.; Mani, Venkatesh

    2012-01-01

    Cardiovascular disease due to atherosclerosis is the number one killer in the Western world, and threatens to become the major cause of morbidity and mortality worldwide. It is therefore paramount to develop non-invasive methods for the detection of high-risk, asymptomatic individuals before the onset of clinical symptoms or events. In the recent past, great strides have been made in the understanding of the pathological mechanisms involved in the atherosclerotic cascade down to the molecular details. This has allowed the development of contrast agents that can aid in the in vivo characterization of these processes. Gadolinium chelates are among the contrast media most commonly used in MR imaging. Originally used for MR angiography for the detection and quantification of vascular stenosis, more recently they have been applied to improve characterization of atherosclerotic plaques. In this manuscript, we will briefly review gadolinium-chelates (Gd) based contrast agents for non-invasive MR imaging of atherosclerosis. We will first describe Gd-based non-targeted FDA approved agents, used routinely in clinical practice for the evaluation of neovascularization in other diseases. Secondly, we will describe non-specific and specific targeted contrast agents, which have great potential for dissecting specific biological processes in the atherosclerotic cascade. Lastly, we will briefly compare Gd-based agents to others commonly used in MRI and to other imaging modalities. PMID:23539505

  16. Gadolinium-Based Contrast Agents for Vessel Wall Magnetic Resonance Imaging (MRI) of Atherosclerosis.

    PubMed

    Calcagno, Claudia; Ramachandran, Sarayu; Millon, Antoine; Robson, Philip M; Mani, Venkatesh; Fayad, Zahi

    2013-02-01

    Cardiovascular disease due to atherosclerosis is the number one killer in the Western world, and threatens to become the major cause of morbidity and mortality worldwide. It is therefore paramount to develop non-invasive methods for the detection of high-risk, asymptomatic individuals before the onset of clinical symptoms or events. In the recent past, great strides have been made in the understanding of the pathological mechanisms involved in the atherosclerotic cascade down to the molecular details. This has allowed the development of contrast agents that can aid in the in vivo characterization of these processes. Gadolinium chelates are among the contrast media most commonly used in MR imaging. Originally used for MR angiography for the detection and quantification of vascular stenosis, more recently they have been applied to improve characterization of atherosclerotic plaques. In this manuscript, we will briefly review gadolinium-chelates (Gd) based contrast agents for non-invasive MR imaging of atherosclerosis. We will first describe Gd-based non-targeted FDA approved agents, used routinely in clinical practice for the evaluation of neovascularization in other diseases. Secondly, we will describe non-specific and specific targeted contrast agents, which have great potential for dissecting specific biological processes in the atherosclerotic cascade. Lastly, we will briefly compare Gd-based agents to others commonly used in MRI and to other imaging modalities.

  17. Chemical and magnetic structure of uranium/gadolinium multilayers studied by transmission

    SciTech Connect

    Wilkins, S.B.; Springell, R.; Langridge, S.; Wildes, A.; Sanchez-Hanke, C.; Moore, K.T.; Butterfield, M.; Chivall, J.; Ward, R.C.C.; Wells, M.R.; Lander, G.H.

    2010-04-29

    We present a multitechnique approach to study the detailed chemical and magnetic structure of uranium/gadolinium multilayers. At low temperature the saturation magnetization is found to be {approx}60% of that of bulk gadolinium. We address this problem, which is found in many other multilayers and suggest a model that may have wider applications. Transmission electron microscopy images indicate a microstructure, consistent with a columnar growth of Gd with crystallites of the order 20 {yields} 100{angstrom}. Off-specular neutron scattering is most strongly visible at saturation field, indicating that Gd moments are not aligned with the applied field. X-ray resonant magnetic scattering provides proof of coupled in-plane length scales for both the structural and the magnetic roughness. A detailed x-ray scattering study of both the specular and off-specular reflectivities has been used to investigate the in-plane structure of the multilayers. We calculate the roughness and transverse correlation cut-off length, {zeta}{sub x} = 120 {+-} 30{angstrom}, and present a simple model to determine an average column size of 27 {+-} 6{angstrom} and a reduction in the magnetic saturation of {approx}40%.

  18. Order-disorder transitions in gadolinium zirconate: A potential electrolyte material in solid oxide fuel cells

    SciTech Connect

    Meilicke, S.; Haile, S.

    1995-12-31

    Rare-earth, yttrium, and calcium doped zirconates are the materials of choice for electrolytes in solid oxide fuel cells. The dopant in these materials serves not only to stabilized the cubic phase of zirconia, but also to introduce anion defects that presumably increase the ionic conductivity. In order to understand the relationships between anion defect distribution, thermal history and ionic conductivity, the structural properties of gadolinium zirconate, Gd{sub 2}Zr{sub 2}O{sub 7}, have been examined via high-temperature x-ray powder diffraction. Gadolinium zirconate is an ideal material for such a structure-property-processing study: it shows ordering of defects at low temperatures, taking on a pyrochlore structure, and disordering at elevated temperature, taking on a defect fluorite structure. Diffraction experiments, performed as functions of time and temperature, confirmed the transition temperature to lie between 1,500 and 1,550 C. They also revealed that the transformation takes place most rapidly just below the transition temperature, indicating that the ordering process is kinetically constrained at low temperatures. Moreover, x-ray data collected at room temperature from quenched samples were found to be as useful, if not more so, than those collected in situ at high temperature. The latter are affected by thermal scattering, severely compromising data quality.

  19. Evaluation of gadolinium compounds potentially suitable for magnetic resonance using Gd-153 scintigraphy

    SciTech Connect

    Engelstad, B.; Huberty, J.; White, D.; Wynne, C.; Ramos, E.; Goldberg, H.

    1985-05-01

    Gd-153 is not customarily considered for scintigraphy, yet it: 1) is available at acceptable cost, 2) has a 242 day half-life suitable for prolonged animal studies and 3) has 97 keV (40%) and 103 keV (59%) photopeaks suitable for conventional scintigraphy. Gd-153 (10-15 ..mu..Ci; 370-555 kBq) was administered to normal rats in 5 forms: 1) carrier 0.1 mmole/kg Gd-EIDA (diethyl iminodiacetic acid), 2) tracer (<.1 umole/kg) Gd-EIDA, 3) tracer Gd-ISIDA (diisopropyl iminodiacetic acid), 4) tracer GdCl/sub 3/, and 5) tracer Gd-DTPA. Scintigraphy, performed continuously for 90 minutes following intravenous injection and at intervals at up to 2 weeks, depicted: 1) rapid, partial hepatobiliary and renal clearance of tracer Gd-EIDA and Gd-ISIDA; 2) slow blood clearance and partial hepatobiliary clearance of carrier Gd-EIDA; and 3) prolonged reticuloendothelial retention of all IDA complexes, similar to GdCl3. Whole body and tissue distribution data paralleled the scintigraphic findings. Gd-153 scintigraphy provides a simple method to assess balance, distribution, kinetics, and stability of new paramagnetic contrast agents, and bis-iminodiacetate gadolinium complexes, unlike technetium analogues, lack effective stability to prevent gadolinium hydrolysis or translocation.

  20. Geometrical confinement of gadolinium-based contrast agents in nanoporous particles enhances T1 contrast

    PubMed Central

    Ananta, Jeyarama S.; Godin, Biana; Sethi, Richa; Moriggi, Loick; Liu, Xuewu; Serda, Rita E.; Krishnamurthy, Ramkumar; Muthupillai, Raja; Bolskar, Robert D.; Helm, Lothar; Ferrari, Mauro; Wilson, Lon J.; Decuzzi, Paolo

    2010-01-01

    Magnetic resonance imaging contrast agents are currently designed by modifying their structural and physiochemical properties in order to improve relaxivity and to enhance image contrast. Here we show a general method for increasing relaxivity by confining contrast agents inside the nanoporous structure of silicon particles. Magnevist, gadofullerenes and gadonanotubes were loaded inside the pores of quasi-hemispherical and discoidal particles. For all combinations of nanoconstructs, a boost in longitudinal proton relaxivity r1 was observed: for Magnevist, r1~14 mM-1s-1/Gd3+ion (~8.15×10+7 mM-1s-1/construct); for gadofullerenes, r1~200 mM-1s-1/Gd3+ion (~7×10+9 mM-1s-1/construct); for gadonanotubes, r1~150 mM-1s-1/Gd3+ion (~2×10+9 mM-1s-1/construct). These relaxivity values are about 4 to 50 times larger than that of clinically-available gadolinium-based agents (~4 mM-1s-1 /Gd3+ion). The enhancement in contrast is attributed to the geometrical confinement of the agents, which influences the paramagnetic behavior of the Gd3+ions. Thus, nanoscale confinement offers a new and general strategy for enhancing the contrast of gadolinium-based contrast agents. PMID:20972435

  1. Disparate ultrafast dynamics of itinerant and localized magnetic moments in gadolinium metal

    PubMed Central

    Frietsch, B.; Bowlan, J.; Carley, R.; Teichmann, M.; Wienholdt, S.; Hinzke, D.; Nowak, U.; Carva, K.; Oppeneer, P. M.; Weinelt, M.

    2015-01-01

    The Heisenberg–Dirac intra-atomic exchange coupling is responsible for the formation of the atomic spin moment and thus the strongest interaction in magnetism. Therefore, it is generally assumed that intra-atomic exchange leads to a quasi-instantaneous aligning process in the magnetic moment dynamics of spins in separate, on-site atomic orbitals. Following ultrashort optical excitation of gadolinium metal, we concurrently record in photoemission the 4f magnetic linear dichroism and 5d exchange splitting. Their dynamics differ by one order of magnitude, with decay constants of 14 versus 0.8 ps, respectively. Spin dynamics simulations based on an orbital-resolved Heisenberg Hamiltonian combined with first-principles calculations explain the particular dynamics of 5d and 4f spin moments well, and corroborate that the 5d exchange splitting traces closely the 5d spin-moment dynamics. Thus gadolinium shows disparate dynamics of the localized 4f and the itinerant 5d spin moments, demonstrating a breakdown of their intra-atomic exchange alignment on a picosecond timescale. PMID:26355196

  2. Thermal neutron capture cross section of gadolinium by pile-oscillation measurements in MINERVE

    SciTech Connect

    Leconte, P.; Di-Salvo, J.; Antony, M.; Pepino, A.; Hentati, A.

    2012-07-01

    Natural gadolinium is used as a burnable poison in most LWR to account for the excess of reactivity of fresh fuels. For an accurate prediction of the cycle length, its nuclear data and especially its neutron capture cross section needs to be known with a high precision. Recent microscopic measurements at Rensselaer Polytechnic Inst. (RPI) suggest a 11% smaller value for the thermal capture cross section of {sup 157}Gd, compared with most of evaluated nuclear data libraries. To solve this inconsistency, we have analyzed several pile-oscillation experiments, performed in the MINERVE reactor. They consist in the measurement of the reactivity variation involved by the introduction in the reactor of small-samples, containing different mass amounts of natural gadolinium. The analysis of these experiments is done through the exact perturbation theory, using the PIMS calculation tool, in order to link the reactivity effect to the thermal capture cross section. The measurement of reactivity effects is used to deduce the 2200 m.s-1 capture cross section of {sup nat}Gd which is (49360 {+-} 790) b. This result is in good agreement with the JEFF3.1.1 value (48630 b), within 1.6% uncertainty at 1{sigma}, but is strongly inconsistent with the microscopic measurements at RPI which give (44200 {+-} 500) b. (authors)

  3. [Important of magnetic resonance angiography with gadolinium injection in pulmonary vein diseases].

    PubMed

    Godart, F; Cocheteux, B; Willoteaux, S; Francart, Ch; Brevière, G M; Jaillard, S; Beregi, J P; Rey, Ch

    2002-05-01

    The study of the pulmonary veins by echocardiography is sometimes difficult especially when the ultrasonic window is restricted. Conventional angiography is the classic reference examination but it exposes the patient to ionising radiation and requires the injection of an iodine contrast product. Another technique that can provide the essential information is magnetic resonance angiography (MRA) with injection of gadolinium. It was performed in 9 patients for suspected congenital or acquired anomalies of the pulmonary veins between June 1999 and December 2001. The patient's ages varied from 1 month to 10 years. The examinations were carried out on a 1.5 T Vision machine (Siemens, Erlangen, Germany) without "cardiac gating" or apnoea after parental consent. MRA with gadolinium injection showed 5 drainage anomalies (3 partial pulmonary venous refluxes in the superior vena cava, 2 scimitar syndromes) and 3 stenoses (one due to compression by an aneurysm of the left pulmonary artery, a second secondary to pericardial agenesis, and a third secondary to hypoplasia of an isolated vein). MRA allowed three dimensional visualisation of these anomalies. This is a rapid, non-invasive and certain imaging technique which does not expose the patient to ionising radiation. It is therefore of significance in the investigation of anomalies of the pulmonary veins complementing echocardiography, and could in future replace cardiac catheterisation.

  4. Nanodiamond-Gadolinium(III) Aggregates for Tracking Cancer Growth In Vivo at High Field.

    PubMed

    Rammohan, Nikhil; MacRenaris, Keith W; Moore, Laura K; Parigi, Giacomo; Mastarone, Daniel J; Manus, Lisa M; Lilley, Laura M; Preslar, Adam T; Waters, Emily A; Filicko, Abigail; Luchinat, Claudio; Ho, Dean; Meade, Thomas J

    2016-12-14

    The ability to track labeled cancer cells in vivo would allow researchers to study their distribution, growth, and metastatic potential within the intact organism. Magnetic resonance (MR) imaging is invaluable for tracking cancer cells in vivo as it benefits from high spatial resolution and the absence of ionizing radiation. However, many MR contrast agents (CAs) required to label cells either do not significantly accumulate in cells or are not biologically compatible for translational studies. We have developed carbon-based nanodiamond-gadolinium(III) aggregates (NDG) for MR imaging that demonstrated remarkable properties for cell tracking in vivo. First, NDG had high relaxivity independent of field strength, a finding unprecedented for gadolinium(III) [Gd(III)]-nanoparticle conjugates. Second, NDG demonstrated a 300-fold increase in the cellular delivery of Gd(III) compared to that of clinical Gd(III) chelates without sacrificing biocompatibility. Further, we were able to monitor the tumor growth of NDG-labeled flank tumors by T1- and T2-weighted MR imaging for 26 days in vivo, longer than was reported for other MR CAs or nuclear agents. Finally, by utilizing quantitative maps of relaxation times, we were able to describe tumor morphology and heterogeneity (corroborated by histological analysis), which would not be possible with competing molecular imaging modalities.

  5. High Relaxivity Gadolinium Hydroxypyridonate-Viral Capsid Conjugates: Nano-sized MRI Contrast Agents

    SciTech Connect

    Meux, Susan C.; Datta, Ankona; Hooker, Jacob M.; Botta, Mauro; Francis, Matthew B.; Aime, Silvio; Raymond, Kenneth N.

    2007-08-29

    High relaxivity macromolecular contrast agents based on the conjugation of gadolinium chelates to the interior and exterior surfaces of MS2 viral capsids are assessed. The proton nuclear magnetic relaxation dispersion (NMRD) profiles of the conjugates show up to a five-fold increase in relaxivity, leading to a peak relaxivity (per Gd{sup 3+} ion) of 41.6 mM{sup -1}s{sup -1} at 30 MHz for the internally modified capsids. Modification of the exterior was achieved through conjugation to flexible lysines, while internal modification was accomplished by conjugation to relatively rigid tyrosines. Higher relaxivities were obtained for the internally modified capsids, showing that (1) there is facile diffusion of water to the interior of capsids and (2) the rigidity of the linker attaching the complex to the macromolecule is important for obtaining high relaxivity enhancements. The viral capsid conjugated gadolinium hydroxypyridonate complexes appear to possess two inner-sphere water molecules (q = 2) and the NMRD fittings highlight the differences in the local motion for the internal ({tau}{sub RI} = 440 ps) and external ({tau}{sub RI} = 310 ps) conjugates. These results indicate that there are significant advantages of using the internal surface of the capsids for contrast agent attachment, leaving the exterior surface available for the installation of tissue targeting groups.

  6. Pediatric Patients Demonstrate Progressive T1-Weighted Hyperintensity in the Dentate Nucleus following Multiple Doses of Gadolinium-Based Contrast Agent.

    PubMed

    Roberts, D R; Chatterjee, A R; Yazdani, M; Marebwa, B; Brown, T; Collins, H; Bolles, G; Jenrette, J M; Nietert, P J; Zhu, X

    2016-12-01

    While there have been recent reports of brain retention of gadolinium following gadolinium-based contrast agent administration in adults, a retrospective series of pediatric patients has not previously been reported, to our knowledge. We investigated the relationship between the number of prior gadolinium-based contrast agent doses and increasing T1 signal in the dentate nucleus on unenhanced T1-weighted MR imaging. We hypothesized that despite differences in pediatric physiology and the smaller gadolinium-based contrast agent doses that pediatric patients are typically administered based on weighted-adjusted dosing, the pediatric brain would also demonstrate dose-dependent increasing T1 signal in the dentate nucleus. We included children with multiple gadolinium-based contrast agent administrations at our institution. A blinded reader placed ROIs within the dentate nucleus and adjacent cerebellar white matter. To eliminate reader bias, we also performed automated ROI delineation of the dentate nucleus, cerebellar white matter, and pons. Dentate-to-cerebellar white matter and dentate-to pons ratios were compared with the number of gadolinium-based contrast agent administrations. During 20 years at our institution, 280 patients received at least 5 gadolinium-based contrast agent doses, with 1 patient receiving 38 doses. Sixteen patients met the inclusion/exclusion criteria for ROI analysis. Blinded reader dentate-to-cerebellar white matter ratios were significantly associated with gadolinium-based contrast agent doses (rs = 0.77, P = .001). The dentate-to-pons ratio and dentate-to-cerebellar white matter ratios based on automated ROI placement were also significantly correlated with gadolinium-based contrast agent doses (t = 4.98, P < .0001 and t = 2.73, P < .02, respectively). In pediatric patients, the number of prior gadolinium-based contrast agent doses is significantly correlated with progressive T1-weighted dentate hyperintensity. Definitive confirmation of

  7. The determination of samarium, europium, gadolinium and dysprosium in uranium products by direct-current plasma emission spectrometry.

    PubMed

    Flavelle, F; Westland, A D

    1986-05-01

    Samarium, europium, gadolinium and dysprosium were separated from uranium-containing materials by means of solvent extraction with Alamine 336, followed by cation-exchange. The elements were determined in the sub-ppm range by means of direct-current plasma atomic-emission spectrometry.

  8. Neutron and Charged-Particle Induced Cross Sections for Radiochemistry in the Region of Samarium, Europium, and Gadolinium

    SciTech Connect

    Hoffman, R D; Kelley, K; Dietrich, F S; Bauer, R; Mustafa, M

    2004-11-30

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron and proton induced nuclear reaction cross sections in the mass region of samarium, europium and gadolinium (62 {le} Z {le} 64, 82 {le} N {le} 96).

  9. Hybrid gold-gadolinium nanoclusters for tumor-targeted NIRF/CT/MRI triple-modal imaging in vivo

    NASA Astrophysics Data System (ADS)

    Hu, De-Hong; Sheng, Zong-Hai; Zhang, Peng-Fei; Yang, Da-Zhi; Liu, Shu-Hui; Gong, Ping; Gao, Du-Yang; Fang, Sheng-Tao; Ma, Yi-Fan; Cai, Lin-Tao

    2013-01-01

    Multimodal imaging is highly desirable for accurate diagnosis because it can provide complementary information from each imaging modality. In this study, we prepared hybrid gold-gadolinium nanoclusters (NCs), which are ultrasmall, stable, biocompatible, and suitable for triple-modal NIRF/CT/MRI imaging. Upon intravenously injected, the hybrid NCs are effectively accumulated in tumor tissues and quickly clear by renal excretion, indicating their capacity of tumor targeting and low body residues. Notably, the ultrasmall hybrid NCs would penetrate into the solid tumor for capturing its heterostructure and do not induce potential toxicity in vivo. Hence, the well-defined hybrid gold-gadolinium NCs provide a versatile nanoprobe for cancer targeted imaging and diagnosis in vivo.Multimodal imaging is highly desirable for accurate diagnosis because it can provide complementary information from each imaging modality. In this study, we prepared hybrid gold-gadolinium nanoclusters (NCs), which are ultrasmall, stable, biocompatible, and suitable for triple-modal NIRF/CT/MRI imaging. Upon intravenously injected, the hybrid NCs are effectively accumulated in tumor tissues and quickly clear by renal excretion, indicating their capacity of tumor targeting and low body residues. Notably, the ultrasmall hybrid NCs would penetrate into the solid tumor for capturing its heterostructure and do not induce potential toxicity in vivo. Hence, the well-defined hybrid gold-gadolinium NCs provide a versatile nanoprobe for cancer targeted imaging and diagnosis in vivo. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr33543c

  10. Endolymphatic hydrops in Meniere's disease detected by MRI after intratympanic administration of gadolinium: comparison with sudden deafness.

    PubMed

    Horii, Arata; Osaki, Yasuhiro; Kitahara, Tadashi; Imai, Takao; Uno, Atsuhiko; Nishiike, Suetaka; Fujita, Norihiko; Inohara, Hidenori

    2011-06-01

    The detection rate of endolymphatic hydrops was significantly higher in patients with Meniere's disease compared with those with sudden deafness, indicating that 3 T magnetic resonance imaging (MRI) with intratympanic gadolinium injection was effective in diagnosing endolymphatic hydrops. To compare the detection rate of endolymphatic hydrops between patients with Meniere's disease and sudden deafness as controls by 3 T MRI after intratympanic gadolinium injection with conventional pulse sequence such as two-dimensional fluid-attenuated inversion recovery. Ten patients with unilateral Meniere's disease and eight with sudden deafness underwent inner ear MRI 24 h after intratympanic gadolinium injection. The endolymphatic space was detected as a low signal intensity area, while the perilymphatic space showed high intensity by gadolinium enhancement. Due to faint enhancement, images could not be evaluated in 1 of 10 patients with Meniere's disease. However, the other nine patients together with two of the eight with sudden deafness were diagnosed as having hydrops. The difference in detection rates between the two diseases was statistically significant. Two hydrops-positive cases with sudden deafness were considered to be of the secondary type of hydrops, because images were taken after partial recovery from hearing loss several months after the onset of the disease.

  11. The feasibility of in vivo quantification of bone-gadolinium in humans by prompt gamma neutron activation analysis (PGNAA) following gadolinium-based contrast-enhanced MRI

    NASA Astrophysics Data System (ADS)

    Mostafaei, F.; McNeill, F. E.; Chettle, D. R.; Noseworthy, M. D.; Prestwich, W. V.

    2015-11-01

    The feasibility of using a 238Pu/Be-based in vivo prompt γ-ray neutron activation analysis (IVNAA) system, previously successfully used for measurements of muscle, for the detection of gadolinium (Gd) in bone was presented. Gd is extensively used in contrast agents in MR imaging. We present phantom measurement data for the measurement of Gd in the tibia. Gd has seven naturally occurring isotopes, of which two have extremely large neutron capture cross sections; 155Gd (14.8% natural abundance (NA), σ= 60,900 barns) and 157Gd (15.65% NA, σ= 254,000 barns). Our previous work focused on muscle but this only informs about the short term kinetics of Gd. We studied the possibility of measuring bone, as it may be a long term storage site for Gd. A human simulating bone phantom set was developed. The phantoms were doped with seven concentrations of Gd of concentrations 0.0, 25, 50, 75, 100, 120 and 150 ppm. Additional elements important for neutron activation analysis, Na, Cl and Ca, were also included to create an overall elemental composition consistent with Reference Man. The overall conclusion is that the potential application of this Pu-Be-based prompt in vivo NAA for the monitoring of the storage and retention of Gd in bone is not feasible.

  12. Magnetic resonance knee arthrography. Enhanced contrast by gadolinium complex in the rabbit and in humans.

    PubMed

    Engel, A

    1990-01-01

    This study contains the fundamentals and the technique of the intraarticular application of an MRI contrast agent in connection with magnetic resonance imaging (MRI arthrography). It also presents the resulting clinical relevance for knee joint diagnostics. The significance of MRI arthrography is linked above all to the central question of whether or not it is possible to depict the hyaline cartilage, its surface and its thickness with the help of MRI arthrography. MRI arthrography was used for in vitro examinations of rabbit knee joint cartilage and human joint cartilage. The in vivo application was carried out in 73 patients. Apart from the metric evaluation and the assessment of the information content of the MRI image, the corresponding histologic sections were made in 20 knee joints in order to compare the cartilage surface and the thickness of the cartilage with the results in the MRI image. The optimum amount of contrast agent for visualization was determined, the uptake and clearance of the contrast agent from the cartilage were assessed, and trace elements from the cartilage were also analyzed. The examination showed that the molecular structure of the contrast agent (gadolinium-DTPA) does not prevent the uptake of the contrast agent into the matrix of the hyaline cartilage. But this process is reversible. Thus, 14 hours after the intraarticular application of the contrast agent no measurable traces of gadolinium-DTPA could be established. The intraarticular application of the contrast agent also made it possible to achieve a constant and reproducible visualization of all joint structures. This affected mainly the surface of the hyaline cartilage. The best imaging quality was achieved with intraarticular application of 30 to 40 mL of a 2 mmolar solution of gadolinium-DTPA. The technique used for the intraarticular application is the same as for the common procedures of knee joint aspiration. The clinical importance of MRI arthrography lies in the fact that

  13. Ligand basicity and rigidity control formation of macrocyclic polyamino carboxylate complexes of gadolinium(III)

    SciTech Connect

    Kumar, K.; Tweedle, M.F. )

    1993-09-29

    The formation reaction rates of some macrocyclic polyamino carboxylate complexes of gadolinium, GdL (where L is DO3A = 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid, H[sub 3]L, HP-DO3A = 10-(hydroxyproyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid, H[sub 3]L, and DO3MA = (1R,4R,7R)-[alpha],[alpha][prime],[alpha][double prime]-trimethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-triacetic acid, H[sub 3]L), have been measured at 25.0 [+-] 0.1 [degrees]C and at a constant ionic strength of 1.0 (NaCl) by an indicator method. The formation reactions are first order in the limiting reagent (ligand) and nearly independent of the excess reagent (gadolinium ion). A mechanism of the formation of the gadolinium complexes involves the formation of a precursor (intermediate) complex, Gd(*HL), in an equilibrium step followed by its deprotonation and reorganization to the final product in the rate-determining step. The stability constants (log K[sub Gd(*HL)]) of the intermediate have been determined from the kinetic data and the values are 8.9 (DO3A), 9.0(HP-DO3A), and 10.7 (DO3MA). The nature of the intermediate is proposed in which the metal is coordinated to oxygens and at least one nitrogen of the ligand. Deprotonation and reorganization of the intermediate are specific-base assisted. The second-order rate constants (k[sub OH], M[sup [minus]1]s[sup [minus]1]) for the reorganization of the intermediate, Gd(*HL) (L are given in the parentheses), are (2.1 [+-] 0.1) x 10[sup 7] (DO3A), (1.23 [+-] 0.04) x 10[sup 7] (HP-DO3A), and (7.2 [+-] 0.3) x 10[sup 4] (DO3MA), compared to the literature data (7.1 [+-] 1) x 10[sup 7] (NOTA) and (5.9 [+-] 0.2) x 10[sup 6] (DOTA). The specific-base assisted rate of reorganization of the intermediate, Gd(*HL), is correlated with the ligand strain energy and its first protonation constant.

  14. Effect of gadolinium on the ryanodine receptor/sarcoplasmic reticulum calcium release channel of skeletal muscle.

    PubMed

    Sárközi, Sándor; Szegedi, Csaba; Lukács, Balázs; Ronjat, Michel; Jóna, István

    2005-01-01

    The effect of gadolinium ions on the sarcoplasmic reticulum (SR) calcium release channel/ryanodine receptor (RyR1) was studied using heavy SR (HSR) vesicles and RyR1 isolated from rabbit fast twitch muscle. In the [(3)H]ryanodine binding assay, 5 microM Gd(3+) increased the K(d) of the [(3)H]ryanodine binding of the vesicles from 33.8 nM to 45.6 nM while B(max), referring to the binding capacity, was not affected significantly. In the presence of 18 nM[(3)H]ryanodine and 100 microM free Ca(2+), Gd(3+) inhibited the binding of the radiolabeled ryanodine with an apparent K(d) value of 14.7 microM and a Hill coefficient of 3.17. In (45)Ca(2+) experiments the time constant of (45)Ca(2+) efflux from HSR vesicles increased from 90.9 (+/- 11.1) ms to 187.7 (+/- 24.9) ms in the presence of 20 microM gadolinium. In single channel experiments gadolinium inhibited the channel activity from both the cytoplasmic (cis) (IC(50) = 5.65 +/- 0.33 microM, n(Hill) = 4.71) and the luminal (trans) side (IC(50) = 5.47 +/- 0.24 microM, n(Hill) = 4.31). The degree of inhibition on the cis side didn't show calcium dependency in the 100 microM to 1 mM Ca(2+) concentration range which indicates no competition with calcium on its regulatory binding sites. When Gd(3+) was applied at the trans side, EGTA was present at the cis side to prevent the binding of Gd(+3) to the cytoplasmic calcium binding regulatory sites of the RyR1 if Gd(3+) accidentally passed through the channel. The inhibition of the channel did not show any voltage dependence, which would be the case if Gd(3+) exerted its effect after getting to the cis side. Our results suggest the presence of inhibitory binding sites for Gd(3+) on both sides of the RyR1 with similar Hill coefficients and IC(50) values.

  15. Effect of the mineralizer solution in the hydrothermal synthesis of gadolinium-doped (10% mol Gd) ceria nanopowders.

    PubMed

    Dell'Agli, Gianfranco; Spiridigliozzi, Luca; Marocco, Antonello; Accardo, Grazia; Ferone, Claudio; Cioffi, Raffaele

    2016-05-18

    Gadolinium-doped ceria is an attractive electrolyte material for potential application in solid oxide fuel cells (SOFCs) operating at intermediate temperatures typically with 10%-20% substitution of Ce+4 by Gd+3. In particular, 10% gadolinium-doped ceria seems to have the highest values of conductivities among the other dopant compositions. Nanosized powders of gadolinium-doped ceria were prepared by hydrothermal treatment using coprecipitate as a precursor and in the presence of 3 different mineralizer solutions. The powders obtained were characterized by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy and thermal analysis, while the electrical behavior of the corresponding pellets were ascertained by AC impedance spectroscopy. Nanocrystalline gadolinium-doped ceria powders with fluorite cubic crystal structure were obtained by hydrothermal treatment. Independent of the mineralizer used, these powders were able to produce very dense ceramics, especially when selecting an optimized sintering cycle. In contrast, the electrical behavior of the samples was influenced by the mineralizer solution, and the samples synthesized in the neutral and alkaline solutions showed higher values of electrical conductivity, in the range of temperatures of interest. By the coprecipitation method, it has been possible to synthesize nanosized gadolinium-doped cerium oxide in a fluorite structure, stable in a wide range of temperatures. Hydrothermal treatment directly on the as-synthesized coprecipitates, without any drying step, had a very positive effect on the powders, which can be sintered with a high degree of densification, especially with an optimized sintering cycle. Furthermore, the electrical behavior of these samples was very interesting, especially for the samples synthesized using neutral mineralizer solution and basic mineralizer solution.

  16. Late gadolinium enhancement and adverse outcomes in a contemporary cohort of adult survivors of tetralogy of Fallot.

    PubMed

    Dobson, Richard J; Mordi, Ify; Danton, Mark H; Walker, Niki L; Walker, Hamish A; Tzemos, Nikolaos

    2017-01-01

    Myocardial fibrosis has been associated with poorer outcomes in tetralogy of Fallot, however only a handful of studies have assessed its significance in the current era. Our aim was to quantify the amount of late gadolinium enhancement in both the LV and RV in a contemporary cohort of adults with surgically repaired tetralogy of Fallot, and assess the relationship with adverse clinical outcomes. Single centre cohort study SETTING: National tertiary referral center Patients: One hundred fourteen patients with surgically repaired tetralogy of Fallot with median age 29.5 years (range 17.5-64.2). Prospective follow-up for mean 2.4 years (SD 1.29). Cardiovascular magnetic resonance was performed, and late gadolinium enhancement mass was estimated for the LV using the 5-SD remote myocardium method, and for the RV using a segmental scoring system. Cohort characterization was determined through the use of a computerized database. Survival analysis from time of scan to first adverse event, defined as an episode of atrial arrhythmia, sustained ventricular arrhythmia, hospitalization with heart failure, or implantable cardioverter-defibrillator insertion. Eleven patients experienced an adverse outcome in the follow-up period, although there were no deaths. LV late gadolinium enhancement was associated with adverse outcomes in a univariate model (P = .027). However, when adjusted for age at scan the significant variables included NYHA class (P = .006), peak oxygen uptake (P = .028), number of prior sternotomies (P = .044), and higher indexed RV and LV end diastolic volumes (P = .002 and P < .001), but not RV or LV late gadolinium enhancement. Formal quantification of late gadolinium enhancement is not currently as helpful in ascertaining prognosis compared to other, more easily assessed parameters in a contemporary cohort of tetralogy of Fallot survivors, however assessment particularly of the LV holds promise for the future. © 2016 Wiley Periodicals

  17. Hepatic Gadolinium Deposition and Reversibility after Contrast Agent-enhanced MR Imaging of Pediatric Hematopoietic Stem Cell Transplant Recipients.

    PubMed

    Maximova, Natalia; Gregori, Massimo; Zennaro, Floriana; Sonzogni, Aurelio; Simeone, Roberto; Zanon, Davide

    2016-11-01

    Purpose To determine if hepatic gadolinium deposition occurs in pediatric patients with iron overload but normal renal and hepatic function who undergo gadolinium-based contrast agent (GBCA)-enhanced magnetic resonance (MR) imaging. Materials and Methods Design and execution of this study was approved by the Ethical Committee of Institute for Research in Maternal and Child Health Burlo Garofolo of Trieste (reference no. 1105/2015). Because of the retrospective nature of the study, the requirement to obtain informed consent was waived. Twenty-one recipients of allogeneic hematopoietic stem cell transplants who underwent GBCA-enhanced MR imaging for suspected infection or relapse followed by liver biopsy comprised the study group. The number of GBCA-enhanced MR examinations and cumulative gadolinium dose for each patient was analyzed by comparing liver histologic analysis and iron and gadolinium liver concentration (GLC). Eight patients had siderosis and underwent chelation therapy. The study group was compared with four control patients who were never exposed to GBCA. Statistical analysis was performed with Spearman rank coefficient for correlation. Results All 21 patients had positive correlations between GLC and total GBCA dose (r = 0.4486; P < .05) and between GLC and liver iron concentration (r = 0.56; P < .05). Patients who underwent deferoxamine therapy had a significant reduction of GLC (from 0.64 μg/g ± 0.29 to 0.20 μg/g ± 0.17 [standard deviation]; P < .05). Conclusion In the presence of siderosis, a transmetallation mechanism may be set off between ferric ion and gadoterate meglumine. Deferoxamine appears capable of binding to gadolinium ion. Further studies of the safety of GBCAs in severe siderosis are needed. Chelation should be considered in patients with iron overload and a history of GBCA exposure. (©) RSNA, 2016.

  18. Tolerance and Long-Term MRI Imaging of Gadolinium-Modified Meshes Used in Soft Organ Repair

    PubMed Central

    Letouzey, Vincent; Huberlant, Stéphanie; Cornille, Arnaud; Blanquer, Sébastien; Guillaume, Olivier; Lemaire, Laurent; Garric, Xavier; de Tayrac, Renaud

    2015-01-01

    Background Synthetic meshes are frequently used to reinforce soft tissues. The aim of this translational study is to evaluate tolerance and long-term MRI visibility of two recently developed Gadolinium-modified meshes in a rat animal model. Materials and Methods Gadolinium-poly-ε-caprolactone (Gd-PCL) and Gadolinium-polymethylacrylate (Gd-PMA) modified meshes were implanted in Wistar rats and their tolerance was assessed daily. Inflammation and biocompatibility of the implants were assessed by histology and immunohistochemistry after 30 days post implantation. Implants were visualised by 7T and 3T MRI at day 30 and at day 90. Diffusion of Gadolinium in the tissues of the implanted animals was assessed by Inductively Coupled Plasma Mass Spectrometry. Results Overall Gd-PMA coated implants were better tolerated as compared to those coated with Gd-PCL. In fact, Gd-PMA implants were characterised by a high ratio collagen I/III and good vascularisation of the integration tissues. High resolution images of the coated mesh were obtained in vivo with experimental 7T as well as 3T clinical MRI. Mass spectrometry analyses showed that levels of Gadolinium in animals implanted with coated mesh were similar to those of the control group. Conclusions Meshes coated with Gd-PMA are better tolerated as compared to those coated with Gd-PCL as no signs of erosion or significant inflammation were detected at 30 days post implantation. Also, Gd-PMA coated meshes were clearly visualised with both 7T and 3T MRI devices. This new technique of mesh optimisation may represent a valuable tool in soft tissue repair and management. PMID:25811855

  19. Preparation and evaluation of cerium(IV) tungstate powder as inorganic exchanger in sorption of cobalt and europium ions from aqueous solutions.

    PubMed

    El-Kamash, A M; El-Gammal, B; El-Sayed, A A

    2007-03-22

    Cerium(IV) tungstate powder was chemically synthesized and exploited as adsorbent material for the decontamination study of cobalt and europium ions from radioactive waste solutions under simulated conditions using batch technique. The influences of pH, particle size and temperature have been reported. The uptake of europium was found to be slightly greater than that of cobalt and the apparent sorption capacity increases with increase in temperature. Thermodynamic parameters such as changes in Gibbs free energy (DeltaG degrees), enthalpy (DeltaH degrees), and entropy (DeltaS degrees) were calculated. The numerical value of DeltaG degrees decreases with an increase in temperature, indicating that the sorption reaction of each ion was spontaneous and more favorable at higher temperature. The positive values of DeltaH degrees correspond to the endothermic nature of sorption processes and suggested that chemisorption was the predominant mechanism. A comparison of kinetic models applied to the sorption rate data of each ion was evaluated for the pseudo first-order, the pseudo second-order, intraparticle diffusion and homogeneous particle diffusion kinetic models. The results showed that both the pseudo second-order and the homogeneous particle diffusion models were found to best correlate the experimental rate data. The numerical values of the rate constants and particle diffusion coefficients were determined from the graphical representation of the proposed models. Activation energy (E(a)) and entropy (DeltaS++) of activation were also computed from the linearized form of Arrhenius equation.

  20. Comparative performance of passively Q-switched diode-pumped Yb:GGG, Yb:YAG, and Yb-doped tungstates lasers using Cr 4+ -doped garnets

    NASA Astrophysics Data System (ADS)

    Kalisky, Y.; Kalisky, O.; Rachum, U.; Boulon, G.; Brenier, A.

    2006-02-01

    We investigated the CW free-running and repetitive modulation in the kHz frequency domain of a passively Q-switched, diode-pumped Yb:YAG, Yb:GGG and Yb:KYW lasers, by using Cr 4+:YAG as a saturable absorber. The results presented here are focused towards the design of a passively Q-switched Yb doped garnets or Yb doped tungstates microlaser. The free-running performance of Yb:YAG, Yb:GGG, Yb:KGW and Yb:KYW were characterized, and experimental parameters such as gain and loss were evaluated. We carried out a fit between our experimental results and an existing numerical model, which relates the experimental and the physical parameters of the ytterbium diode-pumped system to the minimal threshold pumping power. The best performance among the laser crystals was obtained for Yb:YAG laser. A maximum peak power of ~4.5-kW, at an average output power of 1.32-W, were extracted with of ~25 % extraction efficiency.

  1. The magnetic structures of double tungstates, NaM(WO 4) 2, M=Fe, Cr: Examples for superexchange couplings mediated by [NaO 6]-octahedra

    NASA Astrophysics Data System (ADS)

    Nyam-Ochir, L.; Ehrenberg, H.; Buchsteiner, A.; Senyshyn, A.; Fuess, H.; Sangaa, D.

    The crystal structures of the double tungstates NaM(WO 4) 2 with M=Fe, Cr and their solid solution are similar to the wolframite-type structure in the space group P2/c, but with doubled a lattice parameter. Magnetization and neutron-diffraction data reveal that NaFe(WO 4) 2 orders antiferromagnetically below 5 K with a commensurate propagation vector k=({1}/{2},{1}/{2},{1}/{2}) and magnetic moments of Fe 3+ ions oriented along the a-axis. NaCr(WO 4) 2 is antiferromagnetic below 10 K. Its magnetic structure is based on the propagation vector k=({1}/{2},{1}/{2},0), and the magnetic moments of Cr 3+ ions are aligned along the b-axis. The magnetic structure in the bc-plane is explained by a supersuperexchange mechanism. Long-range magnetic superexchange interactions along paths including [NaO 6]-octahedra are necessary to explain the observed magnetic structures. Mixed NaFe xCr 1-x(WO 4) 2, with x=0.25, 0.5, 0.75, do not indicate magnetic order, neither in magnetization nor neutron-diffraction data.

  2. Influence of gadolinium doping on the structure and defects of ceria under fuel cell operating temperature

    NASA Astrophysics Data System (ADS)

    Acharya, S. A.; Gaikwad, V. M.; Sathe, V.; Kulkarni, S. K.

    2014-03-01

    Correlation between atomic positional shift, oxygen vacancy defects, and oxide ion conductivity in doped ceria system has been established in the gadolinium doped ceria system from X-ray diffraction (XRD) and Raman spectroscopy study at operating temperature (300-600 °C) of Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC). High temperature XRD data are used to quantify atomic positional shift from mean position with temperature. The Raman spectroscopy study shows additional vibration modes related to ordering of defect spaces (GdCe'-Vo••)* and (2GdCe'-Vo••)x generated due to association of oxygen vacancies and reduced cerium or dopant cations site (Gd3+), which disappear at 450 °C; indicating oxygen vacancies dissociation from the defect complex. The experimental evidences of cation-anion positional shifting and oxygen vacancies dissociation from defect complex in the IT-SOFC operating temperature are discussed to correlate with activation energy for ionic conductivity.

  3. Novel structured gadolinium doped ceria based electrolytes for intermediate temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Timurkutluk, Bora; Timurkutluk, Cigdem; Mat, Mahmut D.; Kaplan, Yuksel

    Novel three-layered intermediate temperature solid oxide fuel cell (SOFC) electrolytes based on gadolinium doped ceria (GDC) are developed to suppress the electronic conductivity of GDC, to improve the mechanical properties of the cell and to minimize power loss due to mixed conductive nature of GDC. Three different electrolytes are fabricated by sandwiching thin YSZ, ScSZ and ScCeSZ between two relatively thick GDC layers. An electrolyte composed of pure GDC is also manufactured for comparison. NiO/GDC and LSCF/GDC electrodes are then coated on the electrolytes by a screen printing route. SEM results show that it is possible to obtain dense and crack free thin layers of YSZ, ScSZ and ScCeSZ between two GDC layers without delamination. Performance measurements indicate that interlayered thin electrolytes act as an electronic conduction barrier and improve open circuit voltages (OCVs) of GDC based cells.

  4. Synthesis of bulk-size transparent gadolinium oxide-polymer nanocomposites for gamma ray spectroscopy.

    PubMed

    Cai, Wen; Chen, Qi; Cherepy, Nerine; Dooraghi, Alex; Kishpaugh, David; Chatziioannou, Arion; Payne, Stephen; Xiang, Weidong; Pei, Qibing

    2013-03-14

    Heavy element loaded polymer composites have long been proposed to detect high energy X- and γ-rays upon scintillation. The previously reported bulk composite scintillators have achieved limited success because of the diminished light output resulting from fluorescence quenching and opacity. We demonstrate the synthesis of a transparent nanocomposite comprising gadolinium oxide nanocrystals uniformly dispersed in bulk-size samples at a high loading content. The strategy to avoid luminescence quenching and opacity in the nanocomposite was successfully deployed, which led to the radioluminescence light yield of up to 27 000/MeV, about twice as much as standard commercial plastic scintillators. Nanocomposites monoliths (14 mm diameter by 3 mm thickness) with 31 wt% loading of nanocrystals generated a photoelectric peak for Cs-137 gamma (662 keV) with 11.4% energy resolution.

  5. Characterization of PAH matrix with monazite stream containing uranium, gadolinium and iron

    NASA Astrophysics Data System (ADS)

    Pal, Sangita; Meena, Sher Singh; Goswami, D.

    2016-05-01

    Uranium (U) gadolinium(Gd) and iron (Fe) containing alkaline waste simulated effluent (relevant to alkaline effluent of monazite ore) has been treated with a novel amphoteric resin viz, Polyamidehydroxamate (PAH) containing amide and hydroxamic acid groups. The resin has been synthesized in an eco-friendly manner by polymerization nad conversion to functional groups characterized by FT-IR spectra and architectural overview by SEM. Coloration of the loaded matrix and de-coloration after extraction of uranium is the special characteristic of the matrix. Effluent streams have been analyzed by ICP-AES, U loaded PAH has been characterized by FT-IR, EXAFS, Gd and Fe by X-ray energy values of EDXRF at 6.053 Kev and 6.405 Kev respectively. The remarkable change has been observed in Mössbauer spectrum of Fe-loaded PAH samples.

  6. Luminescence properties of Eu3+-doped Lanthanum gadolinium hafnates transparent ceramics

    NASA Astrophysics Data System (ADS)

    Wang, Zhengjuan; Zhou, Guohong; Zhang, Jian; Qin, Xianpeng; Wang, Shiwei

    2017-09-01

    Eu3+-doped Lanthanum gadolinium hafnates (La0.8Gd1.2Hf2O7) transparent ceramics with different Eu3+ concentration were fabricated by vacuum sintering. XRD results showed all the ceramics are cubic pyrochlore structure. The effects of annealing process on in-line transmittance and luminescence behavior of the Eu3+-doped La0.8Gd1.2Hf2O7 transparent ceramics were investigated. Before annealing, the in-line transmittance of the ceramics was low and the luminescence intensity was weak. As Eu3+ doping content increased, the transmittance as well as the luminescence intensity decreased. This was ascribed to oxygen vacancy and other defects in the ceramics resulted from the vacuum sintering. After annealing, the transmittance and luminescence intensity were raised, indicating the elimination of oxygen vacancy. Moreover, with the increase of Eu3+ doping content from 1 at% to 10 at%, the luminescence intensity increased without concentration quenching.

  7. Gadolinium-free MR in coarctation-can contrast-enhanced MR angiography be replaced?

    PubMed

    Kalmar, Peter I; Koestenberger, Martin; Marterer, Robert; Tschauner, Sebastian; Sorantin, Erich

    2016-01-01

    To determine the difference in vessel measurements, signal-to-noise ratio (SNR), and voxel size between contrast-enhanced and noncontrast magnetic resonance techniques in patients with coarctation of the aorta (CoA). In 39 patients, vessel size, SNR, and voxel size were compared in cine magnetic resonance imaging (MRI), gadolinium-free magnetic resonance angiography (Gd-free MRA), and contrast-enhanced MRA (ce-MRA). There was no significant difference in measurement and SNR, but there was a significant difference in voxel size (P<.001). Our results show that, in CoA patients, monitoring of vessel size using cine MRI and Gd-free MRA is equivalent to ce-MRA while being less invasive. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Radioluminescence and optical studies of gadolinium calcium phosphate oxyfluoride glasses doped with Sm3+

    NASA Astrophysics Data System (ADS)

    Meejitpaisan, P.; Insiripong, S.; Kedkaew, C.; Kim, H. J.; Kaewkhao, J.

    2017-08-01

    Sm3+-doped gadolinium calcium phosphate oxyfluoride glasses have been synthesized and investigated their optical, photo and radioluminescence properties. The glasses were prepared by melt quenching technique at 1400 °C. The characteristic absorption bands of Sm3+ ions originating from the 6H5/2 ground state and occurring absorbed photon in visible light (VIS) and near-infrared (NIR) region with clearly observed from absorption spectra. From the photoluminescence (PL), the glasses showed the emission at 561 (4G5/2→6H5/2), 598 (4G5/2→6H7/2), 644 (4G5/2→6H9/2) and 705 nm (4G5/2→6H11/2). The radioluminescence (RL), emission spectra were corresponding to those from PL measurements. From RL measurement, the integral scintillation efficiency of developed glass was determined at 43% when compared with BGO crystal.

  9. Analysis of Blood Gadolinium in an Isotope Geochemist Following Contrast MRI

    NASA Astrophysics Data System (ADS)

    Wasylenki, L. E.

    2011-12-01

    Normal brain tissue does not have blood flowing throughout it; instead oxygen diffuses across a blood-brain barrier in order to oxygenate brain cells. Brain tumors, however, do grow blood supplies, so an abnormal distribution of blood in the brain is a key indicator of abnormal cell growth. But how is the distribution of blood in inside the brain observed? The lanthanide ion gadolinium(III) has unpaired 5f-shell electrons and is thus paramagnetic. As such, the presence of Gd causes the nuclei of nearby atoms to relax more quickly when excited to high-energy spin states by pulses of radio-frequency energy than they would without Gd nearby. The signal in magnetic resonance imaging correlates with this nuclear spin relaxation time, so gadolinium's presence in certain body tissues makes those tissues appear as bright areas on MRI images. Gadolinium is therefore commonly injected intravenously just prior to MRI imaging, so that the distribution of blood in and around the brain can be mapped. Gadolinium as a free ion is toxic, so it is injected in a relatively inert form, often as gadoversetamide, in which Gd is tightly bound in nine-fold coordination with N, C, and O. This compound is removed from the blood by the kidneys at a rate that is fast compared to the rate of breakdown of this compound in the blood, thus preventing release of toxic Gd in the bloodstream. But how quickly can the kidneys of an isotope geochemist remove Gd from blood? In this experiment, a single isotope geochemist's wristwatch was synchronized with that of the MRI technician and then left in a dressing room with all other magnetically susceptible objects until after the MRI. The time of intravenous injection of gadoversetamide into the isotopist was recorded by the technician and later transmitted verbally to the isotopist. Following the MRI session, blood samples were collected by self-fingerprick, in a Class 100 trace metal clean lab, from 47 to 281 minutes after intravenous injection. For each

  10. Modeling of gadolinium recovery from nitrate medium with 8-hydroxyquinoline by emulsion liquid membrane.

    PubMed

    Hasan, M A; Aglan, R F; El-Reefy, S A

    2009-07-30

    The extraction equilibrium of Gd(III) from nitrate medium by 8-hydroxyquinoline (HOX) in toluene was studied. Liquid-liquid investigations were first carried out. Based on the equilibrium results, the extraction of Gd(III) from aqueous nitrate medium into an emulsion liquid membrane system (ELM) containing 8-hydroxyquinoline in toluene as extractant, HNO(3) as stripping solution, Span-80 as surfactant was studied. The stability of the prepared ELM was studied in terms of the degree of membrane breakage. The different parameters affecting the permeation of gadolinium (III) were also studied. A general permeation model for the recovery of Gd(III) by the selected membrane is presented. The internal mass transfer in the water in oil (W/O) emulsion drop, the external mass transfer around the drop, the rates of formation and decomposition of the complex at the external aqueous-organic interface were considered.

  11. X-ray Absorption Improvement of Single Wall Carbon Nanotube through Gadolinium Encapsulation

    NASA Astrophysics Data System (ADS)

    Alimin; Narsito, I.; Kartini; Santosa, S. J.

    2016-02-01

    X-ray absorption improvement of single-wall carbon nanotube (SWCNT) through gadolinium (Gd) encapsulation has been studied. The liquid phase adsorption using ethanol has been performed for the doping treatment. The Gd-doped SWCNT (Gd@SWCNT) was characterized by nitrogen adsorption isotherms, Raman spectroscopy, Transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA) techniques. A relatively high residual weight of Gd@SWCNT compared to non-doped SWCNT (n-SWCNT) indicated that Gd has been doped in the nanotube. Even though Gd nanoparticles could not be observed clearly by TEM image, however, a significant decrease of nitrogen uptakes at low pressure and RBM (Radial Breathing Mode) upshift of Raman spectra of Gd@SWCNT specimen suggest that the metal nanoparticles might be encapsulated in the internal tube spaces of the nanotube. It was found that Gd-doped in the SWCNT increased significantly mass attenuation coefficient of the nanotube.

  12. Characterization of PAH matrix with monazite stream containing uranium, gadolinium and iron

    SciTech Connect

    Pal, Sangita Goswami, D.; Meena, Sher Singh

    2016-05-23

    Uranium (U) gadolinium (Gd) and iron (Fe) containing alkaline waste simulated effluent (relevant to alkaline effluent of monazite ore) has been treated with a novel amphoteric resin viz, Polyamidehydroxamate (PAH) containing amide and hydroxamic acid groups. The resin has been synthesized in an eco-friendly manner by polymerization nad conversion to functional groups characterized by FT-IR spectra and architectural overview by SEM. Coloration of the loaded matrix and de-coloration after extraction of uranium is the special characteristic of the matrix. Effluent streams have been analyzed by ICP-AES, U loaded PAH has been characterized by FT-IR, EXAFS, Gd and Fe by X-ray energy values of EDXRF at 6.053 KeVand 6.405 KeV respectively. The remarkable change has been observed in Mössbauer spectrum of Fe-loaded PAH samples.

  13. Obtaining gadolinium nanoparticles and studying their properties in a helium flow

    NASA Astrophysics Data System (ADS)

    Petinov, V. I.

    2016-07-01

    A method for obtaining Gd nanoparticles with diameters of 89 to 18 nm upon metal evaporation both in a flow of pure helium and with the addition of 0.5% of oxygen is described. It is found that the addition of O2 does not affect the size of the particles, their structure, or the Curie temperature, though the magnetization is reduced. Particles with sizes of 18 nm have cubic lattice symmetry (fcc) and remain paramagnetic below T c; with an increase in the size of nanoparticles, the proportion of the hexagonal (hcp) phase, which coincides with the gadolinium structure, also grows, and below T c such particles become ferromagnetic. Oxygen impurities seem to have no effect on magnetic and structural transitions in nanoparticles.

  14. Effect of Gadolinium Doping on the Air Oxidation of Uranium Dioxide

    SciTech Connect

    Scheele, Randall D.; Hanson, Brady D.; Cumblidge, Stephen E.; Jenson, Evan D.; Kozelisky, Anne E.; Sell, Rachel L.; MacFarlan, Paul J.; Snow, Lanee A.

    2004-12-04

    Researchers at the Pacific Northwest National Laboratory (PNNL) investigated the effects of gadolinia concentration on the air oxidization of gadolinia-doped uranium dioxide using thermogravimetry and differential scanning calorimetry to determine if such doping could improve uranium dioxide's stability as a nuclear fuel during potential accident scenarios in a nuclear reactor or during long-term disposal. We undertook this study to determine whether the resistance of the uranium dioxide to oxidation to the orthorhombic U3O8 with its attendant crystal expansion could be prevented by addition of gadolinia. Our studies found that gadolinium has little effect on the thermal initiation of the first step of the reported two-step air oxidation of UO2; however, increasing gadolinia content does stabilize the initial tetragonal or cubic product allowing significant oxidation before the second expansive step to U3O8 begins.

  15. Feasibility study of a gadolinium-loaded DIN-based liquid scintillator

    NASA Astrophysics Data System (ADS)

    Song, Sook Hyung; Joo, Kyung Kwang; So, Sun Heang; Yeo, In Sung

    2013-09-01

    DIN (di-isopropylnaphthalene) has a high flashpoint and can be used as a base solvent in liquid scintillators. It reduces safety concerns to humans and the environment. (PPO, 3 g/ ℓ) and (bis-MSB, 30 mg/ ℓ) were dissolved to formulate a DIN-based liquid scintillator (LS). A gadolinium (Gd) complex with carboxylic acid was synthesized using a neutralized chemical reaction. Then, 0.1% Gd was loaded into the LS. This Gd-loaded DIN-based LS using a solvent-solvent extraction method is the first attempt at a LS. In this study, we investigated the physical and the optical properties of this LS, and we will summarize all the characteristics of the Gd-loaded DIN-based LS.

  16. Synthesis of bulk-size transparent gadolinium oxide–polymer nanocomposites for gamma ray spectroscopy

    PubMed Central

    Cai, Wen; Chen, Qi; Cherepy, Nerine; Dooraghi, Alex; Kishpaugh, David; Chatziioannou, Arion; Payne, Stephen; Xiang, Weidong

    2015-01-01

    Heavy element loaded polymer composites have long been proposed to detect high energy X- and γ-rays upon scintillation. The previously reported bulk composite scintillators have achieved limited success because of the diminished light output resulting from fluorescence quenching and opacity. We demonstrate the synthesis of a transparent nanocomposite comprising gadolinium oxide nanocrystals uniformly dispersed in bulk-size samples at a high loading content. The strategy to avoid luminescence quenching and opacity in the nanocomposite was successfully deployed, which led to the radioluminescence light yield of up to 27 000/MeV, about twice as much as standard commercial plastic scintillators. Nanocomposites monoliths (14 mm diameter by 3 mm thickness) with 31 wt% loading of nanocrystals generated a photoelectric peak for Cs-137 gamma (662 keV) with 11.4% energy resolution. PMID:26478816

  17. Transient band structures in the ultrafast demagnetization of ferromagnetic gadolinium and terbium

    NASA Astrophysics Data System (ADS)

    Teichmann, Martin; Frietsch, Björn; Döbrich, Kristian; Carley, Robert; Weinelt, Martin

    2015-01-01

    We compare the laser-driven demagnetization dynamics of the rare earths gadolinium and terbium by mapping their transient valance band structures with time- and angle-resolved photoelectron spectroscopy. In both metals, the minority and majority spin valence bands evolve independently with different time constants after optical excitation. The ultrafast shift of the partially unoccupied minority spin bulk band to higher binding energy and of the majority spin surface state to lower binding energy suggests spin transport between surface and bulk. The slower response of the fully occupied majority spin band follows the lattice temperature and is attributed to Elliott-Yafet type spin-flip scattering. Terbium shows a stronger and faster decay of the exchange splitting, pointing to ultrafast magnon emission via 4 f spin-to-lattice coupling.

  18. Dielectric and conducting behavior of gadolinium-terbium fumarate heptahydrate crystals

    NASA Astrophysics Data System (ADS)

    Shah, M. D.; Want, B.

    2015-07-01

    Gadolinium-terbium fumarate heptahydrate crystals were grown in silica gel by using single gel diffusion technique. The crystals were characterized by different physico-chemical techniques of characterization. Powder X-ray diffraction results showed that the grown material is purely crystalline in nature. Elemental analyses suggested the chemical formula of the compound to be Gd Tb (C4H2O4)3ṡ7H2O. Energy dispersive X-ray analysis confirmed the presence of Gd and Tb in the title compound. The dielectric and conductivity studies of the grown compound were carried as function of frequency of applied field and the temperature. The grown material showed a dielectric anomaly which was correlated with its thermal behavior. The ac conductivity of the material showed Jonscher's power law behavior: σ(ω)=σo+Aωs, with a temperature-dependent power exponent s(<1). The conductivity was found to be a function of temperature and frequency.

  19. Controllable Fabrication and Optical Properties of Uniform Gadolinium Oxysulfate Hollow Spheres

    PubMed Central

    Chen, Fashen; Chen, Gen; Liu, Tao; Zhang, Ning; Liu, Xiaohe; Luo, Hongmei; Li, Junhui; Chen, Limiao; Ma, Renzhi; Qiu, Guanzhou

    2015-01-01

    Uniform gadolinium oxysulfate (Gd2O2SO4) hollow spheres were successfully fabricated by calcination of corresponding Gd-organic precursor obtained via a facile hydrothermal process. The Gd2O2SO4 hollow spheres have a mean diameter of approximately 550 nm and shell thickness in the range of 30–70 nm. The sizes and morphologies of as-prepared Gd2O2SO4 hollow spheres could be deliberately controlled by adjusting the experimental parameters. Eu-doped Gd2O2SO4 hollow spheres have also been prepared for the property modification and practical applications. The structure, morphology, and properties of as-prepared products were characterized by XRD, TEM, HRTEM, SEM and fluorescence spectrophotometer. Excited with ultraviolet (UV) pump laser, successful downconversion (DC) could be achieved for Eu-doped Gd2O2SO4 hollow spheres. PMID:26671661

  20. In vivo selective cancer-tracking gadolinium eradicator as new-generation photodynamic therapy agent

    PubMed Central

    Zhang, Tao; Lan, Rongfeng; Chan, Chi-Fai; Law, Ga-Lai; Wong, Wai-Kwok; Wong, Ka-Leung

    2014-01-01

    In this work, we demonstrate a modality of photodynamic therapy (PDT) through the design of our truly dual-functional—PDT and imaging—gadolinium complex (Gd-N), which can target cancer cells specifically. In the light of our design, the PDT drug can specifically localize on the anionic cell membrane of cancer cells in which its laser-excited photoemission signal can be monitored without triggering the phototoxic generation of reactive oxygen species—singlet oxygen—before due excitation. Comprehensive in vitro and in vivo studies had been conducted for the substantiation of the effectiveness of Gd-N as such a tumor-selective PDT photosensitizer. This treatment modality does initiate a new direction in the development of “precision medicine” in line with stem cell and gene therapies as tools in cancer therapy. PMID:25453097