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Sample records for gd tb er

  1. Structures and magnetocaloric effects of Gd65-xRExFe20Al15 (x = 0-20; RE=Tb, Dy, Ho, and Er) ribbons

    NASA Astrophysics Data System (ADS)

    Fang, Y. K.; Chen, H. C.; Hsieh, C. C.; Chang, H. W.; Zhao, X. G.; Chang, W. C.; Li, W.

    2011-04-01

    Gd-based Gd65-xRExFe20Al15 (x = 0-20, RE = Tb, Dy, Ho, and Er) alloys in ribbon form have been prepared by rapid quenching technology. It is found that the Gd65-xTbxFe20Al15 ribbons are in amorphous state. However, for the Gd65-xRExFe20Al15(RE = Dy, Ho, and Er) ribbons, in addition to a diffuse diffraction band, peaks from hexagonal rare-earth-rich phases are present indicating a mixture of amorphous and crystalline phases. This indicates that the heavier rare-earth elements (Dy, Ho, and Er) will decrease glass formability in the Gd-based Gd65-xRExFe20Al15 (RE = Dy, Ho, and Er) ribbons. The magnetic entropy changes of these ribbons increase with increasing the contents of the heavier rare-earth elements. The maximal magnetic entropy changes of the Gd45RE20Fe20Al15 (RE = Tb, Dy, Ho, and Er) ribbons are located in the range of 4.46-5.57 J/kg K under 50 kOe. Refrigerant capacity values are obtained to be about 580-720 J/kg under 50 kOe. These values are comparable to or even higher than those of Gd-based bulk metallic glass alloys.

  2. Local magnetic moment formation at 119Sn Mössbauer impurity in RCo2 (R=Gd,Tb,Dy,Ho,Er) Laves phase compounds

    NASA Astrophysics Data System (ADS)

    de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.

    2008-04-01

    In this work, we theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a Mösbauer Sn119 impurity diluted at the R site (R=Gd,Tb,Dy,Ho,Er) of the cubic Laves phase intermetallic compounds RCo2. One considers that the magnetic hyperfine fields have two contributions, (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24, 1601 (1963)] model, and (ii) the contribution from the induced magnetic moments arising from the Co neighboring sites. Our calculated self-consistent total magnetic hyperfine fields are in a good agreement with recent experimental data.

  3. Electron-magnon interaction in RNiBC (R=Er, Ho, Dy, Tb, and Gd) series of compounds based on magnetoresistance measurements

    NASA Astrophysics Data System (ADS)

    Fontes, M. B.; Trochez, J. C.; Giordanengo, B.; Bud'ko, S. L.; Sanchez, D. R.; Baggio-Saitovitch, E. M.; Continentino, M. A.

    1999-09-01

    We present a study of the transport and magnetic properties of a series of RNiBC compounds (R=Er, Ho, Dy, Tb, and Gd). All the materials investigated have long range magnetic order at sufficiently low temperatures. Magnetoresistance measurements are presented for a large range of temperatures (T) and magnetic fields (H). We show that below the critical temperature, the temperature dependence of the resistivity is determined by electron scattering due to the elementary excitations (spin waves) of the ordered magnetic phase and the values of the gap in the magnon spectra were derived. Finally we discuss the H×T phase diagram of these materials.

  4. Magnetic properties of R2Co15Al2 compounds with R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm

    NASA Astrophysics Data System (ADS)

    Shen, Bao-gen; Cheng, Zhao-hua; Zhang, Shao-ying; Wang, Jing-yun; Liang, Bing; Zhang, Hong-wei; Zhan, Wen-shan

    1999-03-01

    An investigation of the structure and the magnetic anisotropy of R2Co15Al2 (R=Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) compounds has been performed by means of x-ray diffraction and magnetization measurements. X-ray diffraction shows the prepared compounds to be single phase, having the hexagonal Th2Ni17-type structure for R=Y, Ho, Er, and Tm and the rhombohedral Th2Zn17-type structure for R=Ce, Pr, Nd, Gd, Tb, and Dy. Except for the Ce compound, the unit-cell volumes of R2Co15Al2 compounds decrease in accordance with the lanthanide contraction. Substitution of Al for Co in R2Co17 leads to a decrease of the saturation magnetization at 1.5 K and Curie temperature. The exchange-coupling constants JCo-Co and JR-Co have been calculated by using the method based on magnetic ordering temperature. It is found that the JR-Co has a small dependence on the R elements and is almost not affected by the Al substitution. The Ce compound is found to exhibit an anomalous lattice parameter and magnetic characteristic, which are relative to the mixed-valence behavior of the Ce ion. X-ray diffraction measurements on magnetically aligned R2Co15Al2 powders show that the compounds with R=Pr, Nd, Gd, Tb, Dy, and Ho have an easy-plane type of magnetic anisotropy, whereas the compounds with R=Y, Ce, Sm, Er, and Tm exhibit an easy-axis type of magnetic anisotropy at room temperature. The compounds R2Co15Al2 with R=Pr and Ho exhibit a spin-reorientation transition and the spin-reorientation temperature is found to be 531 and 431 K, respectively. A strong uniaxial anisotropy is observed in Sm2Co15Al2 compound with a magnetocrystalline anisotropy field of 84 kOe at room temperature.

  5. Magnetic ordering in Sc2CoSi2-type R2FeSi2 (R=Gd, Tb) and R2CoSi2 (R=Y, Gd-Er) compounds

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Pani, M.; Nirmala, R.; Quezado, S.; Malik, S. K.

    2016-09-01

    Magnetic and magnetocaloric properties of Sc2CoSi2-type R2TSi2 (R=Gd-Er, T=Fe, Co) compounds have been studied using magnetization data. These indicate the presence of mixed ferromagnetic and antiferromagnetic interactions in these compounds. One observes a ferromagnetic transition followed by an antiferromagnetic order and a further possible spin-reorientation transition at low temperatures. Compared to Gd2{Fe, Co}Si2, the Tb2FeSi2 and {Tb-Er}2CoSi2 compounds exhibit remarkable hysteresis (for e.g. Tb2FeSi2 shows residual magnetization Mres/Tb=2.45 μB, coercive field Hcoer=14.9 kOe, and critical field Hcrit 5 kOe at 5 K) possibly due to the magnetocrystalline anisotropy of the rare earth. The R2{Fe, Co}Si2 show relatively small magnetocaloric effect (i.e. isothermal magnetic entropy change, ΔSm) around the magnetic transition temperature: the maximal value of MCE is demonstrated by Ho2CoSi2 (ΔSm=-8.1 J/kg K at 72 K and ΔSm=-9.4 J/kg K at 23 K in field change of 50 kOe) and Er2CoSi2 (ΔSm=-13.6 J/kg K at 32 K and ΔSm=-8.4 J/kg K at 12 K in field change of 50 kOe).

  6. New Materials Derived from Ybco: CrSr2RECu2O8 (RE = La, Pr, Nd, Eu, Gd, Tb, Dy, Y, Ho, Er, Lu).

    PubMed

    Ruiz-Bustos, Rocío; Aguirre, Myriam H; Alario-Franco, Miguel A

    2005-05-02

    Eleven new oxides, derived from yttrium barium copper oxide by replacing the square-planar copper [Cu-O4] of the basal plane of the triple perovskite-based structure with octahedral Cr(IV), have been prepared at high pressure and temperature. Their crystal structures have been determined, and their complex microstructure has been established by means of high-resolution electron microscopy and electron diffraction. The materials have a general formula of CrSr2RECu2O8 (RE = La, Pr, Nd, Eu, Gd, Tb, Dy, Y, Ho, Er, and Lu); they are tetragonal, show the symmetry of space group P4/mmm, and do not appear to be superconducting.

  7. The interplay between magnetism and superconductivity in RNi 2B 2C (R dbnd Lu, Tm, Er, Ho, Dy, Tb, Gd)

    NASA Astrophysics Data System (ADS)

    El Massalami, M.; Bud'ko, S. L.; Giordanengo, B.; Baggio-Saitovitch, E. M.

    1995-02-01

    The superconducting and magnetic phase diagram (characteristic temperatures versus effective ionic radii) of the RNi 2B 2C (R dbnd Lu, Tm, Er, Ho, Dy, Tb, Gd) compounds are considered. Although the gradual degradation of superconductivity can be scaled to the de Gennes factor, ( g-1) 2J( J + 1), the unique reentrant behavior of the HoNi 2B 2C compound and the abrupt quenching of superconductivity for R lighter than Ho are most probably unaccountable within this scheme. Rather, it is argued that their low- T magnetic and transport properties as well as the main features of the interplay between magnetism and superconductivity can be accounted for if the low- T magnetism of HoNi 2B 2C, as reported by Grigereit et al., is generalized to the other isomorphous R members. Thus the onset of the 4f moments antiferromagnetic state at T1 is accompanied by an oscillatory component, which transforms to a commensurate antiferromagnetic state at T2. For HoNi 2B 2C, the pressure and magnetic-field influence on Tc, T1 and T2 will be discussed.

  8. Infrared and Raman spectra of tris(dipivaloylmethanato) lanthanides, Ln(thd)3 (Ln = La, Nd, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu)

    NASA Astrophysics Data System (ADS)

    Belova, Natalya V.; Sliznev, Valery V.; Christen, Dines

    2017-03-01

    The infrared and Raman vibrational spectra of the series of solid tris(dipivaloylmethanato) lanthanides, Ln(thd)3 (Ln = La, Nd, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu), have been recorded at room temperature over wide ranges (4000-50 cm-1 and 3500-80 cm-1, respectively). The experimental spectra obtained in the present study were successfully assigned based on the quantum chemical calculations (DFT/PBE0) performed for the monomer Ln(thd)3 molecules. The experimental vibrational spectra for all complexes studied are rather similar as are the theoretical simulations. The data analysis shows that the main contributions to vibrational modes arise from the vibrations of the ligand possessing practically the same geometry for all complexes. According to the calculation results the structure of the coordination polyhedron is increasingly distorted in the series from La(thd)3 to Lu(thd)3. Although the contributions of the polyhedron vibrations in vibrational modes are not predominant, there is rise in the frequencies associated with vibrations of the coordination polyhedron LnO6 in this series. This increase has been explained by the concept of lanthanide contraction.

  9. Magnetic hyperfine interactions on Cd sites of the rare-earth cadmium compounds R Cd (R =Ce , Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er)

    NASA Astrophysics Data System (ADS)

    Cavalcante, F. H. M.; Leite Neto, O. F. L. S.; Saitovitch, H.; Cavalcante, J. T. P. D.; Carbonari, A. W.; Saxena, R. N.; Bosch-Santos, B.; Pereira, L. F. D.; Mestnik-Filho, J.; Forker, M.

    2016-08-01

    This paper reports the investigation of the magnetic hyperfine field Bh f in a series of rare-earth (R ) cadmium intermetallic compounds R Cd and GdCd2 measured by perturbed angular correlation (PAC) spectroscopy using 111In/111Cd as probe nuclei at Cd sites as well as first-principles calculations of Bh f at Cd sites in the studied compounds. Vapor-solid state reaction of R metals with Cd vapor and the 111In radioisotope was found to be an appropriate route of doping rare-earth cadmium compounds with the PAC probe 111In/111Cd. The observation that the hyperfine parameters depend on details of the sample preparation provides information on the phase preference of diffusing 111In in the rare-earth cadmium phase system. The 111Cd hyperfine field has been determined in the compounds R Cd for the R constituents Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er, in several cases as a function of temperature. For most R constituents, the temperature dependence Bh f(T ) of 111Cd:R Cd is consistent with ferromagnetic order of the compound. DyCd, however, presents a remarkable anomaly: a finite magnetic hyperfine field is observed only in the temperature interval 35 K ≤ T ≤ 80 K which indicates a transition from ferromagnetic order to a spin arrangement where all 4 f -induced contributions to the magnetic hyperfine field at the Cd site cancel. First-principles calculation results for DyCd show that the (π , π , 0) antiferromagnetic configuration is energetically more favorable than the ferromagnetic. The approach used in the calculations to simulate the R Cd system successfully reproduces the experimental values of Bh f at Cd sites and shows that the main contribution to Bh f comes from the valence electron polarization. The de Gennes plot of the hyperfine field Bh f of 111Cd:R Cd vs the 4 f -spin projection (g -1 )J reflects a decrease of the strength of indirect 4 f -4 f exchange across the R series. Possible mechanisms are discussed and the experimental results indicate that

  10. Magnetism in the KBaRE(BO3)2 (RE  =  Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) series: materials with a triangular rare earth lattice

    NASA Astrophysics Data System (ADS)

    Sanders, M. B.; Cevallos, F. A.; Cava, R. J.

    2017-03-01

    We report the magnetic properties of compounds in the KBaRE(BO3)2 family (RE  =  Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), materials with a planar triangular lattice composed of rare earth ions. The samples were analyzed by x-ray diffraction and crystallize in the space group R-3m. Physical property measurements indicate the compounds display predominantly antiferromagnetic interactions between spins without any signs of magnetic ordering above 1.8 K. The ideal 2D rare earth triangular layers in this structure type make it a potential model system for investigating magnetic frustration in rare-earth-based materials.

  11. Hetero-metallic {3d-4f-5d} complexes: preparation and magnetic behavior of trinuclear [(L(Me2)Ni-Ln){W(CN)(8)}] compounds (Ln = Gd, Tb, Dy, Ho, Er, Y; L(Me2) = Schiff base) and variable SMM characteristics for the Tb derivative.

    PubMed

    Sutter, Jean-Pascal; Dhers, Sébastien; Rajamani, Raghunathan; Ramasesha, S; Costes, Jean-Pierre; Duhayon, Carine; Vendier, Laure

    2009-07-06

    Assembling bimetallic {Ni-Ln}(3+) units and {W(CN)(8)}(3-) is shown to be an efficient route toward heteronuclear {3d-4f-5d} compounds. The reaction of either the binuclear [{L(Me2)Ni(H(2)O)(2)}{Ln(NO(3))(3)}] complexes or their mononuclear components [L(Me2)Ni] and Ln(NO(3))(3) with (HNBu(3))(3){W(CN)(8)} in dmf followed by diffusion of tetrahydrofuran yielded the trinuclear [{L(Me2)NiLn}{W(CN)(8)}] compounds 1 (Ln = Y), 2a,b (Gd), 3a,b (Tb), 4 (Dy), 5 (Ho), and 6 (Er) as crystalline materials. All of the derivatives possess the trinuclear core resulting from the linkage of the {W(CN)(8)} to the Ni center of the {Ni-Ln} unit. Differences are found in the solvent molecules acting as ligands and/or in the lattice depending on the crystallization conditions. For all the compounds ferromagnetic {Ni-W} and {Ni-Ln} (Ln = Gd, Tb, Dy, and Er} interactions are operative resulting in high spin ground states. Parameterization of the magnetic behaviors for the Y and Gd derivatives confirmed the strong cyano-mediated {Ni-W} interaction (J(NiW) = 27.1 and 28.5 cm(-1)) compared to the {Ni-Gd} interaction (J(NiGd) = 2.17 cm(-1)). The characteristic features for slow relaxation of the magnetization are observed for two Tb derivatives, but these are modulated by the crystal phase. Analysis of the frequency dependence of the alternating current susceptibility data yielded U(eff)/k(B) = 15.3 K and tau(0) = 4.5 x 10(-7) s for one derivative whereas no maxima of chi(M)'' appear above 2 K for the second one.

  12. Low-temperature superstructures of a series of Cd6M (M = Ca, Y, Sr, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) crystalline approximants.

    PubMed

    Nishimoto, Kazue; Sato, Takeru; Tamura, Ryuji

    2013-06-12

    The low-temperature (LT) superstructure and the phase transition temperature have been investigated for a series of Cd6M crystalline approximants by transmission electron microscopy as well as electrical resistivity measurements. Except for M = Lu, Cd6M is found to undergo a phase transition to a monoclinic phase at a low temperature and the transition temperature (Tc) scales well with the size of the M atom. For M = Ca, Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm the LT superstructure is explained by a √2a × a × √2a lattice with the space group C2/c, and for M = Sr and Yb a √2a × 2a × √2a monoclinic lattice with P2/m. On the other hand, no phase transition is observed for M = Lu, indicating that a Cd4 tetrahedron at the cluster center remains disordered down to the lowest temperature, i.e. 16 K. It is shown that the volume inside the Cd20 dodecahedron plays a crucial role in the occurrence of the phase transition, and long-term aging in particular promotes the phase transition for late rare-earth elements such as Ho, Er and Tm, suggesting that the transition is sensitive to and is even hindered by disorder such as atomic vacancies. The absence of the transition for M = Lu is attributed to the highest activation energy for the transition due to the smallest volume inside the Cd20 dodecahedron.

  13. CeNi3-type rare earth compounds: crystal structure of R3Co7Al2 (R=Y, Gd-Tm) and magnetic properties of {Gd-Er}3Co7Al2, {Tb, Dy}3Ni8Si and Dy3Co7.68Si1.32

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Yapaskurt, V. O.; Nirmala, R.; Quezado, S.; Malik, S. K.

    2017-03-01

    The crystal structure of new CeNi3-type {Y, Gd-Tm}3Co7Al2 (P63/mmc. N 194, hP24) compounds has been established using powder X-ray diffraction studies. The magnetism of Tb3Ni8Si and Dy3Ni8Si is dominated by rare earth sublattice and the magnetic properties of R3Co7Al2 (R =Gd-Er) and Dy3Co7.68Si1.32 are determined by both rare earth and cobalt sublattices. Magnetization data indicate ferromagnetic ordering of {Tb, Dy}3Ni8Si at 32 K and 21 K, respectively. Gd3Co7Al2 and Tb3Co7Al2 exhibit ferromagnetic ordering at 309 K and 209 K, respectively, whereas Dy3Co7Al2, Ho3Co7Al2, Er3Co7Al2 and Dy3Co7.68Si1.32 show a field dependent ferromagnetic-like ordering at 166 K, 124 K, 84 K and 226 K, respectively followed by a low temperature transition at 34 K for Dy3Co7Al2, 18 K for Ho3Co7Al2, 56 K for Er3Co7Al2, 155 K and 42 K for Dy3Co7.68Si1.32. Among these compounds, Dy3Ni8Si shows largest magnetocaloric effect (isothermal magnetic entropy change) of -11.6 J/kg·K at 18 K in field change of 50 kOe, whereas Tb3Co7Al2, Dy3Co7Al2 and Dy3Co7.68Si1.32 exhibit best permanent magnet properties in the temperature range of 2-5 K with remanent magnetization of 11.95 μB/fu, 12.86 μB/fu and 14.4 μB/fu, respectively and coercive field of 3.0 kOe, 1.9 kOe and 4.4 kOe, respectively.

  14. Low-temperature superstructures of a series of Cd6M (M = Ca, Y, Sr, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) crystalline approximants

    NASA Astrophysics Data System (ADS)

    Nishimoto, Kazue; Sato, Takeru; Tamura, Ryuji

    2013-06-01

    The low-temperature (LT) superstructure and the phase transition temperature have been investigated for a series of Cd6M crystalline approximants by transmission electron microscopy as well as electrical resistivity measurements. Except for M = Lu, Cd6M is found to undergo a phase transition to a monoclinic phase at a low temperature and the transition temperature (Tc) scales well with the size of the M atom. For M = Ca, Y, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm the LT superstructure is explained by a \\sqrt{2}a\\times a\\times \\sqrt{2}a lattice with the space group C2/c, and for M = Sr and Yb a \\sqrt{2}a\\times 2 a\\times \\sqrt{2}a monoclinic lattice with P2/m. On the other hand, no phase transition is observed for M = Lu, indicating that a Cd4 tetrahedron at the cluster center remains disordered down to the lowest temperature, i.e. 16 K. It is shown that the volume inside the Cd20 dodecahedron plays a crucial role in the occurrence of the phase transition, and long-term aging in particular promotes the phase transition for late rare-earth elements such as Ho, Er and Tm, suggesting that the transition is sensitive to and is even hindered by disorder such as atomic vacancies. The absence of the transition for M = Lu is attributed to the highest activation energy for the transition due to the smallest volume inside the Cd20 dodecahedron.

  15. Synthesis, structure and properties of the oxychalcogenide series A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd, Tb, Dy, Ho, Er and Y)

    SciTech Connect

    Tuxworth, A.J.; Evans, J.S.O.

    2014-02-15

    Seven oxyselenide materials have been synthesised with composition A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd–Er, Y) via solid state reactions of A{sub 2}O{sub 3}, TiSe{sub 2} and Se at 900 °C. They are all isostructural with Gd{sub 4}O{sub 4}TiSe{sub 4}. Structures have been refined from powder X-ray diffraction data and have monoclinic C2/m symmetry with unit cell parameters of a≈15.7 Å, b≈3.75 Å, c≈9.65 Å and β≈117.5°. They contain infinite ribbons of edge-sharing A{sub 4}O and A{sub 3}TiO tetrahedra 4 units wide, which are linked by chains of TiSe{sub 4}O{sub 2} edge-sharing octahedra. Compositions A=Gd–Ho, Y are semiconductors with conductivities 1–3 Sm{sup −1} at 300 K, with electronic band gaps of between 0.25 and 0.37 eV. Magnetic susceptibility is reported from 1.8 K to 300 K for compositions A=Gd–Ho. Rare earth moments appear to order antiferromagnetically at low temperatures with Gd and Tb showing evidence of ferromagnetism due to spin canting over a narrow temperature range close to T{sub N}. - Graphical abstract: Illustration of the A{sub 4}O{sub 4}TiSe{sub 4} crystal structure (C2/m symmetry), A{sub 4}O and A{sub 3}TiO edge sharing tetrahedral ribbons in red, chains of edge-sharing TiSe{sub 4}O{sub 2} in blue. Rare earth=green, titanium=blue, selenium=yellow, and oxygen=red. Display Omitted - Highlights: • Seven materials with A{sub 4}O{sub 4}TiSe{sub 4} (A=Sm, Gd–Er, Y) have been synthesised as bulk phases for the first time. • Materials are semiconductors and order antiferromagnetically at ∼4 K. • Structure contains M{sub 4}O tetrahedral ribbons and TiSe{sub 4}O{sub 2} 1D octahedral chains.

  16. Cross sections of proton-induced reactions on 152Gd, 155Gd and 159Tb with emphasis on the production of selected Tb radionuclides

    NASA Astrophysics Data System (ADS)

    Steyn, G. F.; Vermeulen, C.; Szelecsényi, F.; Kovács, Z.; Hohn, A.; van der Meulen, N. P.; Schibli, R.; van der Walt, T. N.

    2014-01-01

    Cross sections are presented for various Dy, Tb and Gd radionuclides produced in the proton bombardment of 159Tb as well as for the reactions 152Gd(p,4n)149Tb and 155Gd(p,4n)152Tb up to 66 MeV. The experimental excitation functions are compared with theoretical predictions by means of the geometry-dependent hybrid (GDH) model as implemented in the code ALICE/ASH, as well as with values from the TENDL-2012 library and previous literature experimental data, where available. Physical yields have been derived for the production of some of the medically important radioterbiums, namely 149Tb (radionuclide therapy), 152Tb (PET) and 155Tb (SPECT). The indirect production of high-purity 155Tb via the decay of its precursor 155Dy is reported. The possibility of a large-scale production facility based on a commercial 70 MeV cyclotron is also discussed.

  17. Perpendicular Magnetic Anisotropy of Tb/Fe and Gd/Fe Multilayers Studied with Torque Magnetometer

    NASA Astrophysics Data System (ADS)

    Chowdhury, Ataur

    Perpendicular magnetic anisotropy (PMA) of multilayers critically depend on the magnetic and structural ordering of the interface. To study the effect of interface on PMA, Tb/Fe and Gd/Fe multilayers with varying Fe (0.8-9.0 nm) and Gd (0.5-2.8 nm) or Tb (0.3-6.3 nm) layer thicknesses were fabricated by planar magnetron sputtering. The magnetometer results of spin orientation clearly reveals that samples with Gd or Tb layer thickness of more than 1.2 nm display no PMA, regardless of the Fe layer thickness. Tb/Fe and Gd/Fe multilayers with thin (<1.2 nm) Tb or Gd layers display large PMA, but no PMA is observed when the Fe layer thickness is increased to 4.0 nm and higher. The bulk magnetization and anisotropy energy constant of the samples are found to increase with increasing Fe layer thickness. Torque measurement also reveals that there are two distinctly different axes of spin alignment at different energy. Tb/Fe and Gd/Fe multilayers with similar composition reveal similar magnetic and structural characteristics, and it may imply that single-ion-anisotropy of rare-earth element, which is quite large for Tb ions and very small for Gd ions, may not be the dominating cause of PMA in Td/Fe and Gd/Fe multilayers. A detailed explanation of the results will be provided based on exchange interaction at the interface.

  18. Preparation and luminescent properties of GdOF:Ce, Tb nanoparticles and their transparent PMMA nanocomposites

    NASA Astrophysics Data System (ADS)

    Cai, Wen; Wang, Aiwu; Fu, Li; Hu, Jie; Rao, Tingke; Wang, Junqing; Zhong, Jiasong; Xiang, Weidong

    2015-05-01

    GdOF:Ce, Tb nanoparticles and their poly (methyl methacrylate) (PMMA) nanocomposites have been successfully prepared by a thermolysis route and thermal polymerization of methyl methacrylate (MMA) monomer, respectively. The obtained nanoparticles and nanocomposites are characterized by XRD, EDS, TEM, FTIR, TGA, UV-Vis and PL spectrum. The as-synthesized transparent GdOF:Ce, Tb/PMMA nanocomposites exhibit green photoluminescence under the irradiation of 254 nm UV lamp due to the incorporation of luminescent GdOF:Ce, Tb nanoparticles into the PMMA matrix. The present route would provide a general strategy to prepare other functional nanocomposites.

  19. Enhance the Er3+ Upconversion Luminescence by Constructing NaGdF4:Er3+@NaGdF4:Er3+ Active-Core/Active-Shell Nanocrystals

    NASA Astrophysics Data System (ADS)

    Du, Xiaoyu; Wang, Xiangfu; Meng, Lan; Bu, Yanyan; Yan, Xiaohong

    2017-03-01

    NaGdF4:12%Er3+@NaGdF4: x%Er3+ ( x = 0, 6, 8, 10, and 12) active-core/active-shell nanoparticles (NPs) were peculiarly synthesized via a delayed nucleation pathway with procedures. The phase, shape, and size of the resulting core-shell NPs are confirmed by transmission electron microscopy and X-ray diffraction. Coated with a NaGdF4:10%Er3+ active shell around the NaGdF4:12%Er3+ core NPs, a maximum luminescent enhancement of about 336 times higher than the NaGdF4:12%Er3+ core-only NPs was observed under the 1540 nm excitation. The intensity ratio of green to red was adjusted through the construction of the core-shell structure and the change of Er3+ concentration in the shell. By analyzing the lifetimes of emission bands and exploring the energy transition mechanism, the giant luminescence enhancement is mainly attributed to the significant increase in the near-infrared absorption at 1540 nm and efficient energy migration from the shell to core.

  20. Enhance the Er(3+) Upconversion Luminescence by Constructing NaGdF4:Er(3+)@NaGdF4:Er(3+) Active-Core/Active-Shell Nanocrystals.

    PubMed

    Du, Xiaoyu; Wang, Xiangfu; Meng, Lan; Bu, Yanyan; Yan, Xiaohong

    2017-12-01

    NaGdF4:12%Er(3+)@NaGdF4:x%Er(3+) (x = 0, 6, 8, 10, and 12) active-core/active-shell nanoparticles (NPs) were peculiarly synthesized via a delayed nucleation pathway with procedures. The phase, shape, and size of the resulting core-shell NPs are confirmed by transmission electron microscopy and X-ray diffraction. Coated with a NaGdF4:10%Er(3+) active shell around the NaGdF4:12%Er(3+) core NPs, a maximum luminescent enhancement of about 336 times higher than the NaGdF4:12%Er(3+) core-only NPs was observed under the 1540 nm excitation. The intensity ratio of green to red was adjusted through the construction of the core-shell structure and the change of Er(3+) concentration in the shell. By analyzing the lifetimes of emission bands and exploring the energy transition mechanism, the giant luminescence enhancement is mainly attributed to the significant increase in the near-infrared absorption at 1540 nm and efficient energy migration from the shell to core.

  1. Visible quantum cutting through downconversion in GdPO{sub 4}:Tb{sup 3+} and Sr{sub 3}Gd(PO{sub 4}){sub 3}:Tb{sup 3+}

    SciTech Connect

    Wang Deyin; Kodama, Nobuhiro

    2009-08-15

    Visible quantum cutting has been observed in GdPO{sub 4}:Tb{sup 3+} upon Tb{sup 3+} 4f{sup 8}-4f{sup 7}5d{sup 1} excitation and host excitation, and in Sr{sub 3}Gd(PO{sub 4}){sub 3}:Tb{sup 3+} upon Tb{sup 3+} 4f{sup 8}-4f{sup 7}5d{sup 1} excitation. In the quantum cutting process, Tb{sup 3+} acts as a quantum cutter, which converts one short wavelength ultraviolet photon or one vacuum ultraviolet photon into more than one visible photon. The quantum cutting involves a cross-relaxation process between two neighboring Tb{sup 3+} and direct energy transfer between Tb{sup 3+} and Tb{sup 3+} or Tb{sup 3+} and Gd{sup 3+}, depending on the excitation wavelength. The quantum efficiency variation of GdPO{sub 4}:xTb{sup 3+} and Sr{sub 3}Gd(PO{sub 4}){sub 3}:xTb{sup 3+} shows a growing trend with increasing of Tb{sup 3+} content from x=1.5% to 13%. - Graphical abstract: The ratio of emission from {sup 5}D{sub 4} level to that attributed to {sup 5}D{sub 3} of Tb{sup 3+} and {sup 6}P{sub J} of Gd{sup 3+} under 210,196 and 157 nm excitations are much stronger than that under 273 nm excitation, indicating visible quantum cutting has occurred in GdPO{sub 4}:Tb{sup 3+} upon Tb{sup 3+} 4f{sup 8}-4f{sup 7}5d{sup 1} excitation and host excitation.

  2. Photoluminescence and energy transfer process in Gd2O3:Eu3+, Tb3+

    NASA Astrophysics Data System (ADS)

    Selvalakshmi, T.; Bose, A. Chandra

    2016-05-01

    Variation in photoluminescence (PL) properties of Eu3+ and Tb3+ as a function of co-dopant (Tb3+) concentration are studied for Gd2-x-yO3: Eu3+x Tb3+y (x = 0.02, y = 0.01, 0.03, 0.05). The crystal structure analysis is carried out by X-ray Diffraction (XRD). Absence of addition peaks corresponding europium or terbium phase confirms the phase purity. Diffuse reflectance spectroscopy (DRS) reveals the absorption peaks corresponding to host matrix, Eu3+ and Tb3+. The bandgap calculated from Kubelka - Munk function is also reported. PL spectra are recorded at the excitation wavelength of 307 nm and the emission peak corresponding to Eu3+ confirms the energy transfer from Tb3+ to Eu3+. The agglomeration of particles acts as quenching centres for energy transfer at higher concentrations.

  3. Anion disorder in lanthanoid zirconates Gd(2-x)Tb(x)Zr2O7.

    PubMed

    Reynolds, Emily; Blanchard, Peter E R; Kennedy, Brendan J; Ling, Chris D; Liu, Samuel; Avdeev, Max; Zhang, Zhaoming; Cuello, Gabriel J; Tadich, Anton; Jang, Ling-Yun

    2013-08-05

    The pyrochlore-defect fluorite order-disorder transition has been studied for a series of oxides of the type Gd(2-x)Tb(x)Zr2O7 by a combination of diffraction and spectroscopy techniques. Synchrotron X-ray diffraction data suggest an abrupt transition from the coexistence of pyrochlore and defect fluorite phases to a single defect fluorite phase with increasing Tb content. However neutron diffraction data, obtained at λ ≈ 0.497 Å for all Gd-containing samples to minimize absorption, not only provide evidence for independent ordering of the anion and cation sublattices but also suggest that the disorder transition across the pyrochlore-defect fluorite boundary of Ln2Zr2O7 is rather gradual. Such disorder was also evident in X-ray absorption measurements at the Zr L3-edge, which showed a gradual increase in the effective coordination number of the Zr from near 6-coordinate in the pyrochlore rich samples to near 7-coordinate in the Tb rich defect fluorites. These results indicate the presence of ordered domains throughout the defect fluorite region, and demonstrate the gradual nature of the order-disorder transition across the Gd(2-x)Tb(x)Zr2O7 series.

  4. Supporting clinical management of the difficult-to-treat TB cases: the ERS-WHO TB Consilium.

    PubMed

    D'Ambrosio, Lia; Tadolini, Marina; Centis, Rosella; Duarte, Raquel; Sotgiu, Giovanni; Aliberti, Stefano; Dara, Masoud; Migliori, Giovanni Battista

    2015-03-01

    Multi-drug and extensively drug-resistant tuberculosis (MDR/XDR-TB) are considered a serious threat for TB control and elimination. The outcome of these patients is still largely unsatisfactory as of today, with treatment success rates being consistently below 50% at global level. The World Health Organization (WHO) recommends that management of MDR-TB cases is supported by a specialized team, including complementary medical professionals able to cover several perspectives (clinical, both for adults and children; surgical; radiological; public health; psychological; nursing, among others). Implementation of such a body (known as Consilium in most of the former Soviet Union countries) is often a pre-requisite to apply for international TB control funding and concessionally priced medicines to treat M/XDR-TB cases. The primary objective of the ERS/WHO TB Consilium is to provide clinical consultation for drug-resistant TB and other difficult-to-treat TB cases, including co-infection with HIV and paediatric cases. Through technical guidance to clinicians managing complex TB cases, the main contribution and outcome of the initiative will be a public health response aimed at achieving correct treatment of affected patients and preventing further development of drug resistance. The Consilum's secondary objective is to ensure monitoring and evaluation of clinical practices on the ground (diagnosis, treatment and prevention).

  5. Recombination luminescence of CaSO4:Tb3+ and CaSO4:Gd3+phosphors

    NASA Astrophysics Data System (ADS)

    Kudryavtseva, Irina; Lushchik, Aleksandr; Maaroos, Aarne; Azmaganbetova, Zhannur; Nurakhmetov, Turlybek; Salikhoja, Zhussupbek

    2012-08-01

    A comparative study of the excitation of luminescence by VUV radiation as well as of thermally and photostimulated luminescence has been carried out for CaSO4:Tb3+ and CaSO4:Gd3+ phosphors, where Na+ or F- ions are used for charge compensation. The distinction in hole processes for the phosphors with Na+ or F- compensators is determined by the differing thermal stability of the holes localized at/near Tb3+Na+ and Gd3+Na+ (up to 100-160 K) or at/near Tb3+F- V Ca and Gd3+F- V Ca centers involving also a cation vacancy (up to 400-550 K). Tunnel luminescence in the pairs of localized electrons and holes nearby Tb3+ or Gd3+ has been detected. The mechanisms of electron-hole, hole-electron and tunnel recombination luminescence as well as a subsequent released energy transfer to RE3+ ions are considered.

  6. Ultraviolet upconversion fluorescence of Er3+ in Yb3+/Er3+-codoped Gd2O3 nanotubes.

    PubMed

    Zheng, Kezhi; Zhao, Dan; Zhang, Daisheng; Liu, Zhenyu; Qin, Weiping

    2011-11-01

    Under 980 nm excitation, room-temperature ultraviolet (UV) upconversion (UC) emissions of Er3+ from the 4G(9/2), 2K(13/2), and 2P(3/2) states were observed in Gd2O3:Yb3+/Er3+ nanotubes, which were synthesized via a simple wet-chemical route at low temperature and ambient pressure followed by a subsequent heat treatment at 800 degrees C. The experimental results exhibited that these UV emissions came from four-photon UC processes. In the Gd2O3:Yb3+/Er3+ nanocrystals, the energy transfers (ETs) from Yb3+ to Er3+ played important roles in populating the high-energy states of Er3+ ions. This material provides a possible candidate for building UV compact solid-state lasers or fiber lasers.

  7. Phase transformations and indications for acoustic mode softening in Tb-Gd orthophosphate

    DOE PAGES

    Tschauner, Oliver; Ushakov, Sergey V.; Navrotsky, Alexandra; ...

    2016-01-06

    At ambient conditions the anhydrous rare-earth orthophosphates assume either the xenotime (zircon) or the monazite structure, with the latter favored for the heavier rare earths. Tb0.5Gd0.5PO4 assumes the xenotime structure at ambient conditions but is at the border between the xenotime and monazite structures. Here we show that, at high pressure, Tb0.5Gd0.5PO4 does not transform directly to monazite but through an intermediate anhydrite-type structure. We show softening of (c1133 + c1313) combined elastic moduli close to the transition from the anhydrite to the monazite structure. Stress response of rare-earth orthophosphate ceramics can be affected by both formation of the anhydrite-typemore » phase and the elastic softening in the vicinity of the monazite-phase. In conclusion, we report the first structural data for an anhydrite-type rare earth orthophosphate.« less

  8. Fabrication of isolated CoGdTb magnetic nanodots with perpendicular magnetic anisotropy.

    PubMed

    Nam, Chunghee

    2013-03-01

    The authors report that a closely-packed hybrid nanostructure can be fabricated by using simple sputtering deposition and anodized aluminum oxide (AAO) templates. In order to isolate CoGdTb magnetic materials with the AAO template, carbon nanotubes (CNTs) were incorporated into the AAO template. Scanning electron microscopy reveals that the nanodots are formed exactly on the top of CNTs, which are placed in a regular arrangement over a wide range area. This indicates that magnetic nanodots, well-arranged over a large area, can be formed using simple sputtering deposition. Isothermal magnetization shows that the CoGdTb nanodots have perpendicular magnetic anisotropy and the strength of the dipolar interaction between the magnetic nanodots can be also controlled by adjusting the spacing between the dots.

  9. BaGdF5:Dy(3+),Tb(3+),Eu(3+) multifunctional nanospheres: paramagnetic, luminescence, energy transfer, and tunable color.

    PubMed

    Guan, Hongxia; Song, Yanhua; Zheng, Keyan; Sheng, Ye; Zou, Haifeng

    2016-05-18

    A series of Dy(3+),Tb(3+) and Eu(3+) singly, doubly or triply doped BaGdF5 phosphors were synthesized by a one-step hydrothermal method with l-arginine, and their energy transfer, migrations and multicolored luminescence properties were investigated in detail. The as-prepared Dy(3+),Tb(3+) or Eu(3+) doped samples showed strong blue, green and red emission, respectively. Different hues of green and red light were obtained by co-doped Dy(3+),Tb(3+) and Tb(3+),Eu(3+) in the BaGdF5 host, respectively. More significantly, in the Dy(3+),Tb(3+),Eu(3+) tri-doped BaGdF5 phosphors, colors changed from yellow green to orange red by adjusting the doping concentration of Eu(3+). Energy migrations from Dy(3+) to Tb(3+) and from Tb(3+) to Eu(3+) are reported in detail. Furthermore, the obtained samples exhibit paramagnetic properties at room temperature and low temperature. It is obvious that these Dy(3+), Tb(3+), Eu(3+) singly or doubly or triply doped BaGdF5 nanomaterials with tunable multicolored luminescence properties may have potential applications in the fields of full-color displays, biological labels and bio-separation.

  10. The normal and inverse magnetocaloric effect in RCu2 (R=Tb, Dy, Ho, Er) compounds

    NASA Astrophysics Data System (ADS)

    Zheng, X. Q.; Xu, Z. Y.; Zhang, B.; Hu, F. X.; Shen, B. G.

    2017-01-01

    Orthorhombic polycrystalline RCu2 (R=Tb, Dy, Ho and Er) compounds were synthesized and the magnetic properties and magnetocaloric effect (MCE) were investigated in detail. All of the RCu2 compounds are antiferromagnetic (AFM) ordered. As temperature increases, RCu2 compounds undergo an AFM to AFM transition at Tt and an AFM to paramagnetic (PM) transition at TN. Besides of the normal MCE around TN, large inverse MCE around Tt was found in TbCu2 compound. Under a field change of 0-7 T, the maximal value of inverse MCE is even larger than the value of normal MCE around TN for TbCu2 compound. Considering of the normal and inverse MCE, TbCu2 shows the largest refrigerant capacity among the RCu2 (R=Tb, Dy, Ho and Er) compounds indicating its potential applications in low temperature multistage refrigeration.

  11. Magnetooptics of the luminescent transitions in Tb3+:Gd3Ga5O12

    NASA Astrophysics Data System (ADS)

    Valiev, Uygun V.; Gruber, John B.; Ivanov, Igor'A.; Burdick, Gary W.; Liang, Hongbin; Zhou, Lei; Fu, Dejun; Pelenovich, Oleg V.; Pelenovich, Vasiliy O.; Lin, Zhou

    2015-08-01

    The spectra of the luminescence and magnetic circular polarization of luminescence in terbium-gadolinium gallium garnet Tb3+:Gd3Ga5O12 (Tb3+:GGG) were studied within the visible spectral range at temperatures T = 90 and 300 K in an external magnetic field of 0.45 T. The Zeeman effect in the luminescence "green" band associated with 4f → 4f transition 5D4 → 7F5 of Tb3+:GGG was also studied at T = 90 K in an external field of 0.55 T. Measurement of the Zeeman effect in Tb3+:GGG carried out for some doublet lines of the luminescence band 5D4 → 7F5 at T = 90 K shows that a magnetooptical effect of the intensity change of the emitted light is observed on these lines, in contrast to pure Zeeman splitting of the emission lines measured in the luminescence band 5D4 → 7F6. For the systems we have studied, the maximal value of the magnetooptical effect of the intensity change of the luminescence line at low temperatures has been achieved in paramagnetic garnet Tb0.2Y2.8Al5O12 at comparatively low magnetic fields.

  12. Multiple charge density wave transitions in the antiferromagnets R NiC2 (R =Gd ,Tb)

    NASA Astrophysics Data System (ADS)

    Shimomura, S.; Hayashi, C.; Hanasaki, N.; Ohnuma, K.; Kobayashi, Y.; Nakao, H.; Mizumaki, M.; Onodera, H.

    2016-04-01

    X-ray scattering and electrical resistivity measurements were performed on GdNiC2 and TbNiC2. We found a set of satellite peaks characterized by q1=(0.5 ,η ,0 ) below T1, at which the resistivity shows a sharp inflection, suggesting the charge density wave (CDW) formation. The value of η decreases with decreasing temperature below T1, and then a transition to a commensurate phase with q1 C=(0.5 ,0.5 ,0 ) takes place. The diffuse scattering observed above T1 indicates the presence of soft phonon modes associated with CDW instabilities at q1 and q2=(0.5 ,0.5 ,0.5 ) . The long-range order given by q2 is developed in addition to that given by q1 C in TbNiC2, while the short-range correlation with q2 persists even at 6 K in GdNiC2. The amplitude of the q1 C lattice modulation is anomalously reduced below an antiferromagnetic transition temperature TN in GdNiC2. In contrast, the q2 order vanishes below TN in TbNiC2. We demonstrate that R NiC2 (R = rare earth) compounds exhibit similarities with respect to their CDW phenomena, and discuss the effects of magnetic transitions on CDWs. We offer a possible displacement pattern of the modulated structure characterized by q1 C and q2 in terms of frustration.

  13. Synthesis and characterization of nanocrystalline Gd and Tb co-doped ceria-based electrolyte materials for IT-SOFC.

    PubMed

    Choi, J W; Saradha, T; Heo, M H; Park, K

    2010-05-01

    Gd and Tb co-doped Ce0.8Gd0.2-xTb(x)O2-delta (0 < or = x < or = 0.09) nanopowders were synthesized by the combustion method using aspartic acid as fuel. The calcined powders formed a ceria-based single phase with a cubic fluorite structure. In addition, the powders were pure, homogeneous, and nanocrystalline nature, i.e., 20.1-23.4 nm in the calculated crystallite size. The partial incorporation of Tb for Gd caused a decrease in the average grain size of the sintered bodies. The high-quality nanosized Ce0.8Gd0.17Tb0.03O2-delta powders provided a high density, ultra-fine grain size, and high electrical conductivity even at the low sintering temperature of 1300 degrees C. The grain size and density of the Ce0.8Gd0.17Tb0.03O2-delta were approximately 146 nm and approximately 99% of the theoretical density, respectively, allowing enhanced electrical conductivity (0.106 Scm(-1) at 800 degrees C).

  14. Influence of Tb on easy magnetization direction and magnetostriction of ferromagnetic Laves phase GdFe2 compounds

    NASA Astrophysics Data System (ADS)

    Murtaza, Adil; Yang, Sen; Zhou, Chao; Song, Xiaoping

    2016-09-01

    The crystal structure, magnetization, and spontaneous magnetostriction of ferromagnetic Laves phase GdFe2 compound have been investigated. High resolution synchrotron x-ray diffraction (XRD) analysis shows that GdFe2 has a lower cubic symmetry with easy magnetization direction (EMD) along [100] below Curie temperature TC. The replacement of Gd with a small amount of Tb changes the EMD to [111]. The Curie temperature decreases while the field dependence of the saturation magnetization (Ms) measured in temperature range 5-300 K varies with increasing Tb concentration. Coercivity Hc increases with increasing Tb concentration and decays exponentially as temperature increases. The anisotropy in GdFe2 is so weak that some of the rare-earth substitution plays an important role in determining the easy direction of magnetization in GdFe2. The calculated magnetostrictive constant λ100 shows a small value of 37×10-6. This value agrees well with experimental data 30×10-6. Under a relatively small magnetic field, GdFe2 exhibits a V-shaped positive magnetostriction curve. When the field is further increased, the crystal exhibits a negative magnetostriction curve. This phenomenon has been discussed in term of magnetic domain switching. Furthermore, magnetostriction increases with increasing Tb concentration. Our work leads to a simple and unified mesoscopic explanation for magnetostriction in ferromagnets. It may also provide insight for developing novel functional materials. Project supported by the National Basic Research Program of China (Grant No. 2012CB619401).

  15. Phase transformations and indications for acoustic mode softening in Tb-Gd orthophosphate

    SciTech Connect

    Tschauner, Oliver; Ushakov, Sergey V.; Navrotsky, Alexandra; Boatner, Lynn A.

    2016-01-06

    At ambient conditions the anhydrous rare-earth orthophosphates assume either the xenotime (zircon) or the monazite structure, with the latter favored for the heavier rare earths. Tb0.5Gd0.5PO4 assumes the xenotime structure at ambient conditions but is at the border between the xenotime and monazite structures. Here we show that, at high pressure, Tb0.5Gd0.5PO4 does not transform directly to monazite but through an intermediate anhydrite-type structure. We show softening of (c1133 + c1313) combined elastic moduli close to the transition from the anhydrite to the monazite structure. Stress response of rare-earth orthophosphate ceramics can be affected by both formation of the anhydrite-type phase and the elastic softening in the vicinity of the monazite-phase. In conclusion, we report the first structural data for an anhydrite-type rare earth orthophosphate.

  16. Phase transformations and indications for acoustic mode softening in Tb-Gd orthophosphate

    NASA Astrophysics Data System (ADS)

    Tschauner, O.; Ushakov, S. V.; Navrotsky, A.; Boatner, L. A.

    2016-01-01

    At ambient conditions the anhydrous rare earth orthophosphates assume either the xenotime (zircon) or the monazite structure, with the latter favored for the heavier rare earths and by increasing pressure. Tb0.5Gd0.5PO4 assumes the xenotime structure at ambient conditions but is at the border between the xenotime and monazite structures. Here we show that, at high pressure, Tb0.5Gd0.5PO4 does not transform directly to monazite but through an intermediate anhydrite-type structure. Axial deformation of the unit cell near the anhydrite- to monazite-type transition indicates softening of the (c1133  +  c1313) combined elastic moduli. Stress response of rare-earth orthophosphate ceramics can be affected by both formation of the anhydrite-type phase and the elastic softening in the vicinity of the monazite-phase. We report the first structural data for an anhydrite-type rare earth orthophosphate.

  17. Complex magnetism of Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Lužnik, J.; Koželj, P.; Vrtnik, S.; Jelen, A.; Jagličić, Z.; Meden, A.; Feuerbacher, M.; Dolinšek, J.

    2015-12-01

    Rare earth based equimolar Ho-Dy-Y-Gd-Tb hexagonal high-entropy alloy (HEA) is a prototype of an ideal HEA, stabilized by the entropy of mixing at any temperature with random mixing of elements on the hexagonal close-packed lattice. In order to determine intrinsic properties of an ideal HEA characterized by the enormous chemical (substitutional) disorder on a weakly distorted simple lattice, we have performed measurements of its magnetic and electrical response and the specific heat. The results show that the Ho-Dy-Y-Gd-Tb hexagonal HEA exhibits a rich and complex magnetic field-temperature (H ,T ) phase diagram, as a result of competition among the periodic potential arising from the electronic band structure that favors periodic magnetic ordering, the disorder-induced local random potential that favors spin glass-type spin freezing in random directions, the Zeeman interaction with the external field that favors spin alignment along the field direction, and the thermal agitation that opposes any spin ordering. Three characteristic temperature regions were identified in the (H ,T ) phase diagram between room temperature and 2 K. Within the upper temperature region I (roughly between 300 and 75 K), thermal fluctuations average out the effect of local random pinning potential and the spin system behaves as a pure system of compositionally averaged spins, undergoing a thermodynamic phase transition to a long-range ordered helical antiferromagnetic state at the Néel temperature TN=180 K that is a compositional average of the Néel temperatures of pure Tb, Dy, and Ho metals. Region II (between 75 and 20 K) is an intermediate region where the long-range periodic spin order "melts" and the random ordering of spins in the local random potential starts to prevail. Within the low-temperature region III (below 20 K), the spins gradually freeze in a spin glass configuration. The spin glass phase appears to be specific to the rare earths containing hexagonal HEAs, sharing

  18. X-ray excited photoluminescence near the giant resonance in solid-solution Gd(1-x)Tb(x)OCl nanocrystals and their retention upon solvothermal topotactic transformation to Gd(1-x)Tb(x)F3.

    PubMed

    Waetzig, Gregory R; Horrocks, Gregory A; Jude, Joshua W; Zuin, Lucia; Banerjee, Sarbajit

    2016-01-14

    Design rules for X-ray phosphors are much less established as compared to their optically stimulated counterparts owing to the absence of a detailed understanding of sensitization mechanisms, activation pathways and recombination channels upon high-energy excitation. Here, we demonstrate a pronounced modulation of the X-ray excited photoluminescence of Tb(3+) centers upon excitation in proximity to the giant resonance of the host Gd(3+) ions in solid-solution Gd1-xTbxOCl nanocrystals prepared by a non-hydrolytic cross-coupling method. The strong suppression of X-ray excited optical luminescence at the giant resonance suggests a change in mechanism from multiple exciton generation to single thermal exciton formation and Auger decay processes. The solid-solution Gd1-xTbxOCl nanocrystals are further topotactically transformed with retention of a nine-coordinated cation environment to solid-solution Gd1-xTbxF3 nanocrystals upon solvothermal treatment with XeF2. The metastable hexagonal phase of GdF3 can be stabilized at room temperature through this topotactic approach and is transformed subsequently to the orthorhombic phase. The fluoride nanocrystals indicate an analogous but blue-shifted modulation of the X-ray excited optical luminescence of the Tb(3+) centers upon X-ray excitation near the giant resonance of the host Gd(3+) ions.

  19. Photoluminescent properties of Tb3+ doped GdSrAl3O7 nanophosphor using solution combustions synthesis

    NASA Astrophysics Data System (ADS)

    Khatkar, Satyender Pal; Singh, Sonika; Lohra, Sheetal; Khatkar, Avni; Taxak, Vinod

    2015-05-01

    A color tunable terbium doped GdSrAl3O7 nanophosphor has been synthesized at low temperature using solution combustion synthesis. The photoluminescent properties of nanophosphors have been explored by analyzing their excitation and emission spectra alongwith their decay curves. The emission spectra exhibit dominating green light at 544 nm due to 5D4→7F5 transition of Tb3+ ions in GdSrAl3O7 on excitation by UV light of 239 nm. Furthermore, the luminescence in Gd( 1- x)SrAl3O7: xTb3+nanophosphors shifted from blue to green color by properly tuning the concentration of terbium ions. Decay curves indicate that non-radiative cross-relaxation is primarily responsible for concentration quenching phenomenon in the GdSrAl3O7 host. X-ray diffraction (XRD) analysis confirmed that single tetragonal phased nanophosphor could be readily obtained at low temperature 550°C. The smooth surfaced nanocrystals with particle size of 45 - 50 nm have also been examined by transmission electron microscopy (TEM). All these features augmented the probability of GdSrAl3O7: Tb3+ nanophosphor for potential applications in optical devices. [Figure not available: see fulltext.

  20. Luminescence, Energy Transfer and Tunable Color of Ce3+- and Tb3+-Activated Na3Gd(BO3)2 Phosphors

    NASA Astrophysics Data System (ADS)

    Zhang, Xinguo; Pan, Jialiang; Mo, Fuwang

    2017-02-01

    A series of blue Na3Gd(BO3)2:Ce3+ and blue-to-green color-tunable Na3Gd (BO3)2:Ce3+,Tb3+ phosphors were synthesized by the solid-state method. The luminescence, concentration quenching and energy transfer (ET) process of Na3Gd(BO3)2:Ce3+,Tb3+ were investigated. Both Ce3+ and Tb3+ occupy the Gd3+ site in the Na3Gd(BO3)2 host. Na3Gd(BO3)2:Ce3+ exhibits strong ultraviolet absorption and broadband blue emission. The Ce3+ sensitization effect on Tb3+ has been verified by the variation of PL/PLE spectra, the Ce3+ decay lifetimes and the energy transfer efficiency of Na3Gd(BO3)2:Ce3+,Tb3+ phosphors. The maximum Ce3+-Tb3+ ET efficiency has been calculated to be 95%. The emitting color of the obtained phosphors can be modulated from blue (0.179, 0.204) through bluish-green (0.271, 0.391) to green (0.349, 0.551) by properly changing the ratio of Ce3+/Tb3+.

  1. Synthesis and photoluminescence properties of multicolor tunable GdNbO4: Tb3+, Eu3+ phosphors based on energy transfer

    NASA Astrophysics Data System (ADS)

    Zhang, Lu; Yi, Shuangping; Hu, Xiaoxue; Liang, Boxin; Zhao, Weiren; Wang, Yinhai

    2017-03-01

    A color-tunable phosphor based on Tb3+/Eu3+ co-doped GdNbO4 were synthesized by a traditional solid-state reaction method. X-ray powder diffraction (XRD), diffuse reflectance spectra, photoluminescence spectra and decay curves were utilized to characterize the as-prepared phosphors. XRD result indicated that various concentrations Tb3+/Eu3+ single-doped and co-doped phosphors were well indexed to the pure GdNbO4 phase. The GdNbO4 host was proved to be a self-activated phosphor with broad absorption range from 200 nm to 325 nm. When Tb3+ ions were added into the host lattice, the energy transferring from host to Tb3+ was identified. And the broad absorption in the UV region was changed and enhanced. Therefore, we selected Tb3+ as the sensitizer ion, and adjusted red component from Eu3+ to control the emission color. The energy transfer from Tb3+ to Eu3+ was confirmed based on the luminescence spectra and decay curves. Furthermore, the energy transmission mechanism was deduced to be the dipole-quadrupole interaction. On the whole, the obtained GdNbO4, GdNbO4:Tb3+, and GdNbO4:Tb3+, Eu3+ phosphors may have potential application in the UV white-light-emitting diodes (w-LEDs) and display devices.

  2. Photoluminescence properties of phosphors based on Lu3+-stabilized Gd3Al5O12:Tb3+/Ce3+ garnet solid solutions

    NASA Astrophysics Data System (ADS)

    Li, Jinkai; Li, Ji-Guang; Li, Xiaodong; Sun, Xudong

    2016-12-01

    The Gd3Al5O12:Tb/Ce (GdAG:Tb/Ce) garnet solutions effectively stabilized by Lu3+ have been achieved by calcining their precursor at 1300 °C. Detailed characterizations are given to the materials in terms of XRD, FE-SEM, BET, PL/PLE, and fluorescence decay analysis. The occurrence of Gd3+ and Tb3+ transitions from the photoluminescence excitation spectrum monitoring the Ce3+ yellow emission strongly confirmed the efficient Gd3+ → Ce3+ and Tb3+ → Ce3+ energy transfer. The [(Gd0.8Lu0.2)0.99-xCe0.01Tbx]AG (x = 0-0.1) phosphors with good dispersion and uniform particle size exhibit various luminescent properties under different excitation wavelength of 275, 338, and 457 nm, respectively. The photoluminescence comparison indicated that owing to the Gd3+ → Ce3+ and Tb3+ → Ce3+ energy transfer, the best luminescent phosphor [(Gd0.8Lu0.2)0.89Ce0.01 Tb0.1]AG is almost identical to the well-known YAG:Ce, higher than LuAG:Ce in emission intensity, and has a substantially red-shifted emission band that is desired for warm-white lighting. The Tb3+ → Ce3+ energy transfer was suggested to be electric multipolar interactions, and the processes of energy migration among the optically active Gd3+, Tb3+, and Ce3+ ions were discussed in detail. Fluorescence decay analysis found the lifetime for the Ce3+ emission hardly changes with the Tb3+ incorporation. The [(Gd0.8Lu0.2)0.99-xCe0.01Tbx]AG garnets developed in this work may serve as a new type of phosphor that hopefully meets the requirements of various lighting, optical display, and scintillation applications.

  3. Energy transfer and tunable multicolor emission and paramagnetic properties of GdF3:Dy(3+),Tb(3+),Eu(3+) phosphors.

    PubMed

    Guan, Hongxia; Sheng, Ye; Xu, Chengyi; Dai, Yunzhi; Xie, Xiaoming; Zou, Haifeng

    2016-07-20

    A series of Dy(3+), Tb(3+), Eu(3+) singly or doubly or triply doped GdF3 phosphors were synthesized by a glutamic acid assisted one-step hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) spectroscopy. The results show that the synthesized samples are all pure GdF3. The obtained samples have a peanut-like morphology with a diameter of about 270 nm and a length of about 600 nm. Under UV excitation, GdF3:Dy(3+), GdF3:Tb(3+) and GdF3:Eu(3+) samples exhibit strong blue, green and red emissions, respectively. By adjusting their relative doping concentrations in the GdF3 host, the different color hues of green and red light are obtained by co-doped Dy(3+), Tb(3+) and Tb(3+), Eu(3+) ions in the GdF3 host, respectively. Besides, there exist two energy transfer pairs in the GdF3 host: (1) Dy(3+) → Tb(3+) and (2) Tb(3+) → Eu(3+). More significantly, in the Dy(3+), Tb(3+), and Eu(3+) tri-doped GdF3 phosphors, white light can also be achieved upon excitation of UV light by adjusting the doping concentration of Eu(3+). In addition, the obtained samples also exhibit paramagnetic properties at room temperature (300 K) and low temperature (2 K). It is obvious that multifunctional Dy(3+), Tb(3+), Eu(3+) tri-doped GdF3 materials including tunable multicolors and intrinsic paramagnetic properties may have potential applications in the field of full-color displays.

  4. Spectroscopic properties of transparent Er-doped oxyfluoride glass-ceramics with GdF₃.

    PubMed

    Środa, Marcin; Szlósarczyk, Krzysztof; Różański, Marek; Sitarz, Maciej; Jeleń, Piotr

    2015-01-05

    Optically active glass-ceramics (GC) with the low-phonon phases of fluorides, doped with Er(3+) was studied. Glass based on SiO₂-Al₂O₃-Na₂F₂-Na₂O-GdF₃-BaO system was obtained. Dopant were introduced to the glass in an amount of 0.01 mol Er₂O₃ per 1 mol of glass. DTA/DSC study shows multi-stage crystallization. XRD identification of obtained phases did not confirm the presence of pure GdF₃ phase. Instead of that ceramization process led to formation of NaGdF₄ and BaGdF₅. The structural changes were studied using FT-IR spectroscopic method. The study of luminescence of the samples confirmed that optical properties of the obtained GC depend on crystallizing phases during ceramization. Time resolved spectroscopy of Er-doped glass showed the 3 and 8 times increase of lifetime of emission from (4)S₃/₂ and (4)F₉/₂ states, respectively. It confirms the erbium ions have ability to locate in the low phonon gadolinium-based crystallites. The results give possibility to obtain a new material for optoelectronic application.

  5. Magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}3Co2Ge3 and {Tb, Ho}3Ni2Ge3 compounds

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Yapaskurt, V. O.; Nirmala, R.; Quezado, S.; Malik, S. K.; Mozharivskyj, Y.; Isnard, O.

    2017-02-01

    The magnetic ordering of Hf3Ni2Si3-type {Sm, Tb, Er}3Co2Ge3 and {Tb, Ho}3Ni2Ge3 compounds (space group Cmcm, oC32) was investigated via magnetization measurements and neutron diffraction study in a zero-applied field. {Sm, Tb, Er}3Co2Ge3 and Ho3Ni2Ge3 exhibit field sensitive complex antiferromagnetic orderings with TN=51 K, Tm=10 K for Sm3Co2Ge3, TN=34 K, Tm=13 K for Tb3Co2Ge3, TN=7 K for Er3Co2Ge3 and TN=11 K for Ho3Ni2Ge3. At 2 K and above the critical field of 5 kOe, 20 kOe, 4 kOe and 7 kOe for Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3, respectively, saturation magnetizations per rare-earth atom are 6.5 μB for Tb3Co2Ge3, 7.0 μB for Er3Co2Ge3 and 8.0 μB for Ho3Ni2Ge3 in the field of 140 kOe, whereas magnetization of Sm3Co2Ge3 has an antiferromagnetic behaviour. The isothermal magnetic entropy change, ΔSm, indicates a field-induced ferromagnetic ordering in Sm3Co2Ge3, Tb3Co2Ge3, Er3Co2Ge3 and Ho3Ni2Ge3 with a maximal ΔSm value of -10.9 J/kg K for Ho3Ni2Ge3 at 11 K for a field change of 50 kOe. In a zero-applied magnetic field, below TN=33 K and down to TmND=15 K Tb3Ni2Ge3 shows an ac-antiferromagnetic ordering with the C2‧/c magnetic space group, a K0=[0, 0, 0] propagation vector and a aTb3Ni2Ge3×bTb3Ni2Ge3×cTb3Ni2Ge3 magnetic unit cell. Below TmND=15 K, its magnetic structure is a sum of the ac-antiferromagnetic component with the C2‧/c magnetic space group of the K0 vector and a sine-modulated a-antiferromagnetic component of the K1=[0, 0, ±1/3] propagation vector (the magnetic unit cell is aTb3Ni2Ge3×bTb3Ni2Ge3×3cTb3Ni2Ge3). The magnetic structure is made from the 'Tb2 - 2Tb1‧ clusters of the Tb1 8f and Tb2 4c sublattices with a dominant role of the Tb2 sublattices in the magnetic ordering of Tb3Ni2Ge3.

  6. Microwave solid state synthesis and luminescence properties of green-emitting Gd2O2S:Tb3+ phosphor

    NASA Astrophysics Data System (ADS)

    He, Can; Xia, Zhiguo; Liu, Quanlin

    2015-04-01

    Gd2-xO2S:xTb3+ phosphors were prepared by the microwave solid state method, and its phase formation and morphologies were studied by the X-ray powder diffraction (XRD) and scanning electron microscope (SEM) techniques. The photoluminescence (PL) properties, cathodoluminescence (CL) properties and PL thermal stability of the samples were investigated, which indicated that better luminescence properties can be obtained via the microwave method compared to the conventional high temperature solid-state method. The composition-optimized Gd1.85O2S:15%Tb3+ exhibited strong green emission peaking at 546 nm upon excitation at 254 nm with the CIE coordinates of (0.238, 0.382). Different electric voltage and current dependent CL spectra investigations of Gd1.85O2S:15%Tb3+ phosphor shows similar green spectral profile as PL emission and it also demonstrates the good luminescence stability suggesting its potential application as green emission component in cathode ray tube (CRT).

  7. Measurement of the response of Gd2O2S:Tb phosphor to 6 MV x-rays.

    PubMed

    Glendinning, A G; Hunt, S G; Bonnett, D E

    2001-02-01

    The phosphor GdO2S:Tb is widely used in camera-based electronic portal imaging devices (EPIDs). There is considerable interest in the application of EPIDs to dosimetry and the verification of intensity modulated radiation therapy produced by dynamic multileaf collimation (DMLC). This paper presents direct measurement of Gd2O2S:Tb phosphor luminescence under 6 MV x-ray irradiation from a linear accelerator using a photomultiplier tube. The luminescence following each radiation pulse (3 micros duration) was observed to decay with a dominant lifetime of 558 micros. Using a specialized electrometer, the temporal variation of the optical signal has been compared with the dose rate incident on the phosphor measured using a semiconductor diode detector. Under dose rates typical of those used in the clinic (1.2 Gy min(-1) to the phosphor), measurements at beam-start confirmed that the optical signal is linear with dose per radiation pulse. Measurements at beam termination following phosphor doses up to 4.4 Gy showed no residual signal associated with long-lived luminescence (afterglow) from the phosphor above the noise level of the optical signal (0.17% standard deviation). This measurement demonstrates that afterglow from Gd2O2S:Tb is not of significance for its application to DMLC verification. Additionally, it was confirmed that the accelerator pulse repetition frequency has no effect on the optical signal from the phosphor in the range 25-400 Hz.

  8. Measurement of the response of Gd2O2S:Tb phosphor to 6 MV x-rays

    NASA Astrophysics Data System (ADS)

    Glendinning, A. G.; Hunt, S. G.; Bonnett, D. E.

    2001-02-01

    The phosphor Gd2O2S:Tb is widely used in camera-based electronic portal imaging devices (EPIDs). There is considerable interest in the application of EPIDs to dosimetry and the verification of intensity modulated radiation therapy produced by dynamic multileaf collimation (DMLC). This paper presents direct measurement of Gd2O2S:Tb phosphor luminescence under 6 MV x-ray irradiation from a linear accelerator using a photomultiplier tube. The luminescence following each radiation pulse (3 µs duration) was observed to decay with a dominant lifetime of 558 µs. Using a specialized electrometer, the temporal variation of the optical signal has been compared with the dose rate incident on the phosphor measured using a semiconductor diode detector. Under dose rates typical of those used in the clinic (1.2 Gy min -1 to the phosphor), measurements at beam-start confirmed that the optical signal is linear with dose per radiation pulse. Measurements at beam termination following phosphor doses up to 4.4 Gy showed no residual signal associated with long-lived luminescence (afterglow) from the phosphor above the noise level of the optical signal (0.17% standard deviation). This measurement demonstrates that afterglow from Gd2O2S:Tb is not of significance for its application to DMLC verification. Additionally, it was confirmed that the accelerator pulse repetition frequency has no effect on the optical signal from the phosphor in the range 25-400 Hz.

  9. Experimental optimum design and luminescence properties of NaY(Gd)(MoO4)2:Er3+ phosphors

    NASA Astrophysics Data System (ADS)

    Jia-Shi, Sun; Sai, Xu; Shu-Wei, Li; Lin-Lin, Shi; Zi-Hui, Zhai; Bao-Jiu, Chen

    2016-06-01

    Three-factor orthogonal design (OD) of Er3+/Gd3+/T (calcination temperature) is used to optimize the luminescent intensity of NaY(Gd)(MoO4)2:Er3+ phosphor. Firstly, the uniform design (UD) is introduced to explore the doping concentration range of Er3+/Gd3+. Then OD and range analysis are performed based on the results of UD to obtain the primary and secondary sequence and the best combination of Er3+, Gd3+, and T within the experimental range. The optimum sample is prepared by the high temperature solid state method. Photoluminescence excitation and emission spectra of the optimum sample are detected. The intense green emissions (530 nm and 550 nm) are observed which originate from Er3+ 2H11/2→ 4I15/2 and 4S3/2→4I15/2, respectively. Thermal effect is investigated in the optimum NaY(Gd3+)(MoO4)2:Er3+ phosphors, and the green emission intensity decreases as temperature increases. Project supported by Education Reform Fund of Dalian Maritime University, China (Grant No. 2015Y37), the Natural Science Foundation of Liaoning Province, China (Grant Nos. 2015020190 and 2014025010), the Open Fund of the State Key Laboratory on Integrated Optoelectronics, China (Grant No. IOSKL2015KF27), and the Fundamental Research Funds for the Central Universities, China (Grant No. 3132016121).

  10. X-ray photoelectron spectroscopy analysis for undegraded and degraded Gd2O2S:Tb3+ phosphor thin films

    NASA Astrophysics Data System (ADS)

    Dolo, J. J.; Swart, H. C.; Terblans, J. J.; Coetsee, E.; Ntwaeaborwa, O. M.; Dejene, B. F.

    2012-05-01

    This paper presents the X-ray Photoelectron Spectroscopy (XPS) analysis for the undegraded and degraded Gd2O2S:Tb3+ thin film phosphor. The thin films were grown with the pulsed laser deposition (PLD) technique. XPS measurements were done on Gd2O2S:Tb3+ phosphor thin films before and after electron degradation. The XPS technique has proven the presence of Gd2O3 on the degraded and undegraded thin film spots. The presence of the SO2 bonding was also detected after degradation. This clearly indicates that surface reactions did occur during prolonged electron bombardment in an oxygen atmosphere.

  11. Structural and magnetic properties of morphotropic phase boundary involved Tb1-xGdxFe2 compounds

    SciTech Connect

    Murtaza, Adil; Yang, Sen; Zhou, Chao; Khan, Muhammad Tahir; Ghani, Awais; Tian, Fanghua; Wang, Jieqiong; Song, Xiaoping; Suchomel, Matthrew; Ren, Yang

    2016-09-01

    In the present paper, structural, magnetic and magnetostrictive properties of Tb1-xGdxFe2 (0 <= x <= 1.0) were studied. Synchrotron x-ray diffraction (XRD) results show the non-cubic symmetry of Tb1-xGdxFe2 at room temperature and composition-induced crystallographic phase transition from rhombohedral phase to tetragonal phase. The Gd concentration dependent lattice parameters, lattice distortion and change of easy magnetic direction were detected by synchrotron XRD. With the Gd concentration increases, Curie temperature Tc increases while room temperature magnetization and magnetostriction coefficient lambda(111) and the anisotropy of TbFe2 decrease. The decrease in spontaneous magnetostriction coefficient lambda(111) with increasing Gd substitution can be understood on the basis of the single-ion model; the corresponding decrease of magnetostriction for Tb1-xGdxFe2, and the large magnetostriction value occurs on the Tb-rich side, are ascribed to decrease of lambda(111)

  12. Optical and magneto-optical properties of single crystals of RFe{sub 2} (R = Gd, Tb, Ho, and Lu) and GdCo{sub 2} intermetallic compounds

    SciTech Connect

    Lee, S.J.

    1999-02-12

    The author has studied the diagonal and off-diagonal optical conductivity of RFe{sub 2}(R = Gd, Tb, Ho, Lu) and GdCo{sub 2} single crystals grown by the flux method. Using spectroscopic ellipsometry the author has measured the dielectric function from 1.5 to 5.5 eV. The magneto-optical Kerr spectrometer at temperatures between 7 and 295 K and applied magnetic fields between 0.5 to 1.6 T. The apparatus and calibration method are described in detail. Using magneto-optical data and optical constants he derives the experimental value of the off-diagonal conductivity components. Theoretical calculations of optical conductivities and magneto-optical parameters were performed using the tight binding-linear muffin tin orbitals method within the local spin density approximation. He applied this TB-LMTO method to LuFe{sub 2}. The theoretical results obtained agree well with the experimental data. The oxidation effects on the diagonal part of the optical conductivity were considered using a three-phase model. The oxidation effects on the magneto-optical parameters were also considered by treating the oxide layer as a nonmagnetic thin transparent layer. These corrections change not only the magnitude but also the shape of the optical conductivity and the magneto-optical parameters.

  13. White upconversion emission in Li+/Yb3+/Tm3+/Er3+-doped Gd6MoO12 phosphors

    NASA Astrophysics Data System (ADS)

    Sun, Jiayue; Xue, Bing; Du, Haiyan

    2013-07-01

    The Yb3+/Er3+/Tm3+-doped Gd6MoO12 phosphors and Li+/Yb3+/Er3+/Tm3+-doped Gd6MoO12 phosphors were synthesized by the high-temperature solid-state method. Under 980 nm laser diode excitation, the Gd6MoO12:Li+/Yb3+/Er3+/Tm3+ phosphors show the white upconversion (UC) emission at the pump power of 200 mW/cm2, which is composed of the blue (1G4→3H6 of Tm3+), green (2H11/2, 4S3/2→4I15/2 of Er3+), and red (4F9/2→4I15/2 of Er3+) UC emissions. The calculated CIE color coordinates of Gd6MoO12:Tm3+/Er3+/Yb3+ phosphors changed from blue area to white area after the Li+ ion doping. Then, the effect of Li+ ions mixing on the emission was analysed. The relative UC mechanisms and properties were also investigated and proposed based on their spectral. The additional mixed Li+ ions enhanced the red and green upconversion emission largely in this phosphor and then formed the white UC emission, which indicated that the Li+ is a promising dopant for tuning white light luminescence in some case.

  14. Growth and scintillation properties of Tb doped LiGdF4/LiF eutectic scintillator

    NASA Astrophysics Data System (ADS)

    Kamada, Kei; Hishinuma, Kosuke; Kurosawa, Shunsuke; Yamaji, Akihiro; Shoji, Yasuhiro; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

    2016-11-01

    Tb-doped LiGdF4-LiF eutectics were grown at various growth rate and their directionally solidified eutectic (DSE) system has been investigated. Well aligned fiber like eutectic structure with around 1.7 μm in diameter and 1200 μm in maximum length was obtained the growth speed of 0.15 mm/min. The sample showed optical transparency like bundle optical fibers and around 40% of transmittance at 1.5 mm thick was achieved in 380-630 nm range. The expected 380-630 nm emission exited by UV and α-ray, and 270-330 nm excitation of Tb3+8S -6P transition have been observed. The weak emission of Gd3+ 4f-4f transition at 310 nm was also observed under alpha-ray excitation. The Observed excitation bands peaking at around 275 nm and 310 nm correspond respectively to the 8S7/2- 6I7/2 and 8S7/2-6PJ absorption bands of Gd3+.

  15. Polarized spectroscopic properties of Er3+:Gd2SiO5 crystal and evaluation of Er3+:Yb3+:Gd2SiO5 crystal as a 1.55 μm laser medium

    NASA Astrophysics Data System (ADS)

    Wang, H.; Huang, J. H.; Gong, X. H.; Chen, Y. J.; Lin, Y. F.; Luo, Z. D.; Huang, Y. D.

    2016-10-01

    An Er3+-doped Gd2SiO5 single crystal with high optical quality has been grown by the Czochralski method. Polarized absorption and fluorescence spectra and fluorescence lifetime of the crystal were measured at room temperature. Intensity parameters, spontaneous emission probabilities, fluorescence branching ratios, and radiative lifetimes were estimated on the basis of the Judd-Ofelt theory. Besides, potentiality of 1.55 μm laser emission in an Er3+-Yb3+ co-doped Gd2SiO5 crystal was evaluated.

  16. Magnetic tuning of upconversion luminescence in Au/NaGdF4:Yb(3+)/Er(3+) nanocomposite.

    PubMed

    Dai, Gangtao; Zhong, Zhiqiang; Wu, Xiaofeng; Zhan, Shiping; Hu, Shigang; Hu, Pan; Hu, Junshan; Wu, Shaobing; Han, Junbo; Liu, Yunxin

    2017-04-18

    Lanthanide-doped upconversion nanoparticles (UCNPs) NaGdF4:Yb(3+)/Er(3+) have received increasing attention due to their unique optical-magnetic bifunctional properties. Here, we show that the luminescent intensity from NaGdF4:Yb(3+)/Er(3+) nanoparticles decreases monotonously with increasing the applied magnetic field from 0 to 37.1 T, while plasmon-enhanced upconversion luminescence in Au/NaGdF4:Yb(3+)/Er(3+) nanocomposite is independent of a magnetic field lower than 6 T. The surface plasmon resonances could compensate for the energetic mismatching between the excitation light and the energy-level gaps induced by magnetic field and enhance the radiative efficiency, which is the main factor for achieving this stable upconversion emission in this nanocomposite under a magnetic field not higher than 6 T. These findings provide a novel route for exploring the magnetic control of upconversion luminescence in lanthanide-doped bifunctional nanoparticles.

  17. Magnetic tuning of upconversion luminescence in Au/NaGdF4:Yb3+/Er3+ nanocomposite

    NASA Astrophysics Data System (ADS)

    Dai, Gangtao; Zhong, Zhiqiang; Wu, Xiaofeng; Zhan, Shiping; Hu, Shigang; Hu, Pan; Hu, Junshan; Wu, Shaobing; Han, Junbo; Liu, Yunxin

    2017-04-01

    Lanthanide-doped upconversion nanoparticles (UCNPs) NaGdF4:Yb3+/Er3+ have received increasing attention due to their unique optical-magnetic bifunctional properties. Here, we show that the luminescent intensity from NaGdF4:Yb3+/Er3+ nanoparticles decreases monotonously with increasing the applied magnetic field from 0 to 37.1 T, while plasmon-enhanced upconversion luminescence in Au/NaGdF4:Yb3+/Er3+ nanocomposite is independent of a magnetic field lower than 6 T. The surface plasmon resonances could compensate for the energetic mismatching between the excitation light and the energy-level gaps induced by magnetic field and enhance the radiative efficiency, which is the main factor for achieving this stable upconversion emission in this nanocomposite under a magnetic field not higher than 6 T. These findings provide a novel route for exploring the magnetic control of upconversion luminescence in lanthanide-doped bifunctional nanoparticles.

  18. Magnetic properties of Fe{sub 2}P-type R{sub 6}CoTe{sub 2} compounds (R=Gd-Er)

    SciTech Connect

    Morozkin, A.V.; Mozharivskyj, Yu; Svitlyk, V.; Nirmala, R.; Isnard, O.; Ritter, C.

    2010-06-15

    The magnetic structure of the Fe{sub 2}P-type R{sub 6}CoTe{sub 2} phases (R=Gd-Er, space group P6-bar 2m) has been investigated through magnetization measurement and neutron powder diffraction. All phases demonstrate high-temperature ferromagnetic and low-temperature transitions: T{sub C}=220 K and T{sub CN}=180 K for Gd{sub 6}CoTe{sub 2}, T{sub C}=174 K and T{sub CN}=52 K for Tb{sub 6}CoTe{sub 2}, T{sub C}=125 K and T{sub CN}=26 K for Dy{sub 6}CoTe{sub 2}, T{sub CN}=60 K and T{sub N}=22 K for Ho{sub 6}CoTe{sub 2} and T{sub CN{approx}}30 K and T{sub N{approx}}14 K for Er{sub 6}CoTe{sub 2}. Between 174 and 52 K Tb{sub 6}CoTe{sub 2} has a collinear magnetic structure with K{sub 0}=[0, 0, 0] and with magnetic moments along the c-axis, whereas below 52 K it adopts a non-collinear ferromagnetic one. Below 60 K the magnetic structure of Ho{sub 6}CoTe{sub 2} is that of a non-collinear ferromagnet. The holmium magnetic components with a K{sub 0}=[0, 0, 0] wave vector are aligned ferromagneticaly along the c-axis, whereas the magnetic component with a K{sub 1}=[1/2, 1/2, 0] wave vector are arranged in the ab plane. The low-temperature magnetic transition at {approx}22 K coincides with the reorientation of the Ho magnetic component with the K{sub 0} vector from the collinear to the non-collinear state. Below 30 K Er{sub 6}CoTe{sub 2} shows an amplitude-modulate magnetic structure with a collinear arrangement of magnetic components with K{sub 0}=[0, 0, 0] and K{sub 1}=[1/2, 1/2, 0]. The low-temperature magnetic transition at {approx}14 K corresponds to the variation in the magnitudes of the M{sub Er}{sup K0} and M{sub Er}{sup K1} magnetic components. In these phases, no local moment was detected on the cobalt site. The magnetic entropy of Gd{sub 6}CoTe{sub 2} increases from {Delta}S{sub mag}=-4.5 J/kg K at 220 K up to {Delta}S{sub mag}=-6.5 J/kg K at 180 K for the field change {Delta}{mu}{sub 0}H=0-5 T. - Graphical abstract: The novel Fe{sub 2}P-type R{sub 6}CoTe{sub 2

  19. Controlling the Two-Photon-Induced Photon Cascade Emission in a Gd3+/Tb3+-Codoped Glass for Multicolor Display

    PubMed Central

    Yuan, Mao-Hui; Fan, Hai-Hua; Li, Hui; Lan, Sheng; Tie, Shao-Long; Yang, Zhong-Min

    2016-01-01

    We reported the first observation of the two-photon-induced quantum cutting phenomenon in a Gd3+/Tb3+-codoped glass in which two photons at ~400 nm are simultaneously absorbed, leading to the cascade emission of three photons in the visible spectral region. The two-photon absorption induced by femtosecond laser pulses allows the excitation of the energy states in Gd3+ which are inactive for single-photon excitation and enables the observation of many new electric transitions which are invisible in the single-photon-induced luminescence. The competition between the two-photon-induced photon cascade emission and the single-photon-induced emission was manipulated to control the luminescence color of the glass. We demonstrated the change of the luminescence color from red to yellow and eventually to green by varying either the excitation wavelength or the excitation power density. PMID:26899189

  20. Magnetic properties of Fe{sub 2}P-type Tb{sub 6}FeTe{sub 2}, Tb{sub 6}CoTe{sub 2}, Tb{sub 6}NiTe{sub 2} and Er{sub 6}FeTe{sub 2} compounds

    SciTech Connect

    Morozkin, A.V.; Mozharivskyj, Yu.; SvitlyK, V.; Nirmala, R.; Nigam, A.K.

    2010-12-15

    The magnetic ordering of the Fe{sub 2}P-type Tb{sub 6}FeTe{sub 2}, Tb{sub 6}CoTe{sub 2} Tb{sub 6}NiTe{sub 2} and Er{sub 6}FeTe{sub 2} phases (space group P6-bar 2m) has been investigated through magnetization measurement and neutron powder diffraction. Tb{sub 6}FeTe{sub 2}, Tb{sub 6}CoTe{sub 2} and Tb{sub 6}NiTe{sub 2} demonstrate high-temperature ferromagnetic and low-temperature spin reorientation transitions, whereas Er{sub 6}FeTe{sub 2} shows antiferromagnetic transition, only. The Tb{sub 6}FeTe{sub 2} and Tb{sub 6}NiTe{sub 2} phases show same high-temperature collinear ferromagnetic structure, whereas Tb{sub 6}FeTe{sub 2} is the commensurate non-collinear ferromagnet and Tb{sub 6}NiTe{sub 2} is the canted ferromagnetic cone with K{sub 1}=[0, 0, {+-}3/10] and K{sub 2}=[{+-}2/9, {+-}2/9, 0] wave vectors at 2 K. The magnetic structure of Er{sub 6}FeTe{sub 2} is a flat spiral with K{sub 1}=[0, 0, {+-}1/10] at 2 K. The magnetic entropy change for Tb{sub 6}NiTe{sub 2} is {Delta}S{sub m}=-4.86 J/kg K at 229 K for the field change {Delta}{mu}{sub 0}H=0-5 T. In addition, novel Fe{sub 2}P-type Gd{sub 6}FeTe{sub 2}, Zr{sub 6}FeTe{sub 2}, Hf{sub 6}FeTe{sub 2}, Dy{sub 6}NiTe{sub 2}, Zr{sub 6}NiTe{sub 2} and Hf{sub 6}NiTe{sub 2} phases have been obtained. -- Graphical abstract: The novel Fe{sub 2}P-type Tb{sub 6{l_brace}}Fe, Co, Te{r_brace}Te{sub 2} and Er{sub 6}FeTe{sub 2} phases (space group P6-bar 2m) show the complex magnetic ordering below 18-228 K. The magnetocaloric effect for Tb{sub 6}NiTe{sub 2} in terms of the isothermal entropy change, -{Delta}S{sub m}, has the maximum value of 4.86 J/kg K at 229 K for the 0-5 T field change.

  1. Folic acid-conjugated GdPO4:Tb3+@SiO2 Nanoprobe for folate receptor-targeted optical and magnetic resonance bi-modal imaging

    NASA Astrophysics Data System (ADS)

    Xu, Xianzhu; Zhang, Xiaoying; Wu, Yanli

    2016-11-01

    Both fluorescent and magnetic nanoprobes have great potential applications for diagnostics and therapy. In the present work, a folic acid-conjugated and silica-modified GdPO4:Tb3+ (GdPO4:Tb3+@SiO2-FA) dual nanoprobe was strategically designed and synthesized for the targeted dual-modality optical and magnetic resonance (MR) imaging via a facile aqueous method. Their structural, optical, and magnetic properties were determined using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), ultraviolet-visible spectra (UV-Vis), photoluminescence (PL), and superconducting quantum interference device (SQUID). These results indicated that GdPO4:Tb3+@SiO2-FA were uniform monodisperse core-shell structured nanorods (NRs) with an average length of 200 nm and an average width of 25 nm. The paramagnetic property of the synthesized GdPO4:Tb3+@SiO2-FA NRs was confirmed with its linear hysteresis plot (M-H). In addition, the NRs displayed an obvious T1-weighted effect and thus it could potentially serve as a T1-positive contrast agent. The NRs emitted green lights due to the 5D4 → 7F5 transition of the Tb3+. The in vitro assays with NCI-H460 lung cancer cells and human embryonic kidney cell line 293T cells indicated that the GdPO4:Tb3+@SiO2-FA nanoprobe could specifically bind the cells bearing folate receptors (FR). The MTT assay of the NRs revealed that its cytotoxicity was very low. Further in vivo MRI experiments distinctively depict enhanced anatomical features in a xenograft tumor. These results suggest that the GdPO4:Tb3+@SiO2-FA NPs have excellent imaging and cell-targeting abilities for the folate receptor-targeted dual-modality optical and MR imaging and can be potentially used as the nanoprobe for bioimaging.

  2. Fabrication and characterization of Gd2O2SO4:Tb3+ phosphors by sol-gel method

    NASA Astrophysics Data System (ADS)

    Aritman, I.; Yildirim, S.; Kisa, A.; Guleryuz, L. F.; Yurddaskal, M.; Dikici, T.; Celik, E.

    2017-02-01

    The objective of the innovative approaches of the scintillation materials to be used in the digital portal imaging systems in the radiotherapy applications is to research the GOS material production that has been activated with the rare earth elements (RE), to produce the scintillation detectors that have a rapid imaging process with a lesser radiation and higher image quality from these materials and to apply the radiographic imaging systems. The GOS: Tb3+ showed high emission peak and high x-ray absorption properties which have been determined for application to mammography and dental radiography. In this study, Gd2O2SO4:Tb3+ phosphors were fabricated by the sol-gel method that is a unique technique and not previously applied. Besides, the structural characterization of GOS: Tb3+ has been investigated. The strongest emission peak located at 549 nm under 312 nm UV light excitation was appeared on the GOS: Tb3+ phosphor particles. The characterization processing optimized by using FTIR, DTA-TG, XRD, XPS, SEM and the luminescence spectroscopy.

  3. Photoluminescence and thermoluminescence properties of Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor

    SciTech Connect

    Gupta, Palvi; Bedyal, A.K.; Kumar, Vinay; Khajuria, Y.; Lochab, S.P.; Pitale, S.S.; Ntwaeaborwa, O.M.; Swart, H.C.

    2014-12-15

    Energy level diagram of Tb{sup 3+} ion in the K{sub 3}Gd(PO{sub 4}){sub 2} host lattice. - Highlights: • First time, a detailed TL and PL study on undoped and Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor. • Combustion method was employed to synthesize the Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor. • Mechanism of excitation and emission in undoped and Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2} nanophosphor was given. - Abstract: Tb{sup 3+} doped nanoparticulate K{sub 3}Gd(PO{sub 4}){sub 2} phosphor was prepared by combustion method using urea as a fuel. The structure, optical and luminescent properties of the phosphor were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and thermoluminescence (TL) spectroscopy. In undoped K{sub 3}Gd(PO{sub 4}){sub 2}, the excitation and emission peaks at 273 nm and 323 nm belongs to the {sup 8}S{sub 7/2} → {sup 6}I{sub J(J=7/2)} and {sup 6}P{sub J(J=7/2)} → {sup 8} S{sub 7/2} transitions of Gd{sup 3+} while green emission was observed in the Tb{sup 3+} doped K{sub 3}Gd(PO{sub 4}){sub 2}. TL study was carried out after exposing the samples to γ-radiations (0.1–5 kGy) in the K{sub 3}Gd(PO{sub 4}){sub 2}:Tb{sup 3+} (1.5 mol%). The calculated kinetic parameters were compared with different methods. The band gap of the phosphor was estimated as 5.80 eV. The green shade of the Tb{sup 3+} ion with the CIE coordinates (x, y) as (0.29, 0.54) was in good agreement with the well known green phosphors.

  4. Polarized spectroscopic properties of Er3+:BaGd2(MoO4)4 crystal

    NASA Astrophysics Data System (ADS)

    Pan, Y.; Gong, X. H.; Chen, Y. J.; Lin, Y. F.; Huang, J. H.; Luo, Z. D.; Huang, Y. D.

    2012-05-01

    An Er3+:BaGd2(MoO4)4 single crystal has been grown by the Czochralski method. The polarized absorption spectra, polarized fluorescence spectra, and fluorescence decay curves were measured. In the framework of Judd-Ofelt theory, intensity parameters, spontaneous emission probabilities, fluorescence branching ratios, and radiative lifetimes were calculated. Besides, green upconversion fluorescence was also observed.

  5. Spin transfer torque switching in exchange-coupled amorphous GdFeCo/TbFe bilayers for thermally assisted MRAM application

    NASA Astrophysics Data System (ADS)

    Dai, Bing; Guo, Yong; Zhu, Jiaqi; Kato, Takeshi; Iwata, Satoshi; Tsunashima, Shigeru; Yang, Lei; Han, Jiecai

    2017-04-01

    Exchange-coupled amorphous GdFeCo/TbFe memory layers in giant magneto-resistance (GMR) devices for spin transfer torque (STT) switching have been studied, and temperature dependence of the critical current density of the GMR devices was measured to discuss the effect of exchange-coupled bilayers as a memory layer of the thermally assisted magnetic random access memory (MRAM). The GMR devices having amorphous GdFeCo and TbFe memory bilayers with various thicknesses were prepared by magnetron sputtering and subsequent micro-fabrication processes. A pulsed current was applied to the GMR devices in order to investigate the spin transfer torque (STT) switching. The maximum magneto-resistance (MR) ratio was around 0.15%, and the coercivity of the memory bilayer increased with the TbFe thickness and decreased with elevating temperature. The critical current densities J c to switch the memory bilayer with structure of Gd21.4 (Fe90Co10)78.6(9 nm)/Tb16Fe84 (1 nm) as low as 2.2  ×  107 A cm‑2 was obtained. The J c reduced with increasing the temperature and was found to scale with the effective anisotropy K eff of GdFeCo/TbFe bilayer, which is believed to be suitable for the application of thermally assisted STT-MRAM.

  6. Crystal growth of CW diode-pumped (Er3+,Yb3+):GdAl3(BO3)4 laser material

    NASA Astrophysics Data System (ADS)

    Maltsev, V. V.; Koporulina, E. V.; Leonyuk, N. I.; Gorbachenya, K. N.; Kisel, V. E.; Yasukevich, A. S.; Kuleshov, N. V.

    2014-09-01

    Phase relationships in the Er:YbxGd1-xAl3(BO3)4-K2Mo3O10-B2O3-(Gd,Er,Yb)2O3 (x=0-0.2, Er-1 at%) system were studied in the temperature range from 1150 to 900 °С. Multicomponent melts of 55 mol%K2Mo3O10-45 mol% B2O3 (I) and 55 mol% K2Mo3O10-40 mol% B2O3-5 mol% (Gd,Er,Yb)2O3 (II) were suggested as reasonable fluxes for high-temperature solution growth of (Yb3+,Er3+):GdAl3(BO3)4 single crystals. Yb0.15Gd0.85Al3(BO3)4 solubility in the complex flux of II composition has been found as varying from 17 to 9.5 mol% with decreasing temperature in the interval of 1000-800 °C. As a result, (Er,Yb):GdAB single crystals with high optical quality and sizes up to 20×10×10 mm were grown on dipped "point" seeds. Absorption and stimulated emission spectra, emission lifetimes, and efficiencies of energy transfer from Yb3+ to Er3+ ions were determined. Highly efficient continuous-wave diode-pumped laser operation of (Er,Yb):GdAl3(BO3)4 crystal was realized.

  7. Effect of Low Additions of Y, Sm, Gd, Hf and Er on the Structure and Hardness of Alloy Al - 0.2% Zr - 0.1% Sc

    NASA Astrophysics Data System (ADS)

    Pozdnyakov, A. V.; Osipenkova, A. A.; Popov, D. A.; Makhov, S. V.; Napalkov, V. I.

    2017-01-01

    The structure and phase composition of addition alloys based on aluminum with Hf, Er, Gd, Yand Sm and the effect of low additions of these transition metals on the structure and properties of alloy Al - 0.2% Zr - 0.1% Sc are studied. It is shown that individual introduction of Y, Sm, Er, and Gd in an amount of 0.1% each causes formation of eutectic phases Al3Y, Al3Sm, Al3Er and Al3Gd, respectively. An indirect inference is that the additions of Y, Sm, Hf, Er and Gd raise the thermal stability of the Al3 (Sc, Zr) dispersoids after annealing at 250°C with a hold of up to 100 h; softening at 370°C starts after holding for 54 h. Maximum hardening is detected in the case of 0.1% Er and attains 50 HV after a 54-h hold at 370°C.

  8. Magnetic properties of CaCu5-type RNi3TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Yao, Jinlei; Yuan, Fang; Mozharivskyj, Y.; Nirmala, R.; Quezado, S.; Malik, S. K.

    2015-12-01

    Magnetic properties and magnetocaloric effect of CaCu5-type RNi3TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds have been investigated. Magnetic measurements of RNi3TSi display the increasing of Curie temperature and the decreasing of magnetocaloric effect and saturated magnetic moment in the row of 'RNi3CuSi-RNi3NiSi-RNi3CoSi-RNi3MnSi-RNi3FeSi'. In contrast to GdNi3{Mn, Fe, Co}Si, TbNi3{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. The coercive field increases from TbNi4Si ( 0.5 kOe) to TbNi3CoSi (4 kOe), TbNi3MnSi (13 kOe) and TbNi3FeSi (16 kOe) in field of 50 kOe at 5 K, whereas TbNi3CuSi exhibits a negligible coercive field.

  9. Growth and luminescent properties of Ce and Ce-Tb doped (Y,Lu,Gd)2SiO5:Ce single crystalline films

    NASA Astrophysics Data System (ADS)

    Zorenko, Yuriy; Gorbenko, Vitaliy; Savchyn, Volodymyr; Zorenko, Tetyana; Grinyov, Boris; Sidletskiy, Oleg; Fedorov, Alexander

    2014-09-01

    The paper presents the results of systematic research directed on the development of scintillating screens based on single crystalline films of Ce and Ce-Tb doped (Y,Lu,Gd)2SiO5 orthosilicates using the liquid phase epitaxy method.

  10. Surfactant mediated hydrothermal synthesis, characterization and luminescent properties of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell nanorods

    SciTech Connect

    Khajuria, Heena; Ladol, Jigmet; Khajuria, Sonika; Shah, Mohd Syed; Sheikh, H.N.

    2016-08-15

    Highlights: • Core shell nanorods were synthesised by surfactant assisted hydrothermal method. • Morphology of core shell nanorods resembles those of core nanorods indicating coating of shell on cores. • More uniform and non-aggregated core shell nanorods were prepared in presence of surfactants. • Surfactant assisted prepared core shell nanorods show intense emission as compared to uncoated core nanorods. - Abstract: Core shell GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} nanorods were synthesized via hydrothermal route in the presence of different surfactants [cetyltrimethyl ammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS)]. The nanorods were characterized by powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and photoluminescence (PL) studies. The X-ray diffraction results indicate good crystallinity and effective doping in core and core shell nanorods. SEM and TEM micrographs show that all of the as prepared gadolinium phosphate products have rod like shape. The compositional analysis of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core was done by EDS. The emission intensity of the GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell increased significantly with respect to those of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core nanorods. The effect of surfactant on the uniformity, thickness and luminescence of the core shell nanorods was investigated.

  11. Structural and optical properties of Tb-doped Na-Gd metaphosphate glasses and glass-ceramics

    NASA Astrophysics Data System (ADS)

    Moretti, F.; Vedda, A.; Nikl, M.; Nitsch, K.

    2009-04-01

    The optical and structural properties of terbium doped sodium gadolinium phosphate glasses of three different compositions subjected to a crystallization process were studied and compared with those of the parent glassy samples. The structural characteristics of the glassy and crystallized phases were determined by Raman spectroscopy and the results showed a remarkable reduction in the full width at half maximum of the Raman peaks after crystallization. Radio-luminescence measurements revealed the emissions of both Gd3+ and Tb3+ ions. Their intensities strongly increased and their intensity ratio was modified by the crystallization. The luminescence temperature dependence investigated by radio-luminescence measurements in the temperature interval from 10 to 310 K became more complicated after crystallization. The role of free carrier trapping phenomena in the modification of the radio-luminescence efficiency was also studied by thermally stimulated luminescence.

  12. Structural and optical properties of Tb-doped Na-Gd metaphosphate glasses and glass-ceramics.

    PubMed

    Moretti, F; Vedda, A; Nikl, M; Nitsch, K

    2009-04-15

    The optical and structural properties of terbium doped sodium gadolinium phosphate glasses of three different compositions subjected to a crystallization process were studied and compared with those of the parent glassy samples. The structural characteristics of the glassy and crystallized phases were determined by Raman spectroscopy and the results showed a remarkable reduction in the full width at half maximum of the Raman peaks after crystallization. Radio-luminescence measurements revealed the emissions of both Gd(3+) and Tb(3+) ions. Their intensities strongly increased and their intensity ratio was modified by the crystallization. The luminescence temperature dependence investigated by radio-luminescence measurements in the temperature interval from 10 to 310 K became more complicated after crystallization. The role of free carrier trapping phenomena in the modification of the radio-luminescence efficiency was also studied by thermally stimulated luminescence.

  13. Properties of Gd{sub 2}O{sub 3}:Eu{sup 3+}, Tb{sup 3+} nanopowders obtained by sol-gel process

    SciTech Connect

    Ramirez, A. de J. Morales; Murillo, A. Garcia; Romo, F. de J. Carrillo; Hernandez, M. Garcia; Vigueras, D. Jaramillo

    2010-01-15

    A significant practical application for nanostructured materials is X-ray medical imagery, because it is necessary to use dense materials in order to enable absorption of high energy photons. An important requirement of these materials is UV-vis range emission produced by X-ray excitation, which can be influenced by the particle size. Europium doped gadolinium oxide is a well known red phosphor. Moreover, nanophosphors of Gd{sub 2}O{sub 3} codoped with Tb{sup 3+}, Eu{sup 3+} increase their light yield by energy transfer between Tb{sup 3+} and Eu{sup 3+}. In this study, Gd{sub 2}O{sub 3} nanopowders codoped with Eu{sup 3+} and Tb{sup 3+} (2.5 at.% Eu{sup 3+}, and 0.005 and 0.01 at.% Tb{sup 3+}) were obtained via a sol-gel process using gadolinium pentanedionate as precursor and europium and terbium nitrates as doping sources. In this paper, we report the influence of annealing temperature on the structure, morphology and luminescent properties of Gd{sub 2}O{sub 3}:Eu{sup 3+}, Tb{sup 3+} by means of TGA, XRD, TEM and X-ray emission measurements.

  14. RNi{sub 8}Si{sub 3} (R=Gd,Tb): Novel ternary ordered derivatives of the BaCd{sub 11} type

    SciTech Connect

    Pani, M.; Morozkin, A.V.; Yapaskurt, V.O.; Provino, A.; Manfrinetti, P.; Nirmala, R.; Malik, S.K.

    2016-01-15

    The title compounds have been synthesized and characterized both from the structural and magnetic point of view. Both crystallize in a new monoclinic structure strictly related to the tetragonal BaCd{sub 11} type. The structure was solved by means of X-ray single-crystal techniques for GdNi{sub 8}Si{sub 3} and confirmed for TbNi{sub 8}Si{sub 3} on powder data; the corresponding lattice parameters (obtained from Guinier powder patterns) are a=6.3259(2), b=13.7245(5), c=7.4949(3) Å, β=113.522(3)°, V{sub cell}=596.64(3) Å{sup 3} and a=6.3200(2), b=13.6987(4), c=7.4923(2) Å, β=113.494(2)°, V{sub cell}=594.88(2) Å{sup 3}. The symmetry relationship between the tI48-I4{sub 1}/amd BaCd{sub 11} aristotype and the new ordered mS48-C2/c GdNi{sub 8}Si{sub 3} derivative is described via the Bärnighausen formalism within the group theory. The large Gd–Gd (Tb–Tb) distances, mediated via Ni–Si network, likely lead to weak magnetic interactions. Low-field magnetization vs temperature measurements indicate weak and field-sensitive antiferromagnetic ground state, with ordering temperatures of 3 K in GdNi{sub 8}Si{sub 3} and about 2–3 K in TbNi{sub 8}Si{sub 3}. On the other hand, the isothermal field-dependent magnetization data show the presence of competing interactions in both compounds, with a field-induced ferromagnetic behavior for GdNi{sub 8}Si{sub 3} and a ferrimagnetic-like behavior in TbNi{sub 8}Si{sub 3} at the ordering temperature T{sub C/N} of about (or slightly higher than) 3K. The magnetocaloric effect, quantified in terms of isothermal magnetic entropy change ΔS{sub m}, has the maximum values of –19.8 J(kg K){sup −1} (at 4 K for 140 kOe field change) and −12.1 J(kg K){sup −1} (at 12 K for 140 kOe field change) in GdNi{sub 8}Si{sub 3} and TbNi{sub 8}Si{sub 3}, respectively. - Graphical abstract: GdNi{sub 8}Si{sub 3} and TbNi{sub 8}Si{sub 3} compounds are isostructural, and crystallize in a new monoclinic type strictly related to the tetragonal

  15. Ce(IV) -Gd(III) Mixed Oxides as Hosts for Er(III) -Based Upconversion Phosphors.

    PubMed

    Sorbello, Cecilia; Gross, Petra; Strassert, Cristian A; Jobbágy, Matías; Barja, Beatriz C

    2017-03-23

    A family of Er(III) and Er(III) -Yb(III) based nanophosphors, hosted in monophasic oxidic Ce(IV) -Gd(III) binary solid solutions, was prepared. The samples were formulated with a constant Er(III) content as the activator, with the eventual addition of Yb(III) as a sensitizer. The amorphous Ce0.94-x Gdx Er0.06 (OH)CO3 ⋅H2 O and Ce0.94-x Gdx Er0.05 Yb0.01 (OH)CO3 ⋅H2 O precursors were prepared by following the urea method to obtain monodispersed spheres of tunable size ranging from 30 to 450 nm. After being decomposed at 1273 K under an atmosphere of air, the precursors of 200 nm in diameter evolved into monophasic polycrystalline particles preserving the parent shape and size. The role of the composition of the binary matrices in the emission properties was evaluated for two different excitation wavelengths (976 nm and 780 nm) based on the upconversion (UC) emission spectra and their dependence on the incident power. The yield of the UC process is discussed in the framework of established and novel alternative mechanisms. The number of vacancies and mainly the symmetry of the Er(III) environment play major roles in the deactivation pathways of the UC emission mechanisms. However, the colours obtained by employing bare Ce(IV) or Gd(III) hosts are preserved in the related monophasic Ce(IV) -rich or Gd(III) -rich binary hosts.

  16. Size and shape effects in β-NaGdF4: Yb(3+), Er(3+) nanocrystals.

    PubMed

    Noculak, Agnieszka; Podhorodecki, Artur

    2017-04-28

    Three sets of β-NaGdF4:Yb(3+), Er(3+) nanocrystals (NCs) with different shapes (spherical and more complex flower shapes), different sizes (6-17 nm) and Yb(3+) concentrations (2%-15%) were synthesized by a co-precipitation method using oleic acid as a stabilizing agent. The uncommon, single-crystalline flower-shaped NCs were obtained by simply adjusting the fluorine-to-lanthanides molar ratio. Additionally, some of the NCs with different sizes have been covered by the un-doped shell. The crystal phase, shapes and sizes of all NCs were examined using transmission electron microscopy and x-ray diffraction methods. Simultaneously, upconversion luminescence and lifetimes, under 980 nm excitation, were measured and the changes in green to red (G/R) emission ratios as well as emission decay times were correlated with the evolution of nanocrystal sizes and surface to volume ratios. Three different mechanisms responsible for the changes in G/R ratios were presented and discussed.

  17. Magnetic properties of CaCu{sub 5}-type RNi{sub 3}TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds

    SciTech Connect

    Morozkin, A.V.; Knotko, A.V.; Yapaskurt, V.O.; Yao, Jinlei; Yuan, Fang; Mozharivskyj, Y.; Nirmala, R.; Quezado, S.; Malik, S.K.

    2015-12-15

    Magnetic properties and magnetocaloric effect of CaCu{sub 5}-type RNi{sub 3}TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds have been investigated. Magnetic measurements of RNi{sub 3}TSi display the increasing of Curie temperature and the decreasing of magnetocaloric effect and saturated magnetic moment in the row of ‘RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi’. In contrast to GdNi{sub 3}{Mn, Fe, Co}Si, TbNi{sub 3}{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. The coercive field increases from TbNi{sub 4}Si (~0.5 kOe) to TbNi{sub 3}CoSi (4 kOe), TbNi{sub 3}MnSi (13 kOe) and TbNi{sub 3}FeSi (16 kOe) in field of 50 kOe at 5 K, whereas TbNi{sub 3}CuSi exhibits a negligible coercive field. - Graphical abstract: Magnetic measurements of RNi{sub 3}TSi show the increasing of Curie temperature and the decreasing of magnetocaloric effect and saturated magnetic moment in the row of 'RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi'. In contrast to GdNi{sub 3}{Mn, Fe, Co}Si, TbNi{sub 3}{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. The coercive field increases from TbNi{sub 4}Si (~0.5 kOe) to TbNi{sub 3}CoSi (4 kOe), TbNi{sub 3}MnSi (13 kOe) and TbNi{sub 3}FeSi (16 kOe) in field of 50 kOe at 5 K, whereas TbNi{sub 3}CuSi exhibits a negligible coercive field. - Highlights: • CaCu{sub 5}-type RNi{sub 3}TSi show ferromagnetic ordering (R=Gd, Tb, T=Mn–Co, Cu). • Curie point increases in ‘RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi’ row. • MCE decreases in ‘RNi{sub 3}CuSi–RNi{sub 3}NiSi–RNi{sub 3}CoSi–RNi{sub 3}MnSi–RNi{sub 3}FeSi’ row. • TbNi{sub 3}{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. • The coercive field of TbNi{sub 3}MnSi and TbNi{sub 3}FeSi reach 13 kOe and 16 kOe at 5 K.

  18. Anomalous pressure dependence of magnetic ordering temperature in Tb revealed by resistivity measurements to 141 GPa. Comparison with Gd and Dy

    DOE PAGES

    Lim, J.; Fabbris, G.; Haskel, D.; ...

    2015-05-26

    In previous studies the pressure dependence of the magnetic ordering temperature To of Dy was found to exhibit a sharp increase above its volume collapse pressure of 73 GPa, appearing to reach temperatures well above ambient at 157 GPa. In a search for a second such lanthanide, electrical resistivity measurements were carried out on neighboring Tb to 141 GPa over the temperature range 3.8 - 295 K. Below Tb’s volume collapse pressure of 53 GPa, the pressure dependence To(P) mirrors that of both Dy and Gd. However, at higher pressures To(P) for Tb becomes highly anomalous. This result, together withmore » the very strong suppression of superconductivity by dilute Tb ions in Y, suggests that extreme pressure transports Tb into an unconventional magnetic state with an anomalously high magnetic ordering temperature.« less

  19. Anomalous pressure dependence of magnetic ordering temperature in Tb revealed by resistivity measurements to 141 GPa. Comparison with Gd and Dy

    SciTech Connect

    Lim, J.; Fabbris, G.; Haskel, D.; Schilling, J. S.

    2015-05-26

    In previous studies the pressure dependence of the magnetic ordering temperature To of Dy was found to exhibit a sharp increase above its volume collapse pressure of 73 GPa, appearing to reach temperatures well above ambient at 157 GPa. In a search for a second such lanthanide, electrical resistivity measurements were carried out on neighboring Tb to 141 GPa over the temperature range 3.8 - 295 K. Below Tb’s volume collapse pressure of 53 GPa, the pressure dependence To(P) mirrors that of both Dy and Gd. However, at higher pressures To(P) for Tb becomes highly anomalous. This result, together with the very strong suppression of superconductivity by dilute Tb ions in Y, suggests that extreme pressure transports Tb into an unconventional magnetic state with an anomalously high magnetic ordering temperature.

  20. Luminescent properties of Tb-activated rare-earth oxyapatite silicate MLn4Si3O13 (M = Ca, Sr, Ln = La, Gd)

    NASA Astrophysics Data System (ADS)

    Yamane, A.; Kunimoto, T.; Ohmi, K.; Honma, T.; Kobayashi, H.

    2006-09-01

    Rare-earth oxyapatites MLn4Si3O13 (M = Ca, Sr, Ba Ln = La, Gd) have been proposed as a new plasma display panel (PDP) host material to overcome the problems of Zn2SiO4:Mn commercial green phosphor, such as luminance degradation and poor surface charge. Tb-doped MLn4Si3O13 phosphor powders show a green luminescence with the CIE color coordinate (x, y) = (0.337, 0.562). The PL excitation band lies continuously in the wavelength region from 130 to 260 nm. The photoluminescence (PL) peak intensity of SrGd4Si3O13:Tb is comparable with that of Zn2SiO4:Mn. The phosphor is a candidate for a green PDP phosphor for Xe2 excitation.

  1. 6.7-nm Emission from Gd and Tb Plasmas over a Broad Range of Irradiation Parameters Using a Single Laser

    NASA Astrophysics Data System (ADS)

    Yin, Liang; Wang, Hanchen; Reagan, Brendan A.; Baumgarten, Cory; Gullikson, Eric; Berrill, Mark; Shlyaptsev, Vyacheslav N.; Rocca, Jorge J.

    2016-09-01

    We report a comprehensive study of the emission from Gd and Tb laser-produced plasmas in the 6.5-6.7-nm wavelength region for a broad range of laser-irradiation parameters using a single λ =1030 nm laser with tunable pulse duration in the 120-ps-to-4-ns range. The results are of interest for beyond-extreme-ultraviolet (BEUV) lithography of integrated circuits. BEUV emission spectra are measured as a function of laser-pulse duration, emission angle, and spatial location within the plasma. Images of the BEUV-emitting plasma region at the BEUV wavelength are obtained as a function of irradiation parameters. The emission spectrum is observed to broaden and to shift to a longer wavelength as the duration of the driver laser pulses is shortened from nanoseconds to hundreds of picoseconds. Transient self-consistent hydrodynamic and atomic physics simulations show that the picosecond irradiation creates significantly hotter plasmas in which the dominant emission originates from more highly ionized species. Gd-plasma emission driven by nanosecond laser pulses spectrally best matches the responsivity of the energy monitors used, centered near λ =6.74 nm . Spatially resolved spectra of the Gd plasma are acquired for different laser-pulse durations. The conversion efficiency (CE) of Gd /Tb plasma into a 0.6% bandwidth in a 2 π solid angle is determined by integrating angularly resolved measurements obtained using an array of calibrated energy monitors. Similar maximum CEs of about 0.47% for both the Gd and Tb plasmas are obtained. The source size is measured to approximately match the spot size of the laser on target, in agreement with simulations.

  2. Morphotropic phase boundary and magnetoelastic behaviour in ferromagnetic Tb{sub 1−x}Gd{sub x}Fe{sub 2} system

    SciTech Connect

    Adil, Murtaza; Yang, Sen Mi, Meng; Zhou, Chao Wang, Jieqiong; Zhang, Rui; Liao, Xiaoqi; Wang, Yu; Ren, Xiaobing; Song, Xiaoping; Ren, Yang

    2015-03-30

    Morphotropic phase boundary (MPB), separating two ferroic phases of different crystal symmetries, has been studied extensively for its extraordinary enhancement of piezoelectricity in ferroelectrics. Based on the same mechanism, we have designed a magnetic MPB in the pseudobinary ferromagnetic system of Tb{sub 1−x}Gd{sub x}Fe{sub 2} and the corresponding crystal structure, magnetic properties, and magnetostriction are explored. With the synchrotron x-ray diffractometry, the structure symmetry of TbFe{sub 2}-rich compositions is detected to be rhombohedral (R) and that of GdFe{sub 2}-rich compositions is tetragonal (T) below T{sub c}. With the change of concentration, the value of magnetostriction of the samples changes monotonously, while the MPB composition Tb{sub 0.1}Gd{sub 0.9}Fe{sub 2}, which corresponds to the coexistence of R and T phases, exhibits the maximum magnetization among all available compositions and superposition of magnetostriction behaviour of R and T phases. Our result of MPB phenomena in ferromagnets may provide an effective route to design functional magnetic materials with exotic properties.

  3. Evolution of lattice dynamics in ferroelectric hexagonal REInO3 (RE = Ho, Dy, Tb, Gd, Eu, Sm) perovskites

    NASA Astrophysics Data System (ADS)

    Paul, Barnita; Chatterjee, Swastika; Gop, Sumana; Roy, Anushree; Grover, Vinita; Shukla, Rakesh; Tyagi, A. K.

    2016-07-01

    Rare-earth indates emerge as one of the efficient geometric ferroelectric materials, in which the spontaneous polarization can be tuned by varying their crystal structure along the 4f rare-earth series. We report a systematic study of structural changes in hexagonal REInO3 perovskite (RE = Ho3+, Dy3+, Tb3+, Gd3+, Eu3+, Sm3+) and YInO3 of P63 cm space group by powder x-ray diffraction (XRD) and Raman scattering measurements. The crystal structure of these materials could be investigated by the Rietveld refinement of their XRD patterns. We have calculated density of states of phonons using density functional theory and examined the atomic displacements corresponding to observed Raman modes. The evolution of lattice dynamics of REInO3 has been probed by correlating various Raman modes with the structural distortion of the unit cell and the characteristics of the rare-earth ions. We report the appearance of the coupled mode in the phonon spectra. We have estimated spontaneous polarization from the structural distortion in this system and shown that it can be modulated by varying RE3+ ions in REInO3. We also report the appearance of a ferroelectric soft Raman mode, a unique characteristic of these materials.

  4. Raman spectroscopy of rare-earth orthoferrites R FeO3 (R =La, Sm, Eu, Gd, Tb, Dy)

    NASA Astrophysics Data System (ADS)

    Weber, Mads Christof; Guennou, Mael; Zhao, Hong Jian; Íñiguez, Jorge; Vilarinho, Rui; Almeida, Abílio; Moreira, Joaquim Agostinho; Kreisel, Jens

    2016-12-01

    We report a Raman scattering study of six rare-earth orthoferrites R FeO3, with R = La, Sm, Eu, Gd, Tb, Dy. The use of extensive polarized Raman scattering of SmFeO3 and first-principles calculations enable the assignment of the observed phonon modes to vibrational symmetries and atomic displacements. The assignment of the spectra and their comparison throughout the whole series allow correlating the phonon modes with the orthorhombic structural distortions of R FeO3 perovskites. In particular, the positions of two specific A g modes scale linearly with the two FeO6 octahedra tilt angles, allowing the distortion to be tracked throughout the series. At variance with literature, we find that the two octahedra tilt angles scale differently with the vibration frequencies of their respective A g modes. This behavior, as well as the general relations between the tilt angles, the frequencies of the associated modes, and the ionic radii are rationalized in a simple Landau model. The reported Raman spectra and associated phonon-mode assignment provide reference data for structural investigations of the whole series of orthoferrites.

  5. Structural characterisation of REBaCo 2O 6- δ phases ( RE = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho)

    NASA Astrophysics Data System (ADS)

    Anderson, P. S.; Kirk, C. A.; Knudsen, J.; Reaney, I. M.; West, A. R.

    2005-10-01

    REBaCo 2O 6- δ ( RE = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho) phases were prepared by solid-state reaction at 1100 °C. Post-reaction heat treatments were carried out to alter the oxygen contents, which were determined by H 2-reduction thermogravimetry. Three closely-related structure types were observed, with the general sequence: tetragonal (δ⩾0.6) to orthorhombic (0.6⩾δ⩾0.4) to tetragonal (0.4⩾δ) with increasing oxygen content. Rietveld refinement of combined X-ray and neutron powder diffraction data of NdBaCo 2O 6- δ was carried out for four values of δ. Oxygen deficiency is accommodated by partial occupancy of two sets of oxygen sites, giving a range of coordination environments for Co. Electron diffraction patterns revealed a superlattice ˜2a×4a×c with Cmmm symmetry, where a and c refer to the (pseudo) tetragonal subcell. Tweed-like ferroelastic domains were routinely observed, suggesting that compositions that appear macroscopically tetragonal by X-ray diffraction are in fact orthorhombic with a≈b.

  6. Temperature- and pressure-induced structural transitions in rare-earth-deficient ? (R = Y, Sm, Gd, Tb) Laves phases

    NASA Astrophysics Data System (ADS)

    Gratz, E.; Kottar, A.; Lindbaum, A.; Mantler, M.; Latroche, M.; Paul-Boncour, V.; Acet, M.; Barner, Cl; Holzapfel, W. B.; Pacheco, V.; Yvon, K.

    1996-10-01

    Electrical resistivity, thermal expansion, and temperature-dependent x-ray diffraction measurements on 0953-8984/8/43/026/img14 compounds give mutually consistent evidence for structural phase transitions at 740 K, 550 K, 600 K, and 450 K respectively for R = Y, Sm, Gd, Tb; 0 < x < 0.05. Arguments are given as to why most of the rare-earth - nickel compounds with the 1:2 ratio do not crystallize in the simple cubic Laves phase (C15 type) but show a superstructure of the cubic Laves phase at room temperature and at ambient pressure. This superstructure with the space group 0953-8984/8/43/026/img15 and a doubled cell parameter is characterized by ordered vacancies on the R sites. It is shown that the observed structural instabilities result in transitions to the cubic Laves phase (space group 0953-8984/8/43/026/img16), however with disordered vacancies at high temperatures. High-pressure x-ray powder diffraction experiments show that the phase transition in 0953-8984/8/43/026/img17 shifts down to room temperature for a pressure of 27 GPa.

  7. Family of defect-dicubane Ni4Ln2 (Ln = Gd, Tb, Dy, Ho) and Ni4Y2 complexes: rare Tb(III) and Ho(III) examples showing SMM behavior.

    PubMed

    Zhao, Lang; Wu, Jianfeng; Ke, Hongshan; Tang, Jinkui

    2014-04-07

    Reactions of Ln(III) perchlorate (Ln = Gd, Tb, Dy, and Ho), NiCl2·6H2O, and a polydentate Schiff base resulted in the assembly of novel isostructural hexanuclear Ni4Ln2 complexes [Ln = Gd (1), Tb (2), Dy (3), Ho (4)] with an unprecedented 3d-4f metal topology consisting of two defect-dicubane units. The corresponding Ni4Y2 (5) complex containing diamagnetic Y(III) atoms was also isolated to assist the magnetic studies. Interestingly, complexes 2 and 3 exhibit SMM characteristics and 4 shows slow relaxation of the magnetization. The absence of frequency-dependent in-phase and out-of-phase signals for the Ni-Y species suggests that the Ln ions' contribution to the slow relaxation must be effectual as previously observed in other Ni-Dy samples. However, the observation of χ″ signals with zero dc field for the Ni-Tb and Ni-Ho derivatives is notable. Indeed, this is the first time that such a behavior is observed in the Ni-Tb and Ni-Ho complexes.

  8. Low-temperature heat-capacity studies of R2Ni3Si5 (R=Pr, Nd, Sm, Gd, Tb, Dy, Ho)

    NASA Astrophysics Data System (ADS)

    Mazumdar, Chandan; Ghosh, K.; Nagarajan, R.; Ramakrishnan, S.; Padalia, B. D.; Gupta, L. C.

    1999-02-01

    We report here our low temperature (2-30 K) heat capacity, Cp measurements of R2Ni3Si5 (R=Pr, Nd, Sm, Gd-Ho). Large peaks in heat capacity data at magnetic transition temperatures (TN) confirm the bulk nature of magnetic order in these compounds. In Nd2Ni3Si5, Gd2Ni3Si5, and Dy2Ni3Si5, magnetization studies indicated only one magnetic transition, whereas, heat-capacity data show two transitions. TN of the heavier rare-earth member, Tb2Ni3Si5, showing significant deviation from de Gennes scaling is notable. Magnetic entropy, ΔS, estimated from heat-capacity data suggest that the magnetic ground state is a doublet in R2Ni3Si5 (R=Pr, Nd, Sm, Dy, Ho) and a quartet in Tb2Ni3Si5. In all the cases, ΔS, at TN is slightly less than that expected due to the suggested states, which we attribute to the occurrence of precursor effects of magnetic order above TN. Except for Gd2Ni3Si5, ΔS of the compounds does not reach the saturation limit of R ln(2J+1) even at 30 K, indicating the presence of crystalline electric field (CEF) effects. A hump in Cp is observed below TN in Gd2Ni3Si5 which is interpreted in terms of a possible amplitude-modulated magnetic spin structure.

  9. Synthesis and characterization of a BaGdF5:Tb glass ceramic as a nanocomposite scintillator for x-ray imaging.

    PubMed

    Lee, Gyuhyon; Struebing, Christian; Wagner, Brent; Summers, Christopher; Ding, Yong; Bryant, Alex; Thadhani, Naresh; Shedlock, Daniel; Star-Lack, Josh; Kang, Zhitao

    2016-05-20

    Transparent glass ceramics with embedded light-emitting nanocrystals show great potential as low-cost nanocomposite scintillators in comparison to single crystal and transparent ceramic scintillators. In this study, cubic structure BaGdF5:Tb nanocrystals embedded in an aluminosilicate glass matrix are reported for potential high performance MeV imaging applications. Scintillator samples with systematically varied compositions were prepared by a simple conventional melt-quenching method followed by annealing. Optical, structural and scintillation properties were characterized to guide the design and optimization of selected material systems, aiming at the development of a system with higher crystal volume and larger crystal size for improved luminosity. It is observed that enhanced scintillation performance was achieved by tuning the glass matrix composition and using GdF3 in the raw materials, which served as a nucleation agent. A 26% improvement in light output was observed from a BaGdF5:Tb glass ceramic with addition of GdF3.

  10. Anisotropy in the paramagnetic phase of RAl/sub 2/ cubic intermetallic compounds (R = Tb, Dy, and Er)

    SciTech Connect

    del Moral, A.; Ibarra, M.R.; Abell, J.S.; Montenegro, J.F.D.

    1987-05-01

    In this paper it is shown that the anisotropy in the paramagnetic phase is a useful characteristic when used to single out high-rank susceptibility tensor components in the paramagnetic regime of cubic crystals. Application of this technique to RAl/sub 2/ compounds (R = Tb,Dy,Er) allows the determination of longitudinal and transverse (in the form of linear combinations) fourth- and sixth-rank paramagnetic susceptibilities. The use of the fourth-rank longitudinal susceptibility allows quadrupolar pair interactions in these compounds to be probed.

  11. Magnetic anisotropy and magnetoelectric properties of Tb{sub 1-x}Er{sub x}Fe{sub 3}(BO{sub 3}){sub 4} ferroborates

    SciTech Connect

    Zvezdin, A. K.; Kadomtseva, A. M. Popov, Yu. F.; Vorob'ev, G. P.; Pyatakov, A. P.; Ivanov, V. Yu.; Kuz'menko, A. M.; Mukhin, A. A.; Bezmaternykh, L. N.; Gudim, I. A.

    2009-07-15

    Magnetic and magnetoelectric properties of ferroborate single crystals with complex composition (Tb{sub 1-x}Er{sub x}Fe{sub 3}(BO{sub 3}){sub 4}, x = 0, 0.75) and with competing exchange Tb-Fe and Er-Fe interactions are investigated. Jumps in electric polarization, magnetostriction, and magnetization are observed as a result of spin-flop transitions, as well as a considerable decrease in the critical field upon an increase in the Er concentration, in a field H{sub c} parallel to the c axis. The observed behavior of phase-transition fields is analyzed and explained using a simple model taking into account anisotropy in g factors and exchange splitting of funda-mental doublets of the easy-axis Tb{sup 3+} ion and easy-plane Er{sup 3+} ion. It is established that magnetoelectric and magnetostriction anomalies under spin-flop transitions are mainly controlled by the Tb subsystem. The Tb subsystem makes a nonmonotonic contribution {Delta}P{sub a}(H{sub a}, T) to polarization along the a axis: the value of {Delta}P{sub a} reverses its sign and increases with temperature due to the contribution from the excited states of the Tb{sup 3+} ion.

  12. Microwave sol-gel synthesis and upconversion photoluminescence properties of CaGd2(WO4)4:Er3+/Yb3+ phosphors with incommensurately modulated structure

    NASA Astrophysics Data System (ADS)

    Lim, Chang Sung; Aleksandrovsky, Aleksandr; Molokeev, Maxim; Oreshonkov, Aleksandr; Atuchin, Victor

    2015-08-01

    CaGd2-x(WO4)4:Er3+/Yb3+ phosphors with the doping concentrations of Er3+ and Yb3+ (x=Er3++Yb3+, Er3+=0.05, 0.1, 0.2 and Yb3+=0.2, 0.45) have been successfully synthesized by the microwave sol-gel method. The crystal structure of CaGd2-x(WO4)4:Er3+/Yb3+ tungstates have been refined, and upconversion photoluminescence properties have been investigated. The synthesized particles, being formed after the heat-treatment at 900 °C for 16 h, showed a well crystallized morphology. Under the excitation at 980 nm, CaGd2(WO4)4:Er3+/Yb3+ particles exhibited a strong 525-nm and a weak 550-nm emission bands in the green region and a very weak 655-nm emission band in the red region. The Raman spectrum of undoped CaGd2(WO4)4 revealed about 12 narrow lines. The strongest band observed at 903 cm-1 was assigned to the ν1 symmetric stretching vibration of WO4 tetrahedrons. The spectra of the samples doped with Er and Yb obtained under the 514.5 nm excitation were dominated by Er3+ luminescence preventing the recording of these samples Raman spectra. Concentration quenching of the erbium luminescence at 2H11/2→4I15/2 transition is weak in the range of erbium doping level xEr=0.05-0.2, while, for transition 4S3/2→4I15/2, the signs of concentration quenching become pronounced at xEr=0.2.

  13. Synthesis and photoluminescence properties of Ln3+ (Ln3+=Tb3+, Dy3+, Sm3+, Er3+)-doped Ca2Nb2O7 phosphors

    NASA Astrophysics Data System (ADS)

    Xian, Jieqiang; Yi, Shuangping; Deng, Yaomin; Zhang, Lu; Hu, Xiaoxue; Wang, Yinhai

    2016-02-01

    A series of Ln3+ (Ln3+=Tb3+/Dy3+/Sm3+/Er3+) ions doped Ca2Nb2O7 phosphors have been synthesized by high-temperature solid-state reaction. The Ln3+-doped samples are well indexed to the pure Ca2Nb2O7 phase which revealed for the X-ray diffraction (XRD) result. Under the ultraviolet light, the prepared Ca2-xNb2O7:xLn3+ (Ln3+=Tb3+/Dy3+/Sm3+/Er3+) phosphors show the characteristic cyan (Tb3+), green-white (Sm3+), yellowish (Dy3+) and green (Er3+) emissions. The energy transfer mechanisms in Ca2Nb2O7: Tb3+/Dy3+/Sm3+/Er3+ phosphors have been investigated and it deduced to be a resonant type via an electric dipole-dipole interaction. In addition, their critical distances have been calculated by concentration quenching methods. The luminescence properties of Ca2Nb2O7:Tb3+/Dy3+/Sm3+/Er3+ phosphors indicated that the Ca2Nb2O7 is a suitable host for rare earth doped laser crystal and optical materials.

  14. Fabrication of a novel nanocomposite Ag/graphene@SiO2-NaLuF4:Yb,Gd,Er for large enhancement upconversion luminescence.

    PubMed

    Yin, Dongguang; Cao, Xianzhang; Zhang, Lu; Tang, Jingxiu; Huang, Wenfeng; Han, Yanlin; Wu, Minghong

    2015-06-28

    Upconversion nanocrystals have a lot of advantages over other fluorescent materials. However, their applications are still limited due to their comparatively low upconversion luminescence (UCL). In the present study, a novel nanocomposite of Ag/graphene@SiO2-NaLuF4:Yb,Gd,Er for enhancing UCL was fabricated successfully, and its morphology, crystalline phase, composition, and fluorescent property were investigated. It is interesting to find that the Ag/graphene@SiO2-NaLuF4:Yb,Gd,Er and Ag@SiO2-NaLuF4:Yb,Gd,Er nanocomposites showed high UCL enhancements of 52- and 10-fold compared to the control of Ag-free nanocomposite SiO2-NaLuF4:Yb,Gd,Er, respectively. The enhancement of 52-fold is greater than those reported in our previous studies and some papers. Moreover, the measured life times of the Ag-presented nanocrystals were longer than that of Ag-absent counterparts. These enhancements of UCL can be ascribed to the effect of metal-enhanced fluorescence, which is caused by the enhancement of the local electric field. The UCL intensity of Ag/graphene@SiO2-NaLuF4:Yb,Gd,Er was 5.2-fold higher than that of Ag@SiO2-NaLuF4:Yb,Gd,Er, indicating that graphene presented in the fabricated nanocomposite structure favors metal-enhanced UCL. The small-sized Ag nanoparticles anchored on the graphene sheet mutually enhanced each other's polarizability and surface plasmon resonance, resulting in a big metal-enhanced UCL. This study provides a new strategy for effectively enhancing the UCL of upconversion nanocrystals. The enhancement potentially increases the overall upconversion nanocrystal detectability for highly sensitive biological, medical, and optical detections.

  15. Dual-mode, tunable color, enhanced upconversion luminescence and magnetism of multifunctional BaGdF5:Ln(3+) (Ln = Yb/Er/Eu) nanophosphors.

    PubMed

    Li, Honglan; Liu, Guixia; Wang, Jinxian; Dong, Xiangting; Yu, Wensheng

    2016-08-03

    A series of Yb(3+), Er(3+), and Eu(3+) ions doped BaGdF5 dual-mode (down-conversion (DC) and upconversion (UC)) luminescent nanophosphors were successfully prepared by a simple one-step hydrothermal method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometry (EDS), Fourier-transform infrared (FTIR) spectroscopy, photoluminescence (PL) spectroscopy, fluorescence lifetime measurements, and vibrating sample magnetometry (VSM) were utilized to characterize the samples. Under 274 nm UV light excitation, BaGd0.78-zF5:0.2Yb(3+),0.02Er(3+),zEu(3+) phosphors emitted orange emission. Under 980 nm NIR irradiation, intense up-converted visible green emissions were observed in BaGdF5:Yb(3+),Er(3+)/Eu(3+) samples. The mechanism of UC emissions involved two-photon absorption. In the Yb(3+),Er(3+),Eu(3+) co-doped BaGdF5 phosphors, the energy transfer processes from Gd(3+) to Eu(3+) and from Yb(3+) to Er(3+) were discussed. Tunable colors were visualised with the help of the Commission Internationale de L'Eclairage (CIE) chromaticity diagram and the processes responsible for the DC and UC emissions were discussed in detail. The enhanced up-conversion luminescence of Yb(3+),Er(3+)/Eu(3+) co-doped BaGdF5 nanophosphors (NPs) was realized by modifying the trisodium citrate (Cit(3-)) surfactant. Moreover, the as-prepared samples exhibited paramagnetic properties at room temperature. This type of multifunctional orange-green emitting nanophosphor has promising applications in solid state lasers, lighting, MRI, anti-counterfeiting, biolabels, and so on.

  16. Pressure dependence of the charge-density-wave and superconducting states in GdTe3, TbTe3, and DyTe3

    DOE PAGES

    Zocco, D. A.; Hamlin, J. J.; Grube, K.; ...

    2015-05-14

    Here, we present electrical resistivity and ac-susceptibility measurements of GdTe3, TbTe3 and DyTe3 performed under pressure. An upper charge-density-wave (CDW) is suppressed at a rate of dTCW,1/dP~ –85K/GPa. For TbTe3 and DyTe3, a second CDW below TCDW,2 increases with pressure until it reaches the TCDW,1(P) line. For GdTe3, the lower CDW emerges as pressure is increased above ~1GPa. As these two CDW states are suppressed with pressure, superconductivity (SC) appears in the three compounds at lower temperatures. Ac-susceptibility experiments performed on TbTe3 provide compelling evidence for bulk SC in the low-pressure region of the phase diagram. We provide measurements ofmore » superconducting critical fields and discuss the origin of a high-pressure superconducting phase occurring above 5 GPa.« less

  17. Manifestation of π-π stacking interactions in luminescence properties and energy transfer in aromatically-derived Tb, Eu and Gd tris(pyrazolyl)borate complexes.

    PubMed

    Mikhalyova, Elena A; Yakovenko, Anastasiya V; Zeller, Matthias; Kiskin, Mikhail A; Kolomzarov, Yuriy V; Eremenko, Igor L; Addison, Anthony W; Pavlishchuk, Vitaly V

    2015-04-06

    The three new complexes Tp(Py)Ln(CH3CO2)2(H2O) (Ln = Eu (1), Gd(2), or Tb (3)) were prepared and characterized crystallographically. In the crystal lattices of these complexes, separate molecules are connected in infinite chains by π-stacking interactions. Complexes 1 and 3 display intense photoluminescence and triboluminescence (red and green respectively), while compound 3 exhibits electroluminescence commencing at 9 V in an ITO/PVK/3/Al device (ITO = indium-tin oxide, PVK = poly(N-vinylcarbazole)). A series of Eu/Tb-doped Gd compounds was prepared by cocrystallization from mixtures of 1 and 2 or 2 and 3, respectively. It was shown that π-stacking interactions are involved in increasing the efficiency of energy transfer from the gadolinium complex to emitting [Tp(Py)Eu](2+) or [Tp(Py)Tb](2+) centers, and this energy transfer occurs through hundreds of molecules, resembling the process of energy harvesting in chloroplast stacks.

  18. Up-converted ultraviolet luminescence of Er3+:BaGd2ZnO5 phosphors for healthy illumination

    NASA Astrophysics Data System (ADS)

    Zhang, Ya; Cui, Qingzhi; Wang, Zhanyong; Liu, Gan; Tian, Tian; Xu, Jiayue

    2016-09-01

    Moderate level of exposure to the solar irradiation containing UV component is essential for health care. To incorporate the UV-emitting phosphors into the commercial YAG-based white light-emitting diode introduces the possibilities of healthy illumination to individuals' daily lives. 1 mol.% Er3+-doped BaGd2ZnO5 (BGZ) particles were synthesized via sol-gel method and efficient up-converted luminescence peaked at 380 nm was detected under 480 nm excitation. The mixed phosphors with varied mass ratio of Er3+:BGZ and Ce3+:YAG particles were encapsulated to form LEDs. The study of the LEDs indicated that the introduction of BGZ component favored the enhancement of color-rendering index and the neutralization of the white light emitting. The WLED with the BGZ/YAG ratio of 8:2 was recommendable for its excellent overall white light luminous performances and UV intensity of 84.55 mW/cm2. The UV illumination dose of the WLEDs with mixed YAG and BGZ was controllable by adjusting the ratio, the illumination distance and the illumination time. Er3+:BGZ phosphors are promising UVemitting phosphors for healthy indoor illumination.

  19. Bright white upconversion emission from Yb(3+), Er(3+), and Tm(3+)-codoped Gd(2)O(3) nanotubes.

    PubMed

    Zheng, Kezhi; Zhang, Daisheng; Zhao, Dan; Liu, Ning; Shi, Feng; Qin, Weiping

    2010-07-21

    Yb(3+), Er(3+), and Tm(3+)-codoped Gd(2)O(3) nanotubes were synthesized via a simple wet-chemical route at low temperature and ambient pressure followed by a subsequent heat treatment at 800 degrees C. X-Ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), upconversion (UC) emission spectra, and kinetic decay were used to characterize the samples. Bright white UC luminescence in the nanotubes was observed under diode laser excitation of 980 nm. The white light consists of the blue ((1)G(4)-->(3)H(6) of Tm(3+)), green ((2)H(11/2)/(4)S(3/2)-->(4)I(15/2) of Er(3+)), and red ((4)F(9/2)-->(4)I(15/2) of Er(3+)) UC emissions. As the excitation power density changed in the range of 20-200 W cm(-2), the calculated CIE color coordinates shift only slightly and fall well within the white region. This material may be a potential candidate for applications of color displays, lighting and photonics.

  20. Luminescence and energy transfer of the color-tunable phosphor Li₆Gd(BO₃)₃:Tb³⁺/Bi³⁺, Eu³⁺.

    PubMed

    Chen, Peican; Mo, Fuwang; Guan, Anxiang; Wang, Rongfang; Wang, Guofang; Xia, Siyu; Zhou, Liya

    2016-02-01

    Bi(3+)/Tb(3+), Eu(3+) co-doped Li6Gd(BO3)3 (LGBO) phosphors were synthesized via a traditional solid-state method. Phase purity was investigated using X-ray diffraction, absorption strength of the phosphors were investigated by UV-vis absorption spectra, and the photoluminescence properties of the phosphors were studied systematically. Results showed that the emission intensity of Bi(3+), Eu(3+) co-doped LBOG was 2.76 times higher than that of Eu(3+)-doped LGBO irradiated at 275 nm, thereby implying the possibility of energy transfer from Bi(3+) to Eu(3+). The excitation spectra of Tb(3+), Eu(3+) co-doped LGBO phosphors are broader in comparison with single-doped phosphors and show tunable colors from green to yellow to orange-red when the ratio of Tb(3+) to Eu(3+) is adjusted These results demonstrate that LGBO:Tb(3+), Eu(3+) phosphors have potential use in light-emitting diodes.

  1. Characterization of conjugates of NaYF4:Yb,Er,Gd upconversion nanoparticle with aluminium phthalocyanines

    NASA Astrophysics Data System (ADS)

    Watkins, Zane; Uddin, Imran; Britton, Jonathan; Nyokong, Tebello

    2017-02-01

    NaYF4:Er/Yb/Gd upconversion nanoparticles (UCNP) capped with amino groups were covalently attached to chloro aluminium tetrasulphonated phthalocyanine (ClAlTSPc) and chloro aluminium tetracarboxy phthalocyanine (ClAlTCPc). The conjugates were characterized using different techniques such as infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). There was a decrease in the intensity of fluorescence emission spectra of the UCNPs at 658 nm in the presence of the phthalocyanines. This decrease indicates an energy transfer between the donor UCNP and conjugated accepting phthalocyanine (Pc), due to Förster resonance energy transfer (FRET). FRET efficiencies of 18% and 21% for ClAlTSPc and ClAlTCPc, respectively, were obtained. Oxygen generation by ClAlTSPc following FRET was proved.

  2. Tuning the morphology, luminescence and magnetic properties of hexagonal-phase NaGdF4: Yb, Er nanocrystals via altering the addition sequence of the precursors

    NASA Astrophysics Data System (ADS)

    Zhao, Shuwen; Xia, Donglin; Zhao, Ruimin; Zhu, Hao; Zhu, Yiru; Xiong, Yuda; Wang, Youfa

    2017-01-01

    Hexagonal-phase NaGdF4: Yb, Er upconversion nanocrystals (UCNCs) with tunable morphology and properties were successfully prepared via a thermal decomposition method. The influences of the adding sequence of the precursors on the morphology, chemical composition, luminescence and magnetic properties were investigated by transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectrometry (ICP-AES), upconversion (UC) spectroscopy, and a vibrating sample magnetometer (VSM). It was found that the resulting nanocrystals, with different sizes ranging from 24 to 224 nm, are in the shape of spheres, hexagonal plates and flakes; moreover, the composition percentage of Yb3+-Er3+ and Gd3+ ions was found to vary in a regular pattern with the adding sequence. Furthermore, the intensity ratios of emission colors (f g/r, f g/p), and the magnetic mass susceptibility of hexagonal-phase NaGdF4: Yb, Er nanocrystals change along with the composition of the nanocrystals. A positive correlation between the susceptibility and f g/r of NaGdF4: Yb, Er was proposed. The decomposition processes of the precursors were investigated by a thermogravimetric (TG) analyzer. The result indicated that the decomposition of the resolved lanthanide trifluoroacetate is greatly different from lanthanide trifluoroacetate powder. It is of tremendous help to recognize the decomposition process of the precursors and to understand the related reaction mechanism.

  3. The risk assessment of Gd2O3:Yb3+/Er3+ nanocomposites as dual-modal nanoprobes for magnetic and fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Huang, Long; Tian, Xiumei; Liu, Jun; Zheng, Cunjing; Xie, Fukang; Li, Li

    2017-02-01

    Our group has synthesized Gd2O3:Yb3+/Er3+ nanocomposites as magnetic/fluorescence imaging successfully in the previous study, which exhibit good uniformity and monodispersibility with a mean size of 7.4 nm. However, their systematic risk assessment remains unknown. In this article, the in vitro biocompatibility of the Gd2O3:Yb3+/Er3+ was assessed on the basis of cell viability and apoptosis. In vivo immunotoxicity was evaluated by monitoring the product of reactive oxygen species (ROS), clusters of differentiation (CD) markers, and superoxide dismutase (SOD) in Balb/c mice. No significant differences were found in cell viability, apoptosis, and immunotoxicity between our Gd2O3:Yb3+/Er3+ and gadodiamide which are used commonly in clinical. Few nanoprobes were localized in the phagosomes of the liver, heart, lung, spleen, kidney, brain, and tumor under the transmission electron microscopy (TEM) images. In addition, our products reveal good T1-weighted contrast enhancement of xenografted murine tumor. Therefore, the above results may contribute to the effective application of Gd2O3:Yb3+/Er3+ as molecular imaging contrast agents and dual-modal nanoprobes for cancer detection.

  4. 5 d-4 f luminescence of Nd3+, Gd3+, Er3+, Tm3+, and Ho3+ ions in crystals of alkaline earth fluorides

    NASA Astrophysics Data System (ADS)

    Radzhabov, E. A.; Prosekina, E. A.

    2011-09-01

    The vacuum ultraviolet emission spectra of alkaline-earth fluoride (CaF2, SrF2, BaF2) crystals with rare earth impurity ions (Nd, Gd, Er, Tm, Ho) have been investigated. The main luminescence bands are described well by the transitions from the lowest excited 5 d state to different 4 f levels of rare earth ions.

  5. Fluorescent property of the Gd3+-doped terbium complexes and crystal structure of [Tb(TPTZ)(H2O)6]Cl3.3H2O.

    PubMed

    Zhao, Yan-Fang; Zhao, Yong-Liang; Bai, Feng; Wei, Xiao-yan; Zhou, Yong-sheng; Shan, Mei-na; Li, Huan-huan; Ma, Rui-jun; Fu, Xiao-tao; Du, Yan

    2010-05-01

    The complex of Tb(TPTZ)Cl(3).3H(2)O was synthesized by adding the ethyl alcohol solution of TbCl(3) (1 mmol) to the solution of 2,4,6-tris-(2-pyridyl)-s-triazine(TPTZ, 1 mmol) with constant stirring. The solution which had been filtered was kept at the room temperature for 4 weeks, and then a kind of transparent crystal was formed. Besides, nine kinds of solid complexes in the different molar proportion of terbium to gadolinium had been synthesized by adopting the similar method mentioned above. It was inferred from the elemental analysis and rare earth complexometry that the composition of these complexes is (Tb(x)Gd(y))(TPTZ)Cl(3).3H(2)O (x : y = 0.9 : 0.1, 0.8 : 0.2, 0.7 : 0.3, 0.6 : 0.4, 0.5 : 0.5, 0.4 : 0.6, 0.3 : 0.7, 0.2 : 0.8, 0.1 : 0.9). The absorption spectra and photoluminescence of the complexes were determined in dimethylsulfoxide (DMF), which showed that the excitation of the complexes is mostly ligand based. The triplet state energy level of TPTZ was measured, indicating that the lowest excitation state energy level of Tb(III) and the triplet state energy level of TPTZ match well each other. The fluorescent data indicated that the fluorescent emission intensity of Tb(3+) ions would be enhanced in the complexes after terbium was doped with Gd(3+) ion. When x : y was 0.5 : 0.5, the fluorescent emission intensity was the largest. The result obtained by testing the X-ray diffraction of the monocrystal revealed that the molecular formula of the mono-crystal complex is [Tb(TPTZ)(H(2)O)(6)]Cl(3).3H(2)O. The number of metal ion coordinates is nine, and the tridentate TPTZ and six water molecules are bonded with terbium respectively. Besides, it also revealed that the monocrystal belongs to the monoclinic system, and space group Cc with the following unit cell parameters is a = 1.4785 (3) nm, b = 1.0547 (2) nm, c = 1.7385 (4) nm, beta = 94.42 (3) degrees, V = 2.7028 (9) nm(3) and Z = 4.

  6. Spin exchange interactions in hexagonal manganites RMnO3 (R = Tb, Dy, Ho, Er) epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Chen, Xiang-Bai; Thi Minh Hien, Nguyen; Lee, D.; Jang, S.-Y.; Noh, T. W.; Yang, In-Sang

    2011-08-01

    We present the results of an optical method of quantitatively estimating the spin exchange interactions in hexagonal manganites RMnO3 (R = Tb, Dy, Ho, Er) epitaxial thin films. The two in-plane (a-b plane) spin exchange integrals J1 (intratrimer Mn-Mn interaction) and J2 (intertrimer Mn-Mn interaction) are deduced from the magnon scattering peak wavenumbers. We found that J2 decreases systematically when the R ionic radius increases, while J1 is nearly independent of R ionic radius, contrary to the expectation in single crystals. We show that the R dependence of J1 could be understood in terms of the stress in the thin films. Our result indicates that the stress has stronger effect on the atomic displacement of the intratrimer Mn-Mn distance than the intertrimer Mn-Mn distance.

  7. Fabrication and evaluation of a Gd2O2S:Tb phosphor screen film for development of a CMOS-based X-ray imaging detector

    NASA Astrophysics Data System (ADS)

    Park, Ji Koon; Choi, Su Rim; Noh, Si Cheol; Jung, Bong Jae; Choi, Il Hong; Kang, Sang Sik

    2014-08-01

    In this study, Gd2O2S:Tb phosphor screen films were fabricated by using a special particle-inbinder sedimentation method. The phosphor particles used in this study were manufactured in two sizes, 2.5- μm and 5- μm. To evaluate luminescence efficiency and the spatial resolution according to the thickness, we fabricated screen films with thicknesses of 120, 150, 170, and 210- μm. The spatial resolution of the fabricated films was assessed by using an edge method to measure the modulation transfer function (MTF). From the experimental results, the spatial resolution of the mammography exposures (low-energy X-ray quality) was better than that of dental radiography (high-energy X-ray quality). Also, with the same film thickness, the screen with 2.5- μm particles had better resolution than the screen with 5.0- μm particles, but it showed about 20% lower resolution than a commercial Gd2O2S:Tb screen. In the evaluation of the results for the dependence of the spatial resolution on the film's thickness, the 120- μm-thick screen showed the highest resolution, which was similar to that of a commercial screen.

  8. Syntheses, structures, and properties of high-nuclear 3d-4f clusters with amino acid as ligand: {Gd6Cu24}, {Tb6Cu26}, and {(Ln6Cu24)2Cu} (Ln = Sm, Gd).

    PubMed

    Zhang, Jian-Jun; Hu, Sheng-Min; Xiang, Sheng-Chang; Sheng, Tianlu; Wu, Xin-Tao; Li, Ya-Min

    2006-09-04

    Four novel high-nuclear 3d-4f heterometallic clusters were obtained through the self-assembly of Ln(III), Cu(II), and amino acid ligands (2-methylalanine (mAla), glycine (Gly), and L-proline (Pro), respectively). The metal skeleton of cluster 1, [Gd6Cu24(mu3-OH)30(mAla)16(ClO4)(H2O)22].(ClO4)17.(OH)2.(H2O)2(0), may be described as a huge {Gd6Cu12} octahedron connected with 12 additional Cu(II) ions. The structure of cluster 2, Na4[Tb6Cu26(mu3-OH)30(Gly)18(ClO4)(H2O)22].(ClO4)25.(H2O)42, may be described as a {Tb6Cu24} main structure connected with two [Cu(Gly)(H2O)2]+ groups. Compounds {[Ln6Cu24(mu3-OH)30(Pro)12(Ac)6(ClO4)(H2O)13]2Cu(Pro)2}.(ClO4)18.(OH)16.(H2O)55 (Ln= Sm (3), Gd (4)) are 61-nuclear clusters, which represent the largest known 3d-4f clusters so far, the structure can be described as two {Ln6Cu24} octahedral units connected by a trans-Cu(proline)2 bridge. The electrical conductivity measurements reveal that they are temperature-sensitive semiconductors. The magnetic susceptibility measurements display that compound 4 is ferromagnetic.

  9. Intramolecular energy transfer and co-luminescence effect in rare earth ions (La, Y, Gd and Tb) doped with Eu3+ beta-diketone complexes.

    PubMed

    Li, Ying; Zhao, Yongliang

    2009-07-01

    In this paper, Eu3+ beta-diketone Complexes with the two ligands 1-(2-naphthoyl)-3, 3, 3-trifluoroacetonate (TFNB) and 2'2-bipyridine (bpy) have been synthesized. Furthermore, we reported a systematical study of the co-fluorescence effect of Eu(TFNB)3bpy doped with inert rare earth ions (La3+, Gd3+ and Y3+) and luminescence ion Tb3+. The co-luminescence effect can be found by studying the luminescence spectra of the doped complexes, which means that the existence of the other rare earth ions (La3+, Y3+, Gd3+ and Tb3+) can enhance the luminescence intensity of the central Eu3+, which may be due to the intramolecular energy transfer between rare earth ions and Eu3+. The efficient intramolecular energy transfer in all the complexes mainly occurs between the ligand TFNB and the central Eu3+. Full characterization and detail studies of luminescence properties of all these synthesized materials were investigated in relation to co-fluorescence effect between the central Eu3+ and other inert ions. Further investigation into the luminescence properties of all the complexes show that the characteristic luminescence of the corresponding Eu3+ through the intramolecular energy transfers from the ligand to the central Eu3+. Meantime, the differences in luminescence intensity of the 5D0-->7F2 transition, in the 5D0 lifetimes and in the 5D0 luminescence quantum efficiency among all the synthesized materials confirm that the doped complex Eu(0.5)Tb(0.5)(TFNB)3bpy exhibits higher 5D0 luminescence quantum efficiency and longer lifetime than the pure Eu(TFNB)3bpy complex and other materials.

  10. Optical emission, vibrational feature, and shear-thinning aspect of Tb3+-doped Gd2O3 nanoparticle-based novel ferrofluids irradiated by gamma photons

    NASA Astrophysics Data System (ADS)

    Paul, Nibedita; Hazarika, Samiran; Saha, Abhijit; Mohanta, Dambarudhar

    2013-10-01

    The present work reports on the spectroscopic and rheological properties of un-exposed and gamma (γ-) irradiated rare earth (RE) oxide nanoparticle-based ferrofluids (FFs). The FFs were produced by dispersing surfactant coated terbium (Tb3+)-doped gadolinium oxide (Gd2O3) nanoparticles in the ethanol medium and later on they were subjected to energetic γ-irradiation (1.25 MeV) at select doses (97 Gy and 2.635 kGy). The synthesized RE oxide nanoparticles were of ˜7 nm size and having a cubic crystal structure, as predicted from transmission electron microscopy and x-ray diffraction studies. Fourier transformed infra-red (FT-IR) spectra showed an adequate blue shift of the Gd-O vibrational stretching mode from a wavenumber value of ˜558 cm-1, for the un-irradiated sample to a value of ˜540 cm-1 corresponding to the irradiated sample (2.635 kGy). In contrast, photoluminescence spectra have revealed modification of defect states along with Tb3+ assisted radiative transitions. The rheology measurements have illustrated unusual shear thinning behavior of the FFs, with an apparently improved power index (s) value from 0.34 to 0.50, obtained for increasing γ-dose cases. The variation of the decay parameter with irradiation dose, as predicted from the nature of apparent viscosity curves, is attributed to the defect formation, role of impurity ions (Tb3+), and weakening of inter nanoparticle bonding. The unusual properties of the novel RE oxide based FFs may find scope in sealing and shielding elements in the radiation environment including accelerator and other related zones.

  11. Vacuum ultraviolet and near-infrared excited luminescence properties of Ca 3(PO 4) 2: RE3+, Na + ( RE=Tb, Yb, Er, Tm, and Ho)

    NASA Astrophysics Data System (ADS)

    Zhang, Jia; Wang, Yuhua; Guo, Linna; Zhang, Feng; Wen, Yan; Liu, Bitao; Huang, Yan

    2011-08-01

    Tb 3+, Yb 3+, Tm 3+, Er 3+, and Ho 3+ doped Ca 3(PO 4) 2 were synthesized by solid-state reaction, and their luminescence properties were studied by spectra techniques. Tb 3+-doped samples can exhibit intense green emission under VUV excitation, and the brightness for the optimal Tb 3+ content is comparable with that of the commercial Zn 2SiO 4:Mn 2+ green phosphor. Under near-infrared laser excitation, the upconversion luminescence spectra of Yb 3+, Tm 3+, Er 3+, and Ho 3+ doped samples demonstrate that the red, green, and blue tricolored fluorescence could be obtained by codoping Yb 3+-Ho 3+, Yb 3+-Er 3+, and Yb 3+-Tm 3+ in Ca 3(PO 4) 2, respectively. Good white upconversion emission with CIE chromaticity coordinates (0.358, 0.362) is achieved by quadri-doping Yb 3+-Tm 3+-Er 3+-Ho 3+ in Ca 3(PO 4) 2, in which the cross-relaxation process between Er 3+ and Tm 3+, producing the 1D2- 3F4 transition of Tm 3+, is found. The upconversion mechanisms are elucidated through the laser power dependence of the upconverted emissions and the energy level diagrams.

  12. A facile synthesis approach and impact of shell formation on morphological structure and luminescent properties of aqueous dispersible NaGdF4:Yb/Er upconversion nanorods

    NASA Astrophysics Data System (ADS)

    Ansari, Anees A.; Yadav, Ranvijay; Rai, S. B.

    2016-12-01

    A general facile synthesis approach was used for fabrication of highly emissive aqueous dispersible hexagonal phase upconversion luminescent NaGdF4:Yb/Er nanorods (core NRs) through metal complex decomposition process. An inert NaGdF4 and porous silica layers were grafted surrounding the surface of each and every NRs to enhance their luminescence efficiency and colloidal dispersibility in aqueous environment. Optical properties in terms of band gap energy of core, core/shell, and silica-coated core/shell/SiO2 nanorods were observed to investigate the influence of surface coating, which was gradually decreased after surface coating because of increase crystalline size after growth of inert and silica shells. The inert shell formation before silica surface grafting, upconversion luminescence intensity was greatly improved by about 20 times, owing to the effective surface passivation of the seed core and, therefore, protection of Er3+ ion in the core from the nonradiative decay caused by surface defects. Moreover, after silica coating, core/shell nanorods shows strong upconversion luminescence property similar to the hexagonal upconversion core NRs. It is expected that these NaGdF4:Yb/Er@NaGdF4@SiO2 (core/shell/SiO2) NRs including highly upconversion emissive and aqueous dispersible properties make them an ideal materials for various photonic-based potential applications such as in upconversion luminescent bioimaging, magnetic resonance imaging, and photodynamic therapy.

  13. VUV spectroscopic properties of rare-earth (RE3+ = Sm3+, Eu3+, Tb3+, Dy3+) -activated layered borate Ba6Gd9B79O138

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-Jun; Zhang, Shao-Lin; Zhang, Wei-Bin; Yang, Woochul

    2017-02-01

    Vacuum ultraviolet (VUV) spectroscopic properties of rare-earth RE3+- activated (RE3+ = Sm3+, Eu3+, Tb3+ and Dy3+) Ba6Gd9B79O138 borates (BGBO) are investigated. The strong absorption bands in the VUV range of un-doped and RE3+-activated BGBO were observed. The band range from 140 to 200 nm with a peak at about 173 nm results from the host lattice absorption. For Sm3+-activated BGBO, the charge transfer transition from O2- to Sm3+ was observed at 202 nm. In addition, it exhibits bright red emission originating from the Sm3+f-f transitions of 4G5/2 → 6HJ (J = 5/2, 7/2 and 9/2). The O2--Eu3+ charge transfer (CT) at 249 nm is observed in the excitation spectrum for Eu3+-doped BGBO. For Tb3+-activated BGBO, the broad bands around 208 and 230 nm are due to the spin-allowed and spin-forbidden f-d transitions of Tb3+, respectively. In addition, the absence of the f-d transitions of Sm3+ and Dy3+ in the excitation spectra probably due to the photo-ionization effect. It is demonstrated that there are energy transfers from the BGBO host lattice to the luminescent activators depending on the activators.

  14. Synthesis and photoluminescence characteristics of Ln3+ (Ln = Sm, Er and Dy)-doped BaGd2(MoO4)4 phosphors

    NASA Astrophysics Data System (ADS)

    Deng, Yaomin; Yi, Shuangping; Wang, Yinhai; Xian, Jieqiang

    2014-06-01

    BaGd2(MoO4)4 phosphor powders activated with the trivalent rare-earth Ln3+ (Ln = Sm, Er and Dy) were synthesized by a traditional high temperature solid-state reaction. The resulted phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. XRD results demonstrate that Ln3+-doped samples can be well indexed to the pure monoclinic scheelite-type structure BaGd2(MoO4)4. The photoluminescence investigations revealed that the phosphors exhibit apparent characteristic emissions from the 4G5/2 to 6H5/2, 7/2, 9/2 state for Sm3+, 2H11/2 and 4S3/2 state to the 4I15/2 ground state for Er3+, 4I15/2, 4F9/2 to 6H15/2 and 4F9/2 to 6H13/2 for Dy3+ under near ultraviolet excitation. BaGd1.95(MoO4)4:0.05Sm3+, BaGd1.93(MoO4)4:0.07Er3+ and BaGd1.90(MoO4)4:0.10Dy3+ emit bright orange-red, green and white light with the CIE coordinates of (0.5381, 0.4544), (0.2307, 0.6096) and (0.3314, 0.3853) respectively. The sharp emission peaks and excellent luminescence properties show that BaGd2(MoO4)4 is a suitable host for rare earth doped phosphors, which may be potentially applied in the applications of the optical materials.

  15. Cross-relaxation induced tunable emissions from the Tm(3+)/Er(3+)/Eu(3+) ions activated BaGd2O4 nanoneedles.

    PubMed

    Seeta Rama Raju, G; Pavitra, E; Yu, Jae Su

    2014-07-07

    Tm(3+), Er(3+), Tm(3+)/Er(3+), Tm(3+)/Er(3+)/Eu(3+) single, double and triple activator ion/ions doped nanocrystalline BaGd2O4 (BG) phosphors were prepared by a Pechini type sol-gel process. After annealing at 1300 °C, X-ray diffraction patterns confirmed their orthorhombic structure. Field-emission transmission electron microscope images of the BG sample indicated a nanoneedle-type morphology. Photoluminescence (PL) and cathodoluminescence (CL) measurements were utilized to establish the emission properties of rare-earth ions doped nanocrystalline BG host lattice. Under near-ultraviolet (NUV) excitations, BG:Tm(3+) and BG:Er(3+) exhibited their characteristic emissions in the blue and green regions, respectively, while BG:Tm(3+)/Er(3+) and BG:Tm(3+)/Er(3+)/Eu(3+) showed cyan and white light emissions, respectively, when doped with appropriate amounts of activator ions. In the PL, the cross-relaxation process is dominant rather than the energy transfer process. Due to the different mechanism from PL, the CL spectra showed different emission features of BG:Tm(3+)/Er(3+)/Eu(3+) phosphor. The CL spectra of BG:Tm(3+) and BG:Er(3+) established the high purity blue and green emissions, respectively. From the PL and CL investigations, the white-light emission was realized from the single-phase BG:Tm(3+)/Er(3+)/Eu(3+) phosphor under NUV and low voltage electron beam excitations.

  16. Magnetization and magnetic susceptibilities of GdH3, HoH3, ErH3 and YbH3

    NASA Technical Reports Server (NTRS)

    Flood, D. J.

    1976-01-01

    The magnetic susceptibility of powdered samples of HoH3, ErH3, GdH3 and YbH3 have been measured in the temperature range from 4.2 to 1.2 K. Two broad, local maxima are observed in the variation of chi versus T for GdH3, with maxima in (delta chi delta T) versus T at 1.8 K and 3.3 K. The inverse susceptibilities for HoH3 and ErH3 both obey a Curies-Weiss law over a limited range (4.2 to 2.6K and 4.2 to 2 K respectively) with values for the Weiss constant of -4.25 K and -1.11 K, and effective moments of 8.6 and 7.7 Bohr magnetons respectively. The susceptibility of YbH3 is independent of temperature over the range investigated. High-field magnetization measurements yield extrapolated saturation moments of 7.0 + or - 0.25 Bohr magnetons/ion for GdH3, 6.1 + or - 0.2 Bohr magnetons/ion for HoH3 and 3.74 + or - 0.11 Bohr magnetons/ion for ErH3. In addition, ErH3 exhibits a van Vleck paramagnetism in the high field region.

  17. Magnetism and Raman spectroscopy of the dimeric lanthanide iodates Ln(IO3)3 (Ln Gd, Er) and magnetism of Yb(IO3)3.

    SciTech Connect

    Sykora, Richard E.; Khalifah, Peter; Assefa, Zerihun; Albrecht-Schmitt, Thomas E.; Haire, Richard G.

    2008-01-01

    Colorless single crystals of Gd(IO3)3 or pale pink single crystals of Er(IO3)3 have been formed from the reaction of Gd metal with H5IO6 or Er metal with H5IO6 under hydrothermal reaction conditions at 180 1C. The structures of both materials adopt the Bi(IO3)3 structure type. Crystallographic data are (MoKa, l 0.71073 A ): Gd(IO3)3, monoclinic, space group P21/n, a 8.7615(3) A , b 5.9081(2) A , c 15.1232(6) A , b 96.980(1)1, V 777.03(5) Z 4, R(F) 1.68% for 119 parameters with 1930 re ections with I42s(I); Er(IO3)3, monoclinic, space group P21/n, a 8.6885(7) A , b 5.9538(5) A , c 14.9664(12) A , b 97.054(1)1, V 768.4(1) Z 4, R(F) 2.26% for 119 parameters with 1894 re ections with I42s(I). In addition to structural studies, Gd(IO3)3, Er(IO3)3, and the isostructural Yb(IO3)3 were also characterized by Raman spectroscopy and magnetic property measurements. The results of the Raman studies indicated that the vibrational pro les are adequately sensitive to distinguish between the structures of the iodates reported here and other lanthanide iodate systems. The magnetic measurements indicate that only in Gd(IO3)3 did the 3+ lanthanide ion exhibit its full 7.9 mB Hund s rule moment; Er3+ and Yb3+ exhibited ground state moments and gap energy scales of 8.3 mB/70 K and 3.8 mB/160 K, respectively. Er(IO3)3 exhibited extremely weak ferromagnetic correlations (+0.4 K), while the magnetic ions in Gd(IO3)3 and Yb(IO3)3 were fully non-interacting within the resolution of our measurements ("'0.2 K).

  18. Crystal chemistry of the orthorhombic Ln{sub 2}TiO{sub 5} compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy

    SciTech Connect

    Aughterson, Robert D.; Lumpkin, Gregory R.; Thorogood, Gordon J.; Zhang, Zhaoming; Gault, Baptiste; Cairney, Julie M.

    2015-07-15

    The crystal structures of seven samples of orthorhombic (Pnma) Ln{sub 2}TiO{sub 5} compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy were refined by Rietveld analysis of synchrotron X-ray powder diffraction (S-XRD) data. With increasing size of the lanthanide cation, the lattice parameters increase systematically: c by only ~1.5% whereas both a and b by ~6% from Dy{sub 2}TiO{sub 5} to La{sub 2}TiO{sub 5}. The mean Ti–O bond length only increases by ~1% with increasing radius of the Ln cation from Gd to La, primarily due to expansion of the pair of Ti–O{sub 3} bonds to opposite corners of the Ti–O{sub 5} square based pyramid polyhedra. For Dy{sub 2}TiO{sub 5} and Tb{sub 2}TiO{sub 5}, a significant variation in Ti–O{sub 1} and Ti–O{sub 4} bond lengths results in an increased deformation of the Ti–O{sub 5} base. The particular configuration consists of large rhombic shaped tunnels and smaller triangular tunnels along the b axis, which have implications for defect formation and migration caused by radiation damage or the ionic conductivity. - Graphical abstract: Figure: The crystallographic study of a systematic series of compounds with nominal stoichiometry Ln{sub 2}TiO{sub 5} (with Ln representing La, Pr, Nd, Sm, Gd, Tb and Dy) and orthorhombic, Pnma, symmetry shows changes in cell parameters which fit a linear trend. However, bond lengths are shown to deviate from trend with compounds containing the smaller, heavier lanthanides. - Highlights: • First fabrication and crystallographic refinement of compound Pr{sub 2}TiO{sub 5}. • First systematic study of the crystallography, using S-XRD, for Ln{sub 2}TiO{sub 5} series. • Cation to anion bonding trends and valence states are investigated. • The densities and band-gaps of the series are experimentally determined.

  19. Magnetic phase transitions in the ternary carbides Ln 2Cr 2C 3 (Ln=Tb, Ho, Er)

    NASA Astrophysics Data System (ADS)

    Reehuis, M.; Zeppenfeld, K.; Jeitschko, W.; Stüsser, N.; Ouladdiaf, B.; Loidl, A.

    2002-11-01

    The magnetic structures of the monoclinic carbides Tb 2Cr 2C 3, Ho 2Cr 2C 3 and Er 2Cr 2C 3 (space group C2/m) have been investigated by neutron powder diffraction. Below the Néel temperatures TN=49(1), 14.0(5) and 6.8(5) K the magnetic moments of the terbium, holmium and erbium atoms order antiferromagnetically within the monoclinic ac-plane, respectively. In the case of Tb 2Cr 2C 3 the magnetic structure can be described with the propagation vector k=(0 1 0) and it is stable up to the Néel temperature. The magnetic ordering in Ho 2Cr 2C 3 and Er 2Cr 2C 3 is more complex requiring different sets of coexisting wave vectors pertaining to distinct domains and comprising incommensurate regions and lock-in phase transitions. For the erbium compound the low-temperature ordering is described by the coexisting wave vectors k1=(0 0 {1}/{2}) and k2=(0 1 0) and both are stable up to Tt=5.5(3) K. Between 4.5(3) K and TN=6.8(5) K a sine-wave modulated structure with k3=(τ x,0, {1}/{2}-τ z) appears, where the vector components vary with the temperature. At 5.3 K one obtains τx=0.055(1) and τz=0.070(1). For Ho 2Cr 2C 3 the ordering associated with k1=(0 1 {1}/{2}) is stable between 1.6 K and Tt=12.7(3) K. A second type of ordering appears below TN=14.0(5) K and corresponds to a sine-wave modulated structure with k2=(τ x,0,-τ z) . The length of k2 varies from (0.8856, 0, -0.1395) at 13 K to (0.9935, 0, -0.1075) at Tt=10.2(2), where the modulated structure undergoes a transition to a square-wave one manifested by the presence of higher harmonics.

  20. Simultaneously optimizing fluorescent and paramagnetic properties of bifunctional NaGdF{sub 4}:Yb{sup 3+}/Er{sup 3+} nanocrystals by crystal field tuning

    SciTech Connect

    Wu, Xiaofeng; Hu, Shigang; Tan, Congbing; Liu, Yunxin

    2015-04-15

    Graphical abstract: Crystal field tuning is a powerful approach for simultaneously enhancing the optical and magnetic properties of lanthanide-doped NaGdF{sub 4} bi-functional nanocrystals. - Abstract: Here, we show the simultaneous enhancement of fluorescent and paramagnetic properties in bifunctional NaGdF{sub 4}:Yb{sup 3+}/Er{sup 3+} nanocrystals by crystal field tuning. The energy level splitting calculation indicates, that lanthanide ionic pairs La{sup 3+}/Lu{sup 3+} introduced into the NaGdF{sub 4} host can modify the crystal field around emitters (e.g., Er{sup 3+} and Tm{sup 3+}) and sensitizers (e.g., Yb{sup 3+}) that result in the broadening of crystal field splitting of energy levels and the abundant multi-site distribution of upconversion luminescence. The optimization of the paramagnetic properties in NaGdF{sub 4} doped with emitters and sensitizers is ascribed to the lowering of anti-ferromagnetic coupling.

  1. Passively Q-switched Er,Yb:GdAl3(BO3)4 laser with single-walled carbon nanotube based saturable absorber

    NASA Astrophysics Data System (ADS)

    Gorbachenya, K. N.; Kisel, V. E.; Yasukevich, A. S.; Prudnikova, M. B.; Maltsev, V. V.; Leonyuk, N. I.; Choi, S. Y.; Rotermund, F.; Kuleshov, N. V.

    2017-03-01

    We demonstrate a passively Q-switched Er,Yb:GdAl3(BO3)4 diode-pumped laser emitting near 1.5 µm. By using a single-walled carbon nanotube (SWCNT) as a saturable absorber, Q-switched laser pulses with energy of 0.8 µJ and duration of 130 ns at a maximum repetition rate of 500 kHz were obtained at 1550 nm.

  2. Large magnetic cooling power involving frustrated antiferromagnetic spin-glass state in R2NiSi3(R =Gd ,Er )

    NASA Astrophysics Data System (ADS)

    Pakhira, Santanu; Mazumdar, Chandan; Ranganathan, R.; Giri, S.; Avdeev, Maxim

    2016-09-01

    The ternary intermetallic compounds Gd2NiSi3 and Er2NiSi3 are synthesized in chemically single phase, which are characterized using dc magnetization, ac magnetic susceptibility, heat capacity, and neutron diffraction studies. Neutron diffraction and heat capacity studies confirm that long-range magnetic ordering coexists with the frustrated glassy magnetic components for both compounds. The static and dynamical features of dc magnetization and frequency-dependent ac susceptibility data reveal that Gd2NiSi3 is a canonical spin-glass system, while Er2NiSi3 is a reentrant spin cluster-glass system. The spin freezing temperature merges with the long-range antiferromagnetic ordering temperature at 16.4 K for Gd2NiSi3 . Er2NiSi3 undergoes antiferromagnetic ordering at 5.4 K, which is slightly above the spin freezing temperature at 3 K. The detailed studies of nonequilibrium dynamical behavior, viz., the memory effect and relaxation behavior using different protocols, suggest that both compounds favor the hierarchical model over the droplet model. A large magnetocaloric effect is observed for both compounds. Maximum values of isothermal entropy change (-Δ SM ) and relative cooling power (RCP) are found to be 18.4 J/kg K and 525 J/kg for Gd2NiSi3 and 22.6 J/kg K and 540 J/kg for Er2NiSi3 , respectively, for a change in field from 0 to 70 kOe. The values of RCP are comparable to those of the promising refrigerant materials. A correlation between large RCP and magnetic frustration is discussed for developing new magnetic refrigerant materials.

  3. Paramagnetism and improved upconversion luminescence properties of NaYF4:Yb,Er/NaGdF4 nanocomposites synthesized by a boiling water seed-mediated route

    NASA Astrophysics Data System (ADS)

    Yang, Chao-Qing; Li, Ao-Ju; Guo, Wei; Tian, Peng-Hua; Yu, Xiao-Long; Liu, Zhong-Xin; Cao, Yang; Sun, Zhong-Liang

    2016-03-01

    In a route boiling water served as reaction medium, a stoichiometric amount of rare-earth compound and fluoride are put into this system to form α-NaYF4:Yb, Er nuclei. Then prepared sample is heated at elevated temperature to improve the fluorescence intensity, and next a NaGdF4 shell grows on the surface of NaYF4 nuclei. NaYF4:Yb,Er/NaGdF4 core-shell structured upconversion nanoparticles (CSUCNPs) have been successfully synthesized by above route. The use of boiling water decreases the cubic-to-hexagonal phase transition temperature of NaYF4:Yb,Er to 350°C and increases its upconversion (UC) luminescence intensity. A heterogeneous NaGdF4 epitaxially growing on the surface of Ln3+-doped NaYF4 not only improves UC luminescence, but also creates a paramagnetic shell, which can be used as contrast agents in magnetic resonance imaging (MRI). The solution of CSUCNPs shows bright green UC fluorescence under the excitation at 980 nm in a power density only about 50 mW·cm-2. A broad spectrum with a dominant resonance at g of about 2 is observed by the electron paramagnetic resonance (EPR) spectrum of CSUCNPs. Above properties suggest that the obtained CSUCNPs could be potential candidates for dual-mode optical/magnetic bioapplications.

  4. Structural characterization of Er(3+),Yb(3+)-doped Gd2O3 phosphor, synthesized using the solid-state reaction method, and its luminescence behavior.

    PubMed

    Tamrakar, Raunak Kumar; Bisen, D P; Brahme, Nameeta

    2016-02-01

    We report the synthesis and structural characterization of Er(3+),Yb(3+)-doped Gd2O3 phosphor. The sample was prepared using the conventional solid-state reaction method, which is the most suitable method for large-scale production. The prepared phosphor sample was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermoluminescence (TL), photoluminescence (PL) and CIE techniques. For PL studies, the excitation and emission spectra of Gd2O3 phosphor doped with Er(3+) and Yb(3+) were recorded. The excitation spectrum was recorded at a wavelength of 551 nm and showed an intense peak at 276 nm. The emission spectrum was recorded at 276 nm excitation and showed peaks in all blue, green and red regions, which indicate that the prepared phosphor may act as a single host for white light-emitting diode (WLED) applications, as verified by International de I'Eclairage (CIE) techniques. From the XRD data, the calculated average crystallite size of Er(3+) and Yb(3+) -doped Gd2O3 phosphor is ~ 38 nm. A TL study was carried out for the phosphor using UV irradiation. The TL glow curve was recorded for UV, beta and gamma irradiations, and the kinetic parameters were also calculated. In addition, the trap parameters of the prepared phosphor were also studied using computerized glow curve deconvolution (CGCD).

  5. The crystal structure and luminescence of Ce3+, Tb3+ and Eu3+ in KBaLn3+(BO3)2 [Ln3+ = Sc, Y, Lu, Gd

    NASA Astrophysics Data System (ADS)

    Camardello, S. J.; Her, J. H.; Toscano, P. J.; Srivastava, A. M.

    2015-11-01

    The structure of KBaLn3+(BO3)2 [Ln3+ = Sc, Lu, Gd] was solved by Rietveld refinement of the powder X-ray diffraction data. The materials crystallize with the mineral Buetschliite [K2Ca(CO3)2] structure. The lattice parameters of KBaLn3+(BO3)2 [Ln3+ = Sc, Lu, Gd] increased with increasing ionic radius of the Ln3+ cation. In this structure, the Ln3+ cations are octahedrally coordinated. The phase formation region is dependent on the ionic radii of the Ln3+ cation. The optical properties of Ce3+, Tb3+ and Eu3+ and their dependence on the host lattice composition are investigated and discussed. It is noteworthy that the optical properties of these ions are independent of the Ln3+ cation in KBaLn3+(BO3)2. It is concluded that in this family of materials, the crystalline field strength and the covalence at the rare earth site is independent of the host lattice composition.

  6. Cytotoxic interactions of bare and coated NaGdF4:Yb(3+):Er(3+) nanoparticles with macrophage and fibroblast cells.

    PubMed

    Wysokińska, E; Cichos, J; Zioło, E; Bednarkiewicz, A; Strządała, L; Karbowiak, M; Hreniak, D; Kałas, W

    2016-04-01

    The lanthanide nano-compounds are well suited to serve as fluorescent and magnetic contrast agents and luminescent labels. Although they are considered as promising materials for bio-imaging and bio-sensors in vivo or in vitro, the amount of data is still insufficient for deep understanding the toxicity of these nanomaterials. This knowledge is of great importance in the light of growing use of the biofunctionalized nanoparticles, which raises some questions about safety of these materials. Despite lanthanide-doped NaGdF4 nanocrystals are considered as non-toxic, here we present the data showing the fatal effect of newly synthetized NaGdF4:Yb(3+):Er(3+) on chosen types of cells. Our studies were performed on two cell lines NIH3T3 fibroblasts, and RAW264.7 macrophages. Cytotoxic properties of NaGdF4:Yb(3+):Er(3+) nanoparticles and their biological effects were studied by assessing cell culture viability (MTS), proliferation and apoptosis. Bare NaGdF4:Yb(3+):Er(3+) nanocrystals were cytotoxic and induced apoptosis of both NIH3T3 and RAW264.7 cells. Their cytotoxicity was reduced by PEGylation, at the expense of minimizing direct interactions between the compound and the cell. On the other hand, coating with silica reduced cell death induced by Yb(3+):Er(3+) codoped NaGdF4 nanocrystals (but proliferation was still inhibited). The NH2-modified silica coated nanoparticles were clearly less cytotoxic than pristine nanoparticles, which suggests that both, silica and PEG coatings are reasonable approaches to decrease cytotoxicity of the nanocrystal labels. The silica and PEG shell, should also enable and simplify further bio-functionalization of these luminescent labels. The authors acknowledge the financial support from: Institute of Immunology and Experimental Therapy, Polish Academy of Sciences (IITD PAN) grant no. 3/15, Polish Ministry of Science and Higher Education, Grant N N507 499538 and from the Wroclaw Research Centre EIT+ within the project "The Application of

  7. Magnetoresistance, susceptibility and magnetization measurements on RNiBC compounds (R = Er, Ho, Dy, Tb, and Gd)

    NASA Astrophysics Data System (ADS)

    Tróchez, J. C.; Sánchez, D. R.; Giordanengo, B.; Fontes, M. B.; Continentino, Múcio; Baggio-Saitovitch, E. M.

    1997-08-01

    We studied magnetic behavior of the RNiBC compounds by magnetic and transport measurements. At low temperatures, each compound has different magnetic structure. Magnetoresistivity data are in good accordance with theory of magnetic elementary interactions, susceptibility reveals the magnetic transition and Curie Weiss behavior and magnetization shows low value of the saturation compared with the free R+3 ion that confirm that crystalline electric field is strong as in the RNi2B2C series.

  8. Enhancement of luminescence emission from GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor by Li{sup +} co-doping

    SciTech Connect

    Gavrilović, Tamara V.; Jovanović, Dragana J. Lojpur, Vesna M.; Đorđević, Vesna; Dramićanin, Miroslav D.

    2014-09-15

    This paper demonstrates the effects of Li{sup +} co-doping on the structure, morphology, and luminescence properties of GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor prepared using a high-temperature solid-state chemistry method. The GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} powders synthesized with the Li{sup +} co-dopant (in concentrations of 0, 5, 10, and 15 mol%) are characterized by X-ray powder diffraction, scanning electron microscopy, and photoluminescence spectroscopy. Structural analysis showed that powders co-doped with Li{sup +} have larger crystallite sizes and slightly smaller crystal lattice parameters than powders prepared without Li{sup +} ions. Photoluminescence down-conversion (345-nm excitation) and up-conversion (980-nm excitation) spectra show characteristic Er{sup 3+} emissions, with the most intense bands peaking at 525 nm ({sup 2}H{sub 11/2}→{sup 4}I{sub 15/2} transition) and 552 nm ({sup 4}S{sub 3/2}→{sup 4}I{sub 15/2}). The intensity of up-conversion emission from GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} is enhanced (by a factor of four) by co-doping with 5 mol% of Li{sup +} ions. The mechanisms responsible for this emission enhancement are discussed. - Graphical abstract: UC emission spectra for GdVO{sub 4}:1.5-mol% Er{sup 3+}/20-mol% Yb{sup 3+} powders co-doped with different concentrations of Li{sup +} ions, recorded under 980-nm excitation. - Highlights: • 5-mol% Li{sup +} co-doped powders have 400% enhanced up-conversion emission intensity. • 15-mol% Li{sup +} co-doping produces 40% higher emission in down-conversion. • Li{sup +} co-doped powders have larger crystallite size and smaller lattice parameters.

  9. Magnetic/upconversion fluorescent NaGdF4:Yb,Er nanoparticle-based dual-modal molecular probes for imaging tiny tumors in vivo.

    PubMed

    Liu, Chunyan; Gao, Zhenyu; Zeng, Jianfeng; Hou, Yi; Fang, Fang; Li, Yilin; Qiao, Ruirui; Shen, Lin; Lei, Hao; Yang, Wensheng; Gao, Mingyuan

    2013-08-27

    Detection of early malignant tumors remains clinically difficult; developing ultrasensitive imaging agents is therefore highly demanded. Owing to the unusual magnetic and optical properties associated with f-electrons, rare-earth elements are very suitable for creating functional materials potentially useful for tumor imaging. Nanometer-sized particles offer such a platform with which versatile unique properties of the rare-earth elements can be integrated. Yet the development of rare-earth nanoparticle-based tumor probes suitable for imaging tiny tumors in vivo remains difficult, which challenges not only the physical properties of the nanoparticles but also the rationality of the probe design. Here we report new approaches for size control synthesis of magnetic/upconversion fluorescent NaGdF4:Yb,Er nanocrystals and their applications for imaging tiny tumors in vivo. By independently varying F(-):Ln(3+) and Na(+):Ln(3+) ratios, the size and shape regulation mechanisms were investigated. By replacing the oleic acid ligand with PEG2000 bearing a maleimide group at one end and two phosphate groups at the other end, PEGylated NaGdF4:Yb,Er nanoparticles with optimized size and upconversion fluorescence were obtained. Accordingly, a dual-modality molecular tumor probe was prepared, as a proof of concept, by covalently attaching antitumor antibody to PEGylated NaGdF4:Yb,Er nanoparticles through a "click" reaction. Systematic investigations on tumor detections, through magnetic resonance imaging and upconversion fluorescence imaging, were carried out to image intraperitoneal tumors and subcutaneous tumors in vivo. Owing to the excellent properties of the molecular probes, tumors smaller than 2 mm was successfully imaged in vivo. In addition, pharmacokinetic studies on differently sized particles were performed to disclose the particle size dependent biodistributions and elimination pathways.

  10. A quantum chemistry investigation on the structure of lanthanide triflates Ln(OTf)3 where Ln = La, Ce, Nd, Eu, Gd, Er, Yb and Lu.

    PubMed

    Hannachi, Douniazed; Ouddai, Nadia; Chermette, Henry

    2010-04-21

    Density functional theory has been used to probe the electronic structure, coordination number, optical properties and the vibration spectra of monolanthanide trifluoromethane sulfonate Ln(OTf)(3) complexes where Ln = La, Ce, Nd, Eu, Gd, Er, Yb and Lu. The study reveals that the OTf group is bonded to Ln as a bidentate ligand. TDDFT calculations show that, for La(OTf)(3), MLTC and HOMO-LUMO transitions in the UV-vis are strongly bathochromically shifted compared to those of Lu(OTf)(3.).

  11. Effect of Electronic and Magnetic Valences on Phase Transition and Magnetic Properties in Co-Ni-Al-RE (RE = Gd, Dy and Er) Alloys

    NASA Astrophysics Data System (ADS)

    Ju, Jia; Lou, Shuting; Yang, Liu; Li, Tao; Hao, Shuai; Yan, Chen

    2017-02-01

    The effect of the electronic and magnetic valence state on the phase transition and magnetic properties of several Co-Ni-Al-RE (RE = Gd, Dy and Er) ferromagnetic shape memory alloys were investigated. The martensitic transformation temperature showed a distinct increase with increasing the valence electron concentration, but no obvious change in the magnetic properties of the alloys was observed with increasing the valence electron concentration. On the other hand, the magnetic properties of the sample increased with the magnetic valence number of the alloy, while no change was observed in the phase transformation temperature with the magnetic valence number.

  12. Mo{sub 2}NiB{sub 2}-type (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} and La{sub 2}Ni{sub 3}-type (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} compounds: Crystal structure and magnetic properties

    SciTech Connect

    Morozkin, A.V.; Isnard, O.; Nirmala, R.; Malik, S.K.

    2015-05-15

    earth compounds. The variation of alloy’s composition by ~3 at% i.e. from Dy{sub 2}Ni{sub 2.35}Si{sub 0.65} to Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} leads to significant transformation of crystal structure of compound with different variant of distortion of Po-type rare earth sublattice, as in Gd–Co–Ga and Er–Ni–In systems: the Mo{sub 2}NiB{sub 2}-type Gd{sub 2}Co{sub 2}Ga and La{sub 2}Ni{sub 3}-type Gd{sub 2}Co{sub 2.9}Ga{sub 0.1}, and Mo{sub 2}FeB{sub 2}-type Er{sub 2}Ni{sub 1.78}In and Mn{sub 2}AlB{sub 2}-type Er{sub 2}Ni{sub 2}In. Magnetization measurements indicate collinear ferromagnetic ordering of Mo{sub 2}NiB{sub 2}-type Gd{sub 2}Ni{sub 2.35}Si{sub 0.65} and a complex antiferromagnetic ordering with low-temperature metamagnetic nature for Mo{sub 2}NiB{sub 2}-type Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} compounds. However, neutron diffraction study in zero applied field of Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} reveals c-axis pure antiferromagnetic ordering of terbium sublattice with K=[1/2, 0, 1/2] propagation vector. Magnetization measurements indicate ferromagnetic order with coexisting antiferromagnetic interactions and low-temperature metamagnetic state for La{sub 2}Ni{sub 3}-type Dy{sub 2}Ni{sub 2.5}Si{sub 0.5}. We suggest possible polymorphism in other Mo{sub 2}FeB{sub 2}-type, Mo{sub 2}NiB{sub 2}-type, La{sub 2}Ni{sub 3}-type and Mn{sub 2}AlB{sub 2}-type rare earth compounds with corresponding change in their magnetic properties. - Highlights: • (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} compounds crystallize in the Mo{sub 2}NiB{sub 2}-type structure. • (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} compounds crystallize in the La{sub 2}Ni{sub 3}-type structure. • Gd{sub 2}Ni{sub 2.35}Si{sub 0.65} shows pure ferromagnetic type ordering. • Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} show mixed ferro-antiferromagnetic ordering. • Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} exhibit low-temperature metamagnetic

  13. Investigating the particle packing of powder phosphors for imaging instrumentation technology: an examination of Gd2O2S:Tb phosphor

    NASA Astrophysics Data System (ADS)

    Liaparinos, P.; Kalyvas, N.; Katsiotis, E.; Kandarakis, I.

    2016-10-01

    The present paper summarizes the examination of packing density effect within a phosphor layer by using Mie scattering theory and Monte Carlo simulation techniques. Light propagation in the phosphor layer was modeled by considering the following cases: (i) phosphors of different layer thickness, 100 μm (thin layer) and 200 μm (thick layer), respectively, (ii) packing density from 10% up to 90%, (iii) three values of phosphor grain diameter 100 nm, 500 nm, and 1 μm, (iii) light wavelength and complex refractive index of the phosphor grains which correspond to Gd2O2S:Tb granular phosphor (light wavelength: 545 nm refractive index real part: 2.3, refractive index imaginary part: 10-6). Results showed the linear dependence of light extinction coefficient mext with packing density for all particle diameters considered, and, in particular, the highest variations occurred for particle size 500 nm (from 1.2 μm-1 up to 10.8 μm-1, considering packing density in the range 10% - 90%). Due to this variation, the highest spatial resolution was achieved for the same grain size (500 nm) and for the highest value of packing density (90 %). However, a very significant outcome of the present investigation was that improved spatial resolution can be achieved without significant decrease in light collection efficiency, if particles in the submicrometer scale (e.g., 500 nm) with relatively low packing density (e.g., 40%) are used.

  14. Structural elucidation and magnetic behavior evaluation of rare earth (La, Nd, Gd, Tb, Dy) doped BaCoNi-X hexagonal nano-sized ferrites

    NASA Astrophysics Data System (ADS)

    Majeed, Abdul; Khan, Muhammad Azhar; Raheem, Faseeh ur; Hussain, Altaf; Iqbal, F.; Murtaza, Ghulam; Akhtar, Majid Niaz; Shakir, Imran; Warsi, Muhammad Farooq

    2016-06-01

    Rare-earth (RE=La3+, Nd3+, Gd3+, Tb3+, Dy3+) doped Ba2NiCoRExFe28-xO46 (x=0.25) hexagonal ferrites were synthesized for the first time via micro-emulsion route, which is a fast chemistry route for obtaining nano-sized ferrite powders. These nanomaterials were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), as well as vibrating sample magnetometer (VSM). The XRD analysis exhibited that all the samples crystallized into single X-type hexagonal phase. The crystalline size calculated by Scherrer's formula was found in the range 7-19 nm. The variations in lattice parameters elucidated the incorporation of rare-earth cations in these nanomaterials. FTIR absorption spectra of these X-type ferrites were investigated in the wave number range 500-2400 cm-1. Each spectrum exhibited absorption bands in the low wave number range, thereby confirming the X-type hexagonal structure. The enhancement in the coercivity was observed with the doping of rare-earth cations. The saturation magnetization was lowered owing to the redistribution of rare-earth cations on the octahedral site (3bVI). The higher values of coercivity (664-926 Oe) of these nanomaterials suggest their use in longitudinal recording media.

  15. A new type of silica-coated Gd2(CO3)3:Tb nanoparticle as a bifunctional agent for magnetic resonance imaging and fluorescent imaging

    NASA Astrophysics Data System (ADS)

    Wu, Yanli; Xu, Xianzhu; Tang, Qun; Li, Yongxiu

    2012-05-01

    We report a new type of dual modal nanoprobe to combine optical and magnetic resonance bioimaging. A simple reverse microemulsion method and coating process was introduced to synthesize silica-coated Gd2(CO3)3:Tb nanoparticles, and the particles, with an average diameter of 16 nm, can be dispersed in water. As in vitro cell imaging of the nanoprobe shows, the nanoprobe accomplishes delivery to gastric SGC7901 cancer cells successfully in a short time, as well as NCI-H460 lung cancer cells. Furthermore, it presents no evidence of cell toxicity or adverse affect on kidney cell growth under high dose, which makes the nanoprobe’s optical bioimaging modality available. The possibility of using the nanoprobe for magnetic resonance imaging is also demonstrated, and the nanoprobe displays a clear T1-weighted effect and could potentially serve as a bimodal T1-positive contrast agent. Therefore, the new nanoprobe formed from carbonate nanoprobe doped with rare earth ions provides the dual modality of optical and magnetic resonance imaging.

  16. Crystal structure, electronic and physical properties of monoclinic RECuTe2 in contrast to RECuSe2 (RE = Pr, Sm, Gd, Dy and Er)

    NASA Astrophysics Data System (ADS)

    Esmaeili, Mehdi; Forbes, Scott; Tseng, Yu-Chih; Mozharivskyj, Yurij

    2014-10-01

    The ternary tellurides RECuTe2 (RE = Gd, Dy and Er) have been synthesized, their crystal structure and charge transport properties have been investigated. The tellurides adopt a monoclinicly distorted variant (C2/m, z = 2) of the trigonal structure (P 3 bar m1, Z = 1) observed for RECuSe2 with RE = Dy, Er. The charge transport properties of RECuSe2 with RE = Pr and Sm have been also explored. While RECuTe2 display a metallic type resistivity, RECuSe2 show semiconducting properties. The room-temperature resistivities are between 0.22 and 10.5 Ω cm, with larger values observed for the selenides. Electronic structure calculations support metallic and semiconducting conductivities for the tellurides and selenides, respectively. The Seebeck coefficient indicates that the dominant charge carries are holes for all phases.

  17. Lanthanide stannate pyrochlores Ln{sub 2}Sn{sub 2}O{sub 7} (Ln = Nd, Sm, Eu, Gd, Er, Yb) nanocrystals: Synthesis, characterization, and photocatalytic properties

    SciTech Connect

    Wang, Wanjun; Liang, Shijing; Bi, Jinhong; Yu, Jimmy C.; Wong, Po Keung; Wu, Ling

    2014-08-15

    Highlights: • Ln{sub 2}Sn{sub 2}O{sub 7} (Ln = Nd, Sm, Eu, Gd, Er, Yb) are synthesized by hydrothermal method. • Light absorption edge shows red shift with decreasing Ln{sup 3+} radius from Nd{sup 3+} to Yb{sup 3+}. • Ln{sub 2}Sn{sub 2}O{sub 7} shows increasing photocatalytic activity with the decease of Ln{sup 3+} radius. • Electronic configuration reaches 4f{sup 14} under light irradiation may decrease photocatalytic activity. • Hydroxyl radicals are detected to be the major reactive species. - Abstract: A series of lanthanide stannate pyrochlores Ln{sub 2}Sn{sub 2}O{sub 7} (Ln = Nd, Sm, Eu, Gd, Er, Yb) nanocrystals have been successfully synthesized via a facile hydrothermal route. With the decrease of Ln{sup 3+} radius, the light absorption edge of the as-prepared Ln{sub 2}Sn{sub 2}O{sub 7} shows a red shift from Nd{sup 3+} to Yb{sup 3+}. Their photocatalytic activities are found to be improved with the decrease of Ln{sup 3+} radius. However, the photocatalytic activity of Yb{sub 2}Sn{sub 2}O{sub 7} is a little lower than Er{sub 2}Sn{sub 2}O{sub 7}, although the Yb{sup 3+} radius is smaller than Er{sup 3+}, which may be attributed to the full-filled electronic configuration (4f{sup 14}) of surface Yb{sup 2+} intermediates (formed by Yb{sup 3+} trapping a photo-excited electron). The crystallite size and surface area play the most important role in determining the activities. Furthermore, hydroxyl radicals are detected to be the major reactive species during the photo-degradation process. Our findings provide insights in the fabrication of highly efficient stannate photocatalysts, thus enlarging the family of photocatalysts available.

  18. Synthesis of a New Cubic Conductive Cu6O8-yMX (M=Tb, Dy, Ho, Er, Tm, Yb, Lu, X=NO3, Cl) Family

    NASA Astrophysics Data System (ADS)

    Sugise, Ryoji; Ohdan, Kyoji; Hamamoto, Toshikazu; Kashiwagi, Kouichi; Shirai, Masashi; Yazawa, Ichiro; Ihara, Hideo

    1993-07-01

    A new cubic Cu6O8-yMX family (M=Tb, Dy, Ho, Er, Tm, Yb, Lu, X=NO3, Cl) was prepared. These compounds showed metallic resistivity and paramagnetism. The Cu6O8-yMX compounds could be easily synthesized when a trivalent metal element (M) whose oxide (M2O3) has a cubic Tl2O3-type structure was used. These compounds were prepared in the thermal decomposition process of a mixed copper nitrate, copper chloride and metal element oxide solution. The lattice constants of the Cu6O8-yMX compounds were related to those of M2O3.

  19. Optical Investigations of Rare-Earth Orthochromites. III. GdCrO3 and Summary of the R' Band in RCrO3

    NASA Astrophysics Data System (ADS)

    Kojima, Norimichi; Tsujikawa, Ikuji; Tsushima, Kuniro

    1985-12-01

    Optical absorption spectrum corresponding to the 4A2g→2Eg transition of Cr3+ in GdCrO3 was studied. The R' band was observed in the lower energy side of the R exciton band. The temperature and magnetic field dependences of the R' band imply that the R' band is the combined excitation of a Cr3+ exciton and a Gd3+ spin flip induced by the isotropic part of the Cr3+-Gd3+ exchange interaction. As the summary of the successive papers, the classification of the R' band in RCrO3(R=Yb, Tm, Er, No, Dy, Tb and Gd) was undertaken.

  20. Phase Transformations in the High-Tc Superconducting Compounds, Ba2RCu3O7-δ (R = Nd, Sm, Gd, Y, Ho, and Er).

    PubMed

    Wong-Ng, W; Cook, L P; Su, H B; Vaudin, M D; Chiang, C K; Welch, D R; Fuller, E R; Yang, Z; Bennett, L H

    2006-01-01

    The phase transformation between the orthorhombic and tetragonal structures of six high-T c superconductors, Ba2RCu3O7- δ , where R = Nd, Sm, Gd, Y, Ho, and Er, and δ = 0 to 1, has been investigated using techniques of x-ray diffraction, differential thermal analysis/thermogravimetric analysis (DTA/TGA) and electron diffraction. The transformation from the oxygen-rich orthorhombic phase to the oxygen-deficient tetragonal phase involves two orthorhombic phases. A superlattice cell caused by oxygen ordering, with a' = 2a, was observed for materials with smaller ionic radius (Y, Ho, and Er). For the larger lanthanide samples (Nd, Sm, and Gd), the a' = 2a type superlattice cell was not observed. The structural phase transition temperatures, oxygen stoichiometry and characteristics of the T c plateaus appear to correlate with the ionic radius, which varies based on the number of f electrons. Lanthanide elements with a smaller ionic radius stabilize the orthorhombic phase to higher temperatures and lower oxygen content. Also, the superconducting temperature is less sensitive to the oxygen content for materials with smaller ionic radius. The trend of dependence of the phase transformation temperature on ionic radius across the lanthanide series can be explained using a quasi-chemical approximation (QCA) whereby the strain effect plays an important role on the order-disorder transition due to the effect of oxygen content on the CuO chain sites.

  1. Effect of rare-earth (Er and Gd) substitution on the magnetic and multiferroic properties of DyFe0.5Cr0.5O3

    NASA Astrophysics Data System (ADS)

    Sharma, Mohit K.; Basu, Tathamay; Mukherjee, K.; Sampathkumaran, E. V.

    2016-10-01

    We report the results of our investigations on the influence of partial substitution of Er and Gd for Dy on the magnetic and magnetoelectric properties of DyFe0.5Cr0.5O3, which is known to be a multiferroic system. Magnetic susceptibility and heat capacity data, apart from confirming the occurrence of magnetic transitions at ~121 and 13 K in DyFe0.5Cr0.5O3, bring out that the lower transition temperature only is suppressed by rare-earth substitution. Multiferroic behavior is found to persist in Dy0.4Ln0.6Fe0.5Cr0.5O3 (Ln  =  Er and Gd). There is an evidence for magnetoelectric coupling in all these materials with qualitative differences in its behavior as the temperature is changed across these two transitions. Remnant electric polarization is observed for all the compounds. The most notable observation is that electric polarization is seen to get enhanced as a result of rare-earth substitution with respect to that in DyFe0.5Cr0.5O3. Interestingly, a similar trend is seen in the magnetocaloric effect, consistent with the existence of magnetoelectric coupling. The results thus provide evidence for the tuning of magnetoelectric coupling by rare-earth substitution in this family of oxides.

  2. A co-precipitation preparation, crystal structure and photoluminescent properties of Er5%:Gd{sub 2}O{sub 3} nanorods

    SciTech Connect

    Boopathi, G. Mohan, R.; Raj, S. Gokul; Kumar, G. Ramesh

    2015-06-24

    An inexpensive preparation method is being reported for obtaining erbium doped gadolinium oxide (Er5%:Gd{sub 2}O{sub 3}) nanoscale rods. The elongated nanoscale systems, as-formed through a co-precipitation process, are characterized by using X-ray powder diffraction (XRD) patterns, scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) mapping, Ultra Violet-visible (UV-vis.) absorption spectroscopy and photoluminescence (PL) spectroscopy. In addition, the Williamson–Hall (W–H) plot is also performed to distinguish the effect of crystalline size-induced broadening and strain-induced broadening at full-width at half-maximum (FWHM) of the XRD profile. The XRD patterns of as-formed and calcined products show that the phase confirmation. As revealed from the SEM micrographs, the morphology of the products show that the rod-like nanoparticles. The EDX micrographs show that the presence of elements in our samples. The band gap values in calcined samples are found to be in the range of 3.569 eV. Upon 230 nm excitation on calcined samples, three broad emission peaks are observed from PL studies. The possible mechanism for the formation of Er5%:Gd{sub 2}O{sub 3} nanorods is briefly discussed.

  3. Triple-layered perovskite niobates CaRNb3O10 (R = La, Sm, Eu, Gd, Dy, Er, Yb, or Y): new self-activated oxides.

    PubMed

    Qin, Lin; Wei, Donglei; Huang, Yanlin; Kim, Sun Il; Yu, Young Moon; Seo, Hyo Jin

    2013-09-16

    Niobates CaRNb3O10 (R = La, Sm, Eu, Gd, Dy, Er, Yb, or Y) were prepared by conventional high-temperature solid-state reaction. The formation of a single-phase compound with triple-layered perovskite-type structure was verified through X-ray diffraction (XRD) studies. The luminescence characteristics such as photoluminescence excitation and emission spectra, X-ray-excited luminescence (XEL), Stokes shift, decay curves, and color coordinates were investigated. The niobates can be efficiently excited by UV light and present luminescence behaviors with rich luminescence colors. Under excitation by ultraviolet radiation, CaRNb3O10 (R = La, Gd, Yb, or Y) exhibits strong blue luminescence due to the self-activation center of the octahedral NbO6 groups, even at room temperature. For the materials of composition CaRNb3O10 (R = Sm, Eu, Dy, or Er), the excitation at the host band produces a characteristic luminescence of rare earth ions, indicating a host-guest energy transfer process. CaRNb3O10 (R = Eu) has the strongest luminescence intensity, which can be efficiently excitated by near UV wavelength. It could be suggested to be a potential candidate for the application on near-UV excited white LEDs.

  4. Magnetic Ground States of the Rare-Earth Tripod Kagome Lattice Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er).

    PubMed

    Dun, Z L; Trinh, J; Li, K; Lee, M; Chen, K W; Baumbach, R; Hu, Y F; Wang, Y X; Choi, E S; Shastry, B S; Ramirez, A P; Zhou, H D

    2016-04-15

    We present the structural and magnetic properties of a new compound family, Mg_{2}RE_{3}Sb_{3}O_{14} (RE=Gd,Dy,Er), with a hitherto unstudied frustrating lattice, the "tripod kagome" structure. Susceptibility (ac, dc) and specific heat exhibit features that are understood within a simple Luttinger-Tisza-type theory. For RE=Gd, we found long-ranged order (LRO) at 1.65 K, which is consistent with a 120° structure, demonstrating the importance of diople interactions for this 2D Heisenberg system. For RE=Dy, LRO at 0.37 K is related to the "kagome spin ice" physics for a 2D system. This result shows that the tripod kagome structure accelerates the transition to LRO predicted for the related pyrochlore systems. For RE=Er, two transitions, at 80 mK and 2.1 K are observed, suggesting the importance of quantum fluctuations for this putative XY system.

  5. RE2MAl6Si4 (RE = Gd, Tb, Dy; M = Au, Pt): layered quaternary intermetallics featuring CaAl2Si2-type and YNiAl4Ge2-type slabs grown from aluminum flux.

    PubMed

    Latturner, Susan E; Bilc, Daniel; Mahanti, S D; Kanatzidis, Mercouri G

    2003-12-01

    Six new intermetallic aluminum silicides--Gd(2)PtAl(6)Si(4), Gd(2)AuAl(6)Si(4), Tb(2)PtAl(6)Si(4), Tb(2)AuAl(6)Si(4), Dy(2)PtAl(6)Si(4), and Dy(2)AuAl(6)Si(4)--have been obtained from reactions carried out in aluminum flux. The structure of these compounds was determined by single-crystal X-ray diffraction. They form in space group Rthremacr;m with cell constants of a = 4.1623(3) A and c = 51.048(5) A for the Gd(2)PtAl(6)Si(4) compound. The crystal structure is comprised of hexagonal nets of rare earth atoms alternating with two kinds of layers that have been observed in other multinary aluminide intermetallic compounds (CaAl(2)Si(2) and YNiAl(4)Ge(2)). All six RE(2)MAl(6)Si(4) compounds show antiferromagnetic transitions at low temperatures (T(N) < 20 K); magnetization studies of the Dy compounds show metamagnetic behavior with reorientation of spins at 6000 G. Band structure calculations indicate that the AlSi puckered hexagonal sheets in this structure are electronically distinct from the other surrounding structural motifs.

  6. Synthesis, phase composition modification, and optical properties of Ce{sup 3+}/Tb{sup 3+} activated KGdF{sub 4} and GdF{sub 3} submicrocrystals

    SciTech Connect

    Cao Chunyan; Yang, Hyun Kyoung; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun; Kim, Kwang Ho

    2012-03-15

    Ce{sup 3+}/Tb{sup 3+} co-doped series of samples have been synthesized based on a citric acid assisted hydrothermal method. By controlling the hydrothermal treating time, the samples evolve from the Ce{sup 3+}/Tb{sup 3+} co-doped cubic phase KGdF{sub 4} with spherical morphology into the Ce{sup 3+}/Tb{sup 3+} co-doped orthorhombic phase GdF{sub 3} with rhombic shape finally. The X-ray diffraction data illustrate the phase composition modification process of the samples. The field emission scanning electron microscopy and the transmission electron microscopy images suggest the transformation in the morphology of final products. The spectra of the energy-dispersive spectroscopy reveal the constituents of the samples. And the selected area electronic diffraction patterns prove the crystalline phases of the samples. Based on previous studies and the experimental data, one possible phase composition modification process has been summarized. The photoluminescence excitation and emission spectra and the luminescent dynamic decay curves demonstrate the variations in optical properties of the Ce{sup 3+}/Tb{sup 3+} co-doped final products. - Graphical abstract: Schematic illustration for the phase composition modification from the Ce{sup 3+}/Tb{sup 3+} doped KGdF{sub 4} to the Ce{sup 3+}/Tb{sup 3+}doped GdF{sub 3} with multiform morphologies and different sizes. (C presents cubic phase, H presents hexagonal phase, and O presents orthorhombic phase.) Highlights: Black-Right-Pointing-Pointer The samples were synthesized by a hydrothermal method. Black-Right-Pointing-Pointer The samples evolved from the cubic phase KGdF{sub 4} into the orthorhombic phase GdF{sub 3}. Black-Right-Pointing-Pointer The morphology evolved from the spherical shape into the rhombic shape finally. Black-Right-Pointing-Pointer A possible phase composition modification process was summarized. Black-Right-Pointing-Pointer The optical properties of final products were compared and studied.

  7. Benefits of Silica Core-Shell Structures on the Temperature Sensing Properties of Er,Yb:GdVO4 Up-Conversion Nanoparticles.

    PubMed

    Savchuk, Oleksandr A; Carvajal, Joan J; Cascales, C; Aguiló, M; Díaz, F

    2016-03-23

    We studied the temperature-dependent luminescence of GdVO4 nanoparticles co-doped with Er(3+) (1 mol %) and Yb(3+) (20 mol %) and determined their thermal sensing properties through the fluorescence intensity ratio (FIR) technique. We also analyzed how a silica coating, in a core-shell structure, affects the temperature sensing properties of this material. Spectra were recorded in the range of biological temperatures (298-343 K). The absolute sensitivity for temperature determination calculated for the core-shell nanoparticles is double the one calculated for bare nanoparticles, achieving a thermal resolution of 0.4 K. Moreover, silica-coated nanoparticles show good dispersibility in different solvents, such as water, DMSO, and methanol. Also, they show good luminescence stability without interactions with solvent molecules. Furthermore, we also observed that the silica coating shell prevents progressive heating of the nanoparticles during prolonged excitation periods with the 980 nm laser, preventing effects on their thermometric applications.

  8. Heat capacities, magnetic properties, and resistivities of ternary RPdBi alloys where R = La, Nd, Gd, Dy, Er, and Lu

    SciTech Connect

    Riedemann, T.M.

    1996-05-01

    Over the past four and a half decades research on the rare earths, their compounds, and their alloys has yielded significant insights into the nature of materials. The rare earths can be used to systematically study a series of alloys or compounds. Magnetic ordering, crystalline fields, spin fluctuations, the magnetocaloric effect, and magnetostriction are a small sample of phenomena studied that are exhibited by the rare earth family. A significant portion of research has been conducted on the abundant RM{sub 2} and RM phases, where R is the rare earth and M is a transition metal. The natural progression of science has led to the study of related RMX ternary phases, where X is either another transition metal or semimetal. There are now over 1,000 known RMX phases. The focus of this study is on RPdBi where R = La, Nd, Gd, Dy, Er, and Lu. Their heat capacities, magnetic properties, and resistivities are studied.

  9. Microwave sol–gel synthesis and upconversion photoluminescence properties of CaGd{sub 2}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors with incommensurately modulated structure

    SciTech Connect

    Lim, Chang Sung; Aleksandrovsky, Aleksandr; Molokeev, Maxim; Oreshonkov, Aleksandr; Atuchin, Victor

    2015-08-15

    CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors with the doping concentrations of Er{sup 3+} and Yb{sup 3+} (x=Er{sup 3+}+Yb{sup 3+}, Er{sup 3+}=0.05, 0.1, 0.2 and Yb{sup 3+}=0.2, 0.45) have been successfully synthesized by the microwave sol–gel method. The crystal structure of CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} tungstates have been refined, and upconversion photoluminescence properties have been investigated. The synthesized particles, being formed after the heat-treatment at 900 °C for 16 h, showed a well crystallized morphology. Under the excitation at 980 nm, CaGd{sub 2}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} particles exhibited a strong 525-nm and a weak 550-nm emission bands in the green region and a very weak 655-nm emission band in the red region. The Raman spectrum of undoped CaGd{sub 2}(WO{sub 4}){sub 4} revealed about 12 narrow lines. The strongest band observed at 903 cm{sup −1} was assigned to the ν{sub 1} symmetric stretching vibration of WO{sub 4} tetrahedrons. The spectra of the samples doped with Er and Yb obtained under the 514.5 nm excitation were dominated by Er{sup 3+} luminescence preventing the recording of these samples Raman spectra. Concentration quenching of the erbium luminescence at {sup 2}H{sub 11/2}→{sup 4}I{sub 15/2} transition is weak in the range of erbium doping level x{sub Er}=0.05–0.2, while, for transition {sup 4}S{sub 3/2}→{sup 4}I{sub 15/2}, the signs of concentration quenching become pronounced at x{sub Er}=0.2. - Graphical abstract: CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors with the doping concentrations of Er{sup 3+} and Yb{sup 3+} (x=Er{sup 3+}+Yb{sup 3+}, Er{sup 3+}=0.05, 0.1, 0.2 and Yb{sup 3+}=0.2, 0.45) have been successfully synthesized by the microwave sol–gel method and the crystal structure refinement, and upconversion photoluminescence properties have been investigated. - Highlights: • CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb

  10. Multimodal bioimaging using rare earth doped Gd2O2S: Yb/Er phosphor with upconversion luminescence and magnetic resonance properties

    PubMed Central

    Ajithkumar, G.; Yoo, Benjamin; Goral, Dara E.; Hornsby, Peter J.; Lin, Ai-Ling; Ladiwala, Uma; Dravid, Vinayak P.; Sardar, Dhiraj K

    2013-01-01

    While infrared upconversion imaging using halide nanoparticles are so common the search for a very efficient halide free upconverting phosphors is still lacking. In this article we report Gd2O2S:Yb/Er,YbHo,YbTm systems as a very efficient alternative phosphors that show upconversion efficiency comparable or even higher than existing halide phosphors. While the majority of rare earth dopants provide the necessary features for optical imaging, the paramagnetic Gd ion also contributes to the magnetic imaging,thereby resulting in a system with bimodal imaging features. Results from imaging of the nanoparticles together with aggregates of cultured cells have suggested that imaging of the particles in living animals may be possible. In vitro tests revealed no signficant toxicity because no cell death was observed when the nanoparticles were in the presence of growing cells in culture. Measurement of the magnetization of the phosphor shows that the particles are strongly magnetic, thus making them suitable as an MRI agent. PMID:25191618

  11. Multimodal bioimaging using rare earth doped Gd2O2S: Yb/Er phosphor with upconversion luminescence and magnetic resonance properties.

    PubMed

    Ajithkumar, G; Yoo, Benjamin; Goral, Dara E; Hornsby, Peter J; Lin, Ai-Ling; Ladiwala, Uma; Dravid, Vinayak P; Sardar, Dhiraj K

    2013-03-21

    While infrared upconversion imaging using halide nanoparticles are so common the search for a very efficient halide free upconverting phosphors is still lacking. In this article we report Gd2O2S:Yb/Er,YbHo,YbTm systems as a very efficient alternative phosphors that show upconversion efficiency comparable or even higher than existing halide phosphors. While the majority of rare earth dopants provide the necessary features for optical imaging, the paramagnetic Gd ion also contributes to the magnetic imaging,thereby resulting in a system with bimodal imaging features. Results from imaging of the nanoparticles together with aggregates of cultured cells have suggested that imaging of the particles in living animals may be possible. In vitro tests revealed no signficant toxicity because no cell death was observed when the nanoparticles were in the presence of growing cells in culture. Measurement of the magnetization of the phosphor shows that the particles are strongly magnetic, thus making them suitable as an MRI agent.

  12. Synthesis and characterization of ultrafine Ln{sub 2}Ti{sub 2}O{sub 7} (Ln = Sm, Gd, Dy, Er) pyrochlore oxides by stearic acid method

    SciTech Connect

    Zhang Weiguang; Zhang Lili; Zhong Hui; Lu Lude; Yang Xujie; Wang Xin

    2010-02-15

    Stearic acid method (SAM) was developed to synthesize series of pyrochlore Ln{sub 2}Ti{sub 2}O{sub 7} (Ln = Sm, Gd, Dy, Er) nanocrystals. The synthesis process was monitored by X-ray diffraction, Thermal-gravimetric-differential thermal analysis and Fourier Transform InfraRed methods. Comparing with traditional solid-state reaction (SSR), Ln{sub 2}Ti{sub 2}O{sub 7} can be synthesized at relatively low temperature (700-800 deg. C) with shortened reaction time (2-4 h). The average particle size of Ln{sub 2}Ti{sub 2}O{sub 7} was greatly reduced (ca. 40 nm) and the BET surface area was increased (ca. 12 m{sup 2}/g) by using SAM. From the X-ray diffraction patterns, we found that Ln has an effect on the crystal structure of Ln{sub 2}Ti{sub 2}O{sub 7}, every lattice peak shifted to larger angle slightly with the increasing atomic number of Ln. Also, the lattice constant of Ln{sub 2}Ti{sub 2}O{sub 7} was calculated by Jade.5 and found it decreased along with the decrease of ionic radius of Ln{sup 3+}. The morphology of obtained Ln{sub 2}Ti{sub 2}O{sub 7} was determined by transmission electron microscopy technique. Results showed that the obtained Ln{sub 2}Ti{sub 2}O{sub 7} were all square-like and the interplanar distance of Ln{sub 2}Ti{sub 2}O{sub 7} (Ln = Sm, Gd, Dy, Er) according to (111) plane was 0.65, 0.64, 0.63, and 0.62 nm respectively, which was measured from High Resolution Transmission Electron Microscopy images. Possible reason for this phenomenon was presented.

  13. Investigations into the synthesis and fluorescence properties of Eu(III), Tb(III), Sm(III) and Gd(III) complexes of a novel bis-beta-diketone-type ligand.

    PubMed

    Luo, Yi-Ming; Chen, Zhe; Tang, Rui-Ren; Xiao, Lin-Xiang; Peng, Hong-Jian

    2008-02-01

    A novel bis-beta-diketon ligand, 1,1'-(2,6-bispyridyl)bis-3-phenyl-1,3-propane-dione (L), was designed and synthesized and its complexes with Eu(III), Tb(III), Sm(III) and Gd(III) ions were successfully prepared. The ligand and the corresponding metal complexes were characterized by elemental analysis, and infrared, mass and proton nuclear magnetic resonance spectroscopy. Analysis of the IR spectra suggested that each of the lanthanide metal ions coordinated to the ligand via the carbonyl oxygen atoms and the nitrogen atom of the pyridine ring. The fluorescence properties of these complexes in solid state were investigated and it was discovered that all of the lanthanide ions could be sensitized by the ligand (L) to some extent. In particular, the Tb(III) complex was an excellent green-emitter and would be a potential candidate material for applications in organic light-emitting devices (OLEDs) and medical diagnosis.

  14. Investigations into the synthesis and fluorescence properties of Eu(III), Tb(III), Sm(III) and Gd(III) complexes of a novel bis- β-diketone-type ligand

    NASA Astrophysics Data System (ADS)

    Luo, Yi-Ming; Chen, Zhe; Tang, Rui-Ren; Xiao, Lin-Xiang; Peng, Hong-Jian

    2008-02-01

    A novel bis- β-diketon ligand, 1,1'-(2,6-bispyridyl)bis-3-phenyl-1,3-propane-dione (L), was designed and synthesized and its complexes with Eu(III), Tb(III), Sm(III) and Gd(III) ions were successfully prepared. The ligand and the corresponding metal complexes were characterized by elemental analysis, and infrared, mass and proton nuclear magnetic resonance spectroscopy. Analysis of the IR spectra suggested that each of the lanthanide metal ions coordinated to the ligand via the carbonyl oxygen atoms and the nitrogen atom of the pyridine ring. The fluorescence properties of these complexes in solid state were investigated and it was discovered that all of the lanthanide ions could be sensitized by the ligand (L) to some extent. In particular, the Tb(III) complex was an excellent green-emitter and would be a potential candidate material for applications in organic light-emitting devices (OLEDs) and medical diagnosis.

  15. Enhancement of TbIII–CuII Single‐Molecule Magnet Performance through Structural Modification

    PubMed Central

    Heras Ojea, María José; Milway, Victoria A.; Velmurugan, Gunasekaran; Thomas, Lynne H.; Coles, Simon J.; Wilson, Claire; Wernsdorfer, Wolfgang

    2016-01-01

    Abstract We report a series of 3d–4f complexes {Ln2Cu3(H3L)2Xn} (X=OAc−, Ln=Gd, Tb or X=NO3 −, Ln=Gd, Tb, Dy, Ho, Er) using the 2,2′‐(propane‐1,3‐diyldiimino)bis[2‐(hydroxylmethyl)propane‐1,3‐diol] (H6L) pro‐ligand. All complexes, except that in which Ln=Gd, show slow magnetic relaxation in zero applied dc field. A remarkable improvement of the energy barrier to reorientation of the magnetisation in the {Tb2Cu3(H3L)2Xn} complexes is seen by changing the auxiliary ligands (X=OAc− for NO3 −). This leads to the largest reported relaxation barrier in zero applied dc field for a Tb/Cu‐based single‐molecule magnet. Ab initio CASSCF calculations performed on mononuclear TbIII models are employed to understand the increase in energy barrier and the calculations suggest that the difference stems from a change in the TbIII coordination environment (C 4v versus Cs). PMID:27484259

  16. CsR(R(6)CoI(12))2 (R = Gd, Er) and (CeI)0.26(Ce(6)MnI(9))2: two new structure types featuring R(6)Z clusters.

    PubMed

    Sweet, Lucas E; Hughbanks, Timothy

    2006-11-27

    Compounds adopting two new structure types containing discrete lanthanide clusters have been found, CsR(R6CoI12)2 (R = Gd or Er) and (CeI)0.26(Ce6MnI9)2. CsEr(Er6CoI12)2 and CsGd(Gd6CoI12)2 were synthesized in reactions of CsI, RI3, CoI2, and R metals (3:19:6:23) heated to 750 degrees C for 500 h followed by slow cooling (0.1 degrees C/min). The X-ray crystal structure of CsEr(Er6CoI12)2 was solved in the Pa3 space group with a = 18.063(2) A at 250 K (Z = 4, R1 [I > 2sigma(I)] = 0.0459). (CeI)0.26(Ce6MnI9) was synthesized by combining KI, CeI3, MnI2, and Ce metal and heating to 850 degrees C for 500 h. The single-crystal X-ray structure for (CeI)0.26(Ce6MnI9)2 was solved in the trigonal, P3 (147) space group with lattice parameters of a = 11.695(1) A and c = 10.8591(2) A (Z = 2, R1 [I > 2sigma(I)] = 0.0895). Elemental analyses (X-ray photoelectron spectroscopy (XPS) and atomic absorption spectroscopy (AAS)) were performed and show the absence of potassium in the structure. A disorder model was refined for the atoms in the large cavity. The magnetic susceptibility data for CsGd(Gd6CoI12)2 is consistent with strong intracluster ferromagnetic coupling, but intercluster antiferromagnetic coupling suppresses the susceptibility below 70 K.

  17. Strain tuning and strong enhancement of ionic conductivity in SrZrO3-RE2O3 (RE = Sm, Eu, Gd, Dy, and Er) nanocomposite films

    DOE PAGES

    Lee, Shinbuhm; Zhang, Wenrui; Khatkhatay, Fauzia; ...

    2015-06-05

    Fast ion transport channels at interfaces in thin films have attracted great attention due to a range of potential applications for energy materials and devices, for, solid oxide fuel cells, sensors, and memories. Here, it is shown that in vertical nanocomposite heteroepitaxial films of SrZrO3–RE2O3 (RE = Sm, Eu, Gd, Dy, and Er) the ionic conductivity of the composite can be tuned and strongly enhanced using embedded, stiff, and vertical nanopillars of RE2O3. With increasing lattice constant of RE2O3 from Er2O3 to Sm2O3, it is found that the tensile strain in the SrZrO3 increases proportionately, and the ionic conductivity ofmore » the composite increases accordingly, by an order of magnitude. Lastly, the results here conclusively show, for the first time, that strain in films can be effectively used to tune the ionic conductivity of the materials.« less

  18. Temperature dependence of Er{sup 3+} ionoluminescence and photoluminescence in Gd{sub 2}O{sub 3}:Bi nanopowder

    SciTech Connect

    Boruc, Zuzanna Fetliński, Bartosz; Kaczkan, Marcin; Malinowski, Michał; Gawlik, Grzegorz

    2014-06-15

    Ionoluminescence (IL) and photoluminescence (PL) of trivalent erbium ions (Er{sup 3+}) in Gd{sub 2}O{sub 3} nanopowder host activated with Bi{sup 3+} ions has been studied in order to establish the link between changes in luminescent spectra and temperature of the sample material. IL measurements have been performed with H{sub 2}{sup +} 100 keV ion beam bombarding the target material for a few seconds, while PL spectra have been collected for temperatures ranging from 20 °C to 700 °C. The PL data was used as a reference in determining the temperature corresponding to IL spectra. The collected data enabled the definition of empirical formula based on the Boltzmann distribution, which allows the temperature to be determined with a maximum sensitivity of 9.7 × 10{sup −3} °C{sup −1}. The analysis of the Er{sup 3+} energy level structure in terms of tendency of the system to stay in thermal equilibrium, explained different behaviors of the line intensities. This work led to the conclusion that temperature changes during ion excitation can be easily defined with separately collected PL spectra. The final result, which is empirical formula describing dependence of fluorescence intensity ratio on temperature, raises the idea of an application of method in temperature control, during processes like ion implantation and some nuclear applications.

  19. Preparation and spectroscopic properties of rare-earth (RE) (RE = Sm, Eu, Tb, Dy, Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) phosphate in vacuum ultraviolet region

    SciTech Connect

    Zhang, Zhi-Jun; Lin, Xiao; Zhao, Jing-Tai; Zhang, Guo-Bin

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► We report the VUV spectroscopic properties of rare-earth ions in K{sub 2}LnZr(PO{sub 4}){sub 3}. ► The O{sup 2−}-Eu{sup 3+} charge transfer bands at about 220 nm have been observed. ► The 4f–5d spin-allowed and spin-forbidden transitions of Tb{sup 3+} have been observed. ► There is energy transfer between the host and rare-earth activators. -- Abstract: Rare earth (RE = Sm, Eu, Tb, Dy and Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) have been synthesized by solid-state reaction method, and their vacuum ultraviolet (VUV) excitation luminescent characteristics have been investigated. The band in the wavelength range of 130–157 nm and the other one range from 155 to 216 nm with the maximum at about 187 nm in the VUV excitation spectra of these compounds are attributed to the host lattice absorption and O–Zr charge transfer transition, respectively. The charge transfer bands (CTB) of O{sup 2−}-Sm{sup 3+}, O{sup 2−}-Dy{sup 3+} and O{sup 2−}-Tm{sup 3+}, in Sm{sup 3+}, Dy{sup 3+} and Tm{sup 3+}-activated samples, have not been obviously observed probably because the 2p electrons of oxygen are tightly bound to the zirconium ion in the host lattice. For Eu{sup 3+}-activated samples, the relatively weak O{sup 2−}-Eu{sup 3+} CTB at about 220 nm is observed. And for Tb{sup 3+}-activated samples, the bands at 223 and 258 nm are related to the 4f-5d spin-allowed and spin-forbidden transitions of Tb{sup 3+}, respectively. It is observed that there is energy transfer between the host lattice and the luminescent activators (e.g. Eu{sup 3+}, Tb{sup 3+}). From the standpoint of luminescent efficiency, color purity and chemical stability, K{sub 2}GdZr(PO{sub 4}){sub 3}:Sm{sup 3+}, Eu{sup 3+}, Tb{sup 3+} are attractive candidates for novel yellow, red, green-emitting PDP phosphors.

  20. Magnetism and Raman spectroscopy of the dimeric lanthanide iodates Ln(IO{sub 3}){sub 3} (Ln=Gd, Er) and magnetism of Yb(IO{sub 3}){sub 3}

    SciTech Connect

    Sykora, Richard E. Khalifah, Peter; Assefa, Zerihun; Albrecht-Schmitt, Thomas E.; Haire, Richard G.

    2008-08-15

    Colorless single crystals of Gd(IO{sub 3}){sub 3} or pale pink single crystals of Er(IO{sub 3}){sub 3} have been formed from the reaction of Gd metal with H{sub 5}IO{sub 6} or Er metal with H{sub 5}IO{sub 6} under hydrothermal reaction conditions at 180 deg. C. The structures of both materials adopt the Bi(IO{sub 3}){sub 3} structure type. Crystallographic data are (MoK{alpha}, {lambda}=0.71073 A): Gd(IO{sub 3}){sub 3}, monoclinic, space group P2{sub 1}/n, a=8.7615(3) A, b=5.9081(2) A, c=15.1232(6) A, {beta}=96.980(1){sup o}, V=777.03(5) Z=4, R(F)=1.68% for 119 parameters with 1930 reflections with I>2{sigma}(I); Er(IO{sub 3}){sub 3}, monoclinic, space group P2{sub 1}/n, a=8.6885(7) A, b=5.9538(5) A, c=14.9664(12) A, {beta}=97.054(1){sup o}, V=768.4(1) Z=4, R(F)=2.26% for 119 parameters with 1894 reflections with I>2{sigma}(I). In addition to structural studies, Gd(IO{sub 3}){sub 3}, Er(IO{sub 3}){sub 3}, and the isostructural Yb(IO{sub 3}){sub 3} were also characterized by Raman spectroscopy and magnetic property measurements. The results of the Raman studies indicated that the vibrational profiles are adequately sensitive to distinguish between the structures of the iodates reported here and other lanthanide iodate systems. The magnetic measurements indicate that only in Gd(IO{sub 3}){sub 3} did the 3+ lanthanide ion exhibit its full 7.9 {mu}{sub B} Hund's rule moment; Er{sup 3+} and Yb{sup 3+} exhibited ground state moments and gap energy scales of 8.3 {mu}{sub B}/70 K and 3.8 {mu}{sub B}/160 K, respectively. Er(IO{sub 3}){sub 3} exhibited extremely weak ferromagnetic correlations (+0.4 K), while the magnetic ions in Gd(IO{sub 3}){sub 3} and Yb(IO{sub 3}){sub 3} were fully non-interacting within the resolution of our measurements ({approx}0.2 K). - Graphical abstract: Three f-element iodates Ln(IO{sub 3}){sub 3} (Ln=Gd, Er, Yb), all containing the Bi(IO{sub 3}){sub 3} structure type, were characterized by Raman spectroscopy and magnetic property measurements

  1. Symmetry-Breaking Transitions in RECuAs2-xPx (RE=Sm, Gd, Ho, and Er)

    SciTech Connect

    Mozharivskyj, Yurij

    2002-01-01

    Structural changes resulting in lower symmetries can be understood in terms of electronic instabilities and Coulomb interactions. The interplay of these two interrelated factors is complicated and difficult to analyze. The RECuAs2-xP x phases, because of the variation in the chemical content (As/P substitution), allow, with the aid of band structures, Madelung energies and Landau theory, a partial unraveling of the forces important in the symmetry-breaking transitions in RECuAs2-xP x (RE = Sm, Gd, Ho and Er). Distortions of the P layers in SmCu1.15P2, GdCuP2.20 and ErCuP2 are usefully thought of as generalized Peierls distortions, i.e., they lower the electronic (and total) energy and lead to more stable structures. On the other hand, the P4/nmm → Pmmn transitions, which are observed in all studied arsenophosphide series and occur upon substitution of P for As, originate from the B1g vibrational mode and are structural adaptations to smaller P atoms. These transitions provide tighter atomic packing and better Coulomb interactions. Configurational contribution to the entropy becomes important in stabilizing the mixed occupancy in the RECuAs 2-xP x arsenophosphides. While geometric and electronic factors favor separation of the As and P atoms over two different crystallographic sites, configurational entropy stabilizes the As/P mixing on these two sites.;Progress in the research on RECuAs2-xP x was dependent upon the ability of Landau theory to predict, explain and dismiss structural models and transitions. The space group Pmmn (arising from the B 1g vibrational mode) in all mixed arsenophosphides and the existence of these mixed arsenophosphides followed from the analysis of GdCuAs 2 and GdCuP2, using Landau theory. The impossibility of obtaining the high-symmetry structure (P4/nmm) and the low symmetry structure

  2. Ultrasmall, water dispersible, TWEEN80 modified Yb:Er:NaGd(WO4)2 nanoparticles with record upconversion ratiometric thermal sensitivity and their internalization by mesenchymal stem cells.

    PubMed

    Cascales, Concepcion; Paino, Carlos; Bazán, Eulalia; Zaldo, Carlos

    2017-03-21

    This work presents the synthesis by coprecipitation of diamond shaped Yb:Er:NaGd(WO4)2 crystalline nanoparticles (NPs) with diagonal dimensions in the 5-7 nm × 10-12 nm range which have been modified with TWEEN80 for their dispersion in water, and their interaction with mesenchymal stem cells (MSCs) proposed as cellular NP vehicles. These NPs belong to a large family of tetragonal Yb:Er:NaT(XO4)2 (T=Y, La, Gd, Lu; X= Mo, W) compounds with green (2H11/2+4S3/24I15/2) Er-related upconversion (UC) efficiency comparable to that of Yb:Er:β-NaYF4 reference compound, but with a ratiometric thermal sensitivity (S) 2.5-3.5 times larger than that of the fluoride. At the temperature range of interest for biomedical applications (~293-317 K / 20-44 ºC) S= 108-118 × 10-4 K-1 for 20at%Yb:5at%Er:NaGd(WO4)2 NPs, being the largest values so far reported using the 2H11/2/4S3/2 Er intensity ratiometric method. Cultured MSCs, incubated with these water NP emulsions, internalize and accumulate the NPs enclosed in endosomes/lysosomes. Incubations with up to 10 μg of NPs per ml of culture medium maintain cellular metabolism at 72 h. A thermal assisted excitation path is discussed as responsible for the UC behavior of Yb:Er:NaT(XO4)2 compounds.

  3. Preparation and Dielectric Measurements of the Rare Earth Green Phases R2BaCuO(5-x) (R = Y, Sm, Gd, Dy, Ho, Er, Yb)

    NASA Technical Reports Server (NTRS)

    Gonzalez-Titman, Carlos

    1994-01-01

    It has been demonstrated that R2BaCuO(5-x) (R = Y, Sm, Gd, Dy, Ho, Er, Yb) does not undergo significant densification unless the sintering temperatures are near the incongruent melting point or the sintering times are long. Good quality powders of Y2BaCuO(5-x) have been synthesized by using oxide raw materials or precursors such as acetates and nitrates. The acetates- and the nitrates-derived yttrium green phase resulted in finer particle sizes, acceptable dielectric properties and lower melting temperatures than those processed via oxide raw materials. The hot pressing technique has been employed to produce a dense R2BaCuO(5-x) (R=Y,Gd) substrate with satisfactory dielectric properties. Reactivity to reducing conditions, i.e. graphite die, limited the optimization of the properties. A high sensitivity to the annealing atmosphere has been demonstrated in Y2BaCuO,.,,. Oxygen treatment at 950 OC has been shown to improve the dielectric properties while treatment in nitrogen, at the same temperature, degraded desirable properties. A high sensitivity to the annealing atmosphere has been demonstrated in Y2BaCuO(5-x). Oxygen treatment at 950 C has been shown to improve the dielectric properties while treatment in nitrogen, at the same temperature, degraded desirable properties. The dielectric constants of the rare earth green phases R2BaCuO(5-x) were found to be low. Relaxation peaks were detected at low temperatures (T less than 150 K) and at high temperatures (150 less than T greater than 420 K). The dielectric losses and conductivities at 77 K were measured to be in the range of 10(exp -4) and 10(exp -12) (Omega-cm)(exp -1), respectively. Many parameters were found to exhibit dependencies on the rare earth cation sizes.

  4. Origin of periodic domain structure in Er{sup 3+}-doped beta'-(Sm,Gd){sub 2}(MoO{sub 4}){sub 3} crystal lines patterned by laser irradiations in glasses

    SciTech Connect

    Suzuki, Futoshi; Honma, Tsuyoshi; Komatsu, Takayuki

    2010-04-15

    Er{sup 3+}-doped beta'-(Sm,Gd){sub 2}(MoO{sub 4}){sub 3} crystal lines are patterned on the surface of Er{sub 2}O{sub 3}-Gd{sub 2}O{sub 3}-Sm{sub 2}O{sub 3}-MoO{sub 3}-B{sub 2}O{sub 3} glasses by continuous-wave Yb:YVO{sub 4} laser irradiations (wavelength: 1080 nm, power: 1.3 W, scanning speeds: 5 {mu}m/s), and the origin of the periodicity of self-organized domain structures with high and low refractive index regions in crystal lines is examined from polarized optical microscope (POM) observations, micro-Raman scattering spectrum, and photoluminescence spectrum measurements. It is found that the periodicity of domain structures changes largely depending on Er{sub 2}O{sub 3} content, i.e., the length of high (bright color in POM observations) and low (dark color) refractive index regions increases with increasing Er{sub 2}O{sub 3} content and homogeneous crystal lines with no periodic domain structures are patterned in Er{sub 2}O{sub 3}-Sm{sub 2}O{sub 3}-MoO{sub 3}-B{sub 2}O{sub 3} glass with no Gd{sub 2}O{sub 3}. Considering that the degree of ferroelasticities in beta'-(Sm,Gd){sub 2}(MoO{sub 4}){sub 3} crystals decreases due to the incorporation of Er{sup 3+} ions, it is demonstrated that the origin of periodic domain structures in laser-patterned lines is due to spontaneous strains in ferroelastic beta'-(Sm,Gd){sub 2}(MoO{sub 4}){sub 3} crystals. - Graphical abstract: This figure shows the polarized optical photographs (top view) for the lines patterned by laser irradiations with the power of P=1.3 W and the scanning speed of S=5 {mu}m/s in xEr{sub 2}O{sub 3}-(18.25-x)Gd{sub 2}O{sub 3}-3Sm{sub 2}O{sub 3}-63.75MoO{sub 3}-15B{sub 2}O{sub 3} (mol%) glasses. This figure indicates that the periodicity of domain structures in beta'-(Sm,Gd){sub 2}(MoO{sub 4}){sub 3} crystal lines, i.e., the lengths of bright (high refractive index) and dark (low refractive index) color regions, changes depending on the amount of Er{sub 2}O{sub 3} addition. It is demonstrated that the

  5. Effect of Er, Gd, and Nd Co-Dopants on the Properties of Sm-Doped Ceria Electrolyte for IT-SOFC

    NASA Astrophysics Data System (ADS)

    Arabacı, Aliye

    2017-02-01

    Doped ceria electrolytes of Ce0.8Sm0.20O1.90 (SDC), Ce0.8Er0.08Sm0.12O1.90 (ESDC), Ce0.8Gd0.08Sm0.12O1.90 (GSDC), and Ce0.8Nd0.08Sm0.12O1.90 (NSDC) were prepared by a citric-nitrate combustion process. The thermal decomposition of the precursor was investigated by simultaneous thermogravimetric analysis and differential thermal analysis experiments. The phase structure of the calcined and sintered powders was characterized by X-ray diffraction analysis. All of the samples were fluorite-type ceria-based solid solutions. The calcined and sintered powders were also characterized by Fourier transform infrared spectroscopy. Scanning electron microscopy was used to characterize the samples after calcination and sintering. A relative density over 95 percent of the theoretical density was achieved after the sintering process. Electrical conductivities of the sintered samples were measured using the impedance spectra method. The highest ionic conductivity value was found to be 5.28 × 10-2 S cm-1 at 1023 K (750 °C) for GSDC sintered at 1673 K (1400 °C) for 6 hours.

  6. EPR, magnetization, and resistivity studies in doped (4-f or 3-d ions) and undoped RBa2Cu3Oy high TC superconductors (R=Y,Pr,Nd,Eu,Gd,Ho,Er, or Yb) (abstract)

    NASA Astrophysics Data System (ADS)

    Vier, D. C.; Smyth, J. F.; Salling, C. T.; Schultz, S.; Dalichaouch, Y.; Lee, B. W.; Yang, K. N.; Torikachvili, M.; Maple, M. B.; Oseroff, S. B.; Fisk, Z.; Thompson, J. D.; Smith, J. L.; Zirngiebl, E.

    1988-04-01

    We have measured electron paramagnetic resonance (EPR), resistivity, and dc susceptibility from 2 to 300 K for the oxide high Tc superconductors (R)Ba2Cu3Oy (R=Y,Pr,Nd,Eu,Gd,Ho,Er,Tm, or Yb). Selected systems were doped with 3-d ions (Cr,Mn,Fe,Ni,Co, or Zn) or 4-f ions (Gd or Er) which presumably substitute for the Cu or R site, respectively. In the systems studied we have observed an EPR line at low temperatures (T<40 K), which exhibits an increase in intensity and decrease in field for resonance as the temperature is lowered. The ESR linewidth is also temperature dependent and exhibits a minimum at about 15 K. An additional EPR line that can be associated with a Gd3+, Mn2+ or Er3+ ion was observed for those samples where these ions were present as dilute impurities. In some of the samples another EPR signal is observed with properties that depend on sample preparation conditions. The behavior and origin of all lines will be discussed. The variation of Tc with concentration of the added impurities over the range (1%-15%) will also be presented, and compared with previous studies in other superconducting systems.

  7. Detecting the origin of luminescence in Er3+-doped hexagonal Na1.5Gd1.5F6 phosphors.

    PubMed

    Wang, Xiangfu; Bu, Yanyan; Yan, Xiaohong; Cai, Peiqing; Wang, Jing; Qin, Lin; Vu, Thiquynh; Seo, Hyo Jin

    2016-11-15

    Understanding site-selective fluorescence is one of valuable importance for spectrum modulation. In this Letter, we observed the existence of two non-equivalent Gd-activated crystallographic sites in an Er3+-doped hexagonal Na1.5Gd1.5F6 phosphor. It is proved that two green emissions from the S3/24 level separately originate from the Gd1 (540 nm) and Na2/Gd2 (550-555 nm) crystallographic sites, and the 657 nm red emission from the F9/24 level only originates from Na2/Gd2 site through using the time-resolved luminescence spectra. The 142.2% absolute enhancement of the red emission is realized through the synergistic effect of ultraviolet downconversion and infrared upconversion induced by the 370 nm and 1.54 μm dual-mode excitation.

  8. Hydrothermal synthesis and luminescence properties of hierarchical SrF{sub 2} and SrF{sub 2}:Ln{sup 3+} (Ln = Er, Nd, Yb, Eu, Tb) micro/nanocomposite architectures

    SciTech Connect

    Peng, Jing; Hou, Suying; Liu, Xianchun; Feng, Jing; Yu, Xiaodan; Xing, Yan; Su, Zhongmin

    2012-02-15

    Graphical abstract: Uniform SrF{sub 2} and SrF{sub 2}:Ln{sup 3+} (Ln = Er, Nd, Yb, Eu, Tb) hierarchical microsphere assembled by numerous nanoplates have been successfully synthesized via a facile hydrothermal process in the presence of chelating reagent. Highlights: Black-Right-Pointing-Pointer Uniform SrF{sub 2} and SrF{sub 2}:Ln{sup 3+} (Ln = Er, Nd, Yb, Eu, Tb) hierarchical microsphere were obtained by a simple hydrothermal method. Black-Right-Pointing-Pointer The reaction time, chelating reagent and F source play important roles for the formation of hierarchical microspheres. Black-Right-Pointing-Pointer The luminescence properties of lanthanide ion-doped SrF{sub 2} hierarchical microstructures were discussed. -- Abstract: Highly uniform SrF{sub 2} and SrF{sub 2}:Ln{sup 3+} (Ln = Er, Nd, Yb, Eu, Tb) hierarchical microspheres assembled by 2D nanoplates have been successfully synthesized by a facile and friendly hydrothermal route. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra were used to characterize the samples. The experimental results indicate that reaction time and chelating reagent play a key role in forming the hierarchical microspheres. The formation mechanism was proposed based on the evolution of this morphology as a function of hydrothermal time. The near-infrared luminescence of lanthanide ions (Er, Nd, and Yb) doped SrF{sub 2} microspheres were discussed in detail. In addition, the as-obtained SrF{sub 2}:Eu{sup 3+} sample exhibits orange-red emission centered at 590 nm under excitation at 393 nm, while the SrF{sub 2}:Tb{sup 3+} exhibits a strong green emission at 540 nm. The as-synthesized SrF{sub 2}:Ln{sup 3+} luminescent microspheres might find some potential applications in areas of photoluminescence, telecommunication and laser emission.

  9. TB Terms

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Tuberculosis (TB) Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Tuberculosis Basic TB Facts How TB Spreads Latent TB ...

  10. Vacuum ultraviolet and near-infrared excited luminescence properties of Ca{sub 3}(PO{sub 4}){sub 2}:RE{sup 3+}, Na{sup +} (RE=Tb, Yb, Er, Tm, and Ho)

    SciTech Connect

    Zhang Jia; Wang Yuhua; Guo Linna; Zhang Feng; Wen Yan; Liu Bitao; Huang Yan

    2011-08-15

    Tb{sup 3+}, Yb{sup 3+}, Tm{sup 3+}, Er{sup 3+}, and Ho{sup 3+} doped Ca{sub 3}(PO{sub 4}){sub 2} were synthesized by solid-state reaction, and their luminescence properties were studied by spectra techniques. Tb{sup 3+}-doped samples can exhibit intense green emission under VUV excitation, and the brightness for the optimal Tb{sup 3+} content is comparable with that of the commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+} green phosphor. Under near-infrared laser excitation, the upconversion luminescence spectra of Yb{sup 3+}, Tm{sup 3+}, Er{sup 3+}, and Ho{sup 3+} doped samples demonstrate that the red, green, and blue tricolored fluorescence could be obtained by codoping Yb{sup 3+}-Ho{sup 3+}, Yb{sup 3+}-Er{sup 3+}, and Yb{sup 3+}-Tm{sup 3+} in Ca{sub 3}(PO{sub 4}){sub 2}, respectively. Good white upconversion emission with CIE chromaticity coordinates (0.358, 0.362) is achieved by quadri-doping Yb{sup 3+}-Tm{sup 3+}-Er{sup 3+}-Ho{sup 3+} in Ca{sub 3}(PO{sub 4}){sub 2}, in which the cross-relaxation process between Er{sup 3+} and Tm{sup 3+}, producing the {sup 1}D{sub 2}-{sup 3}F{sub 4} transition of Tm{sup 3+}, is found. The upconversion mechanisms are elucidated through the laser power dependence of the upconverted emissions and the energy level diagrams. - Graphical abstract: The CPO:0.25Tb{sup 3+}, 0.25Na{sup +} exhibits a comparable brightness to the commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+} upon 147 nm excitation. Good white light color is achieved in CPO:Yb{sup 3+}-Tm{sup 3+}-Er{sup 3+}-Ho{sup 3+} under 980 nm excitation. Highlights: > Ca{sub 3}(PO{sub 4}){sub 2}:Tb{sup 3+},Na{sup +} exhibits a comparable brightness with commercial Zn{sub 2}SiO{sub 4}:Mn{sup 2+}. > Red, green and blue colors are achieved in Yb{sup 3+}, Ho{sup 3+}, Er{sup 3+}, Tm{sup 3+} doped Ca{sub 3}(PO{sub 4}){sub 2}. > Good white emission is obtained in Yb{sup 3+}-Ho{sup 3+}-Er{sup 3+}-Tm{sup 3+} quadri-doped Ca{sub 3}(PO{sub 4}){sub 2}. > Ca{sub 3}(PO{sub 4}){sub 2}:Tb{sup 3+}, Yb{sup 3+}, Ho

  11. Sub-10 nm Sr2LuF7:Yb/Er@Sr2GdF7@SrF2 Up-Conversion Nanocrystals for Up-Conversion Luminescence-Magnetic Resonance-Computed Tomography Trimodal Bioimaging.

    PubMed

    Chen, Cailing; Liu, Jianhua; Chen, Ying; Li, Chunguang; Liu, Xiaomin; Huang, He; Liang, Chen; Lou, Yue; Shi, Zhan; Feng, Shouhua

    2017-02-22

    Herein, sub-10 nm core-shell nanocrystals (NCs), which select Sr2LuF7:Yb/Er as core, Sr2GdF7 as middle shell, and SrF2 as an outermost shell, were synthesized by a seed-mediated growth process. The NCs possess good crystallinity, morphology, and up-conversion luminescent properties. After modification by polyethylenimine branched (PEI), in vitro cell up-conversion imaging with low autofluorescence was realized. Due to the presence of Gd(3+) ions, in vivo magnetic resonance (MR) imaging was also achieved with these designed NCs. More significantly, these special core-shell NCs exhibited high contrast in in vivo X-ray computed tomography (CT) imaging because of their good X-ray absorption ability. These results indicate that the core-shell up-conversion NCs can serve as promising contrast agents for up-conversion luminescence-MR-CT trimodal bioimaging.

  12. Nine members of a family of nine-membered cyclic coordination clusters; Fe6Ln3 wheels (Ln = Gd to Lu and Y).

    PubMed

    Kühne, Irina A; Mereacre, Valeriu; Anson, Christopher E; Powell, Annie K

    2016-01-18

    We report a family of isostructural nonanuclear Fe(III)-Ln(III) cyclic coordination clusters [Fe(III)(6)Ln(III)(3)(μ-OMe)9(vanox)6(benz)6]. (Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5), Yb (6), Lu (7), Y (8) and Gd (9)), containing an odd number of metal ions. The planar cyclic coordination cluster cores are built up from three [Fe2Ln] subunits.

  13. Tuberculosis (TB)

    MedlinePlus

    ... with facebook share with twitter share with linkedin Tuberculosis (TB) Tuberculosis (TB) is a contagious and often ... are drug resistant. Why Is the Study of Tuberculosis (TB) a Priority for NIAID? Tuberculosis is one ...

  14. Facile synthesis and multicolor luminescent properties of uniform Lu2O3:Ln (Ln=Eu3+, Tb3+, Yb3+/Er3+, Yb3+/Tm3+, and Yb3+/Ho3+) nanospheres.

    PubMed

    Li, Rumin; Gai, Shili; Wang, Liuzhen; Wang, Jun; Yang, Piaoping

    2012-02-15

    Multicolor Lu(2)O(3):Ln (Ln=Eu(3+), Tb(3+), Yb(3+)/Er(3+), Yb(3+)/Tm(3+), and Yb(3+)/Ho(3+)) nanocrystals (NCs) with uniform spherical morphology were prepared through a facile urea-assisted homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrum (EDS), Fourier transformed infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), and photoluminescence (PL) spectra as well as kinetic decays were employed to characterize these samples. The XRD results reveal that the as-prepared nanospheres can be well indexed to cubic Lu(2)O(3) phase with high purity. The SEM images show the obtained Lu(2)O(3):Ln samples consist of regular nanospheres with the mean diameter of 95 nm. And the possible formation mechanism is also proposed. Upon ultraviolet (UV) excitation, Lu(2)O(3):Ln (Ln=Eu(3+) and Tb(3+)) NCs exhibit bright red (Eu(3+), (5)D(0)→(7)F(2)), and green (Tb(3+), (5)D(4)→(7)F(5)) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Lu(2)O(3):Ln (Ln=Yb(3+)/Er(3+), Yb(3+)/Tm(3+), and Yb(3+)/Ho(3+)) NCs display the typical up-conversion (UC) emissions of green (Er(3+), (4)S(3/2),(2)H(11/2)→(4)I(15/2)), blue (Tm(3+), (1)G(4)→(3)H(6)) and yellow-green (Ho(3+), (5)F(4), (5)S(2)→(5)I(8)), respectively.

  15. Highly uniform and monodisperse beta-NaYF(4):Ln(3+) (Ln = Eu, Tb, Yb/Er, and Yb/Tm) hexagonal microprism crystals: hydrothermal synthesis and luminescent properties.

    PubMed

    Li, Chunxia; Quan, Zewei; Yang, Jun; Yang, Piaoping; Lin, Jun

    2007-08-06

    beta-NaYF4:Ln3+ (Ln = Eu, Tb, Yb/Er, and Yb/Tm) hexagonal microprisms with remarkably uniform morphology and size have been synthesized via a facile hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. It is found that sodium citrate as a shape modifier introduced into the reaction system plays a critical role in the shape evolution of the final products. Furthermore, the shape and size of the products can be further manipulated by adjusting the molar ratio of citrate/RE3+ (RE represents the total amount of Y3+ and the doped rare earth elements such as Eu3+, Tb3+, Yb3+/Er3+, or Yb3+/Tm3+). Under the excitation of 397 nm ultraviolet light, NaYF4:xEu3+ (x = 1.5, 5%) shows the emission lines of Eu3+ corresponding to 5D0-3 --> 7FJ (J = 0-4) transitions from 400 to 700 nm (whole visible spectral region) with different intensity, resulting in yellow and red down-conversion (DC) light emissions, respectively. When doped with 5% Tb3+ ions, the strong DC fluorescence corresponding to 5D4 --> 7FJ (J = 6, 5, 4, 3) transitions with 5D4 --> 7F5 (green emission at 544 nm) being the most prominent group that has been observed. In addition, under 980 nm laser excitation, the Yb3+/Er3+- and Yb3+/Tm3+-codoped beta-NaYF4 samples exhibit bright green and whitish blue up-conversion (UC) luminescence, respectively. The luminescence mechanisms for the doped lanthanide ions were thoroughly analyzed.

  16. Magnetic properties of the charge density wave compounds RTe3, R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er & Tm

    SciTech Connect

    Ru, N.; Chu, J.-H.; Fisher, I.R.; /Stanford U., Geballe Lab.

    2009-12-14

    The antiferromagnetic transition is investigated in the rare-earth (R) tritelluride RTe{sub 3} family of charge density wave (CDW) compounds via specific heat, magnetization and resistivity measurements. Observation of the opening of a superzone gap in the resistivity of DyTe{sub 3} indicates that additional nesting of the reconstructed Fermi surface in the CDW state plays an important role in determining the magnetic structure.

  17. The magnetic properties and magnetocaloric effects in binary R–T (R = Pr, Gd, Tb, Dy, Ho, Er, Tm; T = Ga, Ni, Co, Cu) intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Zheng, Xin-Qi; Shen, Bao-Gen

    2017-02-01

    Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 11274357, 51501005, 51590880, and 11674008), the Fundamental Research Funds for the Central Universities, China (Grant No. FRF-TP-15-010A1), the China Postdoctoral Science Foundation (Grant No. 2016M591071), and the Key Research Program of the Chinese Academy of Sciences (Grant No. KJZD-EW-M05).

  18. Bifunction in Er{sup 3+}/Yb{sup 3+} co-doped BaTi{sub 2}O{sub 5}–Gd{sub 2}O{sub 3} glasses prepared by aerodynamic levitation method

    SciTech Connect

    Zhang, Minghui; Yu, Jianding; Pan, Xiuhong; Cheng, Yuxing; Liu, Yan

    2013-11-15

    Graphical abstract: - Highlights: • Novel BaTi{sub 2}O{sub 5}–Gd{sub 2}O{sub 3} based glasses have been prepared by aerodynamic levitation. • The obtained glasses show high thermal stability with T{sub g} = 763.3 °C. • Er{sup 3+}/Yb{sup 3+} co-doped glasses show strong upconversion based on a two-photon process. • Red emission is stronger than green emissions for EBT by high Yb{sup 3+} concentration. • Magnetic ions are paramagnetic and the distribution is homogeneous in the glasses. - Abstract: Novel Er{sup 3+}/Yb{sup 3+} co-doped BaTi{sub 2}O{sub 5}–Gd{sub 2}O{sub 3} spherical glasses have been fabricated by aerodynamic levitation method. The thermal stability, upconversion luminescence, and magnetic properties of the present glass have been studied. The glasses show high thermal stability with 763.3 °C of the onset temperature of the glass transition. Red and green emissions centered at 671 nm, 548 nm and 535 nm are obtained at 980 nm excitation. The upconversion is based on a two-photon process by energy transfer, excited-state absorption, and energy back transfer. Yb{sup 3+} ions are more than Er{sup 3+} ions in the glass, resulting in efficient energy back transfer from Er{sup 3+} to Yb{sup 3+}. So the red emission is stronger than the green emissions. Magnetization curves indicate that magnetic rare earth ions are paramagnetic and the distribution is homogeneous and random in the glass matrix. Aerodynamic levitation method is an efficient way to prepare glasses with homogeneous rare earth ions.

  19. Lanthanoid single-ion magnets based on polyoxometalates with a 5-fold symmetry: the series [LnP5W30O110]12- (Ln3+ = Tb, Dy, Ho, Er, Tm, and Yb).

    PubMed

    Cardona-Serra, S; Clemente-Juan, J M; Coronado, E; Gaita-Ariño, A; Camón, A; Evangelisti, M; Luis, F; Martínez-Pérez, M J; Sesé, J

    2012-09-12

    A robust, stable and processable family of mononuclear lanthanoid complexes based on polyoxometalates (POMs) that exhibit single-molecule magnetic behavior is described here. Preyssler polyanions of general formula [LnP(5)W(30)O(110)](12-) (Ln(3+) = Tb, Dy, Ho, Er, Tm, and Yb) have been characterized with static and dynamic magnetic measurements and heat capacity experiments. For the Dy and Ho derivatives, slow relaxation of the magnetization has been found. A simple interpretation of these properties is achieved by using crystal field theory.

  20. ARPES study of the evolution of band structure and charge density wave properties in RTe3 ( R=Y , La, Ce, Sm, Gd, Tb, and Dy)

    SciTech Connect

    Hussain, Zahid; Brouet, Veronique; Yang, Wanli; Zhou, Xingjiang; Hussain, Zahid; Moore, R.G.; He, R.; Lu, D. H.; Shen, Z.X.; Laverock, J.; Dugdale, S.B.; Ru, N.; Fisher, R.

    2008-01-16

    We present a detailed angle-resolved photoemission spectroscopy (ARPES) investigation of the RTe3 family, which sets this system as an ideal"textbook" example for the formation of a nesting driven charge density wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDWinstabilities, from the opening of large gaps on the best nested parts of Fermi surface (up to 0.4 eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k space. An additional advantage of RTe3 is that theband structure can be very accurately described by a simple two dimensional tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure by comparing our ARPES measurements with the linear muffin-tinorbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly the evolution of gaps in k space, the evolution of the CDW wave vector with R, and the shape of the residual metallic pockets. Finally, we give an estimation of the CDWinteraction parameters and find that the change in the electronic density of states n (EF), due to lattice expansion when different R ions are inserted, has the correct order of magnitude to explain the evolution of the CDW properties.

  1. Rare-earth transition-metal chalcogenides Ln{sub 3}MGaS{sub 7} (Ln=Nd, Sm, Dy, Er; M=Co, Ni) and Ln{sub 3}MGaSe{sub 7} (Ln=Nd, Sm, Gd, Dy, M=Co; Ln=Nd, Gd, Dy, M=Ni)

    SciTech Connect

    Yin, Wenlong; Shi, Youguo; Kang, Bin; Deng, Jianguo; Yao, Jiyong; Wu, Yicheng

    2014-05-01

    Fifteen new rare-earth transition-metal chalcogenides, Ln{sub 3}MGaS{sub 7} (Ln=Nd, Sm, Dy, Er; M=Co, Ni) and Ln{sub 3}MGaSe{sub 7} (Ln=Nd, Sm, Gd, Dy, M=Co; Ln=Nd, Gd, Dy, M=Ni), have been synthesized by solid state reactions. They are isostructural, adopt Ce{sub 3}Al{sub 1.67}S{sub 7}—related structure type, and crystallize in the non-centrosymmetric hexagonal space group P6{sub 3}. They adopt a three-dimensional framework composed of LnQ{sub 7} monocapped trigonal prisms with the interesting [MQ{sub 3}]{sup 4−} chains and isolated GaQ{sub 4} tetrahedra lying in two sets of channels in the framework. The magnetic susceptibility measurements on Ln{sub 3}CoGaQ{sub 7} (Ln=Dy, Er, Q=S; Ln=Dy, Q=Se) indicate that they are paramagnetic and obey the Curie–Weiss law over the entire experimental temperature, while the magnetic susceptibility of Sm{sub 3}CoGaSe{sub 7} deviates from the Curie–Weiss law as a result of the crystal field splitting. - Graphical abstract: Ln{sub 3}MGaS{sub 7} (Ln=Nd, Sm, Dy, Er; M=Co, Ni) and Ln{sub 3}MGaSe{sub 7} (Ln=Nd, Sm, Gd, Dy, M=Co; Ln=Nd, Gd, Dy, M=Ni) adopt a three-dimensional framework composed of LnQ{sub 7} monocapped trigonal prisms with interesting [MQ{sub 3}]{sup 4−} chains and isolated GaQ{sub 4} tetrahedra lying in two sets of channels in the framework. - Highlights: • New compounds, Ln{sub 3}MGaQ{sub 7} (Ln=rare-earth; M=Co, Ni; Q=S, Se), were synthesized. • They are isostructural and crystallize in the noncentrosymmetric space group P6{sub 3}. • They adopt a three-dimensional framework built by LnQ{sub 7} monocapped trigonal prisms. • Ln{sub 3}CoGaQ{sub 7} (Ln=Dy, Er; Q=S, Se) are paramagnetic and obey the Curie–Weiss law. • The magnetic susceptibility of Sm{sub 3}CoGaSe{sub 7} deviates from the Curie–Weiss law.

  2. Up/down conversion luminescence and charge compensation investigation of Ca0.5Y1-x(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors

    NASA Astrophysics Data System (ADS)

    Mahalingam, Venkatakrishnan; Thirumalai, Jagannathan; Krishnan, Rajagopalan; Mantha, Srinivas

    2016-01-01

    Microstructures of Ca0.5Y(1-x)(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors were prepared via the solid-state reaction method. X-ray diffraction, scanning electron microscopy and photoluminescence were used to characterize the prepared phosphor samples. The results reveal that the phosphor samples have single phase scheelite structures with tetragonal symmetry of I41/a. The down/up conversion photoluminescence of the Ca0.5Y(1-x)(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors properties reveal characteristic visible emissions. The energy transfer process, fluorescence lifetime and color coordinates are discussed in detail. Furthermore, the phosphor Ca0.5Y(1-x)(WO4)2:xPr3+ co-doped with alkali chlorides shows the enhancement of luminescence, which was found in the sodium chloride co-doped powder phosphor. The photometric characteristics indicate the suitability of the inorganic powder phosphors for solid-state lighting and display applications.

  3. Facile synthesis and luminescence properties of Y2O3:Ln(3+) (Ln(3+) = Eu(3+), Tb(3+), Dy(3+), Sm(3+), Er(3+), Ho(3+), Tm(3+), Yb(3+)/Er(3+), Yb(3+)/Tm(3+), Yb(3+)/Ho(3+)) microspheres.

    PubMed

    Xu, Zhenhe; Zhao, Qian; Ren, Baoyi; You, Lixin; Sun, Yaguang

    2014-08-01

    Multicolor and monodisperse Y2O3:Ln(3+) (Ln(3+) = Eu(3+), Tb(3+), Dy(3+), Sm(3+), Er(3+), Ho(3+), Tm(3+), Yb(3+)/Er(3+), Yb(3+)/Ho(3+)) microspheres were prepared through a facile urea-assisted homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrum (EDS), Fourier transformed infrared (FT-IR), thermogravimetric analysis (TGA), photoluminescence (PL) and cathodoluminescence (CL) spectra were employed to characterize the samples. The XRD results reveal that the as-prepared spheres can be well indexed to cubic Y2O3 phase with high purity. The SEM and TEM images show the obtained Y2O3:Ln(3+) samples consist of regular nanospheres with the mean diameter of 350 nm. And the possible formation mechanism is also proposed. Upon ultraviolet and low-voltage electron beams excitation, Y2O3:Ln(3+) (Ln(3+) = Eu(3+), Tb(3+), Dy(3+), Sm(3+), Er(3+), Ho(3+), Tm(3+)) samples exhibit respective bright red (Eu(3+), (5)D0 --> (7)F2), green (Tb(3+), (5)D4 --> (7)F5), blue (Dy(3+), (4)F9/2 --> (6)H13/2), yellow (Sm(3+), (4)G5/2 --> (6)H7/2), green (Er(3+), (4)S3/2 --> (4)I15/2), green (Ho(3+), (5)S2 --> (5)I8), blue (Tm(3+), (1)D2 --> (3)F4) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Y2O3:Ln(3+) (Ln(3+) = Yb(3+)/Er(3+), Yb(3+)/Tm(3+) and Yb(3+)/Ho(3+)) exhibit characteristic up-conversion (UC) emissions of green (Er(3+), (2)H11/2, (4)S3/2, (2)H11/2 --> (4)I5/2), blue (Tm(3+), (1)G4 --> (3)H6) and green (Ho(3+), (5)F4, (5)S2 --> (5)I8), respectively. These merits of multicolor emissions in the visible region endow this kind of material with potential applications in the field of light display systems, lasers, and optoelectronic devices.

  4. Spontaneous polarization and pyroelectric effect in the improper ferroelectrics-ferroelastics Gd2(MoO4)3 and Tb2(MoO4)3 at low temperatures

    NASA Astrophysics Data System (ADS)

    Matyjasik, S.; Shaldin, Yu. V.

    2013-11-01

    The experimental variations in the spontaneous polarization ΔPs(T) and pyroelectric coefficient γs(T) for Gd2(MoO4)3 (GMO) and Tb2(MoO4)3 (TMO) at low temperatures reported here differ from those for intrinsic ferroelectrics. A fundamental difference is found in the repolarization behavior of samples of GMO and TMO at fixed temperatures of 300 and 4.2 K. While the single domain formation temperature essentially has no effect on the measurements for TMO, a fundamental difference is observed in the case of GMO: single domain formation in the latter at 4.2 K leads to an order of magnitude increase in ΔPs at T > 85 K and distinct anomalies are observed in γs(T), at one of which the pyroelectric coefficient reaches a record peak of 3 × 10-4 C/(m2.K) at T = 25 K. At T = 200 K the pyroelectric coefficients equal -1.45 and -1.8 in units of 10-6 C/(m2.K). Based on these results and taking published data on the rotational structural transformation in the (001) plane and symmetry considerations into account, we propose a crystal physical model for GMO-type improper ferroelectrics consisting of four mesotetrahedra, each of which is made up of three different types (a, b, c) of MoO4 coordination tetrahedra. The physical significance of the pseudodeviator coefficient Q12*, which initiates the phase transition at T > 433 K from one non-centrally symmetric phase (mm2) into another (4¯2m), is discussed in terms of this model.

  5. Superconductivity above 90 K in the square-planar compound system ABa2Cu3O(6 + x) with A = Y, La, Nd, Sm, Eu, Gd, Ho, Er, and Lu

    NASA Technical Reports Server (NTRS)

    Hor, P. H.; Meng, R. L.; Wang, Y. Q.; Gao, L.; Huang, Z. J.

    1987-01-01

    Superconductivity has been found in the 90-K range in ABa2Cu3O(6 + x) with A = La, Nd, Sm, Eu, Gd, Ho, Er, and Lu in addition to Y. The results suggest that the unique square-planar Cu atoms, each surrounded by four or six oxygen atoms, are crucial to the superconductivity of oxides in general. In particular, the high Tc of ABa2Cu3O(6 + x) is attributed mainly to the quasi-two-dimensional assembly of the CuO2-Ba-CuO(2 + x)Ba-CuO2 layers sandwiched between two A layers, with particular emphasis in the CuO(2 + x) layers. Higher-Tc oxides are predicted for compounds with bigger assemblies of CuO2 layers coupled by Ba layers.

  6. Dual-modal upconversion fluorescent/X-ray imaging using ligand-free hexagonal phase NaLuF4:Gd/Yb/Er nanorods for blood vessel visualization.

    PubMed

    Zeng, Songjun; Wang, Haibo; Lu, Wei; Yi, Zhigao; Rao, Ling; Liu, Hongrong; Hao, Jianhua

    2014-03-01

    Visualization of blood vessel of lung can improve the detection of the lung and pulmonary vascular diseases. However, research on visualization of blood vessel of lung using the new generation upconversion nanoprobes is still scarce. Herein, high quality hexagonal phase NaLuF4:Gd/Yb/Er nanorods were synthesized by a simple hydrothermal method through doping Gd(3+). Doping Gd can not only promote the phase transformation from cubic to hexagonal and the shape evolution from microtube to rod-like, but also provide an additional magnetic properties for biomedical application. The as-prepared nanorods were further converted to water solubility by treating with HCl for eliminating the capped oleic acid. The ligand-free nanorods were successfully used for high-contrast upconversion fluorescent bioimaging of HeLa cells. Moreover, the in vivo synergistic upconversion fluorescent and X-ray imaging of nude mice were demonstrated by subcutaneously and intravenously administrated the ligand-free nanorods. The X-ray signals were matched well with the upconversion signal, indicating the successfully synergistic bioimaging. The ex-vivo X-ray and upconversion fluorescent imaging of various organs revealed that the nanorods were mainly accumulated in liver and lung. More importantly, the blood vessel of the lung can be readily visualized when these ligand-free nanorods are intravenously injected. Apart from the synergistic X-ray and upconversion bioimaging, the ligand-free nanorods can also possess excellent paramagnetic property for potential magnetic resonance imaging contrast agent. Our results have demonstrated the enhanced visualization of blood vessel of lung performed by dual-modal bioimaging of X-ray and upconversion fluorescence, revealing the great promise of these nanoprobes in angiography imaging. Such a new technique enables the integration of the two bioimaging techniques by combining their collective strengths and minimizing their shortcomings.

  7. Pressure dependence of the charge-density-wave and superconducting states in GdTe3, TbTe3, and DyTe3

    SciTech Connect

    Zocco, D. A.; Hamlin, J. J.; Grube, K.; Chu, J. -H.; Kuo, H. -H.; Fisher, I. R.; Maple, M. B.

    2015-05-14

    Here, we present electrical resistivity and ac-susceptibility measurements of GdTe3, TbTe3 and DyTe3 performed under pressure. An upper charge-density-wave (CDW) is suppressed at a rate of dTCW,1/dP~ –85K/GPa. For TbTe3 and DyTe3, a second CDW below TCDW,2 increases with pressure until it reaches the TCDW,1(P) line. For GdTe3, the lower CDW emerges as pressure is increased above ~1GPa. As these two CDW states are suppressed with pressure, superconductivity (SC) appears in the three compounds at lower temperatures. Ac-susceptibility experiments performed on TbTe3 provide compelling evidence for bulk SC in the low-pressure region of the phase diagram. We provide measurements of superconducting critical fields and discuss the origin of a high-pressure superconducting phase occurring above 5 GPa.

  8. Synthesis, structure, luminescent, and magnetic properties of carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2] (Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato).

    PubMed

    Ehama, Kiyomi; Ohmichi, Yusuke; Sakamoto, Soichiro; Fujinami, Takeshi; Matsumoto, Naohide; Mochida, Naotaka; Ishida, Takayuki; Sunatsuki, Yukinari; Tsuchimoto, Masanobu; Re, Nazzareno

    2013-11-04

    Carbonato-bridged Zn(II)2Ln(III)2 complexes [(μ4-CO3)2{Zn(II)L(n)Ln(III)(NO3)}2]·solvent were synthesized through atmospheric CO2 fixation reaction of [Zn(II)L(n)(H2O)2]·xH2O, Ln(III)(NO3)3·6H2O, and triethylamine, where Ln(III) = Gd(III), Tb(III), Dy(III); L(1) = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, L(2) = N,N'-bis(3-ethoxy-2-oxybenzylidene)-1,3-propanediaminato. Each Zn(II)2Ln(III)2 structure possessing an inversion center can be described as two di-μ-phenoxo-bridged {Zn(II)L(n)Ln(III)(NO3)} binuclear units bridged by two carbonato CO3(2-) ions. The Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of L(n) and one oxygen atom of a bridging carbonato ion at the axial site. Ln(III) ion is coordinated by nine oxygen atoms consisting of four from the deprotonated Schiff-base L(n), two from a chelating nitrate, and three from two carbonate groups. The temperature-dependent magnetic susceptibilities in the range 1.9-300 K, field-dependent magnetization from 0 to 5 T at 1.9 K, and alternating current magnetic susceptibilities under the direct current bias fields of 0 and 1000 Oe were measured. The magnetic properties of the Zn(II)2Ln(III)2 complexes are analyzed on the basis of the dicarbonato-bridged binuclear Ln(III)-Ln(III) structure, as the Zn(II) ion with d(10) electronic configuration is diamagnetic. ZnGd1 (L(1)) and ZnGd2 (L(2)) show a ferromagnetic Gd(III)-Gd(III) interaction with J(Gd-Gd) = +0.042 and +0.028 cm(-1), respectively, on the basis of the Hamiltonian H = -2J(Gd-Gd)ŜGd1·ŜGd2. The magnetic data of the Zn(II)2Ln(III)2 complexes (Ln(III) = Tb(III), Dy(III)) were analyzed by a spin Hamiltonian including the crystal field effect on the Ln(III) ions and the Ln(III)-Ln(III) magnetic interaction. The Stark splitting of the ground state was so evaluated, and the energy pattern indicates a strong easy axis (Ising type) anisotropy. Luminescence spectra of Zn(II)2Tb(III)2 complexes were observed, while those

  9. Crystal structures of RPt{sub 3-x}Si{sub 1-y}(R=Y, Tb, Dy, Ho, Er, Tm, Yb) studied by single crystal X-ray diffraction

    SciTech Connect

    Gribanov, Alexander; Grytsiv, Andriy; Rogl, Peter; Seropegin, Yurii; Giester, Gerald

    2009-07-15

    The crystal structures of ternary compounds RPt{sub 3-x}Si{sub 1-y}(R=Y, Tb, Dy, Ho, Er, Tm, Yb) have been elucidated from X-ray single crystal CCD data. All compounds are isotypic and crystallize in the tetragonal space group P4/mbm. The general formula RPt{sub 3-x}Si{sub 1-y} arises from defects: x{approx}0.20, y{approx}0.14. The crystal structure of RPt{sub 3-x}Si{sub 1-y} can be considered as a packing of four types of building blocks which derive from the CePt{sub 3}B-type unit cell by various degrees of distortion and Pt, Si-defects. - Graphical Abstract: Electron density in RPt{sub 3-x}Si{sub 1-y} at 0, 1/2 , 0.

  10. Canted magnetic ground state of quarter-doped manganites R 0.75Ca0.25MnO3 (R  =  Y, Tb, Dy, Ho, and Er).

    PubMed

    Sinclair, R; Cao, H B; Garlea, V O; Lee, M; Choi, E S; Dun, Z L; Dong, S; Dagotto, E; Zhou, H D

    2017-02-15

    Polycrystalline samples of the quarter-doped manganites R 0.75Ca0.25MnO3 (R  =  Y, Tb, Dy, Ho, and Er) were studied by x-ray diffraction and AC/DC susceptibility measurements. All five samples are orthorhombic and exhibit similar magnetic properties: enhanced ferromagnetism below T 1 (∼80 K) and a spin glass (SG) state below T SG (∼30 K). With increasing R (3+) ionic size, both T 1 and T SG generally increase. The single crystal neutron diffraction results on Tb0.75Ca0.25MnO3 revealed that the SG state is mainly composed of a short-range ordered version of a novel canted (i.e. noncollinear) antiferromagnetic spin state. Furthermore, calculations based on the double exchange model for quarter-doped manganites reveal that this new magnetic phase provides a transition state between the ferromagnetic state and the theoretically predicted spin-orthogonal stripe phase.

  11. Canted magnetic ground state of quarter-doped manganites R 0.75Ca0.25MnO3 (R  =  Y, Tb, Dy, Ho, and Er)

    NASA Astrophysics Data System (ADS)

    Sinclair, R.; Cao, H. B.; Garlea, V. O.; Lee, M.; Choi, E. S.; Dun, Z. L.; Dong, S.; Dagotto, E.; Zhou, H. D.

    2017-02-01

    Polycrystalline samples of the quarter-doped manganites R 0.75Ca0.25MnO3 (R  =  Y, Tb, Dy, Ho, and Er) were studied by x-ray diffraction and AC/DC susceptibility measurements. All five samples are orthorhombic and exhibit similar magnetic properties: enhanced ferromagnetism below T 1 (∼80 K) and a spin glass (SG) state below T SG (∼30 K). With increasing R 3+ ionic size, both T 1 and T SG generally increase. The single crystal neutron diffraction results on Tb0.75Ca0.25MnO3 revealed that the SG state is mainly composed of a short-range ordered version of a novel canted (i.e. noncollinear) antiferromagnetic spin state. Furthermore, calculations based on the double exchange model for quarter-doped manganites reveal that this new magnetic phase provides a transition state between the ferromagnetic state and the theoretically predicted spin-orthogonal stripe phase.

  12. Strain tuning and strong enhancement of ionic conductivity in SrZrO3-RE2O3 (RE = Sm, Eu, Gd, Dy, and Er) nanocomposite films

    SciTech Connect

    Lee, Shinbuhm; Zhang, Wenrui; Khatkhatay, Fauzia; Jia, Quanxi; Wang, Haiyan; MacManus-Driscoll, Judith L.

    2015-06-05

    Fast ion transport channels at interfaces in thin films have attracted great attention due to a range of potential applications for energy materials and devices, for, solid oxide fuel cells, sensors, and memories. Here, it is shown that in vertical nanocomposite heteroepitaxial films of SrZrO3–RE2O3 (RE = Sm, Eu, Gd, Dy, and Er) the ionic conductivity of the composite can be tuned and strongly enhanced using embedded, stiff, and vertical nanopillars of RE2O3. With increasing lattice constant of RE2O3 from Er2O3 to Sm2O3, it is found that the tensile strain in the SrZrO3 increases proportionately, and the ionic conductivity of the composite increases accordingly, by an order of magnitude. Lastly, the results here conclusively show, for the first time, that strain in films can be effectively used to tune the ionic conductivity of the materials.

  13. Octanuclear {Ln(III)8}(Ln = Gd, Tb, Dy, Ho) macrocyclic complexes in a cyclooctadiene-like conformation: manifestation of slow relaxation of magnetization in the Dy(III) derivative.

    PubMed

    Chandrasekhar, Vadapalli; Bag, Prasenjit; Colacio, Enrique

    2013-04-15

    The synthesis of a series of macrocyclic, isostructural octanuclear lanthanide complexes [Gd8 (LH2)4 (μ-Piv)4 (η(2)-Piv)4 (μ-OMe)4]·6CH3OH·2H2O (1), [Tb8 (LH2)4 (μ-Piv)4 (η(2)-Piv)4 (μ-OMe)4]4CH3OH·4H2O (2), [Dy8(LH2)4 (μ-Piv)4 (η(2)-Piv)4 (μ-OMe)4]·8CH3OH (3), and [Ho8(LH2)4(μ-Piv)4 (η(2)-Piv)4 (μ-OMe)4]·CH3OH·4H2O (4) have been achieved, using Ln(III) nitrate salts, pivalic acid, and a new multidentate chelating ligand (2E,N'E)-N'-(3-((bis(2- hydroxyethyl)amino)methyl)-2-hydroxy-5-methylbenzylidene)-2-(hydroxyimino) propane hydrazide (LH5), containing two unsymmetrically disposed arms; one side of the phenol unit is decorated with a diethanolamine group while the other side is a hydrazone that has been built by the condensation reaction involving 2-hydroxyiminopropanehydrazide. All the compounds, 1-4, are neutral and are held by the four [LH2](3-) triply deprotonated chelating ligands. In these complexes all the lanthanide ions are doubly or triply bridged via phenolate, alkoxy, and pivalate oxygens. The metal centers are distributed over the 8 vertices of an octagon, resembling a cyclooctadiene ring core. The details of magnetochemical analysis for complexes 1-4 shows that they exhibit antiferromagnetic interactions between the Ln(3+) ions through the phenoxo, alkoxo, and pivalato bridging groups. None of the compounds exhibits slow relaxation of the magnetization at zero applied direct current (dc) magnetic field, which could be due to the existence of a fast quantum tunneling relaxation of the magnetization (QTM). In the case of 3, the application of a small dc field is enough as to fully or partly suppress the fast and efficient zero-field QTM allowing the observation of slow relaxation above 2 K.

  14. High-pressure stability and compressibility of APO[subscript 4] (A=La, Nd, Eu, Gd, Er, and Y) orthophosphates: An x-ray diffraction study using synchrotron radiation

    SciTech Connect

    Lacomba-Perales, R.; Errandonea, D.; Meng, Y.; Bettinelli, M.

    2010-03-16

    Room-temperature angle-dispersive x-ray diffraction measurements on zircon-type YPO{sub 4} and ErPO{sub 4}, and monazite-type GdPO{sub 4}, EuPO{sub 4}, NdPO{sub 4}, and LaPO{sub 4} were performed in a diamond-anvil cell up to 30 GPa using neon as pressure-transmitting medium. In the zircon-structured oxides we found evidence of a reversible pressure-induced structural phase transformation from zircon to a monazite-type structure. The onset of the transition is at 19.7 GPa in YPO{sub 4} and 17.3 GPa in ErPO{sub 4}. In LaPO{sub 4} a nonreversible transition is found at 26.1 GPa and a barite-type structure is proposed for the high-pressure phase. For the other three monazites studied, their structures were found to be stable up to 30 GPa. Evidence for additional phase transitions or chemical decomposition of the materials was not found in the experiments. The equations of state and axial compressibility for the different phases are also determined. In particular, we found that in a given compound the monazite structure is less compressible than the zircon structure. This fact is attributed to the higher packing efficiency of monazite versus zircon. The differential bond compressibility of different polyhedra is also reported and related to the anisotropic compressibility of both structures. Finally, the sequence of structural transitions and compressibilities are discussed in comparison with other orthophosphates.

  15. Luminescence and magnetic properties of novel nanoparticle-sheathed 3D Micro-Architectures of Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) for bifunctional application

    NASA Astrophysics Data System (ADS)

    Krishnan, Rajagopalan; Thirumalai, Jagannathan; Kathiravan, Arunkumar

    2015-01-01

    For the first time, we report the successful synthesis of novel nanoparticle-sheathed bipyramid-like and almond-like Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) 3D hierarchical microstructures through a simple disodium ethylenediaminetetraacetic acid (Na2EDTA) facilitated hydrothermal method. Interestingly, time-dependent experiments confirm that the assembly-disassembly process is responsible for the formation of self-aggregated 3D architectures via Ostwald ripening phenomena. The resultant products are characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and magnetic measurements. The growth and formation mechanisms of the self-assembled 3D micro structures are discussed in detail. To confirm the presence of all the elements in the microstructure, the energy loss induced by the K, L shell electron ionization is observed in order to map the Fe, Gd, Mo, O, and Eu components. The photo luminescence properties of Fe0.5R0.5(MoO4)1.5 doped with Eu3+, Tb3+, Dy3+ are investigated. The room temperature and low temperature magnetic properties suggest that the interaction between the local-fields introduced by the magnetic Fe3+ ions and the R3+ (La, Gd) ions in the dodecahedral sites determine the magnetism in Fe0.5R0.5(MoO4)1.5:Eu3+. This work provides a new approach to synthesizing the novel Fe0.5R0.5(MoO4)1.5:Ln3+ for bi-functional magnetic and luminescence applications.

  16. Simple correction for the sample shape and radial offset effects on SQUID magnetometers: Magnetic measurements on Ln{sub 2}O{sub 3} (Ln=Gd, Dy, Er) standards

    SciTech Connect

    Morrison, Gregory; Loye, Hans-Conrad zur

    2015-01-15

    An increased focus on magnetic measurements of oriented single crystals, thin films, and magnetically dilute systems has led to a demand for the measurement of weak magnetic moments. This level of sensitivity and precision can be achieved on SQUID magnetometers by decreasing the size of the detection coils. However, the smaller detection coils can amplify two errors in the magnitude of the measured moment, the sample shape and radial offset effects, which were small and typically unaccounted for on previous magnetometers. We report a simple method to determine the radial offset of a sample by taking advantage of the two basic scan modes, DC and lock-in, typically used on magnetometers. This technique allows for the correction of the sample shape and radial offset effects in order to obtain the true moment of a sample. To show the efficacy of this technique, we report the magnetic properties of Ln{sub 2}O{sub 3} (Ln=Gd, Dy, Er). - Graphical abstract: Correction for the sample shape and radial offset effects on SQUID magnetometers using a combination of DC and VSM scan data. - Highlights: • Sample shape and radial offset effects alter the moment measured by magnetometers. • We present a simple method to correct for these sample effects on magnetometers. • We measure magnetic susceptibilities of Ln{sub 2}O{sub 3} to show the efficacy of this method.

  17. Up-conversion emission in KGd(WO 4 ) 2 single crystals triply-doped with Er 3+ /Yb 3+ /Tm 3+ , Tb 3+ /Yb 3+ /Tm 3+ and Pr 3+ /Yb 3+ /Tm 3+ ions

    NASA Astrophysics Data System (ADS)

    Kasprowicz, D.; Brik, M. G.; Majchrowski, A.; Michalski, E.; Głuchowski, P.

    2011-09-01

    Triply-doped single crystals KGd(WO 4) 2:Er 3+/Yb 3+/Tm 3+, KGd(WO 4) 2:Tb 3+/Yb 3+/Tm 3+ and KGd(WO 4) 2:Pr 3+/Yb 3+/Tm 3+ were grown by the Top Seeded Solution Growth (TSSG) method, with an aim of getting efficient up-converted multicolored luminescence, which subsequently can be used for generation of white light. Such an aim determined the choice of the triply doped compounds: excitation of the Yb 3+ ions in the infrared spectral region is followed by red, green and blue emission from other dopants. It was shown that all these systems exhibit multicolor up-conversion fluorescence under 980 nm laser irradiation. Detailed spectroscopic studies of their absorption and luminescence spectra were performed. From the analysis of the dependence of the intensity of fluorescence on the excitation power the conclusion was made about significant role played by the host's conduction band and other possible defects of the KGd(WO 4) 2 crystal lattice in the up-conversion processes.

  18. Amending the anisotropy barrier and luminescence behavior of heterometallic trinuclear linear [M(II) -Ln(III) -M(II) ] (Ln(III) =Gd, Tb, Dy; M(II) =Mg/Zn) complexes by change from divalent paramagnetic to diamagnetic metal ions.

    PubMed

    Das, Sourav; Bejoymohandas, K S; Dey, Atanu; Biswas, Sourav; Reddy, M L P; Morales, Roser; Ruiz, Eliseo; Titos-Padilla, Silvia; Colacio, Enrique; Chandrasekhar, Vadapalli

    2015-04-20

    The sequential reaction of a multisite coordinating compartmental ligand [2-(2-hydroxy-3-(hydroxymethyl)-5-methylbenzylideneamino)-2-methylpropane-1,3-diol] (LH4 ) with appropriate lanthanide salts followed by the addition of [Mg(NO3 )2 ]⋅6 H2 O or [Zn(NO3 )2 ]⋅6 H2 O in a 4:1:2 stoichiometric ratio in the presence of triethylamine affords a series of isostructural heterometallic trinuclear complexes containing [Mg2 Ln](3+) (Ln=Dy, Gd, and Tb) and [Zn2 Ln](3+) (Ln=Dy, Gd, and Tb) cores. The formation of these complexes is demonstrated by X-ray crystallography as well as ESI-MS spectra. All complexes are isostructural possessing a linear trimetallic core with a central lanthanide ion. The comprehensive studies discussed involve the synthesis, structure, magnetism, and photophysical properties on this family of trinuclear [Mg2 Ln](3+) and [Zn2 Ln](3+) heterometallic complexes. [Mg2 Dy](3+) and [Zn2 Dy](3+) show slow relaxation of the magnetization below 12 K under zero applied direct current (dc) field, but without reaching a neat maximum, which is due to the overlapping with a faster quantum tunneling relaxation mediated through dipole-dipole and hyperfine interactions. Under a small applied dc field of 1000 Oe, the quantum tunneling is almost suppressed and temperature and frequency dependent peaks are observed, thus confirming the single-molecule magnet behavior of complexes [Mg2 Dy](3+) and [Zn2 Dy](3+) .

  19. Near infrared emission of TbAG:Ce3+,Yb3+ phosphor for solar cell applications

    NASA Astrophysics Data System (ADS)

    Meshram, N. D.; Yadav, P. J.; Pathak, A. A.; Joshi, C. P.; Moharil, S. V.

    2016-05-01

    Luminescent materials doped with rare earth ions are used for many devices such as optical amplifiers in telecommunication, phosphors for white light emitting diodes (LEDs), displays, and so on. Recently, they also have attracted a great interest for photovoltaic applications to improve solar cell efficiency by modifying solar spectrum. Crystal silicon (c-Si) solar cells most effectively convert photons of energy close to the semiconductor band gap. The mis-match between the incident solar spectrum and the spectral response of solar cells is one of the main reasons to limit the cell efficiency. The efficiency limit of the c-Si has been estimated to be 29% by Shockley and Queisser. However, this limit is estimated to be improved up to 38.4% by modifying the solar spectrum by a quantum cutting (down converting) phosphor which converts one photon of high energy into two photons of lower energy. The phenomenon such as the quantum cutting or the down conversion of rare earth ions have been investigated since Dexter reported the possibility of a luminescent quantum yield greater than unity in 1957. In the past, the quantum cutting from a vacuum ultraviolet photon to visible photons for Pr3+, Gd3+,Gd3+-Eu3+, and Er3+-Tb3+ had been studied. Recently, a new quantum cutting phenomenon from visible photon shorter than 500 nm to two infrared photons for Tb3+-Yb3+, Pr3+-Yb3+, and Tm3+-Yb3+ has been reported. The Yb3+ ion is suitable as an acceptor and emitter because luminescent quantum efficiency of Yb3+ is close to 100% and the energy of the only excited level of Yb3+ (1.2 eV) is roughly in accordance with the band gap of Si (1.1 eV). In addition, the Ce3+-doped Tb3Al5O12 (TbAG), used as a phosphor for white LED, has broad absorption bands in the range of 300-500 nm due to strong ligand field and high luminescent quantum efficiency. Therefore, the Ce3+ ions in the TbAG can be suitable as an excellent sensitizing donor for down conversion materials of Si solar cells. In this

  20. Testing for TB Infection

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  1. Micro-crystallization and spectroscopic properties of Er, Yb:RAl-borates (R=Y, Gd) obtained in RAl3(BO3)4-K2Mo3O10-B2O3-R2O3 and RAl3(BO3)4-B2O3 systems

    NASA Astrophysics Data System (ADS)

    Naprasnikov, D. A.; Maltsev, V. V.; Leonyuk, N. I.; Gorbachenya, K. N.; Kurilchik, S. V.; Kisel, V. E.; Kuleshov, N. V.

    2017-01-01

    The spontaneous YAl3(BO3)4 (YAB) and GdAl3(BO3)4 (GdAB) crystals (of nominal composition and co-doped with Er and Yb) up to 4-5 mm in length were grown from high-temperature solutions using K2Mo3O10 based fluxes in the temperature range of 1120-900 °C. Glass-ceramic composites based on the YAB and GdAB micro-crystals have been prepared by quenching YAB-B2O3 and GdAB-B2O3 melts and characterized by X-ray diffraction and spectroscopic methods. The vitrified melt was shown to contain micro- and nano-crystalline rare-earth borate phases. Their distribution over the composites has been investigated by electron microscopy and three-dimensional X-ray tomography. The absorption spectra of these materials co-doped with erbium and ytterbium as well as luminescence spectrum were demonstrated.

  2. Syntheses, structures, tunable emission and white light emitting Eu3+ and Tb3+ doped lanthanide metal-organic framework materials.

    PubMed

    Ma, Ming-Li; Ji, Can; Zang, Shuang-Quan

    2013-08-07

    A series of novel lanthanide metal-organic frameworks, namely, {[Ln2(L)2]·(H2O)3·(Me2NH2)2}n (Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Ho (9), Er (10)), have been synthesized with hydro(solvo)thermal conditions based on a flexible multicarboxylic acid (H4L = 5-(3,5-dicarboxybenzyloxy)isophthalic acid). Single crystal X-ray diffraction reveals that all of them are isomorphous and possess a (6,6) topological net with a Schläfli symbol of {4(8)·6(7)}. Considering the blue-emission of compound 1 and the intense emission of the Eu and Tb compounds, we successfully construct isostructural Eu(3+) doped Tb compounds whose color can be tuned easily by adjusting the different concentration of the doped ions, and we also obtained white light emitting materials through the doping of Eu and Tb ions in the La compounds.

  3. Raman spectra of 2Ln/sub 2/O/sub 3/ /times/ 9TiO/sub 2/ compounds (Ln = Ce, La, Nd, Pr, Sm, Eu, Gd, Tm, Yb, Tb)

    SciTech Connect

    Mel'nik, N.N.; Tsapenko, L.M.

    1988-03-01

    This work uses Raman and x-ray phase analysis methods to investigate compounds of the type 2Ln/sub 2/O/sub 3/ /times/ 9TiO/sub 2/ (where Ln = Ce, La, Nd, Pr, Sm, Eu, Gd, Tm, and Yb). The compounds were synthesized by melting in an optical beam on a water-cooled substrate (quench rate approx. 10/sup 2/ deg/sec) and by rapid quenching of a melt cupel by slamming with water-cooled blocks quench rate approx. 10/sup 5/ - 10/sup 6/ deg/sec. The x-ray diffraction study was done on a DRON-2 diffractometer. The Raman light spectra were recorded with a DFS-24 double monochromator employing argon laser excitation.

  4. Enhancement of optical Faraday effect of nonanuclear Tb(III) complexes.

    PubMed

    Nakanishi, Takayuki; Suzuki, Yuki; Doi, Yoshihiro; Seki, Tomohiro; Koizumi, Hitoshi; Fushimi, Koji; Fujita, Koji; Hinatsu, Yukio; Ito, Hajime; Tanaka, Katsuhisa; Hasegawa, Yasuchika

    2014-07-21

    The effective magneto-optical properties of novel nonanuclear Tb(III) complexes with Tb-O lattice (specifically, [Tb9(sal-R)16(μ-OH)10](+)NO3(-), where sal-R = alkyl salicylate (R = -CH3 (Me), -C2H5 (Et), -C3H7 (Pr), or -C4H9 (Bu)) are reported. The geometrical structures of these nonanuclear Tb(III) complexes were characterized using X-ray single-crystal analysis and shape-measure calculation. Optical Faraday rotation was observed in nonanuclear Tb(III) complexes in the visible region. The Verdet constant per Tb(III) ion of the Tb9(sal-Me) complex is 150 times larger than that of general Tb(III) oxide glass. To understand their large Faraday rotation, electron paramagnetic resonance measurements of Gd(III) complexes were carried out. In this Report, the magneto-optical relation to the coordination geometry of Tb ions is discussed.

  5. Tuberculosis Facts - Testing for TB

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    Tuberculosis (TB) Facts Testing for TB What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination

  6. Tuberculosis Facts - Exposure to TB

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    Tuberculosis (TB) Facts Exposure to TB What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination

  7. Large-scale synthesis of Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres and their photoluminescence properties

    SciTech Connect

    Gao, Yu; Gong, Jian; Fan, Miaomiao; Fang, Qinghong; Wang, Na; Han, Wenchi; Xu, Zhenhe

    2012-12-15

    Graphical abstract: In this work, multicolor and monodisperse Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres were prepared by a homogeneous precipitation method followed by a subsequent calcination process. Display Omitted Highlights: ► Lu{sub 2}O{sub 3}:Ln{sup 3+} microspheres were prepared by a precipitation followed by a calcination process. ► Lu{sub 2}O{sub 3}:Eu{sup 3+}/Tb{sup 3+} samples exhibit respective red or green emissions. ► Lu{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+}/Tm{sup 3+}/Ho{sup 3+} exhibit emissions of green, blue, yellow-green, respectively. ► These finding may find potential applications in bioanalysis and field emission displays. -- Abstract: In this work, multicolor and monodisperse Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres were prepared by a homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and cathodoluminescence (CL) spectra were employed to characterize the samples. Upon ultraviolet and low-voltage electron beams excitation, Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+} and Tb{sup 3+}) samples exhibit respective bright red (Eu{sup 3+}, {sup 5}D{sub 0} → {sup 7}F{sub 2}) and green (Tb{sup 3+}, {sup 5}D{sub 4} → {sup 7}F{sub 5}) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) exhibit characteristic up-conversion (UC) emissions of green (Er{sup 3+}, {sup 4}S{sub 3/2}, {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2}), blue (Tm{sup 3+}, {sup 1}G{sub 4} → {sup

  8. Crystal structure and magnetic properties of novel R{sub 3}Co{sub 2.2}Si{sub 1.8} compounds (R=Y, Gd-Tm)

    SciTech Connect

    Morozkin, A.V.; Yao, Jinlei; Mozharivskyj, Y.

    2012-08-15

    The crystal structure of new ternary Dy{sub 3}Co{sub 2.2}Si{sub 1.8} compound has been established using single crystal X-ray diffraction, and those of R{sub 3}Co{sub 2.2}Si{sub 1.8} phases (R=Y, Gd-Tm) phases have been verified through the powder diffraction techniques. The Dy{sub 3}Co{sub 2.2}Si{sub 1.8} structure is a new structure type, which is obtained from the Er{sub 3}Ge{sub 4} with an ordered Er{sub 3}Ge{sub 4}-type structure (space group Cmcm) one by coloring the two Ge sites, 4a and 4c, with Si and the 8f site with Co atoms. Tb{sub 3}Co{sub 2.2}Si{sub 1.8}, Dy{sub 3}Co{sub 2.2}Si{sub 1.8}, Ho{sub 3}Co{sub 2.2}Si{sub 1.8} and Er{sub 3}Co{sub 2.2}Si{sub 1.8} compounds display ferromagnetic-type ordering. - Graphical abstract: The novel R{sub 3}Co{sub 2.2}Si{sub 1.8} compounds (R=Y, Gd-Tm) adopt the new structure type, the ordered variant of Er{sub 3}Ge{sub 4}-type structure Magnetic studies on {l_brace}Tb, Dy, Ho, Er{r_brace}{sub 3}Co{sub 2.2}Si{sub 1.8} suggest that their magnetic interactions are primarily ferromagnetic in nature. Highlights: Black-Right-Pointing-Pointer The novel {l_brace}Y, Gd-Tm{r_brace}{sub 3}Co{sub 2.2}Si{sub 1.8} compounds adopt the Dy{sub 3}Co{sub 2.2}Si{sub 1.8} structure type, Black-Right-Pointing-Pointer The Dy{sub 3}Co{sub 2.2}Si{sub 1.8} type is ordered variant of Er{sub 3}Ge{sub 4} type structure. Black-Right-Pointing-Pointer {l_brace}Gd-Tm{r_brace}{sub 3}Co{sub 2.2}Si{sub 1.8} compounds are primarily ferromagnetic in nature.

  9. Syntheses, structures, and magnetic properties of acetato- and diphenolato-bridged 3d-4f binuclear complexes [M(3-MeOsaltn)(MeOH)x(ac)Ln(hfac)2] (M = Zn(II), Cu(II), Ni(II), Co(II); Ln = La(III), Gd(III), Tb(III), Dy(III); 3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato; ac = acetato; hfac = hexafluoroacetylacetonato; x = 0 or 1).

    PubMed

    Towatari, Masaaki; Nishi, Koshiro; Fujinami, Takeshi; Matsumoto, Naohide; Sunatsuki, Yukinari; Kojima, Masaaki; Mochida, Naotaka; Ishida, Takayuki; Re, Nazzareno; Mrozinski, Jerzy

    2013-05-20

    A series of 3d-4f binuclear complexes, [M(3-MeOsaltn)(MeOH)x(ac)Ln(hfac)2] (x = 0 for M = Cu(II), Zn(II); x = 1 for M = Co(II), Ni(II); Ln = Gd(III), Tb(III), Dy(III), La(III)), have been synthesized and characterized, where 3-MeOsaltn, ac, and hfac denote N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, acetato, and hexafluoroacetylacetonato, respectively. The X-ray analyses demonstrated that all the complexes have an acetato- and diphenolato-bridged M(II)-Ln(III) binuclear structure. The Cu(II)-Ln(III) and Zn(II)-Ln(III) complexes are crystallized in an isomorphous triclinic space group P1, where the Cu(II) or Zn(II) ion has square pyramidal coordination geometry with N2O2 donor atoms of 3-MeOsaltn at the equatorial coordination sites and one oxygen atom of the bridging acetato ion at the axial site. The Co(II)-Ln(III) and Ni(II)-Ln(III) complexes are crystallized in an isomorphous monoclinic space group P2(1)/c, where the Co(II) or Ni(II) ion at the high-spin state has an octahedral coordination environment with N2O2 donor atoms of 3-MeOsaltn at the equatorial sites, and one oxygen atom of the bridged acetato and a methanol oxygen atom at the two axial sites. Each Ln(III) ion for all the complexes is coordinated by four oxygen atoms of two phenolato and two methoxy oxygen atoms of "ligand-complex" M(3-MeOsaltn), four oxygen atoms of two hfac(-), and one oxygen atom of the bridging acetato ion; thus, the coordination number is nine. The temperature dependent magnetic susceptibilities from 1.9 to 300 K and the field-dependent magnetization up to 5 T at 1.9 K were measured. Due to the important orbital contributions of the Ln(III) (Tb(III), Dy(III)) and to a lesser extent the M(II) (Ni(II), Co(II)) components, the magnetic interaction between M(II) and Ln(III) ions were investigated by an empirical approach based on a comparison of the magnetic properties of the M(II)-Ln(III), Zn(II)-Ln(III), and M(II)-La(III) complexes. The differences of χ(M)T and M

  10. Treatment: Latent TB Infection (LTBI) and TB Disease

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Tuberculosis (TB) Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Tuberculosis Basic TB Facts How TB Spreads Latent TB ...

  11. Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien)2(μ-1κ,2κ2-AsS4)]n (Ln==Sm, Eu, Gd) and [Ln(dien)2(1κ2-AsS4)] (Ln==Tb, Dy, Ho)

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian

    2013-10-01

    Solvothermal reactions of Ln2O3, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien)2(μ-1κ,2κ2-AsS4)]n [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien)2(1κ2-AsS4)] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln2O3 oxides were converted to [Ln(dien)2]3+ complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS4 unit. In 1-3, the AsS4 units interconnect the [Ln(dien)2]3+ cations via Ln-S bonds as tridentate μ-1κ,2κ2-AsS4 bridging ligands, resulting in the neutral coordination polymers [Ln(dien)2(μ-1κ,2κ2-AsS4)]n (Ln1). In 4-6, the AsS4 units coordinate with the Ln3+ ion of [Ln(dien)2]3+ as 1κ2-AsS4 chelating ligands to form neutral coordination compounds [Ln(dien)2(1κ2-AsS4)] (Ln2). The Ln3+ ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln3+ ions. Optical absorption spectra showed that 1-6 have potential use as semiconductors with the band gaps in the range 2.18-3.21 eV.

  12. Co(II)4, Co(II)7, and a Series of Co(II)2Ln(III) (Ln(III) = Nd(III), Sm(III), Gd(III), Tb(III), Dy(III)) Coordination Clusters: Search for Single Molecule Magnets.

    PubMed

    Modak, Ritwik; Sikdar, Yeasin; Thuijs, Annaliese E; Christou, George; Goswami, Sanchita

    2016-10-03

    We report herein the syntheses and investigation of the magnetic properties of a Co(II)4 compound, a series of trinuclear Co(II)2Ln(III) (Ln(III) = Nd(III), Sm(III), Gd(III), Tb(III), Dy(III)) complexes, and a Co(II)7 complex. The homometallic Co(II)4 core was obtained from the reaction of Ln(NO3)3·xH2O/Co(NO3)2·6H2O/H2vab/Et3N in a 0.5:0.5:1:2 ratio in methanol. Variation in synthetic conditions was necessary to get the desired Co(II)-Ln(III) complexes. The Co(II)-Ln(III) assembly was synthesized from Ln(NO3)3·xH2O/Co(OAc)2·4H2O/H2vab/NaOMe in a 0.4:0.5:1:1 ratio in methanol. The isostructural Co(II)2Ln(III) complexes have a core structure with the general formula [Co2Ln(Hvab)4(NO3)](NO3)2·MeOH·H2O, (where H2vab = 2-[(2-hydroxymethyl-phenylimino)-methyl]-6-methoxy-phenol) with simultaneous crystallization of Co(II)7 complex in each reaction. The magnetic investigation of these complexes reveals that both homometallic complexes and four Co(II)-Ln(III) complexes (except Co(II)-Nd(III)) display behavior characteristic of single molecule magnets.

  13. Controlled synthesis and luminescence properties of Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu, Pr, Sm, Tb, Dy, Yb/Er, Yb/Tm, and Yb/Ho) phosphors by hydrothermal method versus pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Mahalingam, Venkatakrishnan; Thirumalai, Jagannathan; Krishnan, Rajagopalan; Chandramohan, Rathinam

    2016-01-01

    Herein, we report on rare-earth (RE) activated Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu, Pr, Sm, Tb, Dy, Yb/Er, Yb/Ho, and Yb/Tm) phosphors synthesized using a surfactant-mediated hydrothermal route. Timedependent experiments were performed, and the morphological evolution of the phosphors was studied. From prepared powder samples of Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu and Yb/Er), nano-sized thin phosphor films were grown using pulsed laser deposition (PLD). The surface topography of the as-grown thin phosphor films was analyzed. The asprepared phosphors were characterized by structural and optical studies. The powder phosphor exhibited bi pyramid-like micro-architectures. Structural studies indicated that Ca0.5Y1-x(MoO4)2 possesses the scheelite tetragonal crystal structure. The down-conversion luminescence of Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu, Pr, Sm, Tb, and Dy) as powder phosphors and Eu3+ doped Ca0.5Y1-x(MoO4)2 thin phosphor film were studied. Upon irradiation with a 980 nm laser, the Ca0.5Y1-x(MoO4)2: xRE3+ (RE = Yb/Er, Yb/Ho, and Yb/Tm) powder phosphors and Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Yb/Er) thin phosphor film showed intense up-converted visible emissions in green, yellow, and blue regions. The fluorescence decay time and color co-ordinates were determined for all synthesized phosphors. From the obtained results, the prepared powder and thin film phosphors are suggested to be suitable candidates for display and electro-luminescence applications. [Figure not available: see fulltext.

  14. HIV and Tuberculosis (TB)

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  15. Tuberculosis (TB): Treatment

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  16. Questions and Answers about TB

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  17. Location of trivalent lanthanide dopant energy levels in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3}

    SciTech Connect

    Retot, H.; Viana, B.; Bessiere, A.; Galtayries, A.

    2011-06-15

    The location of Ln{sup 3+} dopant energy levels relative to bands in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} was studied. A several-steps analysis of XPS measurements on heavy lanthanides sesquioxides Ln{sub 2}O{sub 3} (Ln = Gd, Tb, Dy, Er, Tm, Yb, Lu) and on Sc{sub 2}O{sub 3} and Y{sub 2}O{sub 3} reference materials were used to locate Ln{sup 3+} dopant ground state relative to the top of the valence band in (Lu{sub 0.5}Gd{sub 0.5}){sub 2}O{sub 3} within an error bar of {+-}0.4 eV. The agreement between XPS data and model was found improved relative to previous studies. When compared to XPS analysis, prediction based on optical absorption shows a slight underestimation attributed to the lack of precision in Ce{sup 4+} charge transfer band measurement.

  18. Disialyl GD2 ganglioside suppresses ICAM-1-mediated invasiveness in human breast cancer MDA-MB231 cells

    PubMed Central

    Kwon, Kyung-Min; Chung, Tae-Wook; Kwak, Choong-Hwan; Choi, Hee-Jung; Kim, Kyung-Woon; Ha, Sun-Hyung; Cho, Seung-Hak; Lee, Young-Choon; Ha, Ki-Tae; Lee, Moon-Jo; Kim, Cheorl-Ho

    2017-01-01

    The disialoganglioside GD3 has been considered to be involved in tumor progression or suppression in various tumor cells. However, the significance of the biological functions of GD3 in breast cancer cells is still controversial. This prompted us to study the possible relationship(s) between GD3 expression and the metastatic potential of a breast cancer MDA-MB231 cells as an estrogen receptor negative (ER-) type. The human GD3 synthase cDNA was transfected into MDA-MB231 cells, and G-418 bulk selection was used to select cells stably overexpressing the GD3 synthase. In vitro invasion potentials of the GD3 synthase over-expressing cells (pc3-GD3s) were significantly suppressed when compared with control cells. Expression of intercellular adhesion molecule-1 (ICAM-1; CD54) was down-regulated in the pc3-GD3s cells and the decrease in ICAM-I expression is directly related to the decrease in invasiveness of the pc3-GD3s cells. Another type of ER negative SK-BR3 cells exhibited the similar level of ICAM-1 expression as MDA-MB231 cells, while the ER positive MCF-7 cells (ER+) showed the increased expression level of ICAM-1. Then, we investigated signaling pathways known to control ICAM-1 expression. No difference was observed in the phosphorylation of ERK and p38 between the pc3-GD3s and control cells (pc3), but the activation of AKT was inhibited in pc3-GD3s, and not in the control (pc3). In addition, the composition of total gangliosides was changed between control (pc3) and pc3-GD3s cells, as confirmed by HPTLC. The pc3-GD3s cells had an accumulation of the GD2 instead of the GD3. RT-PCR results showed that not only GD3 synthase, but also GM2/GD2 synthase (β4-GalNc T) expression was increased in pc3-GD3s cells. Overexpression of GD3 synthase suppresses the invasive potential of human breast cancer MDA-MB-231 cells through down-regulation of ICAM-1 and the crucial pathway to allow the apoptotic effect has been attributed to accumulation of the GD2 ganglioside. ER has

  19. Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln==Sm, Eu, Gd) and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln==Tb, Dy, Ho)

    SciTech Connect

    Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian

    2013-10-15

    Solvothermal reactions of Ln{sub 2}O{sub 3}, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln{sub 2}O{sub 3} oxides were converted to [Ln(dien){sub 2}]{sup 3+} complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS{sub 4} unit. In 1−3, the AsS{sub 4} units interconnect the [Ln(dien){sub 2}]{sup 3+} cations via Ln−S bonds as tridentate μ-1κ,2κ{sup 2}-AsS{sub 4} bridging ligands, resulting in the neutral coordination polymers [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln1). In 4−6, the AsS{sub 4} units coordinate with the Ln{sup 3+} ion of [Ln(dien){sub 2}]{sup 3+} as 1κ{sup 2}-AsS{sub 4} chelating ligands to form neutral coordination compounds [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln2). The Ln{sup 3+} ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln{sup 3+} ions. Optical absorption spectra showed that 1−6 have potential use as semiconductors with the band gaps in the range 2.18−3.21 eV. - Graphical abstract: Two types of Ln-thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] were prepared by solvothermal methods and the soft Lewis basic AsS{sub 4}{sup 3–} ligand to Ln(III) centers with polyamine co-ligand was obtained. Display Omitted - Highlights: • Lanthanide thioarsenates were prepared by solvothermal methods. • The soft Lewis basic AsS{sub 4} ligand coordinate Ln{sup 3+} ions with coexistence polyamine ligands. • Two structural types of Ln-thioarsenates with structural turnover at Tb were obtained along Ln series. • The Ln-thioarsenates are potential semiconductors

  20. TB Is Back.

    ERIC Educational Resources Information Center

    Natale, Jo Anna

    1992-01-01

    The reemergence of tuberculosis, particularly of new drug-resistant strains, points up the need for well-coordinated school health programs. Immigration effects, growing populations of HIV-infected persons, and relaxed screening procedures are partly responsible for TB's reemergence. Two sidebars offer advice on coping with TB at school and…

  1. Sulfate Exchange of the Nitrate-Type Layered Hydroxide Nanosheets of Ln2(OH)5NO3· nH2O for Better Dispersed and Multi-color Luminescent Ln2O3 Nanophosphors (Ln = Y0.98RE0.02, RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm)

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoli; Liu, Weigang; Li, Ji-Guang; Zhu, Qi; Li, Xiaodong; Sun, Xudong

    2016-07-01

    Through restricting thickness growth by performing coprecipitation at the freezing temperature of ~4 °C, solid-solution nanosheets (up to 5-nm thick) of the Ln2(OH)5NO3· nH2O layered hydroxide (Ln = Y0.98RE0.02; RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm, respectively) were directly synthesized without performing conventional exfoliation. In situ exchange of the interlayer NO3 - with SO4 2- produced a sulfate derivative [Ln2(OH)5(SO4)0.5· nH2O] of the same layered structure and two-dimensional crystallite morphology but substantially contracted d 002 basal spacing (from ~0.886 to 0.841 nm). The sulfate derivative was systematically compared against its nitrate parent in terms of crystal structure and phase/morphology evolution upon heating. It is shown that the interlayer SO4 2-, owing to its bonding with the hydroxide main layer, significantly raises the decomposition temperature from ~600 to 1000 °C to yield remarkably better dispersed oxide nanopowders via a monoclinic Ln2O2SO4 intermediate. The resultant (Y0.98RE0.02)2O3 nanophosphors were studied for their photoluminescence to show that the emission color, depending on RE3+, spans a wide range in the Commission Internationale de l'Eclairage (CIE) chromaticity diagram, from blue to deep red via green, yellow, orange, and orange red.

  2. Magnetic ordering in the pyrochlore Ho{sub 2}CrSbO{sub 7} determined from neutron diffraction, and the magnetic properties of other RE{sub 2}CrSbO{sub 7} phases (RE=Y, Tb, Dy, Er)

    SciTech Connect

    Whitaker, Mariana J.; Greaves, Colin

    2014-07-01

    The magnetic structure of the pyrochlore Ho{sub 2}CrSbO{sub 7}, which orders magnetically below 13 K, has been studied using neutron powder diffraction. Ho{sub 2}CrSbO{sub 7} is found to form an “ordered spin-ice structure” where the magnetic moments are constrained along the 111 axes, but with a ferromagnetic moment in one direction. The Cr{sup 3+} ions order ferromagnetically and this is thought to lift the degeneracy of the x, y and z directions in the cubic structure causing the ferromagnetic component from the Ho{sup 3+} ions to align. The pyrochlores RE{sub 2}CrSbO{sub 7} where RE=Y, Tb, Dy and Er have also been prepared and studied using SQUID magnetometry. - Graphical abstract: The Ho magnetic moments align to provide an overall ferromagnetic moment along [001]. - Highlights: • Despite having inherent frustration on the Ho sublattice, Ho{sub 2}CrSbO{sub 7} orders ferromagnetically below 13 K. • Ordering on the Cr/Sb sublattice appears to remove the degenerate ground state for the Ho order. • The Ho{sup 3+} magnetic moments are aligned along <111> directions by crystal field effects. • Y{sub 2}CrSbO{sub 7} with diamagnetic Y{sup 3+} ions also has a ferromagnetic ground state.

  3. Tuberculosis Facts - TB and HIV/AIDS

    MedlinePlus

    Tuberculosis (TB) Facts TB and HIV/AIDS What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination

  4. Structure and photoluminescent properties of green-emitting terbium-doped GdV1-x Px O4 phosphor prepared by solution combustion method.

    PubMed

    Motloung, S J; Shaat, S K K; Tshabalala, K G; Ntwaeaborwa, O M

    2016-08-01

    Terbium-doped gadolinium orthovanadate (GdVO4 :Tb(3+) ), orthophosphate monohydrate (GdPO4 ·H2 O:Tb(3+) ) and orthovanadate-phosphate (GdV,PO4 :Tb(3+) ) powder phosphors were synthesized using a solution combustion method. X-Ray diffraction analysis confirmed the formation of crystalline GdVO4 , GdPO4 ·H2 O and GdV,PO4 . Scanning electron microscopy images showed that the powder was composed of an agglomeration of particles of different shapes, ranging from spherical to oval to wire-like structures. The chemical elements present were confirmed by energy dispersive spectroscopy, and the stretching mode frequencies were determined by Fourier transform infrared spectroscopy. UV-visible spectroscopy spectra showed a strong absorption band with a maximum at 200 nm assigned to the absorption of VO4 (3-) and minor excitation bands assigned to f → f transitions of Tb(3+) . Four characteristic emission peaks were observed at 491, 546, 588 and 623 nm, and are attributed to (5) D4  → (7) Fj (j = 6, 5, 4 and 3). The photoluminescent prominent green emission peak ((5) D4  → (7) F5 ) was centred at 546 nm. The structure and possible mechanism of light emission from GdV1-x Px O4 :% Tb(3+) are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

  5. TB Screening Tests

    MedlinePlus

    ... known as: Purified Protein Derivative; PPD; Mantoux; Latent Tuberculosis Infection Test; Interferon-gamma Release Assays; IGRA; T- ... else I should know? How is it used? Tuberculosis (TB) screening tests are not used as general ...

  6. Luminescence properties of barium--gadolinium-titanate ceramics doped with rare-earth ions (Eu3+ and Tb3+).

    PubMed

    Hemasundara Raju, S; Muni Sudhakar, B; Sudhakar Reddy, B; Dhoble, S J; Thyagarajan, K; Nageswara Raju, C

    2014-11-01

    Barium-gadolinium-titanate (BaGd2 Ti4 O12) powder ceramics doped with rare-earth ions (Eu(3+) and Tb(3+)) were synthesized by a solid-state reaction method. From the X-ray diffraction spectrum, it was observed that Eu(3+) and Tb(3+):BaGd2 Ti4 O12 powder ceramics are crystallized in the form of an orthorhombic structure. Scanning electron microscopy image shows that the particles are agglomerated and the particle size is about 200 nm. Eu(3+) - and Tb(3+) -doped BaGd2 Ti4 O12 powder ceramics were examined by energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, photoluminescence and thermoluminescence (TL) spectra. Emission spectra of Eu(3+)-doped BaGd2 Ti4 O12 powder ceramics showed bright red emission at 613 nm ((5)D0 →(7)F2) with an excitation wavelength λ(exci)  = 408 nm ((7)F0 → (5)D3) and Tb(3+):BaGd2 Ti4 O12 ceramic powder has shown green emission at 534 nm ((5)D4 → (7)F5) with an excitation wavelength λ(exci)  = 331 nm (((7)F6 → (5)D1). TL spectra show that Eu(3+) and Tb(3+) ions affect TL sensitivity.

  7. Tuberculosis Facts - You Can Prevent TB

    MedlinePlus

    Tuberculosis (TB) Facts You Can Prevent TB What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination TB Facts: You Can Prevent TB What ...

  8. Tuberculosis Facts - TB Can Be Treated

    MedlinePlus

    Tuberculosis (TB) Facts TB Can Be Treated What is TB? “TB” is short for a disease called tuberculosis. TB is spread through the air from one ... Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination Page 1 of 2 TB Facts: TB ...

  9. Chloride derivatives of lanthanoid(III) ortho-oxidotungstates(VI) with the formula LnCl[WO4] (Ln=Gd-Lu): Syntheses, crystal structures and spectroscopic properties

    NASA Astrophysics Data System (ADS)

    Schustereit, Tanja; Schleid, Thomas; Höppe, Henning A.; Kazmierczak, Karolina; Hartenbach, Ingo

    2015-03-01

    The lanthanoid(III) chloride ortho-oxidotungstates(VI) with the formula LnCl[WO4] crystallize monoclinically in space group C2/m (a=1019-1032, b=721-733, c=682-689 pm and β=107-108°, Z=4) for Ln=Gd-Er and triclinically in space group P1¯ (a=593-596, b=719-721, c=684-686 pm, α=93-94, β≈103 and γ≈122°, Z=2) for Ln=Tm-Lu. The monoclinic structure contains crystallographically unique Ln3+ cations, which are surrounded by two Cl- and six O2- anions forming distorted trigonal dodecahedra. Their fusion via common edges leads to anionic layers ∞ 2 {[ LnCl2/2eO4/2eO2/1t ] 6 - }. The polyhedra around the Ln3+ cations in the triclinic crystal structure are also built up by two Cl-, but only five O2- anions to form distorted monocapped trigonal prisms. Their linkage through edges constitutes anionic strands ∞ 1 {[ LnCl2/2eO2/2eO3/1t ] 6 - } along [100]. The complex anionic entities of both LnCl[WO4] arrangements become interconnected by W6+ cations to complete the structures by generating discrete [WO4]2- tetrahedra. Since the title compounds emerge as pure phases according to X-ray powder diffractometry, spectroscopic measurements such as single crystal Raman as well as diffuse reflectance spectroscopy (DRS) were performed. Furthermore, GdCl[WO4] and LuCl[WO4] are suitable host materials for doping with Eu3+, which leads to materials with a red luminescence upon excitation with UV light for both structures. Moreover, TbCl[WO4] exhibits a Tb3+-typical yellow-green bulk luminescence upon UV excitation, which could be analyzed by luminescence spectroscopy.

  10. TB in Vulnerable Populations

    PubMed Central

    Ugarte-Gil, César; Caro, Godofredo; Aylas, Rula; Castro, César; Lema, Claudia

    2016-01-01

    Abstract This article analyzes the factors associated with vulnerability of the Ashaninka, the most populous indigenous Peruvian Amazonian people, to tuberculosis (TB). By applying a human rights-based analytical framework that assesses public policy against human rights standards and principles, and by offering a step-by-step framework for a full assessment of compliance, it provides evidence of the relationship between the incidence of TB among the Ashaninka and Peru’s poor level of compliance with its human rights obligations. The article argues that one of the main reasons for the historical vulnerability of the Ashaninka to diseases such as TB is a lack of political will on the part of the national government to increase public health spending, ensure that resources reach the most vulnerable population, and adopt and invest in a culturally appropriate health system. PMID:27780999

  11. TB in Children in the United States

    MedlinePlus

    ... Search The CDC Cancel Submit Search The CDC Tuberculosis (TB) Note: Javascript is disabled or is not ... message, please visit this page: About CDC.gov . Tuberculosis Basic TB Facts How TB Spreads Latent TB ...

  12. Multidrug-Resistant TB

    PubMed Central

    Cox, Helen; Coomans, Fons

    2016-01-01

    Abstract The right to enjoy the benefits of scientific progress (REBSP) is a little-known but potentially valuable right that can contribute to rights-based approaches to addressing multidrug-resistant TB (MDR-TB). We argue that better understanding of the REBSP may help to advance legal and civil society action for health rights. While the REBSP does not provide an individual entitlement to have a new drug developed for MDR-TB, it sets up entitlements to expect a state to establish a legislative and policy framework aimed at developing scientific capacity to address the most important health issues and at disseminating the outcomes of scientific research. By making scientific findings available and accessible, people can be enabled to claim the use of science for social benefits. Inasmuch as the market fails to address neglected diseases such as MDR-TB, the REBSP provides a potential counterbalance to frame a positive obligation on states to both marshal their own resources and to coordinate the actions of multiple other actors towards this goal, including non-state actors. While the latter do not hold the same level of accountability as states, the REBSP can still enable the recognition of obligations at a level of “soft law” responsibilities. PMID:27780997

  13. Thermoelectric properties of epitaxial TbAs:InGaAs nanocomposites

    SciTech Connect

    Clinger, Laura E.; Zide, Joshua M. O.; Pernot, Gilles; Shakouri, Ali; Buehl, Trevor E.; Burke, Peter G.; Gossard, Arthur C.; Palmstroem, Christopher J.

    2012-05-01

    InGaAs lattice-matched to InP was grown by molecular beam epitaxy with randomly distributed TbAs nanoparticles for thermoelectric power generation applications. TbAs:InGaAs is expected to have a large thermoelectric figure of merit, ZT, particularly at high temperatures, owing to energy band alignment between the nanoparticles and their surrounding matrix. Here, the room temperature thermoelectric properties were measured as a function of TbAs concentration, revealing a maximum thermoelectric power factor of 2.38 W/mK{sup 2} and ZT of 0.19 with 0.2% TbAs. Trends in the thermoelectric properties closely resemble those found in comparable ErAs:InGaAs nanocomposite materials. However, nanoparticles were not observed by scanning transmission electron microscopy in the highest ZT TbAs:InGaAs sample, unlike the highest ZT ErAs:InGaAs sample (0.2% ErAs) and two higher concentration TbAs:InGaAs samples examined. Consistent with expectations concerning the positioning of the Fermi level in these materials, ZT was enhanced by TbAs incorporation largely due to a high Seebeck coefficient, whereas ErAs provided InGaAs with higher conductivity but a lower Seebeck coefficient than that of TbAs:InGaAs. Thermal conductivity was reduced significantly from that of intrinsic thin-film InGaAs only with TbAs concentrations greater than {approx}1.7%.

  14. TB & HIV: the deadly intersection.

    PubMed

    MacDougall, D S

    1999-05-01

    About 2 billion people worldwide are infected with Mycobacterium tuberculosis, the causative agent of tuberculosis (TB). TB is the leading cause of premature death in less industrialized countries, and 8 million more people become infected every year. The World Health Organization (WHO) declared TB a global emergency in 1993 and launched a series of prevention and vaccination programs. In spite of effective drug therapy and a vaccine, tuberculosis remains a major public health problem. The TB and HIV epidemics are closely intertwined, and the risk of TB disease progression is 100 times greater in HIV-positive individuals. TB is the leading cause of death among HIV-infected people worldwide, and virologic evidence suggests that the host immune response to TB may enhance HIV replication and accelerate the progression of HIV infection. The interaction between the two diseases was the subject of a conference called TB & HIV: Applying Advances to the Clinic, Public Health, and the World. Charts and tables show reported TB cases in the U.S., trends in TB cases among foreign-born persons in the U.S., and the country of origin for foreign-born persons with TB in the U.S. Several poster sessions from the conference are summarized. Strategies for dealing with the TB epidemic are outlined.

  15. Crystal structure and magnetic properties of novel Hf{sub 3}Ni{sub 2}Si{sub 3}-type R{sub 3}Co{sub 2}Ge{sub 3} compounds (R=Y, Sm, Tb-Tm)

    SciTech Connect

    Morozkin, A.V.; Nirmala, R.; Yao, Jinlei; Mozharivskyj, Y.; Isnard, O.

    2012-12-15

    The novel R{sub 3}Co{sub 2}Ge{sub 3} compounds with R=Y, Sm, Tb-Tm adopt the Hf{sub 3}Ni{sub 2}Si{sub 3}-type structure (ordered variant of the Ca{sub 3}Ga{sub 5}-type one, space group Cmcm). Sm{sub 3}Co{sub 2}Ge{sub 3}, Tb{sub 3}Co{sub 2}Ge{sub 3}, Ho{sub 3}Co{sub 2}Ge{sub 3} and Er{sub 3}Co{sub 2}Ge{sub 3} undergo an antiferromagnetic-type ordering and Tb{sub 3}Co{sub 2}Ge{sub 3} demonstrates a field-sensitive magnetic behavior. Tm{sub 3}Co{sub 2}Ge{sub 3} is a pure paramagnet down to 5 K, whereas Y{sub 3}Co{sub 2}Ge{sub 3} demonstrates Pauli paramagnetism down to {approx}120 K. In zero applied field and between {approx}50 and {approx}15 K Tb{sub 3}Co{sub 2}Ge{sub 3} shows a non-collinear antiferromagnetic ordering with wave vectors K{sub 0}=[0, 0, 0] and K{sub 1}=[{+-}1/3, 0, 0] and a magnetic unit cell 3a{sub Tb{sub 3Co{sub 2Ge{sub 2}}}} Multiplication-Sign b{sub Tb{sub 3Co{sub 2Ge{sub 3}}}} Multiplication-Sign c{sub Tb{sub 3Co{sub 2Ge{sub 3}}}} , whereas below {approx}15 K it exhibits a complex antiferromagnetic ordering with K{sub 0}=[0, 0, 0], K{sub 1}=[{+-}1/3, 0, 0] and K{sub 2}=[1/2, 0, 0] wave vectors and magnetic unit cell 6a{sub Tb{sub 3Co{sub 2Ge{sub 2}}}} Multiplication-Sign b{sub Tb{sub 3Co{sub 2Ge{sub 2}}}} Multiplication-Sign c{sub Tb{sub 3Co{sub 2Ge{sub 2}}}}. - Graphical abstract: The Hf{sub 3}Ni{sub 2}Si{sub 3}-type {l_brace}Y, Sm, Gd-Tm{r_brace}{sub 3}Co{sub 2}Ge{sub 3} (space group Cmcm) demonstrate complex field sensitive antiferromagnetic ordering. The rare earth sublattice of 4d site plays crucial role in the magnetisation of R{sub 3}Co{sub 2}Ge{sub 3} compounds. Highlights: Black-Right-Pointing-Pointer The {l_brace}Y, Sm, Gd-Tm{r_brace}{sub 3}Co{sub 2}Ge{sub 3} adopts the Hf{sub 3}Ni{sub 2}Si{sub 3}-type structure (space group Cmcm). Black-Right-Pointing-Pointer They demonstrate complex field sensitive antiferromagnetic ordering. Black-Right-Pointing-Pointer The 4d site rare earth sublattice plays crucial role in the magnetism of R{sub 3

  16. TB or not TB?: a case of isolated testicular TB with scrotal involvement.

    PubMed

    Bhargava, A; Davenport, C; Gibbons, N; McConkey, S

    2009-06-01

    Despite the genitourinary tract being the most common site affected by extrapulmonary TB, isolated testicular TB remains a rare clinical entity. In patients with co-morbidities such as hepatic impairment, treatment proves a challenge, as first-line hepatotoxic pharmaceuticals are contraindicated. Here, we report a case of isolated testicular TB with scrotal involvement, on a background of hepatic dysfunction.

  17. Synthesis and morphology of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with tungsten bronze structure in RE{sub 2}O{sub 3}-BaO-Nb{sub 2}O{sub 5}-B{sub 2}O{sub 3} glasses (RE: Sm, Eu, Gd, Dy, Er)

    SciTech Connect

    Ida, H.; Shinozaki, K.; Honma, T.; Oh-ishi, K.; Komatsu, T.

    2012-12-15

    Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with a tetragonal tungsten bronze (TTB) structure are synthesized using a conventional glass crystallization technique in 2.3RE{sub 2}O{sub 3}-27.4BaO-34.3Nb{sub 2}O{sub 5}-36B{sub 2}O{sub 3} (mol%) (RE=Sm, Eu, Gd, Dy, and Er) glasses. One sharp crystallization peak is observed at {approx}670 Degree-Sign C in both powdered and bulk glasses, and the formation of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with unit cell parameters of a{approx}1.24 nm and c{approx}0.39 nm was confirmed. It is found from high resolution transmission electron microscope observations that the morphology of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals is ellipsoidal. Their average particle size is in the range of 15-60 nm and decreases with decreasing ionic radius of RE{sup 3+} being present in the precursor glasses. The optical transparent crystallized glass (bulk) shows the total photoluminescence (PL) quantum yield of 53% in the visible region of Eu{sup 3+} ions, suggesting a high potential of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals as PL materials. - Graphical abstract: This figure shows a TEM photograph for the heat-treated (667 Degree-Sign C, 3 h) sample of 2.3Dy{sub 2}O{sub 3}-27.4BaO-34.3Nb{sub 2}O{sub 5}-36B{sub 2}O{sub 3}. An ellipsoidal-shaped Ba{sub 1-x}Dy{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystal with diameters of 17 and 28 nm is observed. The ellipsoidal morphology is a common feature in Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals synthesized by the crystallization of 2.3RE{sub 2}O{sub 3}-27.4BaO-34.3Nb{sub 2}O{sub 5}-36B{sub 2}O{sub 3} glasses. Highlights: Black-Right-Pointing-Pointer Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals with a tetragonal tungsten bronze structure are synthesized. Black-Right-Pointing-Pointer A glass crystallization technique was applied. Black-Right-Pointing-Pointer The morphology of Ba{sub 1-x}RE{sub 2x/3}Nb{sub 2}O{sub 6} nanocrystals is

  18. Tuning interfacial domain walls in GdCo/Gd/GdCo' spring magnets

    NASA Astrophysics Data System (ADS)

    Blanco-Roldán, C.; Choi, Y.; Quirós, C.; Valvidares, S. M.; Zarate, R.; Vélez, M.; Alameda, J. M.; Haskel, D.; Martín, J. I.

    2015-12-01

    Spring magnets based on GdCo multilayers have been prepared to study the nucleation and evolution of interfacial domain walls (iDWs) depending on layer composition and interlayer coupling. GdCo alloy compositions in each layer were chosen so that their net magnetization aligns either with the Gd (G d35C o65 ) or Co (G d11C o89 ) sublattices. This condition forces an antiparallel arrangement of the layers' net magnetization and leads to nucleation of iDWs above critical magnetic fields whose values are dictated by the interplay between Zeeman and exchange energies. By combining x-ray resonant magnetic scattering with Kerr magnetometry, we provide detailed insight into the nucleation and spatial profile of the iDWs. For strong coupling (GdCo/GdCo' bilayer), iDWs are centered at the interface but with asymmetric width depending on each layer magnetization. When interlayer coupling is weakened by introducing a thin Gd interlayer, the exchange spring effect becomes restricted to a lower temperature and field range than observed in the bilayer structure. Due to the ferromagnetic alignment between the high magnetization G d35C o65 layer and the Gd interlayer, the iDW shrinks and moves into the lower exchange Gd interlayer, causing a reduction of iDW energy.

  19. Ultraviolet photoluminescence in Gd-doped silica and phosphosilicate fibers

    NASA Astrophysics Data System (ADS)

    Wang, Y.; He, J.; Barua, P.; Chiodini, N.; Steigenberger, S.; Abdul Khudus, M. I. M.; Sahu, J. K.; Beresna, M.; Brambilla, G.

    2017-04-01

    Optical fiber lasers operating in the near infrared and visible spectral regions have relied on the spectroscopic properties of rare earth ions such as Yb3+, Er3+, Tm3+, Nd3+, and Sm3+. Here, we investigate Gd3+ doping in phosphosilicate and pure silica fibers using solution doping and sol-gel techniques, respectively, for potential applications in the ultraviolet. Photoluminescence spectra for optical fiber bundles and fiber preforms were recorded and compared. Emissions at 312 nm (phosphosilicate) and 314 nm (pure silica) were observed when pumping to the Gd3+ 6DJ, 6IJ, and 6PJ = 5/2, 3/2 energy levels. Oxygen deficient center was observed in solution doping sample with a wide absorption band centered at around 248 nm not affecting pumping to 6IJ states.

  20. Enhancement of the up-conversion luminescence from NaYF4:Yb3+,Tb3+

    NASA Astrophysics Data System (ADS)

    Hölsä, Jorma; Laihinen, Tero; Laamanen, Taneli; Lastusaari, Mika; Pihlgren, Laura; Rodrigues, Lucas C. V.; Soukka, Tero

    2014-04-01

    The synthesis conditions of the Yb3+ and Tb3+ co-doped NaYF4 were optimized by reducing the number of washings to include only ethanol. The avoidance of the loss of amorphous NaF prior to post-annealing of the as-prepared materials resulted in the enhancement of the otherwise rather weak up-conversion from Tb3+ by 1-2 orders of magnitude. At the same time, the temperature of formation of the hexagonal NaRF4 phase with high up-conversion could be lowered by 100 °C down to 350 °C. This improvement in up-conversion was concluded to result from the better stoichiometry of the material without washing with water. The deficit of Na+ would result in the excess of fluoride which, although not as fatal to the luminescence as the fluoride vacancies, has serious implications to the up-conversion intensity. A further enhancement in the up-conversion luminescence was observed to be due to the Er3+ ion impurity frequently associated with high-concentration Yb3+ materials. The mechanism involving the unintentional Er3+ sensitizer and the resonance energy transfer in the Yb3+-Er3+-Tb3+ co-doped NaYF4 were discussed based on the energy level schemes of the Yb3+, Er3+, and Tb3+ ions in NaYF4.

  1. Difference Between Latent TB Infection and Active TB Disease

    MedlinePlus

    ... person with infectious TB coughs or sneezes, droplet nuclei containing M. tuberculosis are expelled into the air. If another person inhales air containing these droplet nuclei, he or she may become infected. However, not ...

  2. Dopant-mediated structural and magnetic properties of TbMnO3

    NASA Astrophysics Data System (ADS)

    Sharma, Vinit; McDannald, A.; Staruch, M.; Ramprasad, R.; Jain, M.

    2015-07-01

    Structural and magnetic properties of the doped terbium manganites (Tb,A)MnO3 (A = Gd, Dy, and Ho) have been investigated using first-principles calculations and further confirmed by subsequent experimental studies. Both computational and experimental studies suggest that compared to the parent material, namely, TbMnO3 (with a magnetic moment of 9.7 μ B for Tb3+) Dy- and Ho-ion substituted TbMnO3 results in an increase in the magnetic susceptibility at low fields ( ≤ 10.6 μ B for Dy3+ and Ho3+). The observed spiral-spin AFM order in TbMnO3 is stable with respect to the dopant substitutions, which modify the Mn-O-Mn bond angles and lead to stronger the ferromagnetic component of the magnetic moment. Given the fact that magnetic ordering in TbMnO3 causes the ferroelectricity, this is an important step in the field of the magnetically driven ferroelectricity in the class of magnetoelectric multiferroics, which traditionally have low magnetic moments due to the predominantly antiferromagnetic order. In addition, the present study reveals important insights on the phenomenological coupling mechanism in detail, which is essential in order to design new materials with enhanced magneto-electric effects at higher temperatures.

  3. Magnetic interactions in CuII-LnIII cyclic tetranuclear complexes: is it possible to explain the occurrence of SMM behavior in CuII-TbIII and CuII-DyIII complexes?

    PubMed

    Hamamatsu, Takefumi; Yabe, Kazuya; Towatari, Masaaki; Osa, Shutaro; Matsumoto, Naohide; Re, Nazzareno; Pochaba, Andrzej; Mrozinski, Jerzy; Gallani, Jean-Louis; Barla, Alessandro; Imperia, Paolo; Paulsen, Carley; Kappler, Jean-Paul

    2007-05-28

    An extensive series of tetranuclear CuII2LnIII2 complexes [CuIILLnIII(hfac)2]2 (with LnIII being all lanthanide(III) ions except for the radioactive PmIII) has been prepared in order to investigate the nature of the CuII-LnIII magnetic interactions and to try to answer the following question: What makes the CuII2TbIII2 and CuII2DyIII2 complexes single molecule magnets while the other complexes are not? All the complexes within this series possess a similar cyclic tetranuclear structure, in which the CuII and LnIII ions are arrayed alternately via bridges of ligand complex (CuIIL). Regular SQUID magnetometry measurements have been performed on the series. The temperature-dependent magnetic susceptibilities from 2 to 300 K and the field-dependent magnetizations from 0 to 5 T at 2 K have been measured for the CuII2LnIII2 and NiII2LnIII2 complexes, with the NiII2LnIII2 complex containing diamagnetic NiII ions being used as a reference for the evaluation of the CuII-LnIII magnetic interactions. These measurements have revealed that the interactions between CuII and LnIII ions are very weakly antiferromagnetic if Ln=Ce, Nd, Sm, Yb, ferromagnetic if Ln=Gd, Tb, Dy, Ho, Er, Tm, and negligible if Ln=La, Eu, Pr, Lu. With the same goal of better understanding the evolution of the intramolecular magnetic interactions, X-ray magnetic circular dichroism (XMCD) has also been measured on CuII2TbIII2, CuII2DyIII2, and NiII2TbIII2 complexes, either at the L- and M-edges of the metal ions or at the K-edge of the N and O atoms. Last, the CuII2TbIII2 complex exhibiting SMM behavior has received a closer examination of its low temperature magnetic properties down to 0.1 K. These particular measurements have revealed the unusual very slow setting-up of a 3D order below 0.6 K.

  4. Inelastic Neutron Scattering on 160Gd

    NASA Astrophysics Data System (ADS)

    Lesher, S. R.; Casarella, C.; Crider, B. P.; Ikeyama, R.; Marsh, I.; Peters, E. E.; Prados-Estévez, F. M.; Smith, M. K.; Tully, Z.; Vanhoy, J. R.; Aprahamian, A.; Yates, S. W.

    2014-03-01

    The nature of low-lying excitations, Kπ=0+ bands in deformed nuclei remain enigmatic in the field, especially in relationship to quadrupole vibrations. One method of characterizing these states beyond excitation energies is through measurements of absolute transition probabilities. In the rare earth region of deformation, there are five stable Gd isotopes, 154Gd, 156Gd, and 158Gd have been studied to obtain B(E2) values, a fourth, 160Gd is the focus of this work. We have examined 160Gd with the (n, n'γ) reaction and neutron energies up to 3.0 MeV to confirm known 0+ states.

  5. Reticulons Regulate the ER Inheritance Block during ER Stress.

    PubMed

    Piña, Francisco Javier; Fleming, Tinya; Pogliano, Kit; Niwa, Maho

    2016-05-09

    Segregation of functional organelles during the cell cycle is crucial to generate healthy daughter cells. In Saccharomyces cerevisiae, ER stress causes an ER inheritance block to ensure cells inherit a functional ER. Here, we report that formation of tubular ER in the mother cell, the first step in ER inheritance, depends on functional symmetry between the cortical ER (cER) and perinuclear ER (pnER). ER stress induces functional asymmetry, blocking tubular ER formation and ER inheritance. Using fluorescence recovery after photobleaching, we show that the ER chaperone Kar2/BiP fused to GFP and an ER membrane reporter, Hmg1-GFP, behave differently in the cER and pnER. The functional asymmetry and tubular ER formation depend on Reticulons/Yop1, which maintain ER structure. LUNAPARK1 deletion in rtn1Δrtn2Δyop1Δ cells restores the pnER/cER functional asymmetry, tubular ER generation, and ER inheritance blocks. Thus, Reticulon/Yop1-dependent changes in ER structure are linked to ER inheritance during the yeast cell cycle.

  6. WHO's End TB Strategy: From stopping to ending the global TB epidemic.

    PubMed

    Uplekar, Mukund; Raviglione, Mario

    2015-10-01

    The 67th World Health Assembly of 2014 adopted the "End TB Strategy" with a vision of making the world free of tuberculosis (TB) and with the goal of ending the global TB epidemic by the year 2035. World Health Organization's "End TB Strategy" captures this holistic response in its four principles and three pillars. The three high-level indicators of the "End TB Strategy" - reductions in TB deaths, reductions in the TB incidence rate and the percentage of TB patients and their households experiencing catastrophic costs - are relevant to all countries.

  7. Litigation as TB Rights Advocacy

    PubMed Central

    2016-01-01

    Abstract One thousand people die every day in India as a result of TB, a preventable and treatable disease, even though the Constitution of India, government schemes, and international law guarantee available, accessible, acceptable, quality health care. Failure to address the spread of TB and to provide quality treatment to all affected populations constitutes a public health and human rights emergency that demands action and accountability. As part of a broader strategy, health activists in India employ Public Interest Litigation (PIL) to hold the state accountable for rights violations and to demand new legislation, standards for patient care, accountability for under-spending, improvements in services at individual facilities, and access to government entitlements in marginalized communities. Taking inspiration from right to health PIL cases (PILs), lawyers in a New Delhi-based rights organization used desk research, fact-findings, and the Right To Information Act to build a TB PIL for the Delhi High Court, Sanjai Sharma v. NCT of Delhi and Others (2015). The case argues that inadequate implementation of government TB schemes violates the Constitutional rights to life, health, food, and equality. Although PILs face substantial challenges, this paper concludes that litigation can be a crucial advocacy and accountability tool for people living with TB and their allies. PMID:27781000

  8. The regulation of ER export and Golgi retention of ST3Gal5 (GM3/GM4 synthase) and B4GalNAcT1 (GM2/GD2/GA2 synthase) by arginine/lysine-based motif adjacent to the transmembrane domain.

    PubMed

    Uemura, Satoshi; Shishido, Fumi; Kashimura, Madoka; Inokuchi, Jin-ichi

    2015-12-01

    In the Golgi maturation model, the Golgi cisternae dynamically mature along a secretory pathway. In this dynamic process, glycosyltransferases are transported from the endoplasmic reticulum (ER) to the Golgi apparatus where they remain and function. The precise mechanism behind this maturation process remains unclear. We investigated two glycosyltransferases, ST3Gal5 (ST3G5) and B4GalNAcT1 (B4GN1), involved in ganglioside synthesis and examined their signal sequences for ER export and Golgi retention. Reports have suggested that the [R/K](X)[R/K] motif functions as an ER exporting signal; however, this signal sequence is insufficient in stably expressed, full-length ST3G5. Through further analysis, we have clarified that the (2)R(3)R(X)(5) (9)K(X)(3) (13)K sequence in ST3G5 is essential for ER export. We have named the sequence the R/K-based motif. On the other hand, for ER export of B4GN1, the homodimer formation in addition to the R/K-based motif is required for ER export suggesting the importance of unidentified lumenal side interaction. We found that ST3G5 R2A/R3A and K9A/K13A mutants localized not only in Golgi apparatus but also in endosomes. Furthermore, the amounts of mature type asparagine-linked (N)-glycans in ST3G5 R2A/R3A and K9A/K13A mutants were decreased compared with those in wild-type proteins, and the stability of the mutants was lower. These results suggest that the R/K-based motif is necessary for the Golgi retention of ST3G5 and that the retention is involved in the maturation of N-glycans and in stability. Thus, several basic amino acids located on the cytoplasmic tail of ST3G5 play important roles in both ER export and Golgi retention.

  9. TB vaccines in clinical development.

    PubMed

    Ginsberg, Ann M; Ruhwald, Morten; Mearns, Helen; McShane, Helen

    2016-08-01

    The 4th Global Forum on TB Vaccines, convened in Shanghai, China, from 21 - 24 April 2015, brought together a wide and diverse community involved in tuberculosis vaccine research and development to discuss the current status of, and future directions for this critical effort. This paper summarizes the sessions on TB Vaccines in Clinical Development, and Clinical Research: Data and Findings. Summaries of all sessions from the 4th Global Forum are compiled in a special supplement of Tuberculosis. [August 2016, Vol 99, Supp S1, S1-S30].

  10. HIV-Associated TB: Facts 2013

    MedlinePlus

    ... HIV worldwide are infected with latent TB. Persons co-infected with TB and HIV are 29.6 ... 5 million in 2011).  Antiretroviral therapy (ART) and co-trimoxazole preventive therapy (CPT) should be given to ...

  11. Is TB in Your Curriculum?

    ERIC Educational Resources Information Center

    Kerr, Joanne; Elwell, Jack

    2002-01-01

    Points out the importance of effective health education to fight against tuberculosis (TB) which is the number one fatal infectious disease around the world. Describes a science curriculum on tuberculosis that includes information on the facts about tuberculosis, a forum on tuberculosis, and evaluation. (Contains 17 references.) (YDS)

  12. NaGd(MoO4)2 nanocrystals with diverse morphologies: controlled synthesis, growth mechanism, photoluminescence and thermometric properties

    PubMed Central

    Li, Anming; Xu, Dekang; Lin, Hao; Yang, Shenghong; Shao, Yuanzhi; Zhang, Yueli

    2016-01-01

    Pure tetragonal phase, uniform and well-crystallized sodium gadolinium molybdate (NaGd(MoO4)2) nanocrystals with diverse morphologies, e.g. nanocylinders, nanocubes and square nanoplates have been selectively synthesized via oleic acid-mediated hydrothermal method. The phase, structure, morphology and composition of the as-synthesized products are studied. Contents of both sodium molybdate and oleic acid of the precursor solutions are found to affect the morphologies of the products significantly, and oleic acid plays a key role in the morphology-controlled synthesis of NaGd(MoO4)2 nanocrystals with diverse morphologies. Growth mechanism of NaGd(MoO4)2 nanocrystals is proposed based on time-dependent morphology evolution and X-ray diffraction analysis. Morphology-dependent down-shifting photoluminescence properties of NaGd(MoO4)2: Eu3+ nanocrystals, and upconversion photoluminescence properties of NaGd(MoO4)2: Yb3+/Er3+ and Yb3+/Tm3+ nanoplates are investigated in detail. Charge transfer band in the down-shifting excitation spectra shows a slight blue-shift, and the luminescence intensities and lifetimes of Eu3+ are decreased gradually with the morphology of the nanocrystals varying from nanocubes to thin square nanoplates. Upconversion energy transfer mechanisms of NaGd(MoO4)2: Yb3+/Er3+, Yb3+/Tm3+ nanoplates are proposed based on the energy level scheme and power dependence of upconversion emissions. Thermometric properties of NaGd(MoO4)2: Yb3+/Er3+ nanoplates are investigated, and the maximum sensitivity is determined to be 0.01333 K−1 at 285 K. PMID:27506629

  13. NaGd(MoO4)2 nanocrystals with diverse morphologies: controlled synthesis, growth mechanism, photoluminescence and thermometric properties

    NASA Astrophysics Data System (ADS)

    Li, Anming; Xu, Dekang; Lin, Hao; Yang, Shenghong; Shao, Yuanzhi; Zhang, Yueli

    2016-08-01

    Pure tetragonal phase, uniform and well-crystallized sodium gadolinium molybdate (NaGd(MoO4)2) nanocrystals with diverse morphologies, e.g. nanocylinders, nanocubes and square nanoplates have been selectively synthesized via oleic acid-mediated hydrothermal method. The phase, structure, morphology and composition of the as-synthesized products are studied. Contents of both sodium molybdate and oleic acid of the precursor solutions are found to affect the morphologies of the products significantly, and oleic acid plays a key role in the morphology-controlled synthesis of NaGd(MoO4)2 nanocrystals with diverse morphologies. Growth mechanism of NaGd(MoO4)2 nanocrystals is proposed based on time-dependent morphology evolution and X-ray diffraction analysis. Morphology-dependent down-shifting photoluminescence properties of NaGd(MoO4)2: Eu3+ nanocrystals, and upconversion photoluminescence properties of NaGd(MoO4)2: Yb3+/Er3+ and Yb3+/Tm3+ nanoplates are investigated in detail. Charge transfer band in the down-shifting excitation spectra shows a slight blue-shift, and the luminescence intensities and lifetimes of Eu3+ are decreased gradually with the morphology of the nanocrystals varying from nanocubes to thin square nanoplates. Upconversion energy transfer mechanisms of NaGd(MoO4)2: Yb3+/Er3+, Yb3+/Tm3+ nanoplates are proposed based on the energy level scheme and power dependence of upconversion emissions. Thermometric properties of NaGd(MoO4)2: Yb3+/Er3+ nanoplates are investigated, and the maximum sensitivity is determined to be 0.01333 K‑1 at 285 K.

  14. Comparison of GD2 Binding Capture ELISA Assays for Anti-GD2-Antibodies Using GD2-Coated Plates and a GD2-Expressing Cell-Based ELISA

    PubMed Central

    Soman, Gopalan; Yang, Xiaoyi; Jiang, Hengguang; Giardina, Steve; Mitra, Gautam

    2011-01-01

    Two assay methods for quantification of the disialoganglioside (GD2)-specific binding activities of anti-GD2 monoclonal antibodies and antibody immunofusion proteins, such as ch14.18 and hu14.18-IL2, were developed. The methods differed in the use of either microtiter plates coated with purified GD2 or plates seeded with GD2-expressing cell lines to bind the anti-GD2 molecules. The bound antibodies were subsequently detected using the reactivity of the antibodies to an HRP-labeled anti-IgG Fc or antibodies recognizing the conjugate IL-2 part of the Hu 14.18IL-2 fusion protein. The bound HRP was detected using reagents such as orthophenylene diamine, 2, 2’-azinobis [3-ethylbenzothiazoline-6-sulfonic acid] or tetramethylbenzidine. The capture ELISA using GD2-coated plates was developed earlier in assay development and used to demonstrate assay specificity and to compare lot-to-lot consistency and stability of ch14.18, and Hu14.18 IL-2 in clinical development. During this study, we found a number of issues related to plate-to-plate variability, GD2 lot variability, and variations due to GD2 storage stability, etc., that frequently lead to assay failure in plates coated with purified GD2. The cell-based ELISA (CbELISA) using the GD2 expressing melanoma cell line, M21/P6, was developed as an alternative to the GD2-coated plate ELISA. The results on the comparability of the capture ELISA on GD2-coated plates and the cell-based assay show that both assays give comparable results. However, the cell-based assay is more consistent and reproducible. Subsequently, the anti-GD2 capture ELISA using the GD2-coated plate was replaced with the CbELISA for product lot release testing and stability assessment. PMID:21893062

  15. Morphotropic phase boundary and magnetoelastic behaviour in ferromagnetic Tb1-xGdxFe2 system

    SciTech Connect

    Adil, Murtaza; Yang, Sen; Mi, Meng; Zhou, Chao; Wang, Jieqiong; Zhang, Rui; Liao, Xiaoqi; Wang, Yu; Ren, Xiaobing; Song, Xiaoping; Ren, Yang

    2015-03-30

    Morphotropic phase boundary (MPB), separating two ferroic phases of different crystal symmetries, has been studied extensively for its extraordinary enhancement of piezoelectricity in ferroelectrics. Based on the same mechanism, we have designed a magnetic MPB in the pseudobinary ferromagnetic system of Tb1-xGdxFe2 and the corresponding crystal structure, magnetic properties, and magnetostriction are explored. With the synchrotron x-ray diffractometry, the structure symmetry of TbFe2-rich compositions is detected to be rhombohedral (R) and that of GdFe2-rich compositions is tetragonal (T) below T-c. With the change of concentration, the value of magnetostriction of the samples changes monotonously, while the MPB composition Tb0.1Gd0.9Fe2, which corresponds to the coexistence of R and T phases, exhibits the maximum magnetization among all available compositions and superposition of magnetostriction behaviour of R and T phases. Our result of MPB phenomena in ferromagnets may provide an effective route to design functional magnetic materials with exotic properties. (C) 2015 AIP Publishing LLC.

  16. Controllable Synthesis of Monodisperse Er3+-Doped Lanthanide Oxyfluorides Nanocrystals with Intense Mid-Infrared Emission

    PubMed Central

    He, Huilin; Liu, Qiang; Yang, Dandan; Pan, Qiwen; Qiu, Jianrong; Dong, Guoping

    2016-01-01

    Monodisperse lanthanide oxyfluorides LnOF (Ln = Gd, Y) with mid-infrared emissions were controllably synthesized via a mild co-precipitation route and a subsequent heat-treatment. The detailed composition and morphology were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and high resolution transmission electron microscopy (HRTEM). The results showed that monodisperse GdOF:Er3+ were nano-riced shape with length about 350 nm and width about 120 nm, while the quasi-spherical YOF:Er3+ were uniform nanocrystals with an average size around 100 nm. The influence of calcination temperature on the size and phase transition of LnOF nanocrystals was also investigated. The photoluminescence (PL) spectra indicated that the 2.7 μm emission of Er3+ had achieved in both GdOF and YOF nanocrystals, which were calcined at different temperatures. In addition, the decay time of both 4I13/2 and 4I13/2 energy levels corresponding to Er3+ in YOF nanocrystals were also studied in detail. The results suggested that both rice-shaped GdOF nanocrystals and YOF nanocrystals could provide suitable candidate materials for nanocrystals-glass composites, which could be a step forward to the realization of mid-infrared laser materials. PMID:27748411

  17. Controllable Synthesis of Monodisperse Er3+-Doped Lanthanide Oxyfluorides Nanocrystals with Intense Mid-Infrared Emission

    NASA Astrophysics Data System (ADS)

    He, Huilin; Liu, Qiang; Yang, Dandan; Pan, Qiwen; Qiu, Jianrong; Dong, Guoping

    2016-10-01

    Monodisperse lanthanide oxyfluorides LnOF (Ln = Gd, Y) with mid-infrared emissions were controllably synthesized via a mild co-precipitation route and a subsequent heat-treatment. The detailed composition and morphology were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and high resolution transmission electron microscopy (HRTEM). The results showed that monodisperse GdOF:Er3+ were nano-riced shape with length about 350 nm and width about 120 nm, while the quasi-spherical YOF:Er3+ were uniform nanocrystals with an average size around 100 nm. The influence of calcination temperature on the size and phase transition of LnOF nanocrystals was also investigated. The photoluminescence (PL) spectra indicated that the 2.7 μm emission of Er3+ had achieved in both GdOF and YOF nanocrystals, which were calcined at different temperatures. In addition, the decay time of both 4I13/2 and 4I13/2 energy levels corresponding to Er3+ in YOF nanocrystals were also studied in detail. The results suggested that both rice-shaped GdOF nanocrystals and YOF nanocrystals could provide suitable candidate materials for nanocrystals-glass composites, which could be a step forward to the realization of mid-infrared laser materials.

  18. Immigrant screening for TB: a missed opportunity to improve TB control in the United Kingdom.

    PubMed

    Lalvani, Ajit; Pareek, Manish

    2012-03-01

    Tuberculosis in the United Kingdom and other high-income countries is primarily a disease of the foreign-born arising from the synergy of migration from high TB burden regions and the reactivation of remotely acquired latent TB infection. UK immigrant screening policy primarily aims to identify active, rather than latent, TB although mounting evidence indicates that implementing latent TB screening for new entrants from intermediate and high incidence countries could cost-effectively reduce TB incidence in the UK.

  19. Magnetoelastic properties of substituted Er1-xGdxMn6Sn6 intermetallic system

    NASA Astrophysics Data System (ADS)

    Tabatabai Yazdi, Sh.; Tajabor, N.; Roknabadi, M. Rezaee; Behdani, M.; Pourarian, F.

    2014-06-01

    The forced magnetostriction of polycrystalline samples of Er1-xGdxMn6Sn6 (0≤x≤1) intermetallics with hexagonal HfFe6Ge6-type structure is investigated in the temperature range of 77-480 K. Gd substitution has a significant effect on interatomic distances and especially on inter-sublattice R-Mn couplings. The replacement of Er by Gd results in increasing the ordering temperature followed by reinforcement of the R-Mn coupling, as well as decreasing the magnetostriction values owing to the S-state character of Gd3+ ions. The results show that the contribution of Er sublattice to anisotropic magnetoelastic effects is positive, while that of Gd and Mn is negative. All the examined samples exhibit considerable magnetovolume anomalies at the ordering temperature (TC=338, 381, 412 and 434 K for the samples with x=0, 0.2, 0.6 and 1.0, respectively). While the unsubstituted sample exhibits metamagnetic transitions, Gd-contained compounds do not show this behavior, owing to the strong Gd-Mn coupling. The experimental results obtained are discussed in the framework of the two-magnetic sublattice by bearing in mind the lattice parameter dependence of the interlayer Mn-Mn exchange interaction in these layered compounds. From the temperature dependence of magnetostriction values and considering the magnetostriction equation for a hexagonal structure, we attempt to determine the signs of some of the magnetostriction constants for these compounds and the influence of Gd substitution on them.

  20. Recent advances in testing for latent TB.

    PubMed

    Schluger, Neil W; Burzynski, Joseph

    2010-12-01

    After more than a century of relying on skin testing for the diagnosis of latent TB infection, clinicians now have access to blood-based diagnostics in the form of interferon γ release assays (IGRAs). These tests are generally associated with higher sensitivity and specificity for diagnosis of latent TB infection. This article reviews the indications for testing and treatment of latent TB infection in the overall context of a TB control program and describes how IGRAs might be used in specific clinical settings and populations, including people having close contact with an active case of TB, the foreign born, and health-care workers.

  1. Judd-Ofelt analysis of the Er3+ (4f11) absorption intensities in Er3+-doped garnets

    NASA Astrophysics Data System (ADS)

    Sardar, Dhiraj K.; Bradley, William M.; Perez, John J.; Gruber, John B.; Zandi, Bahram; Hutchinson, J. Andrew; Trussell, C. Ward; Kokta, Milan R.

    2003-03-01

    Spectroscopic and laser properties of three different Er3+-doped garnet systems are characterized by employing the Judd-Ofelt (JO) analysis. The three garnet hosts are Y3Al5O12 (YAG), Y3Sc2Ga3O12 (YSGG), and Gd3Ga5O12 (GGG). The JO model has been applied to the room temperature absorption intensities of Er3+ (4f11) transitions to establish the so-called JO intensity parameters: Ω2, Ω4, and Ω6 in the three garnet hosts. The intensity parameters are used to determine the radiative decay rates (emission probabilities of transitions) and branching ratios of the Er3+ transitions from the excited state J manifolds to the lower-lying J' manifolds. The predicted decay rates and branching ratios of these Er3+ transitions in YAG, YSGG, and GGG hosts are compared. From the radiative decay rates, the radiative lifetimes of the Er3+ excited states are determined in the three garnets and are also compared. We also report the spectroscopic quality factors, Ω4/Ω6, obtained for the three garnets. The quantum efficiencies of the 4I13/2→4I15/2 Er3+ transition in YAG, YSGG, and GGG are determined to be ˜79%, 82%, and 85%, respectively.

  2. Co-Fe-Tb (202)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 2 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from B-Be-Fe to Co-W-Zr' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Co-Fe-Tb (202)' with the content:

  3. B-Fe-Tb (148)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 2 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from B-Be-Fe to Co-W-Zr' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'B-Fe-Tb (148)' with the content:

  4. {beta}-Decay Half-Lives of New Neutron-Rich Isotopes of Elements from Pm to Tb

    SciTech Connect

    S. Ichikawa; M. Asai; K. Tsukada; A. Osa; M. Sakama; Y. Kojima; M. Shibata; I. Nishinaka; Y. Nagame; Y. Oura; K. Kawade

    1999-12-31

    Eight new neutron-rich lanthanide isotopes produced in the proton-induced fission of {sup 238}U have been identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. For six of these, each half-life was determined: {sup 159}Pm (2 {+-} 1 s), {sup 161}Sm (4.8 {+-} 0.8 s), {sup 165}Gd (10.3 {+-} 1.6 s), {sup 166}Tb (21 {+-} 6 s), {sup 167}Tb (19.4 {+-} 2.7 s) and {sup 168}Tb (8.2 {+-} 1.3 s). The observed half-lives were compared with theoretical calculations. The recent calculation by the gross theory with the new one-particle strength function shows quite good agreement with the experimental half-lives.

  5. {beta}-decay half-lives of new neutron-rich isotopes of elements from Pm to Tb

    SciTech Connect

    Ichikawa, S.; Asai, M.; Tsukada, K.; Nishinaka, I.; Nagame, Y.; Osa, A.; Sakama, M.; Oura, Y.; Kojima, Y.; Shibata, M.; Kawade, K.

    1999-11-16

    Eight new neutron-rich lanthanide isotopes produced in the proton-induced fission of {sup 238}U have been identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. For six of these, each half-life was determined: {sup 159}Pm (2{+-}1 s), {sup 161}Sm (4.8{+-}0.8 s), {sup 165}Gd (10.3{+-}1.6 s), {sup 166}Tb (21{+-}6 s), {sup 167}Tb (19.4{+-}2.7 s) and {sup 168}Tb (8.2{+-}1.3 s). The observed half-lives were compared with theoretical calculations. The recent calculation by the gross theory with the new one-particle strength function shows quite good agreement with the experimental half-lives.

  6. Spectroscopy of Gd153 and Gd157 using the (p,dγ) reaction

    DOE PAGES

    Ross, T. J.; Hughes, R. O.; Allmond, J. M.; ...

    2014-10-31

    Low-spin single quasineutron levels in 153Gd and 157Gd have been studied following the 154Gd(p,d-γ )153Gd and 158Gd(p,d-γ )157Gd reactions. A combined Si telescope and high-purity germanium array was utilized, allowing d-γ and d-γ-γ coincidence measurements. Almost all of the established low-excitation-energy, low-spin structures were confirmed in both 153Gd and 157Gd. Several new levels and numerous new rays are observed in both nuclei, particularly for Ex ≥1 MeV. Lastly, residual effects of a neutron subshell closure at N = 64 are observed in the form of a large excitation energy gap in the single quasineutron level schemes.

  7. Structure, optical and photoluminescence properties of LiGd1-xErx(WO4)2 green luminescence phosphor

    NASA Astrophysics Data System (ADS)

    Demiaï, A.; Derbal, M.; Guerbous, L.; Rekik, B.

    2017-03-01

    Double tungstate of lithium and trivalent gadolinium ions were prepared by mean of solid state reaction, and have been studied using X-ray diffraction, Raman scattering and photoluminescence analysis. The Er3+ concentration effects on the structural and optical properties were studied. The compounds crystallize in the scheelite like structure with space group I41/a, and Z = 2. Spectroscopic and structural properties of the Er3+ ions doping elements in LiGd(WO4)2 have been determined at room temperature. Steady and time resolved photoluminescence spectroscopies of the synthesized compounds are reported. Samples exhibit intense green emission of Er3+ (4S3/2 → 4I15/2 and 2H11/2 → 4I15/2 transitions) under 377 nm excitation wavelength and present luminescent quenching around 3 at% Er3+ concentration. The decay time decrease with increasing the Er3+ concentration.

  8. Ferromagnetic properties of fcc Gd thin films

    SciTech Connect

    Bertelli, T. P. Passamani, E. C.; Larica, C.; Nascimento, V. P.; Takeuchi, A. Y.

    2015-05-28

    Magnetic properties of sputtered Gd thin films grown on Si (100) substrates kept at two different temperatures were investigated using X-ray diffraction, ac magnetic susceptibility, and dc magnetization measurements. The obtained Gd thin films have a mixture of hcp and fcc structures, but with their fractions depending on the substrate temperature T{sub S} and film thickness x. Gd fcc samples were obtained when T{sub S} = 763 K and x = 10 nm, while the hcp structure was stabilized for lower T{sub S} (300 K) and thicker film (20 nm). The fcc structure is formed on the Ta buffer layer, while the hcp phase grows on the fcc Gd layer as a consequence of the lattice relaxation process. Spin reorientation phenomenon, commonly found in bulk Gd species, was also observed in the hcp Gd thin film. This phenomenon is assumed to cause the magnetization anomalous increase observed below 50 K in stressed Gd films. Magnetic properties of fcc Gd thin films are: Curie temperature above 300 K, saturation magnetization value of about 175 emu/cm{sup 3}, and coercive field of about 100 Oe at 300 K; features that allow us to classify Gd thin films, with fcc structure, as a soft ferromagnetic material.

  9. Energies, Wavelengths, and Transition Rates for Ga-Like Ions (Nd XXX-Tb XXXV)

    NASA Astrophysics Data System (ADS)

    El-Sayed, Fatma; Attia, S. M.

    2016-03-01

    Energies, wavelengths, transition probabilities, oscillator strengths, and line strengths have been calculated for 4s24p-4s4p2 and 4s24p-4s24d transitions in gallium-like ions from Z = 60 to 65, for Nd XXX, Pm XXXI, Sm XXXII, Eu XXXIII, Gd XXXIV, and Tb XXXV using the fully relativistic multiconfi guration Dirac-Fock method. The correlation with the n = 4 complex and the quantum electrodynamic effects have been considered in the calculations. The obtained results have been compared with the available experimental and other theoretical results.

  10. Immunity to TB and targets for immunotherapy.

    PubMed

    Gonzalez-Juarrero, Mercedes

    2012-02-01

    For centuries the treatment of TB has presented an enormous challenge to global health. In the 20th century, the treatment of TB patients with long-term multidrug therapy gave hope that TB could be controlled and cured; however, contrary to these expectations and coinciding with the emergence of AIDS, the world has witnessed a rampant increase in hard-to-treat cases of TB, along with the emergence of highly virulent and multidrug-resistant Mycobacterium tuberculosis strains. Unfortunately, these bacteria are now circulating around the world, and there are few effective drugs to treat them. As a result, the prospects for improved treatment and control of TB in the 21st century have worsened and we urgently need to identify new therapies that deal with this problem. The potential use of immunotherapy for TB is now of greater consideration than ever before, as immunotherapy could potentially overcome the problem of drug resistance. TB immunotherapy targets the already existing host anti-TB immune response and aims to enhance killing of the bacilli. For this purpose, several approaches have been used: the use of anti-Mycobacteria antibodies; enhancing the Th1 protective responses by using mycobacterial antigens or increasing Th1 cytokines; interfering with the inflammatory process and targeting of immunosuppressive pathways and targeting the cell activation/proliferation pathways. This article reviews our current understanding of TB immunity and targets for immunotherapy that could be used in combination with current TB chemotherapy.

  11. ER-2 in flight

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In this film clip, we see an ER-2 on its take off roll and climb as it departs from runway 22 at Edwards AFB, California. In 1981, NASA acquired its first ER-2 aircraft. The agency obtained a second ER-2 in 1989. These airplanes replaced two Lockheed U-2 aircraft, which NASA had used to collect scientific data since 1971. The U-2, and later the ER-2, were based at the Ames Research Center, Moffett Field, California, until 1997. In 1997, the ER-2 aircraft and their operations moved to NASA Dryden Flight Research Center, Edwards, California. Since the inaugural flight for this program, August 31, 1971, NASA U-2 and ER-2 aircraft have flown more than 4,000 data missions and test flights in support of scientific research conducted by scientists from NASA, other federal agencies, states, universities, and the private sector. NASA is currently using two ER-2 Airborne Science aircraft as flying laboratories. The aircraft, based at NASA Dryden, collect information about our surroundings, including Earth resources, celestial observations, atmospheric chemistry and dynamics, and oceanic processes. The aircraft also are used for electronic sensor research and development, satellite calibration, and satellite data validation. The ER-2 is a versatile aircraft well-suited to perform multiple mission tasks. It is 30 percent larger than the U-2 with a 20 feet longer wingspan and a considerably increased payload over the older airframe. The aircraft has four large pressurized experiment compartments and a high-capacity AC/DC electrical system, permitting it to carry a variety of payloads on a single mission. The modular design of the aircraft permits rapid installation or removal of payloads to meet changing mission requirements. The ER-2 has a range beyond 3,000 miles (4800 kilometers); is capable of long flight duration and can operate at altitudes up to 70,000 feet (21.3 kilometers) if required. Operating at an altitude of 65,000 feet (19.8 kilometers) the ER-2 acquires data

  12. TB vaccine development and the End TB Strategy: importance and current status.

    PubMed

    Fletcher, Helen A; Schrager, Lewis

    2016-04-01

    TB is now the leading, global cause of death due to a single infectious microbe. To achieve the End TB vision of reducing TB by 90% by 2035 we will need new interventions. The objectives of this manuscript are to summarize the status of the clinical TB vaccine pipeline; to assess the challenges facing the TB development field; and to discuss some of the key strategies being embraced by the field to overcome these challenges. Currently, 8 of the 13 vaccines in clinical development are subunit vaccines; 6 of these contain or express either Ag85A or Ag85B proteins. A major challenge to TB vaccine development is the lack of diversity in both the antigens included in TB vaccines, and the immune responses elicited by TB vaccine candidates. Both will need to be expanded to maximise the potential for developing a successful candidate by 2025. Current research efforts are focused on broadening both antigen selection and the range of vaccine-mediated immune responses. Previous and ongoing TB vaccine efficacy trials have built capacity, generated high quality data on TB incidence and prevalence, and provided insight into immune correlates of risk of TB disease. These gains will enable the design of better TB vaccines and, importantly, move these vaccines into efficacy trials more rapidly and at a lower cost than was possible for previous TB vaccine candidates.

  13. Synthesizing Skyrmion Molecules in Fe-Gd Thin Films

    NASA Astrophysics Data System (ADS)

    Lee, J. C. T.; Chess, J.; Montoya, S. A.; Shi, X. W.; Tamura, Nobumichi; Mishra, S. K.; Parks, D. H.; Fischer, P.; McMorran, B.; Sinha, S. K.; Fullerton, E.; Kevan, S. D.; Roy, S.

    Controlled creation of tunable skyrmion phases at room temperature holds the promise of advanced spintronics applications using these topological entities. By varying the composition and thickness of an amorphous Fe-Gd thin film and optimizing the applied field protocol, we produced at room temperature an ordered, achiral phase of skyrmion molecules, that is, bound pairs of magnetic skyrmions having the same polarity but opposite helicity. This phase appears between stripe and uniform magnetization phase and its origin lies in the existence of mirror planes in the stripe domain structure. Dipolar, exchange, and anisotropy forces are the dominant interactions in these materials, while the role of bulk and surface chiral exchange interactions is small. Supported by the Basic Energy Sciences, US DOE: DE-AC02-05CH11231; DE- FG02-11ER46831; and DE-SC0003678.

  14. Gadolinium (Gd) Oxide, Carbide, and Carbonyl Cation Bond Energies and Evaluation of the Gd + O → GdO(+) + e(-) Chemi-Ionization Reaction Enthalpy.

    PubMed

    Demireva, Maria; Kim, JungSoo; Armentrout, P B

    2016-11-03

    Guided ion beam mass spectrometry (GIBMS) is used to measure the kinetic energy dependent product ion cross sections for reactions of the lanthanide metal gadolinium cation (Gd(+)) with O2, CO2, and CO and for reactions of GdO(+) with CO, O2, and Xe. GdO(+) is formed through barrierless and exothermic processes in the reactions of Gd(+) with O2 and CO2. All other reactions observed are endothermic, and analyses of their kinetic energy dependent cross sections yield 0 K bond dissociation energies (BDEs) for GdO(+), GdC(+), and GdCO(+). The 0 K BDE for GdO(+) is determined from five different reactions to be 7.69 ± 0.10 eV, and this value is combined with literature data to derive the ionization energy (IE) of GdO as 5.82 ± 0.16 eV. Additionally, GdC(+) and GdCO(+) BDEs of 3.18 ± 0.18 eV and 0.65 ± 0.06 eV are obtained from analysis of the Gd(+) reactions with CO and CO2, respectively. Theoretical GdO(+), GdC(+), and GdCO(+) BDEs are calculated for comparison with experiment using various Gd basis sets with an effective core potential and several levels of theory. For calculations that correctly predict a (10)D ground state for Gd(+), good agreement between theoretical and measured GdC(+) and GdCO(+) BDEs is obtained, whereas the GdO(+) BDE is underestimated in these calculations by about 0.8 eV. Additional BDEs for GdO(+) and GdC(+) are calculated using triple- and quadruple-ζ correlation consistent all-electron basis sets for Gd. Calculations with these basis sets provide better agreement with experiment for GdO(+) but not for GdC(+). The measured Gd(+) oxide, carbide, and carbonyl BDEs are similar to those for the group 3 metal ions, Sc(+) and Y(+). This is attributed to similarities in the ground state electronic configurations of these metal ions leading to similar interaction strengths. The experimental GdO(+) BDE measured here combined with the known IE of Gd is used to determine an exothermicity of 1.54 ± 0.10 eV for the Gd chemi-ionization reaction

  15. Scintillating screens based on the LPE grown Tb3Al5O12:Ce single crystalline films

    NASA Astrophysics Data System (ADS)

    Zorenko, Yuriy; Douissard, Paul-Antoine; Martin, Thierry; Riva, Federica; Gorbenko, Vitaliy; Zorenko, Tetiana; Paprocki, Kazimierz; Iskalieva, Aizhan; Witkiewicz, Sandra; Fedorov, Alexander; Bilski, Paweł; Twardak, Anna

    2017-03-01

    We report in this work the creation of new heavy and efficient Tb3Al5O12:Ce (TbAG:Ce) single crystalline film (SCF) scintillators, grown by LPE method from PbO-B2O3 based flux onto Y3Al5O12 (YAG) and Gd3Ga2.5Al2.5O12 (GAGG) substrates, for different optoelectronic applications. The luminescent and scintillation properties of the TbAG:Ce SCF screens, grown onto different types of substrates, are studied and compared with the properties of the Lu3Al5O12:Ce (LuAG:Ce) and YAG:Ce SCF counterparts. TbAG:Ce SCFs show very high scintillation light yield (LY) under α-particles excitation, which overcomes by 30% the LY of high-quality LuAG:Ce SCF samples. In comparison with YAG:Ce and LuAG:Ce SCFs, TbAG:Ce SCF screens show also significantly lower afterglow (up to 10-4 level at X-ray burst duration of 0.1 s), which is comparable with the afterglow level of the best samples of LSO:Ce, Tb SCFs typically being used now for microimaging. Together with a high light output of X-ray excited luminescence, such extremely low afterglow of TbAG:Ce SCF is a very good reason for future development of scintillating screens based on the mentioned garnet. We also introduce the possibility to create new types of ;film-substrate; hybrid scintillators using the LPE method for simultaneous registration of different components of ionizing radiation and microimaging based on the TbAG:Ce SCF and GAGG:Ce substrates.

  16. Barriers to managing TB in emergency departments.

    PubMed

    Morton, Rachel

    Improved management of tuberculosis is a key priority for Public Health England due to unacceptably high rates of the disease in the UK, particularly in London and other major cities. A survey of 20 staff in the acute medical unit at Queen Alexandra Hospital, Portsmouth, explored potential barriers to early TB detection and infection control in busy emergency departments. Low awareness and little familiarity with TB among many emergency admissions staff increased the likelihood of transmission from undiagnosed patients in crowded waiting areas. The study suggested regular updates on TB so staff could refresh their knowledge and awareness, and help improve TB detection and infection control.

  17. GD2-targeted immunotherapy and radioimmunotherapy

    PubMed Central

    Dobrenkov, Konstantin; Cheung, Nai-Kong

    2014-01-01

    Ganglioside GD2 is a tumor-associated surface antigen found in a broad spectrum of human cancers and stem cells. They include pediatric embryonal tumors (neuroblastoma, retinoblastoma, brain tumors, osteosarcoma, Ewing’s sarcoma, rhabdomyosarcoma), as well as adult cancers (small cell lung cancer, melanoma, soft tissue sarcomas). Because of its restricted normal tissue distribution, GD2 has been proven safe for antibody targeting. Anti-GD2 antibody is now incorporated into the standard of care for the treatment of high risk metastatic neuroblastoma. Building on this experience, novel combinations of antibody, cytokines, cells and genetically engineered products all directed at GD2 are rapidly moving into the clinic. In the review, past and present immunotherapy trials directed at GD2 will be summarized, highlighting the lessons learned and the future directions. PMID:25440605

  18. Valence photoelectron spectroscopy of Gd silicides

    SciTech Connect

    Braicovich, L. ); Puppin, E.; Lindau, I. ); Iandelli, A.; Olcese, G.L.; Palenzona, A. )

    1990-02-15

    Gd{sub 3}Si{sub 5}, GdSi, and Gd{sub 5}Si{sub 3} were investigated with photoemission spectroscopy in the photon-energy range 40.8--149 eV by exploiting the energy dependence of the photoemission cross sections and the valence resonance at the crossing of the Gd 4{ital d}-4{ital f} threshold. The modification of the spectra versus photon energy, along with their stoichiometry dependence, show the relevance of covalent mixed Gd 5{ital d}--Si 3{ital sp} states in the formation of the chemical bond. In the region close to the Fermi level an increase of the {ital d} contribution is observed. These points are discussed in connection with the existing models of the silicide bond.

  19. Preparation and characterization of [Gd(hfac)3(DTBN)(H2O)] (DTBN = di-t-butyl nitroxide). Ferromagnetic Gd(3+)-Gd3+ super-superexchange.

    PubMed

    Kanetomo, Takuya; Ishida, Takayuki

    2014-03-07

    The intramolecular radical-Gd antiferromagnetic coupling (2J1/k(B) = -11.6 K) is notably strong, as expected from our molecular design, and the intermolecular exchange coupling along the Gd-O-H···O-Gd bridges is unexpectedly ferromagnetic with the largest Gd···Gd coupling ever known (2J2/k(B) = +0.12 K).

  20. ER Stress and Angiogenesis.

    PubMed

    Binet, François; Sapieha, Przemyslaw

    2015-10-06

    Proper tissue vascularization is vital for cellular function as it delivers oxygen, nutrients, hormones, and immune cells and helps to clear cellular debris and metabolic waste products. Tissue angiogenesis occurs to satisfy energy requirements and cellular sensors of metabolic imbalance coordinate vessel growth. In this regard, the classical pathways of the unfolded protein response activated under conditions of ER stress have recently been described to generate angiomodulatory or angiostatic signals. This review elaborates on the link between angiogenesis and ER stress and discusses the implications for diseases characterized by altered vascular homeostasis, such as cancer, retinopathies, and atherosclerosis.

  1. Sensitisation of Eu(III)- and Tb(III)-based luminescence by Ir(III) units in Ir/lanthanide dyads: evidence for parallel energy-transfer and electron-transfer based mechanisms.

    PubMed

    Sykes, Daniel; Cankut, Ahmet J; Ali, Noorshida Mohd; Stephenson, Andrew; Spall, Steven J P; Parker, Simon C; Weinstein, Julia A; Ward, Michael D

    2014-05-07

    A series of blue-luminescent Ir(III) complexes with a pendant binding site for lanthanide(III) ions has been synthesized and used to prepare Ir(III)/Ln(III) dyads (Ln = Eu, Tb, Gd). Photophysical studies were used to establish mechanisms of Ir→Ln (Ln = Tb, Eu) energy-transfer. In the Ir/Gd dyads, where direct Ir→Gd energy-transfer is not possible, significant quenching of Ir-based luminescence nonetheless occurred; this can be ascribed to photoinduced electron-transfer from the photo-excited Ir unit (*Ir, (3)MLCT/(3)LC excited state) to the pendant pyrazolyl-pyridine site which becomes a good electron-acceptor when coordinated to an electropositive Gd(III) centre. This electron transfer quenches the Ir-based luminescence, leading to formation of a charge-separated {Ir(4+)}˙-(pyrazolyl-pyridine)˙(-) state, which is short-lived possibly due to fast back electron-transfer (<20 ns). In the Ir/Tb and Ir/Eu dyads this electron-transfer pathway is again operative and leads to sensitisation of Eu-based and Tb-based emission using the energy liberated from the back electron-transfer process. In addition direct Dexter-type Ir→Ln (Ln = Tb, Eu) energy-transfer occurs on a similar timescale, meaning that there are two parallel mechanisms by which excitation energy can be transferred from *Ir to the Eu/Tb centre. Time-resolved luminescence measurements on the sensitised Eu-based emission showed both fast and slow rise-time components, associated with the PET-based and Dexter-based energy-transfer mechanisms respectively. In the Ir/Tb dyads, the Ir→Tb energy-transfer is only just thermodynamically favourable, leading to rapid Tb→Ir thermally-activated back energy-transfer and non-radiative deactivation to an extent that depends on the precise energy gap between the *Ir and Tb-based (5)D4 states. Thus, the sensitised Tb(iii)-based emission is weak and unusually short-lived due to back energy transfer, but nonetheless represents rare examples of Tb(III) sensitisation by

  2. What is Multidrug and Extensively Drug Resistant TB?

    MedlinePlus

    ... org > Lung Health and Diseases > Lung Disease Lookup > Tuberculosis (TB) What Is Multidrug and Extensively Drug Resistant TB? Multidrug-resistant tuberculosis ( MDR TB ) is a very dangerous form of ...

  3. TB in Correctional Facilities Is a Public Health Concern

    MedlinePlus

    ... component to TB elimination in the United States. Tuberculosis (TB) is a disease caused by bacteria that ... is essential to these efforts. More Information Reported Tuberculosis in the United States, 2012 TB in Correctional ...

  4. Structural and magnetic properties of the Gd-based bulk metallic glasses GdFe2, GdCo2, and GdNi2 from first principles

    NASA Astrophysics Data System (ADS)

    Lizárraga, Raquel

    2016-11-01

    A structural and magnetic characterization of Gd-based bulk metallic glasses, GdFe2, GdCo2, and GdNi2, was performed. Models for the amorphous structures for two magnetic configurations, ferromagnetic and ferrimagnetic, were obtained by means of a first-principles-based method, the stochastic quenching. In all three cases, the ferrimagnetic configuration was energetically more stable than the ferromagnetic one, in perfect agreement with experiments. In the structural analysis, radial and angle distribution functions as well as calculations of bond lengths and average coordination numbers were included. Structural properties are in good agreement with experiments and do not depend on the magnetic configuration. The distribution of magnetic moments shows that amorphous GdFe2 and GdCo2 are both ferrimagnets, with antiparallel alignment of the magnetic moments of the two magnetic sublattices, whereas Ni nearly loses its magnetic moment in amorphous GdNi2, similar to the situation in its crystalline counterpart.

  5. Estimating the cost of TB and its social impact on TB patients and their households.

    PubMed

    Onazi, O; Gidado, M; Onazi, M; Daniel, O; Kuye, J; Obasanya, O; Odusote, T; Gande, S

    2015-06-21

    Illness often poses a significant financial burden on individuals and their households, and tuberculosis (TB) is no exception. Although TB treatment is free in Nigeria, patients are likely to incur costs due to multiple visits during treatment. The purpose of this study was 1) to examine the health-seeking behaviour of TB patients and the costs borne by TB patients in Nigeria, and 2) to assess the social impact of TB disease on TB patients and their families/households. Of 260 TB patients surveyed, the majority (74.7%) were aged between 20 and 49 years. TB patients expended an average of US$52.02 (N = 8323.58, at the rate of US$1 = N = 160) per person on all visits associated with diagnosis and receipt of diagnostic test results. Overall, households experienced a shortfall of about US$57.30 (N = 9174.72) or 24.9% of income loss due to TB illness. Further analysis revealed that 9.7% of TB patients relied on children of school age or below to finance the costs of TB illness.

  6. Estimating the cost of TB and its social impact on TB patients and their households

    PubMed Central

    Onazi, O.; Gidado, M.; Onazi, M.; Daniel, O.; Kuye, J.; Obasanya, O.; Odusote, T.; Gande, S.

    2015-01-01

    Illness often poses a significant financial burden on individuals and their households, and tuberculosis (TB) is no exception. Although TB treatment is free in Nigeria, patients are likely to incur costs due to multiple visits during treatment. The purpose of this study was 1) to examine the health-seeking behaviour of TB patients and the costs borne by TB patients in Nigeria, and 2) to assess the social impact of TB disease on TB patients and their families/households. Of 260 TB patients surveyed, the majority (74.7%) were aged between 20 and 49 years. TB patients expended an average of US$52.02 (N = 8323.58, at the rate of US$1 = N = 160) per person on all visits associated with diagnosis and receipt of diagnostic test results. Overall, households experienced a shortfall of about US$57.30 (N = 9174.72) or 24.9% of income loss due to TB illness. Further analysis revealed that 9.7% of TB patients relied on children of school age or below to finance the costs of TB illness. PMID:26400384

  7. 'Z(S)-MDR-TB' versus 'Z(R)-MDR-TB': improving treatment of MDR-TB by identifying pyrazinamide susceptibility.

    PubMed

    Zhang, Ying; Chiu Chang, Kwok; Leung, Chi-Chiu; Wai Yew, Wing; Gicquel, Brigitte; Fallows, Dorothy; Kaplan, Gilla; Chaisson, Richard E; Zhang, Wenhong

    2012-07-01

    Indispensable for shortening treatment of drug-susceptible tuberculosis (TB), pyrazinamide (PZA, Z) is also essential in the treatment of multidrug-resistant (MDR)-TB. While resistance to PZA in MDR-TB is associated with poor treatment outcome, bacillary susceptibility to PZA along with the use of fluoroquinolone (FQ) and second-line injectable drugs (SLIDs) may predict improved treatment success in MDR-TB. Despite a high prevalence of PZA resistance among MDR-TB patients (10%-85%), PZA susceptibility testing is seldom performed because of technical challenges. To improve treatment of MDR-TB, we propose to: (i) classify MDR-TB into PZA-susceptible MDR-TB (Z(S)-MDR-TB) and PZA-resistant MDR-TB (Z(R)-MDR-TB); (ii) use molecular tests such as DNA sequencing (pncA, gyrA, rrs, etc.) to rapidly identify Z(S)-MDR-TB versus Z(R)-MDR-TB and susceptibility profile for FQ and SLID; (iii) refrain from using PZA in Z(R)-MDR-TB; and (iv) explore the feasibility of shortening the treatment duration of Z(S)-MDR-TB with a regimen comprising PZA plus at least two bactericidal agents especially new agents like TMC207 or PA-824 or delamanid which the bacilli are susceptible to, with one or two other agents. These measures may potentially shorten therapy, save costs, and reduce side effects of MDR-TB treatment.

  8. Magnetoresistance in nanostructured Tb/Ti and Tb/Si multilayers

    SciTech Connect

    Svalov, A. V.; Kurlyandskaya, G. V.; Vas'kovskiy, V. O.; Sorokin, A. N.; Diercks, D.

    2011-01-15

    Magnetic, magnetoresistive and structural properties were studied for [Tb/Ti]{sub n} and [Tb/Si]{sub n} multilayers which were prepared by rf-sputtering. The thickness of the Tb layers varied from 1.5 to 12 nm. The thickness of 2 nm nonmagnetic spacers of Ti or Si was kept constant. Both anisotropic and isotropic magnetoresistance was observed in [Tb/Ti]{sub n} and [Tb/Si]{sub n} multilayers. A decrease in the thickness of the terbium layers led to a decrease in the anisotropic contribution to the total magnetoresistance. The negative isotropic magnetoresistanse in [Tb/Ti]{sub n} and [Tb/Si]{sub n} multilayers can be attributed to the giant magnetoresistance (GMR) and/or high field isotropic magnetoresistance. The structure of the samples of both types enabled the existence of the GMR effect.

  9. Understanding social context on TB cases

    NASA Astrophysics Data System (ADS)

    Ariyanto, Y.; Wati, D. M.

    2017-01-01

    Tuberculosis (TB) nowadays still becomes one of the world’s deadliest communicable disease. More than half were in South-East Asia and Western Pacific Regions, including Indonesia. As developing country, Indonesia remains classic problems in overcoming TB, that is discontinuation on treatment. Most of discontinuation on treatment among TB patients are affected by diagnostic delay that caused by patient delay. These phenomena occur in many areas, rural to suburb, coastal to plantation, and so on, and they are related with social context among community that could be social capital for each community to deal with TB. Jember as one of county in East Java is known as plantation area. It also has a high prevalence of TB. This study focused on understanding about social context among community, especially on plantation area. This cross-sectional study involved in three districts of Jember, those are Tanggul, Pakusari, and Kalisat. The data were obtained directly from the TB patients, local community, and Primary Health Care (PHC) where the patients recorded. Spatial analysis and social network analysis (SNA) were applied to obtain health seeking behavior pattern among the TB patients coincide the community. Most of TB patients had already chosen health professionals to lead the treatment, although some of them remained to choose self-medication. Meanwhile, SNA showed that religious leader was considered as main part of countermeasures of TB. But they didn’t ever become central figures. So it can be concluded that there are other parts among community who can contribute due to combatting on TB.

  10. Probing the structure-relaxivity relationship of bis-hydrated Gd(DOTAla) derivatives.

    PubMed

    Boros, Eszter; Caravan, Peter

    2015-03-02

    Two structural isomers of the heptadentate chelator DO3Ala were synthesized, with carboxymethyl groups at either the 1,4- or 1,7-positions of the cyclen macrocycle. To interrogate the relaxivity under different rotatational dynamics regimes, the pendant primary amine was coupled to ibuprofen to enable binding to serum albumin. These chelators 6a and 6b form bis(aqua) ternary complexes with Gd(III) or Tb(III) as estimated from relaxivity measurements or luminescence lifetime measurements in water. The relaxivity of [Gd(6a)(H2O)2] and [Gd(6b)(H2O)2] was measured in the presence and absence of coordinating anions prevalent in vivo such as phosphate, lactate, and bicarbonate and compared with data attained for the q = 2 complex [Gd(DO3A)(H2O)2]. We found that relaxivity was reduced through formation of ternary complexes with lactate and bicarbonate, albeit to a lesser degree then the relaxivity of Gd(DO3A). In the presence of 100-fold excess phosphate, relaxivity was slightly increased and typical for q = 2 complexes of this size (8.3 mM(-1) s(-1) and 9.5 mM(-1) s(-1), respectively, at 37 °C, 60 MHz). Relaxivity for the complexes in the presence of HSA corresponded well to relaxivity obtained for complexes with reduced access for inner-sphere water (13.5 and 12.7 mM(-1) s(-1) at 37 °C, 60 MHz). Mean water residency time at 37 °C was determined using temperature-dependent (17)O-T2 measurements at 11.7 T and calculated to be (310)τM = 23 ± 1 ns for both structural isomers. Kinetic inertness under forcing conditions (pH 3, competing DTPA ligand) was found to be comparable to [Gd(DO3A)(H2O)]. Overall, we found that the replacement of one of the acetate arms of DO3A with an amino-propionate arm does not significantly alter the relaxometric and kinetic inertness properties of the corresponding Gd complexes; however, it does provide access to easily functionalizable q = 2 derivatives.

  11. Synthesis and luminescent properties of Gd3Ga2Al3O12 phosphors doped with Eu3+ or Ce3+

    NASA Astrophysics Data System (ADS)

    Oh, M. J.; Kim, H. J.

    2016-09-01

    Eu3+-or Ce3+-doped gadolinium gallium aluminum garnet (GGAG), Gd3Ga2Al3O12, phosphors are fabricated using solid-state reactions with Gd2O3, Ga2O3, Al2O3, CeO2 and Eu2O3 powders. The Eu3+-or Ce3+-doped Gd3Ga2Al3O12 phosphors are sintered at 1300 °C or 1600 °C for 5 hours by using an electric furnace under normal atmosphere. X-ray diffraction and field-emission scanning electron microscopy studies are carried out in order to analyze the physical properties of these materials, and their luminescence properties are also measured by using UV and X-ray sources. The Eu3+-or Ce3+-doped Gd3Ga2Al3O12 phosphors show higher light yields in comparison to commercial phosphors such as Gd2O2S:Tb (gadox). This indicates that Gd3Ga2Al3O12:Eu3+ phosphors are promising materials for use in X-ray imaging and dose monitoring at proton beamlines.

  12. Macrocyclic Gd(3+) complexes with pendant crown ethers designed for binding zwitterionic neurotransmitters.

    PubMed

    Oukhatar, Fatima; Meudal, Hervé; Landon, Céline; Logothetis, Nikos K; Platas-Iglesias, Carlos; Angelovski, Goran; Tóth, Éva

    2015-07-27

    A series of Gd(3+) complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd(3+) chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen-type macrocycle that binds the Ln(3+) ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7 mM(-1)  s(-1) at 60 MHz, 310 K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by (1) H relaxometric titrations of the Gd(3+) complexes and by luminescence measurements on the Eu(3+) and Tb(3+) analogues at pH 7.4. The remarkable relaxivity decrease (≈80 %) observed on neurotransmitter binding is related to the decrease in the hydration number, as evidenced by luminescence lifetime measurements on the Eu(3+) complexes. These complexes show affinity for amino acid neurotransmitters in the millimolar range, which can be suited to imaging concentrations of synaptically released neurotransmitters. They display good selectivity over non-amino acid neurotransmitters (acetylcholine, serotonin, and noradrenaline) and hydrogenphosphate, but selectivity over hydrogencarbonate was not achieved.

  13. Multidrug and extensively drug-resistant TB (M/XDR-TB): problems and solutions.

    PubMed

    Prasad, Rajendra

    2010-10-01

    Multi Drug Resistant Tuberculosis (MDR-TB) and Extensively Drug Resistant Tuberculosis (XDR-TB) are posing a threat to the control of tuberculosis. The first WHO-IUATLD antituberculosis drug resistance surveillance carried out in 1994 in 35 countries reported the median prevalence of primary and acquired multi drug resistance as 1.4% and 13% respectively. Subsequently, second, third and fourth WHO-IUATLD global drug resistance surveillances were carried out in 1996-99, 1999-2002 and 2002-2007 respectively. Based on drug resistance information from 114 countries, the proportion of MDR-TB among all cases was estimated for countries with no survey information. It was estimated that 4,89,139 cases of MDR-TB emerged in 2006. China and India carry approximately 50% of the global burden. 35 countries and two Special Administrative Regions (SARs) reported data on XDR-TB for the first time in 2006. Multidrug and extensively drug-resistant TB 2010 Global report on Surveillance and response estimated that 4,40,000 cases of MDR-TB emerged globally in 2008 and caused an estimated 1,50,000 deaths. 5.4% of MDR-TB cases were found to have XDR-TB. To date, a cumulative total of 58 countries have confirmed at least one case of XDR-TB. M/XDR-TB is a man-made problem and its emergence can be prevented by prompt diagnosis and effective use of first line drugs in every new patient. The DOTS Plus proposed by WHO highlights the comprehensive management strategy to control MDR-TB. Laboratory services for adequate and timely diagnosis of M/XDR-TB must be strengthened and programmatic management of M/XDR-TB must be scaled up as per target set by global plan. Proper use of second-line drugs must be ensured to cure existing MDR-TB, to reduce its transmission and to prevent XDR-TB. Sound infection control measures to avoid further transmission of M/XDR-TB and research towards development of new diagnostics, drugs and vaccines should be promoted to control M/XDR-TB.

  14. Magnetocaloric effect in Gd-based ferromagnet GdZn2

    NASA Astrophysics Data System (ADS)

    Matsumoto, Keisuke T.; Hiraoka, Koichi

    2017-02-01

    Magnetic properties and magnetocaloric effect of the Gd-based compound GdZn2 have been investigated. GdZn2 shows a ferromagnetic transition at TC = 85 K and spin-reorientation transition at TSR = 58 K. The maximum entropy change and relative cooling power (RCP) are estimated to be 11.5 J/K kg and 690 J/kg, respectively, for a magnetic field change of 7 T. The large value of RCP is suggested that GdZn2 is an attractive candidate for a low-temperature magnetic refrigerant.

  15. Sub-6 nm monodisperse hexagonal core/shell NaGdF4 nanocrystals with enhanced upconversion photoluminescence.

    PubMed

    Liu, Jing; Chen, Guanying; Hao, Shuwei; Yang, Chunhui

    2017-01-07

    The ability to fabricate lanthanide-doped upconversion nanocrystals (UCNCs) with tailored size and emission profile has fuelled their uses in a broad spectrum of biological applications. Yet, limited success has been met in the preparation of sub-6 nm UCNCs with efficient upconversion photoluminescence (UCPL), which enable high contrast optical bioimaging with minimized adverse biological effects entailed by size-induced rapid clearance from the body. Here, we present a simple and reproducible approach to synthesize a set of monodispersed hexagonal-phase core NaGdF4:Yb/Ln (Ln = Er, Ho, Tm) of ∼3-4 nm and core/shell NaGdF4:Yb/Ln@NaGdF4 (Ln = Er, Ho, Tm) UCNCs of ∼5-6 nm. We show that the core/shell UCNCs can be up to ∼1000 times more efficient than the corresponding core UCNCs due to the effective suppression of surface-related quenching effects for the core. The observation of prolonged PL lifetime for the core/shell than that for the core UCNCs demonstrates the role of the inert shell layer for the protection of the core. The achievement of sub-6 nm NaGdF4 UCNCs with significantly improved luminescence efficiency constitutes a solid step towards high contrast UCPL optical imaging with secured biological safety.

  16. Trip to ER

    PubMed Central

    Ma, Xuan; Cao, Xiaofeng; Mo, Beixin; Chen, Xuemei

    2013-01-01

    miRNAs elicit gene silencing at the post-transcriptional level by several modes of action: translational repression, mRNA decay, and mRNA cleavage. Studies in animals have suggested that translational repression occurs at early steps of translation initiation, which can be followed by deadenylation and mRNA decay. Plant miRNAs were originally thought to solely participate in mRNA cleavage, but increasing evidence has indicated that they are also commonly involved in translational inhibition. Here we discuss recent findings on miRNA-mediated translational repression in plants. The identification of AMP1 in Arabidopsis as a protein required for the translational repression but not the mRNA cleavage activity of miRNAs links miRNA-based translational repression to the endoplasmic reticulum (ER). Future work is required to further elucidate the miRNA machinery on the ER. PMID:24100209

  17. Hydrogenation behavior of the R4MgCo (R=Y, La, Nd, Tb) compounds

    NASA Astrophysics Data System (ADS)

    Shtender, V. V.; Paul-Boncour, V.; Riabov, A. B.; Denys, R. V.; Zavaliy, I. Yu.

    2015-09-01

    The hydrogen absorption properties of the R4MgCo compounds (R=Y, La, Nd, Tb; str. type Gd4RhIn; sp.gr. F 4 bar 3 m) have been studied for the first time. It was shown that their hydrogen storage capacity reaches about 2 wt%. At low pressure hydrogenation and moderately elevated temperatures the formed hydrides preserve the original structure of the metallic matrix. The crystal structure of the R4MgCoHx hydrides have been determined by XRD. Experimental hydrogen storage capacity (12 at.H/f.u. for Y4MgCo) is in good agreement with the theoretically calculated models, which allow also to estimate the distribution of H-atoms in metal lattice. TDS and DSC experiments demonstrated the multistep desorption process. XRD studies of the Tb4MgCoHx sample after TDS demonstrated the formation of TbH2 as the main phase and disproportionation of the parent compound.

  18. Naltrexone ER/Bupropion ER: A Review in Obesity Management.

    PubMed

    Greig, Sarah L; Keating, Gillian M

    2015-07-01

    Oral naltrexone extended-release/bupropion extended-release (naltrexone ER/bupropion ER; Contrave(®), Mysimba(™)) is available as an adjunct to a reduced-calorie diet and increased physical activity in adults with an initial body mass index (BMI) of ≥ 30 kg/m(2) (i.e. obese) or a BMI of ≥ 27 kg/m(2) (i.e. overweight) in the presence of at least one bodyweight-related comorbidity, such as type 2 diabetes mellitus, hypertension or dyslipidaemia. In 56-week phase III trials in these patient populations, oral naltrexone ER/bupropion ER 32/360 mg/day was significantly more effective than placebo with regard to percentage bodyweight reductions from baseline and the proportion of patients who achieved bodyweight reductions of ≥ 5 and ≥ 10%. Significantly greater improvements in several cardiometabolic risk factors were also observed with naltrexone ER/bupropion ER versus placebo, as well as greater improvements in glycated haemoglobin levels in obese or overweight adults with type 2 diabetes. Naltrexone ER/bupropion ER was generally well tolerated in phase III trials, with nausea being the most common adverse event. Thus, naltrexone ER/bupropion ER 32/360 mg/day as an adjunct to a reduced-calorie diet and increased physical activity, is an effective and well tolerated option for chronic bodyweight management in obese adults or overweight adults with at least one bodyweight-related comorbidity.

  19. Particle-gamma studies of Gd isotopes by (p,p'), (p,d) and (p,t) reactions

    NASA Astrophysics Data System (ADS)

    Ross, T. J.; Hughes, R. O.; Beausang, C. W.; Allmond, J. M.; Burke, J. T.; Phair, L. W.; Scielzo, N.; Angell, C. T.; Basunia, M. S.; Bleuel, D. L.; Casperson, R. J.; Fallon, P.; Hatarik, R.; Munson, J.; Paschalis, S.; Petri, M.; Ressler, J. J.

    2010-11-01

    An experiment was conducted using the STARS-LIBERACE array at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory to study Gd isotopes around the N=90 transition region. A 25 MeV proton beam was incident on ^158/155/154Gd targets and used to populate states in ^152-158Gd by (p,p'), (p,d) and (p,t) reactions. This experiment compliments our earlier work on ^156Gd(p,x),[1]. The exit channel is selected by gating on charged particles using the STARS (Silicon Telescope Array for Reaction Studies) array, which also gives the excitation energy of the residual nucleus. Coincident gamma information is obtained using the LIBERACE (LIvermore BErkeley Array for Collaborative Experiments) clover detector array. Particle-gamma coincidence measurements provide a strong tool for probing the residual nucleus, [1]. Preliminary results pertaining to ^158Gd will be presented. [1] J. M. Allmond et al. Phys. Rev. C 81, 064316 (2010) This work is supported in part via DOE grant numbers DE-FG02-05 ER41379 & DE-FG52-06 NA26206(University of Richmond), DE-AC52 07NA27344(LLNL) and DE-AC02 05CH11231(LBNL).

  20. Controllable synthesis and upconversion emission of ultrasmall lanthanide-doped Sr2GdF7 nanocrystals

    NASA Astrophysics Data System (ADS)

    Xiang, Lijun; Ren, Guozhong; Mao, Yifu; He, Jin; Su, Rui

    2015-11-01

    The effect of rare-earth ions content on the phase structure, crystal size and morphology of SrF2-GdF3 system were studied under solvothermal conditions. By tuning the molar ratio of reactants, tetragonal phase Sr2GdF7 nanocrystals (NCs) were synthesized via solvothermal method using oleic acid as capping ligands. The effects of reaction conditions on the phase structure, crystal size, morphology, and upconversion (UC) emission properties of the products were investigated. The results reveal that apropos Gd3+ ions content (0.30-0.45 mmol) is favorable to the formation of pure phase Sr2GdF7 NCs with more uniform size distribution. The average crystalline size of the products can be controlled less than 10 nm. The energy transfer UC mechanisms for the fluorescent intensity were also investigated. Following Yb3+, Er3+, Tm3+ and Ho3+ ions doping, the Sr2GdF7 NCs show intense green, yellow, and white-color UC emission under the excitation of a 980 nm laser, and the doping concentration of lanthanide ions was optimized, which makes the NCs show maximum intensities under the excitation of a 980 nm laser.

  1. Staying on Track with TB Medicine

    MedlinePlus

    ... if you have other health problems like HIV infection or diabetes. • You will need treatment, whether you have TB ... disease along with other health problems, like HIV infection or diabetes, you may need to have blood, phlegm, or ...

  2. Multidrug-Resistant Tuberculosis (MDR TB)

    MedlinePlus

    ... prisons, or homeless shelters. If you work in hospitals or health-care settings where TB patients are likely to be seen, you should consult infection control or occupational health experts. Ask about administrative and ...

  3. Immunomodulation by vitamin D: implications for TB

    PubMed Central

    Chun, Rene F; Adams, John S; Hewison, Martin

    2011-01-01

    TB remains a major cause of mortality throughout the world. Low vitamin D status has been linked to increased risk of TB and other immune disorders. These observations suggest a role for vitamin D as a modulator of normal human immune function. This article will detail the cellular and molecular mechanisms by which vitamin D regulates the immune system and how vitamin D insufficiency may lead to immune dysregulation. The importance of vitamin D bioavailability as a mechanism for defining the immunomodulatory actions of vitamin D and its impact on TB will also be discussed. The overall aim will be to provide a fresh perspective on the potential benefits of vitamin D supplementation in the prevention and treatment of TB. PMID:22046197

  4. Extensively Drug-Resistant Tuberculosis (XDR TB)

    MedlinePlus

    ... Correctional and Detention Facilities Guidelines for Preventing the Transmission of M. TB in Health care Settings Investigation ... infection control measures in place. Documented places where transmission has occurred include crowded hospitals, prisons, homeless shelters, ...

  5. FPipTB, a benzimidazole derivative, induces chondrosarcoma cell apoptosis via endoplasmic reticulum stress and apoptosis signal-regulating kinase 1.

    PubMed

    Liu, Ju-Fang; Chang, Chih-Shiang; Fong, Yi-Chin; Kuo, Sheng-Chu; Tang, Chih-Hsin

    2012-04-01

    Chondrosarcoma is the second most common primary bone tumor and it responds poorly to both chemotherapy and radiation treatment. In this study, we investigated the anticancer effects of a new benzimidazole derivative, 2-(furanyl)-5-(piperidinyl)- (3,4,5-trimethoxybenzyl) benzimidazole (FPipTB) in human chondrosarcoma cells. FPipTB-induced apoptosis in human chondrosarcoma cell lines (JJ012 and SW1353) but not in primary chondrocytes. Furthermore, it triggered endoplasmic reticulum (ER) stress, which was characterized by changes in cytosolic calcium levels. Treatment of chondrosarcoma cells with FPipTB was associated with increased intracellular levels of ASK1, p38, p53, and Bax, followed by release of cytochrome c from mitochondria and activation of caspases. It is also known that ER stress activates apoptosis signal-regulating kinase 1 (ASK1), which mediates activation of JNK and p38 pathways. We also found that FPipTB-induced p38 and p53 phosphorylation and upregulated Bax expression. To study the mechanism of Bax upregulation, we determined that Bax promoter activity was increased in FPipTB-treated cells, leading to an increase in intracellular levels of Bax. In addition, cell treated with Ca(2+) chelator or p38 inhibitor showed reduced transcriptional activity. The results further suggest that FPipTB triggered ER stress, as indicated by changes in cytosolic calcium levels and activated the ASK1-MKK3/6-p38-p53-Bax pathway, causing chondrosarcoma cell death. Importantly, animal studies revealed a dramatic 40% reduction in tumor volume after 21 d of treatment. Thus, FPipTB may be a novel anticancer agent for the treatment of chondrosarcoma.

  6. Magnetic and transport properties of i-R-Cd icosahedral quasicrystals (R=Y, Gd-Tm)

    SciTech Connect

    Kong, Tai; Bud'ko, Sergey L.; Jesche, Anton; McArthur, John; Kreyssig, Andreas; Goldman, Alan I.; Canfield, Paul C.

    2014-07-01

    We present a detailed characterization of the recently discovered i-R-Cd (R=Y,Gd-Tm) binary quasicrystals by means of x-ray diffraction, temperature-dependent dc and ac magnetization, temperature-dependent resistance, and temperature-dependent specific heat measurements. Structurally, the broadening of x-ray diffraction peaks found for i-R-Cd is dominated by frozen-in phason strain, which is essentially independent of R. i-Y-Cd is weakly diamagnetic and manifests a temperature-independent susceptibility. i-Gd-Cd can be characterized as a spin glass below 4.6 K via dc magnetization cusp, a third order nonlinear magnetic susceptibility peak, a frequency-dependent freezing temperature, and a broad maximum in the specific heat. i-R-Cd (R=Ho-Tm) is similar to i-Gd-Cd in terms of features observed in thermodynamic measurements. i-Tb-Cd and i-Dy-Cd do not show a clear cusp in their zero-field-cooled dc magnetization data, but instead show a more rounded, broad local maximum. The resistivity for i-R-Cd is of order 300μΩ cm and weakly temperature dependent. The characteristic freezing temperatures for i-R-Cd (R=Gd-Tm) deviate from the de Gennes scaling, in a manner consistent with crystal electric field splitting induced local moment anisotropy.

  7. Decay-out of 151Tb Yrast Superdeformed Band and Shape Coexistence

    SciTech Connect

    Duchene, G.; Robin, J.; Odahara, A.; Byrski, Th.; Beck, F.A.; Bednarczyk, P.; Curien, D.; Courtin, S.; Dorvaux, O.; Gall, B.; Joshi, P.; Nourreddine, A.; Pachoud, E.; Piqueras, I.; Vivien, J.P.; Twin, P.J.; Cullen, D.M.; Ertueck, S.; King, S.L.; Paul, E.S.

    2004-02-27

    Linking transitions between the superdeformed (SD) and the normal deformed (ND) wells have been searched in 151Tb nucleus. Two experiments of 5 and 17 days have been performed with EUROBALL IV. Transitions of 2818 keV and 3748 keV with intensities of about 1 % relative to the yrast SD band have been observed. Their decay-out properties are discussed in the text. In addition the eight known SD bands have been extended towards higher rotational frequencies where orbital crossings are observed. For the first time, weakly populated collective ND structures, likely triaxial, similar to the ones recently identified in 152Dy, 153Ho and 155Er nuclei have been observed in 151Tb. The SD and ND structures are interpreted in the frame of Woods-Saxon theoretical calculations.

  8. Self-patterning Gd nano-fibers in Mg-Gd alloys

    PubMed Central

    Li, Yangxin; Wang, Jian; Chen, Kaiguo; Shao, Meiyue; Shen, Yao; Jin, Li; Zhu, Guo-zhen

    2016-01-01

    Manipulating the shape and distribution of strengthening units, e.g. particles, fibers, and precipitates, in a bulk metal, has been a widely applied strategy of tailoring their mechanical properties. Here, we report self-assembled patterns of Gd nano-fibers in Mg-Gd alloys for the purpose of improving their strength and deformability. 1-nm Gd nano-fibers, with a 〈c〉-rod shape, are formed and hexagonally patterned in association with Gd segregations along dislocations that nucleated during hot extrusion. Such Gd-fiber patterns are able to regulate the relative activities of slips and twinning, as a result, overcome the inherent limitations in strength and ductility of Mg alloys. This nano-fiber patterning approach could be an effective method to engineer hexagonal metals. PMID:27924848

  9. Self-patterning Gd nano-fibers in Mg-Gd alloys.

    PubMed

    Li, Yangxin; Wang, Jian; Chen, Kaiguo; Shao, Meiyue; Shen, Yao; Jin, Li; Zhu, Guo-Zhen

    2016-12-07

    Manipulating the shape and distribution of strengthening units, e.g. particles, fibers, and precipitates, in a bulk metal, has been a widely applied strategy of tailoring their mechanical properties. Here, we report self-assembled patterns of Gd nano-fibers in Mg-Gd alloys for the purpose of improving their strength and deformability. 1-nm Gd nano-fibers, with a 〈c〉-rod shape, are formed and hexagonally patterned in association with Gd segregations along dislocations that nucleated during hot extrusion. Such Gd-fiber patterns are able to regulate the relative activities of slips and twinning, as a result, overcome the inherent limitations in strength and ductility of Mg alloys. This nano-fiber patterning approach could be an effective method to engineer hexagonal metals.

  10. Self-patterning Gd nano-fibers in Mg-Gd alloys

    NASA Astrophysics Data System (ADS)

    Li, Yangxin; Wang, Jian; Chen, Kaiguo; Shao, Meiyue; Shen, Yao; Jin, Li; Zhu, Guo-Zhen

    2016-12-01

    Manipulating the shape and distribution of strengthening units, e.g. particles, fibers, and precipitates, in a bulk metal, has been a widely applied strategy of tailoring their mechanical properties. Here, we report self-assembled patterns of Gd nano-fibers in Mg-Gd alloys for the purpose of improving their strength and deformability. 1-nm Gd nano-fibers, with a -rod shape, are formed and hexagonally patterned in association with Gd segregations along dislocations that nucleated during hot extrusion. Such Gd-fiber patterns are able to regulate the relative activities of slips and twinning, as a result, overcome the inherent limitations in strength and ductility of Mg alloys. This nano-fiber patterning approach could be an effective method to engineer hexagonal metals.

  11. Compartmentalization of Gd liposomes: the quenching effect explained.

    PubMed

    Guenoun, Jamal; Doeswijk, Gabriela N; Krestin, Gabriel P; Bernsen, Monique R

    2016-01-01

    Cationic liposomes carrying high [Gd] can be used as efficient cell-labeling agents. In a compartmentalized state, Gd can cause signal loss (relaxivity quenching). The contributions of liposomal [Gd], size and compartmentalization state to relaxivity quenching were assessed. The dependency of signal intensity (SI) on intraliposomal [Gd] was assessed comparing three different [Gd] (0.3, 0.6 and 1.0 M Gd) in both small (80 nm) and large (120 nm) cationic liposomes. In addition, five compartmentalization states were compared: free Gd, intact Gd liposomes, ruptured Gd liposomes, Gd liposomes in intact cells and Gd liposomes in ruptured cells (simulating cell death). Gd also causes R2 effects, which is often overlooked. Therefore, both R1 and R2 relaxation rates of a dilution range were measured by T1 and T2 mapping on a 7 T clinical scanner. Less is more. As the unidirectional water efflux rate (outbound across the liposome membrane, κle) is proportional to the surface:volume ratio, smaller liposomes yielded a consistently higher R1 than larger liposomes. For equal voxel [Gd] less concentrated liposomes (0.3 M Gd) yielded higher R1/R2 ratio because of the higher extraliposomal water fraction (vl ). Gd exhibits a dualistic behavior: from hypointensity to hyperintensity to hypointensity, with decreasing [Gd]. Regarding compartmentalization, fewer membrane barriers means a higher R1 /R2 ratio. Gd liposomes exhibit a versatile contrast behavior, dependent on the compartmentalization state, liposomal size, intraliposomal [Gd] and liposome number. Both R1 and R2 effects contribute to this. The versatility allows one to tailor the optimal liposomal formulation to desired goals in cell labeling and tracking.

  12. Long range ordered magnetic and atomic structures of the quasicrystal approximant in the Tb-Au-Si system

    NASA Astrophysics Data System (ADS)

    Gebresenbut, Girma; Svante Andersson, Mikael; Beran, Přemysl; Manuel, Pascal; Nordblad, Per; Sahlberg, Martin; Pay Gomez, Cesar

    2014-08-01

    The atomic and magnetic structure of the 1/1 Tb(14)Au(70)Si(16) quasicrystal approximant has been solved by combining x-ray and neutron diffraction data. The atomic structure is classified as a Tsai-type 1/1 approximant with certain structural deviations from the prototype structures; there are additional atomic positions in the so-called cubic interstices as well as in the cluster centers. The magnetic property and neutron diffraction measurements indicate the magnetic structure to be ferrimagnetic-like below 9 K in contrast to the related Gd(14)Au(70)Si(16) structure that is reported to be purely ferromagnetic.

  13. Poly(acrylic acid) modified lanthanide-doped GdVO4 hollow spheres for up-conversion cell imaging, MRI and pH-dependent drug release

    NASA Astrophysics Data System (ADS)

    Kang, Xiaojiao; Yang, Dongmei; Dai, Yunlu; Shang, Mengmeng; Cheng, Ziyong; Zhang, Xiao; Lian, Hongzhou; Ma, Ping'an; Lin, Jun

    2012-12-01

    In this study, multifunctional poly(acrylic acid) modified lanthanide-doped GdVO4 nanocomposites [PAA@GdVO4: Ln3+ (Ln = Yb/Er, Yb/Ho, Yb/Tm)] were constructed by filling PAA hydrogel into GdVO4 hollow spheres via photoinduced polymerization. The up-conversion (UC) emission colors (green, red and blue) can be tuned by changing the codopant compositions in the matrices. The composites have potential applications as bio-probes for cell imaging. Meanwhile, the hybrid spheres can act as T1 contrast agents for magnetic resonance imaging (MRI) owing to the existence of Gd3+ ions on the surface of composites. Due to the nature of PAA, DOX-loaded PAA@GdVO4:Yb3+/Er3+ system exhibits pH-dependent drug releasing kinetics. A lower pH offers a faster drug release rate. Such character makes the loaded DOX easily released at cancer cells. The cell uptake process of drug-loaded composites was observed by using confocal laser scanning microscopy (CLSM). The results indicate the potential application of the multifunctional composites as theragnostics (effective bimodal imaging probes and pH-responsive drug carriers).

  14. Comparison of n-type Gd2O3 and Gd-doped HfO2

    NASA Astrophysics Data System (ADS)

    Losovyj, Ya B.; Wooten, David; Colon Santana, Juan; An, Joonhee Michael; Belashchenko, K. D.; Lozova, N.; Petrosky, J.; Sokolov, A.; Tang, Jinke; Wang, Wendong; Arulsamy, Navamoney; Dowben, P. A.

    2009-01-01

    Gd2O3 and Gd-doped HfO2 films were deposited on p-type silicon substrates in a reducing atmosphere. Gd 4f photoexcitation peaks at roughly 7 and 5 eV below the valence band maximum have been identified using the resonant photoemission of Gd2O3 and Gd-doped HfO2 films, respectively. In the case of Gd2O3, strong hybridization with the O 2p band is demonstrated, and there is evidence that the Gd 4f weighted band exhibits dispersion in the bulk band structure. The rectifying (diode-like) properties of Gd-doped HfO2-silicon and Gd2O3-silicon heterojunctions are demonstrated.

  15. Luminescence properties of phosphors based on Tb3Al5O12 (TbAG) terbium-aluminum garnet

    NASA Astrophysics Data System (ADS)

    Zorenko, Yu.; Gorbenko, V.; Voznyak, T.; Zorenko, T.; Kuklinski, B.; Turos-Matysyak, R.; Grinberg, M.

    2009-03-01

    The processes of excitation energy transfer in phosphors based on single-crystal Tb3Al5O12:Ce (TbAG:Ce) and Tb3Al5O12:Ce,Eu (TbAG:Ce,Eu) garnet films have been investigated. These films are considered to be promising materials for screens for X-ray images and luminescence converters of blue LED radiation. The conditions for excitation energy transfer from the matrix (Tb3+ cations) to Ce3+ and Eu3+ ions in TbAG:Ce and TbAG:Ce,Eu phosphors have been analyzed in detail. It is established that a cascade process of excitation energy transfer from Tb3+ ions to Ce3+ and Eu3+ ions and from Ce3+ ions to Eu3+ ions is implemented in TbAG:Ce,Eu via dipole-dipole interaction and through the Tb3+ cation sublattice.

  16. Pulsating White Dwarf Star GD99

    NASA Astrophysics Data System (ADS)

    Chynoweth, K. M.; Thompson, S.; Mullally, F.; Yeates, C.

    2004-12-01

    We present 15 hours of time-series photometry of the variable white dwarf star GD99. These data were obtained at the McDonald Observatory 2.1m Otto Struve Telescope in January 2003, using the Argos CCD photometer. We achieved a noise level as low as 0.07 %, as measured from the power spectrum of our first night. Our observations confirm that GD99 is a unique pulsating white dwarf whose modes show characteristics of both the hot and cold type of DA variable stars. Additionally, GD99 has a large number of modes, making it a good candidate for asteroseismological study. Our preliminary results indicate that this star merits further study to decipher its abundant set of unusual modes. With such a rich period structure, longer continuous data sets will be required to fully resolve the pulsation spectrum.

  17. Effect of Stacking Sequence on Surface Magnetism: Strained hcp Gd(0001) vs fcc Gd(111) Surface

    NASA Astrophysics Data System (ADS)

    Hong, S. C.; Freeman, A. J.

    1997-03-01

    Very recently, the distortion of the bulk bands of Gd was observed with angle resolved photoemission spectrocopy for Gd(0001) films grown on the corrugated Mo(112) surface(C. Waldfried, D.N. McIlroy, C.W. Hutchings, P.A. Dowben, private communication). To clarify the origin of this band distortion, first principles calculations have been done on hcp Gd(0001) and fcc Gd(111) with 2D lattice constants expanded by 20% using the highly precise full-potential linearized augmented plane wave (FLAPW) method(E. Wimmer, H. Krakauer, M. Weinert, and A.J. Freeman Phys. Rev. B24), 864 (1981).. The interlayer spacings were fully relaxed with atomic force and total energy calculations. We found that the strain does not distort the bulk bands significantly; for hcp Gd(0001), the spin magnetic moment(0.61 μ_B) of conduction electrons at the surface layer is enhanced by 13% compared to that (0.54 μ_B) of the bulk-like layer, but for the fcc Gd(111) the moment (0.65 μ_B) at the surface is reduced by 11% compared to that (0.72 μ_B) of the bulk-like layer. This unusal reduction of the magnetic moment at the fcc Gd(111) surface will be discused.

  18. New rare earth metal-rich indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu)—synthesis and crystal chemistry

    NASA Astrophysics Data System (ADS)

    Lukachuk, Mar'yana; Galadzhun, Yaroslav V.; Zaremba, Roman I.; Dzevenko, Mariya V.; Kalychak, Yaroslav M.; Zaremba, Vasyl I.; Rodewald, Ute Ch.; Pöttgen, Rainer

    2005-09-01

    The rare earth-nickel-indides RE14Ni 3In 3 ( RE=Sc, Y, Gd-Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing. The compounds were investigated on the basis of X-ray powder and single crystal data: Lu 14Co 2In 3 type, P4 2/ nmc, Z=4, a=888.1(1), c=2134.7(4), wR2=0.0653, 1381 F2 values, 63 variables for Sc 13.89Ni 3.66In 2.45; a=961.2(1), c=2316.2(5), wR2=0.0633, 1741 F2 values, 64 variables for Y 13.84Ni 3.19In 2.97; a=965.3(1), c=2330.5(5), wR2=0.0620, 1765 F2 values, 63 variables for Gd 14Ni 3.29In 2.71; a=956.8(1), c=2298.4(5), wR2=0.0829, 1707 F2 values, 64 variables for Tb 13.82Ni 3.36In 2.82; a=951.7(1), c=2289.0(5), wR2=0.0838, 1794 F2 values, 64 variables for Dy 13.60Ni 3.34In 3.06; a=948.53(7), c=2270.6(1), wR2=0.1137, 1191 F2 values, 64 variables for Ho 13.35Ni 3.17In 3.48; a=943.5(1), c=2269.1(5), wR2=0.0552, 1646 F2 values, 64 variables for Er 13.53Ni 3.14In 3.33; a=938.42(7), c=2250.8(1), wR2=0.1051, 1611 F2 values, 64 variables for Tm 13.47Ni 3.28In 3.25; a=937.3(1), c=2249.6(5), wR2=0.0692, 1604 F2 values, 64 variables for Tm 13.80Ni 3.49In 2.71; and a=933.4(1), c=2263.0(5), wR2=0.0709, 1603 F2 values, 64 variables for Lu 13.94Ni 3.07In 2.99. The RE14Ni 3In 3 indides show significant Ni/In mixing on the 4 c In1 site. Except the gadolinium compound, the RE14Ni 3In 3 intermetallics also reveal RE/In mixing on the 4 c RE1 site, leading to the refined compositions. Due to the high rare earth metal content, the seven crystallographically independent RE sites have between 9 and 10 nearest RE neighbors. The RE14Ni 3In 3 structures can be described as a complex intergrowth of rare earth-based polyhedra. Both nickel sites have a distorted trigonal-prismatic rare earth coordination. An interesting feature is the In2-In2 dumb-bell at an In2-In2 distance of 304 pm (for Gd 14Ni 3.29In 2.71). The crystal chemical peculiarities of the RE14Ni 3In 3 indides are briefly discussed.

  19. Recent tuberculosis diagnosis toward the end TB strategy.

    PubMed

    Cheon, Seon Ah; Cho, Hyun Hee; Kim, Jeonghyo; Lee, Jaebeom; Kim, Hwa-Jung; Park, Tae Jung

    2016-04-01

    Tuberculosis (TB) is an infectious bacterial disease caused by Mycobacterium tuberculosis. Despite global TB eradication efforts, it is still a global public health concern, especially in low- and middle-income countries. Most of the active TB infections are curable with early diagnosis and appropriate treatment, but drug-resistant TB is difficult and expensive to treat in immunocompetent as well as immunocompromised individuals. Thus, rapid, economic, and accurate point-of care tools for TB diagnosis are required urgently. This review describes the history of M. tuberculosis detection methods up to date and the recent advances using nanotechnology for point-of-care testing of TB diagnosis.

  20. Reinvestigation of the Cd–Gd phase diagram

    PubMed Central

    Reichmann, Thomas L.; Ipser, Herbert

    2014-01-01

    The complete Cd–Gd equilibrium phase diagram was investigated by a combination of powder-XRD, SEM and DTA. All previously reported phases, i.e., CdGd, Cd2Gd, Cd3Gd, Cd45Gd11, Cd58Gd13, and Cd6Gd, could be confirmed. In addition, a new intermetallic compound with a stoichiometric composition corresponding to “Cd8Gd” was found to exist. It was obtained that “Cd8Gd” decomposes peritectically at 465 °C. Homogeneity ranges of all intermetallic compounds were determined at distinct temperatures. In addition, the maximum solubilities of Cd in the low- and high-temperature modifications of Gd were determined precisely as 4.6 and 22.6 at.%, respectively. All invariant reaction temperatures (with the exception of the formation of Cd58Gd13) as well as liquidus temperatures were determined, most probably, Cd58Gd13 is formed in a peritectoid reaction from Cd45Gd11 and Cd6Gd at a temperature below 700 °C. PMID:25544803

  1. Resonant photoemission in f-electron systems: Pu and Gd

    NASA Astrophysics Data System (ADS)

    Tobin, J. G.; Chung, B. W.; Schulze, R. K.; Terry, J.; Farr, J. D.; Shuh, D. K.; Heinzelman, K.; Rotenberg, E.; Waddill, G. D.; van der Laan, G.

    2003-10-01

    Resonant photoemission in the Pu 5f and Pu 6p states is compared to that in the Gd 4f and Gd 5p states. Spectral simulations, based upon an atomic model with angular momentum coupling, are compared to the Gd and Pu results. Additional spectroscopic measurements of Pu, including core level photoemission and x-ray absorption, are also presented.

  2. Resonant Photoemission in f Electron Systems: Pu& Gd

    SciTech Connect

    Tobin, J G; Chung, B W; Schulze, R K; Terry, J; Farr, J D; Shuh, D K; Heinzelman, K; Rotenberg, E; Waddill, G D; van der Laan, G

    2003-03-07

    Resonant photoemission in the Pu5f and Pu6p states is compared to that in the Gd4f and Gd5p states. Spectral simulations, based upon and atomic model with angular momentum coupling, are compared to the Gd and Pu results. Additional spectroscopic measurements of Pu, including core level photoemission and x-ray absorption are also presented.

  3. Resonant photoemission in f electron systems: Pu and Gd

    SciTech Connect

    Tobin, J.G.; Chung, B.W.; Waddill, G.D.; Schulze, R.K.; Terry,J.; Farr, J.D.; Zocco, T.; Shuh, D.K.; Heinzelman, K.; Rotenberg, E.; Vander Laan, G.

    2003-10-14

    Resonant photoemission in the Pu 5f and Pu 6p states is compared to that in the Gd 4f and Gd 5p states. Spectral simulations, based upon an atomic model with angular momentum coupling, are compared to the Gd and Pu results. Additional spectroscopic measurements of Pu, including core level photoemission and x-ray absorption, are also presented.

  4. Cell Death and Autophagy in TB

    PubMed Central

    Moraco, Andrew H.; Kornfeld, Hardy

    2014-01-01

    Mycobacterium tuberculosis has succeeded in infecting one third of the human race though inhibition or evasion of innate and adaptive immunity. The pathogen is a facultative intracellular parasite that uses the niche provided by mononuclear phagocytes for its advantage. Complex interactions determine whether the bacillus will or will not be delivered to acidified lysosomes, whether the host phagocyte will survive infection or die, and whether the timing and mode of cell death works to the advantage of the host or the pathogen. Here we discuss cell death and autophagy in TB. These fundamental processes of cell biology feature in all aspects of TB pathogenesis and may be exploited to the treatment or prevention of TB disease. PMID:25453227

  5. Comparison of Gd-Bz-TTDA, Gd-EOB-DTPA, and Gd-BOPTA for dynamic MR imaging of the liver in rat models.

    PubMed

    Jaw, Twei-Shiun; Chen, Shih-Hsien; Wang, Yun-Ming; Hsu, Jui-Sheng; Kuo, Yu-Ting; Chiu, Yen-Yu; Tsai, Kun-Bow; Hsieh, Tsyh-Jyi; Liu, Gin-Chung

    2012-03-01

    To evaluate the competitive potential of a new lipophilic paramagnetic complex, Gd-Bz-TTDA [4-benzyl-3,6,10-tri (carboxymethyl)-3,6,10-triazado-decanedioic acid] compared with two other commercially available MR hepatobiliary contrast agents, gadobenate dimeglumine (Gd-BOPTA) and gadoxetic acid (Gd-EOB-DTPA), dynamic MR imaging studies were performed on normal and hepatocellular carcinoma (HCC) rat models using a 1.5-Tesla MR scanner. The results indicate that normal rats that were injected with 0.1 mmol/kg Gd-Bz-TTDA showed significantly more intense and persistent liver enhancement than those that were injected with the same dose of Gd-EOB-DTPA or Gd-BOPTA. All of these agents showed similar enhancement patterns in the implanted HCC. The liver-lesion contrast-to-noise ratios were higher and more persistent in rats that were injected with Gd-Bz-TTDA. These results indicate that Gd-Bz-TTDA is comparable with the commercially available hepatobiliary agents, Gd-EOB-DTPA and Gd-BOPTA, and can result in more intense and prolonged liver enhancement while still providing better liver-lesion discrimination. These results warrant further large-scale studies.

  6. Yb-doped Gd2O2CO3: Structure, microstructure, thermal and magnetic behaviour

    NASA Astrophysics Data System (ADS)

    Artini, Cristina; Locardi, Federico; Pani, Marcella; Nelli, Ilaria; Caglieris, Federico; Masini, Roberto; Plaisier, Jasper Rikkert; Costa, Giorgio Andrea

    2017-04-01

    persistent luminescence, with the emission taking place at 970 nm in correspondence of the Yb3+2F7/2-2F5/2 transition, detectable up to 144 h after the end of irradiation. The origin of persistent luminescence is still substantially unclear, even if it is well known that excitation energy has to be stored in an intrinsic or extrinsic trap to be then slowly released. Extrinsic traps can derive from the presence of an aliovalent ion within the matrix; this should be the case of Yb-doped Gd2O2CO3, due to the valence instability of Yb, that is believed to be induced by irradiation [19,20]. In this respect, the precise knowledge of the dioxycarbonate crystal structure and its compositional extent, as well as the determination of the Yb location and its surroundings within the crystal structure, are of great importance. Also a microstructural approach can provide useful hints about the environment of the doping ion, even if it can not replace an investigation at the local scale. The synthetic route used for the preparation of hexagonal RE dioxycarbonates plays an important role in the obtainment of monophasic samples. The formation of the product via transformation of form I or Ia is documented for light lanthanides up to Sm [1], while thermal decomposition of Gd oxalate at 600 °C in static CO2 was performed to obtain hexagonal Gd2O2CO3[21]. The latter method is useful also for the synthesis of some mixed oxycarbonates, such as the ones containing Gd/Nd [9], but not Gd/Ce [8]. Carbonatation of RE2O3 is also reported as successful for RE≡La [1], Pr [1], Gd [21] and Nd [22]. The duration of the synthetic process is significantly shortened by adding the eutectic mixture Li2CO3-Na2CO3-K2CO3 to oxides, and by heating the whole mixture [7]. Nanostructured Yb- and Er-doped Gd2O2CO3 were also obtained, by coating with SiO2 the corresponding RE(OH)CO3·H2O nanoparticles [23]. In this work we present a structural, microstructural, thermal and magnetic study of a series of Yb-doped Gd2O2

  7. Growth and luminescent properties of Lu 2SiO 5:Ce and (Lu 1- xGd x) 2SiO 5:Ce single crystalline films

    NASA Astrophysics Data System (ADS)

    Zorenko, Yu.; Gorbenko, V.; Savchyn, V.; Voznyak, T.; Grinyov, B.; Sidletskiy, O.; Kurtsev, D.; Fedorov, A.; Baumer, V.; Nikl, M.; Mares, J. A.; Beitlerova, A.; Prusa, P.; Kucera, M.

    2011-12-01

    Single crystalline films (SCF) of Lu 2SiO 5:Ce (LSO:Ce), (Lu 1- xGd x) 2SiO 5:Ce (LGSO:Ce) and LGSO:Ce,Tb orthosilicates with thickness of 2.5-21 μm were crystallized by liquid phase epitaxy method onto undoped LSO substrates from melt-solution based on PbO-B 2O 3 flux. The concentration of Gd was varied in the range of x=0.2-0.7 formula units (f.u.). In the case of LGSO:Ce SCF growth we do not use any additional doping for reducing the misfit between the SCF and substrate lattices. The luminescence and scintillation properties of LSO:Ce, LGSO:Ce and LGSO:Ce,Tb SCFs were mutually compared and confronted with the performance of reference LSO:Ce and LYSO:Ce crystals. With increasing Gd content the luminescence spectrum of LGSO:Ce SCF is gradually red-shifted with respect to that of LSO:Ce SCF. The LY of (Lu 1- xGd x)SO:Ce SCF becomes lower in comparison with that for LSO:Ce SC at increasing Gd content in the range of x=0.2-0.7 f.u. The peculiarities of luminescence properties of LSO:Ce and LGSO:Ce SCFs in comparison with crystal analogs are explained by the different distribution of Ce 3+ over Lu1 and Lu2 positions of LSO host and by the influence of Pb 2+ contamination coming from the flux used for the film growth.

  8. A comparative study of magnetic behaviors in TbNi{sub 2}, TbMn{sub 2} and TbNi{sub 2}Mn

    SciTech Connect

    Wang, J. L.; Md Din, M. F.; Hong, F.; Cheng, Z. X.; Dou, S. X.; Kennedy, S. J.; Studer, A. J.; Campbell, S. J.; Wu, G. H.

    2014-05-07

    All TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn compounds exhibit the cubic Laves phase with AB{sub 2}-type structure in spite of the fact that the ratio of the Tb to transition-metal components in TbNi{sub 2}Mn is 1:3. Rietveld refinement indicates that in TbNi{sub 2}Mn the Mn atoms are distributed on both the A (8a) and B (16d) sites. The values of the lattice constants were measured to be a = 14.348 Å (space group F-43 m), 7.618 Å, and 7.158 Å (space group Fd-3 m) for TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn, respectively. The magnetic transition temperatures T{sub C} were found to be T{sub C} = 38 K and T{sub C} = 148 K for TbNi{sub 2} and TbNi{sub 2}Mn, respectively, while two magnetic phase transitions are detected for TbMn{sub 2} at T{sub 1} = 20 K and T{sub 2} = 49 K. Clear magnetic history effects in a low magnetic field are observed in TbMn{sub 2} and TbNi{sub 2}Mn. The magnetic entropy changes have been obtained.

  9. TAIMA (Stop) TB: The Impact of a Multifaceted TB Awareness and Door-to-Door Campaign in Residential Areas of High Risk for TB in Iqaluit, Nunavut

    PubMed Central

    Alvarez, Gonzalo G.; VanDyk, Deborah D.; Aaron, Shawn D.; Cameron, D. William; Davies, Naomi; Stephen, Natasha; Mallick, Ranjeeta; Momoli, Franco; Moreau, Katherine; Obed, Natan; Baikie, Maureen; Osborne, Geraldine

    2014-01-01

    Background The incidence rate of active tuberculosis (TB) disease in the Canadian Territory of Nunavut has shown a rising trend over the past 10 years. In 2010 it was 60 times greater than the national incidence rate. The objective of the Taima (translates to “stop” in Inuktitut) TB study was to implement and evaluate a public health campaign to enhance existing TB prevention efforts in Nunavut. Methods A TB awareness campaign followed by a door-to-door screening campaign was carried out in Iqaluit, Nunavut. The aim of the campaign was to raise awareness about TB, and to provide in-home screening and treatment for people living in residential areas at high risk for TB. Screening was based on geographic location rather than on individual risk factors. Results During the general awareness campaign an increase in the number of people who requested TB testing at the local public health clinic was observed. However, this increase was not sustained following cessation of the awareness campaign. Targeted TB screening in high risk residential areas in Iqaluit resulted in 224 individuals having TSTs read, and detection of 42 previously unidentified cases of latent TB, (overall yield of 18.8% or number needed to screen = 5.3). These cases of latent TB infection (LTBI) were extra cases that had not been picked up by traditional screening practices (34% relative increase within the community). This resulted in a 33% relative increase in the completion of LTBI treatment within the community. The program directly and indirectly identified 5/17 new cases of active TB disease in Iqaluit during the study period (29.5% of all incident cases). Conclusions While contact tracing investigations remain a cornerstone of TB prevention, additional awareness, screening, and treatment programs like Taima TB may contribute to the successful control of TB in Aboriginal communities. PMID:25033320

  10. Electron probe microanalysis in the ternary Gd B C system

    NASA Astrophysics Data System (ADS)

    Ruiz, Domingo; Garland, Maria Teresa; Saillard, Jean-Yves; Halet, Jean-François; Bohn, Marcel; Bauer, Josef

    2002-09-01

    EPMA exploration of the Gd-B-C system in the region "Gd-GdB 2-GdBC" and in the neighborhood of the recently described Gd 4B 3C 4 compound led to the identification of 9 new ternary phases, which allows to clear up the phase diagram of this ternary system. A structural description of the bonding between the non-metal atoms in most of the identified compounds is proposed, on the basis of simple electron counting rules and using the planar repeat units or the finite linear anions which have been shown to exist in the structurally characterized rare-earth borocarbide compounds.

  11. Novel fluorite structured superparamagnetic RbGdF₄ nanocrystals as versatile upconversion host.

    PubMed

    Ahmad, Shahzad; Nagarajan, Rajamani; Raj, Packiya; Prakash, G Vijaya

    2014-10-06

    Fluorite structured nanocrystals of RbGdF4 in cubic symmetry have successfully been synthesized by employing a simple, one-step, and template-free wet chemical method at room temperature. Considering the structural model of cubic KLaF4 in the Fm̅3m space group, the observed powder X-ray diffraction (PXRD) pattern was fitted by the Le Bail procedure with the cubic lattice constant of a = 5.8244 (1) Å. Both high-resolution transmission electron microscopic (HR-TEM) and dynamic light scattering (DLS) measurements revealed the monodispersity of the nanocrystals with their size in the range of 2-18 nm. Upon excitation at 980 nm, Yb(3+), (Er(3+)/Ho(3+)/Tm(3+)) codoped RbGdF4 nanocrystals showed multicolor upconversion including red, yellow, blue, and the combination of basic color (near-white) emissions. Also, near-white upconversion emission from Yb(3+), Ho(3+), Tm(3+) triply doped cubic RbGdF4 nanocrystals was observed at varying laser power densities. RbGdF4 nanocrystals exhibited superparamagnetic behavior with a molar magnetic susceptibility of 2.61 × 10(-2) emu·Oe(-1)·mol(-1) at room temperature, while at low temperature (5 K) a saturation magnetization value of 90.41 emu·g(-1) at an applied field of at 10 kOe was observed. Non-interaction of the localized magnetic moment of Gd(3+) ions in the host matrix has been reasoned out for the observed superparamagnetic behavior. From the Langevin fit of the magnetic data, the average particle diameter obtained was approximately 2.2 nm, matching well with the values from other measurements. RbGdF4 nanocrystals exhibited a large ionic longitudinal relaxivity (r1 = 2.30 s(-1)·mM(-1)), suggesting their potential applicability as a promising agent for T1 contrast magnetic resonance imaging (MRI) in addition to the applications arising from the coupling of optical and magnetic functions such as multiplexing biodetection, bioimaging (optical and MRI), and other optical technologies.

  12. Tuberculosis: Learn the Signs and Symptoms of TB Disease

    MedlinePlus

    ... What's this? Submit Button Past Emails CDC Features Tuberculosis (TB) Disease: Symptoms & Risk Factors Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir Tuberculosis (TB) is a disease caused by bacteria that ...

  13. DNA vaccine expressing the mimotope of GD2 ganglioside induces protective GD2 cross-reactive antibody responses.

    PubMed

    Bolesta, Elizabeth; Kowalczyk, Aleksandra; Wierzbicki, Andrzej; Rotkiewicz, Piotr; Bambach, Barbara; Tsao, Chun-Yen; Horwacik, Irena; Kolinski, Andrzej; Rokita, Hanna; Brecher, Martin; Wang, Xinhui; Ferrone, Soldano; Kozbor, Danuta

    2005-04-15

    The GD2 ganglioside expressed on neuroectodermally derived tumors, including neuroblastoma and melanoma, is weakly immunogenic in tumor-bearing patients and induces predominantly immunoglobulin (Ig)-M antibody responses in the immunized host. Here, we investigated whether interconversion of GD2 into a peptide mimetic form would induce GD2 cross-reactive IgG antibody responses in mice. Screening of the X(15) phage display peptide library with the anti-GD2 monoclonal antibody (mAb) 14G2a led to isolation of mimetic peptide 47, which inhibited the binding of 14G2a antibody to GD2-positive tumor cells. The peptide was also recognized by GD2-specific serum antibodies from a patient with neuroblastoma, suggesting that it bears an internal image of GD2 ganglioside expressed on the tumor cells. The molecular basis for antigenicity of the GD2 mimetic peptide, established by molecular modeling and mutagenesis studies, led to the generation of a 47-LDA mutant with an increased mimicry to GD2. Immunization of mice with peptide 47-LDA-encoded plasmid DNA elicited GD2 cross-reactive IgG antibody responses, which were increased on subsequent boost with GD2 ganglioside. The vaccine-induced antibodies recognized GD2-positive tumor cells, mediated complement-dependent cytotoxicity, and exhibited protection against s.c. human GD2-positive melanoma growth in the severe combined immunodeficient mouse xenograft model. The results from our studies provide insights into approaches for boosting GD2 cross-reactive IgG antibody responses by minigene vaccination with a protective epitope of GD2 ganglioside.

  14. Self-assembly synthesis, structural features, and photophysical properties of dilanthanide complexes derived from a novel amide type ligand: energy transfer from Tb(III) to Eu(III) in a heterodinuclear derivative.

    PubMed

    Gao, Cunji; Kirillov, Alexander M; Dou, Wei; Tang, Xiaoliang; Liu, Liangliang; Yan, Xuhuan; Xie, Yujie; Zang, Peixian; Liu, Weisheng; Tang, Yu

    2014-01-21

    A novel amide type ligand benzyl-N,N-bis[(2'-furfurylaminoformyl)phenoxyl)ethyl]-amine (L) has been designed and applied for the self-assembly generation of homodinuclear lanthanide coordination compounds [Ln2(μ2-L)2(NO3)6(EtOH)2] [Ln = Eu (1), Tb (2), and Gd (3)] and a heterodinuclear derivative [EuTb(μ2-L)2(NO3)6(EtOH)2] (4). All the complexes have been characterized by the X-ray single-crystal diffraction analyses. They are isostructural, crystallize in a monoclinic space group P21/c, and form [2 + 2] rectangular macrocycle structures. Compound 4 is the first example of a [2 + 2] rectangular macrocycle heterodinuclear EuTb complex assembled from an amide type ligand. In 4, the discrete 0D dimeric [EuTb(μ2-L)2(NO3)6(EtOH)2] units are extended, via the multiple N-H···O hydrogen bonds, into a 2D supramolecular network that has been topologically classified as a uninodal 4-connected underlying net with the sql [Shubnikov tetragonal plane net] topology. The triplet state ((3)ππ*) of L studied by the Gd(III) complex 3 demonstrated that the ligand beautifully populates Tb(III) emission (Φ = 52%), whereas the corresponding Eu(III) derivative 1 shows weak luminescence efficiency (Φ = 0.7%) because the triplet state of L has a poor match with (5)D1 energy level of Eu(III). Furthermore, the photoluminescent properties of heterodinuclear complex 4 have been compared with those of the analogous homodinuclear compounds. The quantum yield and lifetime measurements prove that energy transfer from Tb(III) to Eu(III) is being achieved, namely, that the Tb(III) center is also acting to sensitize the Eu(III) and enhancing Eu(III) emission in 4.

  15. [Tuberculosis Annual Report 2009--Series 6. Condition of TB (1)].

    PubMed

    2011-10-01

    The condition of tuberculosis (TB) at the time at which an individual is diagnosed with TB influences the patient's prognosis. This paper focuses on the condition of TB at the time of the diagnosis based on bacteriological status and X-ray findings. The proportion of bacteriologically confirmed cases among newly notified pulmonary TB patients increased greatly from 25.7% in 1979 to 82.7% in 2009. During this period, the proportion of far-advanced cavitary cases among pulmonary TB patients was around 2% and remained stable. This may mean that the diagnosis had come to be performed bacteriologically rather than radiologically. The proportion of bacteriologically confirmed cases among newly notified pulmonary TB patients in 2009 was studied by sex and 5-year age group. The proportion of bacteriologically confirmed cases increased with age in both male and female TB patients. In male TB patients, the proportion of cavitary cases increased in patients aged up to the end of the 50s and then decreased with age. This tendency was not observed in females. Although the proportion of cavitary cases among elderly TB patients was lower than among youths, the proportion having extensive lesions was greater than that among youths. The proportion of sputum-smear-positive cases with cavities among pulmonary TB patients aged 30-59 years was 32.9 % in male TB patients and 17.1% in female TB patients. According to occupation, this proportion was highest in "temporary workers" (52.6%) for male TB cases and "jobless/ others" (24.9%) for female TB cases, and lowest among "medical workers" in both sexes: 8.3% of male TB cases and 7.4% of female TB cases.

  16. Updating and curating metabolic pathways of TB.

    PubMed

    Slayden, Richard A; Jackson, Mary; Zucker, Jeremy; Ramirez, Melissa V; Dawson, Clinton C; Crew, Rebecca; Sampson, Nicole S; Thomas, Suzanne T; Jamshidi, Neema; Sisk, Peter; Caspi, Ron; Crick, Dean C; McNeil, Michael R; Pavelka, Martin S; Niederweis, Michael; Siroy, Axel; Dona, Valentina; McFadden, Johnjoe; Boshoff, Helena; Lew, Jocelyne M

    2013-01-01

    The sequencing of complete genomes has accelerated biomedical research by providing information about the overall coding capacity of bacterial chromosomes. The original TB annotation resulted in putative functional assignment of ∼60% of the genes to specific metabolic functions, however, the other 40% of the encoded ORFs where annotated as conserved hypothetical proteins, hypothetical proteins or encoding proteins of unknown function. The TB research community is now at the beginning of the next phases of post-genomics; namely reannotation and functional characterization by targeted experimentation. Arguably, this is the most significant time for basic microbiology in recent history. To foster basic TB research, the Tuberculosis Community Annotation Project (TBCAP) jamboree exercise began the reannotation effort by providing additional information for previous annotations, and refining and substantiating the functional assignment of ORFs and genes within metabolic pathways. The overall goal of the TBCAP 2012 exercise was to gather and compile various data types and use this information with oversight from the scientific community to provide additional information to support the functional annotations of encoding genes. Another objective of this effort was to standardize the publicly accessible Mycobacterium tuberculosis reference sequence and its annotation. The greatest benefit of functional annotation information of genome sequence is that it fuels TB research for drug discovery, diagnostics, vaccine development and epidemiology.

  17. [Optical parameters of Er3+ in Er3+ : YVO4].

    PubMed

    Chen, Ying; Chen, Xiao-bo; Chen, Luan; Liu, Da-he; Song, Zeng-fu; Li, Yong-liang; Li, Song; Zeng, Yong-zhi; Wu, Zheng-long; Zhang, Chun-lin; Wang, Ya-fei; Guo, Jing-hua

    2010-07-01

    In the present paper the authors firstly measured the absorption spectra of Er3+ in the sample Er3+ : YVO4 (0.5%), then calculated the intensity parameters are calculated by using the Judd-Ofelt theory. After that the authors dealed with some predicted spectroscopic parameters, such as the oscillator strength, spontaneous radiative transition rate, branching ratio and integrated emission cross section. And Er : YVO4 crystal application value has been analyzed with the optical parameters. Especially there are large oscillator strengths and large integrated emission cross sections in the transitions of 4 I1/2 --> 4 I15/2, 2 H11/2 --> 4I15/2, 4S3/2 --> 4 I15/2, and 4F9/2 --> 4 I15/2. So, they are more worth of attention. Moreover, by comparing the Er-doped yttrium vanadate crystal and other Er-doped crystal optical properties, the authors can see the advantages of YVO4 as laser crystal. Finally, the authors discussed the splitting of the energy levels of Er3+ in the crystal YVO4 based on the group theory.

  18. Relevance of latent TB infection in areas of high TB prevalence.

    PubMed

    Sharma, Surendra K; Mohanan, Sandeep; Sharma, Abhishek

    2012-09-01

    About one-third of the world population has latent TB infection (LTBI), the majority of which is distributed in 22 high-burden countries. Early diagnosis and treatment of active TB remains the top priority in resource-poor countries with high TB prevalence. Notwithstanding, because LTBI contributes significantly to the pool of active TB cases later on, its diagnosis and treatment is essential, especially in high-risk groups. The lack of a gold standard and several limitations of currently available tools, namely the tuberculin skin test and interferon-γ release assays, are major constraints for LTBI diagnosis. In areas with high TB prevalence, interferon-γ release assays have not shown superiority over the conventional tuberculin skin test and are yet to be systematically studied. Decisions regarding LTBI treatment with isoniazid preventive therapy should be made, keeping in mind the high prevalence of isoniazid resistance in these settings. Although efforts to shorten the LTBI treatment duration are encouraging, most trials have focused on adherence and toxicity. Future trials on short-duration regimens in high-burden settings should address drug efficacy issues as well. LTBI management, therefore, should comprise a targeted screening approach and individualization of LTBI treatment protocols. In addition, efforts should focus on airborne infection control measures in high-burden countries. A high prevalence of drug-resistant TB, the HIV epidemic, and delays in the diagnosis of active TB cases are other major concerns in areas of high TB prevalence. There is ample space for further research in these countries, whose outcomes may strengthen future national guidelines.

  19. Timing of antiretroviral therapy and TB treatment outcomes in patients with TB-HIV in Myanmar

    PubMed Central

    Shewade, H. D.; Kyaw, N. T. T.; Oo, M. M.; Aung, T. K.; Aung, S. T.; Oo, H. N.; Win, T.; Harries, A. D.

    2016-01-01

    Setting: Integrated HIV Care programme, Mandalay, Myanmar. Objectives: To determine time to starting antiretroviral treatment (ART) in relation to anti-tuberculosis treatment (ATT) and its association with TB treatment outcomes in patients co-infected with tuberculosis (TB) and the human immunodeficiency virus (HIV) enrolled from 2011 to 2014. Design: Retrospective cohort study. Results: Of 1708 TB-HIV patients, 1565 (92%) started ATT first and 143 (8%) started ART first. Treatment outcomes were missing for 226 patients and were thus not included. In those starting ATT first, the median time to starting ART was 8.6 weeks. ART was initiated after 8 weeks in 830 (53%) patients. Unsuccessful outcome was found in 7%, with anaemia being an independent predictor. In patients starting ART first, the median time to starting ATT was 21.6 weeks. ATT was initiated within 3 months in 56 (39%) patients. Unsuccessful outcome was found in 12%, and in 20% of those starting ATT within 3 months. Patients with CD4 count <100/mm3 had a four times higher risk of an unsuccessful outcome. Conclusions: Timing of ART in relation to ATT was not an independent risk factor for unsuccessful outcome. Extensive screening for TB with rapid and sensitive diagnostic tests in HIV-infected persons and close monitoring of anaemia and immunosuppression are recommended to further improve TB treatment outcomes among patients with TB-HIV. PMID:27358804

  20. Donor-derived tuberculosis (TB): isoniazid-resistant TB transmitted from a lung transplant donor with inadequately treated latent infection.

    PubMed

    Jensen, T O; Darley, D R; Goeman, E E; Shaw, K; Marriott, D J; Glanville, A R

    2016-10-01

    Donor-derived tuberculosis (TB) is an increasingly recognized complication of solid organ transplantation. We report a case of isoniazid-resistant pulmonary TB in a lung transplant recipient. The patient acquired the infection from the lung donor who was previously empirically treated with isoniazid for latent TB. The case highlights the caveat that, while adequate treatment of latent TB with isoniazid is presumed, meticulous screening of donors is required.

  1. Inverse effect of morphotropic phase boundary on the magnetostriction of ferromagnetic Tb1-xGdxCo2

    NASA Astrophysics Data System (ADS)

    Zhou, Chao; Ren, Shuai; Bao, Huixin; Yang, Sen; Yao, Yonggang; Ji, Yuanchao; Ren, Xiaobing; Matsushita, Yoshitaka; Katsuya, Yoshio; Tanaka, Masahiko; Kobayashi, Keisuke

    2014-03-01

    The morphotropic phase boundary (MPB) has been utilized extensively in ferroelectrics and recently has attracted interest in ferromagnets [S. Yang, H. Bao, C. Zhou, Y. Wang, X. Ren, Y. Matsushita, Y. Katsuya, M. Tanaka, K. Kobayashi, X. Song, and J. Gao, Phys. Rev. Lett. 104, 197201 (2010), 10.1103/PhysRevLett.104.197201; R. Bergstrom, M. Wuttig, J. Cullen, P. Zavalij, R. Briber, C. Dennis, V. O. Garlea, and M. Laver, Phys. Rev. Lett. 111, 017203 (2013), 10.1103/PhysRevLett.111.017203] for obtaining enhanced large field-induced strain. Here we report that the MPB can also lead to weakening (the inverse effect as compared to the known MPB materials) of field-induced strain, as exhibited in the Tb1-xGdxCo2 system. With synchrotron x-ray diffractometry, the structure symmetry of TbCo2-rich compositions is detected to be rhombohedral below TC and that of GdCo2-rich compositions is tetragonal. The MPB composition Tb0.1Gd0.9Co2, corresponding to the two phases (rhombohedral and tetragonal) of coexistence, shows the exotic minimum (near zero) magnetostriction as well as the largest magnetic susceptibility among all samples. Further analysis suggests that whether MPB can enhance or weaken magnetostriction is determined by the degree of magnetic ordering of two end members that form ferromagnetic MPBs, which was not considered previously. Our work not only reveals a new type of ferromagnetic MPB, but also provides a new recipe for designing functional high-susceptibility and low-strain magnetic materials.

  2. A world of cities and the end of TB.

    PubMed

    Prasad, Amit; Ross, Alex; Rosenberg, Paul; Dye, Christopher

    2016-03-01

    The WHO's End TB Strategy aims to reduce TB deaths by 95% and incidence by 90% between 2015 and 2035. As the world rapidly urbanizes, more people could have access to better infrastructure and services to help combat poverty and infectious diseases, including TB. And yet large numbers of people now live in overcrowded slums, with poor access to urban health services, amplifying the burden of TB. An alignment of the Sustainable Development Goals (SDGs) for health and for urban development provides an opportunity to accelerate the overall decline in infection and disease, and to create cities free of TB.

  3. A world of cities and the end of TB

    PubMed Central

    Prasad, Amit; Ross, Alex; Rosenberg, Paul; Dye, Christopher

    2016-01-01

    The WHO's End TB Strategy aims to reduce TB deaths by 95% and incidence by 90% between 2015 and 2035. As the world rapidly urbanizes, more people could have access to better infrastructure and services to help combat poverty and infectious diseases, including TB. And yet large numbers of people now live in overcrowded slums, with poor access to urban health services, amplifying the burden of TB. An alignment of the Sustainable Development Goals (SDGs) for health and for urban development provides an opportunity to accelerate the overall decline in infection and disease, and to create cities free of TB. PMID:26884491

  4. Pyrido[1,2-a]benzimidazole-based agents active against tuberculosis (TB), multidrug-resistant (MDR) TB and extensively drug-resistant (XDR) TB.

    PubMed

    Pieroni, Marco; Tipparaju, Suresh K; Lun, Shichun; Song, Yang; Sturm, A Willem; Bishai, William R; Kozikowski, Alan P

    2011-02-07

    The struggle against tuberculosis (TB) is still far from over. TB, caused by Mycobacterium tuberculosis, is one of the deadliest infections worldwide. Co-infection with human immunodeficiency virus (HIV) and the emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) strains have further increased the burden for this disease. Herein, we report the discovery of 2-(4-chlorobenzyl)-3-methyl-1-oxo-1H,5H-pyrido[1,2-a]benzimidazole-4-carbonitrile as an effective antitubercular agent and the structural modifications of this molecule that have led to analogues with improved potency and lower toxicity. A number of these derivatives were also active at sub-micromolar concentrations against resistant TB strains and devoid of apparent toxicity to Vero cells, thereby underscoring their value as novel scaffolds for the development of new anti-TB drugs.

  5. TIME Impact - a new user-friendly tuberculosis (TB) model to inform TB policy decisions.

    PubMed

    Houben, R M G J; Lalli, M; Sumner, T; Hamilton, M; Pedrazzoli, D; Bonsu, F; Hippner, P; Pillay, Y; Kimerling, M; Ahmedov, S; Pretorius, C; White, R G

    2016-03-24

    Tuberculosis (TB) is the leading cause of death from infectious disease worldwide, predominantly affecting low- and middle-income countries (LMICs), where resources are limited. As such, countries need to be able to choose the most efficient interventions for their respective setting. Mathematical models can be valuable tools to inform rational policy decisions and improve resource allocation, but are often unavailable or inaccessible for LMICs, particularly in TB. We developed TIME Impact, a user-friendly TB model that enables local capacity building and strengthens country-specific policy discussions to inform support funding applications at the (sub-)national level (e.g. Ministry of Finance) or to international donors (e.g. the Global Fund to Fight AIDS, Tuberculosis and Malaria).TIME Impact is an epidemiological transmission model nested in TIME, a set of TB modelling tools available for free download within the widely-used Spectrum software. The TIME Impact model reflects key aspects of the natural history of TB, with additional structure for HIV/ART, drug resistance, treatment history and age. TIME Impact enables national TB programmes (NTPs) and other TB policymakers to better understand their own TB epidemic, plan their response, apply for funding and evaluate the implementation of the response.The explicit aim of TIME Impact's user-friendly interface is to enable training of local and international TB experts towards independent use. During application of TIME Impact, close involvement of the NTPs and other local partners also builds critical understanding of the modelling methods, assumptions and limitations inherent to modelling. This is essential to generate broad country-level ownership of the modelling data inputs and results. In turn, it stimulates discussions and a review of the current evidence and assumptions, strengthening the decision-making process in general.TIME Impact has been effectively applied in a variety of settings. In South Africa, it

  6. GD SDR Automatic Gain Control Characterization Testing

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer M.; Briones, Janette C.

    2013-01-01

    The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) will provide experimenters an opportunity to develop and demonstrate experimental waveforms in space. The GD SDR platform and initial waveform were characterized on the ground before launch and the data will be compared to the data that will be collected during on-orbit operations. A desired function of the SDR is to estimate the received signal to noise ratio (SNR), which would enable experimenters to better determine on-orbit link conditions. The GD SDR does not have an SNR estimator, but it does have an analog and a digital automatic gain control (AGC). The AGCs can be used to estimate the SDR input power which can be converted into a SNR. Tests were conducted to characterize the AGC response to changes in SDR input power and temperature. This purpose of this paper is to describe the tests that were conducted, discuss the results showi ng how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

  7. GD SDR Automatic Gain Control Characterization Testing

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer M.; Briones, Janette C.

    2013-01-01

    The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) will provide experimenters an opportunity to develop and demonstrate experimental waveforms in space. The GD SDR platform and initial waveform were characterized on the ground before launch and the data will be compared to the data that will be collected during on-orbit operations. A desired function of the SDR is to estimate the received signal to noise ratio (SNR), which would enable experimenters to better determine on-orbit link conditions. The GD SDR does not have an SNR estimator, but it does have an analog and a digital automatic gain control (AGC). The AGCs can be used to estimate the SDR input power which can be converted into a SNR. Tests were conducted to characterize the AGC response to changes in SDR input power and temperature. This purpose of this paper is to describe the tests that were conducted, discuss the results showing how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

  8. Uniform hollow Lu2O3:Ln (Ln = Eu3+, Tb3+) spheres: facile synthesis and luminescent properties.

    PubMed

    Yang, Piaoping; Gai, Shili; Liu, Yanchao; Wang, Wenxin; Li, Chunxia; Lin, Jun

    2011-03-21

    Uniform hollow Lu(2)O(3):Ln (Ln = Eu(3+), Tb(3+)) phosphors have been successfully prepared via a urea-assisted homogeneous precipitation method using carbon spheres as templates, followed by a subsequent calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, kinetic decays, quantum yields (QY), and UV-visible diffuse reflectance spectra were employed to characterize the samples. The results show that hollow Lu(2)O(3):Ln spheres can be indexed to cubic Gd(2)O(3) phase with high purity. The as-prepared hollow Lu(2)O(3):Ln phosphors are confirmed to be uniform in shape and size with diameter of about 300 nm and shell thickness of approximate 20 nm. The possible formation mechanism of evolution from the carbon spheres to the amorphous precursor and to the final hollow Lu(2)O(3):Ln microspheres has been proposed. Upon ultraviolet (UV) and low-voltage electron beams excitation, the hollow Lu(2)O(3):Ln (Ln = Eu(3+), Tb(3+)) spheres exhibit bright red (Eu(3+), (5)D(0)-(7)F(2)) and green (Tb(3+), (5)D(4)-(7)F(5)) luminescence, which may find potential applications in the fields of color display and biomedicine.

  9. Mass incarceration can explain population increases in TB and multidrug-resistant TB in European and central Asian countries.

    PubMed

    Stuckler, David; Basu, Sanjay; McKee, Martin; King, Lawrence

    2008-09-09

    Several microlevel studies have pinpointed prisons as an important site for tuberculosis (TB) and multidrug-resistant TB in European and central Asian countries. To date, no comparative analyses have examined whether rises in incarceration rates can account for puzzling differences in TB trends among overall populations. Using longitudinal TB and cross-sectional multidrug-resistant TB data for 26 eastern European and central Asian countries, we examined whether and to what degree increases in incarceration account for differences in population TB and multidrug-resistant TB burdens. We find that each percentage point increase in incarceration rates relates to an increased TB incidence of 0.34% (population attributable risk, 95% C.I.: 0.10-0.58%, P < 0.01), after controlling for TB infrastructure; HIV prevalence; and several surveillance, economic, demographic, and political indicators. Net increases in incarceration account for a 20.5% increase in TB incidence or nearly three-fifths of the average total increase in TB incidence in the countries studied from 1991 to 2002. Although the number of prisoners is a significant determinant of differences in TB incidence and multidrug-resistant TB prevalence among countries, the rate of prison growth is a larger determinant of these outcomes, and its effect is exacerbated but not confounded by HIV. Differences in incarceration rates are a major determinant of differences in population TB outcomes among eastern European and central Asian countries, and treatment expansion alone does not appear to resolve the effect of mass incarceration on TB incidence.

  10. Innovative clinical trial designs to rationalize TB vaccine development.

    PubMed

    Ellis, R D; Hatherill, M; Tait, D; Snowden, M; Churchyard, G; Hanekom, W; Evans, T; Ginsberg, A M

    2015-05-01

    A recent trial of a leading tuberculosis (TB) vaccine candidate in 3000 South African infants failed to show protection over that from BCG alone, and highlights the difficulties in clinical development of TB vaccines. Progression of vaccine candidates to efficacy trials against TB disease rests on demonstration of safety and immunogenicity in target populations and protection against challenge in preclinical models, but immunologic correlates of protection are unknown, and animal models may not be predictive of results in humans. Even in populations most heavily affected by TB the sample sizes required for Phase 2b efficacy trials using TB disease as an endpoint are in the thousands. Novel clinical trial models have been developed to evaluate candidate TB vaccines in selected populations using biologically relevant outcomes and innovative statistical approaches. Such proof of concept studies can be used to more rationally select vaccine candidates for advancement to large scale trials against TB disease.

  11. The Effectiveness of Core ER Principles

    ERIC Educational Resources Information Center

    Jeon, Eun-Young; Day, Richard R.

    2015-01-01

    This discussion piece continues the discussion forum on extensive reading (ER) from the April 2015 issue of "Reading in a Foreign Language." In that forum, a number of the discussions were concerned with the principles of ER (Day & Bamford, 2002) in implementing ER. Our discussion also concerns the principles; we examine ER programs…

  12. Gd(III)-Gd(III) distance measurements with chirp pump pulses.

    PubMed

    Doll, Andrin; Qi, Mian; Wili, Nino; Pribitzer, Stephan; Godt, Adelheid; Jeschke, Gunnar

    2015-10-01

    The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S=7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero-field splitting

  13. Gd(III)-Gd(III) distance measurements with chirp pump pulses

    NASA Astrophysics Data System (ADS)

    Doll, Andrin; Qi, Mian; Wili, Nino; Pribitzer, Stephan; Godt, Adelheid; Jeschke, Gunnar

    2015-10-01

    The broad EPR spectrum of Gd(III) spin labels restricts the dipolar modulation depth in distance measurements between Gd(III) pairs to a few percent. To overcome this limitation, frequency-swept chirp pulses are utilized as pump pulses in the DEER experiment. Using a model system with 3.4 nm Gd-Gd distance, application of one single chirp pump pulse at Q-band frequencies leads to modulation depths beyond 10%. However, the larger modulation depth is counteracted by a reduction of the absolute echo intensity due to the pump pulse. As supported by spin dynamics simulations, this effect is primarily driven by signal loss to double-quantum coherence and specific to the Gd(III) high spin state of S = 7/2. In order to balance modulation depth and echo intensity for optimum sensitivity, a simple experimental procedure is proposed. An additional improvement by 25% in DEER sensitivity is achieved with two consecutive chirp pump pulses. These pulses pump the Gd(III) spectrum symmetrically around the observation position, therefore mutually compensating for dynamical Bloch-Siegert phase shifts at the observer spins. The improved sensitivity of the DEER data with modulation depths on the order of 20% is due to mitigation of the echo reduction effects by the consecutive pump pulses. In particular, the second pump pulse does not lead to additional signal loss if perfect inversion is assumed. Moreover, the compensation of the dynamical Bloch-Siegert phase prevents signal loss due to spatial dependence of the dynamical phase, which is caused by inhomogeneities in the driving field. The new methodology is combined with pre-polarization techniques to measure long distances up to 8.6 nm, where signal intensity and modulation depth become attenuated by long dipolar evolution windows. In addition, the influence of the zero-field splitting parameters on the echo intensity is studied with simulations. Herein, larger sensitivity is anticipated for Gd(III) complexes with zero

  14. Decay properties of long-lived isomers in the odd-odd N=81 nucleus {sup 146}Tb compared to the {sup 148}Ho and {sup 150}Tm nuclei

    SciTech Connect

    Kownacki, J.; Kisielinski, M.; Droste, Ch.; Morek, T.; Ruchowska, E.; Grodner, E.; Lieder, R. M.; Kowalczyk, M.; Wrzosek-Lipska, K.; Hadynska-KlePk, K.; Mierzejewski, J.; Andrzejewski, J.; Perkowski, J.; Napiorkowski, P. J.; Zielinska, M.; Kordyasz, A.; Srebrny, J.; Korman, A.

    2011-02-15

    Excited states of the {sup 146}Tb nucleus have been studied using {gamma}-ray and electron spectroscopy in off-beam and in-beam modes following {sup 112}Sn({sup 40}Ar,3n3p) reaction with the use of the OSIRIS-II, HPGe detector array and the conversion electron spectrometer. The multipolarity of the 343 keV transition deexciting the (7{sup -}) level in {sup 146}Tb shows mainly an E2 nature and the first excited state above the 23 s isomer is assigned as a (5{sup -},6{sup -}) state. The log ft values have been deduced for 11 {beta}{sup +}/EC transitions populating excited states in {sup 146}Gd. The systematic behavior of spins and parities of the long-lived levels at 0+x keV and the first excited states above them in the N=81 isotones {sup 146}Tb, {sup 148}Ho, and {sup 150}Tm is discussed.

  15. [Present and future perspectives for the rapid molecular diagnosis of TB and MDR-TB].

    PubMed

    Tanasescu, Mihaela; Didilescu, Cristian; Marica, Constantin

    2013-01-01

    Tuberculosis is still one of the diseases with a major medical and social impact, and in terms of early diagnosis (which would imply a fair treatment and established at the time), difficulties related to the delay bacilli isolation in culture, decreased susceptibility testing methods to antituberculosis drugs, lack of methods for differentiation of M. Tuberculosis complex germs of non-TB Mycobacteria, may have important clinical implications. Traditional testing of anti-TB drug susceptibility on solid Löwenstein-Jensen medium (gold standard) or liquid media can only be performed using grown samples. Determining the time it takes up to 42 days on solid media and 12 days for liquid media. For MDR/XDR TB cases itis absolutely essential to reduce the detection time. In these cases rapid diagnostic methods prove their usefulness. Automatic testing in liquid medium, molecular hybridization methods are currently recommended by the current WHO guidelines. Rapid diagnosis of MDR-TBis extremely useful for the early establishment of an effective treatment tailored more accurately on the spectrum of sensitivity of the resistant strain (thus reducing the risk of developing additional resistance to other drugs) and control the spread of these strains. Genetic diagnostic methods, approved and recommended by the WHO, can reduce the time of diagnosis of TB case and, importantly, the case of MDR-TB. They do not replace the current standard diagnostic methods and resistance profile, but complete them in selected cases.

  16. Prevalence of latent TB infection and TB disease among adolescents in high TB burden countries in Africa: a systematic review protocol

    PubMed Central

    Bunyasi, Erick Wekesa; Schmidt, Bey-Marrie; Abdullahi, Leila Hussein; Mulenga, Humphrey; Tameris, Michele; Luabeya, Angelique; Shenje, Justin; Scriba, Thomas; Geldenhuys, Hennie; Wood, Robin; Hatherill, Mark

    2017-01-01

    Introduction Almost a third of the world population has latent tuberculosis (TB) infection (LTBI), ∼10 million of whom develop TB disease annually, despite existence of effective, but lengthy, preventive and curative drug regimens. Although adolescents appear to have a very high force of LTBI, their reported incidence of TB disease is less than that of their corresponding general population. The few available studies on adolescent TB infection and disease prevalence are not sufficient to address the apparent discordance between rates of infection and disease in high TB burden countries in Africa. Therefore, we aim to perform a systematic review to examine the relationship between adolescent LTBI and TB disease, benchmarked against national TB disease burden data. Methods and analysis A comprehensive literature search will be performed for cross-sectional studies and screening data in cohort studies to determine the prevalence of LTBI and TB disease among adolescents in high TB burden countries in Africa in the following databases: PubMed, Scopus, Cochrane library, Web of Science, Africa Wide, CINAHL and the Africa Index Medicus. This will be supplemented by a search of reference lists of selected articles for potentially relevant articles. We will restrict our search to articles published in the English language between 1990 and 2016 among adolescents in order to obtain estimates reflective of the mature HIV epidemic in most high TB burden countries in Africa that occurred over this critical period. Primary end points are: prevalence of LTBI and TB disease. We will use the random-effects or fixed-effects modelling for our meta-analysis based on heterogeneity estimates. Ethics and dissemination No ethics approval is required given that this is a systematic review. Findings will be disseminated in a peer-reviewed journal in line with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). Trial registration number CRD42015023495. PMID

  17. Targeting O-Acetyl-GD2 Ganglioside for Cancer Immunotherapy.

    PubMed

    Fleurence, Julien; Fougeray, Sophie; Bahri, Meriem; Cochonneau, Denis; Clémenceau, Béatrice; Paris, François; Heczey, Andras; Birklé, Stéphane

    2017-01-01

    Target selection is a key feature in cancer immunotherapy, a promising field in cancer research. In this respect, gangliosides, a broad family of structurally related glycolipids, were suggested as potential targets for cancer immunotherapy based on their higher abundance in tumors when compared with the matched normal tissues. GD2 is the first ganglioside proven to be an effective target antigen for cancer immunotherapy with the regulatory approval of dinutuximab, a chimeric anti-GD2 therapeutic antibody. Although the therapeutic efficacy of anti-GD2 monoclonal antibodies is well documented, neuropathic pain may limit its application. O-Acetyl-GD2, the O-acetylated-derivative of GD2, has recently received attention as novel antigen to target GD2-positive cancers. The present paper examines the role of O-acetyl-GD2 in tumor biology as well as the available preclinical data of anti-O-acetyl-GD2 monoclonal antibodies. A discussion on the relevance of O-acetyl-GD2 in chimeric antigen receptor T cell therapy development is also included.

  18. Targeting O-Acetyl-GD2 Ganglioside for Cancer Immunotherapy

    PubMed Central

    Fleurence, Julien; Fougeray, Sophie; Bahri, Meriem; Cochonneau, Denis; Clémenceau, Béatrice; Paris, François; Heczey, Andras

    2017-01-01

    Target selection is a key feature in cancer immunotherapy, a promising field in cancer research. In this respect, gangliosides, a broad family of structurally related glycolipids, were suggested as potential targets for cancer immunotherapy based on their higher abundance in tumors when compared with the matched normal tissues. GD2 is the first ganglioside proven to be an effective target antigen for cancer immunotherapy with the regulatory approval of dinutuximab, a chimeric anti-GD2 therapeutic antibody. Although the therapeutic efficacy of anti-GD2 monoclonal antibodies is well documented, neuropathic pain may limit its application. O-Acetyl-GD2, the O-acetylated-derivative of GD2, has recently received attention as novel antigen to target GD2-positive cancers. The present paper examines the role of O-acetyl-GD2 in tumor biology as well as the available preclinical data of anti-O-acetyl-GD2 monoclonal antibodies. A discussion on the relevance of O-acetyl-GD2 in chimeric antigen receptor T cell therapy development is also included. PMID:28154831

  19. Effect of Al2Gd on microstructure and properties of laser clad Mg-Al-Gd coatings

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Zhang, Ke; Yao, Chengwu; Dong, Jie; Li, Zhuguo; Emmelmann, Claus

    2015-03-01

    In order to investigate the effects of Gd addition on the microstructures and properties of magnesium coatings, the Mg-7.5Al-xGd (x = 0, 2.5, 5.0 and 7.5 wt.%) coatings on cast magnesium alloy were fabricated by laser cladding with wire feeding. The results indicated that the gadolinium (Gd) addition led to the formation of a cubic Al2Gd phase as well as suppressed the precipitation of eutectic Mg17Al12 phase. The laser clad coating containing nominally 7.5 wt.% Gd presented the highest microhardness, ultimate tensile strength and yield strength at both room temperature and high temperatures. The enhancement of heat resistant capacities was chiefly attributed to the existence of thermally stable Al2Gd particles, which prevented tiny liquation of eutectic phases along the grain boundaries and made great contributions on maintaining high yield ratio during high-temperature deformation.

  20. Giant magnetocaloric effect in GdAlO3 and a comparative study with GdMnO3

    NASA Astrophysics Data System (ADS)

    Mahana, Sudipta; Manju, U.; Topwal, D.

    2017-01-01

    The magnetic properties and magnetocaloric effect of polycrystalline GdAlO3 and GdMnO3 have been investigated to assess their potential usage as magnetic refrigerants at cryogenic temperatures. These compounds undergo antiferromagnetic transitions at low temperatures which are associated with the giant magnetic entropy change effect (-\\bigtriangleup {{S}M} )  ˜40.9 J Kg · K-1 under a field change of 0-9 T for GdAlO3 while the moderate effect of 18 J Kg · K-1 is observed for polycrystalline GdMnO3. Though the relative cooling power of both the stated materials is similar however, the absence of magnetic and thermal hysteresis makes GdAlO3 a more efficient magnetic refrigerant than GdMnO3.

  1. The ER Stress Surveillance (ERSU) pathway regulates daughter cell ER protein aggregate inheritance.

    PubMed

    Piña, Francisco J; Niwa, Maho

    2015-09-01

    Stress induced by cytoplasmic protein aggregates can have deleterious consequences for the cell, contributing to neurodegeneration and other diseases. Protein aggregates are also formed within the endoplasmic reticulum (ER), although the fate of ER protein aggregates, specifically during cell division, is not well understood. By simultaneous visualization of both the ER itself and ER protein aggregates, we found that ER protein aggregates that induce ER stress are retained in the mother cell by activation of the ER Stress Surveillance (ERSU) pathway, which prevents inheritance of stressed ER. In contrast, under conditions of normal ER inheritance, ER protein aggregates can enter the daughter cell. Thus, whereas cytoplasmic protein aggregates are retained in the mother cell to protect the functional capacity of daughter cells, the fate of ER protein aggregates is determined by whether or not they activate the ERSU pathway to impede transmission of the cortical ER during the cell cycle.

  2. Atomic transition probabilities of Gd i

    NASA Astrophysics Data System (ADS)

    Lawler, J. E.; Bilty, K. A.; Den Hartog, E. A.

    2011-05-01

    Fourier transform spectra are used to determine emission branching fractions for 1290 lines of the first spectrum of gadolinium (Gd i). These branching fractions are converted to absolute atomic transition probabilities using previously reported radiative lifetimes from time-resolved laser-induced-fluorescence measurements (Den Hartog et al 2011 J. Phys. B: At. Mol. Opt. Phys. 44 055001). The wavelength range of the data set is from 300 to 1850 nm. A least squares technique for separating blends of the first and second spectra lines is also described and demonstrated in this work.

  3. TB and MDR/XDR-TB in European Union and European Economic Area countries: managed or mismanaged?

    PubMed

    Migliori, G B; Sotgiu, G; D'Ambrosio, L; Centis, R; Lange, C; Bothamley, G; Cirillo, D M; De Lorenzo, S; Guenther, G; Kliiman, K; Muetterlein, R; Spinu, V; Villar, M; Zellweger, J P; Sandgren, A; Huitric, E; Manissero, D

    2012-03-01

    In spite of the growing awareness of emerging drug-resistant Mycobacterium tuberculosis, the extent of inappropriate tuberculosis (TB) case management may be underestimated, even in Europe. We evaluated TB case management in the European Union/European Economic Area countries, with special focus on multidrug-resistant (MDR) and extensively drug-resistant (XDR)-TB, using a purposely developed, standardised survey tool. National reference centres in five countries representing different geographical, socioeconomic and epidemiological patterns of TB in Europe were surveyed. 40 consecutive, original clinical TB case records (30 MDR/XDR-TB cases) were reviewed in each of the five countries. The findings were recorded and, through the survey tool, compared with previously agreed and identified international standards. Deviations from international standards of TB care were observed in the following areas: surveillance (no information available on patient outcomes); infection control (lack of respiratory isolation rooms/procedures and negative-pressure ventilation rooms); clinical management of TB, MDR-TB and HIV co-infection (inadequate bacteriological diagnosis, regimen selection and treatment duration); laboratory support; and diagnostic/treatment algorithms. Gaps between present international standards of care and the management of MDR/XDR-TB patients were identified. Training, increased awareness, promotion of standards and allocation of appropriate resources are necessary to ensure appropriate care and management as well as to prevent further emergence of drug resistance.

  4. Investigation of nanostructured Lu2O3:Tb

    NASA Astrophysics Data System (ADS)

    Zych, E.; Deren, Przemyslaw J.; Strek, Wieslaw; Meijerink, Andries; Domagala, K.; Mielcarek, W.

    2001-04-01

    Nano structured Lu2O3, both plane and doped with Tb, was prepared utilizing a combustion technique. The best crystallity of the products can be obtained initiating the reaction within 560-700 $DEGC range of temperature. Tb easily enters the nano scaled host lattice both as Tb3+ and Tb4+. The former gives rise to a typical green emission of the ion, while the later introduces a broad-band visible absorption, due to charge transfer transitions. The green emission of Tb3+ from a raw material may be radically increased by after- preparation heat-treatment. Undoped material gives rise to a blue emission, which disappears when Tb content with respect to Lu reaches 0.0001% or higher level.

  5. Luminescence sensitization of Tb(3+)-DNA complexes by Ag().

    PubMed

    Xu, Lijun; Zhou, Lu; Chen, Xing; Shen, Xiaoqiang; Wang, Jine; Zhang, Jianye; Pei, Renjun

    2017-03-03

    Terbium ions (Tb(3+)) with unique photophysical properties have been utilized to develop biosensors with low background and high sensitivity. In this study, the Ag(+)-sensitized luminescence of Tb(3+)-DNA complexes was uncovered. The luminescence of Tb(3+)-DNA complexes could be enhanced by more than 30 times in the presence of Ag(+), when Tb(3+) was bound with poly(G) and poly(T) whereas not with other homopolymers. This research confirmed that the sensitization resulted from the interaction of Ag(+) with certain bases involved in DNA, not just with the reported certain G-quadruplex sequence. The coordination of Ag(+) to guanine and thymine bases was expected to increase their rigidities, form Tb(3+)-DNA-Ag(+) ternary structures, and thus enhance energy transfer from guanine and thymine to Tb(3+). These findings benefit the development of sensitive luminescence probes for various nucleic acids-related targets.

  6. An Imbalanced Learning based MDR-TB Early Warning System.

    PubMed

    Li, Sheng; Tang, Bo; He, Haibo

    2016-07-01

    As a man-made disease, multidrug-resistant tuberculosis (MDR-TB) is mainly caused by improper treatment programs and poor patient supervision, most of which could be prevented. According to the daily treatment and inspection records of tuberculosis (TB) cases, this study focuses on establishing a warning system which could early evaluate the risk of TB patients converting to MDR-TB using machine learning methods. Different imbalanced sampling strategies and classification methods were compared due to the disparity between the number of TB cases and MDR-TB cases in historical data. The final results show that the relative optimal predictions results can be obtained by adopting CART-USBagg classification model in the first 90 days of half of a standardized treatment process.

  7. Dipstick urinalysis for diabetes screening in TB patients

    PubMed Central

    Restrepo, Blanca I.; Pino, Paula A.; Zarate, Izelda; Mora-Guzman, Francisco

    2013-01-01

    Introduction Diabetes knowledge among TB patients can contribute to improved TB treatment outcomes, but lack of diabetes diagnosis awareness is a limitation in developing countries. Given its low cost, the sensitivity of urine glucose dipsticks for diabetes screening in TB patients was assessed. Methods Glycosuria was assessed in 90 newly diagnosed TB patients (38 with diabetes) in south Texas, USA (n = 20) and northeast Mexico (n = 70) during January 2009–December 2010. Results Glycosuria was detected in 65% of the diabetic patients with chronic hyperglycemia (positive predictive value 91%, negative predictive value 84%). Conclusion We propose that TB clinics with limited budgets where portable glucometers may not be available conduct universal screening for diabetes with urine dipsticks. This could be followed by blood glucose or HbA1c testing in the subset of patients requiring confirmation or higher sensitivity assessment, to improve the comanagement of TB and diabetes. PMID:24030116

  8. Ames ER-2 ozone measurements

    NASA Technical Reports Server (NTRS)

    Pearson, R., Jr.; Vedder, James F.; Starr, W. L.

    1990-01-01

    The objective of this research is to study ozone (O3) in the stratosphere. Measurements of the ozone mixing ratio at 1 s intervals are obtained with an ultraviolet photometer which flies on the ER-2 aircraft. The photometer determines the amount of ozone in air by measuring the transmission of ultraviolet light through a fixed path with and without ambient O3 present.

  9. ERS-1 SAR data processing

    NASA Technical Reports Server (NTRS)

    Leung, K.; Bicknell, T.; Vines, K.

    1986-01-01

    To take full advantage of the synthetic aperature radar (SAR) to be flown on board the European Space Agency's Remote Sensing Satellite (ERS-1) (1989) and the Canadian Radarsat (1990), the implementation of a receiving station in Alaska is being studied to gather and process SAR data pertaining in particular to regions within the station's range of reception. The current SAR data processing requirement is estimated to be on the order of 5 minutes per day. The Interim Digital Sar Processor (IDP) which was under continual development through Seasat (1978) and SIR-B (1984) can process slightly more than 2 minutes of ERS-1 data per day. On the other hand, the Advanced Digital SAR Processore (ADSP), currently under development for the Shuttle Imaging Radar C (SIR-C, 1988) and the Venus Radar Mapper, (VMR, 1988), is capable of processing ERS-1 SAR data at a real time rate. To better suit the anticipated ERS-1 SAR data processing requirement, both a modified IDP and an ADSP derivative are being examined. For the modified IDP, a pipelined architecture is proposed for the mini-computer plus array processor arrangement to improve throughout. For the ADSP derivative, a simplified version is proposed to enhance ease of implementation and maintainability while maintaing real time throughput rates. These processing systems are discussed and evaluated.

  10. Stokes Emission inGdF3:Nd3+Nanoparticles for Bioimaging Probe

    PubMed Central

    Pokhrel, M.; Mimun, L.C.; Yust, B.; Kumar, G.A.; Dhanale, A.; Tang, L.; Sardar, D.K.

    2014-01-01

    There is an increasing interest in rare earth (RE) doped nanoparticles (NPs) due to their sharp absorption and photoluminescence (PL) in the near infrared (NIR) spectral region. These NIR based nanoparticles (NPs) could allow biological imaging at substantial depths with enhanced contrast and high spatial resolution due to the absence of auto fluorescence in biological samples under infrared excitation. Here, we present the highly efficient infrared photoluminescence in GdF3:Nd3+ nanoparticles under 800 nm excitation within the hydrodynamic size limitations for bio-applications. The downconversion (Stokes emission) absolute quantum yield (QY) measurements in powder, poly maleic anhydride- alt-1- octadicene (PMAO) coated powder and colloidal solutions have been investigated. QY measurements have revealed that downconversion(Stokes emission)QY in an average 5 ± 2 nm sized GdF3: 1% Nd3+colloidalNPs are 2000 times higher than efficient upconversion (UC) particles NaYF4: 20 % Er/ 2% Yb of same size. Furthermore, the utility of these NIR emitting nanoparticles forbioimagingprobe has been demonstrated by confocal imaging and spectroscopic study. PMID:24336743

  11. Integrating patients’ perspectives into integrated TB/HIV healthcare

    PubMed Central

    Daftary, Amrita; Padayatchi, Nesri

    2013-01-01

    Background Escalating rates of TB/HIV coinfection call for improved coordination of TB and HIV healthcare services in high-burden countries such as South Africa. Patient perspectives, however, are poorly understood in the context of current integration efforts. Method Under a qualitative research framework, we interviewed 40 HIV-positive adult TB patients and 8 key-informant healthcare workers across 3 clinics in KwaZulu-Natal province to explore non-clinical and non-operational aspects of TB/HIV healthcare. Findings Qualitative analysis highlighted critical social and ethical considerations for the concurrent delivery of TB and HIV care. Coinfected patients navigating between TB and HIV programs are exposed to missed opportunities for TB and HIV service integration, fragmented or vertical care for their dual infections, and contrasting experiences within TB and HIV clinics. These intersecting issues appear to affect patients’ health-related decisions, particularly HIV nondisclosure to non-HIV healthcare workers, and their preferences for integrated healthcare. Conclusion Our study highlights the imperative to address service fragmentation, HIV medical confidentiality and provider mistrust within the healthcare system, and the cultural differences associated with TB and HIV disease control. PMID:23407149

  12. A topologically unique alternating {CoGd} magnetocaloric ring.

    PubMed

    Ojea, María José Heras; Lorusso, Giulia; Craig, Gavin A; Wilson, Claire; Evangelisti, Marco; Murrie, Mark

    2017-04-13

    The adiabatic temperature change of the star-shaped {CoGd} magnetocaloric ring is enhanced via topological control over the assembly process, by using a pre-formed {Co(II)(H6L)} building block that undergoes oxidation to Co(III), successfully separating the Gd(III) ions.

  13. Electronic transitions in GdN band structure

    SciTech Connect

    Vidyasagar, R. Kita, T.; Sakurai, T.; Ohta, H.

    2014-05-28

    Using the near-infrared (NIR) absorbance spectroscopy, electronic transitions and spin polarization of the GdN epitaxial film have been investigated; and the GdN epitaxial film was grown by a reactive rf sputtering technique. The GdN film exhibited three broad bands in the NIR frequency regimes; and those bands are attributable primarily to the minority and majority spin transitions at the X-point and an indirect transition along the Γ-X symmetric direction of GdN Brillouin zone. We experimentally observe a pronounced red-shift of the indirect band gap when cooling down below the Curie temperature which is ascribed to the orbital-dependent coulomb interactions of Gd-5dxy electrons, which tend to push-up the N-2p bands. On the other hand, we have evaluated the spin polarization of 0.17 (±0.005), which indicates that the GdN epitaxial film has almost 100% spin-polarized carriers. Furthermore, the experimental result of GdN electronic transitions are consistent with the previous reports and are thus well-reproduced. The Arrott plots evidenced that the Curie temperature of GdN film is 36 K and the large spin moment is explained by the nitrogen vacancies and the intra-atomic exchange interaction.

  14. Decreasing cost effectiveness of testing for latent TB in HIV in a low TB incidence area.

    PubMed

    Capocci, Santino; Smith, Colette; Morris, Stephen; Bhagani, Sanjay; Cropley, Ian; Abubakar, Ibrahim; Johnson, Margaret; Lipman, Marc

    2015-07-01

    Testing for latent tuberculosis infection (LTBI) in HIV-infected persons in low tuberculosis (TB) incidence areas is often recommended. Using contemporary, clinical data, we report the yield and cost-effectiveness of testing all HIV attendees, two current UK strategies and no LTBI testing. Economic modelling was performed utilising 10-year follow up data from a large HIV clinical cohort. Outcomes were numbers of cases of active TB and incremental cost per quality-adjusted life year (QALY) gained. Between 2000 and 2010, 256 people were treated for TB/HIV co-infection. 72 (28%) occurred ≥3 months after HIV diagnosis and may have been prevented by LTBI testing. Between 2000 and 2005, the incremental cost per QALY gained for the British HIV Association (BHIVA) and UK National Institute of Care Excellence (NICE) strategies, and testing all clinic attendees was €6270, €6998 and €33,473, respectively. These rose to €9332, €32,564 and €74,067, respectively, between 2005 and 2010. Probabilistic sensitivity analysis suggested that at a threshold of €24,000 per additional QALY, the most cost-effective strategies would be NICE or testing all in 2000-2005 and BHIVA during 2005-2010. Both UK testing regimens missed cases but are cost-effective compared with no testing. Using recent data, they all became more expensive, suggesting that alternative or more targeted TB testing strategies must be considered.

  15. Peculiarities of neutron waveguides with thin Gd layer

    NASA Astrophysics Data System (ADS)

    Khaydukov, Yu; Kravtsov, E.; Progliado, V.; Ustinov, V.; Nikitenko, Yu; Keller, T.; Aksenov, V.; Keimer, B.

    2016-09-01

    Peculiarities of the formation of a neutron enhanced standing wave in the structure with a thin highly absorbing layer of gadolinium are considered in the article. An analogue of the poisoning effect well known in reactor physics was found. The effect is stronger for the Nb/Gd/Nb system. Despite of this effect, for a Nb/Gd bilayer and a Nb/Gd/Nb trilayer placed between Al2O3 substrate and Cu layer, it is shown theoretically and experimentally that one order of magnitude enhancement of neutron density is possible in the vicinity of the Gd layer. This enhancement makes it possible to study domain formation in the Gd layer under transition of the Nb layer(s) into the superconducting state (cryptoferromagnetic phase).

  16. Endoplasmic Reticulum (ER) Stress and Endocrine Disorders

    PubMed Central

    Ariyasu, Daisuke; Yoshida, Hiderou; Hasegawa, Yukihiro

    2017-01-01

    The endoplasmic reticulum (ER) is the organelle where secretory and membrane proteins are synthesized and folded. Unfolded proteins that are retained within the ER can cause ER stress. Eukaryotic cells have a defense system called the “unfolded protein response” (UPR), which protects cells from ER stress. Cells undergo apoptosis when ER stress exceeds the capacity of the UPR, which has been revealed to cause human diseases. Although neurodegenerative diseases are well-known ER stress-related diseases, it has been discovered that endocrine diseases are also related to ER stress. In this review, we focus on ER stress-related human endocrine disorders. In addition to diabetes mellitus, which is well characterized, several relatively rare genetic disorders such as familial neurohypophyseal diabetes insipidus (FNDI), Wolfram syndrome, and isolated growth hormone deficiency type II (IGHD2) are discussed in this article. PMID:28208663

  17. Thermochemical investigations in the system Cd–Gd

    PubMed Central

    Reichmann, Thomas L.; Ganesan, Rajesh; Ipser, Herbert

    2014-01-01

    Vapour pressure measurements were performed in terms of a non-isothermal isopiestic method to determine vapour pressures of Cd in the system Cd–Gd between 693 and 1045 K. From these results thermodynamic activities of Cd were derived as a function of temperature for the composition range 52–86 at.% Cd. By employing an adapted Gibbs–Helmholtz equation, partial molar enthalpies of mixing of Cd were obtained for the corresponding composition range, which were used to convert the activity values of Cd to a common average sample temperature of 773 K. The relatively large variation of the activity across the homogeneity ranges of the phases Cd2Gd and Cd45Gd11 indicates that they probably belong to the most stable intermetallic compounds in this system. An activity value of Gd for the two phase field Cd6Gd+L was available from literature and served as an integration constant for a Gibbs–Duhem integration. Integral Gibbs energies are presented between 51 and 100 at.% Cd at 773 K, referred to Cd(l) and α-Gd(s) as standard states. Gibbs energies of formation for the exact stoichiometric compositions of the phases Cd58Gd13, Cd45Gd11, Cd3Gd and Cd2Gd were obtained at 773 K as about −19.9, −21.1, −24.8, and −30.0 kJ g atom−1, respectively. PMID:25328283

  18. First Outcome of MDR-TB among Co-Infected HIV/TB Patients from South-West Iran

    PubMed Central

    Motamedifar, Mohammad; Abadi, Ali Reza Hassan; Moghadam, Mahboube Nakhzari

    2015-01-01

    Background Tuberculosis (TB) is the leading cause of mortality among human immunodeficiency virus (HIV) patients and the majority of them occur in developing countries. The aims of the present study were to determine the frequency of HIV/TB co-infection and other probable associated factors. Methods This 10 year retrospective study was conducted on 824 HIV patients in the south-west of Iran. HIV infection was diagnosed by the enzyme linked immunosorbent assay and confirmed by Western blot. TB diagnosis was based on consistency of the clinical manifestations, chest X-ray, and microscopic examination. Drug susceptibility testing was done by the proportional method on Löwenstein-Jensen media. Results Of 824 HIV patients, 59 (7.2%) were identified as TB co-infected and the majority (86.4%) of them were male. Of the overall TB infected patients, 6 cases (10.2%) showed multidrug-resistant with the mean CD4+ lymphocyte count of 163±166 cells/mm3. The main clinical forms of TB were pulmonary (73%). There was a significant (p<0.05) correlation between TB infection and CD4+ lymphocyte counts ≤200 cells/mm3, gender, prison history, addiction history, and highly active anti-retroviral therapy. Conclusion We reported novel information on frequency of HIV/TB co-infection and multidrug resistant-TB outcome among co-infected patients that could facilitate better management of such infections on a global scale. PMID:26175780

  19. Observations of the Gamow-Teller resonance in the rare-earth nuclei above 146Gd populated in β decay

    NASA Astrophysics Data System (ADS)

    Nácher, E.; Rubio, B.; Algora, A.; Cano-Ott, D.; Taín, J. L.; Gadea, A.; Agramunt, J.; Gierlik, M.; Karny, M.; Janas, Z.; Roeckl, E.; Blazhev, A.; Collatz, R.; Döring, J.; Hellström, M.; Hu, Z.; Kirchner, R.; Mukha, I.; Plettner, C.; Shibata, M.; Rykaczewski, K.; Batist, L.; Moroz, F.; Wittmann, V.; Valiente-Dobón, J. J.

    2016-01-01

    The rare-earth region of the nuclear table around the quasi-doubly magic nucleus 146Gd is one of the very few places in which the Gamow-Teller (GT) resonance can be populated in β decay. The appropriate technique to study such a phenomenon is total absorption spectroscopy, thanks to which one can measure the B (GT) distribution in β -decay experiments even when it is very fragmented and lies at high excitation energy in the daughter nucleus. Results on the GT resonance measured in the β decay of the odd-Z , N =83 nuclei 148Tb 150Ho, and 152Tm are presented in this work and compared with shell-model calculations. The tail of the resonance is clearly observed up to the limit imposed by the Q value. This observation is important in the context of the understanding of the "quenching" of the GT strength.

  20. Alpha particle spectra in coincidence with normal and superdeformed states in {sup 150}Tb

    SciTech Connect

    Viesti, G.; Lunardon, M.; Bazzacco, D. |

    1996-12-31

    The study of correlations between particle evaporation from highly excited compound nuclei at large angular momenta and the states in the final evaporation residues (ER) is a field of investigation which has been opened, in the last years, with the advent of the new large {gamma}-ray arrays. It is now possible to correlate the evaporation spectra to various bands with shapes ranging from spherical to superdeformed (SD) in the same final nucleus. It is generally accepted that the particle evaporation from the compound nucleus is chaotic and that only in the near-yrast {gamma} cascade, where the feeding of different classes of states takes place, the ordered motion is restored. The sensitivity of the particle spectra on the feeding of specific states in the residual nuclei can be taken as an indication that additional degrees of freedom might be important in the evaporation process or that particular regions of the phase space open to the decay populate preferentially some selected structures in the final cold nucleus. This latter point is important for the understanding of the feeding mechanism of SD states. Several experiments performed so far did not find a clear dependence of the shapes of the particle spectra on the excited states having different deformations in the ER. For example, the proton spectra in coincidence with transitions in the SD bands of {sup 133}Nd and {sup 152}Dy nuclei were found to be similar to those in coincidence with transitions in the normal deformed (ND) bands. Alpha particles have been proposed since long as a sensitive probe of the deformation of the emitting nucleus. Results are presented here of an experiment in which the authors have measured the energy spectra of alpha particles associated with different classes of states (ND and SD) in the {sup 150}Tb nucleus populated in the reaction {sup 37}Cl({sup 120}Sn, {alpha}3n{gamma}){sup 150}Tb.

  1. Rapid identification of tuberculosis epididymo-orchitis by INNO-LiPA Rif TB and QuantiFERON-TB Gold In Tube tests: case report.

    PubMed

    Paluch-Oleś, Jolanta; Magryś, Agnieszka; Kot, Ewa; Kozioł-Montewka, Maria

    2010-03-01

    Diagnosis of extrapulmonary tuberculosis (TB) is often missed or delayed because of nonspecific clinical and laboratory findings. Novel detection methods, such as polymerase chain reaction and QuantiFERON-TB Gold In Tube, can aid in the diagnosis of active extrapulmonary TB. Here, we demonstrate a case of epididymo-orchitis as the sole presentation of TB in a 32-year-old man.

  2. The Characteristics of TB Epidemic and TB/HIV Co-Infection Epidemic: A 2007–2013 Retrospective Study in Urumqi, Xinjiang Province, China

    PubMed Central

    Wei, Wang; Wei-Sheng, Zhang; Ahan, Alayi; Ci, Yan; Wei-Wen, Zhang; Ming-Qin, Cao

    2016-01-01

    Objective This study was aimed to find out epidemiologic characteristic of tuberculosis (TB) cases, and Human Immunodeficiency Virus (HIV) positive cases among TB patients (TB/HIV co-infection) through demographic, temporal, and spatial study in Urumqi. Methods Descriptive statistics and multivariate logistic regression were applied to identify the epidemiologic characteristics and risk factors of TB epidemic and TB/HIV co-infection epidemic. All addresses of each TB case, TB/HIV co-infection case, and administrative street were transformed into geographical coordinate. Subsequently, the geocoded address for 82 streets was transformed into a dot map used as the basis of spatial datasets. In addition, the paper also used quantile map and the spatial scan statistic in order to identify the spatial distribution and spatial clusters of TB epidemic and TB/HIV co-infection epidemic. Result There was a declining trend of the notification rates of TB epidemic from 2007 to 2009, as well as a rising trend from 2010 to 2013. However, the notification rates of TB/HIV co-infection epidemic showed a rising trend from 2007 to 2010, and a declining trend from 2011 to 2013. Moreover, a significant share of TB epidemic and TB/HIV co-infection epidemic happened between the age of 15 to 45 years old, indicating an increase in risk of TB and TB/HIV infection. It is worth noting that the risk of HIV infection for male TB patients was 2.947 times (95% CI [2.178, 3.988]) than that of female patients. Han ethnicity and Uygur ethnicity in urban region accounted for a large proportion of total TB and TB/HIV co-infection cases. Most of the TB cases of minorities in Urumqi showed a statistically significant increase in risk of HIV infection than Han ethnicity in Urumqi. In addition, the spatial distribution of TB epidemic and TB/HIV co-infection epidemic was highly skewed. Most of the local clusters were located in urban area and rural-urban continuum where showed an increase in risk of TB and

  3. 46 CFR 35.30-25 - Explosives-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Explosives-TB/ALL. 35.30-25 Section 35.30-25 Shipping... Explosives—TB/ALL. Fulminates or other detonating compounds in bulk in dry condition; explosive compositions... other like explosives shall not be accepted, stored, stowed or transported on board tank vessels....

  4. 46 CFR 35.30-25 - Explosives-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Explosives-TB/ALL. 35.30-25 Section 35.30-25 Shipping... Explosives—TB/ALL. Fulminates or other detonating compounds in bulk in dry condition; explosive compositions... other like explosives shall not be accepted, stored, stowed or transported on board tank vessels....

  5. 46 CFR 35.30-25 - Explosives-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Explosives-TB/ALL. 35.30-25 Section 35.30-25 Shipping... Explosives—TB/ALL. Fulminates or other detonating compounds in bulk in dry condition; explosive compositions... other like explosives shall not be accepted, stored, stowed or transported on board tank vessels....

  6. 46 CFR 35.30-25 - Explosives-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Explosives-TB/ALL. 35.30-25 Section 35.30-25 Shipping... Explosives—TB/ALL. Fulminates or other detonating compounds in bulk in dry condition; explosive compositions... other like explosives shall not be accepted, stored, stowed or transported on board tank vessels....

  7. 46 CFR 35.30-25 - Explosives-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Explosives-TB/ALL. 35.30-25 Section 35.30-25 Shipping... Explosives—TB/ALL. Fulminates or other detonating compounds in bulk in dry condition; explosive compositions... other like explosives shall not be accepted, stored, stowed or transported on board tank vessels....

  8. 46 CFR 30.10-45 - Ocean-TB/O.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Ocean-TB/O. 30.10-45 Section 30.10-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-45 Ocean—TB/O. Under this designation shall be included all tank vessels normally navigating the waters of any ocean...

  9. 46 CFR 30.10-45 - Ocean-TB/O.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Ocean-TB/O. 30.10-45 Section 30.10-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-45 Ocean—TB/O. Under this designation shall be included all tank vessels normally navigating the waters of any ocean...

  10. 46 CFR 30.10-45 - Ocean-TB/O.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Ocean-TB/O. 30.10-45 Section 30.10-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-45 Ocean—TB/O. Under this designation shall be included all tank vessels normally navigating the waters of any ocean...

  11. 46 CFR 30.10-35 - Headquarters-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Headquarters-TB/ALL. 30.10-35 Section 30.10-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-35 Headquarters—TB/ALL. The term Headquarters means the Commandant (CG-CVC), Attn: Office of Commercial...

  12. 46 CFR 30.10-35 - Headquarters-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Headquarters-TB/ALL. 30.10-35 Section 30.10-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-35 Headquarters—TB/ALL. The term Headquarters means the Commandant (CG-CVC), Attn: Office of Commercial...

  13. 46 CFR 35.03-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 35.03-1 Section 35.03-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Work Vests § 35.03-1 Application—TB/ALL. (a) Provisions of this subpart shall apply to all tank vessels....

  14. 46 CFR 34.30-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 34.30-1 Section 34.30-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Automatic Sprinkler Systems, Details § 34.30-1 Application—TB/ALL. Automatic sprinkler systems shall comply with NFPA 13-1996....

  15. 46 CFR 34.10-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 34.10-1 Section 34.10-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Fire Main System, Details § 34.10-1 Application—TB/ALL. (a) On all tankships the provisions of this subpart, with...

  16. 46 CFR 32.70-10 - Cofferdams-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cofferdams-TB/ALL. 32.70-10 Section 32.70-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Cofferdams—TB/ALL. Tank vessels carrying Grade A, B, or C liquids shall be required to conform to...

  17. 46 CFR 34.50-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 34.50-1 Section 34.50-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Portable and Semiportable Extinguishers § 34.50-1 Application—TB/ALL. (a) The provisions of this subpart, with the...

  18. 46 CFR 32.70-10 - Cofferdams-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cofferdams-TB/ALL. 32.70-10 Section 32.70-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Cofferdams—TB/ALL. Tank vessels carrying Grade A, B, or C liquids shall be required to conform to...

  19. 46 CFR 30.10-61 - Rivers-TB/R.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Rivers-TB/R. 30.10-61 Section 30.10-61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-61 Rivers—TB/R. Under this designation shall be included all tank vessels whose navigation is restricted...

  20. 46 CFR 30.10-7 - Certificated-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Certificated-TB/ALL. 30.10-7 Section 30.10-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-7 Certificated—TB/ALL. The term certificated when applied to tank vessels refers to a vessel covered by...

  1. 46 CFR 30.10-61 - Rivers-TB/R.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Rivers-TB/R. 30.10-61 Section 30.10-61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-61 Rivers—TB/R. Under this designation shall be included all tank vessels whose navigation is restricted...

  2. 46 CFR 30.10-49 - Permit-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Permit-TB/ALL. 30.10-49 Section 30.10-49 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-49 Permit—TB/ALL. The term permit refers to endorsement on the certificate of inspection, authorizing the...

  3. 46 CFR 30.10-5 - Cargo-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cargo-TB/ALL. 30.10-5 Section 30.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5 Cargo—TB/ALL. The term cargo means combustible liquid, flammable liquid, or liquefied flammable gas...

  4. 46 CFR 30.10-71 - Tankerman-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Tankerman-TB/ALL. 30.10-71 Section 30.10-71 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-71 Tankerman—TB/ALL. The following ratings are established in part 13 of this chapter. The terms for...

  5. 46 CFR 30.10-17 - Commandant-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Commandant-TB/ALL. 30.10-17 Section 30.10-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-17 Commandant—TB/ALL. The term Commandant means the Commandant of the Coast Guard....

  6. 46 CFR 32.75-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 32.75-1 Section 32.75-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Application—TB/ALL. All wood hull tank vessels, the construction or conversion of which was started prior...

  7. 46 CFR 30.10-17 - Commandant-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Commandant-TB/ALL. 30.10-17 Section 30.10-17 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-17 Commandant—TB/ALL. The term Commandant means the Commandant of the Coast Guard....

  8. 46 CFR 35.07-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 35.07-1 Section 35.07-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Logbook Entries § 35.07-1 Application—TB/ALL. (a) Except as specifically noted, the provisions of this subpart shall apply to all...

  9. 46 CFR 34.50-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 34.50-1 Section 34.50-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Portable and Semiportable Extinguishers § 34.50-1 Application—TB/ALL. (a) The provisions of this subpart, with the...

  10. 46 CFR 32.57-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 32.57-1 Section 32.57-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Application—TB/ALL. (a) The provisions of this subpart shall apply to all tank vessels contracted for on...

  11. 46 CFR 31.20-1 - Waters-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Waters-TB/ALL. 31.20-1 Section 31.20-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS INSPECTION AND CERTIFICATION Waters Operated Over § 31.20-1 Waters—TB/ALL. The certificate of inspection shall show the waters over which the tank...

  12. 46 CFR 30.10-38 - Lightweight-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Lightweight-TB/ALL. 30.10-38 Section 30.10-38 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-38 Lightweight—TB/ALL. The term lightweight means the displacement of a vessel in metric tons without cargo,...

  13. 46 CFR 30.10-35 - Headquarters-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Headquarters-TB/ALL. 30.10-35 Section 30.10-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-35 Headquarters—TB/ALL. The term Headquarters means the Office of the Commandant, U.S. Coast Guard, Washington,...

  14. 46 CFR 32.65-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 32.65-1 Section 32.65-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL..., 1951 § 32.65-1 Application—TB/ALL. The requirements in this subpart apply to all tank vessels,...

  15. 46 CFR 32.40-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 32.40-1 Section 32.40-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Accommodations for Officers and Crew § 32.40-1 Application—TB/ALL. (a) The provisions of...

  16. 46 CFR 30.10-35 - Headquarters-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Headquarters-TB/ALL. 30.10-35 Section 30.10-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-35 Headquarters—TB/ALL. The term Headquarters means the Office of the Commandant, U.S. Coast Guard, Washington,...

  17. 46 CFR 32.75-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 32.75-1 Section 32.75-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Application—TB/ALL. All wood hull tank vessels, the construction or conversion of which was started prior...

  18. 46 CFR 32.65-15 - Cofferdams-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cofferdams-TB/ALL. 32.65-15 Section 32.65-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL..., 1951 § 32.65-15 Cofferdams—TB/ALL. Tank vessels equipped to carry Grade A, B, C, or D liquids...

  19. 46 CFR 30.10-7 - Certificated-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Certificated-TB/ALL. 30.10-7 Section 30.10-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-7 Certificated—TB/ALL. The term certificated when applied to tank vessels refers to a vessel covered by...

  20. 46 CFR 38.05-5 - Markings-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Markings-TB/ALL. 38.05-5 Section 38.05-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS LIQUEFIED FLAMMABLE GASES Design and Installation § 38.05-5 Markings—TB/ALL. (a)(1) Upon satisfactory completion of tests and inspection, pressure...

  1. 46 CFR 30.10-13 - Cofferdam-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cofferdam-TB/ALL. 30.10-13 Section 30.10-13 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-13 Cofferdam—TB/ALL. The term cofferdam means a void or empty space separating two or more compartments for...

  2. 46 CFR 35.07-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 35.07-1 Section 35.07-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Logbook Entries § 35.07-1 Application—TB/ALL. (a) Except as specifically noted, the provisions of this subpart shall apply to all...

  3. 46 CFR 30.10-3 - Approved-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Approved-TB/ALL. 30.10-3 Section 30.10-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-3 Approved—TB/ALL. The term approved means approved by the Commandant unless otherwise stated....

  4. 46 CFR 32.70-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 32.70-1 Section 32.70-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Application—TB/ALL. All steel hull tank vessels, the construction or conversion of which was started prior...

  5. 46 CFR 30.10-27 - Flashpoint-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Flashpoint-TB/ALL. 30.10-27 Section 30.10-27 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-27 Flashpoint—TB/ALL. The term flashpoint indicates the temperature in degrees Fahrenheit at which a...

  6. 46 CFR 30.10-27 - Flashpoint-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Flashpoint-TB/ALL. 30.10-27 Section 30.10-27 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-27 Flashpoint—TB/ALL. The term flashpoint indicates the temperature in degrees Fahrenheit at which a...

  7. 46 CFR 32.70-15 - Pumprooms-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Pumprooms-TB/ALL. 32.70-15 Section 32.70-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Pumprooms—TB/ALL. Tank vessels handling Grade A, B, C or D liquid cargo shall meet the requirements for...

  8. 46 CFR 32.65-15 - Cofferdams-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cofferdams-TB/ALL. 32.65-15 Section 32.65-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL..., 1951 § 32.65-15 Cofferdams—TB/ALL. Tank vessels equipped to carry Grade A, B, C, or D liquids...

  9. 46 CFR 34.01-1 - Applicability-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Applicability-TB/ALL. 34.01-1 Section 34.01-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT General § 34.01-1 Applicability—TB/ALL. (a) The provisions of this part shall apply to all tank vessels except as otherwise...

  10. 46 CFR 32.57-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 32.57-1 Section 32.57-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Application—TB/ALL. (a) The provisions of this subpart shall apply to all tank vessels contracted for on...

  11. 46 CFR 30.10-11 - Coastwise-TB/C.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Coastwise-TB/C. 30.10-11 Section 30.10-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-11 Coastwise—TB/C. Under this designation shall be included all tank vessels normally navigating the waters of...

  12. 46 CFR 30.10-49 - Permit-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Permit-TB/ALL. 30.10-49 Section 30.10-49 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-49 Permit—TB/ALL. The term permit refers to endorsement on the certificate of inspection, authorizing the...

  13. 46 CFR 31.20-1 - Waters-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Waters-TB/ALL. 31.20-1 Section 31.20-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS INSPECTION AND CERTIFICATION Waters Operated Over § 31.20-1 Waters—TB/ALL. The certificate of inspection shall show the waters over which the tank...

  14. 46 CFR 35.03-10 - Use-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Use-TB/ALL. 35.03-10 Section 35.03-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Work Vests § 35.03-10 Use—TB/ALL. (a) Approved buoyant work vests are considered to be items of safety apparel and may be carried aboard...

  15. 46 CFR 32.70-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 32.70-1 Section 32.70-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Application—TB/ALL. All steel hull tank vessels, the construction or conversion of which was started prior...

  16. 46 CFR 35.03-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 35.03-1 Section 35.03-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Work Vests § 35.03-1 Application—TB/ALL. (a) Provisions of this subpart shall apply to all tank vessels....

  17. 46 CFR 34.10-1 - Application-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Application-TB/ALL. 34.10-1 Section 34.10-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Fire Main System, Details § 34.10-1 Application—TB/ALL. (a) On all tankships the provisions of this subpart, with...

  18. 46 CFR 30.10-38 - Lightweight-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Lightweight-TB/ALL. 30.10-38 Section 30.10-38 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-38 Lightweight—TB/ALL. The term lightweight means the displacement of a vessel in metric tons without cargo,...

  19. 46 CFR 32.65-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 32.65-1 Section 32.65-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL..., 1951 § 32.65-1 Application—TB/ALL. The requirements in this subpart apply to all tank vessels,...

  20. 46 CFR 32.70-15 - Pumprooms-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Pumprooms-TB/ALL. 32.70-15 Section 32.70-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL... Pumprooms—TB/ALL. Tank vessels handling Grade A, B, C or D liquid cargo shall meet the requirements for...

  1. 46 CFR 30.10-13 - Cofferdam-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cofferdam-TB/ALL. 30.10-13 Section 30.10-13 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-13 Cofferdam—TB/ALL. The term cofferdam means a void or empty space separating two or more compartments for...

  2. 46 CFR 30.10-5 - Cargo-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cargo-TB/ALL. 30.10-5 Section 30.10-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-5 Cargo—TB/ALL. The term cargo means combustible liquid, flammable liquid, or liquefied flammable gas...

  3. 46 CFR 30.10-71 - Tankerman-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Tankerman-TB/ALL. 30.10-71 Section 30.10-71 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-71 Tankerman—TB/ALL. The following ratings are established in part 13 of this chapter. The terms for...

  4. 46 CFR 30.10-11 - Coastwise-TB/C.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Coastwise-TB/C. 30.10-11 Section 30.10-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-11 Coastwise—TB/C. Under this designation shall be included all tank vessels normally navigating the waters of...

  5. 46 CFR 32.40-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 32.40-1 Section 32.40-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Accommodations for Officers and Crew § 32.40-1 Application—TB/ALL. (a) The provisions of...

  6. 46 CFR 35.35-75 - Emergencies-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Emergencies-TB/ALL. 35.35-75 Section 35.35-75 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Cargo Handling § 35.35-75 Emergencies—TB/ALL. In case of emergencies nothing in the regulations in this subchapter shall be construed...

  7. 46 CFR 30.10-3 - Approved-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Approved-TB/ALL. 30.10-3 Section 30.10-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-3 Approved—TB/ALL. The term approved means approved by the Commandant unless otherwise stated....

  8. 46 CFR 38.05-5 - Markings-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Markings-TB/ALL. 38.05-5 Section 38.05-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS LIQUEFIED FLAMMABLE GASES Design and Installation § 38.05-5 Markings—TB/ALL. (a)(1) Upon satisfactory completion of tests and inspection, pressure...

  9. 46 CFR 35.35-75 - Emergencies-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Emergencies-TB/ALL. 35.35-75 Section 35.35-75 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Cargo Handling § 35.35-75 Emergencies—TB/ALL. In case of emergencies nothing in the regulations in this subchapter shall be construed...

  10. 46 CFR 34.30-1 - Application-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Application-TB/ALL. 34.30-1 Section 34.30-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT Automatic Sprinkler Systems, Details § 34.30-1 Application—TB/ALL. Automatic sprinkler systems shall comply with NFPA 13-1996....

  11. 46 CFR 34.01-1 - Applicability-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Applicability-TB/ALL. 34.01-1 Section 34.01-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS FIREFIGHTING EQUIPMENT General § 34.01-1 Applicability—TB/ALL. (a) The provisions of this part shall apply to all tank vessels except as otherwise...

  12. 69 FR 26606 - Community Preparation for Tuberculosis (TB) Vaccine Trials

    Federal Register 2010, 2011, 2012, 2013, 2014

    2004-05-13

    ... HUMAN SERVICES Centers for Disease Control and Prevention Community Preparation for Tuberculosis (TB..., , as amended. Purpose: The purpose of the program is for CDC to test new Tuberculosis (TB) vaccines... limited to, World Health Organization (WHO), International Union Against Tuberculosis and Lung...

  13. 46 CFR 30.10-45 - Ocean-TB/O.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Ocean-TB/O. 30.10-45 Section 30.10-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-45 Ocean—TB/O. Under this designation shall be included all tank vessels normally navigating the waters of any ocean...

  14. 46 CFR 30.10-45 - Ocean-TB/O.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Ocean-TB/O. 30.10-45 Section 30.10-45 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Definitions § 30.10-45 Ocean—TB/O. Under this designation shall be included all tank vessels normally navigating the waters of any ocean...

  15. Tank 241-ER-311, grab samples, ER311-98-1, ER311-98-2, ER311-98-3 analytical results for the final report

    SciTech Connect

    FULLER, R.K.

    1999-02-24

    This document is the final report for catch tank 241-ER-311 grab samples. Three grab samples ER311-98-1, ER311-98-2 and ER311-98-3 were taken from East riser of tank 241-ER-311 on August 4, 1998 and received by the 222-S Laboratory on August 4, 1998. Analyses were performed in accordance with the Compatibility Grab Sampling and Analysis Plan (TSAP) (Sasaki, 1998)and the Data Quality Objectives for Tank Farms Waste Compatibility Program (DQO) (Mulkey and Miller, 1997). The analytical results are presented in the data summary report (Table 1). No notification limits were exceeded.

  16. NASA ER-2: Flying Laboratory for Earth Science Studies

    NASA Technical Reports Server (NTRS)

    Navarro, Robert

    2007-01-01

    This viewgraph presentation gives an overview of the NASA ER-2 aircraft. The contents include: 1) ER-2 Specifications; 2) ER-2 Basic Configuration; 3) ER-2 Payload Areas: Nose Area; 4) ER-2 Payload Areas: SuperPod Fore and Aftbody; 5) ER-2 Payload Areas: SuperPod Midbody; 6) ER-2 Payload Areas: Q-Bay; 7) ER-2 Payload Areas: Q-Bay Hatch Designs; 8) ER-2 Payload Areas: External Pods; 9) ER-2 Electrical/Control Interface; 10) ER-2 Typical Flight Profile; 11) Tropical Composition, Cloud and Climate Coupling TC-4; 12) TC-4 Timeline; 13) TC4 Area of Interest; 14) ER-2 TC4 Payload; 15) A/C ready for fuel; 16) ER-2 Pilot being suited; 17) ER-2 Taxing; 18) ER-2 Pilot post flight debrief; and 19) NASA ER-2: Flying Laboratory for Earth Science Studies and Remote Sensing.

  17. Synthesis and characterization of Gd-doped magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Honghu; Malik, Vikash; Mallapragada, Surya; Akinc, Mufit

    2017-02-01

    Synthesis of magnetite nanoparticles has attracted increasing interest due to their importance in biomedical and technological applications. Tunable magnetic properties of magnetite nanoparticles to meet specific requirements will greatly expand the spectrum of applications. Tremendous efforts have been devoted to studying and controlling the size, shape and magnetic properties of magnetite nanoparticles. Here we investigate gadolinium (Gd) doping to influence the growth process as well as magnetic properties of magnetite nanocrystals via a simple co-precipitation method under mild conditions in aqueous media. Gd doping was found to affect the growth process leading to synthesis of controllable particle sizes under the conditions tested (0-10 at% Gd3+). Typically, undoped and 5 at% Gd-doped magnetite nanoparticles were found to have crystal sizes of about 18 and 44 nm, respectively, supported by X-ray diffraction and transmission electron microscopy. Our results showed that Gd-doped nanoparticles retained the magnetite crystal structure, with Gd3+ randomly incorporated in the crystal lattice, probably in the octahedral sites. The composition of 5 at% Gd-doped magnetite was Fe(3-x)GdxO4 (x=0.085±0.002), as determined by inductively coupled plasma mass spectrometry. 5 at% Gd-doped nanoparticles exhibited ferrimagnetic properties with small coercivity ( 65 Oe) and slightly decreased magnetization at 260 K in contrast to the undoped, superparamagnetic magnetite nanoparticles. Templation by the bacterial biomineralization protein Mms6 did not appear to affect the growth of the Gd-doped magnetite particles synthesized by this method.

  18. Mitochondria-Associated Membranes and ER Stress.

    PubMed

    van Vliet, Alexander R; Agostinis, Patrizia

    2017-03-28

    The endoplasmic reticulum (ER) is a crucial organelle for coordinating cellular Ca(2+) signaling and protein synthesis and folding. Moreover, the dynamic and complex membranous structures constituting the ER allow the formation of contact sites with other organelles and structures, including among others the mitochondria and the plasma membrane (PM). The contact sites that the ER form with mitochondria is a hot topic in research, and the nature of the so-called mitochondria-associated membranes (MAMs) is continuously evolving. The MAMs consist of a proteinaceous tether that physically connects the ER with mitochondria. The MAMs harness the main functions of both organelles to form a specialized subcompartment at the interface of the ER and mitochondria. Under homeostatic conditions, MAMs are crucial for the efficient transfer of Ca(2+) from the ER to mitochondria, and for proper mitochondria bioenergetics and lipid synthesis. MAMs are also believed to be the master regulators of mitochondrial shape and motility, and to form a crucial site for autophagosome assembly. Not surprisingly, MAMs have been shown to be a hot spot for the transfer of stress signals from the ER to mitochondria, most notably under the conditions of loss of ER proteostasis, by engaging the unfolded protein response (UPR). In this chapter after an introduction on ER biology and ER stress, we will review the emerging and key signaling roles of the MAMs, which have a root in cellular processes and signaling cascades coordinated by the ER.

  19. ER stress-induced cell death mechanisms

    PubMed Central

    Sano, Renata; Reed, John C.

    2013-01-01

    The endoplasmic-reticulum (ER) stress response constitutes a cellular process that is triggered by a variety of conditions that disturb folding of proteins in the ER. Eukaryotic cells have developed an evolutionarily conserved adaptive mechanism, the unfolded protein response (UPR), which aims to clear unfolded proteins and restore ER homeostasis. In cases where ER stress cannot be reversed, cellular functions deteriorate, often leading to cell death. Accumulating evidence implicates ER stress-induced cellular dysfunction and cell death as major contributors to many diseases, making modulators of ER stress pathways potentially attractive targets for therapeutics discovery. Here, we summarize recent advances in understanding the diversity of molecular mechanisms that govern ER stress signaling in health and disease. PMID:23850759

  20. Electron microscopy of a Gd-Ba-Cu-O superconductor

    NASA Technical Reports Server (NTRS)

    Ramesh, R.; Thomas, G.; Meng, R. L.; Hor, P. H.; Chu, C. W.

    1989-01-01

    An electron microscopy study has been carried out to characterize the microstructure of a sintered Gd-Ba-Cu-O superconductor alloy. The GdBa2Cu3O(7-x) phase in the oxygen annealed sample is orthorhombic, while in the vacuum annealed sample it is tetragonal. It is shown that the details of the fine structure in the 001-line zone axis convergent beam patterns can be used to distinguish between the orthorhombic form and the tetragonal form. In addition to this matrix phase, an amorphous phase is frequently observed at the triple grain junctions. Gd-rich inclusions have been observed inside the matrix phase.

  1. Hydrogenation induced structure and property changes in GdGa

    NASA Astrophysics Data System (ADS)

    Nedumkandathil, Reji; Kranak, Verina F.; Johansson, Robert; Ångström, Jonas; Balmes, Oliver; Andersson, Mikael S.; Nordblad, Per; Scheicher, Ralph H.; Sahlberg, Martin; Häussermann, Ulrich

    2016-07-01

    Hydrides GdGaHx were obtained by exposing the Zintl phase GdGa with the CrB structure to a hydrogen atmosphere at pressures from 1.5 to 50 bar and temperatures from 50 to 500 °C. Structural analysis by powder X-ray diffraction suggests that conditions with hydrogen pressures in a range between 15 and 50 bar and temperatures below 500 °C afford a uniform hydride phase with the NdGaH1.66 structure (Cmcm, a=3.9867(7) Å, b=12.024(2) Å, c=4.1009(6) Å) which hosts H in two distinct positions, H1 and H2. H1 is coordinated in a tetrahedral fashion by Gd atoms, whereas H2 atoms are inserted between Ga atoms. The assignment of the NdGaH1.66 structure is corroborated by first principles DFT calculations. Modeling of phase and structure stability as a function of composition resulted in excellent agreement with experimental lattice parameters when x=1.66 and revealed the presence of five-atom moieties Ga-H2-Ga-H2-Ga in GdGaH1.66. From in situ powder X-ray diffraction using synchrotron radiation it was established that hydrogenation at temperatures above 200 °C affords a hydride with x≈1.3, which is stable up to 500 °C, and that additional H absorption, yielding GdGaH1.66, takes place at lower temperatures. Consequently, GdGaH1.66 desorbs H above T=200 °C. Without the presence of hydrogen, hydrides GdGaHx decompose at temperatures above 300 °C into GdH2 and an unidentified Gd-Ga intermetallics. Thus the hydrogenation of GdGa is not reversible. From magnetic measurements the Curie-Weiss constant and effective magnetic moment of GdGaH1.66 were obtained. The former indicates antiferromagnetic interactions, the latter attains a value of 8 μB which is typical for compounds containing Gd3+ions.

  2. Ternary germanides RERhGe2 (RE = Y, Gd-Ho) - New representatives of the YIrGe2 type

    NASA Astrophysics Data System (ADS)

    Voßwinkel, Daniel; Heletta, Lukas; Hoffmann, Rolf-Dieter; Pöttgen, Rainer

    2016-11-01

    The YIrGe2 type ternary germanides RERhGe2 (RE = Y, Gd-Ho) were synthesized from the elements by arc-melting and characterized by powder X-ray diffraction. The structure of DyRhGe2 was refined from single crystal X-ray diffractometer data: Immm, a = 426.49(9), b = 885.0(2), c = 1577.4(3) pm, wR2 = 0.0533, 637 F2 values, 30 variables (300 K data). The structure contains two crystallographically independent dysprosium atoms in pentagonal prismatic and hexagonal prismatic coordination. The three-dimensional [RhGe2] polyanion is stabilized through covalent Rh-Ge (243-261 pm) and Ge-Ge (245-251 pm) bonding. The close structural relationship with the slightly rhodium-poorer germanides RE5Rh4Ge10 (≡ RERh0.8Ge2) is discussed. Temperature-dependent magnetic susceptibility measurements reveal Pauli paramagnetism for YRhGe2 and Curie-Weiss paramagnetism for RERhGe2 with RE = Gd, Tb, Dy and Ho. These germanides order antiferromagnetically at TN = 7.2(5), 10.6(5), 8.1(5), and 6.4(5) K, respectively.

  3. All-in-one optical heater-thermometer nanoplatform operative from 300 to 2000 k based on Er(3+) emission and blackbody radiation.

    PubMed

    Debasu, Mengistie L; Ananias, Duarte; Pastoriza-Santos, Isabel; Liz-Marzán, Luis M; Rocha, J; Carlos, Luís D

    2013-09-20

    A single nanoplatform integrating laser-induced heat generation by gold nanoparticles and temperature sensing up to 2000 K via (Gd,Yb,Er)2 O3 nanorods is demonstrated, which presents considerable potential for nanoscale photonics and biomedicine. Blackbody emission is ascertained from the temperature increment with AuNP concentration, emission color coordinates as a function of the laser pump power, and Planck's law of blackbody radiation.

  4. Cross section measurement of the 159Tb(n, γ)Tb160 nuclear reaction

    NASA Astrophysics Data System (ADS)

    Dzysiuk, N.; Kadenko, I.; Gressier, V.; Koning, A. J.

    2015-04-01

    The cross section of the 159Tb(n, γ)Tb160 reaction was measured in four mono-energetic neutron fields of energy 3.7, 4.3, 5.4, and 6.85 MeV, respectively, with the activation technique applied to metal discs of natural composition. To ensure an acceptable precision of the results all major sources of uncertainties were taken into account. Calculations of detector efficiency, incident neutron spectrum and correction factors were performed with the Monte Carlo code (MCNPX), whereas theoretical excitation functions were calculated with the TALYS-1.2 code and compared to the experimental cross section values. This paper presents both measurements and calculation leading to the cross section values.

  5. Air Travel and TB: an airline perspective.

    PubMed

    Dowdall, Nigel P; Evans, Anthony D; Thibeault, Claude

    2010-03-01

    The commercial airline industry in the 21st century is a global business, able to transport large numbers of people to almost any part of the world within a few hours. There has long been concern in public health circles about the potential for transmission of communicable diseases, such as TB, on board aircraft. The recent threats from novel and emerging infectious diseases including SARS and pandemic flu has facilitated unprecedented levels of cooperation between international industry representatives, regulators and public health authorities in addressing the issues of air travel and communicable disease. This paper reviews the regulatory environment, ways in which the risks are mitigated through aspects of aircraft design, opportunities for prevention by identifying individuals who may be suffering from a communicable disease prior to flight and the approach used in managing suspected cases of communicable disease on board aircraft.

  6. Microstructure and rolling capability of modified AZ31-Ce-Gd alloys

    SciTech Connect

    Li Wenping; Zhou Hong; Lin Pengyu; Zhao Shizhe

    2009-11-15

    AZ31-Ce-Gd alloys were studied and the influence of cerium (Ce) and gadolinium (Gd) on the microstructure and rolling capability of AZ31 alloy was investigated. The results indicated that the grains of AZ31 alloy were refined with Ce and Gd addition. Ce and Gd addition resulted in the formation of Al{sub 4}Ce, Al{sub 2}Gd and Mg{sub 3}Gd. After homogenization and rolling, the Al{sub 4}Ce, Al{sub 2}Gd and Mg{sub 3}Gd still existed. The rolling capability of AZ31 alloy was improved obviously with Ce and Gd addition. However, once Gd content increased to a certain value, the rolling capability of the modified alloy declined but still better than that of AZ31 alloy.

  7. {beta}-decay half-lives of new neutron-rich rare-earth isotopes {sup 159}Pm,{sup 162}Sm, and {sup 166}Gd

    SciTech Connect

    Ichikawa, S.; Asai, M.; Tsukada, K.; Nagame, Y.; Haba, H.; Shibata, M.; Sakama, M.; Kojima, Y.

    2005-06-01

    The new neutron-rich rare-earth isotopes {sup 159}Pm, {sup 162}Sm, and {sup 166}Gd produced in the proton-induced fission of {sup 238}U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of {sup 159}Pm, {sup 162}Sm, and {sup 166}Gd were determined to be 1.5 {+-} 0.2, 2.4 {+-} 0.5, and 4.8 {+-} 1.0 s respectively. The partial decay scheme of {sup 166}Gd was constructed from {gamma}{gamma}-coincidence data. A more accurate half-life value of 25.6 {+-} 2.2 s was obtained for the previously identified isotope {sup 166}Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by Audi and Wapstra.

  8. Enhanced UVB emission and analysis of chemical states of Ca5(PO4)3OH:Gd3+,Pr3+ phosphor prepared by co-precipitation

    NASA Astrophysics Data System (ADS)

    Mokoena, P. P.; Nagpure, I. M.; Kumar, Vinay; Kroon, R. E.; Olivier, E. J.; Neethling, J. H.; Swart, H. C.; Ntwaeaborwa, O. M.

    2014-08-01

    Hydroxyapatite (Ca5(PO4)3OH) is a well-known bioceramic material used in medical applications because of its ability to form direct chemical bonds with living tissues. This mineral is currently used as a host for rare-earth ions (e.g. Gd3+, Pr3+, Tb3+, etc.) to prepare phosphors that can be used in light emitting devices of different types. In this study Ca5(PO4)3OH:Gd3+,Pr3+ phosphors were prepared by the co-precipitation method and were characterised by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and photoluminescence spectroscopy. The x-ray diffraction pattern was consistent with the hexagonal phase of Ca5(PO4)3OH referenced in JCPDS card number 73-0293. The x-ray photoelectron spectroscopy data indicated that Ca2+ occupied two different lattice sites, referred to as Ca1 and Ca2. The photoluminescence data exhibited a narrowband emission located at 313 nm, which is associated with the 6P7/2→8S7/2 transition of the Gd3+ ion. This emission is classified as ultraviolet B and it is suitable for use in phototherapy lamps to treat various skin diseases. The photoluminescence intensity of the 313 nm emission was enhanced considerably by Pr3+ co-doping.

  9. Enhanced upconversion multicolor and white light luminescence in SiO2-coated lanthanide-doped GdVO4 hydrothermal nanocrystals

    NASA Astrophysics Data System (ADS)

    Calderón-Villajos, Rocío; Zaldo, Carlos; Cascales, Concepción

    2012-12-01

    Tetragonal zircon-type codoped Yb, Ln-GdVO4 (Ln=Tm, Ho, Er) upconverting nanocrystals with square and rectangular sections were prepared through an efficient low-temperature hydrothermal synthesis. Further processing that combined annealing at 600 °C followed by coating of the surface with a uniform 5 nm-shell of SiO2 resulted in a significant improvement of the intensity of the upconverted emitted visible light following near-infrared (˜980 nm) diode laser excitation with respect to raw hydrothermal nanocrystals. Strong tunable color and bright visible light composed of red-green, blue and green emissions from Ho3+, Tm3+ and Er3+, respectively, were generated by adjusting the Yb-Ln composition of these silica-coated nanocrystals. Based on calculations of CIE color coordinates, nearly ideal white upconversion light was achieved for samples of composition Gd0.829Yb0.15Tm0.01Ho0.009Er0.002VO4.

  10. First use of bedaquiline in a patient with XDR-TB in Singapore.

    PubMed

    Chua, Angeline Poh-Gek; Hoo, Grace Si-Ru; Chee, Cynthia Bin-Eng; Wang, Yee Tang

    2015-09-23

    Drug-resistant tuberculosis (TB) continues to pose a threat to global control of TB: 3.5% of new and 20.5% of previously treated TB cases were estimated to have multidrug-resistant (MDR)-TB in 2013. Approximately 9% of patients with MDR-TB had extensively drug-resistant (XDR)-TB. A 30-year-old Vietnamese woman previously treated for TB in her home country presented with 5 months of cough and shortness of breath 1 year after migrating to Singapore. Xpert MTB/Rif testing showed rpoB gene mutation. Phenotypic drug susceptibility testing revealed XDR-TB. Second and third-line TB drugs were commenced. To strengthen the efficacy of her treatment regimen, the novel anti-TB drug bedaquiline was obtained for the patient on compassionate grounds. We report the first use in Singapore of bedaquiline for the treatment of XDR-TB.

  11. Evidence for the involvement of lipid rafts localized at the ER-mitochondria associated membranes in autophagosome formation.

    PubMed

    Garofalo, Tina; Matarrese, Paola; Manganelli, Valeria; Marconi, Matteo; Tinari, Antonella; Gambardella, Lucrezia; Faggioni, Alberto; Misasi, Roberta; Sorice, Maurizio; Malorni, Walter

    2016-06-02

    Mitochondria-associated membranes (MAMs) are subdomains of the endoplasmic reticulum (ER) that interact with mitochondria. This membrane scrambling between ER and mitochondria appears to play a critical role in the earliest steps of autophagy. Recently, lipid microdomains, i.e. lipid rafts, have been identified as further actors of the autophagic process. In the present work, a series of biochemical and molecular analyses has been carried out in human fibroblasts with the specific aim of characterizing lipid rafts in MAMs and to decipher their possible implication in the autophagosome formation. In fact, the presence of lipid microdomains in MAMs has been detected and, in these structures, a molecular interaction of the ganglioside GD3, a paradigmatic "brick" of lipid rafts, with core-initiator proteins of autophagy, such as AMBRA1 and WIPI1, was revealed. This association seems thus to take place in the early phases of autophagic process in which MAMs have been hypothesized to play a key role. The functional activity of GD3 was suggested by the experiments carried out by knocking down ST8SIA1 gene expression, i.e., the synthase that leads to the ganglioside formation. This experimental condition results in fact in the impairment of the ER-mitochondria crosstalk and the subsequent hindering of autophagosome nucleation. We thus hypothesize that MAM raft-like microdomains could be pivotal in the initial organelle scrambling activity that finally leads to the formation of autophagosome.

  12. Electronic structure of Gd-doped MgO

    NASA Astrophysics Data System (ADS)

    Lukoyanov, A. V.; Anisimov, V. I.

    2016-02-01

    The electronic structure of Gd-doped MgO is investigated using the LSDA+U (local spin density approximation with U-correction) method and compared with the MgO structure. The total density of states obtained accounting for the correlation effects in the 4 f shell of gadolinium is found to be formed by the oxygen 2 p states at the valence band and the 4 f gadolinium occupied states, while the conduction band is represented by a mixture of empty electronic states. Magnetic properties of the calculated Gd-doped MgO are found to be formed solely by the Gd-4 f-magnetic moment of about 7μB, in good agreement with recent experimental results suggesting a ferromagnetic coupling of the local magnetic moments induced by Gd.

  13. Scissors mode of Gd nuclei studied from resonance neutron capture

    SciTech Connect

    Kroll, J.; Baramsai, B.; Becker, J. A.; and others

    2012-10-20

    Spectra of {gamma} rays following the neutron capture at isolated resonances of stable Gd nuclei were measured. The objectives were to get new information on photon strength of {sup 153,155-159}Gd with emphasis on the role of the M1 scissors-mode vibration. An analysis of the data obtained clearly indicates that the scissors mode is coupled not only to the ground state, but also to all excited levels of the nuclei studied. The specificity of our approach ensures unbiasedness in estimating the sumed scissors-mode strength {Sigma}B(M1){up_arrow}, even for odd product nuclei, for which conventional nuclear resonance fluorescence measurements yield only limited information. Our analysis indicates that for these nuclei the sum {Sigma}B(M1){up_arrow} increases with A and for {sup 157,159}Gd it is significantly higher compared to {sup 156,158}Gd.

  14. New drugs and regimens for treatment of TB

    PubMed Central

    Leibert, Eric; Rom, William N

    2013-01-01

    Tools for effective TB control have been available for years. Case finding, active medications, case management and directly observed therapy are the foundations for the management of TB. The current TB epidemic, centered in resource-limited settings is fueled by the HIV-1 epidemic. Lack of ability to diagnose and treat drug-resistant TB has led to development of more extensive patterns of resistance. Among the currently available drugs, there is reason to hope that rifamycins paired with fluoroquinolones will lead to shorter treatment regimens for drug-susceptible TB. As the result of novel public-private collaborations and investments of resources, new drugs are being developed. These include TMC207, already shown to have activity early in the treatment of multidrug-resistant TB and others that are likely to be active against persistor organisms, and have the prospect to dramatically shorten treatment courses for active and latent TB. Given that these drugs have novel mechanisms of action, combinations have the prospect to be highly active even against multidrug-resistant organisms. PMID:20586565

  15. Predictors of Prolonged TB Treatment in a Dutch Outpatient Setting

    PubMed Central

    Daskapan, Alper; Kosterink, Jos G. W.; van der Werf, Tjip S.; van den Hof, Susan; Alffenaar, Jan-Willem C.

    2016-01-01

    Introduction Standard treatment duration for drug-susceptible tuberculosis (TB) treatment is 6 months. Treatment duration is often extended—and for various different reasons. The aim of this study was to determine the prevalence and to assess risk factors associated with extended TB treatment. Methods A cross-sectional study was conducted. Data including demographic, clinical, radiological and microbiological information from the Netherlands TB Register (NTR) of 90 patients with smear and culture positive pulmonary TB of the region Haaglanden, The Netherlands, was eligible for analysis. Results Treatment was extended to ≥ 200 days by 46 (51%) patients. Extended TB treatment was associated with a higher frequency of symptoms, presumed to be due to adverse drug reactions (ADR; OR 2.39 95% CI: 1.01–5.69), drug-induced liver injury (DILI) (OR: 13.51; 95% CI: 1.66–109.82) and longer than 2 month smear and culture conversion rate (OR: 11.00; 95% CI: 1.24–97.96 and OR: 8.56; 95% CI: 1.53–47.96). In the multivariable logistic analysis, development of DILI emerged as the single statistically strong risk factor necessitating extension of TB treatment. Conclusion This finding will need further confirmation in a prospective study, exploring the possible mutual role of pharmacokinetic and pharmacogenetic determinants of DILI among TB patients. PMID:27832142

  16. [Tuberculosis annual report 2008--series 2. TB in foreigners].

    PubMed

    2009-11-01

    Statistics on tuberculosis (TB) in foreigners have been obtained since 1998 in Japan. The number of foreign TB patients increased from 739 in 1998 to 945 in 2008. In contrast, the number of Japanese TB patients decreased during this period and hence the proportion of foreign TB patients increased from 2.1% in 1998 to 3.9% in 2008, excluding those of unknown nationality. Especially, the proportion of those aged 20-29 years increased greatly from 9.1% in 1998 to 26.3% in 2008. Although the number of nationalities was 47, the majority of patients were from China (27.7%), the Philippines (24.8%) and Korea (10.2%) in 2008. The number of foreign TB patients aged 20-29 years was 468, accounting for 49.5% of all foreign TB patients in 2008. Seventy-seven percent of foreign patients aged 20-29 years had developed TB within 5 years of entering Japan. The equivalent proportion was 49% of those aged 30-39 years and 32% of those aged 40-49 years. Regarding occupation, 39.7% of foreign patients aged 20-29 years were full-time workers, 28.6% were students and 13.7% were part-time workers.

  17. Electronic state of Er in sputtered AlN:Er films determined by magnetic measurements

    SciTech Connect

    Narang, V.; Seehra, M. S.; Korakakis, D.

    2014-12-07

    The optoelectronic and piezoelectric properties of AlN:Er thin films have been of great recent interest for potential device applications. In this work, the focus is on the electronic state of Er in AlN:Er thin films prepared by reactive magnetron sputtering on (001) p-type Si substrate. X-ray diffraction shows that Er doping expands the lattice and the AlN:Er film has preferential c-plane orientation. To determine whether Er in AlN:Er is present as Er metal, Er{sub 2}O{sub 3}, or Er{sup 3+} substituting for Al{sup 3+}, detailed measurements and analysis of the temperature dependence (2 K–300 K) of the magnetization M at a fixed magnetic field H along with the M vs. H data at 2 K up to H = 90 kOe are presented. The presence of Er{sub 2}O{sub 3} and Er metal is ruled out since their characteristic magnetic transitions are not observed in the AlN:Er sample. Instead, the observed M vs. T and M vs. H variations are consistent with Er present as Er{sup 3+} substituting for Al{sup 3+} in AlN:Er at a concentration x = 1.08% in agreement with x = 0.94% ± 0.20% determined using x-ray photoelectron spectroscopy (XPS). The larger size of Er{sup 3+} vs. Al{sup 3+}explains the observed lattice expansion of AlN:Er.

  18. A second ferroelectric transition induced by pressure in multiferroic GdMn2O5

    NASA Astrophysics Data System (ADS)

    Lorenz, Bernd; Poudel, Narayan; Gooch, Melissa; Chu, Ching-Wu; Cheong, Sang-Wook

    2015-03-01

    In multiferroic materials different magnetic and ferroelectric states compete for the ground state and are usually close in energy. This results in a high sensitivity of the multiferroic state to external perturbations, such as magnetic fields or pressure, which has been demonstrated, e.g. in Ni3V2O8,MnWO4,andRMn2O5 (R = Tb, Ho, Dy, Y). Here we report the results of a high-pressure study of the multiferroic and ferroelectric properties of GdMn2O5,theRMn2O5 compound with the highest value of the polarization. The ferroelectric polarization below 29 K is enhanced upon application of pressure. Above a critical pressure, a second ferroelectric transition at even higher temperature is detected through a sizable increase of the polarization and a second peak of the dielectric constant. The ferroelectric polarization at high pressures exhibits two step-like increases upon decreasing temperature. This work was supported by the US AFOSR, the T.L.L. Temple Foundation, the John J. and Rebecca Moores Endowment, and the State of Texas through TCSUH.

  19. Evaluation of hypothetical 153Gd source for use in brachytherapy☆

    PubMed Central

    Ghorbani, Mahdi; Behmadi, Marziyeh

    2016-01-01

    Aim The purpose of this work is to evaluate the dosimetric parameters of a hypothetical 153Gd source for use in brachytherapy and comparison of the dosimetric parameters with those of 192Ir and 125I sources. Materials and methods Dose rate constant, the radial dose function and the two dimensional (2D) anisotropy function data for the hypothetical 153Gd source were obtained by simulation of the source using MCNPX code and then were compared with the corresponding data reported by Enger et al. A comprehensive comparison between this hypothetical source and a 192Ir source with similar geometry and a 125I source was performed as well. Results Excellent agreement was shown between the results of the two studies. Dose rate constant values for the hypothetical 153Gd, 192Ir, 125I sources are 1.173 cGyh−1 U−1, 1.044 cGyh−1 U−1, 0.925 cGyh−1 U−1, respectively. Radial dose function for the hypothetical 153Gd source has an increasing trend, while 192Ir has more uniform and 125I has more rapidly falling off radial dose functions. 2D anisotropy functions for these three sources indicate that, except at 0.5 cm distance, 192Ir and 125I have more isotropic trends as compared to the 153Gd source. Conclusion A more uniform radial dose function, and 2D anisotropy functions with more isotropy, a much higher specific activity are advantages of 192Ir source over 153Gd. However, a longer half-life of 153Gd source compared to the other two sources, and lower energy of the source with respect to 192Ir are advantages of using 153Gd in brachytherapy versus 192Ir source. PMID:26900353

  20. Magnetic anisotropy and spin reorientation effects in Gd/Fe and Gd/(FeCo) multilayers for high density magneto-optical recording

    NASA Astrophysics Data System (ADS)

    Stavrou, E.; Sbiaa, R.; Suzuki, T.; Knappmann, S.; Röll, K.

    2000-05-01

    We have investigated the anisotropy behavior and temperature dependent changes of the magnetic anisotropy in Gd/Fe and Gd/(FeCo) multilayers. The spin reorientation effects are very important for the super resolution readout in new methods for high-density magneto-optical recording. Gd/(Fe, Co) multilayered films are a good alternative to the common Gd(Fe, Co) alloy films, because the magnetic anisotropy and also spin reorientation effects can be comfortably adjusted by varying the interface and volume anisotropy components and the composition using experimental parameters such as the periodicity λ=tGd+tTM [tGd,tTM: the sublayer thicknesses of the Gd and transition metal Fe, FeCo (TM)] and the ratio of the sublayer thicknesses tGd/tTM. We have found the mechanisms for spin reorientation, which are explained qualitatively with a new model.

  1. Direct Measurement of |V{sub tb}| at CDF

    SciTech Connect

    Tartarelli, G.F.

    1997-12-01

    We present a first direct measurement of the ratio of branching fractions R = B(t{r_arrow}Wb)/B(t{r_arrow}Wq), obtained by the CDF Collaboration. We measure R = 0.99 {+-} 0.29(stat+syst) in agreement with the Standard Model predictions. We use this result to measure the element |V{sub tb}| of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. We obtain |V{sub tb}| = 0.99 {+-} 0.15(stat+syst) which translates in the 90% confidence limit |V{sub tb}| {>=} 0.8. 3 refs., 1 fig., 1 tab.

  2. Direct measurement of interlayer interaction in Permalloy/Gd nanodots

    NASA Astrophysics Data System (ADS)

    Lapa, Pavel; Ding, Junjia; Novosad, Valentine; Hoffmann, Axel

    2015-03-01

    Antiferromagnetic interaction at the interfaces of ferromagnetic transition metals(TM) and Gd is well known phenomenon. However, quantitative description of this interaction still lacks understanding. The main reason is that most experimental data were obtained by inspecting the hysteresis loops of TM/Gd multilayers. First, in plane domain structures of TM and Gd films complicates the description of the magnetization reversal process. Second, experimentally measured parameters are averaged over the domains obfuscating the microscopical picture. We make an effort to overcome these limitations by studying the magnetization reversal process of Permalloy/Gd nanodots. The dots were prepared by combination of optical lithography and magnetron sputtering. Experimentally it is observed that in these dots the antiferromagnetic interlayer interaction tunes magnetic vortex nucleation/annihilation fields. Rise of Gd magnetization at low temperature provides unusual temperature behavior of hysteresis loop. Micromagnetic models in which interlayer interaction energy acts as a fitting parameter is applied to simulate experimental hysteresis curves. The effect of nonmagnetic spacer between Permalloy and Gd is also considered and will be presented. This work was supported by the Department of Energy Office of Science, Materials Science and Engineering Division.

  3. Endoplasmic reticulum: ER stress regulates mitochondrial bioenergetics

    PubMed Central

    Bravo, Roberto; Gutierrez, Tomás; Paredes, Felipe; Gatica, Damián; Rodriguez, Andrea E.; Pedrozo, Zully; Chiong, Mario; Parra, Valentina; Quest, Andrew F.G.; Rothermel, Beverly A.; Lavandero, Sergio

    2014-01-01

    Endoplasmic reticulum (ER) stress activates an adaptive unfolded protein response (UPR) that facilitates cellular repair, however, under prolonged ER stress, the UPR can ultimately trigger apoptosis thereby terminating damaged cells. The molecular mechanisms responsible for execution of the cell death program are relatively well characterized, but the metabolic events taking place during the adaptive phase of ER stress remain largely undefined. Here we discuss emerging evidence regarding the metabolic changes that occur during the onset of ER stress and how ER influences mitochondrial function through mechanisms involving calcium transfer, thereby facilitating cellular adaptation. Finally, we highlight how dysregulation of ER–mitochondrial calcium homeostasis during prolonged ER stress is emerging as a novel mechanism implicated in the onset of metabolic disorders. PMID:22064245

  4. Visible-light driven Gd2Ti2O7/GdCrO3 composite for hydrogen evolution.

    PubMed

    Parida, K M; Nashim, Amtul; Mahanta, Saroj Ku

    2011-12-28

    A series of Gd(2)Ti(2)O(7)/GdCrO(3) composites are prepared by solid state combustion method using Gd(NO(3))(3), TiO(2), Cr(2)O(3) as metal source and urea as a fuel. The composites are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible diffuse reflectance spectra (DRUV-vis), Brunauer-Emmett-Teller (BET) surface area measurements, photoluminescence spectra (PL), X-ray photoelectron spectroscopic (XPS) studies, photocurrent measurements etc. The photocatalytic activity of the composites is examined towards hydrogen production without using any co-catalyst under visible light illumination. The rate of formation of hydrogen is measured by the photocatalytic activity measurement device and gas chromatography (GC). The highest efficiency is observed over the composite GTC (Cr:Gd:Ti = 1:1:1). On the basis of photocurrent measurements and PL, a mechanism for the enhanced photocatalytic activity has been discussed.

  5. The Exchange Coupling of Gd3+- and Cr3+-Ions in Paramagnetic GdCrO3 (In German)

    NASA Astrophysics Data System (ADS)

    Dräger, K.

    1986-03-01

    Polycrystalline samples of stoichiometric GdCrO3 have been investigated by ESR at 9.4 GHz. In the temperature range between 175 K and 520 K one broad absorption with a Lorentzian line shape and a g-factor of 2.024 has been observed. Attributing the absorption exclusively to the Gd -ion it can be shown that the temperature dependence of the ESR-intensity follows the predictions of a cluster-model. The energy describing the coupling of a single Gd3+-ion to the surrounding Cr3+-ions is found to be ΔE(Gd) = 170 cm-1. Taking advantage of the similarity within the orthochromites it is possible to determine at the same time the exchange - coupling of Cr3+-ions to their identical nearest neighbours as ΔE(Cr) = 293 cm-1. The relative strength of these couplings given by 0.60 is compatible with other experimental issues.

  6. Microlasers autodoubleurs en Nd:GdCOB

    NASA Astrophysics Data System (ADS)

    Lucas-Leclin, G.; Lombard, L.; Balembois, F.; Georges, P.; Brun, A.; Marty, J.; Ferrand, B.; Calvat, C.; François, B.; Rolland, G.; Pelenc, D.; Aka, G.; Vivien, D.; Pacaud, O.; Maillart, J. M.

    2002-06-01

    Nous avons réalisé des microlasers pompés par diode à émission dans le visible, à partir d'un matériau autodoubleur (Nd:GdCOB) qui possède simultanément des propriétés laser et non linéaires. La fabrication de ces microlasers nécessite une orientation fine des faces des cristaux perpendiculairement à la direction d'accord de phase, avec une précision de t 0,1°. Des miroirs diéléctriques sont déposés sur chaque face. Cette technologie assure une fabrication collective de faible coût. En pompage par diode, une puissance de 21 mW à 530 nm a été atteinte pour une puissance de pompe incidente à 812 nm de 1,4 W. Pour une puissance de pompe réduite de 0,7 W, la puissance émise dans le vert atteint 3 mW, et le profil spatial reste monomode transverse. Ces résultats encourageants sont une nouvelle étape vers la réalisation de sources visibles compactes et bas coût.

  7. Delay in commencing treatment for MDR TB at a specialised TB treatment centre in KwaZulu-Natal.

    PubMed

    Narasimooloo, R; Ross, A

    2012-05-08

    Background. According to the National Department of Health (NDoH) guidelines, patients diagnosed with MDR TB must be referred to a specialised treatment centre for initiation of effective therapy. MDR TB is difficult to diagnose and the centralised referral model is beset with challenges that contribute to treatment delays, increased patient morbidity and mortality, and MDR TB nosocomial transmission. Culture and DST takes 8 weeks or longer to obtain results while line probe assays (LPAs) can give a result in hours. LPAs and the GeneXpert MTB/Rif (GX) are ground-breaking discoveries for TB diagnosis. However, they are not easily accessible or available to those needing it, so culture and sensitivity testing remains the gold standard for diagnosis. Aim. This study aimed to assess the delay in the initiation of MDR TB treatment and profiled the patients being referred to a specialised drug-resistant treatment centre in KwaZulu-Natal. Results. Of all the patients, 75% referred showed a mean delay of 12.4 weeks from the date of sputum collection for culture and drug sensitivity testing to the start of treatment. Most of the patients were symptomatic for TB and HIV-positive. Discussion. Our findings suggest that current policy on the initiation of effective treatment needs urgent revision. Staff should be appropriately trained in LPA and GX technology to reduce delays in initiating treatment for MDR TB. The NDoH's plans for rapid diagnosis and reducing the treatment burden on centralised MDR TB management facilities are in the early phases of implementation and will take years to achieve favourable and significant outcomes. Conclusion. There is a significant delay in initiating definitive management for MDR TB.

  8. Comparison of dentin root canal permeability and morphology after irradiation with Nd:YAG, Er:YAG, and diode lasers.

    PubMed

    Esteves-Oliveira, Marcella; de Guglielmi, Camila A B; Ramalho, Karen Müller; Arana-Chavez, Victor E; de Eduardo, Carlos Paula

    2010-09-01

    The aim of this study was to compare the effects of Nd:YAG, Er:YAG, and diode lasers on the morphology and permeability of root canal walls. The three laser wavelengths mentioned interact differently with dentin and therefore it is possible that the permeability changes caused will determine different indications during endodontic treatment. Twenty-eight human single-rooted teeth were instrumented up to ISO 40 and divided into four groups: group C, control (GC), non-laser irradiated; group N (GN), irradiated with Nd:YAG laser; group E (GE), with Er:YAG laser and group D (GD) with diode laser. After that, the roots were filled with a 2% methylene blue dye, divided into two halves and then photographed. The images were analyzed using Image J software and the percentage of dye penetration in the cervical, middle, and apical root thirds were calculated. Additional scanning electron microscopy (SEM) analyses were also performed. The analysis of variance (ANOVA) showed significant permeability differences between all groups in the middle and cervical thirds (p < 0.05). The Tukey test showed that in the cervical third, GN presented means of dye penetration statistically significantly lower than all of the other groups. In the middle third, GE and GD showed statistically higher dye penetration means than GC and GN. SEM analysis showed melted surfaces for GN, clean wall surfaces with open dentinal tubules for GE, and mostly obliterated dentinal tubules for GD. Er:YAG (2,094 nm) laser and diode laser (808 nm) root canal irradiation increase dentinal permeability and Nd:YAG (1,064 nm) laser decreases dentin permeability, within the studied parameters.

  9. Crystal field states of Tb3 + in the pyrochlore spin liquid Tb2Ti2O7 from neutron spectroscopy

    NASA Astrophysics Data System (ADS)

    Princep, A. J.; Walker, H. C.; Adroja, D. T.; Prabhakaran, D.; Boothroyd, A. T.

    2015-06-01

    We report time-of-flight neutron scattering measurements of the magnetic spectrum of Tb3 + in Tb2Ti2O7 . The data, which extend up to 120 meV and have calibrated intensity, enable us to consolidate and extend previous studies of the single-ion crystal field spectrum. We successfully refine a model for the crystal field potential in Tb2Ti2O7 without relying on data from other rare-earth titanate pyrochlores, and we confirm that the ground state is a non-Kramers doublet with predominantly |±4 > components. We compare the model critically with earlier models.

  10. Drug-resistant TB: deadly, costly and in need of a vaccine.

    PubMed

    Manjelievskaia, Janna; Erck, Dara; Piracha, Samina; Schrager, Lewis

    2016-03-01

    TB is an underappreciated public health threat in developed nations. In 2014, an estimated 9.6 million TB cases and 1.5 million deaths occurred worldwide; 3.3% of these cases resulted from multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) strains. These figures underestimate the economic burden associated with MDR-TB and XDR-TB, as the cost of treating disease caused by these strains can be 9-25 times higher than treating drug-susceptible TB. Developing new drugs, improved diagnostics and new TB vaccines are critical components of a strategy to combat TB in general, and drug-resistant TB in particular. Because Mycobacterium tuberculosis (MTB) has demonstrated a capacity to develop resistance to drugs developed to combat it, it is unlikely that drug-resistant MTB would be 'resistant' to vaccines capable of preventing disease or established infection with drug-sensitive MTB strains. Accordingly, the development of TB vaccines represents an important long-term investment in preventing the spread of drug-resistant TB and achieving WHO's goal of ending the global TB epidemic by 2035. Our current understanding of the epidemiology of drug-resistant TB and the interventions needed to limit its spread, reviewed in this article, illustrates the need for increased financial support for developing new TB drugs, diagnostics and vaccines to meet the WHO goal of TB elimination by 2035.

  11. Drug-resistant TB: deadly, costly and in need of a vaccine

    PubMed Central

    Manjelievskaia, Janna; Erck, Dara; Piracha, Samina; Schrager, Lewis

    2016-01-01

    TB is an underappreciated public health threat in developed nations. In 2014, an estimated 9.6 million TB cases and 1.5 million deaths occurred worldwide; 3.3% of these cases resulted from multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) strains. These figures underestimate the economic burden associated with MDR-TB and XDR-TB, as the cost of treating disease caused by these strains can be 9–25 times higher than treating drug-susceptible TB. Developing new drugs, improved diagnostics and new TB vaccines are critical components of a strategy to combat TB in general, and drug-resistant TB in particular. Because Mycobacterium tuberculosis (MTB) has demonstrated a capacity to develop resistance to drugs developed to combat it, it is unlikely that drug-resistant MTB would be ‘resistant’ to vaccines capable of preventing disease or established infection with drug-sensitive MTB strains. Accordingly, the development of TB vaccines represents an important long-term investment in preventing the spread of drug-resistant TB and achieving WHO's goal of ending the global TB epidemic by 2035. Our current understanding of the epidemiology of drug-resistant TB and the interventions needed to limit its spread, reviewed in this article, illustrates the need for increased financial support for developing new TB drugs, diagnostics and vaccines to meet the WHO goal of TB elimination by 2035. PMID:26884499

  12. Caecal perforation from TB and the Law of Laplace

    PubMed Central

    Khan, Amad N.; Khalid, Salema; Chaudhry, Mohammad Naushad; Ho, Cherrie

    2015-01-01

    A 43-year-old man presented to the hospital with haemoptysis. When worked up, his history and examination were highly suggestive of pulmonary tuberculosis (TB). He subsequently developed a massive upper gastrointestinal bleed and underwent an emergency laparotomy, which revealed a massively dilated caecum measuring ∼20 cm in diameter. The caecum had perforated due to acute decompensation of intestinal TB. Though common in developing countries, TB is rare in the UK, especially the intestinal kind. The most striking feature of this case is, however, the size of the caecal distension caused by the tubercular inflammation and subsequent perforation—something unheard of in the literature. This massive caecal distention would be explained by the Law of Laplace. In conclusion, massive distension and caecal perforation are possible consequences of intestinal TB, especially in the 48–72 h immediately after starting anti-tubercular therapy. PMID:25972412

  13. Managed care and the public health challenge of TB.

    PubMed Central

    Halverson, P K; Mays, G P; Miller, C A; Kaluzny, A D; Richards, T B

    1997-01-01

    Managed care is fast becoming the dominant form of medical care delivery and financing in the United States, yet its effects on public health practice remain largely unknown. Tuberculosis (TB) is a classic example of a disease with both public health and medical care implications, and as such it provides an opportunity for examining the impact on public health of the shift towards managed care in the medical marketplace. The authors approach the role of managed care in TB control by first considering the need for interorganizational coordination at the community level. The authors identify four basic models of how managed care organizations may fit into TB control efforts in local communities, using observations from 12 local public health jurisdictions to illustrate these models. These TB control models provide insight into the general mechanisms through which managed care organizations may affect other areas of public health practice. Images p22-a p23-a p25-a p28-a PMID:9018283

  14. TB diagnostics in India: creating an ecosystem for innovation.

    PubMed

    Engel, Nora; Kenneth, John; Pai, Madhukar

    2012-01-01

    The 'TB diagnostics in India: from importation and imitation to innovation' conference was held in Bangalore, India, on 25-26 August 2011, and was organized by the St. John's Research Institute, Bangalore, with the support of several partners. This unique conference brought together, for the first time, over 220 representatives from industry, government, donors, academia, civil society and the media to discuss what it takes to innovate in tuberculosis (TB) diagnostics in India. The goal was to engage these stakeholders to stimulate interest and investments in TB innovations. The conference was successful in engaging stakeholders and understanding the challenge of TB innovations from diverse perspectives. Coordination between stakeholders and innovations in delivery systems, partnerships, funding, regulatory and communication mechanisms are among the key challenges ahead.

  15. Personalized medicine for patients with MDR-TB.

    PubMed

    Olaru, Ioana D; Lange, Christoph; Heyckendorf, Jan

    2016-04-01

    The emergence of MDR-TB is a cause of great concern due to difficulties in patient management and poor treatment outcomes. Currently the duration of treatment and the choice of drugs for patients with MDR-TB are standardized in many countries. This might not be the best approach since the optimal therapy may depend on different pathogen- and host-related features. Combining the introduction of technological innovations such as whole bacillary genome sequencing for the identification of drug-resistance-associated mutations, therapeutic drug monitoring and host-directed therapies with an individualized approach to MDR-TB management will likely lead to more tolerable, shorter and more efficient treatment regimens and an increase in the quality of life of those affected by MDR-TB.

  16. Tuberculosis: The Connection between TB and HIV (the AIDS Virus)

    MedlinePlus

    ... Tuberculosis Elimination Website at www.cdc.gov/tb File Formats Help: How do I view different file formats (PDF, DOC, PPT, MPEG) on this site? Adobe PDF file Microsoft PowerPoint file Microsoft Word file Microsoft Excel ...

  17. 46 CFR 32.75-1 - Application-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... REQUIREMENTS Hull Requirements for Wood Hull Tank Vessels Constructed Prior to November 10, 1936 § 32.75-1 Application—TB/ALL. All wood hull tank vessels, the construction or conversion of which was started prior...

  18. Disparities in HIV/AIDS, Viral Hepatitis, STDs, and TB

    MedlinePlus

    ... Submit Search The CDC Health Disparities in HIV/AIDS, Viral Hepatitis, STDs, and TB Note: Javascript is ... Hawaiians/Other Pacific Islanders MMWR Publications HIV and AIDS Viral Hepatitis STDs Tuberculosis Training and Networking Resources ...

  19. TB and HIV Therapeutics: Pharmacology Research Priorities.

    PubMed

    Dooley, Kelly E; Kim, Peter S; Williams, Sharon D; Hafner, Richard

    2012-01-01

    An unprecedented number of investigational drugs are in the development pipeline for the treatment of tuberculosis. Among patients with tuberculosis, co-infection with HIV is common, and concurrent treatment of tuberculosis and HIV is now the standard of care. To ensure that combinations of anti-tuberculosis drugs and antiretrovirals are safe and are tested at doses most likely to be effective, selected pharmacokinetic studies based on knowledge of their metabolic pathways and their capacity to induce or inhibit metabolizing enzymes of companion drugs must be conducted. Drug interaction studies should be followed up by evaluations in larger populations to evaluate safety and pharmacodynamics more fully. Involving patients with HIV in trials of TB drugs early in development enhances the knowledge gained from the trials and will ensure that promising new tuberculosis treatments are available to patients with HIV as early as possible. In this review, we summarize current and planned pharmacokinetic and drug interaction studies involving investigational and licensed tuberculosis drugs and antiretrovirals and suggest priorities for tuberculosis-HIV pharmacokinetic, pharmacodynamic, and drug-drug interaction studies for the future. Priority studies for children and pregnant women with HIV and tuberculosis co-infection are briefly discussed.

  20. Comparison of the Sensitivity of QuantiFERON-TB Gold In-Tube and T-SPOT.TB According to Patient Age

    PubMed Central

    Bae, Won; Park, Kyoung Un; Song, Eun Young; Kim, Se Joong; Lee, Yeon Joo; Park, Jong Sun; Cho, Young-Jae; Yoon, Ho Il; Yim, Jae-Joon; Lee, Choon-Taek; Lee, Jae Ho

    2016-01-01

    Currently, there are two types of interferon-gamma release assays (IGRAs) in use for the detection of tuberculosis (TB) infection, the QuantiFERON-TB Gold In-Tube test (GFT-GIT) and T-SPOT.TB. Owing to contradictory reports regarding whether the results of these IGRAs are affected by the age of the patient, we aimed to determine if these two tests have age-related differences in sensitivity. We retrospectively reviewed the medical records of diagnosed TB patients who were tested using either QFT-GIT or T-SPOT.TB from February 2008 to December 2013. The positivity of the two tests was analyzed and compared with true TB infection, which was defined as active TB based on either a positive Mycobacterium culture or a positive TB polymerase chain reaction. The QFT-GIT group included 192 TB patients, and the T-SPOT.TB group included 212 TB patients. Of the patients with pulmonary TB, 76 (39.6%) were in the QFT-GIT group and 143 (67.5%) in the T-SPOT.TB group. The overall sensitivity was 80.2% for QFT-GIT and 91.0% for T.SPOT.TB. The sensitivities of QFT-GIT and T-SPOT.TB according to age group were as follows: <29 years, 93.3% and 96.7%; 30–49 years, 86.5% and 94.7%; 50–69 years, 76.8% and 87.5%; and >70 years, 68.3% and 85.7%, respectively. The trend of age-related changes in sensitivity was significant for both QFT-GIT (p = 0.004) and T.SPOT.TB (p = 0.039). However, only QFT-GIT was significantly related to age in the multivariate analysis. QFT-GIT, but not T-SPOT.TB, was significantly affected by patient age. PMID:27258377