Role of alkali carbonate and salt in topochemical synthesis of K1/2Na1/2NbO3 and NaNbO3 templates

Science.gov (United States)

Lee, Jae-Seok; Jeon, Jae-Ho; Choi, Si-Young

2013-11-01

Since the properties of lead-free piezoelectric materials have thus far failed to meet those of lead-based materials, either chemical doping or morphological texturing should be employed to improve the piezoelectric properties of lead-free piezoelectric ceramics. The goal of this study was to synthesize plate-like K1/2Na1/2NbO3 and NaNbO3 particles, which are the most favorable templates for morphological texturing of K1/2Na1/2NbO3 ceramics. To achieve this goal, Bi2.5Na3.5Nb5O18 precursors in a plate-like shape were first synthesized and subsequently converted into K1/2Na1/2NbO3 or NaNbO3 particles that retain the morphology of Bi2.5Na3.5Nb5O18. In this study, we found that sodium or potassium carbonate does not play a major role in converting the Bi2.5Na3.5Nb5O18 precursor to K1/2Na1/2NbO3 or NaNbO3, on the contrary to previous reports; however, the salt contributes to the conversion reaction. All synthesis processes have been performed via a molten salt method, and scanning electron microscopy, scanning probe microscopy, and inductively coupled plasma mass spectroscopy were used to characterize the synthesized K1/2Na1/2NbO3 or NaNbO3 templates.

History-dependent thermal expansion in NbO{sub 2}F

Energy Technology Data Exchange (ETDEWEB)

Wilkinson, Angus P., E-mail: angus.wilkinson@chemistry.gatech.edu [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Josefsberg, Ryan E.; Gallington, Leighanne C.; Morelock, Cody R.; Monaco, Christopher M. [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States)

2014-05-01

Materials with cubic ReO{sub 3}-type structures are of interest for their low or negative thermal expansion characteristics. TaO{sub 2}F is known to display almost zero thermal expansion over a wide temperature range. On heating NbO{sub 2}F, its volume coefficient of thermal expansion decreases from ∼+45 ppm K{sup −1} at 100 K to almost zero at 400 K. NbO{sub 2}F is cubic between 100 and 500 K. Samples of “NbO{sub 2}F” prepared by the digestion of Nb{sub 2}O{sub 5} in aqueous HF followed by mild drying contain hydroxyl defects and metal vacancies. On heating, they can undergo irreversible chemical changes while maintaining a cubic ReO{sub 3}-type structure. The possibility of hydroxyl defect incorporation should be considered when preparing oxyfluorides for evaluation as battery materials. - Graphical abstract: “NbO{sub 2}F” prepared by the digestion of Nb{sub 2}O{sub 5} in HF contains cation vacancies and hydroxyl groups. It undergoes irreversible changes on heating to low temperatures, unlike NbO{sub 2}F prepared by the solid state reaction of Nb{sub 2}O{sub 5} and NbF{sub 5}. - Highlights: • The digestion of Nb{sub 2}O{sub 5} in aqueous HF followed by mild drying does not produce NbO{sub 2}F. • The ReO{sub 3}-type product from the HF digestion of Nb{sub 2}O{sub 5} contains metal vacancies and hydroxyl. • The thermal expansion coefficient of NbO{sub 2}F decreases on heating and approaches zero at ∼400 K.

Evaluation of the nuclear cross sections for the reactions: /sup 93/Nb(n,2n)sup(92M)Nb and /sup 93/Nb(n,2n)/sup 92/Nb from threshold to 20 MeV

Energy Technology Data Exchange (ETDEWEB)

Philis, C; Young, P G

1975-07-01

A preliminary evaluation of the nuclear cross section for the reactions /sup 93/Nb(n,2n)sup(92M)Nb and /sup 93/Nb(n,2n)/sup 92/Nb has been completed from threshold to 20 MeV. The evaluation is based entirely on experimental results. The recommended values were determined after analysis, selection, and normalization of the measurements to a consistent set of standards. The evaluated data are discussed and compared with theoretical values and estimates of the uncertainty in the adopted data are provided.

Effect of Nb-doped TiO{sub 2} on nanocomposited aligned ZnO nanorod/TiO{sub 2}:Nb for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Saurdi, I., E-mail: saurdy788@gmail.com; Ishak, A. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM),40450 Shah Alam, Selangor (Malaysia); UiTM Sarawak Kampus Kota Samarahan Jalan Meranek, Sarawak (Malaysia); Shafura, A. K.; Azhar, N. E. A.; Mamat, M. H. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM),40450 Shah Alam, Selangor (Malaysia); Malek, M. F.; Rusop, M. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM),40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), (Centre for Nano-Science and Nano-Technology), Institute of Science, Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia); Alrokayan, A. H. Salman; Khan, Haseeb A. [Department of Biochemistry, College of Science, Bldg. 5, King Saud University (KSU) P.O: 2455 Riyadh 1145 (Saudi Arabia)

2016-07-06

The Nb-doped TiO{sub 2} films were deposited on glass substrate at different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively and their electrical and structural properties were investigated. Subsequently, the Nb-doped TiO{sub 2} films were deposited on top of aligned ZnO Nanorod on ITO glass substrates using spin coating technique. The nanocomposited aligned ZnO nanorod/Nb-doped TiO{sub 2} (TiO{sub 2}:Nb) were coated with different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively. The Dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO{sub 2}:Nb photoanodes and their effects on the performance of the DSSCs were investigated. From the solar simulator measurement of DSSC the solar energy conversion efficiency (η) of 5.376% under AM 1.5 was obtained for the ZnO nanorod/TiO{sub 2}:Nb-5at.%.

Effect of Nb aggregates on Zr2Fe

International Nuclear Information System (INIS)

Ramos, Cinthia P.

2001-01-01

The binary Zr-Fe phase diagram revision, performed by Arias et al., accepted the intermetallic Zr 2 Fe crystalline structure as tetragonal and determined that the presence of a third element like oxygen, nitrogen or carbon, stabilizes a cubic phase. Nevitt et al. studying Ti, Zr and Hf alloys with transition metals as second or third element and ternary systems with oxygen as third element, systematized the occurrence of phases with a cubic Ti 2 Ni type crystalline structure. From previous studies in the Zr-Nb-Fe system, it is an agreed fact that Nb presence in the Zr 2 Fe intermetallic stabilizes a cubic Ti 2 Ni type phase. The purpose of the present work is to determine the stability range of the Zr 2 Fe intermetallic with Nb contents, the existence range of the ternary cubic Ti 2 Ni type phase (designated Λ) and the corresponding two-phase region. We analyze as cast and heat treated (800 C degrees) Zr-Nb-Fe alloys with 35 atomic % Fe and Nb contents between 0.5 and 15 atomic %. The determination and characterization of the phases is made by optical and scanning electron microscopy, X-ray diffraction microprobe analysis and Moessbauer Spectroscopy. Joining these techniques together it is found, among many other things, that the Zr 2 Fe phase would accept up to around 0.5 atomic % Nb in solution and that the two-phase region Zr 2 Fe+Λ would be stable in the (0.5 - 3.5) Nb atomic % range. It is proposed as well a 800 C degrees section of the ternary (Zr-Nb-Fe) in the studied region. (author) [es

Facile synthesis and characterization of hexagonal NbSe2 nanoplates

International Nuclear Information System (INIS)

Zhang, Xianghua; Zhang, Du; Tang, Hua; Ji, Xiaorui; Zhang, Yi; Tang, Guogang; Li, Changsheng

2014-01-01

Graphical abstract: - Highlights: • Uniform hexagonal NbSe 2 nanoplates were prepared by a simple solid state reaction. • The possible formation mechanism of the NbSe 2 nanoplates was discussed. • The formation of NbSe 2 nanoplates undergoes a series of phase transition. - Abstract: The NbSe 2 nanoplates with hexagonal morphology have been successfully prepared by a facile, environmentally friendly reaction in closed reactor at moderate temperature. The thermal (750 °C) solid-state reaction between the ball-milled mixture of micro-sized Nb and Se yielded a high yield of NbSe 2 nanoplates. The as-prepared products were characterized by XRD, EDS, and SEM. The results showed that the as-prepared products were hexagonal phase NbSe 2 nanoplates with uniform sizes and the formation of NbSe 2 nanoplates underwent a series of phase transition. On the basis of experimental results obtained at different temperatures, a reasonable reaction process and a formation mechanism were proposed. Moreover, the ball milling time played a crucial role in acquiring the homogeneous distribution nanoplates

MYC/BCL2/BCL6 triple hit lymphoma: a study of 40 patients with a comparison to MYC/BCL2 and MYC/BCL6 double hit lymphomas.

Science.gov (United States)

Huang, Wenting; Medeiros, L Jeffrey; Lin, Pei; Wang, Wei; Tang, Guilin; Khoury, Joseph; Konoplev, Sergej; Yin, C Cameron; Xu, Jie; Oki, Yasuhiro; Li, Shaoying

2018-05-21

High-grade B-cell lymphomas with MYC, BCL2, and BCL6 rearrangements (triple hit lymphoma) are uncommon. We studied the clinicopathologic features of 40 patients with triple hit lymphoma and compared them to 157 patients with MYC/BCL2 double hit lymphoma and 13 patients with MYC/BCL6 double hit lymphoma. The triple hit lymphoma group included 25 men and 15 women with a median age of 61 years (range, 34-85). Nine patients had a history of B-cell lymphoma. Histologically, 23 (58%) cases were diffuse large B-cell lymphoma and 17 cases had features of B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma. Most cases of triple hit lymphoma were positive for CD10 (100%), BCL2 (95%), BCL6 (82%), MYC (74%), and 71% with MYC and BCL2 coexpression. P53 was overexpressed in 29% of triple hit lymphoma cases. The clinicopathological features of triple hit lymphoma patients were similar to patients with MYC/BCL2 and MYC/BCL6 double hit lymphoma, except that triple hit lymphoma cases were more often CD10 positive compared with MYC/BCL6 double hit lymphoma (p hit lymphoma and double hit lymphoma and overall survival in triple hit lymphoma patients was 17.6 months, similar to the overall survival of patients with double hit lymphoma (p = 0.67). Patients with triple hit lymphoma showing P53 overexpression had significantly worse overall survival compared with those without P53 overexpression (p = 0.04). On the other hand, double expressor status and prior history of B-cell lymphoma did not correlate with overall survival. In conclusion, most patients with triple hit lymphoma have an aggressive clinical course and poor prognosis and these tumors have a germinal center B-cell immunophenotype, similar to patients with double hit lymphomas. P53 expression is a poor prognostic factor in patients with triple hit lymphoma.

Topotactic dehydration of the lamellar oxide HK2Ti5NbO14 x H2O: the oxide K4Ti10Nb2O27

International Nuclear Information System (INIS)

Grandin, A.; Borel, M.M.; Hervieu, M.; Raveau, B.

1987-01-01

The lamellar oxide HK 2 Ti 5 NbO 14 x H 2 O can be topotactically dehydrated to K 4 Ti 10 Nb 2 O 27 . Electron diffraction and X-ray diffraction studies of this phase lead to a monoclinic cell with the parameters a = 17.005, b = 3.78, c = 9.01 A and β 92.14 0 . Diffusion streaks on the electron diffraction patterns indicate disorder whereas the existence of two sets of lattices on the same crystal give evidence of the topotactic character of the reaction. A structural model is proposed for K 4 Ti 10 Nb 2 O 27 , which corresponds to the intergrowth of K 3 TiNbO 14 layers with the K 2 Ti 6 O 13 tunnel structure. The possibility of formation of various intergrowths such as (KTi 5 NbO 13 )/sub n/ (HK 2 Ti 5 NbO 14 )/sub n/' is suggested

Electronic parameters of Sr2Nb2O7 and chemical bonding

DEFF Research Database (Denmark)

Atuchin, V.V.; Grivel, Jean-Claude; Korotkov, A.S.

2008-01-01

/2)) and Delta(O-Sr) = BE(O 1s)-BE(Sr 3d(5/2)), were used to characterize the valence electron transfer on the formation of the Nb-O and Sr-O bonds. The chemical bonding effects were considered on the basis of our XPS results for Sr2Nb2O7 and earlier published structural and XPS data for other Sr- or Nb...

No solid solution compounds in between the binaries. Syntheses and crystal structures of Nb(Br{sub 0.62(4)}Cl{sub 0.38(4)}){sub 2}Cl{sub 2} and NbI{sub 2}Cl{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Reckeweg, Olaf; Schleid, Thomas [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

2018-04-01

The anion-mixed niobium tetrahalides Nb(Br{sub 0.62(4)}Cl{sub 0.38(4)}){sub 2}Cl{sub 2} and NbI{sub 2}Cl{sub 2} were obtained by heating NbBr{sub 5} with NbCl{sub 5} and NbI{sub 5} with NbCl{sub 5}, respectively, in equimolar ratios with niobium metal in evacuated, torch-sealed silica ampoules at 720 K for 3 days. The orthorhombic title compounds form as very brittle black needles and were characterized by single-crystal X-ray diffraction [space group: Immm, Z=4; a=704.27(6), b=824.13(7), c=929.64(8) pm for Nb(Br{sub 0.62(4)}Cl{sub 0.38(4)}){sub 2}Cl{sub 2} and a=753.76(6), b=829.38(7) and c=983.41(8) pm for NbI{sub 2}Cl{sub 2}]. Surprisingly enough, these mixed-anionic halides are not isostructural with either NbCl{sub 4}, NbBr{sub 4} or NbI{sub 4}, but crystallize isotypically with TaI{sub 2}Cl{sub 2}, thus being examples for differential site occupancy stabilized materials. Structural features of other niobium(IV) halides are compiled and compared to those of Nb(Br{sub 0.62(4)}Cl{sub 0.38(4)}){sub 2}Cl{sub 2} and NbI{sub 2}Cl{sub 2}. Except for NbF{sub 4}, they all exhibit chains of trans-edge connected [NbX{sub 6}]{sup 2-} octahedra, which allow Peierls distortions to form Nb-Nb single bonds. The packing of these chains differ, however, depending on the actual halide or mixed-halide combination.

Synthesis and phase transformation mechanism of Nb{sub 2}C carbide phases

Energy Technology Data Exchange (ETDEWEB)

Vishwanadh, B., E-mail: visubathula@gmail.com [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 094 (India); Murthy, T.S.R.Ch. [Materials Processing Division, Bhabha Atomic Research Centre, Mumbai 400 094 (India); Arya, A.; Tewari, R.; Dey, G.K. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 094 (India)

2016-06-25

In the present work, Niobium carbide samples were prepared through powder metallurgy route using spark plasma sintering technique. Some of these samples were heat treated at 900 °C up to 7 days. In order to investigate the phase transformation in Nb{sub 2}C carbide, the as-prepared and heat treated samples were characterized by X-ray diffraction, scanning electron microscopy and electron back scattered diffraction (EBSD) and transmission electron microscopy techniques. EBSD could index the same area of the sample in terms of any of the three allotropes of Nb{sub 2}C carbide phases (γ-Nb{sub 2}C, β-Nb{sub 2}C and α-Nb{sub 2}C) with good confidence index. From the EBSD patterns orientation relationships (OR) among γ, β and α-Nb{sub 2}C have been determined. Based on this OR when crystals of the three allotropes were superimposed, it has revealed that the basic Nb metal atom lattice (hcp lattice) in all the Nb{sub 2}C phases is same. The only difference exists in the carbides is the ordering of carbon atoms and vacancies in the octahedral positions of the hcp Nb metal atom lattice. Crystallographic analysis showed that for the transformation of γ-Nb{sub 2}C → β-Nb{sub 2}C → α-Nb{sub 2}C, large movement of Nb atoms is not required; but only by ordering of carbon atoms ensues the phase transformation. Literature shows that in the Nb–C system formation of the α-Nb{sub 2}C is not well established. Therefore, first principle calculations were carried out on these carbides. It revealed that the formation energy for α-Nb{sub 2}C is lower than the β and γ-Nb{sub 2}C carbides which indicate that the formation of α-Nb{sub 2}C is thermodynamically feasible. - Highlights: • Nb{sub 2}C carbide was produced by Spark Plasma Sintering in a single process. • Phase transformation mechanism of different Nb{sub 2}C carbide phases is studied. • In all the three Nb{sub 2}C carbides (γ, β, α), the base Nb lattice remains same. • Among γ, β and α-Nb{sub 2}C

The creep of UO2 fuel doped with Nb2O5

International Nuclear Information System (INIS)

Sawbridge, P.T.; Reynolds, G.L.; Burton, B.

1981-01-01

The creep of UO 2 containing small additions of Nb 2 O 5 has been investigated in the stress range 0.5-90 MN/m 2 at temperatures between 1422 and 1573 K. The functional dependence of the creep rate of five dopant concentrations up to 0.8 mol% Nb 2 O 5 has been examined and it was established that in all the materials the secondary creep rate could be represented by the equation epsilonkT = Asigmasup(n) exp(-Q/RT), where epsilon is the steady state creep rate per hour, Q the activation energy and A and n are constants for each material. It was observed that Nb 2 O 5 additions can cause a dramatic increase in the steady state creep rate as long as the niobium ion is maintainde in the Nb 5+ valence state. Material containing 0.4 mol% Nb 2 O 5 creeps three orders of magnitude faster than the pure material. Analysis of the results in terms of grain size compensated viscosity suggest that, like pure UO 2 , the creep rate of Nb 2 O 5 doped fuel is diffusion-controlled and proportional to the reciprocal square of the grain size. A model is developed which suggests that the increase in creep rate results from suppression of the U 5+ ion concentration by the addition of Nb 5+ ions, which modifies the crystal defect structure and hence the uranium ion diffusion coefficient. (orig.)

Superconducting Nb{sub 3}Sn intermetallics made by electrochemical reduction of Nb{sub 2}O{sub 5}-SnO{sub 2} oxides

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B A; Fray, D J; Yan, X-Y; Chen, G

2003-05-01

The article is focused on low temperature superconducting Nb{sub 3}Sn material manufactured by novel electrodeoxidizing method developed in Cambridge whereby the range of alloys and intermetallics are produced cheaply making potential superconducting wires more cost effective. The process of direct electrochemical reduction of Nb{sub 2}O{sub 5}-SnO{sub 2} mixtures and in situ formation of the Nb{sub 3}Sn is discussed in details.

The preparation and testing of Nb-Zr and Nb-ZrO2 single crystals for deformation studies

International Nuclear Information System (INIS)

Botta Filho, W.J.; Christian, J.W.; Taylor, G.

1987-01-01

The difficulties to obtain adequate single crystals of Nb-Zr and Nb-ZrO 2 alloys for deformation studies are discussed. Low-temperature internal oxidation of Nb-Zr alloys followed by ageing at higher temperatures resulted in the precipitation of ZrO 2 particles. However, the effect of this treatment on the particles size and distribution and on the crystallographic structure of the particle was not completely understood. Compression tests in the temperature range 4.2K to 373K showed a small effect of zirconia particles on the mechanical properties of Nb-Zr solid solutions and a significative effect of the amount of oxygen remaining in solid solution after the oxidation treatment. (author) [pt

Z-contrast imaging of ordered structures in Pb(Mg1/3Nb2/3)O3 and Ba(Mg1/3Nb2/3)O3

International Nuclear Information System (INIS)

Yan, Y.; Pennycook, S.J.; Xu, Z.; Viehland, D.

1998-02-01

Lead-based cubic perovskites such as Pb(B 1/3 2+ B 2/3 5+ )O 3 (B 2+ Mg, Co, Ni, Zn; B 5+ = Nb, Ta) are relaxor ferroelectrics. Localized order and disorder often occur in materials of this type. In the Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) family, previous studies have proposed two models, space-charge and charge-balance models. In the first model, the ordered regions carry a net negative charge [Pb(Mg 1/2 Nb 1/2 )O 3 ], while in the second model it does not carry a net charge [Pb((Mg 2/3 Nb 1/3 ) 1/2 Nb 1/2 )O 3 ]. However, no direct evidence for these two models has appeared in the literature yet. In this paper the authors report the first direct observations of local ordering in undoped and La-doped Pb(Mg 1/3 Nb 2/3 )O 3 , using high-resolution Z-contrast imaging. Because the ordered structure in Ba(Mg 1/3 Nb 2/3 )O 3 is well known, the Z-contrast image from an ordered domain is used as a reference for this study

Fatigue and strain effects in NbTi, Nb3Sn, and V2(Hf, Zr) multifilamentary superconductors

International Nuclear Information System (INIS)

Kuroda, T.; Wada, H.; Tachikawa, K.

1988-01-01

The effects of cyclic strain on critical current were studied in NbTi, bronze processed Nb 3 Sn, and composite diffusion processed V 2 (Hf,Zr) multifilamentary wires. No appreciable changes in critical current were found in NbTi wires until just prior to fatigue-induced fracture. Critical current degradation was also not observed in Nb 3 Sn or V 2 (Hf,Zr) as long as the wires were strained below the reversible limit strain. For strains beyond this limit strain the critical current was first degraded by an increasing number of cycles and then remained constant after a certain cycle number was passed

Vaporization study on nonstoichiometric NbOsub(2+-x) by mass-spectrometric method

International Nuclear Information System (INIS)

Matsui, T.; Naito, K.

1981-01-01

The vapor pressures over nonstoichiometric NbOsub(2+-x)(s) (1.972 2 (g) and NbO(g) over nonstoichiometric NbOsub(2+-x), from which the partial molar enthalpies and entropies of oxygen were calculated as a function of O/Nb composition. The composition dependence of the partial molar enthalpy and entropy obtained suggested the existence of some kind of short-range ordering in the nonstoichiometric Nbsub(2+-x) (s) phase. The enthalpies of formation of nonstoichiometric NbOsub(2+-x) (s) were also determined as a function of composition by combining the partial molar enthalpies of oxygen with the enthalpy of formation of stoichiometric NbOsub(2.000) (s). The phase diagram around NbOsub(2+-x) at high temperatures was determined from the vaporization study. (orig.)

Valence band electronic structure of Nb{sub 2}Pd{sub 1.2}Se{sub 5} and Nb{sub 2}Pd{sub 0.95}S{sub 5} superconductors

Energy Technology Data Exchange (ETDEWEB)

Lohani, H. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085 (India); Mishra, P. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Goyal, R.; Awana, V.P.S. [National Physical Laboratory(CSIR), Dr. K. S. Krishnan Road, New Delhi 110012 (India); Sekhar, B.R., E-mail: sekhar@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085 (India)

2017-03-15

We present a comparative study of our valence band photoemission results on Nb{sub 2}Pd{sub 1.2}Se{sub 5} and Nb{sub 2}Pd{sub 0.95}S{sub 5} superconductors which are supported by our DFT based electronic structure calculations. We observe that the VB spectra of both the compounds are qualitatively similar, except for some slight differences in the binding energy positions of all the features. This could be due to the unequal electronegativities of Se and S atom. The calculated density of states (DOS) reveals that the VB features are mainly composed of Pd-Se/S hybridized states. The nature of DOS originating from the distinctly coordinated Pd atoms is different. Further, various Pd-4d and Nb-4d states crossing the Fermi level (E{sub f}) signifies the multiband character of these compounds. In addition, we find a temperature dependent pseudogap in Nb{sub 2}Pd{sub 0.95}S{sub 5} which is absent in Nb{sub 2}Pd{sub 1.2}Se{sub 5}.

Synthesis and molecular structures of niobocene derivatives containing Nb-Sn-Nb metallochain

International Nuclear Information System (INIS)

Skripkin, Yu.V.; Volkov, O.G.; Pasynskij, A.A.

1985-01-01

The [Cp 2 Nb(CO)] 2 SnCl 2 (1) complex is synthesized in the form of crystals with 63% yield by the Cp 2 Nb(CO)H reaction wih SnCl 4 in THF in the presence of Et 3 N. The complex 1 is also prepared by interaction of Cp 2 Nb(CO)H with Cp 2 Nb(CO)SnCl 3 with 16% yield. The crystalline more sluble analog [(CH 3 C 5 H 4 ) 2 Nb(CO)] 2 ShCl 2 (2) is extracted, which contains the chain of Nb-Sn-Nb with short Nb-Sn(2.840)2)A bonds and 140.69(5) deg angle between them. The (Cp 2 NbH) 2 Sn(Cl)Et (3) complex is prepared wih 12% yield, possessing the structure analogous to type 2. In 3 each fragment CpNb is connected with the terminal hydride (Nb-H, 1.66(1) and 1.69(1)A) atom forms shortened bond with tin atom Nb-Sn 2.868(1) and 2.856(1) A, NbSnNb angle is 129.44(5)

Effect of quenching in the Ti-Nb-2%Al alloys structure; Efeito da tempera na estrutura das ligas Ti-Nb-2%Al

Energy Technology Data Exchange (ETDEWEB)

Santos, L.C.O.; Matlakhova, L.A.; Matlakhov, A.N.; Toledo, R. [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacazes, RJ (Brazil). Centro de Ciencias e Tecnologia. Lab. de Materiais Avancados (LAMAV)], e-mail: lucascunhasantos@terra.com.br

2006-07-01

In the present work, the Ti-Nb-2%Al alloys, with the rate varied Nb from 15 to 40%, they were submitted to the quenched since 1000 deg C, in water, to verify the influence of Nb in the structure and phase composition. The alloys were obtained in a process of five coalitions in an oven to electric arch and, soon afterwards, wrought the hot and homogenized to 1200 deg C, for 10 hours. After the quenching and conventional metallographic preparation of the samples obliquely cut, the alloys were examined through the optic microscopic, diffraction of ray-X and Vickers hardness. The very defined correlation was shown between the niobium rate and the structure resulting from the quenched alloys. The phase martensitic was revealed in the alloy with 15% Nb, the phases martensitic and beta metastable in the alloys containing above 30% Nb and the phase beta in the alloys with 38% Nb and 40% Nb. the hardness of the phase martensitic increases with the increment of the niobium rate. (author)

Irradiation-induced amorphization of Cd2Nb2O7 pyrochlore

International Nuclear Information System (INIS)

Meldrum, A.; White, C. W.; Keppens, V.; Boatner, L. A.; Ewing, R. C.

2001-01-01

Several investigations have recently been undertaken in order to achieve a more complete understanding of the radiation-damage mechanisms in A 2 B 2 O 7 pyrochlore-structure compounds. The present work represents the first systematic study of the irradiation-induced amorphization of a pyrochlore with A- and B-site cation valences of +2 and +5, respectively. Relatively large single crystals of Cd 2 Nb 2 O 7 were grown for these experiments. In situ ion-irradiation experiments were carried out in a transmission electron microscope in conjunction with ex situ Rutherford backscattering measurements of ion-irradiated Cd 2 Nb 2 O 7 single crystals. Cd 2 Nb 2 O 7 can be amorphized in situ by Ne or Xe ions at temperatures up to 480 and 620 K, respectively. At room temperature, the amorphization fluence was 36 times higher for 280 keV Ne + than for 1200 keV Xe 2+ , corresponding to a displacement dose that was higher by a factor of 3. Disordering of Cd and Nb over the available cation sites occurs at intermediate ion doses prior to amorphization. The temperature dependence of the amorphization dose is modeled, and the results are compared to those of a previous model. The bulk-sample Rutherford backscattering spectroscopy (RBS) results were generally consistent with the in situ TEM measurements. Effects of crystallographic orientation and ion charge state had relatively little effect on the damage accumulation in bulk crystals. The RBS data are consistent with a defect-accumulation, cascade-overlap model of amorphization of Cd 2 Nb 2 O 7 , as are the in situ TEM observations

A Ruddlesden-Popper-type layered perovskite, Na2Ca2Nb4O13

International Nuclear Information System (INIS)

Chiba, K.; Ishizawa, N.; Oishi, S.

1999-01-01

Single crystals of disodium dicalcium tetraniobium tridecaoxide, Na 2 Ca 2 Nb 4 O 13 , were grown by the flux method. The structure was determined in space group Bb2 1 m. Perovskite-type layers with the formula [(Ca 2 Na)Nb 4 O 13 ] - are concatenated by Na + cations near the interlayer, forming a Ruddlesden-Popper-type structure. The interlayer structure, composed of Na and O atoms, can be regarded as a rocksalt-type. NbO 6 octahedra are tilted about [010] and [001]. The off-centre displacement of Nb atoms suggests a ferroelectric nature along [010], with a calculated magnitude of polarization of 0.12 C m -2 . (orig.)

Liquidus projection of the Nb-Cr-Al system near the Al3(Nb,Cr) + Cr(Al,Nb) eutectic region

International Nuclear Information System (INIS)

Souza, S.A.; Ferrandini, P.L.; Nunes, C.A.; Coelho, A.A.; Caram, R.

2006-01-01

The system Nb-Cr-Al was investigated in the region near the Al 3 (Nb,Cr) + Cr(Al,Nb) eutectic and the liquidus projection of that region was determined based on the microstructural characterization of arc melted alloys. The characterization utilized scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential thermal analysis (DTA) and X-ray diffraction (XRD). The results allowed one to determine three primary solidification liquidus surfaces ((Cr,Al) 2 Nb, Cr(Al,Nb) and Al 3 (Nb,Cr)), that are originated from the binary systems Cr-Nb, Cr-Al and Al-Nb. It is proposed the occurrence of the invariant reaction L + (Cr,Al) 2 Nb ↔ Al 3 (Nb,Cr) + Cr(Al,Nb) and of a point of minimum, which involves a three phase reaction, L ↔ Al 3 (Nb,Cr) + Cr(Al,Nb). All alloys studied showed formation of the Al 3 (Nb,Cr) + Cr(Al,Nb) eutectic as the last solidification step with Al(Nb)Cr 2 precipitating from Cr(Al,Nb)

J chain and myocyte enhancer factor 2B are useful in differentiating classical Hodgkin lymphoma from nodular lymphocyte predominant Hodgkin lymphoma and primary mediastinal large B-cell lymphoma.

Science.gov (United States)

Moore, Erika M; Swerdlow, Steven H; Gibson, Sarah E

2017-10-01

Although most classical Hodgkin lymphomas (CHLs) are easily distinguished from nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) and primary mediastinal large B-cell lymphoma (PMBL), cases with significant CD20 expression cause diagnostic confusion. Although the absence of OCT-2 and BOB.1 are useful in these circumstances, a variable proportion of CHLs are positive for these antigens. We investigated the utility of J chain and myocyte enhancer factor 2B (MEF2B) in the diagnosis of CHL; NLPHL; PMBL; T-cell/histiocyte-rich large B-cell lymphoma (TCRLBL); and B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and CHL, compared with OCT-2 and BOB.1. J chain and MEF2B highlighted lymphocyte predominant (LP) cells in 20/20 (100%) NLPHLs and were negative in 43/43 (100%) CHLs. Fourteen of 15 (93%) PMBLs and 4/4 (100%) TCRLBLs were MEF2B positive, whereas 67% of PMBLs and 50% of TCRLBLs were J chain positive. Three of 3 B-cell lymphomas, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and CHL, were negative for J chain and MEF2B. J chain and MEF2B were 100% sensitive and specific for NLPHL versus CHL. MEF2B was 100% sensitive and 98% specific for PMBL versus CHL. Whereas loss of OCT-2 and/or BOB.1 expression had a sensitivity of only 86% and specificity of 100% for CHL versus NLPHL, PMBL, and TCRLBL, lack of both J chain and MEF2B expression was 100% sensitive and 97% specific. J chain and MEF2B are highly sensitive and specific markers of NLPHL versus CHL; are particularly useful in highlighting LP cells; and, with rare exception, are of greater utility than OCT-2 and BOB.1 in differentiating CHL from NLPHL and other large B-cell lymphomas. Copyright © 2017 Elsevier Inc. All rights reserved.

Carrier compensation mechanism in heavily Nb-doped anatase Ti{sub 1-x}Nb{sub x}O{sub 2+{delta}} epitaxial thin films

Energy Technology Data Exchange (ETDEWEB)

Nogawa, H; Chikamatsu, A; Hirose, Y; Hasegawa, T [Department of Chemistry, University of Tokyo, Tokyo 113-0033 (Japan); Nakao, S [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); Kumigashira, H; Oshima, M, E-mail: chikamatsu@chem.s.u-tokyo.ac.jp [Department of Applied Chemistry, University of Tokyo, Tokyo 113-8656 (Japan)

2011-09-14

We investigated the electronic structures of anatase Ti{sub 1-x}Nb{sub x}O{sub 2+{delta}} (TNO) thin films as a function of Nb concentration x using photoemission spectroscopy (PES) measurements to elucidate the origin of the abrupt decrease in carrier activation in heavily Nb-doped regime. The existing intensity ratio of Nb{sup 5+} evaluated from Nb 3d core-level PES spectra maintained a constant value of {approx}0.8 at x = 0.06-0.3, implying that electron carriers generated by Nb doping are compensated by p-type defects. Ti 2p-3d and O1s-2p resonant PES measurements of x = 0.06-0.3 films revealed that the in-gap states positioned {approx}1 eV below the Fermi level (E{sub F}) have a mixed character of Ti 3d and O 2p orbitals, whereas the states at E{sub F} mainly have a Ti 3d nature. We proposed a carrier compensation mechanism that interstitial oxygen atoms strongly combined with surrounding Nb atoms kill conduction electrons in heavily Nb-doped anatase TiO{sub 2}.

Two-dimensional Haeckelite NbS{sub 2}. A diamagnetic high-mobility semiconductor with Nb{sup 4+} ions

Energy Technology Data Exchange (ETDEWEB)

Ma, Yandong; Kuc, Agnieszka; Jing, Yu; Heine, Thomas [Wilhelm-Ostwald-Institut fuer Physikalische und Theoretische Chemie, Universitaet Leipzig (Germany); Philipsen, Pier [Scientific Computing and Modelling NV, Amsterdam (Netherlands)

2017-08-14

In all known Group 5 transition-metal dichalcogenide monolayers (MLs), the metal centers carry a spin, and their ground-state phases are either metallic or semiconducting with indirect band gaps. Here, on grounds of first-principles calculations, we report that the Haeckelite polytypes 1S-NbX{sub 2} (X=S, Se, Te) are diamagnetic direct-band-gap semiconductors even though the Nb atoms are in the 4+ oxidation state. In contrast, 1S-VX{sub 2} MLs are antiferromagnetically coupled indirect-band-gap semiconductors. The 1S phases are thermodynamically and dynamically stable but of slightly higher energy than their 1H and 1T ML counterparts. 1S-NbX{sub 2} MLs are excellent candidates for optoelectronic applications owing to their small band gaps (between 0.5 and 1 eV). Moreover, 1S-NbS{sub 2} shows a particularly high hole mobility of 2.68 x 10{sup 3} cm{sup 2} V{sup -1} s{sup -1}, which is significantly higher than that of MoS{sub 2} and comparable to that of WSe{sub 2}. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

A study on the delayed hydride cracking mechanism in cold worked Zr-2.5Nb, heat treated Zr-2.5Nb and zircaloy-2 pressure tubes

Energy Technology Data Exchange (ETDEWEB)

Choi, Kwang Sik

1992-02-15

Cold worked Zr-2.5Nb, heat treated Zr-2.5Nb and Zircaloy-2 pressure tubes were hydrided to the hydrogen concentration of 68 ppm, 49 ppm and 242-411 ppm, respectively, and compact tension specimens were machined from the hydrided materials. The crack growth rate by delayed hydride cracking was measured by potential drop method at various temperatures on the above mentioned three types of specimens. The activation energy obtained were 43 KJ/mol for cold worked Zr-2.5Nb and 37 KJ/mol for heat treated Zr-2.5Nb, which were in good agreements with that of Coleman (1977), while they were lower than the activation energy of 65.5 KJ/mol obtained by Simpson-puls (1979) and 71.5 KJ/mol by Ambler (1984). The DHC growth rate in Zircaloy-2 were about one fifth of that of Zr-2.5Nb, which is due to the texture and material strength effects. Striations which indicate stepwise DHC growth were observed at fracture surface by scanning electron microscope and unsymmetric crack tunnellings were also observed, which seems to be due to the difference in hydrogen diffusion rate caused by the difference in stress fields between inner and outer surface. The comparison of test results with the DHC growth rate calculated by Simpson-puls model showed good agreement at high temperatures, whereas at the lower temperatures the crack growth rates were 2.5 times higher than the calculated values.

A study on the delayed hydride cracking mechanism in cold worked Zr-2.5Nb, heat treated Zr-2.5Nb and zircaloy-2 pressure tubes

International Nuclear Information System (INIS)

Choi, Kwang Sik

1992-02-01

Cold worked Zr-2.5Nb, heat treated Zr-2.5Nb and Zircaloy-2 pressure tubes were hydrided to the hydrogen concentration of 68 ppm, 49 ppm and 242-411 ppm, respectively, and compact tension specimens were machined from the hydrided materials. The crack growth rate by delayed hydride cracking was measured by potential drop method at various temperatures on the above mentioned three types of specimens. The activation energy obtained were 43 KJ/mol for cold worked Zr-2.5Nb and 37 KJ/mol for heat treated Zr-2.5Nb, which were in good agreements with that of Coleman (1977), while they were lower than the activation energy of 65.5 KJ/mol obtained by Simpson-puls (1979) and 71.5 KJ/mol by Ambler (1984). The DHC growth rate in Zircaloy-2 were about one fifth of that of Zr-2.5Nb, which is due to the texture and material strength effects. Striations which indicate stepwise DHC growth were observed at fracture surface by scanning electron microscope and unsymmetric crack tunnellings were also observed, which seems to be due to the difference in hydrogen diffusion rate caused by the difference in stress fields between inner and outer surface. The comparison of test results with the DHC growth rate calculated by Simpson-puls model showed good agreement at high temperatures, whereas at the lower temperatures the crack growth rates were 2.5 times higher than the calculated values

Phase equilibria and crystal chemistry in the ternary system BaO-TiO 2-Nb 2O 5. II. New barium polytitanates with <5 mole% Nb 2O 5

Science.gov (United States)

Roth, R. S.; Ettlinger, L. D.; Parker, H. S.

1987-06-01

Four new compounds were found in the BaO-TiO 2-Nb 2O 5 system, each containing orth ≈ 9.9A˚, b mon ≈ a orth ≈ 17A˚). Ba 14Ti 40Nb 2O 99 is a 20-layer orthorhombic phase, Cmc*, withc ≈ 46.86A˚. Ba 10Ti 28Nb 2O 72 is a 7-layer monoclinic phase, C2m, c ≈ 16.72A˚, β ≈ 101.2°. Ba 18Ti 54Nb 2O 132 is a 13-layer monoclinic phase, C2m, c ≈ 30.65A˚, β ≈ 96°. The compositions were derived by analogy to the layers in Ba 4Ti 13 O 30 and Ba 6Ti 17O 40 and are consistent with limited phase equilibria data.

Atomic Defects and Doping of Monolayer NbSe2.

Science.gov (United States)

Nguyen, Lan; Komsa, Hannu-Pekka; Khestanova, Ekaterina; Kashtiban, Reza J; Peters, Jonathan J P; Lawlor, Sean; Sanchez, Ana M; Sloan, Jeremy; Gorbachev, Roman V; Grigorieva, Irina V; Krasheninnikov, Arkady V; Haigh, Sarah J

2017-03-28

We have investigated the structure of atomic defects within monolayer NbSe 2 encapsulated in graphene by combining atomic resolution transmission electron microscope imaging, density functional theory (DFT) calculations, and strain mapping using geometric phase analysis. We demonstrate the presence of stable Nb and Se monovacancies in monolayer material and reveal that Se monovacancies are the most frequently observed defects, consistent with DFT calculations of their formation energy. We reveal that adventitious impurities of C, N, and O can substitute into the NbSe 2 lattice stabilizing Se divacancies. We further observe evidence of Pt substitution into both Se and Nb vacancy sites. This knowledge of the character and relative frequency of different atomic defects provides the potential to better understand and control the unusual electronic and magnetic properties of this exciting two-dimensional material.

The system K2NbF7-K2TiF6-KCl

International Nuclear Information System (INIS)

Kamenskaya, L.A.; Matveev, A.M.

1984-01-01

Using visual-polythermal and thermographical methods the ternary system K 2 NbF 7 -K 2 TiE 6 -KCl has been studied. Crystallization fields of initial components and the field of solid solutions of double compounds K 3 NbClF 7 and K 3 TiClF 6 are outlined. Ternary eutectics at 654 deg C, having the composition K 2 NbF 6 -41, K 2 TiP 6 -41, KCl-18 mol.%, is determined. Potassium fluoroniobate and fluorotitanate form continuous solid solutions unstable in the presence of the third component, potassium chloride

Electrochemical conversion of solid Nb{sub 2}O{sub 5} to Nb in sodium chloride melt as proof of oxygen ionisation mechanism of electrodeoxidation

Energy Technology Data Exchange (ETDEWEB)

Sri Maha Vishnu, D., E-mail: smvd2@cam.ac.uk [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India); Presently with Materials Chemistry Group, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS (United Kingdom); Sanil, N.; Mohandas, K.S. [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India)

2016-08-25

The direct electrochemical reduction of a solid metal oxide (MO{sub x}) to metal (M) in calcium chloride melt (FFC Cambridge process) has been proposed to take place via. oxygen ionisation mechanism, MO{sub x} + 2xe{sup −} → M + xO{sup 2−}. However, generation of calcium metal and reduction of the oxide with it too becomes possible under the applied potential condition (3.1 V) of an FFC cell. The unique chemistry of calcium chloride melt, upon cathodic polarisation, makes it difficult to distinguish between the reduction by electrons and calcium metal. Hence in order to confirm the oxygen ionisation theory of electro-deoxidation, electrochemical deoxidation experiments were carried out with sintered Nb{sub 2}O{sub 5} pellet electrodes in molten sodium chloride at 1173 K. The pellets were found reduced to Nb metal. Sodiothermic reduction of Nb{sub 2}O{sub 5} is thermodynamically not feasible (Nb{sub 2}O{sub 5} + 10Na → 5Na{sub 2}O + 2Nb, ΔG°{sub 1173K} = 102.1 kJ) and hence the observed reduction of the oxide is attributed to electrons. This study, for the first time, gives reliable experimental evidence to the oxygen ionisation mechanism of electro-reduction of solid oxides in the FFC process. The experimental results also prove that the electro-reduction of oxides can occur in melts, which otherwise were considered unsuitable from thermodynamic considerations. - Highlights: • In NaCl melt: Negligible O{sup 2−} ion solubility & Na reduction of Nb{sub 2}O{sub 5} to Nb – absent. • Nb{sub 2}O{sub 5} could be electrochemically reduced to spongy Nb in NaCl melt at 1173 K. • Mechanism: Nb{sub 2}O{sub 5} → Na−Nb−O compounds + suboxides of Nb → Na{sub x}NbO{sub y} → Nb. • Metallothermic reduction of oxide in melt - not mandatory for electrodeoxidation. • In FFC Cambridge process: Metallothermic reduction is not essential but desirable.

Thermodynamics of superconducting Nb3Al, Nb3Ge, Nb3Sn, and V3Ga

Science.gov (United States)

Mitrović, B.; Schachinger, E.; Carbotte, J. P.

1984-06-01

We have calculated the superconducting thermodynamic properties for several high-transition-temperature A15 compounds: Nb-Al, Nb-Ge, Nb-Sn, and V-Ga. In our calculations we have used the tunneling electron-phonon-coupling spectra α2F for all four systems considered, and in the case of Nb-Al and Nb-Ge we have also used α2F=CG, where G is the measured generalized phonon density of states and C is a constant. We find that all Nb-based A15 compounds display similar thermodynamic properties, which do not depend explicitly on the band density of states: 2Δ0κBTc≅4.6, ΔCγTc≅2.5-2.6,-Tc[dHc(T)dT]TcHc(0)≅2.1, γ[TcHc(0)]2≅0.134, and positive D(t)'s with the maximum value around 0.02. For Nb3Sn we find good agreement between the calculated properties and the old specific-heat experimental results (γ≅52 mJ/mol K2). The same applies to V3Ga, where the theoretical results have been compared with the experiments of Junod et al. However, we do not find good agreement between calculated ΔCγTc, - Tc[dHc(T)dT]TcHc(0), γ[TcHc(0)]2, and experimental values for Nb3Al and Nb3Ge, presumably due to broadened transitions. It is argued that the tunneling experiments underestimate the value of the gap which should be associated with the inverted α2F.

New NbCd2 Phase in Niobium-Cadmium Coating Films

Science.gov (United States)

Volodin, V. N.; Tuleushev, Yu. Zh.; Zhakanbaev, E. A.; Tsai, K. V.; Rofman, O. V.

2018-02-01

Solid solutions in the form of alloy coatings have been obtained for the first time in the Cd concentration range of 64.5% using ion-plasma sputtering and the codeposition of Nb and Cd ultrafine particles. This supports thermal fluctuation melting and the coalescence of fine particles. A coating of niobium and cadmium layers less than 2 nm thick at 68 at % Cd results in the formation of a new phase identified as NbCd2. The tetragonal fcc phase with lattice parameters a = 0.84357 nm and c = 0.54514 nm forms directly during film coating. XRD data for the identification of the intermetallic compound have been determined. The thermal stability of the NbCd 2 intermetallic compound is limited by 200°C. The properties of the synthesized NbCd 2 phase are typical of semiconductors.

Pembrolizumab and Vorinostat in Treating Patients With Relapsed or Refractory Diffuse Large B-Cell Lymphoma, Follicular Lymphoma, or Hodgkin Lymphoma

Science.gov (United States)

2018-04-23

Grade 3a Follicular Lymphoma; Grade 3b Follicular Lymphoma; Recurrent Classical Hodgkin Lymphoma; Recurrent Diffuse Large B-Cell Lymphoma; Recurrent Follicular Lymphoma; Recurrent Grade 1 Follicular Lymphoma; Recurrent Grade 2 Follicular Lymphoma; Recurrent Mediastinal (Thymic) Large B-Cell Cell Lymphoma; Refractory Classical Hodgkin Lymphoma; Refractory Diffuse Large B-Cell Lymphoma; Refractory Follicular Lymphoma; Refractory Mediastinal (Thymic) Large B-Cell Cell Lymphoma

Critical state instability in Nb-clad MgB2 superconducting wires

International Nuclear Information System (INIS)

Beilin, V.; Felner, I.; Tsindlekht, M.I.; Dul'kin, E.; Mojaev, E.; Roth, M.

2008-01-01

Magnetization hysteresis loops of Cu/MgB 2 , Nb/MgB 2 , Cu/Nb/MgB 2 and Fe/Cu/MgB 2 wires in parallel magnetic fields of up to 5 T were studied in the temperature range from 5 to 35 K. All Nb-clad samples exhibited a thermomagnetic instability (TMI) in the form of magnetization jumps. In a thick wire (about 2 mm in core diameter), the TMI persisted up to the unexpectedly high temperature of 32 K. Thin wires showed low TMI which vanished at T > 10 K. Cu/MgB 2 wires which did not contain a Nb barrier, showed no signs of TMI. The TMI in thin wires exhibited good reproducibility and stability in the jump pattern (JP) (jump amplitudes and positions), while thick wires showed the worst time stability. We found that moderate flat rolling of the round unstable Cu/Nb/MgB 2 wire resulted in negligible TMI at 5 K in the processed flat tape. The TMI amplitudes of studied samples correlated with the adiabatic stability parameter, β -1

Effects of Nb content on the Zr2Fe intermetallic stability

International Nuclear Information System (INIS)

Ramos, C.; Saragovi, C.; Granovsky, M.; Arias, D.

2003-01-01

With the aim of studying the stability range of the Zr 2 Fe intermetallic when adding Nb, the range of existence of the cubic ternary phase (λ 1 ) and the corresponding two-phase field between them, four samples were analyzed, each one containing 35 at.% Fe and different at.% Nb: 0.5, 4 10 and 15. Optical and scanning electron metallographies, X-ray diffraction, microprobe analysis and Moessbauer spectroscopy were performed to determine and characterize the phases present in the samples. Results show that the Zr 2 Fe compound accepts up to nearly 0.5 at.% Nb in solution, since the Zr 2 Fe+λ 1 region is stable in the (0.5-3.5) at.% Nb range. To summarize these results an 800 deg. C section of the ternary Zr-Nb-Fe diagram, in the studied zone, was proposed

Isolation and structures of sulfonium salts derived from thioethers: [{o-C(6)H(4)(CH(2)SMe)(2)}H][NbF(6)] and [{[9]aneS(3)}H][NbF(6)].

Science.gov (United States)

Jura, Marek; Levason, William; Reid, Gillian; Webster, Michael

2009-10-07

Two very unusual sulfonium salts, [{o-C(6)H(4)(CH(2)SMe)(2)}H][NbF(6)] and [{[9]aneS(3)}H][NbF(6)], obtained from reaction of the thioethers with NbF(5) in CH(2)Cl(2) solution, are reported and their structures described; the eight-coordinate tetrafluoro Nb(v) cation of the dithioether is obtained from the same reaction.

Redetermination of AgNb2PS10 revealing a silver deficiency

Directory of Open Access Journals (Sweden)

Hoseop Yun

2009-08-01

Full Text Available In comparison with a previous crystallographic study [Goh et al. (2002. J. Solid State Chem. 168, 119–125] of the title compound, silver diniobium tris(disulfide tetrathiophosphate(V, that reports a full occupation of the silver position and isotropic displacement parameters for the atoms, the current redetermination reveals a silver deficiency with a site-occupation factor of 0.88 (1 and reports all atoms with anisotropic displacement parameters. The structure of Ag0.88Nb2PS10 is composed of ∞1[Nb2PS10] chains, which are built up from pairs of distorted bicapped trigonal-prismatic [NbS8] polyhedra forming [Nb2S12] dimers and of tetrahedral [PS4] groups. These chains are connected via the statistically disordered Ag+ ions, forming double layers. Adjacent layers are stacked solely through van der Waals forces into a three-dimensional structure. Short and long Nb—Nb distances [2.880 (1 and 3.770 (2 Å, respectively] alternate along the chain and S22− and S2− anionic species are observed.

In situ synthesis of NiAl–NbB2 composite powder through combustion synthesis

International Nuclear Information System (INIS)

Shokati, Ali Akbar; Parvin, Nader; Sabzianpour, Naser; Shokati, Mohammad; Hemmati, Ali

2013-01-01

Highlights: ► A Novel NiAl matrix composite powder with 0–40 wt.% NbB 2 was synthesized. ► Composite powders were synthesized by thermal explosion reaction of Ni–Al–Nb–B system. ► Microhardness of NiAl considerably increased with raising NbB 2 content. ► Synthesized composite powders is a good candidate as precursor for thermal barrier application. - Abstract: Synthesis of a novel NiAl matrix composite powder reinforced with 0–40 wt.% NbB 2 by combustion synthesis in thermal explosion mode was investigated. The elemental powders of Ni, Al, Nb, and amorphous boron were used as starting material. For all compositions final products consisted of only the NiAl and NbB 2 phases. Coarser NbB 2 with a relatively uniform distribution in NiAl matrix was formed with rising NbB 2 content. Microhardness of NiAl considerably increased from 377 ± 13 HV 0.05 to 866 ± 81 HV 0.05 for NiAl with 40 wt.% NbB 2 . High microhardness, proper size and distribution of NbB 2 in NiAl matrix make it a good candidate as precursor for thermal spray application.

Thermodynamics of superconducting Nb3Al, Nb3Ge, Nb3Sn, and V3Ga

International Nuclear Information System (INIS)

Mitrovic, B.; Schachinger, E.; Carbotte, J.P.

1984-01-01

We have calculated the superconducting thermodynamic properties for several high-transition-temperature A15 compounds: Nb-Al, Nb-Ge, Nb-Sn, and V-Ga. In our calculations we have used the tunneling electron-phonon--coupling spectra α 2 F for all four systems considered, and in the case of Nb-Al and Nb-Ge we have also used α 2 F = CG, where G is the measured generalized phonon density of states and C is a constant. We find that all Nb-based A15 compounds display similar thermodynamic properties, which do not depend explicitly on the band density of states: 2Δ 0 /k/sub B/T/sub c/approx. =4.6, ΔC/γT/sub c/approx. =2.5--2.6, -T/sub c/[dH/sub c/(T)/dT]c/ H/sub c/(0)approx. =2.1, γ[T/sub c//H/sub c/(0)] 2 approx. =0.134, and positive D(t)'s with the maximum value around 0.02. For Nb 3 Sn we find good agreement between the calculated properties and the old specific-heat experimental results (γapprox. =52 mJ/mol K 2 ). The same applies to V 3 Ga, where the theoretical results have been compared with the experiments of Junod et al. However, we do not find good agreement between calculated ΔC/γT/sub c/, -T/sub c/[dH/sub c/(T)/dT]c/H/sub c/(0), γ[T/sub c//H/sub c/(0)] 2 , and experimental values for Nb 3 Al and Nb 3 Ge, presumably due to broadened transitions. It is argued that the tunneling experiments underestimate the value of the gap which should be associated with the inverted α 2 F

Microstructural evolution and tensile behavior of Ti{sub 2}AlNb alloys based α{sub 2}-phase decomposition

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei, E-mail: gackmol@163.com [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Zeng, Weidong, E-mail: zengwd@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Li, Dong; Zhu, Bin; Zheng, Youping [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Liang, Xiaobo [Beijing Iron & Steel Research Institute, Beijing 100081 (China)

2016-04-26

The formation mechanism of the fine plate-like O-phases within α{sub 2}-phases and tensile behavior of an isothermally forged Ti–22Al–25Nb (at%) orthorhombic alloy at 1040 °C during heat treatment were investigated. The investigation indicated that the alloys were heat-treated in O+B2 phase region after α{sub 2}+B2 phase region isothermally forging, the equiaxed α{sub 2}-phase was not stable and decomposed into O+α{sub 2} phases. The α{sub 2} phases formed during isothermal forging process have higher concentration of Nb and begun to decompose during O+B2 phase region heat treatment. And then the α{sub 2} phases separated into Niobium-lean and Niobium-rich regions through the Niobium diffusion: α{sub 2}→α{sub 2} (Nb-lean)+O (Nb-rich). Nb-rich regions with composition similar to Ti{sub 2}AlNb transformed to the O-phase, while the Nb-lean regions remained untransformed and retained the α{sub 2}-phase. The deformation behavior and fracture mechanism of Ti–22Al–25Nb alloy at room temperature were discussed. The deformation behavior and microstructural evolution of this alloy at different temperatures and stain rates were also investigated using uniaxial tensile test.

Theoretical and experimental study of NbO2 nanoslice formation

International Nuclear Information System (INIS)

Music, Denis; Geyer, Richard W

2015-01-01

We have used reactive magnetron sputtering to form NbO 2 nanoslices. These unique nanostructures with the dominating diffractions peaks related to low surface energy NbO 2 planes are self-assembled into two different populations: aligned and random nanoslices. To provide an explanation for the formation of these NbO 2 nanoslices with respect to competitive growth of nanorods, we employed density functional theory based molecular dynamics. (1 1 0) and (0 0 1) surfaces together with the related nanoslices and nanorods were considered, corresponding to low and high surface energy configurations, respectively. For the (1 1 0) configuration, nanoslices are more stable at all temperatures (0 K–900 K), which is consistent with experimental observations. On the other hand, for the (0 0 1) configuration nanorods are more stable at and above room temperature. We suggest that the texture modulation is the physical origin of NbO 2 nanostructure formation. (paper)

Precipitation in Zr-2.5Nb enhanced by proton irradiation

Energy Technology Data Exchange (ETDEWEB)

Cann, C. D.; So, C. B.; Styles, R. C.; Coleman, C. E.

1993-08-15

A 3.6 MeV proton irradiation of annealed Zr-2.5Nb has been performed to determine whether proton irradiation will enhance the precipitation of Nb-rich {beta}-phase precipitates within the {alpha}-grains. a transmission electron microscope examination of a foil after irradiation at 770 K for 18 h and at 720 K for 264.5 h to a total damage of 0.94 dpa revealed a fine dispersion of precipitates within the {alpha}-grains. Electron diffraction analysis of the precipitates found they have lattice plane spacings consistent with the Nb-rich {beta}-phase. This result is in agreement with the {beta}phase precipitation observed following neutron irradiation, and thus it supports the use of proton irradiation to simulate neutron-irradiation effects in Zr-2.5Nb.

Precipitation in Zr-2.5Nb enhanced by proton irradiation

International Nuclear Information System (INIS)

Cann, C.D.; So, C.B.; Styles, R.C.; Coleman, C.E.

1993-08-01

A 3.6 MeV proton irradiation of annealed Zr-2.5Nb has been performed to determine whether proton irradiation will enhance the precipitation of Nb-rich β-phase precipitates within the α-grains. a transmission electron microscope examination of a foil after irradiation at 770 K for 18 h and at 720 K for 264.5 h to a total damage of 0.94 dpa revealed a fine dispersion of precipitates within the α-grains. Electron diffraction analysis of the precipitates found they have lattice plane spacings consistent with the Nb-rich β-phase. This result is in agreement with the βphase precipitation observed following neutron irradiation, and thus it supports the use of proton irradiation to simulate neutron-irradiation effects in Zr-2.5Nb

Novel transparent conducting oxide: Anatase Ti1-xNb xO2

International Nuclear Information System (INIS)

Furubayashi, Yutaka; Hitosugi, Taro; Yamamoto, Yukio; Hirose, Yasushi; Kinoda, Go; Inaba, Kazuhisa; Shimada, Toshihiro; Hasegawa, Tetsuya

2006-01-01

Single-crystalline Ti 1-x Nb x O 2 (x = 0.2) films of 40 nm thickness were deposited on SrTiO 3 (100) substrates by the pulsed laser deposition (PLD) technique. X-ray diffraction measurement confirmed epitaxial growth of anatase (001) film. The resistivity of Ti 1-x Nb x O 2 films with x ≥ 0.03 is 2-3 x 10 -4 Ω cm at room temperature. The carrier density of Ti 1-x Nb x O 2 , which is almost proportional to the Nb concentration, can be controlled in a range of 1 x 10 19 to 2 x 10 21 cm -3 . Optical measurements revealed that internal transmittance in the visible and near-infrared region for films with x = 0.03 was more than 97%. These results demonstrate that the presently developed anatase Ti 1-x Nb x O 2 is one of the promising candidates for the practical TCOs

Clinicopathological and genomic analysis of double-hit follicular lymphoma: comparison with high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements.

Science.gov (United States)

Miyaoka, Masashi; Kikuti, Yara Y; Carreras, Joaquim; Ikoma, Haruka; Hiraiwa, Shinichiro; Ichiki, Akifumi; Kojima, Minoru; Ando, Kiyoshi; Yokose, Tomoyuki; Sakai, Rika; Hoshikawa, Masahiro; Tomita, Naoto; Miura, Ikuo; Takata, Katsuyoshi; Yoshino, Tadashi; Takizawa, Jun; Bea, Silvia; Campo, Elias; Nakamura, Naoya

2018-02-01

Most high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements are aggressive B-cell lymphomas. Occasional double-hit follicular lymphomas have been described but the clinicopathological features of these tumors are not well known. To clarify the characteristics of double-hit follicular lymphomas, we analyzed 10 cases of double-hit follicular lymphomas and 15 cases of high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements for clinicopathological and genome-wide copy-number alterations and copy-neutral loss-of-heterozygosity profiles. For double-hit follicular lymphomas, the median age was 67.5 years (range: 48-82 years). The female/male ratio was 2.3. Eight patients presented with advanced clinical stage. The median follow-up time was 20 months (range: 1-132 months). At the end of the follow-up, 8 patients were alive, 2 patients were dead including 1 patient with diffuse large B-cell lymphoma transformation. Rearrangements of MYC/BCL2, MYC/BCL6, and MYC/BCL2/BCL6 were seen in 8, 1, and 1 cases, respectively. The partner of MYC was IGH in 6 cases. There were no cases of histological grade 1, 4 cases of grade 2, 5 cases of grade 3a, and 1 case of grade 3b. Two cases of grade 3a exhibited immunoblast-like morphology. Immunohistochemistry demonstrated 9 cases with ≥50% MYC-positive cells. There was significant difference in MYC intensity (P=0.00004) and MIB-1 positivity (P=0.001) between double-hit follicular lymphomas and high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements. The genome profile of double-hit follicular lymphomas was comparable with conventional follicular lymphomas (GSE67385, n=198) with characteristic gains of 2p25.3-p11.1, 7p22.3-q36.3, 12q11-q24.33, and loss of 18q21.32-q23 (Phit follicular lymphomas had fewer copy-number alterations and minimal common region of gain at 2p16.1 (70%), locus also significant against conventional follicular lymphomas (P=0.0001). In summary, double-hit follicular

Molten salt synthesis of ZnNb2O6 powder

International Nuclear Information System (INIS)

Guo Liangzhai; Dai Jinhui; Tian Jintao; Zhu Zhibin; He Tian

2007-01-01

Pure ZnNb 2 O 6 powder was successfully prepared by the molten salt synthesis method using Nb 2 O 5 and ZnO as raw materials and a mixture of NaCl and KCl as the solvent. The phase form and morphology of the prepared powder were characterized by X-ray diffraction and scanning electron microscopy. The effect of reacting temperature on phase formation was investigated. The results indicated that the single phase ZnNb 2 O 6 powder can be obtained by the molten salt synthesis method at 600 deg. C, and the SEM photographs show that the grains of the powder are rod-like particles

Production of superconducting Nb3Sn wire using Nb or Nb(Ti) and Sn(Ga) solid solution powders

International Nuclear Information System (INIS)

Thieme, C.L.H.; Foner, S.

1991-01-01

This paper reports on superconducting Nb 3 Sn wire produced by the powder metallurgy method using Nb or Nb-2.9 at% Ti powder in combination with Sn-x at% Ga powders (x = 3, 4.2, 6.2 and 9.0). Ga additions to the Sn caused considerable solid solution hardening which improved its workability. It made the Nb-Sn(Ga) powder combinations convenient for swaging and extensive wire drawing. Anneals at 950 degrees C produced wires with an overall J c of 10 4 A/cm 2 at 21.9 T for wires with both Ti in the Nb and 6.2 at% Ga in the Sn. Comparison of this wire with the best Nb(Ti)-Cu-internal Sn(Ti) shows a higher J c per A15 areas, especially in fields of 22T and above

Stress corrosion of the alloy U-7.5 Nb-2.5 Zr

International Nuclear Information System (INIS)

Lepoutre, D.; Nomine, A.M.; Miannay, D.

1983-09-01

Oxide formed on U-7.5 Nb-2.5 Zr at room temperature during stress corrosion cracking in oxygen is identical to the natural oxide of the alloy. It is formed by UO 2 with Nb and Zr and is associated with an increased Nb content at the interface. This oxide would be responsible for cracking [fr

Corrosion of electron-irradiated Zr-2.5Nb and Zircaloy-2

International Nuclear Information System (INIS)

Woo, O.-T.; McDougall, G.M.; Hutcheon, R.M.; Urbanic, V.F.; Griffiths, M.; Coleman, C.E.

2000-01-01

We used 10-MeV electrons to rapidly produce radiation damage in zirconium alloys, investigated whether electrons produced the same microstructural changes as neutrons, then performed post-irradiation corrosion tests to determine whether electron-irradiated materials displayed similar corrosion behavior to neutron-irradiated materials. Two irradiations were completed using 10-MeV electrons with the beam normal to thin disks of material of 4 diameter slightly larger than the beam. The beam distribution. and disk cooling were designed to produce radial temperature and dose distributions having maxima at the disk center. A high-temperature irradiation was performed on annealed Zr-2.5Nb disks, achieving a central dose of 1.3 dpa and at a central temperature of ∼450 deg C. After irradiation, the samples contained needle-like β-Nb precipitates in the α-Zr matrix similar to those produced by neutrons. A low-temperature irradiation was performed on half-moon disks of Zr-2.5Nb and Zircaloy-2 pressure tube materials at 310 deg C central temperature and 1.3-dpa central dose. Dislocation loops were observed, again similar to those produced in neutron-irradiated materials. Some of the high-temperature electron-irradiated disks were exposed to 300 deg C moist air (saturated with D 2 O), and in separate tests, high- and low-temperature irradiated disks were corroded in 300 deg C D 2 0 (11.0 pD at room temperature) in an autoclave. Measurements of oxide thickness by Fourier Transform Infrared Reflectance (FTIR) spectroscopy showed that electron irradiation reduced the corrosion rate of Zr-2.5Nb compared with that of unirradiated material, as observed for neutron irradiation. For exposures to moist air and to D 2 O, the theoretical deuterium uptakes for the electron-irradiated materials were, respectively, about 4 times and 1.5 to 2 times those for the unirradiated materials. This is also in good agreement with results for neutron-irradiated pressure tube materials. Thus, 10-Me

Structure of TeO2 - LiNbO3 glasses

Science.gov (United States)

Shinde, A. B.; Krishna, P. S. R.; Rao, Rekha

2017-05-01

Tellurite based lithium niobate glasses with composition (100-x)TeO2-xLiNbO3 (x=0.1,0.2 & 0.3) were prepared by conventional melt quenching method. The microscopic structural investigation of these glasses is carried out by means of neutron diffraction and Raman scattering measurements. It is found that the basic structural units in these glasses are TeO4 trigonal bipyramids(TBP), TeO3 trigonal pyramids(TP) and NbO6 Octahedra depending on the composition. It is evident from Raman studies that TBPs decreases, TPs increases and NbO6 Octahedra increases with increasing x. From Neutron diffraction studies it is found that network is comprised of TBPs and TPs along with TeO3+1 structural units. Distorted NbO6 octahedral units are present and also increase with the increase in x.

Phase relations, crystal structure, and phase transformation of In_1_−_xNb_1_−_xTi_2_xO_4 (0 ≤ x < 0.45) in In_2O_3–Nb_2O_5–TiO_2 system

International Nuclear Information System (INIS)

Su, Liumei; Fan, Xing; Cai, Gemei; Liu, Huashan; Jin, Zhanpeng

2015-01-01

Phase relations, crystal structures, and phase transformation of In_1_−_xNb_1_−_xTi_2_xO_4 (0 ≤ x < 0.45) in In_2O_3–Nb_2O_5–TiO_2 ternary system were investigated for the first time. A number of samples with different compositions were prepared by a solid-state reaction method, and phase assembles were analyzed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe micro-analysis (EPMA). Five three-phase regions, ten two-phase regions, and six single-phase solid solutions were determined in this system. The solid solution of In_1_−_xNb_1_−_xTi_2_xO_4 (0 ≤ x < 0.45) is composed of both ordered monoclinic wolframite-type structure (0 ≤ x < 0.35) and disordered orthorhombic α-PbO_2 type structure (0.35 < x < 0.45). Driving force for composition-driven phase transformation in In_1_−_xNb_1_−_xTi_2_xO_4 (0 ≤ x < 0.45) stems from the ordering of cations. The ever reported compound InNbTiO_6 with an orthorhombic α-PbO_2 type structure was amended to be a monoclinic wolframite-type structure. Present investigations will be useful for the whole ceramic community working with In_2O_3–Nb_2O_5–TiO_2 ternary system as well as for the development of functional materials. - Highlights: • Phase relations of In_2O_3–Nb_2O_5–TiO_2 ternary system were constructed. • Crystal structures of a novel solid solution In_1_−_xNb_1_−_xTi_2_xO_4 were determined. • Crystal structure of InNbTiO_6 was amended to be a wolframite-type structure. • Composition-driven phase transformation of In_1_−_xNb_1_−_xTi_2_xO_4 was investigated.

Functionalized NbS2 as cathode for Li- and Na-ion batteries

KAUST Repository

Zhu, Jiajie

2017-07-27

Cathodes of Li- and Na-ion batteries usually have capacities <200 mAh/g, significantly less than the anodes. Two-dimensional materials can overcome this limitation but suffer from low voltages. In this context, we investigate NbS2 functionalized by O, F, and Cl as a cathode material by first-principles calculations, considering both the conversion and intercalation mechanisms. NbS2O2 shows a higher voltage than NbS2 for both Li and Na, but the voltage decreases drastically for increasing ion coverage. Even higher voltages and favorable dependences on the ion coverage are achieved by F and Cl functionalization. We obtain NbS2F2 and NbS2Cl2 energy densities of 1223 mW h/g and 823 mW h/g for lithiation and 1086 mW h/g and 835 mW h/g for sodiation, respectively. These values are higher than those for most state-of-the-art cathode materials (∼600 mW h/g). In addition, low diffusion barriers enable high cycling rates.

Functionalized NbS2 as cathode for Li- and Na-ion batteries

KAUST Repository

Zhu, Jiajie; Alshareef, Husam N.; Schwingenschlö gl, Udo

2017-01-01

Cathodes of Li- and Na-ion batteries usually have capacities <200 mAh/g, significantly less than the anodes. Two-dimensional materials can overcome this limitation but suffer from low voltages. In this context, we investigate NbS2 functionalized by O, F, and Cl as a cathode material by first-principles calculations, considering both the conversion and intercalation mechanisms. NbS2O2 shows a higher voltage than NbS2 for both Li and Na, but the voltage decreases drastically for increasing ion coverage. Even higher voltages and favorable dependences on the ion coverage are achieved by F and Cl functionalization. We obtain NbS2F2 and NbS2Cl2 energy densities of 1223 mW h/g and 823 mW h/g for lithiation and 1086 mW h/g and 835 mW h/g for sodiation, respectively. These values are higher than those for most state-of-the-art cathode materials (∼600 mW h/g). In addition, low diffusion barriers enable high cycling rates.

Improvement of the phase diagram for the pseudobinary PbNb2O6-BaNb2O6 system

International Nuclear Information System (INIS)

Venet, M.; Zabotto, F. L.; Eiras, J. A.; Garcia, D.

2009-01-01

Characteristics of phase transitions of lead barium niobate compositions around the morphotropic phase boundary were investigated. Using structural characterizations, it was found that the morphotropic phase boundary extends toward a wide composition range, in which both tetragonal (4mm) and orthorhombic (m2m) tungsten bronze phases coexist. In addition, on heating, two phase transitions were observed for all the studied compositions. First, the fraction with m2m symmetry phase transforms into the 4mm symmetry one and, second, the 4mm symmetry phase, which represents the whole material, transforms into the paraelectric phase (4/mmm symmetry). The phase transition temperatures were determined from dielectric characterizations. These results helped to improve the phase diagram of the pseudobinary PbNb 2 O 6 -BaNb 2 O 6 system around the morphotropic phase boundary region.

Determination of Nb and Zr in U-Nb-Zr alloys by ICP-AES

International Nuclear Information System (INIS)

Wang Cuiping; Dong Shizhe; Li Lin; He Meiying

2003-01-01

The U-Nb-Zr alloy sample is dissolved by HNO 3 , H 2 O 2 and HF, and the contents of Nb and Zr in the sample are determined on the JY-70 II type ICP-AES by using the internal standard synchronous dilution method. The range of determination is 1%-10% and 0.33%-3.33%, respectively for Nb and Zr. The relative standard deviation is better than 3.2% for Nb, and 2.5% for Zr. The method is rapid and convenient for determining Nb and Zr in U-Nb-Zr alloy sample

Phase stability in the Nb-rich region of the Nb-B-Si system

Energy Technology Data Exchange (ETDEWEB)

Nunes, C.A.; Coelho, G.C.; Pinto, D.M. Jr.; Camargo Gandolpho, K.C. de; Borges, L.A. Jr.; Rodrigues, G. [Polo Urbo-Ind., Gleba, Lorena (Brazil). Dept. de Engenharia de Materiais

2000-07-01

Alloys of the Me-B-Si systems (Me-refractory metal) have been evaluated due to their potential for use as high temperature structural materials (T>1400 C). In the present study, the phase stability in the Nb-rich region of the Nb-B-Si system has been evaluated in terms of the current information associated to the Nb-Si, Nb-B and Nb-B-Si systems as well as our own data. For the experiments several as-cast and heat-treated alloys of the Nb-B and Nb-B-Si systems were investigated by X-ray diffraction and scanning electron microscopy. Concerning the Nb-B system the results indicated the existence of the eutectic reaction L ({proportional_to} 16 at%B) <=> Nb{sub ss}+NbB. The Nb{sub 3}B{sub 2} phase was not observed in the microstructure of as-cast alloys with composition in the range of 0 to 50 at%B. The analysis of heat-treated ternary alloys at 1600 C and 1750 C confirmed the existence of the Nb{sub ss}+T{sub 2} two-phase field at those temperatures. This T{sub 2}-phase is isomorphous of the {alpha}Nb{sub 5}Si{sub 3} and is formed through the partial substitution of Si atomos for B atoms in the lattice of the {alpha}Nb{sub 5}Si{sub 3}-phase. All ternary alloys prepared in the present study presented either Nb{sub ss} or T{sub 2} primary phases in the as-cast microstructures. In addition, those alloys presented an eutectic-like microstructure formed by the Nb{sub ss} and T{sub 2} phases in the interdendritic region. (orig.)

Structural and vibrational investigations of Nb-doped TiO2 thin films

International Nuclear Information System (INIS)

Uyanga, E.; Gibaud, A.; Daniel, P.; Sangaa, D.; Sevjidsuren, G.; Altantsog, P.; Beuvier, T.; Lee, Chih Hao; Balagurov, A.M.

2014-01-01

Highlights: • We studied the evolutions of structure for TiO 2 thin film as changes with Nb doping and temperatures. • Up to 800 °C, the grain size of Nb 0.1 Ti 0.9 O 2 is smaller than for pure TiO 2 because doped Nb hinders the growth of the TiO 2 grains. • There was no formation of the rutile phase at high temperature. • Nb doped TiO 2 films have high electron densities at 400–700 °C. • Nb dope extends the absorbance spectra of TiO 2 which leads to the band gap reduce. - Abstract: Acid-catalyzed sol–gel and spin-coating methods were used to prepare Nb-doped TiO 2 thin film. In this work, we studied the effect of niobium doping on the structure, surface, and absorption properties of TiO 2 by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray reflectometry (XRR), X-ray photoelectron spectroscopy (XPS), Raman, and UV–vis absorption spectroscopy at various annealing temperatures. EDX spectra show that the Nb:Ti atomic ratios of the niobium-doped titania films are in good agreement with the nominal values (5 and 10%). XPS results suggest that charge compensation is achieved by the formation of Ti vacancies. Specific niobium phases are not observed, thus confirming that niobium is well incorporated into the titania crystal lattice. Thin films are amorphous at room temperature and the formation of anatase phase appeared at an annealing temperature close to 400 °C. The rutile phase was not observed even at 900 °C (XRD and Raman spectroscopy). Grain sizes and electron densities increased when the temperature was raised. Nb-doped films have higher electron densities and lower grain sizes due to niobium doping. Grain size inhibition can be explained by lattice stress induced by the incorporation of larger Nb 5+ ions into the lattice. The band gap energy of indirect transition of the TiO 2 thin films was calculated to be about 3.03 eV. After niobium doping, it decreased to 2.40 eV

Irradiation effects on Zr-2.5Nb in power reactors

Energy Technology Data Exchange (ETDEWEB)

Song, C., E-mail: Carol.Song@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

2016-06-15

Zirconium alloys are widely used as structural materials in nuclear applications because of their attractive properties such as a low absorption cross-section for thermal neutrons, excellent corrosion resistance in water, and good mechanical properties at reactor operating temperatures. Zr-2.5Nb is one of the most commonly used zirconium alloys and has been used for pressure tube materials in CANDU (Canada Deuterium Uranium) and RBMK (Reaktor Bolshoy Moshchnosti Kanalnyy, 'High Power Channel-type Reactor') reactors for over 40 years. In a recent report from the Electric Power Research Institute, Zr-2.5Nb was identified as one of the candidate materials for use in normal structural applications in light-water reactors owing to its increased resistance to irradiation-induced degradation as compared with currently used materials. Historically, the largest program of in-reactor tests on zirconium alloys was performed by Atomic Energy of Canada Limited. Over many years of in-reactor testing and CANDU operating experience with Zr- 2.5Nb, extensive research has been conducted on the irradiation effects on its microstructures, mechanical properties, deformation behaviours, fracture toughness, delayed hydride cracking, and corrosion. Most of the results on Zr-2.5Nb obtained from CANDU experience could be used to predict the material performance under light water reactors. This paper reviews the irradiation effects on Zr-2.5Nb in power reactors (including heavy-water and light-water reactors) and summarizes the current state of knowledge. (author)

Development and application of graphite-SiO2/Al2O3/Nb2O5-methylene blue (GRP-SiAlNb-MB composite for electrochemical determination of dopamine

Directory of Open Access Journals (Sweden)

Juliana de Fátima Giarola

2017-03-01

Full Text Available In the present paper an amperometric sensor based on graphite-SiO2/Al2O3/Nb2O5-methylene blue (GRP-SiAlNb-MB composite has been successfully prepared for dopamine (DA determination in real samples. The electrochemical behavior of DA at the GRP-SiAlNb-MB has been evaluated by employing cyclic voltammetry. The best ratio (m/m of GRP-SiAlNb-MB composite was found to be 1:0.54. Under optimized conditions (pH 7.5 in 0.15 mol L−1 phosphate buffer the amperometry method responds linearly to DA from 5.0 up to 500.0 μmol L−1 (r = 0.995 with limits of detection and quantification of 1.49 and 4.97 μmol L−1, respectively. The developed method was successfully applied for DA determination in real samples of pharmaceutical formulations and can be used for routine quality control analysis of pharmaceutical formulations containing DA. The use of inorganic matrix SiAlNb was found to be very useful to adsorb MB in the composite material with further improvement of the anodic peak current of DA.

Effects of Nb content on the Zr{sub 2}Fe intermetallic stability

Energy Technology Data Exchange (ETDEWEB)

Ramos, C. E-mail: ciramos@cnea.gov.ar; Saragovi, C.; Granovsky, M.; Arias, D

2003-02-01

With the aim of studying the stability range of the Zr{sub 2}Fe intermetallic when adding Nb, the range of existence of the cubic ternary phase ({lambda}{sub 1}) and the corresponding two-phase field between them, four samples were analyzed, each one containing 35 at.% Fe and different at.% Nb: 0.5, 4 10 and 15. Optical and scanning electron metallographies, X-ray diffraction, microprobe analysis and Moessbauer spectroscopy were performed to determine and characterize the phases present in the samples. Results show that the Zr{sub 2}Fe compound accepts up to nearly 0.5 at.% Nb in solution, since the Zr{sub 2}Fe+{lambda}{sub 1} region is stable in the (0.5-3.5) at.% Nb range. To summarize these results an 800 deg. C section of the ternary Zr-Nb-Fe diagram, in the studied zone, was proposed.

Cr3+ and Nb5+ co-doped Ti2Nb10O29 materials for high-performance lithium-ion storage

Science.gov (United States)

Yang, Chao; Yu, Shu; Ma, Yu; Lin, Chunfu; Xu, Zhihao; Zhao, Hua; Wu, Shunqing; Zheng, Peng; Zhu, Zi-Zhong; Li, Jianbao; Wang, Ning

2017-08-01

Ti2Nb10O29 is an advanced anode material for lithium-ion batteries due to its large specific capacity and high safety. However, its poor electronic/ionic conductivity significantly limits its rate capability. To tackle this issue, a Cr3+-Nb5+ co-doping is employed, and a series of CrxTi2-2xNb10+xO29 compounds are prepared. The co-doping does not change the Wadsley-Roth shear structure but increases the unit-cell volume and decreases the particle size. Due to the increased unit-cell volumes, the co-doped samples show increased Li+-ion diffusion coefficients. Experimental data and first-principle calculations reveal significantly increased electronic conductivities arising from the formation of impurity bands after the co-doping. The improvements of the electronic/ionic conductivities and the smaller particle sizes in the co-doped samples significantly contribute to improving their electrochemical properties. During the first cycle at 0.1 C, the optimized Cr0.6Ti0.8Nb10.6O29 sample delivers a large reversible capacity of 322 mAh g-1 with a large first-cycle Coulombic efficiency of 94.7%. At 10 C, it retains a large capacity of 206 mAh g-1, while that of Ti2Nb10O29 is only 80 mAh g-1. Furthermore, Cr0.6Ti0.8Nb10.6O29 shows high cyclic stability as demonstrated in over 500 cycles at 10 C with tiny capacity loss of only 0.01% per cycle.

Temperature evolution of subharmonic gap structures in MgB{sub 2}/Nb point-contacts

Energy Technology Data Exchange (ETDEWEB)

Giubileo, F. [CNR-INFM Laboratorio Regionale SUPERMAT e Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, via Salvador Allende, 84081 Baronissi (Italy)], E-mail: giubileo@sa.infn.it; Bobba, F.; Scarfato, A.; Piano, S. [CNR-INFM Laboratorio Regionale SUPERMAT e Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, via Salvador Allende, 84081 Baronissi (Italy); Aprili, M. [Laboratoire de Spectroscopie en Lumiere Polarisee, ESPCI, 10 rue Vauquelin, 75005 Paris (France); CSNSM-CNRS, Bat. 108 Universite Paris-Sud, 91405 Orsay (France); Cucolo, A.M. [CNR-INFM Laboratorio Regionale SUPERMAT e Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, via Salvador Allende, 84081 Baronissi (Italy)

2007-09-01

We have performed point-contact spectroscopy experiments on superconducting micro-constrictions between Nb tips and high quality MgB{sub 2} pellets. We measured the temperature evolution (between 4.2 K and 300 K) of the current-voltage (I-V) and of the dynamical conductance (dI/dV-V) characteristics. Above the Nb critical temperature T{sub C}{sup Nb}, the conductance of the constrictions behaves as predicted by the BTK model for S/N contacts being Nb in its normal state below T{sub C}{sup Nb}, the contacts show Josephson current and subharmonic gap structures, due to multiple Andreev reflections. These observations clearly indicate the coupling of the MgB{sub 2} 3D {pi}-band with the Nb superconducting order parameter. We found {delta}{sub {pi}} = 2.4 {+-} 0.2 meV for the three-dimensional gap of MgB{sub 2}.

Corrosion of electron-irradiated Zr-2.5Nb and Zircaloy-2

Energy Technology Data Exchange (ETDEWEB)

Woo, O.-T.; McDougall, G.M.; Hutcheon, R.M.; Urbanic, V.F.; Griffiths, M.; Coleman, C.E

2000-07-01

We used 10-MeV electrons to rapidly produce radiation damage in zirconium alloys, investigated whether electrons produced the same microstructural changes as neutrons, then performed post-irradiation corrosion tests to determine whether electron-irradiated materials displayed similar corrosion behavior to neutron-irradiated materials. Two irradiations were completed using 10-MeV electrons with the beam normal to thin disks of material of 4 diameter slightly larger than the beam. The beam distribution. and disk cooling were designed to produce radial temperature and dose distributions having maxima at the disk center. A high-temperature irradiation was performed on annealed Zr-2.5Nb disks, achieving a central dose of 1.3 dpa and at a central temperature of {approx}450 deg C. After irradiation, the samples contained needle-like {beta}-Nb precipitates in the {alpha}-Zr matrix similar to those produced by neutrons. A low-temperature irradiation was performed on half-moon disks of Zr-2.5Nb and Zircaloy-2 pressure tube materials at 310 deg C central temperature and 1.3-dpa central dose. Dislocation loops were observed, again similar to those produced in neutron-irradiated materials. Some of the high-temperature electron-irradiated disks were exposed to 300 deg C moist air (saturated with D{sub 2}O), and in separate tests, high- and low-temperature irradiated disks were corroded in 300 deg C D{sub 2}0 (11.0 pD at room temperature) in an autoclave. Measurements of oxide thickness by Fourier Transform Infrared Reflectance (FTIR) spectroscopy showed that electron irradiation reduced the corrosion rate of Zr-2.5Nb compared with that of unirradiated material, as observed for neutron irradiation. For exposures to moist air and to D{sub 2}O, the theoretical deuterium uptakes for the electron-irradiated materials were, respectively, about 4 times and 1.5 to 2 times those for the unirradiated materials. This is also in good agreement with results for neutron-irradiated pressure

Quadruple-layered perovskite (CuCl)Ca2NaNb4O13

International Nuclear Information System (INIS)

Kitada, A.; Tsujimoto, Y.; Yamamoto, T.; Kobayashi, Y.; Narumi, Y.; Kindo, K.; Aczel, A.A.; Luke, G.M.; Uemura, Y.J.; Kiuchi, Y.; Ueda, Y.; Yoshimura, K.; Ajiro, Y.; Kageyama, H.

2012-01-01

We will present the synthesis, structure and magnetic properties of a new quadruple-layered perovskite (CuCl)Ca 2 NaNb 4 O 13 . Through a topotactic ion-exchange reaction with CuCl 2 , the precursor RbCa 2 NaNb 4 O 13 presumably having an incoherent octahederal tliting changes into (CuCl)Ca 2 NaNb 4 O 13 with a 2a p ×2a p ×2c p superstructure (tetragonal; a=7.73232(5) Å, c=39.2156(4) Å). The well-defined superstructure for the ion-exchanged product should be stabilized by the inserted CuCl 4 O 2 octahedral layers that firmly connect with neighboring perovskite layers. Magnetic studies show the absence of long-range magnetic ordering down to 2 K despite strong in-plane interactions. Aleksandrov′s group theory and Rietveld refinement of synchrotron X-ray diffraction data suggest the structure to be of I4/mmm space group with in-phase tilting along the a and b axes, a two-tilt system (++0). - Graphical Abstract: We present a quadruple-layered copper oxyhalide (CuCl)Ca 2 NaNb 4 O 13 synthesized through a topotactic ion-exchange reaction of RbCa 2 NaNb 4 O 13 with CuCl 2 . The compound has a well-defined superstructure. Magnetic studies suggest the absence of magnetic order even at 2 K. Highlights: ► (CuCl)Ca 2 NaNb 4 O 13 was prepared by ion-exchange reaction of RbCa 2 NaNb 4 O 13 with CuCl 2 . ► Compound has a 2a p ×2a p ×2c p superstructure (tetragonal; a=7.73 Å, c=39.21 Å). ► Such a well-defined superstructure was not observed in the precursor compound. ► Aleksandrov′s theory and Rietveld study suggest a (++0) octahedral tilting (I4/mmm). ► Magnetic studies revealed the absence of magnetic order down to 2 K.

Metal-metal bonding and aromaticity in [M2(NHCHNH)3]2 (μ-E)2 (E = O, S; M = Nb, Mo, Tc, Ru, Rh).

Science.gov (United States)

Yan, Xiuli; Meng, Lingpeng; Sun, Zheng; Li, Xiaoyan

2016-02-01

The nature of M-M bonding and aromaticity of [M2(NHCHNH)3]2(μ-E)2 (E = O, S; M = Nb, Mo, Tc, Ru, Rh) was investigated using atoms in molecules (AIM) theory, electron localization function (ELF), natural bond orbital (NBO) and molecular orbital analysis. These analyses led to the following main conclusions: in [M2(NHCHNH)3]2(μ-E)2 (E = O, S; M = Nb, Mo, Tc, Ru, Rh), the Nb-Nb, Ru-Ru, and Rh-Rh bonds belong to "metallic" bonds, whereas Mo-Mo and Tc-Tc drifted toward the "dative" side; all these bonds are partially covalent in character. The Nb-Nb, Mo-Mo, and Tc-Tc bonds are stronger than Ru-Ru and Rh-Rh bonds. The M-M bonds in [M2(NHCHNH)3]2(μ-S)2 are stronger than those in [M2(NHCHNH)3]2(μ-O)2 for M = Nb, Mo, Tc, and Ru. The NICS(1)ZZ values show that all of the studied molecules, except [Ru2(NHCHNH)3]2(μ-O)2, are aromaticity molecules. O-bridged compounds have more aromaticity than S-bridged compounds. Graphical Abstract Left Molecular graph, and right electron localization function (ELF) isosurface of [M2(NHCHNH)3]2(μ-E)2(E = O, S; M = Nb, Mo, Tc, Ru, Rh).

Dielectric properties of the ternary TeO2/Nb2O5/ZnO glasses

International Nuclear Information System (INIS)

Ahmad, Mohamad M.; Yousef, El Sayed; Moustafa, El Sayed

2006-01-01

Glasses of the system TeO 2 /Nb 2 O 5 /ZnO containing different concentration of ZnO (ranging from 5 to 20 mol%) were prepared. The dielectric properties over wide ranges of frequencies and temperatures were investigated as a function of ZnO content by impedance spectroscopy measurements. The impedance spectra of the present glasses were modeled by appropriate equivalent circuit. The dielectric constant has a value of 66 for the 85TeO 2 /10Nb 2 O 5 /5ZnO glass, which is three times larger than that of pure TeO 2 glass and other binary, e.g. TeO 2 /ZnCl 2 , tellurite glassy systems. The results have been analyzed in light of varying NbO 6 octahedra and NbO 4 tetrahedra of niobium oxide as zinc oxide varies from 5 to 20 mol%. The relaxation properties of the investigated glasses are presented in the electric modulus formalism, where the relaxation time and the respective activation energy are determined

Intercalation compounds of NbSe2 und SnSe2. Model systems for low-dimensional superconductors

International Nuclear Information System (INIS)

Herzinger, Michael

2013-01-01

Quasi-two-dimensional (2D) metal dichalcogenides have received considerable research interest since their complex anisotropic electronic properties can be controlled by the intercalation of donor species. Although layered dichalcogenides have been studied by many aspects of chemical and physical properties, their two-dimensional character is only poorly understood. The present work deals with the layer-shaped dichalcogenides SnSe 2 and NbSe 2 . The host-material SnSe 2 was synthesized by chemical transport with Iodine as transport agent in sealed quartz ampoules. The intercalation of the semiconducting layered single crystals SnSe 2 with the organometallic compound cobaltocene (CoCp 2 ) leads to superconductivity up to T = 8 K. Ex-situ intercalation studies show an intercalation-mechanism outgoing from the host material 2H-SnSe 2 in a stage-2 phase which goes over in a stage-1 phase for higher intercalation degrees. In addition, SnSe 2 {CoCp 2 } x show remarkable low-temperature properties e.g. the coexistence of superconductivity and magnetism in dependence of the staging and cobaltocene-content of the material. Starting from an intercalation degree of 17% CoCp 2 long range ordered magnetism (with increasing saturation magnetization) was observed in 18R-SnSe 2 {CoCp 2 } x . Furthermore SnSe 2 {CoCp 2 } x show an extremely sensitive superconducting pinning behavior in very small magnetic fields partially below B 2 -content. A phase diagram was developed in dependence of the degree of intercalation over the whole range of intercalation between 0 % and 33 %. For comparison of the low-temperature character of SnSe 2 {CoCp 2 } x , another layer-shaped superconductor NbSe 2 was intercalated with CoCp 2 . The layered high-k s-wave superconductor 2H-NbSe 2 belongs to the most prominent low-dimensional materials studied during the past fifty years. After the discovery of the high temperature superconductor MgB 2 , a benchmark system for multi-band superconductivity, NbSe 2

Nuclear orientation of 9597Nb and 95Zr in ZrFe2

International Nuclear Information System (INIS)

Krane, K.S.; Olsen, C.E.; Rosenblum, S.S.; Steyert, W.A.

1976-01-01

The angular distribution anisotropies of γ rays were measured following the decays of 95 , 97 Nb and 95 Zr oriented at low temperatures in the ferromagnetic Laves phase compound ZrFe 2 . The magnetic hyperfine field of Nb in ZrFe 2 was deduced to be 9.4+-1.6 T; that of Zr in ZrFe 2 was estimated to be 15+-4 T. The nuclear magnetic moment of 97 Nb was deduced to be μ = (7.5+-1.4) μ/subN/

Vibrational modes and Structure of Niobium(V) Oxosulfato Complexes in the Molten Nb2O5-K2S2O7-K2SO4 System Studied by Raman Spectroscopy

DEFF Research Database (Denmark)

Paulsen, Andreas L.; Borup, Flemming; Berg, Rolf W.

2010-01-01

The structural and vibrational properties of NbV oxosulfato complexes formed in Nb2O5-K2S2O7 and Nb2O5-K2S2O7-K2SO4 molten mixtures with 0 ... for the binary Nb2O5-K2S2O7 molten system indicate that the dissolution of Nb2O5 proceeds with consumption of S2O7 leading to the formation of a NbV oxosulfato complex according to Nb2O5 + nS2O7 --> C2n-; a simple formalism exploiting the relative Raman band intensities is used for determining the stoichiometric...... coefficient, n, pointing to n = 3 and to the following reaction: Nb2O5 + 3S2O7 --> 2NbO(SO4)3, which is consistent with the Raman spectra of the molten mixtures. Nb2O5 could be dissolved much easier when K2SO4 was present in an equimolar (1:1) SO4/Nb ratio; the incremental presence of K2SO4 in Nb2O5-K2S2O7...

Tribological properties of copper-based composites with copper coated NbSe2 and CNT

International Nuclear Information System (INIS)

Chen, Beibei; Yang, Jin; Zhang, Qing; Huang, Hong; Li, Hongping; Tang, Hua; Li, Changsheng

2015-01-01

Graphical abstract: Morphology of copper coated NbSe 2 and CNT; friction coefficient and wear rate of copper-based composites. - Highlights: • NbSe 2 and CNT were coated with copper layers by the means of electroless plating. • The mechanical and tribological properties of copper composites were studied. • The enhancement mechanisms of copper coated NbSe 2 and CNT were proposed. • Copper–copper coated (12 wt.%NbSe 2 –3 wt.%CNT) composite had the best wear resistance. - Abstract: Copper-based composites with copper coated NbSe 2 and/or CNT were fabricated by the powder metallurgy technique. The morphology and phase composition of copper coated NbSe 2 and carbon nanotube (CNT) were observed using high solution transmission electronic microscope (HRTEM), scanning electronic microscope (SEM equipped with EDS) and X-ray diffraction (XRD). The density, hardness, and bending strength of as-prepared copper-based composites were measured, and their tribological properties were investigated using UMT-2 tester. Results indicated that all copper-based composites showed decreased density and bending strength, but increased hardness in comparison with copper matrix. Besides, the incorporation of copper coated NbSe 2 improved the friction-reducing and anti-wear properties of copper matrix. Addition of copper coated CNT greatly enhanced the mechanical and tribological properties. In particular, when the content of copper coated CNT was 3 wt.%, the corresponding composite exhibited the best tribological properties. This was because NbSe 2 was distributed chaotically in matrix, which greatly improved the friction-reducing property of copper, while CNT with superior mechanical strength enhanced the wear resistance by increasing the load-carrying capacity. More importantly, copper layers coated on NbSe 2 and CNT favored the good interfacial combination between fillers and copper matrix showing beneficial effect for the stresses transferring from matrix to fillers

Electron concentration and phase stability in NbCr2-based Laves phase alloys

Energy Technology Data Exchange (ETDEWEB)

Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1997-05-12

Phase stability in NbCr{sub 2}-based transition-metal Laves phases was studied, based on the data reported for binary X-Cr, Nb-X, and ternary Nb-Cr-X phase diagrams. It was shown that when the atomic size ratios are kept identical, the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based transition-metal Laves phases. The e/a ratios for different Laves polytypes were determined as followed: with e/a < 5.76, the C15 structure is stabilized; at an e/a range of 5.88--7.53, the C14 structure is stabilized; with e/a > 7.65, the C15 structure is stabilized again. A further increase in the electron concentration factor (e/a > 8) leads to the disordering of the alloy. The electron concentration effect on the phase stability of Mg-based Laves phases and transition-metal A{sub 3}B intermetallic compounds is also reviewed and compared with the present observations in transition-metal Laves phases. In order to verify the e/a/phase stability relationship experimentally, additions of Cu (with e/a = 11) were selected to replace Cr in the NbCr{sub 2} Laves phase. Experimental results for the ternary Nb-Cr-Cu system are reported and discussed in terms of the correlation between the e/a ratio and phase stability in NbCr{sub 2}-based Laves phases. A new phase was found, which has an average composition of Nb-47Cr-3Cu. Within the solubility limit, the electron concentration and phase stability relationship is obeyed in the Nb-Cr-Cu system.

Delayed hydride cracking in Zr-2.5Nb pressure tubes

International Nuclear Information System (INIS)

Mieza, Juan I.; Domizzi, Gladys; Vigna, Gustavo L.

2007-01-01

Zr-2.5 Nb alloy from CANDU pressure tubes are prone to failure by hydrogen intake. One of the degradation mechanisms is delayed hydride cracking, which is characterized by the velocity of cracking. In this work, we study the effect of beta zirconium phase transformation over delayed hydride cracking velocity in Zr-2.5 Nb alloy from pressure tubes. Acoustic emission technique was used for cracking detection. (author) [es

Ultrasonic, photocatalytic and sonophotocatalytic degradation of Basic Red-2 by using Nb2O5 nano catalyst

Directory of Open Access Journals (Sweden)

Gunvant H. Sonawane

2016-09-01

Full Text Available The ultrasonic, photocatalytic and sonophotocatalytic degradation of Basic Red-2 accompanied by Nb2O5 nano catalysts were studied. The structure and morphology of synthesized Nb2O5 nano catalyst was investigated using scanning election microscopy (SEM, Electron dispersive X-ray spectroscopy (EDS and X-ray diffraction (XRD.The effects of various experimental parameters such as the Basic Red-2 concentration, catalyst dose, pH and addition of H2O2 on the ultrasonic, photocatalytic and sonophotocatalytic degradation were investigated. Photocatalytic and sonophotocatalytic degradation of Basic Red-2 was strongly affected by initial dye concentration, catalyst dose, H2O2 addition and pH. Basic pH (pH-10 was favored for the ultrasonic (US, photocatalytic (UV + Nb2O5 and sonophotocatalytic (US + UV + Nb2O5 degradation of Basic Red-2 by using Nb2O5 nano catalyst. The ultrasonic degradation of Basic Red-2 was enhanced by the addition of photocatalyst. Then, the effect of Nb2O5 dose on photocatalytic and sonophotocatalytic degradation were studied, and it was found that increase in catalyst dose increase in the percentage degradation of Basic Red-2. In addition, the effects of H2O2 on ultrasonic, photolytic, photocatalytic and sonophotocatalytic degradation was also investigated, and it was found that H2O2 enhances the % degradation of Basic Red-2. The possible mechanism of ultrasonic, photocatalytic and sonophotocatalytic degradation of Basic Red-2 reported by LC-MS shows generation of different degradation products

Atomic defects and doping of monolayer NbSe2

OpenAIRE

Nguyen, Lan; Komsa, Hannu-Pekka; Khestanova, Ekaterina; Kashtiban, Reza J; Peters, Jonathan J.P.; Lawlor, Sean; Sanchez, Ana M.; Sloan, Jeremy; Gorbachev, Roman; Grigorieva, Irina; Krasheninnikov, Arkady V.; Haigh, Sarah

2017-01-01

We have investigated the structure of atomic defects within monolayer NbSe2 encapsulated in graphene by combining atomic resolution transmission electron microscope imaging, density functional theory (DFT) calculations, and strain mapping using geometric phase analysis. We demonstrate the presence of stable Nb and Se monovacancies in monolayer material and reveal that Se monovacancies are the most frequently observed defects, consistent with DFT calculations of their formation energy. We reve...

Study of fatigue and fracture behavior of NbCr{sub 2}-based alloys: Phase stability in Nb-Cr-Ni ternary system

Energy Technology Data Exchange (ETDEWEB)

Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1997-12-01

Phase stability in a ternary Nb-Cr-Ni Laves phase system was studied in this paper. Their previous study in NbCr{sub 2}-based transition-metal Laves phases has shown that the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based Laves phases when the atomic size ratios are kept identical. Since Ni has ten out-shell electrons, the substitution of Ni for Cr in NbCr{sub 2} will increase the average electron concentration of the alloy, thus leading to the change of the crystal structures from C15 to C14. In this paper, a number of pseudo-binary Nb(Cr,Ni){sub 2} alloys were prepared, and the crystal structures of the alloys after a long heat-treatment at 1000 C as a function of the Ni content were determined by the X-ray diffraction technique. The boundaries of the C15/C14 transition were determined and compared to their previous predictions. It was found that the electron concentration and phase stability correlation is obeyed in the Nb-Cr-Ni system. However, the e/a ratio corresponding to the C15/C14 phase transition was found to move to a higher value than the predicted one. The changes in the lattice constant, Vickers hardness and fracture toughness were also determined as a function of the Ni content, which were discussed in light of the phase stability difference of the alloys.

Phase Evolution in and Creep Properties of Nb-Rich Nb-Si-Cr Eutectics

Science.gov (United States)

Gang, Florian; Kauffmann, Alexander; Heilmaier, Martin

2018-03-01

In this work, the Nb-rich ternary eutectic in the Nb-Si-Cr system has been experimentally determined to be Nb-10.9Si-28.4Cr (in at. pct). The eutectic is composed of three main phases: Nb solid solution (Nbss), β-Cr2Nb, and Nb9(Si,Cr)5. The ternary eutectic microstructure remains stable for several hundred hours at a temperature up to 1473 K (1200 °C). At 1573 K (1300 °C) and above, the silicide phase Nb9(Si,Cr)5 decomposes into α-Nb5Si3, Nbss, and β-Cr2Nb. Under creep conditions at 1473 K (1200 °C), the alloy deforms by dislocation creep while the major creep resistance is provided by the silicide matrix. If the silicide phase is fragmented and, thus, its matrix character is destroyed by prior heat treatment [ e.g., at 1773 K (1500 °C) for 100 hours], creep is mainly controlled by the Laves phase β-Cr2Nb, resulting in increased minimum strain rates. Compared to state of the art Ni-based superalloys, the creep resistance of this three-phase eutectic alloy is significantly higher.

Effect of Nb element content in U-Zr-Nb alloy on hardness, microstructure and phase formation

International Nuclear Information System (INIS)

Masrukan; M Husna Al Hasa; Jan Setiawan; Slamet Pribadi

2015-01-01

Experiments to determine the effect of Nb element in the U-Zr alloys on hardness, microstructure and phase formation has been done. The addition of Nb element would effect the hardness, microstructure and phase which formed. The U-Zr-Nb alloy was made with the variation of Nb 2%, 5% and 8% by melting in an electric arc melting furnace that equipped with water cooling and the argon atmosphere. The U-Zr-Nb alloy to be cut divided to some testing, such as hardness test, microstructure, and phase analysis. Hardness testing was done by Vickers hardness testing equipment, microstructure by an optical microscope, and diffraction pattern by XRD and phase analysis was done by GSAS. Hardness testing results showed that the addition of 2% to 5% Nb element in U-Zr alloys will increased in hardness, but the addition of Nb element over 5% the hardness was decreased. Observations the microstructure showed that the addition of 2% to 5% Nb element, grains were formed from fine into coarse. Phase analysis for diffraction pattern showed that the phase changed from αU and γU (Zr,Nb)at 2% Nb to be αU, γU (Zr,Nb) and δ1 (UZr_2) phase at 5% and 8% Nb. Phase changes was followed by changes in its compositions. The composition of αU at 2% Nb was 40% increased to 81% at 5% Nb and decreased to 3.9% at 8% Nb. The composition of γU decreased from 59,86% to 14,91% with increased Nb from 2% to 5% and further increased to 52,74% at 8% Nb. (author)

Perturbed angular correlation study of α - Nb2O5

International Nuclear Information System (INIS)

Shitu, Jorge; Massolo, C.P.; Bibiloni, A.G.; Renteria, Mario; Desimoni, Judith

1989-01-01

The TANDAR accelerator of the National Atomic Energy Commission has been used to obtain the non-conventional radioactive probe 100 Rh embedded in α - Nb 2 O 5 allowing the PAC study of the range of high electric field gradients in this semiconductor. A sintered oxide tablet, obtained from metallic Nb powder calcination in air at 1050deg C, was irradiated with a 100 MeV 12 C6+ beam for 15 hours to produce the 100 Rh probe through the reaction 93 Nb ( 12 C,5n) 100 Ag → 100 Pd → 100 Rh. The PAC measurements show a non-homogenous distribution of the probes substituting the Nb in lattice sites of high electric field gradient. The range of low electric field gradients was studied using the probe 111 In incorporated to the samples by diffusion. (Author) [es

Micro-nanocomposites Al2O3/ NbC/ WC and Al2O3/ NbC/ TaC

International Nuclear Information System (INIS)

Santos, Thais da Silva

2014-01-01

Alumina based ceramics belong to a class of materials designated as structural, which are widely used in cutting tools. Although alumina has good properties for application as a structural ceramics, composites with different additives have been produced with the aim of improving its fracture toughness and mechanical strength. New studies point out micro-nanocomposites, wherein the addition of micrometric particles should enhance mechanical strength, and nano-sized particles enhance fracture toughness. In this work, alumina based micro nanocomposites were obtained by including nano-sized NbC and micrometer WC particles at 2:1, 6:4, 10:5 and 15:10 vol% proportions, and also with the inclusion of nano-sized NbC and micrometer TaC particles at 2:1 vol% proportion. For the study of densification, micro-nanocomposites were sintered in a dilatometer with a heating rate of 20°C/min until a temperature of 1800°C in argon atmosphere. Based on the dilatometry results, specimens were sintered in a resistive graphite furnace under argon atmosphere between 1500°C and 1700°C by holding the sintering temperature for 30 minutes. Densities, crystalline phases, hardness and tenacity were determined, and micro-nanocomposites microstructures were analyzed. The samples Al 2 O 3 : NbC: TaC sintered at 1700 ° C achieved the greater apparent density (~ 95% TD) and the sample sintered at 1600 ° C showed homogeneous microstructure and increased hardness value (15.8 GPa) compared to the pure alumina . The compositions with 3% inclusions are the most promising for future applications. (author)

Expression of the Eukaryotic Translation Initiation Factors 4E and 2α in Non-Hodgkin’s Lymphomas

Science.gov (United States)

Wang, Songtao; Rosenwald, Igor B.; Hutzler, Michael J.; Pihan, German A.; Savas, Lou; Chen, Jane-Jane; Woda, Bruce A.

1999-01-01

Transition of cells from quiescence to proliferation requires an increase in the rate of protein synthesis, which is regulated in part by two key translation initiation factors, 4E and 2α. The expression and activity of both factors are increased transiently when normal resting cells are stimulated to proliferate. They are constitutively elevated in oncogene transformed cultured cells, and overexpression of either initiation factor in rodent cells makes them tumorigenic. In this study we investigate an association between the expression of translation initiation factors and lymphomagenesis. We have analyzed the expression of the protein synthesis initiation factors 4E and 2α by immunohistochemistry in reactive lymph nodes and several types of non-Hodgkin’s lymphoma representing a wide range of clinical behaviors based on the Revised European-American Lymphoma behavioral classification. The study included 7 benign lymph nodes with follicular hyperplasia, 26 indolent lymphomas (6 marginal zone lymphomas, 7 small lymphocytic lymphomas, and 13 follicular lymphomas, grades 1 and 2), 16 moderately aggressive lymphomas (8 mantle cell lymphomas and 8 follicular lymphomas, grade 3), 24 aggressive lymphomas (14 large-B-cell lymphomas and 10 anaplastic large-cell lymphomas), and 15 highly aggressive lymphomas (7 lymphoblastic lymphomas and 8 Burkitt’s lymphomas). Strong expression of initiation factors 4E and 2α was demonstrated in the germinal centers of reactive follicles. Minimal or no expression was seen in the mantle zones and surrounding paracortices, indicating that high expression of initiation factors 4E and 2α is associated with the active proliferation of lymphocytes. Most cases of aggressive and highly aggressive lymphomas showed strong expression of initiation factors 4E and 2α, in contrast to the cases of indolent and moderately aggressive lymphoma, in which their expression was intermediate between the germinal centers and the mantles of reactive

Alisertib in Combination With Vorinostat in Treating Patients With Relapsed or Recurrent Hodgkin Lymphoma, B-Cell Non-Hodgkin Lymphoma, or Peripheral T-Cell Lymphoma

Science.gov (United States)

2018-04-10

Adult B Acute Lymphoblastic Leukemia; Adult T Acute Lymphoblastic Leukemia; Anaplastic Large Cell Lymphoma; Angioimmunoblastic T-Cell Lymphoma; Chronic Lymphocytic Leukemia; Extranodal Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue; Hepatosplenic T-Cell Lymphoma; Intraocular Lymphoma; Lymphomatous Involvement of Non-Cutaneous Extranodal Site; Mature T-Cell and NK-Cell Non-Hodgkin Lymphoma; Nodal Marginal Zone Lymphoma; Primary Cutaneous B-Cell Non-Hodgkin Lymphoma; Recurrent Adult Acute Lymphoblastic Leukemia; Recurrent Adult Burkitt Lymphoma; Recurrent Adult Grade III Lymphomatoid Granulomatosis; Recurrent Adult Hodgkin Lymphoma; Recurrent Adult Immunoblastic Lymphoma; Recurrent Adult Lymphoblastic Lymphoma; Recurrent Adult T-Cell Leukemia/Lymphoma; Recurrent Grade 1 Follicular Lymphoma; Recurrent Grade 2 Follicular Lymphoma; Recurrent Grade 3 Follicular Lymphoma; Recurrent Mantle Cell Lymphoma; Recurrent Marginal Zone Lymphoma; Recurrent Mycosis Fungoides and Sezary Syndrome; Recurrent Non-Hodgkin Lymphoma; Recurrent Primary Cutaneous T-Cell Non-Hodgkin Lymphoma; Recurrent Small Lymphocytic Lymphoma; Refractory Chronic Lymphocytic Leukemia; Refractory Hairy Cell Leukemia; Small Intestinal Lymphoma; Splenic Marginal Zone Lymphoma; T-Cell Large Granular Lymphocyte Leukemia; Testicular Lymphoma; Waldenstrom Macroglobulinemia

Frequent alteration of MDM2 and p53 in the molecular progression of recurring non-Hodgkin's lymphoma

DEFF Research Database (Denmark)

Møller, Michael Boe; Nielsen, O; Pedersen, Niels Tinggaard

2002-01-01

-Hodgkin's lymphoma. METHODS AND RESULTS: We have analysed sequential biopsies from 42 non-Hodgkin's lymphoma patients immunohistochemically for p53 alterations (based on p53 and p21Waf1 expression), as well as for expression of MDM2, p27Kip1 and cyclin D3. Relapse of follicle centre lymphoma was associated with p53...... alterations as 5/6 (83%) follicle centre lymphomas with normal p53 at diagnosis showed p53 alterations at relapse. Of these cases, three showed transformation to diffuse large B-cell lymphoma. p53 alteration was also associated with relapse of de novo diffuse large B-cell lymphoma and T-cell non......-Hodgkin's lymphoma, as 2/5 (40%) diffuse large B-cell lymphomas and 3/9 (33%) T-cell non-Hodgkin's lymphomas with normal p53 at diagnosis showed p53 alterations at relapse. No indolent non-Hodgkin's lymphoma case showed MDM2 over-expression at diagnosis, whereas 4/5 (80%) transformed diffuse large B-cell lymphomas...

Free-anchored Nb2O5@graphene networks for ultrafast-stable lithium storage

Science.gov (United States)

Deng, Qinglin; Li, Mengjiao; Wang, Junyong; Jiang, Kai; Hu, Zhigao; Chu, Junhao

2018-05-01

Orthorhombic Nb2O5 (T-Nb2O5) has structural merit but poor electrical conductivity, limiting their applications in energy storage. Although graphene is frequently adopted to effectively improve its electrochemical properties, the ordinary modified methods cannot meet the growing demands for high-performance. Here, we demonstrate that different graphene modified routes play a vital role in affecting the electrochemical performances of T-Nb2O5. By only manual shaking within one minute, Nb2O5 nano-particles can be rapidly adsorbed onto graphene, then the free-anchored T-Nb2O5@graphene three-dimensional networks can be successfully prepared based on hydrogel method. As for the application in lithium-ion batteries, it performs outstanding rate character (129 mA h g-1 (25C rate), 110 mA h g-1 (50C rate) and 90 mA h g-1 (100C rate), correspond to 79%, 67% and 55% capacity of 0.5C rate, respectively) and excellent long-term cycling feature (˜70% capacity retention after 20000 cycles). Moreover, it still maintains similar ultrafast-stable lithium storage performances when Cu foil is substituted by Al foil as current collector. In addition, relevant kinetics mechanisms are also expounded. This work provides a versatile strategy for the preparation of graphene modified Nb2O5 or other types of nanoparticles.

Regulation of Id2 expression in EL4 T lymphoma cells overexpressing growth hormone.

Science.gov (United States)

Weigent, Douglas A

2009-01-01

In previous studies, we have shown that overexpression of growth hormone (GH) in cells of the immune system upregulates proteins involved in cell growth and protects from apoptosis. Here, we report that overexpression of GH in EL4 T lymphoma cells (GHo) also significantly increased levels of the inhibitor of differentiation-2 (Id2). The increase in Id2 was suggested in both Id2 promoter luciferase assays and by Western analysis for Id2 protein. To identify the regulatory elements that mediate transcriptional activation by GH in the Id2 promoter, promoter deletion analysis was performed. Deletion analysis revealed that transactivation involved a 301-132bp region upstream to the Id2 transcriptional start site. The pattern in the human GHo Jurkat T lymphoma cell line paralleled that found in the mouse GHo EL4 T lymphoma cell line. Significantly less Id2 was detected in the nucleus of GHo EL4 T lymphoma cells compared to vector alone controls. Although serum increased the levels of Id2 in control vector alone cells, no difference was found in the total levels of Id2 in GHo EL4 T lymphoma cells treated with or without serum. The increase in Id2 expression in GHo EL4 T lymphoma cells measured by Id2 promoter luciferase expression and Western blot analysis was blocked by the overexpression of a dominant-negative mutant of STAT5. The results suggest that in EL4 T lymphoma cells overexpressing GH, there is an upregulation of Id2 protein that appears to involve STAT protein activity.

Diatomic substitutionals in superconducting Nb(1-x)B2

International Nuclear Information System (INIS)

Farrell, H.H.; LaViolette, Randall A.; Lillo, T.M.

2006-01-01

Using first-principles, density functional theory calculations, we have shown that the increase in superconducting critical temperature to above 9 K experimentally observed for B-rich, off-stoichiometry NbB 2 material is associated with the formation of B-dimers on Nb sites rather than with the formation of Nb vacancies, as previously proposed. Our calculations show that certain of these B-dimer configurations have lower binding energies than do the vacancy structures. This result is pressure independent in the range between 0 and 10 GPa, and above. Further, the dimer-containing materials have a higher electronic density of states at the Fermi level than do the vacancy structures. Finally, the presence of B-dimers results in the splitting off of phonon normal modes. These last two factors are relevant to the improved superconducting properties

Nanocomposite dielectrics in PbO-BaO-Na2O-Nb2O5-SiO2 system with high breakdown strength for high voltage capacitor applications.

Science.gov (United States)

Zhang, Qingmeng; Luo, Jun; Tang, Qun; Han, Dongfang; Zhou, Yi; Du, Jun

2012-11-01

Nanocomposite dielectrics in 6PbO-4BaO-20Na2O-40Nb2O5-30SiO2 system were prepared via melt-quenching followed by controlled crystallization. X-ray diffraction studies reveal that Pb2Nb2O7, Ba,NaNb5O15, NaNbO3 and PbNb2O6 phases are formed from the as-quenched glass annealed in temperature range from 700 degrees C to 850 degrees C. Ba2NaNb5O15, Pb2Nb2O7 crystallizes at 700 degrees C and then Pb2Nb2O7 disappears at 850 degrees C, while PbNb2O6 and NaNbO3 are formed at 850 degrees C. Microstructural observation shows that the crystallized particles are nanometer-sized and randomly distributed with glass matrix being often found at grain boundaries. The dielectric constant of the nanocomposites formed at different crystallization temperatures shows good frequency and electric field stability. The breakdown strength is slightly decreased when the glass-ceramics thickness is varied from 1 mm to 4 mm. The corresponding energy density could reach 2.96 J/cm3 with a breakdown strength of 58 kV/mm for thickness of 1 mm.

The quinternary thiophosphate Cs0.5Ag0.5Nb2PS10

Directory of Open Access Journals (Sweden)

Sojeong Park

2010-07-01

Full Text Available The quinternary thiophosphate Cs0.5Ag0.5Nb2PS10, cesium silver tris(disulfido[tetrathiophosphato(V]diniobate(IV, has been prepared from the elements using a CsCl flux. The crystal structure is made up of ∞1[Nb2PS10] chains expanding along [010]. These chains are built up from bicapped trigonal-prismatic [Nb2S12] units and tetrahedral [PS4] groups and are linked through a linear S—Ag—S bridge, forming a two-dimensional layer. These layers then stack on top of each other, completing the three-dimensional structure with an undulating van der Waals gap. The disordered Cs+ ions reside on sites with half-occupation in the voids of this arrangement. Short [2.8843 (5 Å] and long [3.7316 (4 Å] Nb—Nb distances alternate along the chains, and anionic S22− and S2− species are observed. The charge balance of the compound can be represented by the formula [Cs+]0.5[Ag+]0.5[Nb4+]2[PS43−][S22−]3.

Oncoprotein MDM2 Overexpression is Associated with Poor Prognosis in Distinct Non-Hodgkin's Lymphoma Entities

DEFF Research Database (Denmark)

Møller, Michael Boe; Nielsen, O; Pedersen, Niels Tinggaard

1999-01-01

MDM2 is an oncoprotein involved in the regulation of p53. MDM2 exerts its tumorigenic potential through p53-dependent and -independent mechanisms. It is frequently overexpressed in various malignancies. Little is known about the prognostic value of MDM2 expression in non-Hodgkin's lymphomas (NHL...... overexpression was present in 42 (22%) of 188 cases. The frequency was highest in aggressive/very aggressive NHL (P lymphomas, MDM2 overexpression was associated with higher-grade disease (P = .008). MDM2 overexpression was not related to a phenotype indicating...... altered p53. In univariate analysis MDM2 overexpression associated with short survival in follicle center lymphomas (P = .0256), extranodal marginal zone lymphomas (P lymphomas (P = .0047). The relation to poor prognosis was maintained in a Cox regression analysis including known...

Nonequilibrium synthesis of NbAl3 and Nb-Al-V alloys by laser cladding. II - Oxidation behavior

Science.gov (United States)

Haasch, R. T.; Tewari, S. K.; Sircar, S.; Loxton, C. M.; Mazumder, J.

1992-01-01

Isothermal oxidation behaviors of NbAl3 alloy synthesized by laser cladding were investigated at temperatures between 800 and 1400 C, and the effect of vanadium microalloying on the oxidation of the laser-clad alloy was examined. The oxidation kinetics of the two alloys were monitored using thermal gravimetric weight gain data, and the bulk and surface chemistries were analyzed using XRD and XPS, respectively. It was found that NbAl3 did not form an exclusive layer of protective Al2O3. The oxidation products at 800 C were found to be a mixture of Nb2O5 and Al2O3. At 1200 C, a mixture of NbAlO4, Nb2O5, and Al2O3 formed; and at 1400 C, a mixture of NbAlO4, Al2O3, NbO2, NbO(2.432), and Nb2O5 formed. The addition of V led to a dramatic increase of the oxidation rate, which may be related to the formation of (Nb, V)2O5 and VO2, which grows in preference to protective Al2O3.

Single-Crystal X-Ray Diffraction Studies of Homologues in the Series nBa(Nb,Zr)O 3+3 mNbO with n=2, 3, 4, 5 and m=1

Science.gov (United States)

Nilsson, G.; Svensson, G.

2001-01-01

Single crystals of four homologues in the series nBa(Nb,Zr)O3+3mNbO, with n:m=2:1, 3:1, 4:1, and 5:1, were found in the reduced Ba-Nb-Zr-O system. Single-crystal X-ray diffraction data were collected for all the crystals. For all homologues the space group was found to be P4/mmm. The structures can be described as intergrowths of Ba(Nb,Zr)O3 perovskite and NbO slabs. The refined cell parameters and compositions of the 2:1, 3:1, and 4:1 homologues are a=4.1768(5) Å and c=12.269(2) Å for Ba2Nb4.5(1)Zr0.5(1)O9, a=4.1769(5) Å and c=16.493(3) Å for Ba3+δNb4.8(2)-δ Zr1.2(2)O12-δ (δ=0.098(4)), and a=4.1747(6) Å and c= 20.619(4) Å for Ba4+δNb5.1(4)-δZr1.9(4)O15-δ (δ=0.270(9)). The refined cell parameters of the 5:1 homologue are a=4.1727(3) Å and c=24.804(3) Å. Zr replaces Nb only in the NbO6 octahedra found in the perovskite slabs.

Nanoporous niobium nitride (Nb2N) with enhanced electrocatalytic performance for hydrogen evolution

Science.gov (United States)

Li, Yan; Zhang, Jianli; Qian, Xingyue; Zhang, Yue; Wang, Yining; Hu, Rudan; Yao, Chao; Zhu, Junwu

2018-01-01

The transition metal nitrides (TMNs) with nanoporous structure have shown great promise as potential electrocatalysts for the hydrogen evolution reaction (HER). Herein, self-organized nanoporous Nb2N was first successfully synthesized through the anodization of niobium in mixed oxalic acid/HF electrolyte, followed by a simple annealing treatment in the ammonia atmosphere. Due to the highly ordered nanoporous structure with abundant active sites and the enhanced electrical conductivity, the Nb2N exhibits a high catalytic current (326.3 mA cm-2) and low onset potential (96.3 mV), which is almost 3.9 times and 4.2 times better than that of Nb2O5, respectively. Meanwhile, the Nb2N also presents low Tafel slope (92 mV dec-1), and excellent cycling durability. More importantly, this study will provide more opportunities for designing and fabricating niobium compounds as an innovative HER catalysts.

Preparation, composition, and solid state investigations of TiN, ZrN, NbN, and compounds from the pseudobinary systems NbN-NbC, NbN-TiC, and NbN-TiN

International Nuclear Information System (INIS)

Christensen, A.N.; Fregerslev, S.

1977-01-01

Single crystals of the cubic phases TiN, ZrN, delta-NbN and of compounds from the pseudobinary systems NbN-NbC, NbN-TiC, and NbN-TiN were obtained by zone melting, zone annealing and annealing of the metal carbides in nitrogen gas of 2 MPa. Single crystals of the tetragonal phase gamma-NbN were obtained in a similar way by annealing of niobium. The nitrides are non-stochiometric. TiN was obtained in the composition range TiNsub(0.99) to TiNsub(0.50), ZrN in the range ZrNsub(1.00) to ZrNsub(0.63), and in niobium nitrides were obtained in the composition range NbNsub(0.90) to NbNsub(0.69). The compounds from the pseudobinary systems have up to 35% vacant sites in the nitrogen-carbon sublattice. TiN and ZrN have only vacant sites in the nitrogen sublattice. A correlation is found between the unit cell parameters for titanium nitride and zirconium nitride and the nitrogen-metal ratios. (orig.) [de

Hexagonal-like Nb2O5 Nanoplates-Based Photodetectors and Photocatalyst with High Performances

Science.gov (United States)

Liu, Hui; Gao, Nan; Liao, Meiyong; Fang, Xiaosheng

2015-01-01

Ultraviolet (UV) photodetectors are important tools in the fields of optical imaging, environmental monitoring, and air and water sterilization, as well as flame sensing and early rocket plume detection. Herein, hexagonal-like Nb2O5 nanoplates are synthesized using a facile solvothermal method. UV photodetectors based on single Nb2O5 nanoplates are constructed and the optoelectronic properties have been probed. The photodetectors show remarkable sensitivity with a high external quantum efficiency (EQE) of 9617%, and adequate wavelength selectivity with respect to UV-A light. In addition, the photodetectors exhibit robust stability and strong dependence of photocurrent on light intensity. Also, a low-cost drop-casting method is used to fabricate photodetectors based on Nb2O5 nanoplate film, which exhibit singular thermal stability. Moreover, the hexagonal-like Nb2O5 nanoplates show significantly better photocatalytic performances in decomposing Methylene-blue and Rhdamine B dyes than commercial Nb2O5.

X-ray and neutron diffraction studies of the formation and structure of hydrogen intercalated 2H-NbSe2 phases

International Nuclear Information System (INIS)

Kulikov, L.M.; Skolozdra, R.V.; Fruchart, D.; Soubeyroux, J.L.

1996-01-01

Intercalated compounds of H 0.07 NbSe 2 and D x NbSe 2 (x = 0.41; 0.49) composition have been prepared and investigated by powder X-ray and neutron diffraction. Rietveld analysis of the data showed that hydrogen (deuterium) atoms occupy the 2(c) site with coordinates (1/3 2/3 1/4) (structure type 2H-TaS 2 for H 0.07 NbSe 2 ) and the 2(b) site with coordinates (0 0 1/3) (structure type 2H-MoS 2 for D 0.41 NbSe 2 and D 0.49 NbSe 2 ). According to crystallographic results it is suggested that the nature of the quasi-two-dimensional layer plays a key role in the unusual location of the hydrogen atoms, the intercalation processes and the maximum uptake of hydrogen. The results are compared with the available literature data. (orig.)

Heat capacity measurement of Ba3SrNb2O9

International Nuclear Information System (INIS)

Singh, B.M.; Samui, Pradeep; Agarwal, Renu; Mukerjee, S.K.

2016-01-01

Barium, Strontium and Niobium are important fission products in nuclear reactor with reasonable fission yields. During irradiation of oxide fuels, they can combine to form compounds of Ba-Sr-Nb-O system. Therefore, thermodynamic properties of Ba 3 SrNb 2 O 9 are required for modelling fuel behaviour however thermodynamic data of this compound is not available in literature. Ba 3 SrNb 2 O 9 was prepared by solid state route, by mixing stoichiometric amounts of finely grounded SrCO 3 , BaCO 3 and Nb 2 O 5 . Finally mixed powder was pressed into a pellet at 5 ton pressure for 2 minutes in a hydraulic press and the pellet was heated at 1123 K for 60 h in air. The pellet was cooled, finely grounded, re-pelletised and heated at 1473 K for 120 h. The formation of compound was confirmed by X-ray diffraction pattern, collected at room temperature using Cu-K α radiation (λ = 1.54 nm), scanned over the angular range 20-80° (2θ) with steps of 0.02°. Heat capacity of the compound was measured by the classical three-step method, in continuous mode, using LABSYS EVO, in temperature range of 370 and 950 K. No transition was observed in the investigated temperature range

Malignant lymphoma of the conjunctiva

DEFF Research Database (Denmark)

Kirkegaard, Marina M.; Coupland, Sarah E.; Prause, Jan U.

2015-01-01

Conjunctival lymphomas constitute 25% of all ocular adnexal lymphomas. The majority are B-cell non-Hodgkin lymphomas (NHLs) (98%), whereas conjunctival T-cell NHLs are rare (2%). The most frequent subtype of conjunctival B-cell lymphoma is extranodal marginal zone lymphoma (EMZL; 81%), followed...... by follicular lymphoma (8%), diffuse large B-cell lymphoma (3%), and mantle cell lymphoma (3%). Extranodal marginal zone lymphoma occurs slightly more often in women and, along with follicular lymphoma, presents late in the seventh decade of life, whereas diffuse large B-cell lymphoma and especially mantle cell...... lymphoma have a predilection for the male gender and typically present in the eighth decade. Extranodal marginal zone lymphoma and follicular lymphoma present most frequently in the forniceal and bulbar conjunctiva. Conjunctival diffuse large B-cell lymphoma, mantle cell lymphoma and T-cell NHLs...

Large-scale synthesis of NbS2 nanosheets with controlled orientation on graphene by ambient pressure CVD.

Science.gov (United States)

Ge, Wanyin; Kawahara, Kenji; Tsuji, Masaharu; Ago, Hiroki

2013-07-07

We report ambient pressure chemical vapor deposition (CVD) growth of single-crystalline NbS2 nanosheets with controlled orientation. On Si and SiO2 substrates, NbS2 nanosheets grow almost perpendicular to the substrate surface. However, when we apply transferred CVD graphene on SiO2 as a substrate, NbS2 sheets grow laterally lying on the graphene. The NbS2 sheets show the triangular and hexagonal shapes with a thickness of about 20-200 nm and several micrometres in the lateral dimension. Analyses based on X-ray diffraction and Raman spectroscopy indicate that the NbS2 nanosheets are single crystalline 3R-type with a rhombohedral structure of R3m space group. Our findings on the formation of highly aligned NbS2 nanosheets on graphene give new insight into the formation mechanism of NbS2 and would contribute to the templated growth of various layered materials.

Impact of Nb vacancies and p-type doping of the NbCoSn-NbCoSb half-Heusler thermoelectrics.

Science.gov (United States)

Ferluccio, Daniella A; Smith, Ronald I; Buckman, Jim; Bos, Jan-Willem G

2018-02-07

The half-Heuslers NbCoSn and NbCoSb have promising thermoelectric properties. Here, an investigation of the NbCo 1+y Sn 1-z Sb z (y = 0, 0.05; 0 ≤ z ≤ 1) solid-solution is presented. In addition, the p-type doping of NbCoSn using Ti and Zr substitution is investigated. Rietveld analysis reveals the gradual creation of Nb vacancies to compensate for the n-type doping caused by the substitution of Sb in NbCoSn. This leads to a similar valence electron count (∼18.25) for the NbCo 1+y Sn 1-z Sb z samples (z > 0). Mass fluctuation disorder due to the Nb vacancies strongly decreases the lattice thermal conductivity from 10 W m -1 K -1 (z = 0) to 4.5 W m -1 K -1 (z = 0.5, 1). This is accompanied by a transition to degenerate semiconducting behaviour leading to large power factors, S 2 /ρ = 2.5-3 mW m -1 K -2 and figures of merit, ZT = 0.25-0.33 at 773 K. Ti and Zr can be used to achieve positive Seebeck values, e.g. S = +150 μV K -1 for 20% Zr at 773 K. However, the electrical resistivity, ρ 323K = 27-35 mΩ cm, remains too large for these materials to be considered useful p-type materials.

Non-stoichiometric disorder in α-Nb2O5 at elevated temperatures

International Nuclear Information System (INIS)

Balachandran, U.; Eror, N.G.

1982-01-01

The electrical conductivity of polycrystalline α-Nb 2 O 5 was determined for the oxygen partial pressure range of 10 0 to 10 -20 atm and temperature range 700 to 1150 0 C. The data were found to be proportional to the -1/6th power of the oxygen partial pressure for the oxygen pressure range 10 -20 to 10 -9 atm, and proportional to Psub(O 2 )sup(-1/4) for oxygen pressures greater than 10 -9 atm. The region of linearity where electrical conductivity varies as the -1/4th power of Psub(O 2 ) increased as the temperature was decreased. Thermogravimetric measurements were carried out in the temperature range 950 to 1250 0 C. The deviation from stoichiometry in α-Nb 2 O 5 (x in Nb 2 Osub(5-x)) as a function of partial pressure of oxygen showed two distinct regions, namely a region with an approximately -1/6th dependence on Psub(O 2 ) and a region where the deviation was nearly independent of oxygen partial pressure. The electrical conductivity and thermogravimetric data are consistent with the presence of small amounts of acceptor impurities in α-Nb 2 O 5 . (author)

Creep and stress rupture behaviour of zircaloy-2 and Zr-2.5% Nb alloy tubes at 573 K

International Nuclear Information System (INIS)

Laha, K.; Bhanu Sankara Rao, K.; Chandravathi, K.S.; Mannan, S.L.

1992-01-01

Zirconium alloys are extensively used for coolant tubes of pressurised heavy water reactors. The choice of these materials is based on their good corrosion resistance in water, low capture cross section for thermal neutrons and good mechanical properties. In this paper the results of an investigation performed on the creep and rupture behaviour of indigenously produced zircaloy-2 and Zr-2.5% Nb alloy are presented. Samples for creep testing were cut longitudinally from finished pressure tubes. Creep rupture tests were carried out in air under constant load conditions at 300 C employing five stress levels in the range 300-360 MPa. Zr-2.5% Nb alloy displayed higher rupture lives at all stress levels compared to zircaloy-2. Steady state creep rate of Zr-2.5%Nb was lower than that zircaloy-2 at identical stress levels. In the stress range of the experiments, the dependence of the steady state creep rate (ε s ) on applied stress (σ) for both the alloys could be represented by a power law, ε s =A σ n The stress sensitivity (n) for Zr-2.5% Nb was lower than that of zircaloy-2. For both the alloys the time to creep rupture t r was found related to the steady state creep rate through the modified Monkman-Grant relation (ε s ) α . t r = constant. Similar value of α was obtained for both the materials. Zr-2.5%Nb exhibited higher ductility (% elongation to rupture) compared to zircaloy-2 at stress levels ≥ 320 MPa. At lower stresses significant difference in ductility was not noticed. Percentage reduction in area was lower in Zr-2.5%Nb at all stress levels indicating better resistance for necking. The time for onset of tertiary was longer for Zr-2.5% Nb alloy. The proportion of life spent by Zr-2.5% Nb in steady state creep regime was higher compared to that of zircaloy-2. Metallographic investigations on longitudinal sections in both the alloys showed large number of intragranular pores close to the fracture surface. A few number of cracks which are characteristic of

Tensile and fracture toughness characteristics of Zr-2.5Nb pressure tube

International Nuclear Information System (INIS)

Jung, H. C.; Kim, Y. S.; Ahn, S. B.; Kim, S. S.; Im, K. S.

2004-01-01

The object of this study is to evaluate the characteristics of tensile and fracture toughness of Zr-2.5Nb pressure tube. The transverse tensile tests were performed at various temperatures and the fracture toughness tests were carried out at room temperature using the CCT (curved compact tension) specimen. These specimens were directly machined from the pressure tube retaining original curvatures. Also, the fracture toughness of two sets of Zr-2.5Nb manufactured at different time was compared. The chemical analysis and the Vicker's hardness tests were performed at two sets of Zr-2.5Nb pressure tube. The Vicker's hardness value of SET-2 containing more oxygen and carbon relatively was higher about 11 than that of SET-1

Transformation of follicular lymphoma to plasmablastic lymphoma with c-myc gene rearrangement.

Science.gov (United States)

Ouansafi, Ihsane; He, Bing; Fraser, Cory; Nie, Kui; Mathew, Susan; Bhanji, Rumina; Hoda, Rana; Arabadjief, Melissa; Knowles, Daniel; Cerutti, Andrea; Orazi, Attilio; Tam, Wayne

2010-12-01

Follicular lymphoma (FL) is an indolent lymphoma that transforms to high-grade lymphoma, mostly diffuse large B-cell lymphoma, in about a third of patients. We present the first report of a case of FL that transformed to plasmablastic lymphoma (PBL). Clonal transformation of the FL to PBL was evidenced by identical IGH/BCL2 gene rearrangements and VDJ gene usage in rearranged IGH genes. IGH/ BCL2 translocation was retained in the PBL, which also acquired c-myc gene rearrangement. Genealogic analysis based on somatic hypermutation of the rearranged IGH genes of both FL and PBL suggests that transformation of the FL to PBL occurred most likely by divergent evolution from a common progenitor cell rather than direct evolution from the FL clone. Our study of this unusual case expands the histologic spectrum of FL transformation and increases our understanding of the pathogenetic mechanisms of transformation of indolent lymphomas to aggressive lymphomas.

Superconductivity in the ferecrystals (PbSe){sub 1.14}(NbSe{sub 2}){sub n}

Energy Technology Data Exchange (ETDEWEB)

Grosse, Corinna; Chiatti, Olivio; Fischer, Saskia F. [Novel Materials Group, Humboldt-Universitaet Berlin (Germany); Alemayehu, Matti B.; Falmbigl, Matthias; Johnson, David C. [Department of Chemistry, University of Oregon, Eugene, OR (United States)

2016-07-01

The ferecrystals (PbSe){sub 1.14}(NbSe{sub 2}){sub n} are artificially layered materials consisting of n NbSe{sub 2} single-layers stacked alternately with atomic double layers of PbSe. NbSe{sub 2} is a transition metal dichalcogenide with interesting electrical properties such as superconductivity and charge density waves. The influence of turbostratic disorder, a random rotation between the NbSe{sub 2} and PbSe layers, on the superconducting transition temperature has been unknown so far. We investigate the structural and temperature-dependent electrical properties of the ferecrystals (PbSe){sub 1.14}(NbSe{sub 2}){sub n} by means of scanning transmission electron microscopy, X-ray diffraction, in-plane resistivity and Hall measurements and compare them to those of analogous non-disordered misfit layer compound (MLC) polymorphs. We observe a superconducting transition in the resistivity of the ferecrystals. The transition temperatures are reduced by up to 55 % with respect to the analogous MLC polymorphs. This indicates that turbostratic disorder substantially weakens the electron-phonon coupling in (PbSe){sub 1.14}(NbSe{sub 2}){sub n}. We discuss the results of the structural and electrical properties of the ferecrystals with respect to their MLC analogues and also with respect to ultra-thin NbSe{sub 2} layers.

Reduction of hydrogen desorption temperature of ball-milled MgH2 by NbF5 addition

International Nuclear Information System (INIS)

Recham, N.; Bhat, V.V.; Kandavel, M.; Aymard, L.; Tarascon, J.-M.; Rougier, A.

2008-01-01

Enhanced sorption properties of ball-milled MgH 2 are reported by adding NbF 5 . Among various catalyst amounts, 2 mol% of NbF 5 reveals to be the optimum concentration leading to significant reduction of the desorption temperature as well as faster kinetics of ball-milled MgH 2 . At 200 deg. C, temperature at which MgH 2 does not show any activity, MgH 2NbF 5 /2mol% composite desorbs 3.2 wt.% of H 2 in 50 mins. Interestingly, the addition of NbF 5 is also associated with an increase in the desorption pressure. At 300 deg. C, MgH 2NbF 5 /2mol% composite starts to desorb hydrogen at 600 mbar in comparison with 1 mbar for MgH 2 . Further improvements were successfully achieved by pre-grinding NbF 5 prior to ball-milling the catalyst with MgH 2 . Such pre-ground NbF 5 catalyzed MgH 2 composite desorbs 3 wt.% of H 2 at 150 deg. C. Improved properties are associated with smaller activation energies down to values close to the enthalpy of formation of MgH 2 . Finally, the mechanism at the origin of the enhancement is discussed in terms of catalyst stability, MgF 2 formation and electronic density localization

Investigation of the La2O3-Nb2O5-WO3 ternary phase diagram: Isolation and crystal structure determination of the original La3NbWO10 material

KAUST Repository

Vu, T.D.; Vu, T.D.; Barre, M.; Adil, Karim; Jouanneaux, A.; Suard, E.; Goutenoire, F.

2015-01-01

In the course of the exploration of the La2O3-WO3-Nb2O5 ternary phase diagram, a new compound with the formula La3NbWO10 was discovered. Its structure was determined from a combination of powder X-ray and neutron diffraction data. It crystallizes

Electronic, structural and magnetic studies of niobium borides of group 8 transition metals, Nb2MB2 (M=Fe, Ru, Os) from first principles calculations

International Nuclear Information System (INIS)

Touzani, Rachid St.; Fokwa, Boniface P.T.

2014-01-01

The Nb 2 FeB 2 phase (U 3 Si 2 -type, space group P4/mbm, no. 127) is known for almost 50 years, but until now its magnetic properties have not been investigated. While the synthesis of Nb 2 OsB 2 (space group P4/mnc, no. 128, a twofold superstructure of U 3 Si 2 -type) with distorted Nb-layers and Os 2 -dumbbells was recently achieved, “Nb 2 RuB 2 ” is still not synthesized and its crystal structure is yet to be revealed. Our first principles density functional theory (DFT) calculations have confirmed not only the experimental structures of Nb 2 FeB 2 and Nb 2 OsB 2 , but also predict “Nb 2 RuB 2 ” to crystalize with the Nb 2 OsB 2 structure type. According to chemical bonding analysis, the homoatomic B–B interactions are optimized and very strong, but relatively strong heteroatomic M–B, B–Nb and M–Nb bonds (M=Fe, Ru, Os) are also found. These interactions, which together build a three-dimensional network, are mainly responsible for the structural stability of these ternary borides. The density-of-states at the Fermi level predicts metallic behavior, as expected, from metal-rich borides. Analysis of possible magnetic structures concluded preferred antiferromagnetic ordering for Nb 2 FeB 2 , originating from ferromagnetic interactions within iron chains and antiferromagnetic exchange interactions between them. -- Graphical abstract: Nb 2 FeB 2 (U 3 Si 2 structure type, space group P4/mbm, no. 127) is predicted to order antiferromagnetically, due to the presence of iron chains which show ferromagnetic interactions in the chains and antiferromagnetic interactions between them. “Nb 2 RuB 2 ” is predicted to crystallize with the recently discovered Nb 2 OsB 2 twofold superstructure (space group P4/mnc, no. 128) of U 3 Si 2 structure type. The building of ruthenium dumbbells instead of chains along [001] is found to be responsible for the stabilization of this superstructure. Highlights: • Nb 2 FeB 2 is predicted to order antiferromagnetically. �

Vorinostat, Rituximab, Ifosfamide, Carboplatin, and Etoposide in Treating Patients With Relapsed or Refractory Lymphoma or Previously Untreated T-Cell Non-Hodgkin Lymphoma or Mantle Cell Lymphoma

Science.gov (United States)

2017-04-17

Adult Nasal Type Extranodal NK/T-cell Lymphoma; Anaplastic Large Cell Lymphoma; Angioimmunoblastic T-cell Lymphoma; Contiguous Stage II Mantle Cell Lymphoma; Cutaneous B-cell Non-Hodgkin Lymphoma; Extranodal Marginal Zone B-cell Lymphoma of Mucosa-associated Lymphoid Tissue; Nodal Marginal Zone B-cell Lymphoma; Noncontiguous Stage II Mantle Cell Lymphoma; Recurrent Adult Burkitt Lymphoma; Recurrent Adult Diffuse Large Cell Lymphoma; Recurrent Adult Diffuse Mixed Cell Lymphoma; Recurrent Adult Diffuse Small Cleaved Cell Lymphoma; Recurrent Adult Grade III Lymphomatoid Granulomatosis; Recurrent Adult Hodgkin Lymphoma; Recurrent Adult Immunoblastic Large Cell Lymphoma; Recurrent Adult Lymphoblastic Lymphoma; Recurrent Cutaneous T-cell Non-Hodgkin Lymphoma; Recurrent Grade 1 Follicular Lymphoma; Recurrent Grade 2 Follicular Lymphoma; Recurrent Grade 3 Follicular Lymphoma; Recurrent Mantle Cell Lymphoma; Recurrent Marginal Zone Lymphoma; Recurrent Mycosis Fungoides/Sezary Syndrome; Recurrent Small Lymphocytic Lymphoma; Splenic Marginal Zone Lymphoma; Stage I Cutaneous T-cell Non-Hodgkin Lymphoma; Stage I Mantle Cell Lymphoma; Stage I Mycosis Fungoides/Sezary Syndrome; Stage II Cutaneous T-cell Non-Hodgkin Lymphoma; Stage II Mycosis Fungoides/Sezary Syndrome; Stage III Cutaneous T-cell Non-Hodgkin Lymphoma; Stage III Mantle Cell Lymphoma; Stage III Mycosis Fungoides/Sezary Syndrome; Stage IV Cutaneous T-cell Non-Hodgkin Lymphoma; Stage IV Mantle Cell Lymphoma; Stage IV Mycosis Fungoides/Sezary Syndrome; Waldenström Macroglobulinemia

NbN/AlN/NbN tunnel junctions with high current density up to 54 kA/cm2

International Nuclear Information System (INIS)

Wang, Z.; Kawakami, A.; Uzawa, Y.

1997-01-01

We report on progress in the development of high current density NbN/AlN/NbN tunnel junctions for applications as submillimeter wave superconductor-insulator-superconductor mixers. A very high current density up to 54 kA/cm 2 , roughly an order of magnitude larger than any reported results for all-NbN tunnel junctions, was achieved in the junctions with about 1 nm thick AlN barriers. The magnetic field and temperature dependence of critical supercurrents were measured to investigate the Josephson tunneling behavior of critical supercurrents in the high-J c junctions. The junctions showed high-quality junction characteristics with a large gap voltage of 5 mV and sharp quasiparticle current rise (ΔV g =0.1 mV). The R sg /R N ratio was about 5 with a V m value of 14 mV measured at 4.2 K. copyright 1997 American Institute of Physics

Nanostructured TiO2 Doped with Nb as a Novel Support for PEMFC

Directory of Open Access Journals (Sweden)

Edgar Valenzuela

2013-01-01

Full Text Available Nowadays, one of the major issues of the PEMFC concerns the durability. Historically, carbon has been used as a catalyst support in PEMFC; nevertheless, under the environmental conditions of the cell, the carbon is oxidized, leaving the catalyst unsupported. In order to increase the stability and durability of the catalyst in the PEMFC, a novel nanostructured metallic oxide support is proposed. In this work, TiO2 was doped with Nb to obtain a material that combines chemical stability, high surface area, and an adequate electronic conductivity in order to be a successful catalyst support candidate for long-term PEMFC applications. The TiO2-Nb nanostructured catalyst support was physically and electrochemically characterized. According to the results, the TiO2-Nb offers high surface area and good particle dispersion; also, the electrochemical activity and stability of the support were evaluated under high potential conditions, where the TiO2-Nb proved to be much more stable than carbon.

Nanostructured rare earth doped Nb2O5: Structural, optical properties and their correlation with photonic applications

International Nuclear Information System (INIS)

Pereira, Rafael Ramiro; Aquino, Felipe Thomaz; Ferrier, Alban; Goldner, Philippe; Gonçalves, Rogéria R.

2016-01-01

In the present work, we report on a systematic study on structural and spectroscopic properties Eu 3+ and Er 3+ -doped Nb 2 O 5 prepared by sol–gel method. The Eu 3+ ions were used as structural probe to determine the symmetry sites occupied by lanthanide ions. The Eu 3+ -doped Nb 2 O 5 nanocrystalline powders were annealed at different temperatures to verify how the different Nb 2 O 5 crystalline phases affect the structure and the luminescence properties. Er 3+ -doped Nb 2 O 5 was prepared showing an intense NIR luminescence, and, visible luminescence on the green and red, deriving from upconversion process. The synthetized materials can find widespread applicability in photonics as red luminophor for white LED (with tricolor), optical amplifiers and upconverter materials. - Highlights: • Vis and NIR emission from nanostructured lanthanide doped Nb 2 O 5 . • Eu 3+ -doped Nb 2 O 5 as Red luminophor. • Multicolor tunability of intense upconversion emission from lanthanide doped Nb 2 O 5 . • Potential application as biological markers. • Broad band NIR emission.

Continuous, flexible, and high-strength superconducting Nb3Ge and Nb3Sn filaments

International Nuclear Information System (INIS)

Ahmad, I.; Heffernan, W.J.

1976-01-01

Fabrication of continuous, flexible, and high-strength (1600 MN/m 2 ) composite filaments of Nb 3 Ge (T/subc/ 18 0 K) and Nb 3 Sn is reported, involving chemical vapor deposition of these compounds on Nb-coated high-strength W--1% ThO 2 filaments

Crystal and magnetic structures of Cr{sub 1∕3}NbSe{sub 2} from neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Gubkin, A. F., E-mail: agubkin@imp.uran.ru; Baranov, N. V. [M.N. Miheev Institute of Metal Physics, Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Natural Sciences, Ural Federal University, 620083 Yekaterinburg (Russian Federation); Proskurina, E. P.; Sherokalova, E. M.; Selezneva, N. V. [Institute of Natural Sciences, Ural Federal University, 620083 Yekaterinburg (Russian Federation); Kousaka, Y.; Akimitsu, J. [Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Center for Chiral Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Miao, P.; Lee, S.; Ishikawa, Y.; Torii, S. [Institute of Materials Structure Science, KEK, Tokai, Ibaragi 319-1106 (Japan); Zhang, J. [Institute of Materials Structure Science, KEK, Tokai, Ibaragi 319-1106 (Japan); China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803, Guangdong (China); Kamiyama, T. [Institute of Materials Structure Science, KEK, Tokai, Ibaragi 319-1106 (Japan); Sokendai (Graduate University for Advanced Studies), KEK, Tokai, Ibaragi 319-1106 (Japan); Campo, J. [Aragón Materials Science Institute (CSIC - University of Zaragoza), 50009 Zaragoza (Spain)

2016-01-07

Neutron diffraction measurements of the Cr intercalated niobium diselenide Cr{sub 1∕3}NbSe{sub 2} together with magnetization measurements have revealed that this compound exhibits ferromagnetic ordering below T{sub C} = 96 K unlike a chiral helimagnetic order observed in the sulfide compound Cr{sub 1∕3}NbS{sub 2}. As derived from neutron diffraction data, the Cr magnetic moments μ{sub Cr} = 2.83 ± 0.03 μ{sub B} in Cr{sub 1∕3}NbSe{sub 2} are aligned within basal plane. The discrepancy in the magnetic states of Cr{sub 1∕3}NbS{sub 2} and Cr{sub 1∕3}NbSe{sub 2} is ascribed to the difference in the preferential site occupation of Cr ions in crystal lattices. In Cr{sub 1∕3}NbSe{sub 2}, the Cr ions are predominantly distributed over 2b Wyckoff site, which determines a centrosymmetric character of the crystal structure unlike Cr{sub 1∕3}NbS{sub 2}, where the Cr ions are mainly located in 2c position and the crystal structure is non-centrosymmetric.

Current-Voltage Characteristics of Nb2O5 nanoporous via light illumination

Science.gov (United States)

Samihah Khairir, Nur; Rani, Rozina Abdul; Fazlida Hanim Abdullah, Wan; Hafiz Mamat, Mohamad; Kadir, Rosmalini Abdul; Rusop, M.; Sabirin Zoolfakar, Ahmad

2018-03-01

This work discussed the effect of light on I-V characteristics of anodized niobium pentoxide (Nb2O5) which formed nanoporous structure film. The structure was synthesized by anodizing niobium foils in glycerol based solution with 10 wt% supplied by two different voltages, 5V and 10V. The anodized foils that contained Nb2O5 film were then annealed to obtain an orthorhombic phase for 30 minutes at 450°C. The metal contact used for I-V testing was platinum (Pt) and it was deposited using thermal evaporator at 30nm thickness. I-V tests were conducted under different condition; dark and illumination to study the effect of light on I-V characteristics of anodized nanoporous Nb2O5. Higher anodization voltage and longer anodization time resulted in higher pore dispersion and larger pore size causing the current to increase. The increase of conductivity in I-V behaviour of Nb2O5 device is also affected by the illumination test as higher light intensity caused space charge region width to increase, thus making it easier for electron transfer between energy band gap.

Niobium Nb and tantalum Ta

International Nuclear Information System (INIS)

Busev, A.I.; Tiptsova, V.G.; Ivanov, V.M.

1978-01-01

The basic methods for determining niobium and tantalum in various objects are described. Nb and Ta are separated with the aid of N-benzoyl-N-phenylhydroxylamine by precipitating Nb(5) from a tartaric acid solution with subsequent precipitation of Ta from the filtrate. The gravimetric determination of Nb and Ta in steels is based on their quantitative separation from a diluted solution by way of hydrolysis with subsequent after-precipitation with phenylarsonic acid (in the absence of W). The gravimetric determination of Nb in the presence of W is carried out with the aid of Cupferron. To determine Nb in its carbide, Nb(5) reduced to Nb(3) is titrated with a solution of K 2 Cr 2 O 7 in the presence of phenyl-anthranilic acid. The photometric determination of Nb in tungsten-containing steels and in ores containing Ti, W, Mo and Cr is based on the rhodanide method. Nb is determined in alloys with Zr and Ti photometrically with the aid of 4-(2-pyridylazo)-resorcin and in alloyed steels with the aid of benzhydroxamic acid. The latter complex is extracted with chloroform. This method is used to determine Nb in rocks. The photometric determination of Ta in TiCl 4 is carried out with the aid of pyrogallol, in commercial niobium with the aid of methyl violet, and in steel with the aid of 4-(-pyridylazo)-resorcin. Also described is the polarographic determination of Nb in tantalum pentoxide

Insertion of lithium in Nb2O5

International Nuclear Information System (INIS)

Alves, M.C.M.; Bulhoes, L.O.S.; Castro, S.C.

1990-01-01

The electrode process during the reduction and oxidation of Nb sub(2) O sub(5) by cyclic voltametry was characterized. The surface analysis by X-ray photo electronic spectroscopy allowed characterize the surface processes, that happening during the insertion reaction. (author)

Formation and oxidation resistance of NbSi2 coatings on niobium by pack cementation

International Nuclear Information System (INIS)

Li Ming; Song Lixin; Le Jun; Zhang Xiaowei; Pei Baogen; Hu Xingfang

2005-01-01

NbSi 2 coatings were formed on niobium by halide-activated pack cementation process. The as-coated niobium samples were oxidized in air up to 1723 K by thermogravimetry method. The surface and cross-sectional morphology, phase composition and element distribution of the NbSi 2 coatings before and after oxidation were characterized by SEM, XRD and EPMA. The results show that the as-formed coatings consist of single phase of hexagonal NbSi 2 and the oxidation resistance of pure niobium can be greatly improved by pack siliconizing. (orig.)

High-pressure phases of Weyl semimetals NbP, NbAs, TaP, and TaAs

Science.gov (United States)

Guo, ZhaoPeng; Lu, PengChao; Chen, Tong; Wu, JueFei; Sun, Jian; Xing, DingYu

2018-03-01

In this study, we used the crystal structure search method and first-principles calculations to systematically explore the highpressure phase diagrams of the TaAs family (NbP, NbAs, TaP, and TaAs). Our calculation results show that NbAs and TaAs have similar phase diagrams, the same structural phase transition sequence I41 md→ P6¯ m2→ P21/ c→ Pm3¯ m, and slightly different transition pressures. The phase transition sequence of NbP and TaP differs somewhat from that of NbAs and TaAs, in which new structures emerge, such as the Cmcm structure in NbP and the Pmmn structure in TaP. Interestingly, we found that in the electronic structure of the high-pressure phase P6¯ m2-NbAs, there are coexistingWeyl points and triple degenerate points, similar to those found in high-pressure P6¯ m2-TaAs.

Double-hit or dual expression of MYC and BCL2 in primary cutaneous large B-cell lymphomas.

Science.gov (United States)

Menguy, Sarah; Frison, Eric; Prochazkova-Carlotti, Martina; Dalle, Stephane; Dereure, Olivier; Boulinguez, Serge; Dalac, Sophie; Machet, Laurent; Ram-Wolff, Caroline; Verneuil, Laurence; Gros, Audrey; Vergier, Béatrice; Beylot-Barry, Marie; Merlio, Jean-Philippe; Pham-Ledard, Anne

2018-03-26

In nodal diffuse large B-cell lymphoma, the search for double-hit with MYC and BCL2 and/or BCL6 rearrangements or for dual expression of BCL2 and MYC defines subgroups of patients with altered prognosis that has not been evaluated in primary cutaneous large B-cell lymphoma. Our objectives were to assess the double-hit and dual expressor status in a cohort of 44 patients with primary cutaneous large B-cell lymphoma according to the histological subtype and to evaluate their prognosis relevance. The 44 cases defined by the presence of more than 80% of large B-cells in the dermis corresponded to 21 primary cutaneous follicle centre lymphoma with large cell morphology and 23 primary cutaneous diffuse large B-cell lymphoma, leg type. Thirty-one cases (70%) expressed BCL2 and 29 (66%) expressed MYC. Dual expressor profile was observed in 25 cases (57%) of either subtypes (n = 6 or n = 19, respectively). Only one primary cutaneous follicle centre lymphoma, large-cell case had a double-hit status (2%). Specific survival was significantly worse in primary cutaneous diffuse large B-cell lymphoma, leg type than in primary cutaneous follicle centre lymphoma, large cell (p = 0.021) and for the dual expressor primary cutaneous large B-cell lymphoma group (p = 0.030). Both overall survival and specific survival were worse for patients belonging to the dual expressor primary cutaneous diffuse large B-cell lymphoma, leg type subgroup (p = 0.001 and p = 0.046, respectively). Expression of either MYC and/or BCL2 negatively impacted overall survival (p = 0.017 and p = 0.018 respectively). As the differential diagnosis between primary cutaneous follicle centre lymphoma, large cell and primary cutaneous diffuse large B-cell lymphoma, leg type has a major impact on prognosis, dual-expression of BCL2 and MYC may represent a new diagnostic criterion for primary cutaneous diffuse large B-cell lymphoma, leg type subtype and further identifies patients with

Non-Hodgkin's lymphoma in patients with systemic lupus erythematosus: 2 case reports

International Nuclear Information System (INIS)

Ferri, M.; Mar, C.; Bhatia, R.S.

2002-01-01

The association between autoimmune rheumatic diseases and malignancy, and between lymphoproliferative disorders and systemic lupus erythematosus (SLE), in particular, has been documented. Although the imaging features of pulmonary lymphoma and of pulmonary manifestations of SLE have been described separately, the imaging features of the 2 together have not been demonstrated. We present the cases of 2 patients with SLE presenting with non-Hodgkin's lymphoma (NHL). (author)

Synthesis, structural characterization and dielectric properties of Nb doped BaTiO3/SiO2 core–shell heterostructure

International Nuclear Information System (INIS)

Cernea, M.; Vasile, B.S.; Boni, A.; Iuga, A.

2014-01-01

Highlights: • Optimal parameters for preparation by sol–gel of core–shell (BT-Nb 0.005 )/SiO 2 are presented in this paper. • Single crystalline BT-Nb 0.005 /SiO 2 core–shell composite with ∼34 nm shell thick was prepared. • The core–shell ceramic exhibits good dielectric properties and ferroelectric characteristics. -- Abstract: Perovskite complex ceramic oxides, BaTiO 3 doped with 0.5 mol%Nb 2 O 5 and then nanocoated with SiO 2 (abbreviated as BT-Nb 0.005 /SiO 2 ) was successful prepared using conventional sol–gel processing. Phase composition, particle morphology, structure, and electric properties of BT-Nb 0.005 core and BT-Nb 0.005 /SiO 2 core–shell were examined and compared, using X-ray diffraction, transmission electron microscopy and, dielectric and ferroelectric measurements. Core–shell composite with well-defined perovskite tetragonal phase of BaTiO 3 was achieved. Furthermore, single crystalline BT-Nb 0.005 /SiO 2 core–nanoshell heterostructure with ∼34 nm shell thick was prepared, which is a novelty in ferroelectrics field. The ferroelectric quality of BT-Nb 0.005 has suffered an alteration when the (BT-Nb 0.005 )/SiO 2 core–shell heterostructure was realized. One-dimensional BT-Nb 0.005 /SiO 2 core–shell heterostructure exhibits an improvement of dielectric losses and a decrease of dielectric constant, compared to uncoated BT-Nb 0.005 . The (BT-Nb 0.005 )/SiO 2 core–shell material could be interesting for application in the composite capacitors

Shape memory characteristics of Ti-22Nb-(2-8)Zr(at.%) biomedical alloys

International Nuclear Information System (INIS)

Kim, J.I.; Kim, H.Y.; Inamura, T.; Hosoda, H.; Miyazaki, S.

2005-01-01

Shape memory characteristics of Ti-22Nb-(2-8)Zr(at.%) biomedical alloys were investigated by using tensile tests and X-ray diffraction (XRD) measurement. The alloy ingots were fabricated by an arc melting method. The ingots were cold-rolled by a reduction up to 95% in thickness at room temperature. All the alloys were solution-treated at 1173 K for 1.8 ks. The alloys subjected to the solution treatment exhibited large elongations ranging between 28 and 40%. The martensitic transformation temperature decreased by 38 K with 1 at.% increase of Zr content. The maximum recovered strain of 4.3% was obtained in the Ti-22Nb-4Zr(at.%) alloy. Ti-22Nb-(2-4)Zr(at.%) and Ti-22Nb-6Zr(at.%) alloys exhibited stable shape memory effect and superelastic behavior at room temperature, respectively

Whole-genome sequencing identifies recurrent somatic NOTCH2 mutations in splenic marginal zone lymphoma.

Science.gov (United States)

Kiel, Mark J; Velusamy, Thirunavukkarasu; Betz, Bryan L; Zhao, Lili; Weigelin, Helmut G; Chiang, Mark Y; Huebner-Chan, David R; Bailey, Nathanael G; Yang, David T; Bhagat, Govind; Miranda, Roberto N; Bahler, David W; Medeiros, L Jeffrey; Lim, Megan S; Elenitoba-Johnson, Kojo S J

2012-08-27

Splenic marginal zone lymphoma (SMZL), the most common primary lymphoma of spleen, is poorly understood at the genetic level. In this study, using whole-genome DNA sequencing (WGS) and confirmation by Sanger sequencing, we observed mutations identified in several genes not previously known to be recurrently altered in SMZL. In particular, we identified recurrent somatic gain-of-function mutations in NOTCH2, a gene encoding a protein required for marginal zone B cell development, in 25 of 99 (∼25%) cases of SMZL and in 1 of 19 (∼5%) cases of nonsplenic MZLs. These mutations clustered near the C-terminal proline/glutamate/serine/threonine (PEST)-rich domain, resulting in protein truncation or, rarely, were nonsynonymous substitutions affecting the extracellular heterodimerization domain (HD). NOTCH2 mutations were not present in other B cell lymphomas and leukemias, such as chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL; n = 15), mantle cell lymphoma (MCL; n = 15), low-grade follicular lymphoma (FL; n = 44), hairy cell leukemia (HCL; n = 15), and reactive lymphoid hyperplasia (n = 14). NOTCH2 mutations were associated with adverse clinical outcomes (relapse, histological transformation, and/or death) among SMZL patients (P = 0.002). These results suggest that NOTCH2 mutations play a role in the pathogenesis and progression of SMZL and are associated with a poor prognosis.

Cobalt-doped Ti–48Al–2Cr–2Nb alloy fabricated by cold compaction and pressureless sintering

Energy Technology Data Exchange (ETDEWEB)

Xia, Y. [The University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, Qld 4072 (Australia); Yu, P. [Department of Micro-Nano Material and Device, The South University of Science and Technology of China, Shenzhen, 518055 (China); Schaffer, G.B. [The University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, Qld 4072 (Australia); Qian, M., E-mail: ma.qian@uq.edu.au [The University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, Qld 4072 (Australia)

2013-07-01

An addition of 1.5 at% Co to Ti–48Al–2Cr–2Nb (in at%) transformed the alloy from essentially unsinterable to fully sinterable at 1300 °C. This, together with a simple powder coating process developed recently, has allowed near-net shape fabrication of the alloy for the first time by cold compaction and pressureless sintering. The addition of Co results in the formation of an intermediate face centred cubic (fcc) CoAl{sub 2}Ti phase prior to 1220 °C during heating. It subsequently reacts with an α phase leading to the formation of a Co-containing, wettable sintering liquid through a two-step process, CoAl{sub 2}Ti+α→Liquid at 1256.2 °C and CoAl{sub 2}Ti+α→γ-TiAl+Liquid at 1267.2 °C, and therefore full densification of the alloy. Without Co, sintering of the Ti–48Al–2Cr–2Nb alloy powder at 1300 °C is controlled by the slow self-diffusion of Ti and interdiffusion of Ti and Al according to the activation energy determined. Transmission electron microscopy (TEM) identified an fcc CoAl{sub 2}Ti phase and a hexagonal close packed (hcp) Co-enriched Ti(Al, Co, Cr, Nb) phase in the final as-sintered Ti–48Al–2Cr–2Nb–1.5Co alloy. They both form during cooling at 1240 °C through Liquid+α→CoAl{sub 2}Ti+Ti (Al, Co, Cr, Nb). The tensile and compressive properties of the as-sintered Ti–48Al–2Cr–2Nb–1.5Co alloy were compared to the original General Electric (GE) Ti–48Al–2Cr–2Nb alloy fabricated by casting or metal injection moulding.

Study and fabrication of ZnNb2O6 thin films by sol-gel method

International Nuclear Information System (INIS)

Hsu, Cheng-Hsing; Yang, Pai-Chuan; Yang, Hsi-Wen; Yan, Shu-Fong; Tung, Hsin-Han

2011-01-01

Zinc niobium oxide (ZnNb 2 O 6 ) thin films were grown on ITO/glass substrate by sol-gel process. Microstructure and surface morphology of the ZnNb 2 O 6 thin films have been studied by X-ray diffraction and scanning electron microscopy. Optical properties of the ZnNb 2 O 6 thin films were obtained by UV-visible recording spectrophotometer. The dependence of the microstructure, optical transmittance spectra, optical band gap on annealing temperature was also investigated.

Evolution of ferroelectric SrBi2Nb2O9 phase embedded in tellurite glass

Science.gov (United States)

Mohamed, E. A.

2017-12-01

Glasses with the composition, [(100-x)TeO2- x(SrO-Bi2O3-Nb2O5)] with x = 20, 30 and 40 (in mol %) were prepared. The X-ray diffraction (XRD) pattern and differential thermal analysis (DTA) for the as-prepared samples confirmed the amorphous and glassy characteristics, respectively. The SrBi2Nb2O9 phase in tellurite glass for HT773 sample at x = 40 mol % is formed and confirmed by the Rietveld refinement. DTA curves for all glass samples exhibit two endothermic dips while the two broad exothermic peaks at lower x reduced to one at higher x. Infrared (IR) results revealed that the glassy matrix are composed of TeO3, TeO3+1, TeO4, BiO6 and NbO6 structural units. The changes in the density (ρ), molar volume (Vm), oxygen molar volume (V0) and oxygen packing fraction (OPD) have correlated with structural changes in the glass network. The optical studies show an absorption bands below the absorption edge in the glass samples.

Influence of Nb dopant on the structural and optical properties of nanocrystalline TiO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Kaleji, Behzad Koozegar, E-mail: bkaleji@yahoo.com [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box:14115-143, Tehran (Iran, Islamic Republic of); Sarraf-Mamoory, Rasoul, E-mail: rsarrafm@modares.ac.ir [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box:14115-143, Tehran (Iran, Islamic Republic of); Fujishima, Akira [Photo-catalyst Group, Kanagawa Academy of Science and Technology, KSP East 412, 3-2-1 Sakado, Takatsu-ku, Kawasaki, Kanagawa 213-0012 (Japan)

2012-01-16

Highlights: Black-Right-Pointing-Pointer We coated Nb-doped TiO{sub 2} films on glazed porcelain via sol-gel dip coating method. Black-Right-Pointing-Pointer We examined coatings by degradation of MB solution and optical light transmittance. Black-Right-Pointing-Pointer Coatings show enhanced photo-catalytic activity in 1 mol% Nb. Black-Right-Pointing-Pointer Nb doping inhibited the grain growth, and which are found to inhibit the anatase to rutile phase transformation. - Abstract: In this study, preparation of Nb-doped (0-20 mol% Nb) TiO{sub 2} dip-coated thin films on glazed porcelain substrates via sol-gel process has been investigated. The effects of Nb on the structural, optical, and photo-catalytic properties of applied thin films have been studied by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Surface topography and surface chemical state of thin films was examined by atomic force microscope and X-ray photoelectron spectroscopy. XRD and Raman study showed that the Nb doping inhibited the grain growth. The photo-catalytic activity of the film was tested on degradation of methylene blue. Best photo-catalytic activity of Nb-doped TiO{sub 2} thin films were measured in the TiO{sub 2}-1 mol% Nb sample. The average optical transmittance of about 47% in the visible range and the band gap of films became wider with increasing Nb doping concentration. The Nb{sup 5+} dopant presented substitutional Ti{sup 4+} into TiO{sub 2} lattice.

Spectroscopic and optical properties of the VO2+ ion doped TeO2-TiO2-ZnO-Nb2O5 glass system

Science.gov (United States)

Swapna; Upender, G.; Sreenivasulu, V.; Prasad, M.

2016-04-01

Studies such as optical absorption, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Electron paramagnetic resonance (EPR) spectroscopy and Differential scanning calorimetry (DSC) were carried out on VO2+ ion doped TeO2-TiO2-ZnO-Nb2O5 glass system. Raman and FTIR spectra of the glasses revealed the presence of [TeO3], [TeO4] and [NbO6] structural units in the glass network. The Urbach energy (Δ E), cut-off wavelength (λ c ), optical band gap ( E opt ), optical basicity (Λ) and electron polarizability ( α) of the glasses were determined from optical absorption studies. The density ( ρ), molar volume ( V m ), oxygen molar volume ( V o ) and refractive index ( n) were also measured. Spin-Hamiltonian parameters were calculated from the EPR studies. When Nb2O5 was increased at the expense of ZnO, the density, optical band gap and Urbach energy of the glasses increased, and the electronic polarizability and optical basicity decreased. The EPR spectra clearly showed that vanadium was in the glass as VO2+ and occupied octahedral sites with tetrahedral compression. Spin-Hamiltonian parameters g‖ and g⊥ decreased as Nb2O5 content increased in the glass. The glass transition temperature ( T g ) also increased with increasing Nb2O5 content in the glass.

Fabrication and characterization of perovskite-type solar cells with Nb-doped TiO{sub 2} layers

Energy Technology Data Exchange (ETDEWEB)

Saito, Jo; Oku, Takeo, E-mail: oku@mat.usp.ac.jp; Suzuki, Atsushi; Akiyama, Tsuyoshi [The University of Shiga Prefecture, Hikone, Shiga 522-8533 (Japan)

2016-02-01

Organic-inorganic hybrid heterojunction solar cells containing perovskite CH{sub 3}NH{sub 3}PbI{sub 3} using Nb-doped TiO{sub 2} as an electron-transporting layer were fabricated and characterized. Nb-doped TiO{sub 2} layer showed an improvement of the short-circuit current density and power conversion efficiency using Ti{sub 0.95}Nb{sub 0.05}O{sub 2}.

How I treat double-hit lymphoma.

Science.gov (United States)

Friedberg, Jonathan W

2017-08-03

The 2016 revision of the World Health Organization (WHO) classification for lymphoma has included a new category of lymphoma, separate from diffuse large B-cell lymphoma, termed high-grade B-cell lymphoma with translocations involving myc and bcl-2 or bcl-6 . These lymphomas, which occur in hit lymphomas (or triple-hit lymphomas if all 3 rearrangements are present). It is important to differentiate these lymphomas from the larger group of double-expressor lymphomas, which have increased expression of MYC and BCL-2 and/or BCL-6 by immunohistochemistry, by using variable cutoff percentages to define positivity. Patients with double-hit lymphomas have a poor prognosis when treated with standard chemoimmunotherapy and have increased risk of central nervous system involvement and progression. Double-hit lymphomas may arise as a consequence of the transformation of the underlying indolent lymphoma. There are no published prospective trials in double-hit lymphoma, however retrospective studies strongly suggest that aggressive induction regimens may confer a superior outcome. In this article, I review my approach to the evaluation and treatment of double-hit lymphoma, with an eye toward future clinical trials incorporating rational targeted agents into the therapeutic armamentarium. © 2017 by The American Society of Hematology.

Magnetization anomaly of Nb3Al strands and instability of Nb3Al Rutherford cables

International Nuclear Information System (INIS)

Yamada, Ryuji; Kikuchi, Akihiro; Wake, Masayoshi

2006-01-01

Using a Cu stabilized Nb 3 Al strand with Nb matrix, a 30 meter long Nb 3 Al Rutherford cable was made by a collaboration of Fermilab and NIMS. Recently the strand and cable were tested. In both cases instability was observed at around 1.5 Tesla. The magnetization of this Nb 3 Al strand was measured first using a balanced coil magnetometer at 4.2 K. Strands showed an anomalously large magnetization behavior around at 1.6 T, which is much higher than the usual B c2 ∼ 0.5 Tesla (4.2 K) of Nb matrix. This result is compared with the magnetization data of short strand samples using a SQUID magnetometer, in which a flux-jump signal was observed at 0.5 Tesla, but not at higher field. As a possible explanation for this magnetization anomaly, the interfilament coupling through the thin Nb films in the strands is suggested. The instability problem observed in low field tests of the Nb 3 Al Rutherford cables is attributed to this effect

The influence of oxide on the electrochemical processes in K2NbF7-NaCl-KCl melts

DEFF Research Database (Denmark)

Lantelme, F.; Berghoute, Y.; Barner, Jens H. Von

1995-01-01

Transient electrochemical techniques showed that in NaCl-KCl melts the reduction of K2NbF7 occurs through atwo-step reaction Nb(V) --> Nb(IV) --> Nb. When oxide ions were introduced, cyclic voltammetry indicated that the wavescorresponding to reduction of the complex NbF72- progressively...

Highly retarded M2 transition in 90Nb

International Nuclear Information System (INIS)

Sergeev, V.O.

2006-01-01

One studied properties of 2.3 keV transition between 124.67 (4 - ) and 122.37 keV (6 + ) in 90 Nb. The mentioned M2-transition is shown to be retarded by approximately 10 4 times and provided explanations of the mentioned extraordinary high factor of deceleration. One evaluated impurity of E3 possible multipolarity constituent in the mentioned transition (δ 2 [ru

Flexible Nb2O5 nanowires/graphene film electrode for high-performance hybrid Li-ion supercapacitors

Science.gov (United States)

Song, Hao; Fu, Jijiang; Ding, Kang; Huang, Chao; Wu, Kai; Zhang, Xuming; Gao, Biao; Huo, Kaifu; Peng, Xiang; Chu, Paul K.

2016-10-01

The hybrid Li-ion electrochemical supercapacitor (Li-HSC) combining the battery-like anode with capacitive cathode is a promising energy storage device boasting large energy and power densities. Orthorhombic Nb2O5 is a good anode material in Li-HSCs because of its large pseudocapacitive Li-ion intercalation capacity. Herein, we report a high-performance, binder-free and flexible anode consisting of long Nb2O5 nanowires and graphene (L-Nb2O5 NWs/rGO). The paper-like L-Nb2O5 NWs/rGO film electrode has a large mass loading of Nb2O5 of 93.5 wt% as well as short solid-state ion diffusion length, and enhanced conductivity (5.1 S cm-1). The hybrid L-Nb2O5 NWs/rGO paper electrode shows a high reversible specific capacity of 160 mA h g-1 at a current density of 0.2 A g-1, superior rate capability with capacitance retention of 60% when the current density increases from 0.2 to 5 A g-1, as well as excellent cycle stability. The Li-HSC device based on the L-Nb2O5/rGO anode and the cathode of biomass-derived carbon nanosheets delivers an energy density of 106 Wh kg-1 at 580 W kg-1 and 32 Wh kg-1 at a large power density of 14 kW kg-1. Moreover, the Li-HSC device exhibits excellent cycling performance without obvious capacitance decay after 1000 cycles.

The optimization of NbTi-Nb/sub 3/Sn high field superconducting magnet used for physics experiments

International Nuclear Information System (INIS)

Han, B.; Han, S.; Feng, Z.X.

1989-01-01

The approach to the optimum cost design of multigraded NbTi-Nb/sub 3/Sn high field superconducting magnet is proposed. Investigation shows that by reasonably choosing the contribution of NbTi and Nb/sub 3/Sn coils to the central field required and properly increasing the parameters β of both NbTi and Nb/sub 2/Sn coils, the optimum cost design of the NbTi-Nb/sub 3/Sn solenoid magnet can be obtained. This is the base on which the minimum cost design of multi-graded NbTi-Nb/sub 3/Sn high field superconducting magnet is reached. As an example, a calculation of a 14T three graded NbT-Nb/sub 3/Sn superconducting magnet with a bore of 31mm in diameter is given

Promotion of Nb2O5 on the wustite-based iron catalyst for ammonia synthesis

International Nuclear Information System (INIS)

Han, Wenfeng; Huang, Shiliang; Cheng, Tianhong; Tang, Haodong; Li, Ying; Liu, Huazhang

2015-01-01

Highlights: • Niobium enhances the reduction of wustite-based ammonia synthesis catalyst significantly. • Nb 2 O 5 inhibits the segregation or formation of solid solutions on the catalyst surface. • Nb 2 O 5 doping enhances the growth rates of [2 1 1] and [2 0 0] planes rather than their amounts. - Abstract: Niobium was selected and investigated as a potential promoter for wustite-based catalyst (WBC) for ammonia synthesis. Experiments on reduction performance, activity test and H 2 -TGA, in situ XRD as well as XPS were carried out to obtain the promotion effect and mechanism involved. Niobium as a promoter was confirmed to enhance the reduction of WBC significantly. This behavior is highly desired for industry in terms of catalyst regeneration and lesser pretreatment time for fabrication regardless the unimproved catalytic performance for Nb 2 O 5 -doped wustite-based catalyst (Nb-WBC). Possible reasons for these phenomena are discussed. It is suggested that Nb 2 O 5 is not favorable for the segregation or formation of solid solutions on the catalyst surface, which are difficult to be reduced. However, it seems that niobium does not promote the growth of [2 1 1] plane, which is active for ammonia synthesis.

Reduced TET2 function leads to T-cell lymphoma with follicular helper T-cell-like features in mice

International Nuclear Information System (INIS)

Muto, H; Sakata-Yanagimoto, M; Nagae, G; Shiozawa, Y; Miyake, Y; Yoshida, K; Enami, T; Kamada, Y; Kato, T; Uchida, K; Nanmoku, T; Obara, N; Suzukawa, K; Sanada, M; Nakamura, N; Aburatani, H; Ogawa, S; Chiba, S

2014-01-01

TET2 (Ten Eleven Translocation 2) is a dioxygenase that converts methylcytosine (mC) to hydroxymethylcytosine (hmC). TET2 loss-of-function mutations are highly frequent in subtypes of T-cell lymphoma that harbor follicular helper T (Tfh)-cell-like features, such as angioimmunoblastic T-cell lymphoma (30–83%) or peripheral T-cell lymphoma, not otherwise specified (10–49%), as well as myeloid malignancies. Here, we show that middle-aged Tet2 knockdown (Tet2 gt/gt ) mice exhibit Tfh-like cell overproduction in the spleen compared with control mice. The Tet2 knockdown mice eventually develop T-cell lymphoma with Tfh-like features after a long latency (median 67 weeks). Transcriptome analysis revealed that these lymphoma cells had Tfh-like gene expression patterns when compared with splenic CD4-positive cells of wild-type mice. The lymphoma cells showed lower hmC densities around the transcription start site (TSS) and higher mC densities at the regions of the TSS, gene body and CpG islands. These epigenetic changes, seen in Tet2 insufficiency-triggered lymphoma, possibly contributed to predated outgrowth of Tfh-like cells and subsequent lymphomagenesis. The mouse model described here suggests that TET2 mutations play a major role in the development of T-cell lymphoma with Tfh-like features in humans

Nb-TiO{sub 2}/polymer hybrid solar cells with photovoltaic response under inert atmosphere conditions

Energy Technology Data Exchange (ETDEWEB)

Lira-Cantu, Monica; Khoda Siddiki, Mahbube; Munoz-Rojas, David; Amade, Roger [Centre d' Investigacio en Nanociencia i Nanotecnologia (CIN2, CSIC), Laboratory of Nanostructured Materials for Photovoltaic Energy, Campus UAB, Barcelona (Spain); Gonzalez-Pech, Natalia I. [Centre d' Investigacio en Nanociencia i Nanotecnologia (CIN2, CSIC), Laboratory of Nanostructured Materials for Photovoltaic Energy, Campus UAB, Barcelona (Spain); Instituto Tecnologico y de Estudios Superiores de Monterrey (ITESM), Ave. Eugenio Garza Sada, 64640 Monterrey, N.L. (Mexico)

2010-07-15

Hybrid Solar Cells (HSC) applying Nb-TiO{sub 2} in direct contact with a conducting organic polymer, MEH-PPV, show higher stability than the bare TiO{sub 2}-based HSC when analyzed under inert atmosphere conditions. IPCE analyses revealed that inert atmospheres affect directly the semiconductor oxide in the first stages of the analyses but photovoltaic performance stabilizes after several hours. A 20 wt% Nb-doped TiO{sub 2} presented the highest stability and photovoltaic properties. The behavior has been attributed to the solubility limit of Nb within the TiO{sub 2} beyond 20 wt% doping level where the co-existence of NbO{sub 2} is observed. The HSCs were analyzed under controlled N{sub 2} atmosphere and 1000 W/m{sup 2} (AM 1.5) irradiation. (author)

Value of low-dose 2 X 2 Gy palliative radiotherapy in advanced low-grade non-Hodgkin's lymphoma

International Nuclear Information System (INIS)

Ng, M.; Wirth, A.; Ryan, G.; MacManus, M.

2006-01-01

Low-dose radiotherapy over the last decade has been reported to provide effective palliation for patients with low-grade non-Hodgkin's lymphoma. In this retrospective case series of 10 patients, we report our early experience using low-dose radiotherapy (usually 2 x2 Gy) for patients with advanced-stage follicular, mucosal associated lymphoid tissue, mantle cell and small lymphocytic lymphomas. Median follow up was 27 weeks. Response rates were high (complete response, 70%; partial response, 20%), the response durable and the toxicity was minimal (no toxicity greater than grade 1). Low-dose irradiation is an effective treatment option for patients with low-grade lymphomas with local symptoms Copyright (2006) Blackwell Publishing Asia Pty Ltd

Synthesis and characterization of Nb_2O_5 by a colloidal route

International Nuclear Information System (INIS)

Falk, G.S.; Borlaf, M.; Oliveira, A.P. Novaes de; Rodrigues Neto, J.B.; Hotza, D.; Moreno, R.

2014-01-01

The niobium pentoxide (Nb_2O_5) is known to be a polymorphic ceramic semiconductor and display features, which makes it a potential candidate in the field of photocatalysis. In this paper, we evaluate a colloidal route for the synthesis of Nb_2O_5. The properties of the suspension and the powder obtained were determined by analysis of particle size, zeta potential, thermogravimetric and differential thermal analysis (TG-DTA) and X-ray diffraction (XRD). The results indicated that the particle size was 0.3 μm and at pHs between 8 and 9, stable suspensions were obtained. Through the XRD results it was observed that the synthesized powder is amorphous and that at 300°C/1h niobic acid (HNbO_3) crystallizes, which after calcination at 450, 650, 850 and 1050 deg C/1h, turns into Nb_2O_5 with different crystalline structures. (author)

Isolated orbital mass as the primary presentation of a triple-hit lymphoma transformed from a systemic follicular lymphoma

Directory of Open Access Journals (Sweden)

Xiao Yi Zhou

2018-06-01

Full Text Available Purpose: Triple-hit lymphoma is a highly aggressive B-cell lymphoma. We report a case of triple-hit lymphoma transformed from systemic follicular lymphoma (FL after 9-year remission and presented primarily as an isolated orbital mass without systemic symptoms or lymphadenopathy. Observations: A 58-year-old female presented with intermittent vertical binocular diplopia, left upper eyelid swelling and pain and was found to have a 2.9 cm orbital mass. Histological section revealed a CD10-positive large B-cell lymphoma, consistent with transformation of FL. Fluorescent in situ hybridization (FISH analysis demonstrated rearrangements involving C-MYC, BCL-2 and BCL-6 genes, indicating a high grade, triple-hit lymphoma. Conclusions and importance: Triple-hit lymphoma transformed from a low-grade lymphoma may initially present as an isolated orbital mass without systemic evidence of transformation. Early recognition of double or triple-hit lymphomas is important since these patients require aggressive chemotherapy. Keywords: Lymphoma, Triple-hit lymphoma, Orbital mass

Corrosion kinetics at high pressure and temperature of Zr-2.5 Nb with different heat treatments

International Nuclear Information System (INIS)

Jaime Solis, F.; Bordoni, Roberto; Olmedo, Ana M.; Villegas, Marina; Miyagusuku, Marcela

2003-01-01

The corrosion behaviour of Zr-2.5 Nb pressure tube (PT) specimens, with ageing treatments at 400 and 500 C degrees for different times, was studied. The results were analyzed using the corrosion behavior of Zr-20 Nb and Zr-1 Nb samples heat treated during 1 hour at 850 C degrees, cooled in air and aged at the same temperature and times than the PT specimens. The comparison between the corrosion behaviour of Zr-1 Nb and Zr-20 Nb aged coupons with the aged pressure tube specimens, together with the metal/oxide interface morphology of Zr-2.5 Nb specimens, suggest that the increase in the corrosion resistance in the latter coupons is associated with the decomposition of the β-Zr phase. There is also a contribution of α-Zr phase when the ageing temperatures are high enough or the ageing times are long enough, due to a decrease in the Nb content of this phase. This last contribution is associated with an increase in the corrosion resistance of the central zone of pressure tube in the reactor. (author)

Effects of alloying and temperature on the high-temperature oxidation of Cr-Cr{sub 2}Nb

Energy Technology Data Exchange (ETDEWEB)

Tortorelli, P.F.; DeVan, J.H. [Oak Ridge National Lab., TN (United States); Carson, L.J. [Lincoln Univ., PA (United States)

1993-06-01

Effects of alloying additions and temperature on isothermal and cyclic oxidation resistance of Cr-Cr{sub 2}Nb alloys were examined for air exposures. An isothermal exposure temperature of 1100C led to rapid reaction of binary Cr-12 at.% Nb as manifested a high oxidation rate and nonprotective behavior. Generally parabolic kinetics, complicated by some isothermal scale cracking, were observed at 900--1000C. Scale damage was exacerbated by thermal cycling. The addition of 8 at.% Al to Cr-12 at.% Nb did not effect cyclic oxidation resistance, but there was some evidence that scale adherence on Cr-6 at.% Nb-8 at.% Al was better than that for binary Cr-6 at.% Nb. Alloying additions of Al (up to 18 at.%) or Re (2 at.%) did not improve the isothermal oxidation resistance of Cr-12 at.% Nb. However, the tendency for scale damage during both isothermal and thermal cycling exposures suggests that alloying additions that specifically improve scale plasticity or modify growth stresses could be effective for Cr-Nb alloys. 10 refs, 9 figs, 1 tab.

Facile preparation of C, N co-modified Nb2O5 nanoneedles with enhanced visible light photocatalytic activity

KAUST Repository

Xue, Jiao

2016-09-28

C, N co-modified niobium pentoxide (Nb2O5) nanoneedles have been successfully synthesized via a facile hydrothermal method with Niobium Chloride (NbCl5) as a precursor and triethylamine as both the carbon and nitrogen source. The formation process of Nb2O5 nanoneedles has been presented in detail by investigating the effect of the crystallization temperature, the amount of triethylamine and the calcination temperature. The as-prepared Nb2O5 nanoneedles exhibit more efficient photocatalytic activity than commercial Degussa P25 and commercial Nb2O5 towards photodegradation of Rhodamine B (RhB) at a concentration of 10 mg L−1 under visible light. Special chemical species, such as carbonate species and NOX species, that exist on the surface of the as-prepared catalyst could extend the absorption into the visible region and thus enhance the photocatalytic activity of the Nb2O5 nanoneedles. At the same time, the obtained Nb2O5 nanoneedles exhibit excellent stability even after three successive cycles. A possible photodegradation mechanism was proposed and the corresponding photodecomposition process of RhB over the Nb2O5 nanoneedles was elucidated by a reactive species trapping experiment, suggesting that h+ and O2˙− play a major role in the photodegradation of RhB in aqueous solution.

Determination of Nb in ZrO2 matrix using Wavelength Dispersive X-Ray Fluorescence (WDXRF) technique

International Nuclear Information System (INIS)

Jha, S.N.; Kapoor, S.K.; Malhotra, S.K.; Kaimal, R.; Kamat, M.J.; Sehra, J.C.

1998-09-01

A Wavelength Dispersive X-Ray Fluorescence (WDXRF) method is described for the estimation of niobium in ZrO 2 matrix in the concentration range of 0.5 to 35%. Analysis of Nb is desired during the reclamation of zirconium from Zr-2.5% Nb scrap. Zr-2.5% Nb is used in water cooled nuclear power reactors on account of high creep resistance and strength. For the reclamation of these metals from the scrap, chlorination is done to produce mixed chloride. The mixed chloride is treated to obtain individual chloride for eventually converting to respective metal. Analysis is required to ascertain purity of these metals reclaimed from the scrap. Primary x-rays from gold target x-ray tube were used to excite the K lines of Nb. A linear relation has been found between the intensity of Nb-Kα 1,2 line and concentration in the above range and the detection limit was 0.03% for 10 seconds counting time. (author)

Peierls-distorted Ru-chains and boron dumbbells in Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} from first-principles calculations and experiments

Energy Technology Data Exchange (ETDEWEB)

Touzani, Rachid S.; Mbarki, Mohammed; Chen, Ximeng [Institute of Inorganic Chemistry, RWTH Aachen University (Germany); Fokwa, Boniface P.T. [Institute of Inorganic Chemistry, RWTH Aachen University (Germany); Department of Chemistry, University of California Riverside (UCR), Riverside, CA (United States)

2016-09-15

Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} phases were recently predicted by GGA-VASP structure optimization to crystallize in the Nb{sub 2}OsB{sub 2}-type structure. Although the Fe-based (Mo{sub 2}FeB{sub 2} type) and Os-based (Nb{sub 2}OsB{sub 2} type, superstructure variant of Mo{sub 2}FeB{sub 2} type) analogues have been synthesized and characterized successfully, the Ru-based phases remained unknown. Crystal structure prediction of Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} phases, using an evolutionary algorithm, led to the AlMn{sub 2}B{sub 2}-type structure in contrast to the aforementioned optimization; however, phonon calculations showed that the Nb{sub 2}OsB{sub 2}-type phases are dynamically more stable than the AlMn{sub 2}B{sub 2}-type phases. A slightly modified synthetic strategy finally led to the successful preparation of the predicted phases. The extremely quick arc-melting procedure, under argon atmosphere, not only led to a quantitative amount of the phases but also to single crystals suitable for structure determination. Powder and single-crystal X-ray diffraction as well as EDX analysis of the metal ratio have confirmed the GGA-VASP structure optimization: Nb{sub 2}RuB{sub 2} and Ta{sub 2}RuB{sub 2} compounds indeed crystallize isotypically with Nb{sub 2}OsB{sub 2} structure, a superstructure variant of Mo{sub 2}FeB{sub 2} type, in which B-dumbbells and Peierls-distorted Ru-chains are found. Susceptibility measurements on a Ta{sub 2}RuB{sub 2} single crystal reveal no superconducting transition down to 2 K, even though some features in the band structures of both phases, similar to those reported in superconducting NbRuB, hinted at possible superconductivity. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Electronic, structural and magnetic studies of niobium borides of group 8 transition metals, Nb{sub 2}MB{sub 2} (M=Fe, Ru, Os) from first principles calculations

Energy Technology Data Exchange (ETDEWEB)

Touzani, Rachid St.; Fokwa, Boniface P.T., E-mail: Boniface.Fokwa@ac.rwth-aachen.de

2014-03-15

The Nb{sub 2}FeB{sub 2} phase (U{sub 3}Si{sub 2}-type, space group P4/mbm, no. 127) is known for almost 50 years, but until now its magnetic properties have not been investigated. While the synthesis of Nb{sub 2}OsB{sub 2} (space group P4/mnc, no. 128, a twofold superstructure of U{sub 3}Si{sub 2}-type) with distorted Nb-layers and Os{sub 2}-dumbbells was recently achieved, “Nb{sub 2}RuB{sub 2}” is still not synthesized and its crystal structure is yet to be revealed. Our first principles density functional theory (DFT) calculations have confirmed not only the experimental structures of Nb{sub 2}FeB{sub 2} and Nb{sub 2}OsB{sub 2}, but also predict “Nb{sub 2}RuB{sub 2}” to crystalize with the Nb{sub 2}OsB{sub 2} structure type. According to chemical bonding analysis, the homoatomic B–B interactions are optimized and very strong, but relatively strong heteroatomic M–B, B–Nb and M–Nb bonds (M=Fe, Ru, Os) are also found. These interactions, which together build a three-dimensional network, are mainly responsible for the structural stability of these ternary borides. The density-of-states at the Fermi level predicts metallic behavior, as expected, from metal-rich borides. Analysis of possible magnetic structures concluded preferred antiferromagnetic ordering for Nb{sub 2}FeB{sub 2}, originating from ferromagnetic interactions within iron chains and antiferromagnetic exchange interactions between them. -- Graphical abstract: Nb{sub 2}FeB{sub 2} (U{sub 3}Si{sub 2} structure type, space group P4/mbm, no. 127) is predicted to order antiferromagnetically, due to the presence of iron chains which show ferromagnetic interactions in the chains and antiferromagnetic interactions between them. “Nb{sub 2}RuB{sub 2}” is predicted to crystallize with the recently discovered Nb{sub 2}OsB{sub 2} twofold superstructure (space group P4/mnc, no. 128) of U{sub 3}Si{sub 2} structure type. The building of ruthenium dumbbells instead of chains along [001] is found to be

Investigation of the La2O3-Nb2O5-WO3 ternary phase diagram: Isolation and crystal structure determination of the original La3NbWO10 material

KAUST Repository

Vu, T.D.

2015-05-23

In the course of the exploration of the La2O3-WO3-Nb2O5 ternary phase diagram, a new compound with the formula La3NbWO10 was discovered. Its structure was determined from a combination of powder X-ray and neutron diffraction data. It crystallizes in the tetragonal space group P42/nmc (no. 137) with the lattice parameters: a=10.0807(1) Å; c=12.5540(1) Å. The structure is built up from infinite ribbons of octahedra (W/Nb)O5 which are perpendicular to each other, lanthanum ions being distributed around these ribbons. The electrical properties of this compound were investigated on sintered pellets by means of complex impedance spectroscopy. © 2015 Elsevier Inc. All rights reserved.

Highly Stable and Active Pt/Nb-TiO2 Carbon-Free Electrocatalyst for Proton Exchange Membrane Fuel Cells

Directory of Open Access Journals (Sweden)

Shuhui Sun

2012-01-01

Full Text Available The current materials used in proton exchange membrane fuel cells (PEMFCs are not sufficiently durable for commercial deployment. One of the major challenges lies in the development of an inexpensive, efficient, and highly durable and active electrocatalyst. Here a new type of carbon-free Pt/Nb-TiO2 electrocatalyst has been reported. Mesoporous Nb-TiO2 hollow spheres were synthesized by the sol-gel method using polystyrene (PS sphere templates. Pt nanoparticles (NPs were then deposited onto mesoporous Nb-TiO2 hollow spheres via a simple wet-chemical route in aqueous solution, without the need for surfactants or potentiostats. The growth densities of Pt NPs on Nb-TiO2 supports could be easily modulated by simply adjusting the experimental parameters. Electrochemical studies of Pt/Nb-TiO2 show much enhanced activity and stability than commercial E-TEK Pt/C catalyst. PtNP/Nb-TiO2 is a promising new cathode catalyst for PEMFC applications.

A first-principles study of NbSe2 monolayer as anode materials for rechargeable lithium-ion and sodium-ion batteries

Science.gov (United States)

Lv, Xingshuai; Wei, Wei; Sun, Qilong; Huang, Baibiao; Dai, Ying

2017-06-01

There is a great desire to search for suitable anodes with good performance for rechargeable metal-ion batteries, which require not only large capacity but excellent rate performance and cycling stability. In this work, the electronic properties of NbSe2 monolayer were explored based on first-principles calculations. We performed a full geometry optimization for Li/Na-adsorbed structures and obtained favorable adsorption sites. The metallic character for both pristine NbSe2 monolayer and the Li/Na-adsorbed NbSe2 ensures good electrical conduction. In addition, we find that NbSe2 monolayer is more inclined to adsorb Li and Na atoms with smaller adsorption energy under Li/Na-rich condition, indicating the superiority of NbSe2 monolayer as an electrode. Then, we obtained a relatively low diffusion barrier of approximately 0.205 eV for Li and, in particular, a significantly small diffusion barrier of about 0.086 eV for Na, which ensures excellent cycling performance of NbSe2 monolayer as a battery electrode. Most importantly, the Li and Na adsorption density in NbSe2 monolayer can be as high as Li2NbSe2 and Na4NbSe2, corresponding to theoretical specific capacities of 203 and 312 mAh·g-1, respectively. And the average electrode potentials were predicted to be 0.51 V for the chemical stoichiometry of Li2NbSe2 and 0.22 V for Na4NbSe2. In view of these excellent properties, our work predicts that NbSe2 monolayer can be a promising anode material for the development of low-cost high-performance Li- and Na-ion batteries.

Efficient eNB inter-communication scheme in converged mobile and NG-PON2 system

Science.gov (United States)

Xiao, Simiao; Sun, Xiao; Zhang, Kaibin

2016-02-01

In LTE, a new X2-interface is defined to facilitate direct communication between neighboring eNBs. Since LTE is an all-IP network, the X2-interface traffic currently needs to be routed and transponded in L3 at the edge router by IP addressing. As mobile data increases, it is a promising trend to backhaul mobile services based on PON. In this paper, an effective approach for eNB inter-communication over TWDM-PON is proposed. By associating the IP address of eNB and the MAC address of ONU, the "inter-eNB communication in L3" can be mapped into "inter-ONU communication in L2" and transponded via the protocol of PON at the OLT. Thus, fast and cost-effective eNB inter-communication can be realized based on TWDM-PON within one wavelength channel and between different wavelength channels. The increasing data traffic pressure to the core network can also be alleviated.

Study of fluorine doped (Nb,Ir)O_2 solid solution electro-catalyst powders for proton exchange membrane based oxygen evolution reaction

International Nuclear Information System (INIS)

Kadakia, Karan Sandeep; Jampani, Prashanth H.; Velikokhatnyi, Oleg I.; Datta, Moni Kanchan; Patel, Prasad; Chung, Sung Jae; Park, Sung Kyoo; Poston, James A.; Manivannan, Ayyakkannu; Kumta, Prashant N.

2016-01-01

Graphical abstract: High surface area (∼300 m"2/g) nanostructured powders of nominal composition (Nb_1_−_xIr_x)O_2 and (Nb_1_−_xIr_x)O_2:10F have been synthesized and tested as oxygen evolution electro-catalysts for PEM based water electrolysis using a simple two-step chemical synthesis procedure. Superior electrochemical activity was demonstrated by fluorine doped compositions of (Nb_1_−_xIr_x)O_2 with an optimal composition (Nb_0_._7_5Ir_0_._2_5)O_2:10F (x = 0.25) demonstrating on-par performance with commercial hydrated IrO_2 and nanostructured in-house chemically synthesized IrO_2. Using first principles calculations, the electronic structure modification resulting in ∼75 at.% reduction (experimentally observed) in noble metal content without loss in catalytic performance and stability has been established. - Highlights: • (Nb_1_−_xIr_x)O_2:10F nanopowder electrocatalysts have been wet chemically synthesized. • (Nb_0_._7_5Ir_0_._2_5)O_2:10F exhibits superior electrochemical activity than pure IrO_2. • Stability of the (Nb,Ir)O_2:10F nanomaterials is comparable to pure (Nb,Ir)O_2. • High surface area F doped (Nb,Ir)O_2 are promising OER anode electro-catalysts. - Abstract: High surface area (∼300 m"2/g) nanostructured powders of (Nb_1_−_xIr_x)O_2 and (Nb_1_−_xIr_x)O_2:10F (∼100 m"2/g) have been examined as promising oxygen evolution reaction (OER) electro-catalysts for proton exchange membrane (PEM) based water electrolysis. Nb_2O_5 and 10 wt.% F doped Nb_2O_5 powders were prepared by a low temperature sol-gel process which were then converted to solid solution (Nb,Ir)O_2 and 10 wt.% F doped (Nb,Ir)O_2 [(NbIr)O_2:10F] electro-catalysts by soaking in IrCl_4 followed by heat treatment in air. Electro-catalyst powders of optimal composition (Nb_0_._7_5Ir_0_._2_5)O_2:10F with ∼75 at.% reduction in noble metal content exhibited comparable OER activity to commercial hydrated IrO_2 and nanostructured in-house chemically synthesized IrO_2

Study of the initial oxidation of the U4Zr2Nb alloy by X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Mendonca, Renato de; Ferraz, Wilmar B.; Braga, Daniel M.; Macedo, Waldemar A.A.

2009-01-01

In this work, the initial stages of oxidation of the U4Zr2Nb alloy in O 2 atmosphere were studied in-situ, in ultrahigh vacuum, by X-ray photoelectron spectroscopy (XPS), an advanced surface-sensitive technique. After several hours of Ar + ion-sputtering to surface cleanness, the O 2 exposures was realized on the sample at room temperature. The evolution of oxide film formed on the sample surface was followed by XPS measures, by using Mg K α radiation of 1253.6 eV and a CLAM-2 (Vacuum Generator) electron energy analyzer. The changes of U 4f, Nb 3d, Zr 3d and O 1s photoemission peaks with O 2 exposure indicate that the adsorption of oxygen on the U4Zr2Nb alloy surface leads to fast formation of UO 2 . The alloying elements show slower oxidation and different compounds are observed in Nb 3d spectra analysis. This work shows an expressive enlargement of Nb 3d peak at 100 Langmuir exposure, indicating the formation of Nb 2 O 5 and NbO in the oxide. On the other hand, the binding energy of Zr 3d suggests that the ZrO 2 formation is stable as well as uranium dioxide. (author)

Lymphoma classification update: B-cell non-Hodgkin lymphomas.

Science.gov (United States)

Jiang, Manli; Bennani, N Nora; Feldman, Andrew L

2017-05-01

Lymphomas are classified based on the normal counterpart, or cell of origin, from which they arise. Because lymphocytes have physiologic immune functions that vary both by lineage and by stage of differentiation, the classification of lymphomas arising from these normal lymphoid populations is complex. Recent genomic data have contributed additional complexity. Areas covered: Lymphoma classification follows the World Health Organization (WHO) system, which reflects international consensus and is based on pathological, genetic, and clinical factors. A 2016 revision to the WHO classification of lymphoid neoplasms recently was reported. The present review focuses on B-cell non-Hodgkin lymphomas, the most common group of lymphomas, and summarizes recent changes most relevant to hematologists and other clinicians who care for lymphoma patients. Expert commentary: Lymphoma classification is a continually evolving field that needs to be responsive to new clinical, pathological, and molecular understanding of lymphoid neoplasia. Among the entities covered in this review, the 2016 revision of the WHO classification particularly impact the subclassification and genetic stratification of diffuse large B-cell lymphoma and high-grade B-cell lymphomas, and reflect evolving criteria and nomenclature for indolent B-cell lymphomas and lymphoproliferative disorders.

B-site cation order/disorder and their valence states in Ba3MnNb2O9 perovskite oxide

Science.gov (United States)

Xin, Yan; Huang, Qing; Shafieizadeh, Zahra; Zhou, Haidong

2018-06-01

Polycrystalline samples Ba3MnNb2O9 synthesized by solid state reaction and single crystal samples grown by optical floating zone have been characterized using scanning transmission electron microscopy and electron energy loss spectroscopy. Three types of B-site Mn and Nb ordering phase are observed: fully ordered 1Mn:2Nb; fully disordered; nano-sized 1Mn:1Nb ordered. No electronic structure change for crystals with different ordering/disordering. The Mn valence is determined to be 2+, and Nb valence is 5+. Oxygen 2p orbitals hybridize with Mn 3d and Nb 4d orbitals. Factors that affect the electron energy loss near edge structures of transition metal white-lines in electron energy loss spectroscopy are explicitly illustrated and discussed.

Crystal structure and ion conducting properties of La5NbMo2O16

KAUST Repository

Vu, T.D.

2016-01-29

The new compound La5NbMo2O16 with high ionic conduction has been discovered during the study of the ternary phase diagram of La2O3-MoO3-Nb2O5. The material crystallizes in the cubic space group Pn 3n (no 222) with the unit cell parameter a=11.2250(1) Å. La5NbMo2O16 is a new analogue of the R5Mo3O16 series (R=Pr, Nd). The structure was refined from a combined data X-ray and neutron powder diffraction. The ionic conductivity of the compound is then measured on sintered pellets, by means of complex impedance spectroscopy. © 2016 Elsevier Inc. All rights reserved.

Solidification processing of intermetallic Nb-Al alloys

Science.gov (United States)

Smith, Preston P.; Oliver, Ben F.; Noebe, Ronald D.

1992-01-01

Several Nb-Al alloys, including single-phase NbAl3 and the eutectic of Nb2Al and NbAl3, were prepared either by nonconsumable arc melting in Ar or by zone processing in He following initial induction melting and rod casting, and the effect of the solidification route on the microstructure and room-temperature mechanical properties of these alloys was investigated. Automated control procedures and melt conditions for directional solidification of NbAl3 and the Nb2Al/Nb3Al eutectic were developed; high purity and stoichiometry were obtained. The effects of ternary additions of Ti and Ni are described.

Directional solidification and characterization of the Al Nb2 - Al3 Nb eutectic system

International Nuclear Information System (INIS)

Trevisan, Eduardo A.O.; Andreotti, Fabio; Caram, Rubens

1996-01-01

The manufacturing of components to operate at high temperatures requires the use of metallic materials which can keep satisfactory mechanical and chemical properties, even at temperatures beyond 1000 deg C. An interesting alternative is the use of directionally solidified eutectic alloys. The eutectic alloy solidification makes possible the production of 'in situ' composite. A potentially useful system for manufacturing structural materials is the Al-Nb eutectic system. The aim of this work is to present the directional solidification of the Al-Nb eutectic alloy. (author)

Preparation and characterization of Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composite oxide formed by cathodic electroplating and anodizing

Energy Technology Data Exchange (ETDEWEB)

Jang, Joo-Hee; Kim, Tae-Yoo; Kim, Nam-Jeong; Lee, Chang-Hyoung; Park, Eun-Mi [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Park, Chan [Division of Materials Science and Engineering, Pukyong National University, Busan 608-739 (Korea, Republic of); Suh, Su-Jeong, E-mail: suhsj@skku.ac.kr [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Advanced Materials and Process Research Center for IT, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2011-11-15

Highlights: > We fabricate Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3}/Al film for high performance thin film capacitor. > The optimum condition of electrolyte composition will coat NbO{sub x} on Al without corrosion of Al during the cathodic electroplating. > Increasing annealing temperature will form Nb{sub 2}O{sub 5} crystalline. > The Al{sub 2}O{sub 3} layer will form between Nb{sub 2}O{sub 5} layer and metal Al after anodizing and the thin film capacitor with Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3}/Al improve dielectric properties. - Abstract: Al foil was coated with niobium oxide by cathodic electroplating and anodized in a neutral boric acid solution to achieve high capacitance in a thin film capacitor. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) revealed the niobium oxide layer on Al to be a hydroxide-rich amorphous phase. The film was crystalline and had stoichiometric stability after annealing at temperatures up to 600 deg. C followed by anodizing at 500 V, and the specific capacitance of the Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composite oxide was approximately 27% higher than that of Al{sub 2}O{sub 3} without a Nb{sub 2}O{sub 5} layer. The capacitance was quite stable to the resonance frequency. Overall, the Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composite oxide film is a suitable material for thin film capacitors.

Isolated orbital mass as the primary presentation of a triple-hit lymphoma transformed from a systemic follicular lymphoma.

Science.gov (United States)

Zhou, Xiao Yi; Lu, Xinyan; Raparia, Kirtee; Chen, Yi-Hua

2018-06-01

Triple-hit lymphoma is a highly aggressive B-cell lymphoma. We report a case of triple-hit lymphoma transformed from systemic follicular lymphoma (FL) after 9-year remission and presented primarily as an isolated orbital mass without systemic symptoms or lymphadenopathy. A 58-year-old female presented with intermittent vertical binocular diplopia, left upper eyelid swelling and pain and was found to have a 2.9 cm orbital mass. Histological section revealed a CD10-positive large B-cell lymphoma, consistent with transformation of FL. Fluorescent in situ hybridization (FISH) analysis demonstrated rearrangements involving C-MYC, BCL-2 and BCL-6 genes, indicating a high grade, triple-hit lymphoma. Triple-hit lymphoma transformed from a low-grade lymphoma may initially present as an isolated orbital mass without systemic evidence of transformation. Early recognition of double or triple-hit lymphomas is important since these patients require aggressive chemotherapy.

Structural, electric and dielectric properties of Eu-doped SrBi2Nb2O9 ceramics obtained by co-precipitation route

Directory of Open Access Journals (Sweden)

Mohamed Afqir

2018-03-01

Full Text Available This paper presents a study of the structure and dielectric properties of Eu-doped SrBi2Nb2O9 ceramics prepared by co-precipitation route and sintered at 850 °C. The materials were examined using XRD and FTIR methods. XRD data indicated the formation of well crystallized structure of the pure and doped SrBi2Nb2O9, without the presence of undesirable phases. FTIR spectra do not bring a significant shift in the band positions. Moreover, the AC conductivity, dielectric constant and dielectric loss of the ceramics were determined through the frequency range [50 kHz–1 MHz]. In particular, the dielectric constant (ε′ and dielectric losses (tan δ of the SrBi2Nb2O9 and SrBi1.6Eu0.4Nb2O9 ceramics were measured as a function of temperature at various frequencies.

X-ray investigation of Nb/O interfaces

International Nuclear Information System (INIS)

Delheusy, Melissa

2008-01-01

X-ray free electron lasers and the future International Linear Collider project are based on the performance of niobium superconducting rf cavities for efficient particle acceleration. A remarkable increase of the rf accelerating field is usually achieved by low-temperature annealing of the cavities (T 2 O 5 , NbO 2 and NbO, from the surface to the interface. It reduces progressively upon heating from Nb 2 O 5 to NbO 2 at low temperatures, and to NbO at 300 C. The Nb(110)/NbO(111) interface presents a Nishiyama-Wassermann epitaxial orientation relationship. The depth-distribution of interstitial oxygen has been established indicating that most of the oxygen is located in the direct vicinity of the oxide/niobium interface. No evidence of oxygen depletion below the oxide layer has been observed for the low temperature thermal treatments and surface preparations investigated in this study. (orig.)

Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

International Nuclear Information System (INIS)

Sasani, Alireza; Baktash, Ardeshir; Mirabbaszadeh, Kavoos; Khoshnevisan, Bahram

2016-01-01

Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO_2 anatase surface (101) is studied. • Effect of Mg defect to the TiO_2 anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO_2 anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO_2 anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO_2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J_S_C of the surface while slightly decreasing V_O_C compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

The effect of niobium morphology on the fracture behavior of MoSi2/Nb composites

International Nuclear Information System (INIS)

Alman, D.E.; Stoloff

1995-01-01

The morphology of the niobium reinforcement added to MoSi 2 affected the fracture behavior (and hence toughness) of MoSi 2 /20 vol pct Nb composites. The addition of discontinuous random niobium in the form of particles or short fibers deflected cracks that propagated through the MoSi 2 matrix. However, this did not result in any improvements in toughness, as matrix cracks preferentially propagated through the Nb/MoSi 2 interphase region. The addition of aligned niobium fibers, oriented perpendicular to the direction of matrix crack propagation, directly participated in the fracture of the composite. Depending on the diameter of Nb embedded in the MoSi 2 matrix, these fibers either fractured in a brittle manner or ruptured in a ductile manner. Small (400-μm) diameter continuously aligned Nb fibers fractured by brittle cleavage during testing. Therefore, the addition of these fibers was not as effective in improving the toughness of MoSi 2 as the addition of larger (800-μm) diameter continuously aligned Nb fibers, which ruptured in a ductile manner. It was observed that the larger diameter fibers had separated from the matrix through the propagation of cracks in the reaction zone adjacent to the fibers and that these cracks formed prior to yielding of these fibers. In contrast, the smaller diameter fibers remained well bonded to the matrix and, thus, were constrained by the MoSi 2 matrix from yielding. This resulted in brittle fracture behavior of the Nb fiber. There appeared to be an effect of aspect ratio on the fracture of the ductile embedded fibers

Diatomic substitutionals in superconducting Nb{sub (1-x)}B{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Farrell, H.H. [Idaho National Laboratory, Materials Science Department, 2525 N. Freemont Ave., MS-2211, P.O. Box 1625, Idaho Falls, ID 83415-2211 (United States)]. E-mail: Helen.Farrell@inl.gov; LaViolette, Randall A. [Idaho National Laboratory, Materials Science Department, 2525 N. Freemont Ave., MS-2211, P.O. Box 1625, Idaho Falls, ID 83415-2211 (United States); Lillo, T.M. [Idaho National Laboratory, Materials Science Department, 2525 N. Freemont Ave., MS-2211, P.O. Box 1625, Idaho Falls, ID 83415-2211 (United States)

2006-11-01

Using first-principles, density functional theory calculations, we have shown that the increase in superconducting critical temperature to above 9 K experimentally observed for B-rich, off-stoichiometry NbB{sub 2} material is associated with the formation of B-dimers on Nb sites rather than with the formation of Nb vacancies, as previously proposed. Our calculations show that certain of these B-dimer configurations have lower binding energies than do the vacancy structures. This result is pressure independent in the range between 0 and 10 GPa, and above. Further, the dimer-containing materials have a higher electronic density of states at the Fermi level than do the vacancy structures. Finally, the presence of B-dimers results in the splitting off of phonon normal modes. These last two factors are relevant to the improved superconducting properties.

Surface activation of MnNb{sub 2}O{sub 6} nanosheets by oxalic acid for enhanced photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Wu, Junshu; Wang, Jinshu, E-mail: wangjsh@bjut.edu.cn; Li, Hongyi; Li, Yongli; Du, Yucheng; Yang, Yilong; Jia, Xinjian

2017-05-01

Graphical abstract: Visible light driven photoreduction of Cr(VI) over MnNb{sub 2}O{sub 6} nanosheets is enhanced via oxalic acid surface complex to generate activation layer. - Highlights: • MnNb{sub 2}O{sub 6} nanosheets are crystallized by a surface capping route of sulfonate groups. • Oxalic acid on MnNb{sub 2}O{sub 6} nanosheets forms an excited surface complex hybrid layer. • Surface activation enhances visible-light induced reduction of Cr(VI) into Cr(III). - Abstract: MnNb{sub 2}O{sub 6} nanosheets (P-MNOs) is selectively crystallized by using surface capping ligand with functional sulfonate group (sodium dodecyl benzene sulphonate), which binds to the (131) surface of MnNb{sub 2}O{sub 6} inducing the morphology-controlled crystallization of MnNb{sub 2}O{sub 6} materials. Surface modification of photoactive P-MNOs with electron-rich oxalic acid ligands establishes an excited surface complex layer on phase-pure P-MNO as evidenced by spectroscopic analyses (FT-IR, UV–vis, Raman, PL, etc.), and thus more efficiently photocatalyzes the reduction of Cr(VI) into Cr(III) than solely P-MNOs or oxalic acid under visible light (λ > 420 nm) via a ligand-to-metal interfacial electron transfer pathway. However, the interaction between oxalic acid and MnNb{sub 2}O{sub 6} is highly dependent upon the morphology of solid MnNb{sub 2}O{sub 6} substrate due to the higher surface-area-to-volume ratio and higher surface activity of (131) planes in the sheet-like morphology. This study could assist the construction of stable niobate material systems to allow a versatile solid surface activation for establishing more energy efficient and robust catalysis process under visible light.

Double-hit lymphomas constitute a highly aggressive subgroup in diffuse large B-cell lymphomas in the era of rituximab.

Science.gov (United States)

Kobayashi, Tsutomu; Tsutsumi, Yasuhiko; Sakamoto, Natsumi; Nagoshi, Hisao; Yamamoto-Sugitani, Mio; Shimura, Yuji; Mizutani, Shinsuke; Matsumoto, Yosuke; Nishida, Kazuhiro; Horiike, Shigeo; Asano, Naoko; Nakamura, Shigeo; Kuroda, Junya; Taniwaki, Masafumi

2012-11-01

The incorporation of rituximab in immunochemotherapy has improved treatment outcomes for diffuse large B-cell lymphoma, but the prognosis for some diffuse large B-cell lymphomas remains dismal. Identification of adverse prognostic subgroups is essential for the choice of appropriate therapeutic strategy. We retrospectively investigated the impact of so-called 'double-hit' cytogenetic abnormalities, i.e. cytogenetic abnormalities involving c-MYC co-existing with other poor prognostic cytogenetic abnormalities involving BCL2, BCL6 or BACH2, on treatment outcomes for 93 consecutive diffuse large B-cell lymphoma patients. According to the revised international prognostic index, no patients were cytogenetically diagnosed with double-hit lymphomas in the 'very good' risk group or in the 'good' risk group, while 5 of 33 patients had double-hit lymphomas in the 'poor' risk group. All the double-hit lymphoma patients possessed both nodal and extranodal involvement. The overall complete response rate was 89.3%, overall survival 87.1% and progression-free survival 75.8% over 2 years (median observation period: 644 days). The complete response rates were 93.2% for the non-double-hit lymphoma patients and 40.0% for the double-hit lymphoma patients. Significantly longer progression-free survival and overall survival were observed for the 'very good' and the 'good' risk patients than for the 'poor' risk patients. Moreover, the progression-free survival of double-hit lymphoma was significantly shorter than that of the non-double-hit lymphoma 'poor' risk patients (P = 0.016). In addition, the overall survival of the double-hit lymphoma patients also tended to be shorter than that of the non-double-hit lymphoma 'poor' risk group. The diagnosis of double-hit lymphoma can help discriminate a subgroup of highly aggressive diffuse large B-cell lymphomas and indicate the need for the development of novel therapeutic strategies for double-hit lymphoma.

Surface energy effects on the stability of anatase and rutile nanocrystals: A predictive diagram for Nb_2O_5-doped-TiO_2

International Nuclear Information System (INIS)

Silva, Andre Luiz da; Hotza, Dachamir; Castro, Ricardo H.R.

2017-01-01

Highlights: • Anatase-rutile phase transition diagram was built for nano Nb_2O_5-doped-TiO_2. • Nb_2O_5-doping postpones the anatase-to-rutile transition. • The stability crossover for TiO_2 was 17.3 nm, for 2 mol% Nb_2O_5-doped-TiO_2 ∼30 nm. • The surface energy for Nb_2O_5-doped-TiO_2 decreases systematically with Nb concentration. - Abstract: Titanium dioxide nanoparticles are widely used for photocatalysis, and the relative fraction of titanium dioxide polymorph, i.e. anatase, rutile, or brookite, significantly affects the final performance. Even though conventional phase diagrams indicate a higher stability for the rutile polymorph, it is well established that nanosizes benefit the anatase phase due to its smaller surface energy. However, doping elements are expected to change this behavior, once changes in both surface and bulk energies may occur. Nb_2O_5 is commonly added to TiO_2 to allow property control. However, the effect of niobium on the relative stability of anatase and rutile phases is not well understood from the thermodynamic point of view. The objective of this work was to build a new predictive nanoscale phase diagram for Nb_2O_5-doped TiO_2. Water adsorption microcalorimetry and high temperature oxide melt solution were used to obtain the surface and bulk enthalpies. The phase diagram obtained shows the stable titania polymorph as a function of the composition and size.

Preparation and Characteristics of Ultrasonic Transducers for High Temperature Using PbNb2O6

Science.gov (United States)

Soejima, Junichiro; Sato, Kokichi; Nagata, Kunihiro

2000-05-01

The substance PZT(Pb(Zr, Ti)O3) is chiefly used for piezoceramic transducers in many ultrasonic flow meters. It is difficult to use PZT transducers for flow meters for automobile exhaust gas at high temperatures over 350°C. Lead niobate (PbNb2O6) has a high Curie temperature of 540°C and a low mechanical quality factor, and is the most suitable as the sensor element in flow meters for automobile exhaust gas. However, it is difficult to fabricate dense PbNb2O6 ceramics that have good piezoelectric properties. In this study, ceramics with high density and a high piezoelectric effect were fabricated by adding various elements such as Mn and Ca to PbNb2O6 and by examining the sintering process. A Langevin transducer with a resonance frequency of 80 kHz was made for measuring automobile exhaust gas flow using PbNb2O6 ceramics.

Solid Phase Equilibrium Relations in the CaO-SiO2-Nb2O5-La2O3 System at 1273 K

Science.gov (United States)

Qiu, Jiyu; Liu, Chengjun

2018-02-01

Silicate slag system with additions Nb and RE formed in the utilization of REE-Nb-Fe ore deposit resources in China has industrial uses as a metallurgical slag system. The lack of a phase diagram, theoretical, and thermodynamic information for the multi-component system restrict the comprehensive utilization process. In the current work, solid phase equilibrium relations in the CaO-SiO2-Nb2O5-La2O3 quaternary system at 1273 K (1000 °C) were investigated experimentally by the high-temperature equilibrium experiment followed by X-ray diffraction, scanning electron microscope, and energy dispersive spectrometer. Six spatial independent tetrahedron fields in the CaO-SiO2-Nb2O5-La2O3 system phase diagram were determined by the Gibbs Phase Rule. The current work combines the mass fraction of equilibrium phase and corresponding geometric relation. A determinant method was deduced to calculate the mass fraction of equilibrium phase in quaternary system according to the Mass Conservation Law, the Gibbs Phase Rule, the Lever's Rule, and the Cramer Law.

Study of magnetic defects in Nb{sub 2}VSbO{sub 10}

Energy Technology Data Exchange (ETDEWEB)

Typek, J., E-mail: typjan@zut.edu.pl [Institute of Physics, West Pomeranian University of Technology, Szczecin, Al. Piastow 48, 70-311 Szczecin (Poland); Cyran, A.; Zolnierkiewicz, G.; Bobrowska, M. [Institute of Physics, West Pomeranian University of Technology, Szczecin, Al. Piastow 48, 70-311 Szczecin (Poland); Filipek, E.; Piz, M. [Department of Inorganic and Analytical Chemistry, West Pomeranian University of Technology, Szczecin, Al. Piastow 42, 71-065 Szczecin (Poland)

2017-02-15

Magnetic properties of Nb{sub 2}VSbO{sub 10}, the compound formed in V–Sb–Nb oxide system, were investigated by dc magnetisation measurements using an MPMS-7 SQUID magnetometer and EPR conventional X–band Bruker E 500 spectrometer. Although the nominal valences of the constituting metal ions indicated a diamagnetic material, Nb{sub 2}VSbO{sub 10} displayed rich and interesting magnetic behaviour due to the existence of numerous defects related to oxygen vacancies. Isothermal magnetisation has revealed the presence of three spin subsystems – two different paramagnetic systems and antiferromagnetic spin clusters. EPR spectra showed the presence of three components, involving isolated and interacting V{sup 4+} ions as well as antiferromagnetic spin clusters. All these magnetic defects are the result of valence changes of metal ions due to charge compensation in the neighborhood of oxygen vacancies, most probably located on grains boundaries.

Nb/sub 2/Te/sub 2/O/sub 9/ and Ta/sub 2/Te/sub 2/O/sub 9/: Two new mixed oxides of Te(IV)

International Nuclear Information System (INIS)

Gaitan, M.; Jerez, A.; Pico, C.; Veiga, M.L.

1987-01-01

Nb/sub 2/Te/sub 2/O/sub 9/ and Ta/sub 2/Te/sub 2/O/sub 9/ were prepared by solid state reactions between amorphous TeO/sub 3/(s) and metallic pentoxides of Nb and Ta. A crystallographic analysis carried out by X-ray diffraction showed that these compounds are isostructural (space group: P2/sub 1//C. a = 6.883 A, b = 7.853 A, c = 14.591 A, β = 103.66 for Nb/sub 2/Te/sub 2/O/sub 9/ and a = 7.10 A, b = 7.48 A, c = 14.62 A, β = 102.9 for Ta/sub 2/Te/sub 2/O/sub 9/). The IR spectra and thermal decomposition processes of both mixed oxides were studied

Preparation of orthophosphate glasses in the MgO-CaO-SiO2-Nb2O5-P2O5 system.

Science.gov (United States)

Lee, Sungho; Ueda, Kyosuke; Narushima, Takayuki; Nakano, Takayoshi; Kasuga, Toshihiro

2017-01-01

Niobia/magnesia-containing orthophosphate invert glasses were successfully prepared in our earlier work. Orthophosphate groups in the glasses were cross-linked by tetrahedral niobia (NbO4) and magnesia. The aim of this work is to prepare calcium orthophosphate invert glasses containing magnesia and niobia, incorporating silica, and to evaluate their structures and releasing behaviors. The glasses were prepared by melt-quenching, and their structures and ion-releasing behaviors were evaluated. 31P solid-state nuclear magnetic resonance (NMR) and Raman spectroscopies showed the glasses consist of orthophosphate (PO4), orthosilicate (SiO4), and NbO4 tetrahedra. NbO4 and MgO in the glasses act as network formers. By incorporating SiO2 into the glasses, the chemical durability of the glasses was slightly improved. The glasses reheated at 800°C formed the orthophosphate crystalline phases, such as β-Ca3(PO4)2, Mg3(PO4)2 and Mg3Ca3(PO4)4 in the glasses. The chemical durability of the crystallized glasses was slightly improved. Orthosilicate groups and NbO4 in the glasses coordinated with each other to form Si-O-Nb bonds. The chemical durability of the glasses was slightly improved by addition of SiO2, since the field strength of Si is larger than that of Ca or Mg.

Lennert's Lymphoma

International Nuclear Information System (INIS)

Narayanrao, Suresh T.; Pillai, R.; Nada, Aymen; Hasan, Suhel

2005-01-01

Lymphoepithelioid cell lymphoma (Lennert's lymphoma) is a rare morphological variant of peripheral T-cell lymphoma characterized by the presence of numerous clusters of epithelioid histiocytes without formation of discrete granulomas and the intervening atypical lymphocytes. Lennert's lymphoma is often misinterpreted as granulomatous lymphadenitis or Hodgkin's disease. This report describes fine needle aspiration cytology and histological findings in a case of Lennert's lymphoma. (author)

Observation of superconductivity in BaNb2S5

Science.gov (United States)

Smith, M. G.; Neumeier, J. J.

2018-06-01

Bulk superconductivity is reported in BaNb2S5 at the transition temperature Tc = 0.85(1) K. The electrical resistivity ρ versus T is metallic with ρ(2 K) = 42.4 μΩ cm. The magnetic susceptibility is paramagnetic, with temperature-independent contributions due to diamagnetism, Pauli paramagnetism, and Van Vleck paramagnetism; a Curie-Weiss contribution appears to be impurity related. Hall effect measurements show that the majority charge carriers are electrons with charge-carrier concentration n(3 K) = 2.40(2) × 1021 cm-3. Specific heat measurements reveal an electronic specific heat coefficient γ = 11.2(1) mJ/mol K2, a Debye temperature ΘD = 126.4(8) K, and an energy gap associated with the superconducting state of Eg = 0.184(4) meV. Measurements of ρ(T) in magnetic field provide the upper critical magnetic field of about 3055(74) Oe as T → 0 K, which was used to estimate the coherence length ξ = 6.21(15) nm. The results allow classification of BaNb2S5 as a Type II, BCS superconductor in the dirty limit.

Prognostic significance of CD95, P53, and BCL2 expression in extranodal non-Hodgkin's lymphoma

OpenAIRE

Chatzitolios , Anastasios; Venizelos , Ioannis; Tripsiannis , Gregory; Anastassopoulos , George; Papadopoulos , Nikolaos

2010-01-01

Abstract Apoptosis-related proteins play an important role in lymphoma cell death during chemotherapy. In our study, we investigated the prognostic significance of CD95, BCL2, and P53 expression in extranodal non-Hodgkin?s lymphoma (NHL). We examined 71 patients with extranodal NHL [45 diffuse large B-cell lymphomas (DLBCLs) and 26 mucosa-associated lymphoid tissue lymphomas (MALTLs)], 35 male and 36 female, with a median age of 65.8 years. The most common site of origin was the st...

Vertically aligned nitrogen doped (Sn,Nb)O_2 nanotubes – Robust photoanodes for hydrogen generation by photoelectrochemical water splitting

International Nuclear Information System (INIS)

Patel, Prasad Prakash; Hanumantha, Prashanth Jampani; Velikokhatnyi, Oleg I.; Datta, Moni Kanchan; Gattu, Bharat; Poston, James A.; Manivannan, Ayyakkannu; Kumta, Prashant N.

2016-01-01

Graphical abstract: - Highlights: • Nb and N co-doping provides excellent optoelectronic properties for SnO_2 NTs. • The optoelectronic properties of doped SnO_2 are studied by first principles study. • (Sn_0_._9_5Nb_0_._0_5)O_2:N-600 NTs exhibits superior ABPE (4.1%) to date. • Excellent photoelectrochemical stability of (Sn_0_._9_5Nb_0_._0_5)O_2:N-600 NTs. - Abstract: Hydrogen generation from photoelectrochemical (PEC) water splitting is on the forefront of clean energy generation landscape. The efficiency of PEC system is dependent on the engineering of semiconductors with tailored narrow band gap coupled with superior photoelectrochemical activity and desired stability vital for the commercialization of PEC water splitting cells. We report herein the study of vertically aligned Nb and N doped SnO_2 nanotubes (NTs), i.e., (Sn_0_._9_5Nb_0_._0_5)O_2:N NTs for PEC water splitting. (Sn_0_._9_5Nb_0_._0_5)O_2 NTs was selected for co-doping with nitrogen by systematic analysis of applied bias photon-to-current efficiency of various Nb doped SnO_2 (x = 0–0.1) compositions. Consequently, excellent photoelectrochemical stability and the highest efficiency of 4.1% is obtained for (Sn_0_._9_5Nb_0_._0_5)O_2:N-600 NTs never observed for other known TiO_2, ZnO, and Fe_2O_3 systems to date. Additionally, theoretical first principles study provides understanding of Nb and N co-doping on the electronic structure and band gap of SnO_2 semiconductor, further corroborating results of the experimental study.

Caging Nb2 O5 Nanowires in PECVD-Derived Graphene Capsules toward Bendable Sodium-Ion Hybrid Supercapacitors.

Science.gov (United States)

Wang, Xiangguo; Li, Qiucheng; Zhang, Li; Hu, Zhongli; Yu, Lianghao; Jiang, Tao; Lu, Chen; Yan, Chenglin; Sun, Jingyu; Liu, Zhongfan

2018-05-14

Sodium-ion hybrid supercapacitors (Na-HSCs) by virtue of synergizing the merits of batteries and supercapacitors have attracted considerable attention for high-energy and high-power energy-storage applications. Orthorhombic Nb 2 O 5 (T-Nb 2 O 5 ) has recently been recognized as a promising anode material for Na-HSCs due to its typical pseudocapacitive feature, but it suffers from intrinsically low electrical conductivity. Reasonably high electrochemical performance of T-Nb 2 O 5 -based electrodes could merely be gained to date when sufficient carbon content was introduced. In addition, flexible Na-HSC devices have scarcely been demonstrated by far. Herein, an in situ encapsulation strategy is devised to directly grow ultrathin graphene shells over T-Nb 2 O 5 nanowires (denoted as Gr-Nb 2 O 5 composites) by plasma-enhanced chemical vapor deposition, targeting a highly conductive anode material for Na-HSCs. The few-layered graphene capsules with ample topological defects would enable facile electron and Na + ion transport, guaranteeing rapid pseudocapacitive processes at the Nb 2 O 5 /electrolyte interface. The Na-HSC full-cell comprising a Gr-Nb 2 O 5 anode and an activated carbon cathode delivers high energy/power densities (112.9 Wh kg -1 /80.1 W kg -1 and 62.2 Wh kg -1 /5330 W kg -1 ), outperforming those of recently reported Na-HSC counterparts. Proof-of-concept Na-HSC devices with favorable mechanical robustness manifest stable electrochemical performances under different bending conditions and after various bending-release cycles. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

TET2 mutations in B cells of patients affected by angioimmunoblastic T-cell lymphoma.

Science.gov (United States)

Schwartz, Friederike H; Cai, Qian; Fellmann, Eva; Hartmann, Sylvia; Mäyränpää, Mikko I; Karjalainen-Lindsberg, Marja-Liisa; Sundström, Christer; Scholtysik, René; Hansmann, Martin-Leo; Küppers, Ralf

2017-06-01

Angioimmunoblastic T-cell lymphomas (AITLs) frequently carry mutations in the TET2 and IDH2 genes. TET2 mutations represent early genetic lesions as they had already been detected in haematopoietic precursor cells of AITL patients. We show by analysis of whole-tissue sections and microdissected PD1 + cells that the frequency of TET2-mutated AITL is presumably even higher than reported (12/13 cases in our collection; 92%). In two-thirds of informative AITLs (6/9), a fraction of B cells was also TET2-mutated. Investigation of four AITLs by TET2 and IGHV gene sequencing of single microdissected B cells showed that between 10% and 60% of polyclonal B cells in AITL lymph nodes harboured the identical TET2 mutations of the respective T-cell lymphoma clone. Thus, TET2-mutated haematopoietic precursor cells in AITL patients not only give rise to the T-cell lymphoma but also generate a large population of mutated mature B cells. Future studies will show whether this is a reason why AITL patients frequently also develop B-cell lymphomas. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Phase formation of V2O5.xNb2O5 compounds via gels and freeze-dried precursors

International Nuclear Information System (INIS)

Langbein, Hubert; Mayer-Uhma, Tobias

2009-01-01

An X-ray powder diffraction study of the phase formation in the system V 2 O 5 /Nb 2 O 5 is performed. Freeze-dried ammonium vanadate and ammonium oxalato niobate, alkoxide-derived xerogels and a mixture of active oxides are used as precursors to compare the resulting phase composition. Thermal decomposition of the freeze-dried precursor is monitored with DTA/TG and mass spectrometry. In the quasi-binary system V 2 O 5 -Nb 2 O 5 metastable VNbO 5 , V 4 Nb 18 O 55 , VNb 9 O 25 and solid solutions of V 2 O 5 in TT-Nb 2 O 5 as also thermodynamically stable VNb 9 O 25 exist. The thermal decomposition of freeze-dried vanadate-oxalatoniobate solution allows the synthesis of all these phases in a relative simple manner. Structural relationships between an intermediate phase and the product, or, in the case of solid-state reactions, between one of the starting oxide and the product, favour the desired reaction. Therefore, the structure of a former phase influences or directs the structure of the product similar to a topotactic reaction

NbN-AlN-NbN Josephson junctions on different substrates

Energy Technology Data Exchange (ETDEWEB)

Merker, Michael; Bohn, Christian; Voellinger, Marvin; Ilin, Konstantin; Siegel, Michael [KIT, Karlsruhe (Germany)

2016-07-01

Josephson junction technology is important for the realization of high quality cryogenic devices such as SQUIDs, RSFQ or SIS-mixers. The material system based on NbN/AlN/NbN tri-layer has gained a lot of interest, because it offers higher gap voltages and critical current densities compared to the well-established Nb/Al-AlOx/Nb technology. However, the realization of high quality Josephson junctions is more challenging. We developed a technology of Josephson junctions on a variety of substrates such as Silicon, Sapphire and Magnesium oxide and compared the quality parameters of these junctions at 4.2 K. The gap voltages achieved a range from 4 mV (for the junctions on Si) to 5.8 mV (in case of MgO substrates) which is considerably higher than those obtained from Nb based Josephson junctions. Another key parameter is the ratio of the subgap resistance to the normal state resistance. This so-called subgap ratio corresponds to the losses in a Josephson junction which have to be minimized. So far, subgap ratios of 26 have been achieved. Further careful optimization of the deposition conditions is required to maximize this ratio, The details of the optimization of technology and of characterization of NbN/AlN/NbN junctions will be presented and discussed.

A structural, magnetic, and Mössbauer study of the Dy{sub 2}Fe{sub 17−x}Nb{sub x} solid solutions

Energy Technology Data Exchange (ETDEWEB)

Rai, B.K. [Department of Physics, The University of Memphis, Memphis, TN 38152 (United States); Syed Ali, K.S. [Department of Science, Estill High school, Estill, SC 29918 (United States); Mishra, S.R., E-mail: srmishra@memphis.edu [Department of Physics, The University of Memphis, Memphis, TN 38152 (United States); Khanra, S.; Ghosh, K. [Department of Physics, Astronomy, and Materials Science, The Missouri State University, Springfield, MO 65897 (United States)

2014-03-15

The single-phase intermetallic compounds of refractory metal Nb doped Dy{sub 2}Fe{sub 17−x}Nb{sub x} were prepared by arc melting. The substitution of Nb in the Dy{sub 2}Fe{sub 17} compound was found to have an important effect on their structure and magnetic properties. The Rietveld analysis of X-ray diffraction data shows that Dy{sub 2}Fe{sub 17−x}Nb{sub x} (x=0–1.5) solid solutions crystallize with the Th{sub 2}Ni{sub 17} structure. The lattice parameters obtained from Rietveld refinement show that the unit cell volume of Dy{sub 2}Fe{sub 17−x}Nb{sub x} increases linearly with increasing Nb concentration up to x=1. The solubility of Nb was found to be limited to x∼1. The substitutional Nb atoms occupied all four sites in the order 12j>12k>6g>4f of a Th{sub 2}Ni{sub 17} structure. The Curie temperature (T{sub c}) was found to be Nb content dependent. The T{sub c} first increased and then decreased with increasing Nb content x, attaining a maximum value of 460 K at around x=1, which is 78 K higher than that of Dy{sub 2}Fe{sub 17}. The saturation magnetization decreased linearly with increasing Nb content from 69 emu/g for x=0 to 38 emu/g for x=1.5. {sup 57}Fe Mössbauer spectra show the presence of DyFe{sub 3} and NbFe{sub 2} phases at a higher Nb content x≥1. The hyperfine field values of 4f site first increased up to x=1 and then decreased at higher Nb content. - Highlights: • Nb is used to suppress the free alpha iron in 2:17 intermediates. At higher concentration x>1, Nb forms paramagnetic phase with alpha iron, NbFe{sub 2}. • The low level of Nb doping (x<1) in Dy{sub 2}Fe{sub 17−x}Nb{sub x} brings in ∼21% increase in the Curie temperature. • In Al, Si or Ga doped 2:17 intermatallics, similar improvement is observed in T{sub c} at a much higher doping concentration at the cost of reduction in net magnetization. • The maximum Curie temperature, 460 K, is observed for x∼1 Nb doping.

Nanostructured rare earth doped Nb{sub 2}O{sub 5}: Structural, optical properties and their correlation with photonic applications

Energy Technology Data Exchange (ETDEWEB)

Pereira, Rafael Ramiro; Aquino, Felipe Thomaz [Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP CEP 14040-901 (Brazil); Ferrier, Alban [PSL Research University, Chimie ParisTech-CNRS, Institut de Recherche de Chimie Paris, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Goldner, Philippe [PSL Research University, Chimie ParisTech-CNRS, Institut de Recherche de Chimie Paris, 75005 Paris (France); Gonçalves, Rogéria R., E-mail: rrgoncalves@ffclrp.usp.br [Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP CEP 14040-901 (Brazil)

2016-02-15

In the present work, we report on a systematic study on structural and spectroscopic properties Eu{sup 3+} and Er{sup 3+}-doped Nb{sub 2}O{sub 5} prepared by sol–gel method. The Eu{sup 3+} ions were used as structural probe to determine the symmetry sites occupied by lanthanide ions. The Eu{sup 3+}-doped Nb{sub 2}O{sub 5} nanocrystalline powders were annealed at different temperatures to verify how the different Nb{sub 2}O{sub 5} crystalline phases affect the structure and the luminescence properties. Er{sup 3+}-doped Nb{sub 2}O{sub 5} was prepared showing an intense NIR luminescence, and, visible luminescence on the green and red, deriving from upconversion process. The synthetized materials can find widespread applicability in photonics as red luminophor for white LED (with tricolor), optical amplifiers and upconverter materials. - Highlights: • Vis and NIR emission from nanostructured lanthanide doped Nb{sub 2}O{sub 5}. • Eu{sup 3+}-doped Nb{sub 2}O{sub 5} as Red luminophor. • Multicolor tunability of intense upconversion emission from lanthanide doped Nb{sub 2}O{sub 5}. • Potential application as biological markers. • Broad band NIR emission.

Involvement of p53 and Bcl-2 in sensory cell degeneration in aging rat cochleae.

Science.gov (United States)

Xu, Yang; Yang, Wei Ping; Hu, Bo Hua; Yang, Shiming; Henderson, Donald

2017-06-01

p53 and Bcl-2 (B-cell lymphoma 2) are involved in the process of sensory cell degeneration in aging cochleae. To determine molecular players in age-related hair cell degeneration, this study examined the changes in p53 and Bcl-2 expression at different stages of apoptotic and necrotic death of hair cells in aging rat cochleae. Young (3-4 months) and aging (23-24 months) Fisher 344/NHsd rats were used. The thresholds of the auditory brainstem response (ABR) were measured to determine the auditory function. Immunolabeling was performed to determine the expression of p53 and Bcl-2 proteins in the sensory epithelium. Propidium iodide staining was performed to determine the morphologic changes in hair cell nuclei. Aging rats exhibited a significant elevation in ABR thresholds at all tested frequencies (p aging hair cells showing the early signs of apoptotic changes in their nuclei. The Bcl-2 expression increase was also observed in hair cells displaying early signs of necrosis. As the hair cell degenerative process advanced, p53 and Bcl-2 immunoreactivity became reduced or absent. In the areas where no detectable nuclear staining was present, p53 and Bcl-2 immunoreactivity was absent.

Electrical and magnetic properties of Nb₂O_5-γ crystallographic shear structures

DEFF Research Database (Denmark)

Cava, R.J.; Batlogg, B.; Krajewski, J.J.

1991-01-01

The reduced niobium oxides Nb25O62, Nb47O116, Nb22O54, and Nb12O29 have been prepared in pure polycrystalline form by a niobium-metal gettering technique. They are related to the high niobia parent structure through the action of cystallographic shear to accommodate oxygen deficiency in Nb2O5-del...

Malignant lymphoma in african lions (panthera leo).

Science.gov (United States)

Harrison, T M; McKnight, C A; Sikarskie, J G; Kitchell, B E; Garner, M M; Raymond, J T; Fitzgerald, S D; Valli, V E; Agnew, D; Kiupel, M

2010-09-01

Malignant lymphoma has become an increasingly recognized problem in African lions (Panthera leo). Eleven African lions (9 male and 2 female) with clinical signs and gross and microscopic lesions of malignant lymphoma were evaluated in this study. All animals were older adults, ranging in age from 14 to 19 years. Immunohistochemically, 10 of the 11 lions had T-cell lymphomas (CD3(+), CD79a(-)), and 1 lion was diagnosed with a B-cell lymphoma (CD3(-), CD79a(+)). The spleen appeared to be the primary site of neoplastic growth in all T-cell lymphomas, with involvement of the liver (6/11) and regional lymph nodes (5/11) also commonly observed. The B-cell lymphoma affected the peripheral lymph nodes, liver, and spleen. According to the current veterinary and human World Health Organization classification of hematopoietic neoplasms, T-cell lymphoma subtypes included peripheral T-cell lymphoma (4/11), precursor (acute) T-cell lymphoblastic lymphoma/leukemia (2/11), chronic T-cell lymphocytic lymphoma/leukemia (3/11), and T-zone lymphoma (1/11). The single B-cell lymphoma subtype was consistent with diffuse large B-cell lymphoma. Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) testing by immunohistochemistry on sections of malignant lymphoma was negative for all 11 lions. One lion was seropositive for FeLV. In contrast to domestic and exotic cats, in which B-cell lymphomas are more common than T-cell lymphomas, African lions in this study had malignant lymphomas that were primarily of T-cell origin. Neither FeLV nor FIV, important causes of malignant lymphoma in domestic cats, seems to be significant in the pathogenesis of malignant lymphoma in African lions.

Control of the interfacial reactions in Nb-toughened MoSi2

International Nuclear Information System (INIS)

Shaw, L.; Abbaschian, R.

1993-01-01

Toughening of MoSi 2 for high-temperature applications can be achieved by incorporating ductile refractory-metal reinforcements, provided that a coating is applied to prevent interdiffusion and reaction between the matrix and the reinforcements. In the present study, three different coating techniques for applying a thin Al 2 O 3 film on Nb reinforcements as a diffusion barrier have been studied. The techniques consisted of (1) sol-gel coating; (2) physical vapor deposition (PVD); (3) hot dipping in molten Al, followed by anodizing Al to form Al 2 O 3 . The processing parameters for the techniques were evaluated and the effectiveness of each coating as a diffusion barrier was assessed. For the present MoSi 2 matrix which contains SiO 2 , PVD coatings provided the most effective diffusion barrier for processing MoSi 2 /Nb composites

Comparison of the costs of superconducting accelerator dipoles using NbTi, Nb3Sn and NbTiTa

International Nuclear Information System (INIS)

Hassenzahl, W.

1981-03-01

The present study, which is based on the assumption that future, high-energy accelerators will use superconductors, is a comparison of the costs of 5 to 12 Tesla NbTi, Nb 3 S/sub n/, and NbTiTa accelerator magnets operating at 4.2 K or 1.8 K. The object of this evaluation is not to determine the actual cost of future accelerators, rather, its purpose is to provide some rationale for research on the next generation of superconducting accelerator magnets. Thus, though the actual costs of accelerator magnets may be different from those given here, the comparisons are valid

CARDIAC LYMPHOMA IN DOG

Directory of Open Access Journals (Sweden)

G. D. Cruz

2016-11-01

Full Text Available Lymphoma is a lymphoid tumor that originates in hematopoietic organs such as lymph node, spleen or liver. In dogs, the overall prevalence of cardiac tumors was estimated to be only 0.19% based on the results of the survey of a large database, and lymphomas accounts for approximately 2% of all cardiac tumors. In general, the involvement of the myocardium is rarely described in canine lymphoma. Currently, there is no evidence of a viral association with primary cardiac lymphoma in dogs, but other types of immunosuppression may contribute to abnormal events, such as involvement primary cardiac. The aim of this study was to analyze a case of sudden death of a bitch, SRD, aged 10, who had the final diagnosis of cardiac lymphoma.

Collinear Order in Frustrated Quantum Antiferromagnet on Square Lattice (CuBr)LaNb2O7

Science.gov (United States)

Oba, Noriaki; Kageyama, Hiroshi; Kitano, Taro; Yasuda, Jun; Baba, Yoichi; Nishi, Masakazu; Hirota, Kazuma; Narumi, Yasuo; Hagiwara, Masayuki; Kindo, Koichi; Saito, Takashi; Ajiro, Yoshitami; Yoshimura, Kazuyoshi

2006-11-01

Magnetic susceptibility, heat capacity, high-field magnetization and neutron diffraction measurements have been performed on a two-dimensional S = 1/2 square-lattice system (CuBr)LaNb2O7, prepared by a topotactic ion-exchange reaction of a nonmagnetic double-layered perovskite RbLaNb2O7. (CuBr)LaNb2O7 exhibits a second-order magnetic transition at 32 K, in marked contrast to a spin-singlet nature for its Cl-based counterpart (CuCl)LaNb2O7, despite nearly identical structural parameters. The magnetic structure is a novel collinear antiferromagnetic (CAF) ordering characterized by a modulation vector q = (π, 0, π) with a reduced moment of 0.6μB. Mixed ferromagnetic nearest-neighbor (J1) and antiferromagnetic second-nearest-neighbor (J2) interactions are of comparable strength (J1/kB = -35.6 K and J2/kB = 41.3 K), placing the system in a more frustrated region of the CAF phase than ever reported.

A new type of one-dimensional compound: Structure of Nb4(Te2)4Te4I

International Nuclear Information System (INIS)

Deng Shuiquan; Zhuang Honghui; Lu Canzhong; Huang Jinshun; Huang Jingling

1993-01-01

The new infinite-chain niobium telluride iodide has been prepared by reaction of the elements at 893 K. Nb 4 (Te 2 ) 4 Te 4 I represents a new one-dimensional structure type. The structure consists of [Nb 4 (Te 2 ) 4 Te 4 I] ∞ chains which are formed by the four-nuclear butterfly cluster units 'Nb 4 (Te 2 ) 4 Te 4 ' with the I atoms bridging between different cluster units. (orig.)

Immunohistochemical Characterization of Canine Lymphomas

Directory of Open Access Journals (Sweden)

Roxana CORA

2017-11-01

Full Text Available Lymphomas occur by clonal expansion of lymphoid cells and have distinctive morphological and immunophenotypic features. Determination of canine lymphoma immunophenotype is useful for accurate prognosis and further therapy. In the suggested study, we performed an immunohistochemical evaluation of some cases with canine lymphoma diagnosed in the Department of Pathology (Faculty of Veterinary Medicine, Cluj-Napoca, Romania, in order to characterize them. The investigation included 39 dogs diagnosed with different anatomical forms of lymphoma, following necropsy analysis or assessment of biopsies. The diagnosis of lymphoma was confirmed by necropsy and histopathology (Hematoxylin-eosin stain examinations. The collected specimens were analyzed by immunohistochemistry technique (automatic method using the following antibodies: CD3, CD20, CD21 and CD79a. The analyzed neoplasms were characterized as follows: about 64.10% of cases were diagnosed as B-cell lymphomas, 33.34% of cases as T-cell lymphomas, whereas 2.56% of cases were null cell type lymphomas (neither B nor T. Most of multicentric (80%, mediastinal (60% and primary central nervous system lymphomas (100% had B immunophenotype, while the majority of cutaneous (80% and digestive (100% lymphomas had T immunophenotype. Immunohistochemical description of canine lymphomas can deliver some major details concerning their behavior and malignancy. Additionally, vital prognosis and efficacy of some therapeutic protocols are relying on the immunohistochemical features of canine lymphoma.

Relations between anisotropic defects, structural evolution, and van der Waals bonding in 2H-NbSe2

International Nuclear Information System (INIS)

Gavarri, J.R.; Mokrani, R.; Boulesteix, C.; Vacquier, G.

1988-01-01

Correlations between anisotropic defects and van der Waals interactions have been established for the layer compound 2H-NbSe 2 which is investigated by low temperature X-ray diffraction techniques. Thermal expansion coefficients and anisotropic Debye temperatures are determined. A diffraction profile analysis reveals the existence of lattice distortions independent of the temperature. They are due to layer defects. To interpret the structural evolution data, the thermal expansion functions, α a (T) and α c (T) are simulated in the low temperature range which yield the elastic constants and the Grueneisen parameters. Using bond energy models, the Van der Waals nature of interlayer Se-Se interactions is confirmed by a model of thermal expansion of bonds and connected with the C 13 component of the elastic tensor. Such interactions can explain the presence of some layer defects that can be 4H-NbSe 2 nuclei in the 2H host lattice. In addition, no strong change in the Grueneisen parameters is clearly shown to occur at the 35 K transition of 2H-NbSe 2 . (author)

Porous TiNb2O7 Nanospheres as ultra Long-life and High-power Anodes for Lithium-ion Batteries

International Nuclear Information System (INIS)

Cheng, Qiushi; Liang, Jianwen; Lin, Ning; Guo, Cong; Zhu, Yongchun; Qian, Yitai

2015-01-01

Graphical abstract: Due to the combinative merits of porosity and nanostructure, porous TiNb 2 O 7 nanospheres exhibit ultra long cyclic life and excellent rate performance for lithium ion batteries. - Highlights: • Porous TiNb 2 O 7 nanospheres have been fabricated with the assistance of block copolymer P123. • The as-prepared TiNb 2 O 7 anodes present a reversible capacity of 160 mA h/g after 10000 cycles at 5 C with a capacity loss of only 0.0033% per cycle. • The TiNb 2 O 7 anodes show good rate performance of 167 mA h/g at 50C. • The TiNb 2 O 7 materials maintain the morphology of nanospheres and the porous structure even after 10000 cycles. - Abstract: Porous TiNb 2 O 7 nanospheres comprised of nanoparticles have been synthesized with the assistance of block copolymer P123 (EO 20 PO 70 EO 20 ). Such porous TiNb 2 O 7 nanospheres, with diameter of 500 nm, exhibit a BET surface area of 23.4 m 2 /g and pore volume of 0.155 cm 3 /g. As the anodes for lithium-ion batteries, the TiNb 2 O 7 nanospheres present a reversible capacity of 160 mA h/g after 10000 cycles at 5 C with a capacity loss of only 0.0033% per cycle, and good rate performance of 167 mA h/g at 50 C. Furthermore, the TiNb 2 O 7 materials still maintain the morphology of nanospheres and the porous structure even after 10000 cycles

Magnetic structure driven ferroelectricity and large magnetoelectric coupling in antiferromagnet Co4Nb2O9

Science.gov (United States)

Srivastava, P.; Chaudhary, S.; Maurya, V.; Saha, J.; Kaushik, S. D.; Siruguri, V.; Patnaik, S.

2018-05-01

Synthesis and extensive structural, pyroelectric, magnetic, dielectric and magneto-electric characterizations are reported for polycrystalline Co4Nb2O9 towards unraveling the multiferroic ground state. Magnetic measurements confirm that Co4Nb2O9 becomes an anti-ferromagnet at around 28 K. Associated with the magnetic phase transition, a sharp peak in pyroelectric current indicates the appearance of strong magneto-electric coupling below Neel temperature (TN) along with large coupling constant upto 17.8 μC/m2T. Using temperature oscillation technique, we establish Co4Nb2O9 to be a genuine multiferroic with spontaneous electric polarization in the anti-ferromagnetic state in the absence of magnetic field poling. This is in agreement with our low temperature neutron diffraction studies that show the magnetic structure of Co4Nb2O9 to be that of a non-collinear anti-ferromagnet with ferroelectric ground state.

Immunohistochemical detection of cdc2 is useful in predicting survival in patients with mantle cell lymphoma.

Science.gov (United States)

Hui, David; Reiman, Tony; Hanson, John; Linford, Rick; Wong, Winson; Belch, Andrew; Lai, Raymond

2005-09-01

Recent cDNA microarray studies have reported the prognostic value of several genes in mantle cell lymphoma patients. We aimed to validate the prognostic significance of three of these genes: alpha-tubulin, cdc2, and CENP-F. The protein expression of alpha-tubulin, cdc2, and CENP-F was assessed using immunohistochemistry. Their immunoreactivity in 48 formalin-fixed/paraffin-embedded mantle cell lymphoma tumors was determined by estimating the percentage of positive cells. These results were correlated with the expression of proliferation marker Ki67 and survival. Of these 48 mantle cell lymphoma patients, 41 were men and seven were women. The median age at time of diagnosis was 64.5 years, and the overall median survival was 40 months. In benign lymph nodes, the expression of cdc2 and alpha-tubulin was restricted to the germinal centers; mantle zones were negative. Expression of CENP-F was more uniformly distributed. In mantle cell lymphoma, Ki67 significantly correlated with all three markers (P50%) and cdc2 (>25%) significantly correlated with shorter survival (Por=2 correlated with worse clinical outcome, and high clinical stage (ie 4 vs 2 and Ki67 was independent of international prognostic index and clinical stage. We have validated the prognostic value of cdc2, and confirmed that of Ki67, in a cohort of mantle cell lymphoma patients. Immunohistochemical detection of cdc2 and Ki67 may be a useful and simple method in evaluating the prognosis of mantle cell lymphoma patients.

Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

Energy Technology Data Exchange (ETDEWEB)

Sasani, Alireza [Department of Science, Karaj Islamic Azad University, Karaj, Alborz, P.O. Box 31485-313 (Iran, Islamic Republic of); Baktash, Ardeshir [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Mirabbaszadeh, Kavoos, E-mail: mirabbas@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, P. O. Box 15875-4413 (Iran, Islamic Republic of); Khoshnevisan, Bahram [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of)

2016-10-30

Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO{sub 2} anatase surface (101) is studied. • Effect of Mg defect to the TiO{sub 2} anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO{sub 2} anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO{sub 2} anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO{sub 2} surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J{sub SC} of the surface while slightly decreasing V{sub OC} compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

Mechanism of generation of large (Ti,Nb,V)(C,N)-type precipitates in H13 + Nb tool steel

Science.gov (United States)

Xie, You; Cheng, Guo-guang; Chen, Lie; Zhang, Yan-dong; Yan, Qing-zhong

2016-11-01

The characteristics and generation mechanism of (Ti,Nb,V)(C,N) precipitates larger than 2 μm in Nb-containing H13 bar steel were studied. The results show that two types of (Ti,Nb,V)(C,N) phases exist—a Ti-V-rich one and an Nb-rich one—in the form of single or complex precipitates. The sizes of the single Ti-V-rich (Ti,Nb,V)(C,N) precipitates are mostly within 5 to 10 μm, whereas the sizes of the single Nb-rich precipitates are mostly 2-5 μm. The complex precipitates are larger and contain an inner Ti-V-rich layer and an outer Nb-rich layer. The compositional distribution of (Ti,Nb,V)(C,N) is concentrated. The average composition of the single Ti-V-rich phase is (Ti0.511V0.356Nb0.133)(C x N y ), whereas that for the single Nb-rich phase is (Ti0.061V0.263Nb0.676)(C x N y ). The calculation results based on the Scheil-Gulliver model in the Thermo-Calc software combining with the thermal stability experiments show that the large phases precipitate during the solidification process. With the development of solidification, the Ti-V-rich phase precipitates first and becomes homogeneous during the subsequent temperature reduction and heat treatment processes. The Nb-rich phase appears later.

Mesostructured niobium-doped titanium oxide-carbon (Nb-TiO2-C) composite as an anode for high-performance lithium-ion batteries

Science.gov (United States)

Hwang, Keebum; Sohn, Hiesang; Yoon, Songhun

2018-02-01

Mesostructured niobium (Nb)-doped TiO2-carbon (Nb-TiO2-C) composites are synthesized by a hydrothermal process for application as anode materials in Li-ion batteries. The composites have a hierarchical porous structure with the Nb-TiO2 nanoparticles homogenously distributed throughout the porous carbon matrix. The Nb content is controlled (0-10 wt%) to investigate its effect on the physico-chemical properties and electrochemical performance of the composite. While the crystalline/surface structure varied with the addition of Nb (d-spacing of TiO2: 0.34-0.36 nm), the morphology of the composite remained unaffected. The electrochemical performance (cycle stability and rate capability) of the Nb-TiO2-C composite anode with 1 wt% Nb doping improved significantly. First, a full cut-off potential (0-2.5 V vs. Li/Li+) of Nb-doped composite anode (1 wt%) provides a higher energy utilization than that of the un-doped TiO2-C anode. Second, Nb-TiO2-C composite anode (1 wt%) exhibits an excellent long-term cycle stability (100% capacity retention, 297 mAh/g at 0.5 C after 100 cycles and 221 mAh/g at 2 C after 500 cycles) and improved rate-capability (192 mAh/g at 5 C), respectively (1 C: 150 mA/g). The superior electrochemical performance of Nb-TiO2-C (1 wt%) could be attributed to the synergistic effect of improved electronic conductivity induced by optimal Nb doping (1 wt%) and lithium-ion penetration (high diffusion kinetics) through unique pore structures.

Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2H-NbSe2.

Science.gov (United States)

Arguello, C J; Rosenthal, E P; Andrade, E F; Jin, W; Yeh, P C; Zaki, N; Jia, S; Cava, R J; Fernandes, R M; Millis, A J; Valla, T; Osgood, R M; Pasupathy, A N

2015-01-23

We show that a small number of intentionally introduced defects can be used as a spectroscopic tool to amplify quasiparticle interference in 2H-NbSe2 that we measure by scanning tunneling spectroscopic imaging. We show, from the momentum and energy dependence of the quasiparticle interference, that Fermi surface nesting is inconsequential to charge density wave formation in 2H-NbSe2. We demonstrate that, by combining quasiparticle interference data with additional knowledge of the quasiparticle band structure from angle resolved photoemission measurements, one can extract the wave vector and energy dependence of the important electronic scattering processes thereby obtaining direct information both about the fermiology and the interactions. In 2H-NbSe2, we use this combination to confirm that the important near-Fermi-surface electronic physics is dominated by the coupling of the quasiparticles to soft mode phonons at a wave vector different from the charge density wave ordering wave vector.

Synthesis and characterization of Al2O3NbC composite and the effect of Y2O3 addition on its sintering

International Nuclear Information System (INIS)

Pasotti, Rosa Maria da Rocha

1999-01-01

Alumina composites containing ceramic particles have been intensively studied because they show improved mechanical properties and some advantages over fibres and whiskers based composites mainly for processing. The embedment of NbC particles in an Al 2 O 3 matrix has been investigated in this work. Composite materials were obtained by the conventional ceramic processing with compositions Al 2 O 3 -x NbC where x=10, 20, and 40 weight %. Materials were sintered in argon at 1650 deg C/30 min, and at 1750 deg C/15min using a graphite resistance furnace. Three sets of samples were processed: containing NbC powder as received; containing NbC powder milled for 30 h; and containing 3 weight % of Y 2 O 3 added to the Al 2 O 3 matrix. After sintering samples were analysed to evaluate the densification grade. Phases were determined by X-ray diffraction, and samples were analysed by optical microscopy, scanning electron microscopy and transmission electron microscopy to observe the microstructure features. Hardness and fracture toughness at room temperature were also determined by the indentation method, and the sintering kinetic was evaluated by dilatometry. The present work shows that Al 2 O 3 -NbC composite can be produced by using pressureless sintering, leading to materials with densities higher than 95% of the theoretical density for all composites containing NbC and sintered at 1750 deg C. The same result can be obtained for composites containing 10 and 20 weight % of NbC, and sintered at temperatures as low as 1650 deg C. Higher concentration of NbC in the Al 2 O 3 matrix promotes an improvement of fracture toughness. Samples with 40-wt % of NbC show K IC equals to 4.5 MPa.m 1/2 . This value is compared to the ones previously determined for Al 2 O 3 - TiC composites, available commercially and used in ceramic cutting-tools. (author)

Peak effect studies in single crystals CeRu2 and 2H-NbS2

Indian Academy of Sciences (India)

vibrating sample magnetometer (VSM) (Oxford Instruments, UK) on single crystal sam- ples of CeRu2 and 2H-NbS2. All the measurements were carried out by cooling the sample in zero field (ZFC mode) and then by applying the magnetic field. The measurements were carried out with the magnetic field parallel to the cube ...

ESMO Consensus conferences : guidelines on malignant lymphoma. part 2: marginal zone lymphoma, mantle cell lymphoma, peripheral T-cell lymphoma

NARCIS (Netherlands)

Dreyling, M.; Thieblemont, C.; Gallamini, A.; Arcaini, L.; Campo, E.; Hermine, O.; Kluin-Nelemans, J. C.; Ladetto, M.; Le Gouill, S.; Iannitto, E.; Pileri, S.; Rodriguez, J.; Schmitz, N.; Wotherspoon, A.; Zinzani, P.; Zucca, E.

To complement the existing treatment guidelines for all tumour types, ESMO organizes consensus conferences to focus on specific issues in each type of tumour. In this setting, a consensus conference on the management of lymphoma was held on 18 June 2011 in Lugano, next to the 11th International

A phase II study of the oral JAK1/JAK2 inhibitor ruxolitinib in advanced relapsed/refractory Hodgkin lymphoma

NARCIS (Netherlands)

E. van den Neste (Eric); J.-L. André (Jean-Luc); Gastinne, T. (Thomas); A. Stamatoullas (Aspasia); C. Haioun (Corinne); Belhabri, A. (Amine); O. Reman (Oumédaly); O. Casasnovas (O.); H. Ghesquieres; G.E.G. Verhoef (Gregor); Claessen, M.-J. (Marie-José); H.A. Poirel (Hélène A); M.-C. Copin; Dubois, R. (Romain); P. Vandenberghe (Peter); Stoian, I.-A. (Ioanna-Andrea); Cottereau, A.S. (Anne S.); Bailly, S. (Sarah); L. Knoops (Laurent); F. Morschhauser (Frank)

2018-01-01

textabstractJAK2 constitutive activation/overexpression is common in classical Hodgkin lymphoma, and several cytokines stimulate Hodgkin lymphoma cells by recognizing JAK1-/JAK2-bound receptors. JAK blockade may thus be therapeutically beneficial in Hodgkin lymphoma. In this phase II study we

Carbides precipitated from the melt in a Zr-2.5 Nb alloy

International Nuclear Information System (INIS)

Piotrkowski, R.; Garcia, E.A.; Vigna, G.L.; Bermudez, S.E.

1993-01-01

An experimental method is presented which leads to the formation of carbides similar in size (3 to 8 microns) and composition to those observed in some pressure tubes of CANDU type reactors. The method is based on melting the Zr-2.5 Nb alloy in a graphite crucible, where isothermal C diffusion in the Zr-Nb melt took place. It can be inferred that the carbides observed in pressure tubes could be originated in high temperature stages of the manufacture process. Otherwise, they could have been incorporated in the Zr sponge. As a result of the diffusion couple Liquid Zr-2.5 Nb/Solid Graphite, a carbide layer, up to 100μm thick, grew attached to the crucible wall, together with carbide particles whose size was in the some microns range. The smallest particles were arranged in rows determined by the prior β phase grains. The main carbide phase detected was the cubic MC 1-x ; the hexagonal M 2 C was also detected; M for metal. (Author)

Colossal Dielectric Behavior of Ga+Nb Co-Doped Rutile TiO2.

Science.gov (United States)

Dong, Wen; Hu, Wanbiao; Berlie, Adam; Lau, Kenny; Chen, Hua; Withers, Ray L; Liu, Yun

2015-11-18

Stimulated by the excellent colossal permittivity (CP) behavior achieved in In+Nb co-doped rutile TiO2, in this work we investigate the CP behavior of Ga and Nb co-doped rutile TiO2, i.e., (Ga(0.5)Nb(0.5))(x)Ti(1-x)O2, where Ga(3+) is from the same group as In(3+) but with a much smaller ionic radius. Colossal permittivity of up to 10(4)-10(5) with an acceptably low dielectric loss (tan δ = 0.05-0.1) over broad frequency/temperature ranges is obtained at x = 0.5% after systematic synthesis optimizations. Systematic structural, defect, and dielectric characterizations suggest that multiple polarization mechanisms exist in this system: defect dipoles at low temperature (∼10-40 K), polaronlike electron hopping/transport at higher temperatures, and a surface barrier layer capacitor effect. Together these mechanisms contribute to the overall dielectric properties, especially apparent observed CP. We believe that this work provides comprehensive guidance for the design of new CP materials.

The effect of oxide microstructure on kinetic transition in out-of-pile steam corrosion test for Zircaloy-2 and Nb-added Zircaloy-2

Energy Technology Data Exchange (ETDEWEB)

Nanikawa, Shuichi [Japan Nuclear Fuel Co. Ltd., Yokosuka, Kanagawa (Japan); Etoh, Yoshinori [Japan Nuclear Fuel Co. Ltd., Yokohama, Kanagawa (Japan)

2001-06-01

In order to study the mechanism of kinetic transition of corrosion rate for zirconium alloys, oxide films formed on Zircaloy-2 (Zry-2) and Nb-added Zircaloy-2 (0.5Nb/Zry-2) in steam at 673 K and 10.3 MPa were examined with TEM and SIMS. Kinetic transition occurred at almost the same oxide thicknesses for both Zry-2 and 0.5Nb/Zry-2, but the corrosion rate after the transitions were quite different for the two alloys. Zircaloy-2 showed cyclical oxidation, while the weight gain of 0.5Nb/Zry-2 increased linearly. The morphology and crystal structure were similar for the oxides of the two alloys and both the oxide films still mainly consisted of columnar grains even after the transition. Interface layers which mainly consisted of {alpha}-Zr crystallites were observed for both alloys and the oxygen content in the interface layers increased after the transition. The solute concentrations of Fe, Cr and Ni became higher, accompanying the increase of oxygen concentrations at columnar grain boundaries in the oxide films after the transition for 0.5Nb/Zry-2. It was thought that the properties of grain boundaries of the 0.5Nb/Zry-2 oxide films changed after the transition, and the increase in oxygen diffusivity at grain boundaries caused the linear increase in weight gain. (author)

Mantle Cell Lymphoma

Science.gov (United States)

... Non-Hodgkin Lymphoma Peripheral T-Cell Lymphoma Primary Central Nervous System Lymphoma T-Cell Lymphoma Transformed Mycosis Fungoides Waldenstrom Macroglobulinemia Young Adult Lymphoma Overview Treatment Options Relapsed/Refractory Long-term ...

Marginal Zone Lymphoma

Science.gov (United States)

... Non-Hodgkin Lymphoma Peripheral T-Cell Lymphoma Primary Central Nervous System Lymphoma T-Cell Lymphoma Transformed Mycosis Fungoides Waldenstrom Macroglobulinemia Young Adult Lymphoma Overview Treatment Options Relapsed/Refractory Long-term ...

Understanding cation ordering and oxygen vacancy site preference in Ba3CaNb2O9 from first-principles

Science.gov (United States)

Ding, Hepeng; Virkar, Anil; Liu, Feng

2014-03-01

We investigate the physical mechanism underlying the formation of the B-site cation ordering and the oxygen vacancy site selection in Ba3CaNb2O9 using density functional theory calculations. We found that either cation site exchange or oxygen vacancy formation induces negligible lattice strain. This implies that the ionic radius plays an insignificant role in governing these two processes. Furthermore, the electrostatic interactions are found dominant in the ordering of mixed valence species on one or more sites, the ionic bond strength is identified as the dominant force in governing both the 1:2 B-site cation ordering along the direction and the oxygen vacancy site preference in Ba3CaNb2O9. Specifically, the cation ordering can be rationalized by the increased mixing bonding energy of the Ca-O-Nb bonds over the Ca-O-Ca and Nb-O-Nb bonds, i.e., 1/2(Ca-O-Ca + Nb-O-Nb) Grant Number DE-SC0001061 as a flow through from the University of South Carolina.

Influence of Nb content on the structural and optical properties of anatase TiO{sub 2} polycrystalline thin film by e-beam technique

Energy Technology Data Exchange (ETDEWEB)

Shah, A., E-mail: attaullah77@yahoo.com; Mahmood, Arshad; Aziz, Uzma; Rashid, Rashad; Raza, Qaiser; Ali, Zahid

2016-09-01

In this paper, we report the structural and optical properties of Nb-doped TiO{sub 2} thin films deposited by e-beam evaporation technique. After post annealing in air at 500 °C for 1 h, the samples were characterized by various techniques such as X-ray diffraction (XRD), Raman spectroscopy, UV–Vis spectrophotometry and spectroscopic Ellipsometer. Both XRD and Raman analyses indicate that the films were crystallized into the polycrystalline anatase TiO{sub 2} structure. However it was observed that the crystallinity of the films decreases with the addition of Nb atoms and tends to become amorphous at 20% Nb content in TiO{sub 2} film. Moreover, no new phases such as Nb{sub 2}O{sub 5}, NbO{sub 2} or Nb metal were observed. The band gap energy was found to decrease with the increasing of Nb concentration which was verified by ellipsometric study. Ellipsomtric measurements also indicate that refractive index (n) of the films decreases while extinction coefficient (k) increases with the increasing of Nb content. All these analyses elucidate that the incorporation of Nb atom into TiO{sub 2} may tune the structural and optical properties of TiO{sub 2} thin films. - Highlights: • The addition of Nb into TiO{sub 2} film has strongly influenced its physical properties. • Anatase polycrystalline Nb:TiO{sub 2} films were grown up to 15% Nb content. • The film becomes an amorphous at 20% Nb doping. • Band gap energy of TiO{sub 2} film was decreased with increasing of Nb content in the film. • The Optical constants (n, k) of Nb:TiO{sub 2} film were varied as a function of Nb content.

The radiographic findings in diagnosis of pulmonary lymphoma

International Nuclear Information System (INIS)

Song Wei; Wang Li; Yan Hongzhen

2001-01-01

Objective: To study the radiographic findings in the diagnosis of pulmonary lymphoma and pseudo lymphoma. Methods: Eight patients with pulmonary lymphoma and 2 with pseudo lymphoma were examined by X-ray film, tomography, and CT. Results: Single or multiple nodules or masses were observed in 8 patients with pulmonary lymphoma, shaggy borders or halo of ground-glass attenuation in 7 patients, 2 patients had multiple patchy infiltrates bilaterally, 2 had diffuse interstitial infiltrates and 1 had miliary nodules. Multiple consolidations with air bronchogram and without hilar and mediastinal lymphadenopathy were observed in 2 patients with pulmonary pseudo lymphoma. Conclusion: Radiographic findings of pulmonary lymphoma were varied, the most common findings were the nodules or masses with shaggy borders or halo of ground-glass attenuation. The specific findings of pulmonary pseudo lymphoma were multiple consolidations with air bronchogram and without hilar and mediastinal lymphadenopathy. The final diagnosis relied on pathology

Development of Nb3Sn AC superconducting wire. Pt. 2

International Nuclear Information System (INIS)

Kasahara, Hobun; Torii, Shinji; Akita, Shirabe; Ueda, Kiyotaka; Kubota, Yoji; Yasohama, Kazuhiko; Kobayashi, Hisayasu; Ogasawara, Takeshi.

1993-01-01

For the realization of superconducting power apparatus, it is important that the development of highly stable superconducting cables. Nb 3 Sn wire has higher critical temperature than NbTi wire. Therefore, it is possible to make highly stable superconducting wires. In this report, we examine a manufacturing process of Ac Nb 3 Sn wire. This manufacturing process has four times higher critical current density than conventional processes. We have made a 400 kVA class AC coil with React and Wind method. The loss density of this coil was 20MW/m 3 at just before the quench. In this case, the temperature of cable increased about 3.8 K. This means that the Nb 3 Sn coil has a very high stability. (author)

Study of fluorine doped (Nb,Ir)O{sub 2} solid solution electro-catalyst powders for proton exchange membrane based oxygen evolution reaction

Energy Technology Data Exchange (ETDEWEB)

Kadakia, Karan Sandeep [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Jampani, Prashanth H., E-mail: pjampani@pitt.edu [Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Velikokhatnyi, Oleg I.; Datta, Moni Kanchan [Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Center for Complex Engineered Multifunctional Materials, University of Pittsburgh, PA 15261 (United States); Patel, Prasad [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Chung, Sung Jae [Mechanical Engineering and Materials Science, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Park, Sung Kyoo [Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Poston, James A.; Manivannan, Ayyakkannu [US Department of Energy, National Energy Technology Laboratory, Morgantown, WV 26507 (United States); Kumta, Prashant N. [Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Bioengineering, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Center for Complex Engineered Multifunctional Materials, University of Pittsburgh, PA 15261 (United States); Mechanical Engineering and Materials Science, Swanson School of Engineering, University of Pittsburgh, PA 15261 (United States); Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, PA 15217 (United States)

2016-10-15

Graphical abstract: High surface area (∼300 m{sup 2}/g) nanostructured powders of nominal composition (Nb{sub 1−x}Ir{sub x})O{sub 2} and (Nb{sub 1−x}Ir{sub x})O{sub 2}:10F have been synthesized and tested as oxygen evolution electro-catalysts for PEM based water electrolysis using a simple two-step chemical synthesis procedure. Superior electrochemical activity was demonstrated by fluorine doped compositions of (Nb{sub 1−x}Ir{sub x})O{sub 2} with an optimal composition (Nb{sub 0.75}Ir{sub 0.25})O{sub 2}:10F (x = 0.25) demonstrating on-par performance with commercial hydrated IrO{sub 2} and nanostructured in-house chemically synthesized IrO{sub 2}. Using first principles calculations, the electronic structure modification resulting in ∼75 at.% reduction (experimentally observed) in noble metal content without loss in catalytic performance and stability has been established. - Highlights: • (Nb{sub 1−x}Ir{sub x})O{sub 2}:10F nanopowder electrocatalysts have been wet chemically synthesized. • (Nb{sub 0.75}Ir{sub 0.25})O{sub 2}:10F exhibits superior electrochemical activity than pure IrO{sub 2}. • Stability of the (Nb,Ir)O{sub 2}:10F nanomaterials is comparable to pure (Nb,Ir)O{sub 2}. • High surface area F doped (Nb,Ir)O{sub 2} are promising OER anode electro-catalysts. - Abstract: High surface area (∼300 m{sup 2}/g) nanostructured powders of (Nb{sub 1−x}Ir{sub x})O{sub 2} and (Nb{sub 1−x}Ir{sub x})O{sub 2}:10F (∼100 m{sup 2}/g) have been examined as promising oxygen evolution reaction (OER) electro-catalysts for proton exchange membrane (PEM) based water electrolysis. Nb{sub 2}O{sub 5} and 10 wt.% F doped Nb{sub 2}O{sub 5} powders were prepared by a low temperature sol-gel process which were then converted to solid solution (Nb,Ir)O{sub 2} and 10 wt.% F doped (Nb,Ir)O{sub 2} [(NbIr)O{sub 2}:10F] electro-catalysts by soaking in IrCl{sub 4} followed by heat treatment in air. Electro-catalyst powders of optimal composition (Nb{sub 0.75}Ir

Preparation of Pb(Mg1/3Nb2/3)O3 by simultaneous precipitations

International Nuclear Information System (INIS)

Juiz, S.A.; Varela, J.A.; Santilli, C.V.; Pulcinelli, S.H.; Longo, E.

1990-01-01

Pb(Mg 1/3 Nb 2/3 )O 3 was obtained by simultaneous precipitation of Pb(NO 3 ) 2' Mg(NO 3 ) 2 . 6H 2 O and NH 4 H 2 /NbO(C 2 O 4 ) 3 ./3H 2 O in alkaline medium. DTA of the precipitates show the PMN formation between 700 and 750 0 C. XRD on powder calcined at 750 0 C indicates on other phases basiders PMN. Measurements of dielectric constants shows a Curie temperature shifted to -80 0 C. (author) [pt

Treatment results of localized gastric lymphoma

International Nuclear Information System (INIS)

Abe, Tatsuyuki; Gomi, Hiromichi; Sakaino, Shinjiro; Nakajima, Yasuo

2008-01-01

Between 2000 and 2007, 17 patients with localized gastric lymphoma (10 mucosa-associated lymphoid tissue lymphomas and 7 diffuse large B-cell lymphomas) were treated with radiotherapy alone or doxorubicin-based chemotherapy followed by radiotherapy. Radiation dose of mucosa-associated lymphoid tissue (MALT) lymphoma was 30 Gy with a daily fraction size of 1.5 Gy. Sixteen patients achieved complete remission and the 5-year overall survival of MALT lymphoma and diffuse large B-cell lymphoma (DLBCL) were 100% and 87%, respectively. No gastric perforation and hemorrhage were noticed. Using AP/LR 2-port radiotherapy markedly decreased the liver dose. (author)

Magnetic hyperfine fields on 181Ta at the Nb and V sites in Heusler alloys CO2YAL (Y=NB,V)

International Nuclear Information System (INIS)

Pendl Junior, W.

1990-01-01

Magnetic hyperfine fields (MHF) acting on sup(181)Ta at the Nb and V sites have been determined in the Heusler alloys Co sub(2) NbA1 and Co sub(2) VA1 by the time differential perturbed angular correlation (TDPAC) technique utilizing the well known 133-482 Kev gamma cascade in sup(181)Ta. The measurement were carried out using an automatic spectrometer consisting of three NaI(T1) detectors and a fast-slow coincidence system. The measurements were performed at 77 K with and without an externally applied magnetic field ( ∼ 4.5 KGauss) to determine the sign as well as the magnitude of the hyperfine fields in both alloys. For the alloy Co sub(2) NbA1 a unique field of -138(4) KOe was observed whereas in the case of Co sub(2)VA1 two distinct magnetic sites were observed. The present result show that approximately 24% of the sup(181)Ta atoms in this alloy probe a field of -116(4) KOe while the other ∼ 76% of the atoms feel -83(3) KOe. Present data along with the existing results on similar alloys Co sub(2)T1,Hf,Zr (Al,Ga,Sn) are discussed and compared with the magnetic hyperfine field systematics in Heusler alloys. (author)

Electric Properties of Pb(Sb1/2Nb1/2)O3 PbTiO3 PbZrO3 Ceramics

Science.gov (United States)

Kawamura, Yasushi; Ohuchi, Hiromu

1994-09-01

Solid-solution ceramics of ternary system xPb(Sb1/2Nb1/2)O3 yPbTiO3 zPbZrO3 were prepared by the solid-state reaction of powder materials. Ceramic, electric, dielectric and piezoelectric properties and crystal structures of the system were studied. Sintering of the system xPb(Sb1/2Nb1/2)O3 yPbTiO3 zPbZrO3 is much easier than that of each end composition, and well-sintered high-density ceramics were obtained for the compositions near the morphotropic transformation. Piezoelectric ceramics with high relative dielectric constants, high radial coupling coefficient and low resonant resistance were obtained for the composition near the morphotropic transformation. The composition Pb(Sb1/2Nb1/2)0.075Ti0.45Zr0.475O3 showed the highest dielectric constant (ɛr=1690), and the composition Pb(Sb1/2Nb1/2)0.05Ti0.45Zr0.5O3 showed the highest radial coupling coefficient (kp=64%).

Nb2O5 hollow nanospheres as anode material for enhanced performance in lithium ion batteries

International Nuclear Information System (INIS)

Sasidharan, Manickam; Gunawardhana, Nanda; Yoshio, Masaki; Nakashima, Kenichi

2012-01-01

Graphical abstract: Nb 2 O 5 hollow nanosphere constructed electrode delivers high capacity of 172 mAh g −1 after 250 cycles and maintains structural integrity and excellent cycling stability. Highlights: ► Nb 2 O 5 hollow nanospheres synthesis was synthesized by soft-template. ► Nb 2 O 5 hollow nanospheres were investigated as anode material in Li-ion battery. ► Nanostructured electrode delivers high capacity of 172 mAh g −1 after 250 cycles. ► The electrode maintains the structural integrity and excellent cycling stability. ► Nanosized shell domain facilitates fast lithium intercalation/deintercalation. -- Abstract: Nb 2 O 5 hollow nanospheres of average diameter ca. ∼29 nm and hollow cavity size ca. 17 nm were synthesized using polymeric micelles with core–shell–corona architecture under mild conditions. The hollow particles were thoroughly characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermal (TG/DTA) and nitrogen adsorption analyses. Thus obtained Nb 2 O 5 hollow nanospheres were investigated as anode materials for lithium ion rechargeable batteries for the first time. The nanostructured electrode delivers high capacity of 172 mAh g −1 after 250 cycles of charge/discharge at a rate of 0.5 C. More importantly, the hollow particles based electrodes maintains the structural integrity and excellent cycling stability even after exposing to high current density 6.25 A g −1 . The enhanced electrochemical behavior is ascribed to hollow cavity coupled with nanosized Nb 2 O 5 shell domain that facilitates fast lithium intercalation/deintercalation kinetics.

Ti2Nb10O29-x mesoporous microspheres as promising anode materials for high-performance lithium-ion batteries

Science.gov (United States)

Deng, Shengjue; Luo, Zhibin; Liu, Yating; Lou, Xiaoming; Lin, Chunfu; Yang, Chao; Zhao, Hua; Zheng, Peng; Sun, Zhongliang; Li, Jianbao; Wang, Ning; Wu, Hui

2017-09-01

Ti2Nb10O29 has recently been reported as a promising anode material for lithium-ion batteries. However, its poor electronic conductivity and insufficient Li+-ion diffusion coefficient significantly limit its rate capability. To tackle this issue, a strategy combining nanosizing and crystal-structure modification is employed. Ti2Nb10O29-x mesoporous microspheres with a sphere-size range of 0.5-4 μm are prepared by a one-step solvothermal method followed by thermal treatment in N2. These Ti2Nb10O29-x mesoporous microspheres exhibit primary nanoparticles, a large specific surface area (22.9 m2 g-1) and suitable pore sizes, leading to easy electron/Li+-ion transport and good interfacial reactivity. Ti2Nb10O29-x shows a defective shear ReO3 crystal structure with O2- vacancies and an increased unit cell volume, resulting in its increased Li+-ion diffusion coefficient. Besides Ti4+ and Nb5+ ions, Ti2Nb10O29-x comprises Nb4+ ions with unpaired 4d electrons, which significantly increase its electronic conductivity. As a result of these improvements, the Ti2Nb10O29-x mesoporous microspheres reveal superior electrochemical performances in term of large reversible specific capacity (309 mAh g-1 at 0.1 C), outstanding rate capability (235 mAh g-1 at 40 C) and durable cyclic stability (capacity retention of 92.1% over 100 cycles at 10 C).

In vivo efficacy of the Bcl-2 antagonist ABT-737 against aggressive Myc-driven lymphomas

OpenAIRE

Mason, Kylie D.; Vandenberg, Cassandra J.; Scott, Clare L.; Wei, Andrew H.; Cory, Suzanne; Huang, David C. S.; Roberts, Andrew W.

2008-01-01

Deregulated Myc expression drives many human cancers, including Burkitt's lymphoma and a highly aggressive subset of diffuse large cell lymphomas. Myc-driven tumors often display resistance to chemotherapeutics because of acquisition of mutations that impair the apoptosis pathway regulated by the Bcl-2 protein family. Given the need to identify new therapies for such lymphomas, we have evaluated the efficacy of ABT-737, a small molecule that mimics the action of the BH3-only proteins, natural...

Crystal growth and optical properties of Sm:CaNb2O6 single crystal

International Nuclear Information System (INIS)

Di Juqing; Xu Xiaodong; Xia Changtai; Zeng Huidan; Cheng Yan; Li Dongzhen; Zhou Dahua; Wu Feng; Cheng Jimeng; Xu Jun

2012-01-01

Highlights: ► Sm:CaNb 2 O 6 single crystal was grown by the Czochralski method. ► Thermal expansion coefficients and J–O parameters were calculated. ► We found that this crystal had high quantum efficiency of 97%. - Abstract: Sm:CaNb 2 O 6 single crystal has been grown by the Czochralski method. Its high-temperature X-ray powder diffraction, optical absorption, emission spectroscopic as well as lifetime have been studied. Thermal expansion coefficients (α), J–O parameters (Ω i ), radiative lifetime (τ rad ), branching ratios (β) and stimulated emission cross-sections (σ e ) were calculated. The quantum efficiency (η) was calculated to be 97%. The intense peak emission cross section at 610, 658 nm were calculated to be 2.40 × 10 −21 , 2.42 × 10 −21 cm 2 . These results indicate that Sm:CaNb 2 O 6 crystal has potential use in visible laser and photonic devices area.

Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

Directory of Open Access Journals (Sweden)

Rui Sun

2016-06-01

Full Text Available We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100 substrates with a TiN buffer layer. A 50-nm-thick (200-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large IcRN product of 3.8 mV, a sharp quasiparticle current rise with a ΔVg of 0.4 mV, and a small subgap leakage current. The junction quality factor Rsg/RN was about 23 for the junction with a Jc of 47 A/cm2 and was about 6 for the junction with a Jc of 3.0 kA/cm2. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200-orientated TiN buffer layer and had a highly crystalline structure with the (200 orientation.

Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

Energy Technology Data Exchange (ETDEWEB)

Sun, Rui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Makise, Kazumasa; Terai, Hirotaka [Advanced ICT Research Institute, National Institute of Information and Communications Technology (Japan); Zhang, Lu [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Wang, Zhen, E-mail: zwang@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Shanghai Tech University, Shanghai 201210 (China)

2016-06-15

We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100) substrates with a TiN buffer layer. A 50-nm-thick (200)-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large I{sub c}R{sub N} product of 3.8 mV, a sharp quasiparticle current rise with a ΔV{sub g} of 0.4 mV, and a small subgap leakage current. The junction quality factor R{sub sg}/R{sub N} was about 23 for the junction with a J{sub c} of 47 A/cm{sup 2} and was about 6 for the junction with a J{sub c} of 3.0 kA/cm{sup 2}. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200)-orientated TiN buffer layer and had a highly crystalline structure with the (200) orientation.

Structural, electrical, and optical properties of polycrystalline NbO_2 thin films grown on glass substrates by solid phase crystallization

International Nuclear Information System (INIS)

Nakao, Shoichiro; Kamisaka, Hideyuki; Hirose, Yasushi; Hasegawa, Tetsuya

2017-01-01

We investigated the structural, electrical, and optical properties of polycrystalline NbO_2 thin films on glass substrates. The NbO_2 films were crystallized from amorphous precursor films grown by pulsed laser deposition at various oxygen partial pressures (P_O_2). The electrical and optical properties of the precursor films systematically changed with P_O_2, demonstrating that the oxygen content of the precursor films can be finely controlled with P_O_2. The precursors were crystallized into polycrystalline NbO_2 films by annealing under vacuum at 600 C. The NbO_2 films possessed extremely flat surfaces with branching patterns. Even optimized films showed a low resistivity (ρ) of 2 x 10"2 Ω cm, which is much lower than the bulk value of 1 x 10"4 Ω cm, probably because of the inferior crystallinity of the films compared with that of a bulk NbO_2 crystal. Both oxygen-rich and -poor NbO_2 films showed lower ρ than that of the stoichiometric film. The NbO_2 film with the highest ρ showed an indirect bandgap of 0.7 eV. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Follicular non-Hodgkin's lymphoma

International Nuclear Information System (INIS)

Hayashi, D.; Lee, J.C.; Devenney-Cakir, B.; Zaim, S.; Ounadjela, S.; Solal-Celigny, P.; Juweid, M.; Guermazi, A.

2010-01-01

Follicular non-Hodgkin's lymphoma (NHL) is a unique subtype of NHL, which is indolent, incurable with a high prevalence of residual mass after treatment, and may transform to more aggressive NHL. The aim of this review is to (1) describe the histological and flow cytometry characteristics of follicular NHL; (2) introduce the Follicular Lymphoma International Prognostic Index 2 (FLIPI-2), which allows better treatment selection and patient stratification for clinical trials; (3) illustrate the classic and atypical ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and positron-emission tomography (PET)/CT appearance of follicular NHL; and (4) characterize the appearance of nodal and extranodal follicular NHL with pathological correlation. Imaging is essential in every step of the management of patients with follicular lymphoma. Overall survival is improved with better predictive tools and new targeted biological therapies. Radiologists should be aware of possible active residual mass, indolent recurrence, transformation, and association with other primary cancers in patients treated for follicular lymphoma.

Collinear order in frustrated quantum antiferromagnet on square lattice (CuBr)LaNb2O7

International Nuclear Information System (INIS)

Oba, Noriaki; Kageyama, Hiroshi; Kitano, Taro

2006-01-01

Magnetic susceptibility, heat capacity, high-field magnetization and neutron diffraction measurements have been performed on a two-dimensional s=1/2 square-lattice system (CuBr)LaNb 2 O 7 , prepared by a topotactic ion-exchange reaction of a nonmagnetic double-layered perovskite RbLaNb 2 O 7 . (CuBr)LaNb 2 O 7 exhibits a second-order magnetic transition at 32K, in marked contrast to a spin-singlet nature for its Cl-based counterpart (CuCl)LaNb 2 O 7 , despite nearly identical structural parameters. The magnetic structure is a novel collinear antiferromagnetic (CAF) ordering characterized by a modulation vector q=(π, 0, π) with a reduced moment of 0.6μ B . Mixed ferromagnetic nearest-neighbor (J 1 ) and antiferromagnetic second-nearest-neighbor (J 2 ) interactions are of comparable strength (J 1 /k B =-35.6K and J 2 /k B =41.3K), placing the system in a more frustrated region of the CAF phase than ever reported. (author)

A combined diffraction and dielectric properties investigation of Ba3MnNb2O9 complex perovskites

International Nuclear Information System (INIS)

Liu Yun; Withers, Ray L.; Whichello, A.P.; Noren, Lasse; Ting, Valeska; Brink, Frank; Fitz Gerald, John D.

2005-01-01

A combined synthesis, diffraction and dielectric properties investigation of the dependence (and effect) of Mn 2+ /Nb 5+ ordering in Ba 3 MnNb 2 O 9 (BMN) upon annealing atmosphere and processing conditions has been carried out. Annealing in different atmospheres was not found to significantly alter either nominal stoichiometry or structure type. The obtained structure type (disordered metrically cubic or ordered trigonal) as well as the measured electrical properties (in particular, the dielectric loss) were, however, found to be sensitive to the synthesis route. Samples obtained via solid-state reaction were found to be predominantly of 1:2 Mn 2+ /Nb 5+ ordered, P3-bar m1 trigonal structure type whereas samples obtained via an aqueous solution route were found to be of a Mn 2+ /Nb 5+ 'disordered', metrically cubic structure type. All solid-state synthesized samples showed reasonable dielectric properties. The microwave dielectric constant and dielectric quality factor, Q, at 8GHz of an as-synthesized BMN sample were 38 and 100, respectively. By contrast, the dielectric loss of the metrically cubic, Mn 2+ /Nb 5+ 'disordered' samples obtained via an aqueous solution synthesis process were significantly worse

Corrosion of thin, magnetron sputtered Nb_2O_5 films

International Nuclear Information System (INIS)

Pillis, Marina Fuser; Geribola, Guilherme Altomari; Scheidt, Guilherme; Gonçalves de Araújo, Edval; Lopes de Oliveira, Mara Cristina; Antunes, Renato Altobelli

2016-01-01

Highlights: • Niobium oxide based films were obtained by DC magnetron sputtering. • Different deposition times were tested. • The best corrosion resistance was obtained for the Nb_2O_5 film produced at 15′. • Film porosity determines the corrosion resistance. - Abstract: Niobium oxide based thin films were deposited on AISI 316 stainless steel substrates using reactive DC magnetron sputtering. Structure, composition and corrosion resistance of the niobium oxide films were studied. The corrosion behavior of the specimens was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The concentration of niobium and oxygen in the films was obtained by Rutherford backscattering spectroscopy (RBS). The film structure was analyzed by X-ray diffractometry. The corrosion resistance of the substrate was improved by the Nb_2O_5 layers. The best protective performance was achieved for the deposition time of 15 min.

Non-Hodgkin's lymphoma in patients with systemic lupus erythematosus: 2 case reports

Energy Technology Data Exchange (ETDEWEB)

Ferri, M. [Hamilton Health Sciences Corp., Dept. of Radiology, Hamilton, Ontario (Canada); Mar, C.; Bhatia, R.S. [Memorial Univ. of Newfoundland, Health Sciences Centre, Discipline of Radiology, St. John' s Newfoundland (Canada)

2002-04-01

The association between autoimmune rheumatic diseases and malignancy, and between lymphoproliferative disorders and systemic lupus erythematosus (SLE), in particular, has been documented. Although the imaging features of pulmonary lymphoma and of pulmonary manifestations of SLE have been described separately, the imaging features of the 2 together have not been demonstrated. We present the cases of 2 patients with SLE presenting with non-Hodgkin's lymphoma (NHL). (author)

Hexagonal perovskites with cationic vacancies. 21. Structure of Ba/sub 4/Nb/sub 2/WvacantO/sub 12/ and Ba/sub 3/LaNb/sub 3/vacantO/sub 12/

Energy Technology Data Exchange (ETDEWEB)

Rother, H J; Kemmler-Sack, S; Treiber, U; Cyris, W R [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1980-07-01

Compounds of type Ba/sub 4/M/sub 2/sup(V)WvacantO/sub 12/ and Ba/sub 3/LaM/sub 3/sup(V)vacantO/sub 12/ with Msup(V) = Nb, Ta belong to the group of rhombohedral 12 L stacking polytypes (space group R-3m, sequence (hhcc)/sub 3/). The structure determinations on powder patterns for the Nb compounds gave a refined, intensity related R' value of 6.3% (Ba/sub 4/Nb/sub 2/WvacantO/sub 12/) and 6.6% (Ba/sub 3/LaNb/sub 3/vacantO/sub 12/). The octahedral net consists of blocks of three face connected octahedra with a central void (M/sub 2/vacantO/sub 12/ unit), which are linked to each other through single corner sharing octahedra. In both compounds the M atoms in the M/sub 2/vacantO/sub 12/ groups are displaced in the direction of the central void. The A atoms move in the same direction but the dislocation for A in the hexagonal packed sheets (neighbouring the vacancies) is stronger than in the cubic packed AO/sub 3/ sheets. The results of the vibrational spectroscopic investigations are reported for Ba/sub 4/Nb/sub 2/WvacantO/sub 12/, Ba/sub 4/Ta/sub 2/WvacantO/sub 12/, Ba/sub 3/LaNb/sub 3/vacantO/sub 12/ and Ba/sub 4/CeW/sub 2/vacantO/sub 12/; they are discussed in connection with the factor group analysis.

A new one-dimensional compound: Synthesis and structure of InNb3(Se2)6

International Nuclear Information System (INIS)

Deng Shuiquan; Zhuang Honghui; Huang Jinshun; Huang Jingling

1993-01-01

The new one-dimensional compound, indium niobium selenide, was synthesized by high-temperature solid-state reactions. The structure is composed of [Nb 3 (Se 2 ) 6 ] ∞ chains running along the c axis with In atoms intercalated between these chains. All the Nb atoms have rectangular antiprismatic coordination environments. All the Se atoms in the structure are in the form of Se 2 dimers with Se-Se distances of 2.325(2) and 2.356(2) A. (orig.)

Microstructure evolution and mechanical properties of Ti−22Al−25Nb alloy joints brazed with Ti−Ni−Nb alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, Y.; Cai, X.Q.; Yang, Z.W., E-mail: tjuyangzhenwen@163.com; Qiu, Q.W.; Wang, D.P.; Liu, Y.C.

2016-10-01

Ti{sub 45}Ni{sub 45}Nb{sub 10} (at.%) brazing alloy, fabricated by arc melting, was successfully used to braze Ti−22Al−25Nb (at.%) alloy. The microstructures of Ti{sub 45}Ni{sub 45}Nb{sub 10} brazing alloy and Ti−22Al−25Nb alloy brazed joints were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and micro-area X-ray diffraction (XRD). The effects of the brazing parameters on the interfacial microstructure and mechanical properties of the Ti−22Al−25Nb alloy brazed joints were investigated. The results showed that the joint was primarily comprised of two characteristic zones: diffusion zone I and central zone II, and the reaction phases formed in the brazed joint were the B2, O, τ{sub 3}, and Ti{sub 2}Ni phase. The crystal orientation of B2 phase in diffusion zone I was consistent with that in the Ti−22Al−25Nb substrate. The O phase was precipitated from the B2 phase. As the brazing temperature or holding time increased, τ{sub 3} was gradually replaced by the B2 phase, and the Ti{sub 2}Ni phase decreased and ultimately disappeared. The maximum shear strength achieved at room temperature was 318 MPa when the joint was brazed at 1180 °C for 20 min, whereas it was 278 MPa at 650 °C. Crack primarily propagated in the τ{sub 3} compound, which was extremely hard and brittle, and partially traversed the B2 and O phases. - Highlights: • Ti{sub 45}Ni{sub 45}Nb{sub 10} alloy was successfully developed to braze Ti−22Al−25Nb alloy. • Ti−22Al−25Nb alloy was transformed from B2 phase into the O + B2 duplex phase after brazing. • Crystal orientation of B2 in joint was dependent on metal substrate. • Correlation between joint microstructure and mechanical properties was revealed. • Ti−22Al−25Nb brazed joint had excellent ambient and high temperature strength.

Lymphoma of the eyelid

DEFF Research Database (Denmark)

Svendsen, Frederik Holm; Heegaard, Steffen

2017-01-01

Lymphoma of the eyelid constitutes 5% of ocular adnexal lymphoma. In previously published cases, 56% of lymphomas of the eyelid are of B-cell origin and 44% are of T-cell origin. The most frequent B-cell lymphomas are extranodal marginal zone lymphoma (27 cases-14%) and diffuse large B......-cell lymphoma (18 cases-9%). T-cell lymphomas are most frequently mycosis fungoides (25 cases-13%), extranodal natural killer/T-cell, nasal-type lymphoma (12 cases-6%), and primary cutaneous anaplastic large-cell lymphoma (12 cases-6%). This distribution differs from the distribution of ocular adnexal lymphoma...... and that of cutaneous lymphoma. The majority of subtypes occur in elderly patients, except for lymphoblastic lymphoma of B-cell and T-cell origin and Burkitt lymphoma, which occur in children and adolescents. Several subtypes have a male predominance, including peripheral T-cell lymphoma and Burkitt lymphoma. Only...

Investigation of B2 and related phases in the Ti-Al-Nb ternary systems

International Nuclear Information System (INIS)

Bendersky, L.A.; Boettinger, W.J.

1989-01-01

Alloy compositions around Ti 2 AlNb were studied to establish phase equilibria and transformations during cooling from 1100 degrees C and 1400 degrees C. In addition to general results obtained on a wide range of compositions, which include evidence for a broad B2 phase field, transformation of BCC Ti 4 Al 3 Nb to a phase with an omega-type structure is reported. Detailed analysis indicates that this phase has the B8 2 structure after annealing at 700 degrees C

Pd/Nb2O5/SiO2 catalyst for the direct hydrodeoxygenation of biomass-related compounds to liquid alkanes under mild conditions.

Science.gov (United States)

Shao, Yi; Xia, Qineng; Liu, Xiaohui; Lu, Guanzhong; Wang, Yanqin

2015-05-22

A simple Pd-loaded Nb2 O5 /SiO2 catalyst was prepared for the hydrodeoxygenation of biomass-related compounds to alkanes under mild conditions. Niobium oxide dispersed in silica (Nb2 O5 /SiO2 ) as the support was prepared by the sol-gel method and characterized by various techniques, including N2 adsorption, XRD, NH3 temperature-programmed desorption (TPD), TEM, and energy-dispersive X-ray spectroscopy (EDAX) atomic mapping. The characterization results showed that the niobium oxide species were amorphous and well dispersed in silica. Compared to commercial Nb2 O5 , Nb2 O5 /SiO2 has significantly more active niobium oxide species exposed on the surface. Under mild conditions (170 °C, 2.5 MPa), Pd/10 %Nb2 O5 /SiO2 was effective for the hydrodeoxygenation reactions of 4-(2-furyl)-3-buten-2-one (aldol adduct of furfural with acetone), palmitic acid, tristearin, and diphenyl ether (model compounds of microalgae oils, vegetable oils, and lignin), which gave high yields (>94 %) of alkanes with little CC bond cleavage. More importantly, owing to the significant promotion effect of NbOx species on CO bond cleavage and the mild reaction conditions, the CC cleavage was considerably restrained, and the catalyst showed an excellent activity and stability for the hydrodeoxygenation of palmitic acid with almost no decrease in hexadecane yield (94-95 %) in a 150 h time-on-stream test. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of Bi(Zn2/3Nb1/3)O3 Modification on the Relaxor Behavior and Piezoelectricity of Pb(Mg1/3Nb2/3)O3-PbTiO3 Ceramics.

Science.gov (United States)

Liu, Zenghui; Wu, Hua; Paterson, Alisa; Ren, Wei; Ye, Zuo-Guang

2017-10-01

Relaxor lead magnesium niobate (PMN)-based materials exhibit complex structures and unusual properties that have been puzzling researchers for decades. In this paper, a new ternary solid solution of Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 -Bi(Zn 2/3 Nb 1/3 )O 3 (PMN-PT-BZN) is prepared in the form of ceramics, and the effects of the incorporation of BZN into the PMN-PT binary system are investigated. The crystal structure favors a pseudocubic symmetry and the relaxor properties are enhanced as the concentration of BZN increases. The relaxor behavior and the related phase transformations are studied by dielectric spectroscopy. A phase diagram mapping out the characteristic temperatures and various states is established. Interestingly, the piezoelectricity of the PMN-PT ceramics is significantly enhanced by the BZN substitution, with an optimal value of d 33 reaching 826 pC/N for 0.96[0.7Pb(Mg 1/3 Nb 2/3 )O 3 -0.3PbTiO 3 ]-0.04Bi(Zn 2/3 Nb 1/3 )O 3 . This paper provides a better understanding of the relaxor ferroelectric behavior, and unveils a new relaxor-based ternary system as piezoelectric materials potentially useful for electromechanical transducer applications.

Cerebral lymphoma - CT and MRI diagnostic

International Nuclear Information System (INIS)

Popovska, T.; Yanakiev, A.; Zashev, I.

2012-01-01

Lymphoma (Hodgkin's and non-Hodgkin's) is a disease of the lymphatic system where the central neural system is affected in very rare cases. According to different authors the frequency of cases with lymphoma where the neural system is affected varies between 0, 2 % and 0, 5 %, and the primary cerebral lymphoma accounts for about 1-2% of ail brain neoplasms. The intracranial form of iymphoma is usually a late onset of the disease with serious and potentially fatal complications for the patient. These complications usually appear several years after diagnosing the disease, but the cerebral lymphoma may occur even in patients who are in remission which is the case with our patient. We present you a case with a 38 -year-old female, who was hospitalized in the Neuro ward with the following complaints -loss of speech for a few minutes, dizziness, weakness, tingling in her right leg as well as shuffling. This patient was diagnosed with histological B-cell non-Hodgkin's lymphoma 8 years ago. CT and MRI were carried out on that patient. Despite both clinical and radiographic suspicions for intracranial forms of lymphoma, the patient was still difficult to diagnose. A definitive diagnosis was given after a surgery and histological examination, i.e. non-Hodgkin's lymphoma - large B-cell lymphoma. This case is of interest because of its rare intracranial localization of the lymphoma. The knowledge of CT and MRI images of the intracranial form of lymphoma may help diagnosing, but images should be interpreted together with the clinical and paraclinical results Hodgkin's and non-Hodgkin's) is a disease of the lymphatic system where the central neural system is affected in very rare cases. According to different authors the frequency of cases with lymphoma where the neural system is affected varies between 0, 2 % and 0, 5 %, and the primary cerebral lymphoma accounts for about 1-2% of ail brain neoplasms. The intracranial form of iymphoma is usually a late onset of the disease

High-rate capability of three-dimensionally ordered macroporous T-Nb2O5 through Li+ intercalation pseudocapacitance

Science.gov (United States)

Lou, Shuaifeng; Cheng, Xinqun; Wang, Long; Gao, Jinlong; Li, Qin; Ma, Yulin; Gao, Yunzhi; Zuo, Pengjian; Du, Chunyu; Yin, Geping

2017-09-01

Orthorhombic Niobium oxide (T-Nb2O5) has been regarded as a promising anode material for high-rate lithium ion batteries (LIBs) due to its potential to operate at high rates with improved safety and high theoretical capacity of 200 mA h g-1. Herein, three-dimensionally ordered macroporous (3DOM) T-Nb2O5, with mesoporous hierarchical structure, was firstly prepared by a simple approach employing self-assembly polystyrene (PS) microspheres as hard templates. The obtained T-Nb2O5 anode material presents obvious and highly-efficiency pseudocapacitive Li+ intercalation behaviour, which plays a dominant role in the kinetics of electrode process. As a result, rapid Li+ intercalation/de-intercalation are achieved, leading to excellent rate capability and long cycle life. The 3DOM T-Nb2O5 shows a remarkable high capacity of 106 and 77 mA h g-1 at the rate of 20C and 50C. The work presented herein holds great promise for future design of material structure, and demonstrates the great potential of T-Nb2O5 as a practical high-rate anode material for LIBs.

Experimental study on microstructure development of binary system Zn-O-Nb2O5 sintered at 1100 deg C-1400 deg C

International Nuclear Information System (INIS)

Syarif, Dani Gustaman; Sukirman, Engkir; Handayani, Ari; Hidayat, Saeful

2000-01-01

In order to find effective (simple) varistor, in this work effect of Nb 2 O 5 addition on microstructure development and it's mechanism was studied experimentally. The study was conducted by sintering Zn-O added with 0-1% mole Nb 2 O 5 at 1100 o C-1400 o C in air for 1 hour and analyzing the sintered pellets using optical and electromicroscope (SEM) and x-ray diffractometer. The x-ray diffraction analysis showed that in Nb 2 O 5 added -ZnO (Zn-O-Nb 2 O 5 ) pellets sintered at 1100 o C-1400 o C, second phase of Zn 3 Nb 2 O 8 existed. On the other hand, the metallographic analysis showed that at sintering temperature of 1100 o C-1400 o C, grain size of Zn-O-Nb 2 O 5 pellets increased with increasing of Nb 2 O 5 , however, the grain size decreased again after the concentration of Nb 2 O 5 exceeding certain value. From this data it was know also, that there was solid solution area in Zn-O-Nb 2 O 5 phase diagram. At sintering temperature ≥ 1300 o C, there was liquid phase sintering that make grains become rounded

Effect of excess Mg and Excess Nb incorporation into the B-site of pyrochlore in the Pb-Mg-Nb-O system

Directory of Open Access Journals (Sweden)

Mergen, A.

2002-12-01

Full Text Available In the Pb-Mg-Nb-O system, excess Mg and excess Nb incorporation into the B-site of PMN pyrochlore were investigated along the compositons of Pb1.83Mg0.29+xNb1.71-xO6.39-1.5x where x=0.1, 0.2, 0.3, 0.4, 0.522 and Pb1.83Mg0.29-xNb1.71+xO6.39+1.5x where x=0.1, 0.2, 0.29 respectively. Excess Mg incorporation led to the formation of perovskite and excess Nb resulted in formation of Pb2Nb2O7 monoclinic pyrochlore. The densities of the PMN pyrochlore-PMN perovskite mixtures decreased with an increase in Mg concentration. The relative permittivity of the mixtures increased with decreasing pyrochlore content. The effect of pyrochlore on the permittivity follows the Weiner’s mixture rule up to a pyrochlore content of 50 vol%.

Se investigó la incorporación en lugares B de pirocloro PMN de un exceso de Mg y un exceso de Nb. En el sistema Pb-Mg-Nb-O2 las composiciones analizadas fueron Pb1.83Mg0.29+xNb1.71-xO6.39-1.5x donde x=0.1, 0.2, 0.3, 0.4, 0.522 y en Pb1.83Mg0.29-xNb1.71+xO6.39+1.5x donde x= 0.1, 0.2,0.29. El exceso de Mg condujo a la formación de perovskita y el exceso de Nb resultó en la formación del pirocloro monolínico, Pb2Nb2O7. La densidad de la mezcla de PMN pirocloro-perovskita dismunuye con el aumento de la concentración de Mg. La permitividad dieléctrica de las mezclas aumenta con la disminución del contenido de pirocloro. El efecto del pirocloro sobre la permitividad sigue la regla de mezclas de Weiner hasta conenidos de pirocloro del 50%.

Composition, ferroelectric and antiferroelectric ordering in Pb2InNbO6 crystals

International Nuclear Information System (INIS)

Bokov, A.A.; Raevskij, I.P.; Smotrakov, V.G.

1984-01-01

Effect of thermal treatment on temperatures of phase transitions and electrical properties has been studied in Pb 2 InNbO 6 crystals with the high-temperature phase transition of the order-disorder type in In and Nb cations disposition in crystallographic positions. The order-disorder transition temperature (Tsub(t) approximately 1020 deg C) has been directly determined for the first time using the method of electric conductivity investigation. It has been shown that Pb 2 InNbO 6 in the ordered state represents the antiferroelectric material with the Curie point of 195 deg C, and it represents the ferroelectric material with a smeared transition to the paraelectric phase in the temperature range of 60 deg C in the disordered state. With temperature decrease crystals with the mean ordering degree-paraelectric phase pass to the antiferroelectric phase and then to the ferroelectric phase

Primary Breast Mucosa-Associated Lymphoid Tissue (MALT Lymphoma Transformation to Diffuse Large B-cell Lymphoma: A Case Report

Directory of Open Access Journals (Sweden)

Şerife Hülya Arslan

2012-09-01

Full Text Available Primary non-Hodgkin’s lymphoma (NHL of the breast constitutes 0.04%-0.53% of all malignancies and 2.2% of extra nodal lymphomas. In total, 7%-8% of all B-cell lymphomas are the mucosa-associated lymphoid tissue (MALT type, of which up to 50% of primary gastric MALT lymphoma. Herein we present a patient with breast MALT lymphoma that transformed to diffuse large B-cell lymphoma (DLBCL. A 69-year-old female presented with a mass on her left breast. Physical examination showed a 3 × 3-cm mass located 1 cm from the areola on the upper lateral quadrant of the breast at the 1 o’clock position, which was fixed and firm. Excisional biopsy was performed and pathologic examination of the specimen showed MALT lymphoma transformation to DLBCL. The patient was staged as II-EA. The rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP protocol was scheduled as treatment. Following 6 courses of R-CHOP, 2 additional courses of rituximab were administered. Positron emission tomography (PET-CT was done at the end of the treatment. PET showed that the patient was in complete remission. At the time this report was written, the patient was being followed-up at the outpatient clinic on a regular basis. Lymphoma of the breast is a rarity among malignant tumors of the breast. The most common type of lymphoma is DLBCL. Breast MALT lymphoma is extremely rare. Primary MALT lymphoma of the breast can transform from low grade to high grade and recurrence is possible; therefore, such patients should be monitored carefully for transformation.

Piezoelectric and electromechanical properties of ultrahigh temperature CaBi2Nb2O9 ceramics

International Nuclear Information System (INIS)

Wang, Jin-Feng; Zhang, Shujun; Shrout, Thomas R.; Wang, Chun-Ming

2009-01-01

The piezoelectric, dielectric, and electromechanical properties of the (KCe) co-substituted calcium bismuth niobate (CaBi 2 Nb 2 O 9 , CBN) were investigated. The piezoelectric activities of CBN ceramics were significantly enhanced and the dielectric loss tan δ decreased by (KCe) substitution. The Ca 0.9 (KCe) 0.05 Bi 2 Nb 2 O 9 ceramics possess the optimal piezoelectric properties, and the piezoelectric coefficient (d 33 ), Curie temperature (T C ), and electromechanical coupling factors (k p and k t ) were found to be 16 pC/N, 868 C, 8.6%, and 23.8%, respectively. The excellent dielectric and electromechanical spectra, together with the high piezoelectric activities and ultrahigh Curie temperature, make CBN ceramics promising candidates for high temperature piezoelectric applications. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Transformation of Follicular Lymphoma to a High-Grade B-Cell Lymphoma With MYC and BCL2 Translocations and Overlapping Features of Burkitt Lymphoma and Acute Lymphoblastic Leukemia: A Case Report and Literature Review

Directory of Open Access Journals (Sweden)

Alina M Bischin

2017-02-01

Full Text Available Most commonly, histologic transformation (HT from follicular lymphoma (FL manifests as a diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS. Less frequently, HT may result in a high-grade B-cell lymphoma (HGBL with MYC and B-cell lymphoma protein 2 (BCL2 and/or BCL6 gene rearrangements, also known as “double-hit” or “triple-hit” lymphomas. In the 2016 revision of the World Health Organization (WHO classification of lymphoid neoplasms, the category B-cell lymphoma, unclassifiable was eliminated due to its vague criteria and limiting diagnostic benefit. Instead, the WHO introduced the HGBL category, characterized by MYC and BCL2 and/or BCL6 rearrangements. Cases that present as an intermediate phenotype of DLBCL and Burkitt lymphoma (BL will fall within this HGBL category. Very rarely, HT results in both the intermediate DLBCL and BL phenotypes and exhibits lymphoblastic features, in which case the WHO recommends that this morphologic appearance should be noted. In comparison with de novo patients with DLBCL, NOS, those with MYC and BCL2 and/or BCL6 gene rearrangements have a worse prognosis. A 63-year-old woman presented with left neck adenopathy. Laboratory assessments, including complete blood count, complete metabolic panel, serum lactate dehydrogenase, and β 2 -microglobulin, were all normal. A whole-body computerized tomographic (CT scan revealed diffuse adenopathy above and below the diaphragm. An excisional node biopsy showed grade 3A nodular FL. The Ki67 labeling index was 40% to 50%. A bone marrow biopsy showed a small focus of paratrabecular CD20+ lymphoid aggregates. She received 6 cycles of bendamustine (90 mg/m 2 on days +1 and +2 and rituximab (375 mg/m 2 on day +2, with each cycle delivered every 4 weeks. A follow-up CT scan at completion of therapy showed a partial response with resolution of axillary adenopathy and a dramatic shrinkage of the large retroperitoneal nodes. After 18 months, she had crampy

Conjunctival Lymphoma

DEFF Research Database (Denmark)

Kirkegaard, Marina M; Rasmussen, Peter K; Coupland, Sarah E

2016-01-01

IMPORTANCE: To date, the clinical features of the various subtypes of conjunctival lymphoma (CL) have not been previously evaluated in a large cohort. OBJECTIVE: To characterize subtype-specific clinical features of CL and their effect on patient outcome. DESIGN, SETTING, AND PARTICIPANTS...... age was 61.3 years, and 55.1% (145 of 263) were female. All lymphomas were of B-cell type. The most frequent subtype was extranodal marginal zone lymphoma (EMZL) (68.4% [180 of 263]), followed by follicular lymphoma (FL) (16.3% [43 of 263]), mantle cell lymphoma (MCL) (6.8% [18 of 263]), and diffuse...... large B-cell lymphoma (DLBCL) (4.6% [12 of 263). Conjunctival lymphoma commonly manifested in elderly individuals (age range, 60-70 years old), with EMZL having a female predilection (57.8% [104 of 180]) and MCL having a marked male predominance (77.8% [14 of 18]). Unlike EMZL and FL, DLBCL and MCL were...

Determination of activation energy of hydrogen diffusion in Zr-2.5%Nb alloy

International Nuclear Information System (INIS)

Chandra, Komal; Kulkarni, A.S.; Ramanjaneyulu, P.S.; Yadav, C.S.; Saxena, M.K.; Tomar, B.S.; Ramakumar, K.L.; Sunil, Sourav; Singh, R.N.

2013-01-01

The present paper describes the study on the determination of diffusion coefficient of hydrogen in Zr-2.5%Nb alloy. Hydrogen was charged on Zr-2.5% Nb alloy electrolytically. After annealing at required temperature, hydrogen concentration at various depths from the charged end was determined employing hot vacuum extraction-quadrupole mass spectrometer (HVE-QMS). The depth profile was used to obtain the diffusion coefficient employing Fick's second law of diffusion. From the Arrhenius relation between diffusion coefficient and temperature, activation energy of hydrogen diffusion was calculated. (author)

Fabrication of Nb3Al superconducting wires by utilizing the mechanically alloyed Nb(Al)ss supersaturated solid-solution with low-temperature annealing

International Nuclear Information System (INIS)

Pan, X.F.; Yan, G.; Qi, M.; Cui, L.J.; Chen, Y.L.; Zhao, Y.; Li, C.S.; Liu, X.H.; Feng, Y.; Zhang, P.X.; Liu, H.J.

2014-01-01

Highlights: • This paper reported superconducting properties of the powder-in-tube Nb 3 Al wires. • The Nb 3 Al wires were made by using Nb(Al) ss supersaturated solid solution powders. • The Cu-matrix Nb 3 Al superconducting wires have been successfully fabricated. • The transport J c of Nb 3 Al wires at 4.2 K, 10 T is up to 12,700 A/cm 2 . - Abstract: High-performance Nb 3 Al superconducting wire is a promising candidate to the application of high-field magnets. However, due to the production problem of km-grade wires that are free from low magnetic field instability, the Nb 3 Al wires made by rapid heating, quenching and transformation (RHQT) are still not available to the large-scale engineering application. In this paper, we reported the properties of the in situ powder-in-tube (PIT) Nb 3 Al superconducting wires, which were made by using the mechanically alloyed Nb(Al) ss supersaturated solid solution, as well as the low temperature heat-treatment at 800 °C for 10 h. The results show that Nb 3 Al superconductors in this method possess very fine grains and well superconducting properties, though a little of Nb 2 Al and Nb impurities still keep being existence at present work. At the Nb 3 Al with a nominal 26 at.% Al content, the onset T c reaches 15.8 K. Furthermore, a series of Nb 3 Al wires and tapes with various sizes have been fabricated; for the 1.0 mm-diameter wire, the J c at 4.2 K, 10 T and 14 T have achieved 12,700 and 6900 A/cm 2 , respectively. This work suggests it is possible to develop high-performance Cu-matrix Nb 3 Al superconducting wires by directly using the Nb(Al) ss supersaturated solid-solution without the complex RHQT heat-treatment process

X-ray investigation of Nb/O interfaces

International Nuclear Information System (INIS)

Delheusy, M.

2008-01-01

X-ray free electron lasers and the future International Linear Collider project are based on the performance of niobium superconducting RF cavities for efficient particle acceleration. A remarkable increase of the RF accelerating field is usually achieved by low-temperature annealing of the cavities (T≤150 C, several hours). The microscopic origin of this effect has remained unclear; however, it has been argued that a redistribution of subsurface interstitial oxygen into niobium is involved. In this study, the near surface structure of oxidized niobium single crystals and its evolution upon vacuum annealing has been studied by means of non-destructive in-situ surface sensitive x-ray techniques: x-ray reflectivity (XRR), grazing incidence x-ray diffraction (GIXD), diffuse scattering (GIDXS), crystal truncation rods measurements (CTRs), and high-resolution core-level spectroscopy (HRCLS). A first insight into the interplay between the oxide formation/dissolution and the occurrence of 181 subsurface interstitial oxygen has been given. The natural oxide on Nb(110) and Nb(100) surfaces is constituted of Nb 2 O 5 , NbO 2 and NbO, from the surface to the interface. It reduces progressively upon heating from Nb 2 O 5 to NbO 2 at low temperatures, and to NbO at 300 C. The Nb(110)/NbO(111) interface presents a Nishiyma-Wassermann epitaxial orientation relationship. The depth-distribution of interstitial oxygen has been established indicating that most of the oxygen is located in the direct vicinity of the oxide/niobium interface. No evidence of oxygen depletion below the oxide layer has been observed for the low temperature thermal treatments and surface preparations investigated in this study. (author) [fr

X-ray investigation of Nb/O interfaces

Energy Technology Data Exchange (ETDEWEB)

Delheusy, Melissa

2008-07-07

X-ray free electron lasers and the future International Linear Collider project are based on the performance of niobium superconducting rf cavities for efficient particle acceleration. A remarkable increase of the rf accelerating field is usually achieved by low-temperature annealing of the cavities (T<150 C, several hours). The microscopic origin of this effect has remained unclear; however, it has been argued that a redistribution of subsurface interstitial oxygen into niobium is involved. In this study, the near surface structure of oxidized niobium single crystals and its evolution upon vacuum annealing has been studied by means of non-destructive in-situ surface sensitive X-ray techniques: X-ray reflectivity (XRR), grazing incidence X-ray diffraction (GIXD), diffuse scattering (GIDXS), crystal truncation rods measurements (CTRs), and high-resolution core-level spectroscopy (HRCLS). A first insight into the interplay between the oxide formation/dissolution and the occurrence of subsurface interstitial oxygen has been given. The natural oxide on Nb(110) and Nb(100) surfaces is constituted of Nb{sub 2}O{sub 5}, NbO{sub 2} and NbO, from the surface to the interface. It reduces progressively upon heating from Nb{sub 2}O{sub 5} to NbO{sub 2} at low temperatures, and to NbO at 300 C. The Nb(110)/NbO(111) interface presents a Nishiyama-Wassermann epitaxial orientation relationship. The depth-distribution of interstitial oxygen has been established indicating that most of the oxygen is located in the direct vicinity of the oxide/niobium interface. No evidence of oxygen depletion below the oxide layer has been observed for the low temperature thermal treatments and surface preparations investigated in this study. (orig.)

Photoluminescence of rare-earth ion (Eu3+, Tm3+, and Er3+)-doped and co-doped ZnNb2O6 for solar cells

Science.gov (United States)

Gao, Sen-Pei; Qian, Yan-Nan; Wang, Biao

2015-08-01

Visible converted emissions produced at an excitation of 286 nm in ZnNb2O6 ceramics doped with rare-earth ions (RE = Eu3+, Tm3+, Er3+ or a combination of these ions) were investigated with the aim of increasing the photovoltaic efficiency of solar cells. The structure of RE:ZnNb2O6 ceramics was confirmed by x-ray diffraction patterns. The undoped ZnNb2O6 could emit a blue emission under 286-nm excitation, which is attributed to the self-trapped excitons’ recombination of the efficient luminescence centers of edge-shared NbO6 groups. Upon 286-nm excitation, Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 ceramics showed blue, green, and red emissions, which correspond to the transitions of 5D0 → 7FJ (J = 1-4) (Eu3+), 1G4 → 3H6 (Tm3+), and 2H11/2/4S3/2 → 4I15/2 (Er3+), respectively. The calculated CIE chromaticity coordinates of Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 are (0.50, 0.31), (0.14, 0.19), and (0.29, 0.56), respectively. RE ion-co-doped ZnNb2O6 showed a combination of characteristic emissions. The chromaticity coordinates of Eu/Tm:ZnNb2O6, Eu/Er:ZnNb2O6, and Tm/Er:ZnNb2O6 were calculated to be (0.29, 0.24), (0.45, 0.37), and (0.17, 0.25). Project supported by the National Natural Science Foundation of China (Grant Nos. 10572155 and 10732100) and the Research Fund for the Doctoral Program of Ministry of Education, China (Grant No. 20130171130003).

Multifilamentar superconductor wires of Cu-Nb-Al and Cu-Nb3Sn obtained by a new method

International Nuclear Information System (INIS)

Lima, O.F. de

1985-01-01

A new method to prepare multifilamentar wires of Cu-Nb 3 Sn which is based on power metallurgy is developed. Wires of Cu+xw%Nb++2wt%Al (x =10,30) were tinned and heat treated for Sn diffusion and reaction (T = 700 0 C), leading to the Nb 3 Sn A 15 phase. Final wires showed microfilament density around 8 x 10 4 mm -2 . The superconducting properties (T sup(c), J sup(c) x H), mechanical properties (tau x epsilon) and eletrical resistivity for Cu-Nb-Al wires were as normally expected. The Cu-Nb 3 Sn wires showed high T sub(c) approx. 17.9 K, very near that for the pure A 15 phase. J sub(c) x H curves were approx. 4 times lower than typical published results for wires prepared by other methods. The experimental evidence shows that J sub(c) increases when decreases the initial Nb particle size. (Author) [pt

Synthesis and photocatalytic activity of hydrated layered perovskite K2-xLa2Ti3-xNb xO10 (0 ≤ x ≤ 1) and protonated derivatives

International Nuclear Information System (INIS)

Huang Yunfang; Wu Jihuai; Wei Yuelin; Hao Sancun; Huang Miaoliang; Lin Jianming

2007-01-01

A series of photocatalytic intercalated materials K 2-x La 2 Ti 3-x Nb x O 10 (0 ≤ x ≤ 1) and a series of its protonated derivatives H 2-x La 2 Ti 3-x Nb x O 10 were prepared by solid-state reaction and ion-exchange reaction. The photocatalytic activities of samples were evaluated using methanol as electron donor under UV irradiation. All H 2-x La 2 Ti 3-x Nb x O 10 samples possessed approximately twofold higher photocatalytic activity than the corresponding K 2-x La 2 Ti 3-x Nb x O 10 . This difference was most pronounced for the photocatalyst H 1.9 La 2 Ti 2.9 Nb 0.1 O 10 which showed the highest activity: 22 μmol H 2 /catalyst (g) for 5 h, more than three times the activity of K 1.9 La 2 Ti 2.9 Nb 0.1 O 10

Formation of Nb3Al in powder processed Nb-Al superconductors

International Nuclear Information System (INIS)

Johnson, P.E.

1987-05-01

In high magnetic fields, the critical current density is strongly dependent on the upper critical field, which is determined primarily by the stoichiometry of the Nb 3 Al. The critical temperature (T/sub c/), like the upper critical field, is considered to be a measure of the ''intrinsic'' quality of the superconductor, indicating the stoichiometry, order, and strain. If the A15 phase is stoichiometric and well ordered, a high T/sub c/ (and high H/sub C 2 /) is expected, regardless of the volume fraction of superconductor. On the other hand, if sigma phase is present with the A15, the resultant composition gradient across the sigma-A15 interface(s) requires that some of the A15 be off-stoichiometric, and therefore that the T/sub c/ (and H/sub C 2 /) be low. Thus the extent of the A15 (Nb 3 Al) reaction and the quality of the A15 formed are interdependent. This work focuses on the factors that control the extent of Nb 3 Al formation in Nb/Al powder wires. The morphology and content of the reacted and unreacted wires are studied in optical, SEM, and TEM micrographs. Critical current density data and its dependence on processing are explained in terms of the unreacted microstructure and its effect on the extent of Nb 3 Al formation. As a method of improving the critical current density, a new variation of the conventional powder process for wire manufacturing is developed and tested

Cerebrospinal fluid beta-2-microglobulin in adult patients with acute leukemia or lymphoma

DEFF Research Database (Denmark)

Hansen, P B; Kjeldsen, L; Dalhoff, K

1992-01-01

Beta-2-microglobulin (B2m) was measured in the cerebrospinal fluid (CSF) and serum from 18 adults with acute lymphoblastic leukemia, acute myeloblastic leukemia or lymphoma in order to detect early central nervous system (CNS) involvement or relapse. Six had CNS-involvement documented by neurologic...... determination of CSF-B2m alone may be a useful and sensitive marker of CNS-dissemination in acute leukemia and malignant lymphoma. Using the criteria of CSF-B2m greater than 160 nmol/l as a positive diagnostic test the sensitivity of the test was 100%, the specificity was 76%. The same values for the CSF...

ESMO Consensus Conference on malignant lymphoma

DEFF Research Database (Denmark)

Buske, C; Hutchings, M; Ladetto, M

2018-01-01

The European Society for Medical Oncology (ESMO) consensus conference on mature B cell lymphomas and chronic lymphocytic leukaemia (CLL) was held on 20 June 2015 in Lugano, Switzerland, and included a multidisciplinary panel of 25 leading experts. The aim of the conference was to develop recommen......The European Society for Medical Oncology (ESMO) consensus conference on mature B cell lymphomas and chronic lymphocytic leukaemia (CLL) was held on 20 June 2015 in Lugano, Switzerland, and included a multidisciplinary panel of 25 leading experts. The aim of the conference was to develop...... of the three key areas identified. This manuscript presents the consensus recommendations regarding the clinical management of elderly patients diagnosed with malignant lymphoma. Four clinically-relevant topics identified by the panel were: 1) how to define patient fitness, 2) assessing quality of life, 3......) diagnostic work-up and 4) clinical management of elderly patients with lymphoma. Each of these key topics is addressed in the context of five different lymphoma entities, namely: CLL, follicular lymphoma, mantle cell lymphoma, peripheral T-cell lymphoma and diffuse large B-cell lymphoma. Results, including...

Bridge toughening enhancement in double-notched MoSi2/Nb model composites

International Nuclear Information System (INIS)

Pickard, S.M.; Ghosh, A.K.

1996-01-01

Single-ply composites containing both laminate and continuous Nb fiber reinforcement coated with Al 2 O 3 debond coatings in an MoSi 2 matrix are used as model systems for investigating bridge toughening concepts for various precrack configurations., When cracks are introduced symmetrically on either side of the ductile phase with zero crack offset spacing (S = 0), a minimum amount of energy is expended in plastic deformation and the local rupture process in the metal, as measured by the area of the force displacement curve in tension. For asymmetric precracks introduced on either side of the ductile reinforcement, as the offset spacing, S, was varied from 1 to 20 R (R being the ductile phase half-thickness), the overall extension continuously increased within the bridging ligament. The effective ligament gage length was nearly equal to the crack spacing in the limiting case of a weak interface. However, the ductile Nb phase developed a Nb 5 Si 3 reaction layer on its surface which was strongly bonded to the Nb and was found to undergo periodic cracking, leading to numerous shear bands within the ductile phase. This unique and previously unreported mode of metal deformation in shear loading has been analyzed using a simple geometric model. The results indicate that the profusion of shear bands is the primary source of toughening enhancement in the case of asymmetric crack geometry, which was not recognized in prior work of this type

Cs0.49NbPS6

Directory of Open Access Journals (Sweden)

Hoseop Yun

2011-01-01

Full Text Available The quaternary thiophosphate, Cs0.49NbPS6, caesium hexathioniobiophosphate(V, has been synthesized by the reactive halide flux method. The title compound is isotypic with Rb0.46TaPS6 and is made up of a bicapped trigonal–biprismatic [Nb2S12] unit and a tetrahedral [PS4] group. The [Nb2S12] units linked by the [PS4] tetrahedra form infinite chains, yielding a three-dimensional network with rather large van der Waals gaps along the c axis in which the disordered Cs+ ions reside. The electrons released by the Cs atoms are transferred to the pairwise niobium metal site and there are substantial intermetallic Nb—Nb bonding interactions. This leads to a significant decrease of the intermetallic distance in the title compound compared to that in TaPS6. The classical charge balance of the title compound may be represented as [Cs+]0.49[Nb4.51+][P5+][S2−]4[S22−].

Estudio dieléctrico de cerámicas de textura y microestructura controladas con composiciones (SrBi2Nb2O91-x(Bi3TiNbO9x

Directory of Open Access Journals (Sweden)

Pardo, L.

2002-02-01

Full Text Available Ceramics of composition (SrBi2Nb2O91-x(Bi3TiNbO9x with x = 0.35, 0.65 and 1.00 and Aurivillius type structure have been prepared by natural sintering and hot pressing. Amorphous precursors were obtained by mechanochemical activation of stoichiometric mixtures of oxides and carbonates, which allows using moderate processing temperatures. These materials are interesting for their use as high temperature piezoelectrics. Dielectric characterisation allows to know the temperature at what takes place the ferro-paraelectric transition, which limits the working temperature of the material. It also gives information on how the electric properties, especially the d. c. conductivity, affect the polarizability of the ceramics. The properties relation with the microstructure and the texture is studied. In this work, dielectric studies of these materials have been made, in the frequency interval from 100 Hz to 5 MHz and in the temperature range from 200 ºC up to the ferroparaelectric transition temperatures (>900 ºC for Bi3TiNbO9.Se han preparado cerámicas de la solución sólida (SrBi2Nb2O91-x(Bi3TiNbO9x con x = 0.35, 0.65 y 1.00 y estructura tipo Aurivillius obtenidas por sinterización natural y por prensado en caliente. Se parte de precursores amorfos obtenidos por activación mecanoquímica de una mezcla estequiométrica de óxidos y carbonatos, lo que permite utilizar temperaturas moderadas de procesado. Estos materiales son interesantes por su posible uso como piezoeléctricos de alta temperatura. La caracterización dieléctrica permite establecer a qué temperatura se encuentra la transición ferro-paraeléctrica que limita la temperatura de uso del material y como afectan las propiedades eléctricas, especialmente la conductividad d. c., a la polarizabilidad de las cerámicas, así como su relación con su microestructura y textura. En este trabajo se ha realizado el estudio dieléctrico de estos materiales en el intervalo de frecuencias de 100

Stress distribution and lattice distortions in Nb3Sn multifilament wires under uniaxial tensile loading at 4.2 K

International Nuclear Information System (INIS)

Scheuerlein, C; Flükiger, R; Kadar, J; Bordini, B; Ballarino, A; Bottura, L; Di Michiel, M; Buta, F; Seeber, B; Senatore, C; Siegrist, T; Besara, T

2014-01-01

The lattice parameter changes in three types of Nb 3 Sn superconducting wires during uniaxial stress–strain measurements at 4.2 K have been measured by high-energy synchrotron x-ray diffraction. The nearly-stress-free Nb 3 Sn lattice parameter has been determined using extracted filaments, and the elastic strain in the axial and transverse wire directions in the different wire phases has been calculated. The mechanical properties of the PIT and RRP wire are mainly determined by the properties of Nb 3 Sn and unreacted Nb. This is in contrast to the bronze route wire, where the matrix can carry substantial loads. In straight wires the axial Nb 3 Sn pre-strain is strongest in the bronze route wire, its value being smaller in the PIT and RRP wires. A strong reduction of the non-Cu elastic modulus of about 30% is observed during cool-down from ambient temperature to 4.2 K. The Nb 3 Sn Poisson ratio at 4.2 K measured in the untwisted bronze route wire is 0.35. The present study also shows that the process route has a strong influence on the Nb 3 Sn texture. (paper)

Note: High-power piezoelectric transformer fabricated with ternary relaxor ferroelectric Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3 single crystal.

Science.gov (United States)

Wang, Qing; Ma, Chuanguo; Wang, Feifei; Liu, Bao; Chen, Jianwei; Luo, Haosu; Wang, Tao; Shi, Wangzhou

2016-03-01

A plate-shaped piezoelectric transformer was designed and fabricated using ternary relaxor ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O3-Pb(In(1/2)Nb(1/2))O3-PbTiO3. Both the input and output sections utilized the transverse-extensional vibration mode. The frequency and load dependences of the electrical properties for the proposed transformer were systematically studied. Results indicated that under a matching load resistance of 14.9 kΩ, a maximum output power of 2.56 W was obtained with the temperature rise less than 5 °C. The corresponding power density reached up to 50 W/cm(3). This ternary single-crystal transformer had potential applications in compact-size converters requiring high power density.

Structural, electrical, and optical properties of polycrystalline NbO{sub 2} thin films grown on glass substrates by solid phase crystallization

Energy Technology Data Exchange (ETDEWEB)

Nakao, Shoichiro [Kanagawa Academy of Science and Technology (KAST), Kawasaki (Japan); Kamisaka, Hideyuki [Department of Chemistry, The University of Tokyo (Japan); Hirose, Yasushi; Hasegawa, Tetsuya [Kanagawa Academy of Science and Technology (KAST), Kawasaki (Japan); Department of Chemistry, The University of Tokyo (Japan)

2017-03-15

We investigated the structural, electrical, and optical properties of polycrystalline NbO{sub 2} thin films on glass substrates. The NbO{sub 2} films were crystallized from amorphous precursor films grown by pulsed laser deposition at various oxygen partial pressures (P{sub O2}). The electrical and optical properties of the precursor films systematically changed with P{sub O2}, demonstrating that the oxygen content of the precursor films can be finely controlled with P{sub O2}. The precursors were crystallized into polycrystalline NbO{sub 2} films by annealing under vacuum at 600 C. The NbO{sub 2} films possessed extremely flat surfaces with branching patterns. Even optimized films showed a low resistivity (ρ) of 2 x 10{sup 2} Ω cm, which is much lower than the bulk value of 1 x 10{sup 4} Ω cm, probably because of the inferior crystallinity of the films compared with that of a bulk NbO{sub 2} crystal. Both oxygen-rich and -poor NbO{sub 2} films showed lower ρ than that of the stoichiometric film. The NbO{sub 2} film with the highest ρ showed an indirect bandgap of 0.7 eV. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Composite Lymphoma : EBV-positive Classic Hodgkin Lymphoma and Peripheral T-cell Lymphoma A Case Report

NARCIS (Netherlands)

Gualco, Gabriela; Chioato, Lucimara; Van Den Berg, Anke; Weiss, Lawrence M.; Bacchi, Carlos E.

Composite lymphomas are rare and defined as hematopoietic neoplasms with more than I malignant lymphomatous clone showing different phenotypic features. Of all possible combinations between non-Hodgkin lymphomas, B cell or T cell, and Hodgkin lymphoma, the least frequent are the ones combining

Zirconium hydrides and Fe redistribution in Zr-2.5%Nb alloy under ion irradiation

Energy Technology Data Exchange (ETDEWEB)

Idrees, Y.; Yao, Z. [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, ON, Canada, K7L 3N6 (Canada); Cui, J.; Shek, G.K. [Kinetrics, Mississauga, ON (Canada); Daymond, M.R., E-mail: daymond@queensu.ca [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, ON, Canada, K7L 3N6 (Canada)

2016-11-15

Zr-2.5%Nb alloy is used to fabricate the pressure tubes of the CANDU reactor. The pressure tube is the primary pressure boundary for coolant in the CANDU design and is susceptible to delayed hydride cracking, reduction in fracture toughness upon hydride precipitation and potentially hydride blister formation. The morphology and nature of hydrides in Zr-2.5%Nb with 100 wppm hydrogen has been investigated using transmission electron microscopy. The effect of hydrides on heavy ion irradiation induced decomposition of the β phase has been reported. STEM-EDX mapping was employed to investigate the distribution of alloying elements. The results show that hydrides are present in the form of stacks of different sizes, with length scales from nano- to micro-meters. Heavy ion irradiation experiments at 250 °C on as-received and hydrided Zr-2.5%Nb alloy, show interesting effects of hydrogen on the irradiation induced redistribution of Fe. It was found that Fe is widely redistributed from the β phase into the α phase in the as-received material, however, the loss of Fe from the β phase and subsequent precipitation is retarded in the hydrided material. This preliminary work will further the current understanding of microstructural evolution of Zr based alloys in the presence of hydrogen. - Graphical abstract: STEM HAADF micrographs at low magnification showing the hydride structure in Zr-2.5Nb alloy.

Origin of Superconductivity and Latent Charge Density Wave in NbS2

Science.gov (United States)

Heil, Christoph; Poncé, Samuel; Lambert, Henry; Schlipf, Martin; Margine, Elena R.; Giustino, Feliciano

2017-08-01

We elucidate the origin of the phonon-mediated superconductivity in 2 H -NbS2 using the ab initio anisotropic Migdal-Eliashberg theory including Coulomb interactions. We demonstrate that superconductivity is associated with Fermi surface hot spots exhibiting an unusually strong electron-phonon interaction. The electron-lattice coupling is dominated by low-energy anharmonic phonons, which place the system on the verge of a charge density wave instability. We also provide definitive evidence for two-gap superconductivity in 2 H -NbS2 , and show that the low- and high-energy peaks observed in tunneling spectra correspond to the Γ - and K -centered Fermi surface pockets, respectively. The present findings call for further efforts to determine whether our proposed mechanism underpins superconductivity in the whole family of metallic transition metal dichalcogenides.

Temperature stability of c-axis oriented LiNbO3/SiO2/Si thin film layered structures

International Nuclear Information System (INIS)

Tomar, Monika; Gupta, Vinay; Mansingh, Abhai; Sreenivas, K.

2001-01-01

Theoretical calculations have been performed for the temperature stability of the c-axis oriented LiNbO 3 thin film layered structures on passivated silicon (SiO 2 /Si) substrate with and without a non-piezoelectric SiO 2 overlayer. The phase velocity, electromechanical coupling coefficient and temperature coefficient of delay (TCD) have been calculated. The thicknesses of various layers have been determined for optimum SAW performance with zero TCD. The presence of a non-piezoelectric SiO 2 overlayer on LiNbO 3 film is found to significantly enhance the coupling coefficient. The optimized results reveal that a high coupling coefficient of K 2 =3.45% and a zero TCD can be obtained in the SiO 2 /LiNbO 3 /SiO 2 /Si structure with a 0.235λ thick LiNbO 3 layer sandwiched between 0.1λ thick SiO 2 layers. (author)

Comparing Thermal Stability of NbTi and Nb$_3$Sn Wires

CERN Document Server

Breschi, M; Bottura, L; Devred, A; Trillaud, F

2009-01-01

The investigation of quenching in low temperature superconducting wires is of great relevance for a proper design of superconductive cables and magnets. This paper reports the experimental results of a vast measurement campaign of quench induced by laser pulses on NbTi and Nb$_{3}$Sn wires in pool boiling Helium I. A comparison of the quench behavior of two typical NbTi and Nb$_{3}$Sn wires is shown from different standpoints. Different qualitative behaviors of the voltage traces recorded during quenches and recoveries on NbTi and Nb$_{3}$Sn wires are reported and analyzed. It is shown that the Nb$_{3}$Sn wire exhibits a quench or no-quench behavior, whereas quenches and recoveries are exhibited by the NbTi wire. The two wires are also compared considering the behaviors of the two main parameters describing quench, i.e. quench energies and quench velocities, with respect to operation current and pulse duration and magnetic field. It is shown that the Nb$_{3}$Sn wire exhibits a ‘kink’ of the quench energy ...

MDX-010 in Treating Patients With Recurrent or Refractory Lymphoma

Science.gov (United States)

2014-05-22

Adult Grade III Lymphomatoid Granulomatosis; B-cell Chronic Lymphocytic Leukemia; Cutaneous B-cell Non-Hodgkin Lymphoma; Extranodal Marginal Zone B-cell Lymphoma of Mucosa-associated Lymphoid Tissue; Intraocular Lymphoma; Nodal Marginal Zone B-cell Lymphoma; Recurrent Adult Burkitt Lymphoma; Recurrent Adult Diffuse Large Cell Lymphoma; Recurrent Adult Diffuse Mixed Cell Lymphoma; Recurrent Adult Diffuse Small Cleaved Cell Lymphoma; Recurrent Adult Grade III Lymphomatoid Granulomatosis; Recurrent Adult Hodgkin Lymphoma; Recurrent Adult Immunoblastic Large Cell Lymphoma; Recurrent Adult Lymphoblastic Lymphoma; Recurrent Grade 1 Follicular Lymphoma; Recurrent Grade 2 Follicular Lymphoma; Recurrent Mantle Cell Lymphoma; Recurrent Marginal Zone Lymphoma; Refractory Hairy Cell Leukemia; Small Intestine Lymphoma; Splenic Marginal Zone Lymphoma; Testicular Lymphoma; Waldenström Macroglobulinemia

Phase transition and piezoelectric properties of K0.48Na0.52NbO3-LiTa0.5Nb0.5O3-NaNbO3 lead-free ceramics

International Nuclear Information System (INIS)

Gao Feng; Liu Liangliang; Xu Bei; Cao Xiao; Deng Zhenqi; Tian Changsheng

2011-01-01

Highlights: → The evolution of the crystal structure for the new phase K 3 Li 2 Nb 5 O 15 was described. → The dielectric relaxor behavior would be strengthened by increasing plate-like NN. → k p and d 33 decrease with increasing amount of plate-like NN. → 0.01-0.03 mol of plate-like NN is a proper content for texturing ceramics by RTGG. - Abstract: Plate-like NaNbO 3 (NN) particles were used as the raw material to fabricate (1 - x)[0.93 K 0.48 Na 0.52 Nb O 3 -0.07Li(Ta 0.5 Nb 0.5 )O 3 ]-xNaNbO 3 lead-free piezoelectric ceramics using a conventional ceramic process. The effects of NN on the crystal structure and piezoelectric properties of the ceramics were investigated. The results of X-ray diffraction suggest that the perovskite phase coexists with the K 3 Li 2 Nb 5 O 15 phase, and the tilting of the oxygen octahedron is probably responsible for the evolution of the tungsten-bronze-typed K 3 Li 2 Nb 5 O 15 phase. The Curie temperature (T C ) is shifted to lower temperature with increasing NN content. (1 - x)[0.93 K 0.48 Na 0.52 NbO 3 -0.07Li(Ta 0.5 Nb 0.5 )O 3 ]-xNaNbO 3 ceramics show obvious dielectric relaxor characteristics for x > 0.03, and the relaxor behavior of ceramics is strengthened by increasing NN content. Both the electromechanical coupling factor (k p ) and the piezoelectric constant (d 33 ) decrease with increasing amounts of NN. 0.01-0.03 mol of plate-like NaNbO 3 in 0.93 K 0.48 Na 0.52 NbO 3 -0.07Li(Ta 0.5 Nb 0.5 )O 3 gives the optimum content for preparing textured ceramics by the RTGG method.

TEM study of a hot-pressed Al2O3-NbC composite material

Directory of Open Access Journals (Sweden)

Wilson Acchar

2005-03-01

Full Text Available Alumina-based composites have been developed in order to improve the mechanical properties of the monolithic matrix and to replace the WC-Co material for cutting tool applications. Al2O3 reinforced with refractory carbides improves hardness, fracture toughness and wear resistance to values suitable for metalworking applications. Al2O3-NbC composites were uniaxially hot-pressed at 1650 °C in an inert atmosphere and their mechanical properties and microstructures were analyzed. Sintered density, average grain size, microhardness and fracture toughness measurements and microstructural features were evaluated. Results have shown that the mechanical properties of alumina-NbC are comparable to other carbide systems. Microstructural analysis has shown that the niobium carbide particles are mainly located at the grain boundaries of alumina grains, which is an evidence of the "pinning effect", produced by NbC particles.

FT-NMR of {sup 93}Nb in TiO{sub 2} single crystal

Energy Technology Data Exchange (ETDEWEB)

Sato, Kazunori; Akai, Hisazumi [Osaka Univ., Toyonaka (Japan). Faculty of Science; Takeda, Sadamu [and others

1997-03-01

We determined the electric field gradient (EFG) at the impurity Nb site in TiO{sub 2} experimentally. It was shown that the principal component and the asymmetry parameter differ significantly from those of the host Ti site in TiO{sub 2}. Ab initio calculations of the EFG`s by the KKR method with the super-cell reproduced this experimental results if Nb{sup 5+} ion is simulated by shifting {epsilon}{sub f}. It was shown that considering the charge state of impurities was indispensable in calculating the EFG`s at impurity sites. (J.P.N.)

Peripheral T-Cell Lymphoma

Science.gov (United States)

... Non-Hodgkin Lymphoma Peripheral T-Cell Lymphoma Primary Central Nervous System Lymphoma T-Cell Lymphoma Transformed Mycosis Fungoides Waldenstrom Macroglobulinemia Young Adult Lymphoma Overview Treatment Options Relapsed/Refractory Long-term ...

Angioimmunoblastic T-Cell Lymphoma

Science.gov (United States)

... Non-Hodgkin Lymphoma Peripheral T-Cell Lymphoma Primary Central Nervous System Lymphoma T-Cell Lymphoma Transformed Mycosis Fungoides Waldenstrom Macroglobulinemia Young Adult Lymphoma Overview Treatment Options Relapsed/Refractory Long-term ...

Anaplastic Large Cell Lymphoma

Science.gov (United States)

... Non-Hodgkin Lymphoma Peripheral T-Cell Lymphoma Primary Central Nervous System Lymphoma T-Cell Lymphoma Transformed Mycosis Fungoides Waldenstrom Macroglobulinemia Young Adult Lymphoma Overview Treatment Options Relapsed/Refractory Long-term ...

Reactive synthesis of NbAl3 matrix composites

International Nuclear Information System (INIS)

Lu, L.; Kim, Y.S.; Gokhale, A.B.; Abbaschian, R.

1990-01-01

NbAl 3 matrix composites were synthesized in-situ via reactive hot compaction (RHC) of elemental powders. It was found that the simultaneous application of pressure during synthesis was effective in attaining a near-theoretical density matrix at relatively low temperatures and pressures. Using this technique, two types of composites were produced: matrices containing a uniform dispersion of second phase particles (either Nb 3 Al or Nb 2 Al with an Nb core or Nb 2 Al) and matrices reinforced with coated or uncoated ductile Nb filaments. It was found that a limited amount of toughening is obtained using the first approach, while composites containing coated Nb filaments exhibited a significant increase in the ambient temperature fracture toughness. In this paper, various aspects of RHC processing of NbAl 3 matrix composites, the effect of initial stoichiometry and powder size on the microstructure, as well as the mechanical behavior of the composites are discussed

Anti-ICOS Monoclonal Antibody MEDI-570 in Treating Patients With Relapsed or Refractory Peripheral T-cell Lymphoma Follicular Variant or Angioimmunoblastic T-cell Lymphoma

Science.gov (United States)

2018-05-09

Follicular T-Cell Lymphoma; Grade 1 Follicular Lymphoma; Grade 2 Follicular Lymphoma; Grade 3a Follicular Lymphoma; Recurrent Angioimmunoblastic T-Cell Lymphoma; Recurrent Follicular Lymphoma; Recurrent Mature T- and NK-Cell Non-Hodgkin Lymphoma; Recurrent Mycosis Fungoides; Recurrent Primary Cutaneous T-Cell Non-Hodgkin Lymphoma; Refractory Angioimmunoblastic T-Cell Lymphoma; Refractory Follicular Lymphoma; Refractory Mature T-Cell and NK-Cell Non-Hodgkin Lymphoma; Stage IB Mycosis Fungoides AJCC v7; Stage II Mycosis Fungoides AJCC v7; Stage III Cutaneous T-Cell Non-Hodgkin Lymphoma; Stage III Mycosis Fungoides AJCC v7; Stage IV Cutaneous T-Cell Non-Hodgkin Lymphoma; Stage IV Mycosis Fungoides AJCC v7

Lymphoma imaging with a new technetium-99m labelled antibody, LL2

International Nuclear Information System (INIS)

Murthy, S.; Sharkey, R.M.; Goldenberg, D.M.; Lee, R.E.; Pinsky, C.M.; Hansen, H.J.; Burger, K.; Swayne, L.C.

1992-01-01

The lesion detection capability of a new technetium-99m labelled B-cell lymphoma monoclonal antibody (MoAb) imaging agent, LL2, was evaluated in 8 patients with non-Hodgkin's lymphoma and 1 patient with chronic lymphocytic leukaemia. The MoAb kit consists of a 1-vial, 1-mg Fab' form of LL2 ready for instant labelling with technetium. The patients were injected with ∝925 MBq (25 mCi) of 99m Tc-LL2 Fab' (1 mg), and planar and single photon emission tomography (SPET) studies were performed at 3-4 h post injection and at 24 h. There was no evidence of thyroid or stomach activity up to 24 h. Uniform splenic uptake was seen in all patients. Two non-lymphoma patients were also administered with the same agent and demonstrated a similar splenic distribution; therefore, splenic targeting was not scored as tumour-specific. A total of 29 from 48 tumour sites were detected by scintigraphy, including tumours of various grades and histological types. Excluding 1 patient who had a large tumour burden of over 500 g, 29 of 33 lesions were detected. One patient was free of disease at the time of the study and had a negative scan. Another patient showed excellent targeting of gallium-negative sites in the liver and bone. The bone involvement was not known prior to the antibody study and was subsequently confirmed by a bone scan. Additional sites of MoAb localization could not be followed in this group, since most patients went on to radioimmunotherapy immediately following the 99m Tc-LL2 study. However, these initial results suggest that this new 99m Tc-labelled antibody imaging kit should be further investigated for its potential role in the staging and follow-up of lymphoma patients. (orig.)

The effect of low platinum loading on the efficiency of PEMFC’s electrocatalysts supported on TiO2–Nb, and SnO2–Nb: An experimental comparison between active and stable conditions

International Nuclear Information System (INIS)

Shahgaldi, Samaneh; Hamelin, Jean

2015-01-01

Highlights: • SnO 2 –Nb, and TiO 2 –Nb thin films synthesized via sputtering. • SnO 2 –Nb, and TiO 2 –Nb thin films applied as a Pt support in PEMFC. • Low amount of Pt sputtered on supports as catalyst in cathode side. • Fabricate a single cell and plot I–V curves. - Abstract: Electrocatalyst supports have been demonstrated to strongly influence the cost, performance and durability of PEMFC systems, which have been among the heated research topics in the course of the past decades. However, the present support materials used in fuel cell stack are not adequately durable for commercialization. Development of active electrocatalyst with cost effectiveness and high durability is one of the main challenges. In this paper, titania and tin oxide nanoparticles doped nobidium were selected as thermo chemically stable and carbonless electrocatalyst supports. Low Pt loading (0.05 mg/cm 2 ) is deposited on supports through sputtering method, and the structure, the distribution of nanoparticles, and the electrical resistivity were systematically analyzed. To make the studies of oxygen reduction reaction activity, catalytic stability and performance of PEMFC more precise, rotation disk electrode (RDE), cyclic voltammetry (CV), and single cell test were utilized. The data analysis of this study highlighted that SnO 2 –Nb–Pt depicted higher stability and better fuel cell performance in comparison with TiO 2 –Nb–Pt

Bubble template synthesis of Sn2Nb2O7 hollow spheres for enhanced visible-light-driven photocatalytic hydrogen production.

Science.gov (United States)

Zhou, Chao; Zhao, Yufei; Bian, Tong; Shang, Lu; Yu, Huijun; Wu, Li-Zhu; Tung, Chen-Ho; Zhang, Tierui

2013-10-28

Hierarchical Sn2Nb2O7 hollow spheres were prepared for the first time via a facile hydrothermal route using bubbles generated in situ from the decomposition of urea as soft templates. The as-obtained hollow spheres with a large specific surface area of 58.3 m(2) g(-1) show improved visible-light-driven photocatalytic H2 production activity in lactic acid aqueous solutions, about 4 times higher than that of the bulk Sn2Nb2O7 sample prepared by a conventional high temperature solid state reaction method.

Internal friction and Young's modulus measurements in Zr-2.5Nb alloy doped with hydrogen

International Nuclear Information System (INIS)

Ritchie, I.G.; Pan, Z.-L.

1992-01-01

The presence of hydrides is an important factor in assessing the potential for delayed hydride cracking in Zr-2.5Nb alloys, and consequently, the terminal solid solubility (TSS) of hydrogen in the material is an important parameter. In pure zirconium doped with hydrogen, the TSS is marked by a dissolution peak of internal friction on heating and a truncated precipitation peak associated with hydride nucleation on cooling. These phenomena occur only at low frequencies and are accompanied in torsion pendulum studies by autotwisting of the sample (or zero-point drift) that stops abruptly at the TSS. Neither the dissolution/precipitation peaks nor the autotwisting phenomena are observed in Zr-2.5Nb. However, the TSS is also marked by an abrupt change in the slope of Young's modulus as a function of temperature. This phenomenon is observed regardless of the frequency (in the range 1 Hz to 120 kHz) and in both pure zirconium and Zr-2.5Nb alloys. The reasons for the absence of the dissolution/precipitation peak in Zr-2.5Nb alloys are discussed and the use of Young's modulus changes to investigate the TSS of hydrogen and the hysteresis between heat-up and cool-down TSS curves is demonstrated. (author)