28 research outputs found

    Effect of Fe substitution for Cu on microstructure and magnetic properties of laser floating zone (LFZ) grown Bi-2212 rods

    Get PDF
    In this paper, the laser floating zone (LFZ) technique has been used to fabricate Bi2Sr2Ca1Cu2-x Fe x O (x=0,0.01,0.03,0.05,0.1) superconducting fibers. The effects of Fe substitution on grain alignment and superconducting properties of annealed fibers were studied using SEM/EDX microanalysis in addition to phase analysis and magnetic measurements realized through XRD, M-T, and M-H loops. In the same growth conditions, higher Fe contents lead to a more compact microstructure with lower porosity but also caused the formation of poor superconducting phases followed by the decrease of T c and J cmag. No evidence of enhanced pinning capability was found in the magnetic measurements. Annealed rods indicated a weakly ferromagnetic-like behavior at relatively high doping levels.This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) in the scope of 2214 International Doctoral Research Fellowship Program. A. Sotelo and M.A. Madre acknowledge MICINN-FEDER (Project MAT2008- 00429) and DGA (Consolidated research group T12) for financial support.Peer Reviewe

    Grain alignment and its relationship with superconductivity and thermal transport of Ni-substituted Bi-2212 textured rods fabricated at two different growth rates

    Get PDF
    The microstructure, grain alignment, superconducting and thermal transport properties of Ni-substituted Bi-2212 rods grown at two different speeds (15 and 30 mm h−1) through the Laser Floating Zone method, have been evaluated. Significant variations in grain size, grain alignment, electrical and thermoelectric power properties have been observed for the rods depending on the growth and substitution rates. The highest aligned structure was obtained on unsubstituted rods grown at 15 mm h−1. Both increased substitution and growth rates degraded the grain alignment. The presence of Ni-based secondary phases showed that Ni is not totally incorporated into the crystal structure, which, in turn, caused a decrease on the average grain size of the rods. With increasing Ni concentration, peak values of thermoelectric power of the rods, which lie between 3.8 and 6.4 μVK−1, monotonically decreased while thermal conductivity values did not show any systematic change. The activation energy of flux motion, Uo, was calculated from the field dependent resistivity–temperature curves in a range of 0–8 T. Superconducting transition temperatures, Tconset and Tcoffset, and activation energy, Uo, were found to decrease with increasing Ni contents and applied magnetic field. It has been estimated from the magnetic field dependence of activation energy of the samples that plastic creep of the collective vortices is dominant in the rods.This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under 2214 International Doctoral Research Fellowship Program (M. Ozabaci). A. Sotelo and M.A. Madre acknowledge DGA (Consolidated research group T12) for financial support. M. A. Madre acknowledges MINECO-FEDER (Project MAT2011-22719) for funding.Peer Reviewe

    Effectiveness of Schema Therapy on the Treatment of Depressive Disorders: A Meta-Analysis

    Get PDF
    The effectiveness of schema therapy in the treatment of depressive disorders was examined in this meta-analysis study. As a result of the literature review using various databases, a total of 35 studies which were carried out in 2007-2017 were reached, 7 of which included in this meta-analysis. For these 7 experimental studies, the country (culture), the type of depressive disorder, the number of participants, the number of sessions, the type of session (individual or group), the duration of the session (minute), and the whole session process (week) were determined as hypothetic moderator variables. The results of the analysis using the random effect model showed that schema therapy had a high level of efficacy in the treatment of depressive disorders. It had been determined that none of the hypothetic moderator variables had moderator functions

    Additive nonparametric regression in the presence of endogenous regressors

    Get PDF
    Ministry of Education, Singapore under its Academic Research Funding Tier

    Structural and superconducting properties of magnetically doped Bi-2212 textured rods grown by laser floating zone (LFZ) technique

    Get PDF
    In this work, we have applied the laser floating zone technique, a well-known method to produce highly aligned crystals and dense morphology, with improved transport properties, to obtain Bi2Sr2Ca1Cu2−x Ni x O (x=0, 0.01, 0.03, 0.05 and 0.1) fibers of about 1.8 mm diameter ×12 cm length. Microstructural and magnetic properties of textured materials grown in the optimum conditions were analyzed through scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX), powder XRD patterns, M–T and M–H loops. XRD analysis showed that addition of Ni at x=0.1 level caused the formation of small amounts of Bi-2201 phase. Thermal treatment has produced the agglomeration of Ni particles up to a few μm, detected by dot mapping EDX. Both T c-onset and J cmag values of the annealed rods decreased with the increasing Ni substitution rate, determined from the M–T and M–H loops, respectively.This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under 2214 International Doctoral Research Fellowship Program. A. Sotelo and M.A. Madre acknowledge MICINN-FEDER (Project MAT2008-00429) and DGA (Consolidated research group T12) for financial support.Peer Reviewe

    WP 2019-404

    Full text link
    When determining a claimant’s eligibility for Social Security Disability Insurance (SSDI) benefits, the Social Security Administration (SSA) assesses whether his/her health condition (e.g., back/spine problems) sufficiently impairs his/her functional capacity (e.g., ability to lift/carry weight) so that the he/she is unable to meet the requirements (e.g., need to lift/carry 25 pounds) of his/her previous occupation and other possible occupations. Using data from the Survey of Income and Program Participation (SIPP) and Occupational Requirements Survey (ORS), we compare the occupational requirements of workers with and without a given health condition in order to understand what to expect from claimants with that health condition. Although sample sizes are limiting and ORS data collection is not yet complete, we find some evidence that workers’ occupational requirements accommodate their health conditions. This evidence suggests that claimants with these health conditions may be able to fulfill the requirements in these occupations. We do find some evidence of the opposite causality: Workers may experience health conditions later in life from occupational requirements that may have caused their health conditions. This evidence is a caution against using data without onset information to inform claimant-ability expectations. Overall, this report provides evidence that national surveys with occupation, health, and function questions have the potential to inform revisions to the SSA disability determination process by providing information on people with health conditions who are working and meeting the requirements of a variety of occupations.U.S. Social Security Administration grant number RDR18000002, UM19-09https://deepblue.lib.umich.edu/bitstream/2027.42/152469/1/wp404.pdfDescription of wp404.pdf : Working pape

    Enhancement of magnetic relaxation behavior by texturing in Bi-2212 superconducting rods

    Get PDF
    Time decay of magnetization, known as magnetic relaxation, is crucial for both fundamental and applied point of view in bulk high temperature superconductors (HTS) by setting the limits to the HTS devices stability. Melt-processed BiSrCaCuGaO rods (Bi-2212, x=0, 0.1) were used to study the effect of both grain alignment and substitution on the samples critical current density, relaxation and pinning behavior. The magnetic field has been applied both perpendicular and parallel to the rods growth axis to determine the effect of grain alignment. It has been found that Ga substitution reduces grains orientation and sizes leading to lower magnetic properties. The peaks of the curves, which indicate the temperature dependence of the samples magnetic relaxation rate (S), have been observed in the 7-35 K temperature range. Characteristic pinning energy (U/k) of samples was determined using the formalism developed by Maley. The change of pinning energy as a function of magnetization has been found to be exponential between 3 and 60 K, which is in agreement with the collective creep theory.Peer Reviewe

    Structural, magnetic and electrical properties of magnetically doped Bi -2212 textured rods grown by laser floating zone (LFZ) technique

    No full text
    Resumen del trabajo presentado a la: "3rd International Conference on Superconductivity and Magnetism" celebrada en Estambul (Turquia) del 29 de abril al 4 de mayo de 2012.In this work, we have applied laser floating zone technique, a well -known way of fabricating crystals having highly-aligned dense morphology with improved transport properties, to obtain Bi2Sr2Ca1Cu2-xNixO (x=0, 0.01, 0.03, 0.05 and 0.1) fibers of size 1.8 mm diameter x 12 cm length. Microstructural, magnetic and electrical properties of fibers, grown with optimum growth conditions, were analyzed through scanning electron microscope (SEM), energy dispersive x-ray analysis (EDX), XRD patterns, R-T, I-V, M-T and M-H loops. In SEM/EDX and XRD measurements, it couldn’t be possible to find phases belong to Ni especially for low doping rates. On the other hand, Ni doping caused some negative effects regarding the magnetic properties of fibers.Peer reviewe

    Effects of Fe doping on microstructure and superconducting properties of laser floating zone (LFZ) grown Bi-2212 rods

    No full text
    Resumen del trabajo presentado a la: "3rd International Conference on Superconductivity and Magnetism" celebrada en Estambul (Turquia) del 29 de abril al 4 de mayo de 2012.In this paper, we have produced the highly-aligned Bi2Sr2Ca1Cu2-xFexO superconducting fibers by laser floating zone (LFZ) technique containing Nd:YAG laser beam with 1064 nm wavelength as a continuous power source for x = 0, 0.01, 0.03, 0.05 and 0.1 doping rates. The effects of iron doping on the grain alignment and superconducting properties of fibers were investigated by the detailed scanning electron microscopy and energy dispersive spectroscopy microanalysis from both the as-grown and annealed rods with 1.5-2 mm in diameter and up to 15 cm in length. In addition to these investigations phase studies, electrical and magnetic measurements were realized through XRD, R-T, M-T and M-H loops. At the same time, magnetization of fibers was studied with the magnetic fields applied from different axes. With the same growth conditions, increasing doping rate degraded the texturing level and also magnetic properties of samples.Peer reviewe
    corecore