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Objective Brain structural changes in schizoaffective disorder, and how far they resemble those seen in schizophrenia and bipolar disorder, have only been studied to a limited extent. Method Forty-five patients meeting DSM- IV and RDC criteria for schizoaffective disorder, groups of patients with 45 matched schizophrenia and bipolar disorder, and 45 matched healthy controls were examined using voxel-based morphometry ( VBM). Results Analyses comparing each patient group with the healthy control subjects found that the patients with schizoaffective disorder and the patients with schizophrenia showed widespread and overlapping areas of significant volume reduction, but the patients with bipolar disorder did not. A subsequent analysis compared the combined group of patients with the controls followed by extraction of clusters. In regions where the patients differed significantly from the controls, no significant differences in mean volume between patients with schizoaffective disorder and patients with schizophrenia in any of five regions of volume reduction were found, but mean volumes in the patients with bipolar disorder were significantly smaller in three of five. Conclusion The findings provide evidence that, in terms of structural gray matter brain abnormality, schizoaffective disorder resembles schizophrenia more than bipolar disorder. [ABSTRACT FROM AUTHOR]

Bi-2212 samples prepared by a solid-state reaction technique have been grown from the melt using the laser floating zone method. After annealing the as-grown bars, the samples showed a good grain alignment and a high transport critical current density. Secondary annealing processes were performed on the annealed samples with the aim of producing Bi-2212 phase controlled decomposition. Hence, the Bi-2201 phase and the secondary phases, which act as effective pinning centers, were obtained with the secondary annealing process. After these thermal treatments, the transport critical current densities of samples significantly increased, when compared to the annealed ones. The maximum critical current density was achieved when the samples were subjected to secondary annealing at 680°C for 168 h with an improvement of ~80%, compared to the annealed ones. Moreover, it was found that magnetization of the secondarily annealed samples was also increased. The magnetic critical current densities in these secondary annealed samples were about 3 times higher than the values obtained for the annealed ones. These results clearly indicate that the secondary annealing processes lead to the formation of effective pinning centers in the bulk material. [ABSTRACT FROM AUTHOR]

In the present study, thermal conductivity ( κ − T), thermoelectric power ( S − T), and figure of merit (ZT) measurements from room temperature down to 20 K of polycrystalline BiSrCaNaCuO and BiSrCaKCuO superconductors prepared by a polymer solution technique using polyethyleneimine, PEI, have been carried out. The thermoelectric power, S( T), of samples have both negative (at high T) and positive values (at low T), and are found to increase with decreasing temperature, reaching their maximum values (peaks) around their T values and dropping rapidly to zero below T. Na and K substitutions also have a considerable effect on the thermal conductivity, κ. Namely, with increasing Na concentration the magnitude of κ is decreased, but for the K substitution, the magnitude of κ is drastically increased for x = 0.75. [ABSTRACT FROM AUTHOR]

In this study, Na-substituted BiSrCaNa CuO superconductor samples were prepared by a polymer solution method. Three different sintering temperatures (850, 860, and 870 °C) were used to study the effect of Na substitution. The samples have been characterized using X-ray diffraction, scanning electron microscopy (SEM), DC electrical resistivity, and DC magnetic measurements. Magnetoresistivity measurements have shown a broadening of the superconducting transition under magnetic field which is explained on the basis of the thermally activated flux flow (TAFF) model. The calculated flux pinning energies of the samples varied from 0.17 to 0.02 eV by means of increasing magnetic field 0 to 9 T. The upper critical magnetic field H(0) and the coherence length ( ζ(0)) at T = 0 K were calculated using the resistivity data. H(0) and ξ(0) values have been calculated as 194, 144, and 139 T and 15.5, 15.2, and 13 Å at 850, 860, and 870 °C, respectively. TAFF model has shown BiSrCaNaCuO flux pinning energies are 0.015 eV at 9 T in all cases, while they were 0.165, 0153, and 0.149 eV at 0 T for samples sintered at 850, 860, and 870 °C, respectively. [ABSTRACT FROM AUTHOR]

BiSrCoO ceramics have been synthesized through solid-state reaction methods and directionally grown from the melt by laser floating zone technique. Mechanical and thermoelectric characteristics of this material were determined by three point bending tests and the four probe technique, respectively. The mechanical and thermoelectric properties of BiSrCoO were determined as a function of the environmental conditions, air and water. Flexural strength data show that textured materials possess a high degradation resistance due to the low porosity of the external part of the rods (~65 µm), which avoids water infiltration and, as a consequence, the internal degradation. Moreover, power factor values are maintained practically unchanged for the samples immersed in water for 24 h. [ABSTRACT FROM AUTHOR]

BiPbSrCaCuO ( x = 0.0, 0.3, 0.4, and 0.5) textured materials have been prepared by the laser floating zone technique. The E − I curves showed and increase of the slope of the normal to superconducting transition with Pb addition. The best values have been obtained for the 0.4 Pb-doped samples, around 16 at 77 K. In spite of this improvement, Pb addition decreased J and T in all cases. On the other hand, electrical characterization at lower temperatures has led to an impressive raise in the 0.4 Pb-doped samples, reaching n values around 31, and J of about 3,000 A/cm , at 65 K. At the same time, the mechanical integrity of the vitreous precursor materials has been determined. All the obtained results clearly indicate that these precursors, when properly processed by the laser floating technique, are promising candidates for practical applications as current limiters. [ABSTRACT FROM AUTHOR]

In the present work, magnetoresistivity performance of polycrystalline BiSrCa KCu O superconductor with x=0.0,0.05,0.075, and 0.1 has been studied by change of flux pinning mechanism, using magnetoresistivity measurements. The samples were prepared using a polymer solution technique. The effects of K substitution for Ca on the irreversibility field, upper critical magnetic field, coherence length, and activation energies have been investigated. The magnetoresistivity of the samples has been measured under applied magnetic fields ranging from 0 to 9 T. Broadening of superconducting transition is observed under magnetic field, explained on the basis of thermally activated flux flow (TAFF) model. The upper critical magnetic field H(0) and the coherence length ( ζ(0)) at T = 0 K were calculated using the resistivity data and from H(0) ,respectively. H(0) and ξ(0) values have been calculated as 62, 72, 75, and 53 T and 23, 21, 20, and 25 Å for the 0.0, 0.05, 0.075, and 0.10 K doped samples, respectively. TAFF model has been studied in order to calculate the flux pinning energies. In particular, the flux pinning energies of BiSrCa KCu O where x = 0.075 are calculated as 0.0147 eV for 9 T and 0.29 eV for 0 T. [ABSTRACT FROM AUTHOR]