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Well-textured BiSrCaCuO/2.9 wt % Ag composite samples have been grown by the laser floating zone at very low rates (1, 3, and 5 mm/h). The as-grown samples present superconducting behavior, as a result of being composed by long and well-textured Bi-2212 grains as major phase. After annealing, the samples do not dramatically increase their J. This effect has been associated with the presence of long cracks along the ab planes of the superconducting grains. Even after annealing, the cracks have not been totally removed and, as a consequence, the critical current of the samples after the thermal treatment has only been improved in around 50 %, compared with the as-grown samples. [ABSTRACT FROM AUTHOR]

CaCoTiO polycrystalline thermoelectric ceramics with small amounts of Ti have been prepared by the classical solid state method. X-ray diffraction data have shown that CaCoO is the major phase, with small amounts of the CaCoO one. Moreover, they show that Ti has been incorporated into these two phases. Electrical resistivity decreases, compared with the values for undoped samples, until 0.03-Ti doped ones. Further Ti addition produces an increase of resistivity with respect to the 0.03 Ti doped samples. Seebeck coefficient does not appreciably change in all the measured temperature range, independently of Ti content. The improvement in electrical resistivity leads to about 55 % higher power factor values for the 0.03 Ti-doped samples than that obtained in the undoped ones. The maximum power factor at 800 °C, around 0.33 mW/K m, is slightly higher than the obtained in higher density samples, clearly indicating the good thermoelectric performances of these doped samples. [ABSTRACT FROM AUTHOR]

Fe-substituted superconducting thin BiSrCaCuO rods with nominal compositions of BiSrCaCuFeO ( x = 0, 0.01, 0.03, 0.05, and 0.1) were fabricated using the laser floating zone technique at two different growth speeds, 15 mm h and 30 mm h. The influences of growth speed and Fe substitution on the grain alignment in the rods were evaluated by means of x-ray pole figure studies. The obtained results showed that both applied growth speed and Fe substitution play a crucial role on grain alignment, which is strongly connected with the current-carrying capacity of the rods. It was found that the rods grown at 15 mm h (G15) have stronger orientation than the rods grown at 30 mm h (G30). However, in contrast to the G15 rods, an increased substitution rate improved the orientation of the G30 rods. Another important observation is that the increase on the substitution caused a decrease on the grain size of all the rods. The decrease of critical temperature values of the rods upon substitution was ascribed to both grain size effect and formation of a nonsuperconducting Fe-rich phase detected in scanning electron microscope/energy-dispersive x-ray analyses. The thermal conductivity values of the G15 and G30 rods were found to be in the range of 0.9-1.9 and 1.1-1.18 W m K at 150 K, respectively. The higher values of figure of merit ( ZT), at all temperature ranges, were obtained from the highest substituted rods ( x = 0.1) for both of the applied growth speeds. In addition, it was observed that the ZT of G30 rods are up to three times higher than that of G15 ones. [ABSTRACT FROM AUTHOR]

In this study, the effect of Na substitution on the structural, electrical and magnetic properties of BiSrCaNaCuO superconductor with x = 0.0, 0.05, 0.075, 0.1, 0.15, and 0.2 has been investigated. The effects of partial replacement of Na for Ca have been investigated by electrical resistivity ( ρ- T), scanning electron microscopy (SEM), X-ray diffraction (XRD), and magnetic characterizations. XRD results have shown that the Bi-(2212) phase is the major one independently of the Na-concentration. SEM results indicate that the microstructure of samples is improved with increasing of Na-contents. From the electrical resistivity measurements it has been found that Tc is slightly higher than 92 K for Na-concentrations up to 0.20. Moreover, this trend is maintained in the magnetic measurements where the hysteresis loops are increased with increasing Na-concentrations. The maximum calculated Jc, using Bean's model, is around 10 × 10 A/cm at 10 K and ~1,000 Oe for the 0.075 Na doped samples. [ABSTRACT FROM AUTHOR]

In this work, the effect of K in the BiSrCaKCuO superconductor with x = 0.0, 0.05, 0.075, and 0.1, has been investigated. The samples were prepared by a polymer solution technique using polyethyleneimine, PEI. The effects of K substitution have been investigated by electrical resistivity ( ρ− T), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, and magnetic characterizations. SEM and XRD results have shown that the Bi-(2212) phase is the major one independently of the K concentration. Moreover, the microstructure of samples is improved with K-concentration up to x = 0.075. From electrical resistivity measurements we have found that Tc is slightly higher than 91 K for K-concentrations up to 0.075, and then it decreases for higher doping for about 0.5 K. Moreover, this trend is maintained in the magnetic measurements in which the hysteresis loops are increased until 0.075 K-concentrations. The maximum calculated Jc, using Bean's model, has been found at around 4.5 10A/cm at 10 K and ~1,000 Oe for the 0.05 K doped samples. [ABSTRACT FROM AUTHOR]

CaCoZnO (x = 0.01, 0.03, and 0.05) polycrystalline thermoelectric ceramics have been prepared by the classical solid state method. XRD data have shown that CaCoO is the major phase, with small amounts of the CaCoO one. Moreover, it has been found that the Zn has been incorporated into these two phases. Slight Zn doping decreases electrical resistivity compared with the values obtained in undoped samples. The minimum values have been obtained for the 0.01-Ni doped samples, increasing for further Zn substitution. Seebeck coefficient does not appreciably change in all the measured temperature range, independently of Zn content. The improvement in electrical resistivity leads to higher power factor values for the 0.01 Zn-doped samples (about 30 %) than for the undoped ones. The maximum power factor at 800 °C, around 0.27 mW/K m is significantly higher than the best results obtained in Zn doped samples reported in the literature. [ABSTRACT FROM AUTHOR]

CaRECoO thermoelectric ceramics with different rare earth (RE = Dy, Er, Gd, and Tb) substitution for Ca have been successfully produced by the classical solid state method. All these rare earths in small proportions produce the same effects on the thermoelectric phase, reflected on a similar and significant decrease of the electrical resistivity, compared with the undoped samples. The Seebeck coefficient slightly decreases with all the studied substitutions while the power factor values appreciably increase at high temperatures for small amounts (0.01) of doping elements. Further doping produces the decrease of power factor which indicates that the optimal doping level has been determined to be 0.01 for all the tested rare earths which produces, approximately, the same improvement, around 20 % of the power factor obtained in the undoped samples at 800 °C. [ABSTRACT FROM AUTHOR]

In this study, the effect of Ce doping on the properties of BiSrCaCeCuO ceramic superconductors, with x=0.0, 0.01, 0.05, 0.1, and 0.25, has been investigated. Samples' precursors were prepared using the conventional solid state method and subsequently textured using the Laser Floating Zone technique. The magnetoresistance measurements were studied under various applied magnetic fields. The activation energies, irreversibility fields ( H), upper critical fields ( H) and coherence lengths at 0 K ( ξ(0)) were calculated from the resistivity versus temperature ( ρ- T) curves, under DC magnetic fields up to 5 T. The thermally activated flux flow model has been applied in order to calculate the flux pinning energies. The results indicated that H(0) varied from 416.19 to 115 T and the flux pinning energies varied from 1.46 to 0.042 eV at 0 T. [ABSTRACT FROM AUTHOR]

CaNdCoO polycrystalline thermoelectric ceramics with small amounts of Nd have been synthesized by the classical solid state method. X-ray diffraction data have shown that all the Nd has been incorporated into the CaCoO and CaCoO phases and no Nd-containing secondary phases have been produced. Apparent density measurements have revealed that all samples are very similar, with densities around 70 % of the theoretical one. Electrical resistivity decreases in all Nd-doped samples, compared with the pure one, while Seebeck coefficient remains constant for all samples. The improvement in resistivity leads to higher power factor values than the obtained for the undoped samples. [ABSTRACT FROM AUTHOR]

In this work, BiSrCaCuCoO ( x=0.0, 0.05, 0.10, and 0.25) textured superconductors were prepared by a LFZ melting technique. In all cases, the powder X-ray diffraction patterns of samples show that the Bi-2212 phase is the major one. All samples have good oriented structure, which is a typical picture for superconductors prepared by the LFZ method. Magnetization hysteresis loops, made for all samples at two different temperatures, showed that the loops become narrower with increasing temperature and doping levels. In addition, the effect of Co doping on the critical current density, J, of BiSrCaCuCoO has been estimated from hysteresis loop measurement by using Bean's model. The increase of the Co amount in the BiSrCaCuCoO structure significantly decreases the critical current density, showing worse connectivity of the grains. All the results indicate that Co substitution for Cu produces the deterioration on the superconducting properties, compared with the undoped samples. [ABSTRACT FROM AUTHOR]

Thermoelectric ceramics are based in a limited number of transition metal oxides (Co, Mn, Ni,...) which produce materials with high thermoelectric performances. Based on previously existing thermoelectric phases, the phase diagram equilibrium can help to design new thermoelectric ceramics based on other transition metals (for example, Fe). In this work, BaFeO ceramics have been prepared by the classical solid state method using different sintering temperatures. The produced materials have shown promising thermoelectric properties when treatment temperatures are in the perovskite zone domain of the phase equilibrium diagram. In spite of the good values for the Seebeck coefficients, power factor is low due to the high resistivities measured in all cases. [ABSTRACT FROM AUTHOR]

In this study, BiSrCaCeCuO, where x = 0, 0.01, 0.05, 0.1 and 0.25, superconducting samples were prepared by solid state method and subsequently used as feed in a laser induced directional solidification (LFZ) process. The physical properties of the samples were investigated by powder X-ray diffraction, scanning electron microscopy, dc-electrical resistance, magnetization, and magnetic-hysteresis loops measurements. It has been found that no significant difference has been observed in the critical transition temperatures of samples except for the sample with the highest Ce additions, which shows the lowest T compared with the other doped samples. Magnetic hysteresis measurements have shown that the hysteresis loop is greater than the doped samples. In addition, critical current density values obtained from the hysteresis loops measurements by using Bean's critical state model show a decrease with Ce-addition. All the results indicate that Cerium substitution for Ca produces the deterioration on the superconducting properties, compared with the undoped sample. [ABSTRACT FROM AUTHOR]

Bi-2212 samples prepared by the classical solid-state method have been grown from the melt using the Laser Floating Zone (LFZ) method. They have shown good grain alignment and transport critical current densities ( J). After postannealing processes designed to produce the Bi-2212 phase controlled decomposition, J values have been increased in an important manner. Maximum values have been achieved when samples were thermally treated at 680 °C for 168 h with improvements around 80 %, compared with the original textured samples. The results clearly indicate that postannealing processes, when adequately controlled, produce the formation of effective pinning centers which are responsible for the increase in the measured J values. [ABSTRACT FROM AUTHOR]

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 BiSrCaCuNiO ( 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 and J values of the annealed rods decreased with the increasing Ni substitution rate, determined from the M- T and M- H loops, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the measured magnetic properties of BiSrCaCuO/3 wt.% Ag textured composite materials prepared by a LFZ melting technique at different growth speeds (5, 15, 30, and 60 mm/h) are presented. X-ray diffraction patterns have shown that Bi-2212 phase is the major one in all cases. The magnetization measurements have been carried out as a function of the magnetic field up to 10 kOe. J values, calculated using Bean's model, indicate that the growth speeds have a significant effect on J. It has been found that the maximum critical current density, 4.42×10 A/cm at 10 K, has been obtained for the 15 mm/h grown sample. [ABSTRACT FROM AUTHOR]

In this study, we report the physical and magnetic properties of BiSrCaCuO textured materials prepared by a LFZ melting technique and annealed for different times (60, 72, 96 and 120 h). SEM images of the annealed samples for 96 and 120 hours indicate very good alignment with the longitudinal rod axis. In all cases, X-ray diffraction patterns show that the Bi-2212 phase is the major one. The magnetization measurements have been carried out as a function of the magnetic field up to 9 kOe. J values of the samples were calculated by using the Bean model. The results indicate that the different annealing time has no significant effects on the T values but, significant change on the critical current values of samples, J, has been obtained for sample annealed at 96 hours. We also found that the maximum critical density of J is 5.5×10 A/cm at 10 K for the 96 hours annealed sample. [ABSTRACT FROM AUTHOR]

It is well know that HO and CO (both present in the atmosphere) can react chemically with BSCCO superconductors, especially with the alkaline-earth cations, producing chemical degradation and reducing their performances. In this work, Bi-2212 highly textured rods were grown from the melt through a laser floating zone melting technique. In order to determine the influence of HO and CO on these bulk textured samples, they were immersed in distilled water and in CO saturated water. The evolution of the electrical and mechanical properties of these rods was determined as a function of the immersion time in both media and compared with their initial properties. It has been found that performance degradation was higher in distilled water than in CO saturated one. Nevertheless, in any case, the degradation has been found to be not very important. [ABSTRACT FROM AUTHOR]

In this paper, the laser floating zone (LFZ) technique has been used to fabricate BiSrCaCuFeO ( 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 and J. 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. [ABSTRACT FROM AUTHOR]

Bi-2212/Ag superconducting ceramics were grown using the electrically assisted laser floating zone (EALFZ) technique. The main goal was improving the superconducting properties by applying an electrical current through the sample during the solidification process. The effect of a 100 mA current intensities in two configurations were studied: (i) direct current (connecting the seed rod to the positive pole and the feed to the negative one) and (ii) reverse current (positive pole connected to the feed rod and negative to the seed one). The resulting textured cylindrical bars were annealed in order to obtain the superconducting phases. A strong correlation between current polarity, grain alignment and superconducting properties was observed. The rods grown under direct current exhibit higher critical current density (∼3000 A/cm) than the ones grown under conventional method (∼2300 A/cm) or under reverse current condition (∼35 A/cm). The superior value obtained for the direct current results from a better grain alignment and fewer amount of second phases. [ABSTRACT FROM AUTHOR]

The effect of MoO addition on the properties of Bi-2212 superconducting ceramic samples prepared by solid state reaction method has been investigated. Mo content was varied from 0 to 0.25 on a general stoichiometric formula BiSrMoCaCuO. Electrical resistivity showed that transition temperature width increased directly with the Mo amount. XRD data have shown that MoO addition in the BiSrMoCaCuO precursor reduces the amount of Bi-2212 phase. In addition, J values of the samples, calculated from the hysteresis loops using the Bean's model, decreased with increasing Mo substitution. Vickers microhardness measurements show that samples are very sensitive to Mo content and applied load. In addition, various models like Meyer's Law and Young's Modulus equations have been used to better explain the mechanical properties of samples. [ABSTRACT FROM AUTHOR]

BackgroundSchizo-affective disorder has not been studied to any significant extent using functional imaging. The aim of this study was to examine patterns of brain activation and deactivation in patients meeting strict diagnostic criteria for the disorder.MethodThirty-two patients meeting Research Diagnostic Criteria (RDC) for schizo-affective disorder (16 schizomanic and 16 schizodepressive) and 32 matched healthy controls underwent functional magnetic resonance imaging (fMRI) during performance of the n-back task. Linear models were used to obtain maps of activations and deactivations in the groups.ResultsControls showed activation in a network of frontal and other areas and also deactivation in the medial frontal cortex, the precuneus and the parietal cortex. Schizo-affective patients activated significantly less in prefrontal, parietal and temporal regions than the controls, and also showed failure of deactivation in the medial frontal cortex. When task performance was controlled for, the reduced activation in the dorsolateral prefrontal cortex (DLPFC) and the failure of deactivation of the medial frontal cortex remained significant.ConclusionsSchizo-affective disorder shows a similar pattern of reduced frontal activation to schizophrenia. The disorder is also characterized by failure of deactivation suggestive of default mode network dysfunction. [ABSTRACT FROM AUTHOR]

In this study, samples with nominal composition of BiSrCaCuYbO, where x=0.0, 0.05, 0.1 and 0.25, have been textured using the Laser Floating Zone technique. The effects of different Yb doping on the structure have been investigated by electrical resistivity, scanning electron microscopy, XRD, mechanical and dc-magnetization techniques. It has been found that with increasing Yb doping for Cu, the physical and superconducting properties of structure gradually decrease. J values, calculated using the Bean's model, significantly change, although T is approximately the same for all samples. [ABSTRACT FROM AUTHOR]

Transport properties on Bi-2212 superconductors can be improved by grain orientation methods while mechanical ones can be tuned up by the addition of metallic silver. Both processes can be performed simultaneously using the Laser Floating Zone (LFZ) method. In this work, BiSrCaCuO/3 wt.%Ag textured composite materials were prepared by a LFZ melting technique at different growth speeds (5, 15, 30, and 60 mm/h). In all cases, the observed microstructure after annealing shows the Bi-2212 phase as the major one. Although growth speed has no effect on the measured T values, a drastic change on the J values has been found. The best results, both mechanical and transport properties, have been obtained for samples grown at 15 mm/h. [ABSTRACT FROM AUTHOR]

Several synthetic methods, solid-state, sol-gel and polymer solution methods, have been used to prepare prereacted precursors, as well as a vitreous material obtained by melt quenching. The influence of the starting powder characteristics on the phase formation, microstructure, T and J of Bi-2212 textured rods prepared by directional crystallization from the melt has been analyzed. In all the cases, high transport critical current values (higher than 3000 A/cm at 77 K) have been obtained, independently of the precursor type. Samples obtained by the polymer route show improved T values, associated to a lower oxygen content. [ABSTRACT FROM AUTHOR]

In this work, superconducting samples of (Bi1.6Pb0.4)Sr2CaCu2O8+δ+3 wt.%Ag have been studied and compared with Ag free samples, (Bi1.6Pb0.4)Sr2CaCu2O8+δ, and with Ag and Pb free ones, Bi2Sr2CaCu2O8+δ. It has been found that Pb doped samples present a worse texture when compared with the undoped ones, resulting in a drastic change on the microstructure. The results showed that electrical resistivity at room temperature, critical current as well as flexural strength are decreasing for the Pb doped samples. When Ag is added to these Pb doped samples, all the properties are improved even if they do not reach the same values as the undoped ones. On the other hand, it has been found that Pb doped samples showed E–I curves with very high sharpness values on the zone of the superconducting to normal transition, reaching n values (E∼In) as high as 45 at 65 K, for samples with simultaneous Pb and Ag additions. [ABSTRACT FROM AUTHOR]

The article discusses a study on the synthesis and characterization of Bi-based misfit cobaltite rods. It notes that the Laser Floating Zone method was used in processing the specimens in air. It cites that the research determined the electrical resistivity (p) of directionally solidified rods and correlated with the textural and microstructural features.

Introduction. Psychomotor agitation is a common event in psychiatric emergency services (PES) with a prevalence of approximately 10 %. There is no general consensus on to how to manage psychomotor agitation; benzodiazepines, typical antipsychotics and now atypical antipsychotics have demonstrated similar efficacy. The aim of our study was to describe the epidemiology and clinical management of agitation in «real-life» in a psychiatric emergency service. Methods. A naturalistic study was performed in acutely agitated patients recruited consecutively in a psychiatric emergency service. Demographics, clinical and therapeutic characteristics were analyzed. Efficacy was assessed by the Excitement Component of the Positive and Negative Syndrome Scale (PANSS-EC) and the Agitation-Calmness Evaluation Scale (ACES). Pragmatic variables such as the need for second pharmacological intervention and the need for physical restraints were assessed. Results. The study included 100 patients with psychomotor agitation. Mean age was 36.2 % and 54% were women. The most prevalent diagnoses were psychotic disorder (48 %) and personality disorder (24 %). Physical restraint was required in 39 % of patients and 52 % accepted oral treatment. Haloperidol was the most frequent oral treatment and olanzapine was the most frequent intramuscular treatment. Conclusions. A naturalistic approach provides data based on clinical reality in psychiatric emergency services. Strict research designs of clinical trials of efficacy imply sample selection biases and are generally distanced from the clinical reality. Atypical antipsychotics have become the first-line treatment in acute agitation. [ABSTRACT FROM AUTHOR]

S-A ikylation of 2-acetam ido-9- (2-acetoxyethoxymethyl)- 6-oxo-8th ioxopurine was used to synthesize its novel S- and N(7)-substituted derivatives. We have established the effect of the structure of the alkylating agent on the reaction conditions and its regioselectivity. We have shown that the synthesized guanine derivatives can be modified further. [ABSTRACT FROM AUTHOR]

Bi2Sr2Ca1Cu1.75Na0.25Oy ceramics have been prepared by the classical solid state reaction method followed by hot-pressing process under several applied pressures and temperatures: 22 and 33 MPa at 750 °C, and 22 MPa at 800 °C. X-ray diffraction data indicate that the major phase in all samples is the Bi2Sr2Ca1Cu1.75Na0.25Oy phase, accompanied by small amounts of Bi2CaO4 and Bi3Sr4CaCu3O4 secondary phases. Microstructural results clearly showed that the best grain orientation has been obtained under 33 MPa at 750 °C. Critical temperatures, TC (onset) and TC (offset), of these samples were significantly increased to 96.6 and 85.6 K, respectively, pointing out to a good intergranular coupling. M-H hysteresis curves for all samples display a very large area due to the microstructural characteristics obtained in these samples. The highest critical current density, calculated from M-H measurements according to Bean's model, has been obtained in samples prepared under 33 MPa at 750 °C (201.5 × 104 A/cm2 at 1.9 T and 15 K), which are much larger than those reported for samples with the same composition prepared through the classical solid state method. [ABSTRACT FROM AUTHOR]