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Abstract  

Sol-gel process was employed to synthesize the Pb-BSCCO system having general composition Bi2−xPbxSr2Ca2Cu3O10−δ, where x=0.2, 0.4 and 0.8. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), dilatometry and vibrating sample magnetometer (VSM) were employed to study the materials produced at different stages. Two-stage heating firstly at 300 and then 800°C was adopted in order to avoid the burning of the materials and formation of carbonates. The carbonate formation was avoided by heating the materials firstly at 300°C for 2 h and without intermediate cooling moved to the furnace having temperature 800°C and hold for 2 h. The sintering behaviour of samples was studied by dilatometry and the results revealed that the sample having x=0.4 was stabled up to a temperature of 700°C while samples having x=0.2 and 0.8 to a temperature of 625°C. The maximum shrinkage was observed at 850°C in all the samples. On the basis of dilatometry results, the samples were sintered at 845°C for 60 h to observe the superconducting phases. The highest volume fraction of high superconducting phase (2223) was noticed in the sample containing x=0.4 having onset T c=110 K.

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Abstract  

Sol–gel auto combustion process was employed to synthesize nanosized Mn–Zn ferrite at different pH values (<1, 5, 6, 7, 8 and 10). Although self propagating combustion behavior of gel was noted at pH 5 but more effective combustion was observed at pH 6. The smoldering effect was observed in gel prepared at pH 7, 8 and 10, whereas pH < 1 showed localized burning. Thermogravimetric (TG) and X-ray diffraction (XRD) analyses were done to investigate the effect of pH on the combustion behavior, particle size and the formation of desired magnetic (spinel) phase. From TG curves of burnt powders, activation energy of ignition reaction at each pH value was calculated. The results showed that fuel to oxidant ratio and the amount of gel residuals decided the value of activation energy required to further purify the burnt powders. Calcination parameters (time and temperature in air) of powders P1 and P6 synthesized at pH < 1 and pH 6 were also determined. B–H loop results showed that calcined powder C6 was more ferromagnetic than C1 due to fully developed spinel phase and larger particle size.

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Abstract  

The objective of present research was to sinter nanosized Mn–Zn ferrites (MZF) at low temperature (≤1,000 °C) by avoiding the formation of nonmagnetic phase (hematite). For this purpose, MZF powder was synthesized by sol–gel auto combustion process at 220 °C and further calcined at 450 °C. In calcined powder, single phase (spinel) was confirmed by X-ray diffraction analysis. Pellets were pressed, having 43% of the theoretical density and showing 47 emu gm−1 saturation magnetization (M s). Various combinations of heating rate, dwelling time and gaseous environment were employed to meet optimum sintering conditions at low temperature (≤1,000 °C). It was observed that sintering under air or N2 alone had failed to prevent the formation of nonmagnetic (hematite) phase. However, hematite phase can be suppressed by retaining the green compacts at 1,000 °C for 180 min in air then further kept for 120 min in nitrogen. Under these conditions, spinel phase (comprising of nano crystallites), 90% of theoretical density and 102 emu gm−1 of saturation magnetization has been achieved.

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thermally decomposed to give a powder that was later characterized using X-ray diffractometer (XRD), SEM, and vibrating sample magnetometer (VSM). TG curves were also obtained for the annealed powders. Stoichiometry of all the annealed powders was confirmed

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, Chandrasekaran , G . 2008 . Sol–gel route of synthesis of nanoparticles of MgFe 2 O 4 and XRD, FTIR and VSM study . J Magn Magn Mater . 320 : 2774 – 2779 10.1016/j.jmmm.2008.06.012 . 14. Huang

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Summary

Profiles of volatile secondary metabolites (VSM) in Mediterranean and Continental Festuca arundinacea, either endophyte free or infected with the fungal endophyte Neotyphodium coenophialum strain AR542, were determined using gas chromatography-mass spectrometry (GC-MS). The profile of VSM in the endophyte-free Mediterranean F. arundinacea germplasm was similar to that of endophyte-free Continental F. arundinacea germplasm. However, the VSM profile in AR542-infected Mediterranean F. arundinacea was different to that in AR542-infected Continental F. arundinacea. Compound 1, identified as N-acetylnorloline, was detected in AR542-infected Mediterranean F. arundinacea as being sevenfold greater compared with its level in AR542-infected Continental F. arundinacea. Levels of compounds 2, 4, and 5 detected in AR542-infected Mediterranean F. arundinacea were significantly lower when compared with their levels in the AR542-infected Continental F. arundinacea. Levels of compound 3 were similar in both germplasms infected with endophyte strain AR542. The levels of compounds 2, 4, and 5 but not compound 3 were different between AR542 infected and endophyte free depending on germplasm. On the basis of the mass spectra obtained, compounds 2, 3, 4, and 5 were identified as tridecanoic acid methyl ester, n-capric acid, 11, 14, 17-eicosatrienoic acid, and linoleic acid ethyl ester, respectively. Our results highlight key differences between the Mediterranean and Continental germplasms. Comparison of the VSM of AR542-infected Mediterranean F. arundinacea with AR542-infected Continental F. arundinacea showed that there are quantitative differences between the two germplasms. These differences, which may impact on grazing systems involving horses, most probably arose as a result of intrinsic genetic differences between the two germplasms and are yet to be indentified.

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Abstract  

The high T C superconducting phase Bi2Sr2Ca2Cu3Ox (2223) in the Pb-BSCCO system has been produced by EDTA-gel processing using nitrate solutions. The precursor has heated in two stages, at 300 and 800C each for 2 h, to avoid the burning of the important species involved in the final product. The effects of time (6 to 48 h) and temperature (845 and 855C) on the formation of the 2223 phase have been studied by sintering the samples in air. Thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and a vibrating sample magnetometer (VSM) have been employed to investigate the powder produced at different stages of decomposition, oxidation and formation of sintered materials from the powders. The volume-fraction of the 2223 phase at 845C increases with time, the maximum value of the 2223 phase was obtained at 120 h. It has been observed that the formation of the high T C phase is remarkably enhanced at the temperature of the endothermic peak of the DTA curve. The best result has been obtained in the sample sintered for 24 h at the temperature 855C (endothermic peak). This also indicated that at 855C, the large volume-fraction of 2223 phase with T C 113 K grew in short time and as the sintering time increased, it decomposed into the Bi2Sr2CaCu2Ox (2212) phase and other phases.

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Abstract  

The production of bulk high T c superconducting phase (2223) by EDTA-gel (ethylenediaminetetraacetic acid) techniques has been investigated. It is shown that close control of pH is necessary for the production of a well-complexed precursor which allows subsequent decomposition in two stages at 300 and 800�C. The problem of carbonate formation was investigated experimentally and solved. Precursors are characterised by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) and the sintering behaviour was monitored by dilatometry. At least three different phases Bi2Sr2Cax−1CuxO8+y (BSCCO); where x=1, 2, 3 were identified within superconducting pellets using XRD, named as Bi2Sr2CuO7 (2201), Bi2Sr2CaCu2O9 (2212) and Bi2Sr2Ca3O10 (2223). The superconducting properties of the sintered samples were studied by vibrating sample magnetometer (VSM). Transition to a superconducting state around 80 K appeared in samples (sintered at 845�C) containing the Bi2Sr2Ca1Cu2Oy (2212) phase. Liquid phase sintering of the samples aided the formation of Bi2Sr2Ca2Cu3Ox (2223) phase at high temperature (860�C), which showed a superconducting transition temperature of 108 K.

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Abstract

The precursor of nanocrystalline BiFeO3 was obtained by solid-state reaction at low heat using Bi(NO3)3·5H2O, FeSO4·7H2O, and Na2CO3·10H2O as raw materials. The nanocrystalline BiFeO3 was obtained by calcining the precursor. The precursor and its calcined products were characterized by differential scanning calorimetry (DSC), Fourier transform-infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The data showed that highly crystallization BiFeO3 with rhombohedral structure (space group R3c (161)) was obtained when the precursor was calcined at 873 K for 2 h. The thermal process of the precursor experienced three steps, which involve the dehydration of adsorption water, hydroxide, and decomposition of carbonates at first, and then crystallization of BiFeO3, and at last decomposition of BiFeO3 and formation of orthorhombic Bi2Fe4O9. The mechanism and kinetics of the crystallization process of BiFeO3 were studied using DSC and XRD techniques, the results show that activation energy of the crystallization process of BiFeO3 is 126.49 kJ mol−1, and the mechanism of crystallization process of BiFeO3 is the random nucleation and growth of nuclei reaction.

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Abstract  

In this study, superparamagnetic iron oxide nanoparticles (SPION) embedded by folic acid (SPION-folate) were prepared by a modified co-precipitation method. The structure, size, morphology, magnetic property and relaxivity of the SPION-folate were characterized systematically by means of XRD, VSM, HRSEM and TEM and the interaction between folate and iron oxide (Fe3O4) was characterized by FT-IR. The particle size was shown to be ≈5–10 nm. To ensure biocompatibility, the interaction of these SPION with mouse connective tissue cells (adhesive) was investigated using an MTT assay. Consequently, gallium-67 labeled nanoparticles ([67Ga]-SPION-folate) were prepared using 67Ga with a high labeling efficiency (over 96%, RTLC method) and they also showed an excellent stability at room temperature for at least 2 days and were evaluated for their biodistribution in normal rats up to 24 h compared with free Ga3+ cation and [67Ga]-SPION biodistribution. The biodistribution of the tracer among 3 other folate tracers were compared, showing lower liver uptake and higher blood circulation after 24 h leading to better bioavailability. The bone:muscle, kidney:muscle, lung:muscle, stomach:muscle ratios were 9.3, 9.32, 7.6 and 5.83 respectively. The developed folate-containing nano-system can be an interesting folate receptor tracer, capable of better cell membrane permeability while possessing paramagnetic properties for thermotherapy.

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