Fabrication and characterization of Ni0.3Zn0.7Fe2.0O4-BaTiO3 ceramic composites

The ceramic composites containing 1-25 vol% BaTiO3 in a ferrite matrix phase of Ni0.3Zn0.7Fe2O4 were fabricated by sintering at 1250°C in air. The sintered composites indicated a steep increase in dielectric permittivity in a small BaTiO3 ratio up to 5 vol%. In a limited BaTiO3 ratio of 3-15 vol%, a reaction between Ni0.3Zn0.7Fe2O4 and BaTiO3 resulted in the production of a liquid phase during sintering, which caused correspondingly the formation of secondary phases of BaFe2O4 ss and hexagonal BaTiO3 ss. These solid phase and microstructure changes, however, brought about little contribution to the increasing permittivity of the composites. Electrical property evaluations combined with compositional analysis revealed that the remarkably increasing permittivity could be predominantly attributed to the electron hopping between Fe2+ and Fe3+ in the ferrite matrix, which was caused by the incorporation of a small amount of Ti4+ into the spinel sublattice

Permittivity Change of NiZn Ferrite–BaTiO3Composites with Fe Content

Ceramic composites were fabricated from powder mixtures of BaTiO3 and Ni0:3Zn0:7FexO4 with different Fe contents of x ¼ 1:8, 1.9, 2.0, 2.1, and 2.2 to examine the effect of Fe content on the dielectric permittivity ("r) of the composite samples (these are referred to as Fe1.8, Fe1.9, Fe2.0, Fe2.1, and Fe2.2 composites or samples, respectively). The "r values of the composites were greatly affected by the Fe content such that a small "r value of the Fe1.8 composite sample steeply increased with increasing Fe content by about three orders of magnitude for the Fe2.1 and Fe2.2 samples. The strong Fe content dependence could be correlated with the incorporation of Ti4þ ions into the octahedral sublattices in the ferrite structure. Therefore, the markedly increasing "r values for the Fe2.1 and Fe2.2 composite samples can be attributed to the presence of Fe2þ ions synergetically created by the Ti-substitution and Fe-rich composition

Low-temperature fabrication of NiCuZn Ferrite^|^ndash;(Ba0.7Sr0.3)TiO3 composites using granulated powders

NiCuZn ferrite( Ba0.7Sr0.3)TiO3 (BST) composite ceramics with the BST content of up to 50 vol% were fabricated by sintering compacted powder mixtures at 900°C. The granulation of the BST powder and addition of a Bi2O3-based oxide additive effectively assisted the densification of the composite samples. The samples thus fabricated showed required ¾r values whereas their ®r values were considerably reduced, especially for those with lower BSTcontents. From the detailed examinations on the effect of the Bi2O3- based oxide additives and on the process modification to improve the reduced ®r values, the addition of a Bi2O3ZnO additive with the eutectic composition of as low as 1wt%was enough to produce a densified 10 vol%BSTcomposite sample with a highest ®r value. It was also found that the incorporation of ferrite granules calcined at 600°C caused further improvement of ®r. Thus, a densified 10BST composite sample with ®r = 125 was fabricated by low-temperature sintering at 900°C

Impact of Serum Uric Acid Level on Systemic Endothelial Dysfunction in Patients with a Broad Spectrum of Ischemic Heart Disease

Previous studies indicated that serum uric acid (SUA) level is a marker of endothelial function in subsets of ischemic heart disease (IHD). In the present study, we aimed to evaluate the relation between the SUA level and endothelial function in patients with a broad spectrum of IHD, including obstructive coronary artery disease (CAD) and ischemia with no obstructive CAD (INOCA). Three prospective studies and one retrospective study were pooled, in which the SUA level was measured, and systemic endothelial function was assessed using the reactive hyperemia index (RHI). The primary endpoint of the present study was a correlation of the SUA level with RHI. A total of 181 patients with a broad spectrum of IHD were included, among whom, 46 (25%) had acute coronary syndrome presentation and 15 (8%) had INOCA. Overall, the SUA level was negatively correlated with the RHI (r = −0.22, p = 0.003). Multivariable analysis identified the SUA level and INOCA as significant factors associated with RHI values. In conclusion, in patients with a broad spectrum of IHD, including obstructive epicardial CAD (chronic and acute coronary syndromes) and INOCA, the SUA level was significantly and negatively correlated with systemic endothelial function assessed with the RHI. INOCA, rather than obstructive CAD, was more associated with endothelial dysfunction