0-3 type magnetoelectric(ME) composites of PbTiO 3 (PT) and CoFe 2 O 4 (CFO) were prepared by a conventional solid-state reaction method with different volume fraction. The composites exhibited ferroelectric phase and ferromagnetic phase coexisting. The ferroelectric and magnetic properties of as-sintered samples were measured. The magnetic properties change regularly with the test frequency. But the dielectric permittivity shows the anomalies, which can be attributed to constraints and dilutions from the ferromagnetic phase and the element diffusion.
In the present study, we have demonstrated that alginate and collagen sponge can act as scaffolds in order to support 3-dimensional structure for the differentiated bone marrow derived mesenchymal stem cells (BMSCs) during chondrogenesis in vitro and in vivo. The chondrogenic induced BMSCs were well distributed and differentiation in scaffolds system before implantation, then they produced sufficient ECM in the implants to form chondroid aggregates in vivo. In our opinion, well-differentiated BMSCs is a crucial feature of cartilage repair and only can be achieved in scaffold matrix. Furthermore, when dealing with cartilage defects, alginate seem to be superior to collagen sponge, and the combinational strategy of pre-induced BMSCs combined with alginate 3D-culture might be useful in improving conventional autologous cells transplantation or free-cells scaffolds.
The BiFeO3 thin film was prepared by sol-gel process on Pt/Si substrates. The dependences of structural, electrical properties on annealed temperature were studied. X-ray diffraction (XRD) analysis revealed that the pure phase of BiFeO3 thin film was obtained when annealed below 650°C for 60 minutes in air. The film annealed at lower temperature had denser surface morphology, and showed better electrical characteristic.
Single phase pyrite has been successfully prepared via the reaction of FeSO 4 ·7H 2 O, S and Na 2 S·9H 2 O using hydrothermal method. The X-ray powder diffraction measurements confirm the formation of iron disulfides in the pH range of 1-12. Marcasite is formed at pH<4, the marcasite contents in the final products increasing with decreasing pH; when the pH is higher than 4, the final product is single phase pyrite. Scanning electron microscope (SEM) images reveal that both the pH and temperatures have significant effects on the size and morphology of final products. Pyrite micro-nanocubes of 200-400nm in length were synthesized at pH=9. Detailed information of the experimental results are analyzed in the results and discussion part.
In this paper, the composition and dielectric properties of Ba 2 Ti 9 O 20 -BaFe 12 O 19 system ceramics were studied. The ceramics were prepared successfully through the conventional ceramic processing. The x-ray diffraction results showed that all specimens were made of multi-phases, and the sintering temperature on the phase structure of the ceramics did not affected. The effects of sintering conditions and the components on the dielectric properties were investigated in detail. The investigations indicated that the initial Ba 2 Ti 9 O 20 / BaFe 12 O 19 ratio had a great effect on the dielectric of the ceramics. The permittivity increased as the BaFe 12 O 19 content increased, whereas the dielectric loss decreased in the composite systems, which could be attributed to the variance in the formation of phases. At last, we suggested that further studies on magnetic properties should be considered for the application in electronic devices like LC filter.
The microstructure and dielectric properties of ferroelectric solutions which is formulated with (1-x)[0.9Pb(Mg 1/3 Nb 2/3 )O 3 -0.1PbTiO 3 ]-x mol% SrTiO 3 (x=0, 1, 3 and 5) have been investigated. The ceramics was fabricated by a modified columbite route sintered at 1200 °C. The effects of dopants on microstructure, maximum dielectric constant (ε m ) and diffuseness of the phase transition, etc. have been studied. It is found that the maximum permittivity (ε m ) increases to 24968 for the ST-doped (1 mol %) sample, subsequently decreases with ST addition and its corresponding phase-transition-temperature (T m ) shifts to the lower temperature. The variation of ε m is caused by the decrease of polar nano-region size, increase of the fluctuation of the component and the increase of the effective spontaneous polarization. The enhancement of relaxor behavior in the PMN-PT sample is explained by the decrease of FE/AFE coupling.
Over the years, probabilistic nature of renewable energy sources (RES) and its influence on power system adequacy have been well studied. However, rather less attention has been paid to the impact of RES unit itself's and its power conversion system's (PCS') reliability, as well as their various connection topologies. This paper devises a comprehensive sensitivity study on how each of these elements can affect overall generating system reliability. given the plethora of RES configurations and components, it is of import to identify the most vulnerable element in RES. In this work, component importance is extended, for the first time, to generating capacity adequacy assessment (HLI). Measurement index is the centerpiece in reliability importance. New indices have to be introduced to facilitate the study. While the physical meaning of previously developed indices is lost, in this study indices are proposed based on traditional importance measures, of which the physical meaning are strictly retained and consistent with the definitions. With the proposed assessment technique, components in various RES configuration can be ranked according to their reliability importance. It is found in the numerical study that different importance measures (such as risk-achievement based measures and risk-reduction based measures) can result in different rankings. Studies on contributing factors of the reliability importance are also performed. As more and more RES gaining foothold in generating systems, the proposed technique assist to achieve targeted reliability level of the system, by easily identifying and prioritizing reliability improvement tasks among various units/components in the increasing complex system.
Most of simulations often require the calculation of all pairwise interaction in large ensembles of particles, such as N-body problem of gravitation, electrostatic interaction and magnetic dipolar interaction, etc. The main difficulty in the calculation of long-range interaction is how to accelerate the slow convergence of the occurring sums. In this work, we are interested in the dipolar interaction in the two dimensional (2D) magnetic dipolar nanoparticle systems, which have attracted much attention due to both their important technological applications such as high-density patterned recording media and their rich and often unusual experimental behaviours. We develop a high efficiency algorithm based on the Lekner method to evaluate the magnetic dipolar energy for such systems, where the simulation cell is periodically replicated in the plane. Taking advantage of the symmetry of the systems, the dipolar interaction energy is expressed by rapidly converging series of modified Bessel functions in our algorithm. We found that our algorithm is better than the traditional Ewald summation method in efficiency for the regular arrays. Moreover, two simple formulas are obtained to evaluate the self-energy, which is important in the simulation of the dipolar systems.
Wave-transparent materials of aluminum borate whisker/phosphate chrome-alumina are synthesized through coating method. It is found that, from the TG-DSC image analysis, there are two endothermic peaks at 120 °C and 180 °C, respectively. Pressure and curing time at this temperature should be increased. The flexural and tensile strength of the composite material reach the maximum when the content of aluminum borate whiskers is 6%.
Since 1998, the telecommunications industry in China has gained the great growth. Hence, the telecommunications charges have been continuously lowered, telecommunications technical services have been persistently innovated, and the telecommunications users and business revenues increased constantly, having exerted great effect on the society. But there are also new questions ahead: the TFP has gradually slowed down since 2011, and the unbalanced development is shown in the eastern, middle and western regions, but some areas are undergoing extensive growth. The paper researches exogenous factors affecting China telecommunications industry TFP growth. The result pointed out that the level of economic development and degree of industrialization had contributed, to some extent, to improving the TFP growth rates of the telecommunications industry; Population scale and population density played a positive role in promoting the TFP growth rates of the telecommunications industry; Technological innovation had no effect on the telecommunications industry TFP, but there appeared the inhibition efficiency trend.
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