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Solid solutions of BaTiO3 ferroelectric ceramics containing Sn2+ ions have been synthesized by solid state reaction with Ca2+ codoping. The crystal structures of Sn2+ ions doped (Ba,Ca)TiO3 were identified as tetragonal perovskite type BaTiO3 based on x-ray diffraction profiles analysis. (Ba1−xCax)TiO3 (x=0.13) tetragonality increased with Sn ions doping. Temperature dependence of the dielectric properties for Sn2+ ions doped (Ba1−xCax)TiO3 ceramic sample showed a tetragonal-to-cubic phase transition temperature of 155 °C, which is higher than that of undoped (Ba1−xCax)TiO3 (135 °C). By using synchrotron x-ray absorption near-edge structure spectroscopy the valence state of Sn ions in the (Ba1−x−yCaxSny)TiO3 (x=0.13, y=0.05) ferroelectric ceramics was identified to be Sn2+.

In this study, we investigated the sintering atmosphere dependence of the electric properties of Sn-doped (Ba0.82Ca0.13)TiO3 ceramics to clarify the effect of Sn2+ ions. The temperature of the dielectric constant peak for Sn-doped (Ba0.82Ca0.13)TiO3 ceramics sintered in a low P(O2) (1×10-11 MPa) atmosphere is higher than that for the sample sintered in a high P(O2) (2×10-2 MPa) atmosphere. The remanent polarization and coercive field for the Sn-doped (Ba0.82Ca0.13)TiO3 ceramics sintered at low P(O2) (1×10-11 MPa) also increased compared with those of the sample sintered at high P(O2) (2×10-2 MPa) at room temperature. The low P(O2) sintering atmosphere for Sn-doped (Ba0.82Ca0.13)TiO3 ceramics leads to a high tetragonality and the existence of Sn2+ ions. In addition, by X-ray absorption spectroscopy, it was verified that Sn2+ ions occupy Ba2+ sites in the (Ba0.82Ca0.13)TiO3 ceramics. Consequently, it is concluded that the high ferroelectric-to-paraelectric phase transition temperature and the high remanent polarization on the ceramics originate from Sn2+ ions substituted for Ba2+ sites in Sn-doped (Ba0.82Ca0.13)TiO3 ceramics.

An artificial basement membrane is fabricated using porous polymer nanosheets. Spontaneous formation of anisotropic cellular alignment is induced in a rolled nanosheet construct, seen in the figure, in which the macroporous structure contributes to the interconnection of adjacent cell monolayers. The biodegradable porous nanosheet fabricated by gravure coating and phase separation is a useful tool for engineering hierarchical cellular organization.

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Average and local structure of the Pb-free ferroelectric perovskites (Sr,Sn)TiO3 and (Ba,Ca,Sn)TiO3 The characteristic structural off-centering of Pb 2+ in oxides, associated with its 6s 2 lone pair, allows it to play a dominant role in polar materials, and makes it a somewhat ubiquitous component of ferroelectrics. In this work, we examine the compounds Sr0.9Sn0.1TiO3 and Ba0.79Ca0.16Sn0.05TiO3 using neutron total scattering techniques with data acquired at different temperatures. In these compounds, previously reported as ferroelectrics, Sn 2+ appears to display some of the characteristics of Pb 2+ . We compare the local and long-range structures of the Sn 2+ -substituted compositions to the unsubstituted parent compounds SrTiO3 and BaTiO3. We find that even at these small substitution levels, the Sn 2+ lone pairs drive the local ordering behavior, with the local structure of both compounds more similar to the structure of PbTiO3 rather than the parent compounds.

Background: Pulmonary vein (PV) stump thrombus, a known source of cerebral infarction, develops almost exclusively after left upper lobectomy; however, the mechanism remains unclear. We therefore evaluated the hemodynamics in the left atrium with four-dimensional flow magnetic resonance imaging (4D-flow MRI), which enables the simultaneous depiction of blood flow at three locations and the evaluation of hemodynamics. Methods: 4D-flow MRI was basically performed 7 days after lobectomy for cancer arising in the right upper lobe (n=11), right lower lobe (n=8), left upper lobe (n=13), or left lower lobe (n=8). We evaluated dynamic blood movement from the ipsilateral remaining PV, the resected PV stump, and the contralateral PVs into the left atrium using 4D-flow MRI.Results: There were some characteristic blood flow patterns that seemed to either promote or prevent PV stump thrombus. Promotive flow patterns were significantly more frequent and preventive flow patterns were significantly less frequent in patients who had undergone left upper lobectomy than in those who had undergone other lobectomy. Accordingly, the degree of blood turbulence near the vein stump, as measured by the extent of change in the blood movement, was significantly higher in patients who had undergone left upper lobectomy than in patients who had undergone other lobectomy. Conclusions: Our study revealed that left upper lobectomy likely causes blood turbulence near the vein stump through complicated blood streams in the left atrium, which can play a part in the development of vein stump thrombus. Further study to identify patients at high risk of vein stump thrombus is warranted.

We discuss the doping effect of Sn2+ on ATiO3 perovskites by comparing with those of Pb and Ba. The solution energy of Sn into A sites of ATiO3 perovskites shows minimum when the lattice size is almost the same as that of SrTiO3 (STO), as determined by first-principles calculations. In dielectric measurements of these STO-based ceramics, the Sn2+-doped STO ceramics showed a higher peak temperature than the Pb2+- or Ba2+-doped STO ceramics at the same doping amount. In addition, the maximum polarization obtained in the Sn2+-doped STO ceramics was larger than that obtained in the Pb2+- or Ba2+-doped ceramics in terms of the relationship between the polarization and electric field curve measurement at room temperature. The piezoresponse was also observed in the Sn2+-doped STO ceramics at room temperature by piezoresponse force microscopy. We propose that these effects originate from the bond length between Sn2+ and O2- which is smaller than that between Pb2+ and O2-. The Sn2+ ion prefers the off-center position at the Sr2+ site because of the retention of the stable bond length between Sn2+ and O2-. These leads to the formation of polar regions and which can assist in the generation of a larger polarization.