Anisotropic Local Correlations and Dynamics in a Relaxor Ferroelectric

Relaxor ferroelectrics have been a focus of intense attention due to their anomalous dielectric characteristics, diffuse phase transitions, and strong piezoelectricity. Understanding the structure and dynamics of relaxors has been one of the long-standing challenges in solid-state physics, with the current model of polar nanoregions in a non-polar matrix providing only a qualitative description of the relaxor phase transitions. In this paper, we investigate the local structure and dynamics in 75%PbMg$_{1/3}$Nb$_{2/3}$O$_3$-25%PbTiO$_3$ (PMN-PT) using molecular dynamics simulations and the dynamic pair distribution function technique. We show for the first time that relaxor transitions can be described by local order parameters. We find that structurally, the relaxor phase is characterized by the presence of highly anisotropic correlations between the local cation displacements. These correlations resemble the hydrogen bond network in water. Our findings contradict the current polar nanoregion model; instead, we suggest a new model of a homogeneous random network of anisotropically coupled dipoles.Comment: We combine our manuscript and supplementary information in one file. 5 pages and 3 figures in main text. 3 pages and 3 figures in supplementary informatio

Post density functional theoretical studies of highly polar semiconductive Pb(Ti1−x_{1-x}Nix_{x})O3−x_{3-x} solid solutions: The effects of cation arrangement on band gap

We use a combination of conventional density functional theory (DFT) and post-DFT methods, including the local density approximation plus Hubbard $U$ (LDA+$U$), PBE0, and self-consistent $GW$ to study the electronic properties of Ni-substituted PbTiO$_{3}$ (Ni-PTO) solid solutions. We find that LDA calculations yield unreasonable band structures, especially for Ni-PTO solid solutions that contain an uninterrupted NiO$_{2}$ layer. Accurate treatment of localized states in transition-metal oxides like Ni-PTO requires post-DFT methods. $B$-site Ni/Ti cation ordering is also investigated. The $B$-site cation arrangement alters the bonding between Ni and O, and therefore strongly affects the band gap ($E_{\rm g}$) of Ni-PTO. We predict that Ni-PTO solid solutions should have a direct band gap in the visible light energy range, with polarization similar to the parent PbTiO$_{3}$. This combination of properties make Ni-PTO solid solutions promising candidate materials for solar energy conversion devices.Comment: 19 pages, 6 figure

In-situ growth of superconducting NdFeAs(O,F) thin films by Molecular Beam Epitaxy

The recently discovered high temperature superconductor F-doped LaFeAsO and related compounds represent a new class of superconductors with the highest transition temperature (Tc) apart from the cuprates. The studies ongoing worldwide are revealing that these Fe-based superconductors are forming a unique class of materials that are interesting from the viewpoint of applications. To exploit the high potential of the Fe-based superconductors for device applications, it is indispensable to establish a process that enables the growth of high quality thin films. Efforts of thin film preparation started soon after the discovery of Fe-based superconductors, but none of the earlier attempts had succeeded in an in-situ growth of a superconducting film of LnFeAs(O,F) (Ln=lanthanide), which exhibits the highest Tc to date among the Fe-based superconductors. Here, we report on the successful growth of NdFeAs(O,F) thin films on GaAs substrates, which showed well-defined superconducting transitions up to 48 K without the need of an ex-situ heat treatment

Development of Health Literacy from Activities of Culture, Leisure, and Sports

Living in a healthy and independent manner would be beneficial for people. Health literacy can be obtained through activities of culture, leisure, and sports. Authors have been involved in sports medicine, music, and management of International Masters Athletics Federation（IMAF）. Health literacy would be a dynamic multi-dimensional perspective that combines various kinds of health-related matter, information, and activity. It can be developed through the activities of sports and music. These opportunities are divided into scheduled care healthcare programs and unexpected human interaction with various participants together. The latter would be a synergistic effect in multi-dimensional aspects

Lentivector Transduction Improves Outcomes Over Transplantation of Human HSCs Alone in NOD/SCID/Fabry Mice

Fabry disease is a lysosomal storage disorder caused by a deficiency of a-galactosidase A (a-gal A) activity that results in progressive globotriaosylceramide (Gb(3)) deposition. We created a fully congenic nonobese diabetic (NOD)/severe combined immunodeficiency (SCID)/Fabry murine line to facilitate the in vivo assessment of human cell-directed therapies for Fabry disease. This pure line was generated after 11 generations of backcrosses and was found, as expected, to have a reduced immune compartment and background a-gal A activity. Next, we transplanted normal human CD34(+) cells transduced with a control (lentiviral vector-enhanced green fluorescent protein (LV-eGFP)) or a therapeutic bicistronic LV (LV-a-gal A/internal ribosome entry site (IRES)/hCD25). While both experimental groups showed similar engraftment levels, only the therapeutic group displayed a significant increase in plasma a-gal A activity. Gb(3) quantification at 12 weeks revealed metabolic correction in the spleen, lung, and liver for both groups. Importantly, only in the therapeutically-transduced cohort was a significant Gb(3) reduction found in the heart and kidney, key target organs for the amelioration of Fabry disease in humans.Fil: Pacienza, Natalia Alejandra. University Health Network; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Yoshimitsu, Makoto. Kagoshima University; Japón. University Health Network; CanadáFil: Mizue, Nobuo. University Health Network; CanadáFil: Au, Bryan C. Y.. University Health Network; CanadáFil: Wang, James C. M.. University Health Network; CanadáFil: Fan, Xin. University Health Network; CanadáFil: Takenaka, Toshihiro. Kagoshima University; JapónFil: Medin, Jeffrey A. University Health Network; Canadá. University of Toronto; Canad