3,517 research outputs found
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%PbMgNbO-25%PbTiO
(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(TiNi)O 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
(LDA+), PBE0, and self-consistent to study the electronic properties of
Ni-substituted PbTiO (Ni-PTO) solid solutions. We find that LDA
calculations yield unreasonable band structures, especially for Ni-PTO solid
solutions that contain an uninterrupted NiO layer. Accurate treatment of
localized states in transition-metal oxides like Ni-PTO requires post-DFT
methods. -site Ni/Ti cation ordering is also investigated. The -site
cation arrangement alters the bonding between Ni and O, and therefore strongly
affects the band gap () 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. 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 CientÃficas 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
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