Lower Vitamin D Levels are Associated with Higher Seroprevalence of Toxoplasma gondii —a US National Survey Study

Vitamin D deficiency is associated with high susceptibility to infections. The present study aimed at exploring the relationship between vitamin D levels and Toxoplasma gondii ( T. gondii ) infection, on the basis of a nationally representative database. The study data came from the National Health and Nutrition Examination Surveys (NHANES) 2001–2004. Participants underwent both Toxoplasma IgG antibody testing and serum vitamin D testing. Vitamin D deficiency was defined by a serum 25-hydroxyvitamin D level <20 ng/mL. Multivariate logistic regression and propensity score matching were used to adjust for potential confounders. All analyses were conducted in R software. A total of 10613 participants were included. Among these, 3973 (37.4%) were vitamin D deficient, and 2070 (19.5%) were seropositive for T. gondii IgG antibody. Vitamin D deficiency was found in 42.3% of the seropositive population, compared with 36.3% of the seronegative population ( P <0.001). After adjustment for sex, age, body mass index, smoking history, drinking history and testing season, vitamin D deficiency was associated with an elevated risk of T. gondii infection (OR=1.303, 95% CI=1.136–1.495, P <0.001). This effect persisted in the propensity matching cohort. Low vitamin D levels are associated with high seroprevalence of T. gondii

Robust ferromagnetism of single crystalline CoxZn1−xO (0.3 ≤ x ≤ 0.45) epitaxial films with high Co concentration

In contrast to conventional dilute magnetic semiconductors with concentrations of magnetic ions of just a few percent, here, we report the fabrication of epitaxial Cox Zn 1− xO single crystalline films with Co concentrations from x = 0.3 up to 0.45 by radio-frequency oxygen-plasma-assisted molecular beam epitaxy. The films retain their single crystalline wurtzite structure without any other crystallographic phase from precipitates, based on reflection high energy electron diffraction, X-ray diffraction, transmission electron microscopy, and Raman scattering. The results of X-ray diffraction, optical transmission spectroscopy, and in-situ X-ray photoelectron spectroscopy confirm the incorporation of Co2+ cations into the wurtzite lattice. The films exhibit robust ferromagnetism and the magneto-optical Kerr effect at room temperature. The saturation magnetization reaches 265 emu/cm3 at x = 0.45, which corresponds to the average magnetic moment of 1.5 μB per Co atom

Atomic scale study of the oxygen annealing effect on piezoelectricity enhancement of (K,Na)NbO 3 nanorods

With the increasing requirement of developing non-toxic piezoelectric materials, an alkaline niobate-based perovskite solid (K,Na)NbO3 (KNN) has been intensively studied. Promising piezoelectric properties are reported, which are mostly achieved by adding other elements, or simply varying the K/Na ratio. It is found that KNN nanorods grown on conductive Nb-doped SrTiO3 (STO) substrates show enhanced piezoelectric properties after annealing at 800 °C for 12 h [Y. He, Z. Wang, W. Jin, X. Hu, L. Li, Y. Gao, X. Zhang, H. Gu and X. Wang, Appl. Phys. Lett., 2017, 110, 212904]. However, the underlying mechanism for property enhancement at the atomic scale is not clearly revealed. In this study, comprehensive transmission electron microscopy techniques are utilized focusing on the atomic scale study of the interfacial composition, structures, strain, dipolar displacement vectors and their variations along the interface normal of the as-grown and annealed KNN nanorods. The results indicate phase transformation during annealing, and a larger spontaneous polarization within each unit cell of the annealed KNN nanorods, which lead to an overall enhancement of the piezoelectric properties. These results would be very beneficial for advanced nanogenerators and sensors with enhanced piezoelectric properties

Interfacial Strain Gradients Control Nanoscale Domain Morphology in Epitaxial BiFeO3 Multiferroic Films

International audienceIn ferroelectric thin films, the domain structure defines ferroelectric switching pathways and thus influences device performance. In epitaxial bismuth ferrite (BiFeO3) films, fractal-like domains have been observed, but direct evidence of their origins has remained unclear. Here, we show that the nature of the ferroelectric domain structure-i.e. striped vs. fractal-like-in epitaxial BiFeO3 is defined by the strain profile across the film-substrate interface. In samples with fractal-like domains, X-ray diffraction analysis reveals strong strain gradients, while geometric phase analysis using atomic resolution scanning transmission electron microscopy reveals that within a few nanometers of the film-substrate interface, the out of plane strain shows an anomalous dip while the in-plane strain is constant. Electron energy-loss near edge structure at the oxygen K edge shows that in the vicinity of the interface, the oxygen coordination is locally modified; this combined with the anomalous strain behavior thus drives the formation of fractal-like domains. Conversely, if uniform strain is maintained across the interface, characteristic striped domains are formed. Interestingly, conversion from the fractal-like arrangement to striped domains is found possible by an ex-situ thermal treatment step. Critically, the antiferromagnetic state of the BiFeO3 is influenced by the domain structure, whereby the fractal-like domains disrupt the long-range spin cycloid. Finally, as a demonstration of the applicability of this concept, we show that a carefully engineered lower electrode with large strain gradient can be used to induce fractal domains