86 research outputs found

    Ferroelectric Photovoltaic Effect

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    Tetragonal BiFeO3 films with the thickness of 30 nm were grown epitaxially on (001) oriented LaAlO3 substrate by using pulsed laser deposition (PLD). The transverse photovoltaic effects were studied as a function of the sample directions in-plane as well as the angle between the linearly polarized light and the plane of the sample along X and Y directions. The absorption onset and the direct band gap are ~2.25 and ~2.52 eV, respectively. The photocurrent depends not only on the sample directions in-plane but also on the angle between the linearly polarized light and the plane of the sample along X and Y directions. The results indicate that the bulk photovoltaic effect together with the depolarization field was ascribed to this phenomenon. Detailed analysis presents that the polarization direction is along [110] direction and this depolarization field induced photocurrent is equal to ~3.53 μA/cm2. The BPV induced photocurrent can be approximate described as Jx ≈ 2.23cos(2θ), such an angular dependence of photocurrent is produced as a consequence of asymmetric microscopic processes of carriers such as excitation and recombination

    HybridGait: A Benchmark for Spatial-Temporal Cloth-Changing Gait Recognition with Hybrid Explorations

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    Existing gait recognition benchmarks mostly include minor clothing variations in the laboratory environments, but lack persistent changes in appearance over time and space. In this paper, we propose the first in-the-wild benchmark CCGait for cloth-changing gait recognition, which incorporates diverse clothing changes, indoor and outdoor scenes, and multi-modal statistics over 92 days. To further address the coupling effect of clothing and viewpoint variations, we propose a hybrid approach HybridGait that exploits both temporal dynamics and the projected 2D information of 3D human meshes. Specifically, we introduce a Canonical Alignment Spatial-Temporal Transformer (CA-STT) module to encode human joint position-aware features, and fully exploit 3D dense priors via a Silhouette-guided Deformation with 3D-2D Appearance Projection (SilD) strategy. Our contributions are twofold: we provide a challenging benchmark CCGait that captures realistic appearance changes across an expanded and space, and we propose a hybrid framework HybridGait that outperforms prior works on CCGait and Gait3D benchmarks. Our project page is available at https://github.com/HCVLab/HybridGait

    Influence of Co ion doping on the microstructure, magnetic and dielectric properties of Ni1-xCoxFe2O4 ceramics

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    Ni1-xCoxFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8) ceramics were prepared by chemical co-precipitation method and the effect of Co ion doping on the microstructure, magnetic and dielectric properties has been investigated. The results show that the synthesized ceramics display only spinel phase of Ni1-xCoxFe2O4, without other apparent impurities found. The lattice of Ni1-xCoxFe2O4 crystal structure was distorted as a result of the incorporation of Co ion, and the lattice parameters increase with the increase of Co ion content. The grain size decreases slightly with increasing the content of Co ion, indicating a change of particle size and morphology at higher doping content. The results of impedance analysis shows that the sample doped with 80 at.% Co possesses the maximal dielectric constant, while the pure NiFe2O4 sample shows the minimal value when the frequency is below 0.1 MHz. The M-H loops of these ceramics exhibit highly magnetic nature and the saturation magnetization. The remnant magnetization increases linearly with the increase of Co-concentration in nickel ferrite while the coercive field (Hc) shows non-monotonic variation with Co content. The minimal and maximal values of Hc can be obtained when the Co concentrations are 40 and 80 at.%, respectively. The highest value of the saturation magnetization is 63 emu/g obtained with 80 at.% Co doping while the lowest value is ∼31 emu/g for the pure NiFe2O4 ceramics. The abnormal magnetic behaviour is due to the A-B super exchange interaction when magnetic Co2+ ions are added

    Dielectric, ferroelectric and magnetic properties of Bi0.78La0.08Sm0.14Fe0.85Ti0.15O3 ceramics prepared at different sintering conditions

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    Although BiFeO3 (BFO) has attracted great attention due to its special physical properties as a typical single phase multiferroic material, the application is limited due to the formation of impurities, defects and so forth. Herein, we report improved multiferroic properties of Bi0.78La0.08Sm0.14Fe0.85Ti0.15O3 (BLSFTO) ceramics by combination of co-doping and sintering schedule. BLSFTO multiferroic ceramics were prepared by using the conventional solid state reaction method and the effect of sintering time (2, 5, 10, 20 and 30 h) on the structural, dielectric and multiferroic properties was investigated systematically. The result indicates that stable BLSFTO phase with perovskite structure was formed for all the samples. Only some impurities such as Bi2O4 can be observed when the sintering time is longer than 20 h, indicating that the sintering time can induce structural changes in BLSFTO and too long sintering time can remarkably increase the secondary phases. In addition, the frequency dependent dielectric properties show that sintering time has distinct effect on the frequency stability and the relaxation process. The result demonstrates that the enhanced magnetization, improved dielectric and ferroelectric properties may be correlated with the structural transformation, impurities, oxygen vacancies and grain morphology

    Morphological Variation and Its Environmental Correlates in the Taihangshan Swelled-Vented Frog across the Qinling Mountains

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    The Taihangshan swelled-vented frog (Feirana taihangnica), an endemic species to the Qinling Mountains, central China, has experienced a dramatic population decline over the last few decades. The aim of this work was to quantify morphological variation in F. taihangnica across the Qinling Mountains and examine environmental correlates of this variation of morphological traits. We implemented a hierarchical partitioning to estimate the independent contribution of each environmental variable on morphological variations. Temperature seasonality was the greatest contributor in variations of snout-vent length (SVL) and head width, and ultraviolet-B (UV-B) radiation of the lowest month was the most influential on both thigh length and tibia width. Then, we used generalized additive models to analyze the relationship between each environmental factor and morphological trait variations. Along the increasing of annual mean temperature, SVL decreased firstly and then increased, indicating no support for Bergmann’s rule. Furthermore, SVL was negatively correlated with annual precipitation, while positively with temperature seasonality. The mean UV-B of the highest and lowest months was positively and negatively correlated with head width, thigh length and tibia width, respectively. The results of this study help us to understand adaptive potential of this mountain frog species via morphological variations in the light of environmental changes

    Effects of sintering temperature and holding time on the microstructure and electric properties of Ba(Zr0.3Ti0.7)O3 ceramics

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    Ba(Zr0.3Ti0.7)O3 (BZT) ceramics was prepared by using conventional solid state reaction. The effects of sintering temperature and holding time on the crystal structure, surface morphology, dielectric, ferroelectric and piezoelectric properties of the BZT ceramics were systematically investigated. X-ray diffraction (XRD) results confirm single cubic perovskite phase in all the sintered samples. Microstructure analysis using scanning electron microscopy (SEM) reveals that the grain sizes increase with increasing the sintering temperature. Dielectric spectroscopy performed in the range of 20 Hz to 2 MHz at room temperature shows that the dielectric constant increases with the sintering temperature and the dielectric constant of the BZT ceramics sintered at 1400 °C for 8 h is around 11500. The ferroelectric hysteresis loops show that the coercive field decreases with the holding time, while the remnant polarization does not change obviously. The maximum strain is 0.023% for the sample sintered at 1400 °C for 4 h. It is found that the maximum value of the direct piezoelectric coefficient (d33) of the BZT ceramics sintered at 1400 °C for 8 h measured at room temperature is 36.7 pC/N

    Comprehensive Genome-Wide Analysis of <i>Wnt</i> Gene Family and Expression Profiling during Limb Regeneration in <i>Portunus trituberculatus</i>

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    Wnt genes encode a family of secretory glycoproteins that are involved in various stages of organ development through regulation of cell proliferation, differentiation, and growth. Recently, Wnt genes have been shown to play an important role in regeneration processes. However, there have been no previous genome-wide analyses of the Wnt gene family members in crab species. In this study, a total of 13 Wnt family genes were identified from the genome of the swimming crab Portunus trituberculatus and classified into three main groups based on the conserved domain, protein sequence, and motifs. Chromosome location analysis showed that tandem duplication may have resulted in the expansion of the PtWnt gene family. RNA-seq results indicated that most PtWnt genes had a higher Fragments Per Kilobase of transcript sequences per Million base pairs (FPKM) value in the regenerating limb bud muscle than in the normal limb muscle, and the genes were enriched in a number of pathways that had biological functions underlying limb regeneration such as the cell surface receptor signaling pathway, the hippo signaling pathway, receptor binding, and basal cell carcinoma. Moreover, quantitative real-time PCR (RT-qPCR) analysis confirmed that the expression levels of nine PtWnts except for PtWnt1, PtWnt2, and PtWnt6 had a consistently increasing trend during limb regeneration. PtWnt1, PtWnt2, and PtWnt6 exhibited significantly up- or down-regulated expression at different limb regeneration stages. These results provide valuable information for further evolutionary and functional characterization of PtWnt genes and indicate the complexity and specialized mechanism of the Wnt signaling pathway regulating regeneration in crustaceans

    Comprehensive Genome-Wide Analysis of Wnt Gene Family and Expression Profiling during Limb Regeneration in Portunus trituberculatus

    No full text
    Wnt genes encode a family of secretory glycoproteins that are involved in various stages of organ development through regulation of cell proliferation, differentiation, and growth. Recently, Wnt genes have been shown to play an important role in regeneration processes. However, there have been no previous genome-wide analyses of the Wnt gene family members in crab species. In this study, a total of 13 Wnt family genes were identified from the genome of the swimming crab Portunus trituberculatus and classified into three main groups based on the conserved domain, protein sequence, and motifs. Chromosome location analysis showed that tandem duplication may have resulted in the expansion of the PtWnt gene family. RNA-seq results indicated that most PtWnt genes had a higher Fragments Per Kilobase of transcript sequences per Million base pairs (FPKM) value in the regenerating limb bud muscle than in the normal limb muscle, and the genes were enriched in a number of pathways that had biological functions underlying limb regeneration such as the cell surface receptor signaling pathway, the hippo signaling pathway, receptor binding, and basal cell carcinoma. Moreover, quantitative real-time PCR (RT-qPCR) analysis confirmed that the expression levels of nine PtWnts except for PtWnt1, PtWnt2, and PtWnt6 had a consistently increasing trend during limb regeneration. PtWnt1, PtWnt2, and PtWnt6 exhibited significantly up- or down-regulated expression at different limb regeneration stages. These results provide valuable information for further evolutionary and functional characterization of PtWnt genes and indicate the complexity and specialized mechanism of the Wnt signaling pathway regulating regeneration in crustaceans
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