Effect of Ba content on the stress-sensitivity of the antiferroelectric to ferroelectric phase transition in (Pb,La,Ba,)(Zr,Sn,Ti)O3 ceramics

The effect of Ba content on the stress sensitivity of the antiferroelectric to ferroelectric phase transition in (Pb0.94−xLa0.04Bax)[(Zr0.60Sn0.40)0.84Ti0.16]O3 ceramics is investigated through monitoring electric field-induced polarization and longitudinal strain under compressive prestresses. It is found that incorporation of Ba significantly suppresses the stress sensitivity of the phase transition, as manifested by slight decreases under prestresses up to 100 MPa in the maximum polarization (Pm) and longitudinal strain (xm). The energy storage density is even increased under the mechanical confinement in compositions x = 0.02 and 0.04. X-ray diffraction, transmission electron microscopy, and dielectric measurements indicate that the suppressed stress sensitivity is associated with the disruption of micrometersized antiferroelectric domains into nanodomains and the transition from antiferroelectric to relaxor behavior

Refined Equivalent Pinhole Model for Large-scale 3D Reconstruction from Spaceborne CCD Imagery

In this study, we present a large-scale earth surface reconstruction pipeline for linear-array charge-coupled device (CCD) satellite imagery. While mainstream satellite image-based reconstruction approaches perform exceptionally well, the rational functional model (RFM) is subject to several limitations. For example, the RFM has no rigorous physical interpretation and differs significantly from the pinhole imaging model; hence, it cannot be directly applied to learning-based 3D reconstruction networks and to more novel reconstruction pipelines in computer vision. Hence, in this study, we introduce a method in which the RFM is equivalent to the pinhole camera model (PCM), meaning that the internal and external parameters of the pinhole camera are used instead of the rational polynomial coefficient parameters. We then derive an error formula for this equivalent pinhole model for the first time, demonstrating the influence of the image size on the accuracy of the reconstruction. In addition, we propose a polynomial image refinement model that minimizes equivalent errors via the least squares method. The experiments were conducted using four image datasets: WHU-TLC, DFC2019, ISPRS-ZY3, and GF7. The results demonstrated that the reconstruction accuracy was proportional to the image size. Our polynomial image refinement model significantly enhanced the accuracy and completeness of the reconstruction, and achieved more significant improvements for larger-scale images.Comment: 24 page

Electrocaloric effect in ferroelectric ceramics with point defects

The electrocaloric effect has drawn much attention due to its potential application in cooling devices. A negative electrocaloric effect is predicted to be induced in defect-doped ferroelectrics by computational results [A. Grunebohm and T. Nishimatsu, Phys. Rev. B 93, 134101 (2016) and Ma et al., Phys. Rev. B 94, 094113 (2016)], but it need to be confirmed by experimental results. In this work, we prepared a 1mol. % Mn-doped Pb(Zr0.2,Ti0.8)O3 ceramics (Pb((Zr0.2,Ti0.8)0.99,Mn0.01)O3), and the electrocaloric effect of the defect-containing ferroelectric ceramics has been investigated by both direct and indirect methods. The indirect method shows a similar negative electrocaloric effect signal as the computational results predicted, while the direct method gives a positive electrocaloric effect. The absence of the negative electrocaloric effect obtained by the direct method may originate from: (a) the unavailability and the improper prediction of the Maxwell relation, (b) an improper assumption of fixed defects in the computational models, and (c) the offset of heat loss due to the application of a large electric field. In addition, we find a giant positive electrocaloric effect of 0.55K at room temperature in the aged ceramics where no phase transition takes place. We attribute this abnormal electrocaloric effect to the restoration force of the defect dipoles. Our results not only provide insights into the origin of the negative electrocaloric effect, but also offer opportunities for the design of electrocaloric materials

The role of ERK1/2 in colitis through regulation of NADPH oxidase and mitochondrial fission

Objective To investigate the role of extracellular signal regulated kinase 1/2 （ERK1/2） in colitis through the regulation of NADPH oxidase and mitochondrial fission. Methods Mice models of acute colitis were induced by 3% dextran sulfate sodium （DSS）. Thirty C57BL/6J mice were randomly divided into six groups by random number table method： control group， 3%DSS group，1% dimethyl sulfoxide （DMSO） group， ERK1/2 inhibitor（PD98059） group， 3%DSS+1%DMSO group and 3%DSS+PD98059 group， with five mice in each group. The changes of body weight， colonic length， disease activity index and colonic histopathological changes of mice in the control and 3%DSS groups were evaluated， and the expression levels of ERK1/2， p-ERK1/2， Nicotinamide adenine dinucleotide phosphate oxidase 1 （Nox1） and Nox2 in colonic mucosa of mice were detected. Mice in 1%DMSO and 3%DSS+1%DMSO groups were intraperitoneally injected with 1%DMSO. Mice in the PD98059 and 3%DSS+PD98059 groups were intraperitoneally injected with PD98059. The colonic histopathological changes were evaluated among four groups， and the expression levels of Nox1， Nox2， Dynamin related protein 1 （DRP1）， p-DRP1-S616 and p-DRP1-S637 mitochondrial fission related proteins were detected. Mitochondrial fission of colonic epithelial cells in the control and 3%DSS groups was observed by transmission electron microscopy. The co-localization of Nox2 and mitochondrial outer membrane translocator enzyme TOM complex （TOMM20） in colonic mucosa of mice in two groups was analyzed by double-immunofluorescence staining. The correlation between relative expression levels of DRP1 and Nox2 mRNA in mouse colonic mucosa was analyzed in two groups. Results Compared with the control group， mice in the 3%DSS group exhibited body weight loss， shortened colonic length， increased disease activity index and increased colonic histopathological score. The expression levels of p-ERK1/2， Nox1， Nox2 in colonic mucosa of mice were significantly up-regulated in the 3%DSS group （all P < 0.05）. In mice with colitis， mitochondrial fission in colonic epithelial cells was increased， and the colonic mucosa co-localization of DRP1 and Nox2 was elevated， and the relative mRNA expression levels of both target genes were positively correlated （r = 0.678， P < 0.05）. ERK1/2 inhibitor PD98059 improved colonic histopathological changes in mice with colitis， and down-regulated the expression levels of Nox1， Nox2， DRP1， p-DRP1-S616 in colonic mucosa. Conclusion Inhibition of ERK1/2 may ameliorate colitis by down-regulating NADPH oxidase expression and alleviating mitochondrial fission

Genotyping and Phylogenetic Analysis of Yersinia pestis by MLVA: Insights into the Worldwide Expansion of Central Asia Plague Foci

BACKGROUND: The species Yersinia pestis is commonly divided into three classical biovars, Antiqua, Medievalis, and Orientalis, belonging to subspecies pestis pathogenic for human and the (atypical) non-human pathogenic biovar Microtus (alias Pestoides) including several non-pestis subspecies. Recent progress in molecular typing methods enables large-scale investigations in the population structure of this species. It is now possible to test hypotheses about its evolution which were proposed decades ago. For instance the three classical biovars of different geographical distributions were suggested to originate from Central Asia. Most investigations so far have focused on the typical pestis subspecies representatives found outside of China, whereas the understanding of the emergence of this human pathogen requires the investigation of strains belonging to subspecies pestis from China and to the Microtus biovar. METHODOLOGY/PRINCIPAL FINDINGS: Multi-locus VNTR analysis (MLVA) with 25 loci was performed on a collection of Y. pestis isolates originating from the majority of the known foci worldwide and including typical rhamnose-negative subspecies pestis as well as rhamnose-positive subspecies pestis and biovar Microtus. More than 500 isolates from China, the Former Soviet Union (FSU), Mongolia and a number of other foci around the world were characterized and resolved into 350 different genotypes. The data revealed very close relationships existing between some isolates from widely separated foci as well as very high diversity which can conversely be observed between nearby foci. CONCLUSIONS/SIGNIFICANCE: The results obtained are in full agreement with the view that the Y. pestis subsp. pestis pathogenic for humans emerged in the Central Asia region between China, Kazakhstan, Russia and Mongolia, only three clones of which spread out of Central Asia. The relationships among the strains in China, Central Asia and the rest of the world based on the MLVA25 assay provide an unprecedented view on the expansion and microevolution of Y. pestis

Epidemic clones, oceanic gene pools and eco-LD in the free living marine pathogen Vibrio parahaemolyticus

We investigated global patterns of variation in 157 whole genome sequences of Vibrio parahaemolyticus, a free-living and seafood associated marine bacterium. Pandemic clones, responsible for recent outbreaks of gastroenteritis in humans have spread globally. However, there are oceanic gene pools, one located in the oceans surrounding Asia and another in the Mexican Gulf. Frequent recombination means that most isolates have acquired the genetic profile of their current location. We investigated the genetic structure in the Asian gene pool by calculating the effective population size in two different ways. Under standard neutral models, the two estimates should give similar answers but we found a thirty fold difference. We propose that this discrepancy is caused by the subdivision of the species into a hundred or more ecotypes which are maintained stably in the population. To investigate the genetic factors involved, we used 51 unrelated isolates to conduct a genome-wide scan for epistatically interacting loci. We found a single example of strong epistasis between distant genome regions. A majority of strains had a type VI secretion system associated with bacterial killing. The remaining strains had genes associated with biofilm formation and regulated by c-di-GMP signaling. All strains had one or other of the two systems and none of isolate had complete complements of both systems, although several strains had remnants. Further top-down analysis of patterns of linkage disequilibrium within frequently recombining species will allow a detailed understanding of how selection acts to structure the pattern of variation within natural bacterial populations