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  • 1
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    In:  Tectonophysics, Kunming, China, 3-4, vol. 374, no. 3-4, pp. 115-134, pp. B05301, (ISSN: 1340-4202)
    Publication Date: 2003
    Keywords: Modelling ; Geothermics ; Physical properties of rocks ; China ; Rheology ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; FLORENZO
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  • 2
    Publication Date: 2016-07-19
    Description: Li 2 O–MgO–TiO 2 ternary system is an important microwave dielectric ceramic material with excellent properties and prospect in both scientific research and application. A phase diagram of the Li 2 O–MgO–TiO 2 ternary system was established in this article, based on earlier research results and our present work. Microwave dielectric properties with compositions in different regions of the phase diagram have been analyzed. We found that the 0.33 Li 2 MgTi 3 O 8 –0.67 Li 2 TiO 3 ceramics sintered at 1200°C exhibited excellent dielectric properties: Q × f value = 80 476 GHz (at 7.681 GHz), ε r = 24.7, τ f = +3.2 ppm/°C. We also designed two ceramic systems in the Li-rich region of the Li 2 O–MgO–TiO 2 ternary system, which received little attention in the past decades, because many excellent single-phase ceramics, such as Li 2 MgTiO 4 , Li 2 MgTi 3 O 8 and MgTiO 3 , have been found in the Ti-rich region. The ceramic systems have low sintering temperatures but also relatively poor dielectric properties.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
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  • 3
    Publication Date: 2015-04-16
    Description: In this study, the spinel solid solution ceramics (1− x )LiFe 5 O 8 – x Li 2 ZnTi 3 O 8 (0 ≤  x  ≤ 1) were prepared via the solid-state reaction method. The phase evolution, sintering behaviors, microstructures, magneto-dielectric properties, and microwave dielectric properties were systematically investigated. The XRD and SEM analysis indicated that the LiFe 5 O 8 phase and the Li 2 ZnTi 3 O 8 phase were almost fully soluble in each other at any proportion. Meanwhile, the evidence of ionic substitution has been directly observed at the atomic scale by means of scanning transmission electron microscopy, which is further confirmed by the Raman spectroscopy. Evidence shows that the magnetic and dielectric properties are quite sensitive to the compositions. The optimal results with remarkable magneto-dielectric properties of μ′ = 38.2, tanδ μ  = 0.25, ε′ = 19.6, tanδ ε  = 8 × 10 −3 at 1 MHz, and ε′ = 19.1, Q  ×  f  = 10 400 GHz at about 7 GHz have been obtained in 0.25LiFe 5 O 8 –0.75Li 2 ZnTi 3 O 8 sample. The design of complex spinel solid solution can generate novel magneto-dielectric single-phase ceramics combining both high permeability and good dielectric properties, which provides a way in developing multifunctional materials for applications in electronic devices.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
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  • 4
    Publication Date: 2016-03-24
    Description: Modes of surface premelting in colloidal crystals composed of attractive particles Nature 531, 7595 (2016). doi:10.1038/nature16987 Authors: Bo Li, Feng Wang, Di Zhou, Yi Peng, Ran Ni & Yilong Han Crystal surfaces typically melt into a thin liquid layer at temperatures slightly below the melting point of the crystal. Such surface premelting is prevalent in all classes of solids and is important in a variety of metallurgical, geological and meteorological phenomena. Premelting has been studied using X-ray diffraction and differential scanning calorimetry, but the lack of single-particle resolution makes it hard to elucidate the underlying mechanisms. Colloids are good model systems for studying phase transitions because the thermal motions of individual micrometre-sized particles can be tracked directly using optical microscopy. Here we use colloidal spheres with tunable attractions to form equilibrium crystal–vapour interfaces, and study their surface premelting behaviour at the single-particle level. We find that monolayer colloidal crystals exhibit incomplete premelting at their perimeter, with a constant liquid-layer thickness. In contrast, two- and three-layer crystals exhibit conventional complete melting, with the thickness of the surface liquid diverging as the melting point is approached. The microstructures of the surface liquids differ in certain aspects from what would be predicted by conventional premelting theories. Incomplete premelting in the monolayer crystals is triggered by a bulk isostructural solid–solid transition and truncated by a mechanical instability that separately induces homogeneous melting within the bulk. This finding is in contrast to the conventional assumption that two-dimensional crystals melt heterogeneously from their free surfaces (that is, at the solid–vapour interface). The unexpected bulk melting that we observe for the monolayer crystals is accompanied by the formation of grain boundaries, which supports a previously proposed grain-boundary-mediated two-dimensional melting theory. The observed interplay between surface premelting, bulk melting and solid–solid transitions challenges existing theories of surface premelting and two-dimensional melting.
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 5
    Publication Date: 2019
    Description: Abstract In the (Bi1‐xCex)VO4 (0 ≤ x ≤ 1) system, we found that the (Bi1‐xCex)VO4 (0 ≤ x ≤ 0.1) belongs to the monoclinic scheelite phase and the (Bi1‐xCex)VO4 (0.7 ≤ x ≤ 1) belongs to the tetragonal zircon phase, while the (Bi1‐xCex)VO4 (0.1 〈 x 〈 0.7) belongs to the mixed phases of both monoclinic scheelite and tetragonal zircon structure. Interestingly, two components with near‐zero temperature coefficient of resonant frequency (TCF) appeared in this system. In our previous work, a near‐zero TCF of ~ +15 ppm/oC was obtained in a (Bi0.75Ce0.25)VO4 ceramic with a permittivity (εr) of ~ 47.9, a Qf (Q = quality factor = 1/dielectric loss; f = resonant frequency) value of ~18,000 GHz (at 7.6 GHz). Furthermore, in the present work, another temperature stable microwave dielectric ceramic was obtained in (Bi0.05Ce0.95)VO4 composition sintered at 950 °C and exhibits good microwave dielectric properties with a εr of ~ 11.9, a Qf of ~ 22,360 GHz (at 10.6 GHz), a near‐zero TCF of ~ +6.6 ppm/oC. The results indicate that this system might be an interesting candidate for microwave device applications. This article is protected by copyright. All rights reserved.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Wiley
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  • 6
    Publication Date: 2019
    Electronic ISSN: 2041-1723
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 7
    Publication Date: 2019
    Description: The MEF2 (myocyte enhancer factor 2) family belongs to the MADS-box superfamily of eukaryotic transcription factors. The vertebrate genes compose four distinct subfamilies designated MEF2A, -B, -C, and -D. There are multiple mef2 genes in the common carp (Cyprinus carpio). So far, the embryonic expression patterns of these genes and the evolution of fish mef2 genes have been barely investigated. In this study, we completed the coding information of C. carpio mef2ca2 and mef2d1 genes via gene cloning and presented two mosaic mef2 sequences as evidence for recombination. We also analyzed the phylogenetic relationship and conserved synteny of mef2 genes and proposed a new evolutionary scenario. In our version, MEF2B and the other three vertebrate subfamilies were generated in parallel from the single last ancestor via two rounds of whole genome duplication events that occurred at the dawn of vertebrates. Moreover, we examined the expression patterns of C. carpio mef2 genes during embryogenesis, by using whole-mount in situ hybridization, and found the notochord to be a new expression site for these genes except for mef2ca1&2. Our results thus provide new insights into the evolution and expression of mef2 genes.
    Electronic ISSN: 2073-4425
    Topics: Biology
    Published by MDPI
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  • 8
    Publication Date: 2019
    Description: Temperature coefficient of NdNbO4 microwave ceramic was adjusted to near zero by Bi substitutions. Abstract In the present work, Bi3+ was used to substitute for Nd3+ in the NdNbO4 ceramic and pure fergusonite solid solution was formed within 20 mol. % substitutions. Microwave dielectric permittivity of the (Nd1‐xBix)NbO4 (x ≤ 0.2) ceramics increased linearly with x value due to the larger ionic polarizability of Bi3+ than Nd3+. Excellent microwave dielectric properties with a permittivity (εr) ~22.5, a Qf (Q = quality factor, f = resonant frequency) ~50 000 GHz, and a TCF ~−9 ppm/°C were obtained in the (Nd0.9Bi0.1)NbO4 ceramic. This method might work in other fergusonite‐type rare‐earth ortho‐niobates.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Wiley
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  • 9
    Publication Date: 2016-06-08
    Description: The development of micro-/nano-scaled energy harvesters and the self-powered sensor system has attracted great attention due to the miniaturization and integration of the micro-device. In this work, lead-free NaNbO3 piezoelectric nanofibers with a monoclinic perovskite structure were synthesized by the far-field electrospinning method. The flexible active humidity sensors were fabricated by transferring the nanofibers from silicon to a soft polymer substrate. The sensors exhibited outstanding piezoelectric energy-harvesting performance with output voltage up to 2 V during the vibration process. The output voltage generated by the NaNbO3 sensors exhibited a negative correlation with the environmental humidity varying from 5% to 80%, where the peak-to-peak value of the output voltage generated by the sensors decreased from 0.40 to 0.07 V. The sensor also exhibited a short response time, good selectively against ethanol steam, and great temperature stability. The piezoelectric active humidity sensing property could be attributed to the increased leakage current in the NaNbO3 nanofibers, which was generated due to proton hopping among the H3O+ groups in the absorbed H2O layers under the driving force of the piezoelectric potential.
    Electronic ISSN: 1424-8220
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Published by MDPI Publishing
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  • 10
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    American Physical Society (APS)
    Publication Date: 2015-04-18
    Description: Author(s): Xianhao Xin and Di Zhou We investigate theoretically the nonequilibrium transport properties of a topological insulator quantum dot (TIQD) in the Coulomb blockade and Kondo regime. An Anderson impurity model is applied to a TIQD system coupled to two external leads, and we show that the model realizes the spin-orbital Kond... [Phys. Rev. B 91, 165120] Published Fri Apr 17, 2015
    Keywords: Electronic structure and strongly correlated systems
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
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