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Over the past decades, Na0.5Bi0.5TiO3 (NBT)-based ceramics have received increasing attention in energy storage applications due to their high power density and relatively large maximum polarization. However, their high remnant polarization (Pr) and low breakdown field strength are detrimental for their practical applications. In this paper, a new solid solution (1−x)Na0.5Bi0.5TiO3–xCaHfO3 (x = 0.04, 0.08, 0.12, 0.16) was constructed by introducing CaHfO3 into NBT, and thus was prepared using a conventional solid-state reaction. With the addition of CaHfO3, the disorder of the structure increased, A-site vacancies formed, and thus oxygen vacancies were suppressed due to the replacement of the Na+ by Ca2+, resulting in the enhanced relaxation behavior and the reduced Pr, the refined grain, and improved breakdown strength. Furthermore, an optimal recoverable energy storage density (Wrec) of 1.2 J/cm3 was achieved in 0.92Na0.5Bi0.5TiO3–0.08CaHfO3 ceramics under the breakdown strength of 140 kV/cm, which is mainly attributed to the resultant defect of Na+ vacancy. [ABSTRACT FROM AUTHOR]

When asphalt pavement is in practical use, it is prone to cracking and other diseases due to the long-term effects of load and climate and the restricted self-healing properties of the asphalt material. In order to improve the properties and durability of asphalt pavement, we introduced disulfide bonds into polyurethane (PU) in this study. We prepared polyurethane-modified asphalt (PUA) containing dynamic disulfide covalent bonds using polytetrahydrofuran (PTMG), polyethylene adipate (PEA), and hydroxyl-terminated polybutadiene (HTPB) as soft segments. Subsequently, the rheological properties, healing performance, and microstructure of the PUA were studied. The results indicated that the PU with disulfide bonds was integrated into the asphalt and had good dispersity. A cross-linked network structure formed between them. PUA with HTPB as the soft segment had excellent high-temperature deformation and low-temperature cracking resistance and a prominent advantage in durability. In comparison, PUA synthesized with PEA had better high-temperature performance and fatigue resistance, and PUA synthesized with PTMG had considerable low-temperature properties and stability. The disulfide bonds had a positive impact on the high-temperature performance, aging resistance, and healing properties of PUA through constant dynamic exchange and topological rearrangement effects. This study provides a reference for the preparation of PUA with ideal self-healing ability and has instructive significance for the selection of soft segment materials for synthesizing PUA. [ABSTRACT FROM AUTHOR]

The surface texture of asphalt pavement has a significant effect on skid resistance performance. However, its contribution to the performance of skid resistance is non‐homogeneous and subjects to local validity. There are also a few deep learning models that take into account the effective contact texture region. This paper proposes a convolutional neural network model based on the effective contact texture region, containing macro‐ and micro‐scale awareness sub‐modules. In this study, the asphalt mixture with varying gradations was designed to accurately obtain the effective contact texture region. Then, the textures were disentangled into macro‐ and micro‐texture scales by applying the fast Fourier transform and fed into the model for training. Finally, the area of effective contact texture region was calculated, and the effective contact ratio parameter was then proposed using the triangulation algorithm. The results showed that the effective contact texture area of pavement varies by the asphalt mixture type. The effective contact ratio parameter exhibited a significant positive correlation (Pearson correlation coefficient is 0.901, R2= 0.8129) with skid resistance performance and was also influenced by key sieve aggregate content from 2.36 to 4.75 mm. The data of effective contact texture region following disentanglement significantly released the model performance (the relative error dropped to 1.81%). The model exhibited improved precision and performance, which can be utilized as an efficient, non‐contact alternative method for skid resistance analysis. [ABSTRACT FROM AUTHOR]

To reduce vehicle exhaust gas pollution in transport-intensive roadways and tunnels, six types of photocatalytic asphalt binders were designed using graphite-phase carbon nitride (g-C3N4) and nanoscale titanium dioxide (nano-TiO2) particles. In this paper, the rheological behaviors and fatigue life of the nano-TiO2-modified asphalt binder (TiO2-MA) and g-C3N4-modified asphalt binder (C3N4-MA) were investigated. NO degradation capacity of six types of photocatalytic asphalt binders was characterized under visible light conditions. The results showed that TiO2-MA had more excellent rheological behaviors and rutting resistance than C3N4-MA. In addition, 4 wt% nano-TiO2 markedly improved the rheological behaviors and rutting resistance of MA compared to other dosages. TiO2-MA exhibited higher fatigue resistance. The fatigue life of TiO2-MA with 4 wt% nano-TiO2 was increased to 234.1% at 2.5% strain and 242.5% at 5% strain, respectively, compared to base asphalt binder (BA). C3N4-MA had better NO degradation capacity than TiO2-MA. Meanwhile, the NO degradation efficiency of C3N4-MA reached 17.8% with 5 wt% g-C3N4. [ABSTRACT FROM AUTHOR]

Na0.5Bi0.5TiO3 (NBT)-based ceramics are promising lead-free candidates for energy-storage applications due to their outstanding dielectric and ferroelectric properties derived from large polarization. However, the high coercive field and large remnant polarization are unfavorable for practical applications, and thus NBT-based ceramics with relaxation behavior via doping/forming solid solutions with other elements/components have been widely studied. In this work, BaTiO3 (BT) was introduced to the 0.94Na0.5Bi0.5TiO3-0.06Bi(Mg2/3Nb1/3)O3 system by a conventional solid-state reaction to form a homogeneous solid solution of 0.94[(1−x)Na0.5Bi0.51TiO3-xBaTiO3]-0.06Bi(Mg2/3Nb1/3)O3 (BNT-100xBT-BMN). As the BT content increased, the proportion of the rhombohedral R3c phase increased while that of the tetragonal P4bm phase decreased, leading to the maximum Pmax (38.29 μC/cm2) and Eb (80 kV/cm) obtained in BNT-7BT-BMN (x = 0.07) composition. Specifically, the optimal energy storage properties of Wrec ~ 1.02 J/cm3 and η ~ 62.91% under 80 kV/cm were obtained in BNT-7BT-BMN ceramics, along with good temperature stability up to 200 °C, which are promising factors for future pulse power applications. [ABSTRACT FROM AUTHOR]

The recombination of charge carriers in photocatalysts is one of the main factors restricting photocatalytic performance. In this paper, the NaNbO3/g-C3N4 heterojunction photocatalyst was prepared by a simple ultrasonic mixing approach and applied to obtain superior piezo-photocatalytic activity. The results showed that the NaNbO3 nanowires were attached to the g-C3N4 surface for efficient degradation of rhodamine B (RhB). Through the synergistic action of visible-light irradiation and ultrasonic vibration, the RhB solution could be degraded within 30 min by 5% NaNbO3/g-C3N4 heterojunction. The reaction rate constant (k) of 5% NaNbO3/g-C3N4 heterojunction is 2.7 times that of pure g-C3N4. Moreover, quenching tests and electronic spin resonance (ESR) indicated that ·O2− was the primary active species for RhB degradation. The enhanced photocatalytic performance was attributed to the formation of the heterojunction at the NaNbO3/g-C3N4 interface. Furthermore, the piezoelectric field that originated from the bending deformation of NaNbO3 nanowires effectively promoted charge carriers separation efficiency in the NaNbO3/g-C3N4 heterojunction. [ABSTRACT FROM AUTHOR]

Higher yields of the aminated compounds were achieved in the nuclear amination and side-chain amination reactions in the reaction of 2,3-diiodo-5,6-dimethylhydroquinone or 2,3-dimethylhydroquinone with primary and secondary amines. X-ray crystallographic data on the structures of these products also represent the first crystallographic proof of the methyl group replacement in nuclear amination. A new palladium-catalyzed synthesis of an indolequinone derivative from the reaction of 2,3-diiodo-5,6-dimethylhydroquinone and i-Pr2NH is also reported.

Water pollution caused by dye wastewater is a potential threat to human health. Using photocatalysis technology to deal with dye wastewater has the advantages of strong purification and no secondary pollution, so it is greatly significant to look for new visible-light photocatalysts with high photocatalytic ability for dye wastewater degradation. Semiconductor photocatalyst silver phosphate (Ag3PO4) has high quantum efficiency and photocatalytic degradation activity. However, Ag3PO4 is prone to photoelectron corrosion and becomes unstable during photocatalysis, which severely limits its application in this field. In this study, a tubelike g-C3N4/Ag3PO4 heterojunction was constructed by the chemical precipitation method. An Ag3PO4 nanoparticle was loaded onto the surface of the tubelike g-C3N4, forming close contact. The photocatalytic activity of the photocatalyst was evaluated by the degradation of RhB under visible-light irradiation. The tubelike g-C3N4/Ag3PO4-5% heterojunction exhibited optimal photocatalytic performance. In an optimal process, the degradation rate of the RhB is 90% under visible-light irradiation for 40 min. The recycling experiment showed that there was no apparent decrease in the activity of tubelike g-C3N4/Ag3PO4-5% heterojunction after five consecutive runs. A possible Z-type mechanism is proposed to explain the high activity and stability of the heterojunction. [ABSTRACT FROM AUTHOR]

Ba0.6Sr0.4TiO3 (BST) ceramic materials have been widely used in the field of multilayer ceramic capacitors. Surface modification through the surface coating to form a heterogeneous layer could effectively improve the dielectric properties. In this work, BST powders were prepared by a co-precipitation method. The effects of reaction conditions on the microstructure of the BST powder were investigated. The reaction temperatures significantly affected the morphology of BST powder, and the rhombic-type particles were obtained with the reaction temperature around 80 °C. Meanwhile, the BST@Fe2O3 was prepared by the chemical precipitation method using BST powders with rhombic-type microstructure as "core", and the so-called "core-shell" microstructure was confirmed in the BST@Fe2O3 powder. Then, BST@x wt%Fe2O3 (x = 2.5, 5, 7.5, and 10, denoting the different content of Fe2O3) ceramics were further prepared, and the influence of "core-shell" structure on the phase structure, microstructure, and dielectric properties was investigated. With the increasing of Fe2O3 content, the ferroelectric–paraelectric phase transition temperature shifts toward lower temperatures, and dielectric peaks gradually become broad and frequency-dependent, which may be due to inconsistent chemical composition from core to shell. [ABSTRACT FROM AUTHOR]