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Gd2O3:Eu3+@ CsPbBr3 QDs mesoporous hollow nanocomposites with good luminescent properties and high stability were built. Among which, the hollow Gd2O3:Eu3+ spheres and CsPbBr3 QDs were prepared by urea homogeneous precipitation and hot-injection method, respectively. Finally, the Gd2O3:Eu3+@ CsPbBr3 QDs shell-core compounds were constructed through mechanical stirring. The structure, morphology, stability and luminescent properties were studied by the comprehensive of Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry/thermogravity (DSC/TG), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence excitation/photoluminescence (PLE/PL) and life decay tools. Compared to the original CsPbBr3 QDs, Gd2O3:Eu3+@ CsPbBr3 QDs display better photostability, thermal stability and current stability. The resulting Gd2O3:Eu3+@ CsPbBr3 QDs composite exhibit good yellow emission. The Gd2O3:Eu3+@ CsPbBr3 QDs mixed silicone resin was directly coated on the blue LED chip, then the w-LED device with the color coordinate of (0.31, 0.32) was successfully assembled. The Gd2O3:Eu3+@ CsPbBr3 QDs compounds with excellent luminescent properties and stability are expected to be widely used in lighting and display areas.

We have fabricated a new perylene bisimide (PBI) folda-dimer (BPBI-CB-1) by tethering two PBI moieties to the ortho-carbon positions of a carborane unit. The synthesized compound adopted distinct c...

In this letter, high-performance p-NiO/-Ga2O3 heterojunction diodes (HJDs) with composite terminal structures, a p-NiO junction termination extension (JTE), and a small-angle beveled field plate (BFP), are demonstrated. By implementing a p-NiO JTE structure, the optimal breakdown voltage (Vbr) of -Ga2O3 HJD increase from 955 V to 1945 V, and the integration of the small-angle BFP further boosts the breakdown voltage up to 2410 V. An 80-nm thin p-NiO layer is adopted in the heterojunction to reduce the specific on-resistance (Ron,sp), while the composite terminal structures have little effect on Ron,sp, due to the super-large lateral spread resistance. The -Ga2O3 HJD with composite terminal structures achieves a low Ron,sp of 1.12 mcm2, yielding the highest direct-current Baligas figure-of-merit (FOM = Vbr2/Ron,sp) among all reported -Ga2O3 diodes with a value of 5.18 GW/cm2, which is about 15% of theoretical value. These results suggest that the electrical field engineering with composite terminal structure is a viable and effective technological strategy to enable the realization of -Ga2O3 bipolar power rectifiers.

Scalable fabrication of membrane substrates, having high strength, customizable pore size, high gas and water permeation, has been key issue in recent years due to the rapid growth of engineered separation processes. This work provides a novel fabrication method for porous Al2O3 membrane substrates (PAS) by using suspension emulsions as pore forming agents and gel-tape-casting as a shaping method. The substrates displayed a smooth surface and a porous internal structure. By adjusting the volume ratio of water and oil from 1:1 to 1:4, the average pore size increased from 0.53 to 1.06 μm. Moreover, the porosity increased from 50.7% to 75.8%, in contrast, the bending strength decreased from 46.7 ± 1.5 to 17.3 ± 1.1 MPa. In addition, the permeability of the N2 and water was improved from 8.13 × 105 to 5.10 × 106 L m−2 h−1 bar−1 and 5.02 × 103 to 1.84 × 104 L m−2 h−1 bar−1 respectively and as a result, this can qualify the membranes for a wide range of applications.

Ti3C2Tx, a member of the MXene, has attracted extensive interest because of its high conductivity, unique two-dimensional (2D) structure and intrinsic pseudocapacitance for supercapacitors. Flexible and freestanding Ti3C2Tx films are promising electrodes for functioned supercapacitors used in wearable and portable electronic devices. However, the severe self-restacking of 2D Ti3C2Tx nanosheets restraints their practical application. Herein, freestanding and flexible three-dimensional (3D) cross-linked Ti3C2Tx-Ca-SA (sodium alginate) films with expanded Ti3C2Tx interlayer spacing are reported. The expanded interlayer spacing allows more electrolyte ions to quickly intercalate providing more intercalation pseudocapacitance, while the 3D cross-linked microstructure ensures a continuous conductive network facilitating charges transport. Attributing to the unique structure, the Ti3C2Tx-Ca-SA film delivers an outstanding areal capacitance (633 mF cm-2 at 5 mV s-1). Meanwhile, the assembled all-solid-state pseudocapacitor shows good flexibility and capacity stability under various bending conditions. The device exhibits a high energy density up to 12.6 µWh cm−2 at the power density of 375 µW cm−2 and excellent cycling stability, which are much better than prior reported state-of-the-art supercapacitors. This research exploits a simple method to optimize the structure of MXene as state-of-the-art electrodes for high-performance flexible energy-storage devices.

Lithium-sulfur (Li-S) batteries have attracted extensive attention in the field of energy storage due to their high energy density and low cost. However, conundrums such as severe polarization, poor cyclic performance originating from shuttle effect of lithium polysulfides and sluggish sulfur redox kinetics are stumbling blocks for their practical application. Herein, a novel sulfur cathode integrating sulfur and polyvinylpyrrolidone(PVP)-derived N-doped porous carbon nanofibers (PCNFs) with embedded CoF3 and YF3 nanoparticles are designed and prepared though the electrostatic blowing technology and carbonization process. The unique flexible PCNFs with embedded polar CoF3 and YF3 nanoparticles not only offer enough voids for volume expansion to maintain the structural stability during the electrochemical process, but also promote the physical encapsulation and chemical entrapment of all sulfur species. Moreover, the uniform distribution of YF3/CoF3 nanoparticles also can expose more binding active sites to lithium polysulfide and present more catalytic sites to the greatest extent. Therefore, the assembled cells with the prepared cathode exhibited stable performances with an outstanding initial capacity of 1055.2 mAh g−1 and an extended cycling stability of 0.029% per cycle during the 300 cycles at 0.5C. Even at a high sulfur loading of 2.1 mg cm−2, The YF3/CoF3 doped-PCNFs exhibited a high discharge specific capacity of 1038 mAh g−1, and the decay rate is also as low as 0.05% over 1000 cycles. This work shares a convenient and safe strategy for the synthesis of multi-dimension, dual-functional and stable superstructure electrode for advanced Li-S batteries.

Hypothesis Transparent superhydrophilic coatings are very promising in various scenarios. Appropriate fabrication of colloid coatings with superhydrophilicity both in air and under oil would enlarge their application potential in anti-oil fouling and facilitate anti-fogging of transparent surfaces. Experiments The Barite colloid was obtained from a one-step precipitation method and was transferred onto glasses to prepare transparent coatings with different thicknesses simply by dip-coating. Then, the impact of thickness on wettability and property was studied through the investigation of wettability in various phase, anti-crude oil fouling performance and anti-fogging ability. Findings Similar surface morphology and roughness of these coatings were achieved and all the coated surfaces showed ultra-hydrophilicity both in air and under oil. Moreover, the hydrophilicity in air and under oil was found to deteriorate with the decrease of coatings’ thickness and dual superhydrophilicity could be achieved on thick coatings. More importantly, excellent anti-crude oil fouling property and durable anti-fogging ability were realized on these transparent coatings with dual superhydrophilicity.

The inert sites of Prussian Blue Analogue (PBA) seriously affected its electrocatalytic activity and application, how to activate inert sites in PBA to fulfill effective oxygen evolution reduction (OER) is a major challenge. Herein, Mo substituted Fe sites and S doped in inert PBA were designed and synthesized by hydrothermal method to enhance structural stability and OER activity. PBA-SMo/NF shows the optimum activity with a low overpotential of 252 and 294 mV for harvesting current density 20 and 100 mA cm−2, respectively, and exhibits excellent durability under high current density. Theoretical calculation of H2O adsorption energy and Bader charges reveals that Mo sites in PBA-SMo possess favourable H2O adsorption kinetics. More important, Gibbs free energy diagram and DOS show PBA-SMo have lower energy barriers for OER and better conductivity. This work provides a kind of guidance for the design and optimization of PBA for broad applications.

The waxberry-like mixed-phase TiO2 hollow microstructures (WMTHMs) are controllably prepared via a topotactic synthetic method, involving the synthesis of monodispersed CaTiO3 precursors by a solvothermal method and subsequently transforming them into TiO2 through a Na2EDTA-assisted ion-exchange process. The ratio of anatase-rutile is adjustable, and the two phases are connected well with each other. WMTHMs are composed of radially aligned nanorods, speeding up the electron transport. The optimum WMTHMs sample shows a specific surface area of 68.05 m2/g and exhibits an excellent light scattering capacity. The cell based on WMTHMs light scattering layer obtained an optimal efficiency of 9.12%. The improvement of cell efficiency is mainly attributed to the high specific surface area, the efficient light scattering, the appropriate ratio of anatase-rutile, the staggered bandgap structure, and the convenient one-dimensional electron transport channel.

The underlying structural origin of magnetic properties is still elusive in Fe-based amorphous alloys. In this study, distinctive soft magnetic properties were developed in Fe76Si9B10P5 amorphous ribbons through systematic design of annealing process. Combining with synchrotron radiation, high-resolution transmission electron microscopy and first principle ab initio molecular dynamic simulation, it is found that the atomic structural evolution both in short range order and medium range order is responsible for the magnetic softness at proper annealing temperature. In short range, formation of separated and densely coordinated Fe-metalloid clusters is instigated to adapt energy minimization, resulting in strengthening of ferromagnetic exchange interaction locally. In medium range, a homogeneous exchange-coupling from the uniformly strong and weak ferromagnetic regions is generated, which significantly weakens magnetic heterogeneity and leads to the excellent magnetic softness. Our findings may provide an effective/promising pathway to modulate the magnetic properties for Fe-based amorphous alloys, and give a comprehensive and quantitative understanding of the structure-properties relationship in amorphous materials.

Thermal metamaterials are a class of artificial composite structures with special thermal conduction properties. Due to the existence of complex multi-phase materials arrangement and interfaces in the thermal metamaterials, an efficient and accurate numerical method is on-demand to predict their temperature distribution and performances. In this paper, we studied the edge-based smoothed finite element method (ES-FEM) for simulating the heat conduction of thermal metamaterials in both steady-state and transient circumstances. Benefit from the adopted smoothing technique, the numerical errors caused by the complex interface are further eliminated. The most significant advantage of the proposed method is that one can directly use the automatically generated coarse triangle mesh to reduce the computational costs while ensuring accuracy. Two numerical examples are presented, in which two typical thermal metamaterials, the thermal cloak and thermal concentration device, are considered respectively in both steady-state and transient cases. The results illustrate that the ES-FEM based approach has good efficiency and accuracy in the heat conduction simulation of the thermal metamaterials.

This paper proposes the use of a novel modular joint to overcome the shortcomings of existing aluminium alloy gusset joints. Bearing capacity tests are performed on the bearing capacity of four sets of joints in the early stage, and the force characteristics and failure mechanism of the novel modular joint are summarized. On this basis, this study conducts theoretical research on the design method of this new type of joint. According to the four failure modes that occurred in the experiment, namely, the bending failure of the aluminium alloy beam, the shear failure of the bolt group, the tensile and shear failure of the modular unit, and the local buckling failure of the unit bottom plate, a formula for calculating the ultimate bearing capacity of each component is provided. According to the working mechanism of modular joints, theoretical formulas for the ultimate flexural bearing capacity and initial stiffness of the joints are derived according to the three-part bending moments produced by each component. Based on a power function model, a prediction formula is fitted to the bending moment-rotation curve of the new joint and compared with the measured values of the joint and 22 numerical models. The results show that the average errors of the two sets of theoretical formulas are only 2.85% and 4.5%, fully verifying their validity and reliability. The results provide a theoretical basis for the engineering design and application of this type of joint.

Corundum–MgAl2O4 spinel-based castables bonded with calcium aluminate cement (CAC) and hydratable alumina (HA) were studied to evaluate their performance as gas purging plugs in steel ladles. The thermomechanical properties and corrosion behavior of the as-prepared castables were investigated. The results indicate that the cold crushing strength and modulus of rupture of castables bonded with CAC and HA after firing at 1600 °C are in the same levels of 160 and 32 MPa, respectively. The sample bonded with HA showed lower permanent change of − 0.23 pct and slag infiltration index of 0.07 compared with CAC-bonded samples (> 0.34 pct and > 0.36, respectively), suggesting the better volume stability and corrosion and slag infiltration resistance to CaO–SiO2–Fe2O3–Al2O3-based slag of HA-bonded castable. The in situ-formed MgAl2O4 spinel changed the corrosion and infiltration indices of CAC-bonded castable to 0.09 and 0.39, respectively, compared with castable without in situ MgAl2O4 spinel, indicating that the corrosion resistance was improved but the infiltration resistance was reduced by the in situ-formed MgAl2O4 spinel.

Transition metal dichalcogenides, especially MoS2-based materials, have been actively investigated for application as high-performance electrode materials for metal-ion batteries. To further improv...

The uniaxial compression tests were conducted on granite samples with different joint dip angles to more favorably explore the influences of the nonconsecutive joint on mechanical properties and deformation characteristics of the rock mass. The stress-strain curves, deformation and strength characteristics, and energy evolution process of the samples were analyzed. Numerical simulation using particle flow code (PFC) is employed to study the crack propagation process. The mode of jointed and fractured rock was investigated. The research results showed a significant reduction in both the peak strength and elastic modulus of jointed samples compared with intact ones: the peak strength and elastic modulus drop to the minimum at the joint dip angle of about 45°, especially for the peak strength, which takes up about 55% of the intact samples. The fractured samples’ total energy, elastic strain energy, and dissipated energy during the uniaxial compression drop significantly relative to intact samples. The proportion of the fracture modes varies with different joint dip angles, in which the ratio of shear cracks grows at first and then declines, with the highest balance at the dip angle of 45°. The damage stress’s sensitivity to the dip angle change is greater than that of the peak stress, with reduction amplitude more extensive than the latter.

Three kinds of particle size products (i.e., 2.5, 5.0, and 10 μm) synthesized by multi-heat source method and separated by air were selected as the raw materials to study the purification by heat treating at 1800 °C and 2100 °C for 2 h, respectively. Chemical analysis, inductively coupled plasma-optical emission spectrometry (ICP-OES), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and particle size test were used to compare the changes of purity, structure, morphology, and particle size before and after heat treatment. The results show that the impurities of β-SiC powders with three sizes can be effectively removed after heat treatment. A higher temperature favors a better purification effect. The β-α phase transformation occurs at 2100 °C. The smaller the particle size, the higher the degree of phase transformation and the larger the product particle size. In order to maintain the crystal phase and particle size of β-SiC, 1800 °C should be selected for purification. The purity of β-SiC powder after treatment can reach more than 99% and makes great potentials for preparing semiconductive composites.

Integrating multiple photosensitive properties into an “all-in-one” photosensitizer (PS) shows great promise for the treatment of cancers owing to synergistic effect among them. However, the development of such PSs, especially those that need a single laser source, remains a challenge. Herein, we report an orchestration of electron donors and acceptors in a propeller-like pentad, PBI-4Cz, where four carbazole (Cz) units are covalently linked to the ortho-positions of the perylene bisimide (PBI) core. Strong intramolecular donor-acceptor interaction significantly quenches the luminescence and largely extends the absorption spectra to near-infrared region. Excited-state dynamics investigated via femto- and nano-second transient absorption spectroscopy revealed exclusive charge separation of the PBI-4Cz within initial 0.5 ps when photoexcited regardless of which intermediate is involved. Energy dissipation of the resulting charge-separated state (PBI•−-4Cz•−) is subjected to the toggle between intersystem-crossing toward excited triplet states and charge recombination toward ground states. Relative importance of the two pathways can be tuned by micro-environmental polarity, which endows PBI-4Cz remarkable performances of singlet-oxygen generation (>90.0%) in toluene and photothermal conversion (∼28.6%) in DMSO. Harnessing intrinsic photostability and excited-state processes of heavy-atom-free PBI derivatives not only holds a promise for multifunctional phototheranostics, but also provides a prototype for designing high-performance PSs with tunable photoconversion pathways.

A simple hydrothermal method has been developed to prepare a WO3 nanorod array@Prussian blue (WO3@PB) composite material on FTO substrates with core–shell heterogeneous structures, aiming to enhanc...

The dispersion and dielectric attenuation characteristics of a double-staggered grating waveguide (DSGW) are two crucial features related to the output characteristics of a sheet-beam traveling-wave amplifier and have been previously studied by using theoretical analysis and simulations. In this work, these two characteristics are both experimentally studied. Two ${H}$ -band (220–325 GHz) DSGW circuit prototypes with and without dielectric attenuators made of the BeO-TiO2 composite ceramic were machined by using nanocomputer numerical control milling. Experimental studies of the dispersion property were performed successfully where the measurement results were in good agreement with those predicted by simulations, exhibiting a wide passband of 70 GHz (230–300 GHz). The measured transmission coefficient has been decreased from −5 to −55 dB after the introduction of dielectric attenuators, experimentally verifying the feasibility of the adopted methodology. The effects of the variations of dispersion relation and transmission loss on the beam-wave interaction stability were also investigated.

Thermocline sensible heat storage (SHS) systems are usually utilized in parabolic trough solar power systems. Liquid lead–bismuth eutectic (LBE) is a potential heat transfer medium for SHS systems, but its influences on the performances of SHS systems are rarely studied. In this study, a simulation model of thermocline SHS tank using liquid LBE as the heat transfer fluid is established, and the influences of initial cold and hot LBE temperatures on the operation and mechanical performances of the tank are estimated. The results reveal that when the liquid LBE is used as the heat transfer fluid, the SHS tank can operate stably. The initial cold LEB temperature has almost no influence on both the total heat storage and heat release durations of the tank, while the initial hot LBE temperature has proportional relationships with the total heat storage and heat release durations. The heat storage performance as well as the heat release behavior of the tank can be improved by increasing the initial cold LBE temperature, or by decreasing the initial hot LBE temperature. The peak maximum mechanical stress of the tank can be decreased by increasing the initial cold LBE temperature, or by decreasing the initial hot LBE temperature.

Structure and composition of materials have an irreplaceable effect on their electromagnetic wave absorption ability. In this study, a series of heterogeneous interface reconstruction products (ZnCo2O4-CoO@N/C, ZnO-Co@N/C and Co3ZnC-Co@N/C) was obtained by calcining the prepared ZnCo2O4@ZIF-67(MOF) heterogeneous precursor composite material at different temperatures. The results show that, ZnCo2O4-CoO@N/C shows excellent reflection loss (RL) of −17.82 dB with the maximum effective absorption bandwidth (EAB) of 3.77 GHz, ZnO-Co@N/C shows RL of −62.7 dB with EAB of 5.75 GHz and Co3ZnC-Co@N/C shows RL of −67.97 dB with EAB of 5.23 GHz. The results further confirmed that the absorbing materials with multi-heterogeneous interfaces can achieve better impedance matching and reflection loss through multiple reflections and scatterings as well as the synergistic effects of conductive loss, dielectric loss and magnetic loss. The research results also show that the composition of the multi-heterointerface absorbing material has an important influence on its absorption performance. Therefore, this work provides an important thought for the design and preparation of high-performance multi-heterointerface absorbing materials.

This paper presents a comparative analysis of thermal and mechanical behaviors of the thermally stratified heat storage system using three different heat transfer materials, which are the binary nitrate salt, ternary nitrate salt and liquid lead–bismuth eutectic (LBE) alloy. The discharging behaviors of the tank using three different heat transfer materials are investigated by using both the algebraic and numerical models. For all the three materials, the algebraic results are consistent with the simulation ones. During the discharging process, in comparison, the thermal stratification thickness of the tank using the binary nitrate salt is relatively smaller, which can lead to a better discharging performance. The comparison results of expanding behaviors of the standby tank reveal that the thermal stratification thicknesses of tanks using the three different heat transfer materials all increase with the standby time increased. Compared with the other two materials, the thermal stratification thickness of the tank using the binary nitrate salt is the smallest at the same standby time. The comparison results of mechanical behaviors of the tank demonstrate that the maximum mechanical stress of the tank using the liquid LBE is the greatest, while the tank using the molten salts can have better mechanical properties.

Fluorine-doped graphene quantum dots have unique chemical bonds and charge distribution, which can bring unexpected properties compared to other common atom-doped graphene quantum dots. In the present work, fluorine and nitrogen co-doped graphene quantum dots (F, N-GQDs) are synthesized from levofloxacin via a simple hydrothermal method. Systematic studies demonstrate that F, N-GQDs can emit various fluorescence with the wavelength ranging from blue to green by dispersing F, N-GQDs into different solvents. Moreover, multi-color fluorescence is available by simply changing the concentration of F, N-GQDs. In addition to these unique characteristics, F, N-GQDs also exhibit a sensitive fluorescence response to tetracycline with an ultralow detection limit of 77 nM in water. Because of high photostability and high quantum yield, the F, N-GQDs are exploited as a unique invisible ink, which is printable and writable on paper. Meanwhile, based on the solvatochromism of F, N-GQDs, we realized the color adjustable fluorescent ink. Finally, large-area flexible multi-color fluorescent films are realized. Our synthesized F, N-GQDs, with tunable fluorescence in wavelength and intensity, have numerous opportunities for optical molecular sensors, information security, flexible optics, and others.

Solar steam generation is considered to be an effective strategy to alleviate the global water shortage problem. Therefore, exploring highly efficient and thermal stability photothermal conversion materials is highly essential and urgent. In this work, we develop a three-dimensional (3D) oxygen vacancy-rich WO3 with ‘‘nanorod array grown on nanosheet array” unique architecture decorated on Ni foam (denoted as WO3−x/NF) through a simple and effective hydrothermal method followed by an annealing route, which is applied as light-absorbing material. The 3D hierarchical porous unique structure of the WO3−x/NF evaporator can supply a channel steam escaping and enhance the light trapping due to the multi-scattering effect, and the localized surface plasmon resonance (LSPR) effects of WO3−x also contribute to increase the light absorption in the full solar spectrum. The as-prepared WO3−x/NF evaporator reveals a high solar absorption (95%), an evaporation rate of 1.50 kg m−2 h−1 under one sun illumination, and a light-to-heat conversion efficiency of about 88%, as well as stable salt-resistance performance. The water purification results show that WO3−x/NF evaporator has a significant effect on seawater desalination without significant salt accumulation and purification of heavy metal wastewater. Furthermore, the first-principles calculations reveal that WO3 with oxygen vacancies has a narrower bandgap, which is more conducive to absorb solar energy from the whole spectrum. This work can provide a new avenue toward the design of other high photothermal conversion system.

The indoor low-concentration formaldehyde (HCHO) removal in cobalt-based catalysts is still a “hot potato”. In this work, metal–organic-frameworks (MOF)-derived and Zinc (Zn)-modulated new cobalt nanoparticles catalyst (CZ-Co@NC-800) was designed and prepared. The CZ-Co@NC-800 performed outstanding elimination activities for ~1 ppm HCHO at 25 °C. In the static test condition, it achieves complete HCHO removal in 3 h at a relative humidity (RH) of ~55%. Moreover, 90.18% HCHO removal ratio is held after five recycle tests. In the dynamic test condition, it remains the characteristic to eliminate around 95.89% of HCHO within 8 h under an RH of ~55% and a gas hourly space velocity (GHSV) of ~150,000 mL·h−1g−1. Such advanced results should be ascribed to large specific surface area bringing about more cobalt active sites; and it is also because residual Zn metal affects the electronic structure of CZ-Co@NC-800 and enhance the surface charge transfer rate, thus the activation and dissociation ability of oxygen is promoted. Besides, a short HCHO reaction path over CZ-Co@NC-800 which was clarified by the In situ DRIFTs is also a reason for excellent catalytic performance. This work represents a crucial addition to expand the family of cobalt-based catalysts for indoor HCHO elimination.

The influence of induction heating on the grain boundary character distribution (GBCD) in near-surface regions of a cold-rolled Nickel-based superalloy was researched. After induction heating, most of low-Σ coincidence site lattice (CSL) boundaries were Σ3 boundaries, which were mainly formed via the growth accident model. Moreover, the grain structures evolution during induction heating had a great influence on the evolution of GBCD. At the low strain of 0.1, both the fraction of Σ3 boundaries and grain size increased with the increasing temperatures, while the former was closely related to the better development of grain-clusters at the higher temperature. In addition, the coherent Σ3 boundaries were easier to be formed at the higher temperature during induction heating, owing to their low interface energy and mobility. At the large strain of 0.5, the fraction of Σ3 boundaries also increased with the increasing temperatures, but the grain size exhibited the opposite trend, which was closely related to the well development of static recrystallization (SRX) behaviors. Meanwhile, there was a “symbiotic relationship” between the SRX grains and Σ3 boundaries during induction heating. Through the electrochemical corrosion tests, it was proved that induction heating can contribute to the improvement of corrosion properties of superalloys via increasing the fraction of Σ3 boundaries, while the best corrosion resistance appeared in the samples treated at 800 °C with the strain of 0.5. Moreover, the evolution of both Σ9 and Σ27 boundaries was also closely related to strains and induction heating temperatures, but their fractions were less than 4%.

The rational design of oxygen vacancies and electronic microstructures of electrode materials for energy storage devices still remains a challenge. Herein, we synthesize nickel cobalt-based oxides nanoflower arrays assembled with nanowires grown on Ni foam via the hydrothermal process followed annealing process in air and argon atmospheres respectively. It is found that the annealing atmosphere has a vital influence on the oxygen vacancies and electronic microstructures of resulting NiCo2O4 (NCO-Air) and CoNiO2 (NCO-Ar) products, which NCO-Ar has more oxygen vacancies and larger specific surface area of 163.48 m2/g. The density functional theory calculation reveals that more oxygen vacancies can provide more electrons to adsorb -OH free anions resulting in superior electrochemical energy storage performance. Therefore, the assembled asymmetric supercapacitor of NCO-Ar//active carbon delivers an excellent energy density of 112.52 Wh/kg at a power density of 558.73 W/kg and the fabricated NCO-Ar//Zn battery presents the specific capacity of 180.20 mAh/g and energy density of 308.14 Wh/kg. The experimental measurement and theoretical calculation not only provide a facile strategy to construct flower-like mesoporous architectures with massive oxygen vacancies, but also demonstrate that NCO-Ar is an ideal electrode material for the next generation of energy storage devices.

Size reduction can generally enhance the surface reactivity of inorganic nanomaterials. The origin of this nano-effect has been ascribed to ultrasmall size, large specific surface area, or abundant defects, but the most intrinsic electronic-level principles are still not fully understood yet. By combining experimental explorations and mathematical modeling, herein we propose an electronic-level model to reveal the physicochemical nature of size-dependent nanomaterial surface reactivity. Experimentally, we reveal that competitive redistribution of surface atomic orbitals from extended energy band states into localized surface chemical bonds is the critical electronic process of surface chemical interactions, using H2O2-TiO2 chemisorption as a model reaction. Theoretically, we define a concept, orbital potential (G), to describe the electronic feature determining the tendency of orbital redistribution, and deduce a mathematical model to reveal how size modulates surface reactivity. We expose the dual roles of size reduction in enhancing nanomaterial surface reactivity—inversely correlating to orbital potential and amplifying the effects of other structural factors on surface reactivity.

In this work, the thermal stability of nanocrystalline (NC) AZ31/TiB2 magnesium matrix composites was investigated, while the microstructure evolution and mechanical properties were analyzed. The results indicated the AZ31/TiB2 still maintained NC structure after annealing at 350 °C for 180 min. Even at the high annealing temperature of 400 °C and 450 °C for 180 min, their average grain size just reached about 124 nm and 155 nm, indicating excellent thermal stability. The TiB2 particles with sub-micron size uniformly distributed in Mg matrix had no change in size and no reaction with matrix during the annealing treatment. Due to the strong Zener pinning effect of TiB2 particles, the grain growth of Mg matrix at high temperature was effectively inhibited. Meanwhile, the solution and precipitation behavior of Al atoms were completed in a short time, due to the existence of many grain boundaries and structural defects. By calculation, the grain growth kinetics was described by the kinetics equation $$D^{8} - D_{0}^{8} = kt$$ and the activation energy Eg for grain growth was 131.6 kJ/mol, which was much higher than that of pure Mg (92 kJ/mol). Due to their excellent thermal stability, the decrease in both compressive yield strength and ultimate compressive strength was no more than 12.2% after annealing treatment. Even annealing at 450 °C for 180 min, the CYS and UCS of the samples were still above 283 MPa and 295 MPa, respectively.

Purpose The purpose of this study is to investigate the heat resistance and heat-resistant oxygen aging of 4-nitrophthalonitrile-etherified cardanol-phenol-formaldehyde (PPCF) to further use and develop the resin as the matrix resin of high-temperature resistant adhesives and coatings. Design/methodology/approach PPCF resin was synthesized by 4-nitrophthalonitrile and cardanol-phenol-formaldehyde (PCF). The structures of PPCF and PCF were investigated by Fourier transform infrared, differential scanning calorimetry and proton nuclear magnetic resonance. In addition, the heat resistance and processability of PPCF and PCF resins were studied by dynamic mechanical analysis, thermogravimetric analysis, scanning electronic microscopy (SEM), X-ray diffraction (XRD) techniques and rheological studies. Findings The results reveal that PPCF forms a cross-linked network at a lower temperature. PPCF resin has excellent resistance under thermal aging in an air atmosphere and that it still had a certain residual weight after aging at 500°C for 2 h, whereas the PCF resin is completely decomposed. Originality/value 4-Nitrophthalonitrile was introduced into PCF resin, and XRD and SEM were used to investigate the high temperature residual carbon rate and heat-resistant oxygen aging properties of PPCF and PCF resins.

ZnO nanomaterials with the stereochemical structure were becoming a research focus in the scope of photocatalytic materials, but the ZnO was sensitive to UV light rather than the solar light source, which considerably prohibited its extended application. ZnO nanomaterials coupled with other nanomaterials could generate the alternative composite heterojunction nanomaterials to promote the photocatalytic activity. Herein, we reported two facile and feasible synthesis methods to fabricate TiO2/ZnO cube nanocomposites and Ag/ZnO hollow spheres by hydrothermal reaction and chemical deposition, respectively. In this regard, these composited nanomaterials have been successfully fabricated with high purities, good morphology, and crystal structure. Noticeably, in contrast with TiO2/ZnO and Ag/ZnO bulk nanocomposites, the Ag/ZnO hollow spheres could offer the higher activity for RhB degradation under the visible light. Moreover, the photocatalytic performance of Ag/ZnO for RhB degradation could be improved synergistically, and the effect of RhB degradation was highest when the Ag mass ratio was modulated at 10% in the sample. Furthermore, it remained a high photocatalytic efficiency even after four cycles. This protocol provided an approvable approach to fabricate efficient photocatalysts with persistent photostability in the wastewater treatment process.

To study the effect of acid-heat coupled fracturing on the damage of coal pores and fractures, scanning electron microscope-energy dispersive spectrometry (SEM-EDS), mercury intrusion porosimetry (MIP) were used to analyze. The results of the study show that the acid-heat coupling effect not only changes the microscopic morphology and element composition of the coal sample, but also promotes the formation of a pore-fracture network within the coal, and the connectivity is significantly increased, which is conducive to the diffusion and migration of coalbed methane. The optimum acidification temperature for the experiment is 50 °C. SEM observed that the acid-heat coupling changed the local stress sensitivity of the coal body and weakens the strength of the coal body to form a fracture network. EDS analysis shows that the element distribution on the coal surface changes regularly with the increase of acidification temperature, and the reduction rate of mineral content on the coal surface is highest at 50 °C. MIP and fitting analysis show that the pore parameters of coal samples will increase with the increase of acid-heat coupling temperature, reaching a peak at 50 °C, and the acidification effect will be relatively slow after increasing the temperature. This research is of great significance for exploring the optimal acidification conditions of coal mines, reducing acidizing fracturing costs, and ensuring coal mine safety production.

Constructing electrocatalysts with plentiful active sites, great mass transfer ability, and high electrical conductivity is critical to realize efficient hydrogen evolution reaction (HER). Hierarchically porous cobalt phosphide/N-doped nanotubular carbon networks (CoP/NCNs) that have all the features were fabricated in this work. For the fabrication, the polymeric worm-like micelles (PWs) with a large aspect ratio were coated by a uniform nanolayer of Zn-Co zeolitic imidazolate frameworks (Zn-Co-ZIFs) on their surface, resulting in the hybrid nanofibers PWs@Zn-Co-ZIFs (HPWs). Inheriting the randomly curved and entanglement properity of PWs, the rigid HPWs formed hybrid networks with the packing voids sized tens to 200 nm. Then, the hybrid networks were treated by pyrolysis-oxidation-phosphidation and ZnO-removal processes, leading to the hierarchically porous CoP/NCNs. In the CoP/NCNs, there are plentiful CoP nanoparticles embedded on the surface of conductive carbon network and fully exposed. When used for HER electrocatalyst, the CoP/NCNs only need small overpotentials (98 and 118 mV in acid and alkaline electrolyte) at 10 mA cm−2. This novel strategy is instructive for tailoring hierarchically porous transition metal phosphide/carbon nanocomposites as promising electrocatalysts.

Joints are the most critical component of reticulated shell structures, and their hysteretic performance is crucial to the mechanical properties of the whole reticulated shell structure under seismic action. Therefore, the hysteretic behaviour of aluminium alloy flower-gusset composite joint for an out-of-plane bending moment was studied by experiments and numerical analysis. The results show that the hysteretic curves of flower-gusset composite joints and gusset joints contain four stages: an elastic stage, a bolt slip stage, a hole wall pressure-stiffness degradation stage and a failure stage. The hysteretic performance of the new flower-gusset composite joint is obviously better than that of the traditional plate joint. With the increase in the thickness of the cover plate, the bending stiffness of the flower-gusset composite joint increases significantly, while the rotational deformation decreases. Then, a restoring force model of the flower-gusset composite joint is proposed through theoretical analysis based on experiments and numerical analysis.

Purpose This paper aims to investigate the micro-plastic behavior of granular material in three-body friction interface and its effect on friction characteristics. Design/methodology/approach A numerical model of particle breakage in friction contact was constructed based on the discrete element method. The influence of friction pair working condition and internal bonding strength on the micro-plastic behavior of particulate matter was analyzed. A reciprocating linear tribometer was used to verify the simulation results. Findings The results show that when the granular materials are squeezed and sheared by the friction pair, a shear zone inclined to the left is gradually formed, which leads to particle breakage. The breakage of the particle leads to the reduction of load-bearing capacity and the increase of friction coefficient. Due to the differences in bond strength and friction pairs working conditions, the particle plastic behavior is divided into the following three states: elastic deformation, breakage and plastic rheology. Originality/value This study is helpful to understand the effect of the micro-plastic behavior of particles on the three-body friction characteristics.

Summary Mechanism-guided catalyst design and engineering at the scale of active sites has been developed as a powerful tool for boosting catalytic performance. Herein, we report an efficient selective silylation strategy for the elaborate fabrication of ternary Au–Ti–Si sites to boost propylene epoxidation with H2 and O2. Kinetics (isotopic) analysis, Fourier transform infrared measurements, and theoretical calculations indicate an urgent necessity for selective consuming silanol sites not only to suppress propylene oxide (PO) ring opening to byproducts promoted by H2 spillover but also to minimize PO inhibition effects. A continuous silylation treatment was developed to encourage the kinetically favorable formation of ternary Au–Ti(–OH)–Si(–O–SiR3) moiety. This delivers significantly improved H2 efficiency of 42.5% in addition to the promising PO formation rate of 193 g h−1 kgcat−1 and PO selectivity of 95.7% with the long-term stability in excess of 200 h. These insights could pave the way for rationally fabricating catalyst active sites toward optimized performance.

The differences between the power quality at the AC and DC sides, caused by AC-DC converters with constant DC voltage control, commonly exist in low-voltage direct current (LVDC) systems. The voltage deviation isolation (VDI) is one of the typical phenomenons. A method is proposed to analyze the VDI performance and applied in two-stage high-frequency isolated AC-DC converters, which can isolate not only the faults but also the voltage deviation at the AC side and improve the voltage quality at the DC side. First, the voltage deviation isolation ratio (VDIR) is defined to assess VDI. Based on VDIR, the operation characteristics of AC-DC converters with constant DC voltage control are analyzed and the range of VDI is defined. Second, with considering the conditions for stable operation of AC-DC converters, constraints on power transmission limit and static stability limit are used to determine the range of VDI. Third, a simulation model is established and the feasibility and validity of the method are verified. Finally, the main factors affecting the range of VDI are analyzed. Actually, the method proposed is adapted to various types of AC-DC converters with constant DC voltage control.

The sintering and dielectric properties of (1 − x)Li2Mg0.95Co0.05SiO4 + xTiO2 ceramics created by the solid state reaction method were investigated. X-ray diffraction and energy-dispersive X-ray spectroscopy were used to obtain phase composition of the ceramics, and scanning electron microscopy was used to observe their microstructure. A network analyzer was used to measure dielectric properties, while mechanical, simultaneous-thermal, and dynamic mechanical analyzers were used to obtain mechanical and chemical properties. Li2Mg0.95Co0.05SiO4 (LMCS) and TiO2 co-exist in the composite system. TiO2 addition resulted in decreasing grain size and crystallite size, increasing starting temperature of shrinkage, increasing activation energy, and increasing elasticity and stiffness. A 4%/volume addition of TiO2 and sintering at 1075 °C changed the LMCS τf to 1.57 ppm/°C and resulted in dielectric properties of er = 6.33 and Q × f = 17,000 GHz (16 GHz) with a relative density equals to 96.13%.

AC magnetic flux leakage (ACMFL) testing is a novel method for the detection of defects of metallic materials. Conventional ACMFL probes excited by a single-frequency (SF) sine signal have limitations in accurately detecting the defect size and identifying the defect orientation. In this article, a multifrequency ACMFL (MF-ACMFL) method is proposed to address these issues. First, we give a thorough analysis of the effects of excitation frequencies on magnetic flux density under different defect sizes and orientations using the finite-element method. The numerical results indicate that the optimal frequencies are 400 and 500 Hz to detect the defect size, and that to identify the defect orientation are approximately 400–500 Hz. Then, we compare the receiver signal under SF and MF excitations and estimate the size of the defect including its length, width, and depth under oblique angles of 0° and 30°, whose results validate the effectiveness of the proposed method. Finally, measuring the depths and orientations of the defect on the thick steel plate verifies the correctness of the numerical results and the advantage of the proposed method in the orientation identification of the defect. Thus, the proposed scheme is an effective complementary measure for the existing ACMFL tools.

The development of high–efficiency and low–cost bifunctional oxygen electrocatalysts is critical to enlarge application of zinc–air batteries (ZABs). However, it still remains challenges due to their uncontrollable factor at atomic level during the catalysts preparation, which requires the precise regulation of active sites and structure engineering to accelerate the reaction kinetics for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, a novel Co–doped mixed lanthanum oxide and hydroxide heterostructure (termed as Co–LaMOH|OV@NC) was synthesized by pyrolysis of La–MOF–NH2 with spontaneous cobalt doping. Synergistic coupling of its hollow structure, doping effect and abundant oxygen vacancies creates more active sites and leads to higher electroconductivity, which contribute to the better performance. As employed as a bifunctional oxygen electrocatalyst, the resulting 3Co–LaMOH|OV@NC exhibits superior electrocatalytic activity for both ORR and OER. In assembled ZAB, it also demonstrates an excellent power density of 110.5 mW cm−2, high specific capacity of 810 mAh gZn−1, and good stability over 100 h than those of Pt/C + RuO2. Density functional theory (DFT) calculation reveals that the heterointerfaces coupled with oxygen vacancies lead to an enhanced charge state and electronic structure, which may optimize the conductivity, charge transfer, and the reaction process of catalysts. This study provides a new strategy for designing highly efficient bifunctional oxygen electrocatalysts based on rare earth oxide and hydroxides heterointerface.

The erosion of soluble rock and transformation of groundwater result in the high geometrical irregularity of cavities in nature. The purpose of this paper is to quantitatively describe the shape of irregular cavities using Fourier transform analysis. Firstly, multi-level characterization indexes of the 2D section of cavities have been proposed, considering the high shape irregularity of cavities. The first level indexes include Shape Factor (SF), Aspect Ratio (AR) and Sphere Like (SL). The second level indexes consist of Angularity Factor (AF) and Convexity Factor (CF). The third level indexes are Roundness Factor (RF). Then, the geometric contour of cavity was transformed into a 2D waveform, with an equal-angle points sampling of the cavity boundary. The geometric boundary of irregular cavity was segmented and transformed from discrete time domain to frequency domain based on discrete Fourier transform (DFT). Furthermore, we proposed Fourier shape descriptor, which was found to control the cavity shape. The relationship between Fourier shape descriptors in different sequences and multi-level characterization indexes was determined using designed and irregular nature cavities as sample data. The results demonstrated that the Fourier shape descriptors​ D 2 , D 3 and D 8 mainly control multi-level characterization indexes including the overall shape, the irregularity and the roughness of the cavity boundary, respectively. Finally, the 3D characterization method of cavity shape was further proposed based on averaging the 2D sections, which hence offers a possible way to further quantitatively study the mechanical properties of surrounding rockmass effected by the irregular shape of cavities.

The shear behaviour on the interface between soil and structure is a research hot point. Based on the RMT-150B rock mechanics test system, a series of high-stress direct tests were performed on the coarse sand under the condition of different moisture contents and concrete substrates with different rough and hardness. The results showed that the shear stress-displacement curve and volumetric strain-displacement curve of the interface under high stress could be fitted by a hyperbolic model; the ultimate shear strength and initial shear stiffness of the interface both increased with the normal stress while the shear stiffness decreased with the shear displacement. The crushing rate of the coarse sand particles on the interface increased with the normal stress. After the range analysis for the influencing factors of the interface’s shearing behaviour, it was shown that for the ultimate shear strength, their sequence of influencing degree was normal stress, the roughness of interface, moisture content, and hardness of concrete base; for the initial shear strength, the sequence was normal stress, moisture content, interface roughness, and basal hardness. As for dry sand, the possibility of relative particle crushing was higher than that of sand with a moisture content of 8%, and a peak of crushing occurred when the moisture content was 16%.

The IHTC (Interfacial-Heat-Transfer-Coefficient) between 22MnB5 and KDAHP1 hot work tool steel during the hot stamping process is an important thermal parameter to reflect the heat transfer efficie...