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Rechargeable Li-CO2 batteries (LCBs) are considered as a promising candidate for the next generation energy storage system, but still be impeded by the lack of high-performance cathode catalyst and poor understanding for the complicated reaction mechanism. In the present work, we demonstrate that the catalytic capability of cathode catalyst of LCBs can be remarkably enhanced from the accelerated reaction kinetics using a p-type substrate as adsorption/desorption promoter for refined reaction route. A carbon-free atomic Ir-Te cathode catalyst with Ir atomic cluster is uniformly super-assembled on the surface of Te nanowires forming an amorphous surface layer (ca. 3 nm) to maximize the catalytic capability of active Ir sites and provide a refined reaction pathway due to synergistic effect of Ir active sites and Te substrate. The adsorption ability of Li2C2O4 during discharging and the desorption ability of CO2 species during charging of the p-type Te substrate could both promote the catalytic reaction kinetics and optimize the reaction pathways on Ir active sites. Finally, a large specific capacity of 13,247.1 mAh g−1 and an excellent high rate cyclability with stably over 350 and 200 cycles at the current density of 1000 and 2000 mA g−1 are achieved. This contribution provides a rational design strategy for high performance cathode catalyst, and intrinsic insight towards the understanding the reaction mechanisms of LCBs.

As most of the known systems are flashtype, long-lasting chemiluminescence (CL) emissions are extremely needed for the application of cold light sources, accurate CL quantitative analysis, and biological mapping. In this work, the flashtype system of luminol was altered to a long lasting CL system just because of the paper substrate. The Cu(II)-based organic complex was loaded on the paper surface, which can trigger luminol-H2O2 to produce a long lasting CL emission for over 30 min. By using 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) as the ligand, a hexacoordinated Cu(II)-based organic complex was synthesized by the simple freeze-drying method. It is interesting that the complex morphology can be controlled by adding different amounts of water in the synthesizing procedure. The complex with a certain size can be definitely trapped in the pores of the cellulose. Then, slow diffusion, which can be attributed to the long lasting CL emission, was produced. With the high catalytic activity of the complex, reactive oxygen species from H2O2 was generated and was responsible for the high CL intensity. By using the paper substrate, the flash-type luminol system can be easily transferred to the long-duration CL system without any extra reagent. This long-lasting emission system was used for hydrogen sulfide detection by the CL imaging method. This paper-based sensor has great potential for CL imaging in the clinical field in the future.

The renaissance of aqueous Zn ion batteries has drawn intense attention to Zn metal anode issues, including dendrites growth, dead Zn, low efficiency, and other parasitic reactions. However, against the widely used 2D Zn foil, in fact, the Zn powder anode is a more practical choice for Zn-based batteries in industrial applications, but the related solutions are rarely investigated. Herein, we focus on the Zn powder anode and disclose its unknown failure mechanism different from Zn foils. By utilization of 2D flexible conductive Ti3C2Tx MXene flakes with hexagonal close-packed lattice as electrons and ions redistributor, a stable and highly reversible Zn powder anode without dendrite growth and low polarization is constructed. Low lattice mismatch (∼10%) enables a coherent heterogeneous interface between the (0002) plane of deposited Zn and (0002) plane of the Ti3C2Tx MXene. Thus, the Zn2+ ions are induced to undergo rapid uniform nucleation and sustained reversible stripping/plating with low energy barriers via the internally bridged shuttle channels. Paired with cyano group iron hexacyanoferrate (FeHCF) cathode, the FeHCF//MXene@Zn full battery delivers superior cycle durability and rate capability, whose service life with a CE of near 100% touches 850% of bare Zn powder counterparts. The proposed Ti3C2Tx MXene redistributor strategy concerning high-speed electrons/ions channel, low-barrier heterogeneous interface, is expected to be widely applied to other alkali metal anodes.

The wear and corrosion resistance of Ni-based niobium carbide (NbC) coatings were investigated via scanning electron microscopy, energy dispersive spectrometry, particle size analysis, X-ray diffraction, electrochemical polarization, electrochemicl impedance spectroscopy, digital microhardness testing and wear testing. The results showed that the substrate was mainly composed of a γ-Cr (Fe) solid solution, and the composite coating was composed of FeNi, NbC, and Ni. In addition, the hardness of the coating increased gradually with increasing NbC content. The optimal corrosion resistance and wear resistance of the coating were realized at an NbC content of 20%.

Highly reliable signal recording with low electrode-skin impedance makes the microneedle array electrode (MAE) a promising candidate for biosignal sensing. However, when used in long-term health monitoring for some incidental diseases, flexible microneedles with perfectly skin-tight fit substrates lead to sweat accumulation inside, which will not only affect the signal output but also trigger some skin allergic reactions. In this paper, a flexible MAE on a Miura-ori structured substrate is proposed and fabricated with two-directional in-plane bendability. The results from the comparison tests show enhanced performance in terms of (1) the device reliability by resisting peeling off of the metal layer from the substrate during the operation and (2) air ventilation, achieved from the air-circulating channels, to remove sweat. Bio-signal recordings of electrocardiography (ECG), as well as electromyography (EMG) of the biceps brachii, in both static and dynamic states, are successfully demonstrated with superior accuracy and long-term stability, demonstrating the great potential in health monitoring applications.

Flexible laser display is a critical component for an information output port in next-generation wearable devices. So far, the lack of appropriate display panels capable of providing sustained operation under rigorous mechanical conditions impedes the development of flexible laser displays with high reliability. Owing to the multiple scattering feedback mechanism, random lasers render high mechanical flexibility to withstand deformation, thus making them promising candidates for flexible display planes. However, the inability to obtain pixelated random laser arrays with highly ordered emissive geometries hinders the application of flexible laser displays in the wearable device. Here, for the first time, we demonstrate a mass fabrication strategy of full-color random laser arrays for flexible display panels. The feedback closed loops can be easily fulfilled in the pixels by multiple scatterings to generate durative random lasing. Due to the sustained operation of random laser, the display performance was well-maintained under mechanical deformations, and as a result, a flexible laser display panel was achieved. Our finding will provide a guidance for the development of flexible laser displays and laser illumination devices.

Lithium metal (Li) is regarded as the “holy grail” in the anode material of next-generation high-energy-density batteries. However, the Li dendrites and “dead Li” produced during cycling limit its commercialization process. A properly designed three-dimensional (3D) skeleton plays an important role in determining the performance of Li metal anodes (LMA). Herein, we develop a super-assembled surface-modified lipophilic thin ZnO layer by atomic layer deposition (ALD) and multi-level Cu nanofibers (MCN) on a Cu foam (ZnO-MCNCF) as an advanced Li metal anode host. During the Li plating process, lipophilic ZnO layer can induce uniform nucleation of Li. Meanwhile, the unique hierarchical structure provides a larger specific surface area to distribute the surface charge uniformly, adjust the current density, and ensure more uniform Li deposition. Consequently, the as-designed ZnO-MCNCF host enables dendrite-free deposition of Li, high coulombic efficiency, and remarkable cycling stability at various current densities. Compared with CF and MCNCF host, ZnO-MCNCF has significantly improved Li plating/stripping behavior, with high coulombic efficiency (CE) and excellent Li dendrite growth inhibition ability. The Li@ZnO-MCNCF electrode can be operated for 1400 h at a current density of 10 mA cm−2 and large area specific capacity of 10 mAh cm−2 with an ultra-low overpotential (57.1 mV) without significant fluctuations. The LiFePO4-Li (LFP-Li) and LiCoO2-Li (LCO-Li) full cells also exhibit superior cycling and rate performance.

Tellurium quantum dots (Te QDs) were prepared using bulk tellurium as the precursor. Te QDs can be a highly active photocatalyst for boosting the photocatalytic degradation of rhodamine B (RhB) under visible light irradiation. The morphology and composition of Te QDs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that in the presence of H2O2, the photocatalytic efficiency of Te QDs on RhB could achieve a good degradation effect within a very short time (30 min). The effects of initial dye concentration, pH value, light intensity, catalyst dosage and H2O2 concentration on dye degradation were successively studied. The effects of inorganic ions (NO3−, Cl−, SO42−, Ca2+, Mg2+ and Fe3+) on photocatalytic degradation were also discussed. Experimental results of free radical capture showed that OH• and O2•− played important roles in photocatalytic degradation. More importantly, Te QDs efficiency still remained above 85% after four cycles of use, indicating good stability, recyclability and utility. This work may inspire further design of other semiconductor QDs for highly efficient dye degradation.

With the rapid development of wearable smart devices, many researchers have carried out in-depth research on the stretchable electrodes. As one of the core components for electronics, the electrode mainly transfers the electrons, which plays an important role in driving the various electrical devices. The key to the research for the stretchable electrode is to maintain the excellent electrical properties or exhibit the regular conductive change when subjected to large tensile deformation. This article outlines the recent progress of stretchable electrodes and gives a comprehensive introduction to the structures, materials, and applications, including supercapacitors, lithium-ion batteries, organic light-emitting diodes, smart sensors, and heaters. The performance comparison of various stretchable electrodes was proposed to clearly show the development challenges in this field. We hope that it can provide a meaningful reference for realizing more sensitive, smart, and low-cost wearable electrical devices in the near future.

Zero-dimensional perovskites exhibit exotic optoelectronic responses, but stimulated emissions from such media remain elusive and challenging thus far. Here, we demonstrate for the first time the c...

The characterization and correction of lens distortion is an important part of optical measurement. This work analyzes the formation mechanism of color fringes and multiplication moire, and discusses modification of the color CCD moire method for correcting lens distortion. A demosaicing algorithm was used to simulate the color fringes in a CCD moire pattern. We then performed a detailed analysis of the carrier field, and adopted a universal polynomial distortion model to characterize lens distortion, which increased the accuracy of distortion correction. Comparison experiments verified the feasibility of the modified method and the correctness of the formation mechanism for color CCD moire. The modified method was then applied to lens distortion correction in the DIC measurement process, effectively reducing errors in displacement measurement.

The present study envisaged the WC-reinforced nickel composite coatings prepared on the surface of 4145H steel using the plasma transferred arc (PTA) method. The effects of different content of Y2O3 on the microscopic morphology, phase composition, micro-hardness and wear behavior were investigated by scanning electron microscopy (SEM) with an energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), micro-hardness test and wear experiments. The deposited coatings consisted of WC-reinforced Ni59 composite coatings with the addition of 0 wt%, 0.5 wt% and 1 wt% Y2O3. Microstructural observation showed that the addition of 0.5 wt% Y2O3 had a better improvement on the coarse dendrites and the grain refinement. The main phase composition of the composite coatings was γ-Ni, FeNi3 solid solution, γ(Fe, Ni) eutectic phase, and the hard phase of WC, W2C. The cladding layer added with 0.5 wt% Y2 O3 was preferable over the Y2O3-free coating, as the microhardness was improved from 500 HV to 800 HV with a slight fluctuation of values. The coating with 0.5 wt% Y2O3 offered an excellent wear resistance to the extrusion and cracks for the uniformity of organizational structure compared with the substrate and the other two coatings. Furthermore, the results of weightlessness and coefficient of friction proved the positive effect of the rare earth Y2O3 on the wear resistance.

Nickel-based composite coatings reinforced by spherical tungsten carbide were deposited on 42CrMo alloy steel using plasma transfer arc welding (PTAW) process. Their electrochemical corrosion properties in NaCl solution under atmospheric and high pressure were studied by polarization curve, electrochemical impedance spectroscopy. The corrosion and erosion resistance of the coatings were also investigated by salt spray corrosion and erosion corrosion tests. The results show that the self-corrosion potential of the composite coatings increased with the increase of tungsten carbide content, and the Cr element in Ni60 sample formed a stable and compact passivation film. Compared with corrosion at atmospheric pressure, the adsorption and penetration of Cl- on the coating surface enhanced due to the increase of Cl- activity under pressure, thereby to weaken the corrosion resistance. The Samples that passivated in salt spray environment, cannot completely hinder the corrosion of the coating, just only to slow down the corrosion. This study can provide theoretical basis for deep-sea oil drilling and production engineering equipment.

Two kinds of Co-based coatings were obtained through the laser cladding (LC) and plasma transfer arc (PTA) process. The phase composition and microstructure of the coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The corrosion behaviour of the different Co-based alloy coatings in 3.5wt% NaCl solution were compared by means of open-circuit potential (OCP), polarization curve and electrochemical impedance spectroscopy (EIS). XRD and SEM measurements demonstrated that the microstructures of the two different Co-based coatings were composed of primary solid solution γ-Co and eutectic structure Cr23C6, whereas, fish-bone typed (CoCrW)6C was also detected in the coating produced by PTA. The polarization curves and EIS results showed that in 3.5wt% NaCl solution, the passivation zones of the two coatings occurred obviously, the self-corrosion potential of the two coatings shifted to the right, and the self-corrosion current density was much smaller than that of the substrate. In addition, the Co-based coating made by LC showed lower corrosion current density and larger diameter of a capacitive arc than that of Co-based coating produced by PTA, indicating the LC coating had the best corrosion resistance in the three samples.

Biomaterial surfaces tend to adhere only under dry conditions, preventing them from being used in underwater environments such as body fluids. Therefore, biomaterial surfaces with underwater adhesion ability have received increasing attention. In nature, some organisms can adapt to different environments by evolving appendages with underwater adhesion capability and unique functions. Most of these outstanding functions are derived from special micro/nanostructures and/or chemical compositions of these organisms. Thus, modification of biomaterials surfaces with similar microstructures and chemical groups would help promote underwater adhesion. In this review, we discuss (1) the mechanisms of underwater adhesion; (2) surface modification strategies for underwater adhesion, including mussel-inspired, interlocking, bio-structured surface, and specific adhesion strategies; and (3) the challenges and potential of developing surface-modified, multiscale biomaterials with underwater adhesion.

Anticounterfeiting labels based on physical unclonable functions (PUFs) exhibit high security with unreplicable code outputs, making them an ideal platform to realize unbreakable anticounterfeiting. Although various schemes are proposed for PUF labels, the utilization of natural randomness suffers from unpredictable signal extraction sites, which poses a challenge to efficient and convenient authentication for practical anticounterfeiting applications. Here, a covert optical PUF-based cryptographic protocol from silk protein-based microlaser (SML) arrays that possess hidden randomness of lasers for unclonable lasing signals as well as a defined location for efficient identification is proposed. The initial SMLs are patterned by casting laser dye-doped regenerated silk fibroin solution, resulting in a uniform microlaser array with regulated positions. With the SML array as substrate, random methanol microdroplets are stochastically sprayed on the SML array, which eventually induces uneven lasing signal changes of the patterned microlasers. The treated SML array possesses the deterministic readout sites of laser signals and unrepeatable signal distribution characteristics, which can guarantee efficient authentication and high security when serving as an anticounterfeiting label.

Near-infrared (NIR) microlasers play a significant role in telecommunication and biomedical tissue imaging. However, it remains a big challenge to realize NIR microlasers because of the difficulty in preparing highly efficient NIR luminescent materials and perfect optical resonators. Here, we propose a molecular design strategy to creatively realize the first spiropyrane (SP)-based NIR microlasers with low threshold from self-assembled microsphercial caps. The tetraphenylethylene (TPE) moiety with a highly twisted conformation provides a large free volume to facilitate the photoisomerization process of SP and enhance NIR emission of merocyanine in the solid state. Moreover, self-assembled TPE-SP microsphercial caps simultaneously serve as gain media and resonant microcavities, providing optical gain and feedback for NIR laser oscillations with a low threshold (3.68 μJ/cm

Catalytic steam reforming of methane with Ni-based catalysts is essential for industrial hydrogen production, but the high reforming temperature results in the catalyst deactivation by severe carbon deposition. In this work, a novel electro-catalytic protocol for steam reforming of methane was developed with aims of lowering the reforming temperature and prolonging the catalyst life. Three Ni-based catalysts, i.e., Ni/γ-Al2O3 (Ni/Al2O3), Ni/γ-Al2O3-MgO (Ni/AM) and Ni-CeO2/γ-Al2O3-MgO (Ni-CeO2/AM) were prepared for electro-catalysis to investigate the effects of current intensity, reforming temperature, and steam to carbon ratio on methane conversion, H2 yield and CO selectivity. Moreover, stability tests were performed on the three catalysts. The results indicated that the presence of electric current promoted the methane steam reforming at relatively low temperatures. Among the three catalysts, Ni-CeO2/AM showed the best performance on catalytic efficiency. Under conditions of 600 °C and current of 4.5A, CH4 conversion, H2 yield and CO selectivity achieved 96.4%, 75.3% and 40.1% respectively over Ni-CeO2/AM, which were comparable with those from conventional process at 700 °C. Moreover, after a 9-hour stability test, the CH4 conversion was maintained over 95% under Ni-CeO2/AM. Characterization results of the catalysts from the stability texts showed that the current could help generate more active centers for CH4 activation while inhibit the conversion of coke precursors into carbon on the catalyst surface.

Tough and conductive hydrogels are the promising materials for various applications. However, fabrication of these hydrogels at room or low temperatures, without external stimuli, is a challenge. H...

Amorphous Gd65Fe20Al15 and Gd71Fe3Al26 alloys have ever been reported to exhibit giant refrigerant capacity around their magnetic ferromagnetic-paramagnetic phase transition, which is desirable in magnetic refrigeration. In this paper, we have investigated the critical behavior of amorphous Gd65Fe20Al15 and Gd71Fe3Al26 alloys in order to better understand their magnetic phase transition. We compared the critical exponents estimated using modified Arrott plot and Kouvel-Fisher plot methods. The critical exponents obtained by Widom's law are in good agreement with those calculated from critical isotherm analysis. According to the obtained critical exponents, the magnetic properties of these two samples were re-scaled, indicating that the magnetic behavior of these alloys could be expressed by a universal and unified law. By analyzing the effective critical exponents and exchange interaction of the two alloys, we have determined that Gd65Fe20Al15 and Gd71Fe3Al26 exhibit isotropic short-range magnetic interaction and close to the 3D-Heisenberg model.

In this work, the synthesis and aggregation-induced emission (AIE) properties of a new molecular system are reported. This system composes of three positional isomers, which are fabricated by attaching a methoxy group in different locations. The isomeric effects on the AIE properties as well as the intramolecular charge transfer (ICT) processes were studied. Additionally the new isomers exhibit mechanochromic fluorescence (MCF). Among the three isomers, (E)-2-(((6-chlorobenzo[d]thiazol-2-yl)imino)methyl)-5-methoxyphenol (CHM3) exhibits the most remarkable MCF performance with emission that decreases in intensity and red-shifts in wavelength under mechanical stimuli. The emission changes are caused by crystalline-amorphous transition as verified by Powder X-ray diffraction (PXRD) analysis. The mechano-induced state can be easily recovered through a recrystallization process, which can be activated by solvent fumigation or solvent immersion. Furthermore, the switching between two emission states shows nice reversibility. Based on the MCF material with high fatigue resistance, a new type of rewritable optical data storage (ODS) is developed. Binary data, comprised of “0” and “1” state, can be matched well with the two emission states, respectively. The data could thus be written or erased on the ODS device, demonstrating feasibility and practicability.

Li–O2 batteries have become very promising power sources for electronic vehicles as a result of their extraordinary energy density. Nevertheless, the unfavourable electrocatalytic activity of cathode materials in Li–O2 batteries is still a limiting factor for the practical application of Li–O2 batteries. This study proposes a surface engineering strategy which can enhance the electrocatalytic activity of CeO2 nanorods by tuning the oxygen vacancies on their surface, and found that the highest concentration of oxygen vacancies induces the best electrochemical performance, including an extended electrochemical stability of 200 cycles, and reduces the overpotential of the ORR from the reported 0.26 V to 0.11 V. Ex situ XPS photoelectron spectroscopy was carried out to further explain the role of oxygen vacancies in improving the electrochemical performance of LOBs, indicating that the oxygen vacancies of CeO2 nanorods have more obvious positive effects on the ORR than on the OER. It is believed that they can serve as the active sites for the deposition of Li2O2 films by being involved in the reaction between Li+ and O2 during the ORR, and also boost the electron transport through the insoluble Li2O2 films to further catalyse the Li+ and O2 reaction during the discharge and charge process. This work provides new proof for the association between the discharge/charge behaviour of LOBs and the content of oxygen vacancies.

In this study, we reported the synthesis and aggregation-induced emission (AIE) properties of a new molecular system, comprised of six positional isomers. The presence of electron donor (D) and acceptor (A) units endows them with intramolecular charge transfer (ICT) effects. We studied how changing the positions of the D/A units affects the AIE properties, ICT strength as well as the energy levels of the molecular orbitals. In addition, the self-assembly behaviors of them show distinct isomeric effect: With the D/A units repositioning, various self-assembly architectures with sizes ranging from microscale to nanoscale appear sequentially, including filaments, sheets, rods, irregular particles, needles, fibrous interlocking textures. It was verified that the D/A units on para-position that pose linear dipole-dipole interaction would favor the formation of well-defined structures, otherwise the resulting assembly would be underdeveloped or ill-shaped due to low degree of order in the molecular packing. This study probed the relationships between molecular structure and self-assembly behaviour, and further makes the self-assembly customizable.

We report the synthesis and photoluminescence (PL) behavior of a new molecular system, which is composed of three positional isomers. They exhibit isomeric effects on both aggregation-induced emission (AIE) and intramolecular charge transfer (ICT) mechanisms. Furthermore, one of them, i.e., (E)-5-methoxy-2-(((6-methylbenzo [d]thiazol-2- yl)imino)methyl)phenol (MTP3), shows unique mechanochromic fluorescence (MCF) phenomenon. Unlike most MCF materials that would function immediately after applying mechanical force, the MCF character of this material is however recessive with mechanical force, but becomes visible upon fumigation treatment. Given that the MCF is activated under specific conditions, it is termed as conditional mechanochromic fluorescence (CMCF) in this study. In light of the CMCF property of MTP3, a new data encryption-decryption technique was developed. Binary data and complex patterns can be recorded by mechanical force and concealed on the tailor-made data storage. The encoded data cannot be read unless it is fumed by organic vapour, demonstrating a successful encryption-decryption technique. The CMCF offers great potential to be the alternative to encryption algorithms and may contribute greatly to data security and cybercrime prevention.

Aqueous graphite-based dual ion batteries have unique superiorities in stationary energy storage systems due to their non-transition metal configuration and safety properties. However, there is an absence of thorough study of the interactions between anions and water molecules and between anions and electrode materials, which is essential to achieve high output voltage. Here we reveal the four-stage intercalation process and energy conversion in a graphite cathode of anions with different configurations. The difference between the intercalation energy and hydration energy of bis(trifluoromethane)sulfonimide makes the best use of the electrochemical stability window of its electrolyte and delivers a high intercalation potential, while BF4− and CF3SO3− do not exhibit a satisfactory potential because the graphite intercalation potential of BF4− is inferior and the graphite intercalation potential of CF3SO3− exceeds the voltage window of its electrolyte. An aqueous dual ion battery based on the intercalation behaviors of bis(trifluoromethane)sulfonimide anions into a graphite cathode exhibits a high voltage of 2.2 V together with a specific energy of 242.74 Wh kg−1. This work provides clear guidance for the voltage plateau manipulation of anion intercalation into two-dimensional materials., The interactions between water molecules, electrode materials and anions are essential yet challenging for aqueous dual ion batteries. Here, the authors demonstrate the voltage manipulation of dual ion batteries through matching intercalation energy and solvation energy of different anions.

While MXene has been widely used in many energy storage systems, the absence of a high intrinsic voltage plateau results in its poor discharging feature. Herein, we report a Nb2CTx MXene cathode with an apparent discharge voltage plateau for high-performance aqueous zinc ion batteries. Triggered by a repeated high-voltage-scanning up to 2.4 V, the Nb2CTx cathode gradually displays a stable Zn2+ storage dominated by a battery behavior. A high discharge voltage plateau of 1.55 V is presented, which is distinct from all reported MXene electrodes. Consequently, a record-level energy density among all aqueous MXenes electrodes of 146.7 Wh kg-1 with a 63% contribution from the plateau region is obtained, which is 292% that of the capacitive Nb2CTx electrode. The developed high-voltage-scanning strategy is also effective for Ti3C2Tx MXene to achieve a remarkable voltage plateau.

This study proposes a lens distortion characterization technique based on a colour charge coupled device (CCD) moire method. The colour CCD imaging lattice unit can be considered as three sets of parallel integrated reference gratings. An image formed from the reflected light of a physical grating through a lens was selected as a specimen grating. High-contrast colour moire stripes were formed by superimposing the three sets of reference gratings and the specimen grating under specific conditions. The mechanism of colour CCD moire formation was further studied and illustrated. The specimen grating image is modulated by lens distortion, and thus the formed moire stripes carry amplified lens distortion information. The principle of lens distortion extraction was described in detail. During moire image processing, a high-contrast image could be obtained by extracting the blue or red values of the original fringe pattern, which were determined by the distribution of the three colour filter arrays on the filter. Because the ultimate resolution of the camera is fully utilised, this method has a high sensitivity and accuracy in the distortion measurement. It not only very intuitively reflects all features of the lens distortion field, but is also very convenient for obtaining the distortion parameters of the lens distortion field. Finally, the distortion and deformation of two types of lens were characterized and analysed using the colour CCD moire method.

In this study, the asphalt microstructure and micro mechanical properties are first investigated using atomic force microscopy (AFM) experiments. The AFM experiment results show that the asphalt samples have very complex microstructure morphology. The molecular dynamics (MD) simulation is then conducted to model the asphalt molecular structure. A tension loading is applied on the asphalt structure. It is discovered that the structure will be gradually stretched and the potential energy for van der Waals interactions takes a major part in the total energy. The effect of molecules number on the MD results was analyzed. The phase field method was also used to simulate the micro mechanical properties considering the material viscoelasticity. Keywords: Asphalt, Molecular structure, MD simulation, AFM

Mortar is one of the most widely used civil infrastructure materials, where the mortar fracture properties will significantly affect the structure service performance and life. In this paper, the fracture toughness of mortar specimen with respect to different thickness is investigated by conducting the three point bending test. The Extended Finite Element Method (XFEM) is also employed to model the crack propagation and failure process in the mortar specimen. It is found that the thickness of mortar specimen will affect the mortar cracking performance and the new emerged numerical tool XFEM is able to characterize the fracture properties of mortar specimen. Keywords: Fracture toughness, Mortar, Crack propagation, XFEM

The performance of waterproof bonding layer directly effects the durability of the highway bridge. Water permeability, shear strength and tension strength are three main indicators evaluating the waterproof bonding layer. In this research, three waterproof bonding materials including SBS modified asphalt, SBR modified asphalt emulsion and second order reaction waterproof material were selected. The water permeability, shear strength and pull-off strength were tested. The effect of different temperature and different contents were analyzed. Results show that: the water permeability resistance of waterproof bonding layer ranked as follows: SBS modified asphalt > Second order reaction waterproof material > SBR modified asphalt emulsion. Compared to SBR modified asphalt emulsion and second order reaction waterproof material, SBS modified asphalt has a better shear resistance. Three waterproof materials used in this research all have temperature sensitivity. Their shear strength and tension strength decrease dramatically with temperature increasing. Keywords: Waterproof bonding layer, Highway bridge, Water permeability, Shear performance, Pull-off performance

We have investigated the magnetocaloric effects and critical behaviors of Eu2NiMnO6 and Dy2NiMnO6 double perovskite oxides. For a magnetic field varying from 0 to 7 T, the maximum values of the magnetic entropy change ( | Δ S M max | ) reach 4.0 J/kg K and 5.2 J/kg K, and the relative refrigeration capacity (RCP) values are 241.5 J/kg and 385.1 J/kg for Eu2NiMnO6 and Dy2NiMnO6, respectively. The relatively high values of | Δ S M | and RCP suggest that these double perovskite oxides can be used as candidates of magnetic refrigerants working in a wide temperature range. Various techniques such as modified Arrott plot, Kouvel-Fisher method and critical isotherm analysis are used to estimate the critical exponents (β, γ and δ) as well as TC for Eu2NiMnO6. These critical exponents not only obey the Widom scaling relation δ = 1 + γ / β , but also fulfill the scaling equation M ( H , e ) = e β f ± ( H / e β + γ ) where e = (T – TC)/TC, f+ (T > TC) and f- (T

Fundamental understandings of the pavement-tire friction are vital to improve the design of asphalt pavements. Most of the current research on pavement-tire friction is based on Finite Element Meth...

Good pavement friction performance between tire and asphalt pavement is the prerequisite to ensure traffic safety and driving comfortability. In this paper, the microscopic friction between tire and asphalt pavement is studied using the Material Studio and LAMMPS software. A 3D contact model of tire, asphalt layer and the substrate layer is established. The Molecular Dynamics (MD) simulation is conducted to simulate the friction behavior under different environments. The influence of different environmental conditions including vehicle speed (20–120 km/h) and pavement surface temperature (−30 to 35 °C) on the pavement surface friction coefficient is also studied. Simulation results show that vehicle speed and pavement surface temperature have significant effects on the friction coefficient at microscale. Keywords: Microscopic friction, Tire and asphalt pavement, Molecular dynamics simulation, Temperature

A MnO@C microcage with a multi-structure and tunable carbon shell was fabricated through a facile bio-inspired synthesis strategy for highly reversible Li storage. Micrometer-sized MnO unit aggregates were covered with a porous carbon shell outside with a thickness of about 0.2 μm, and a graphene-analogous carbon network inside the MnO@C microcages. The carbon shell could be tunable by a graphene-base shell. The unique double-carbon-coating structure of the MnO@C microcages enabled realizing the high Li-storage performance of the MnO particles with a micrometer size. The electrode containing the MnO@C microcages delivered a high reversible capacity of 1450.5 mA h g−1 after 270 cycles at a current density of 0.1 A g−1, good rate capability, and outstanding cycling stability with a retention capacity of 805 mA h g−1 after 2000 cycles at a high current density of 1 A g−1. Quantitative kinetic analysis indicated that around 40% of the charge storage came from the capacitive contribution of the microcage structure. It was found that the tunable graphene-base shell could enhance the Li-ion diffusion rate significantly, and enable a stable ultralong long life cycle performance and enhanced rate performance of the microcages.

Flexible thermoelectric generators (f‐TEGs) have demonstrated great potential in wearable self‐powered health monitoring devices. However, the existing wearable f‐TEGs are neither flexible enough to bend and stretch while maintaining the device's integrity with a good TE performance nor directly compatible with clothes materials. Here, ultraflexible fabric‐based thermoelectric generators (uf‐TEGs) are proposed with conductive cloth electrodes and elastic fabric substrate. The patterned elastic fabric substrate fits the rigid cuboids well, together with serpentine structured cloth electrodes, rendering uf‐TEG with excellent integrity and flexibility, thereby achieving a highly functional TE performance when strain reaches 30% or on arbitrarily shaped heat sources. The uf‐TEGs show a large peak power of 64.10 μW for a temperature difference of 33.24 K with a high voltage output of 111.49 mV, which is superior compared to previously reported fabric‐based TEG devices, and it is still functional after the water immersion test. Besides the energy harvesting function, with both the temperature sensing ability and the touch perception, this uf‐TEG is demonstrated as the electrical skin when mounted on a robot. Moreover, due to the wind‐sensitive performance and self‐power ability, the uf‐TEGs are assembled on cloth as wearable health and motion monitoring devices., An ultraflexible whole‐fabric assisted thermoelectric generator (uf‐TEG) with thermoelectric cuboids, elastic fabric as assembling material, and conductive flexible cloth‐based electrodes is presented here. The uf‐TEG can be applied in different applications such as electrical skin (temperature sensing and touch perception) and human health and motion monitoring (respiration rate, finger gesture, and steps counting).

The research and development of transient energy devices used to power implanted electronic is an emerging engineering field that has attracted increasing attention. This device not only requires the material and system design with excellent performance in routine operations but also can be degraded at a controlled rate once a specific task is completed. Herein, we report a transient, high-performance and formable yarn-like zinc-ion battery (ZIB) composed of a smart humidity-sensitive plasticized gelatin-silk fibroin electrolyte film and a dual-yarn electrode structure. This transient energy battery device exhibits a high specific capacity (311.7 mA h g−1 ) and excellent cycle stability (94.6% capacity retention after 100 cycles) due to the high ionic conductivity . More importantly, the yarn ZIB device also demonstrates superior shape plasticity (high capacity retention of 82.5% after 80 bends) and good biodegradability (fully degraded in 45 days under enzyme digestion). The successful design and fabrication of the ZIB battery system provide new research ideas for the development of transient energy devices in the future and bring new opportunities for multifunctional and green sustainable transient electronic products in the fields of medicine, national defense, flexible wearable, and consumer electronic products.

Stretchable and compressible conductor with a 3D structure has received widespread attention in smart robotics and deformable electronics, because of its special mechano-electrical properties. However, the poor mechanical properties, low electrical conductivity and unstable performance during deformation process are still the biggest technical bottlenecks. In this work, a stretchable and compressible conductive foam with stable mechano-electrical properties was comprised of copper nanowires (Cu NWs) and multi-walled carbon nanotubes (MWCNTs) that were wrapped firmly on flame-retardant ethylene-vinyl acetate (FR-EVA) skeleton. The 3D porous FR-EVA matrix with sufficient internal space provided a remarkable mechanicaldeformability for the composites foam. Additionally, the excellent conductivity of composites foam was mainly derived from the well-connected Cu NW networks, which were welded by chemical steam reduction method. Finally, the MWCNTs not only significantly improved the adhesion between the Cu NWs and FR-EVA skeleton but also effectively overcame the Cu NWs oxidation. Consequently, the 3D conductive composites foam possessed an excellent electrical conductivity (R = 2.40 Ω), mechanical stability (R/R0

Aqueous graphite-based dual ion batteries have unique superiorities in stationary energy storage systems due to their non-transition metal configuration and safety properties. However, there is an absence of thorough study of the interactions between anions and water molecules and between anions and electrode materials, which is essential to achieve high output voltage. Here we reveal the four-stage intercalation process and energy conversion in a graphite cathode of anions with different configurations. The difference between the intercalation energy and hydration energy of bis(trifluoromethane)sulfonimide makes the best use of the electrochemical stability window of its electrolyte and delivers a high intercalation potential, while BF

A series of ordered mesoporous carbons loaded with different contents of NiCo2O4 (X-NiCo2O4/OMC) were synthesized via a facile hydrothermal method and proposed as a catalyst for electrocarboxylation of benzophenone for the first time. The materials were characterized by many measurements, which showed mesoporous structures with high surface area, good dispersion and stability. What's more, the materials exhibit good electrocatalytic performance due to its good ability to capture CO2 and accelerate reaction rate, which brought by redox couples (Ni3+/Ni2+, Co3+/Co2+) and vacancy defects of NiCo2O4. The optimal yield of methyl benzilate reaches 86% on 3-NiCo2O4/OMC.

The interfacial behavior between asphalt binder and mineral fillers directly effects the performance of asphalt mastics or asphalt mixture. However, the understanding about the interfacial interaction between these components is very limited, although the role of individual ingredients on its performance is readily recognized. In order to study the interactions between asphalt binder and mineral fillers, it is necessary to propose an effective evaluation indicator. In this research, dynamic mechanical analysis (DMA) was used to obtain the viscoelastic parameters of different asphalt binder and asphalt mastics. The interfacial interaction parameters between asphalt binder and fillers were calculated based on the viscoelastic parameters and relevant theoretical models. The interaction parameters were compared and the calculated methods were improved. The results show that compared to interfacial interaction parameters Luis Ibrarra- A and K. Ziegel- B , C value based on Palierne theoretical model had the least sensitivity to the volume fraction of fillers. The checking of fitting goodness of improved interaction parameter C value shows a high determination coefficient. It demonstrates that the C value can effectively evaluate the interfacial interaction. The interfacial interaction becomes stronger with the temperature increasing. The higher the specific surface area of filler, he stronger the interfacial interaction between it and asphalt binder.

The interface between asphalt binder and mineral aggregate directly affects the service life of pavement because the defects and stress concentration occur more easily there. The interaction between asphalt binder and mineral aggregate is the main cause of forming the interface. This paper presents an extensive review on the test technologies and analysis methods of interfacial interaction, including molecular dynamics simulation, phase field approach, absorption tests, rheological methods and macro mechanical tests. All of the studies conducted on this topic clearly indicated that the interfacial interaction between asphalt binder and mineral aggregate is a physical-chemical process, and can be qualitatively characterized by microscopical technique (such as SEM and AFM), and also can be quantitatively evaluated by rheological methods and interfacial mechanical tests. Molecular dynamics simulation and phase field approach were also demonstrated to be effective methods to study the interfacial behavior and its mechanism.

The effect of laser doping of Al on the gas sensing behavior of nanocrystalline ZnO thin films is reported. The doping of Al was carried out by the spin-coating of Al-precursors on nanocrystalline ZnO films followed by a pulsed laser irradiation. The laser-doped films were characterized as a function of laser power density by measuring the optical, structural, electrical, morphological and gas sensing properties of ZnO films. It was found that the laser doping process resulted in an increase of electrical conductivity of ZnO films. The performance of gas sensor was investigated for different concentrations of H2 and NH3 in the air. The results indicate that the laser doping process can be utilized to improve the sensor characteristics such as sensitivity and response time by optimization of laser power density. The optimum laser power is interpreted as the critical power level required to compete the effective doping versus developing the effective grain boundaries. Also, the selectivity of laser-doped ZnO sensors for H2 was studied for a likelihood practical gas mixture composed of H2, NH3 and CH4. It is found that these films can be optimized to develop H2 and NH3 sensors in PPM level with a higher selectivity over other reducing gases.

The friction between tire and road surface is fundamentally depending on the molecular forces. In this paper, the nanoscale 3D contact model is employed to investigate the tire-aggregate friction mechanism. The tire and aggregate micro-structure are both constructed to evaluate the microscopic performance of tire-aggregate friction influence. Simulation results show for a high velocity, the energy dissipation of sliding on crystal structure is small, which results in a small friction coefficient; temperature will have influences on the friction coefficient, and with the increasing of velocity, the effect will gradually reduce. Keywords: Tire, Aggregate, Friction coefficient, Microscopic mechanism, MD simulation

In this paper, a combined DEM-MD method is proposed to simulate the crack failure process of Hydrated Cement Paste (HCP) under a tensile force. A three-dimensional (3D) multiscale mechanical model is established using the combined Discrete Element Method (DEM)-Molecular Dynamics (MD) method in LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). In the 3D model, HCP consists of discrete particles and atoms. Simulation results show that the combined DEM-MD model is computationally efficient with good accuracy in predicting tensile failures of HCP.

In this research, the models of four asphalt components (asphaltene, resin, aromatics and saturate) and five minerals (SiO2, Al2O3, CaO, MgO and Fe2O3) were constructed individually, and then the interface models were constructed by adding the asphalt components and minerals together. The interfacial behaviour at molecular scale was simulated by setting boundary conditions, optimising the structure and canonical ensemble. The mean square displacement and diffusion coefficient of particles were selected to study the diffusion of asphalt components on the surface of different minerals. The results show that increasing the temperature can accelerate the diffusion of asphalt components. The diffusion speed of asphalt components on the surface of Al2O3 is faster than other mineral crystals. The temperature sensitivity of diffusion coefficient of asphalt components on the surface of CaO is the maximum. The diffusion speed of asphalt components ranked roughly as their molecular weight: saturate > aromatics > res...

Stacked transition-metal dichalcogenides on hexagonal boron nitride (h-BN) are platforms for high-performance electronic devices. However, such vertical stacks are usually constructed by the layer-by-layer polymer-assisted transfer of mechanically exfoliated layers. This inevitably causes interfacial contamination and device performance degradation. Herein, we develop a two-step, low-pressure chemical vapor deposition synthetic strategy incorporating the direct growth of monolayer h-BN on Au foil with the subsequent growth of MoS2. In such vertical stacks, the interactions between MoS2 and Au are diminished by the intervening h-BN layer, as evidenced by the appearance of photoluminescence in MoS2. The weakened interfacial interactions facilitate the transfer of the MoS2/h-BN stacks from Au to arbitrary substrates by an electrochemical bubbling method. Scanning tunneling microscope/spectroscopy characterization shows that the central h-BN layer partially blocks the metal-induced gap states in MoS2/h-BN/Au ...

All-inorganic halide perovskites (IHPs) have attracted enormous attention due to their intrinsically high optical absorption coefficient and superior ambient stabilities. However, the photosensitivity of IHP-based photodetectors is still restricted by their poor conductivities. Here, a facile design of hybrid phototransistors based on the CsPbBr3 thin film and indium tin oxide (ITO) nanowires (NWs) integrated into a InGaZnO channel in order to achieve both high photoresponsivity and fast response is reported. The metallic ITO NWs are employed as electron pumps and expressways to efficiently extract photocarriers from CsPbBr3 and inject electrons into InGaZnO. The obtained device exhibits the outstanding responsivity of 4.9 × 106 A W-1 , which is about 100-fold better than the previous best results of CsPbBr3 -based photodetectors, together with the fast response (0.45/0.55 s), long-term stability (200 h in ambient), and excellent mechanical flexibility. By operating the phototransistor in the depletion regime, an ultrahigh specific detectivity up to 7.6 × 1013 Jones is achieved. More importantly, the optimized spin-coating manufacturing process is highly beneficial for achieving uniform InGaZnO-ITO/perovskite hybrid films for high-performance flexible detector arrays. All these results can not only indicate the potential of these hybrid phototransistors but also provide a valuable insight into the design of hybrid material systems for high-performance photodetection.

The service life of asphalt pavement is influenced by many factors, of which the properties of asphalt binder are the most important. The self-healing properties of asphalt binder counterac...

With the rapid development of optical-fiber sensing technology recent years, it has been widely used for various purposes in engineering fields. However, the strain concentration generated ...