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MoAlB powders with a purity of 96 wt.% were successfully fabricated by a laser‐induced self‐propagating method using molybdenum boride (MoB) and aluminum powders as starting materials under the conditions of an n(MoB): n(Al) ratio of 1.0:1.4 and the laser linear energy density (El) of 0.9 J/mm, and the effect of raw material composition and El on the phase composition and microstructure of the resultant MoAlB powders were investigated. The minimum reflection loss (RLmin) value and effective absorption bandwidth (EAB) of the as‐prepared MoAlB absorber with a thickness of 5.0 mm were only determined as −12.5 dB (at 16.9 GHz) and 0.9 GHz (16.4–17.3 GHz) in the frequency of 1–18 GHz, respectively. Nevertheless, the RLmin and EAB of as‐prepared MoAlB powders oxidized after 3 h at 773 K increased to −18.59 dB (at 15.82 GHz) and 2.13 GHz (15.22–17.35 GHz), respectively, demonstrating that the as‐prepared MoAlB powders are potential candidates for high‐temperature microwave absorption applications. This study proposes a new efficient strategy for the preparation of boron‐based ternary compounds for high‐temperature electromagnetic wave absorption application. [ABSTRACT FROM AUTHOR]

Flexible grippers require appropriate stiffness to ensure stability and efficiency in unpredictable environments. While combining materials with variable stiffness and elastomers holds significant promise in this regard, concurrently achieving actuation and stiffness modulation typically results in heightened structural complexity and responsiveness issues. In this study, a giant electrorheological dielectric elastomer (GERDE) with high dielectric and high electrorheological (ER) properties is obtained by introducing giant electrorheological particles into silicone elastomers, further substantiating the ability to functionally couple actuation and stiffness‐tuning, as well as application of a flexible gripper in mimicking emotive calligraphy. Specifically, GERDE exhibits better actuating (area strain rate of 33%) and ER performance (storage modulus increment of 1.5 MP) than existing conventional dielectric elastomer (DE) actuators (such as PDMS and VHB4910) under a low electric field. Compared to reported flexible grippers, bionic flexible grippers based on GERDE actuator have enhanced actuation, stiffness adjustment capability (i.e., stiffness is increased by 2.4 times), fast response (≈180 ms), and coupling effect, and can write Chinese calligraphy of different emotions by the same trajectory. This work provides ideas and methods for achieving the integration of actuator‐variable stiffness and emotional transmission in robots. [ABSTRACT FROM AUTHOR]

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis worldwide. In 2018–2022, we investigated the presence of HEV RNA in 1233 stool samples collected in the Qinghai‐Tibetan Plateau, including humans (16), Tibetan pigs (624), yaks (312), sheep (267), and dogs (14). HEV RNA was only detected in Tibetan pig faecal samples (18.27%, 114/624). To perform molecular characterization of HEV strains in Tibetan pigs, we obtained 21 complete HEV genome sequences between 2018 and 2022. Sequence comparisons showed that 21 HEV strains from Tibetan pigs shared the mean nucleotide identities with the reference HEV strains ranging between 82.9% and 94.9% and 89.3% and 92.1% similarities with human HEV strains. Phylogenetic analysis confirmed that all HEV strains were genotype 4, closely related to human HEV strains. Sequence recombinant analysis showed five potential recombinant strains identified in this study, of which SWU/D18/2018 (GenBank No. MK410044) was recombinant with human and swine HEV strains, located 6509–6878 nt from the recombination point. Based on the Bayesian evolutionary trees, we found that most HEV strains diverged later than human HEV (16 Tibetan pig HEV strains diverged later than 1979, and seven human HEV strains diverged earlier than 1979). Therefore, we speculated that the prevalence of HEV 4 in Tibetan pigs possibly originated from humans in the Qinghai‐Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Designing metallic cellular structures with triply periodic minimal surfaces (TPMS) is a novel approach for preparing multifunctional and lightweight metamaterials. TPMS‐structured Batwing Al cellular metamaterials are fabricated using selective laser melting. The mechanical performance, failure/deformation modes, and energy absorption capacity of the metamaterials are investigated. It is demonstrated in experimental results that the unit cell structure has a significant influence on the mechanical properties of the metamaterials, and that the sample with large wall thickness exhibits excellent mechanical properties and energy absorption capacity. Furthermore, the Gibson–Ashby equation is developed to estimate the mechanical properties of the Batwing‐type Al cellular metamaterials. Herein, a theoretical foundation is provided in these findings for the engineering application of phase‐pure Al, which is typically unsuitable as a structural material due to its low yield strength. [ABSTRACT FROM AUTHOR]

Functional single‐crystalline films with mechanical flexibility have attracted intensive interest due to excellent material quality and the wide applications in flexible electronics. However, the free‐standing single‐crystalline films with the thickness in sub‐micrometer range usually deform due to insufficient mechanical strength or internal stress. This study introduces a strain balanced model (SBM) of a sandwich structure and an ion slicing‐based strain compensation bonding method for fabricating ultrathin but self‐supporting single‐crystalline thin films. Based on the SBM and the strain compensation bonding method, a centimeter‐scale strain balanced LiNbO3 (LN) thin film (SB‐LNTF) consisting of two pieces of 550 nm single‐crystalline LN film and an intermediate layer of benzocyclobutene is successfully fabricated. In additional to flat, bendable, transparent, and lightweight, the fabricated ultrathin (<10 µm) SB‐LNTF also exhibits excellent self‐supporting property. Standard piezoresponse force microscopy amplitude butterfly curve and a 180° phase switching associated with ferroelectric behavior of LN film are observed, which confirm its high crystal quality of the ion sliced LiNbO3 thin film. A flexible acoustic resonator demonstrated on SB‐LNTF shows strong resonances. In principle, the strain compensation bonding method is also applicable to epitaxial lift‐off films. [ABSTRACT FROM AUTHOR]

Smart technologies bring innovation to the life and sports arena. To adapt to diverse play styles and improve unconventional technique of table tennis players, a smart table tennis racket with tunable stiffness based on anisotropic electrorheological elastomers (EREs) is developed. The EREs are prepared in the designed mold under the electric field to form an anisotropic structure that consisted of electrorheological particles and facilitated the generation of interparticle saturation surface polarization and the local electric field. Therefore, the electrorheological property of anisotropic EREs is significantly promoted, attaining a relative electrorheological effect of 17 160% in shear mode, and the incremental shear storage and compression modulus of 5.2 and 6.4 MPa. By applying an electric field, the smart racket successfully changes the trajectory of balls, reduced ejection angle by 11% and increased ejection velocity by 2%. [ABSTRACT FROM AUTHOR]

Identification of time delay is a prerequisite for the realisation of control compensation. The existing researches generally assume that the system input should be monotonic, which is unsuitable for online identification due to system saturation. To solve this problem, relaxed input conditions are developed in this Letter. Then a modified least-square algorithm with forgetting factors, which has a strong ability in tracking time-varying delays, is presented. Meanwhile, two extra terms whose design parameters are adjusted online according to the input condition are added into the covariance update law to guarantee the boundedness and robustness of the algorithm. Simulation results demonstrate the superiority of the proposed method and the reasonableness of the developed input conditions. [ABSTRACT FROM AUTHOR]

In this work, soft polydimethylsiloxane (PDMS) screen protectors with microlens arrays (MLAs) are fabricated through a feasible high‐throughput approach. Based on the lateral size scaling effect during discontinuous dewetting, desired SU‐8 convex MLAs with simultaneously controlled focal length (f) and numerical aperture (NA) are produced on a single substrate. A replication technique is employed to prepare PDMS MLAs with the same structure as that of the SU‐8 MLAs. The contact angle and other optical parameters of the MLAs can be tuned over a wide range based on the number of sliding times and lateral size. When the diameter of the MLAs decreases from 100 to 10 µm, the curvature changes from 0.07 to 0.17 for the single‐layer MLAs and from 0.15 to 0.31 for the three‐layer MLAs. The enhancement effect of MLAs on the light from wide‐angle organic light‐emitting diode (OLED) packaging modules is investigated. It is found that PDMS films containing MLAs can increase the brightness of an OLED by 14.13%. The fabricated PDMS concave MLAs can serve as flexible screen protectors to shield OLEDs from damage while enhancing the brightness to improve the energy efficiency. [ABSTRACT FROM AUTHOR]

Lightning is the main cause of transmission line failure, and it is important to improve the lightning protection level of the transmission line for the stability of the power system. Traditional solutions for the shielding failure of transmission lines is to use the electrical geometric model method. However, with the improvement of the voltage level, the physical size increases, and the calculation of lightning protection for ultrahigh-voltage dc lines has a greater difference with operating experience. Based on the Ningxia-Shandong dc transmission lines in China, this study utilised the lead development model to describe the flashover of insulators and the breakdown of the gaps. A comprehensive calculation method of shielding failure trip-out rate considering terrain, earth resistance and weather was proposed. The accuracy was much higher when compared with the traditional calculation and the result can be a reference for other similar calculation for dc lines. [ABSTRACT FROM AUTHOR]

A straight throughout superhydrophilic track that contains high contrast and directional wettability on a superhydrophobic surface is designed. Despite droplets that tend to slide more easily along a direction parallel to the track, it is found that such hybrid strip‐pattern surfaces have higher fog harvesting efficiency along a direction perpendicular to the tracks due to the larger accumulation area for droplet removal. [ABSTRACT FROM AUTHOR]

A modified least‐squares algorithm with forgetting factor is proposed and applied to linear time‐varying systems. The bound on the Euclidean norm of the estimation error is derived mathematically. When the bounded regressor of the linear time‐varying system satisfies persistent excitation condition, this new algorithm can attenuate the influences of bounded disturbances and the change ratio of time‐varying parameters effectively through extra term that is added to the covariance's update law. Contrary to the earlier proposed estimation laws, this algorithm does not require any prior knowledge of upper bounds on the parameters and the disturbances. Simulation results demonstrate the effectiveness of the identification law. [ABSTRACT FROM AUTHOR]

Discontinuous dewetting on a prepatterned surface with regions of different dewettability is an attractive way to assemble a material into 2D microstructures with a predefined lateral size and spatial distribution on a surface. However, few studies have examined the aspect ratio or contact angles of the microstructures. In this Communication, it is found that the static contact angle changes with the lateral size of droplets and variation relationship between them shows two phases: an exponential decrease phase when lateral size is <80 µm, and a minimum plateau phase when lateral size is >80 µm, which is defined as lateral size scaling effect. After dynamically studying the droplet generation, it is proposed that liquid retraction after liquid thin film ruptures is responsible for the lateral size scaling effect. The effect of liquid viscosity and sliding speed on the lateral size scaling effect is also assessed and the lateral size scaling effect in droplet evaporation models is investigated. Finally, differently oriented single metal‐organic framework crystal arrays based on the lateral size scaling effect are successfully fabricated. This work demonstrates a novel 2.5D top‐down strategy to guide bottom‐up assembly. Separated droplet arrays by discontinuous dewetting is systematically investigated and the relationship between the contact angle and lateral size of droplets as the lateral size scaling effect is defined. The lateral size scaling effect results from liquid retraction. Liquid viscosity and sliding speed can influence the effect and the lateral size scaling effect in droplet evaporation models is investigated. [ABSTRACT FROM AUTHOR]