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• CSMA offers excellent electromagnetic stealth performance for a variety of complex applications. • The dual structures synergistically drive the formation of current vector vortices to enhance the loss of electromagnetic wave energy. • CSMA has an effective absorption bandwidth of 6.07–18 GHz and a thickness of 4 mm. The amount of absorbent used is half that of a slab coating of equivalent thickness. The performance breakthroughs of some stealth materials have benefited from incorporating biomimetic concepts, and the design ideas of wave-absorbing metamaterials have been greatly broadened. However, stealth materials developed based on a single biological structure still have limitations regarding overall performance and design freedom. Herein, a dual-structure element combination model with a butterfly-wing porous structure and moth-eye raised structure arranged in an orderly manner is established. Carbonyl iron and polyurethane are mixed as wave absorbents, and the model is utilized to make a biomimetic metamaterial (CSMA), which has an absorption rate of more than 90 % at 6.07–18 GHz, achieving broadband effective absorption. It has been verified that the two biostructures designed after an ordered arrangement show synergistic effects in the combined model, and the cooperation between the structures induces the formation of current vector vortices, which are able to induce microwave losses to broaden the effective absorbing bandwidth. Further, the model has the combined application performance of polarization insensitivity, strong stability of oblique incidence, and low bistatic RCS. Such a thought based on the combination of multiple components provides an effective strategy for the design of broadband-absorbing metamaterials. [Display omitted] [ABSTRACT FROM AUTHOR]

Sensors, such as cameras, millimeter-wave radar, and LiDAR, are widely deployed in cooperative vehicle-infrastructure systems. The demand for calibration of initial installation, damage replacements, and unstable installation has risen dramatically. Traditional methods require on-site operation and road closure; thus, repeated calibration can severely affect traffic conditions and expose operational personnel to potential safety threats. As more and more autonomous vehicles (AVs) flood the roads, this paper proposes an automatic calibration framework of roadside sensors by leveraging the high-precision positioning and perception data of AVs. First, we design a graph-based target-matching algorithm using an AV’s surrounding traffic perception data to identify the AV of interest from a dataset of multiple target trajectories recorded by roadside sensors. A line search algorithm is then designed to adjust the clock delay between sensors and establish the temporal correspondence, where a Gaussian process is applied to estimate the vehicle state in continuous time. Finally, we develop a least squares optimization model to complete the final calibration with the AV positioning data. The influence of measurement noise and missed detections on the proposed calibration framework are analyzed in simulated scenarios based on a Next Generation SIMulation (NGSIM) dataset, and the practicability is validated based on real-world data collected at Donghai Bridge, Hangzhou Bay Bridge, and DAIR-V2X dataset. It is shown that the proposed target matching algorithm can identify an AV trajectory from roadside sensor data with 20%-90% higher accuracy than baseline models, and the framework can accurately estimate the spatial and temporal parameters even with poor data quality. The mean least squares error of the trajectory alignment reaches centimeter-level accuracy.

• The proposed UWMA has excellent electromagnetic stealth performance and is suitable for various complex applications. • The perfect combination of cut-wire metasurface with local-chiral characteristics and magnetic mediums enhances the intrinsic attenuation while also reduces the deterioration of absorption property caused by constructive interference. • The effective absorption bandwidth of UWMA can reach 15.1 GHz with a thickness of only 3.9 mm. Metamaterials with artificial designability and perfect absorption provide a novel design method for the manipulation and attenuation of microwaves. However, owing to the limitations of meta-atomic resonance effect and the lossless medium, it is difficult to achieve effective microwave absorption in a broadband frequency range. Hence, an ultra-wideband metamaterial absorber (UWMA) composed of two magnetic media and a metasurface was designed, and the absorption bandwidth of 2.9 to 18 GHz for 90% absorptivity under normal incidence was achieved, covering almost the entire S, C, X, and Ku bands. Through detailed investigation of equivalent circuit, equivalent medium theory, electromagnetic field distribution and front-back interface interference, the internal physical working mechanism was clarified essentially. In addition, the multi-environment adaptabilities of the proposed absorber, including polarization sensitivity, large angle incidence, dual-station radar stealth, bearing capacity and corrosion resistance, were analyzed. The proposed metamaterial absorber presents an effective way to achieve ultra-wideband absorption and compatibility with environmental adaptability, and provides a new way of thinking for intelligent full-band stealth technology. [Display omitted] [ABSTRACT FROM AUTHOR]

Luminescent nanomaterials with outstanding optical properties have attracted growing interest due to their widespread applications. However, large-scale fabrication of luminescent nanomaterials with desired properties through a simple and economical process remains challenging. As a renewable natural resource, starch is non-toxic, easily accessible, and inexpensive, making it a popular choice for uses in various biomedical fields. In this work, we present a facile assembly strategy for the fabrication of starch-based luminescent nanoaggregates using starch as the host material and aggregation-induced emission luminogens (AIEgens) as guest molecules. By employing simple procedures under mild conditions, highly luminescent nanoparticles with small sizes, high water dispersibility, and low cytotoxicity are prepared on a large scale. The resulting nano-assemblies demonstrate significantly enhanced fluorescence intensities, reduced susceptibility to photobleaching and low cytotoxicity. These fluorescent supramolecular aggregates can be employed in various application fields, including the fabrication of fluorescent hydrogels, fingerprint detection, cell imaging and in vivolymphatic system imaging. The methodology developed in this work has immense potential to greatly promote the production of high-quality nanoparticles on the industrial scale, offering a cost-effective solution that can meet the needs of various applications and pave the way for wider implementation of nanotechnology.

Purpose: The purpose of this study is to discover the uniqueness of China's online livestreaming industry and to make preliminary predictions about its future. Design/methodology/approach: Providing a panoramic description of China's online livestreaming industry and a comparative analysis with other countries' online livestreaming industries. Findings: China's online livestreaming industry is world leader in general. In terms of user size and age structure, although China has a high proportion of online livestreaming users, the proportion of anchors is not high, while the age structure of users in both China and other countries shows the characteristics of younger users. In terms of policy, the difference between China and foreign support in online livestreaming is small, but developed countries have stricter regulations. Originality/value: The research in this paper has great significance in gaining an in-depth understanding of the development status and trends of China's online livestreaming industry and in designing accurate support policies.

• The TiN/BN composite has been constructed via the in-situ synthesis method. • The stable dielectric loss ensures that TiN/BN composite exhibits robust high-temperature absorption properties at X-band. • The stable cyclic microwave absorption properties of TiN/BN composites provide a reliable guarantee for practical applications. High-efficiency and temperature-insensitive microwave absorbing materials (MAMs) are ideal for high-temperature electromagnetic attenuation. Herein, the titanium nitride/boron nitride (TiN/BN) composite with TiN as the loss unit and BN as the impedance matching unit has been constructed by the in-situ synthesis method. The insulating BN not only effectively regulates and optimizes the conductivity and impedance matching of the material but also imparts steady cyclic microwave absorption properties. The steady dielectric loss ensures that TiN/BN composite has robust high-temperature absorption properties at X-band, with a minimum reflection loss (RL min) of −16.74 dB at 873 K and an effective absorption bandwidth (EAB) of 3.26 GHz in the temperature range of 293–873 K. Compared with the TiN/SiO 2 absorbers with a single system, the TiN/BN/SiO 2 composite keeps reliable high temperature absorbing properties at 873 K. This work confirms that wave-transparent materials for dielectric property modulation can resolve poor temperature stability of effective absorption and non-reusability for high-temperature absorbing materials, providing inspirations for designing efficiency high-temperature microwave absorbers. [Display omitted] [ABSTRACT FROM AUTHOR]

Electromagnetic (EM) absorbers serving in the megahertz (MHz) band and a wide temperature range (from −50 to 150 °C) require high and temperature-stable permeability for outstanding EM absorption performance. Herein, FeCoNiCr0.4CuXhigh-entropy alloy (HEA) powders with a unique nanocrystalline structure separated by a thin amorphous layer (NTA) are designed to improve permeability and enhance intergranular coupling. Simultaneously, the long-range anisotropy is introduced via devising the preparation process and tuning the chemical composition, such that the intergranular exchange interaction is further strengthened for stable permeability and EM wave absorption in a wide temperature range. FeCoNiCr0.4Cu0.2HEAs exhibit a near-zero permeability temperature coefficient (5.7 × 10–7°C–1) a in wide temperature range. The maximum reflection loss (RL) of FeCoNiCr0.4Cu0.2HEAs is higher than −7 dB with 5 mm thickness at −50–150 °C, and the absorption bandwidth (RL < −7 dB) can almost cover 400–1000 MHz. Furthermore, FeCoNiCr0.4Cu0.2HEAs also have a high Curie temperature (770 °C) and distinguished oxidation resistance. The permeability temperature dependence of FeCoNiCr0.4CuXHEAs is investigated in-depth in light of the microstructural change induced by tuning the chemical composition, and a new inspiration is provided for the design of magnetic applications serving in wide temperature, such as transformers, sensors, and EM absorbers.

Due to the opposite stealth mechanisms of radar and infrared waves, and the lack of narrow-band absorption at a single frequency point in metamaterials, it is difficult for low-frequency broadband radar and infrared waves to be compatibly stealthy at thin thickness. In order to solve the problem, Minkowski-like fractal metamaterial with frequency-selective surface of ''passing-low-frequency and blocking-high-frequency'' property is designed. The multiscale property of Minkowski-like fractal constructs multiple absorption frequency points and its suitable iteration factor achieves broadband reconfiguration of the absorption frequency points, which enables broadband absorption in S and C bands. Besides, the magneto-electric dual loss mechanism brought by the fractal and the intrinsic loss of the medium are the most fundamental reasons for the stealth being caused. In addition, the selection of iterative cell with infrared emissivity below 0.3 and the self-similarity property of Minkowski-like fractal make the metamaterial embody excellent infrared stealth performance. Ultimately, the 2.24 mm thick fractal metamaterial achieves cross-band radar wave absorption in the range of 3.41–5.82 GHz while being compatible with infrared wave stealth. The layered fractal model provides a new design idea for broadband stealth under multi-band compatible stealth.

Glucagon like peptide‐1 (GLP‐1) is an effective hypoglycemic drug that can repair the pancreas β cells and promote insulin secretion. However, GLP‐1 has poor stability and lacks of target ability, which makes it difficult to reach the site of action to exert its efficacy. Here, GLP‐1‐expressing plasmids are introduced into the Escherichia coliNissle 1917 (EcN) and a lipid membrane is formed through simple self‐assembly on its surface, resulting in an oral delivery system (LEG) capable of resisting the harsh environment of the gastrointestinal tract. The system utilizes the chemotactic properties of probiotics to achieve efficient enrichment at the pancreatic site, and protects islet β cells from destruction by regulating the balance of immune cells. More interestingly, LEG not only continuously produces GLP‐1 to restore pancreatic islet β cell function and secrete insulin to control blood sugar levels, but also regulates the intestinal flora and increases the richness and diversity of probiotics. In mice diabetes models, oral administration of LEG only once every other day has good biosafety and compliance, and achieves long‐term control of blood glucose. Therefore, this strategy not only provides an oral delivery platform for pancreatic targeting, but also opens up new avenues for reversing diabetes. Inspired by the ability of engineered probiotics to secrete protein, an in situ “pharmaceutical factory” (LEG) to produce GLP‐1 for long‐term glycemic control and islet β cell repairment is developed. LEG has good stability in the gastrointestinal environment and can target the pancreas. LEG can also regulate the intestinal flora and increase the richness and diversity of probiotics.

With the continuous development of electromagnetic wave-absorbing materials, the design of artificial structures for electromagnetic absorbers based on the concept of metamaterials is becoming more abundant. However, in the design process, it is difficult to further broaden the effective absorption band due to the limitation that the traditional single-size structure responds to electromagnetic waves only in specific frequency bands. Therefore, in this paper, based on the moth-eye bionic hexagonal structure absorber with antireflection performance, an Archimedean tiling structure is designed to optimize it, and through the introduction of a variety of primitives with large differences in dimensions, a multifrequency band-response mechanism is achieved to enhance the multireflection mechanism, which can effectively broaden the absorption band and improve the wave absorption performance. Ultimately, the moth-eye bionic structure absorber optimized by (3.4.6.4) can achieve an effective absorption of 10.26 GHz at a thickness of 2 mm. This work presents a new idea for the design work of electromagnetic wave-absorbing metamaterials, which has a broad application prospect in the aerospace, electronic information countermeasures, communication, and detection industries.

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Metamaterial has received widespread research in the fields of electromagnetic stealth due to its characteristics of strong resonance and flexible designability. However, a lack of a comprehensive understanding of the internal physical mechanism still imposes certain limitations on broadband absorption designs. Hence, this work proposes a new strategy for the broadening of the working frequency band of metamaterial absorbers by constructing local-chiral features to regulate the amplitude and phase information. The absorber consists of staggered cut-wire metal patterns with lumped resistors placed at the center position determined by characteristic mode analysis. Combining the modal significance, equivalent circuit, surface current, electric field distribution, and symmetry model theory, the working mechanism for wideband absorption performance has been analyzed in detail. The experimental results are in good agreement with the simulation results; the absorption rate exceeds 82% in the frequency range of 4.5–11.7 GHz and surpasses about 90% in the frequency range of 4.7–10.8 GHz under transverse electric (TE) or transverse-magnetic (TM) polarizations. Compared to the case without chiral features, the proposed design can achieve a 28% increase in operating bandwidth. The proposed design method is applicable for the optimization of various typical dipole-type metamaterial absorbers and provides a novel strategy for future wideband metamaterial absorption.

In this study, using nickel nitrate and waste cotton as precursors, porous carbon combined with well-dispersed Ni nanoparticles were formed via an in-situ growth strategy. Due to the distinction of complex permittivity among different components, the expanded interface in the Ni/C heterostructure could improve the interfacial polarization relaxation, which lead to the enhanced dielectric loss and EM absorbing capability. The results show that excellent microwave absorption properties could be exhibited over a wide frequency range with a filler loading of only 10 wt.%, which compete well with what has been observed in the carbon-based composites with much higher filler loadings. This work provides a low-cost and effective approach for lightweight and high-efficiency microwave absorption, which also greatly facilitates the recycling of waste cotton.

In this study, two new functionalized polyethylenimine (PEI), PEIR and PEIQ, have been synthesized by covalently conjugating rhodamine 6G (R6G) or 8-chloroacetyl-aminoquinoline (CAAQ) and have been investigated for their sensing capabilities toward metal ions and anions basing on fluorescence on–off and off–on mechanisms. When triggered by protons, metal ions, or anions, functionalized PEIs can behave as a fluorescence switch, leading to a multiaddressable system. Inspired by these results, functionalized PEI-based logic systems capable of performing elementary logic operations (YES, NOT, NOR, and INHIBIT) and integrative logic operations (OR + INHIBIT) have been constructed by observing the change in the fluorescence with varying the chemical inputs such as protons, metal ions, and anions. Due to its characteristics, such as high sensitivity and fast response, developing functionalized PEI as a new material to perform logic operations may pave a new avenue to construct the next generation of molecular devices with better applicability for biomedical research.

This study used fly ash-slag geopolymer to stabilize silty clayey dredged materials (DM) with recycled glass fibre reinforced plastic (GFRP) fibre. The effects of stabilizer content and fibre content on the mechanical properties of stabilized DM were studied and compared with the reinforced cement stabilized DM. The unconfined compressive strength (UCS) and indirect tensile strength (ITS) of stabilized DM were tested, and the prediction model of bearing capacity was established. The stabilization mechanism was analysed by the microstructural characterization with the scanning electron microscope (SEM). It was found that the post-failure ductility of stabilized DM significantly increased as the content of recycled GFRP fibre increased. When 5 wt% of the fibre was incorporated, both geopolymer and cement stabilized DM reached a maximum strength of 1300kPa and 2200kPa, respectively. As the fibre content further increases, the excessive fibre content would cause agglomeration and deteriorate the mechanical properties. The carbon footprint and cost of geopolymer stabilized DM were reduced by 55% and 26% compared with cement stabilized DM, respectively. This suggests that recycled GFRP fibre incorporated geopolymer provided a potential for being a green DM stabilizer.

Recent developments in the rational design and the controlled assembly of nanoscale building blocks have resulted in functional devices such as nano-optoelectronics, novel contrast probes for molecular imaging, and nanosensors. In the present study, we designed and synthesized a hybrid nanomaterial consisting of [Ru(bpy)3]2+-encapsulated silica nanoparticles (SiNPs) and gold nanoparticles (AuNPs) through peptide-bridged assembly in a controllable way. A peptide that contains recognition sequence DEVD specific for active caspase-3 cleavage was employed to bring SiNPs and AuNPs into close proximity through specific molecular recognition. A FRET system with SiNPs as energy donors and AuNPs as energy acceptors has been thus developed and applied for caspase-3 detection. A change in distance between the two building blocks resulted in a change in FRET efficiency, causing a ratiometric change in emission. Caspase-3 triggers the cleavage of the peptide links between the two nanoparticles and releases AuNPs from the nanohybrids, inducing the activation of SiNPs to the “ON” state. The fluorescence turn-on response is specific to caspase-3 and allows the detection of caspase-3 as low as 0.05 U mL-1(∼6 pM).

The rational structure-effect relationship design of microwave absorption devices provides tremendous potential for the elimination of electromagnetic radiation contamination. Here, we report on the efficient microwave absorbers (MA) consisting of TiN/Fe2Ni2N nanoribbons (NRs) and nanoparticles (NPs) as a functional MA filler. The cross-linked network and multiple heterogeneous interface polarization of TiN/Fe2Ni2N NRs contributes to improved conductance loss and polarization loss and is favorable for obtaining the lightweight MA absorber at a low filler content of 15 wt%. As a comparison, due to the enhanced permeability and balanced permittivity, the maximum reflection loss of the NPs filled absorber can reach −31.9 dB at a filler thickness of 1.3 mm at a high filler content of 50 wt%. This work deepens the understanding for designing the high-performance MA through tuning and optimizing the dielectric and magnetic loss.