Achieving high-performance electromagnetic microwave absorption requires materials that simultaneously exhibit strong absorption, broad effective absorption bandwidth (EAB), minimal thickness, and low density. Synergistic structural and material engineering presents a promising avenue toward this goal. Herein, an ultralight, anisotropic aerogel with hierarchical macro-micro-nanoscale architecture is fabricated via a temperature-gradient-directed assembly strategy. The aligned lamellar structures, abundant and tunable heterointerfaces among hybrid nanosheets, high magnetocrystalline anisotropy, and synergistic magnetic-dielectric coupling collectively contribute to optimized impedance matching, frequency-tunable broadband absorption, and pronounced microwave attenuation. With an ultralow density of 0.009 g cm-3, the resulting MXene/reduced graphene oxide/Fe3O4 nanorod aerogel (MGFA) delivers tunable multiband absorption spanning 4.4-18 GHz, which fully covers the C- (4-8 GHz), X- (8-12 GHz), and Ku- (12-18 GHz) bands. Remarkably, at a thickness of 3.5 mm, the aerogel achieves an exceptional minimum reflection loss (RLmin) of -53.4 dB and an EAB of 5.4 GHz, encompassing the entire X-band and part of the Ku-band. Furthermore, MGFA demonstrates outstanding compression resilience, sustaining 100 cycles at 50% strain without structural failure. This innovative design, enabling multiscale structural control and flexible material configuration, provides a viable strategy for developing advanced microwave-absorption materials suited for both civilian and military applications.

With the ever-increasing demand for high-energy-density lithium-ion batteries (LIBs) in multiscale energy storage, safety concerns have emerged as critical obstacles hindering their widespread application. The excess heat generated during the electrochemical process, if not properly managed, can accumulate and accelerate the aging of key cell components, potentially leading to catastrophic thermal runaway events such as fires and explosions. Thus far, considerable attention has been devoted to alleviating intense thermal runaway through fire-safe materials and energy-intensive thermal management technologies. However, the stabilization of the electrochemical environment through intrinsic thermal dissipation and temperature regulation governed by key material design has received comparatively little consideration. This paper aims to summarize the mechanism of thermal runway and highlight material advances for safer LIBs, with particular emphasis on the thermal-electrochemical synergy in mitigating localized overheating, stabilizing the electrochemical environment, and improving electrochemical performance. Subsequently, recent research progress in thermal management materials and strategies for dynamic temperature regulation is reviewed. Finally, current challenges are discussed, and future directions are proposed for material innovations that can be applied to high-energy-density and high-safety LIBs.

In this letter, a dual-wideband bandpass filter (BPF) covering 22.4-29 GHz (25.7%) and 36.85-45.2 GHz (20.4%) is designed in one substrate-integrated waveguide (SIW) cavity. It has one SIW cavity and two multimode resonant structures (MMRSs) consisting of one nonuniform H-shaped structure (NHS) and two L-shaped structures (LSs). There are six resonant modes, including the TE110 and TE120 modes of SIW cavity, two self-resonant modes from NHS, and a pair of odd and even modes from LSs. Four transmission zeros (TZs) are generated through their cross-coupling without any filtering circuit. As seen from design results, it provides a great candidate for 5G mmWave applications owing to its wide bandwidth, self-packaging, and easy integration.

In this letter, a wideband bandpass filter (BPF) is proposed for the first time by embedding a multimode resonator (MMR) in one substrate integrated waveguide (SIW) cavity. This design has a wide bandwidth by combining the fundamental mode of SIW (i.e., TE110 mode) and the separated odd/even modes of MMR. A filter covering 22.24-31.74 GHz is obtained to behave low insertion loss, high selectivity, wide operating bandwidth, and high out-of-band suppression. The measured results show that this filter could provide a promising candidate for the fifth-generation (5G) millimeter-wave (mmWave) communication systems.

The advancement of multispectral surveillance technologies has rendered conventional single-band camouflage materials ineffective, driving an urgent demand for multispectral-compatible stealth materials. Herein, we report a multidimensional MXene-based composite aerogel engineered via cost-effective lyophilization for radar-infrared compatible camouflage. As building blocks, few-layer Ti3C2Tx MXene nanosheets functionalized with NiB alloy nanoparticles and thermoresponsive VO2 phase-change materials are cross-linked by poly(vinyl alcohol) to construct the MXene/NiB/VO2 composite aerogel through one-step cryo-assembly. The composite demonstrates a remarkable multispectral stealth performance. The thermal radiation temperature of a heated target is reduced from 180 to 55 °C. In addition, a minimum reflection loss (RLmin) of -54.7 dB with an effective absorption bandwidth of 7.1 GHz (8.8-15.9 GHz) at an ultralow low density of 19 mg·cm-3 has been achieved. These breakthroughs stem from synergistic mechanisms: low infrared emissivity, suppressed thermal conduction, dynamic temperature regulation via the VO2 phase transition, and multimodal electromagnetic dissipation. This work establishes a material design paradigm to reconcile infrared-microwave spectral incompatibilities through multidimensional heterostructure engineering, providing a roadmap for next-generation adaptive multispectral stealth technologies.

This article proposes a novel fractional heterogeneous neural network by coupling a Rulkov neuron with a Hopfield neural network (FRHNN), utilizing memristors for emulating neural synapses. The study firstly demonstrates the coexistence of multiple firing patterns through phase diagrams, Lyapunov exponents (LEs), and bifurcation diagrams. Secondly, the parameter related firing behaviors are described through two-parameter bifurcation diagrams. Subsequently, local attraction basins reveal multi-stability phenomena related to initial values. Moreover, the proposed model is implemented on a microcomputer-based ARM platform, and the experimental results correspond to the numerical simulations. Finally, the article explores the application of digital watermarking for medical images, illustrating its features of excellent imperceptibility, extensive key space, and robustness against attacks including noise and cropping.

In this paper, a fractional-order hyperchaotic system based on dual memristors is proposed by introducing flux-controlled and charge-controlled memristors into a simple RLC circuit. Dynamics of the hyperchaotic system are investigated using bifurcation diagrams, Lyapunov exponents spectrum (LEs), phase diagrams, time-domain diagrams, spectral entropy (SE) and C0 complexity. The results show that it has a plane of equilibria and exhibits rich dynamical characteristics, including hyperchaos, homogeneous and heterogeneous extreme multistability. Meanwhile, the transient transition phenomena as well as the effect of parameters on the complexity and chaotic behavior of the system are also studied. Furthermore, the practical implementation of the system is realized through analog and digital circuit. The experimental results validate the correctness of the theoretical analysis and help to make better use of the hyperchaotic system in applications such as secure communications.

Synaptic crosstalk significantly influences neural firing in the brain. Locally-active memristors can effectively emulate neural network synapses and have a significant importance in neural network research. This paper designs a tristable locally-active memristive model and presents a novel fractional-order (FO) heterogeneous neuron network. This neural network consists of Hindmarsh-Rose (HR) neuron and FitzHugh-Nagumo (FHN) neuron, which are connected by coupling FO locally-active memristors. The research found that changes in the order of different dimensions have a significant effect on the neural network firing through the three-parameter bifurcation diagram. Moreover, it is found that the locally-active memristor as a synapse can affect the coexistence firing behavior of the network. The complex dynamics have been studied numerically by using phase diagrams, Lyapunov exponent spectrum, bifurcation diagram and extreme multistability can be found. In particular, the system can generate a complex bursting behavior in the presence of an external current. In order to verify the accuracy of the simulation, the phase diagram of FO heterogeneous neuron network is implemented by STM32 microcontroller, and results of the experiments are in great agreement with results of the numerical simulations. Finally, an image encryption and hiding method based on FO heterogeneous neuron network and discrete wavelet transform (DWT) is proposed. The experimental results demonstrate that the encryption and hiding scheme has excellent security and strong robustness.

This paper investigates a fractional-order Rulkov neuron model with discrete memristor under external electromagnetic radiation. The magnetic flux fluctuation crossing the neuron membrane is used to emulate the influence of electromagnetic radiation. The dynamics of the proposed fractional-order memristive Rulkov (FOMR) neural model are discussed using phase attractors, maximum Lyapunov exponents, bifurcation diagrams, etc. The FOMR neural model proposed exhibits not only extreme multi-stability and pervasive microchaos phenomena, but also demonstrates rich high-complexity dynamic behaviors. Digital implementations based on ARM are employed to validate the numerical simulation results. Finally, employing a method that combines Discrete Wavelet Transforms, Discrete Cosine Transforms, and chaotic index scrambling, a high-security digital watermarking scheme based on the FOMR neuron model for chaotic sequence encryption is proposed, which owns great keyspace and good encryption effect.

In this paper, a compact dual-band bandpass filter is proposed based on a multimode resonator (MMR). The proposed filter consists of two novel circular-ring-shaped parallel coupling lines (PCLs), a multimode resonator (MMR), and a circular substrate integrated waveguide (SIW) cavity. The two PCLs work as the input and output of the filter. The SIW cavity avoids the electromagnetic crosstalk from/to other passive components in microsystems. In this design, transmission zero-points are generated by introducing open-circuit branches at both sides of the MMR. The MMR is optimized to behave with two resonant frequencies in the first band and one resonant frequency in the second band. The best advantage of this design is to fully utilize vertical space in a multi-layer PCB structure. Consequently, the designed filter has a lateral size of 0.051 lambda gx0.051 lambda g (lambda g: the waveguide wavelength at 28.25 GHz), and has two 10-dB impedance matching bandwidths of 25.87-31.70 GHz and 40.27-40.62 GHz, where the insertion loss within the passband is less than 0.2 dB.

Solar-driven CO2 conversion to valuable products is a promising way to realize a carbon-neutral economy. Great progress has been made on photothermal catalysts with high selectivity and activity, but improved materials via a more efficient and cost-effective synthetic strategy are needed. Herein, we present a one-pot synthetic strategy of nickel/metal oxide nanostructured chains for the photothermal conversion of CO2 into methane. Nickel ions were in-situ reduced in a growth solution in the presence of alumina nanocrystals, where the formation and assembly of magnetic nickel nanoparticles decorated with Al2O3 nanocrystals simultaneously proceeded. The obtained composite nanochains exhibited a stable production rate of CH4 as high as 128mmol·gcat−1·h−1 with ~ 99% selectivity in continuous cycling test. The structure analysis of the Ni/Al2O3 composite indicates that a small amount of Al2O3 nanocrystals introduced in the nanocomposites not only ensures sufficient active site exposure to reactive molecules but also prevents the nickel nanoparticles from drastically sintering at high temperatures. The flexibility of this rapid synthesis strategy is also verified by using titania for the synthesis of Ni/TiO2 nanocatalysts, and stable catalytic performance has been achieved, suggesting its potential for practical solar-driven CO2 hydrogenation to valuable fuels.

The dynamic behaviors of coupled neurons with different mathematical representations have received more and more attention in recent years. The coupling among heterogeneous neurons can show richer dynamic phenomena, which is of great significance in understanding the function of the human brain. In this paper, we present a fraction-order heterogeneous network with three neurons, which is built by coupling an FN neuron with two HR neurons. Complex electromagnetic surroundings have meaningful physical influence on the electrical activities of neurons. To imitate the effects of electromagnetic induction on the three-neuron heterogeneous network, we introduce a fraction-order locally active memristor in the neural network. The characteristics of this memristor are carefully analyzed by pinched hysteresis loops and its locally active characteristic is proved by the power-off plot and the DC v-i plot. Then, the parameter-dependent dynamic activities are investigated numerically by using several dynamical analysis methods, such as the phase diagrams, bifurcation diagrams, Lyapunov exponent spectra, and attraction basins. In addition, the network also reveals rich dynamic behaviors, including coexisting activities, anti-monotonicity phenomena, transient chaos and firing patterns, providing support for further investigating the firing patterns of the human brain. In particular, complex dynamics, including coexisting attractors, anti-monotonicity, and firing patterns, can be influenced by the order and strength of electrical synaptic coupling and electromagnetic induction. The control of the bistable state can be realized through the time feedback control method, so that the bistable state can be transformed into an ideal monostable state. The study of the fraction-order memristive neural network may expand the field of view for understanding the collective behaviors of neurons. Finally, based on the ARM platform, we give a digital implementation of the fraction-order memristive neural network, which can verify the consistency with the numerical simulation results. In the future, we will explore more interesting memristive neural networks and study different types of methods to control the firing behaviors of the networks.

This paper proposes a fractional-order memristor-coupled Hindmarsh–Rose neurons model, which the number and stability of equilibrium points are related to the coupling strength. By Lyapunov exponent spectrum, local attraction basins, spectral entropy and so on, firing pattern transition of the system is revealed. In order to deeply expose information transmission in neural networks, the bifurcation behavior of different neuronal orders is studied by three dimensional two-parameter bifurcation diagram. Furthermore, when external stimulus is applied to a neuron, the system produces anti-monotonicity and bursting behavior. A microcontroller based on ARM is used to implement the system and verify various firing activities. Finally, we use the properties of the chaotic system to design a medical image encryption algorithm based on the region of interest. Numerical simulation results demonstrate that the proposed algorithm can improve the security of medical image transmission and resource utilization. It provides strong resistance against attacks to ensure privacy.

Severe surface oxidation and sluggish kinetic rates of Mg hydrides (MGHs) are the main bottlenecks for their industrial applications. Herein, we present a strategy to simultaneously tackle these problems. The nano-size MGHs were encapsulated in nitrogen-doped graphene nanospheres (NGNSs) via a facile wet-chemical method. This configuration not only prevented the MGHs from oxidation when exposed to air even after a long duration, but also stimulated faster kinetic rates of hydrogen absorption and desorption owing to the nano-size effect of MGHs and the unique electronic structure of NGNSs. As a result, MGHs of ca. 20 nm were coated by a few layered NGNSs to form MGH@NGNSs nanocomposite. A high hydrogen absorption capacity of 6.5 wt% was achieved at 200 degrees C within 0.4 h, with a releasing hydrogen capacity of 5.5 wt% at 300 degrees C within 0.5 h, indicating that this composite has obtained remarkably hydrogen storage performance. Density Functional Theory (DFT) based calculations suggested that the hydrogen adsorption/desorption kinetics were significantly fast at the interface of Mg surface and NGNSs with pyridinic configuration. This strategy paves a way for the development of high-performance Mg-based hydrogen storage materials for industrial applications.

This paper proposes a double-layered Huygens’ metasurface unit cell operating at 20 GHz for metasurface design. The unit cell consists of two E-shaped metal structures with the completely same size and opposite directions, and the structures are etched on two sides of one-layer dielectric substrate. When the overlapping area of the top and bottom structure of the proposed unit cell generates surface current in the opposite direction, a loop current can be formed, and then a fictitious magnetic dipole can be generated. Compared with the conventional metasurface unit cells achieving 360° phase coverage by using at least three layers, the proposed Huygens’ unit cell has two layers and only one structural parameter needs to be changed. It is observed from simulation results that the proposed unit cell can achieve 360° transmission phase coverage and transmission amplitude within -2 dB. Therefore, the proposed Huygens’ unit cell has a good application prospect in meta-surface design.

A broadband differentially fed slant ±45° dual-polarized stacked patch antenna is presented to cover 2.3–5 GHz for base station applications. In this letter, both semicircular and sector loaded slotlines are employed to generate three resonant frequencies. A slotted ring is utilized to generate a new resonant frequency, and could make the radiation patterns stable at high frequencies. To verify antenna performances, the proposed design is fabricated. From measurement, it is seen that its relative impedance bandwidth achieves 75.9% (2.28–5.07 GHz), and its port isolation reaches more than 35 dB. Moreover, in the whole band, the gain variation is smaller than 0.8 dB. Therefore, the proposed design could provide great candidate for LTE/5G base station applications.

In this article, a novel ultra-wideband circularly polarized (CP) orthogonal magnetic dipole (OMD) antenna array with a dual-mode sequential rotation feeding (SRF) networks is proposed for the millimeter-wave (mm-wave) applications. Above all, a novel OMD concept model is proposed. Subsequently, based on the conceptual model, a planar CP OMD antenna element is designed and analyzed, and its axial ratio (AR) bandwidth is enhanced by using parasitic patches. To further achieve a wider AR bandwidth and a higher gain, a dual-mode SRF network is proposed and designed to form a $4\times4$ CP antenna array. Finally, the antenna array is fabricated and measured to verify the design. The measurement results of the proposed $4\times4$ CP array show a −10-dB impedance bandwidth of 88.3% (18.15–46.85 GHz) and a 3-dB AR bandwidth of 61.0% (20.5–38.5 GHz) with a peak gain of 16.8 dBic. The proposed antenna array boasts several advantages, such as wide impedance and AR bandwidths and ease of integration, making it suitable for a wide range of applications in fifth-generation (5G) mm-wave communication systems.

Progressive advancement in modern detection technologies entails multispectral compatible camouflage. Previously, infrared camouflage materials, such as photonic crystals and metamaterials, have been developed, but improved multispectral compatibility, easy fabrication, and cost-effectiveness remain a challenge. Here, we report a nanostructured composite film based on oxalate-rich porous alumina (OPA) for visible-to-infrared compatible camouflage and simultaneous thermal management. The nanostructured composite film consists of a visible-transparent OPA layer, a composite layer of OPA/metal oxides, and an aluminum substrate. Each functional layer exhibits desirable reflection/emission properties for infrared and visible camouflage. Infrared camouflage is realized by the high reflection (low emission) of the metal substrate in both infrared-detected bands (3-5 and 8-14 μm). Meanwhile, radiative cooling arising from the intrinsic absorption of oxalate in the undetected band (5-8 μm) enhances surface heat dissipation. In addition, background-matching colors can be tuned by the metal oxides in the composite layer for visible camouflage, such as green for forest and brown for desert. This work provides a facile strategy to modulate multispectral absorption/emission properties with much flexibility and thus has great potential for energy conversion and stealth applications.

In this paper, we proposed a novel tri-stable nonvolatile locally active memristor and analyzed its nonvolatile and locally active characteristics. The phenomenon of edge of chaos in a certain voltage range is found. When the memristor is applied in a simple series circuit with an inductor and a DC power, we can observe Hopf bifurcation and periodic oscillation in the edge region of chaos. When the proposed locally active memristor is applied to the simplest chaotic circuit, some double coexisting phenomena can be observed from coexisting attractors and attraction basin. Furthermore, a color image encryption scheme based on DNA coding is proposed using the proposed memristive chaotic system, and the security of the scheme is evaluated by statistical analysis and different attacks. Finally, the proposed memristive chaotic system is implemented based on ARM platform; at the same time, a color image encryption scheme on DNA encoding and chaotic sequence is implemented in ARM platform. The experimental results are in good agreement with the numerical simulation.

Thirteen to 30 days after unilateral visual cortex ablation or after ablation and complete transection of the corpus callosum, high-frequency callosal stimulation inhibited spontaneous and evoked unit activity in most cells sampled in the intact contralateral visual cortex. On the other hand, few units were excited by callosal stimulation. Since orthograde degeneration of callosal fibers should be complete by 11 days after the lesion, these effects are interpreted as resulting from antidromic activation of axon collaterals of callosal-projecting visual-cortex neurons. The antidromic inhibition was found to occlude orthodromic inhibition evoked by lateral geniculate stimulation and was often facilitated by a preceding brainstem reticular stimulation.