Developing a low-frequency tunable microwave absorber for the normal use of sophisticated electric devices is an urgent requirement for dealing with electromagnetic pollution. Herein, we report the designed synthesis of a three-dimensional (3D) heterostructure constructed from multidimensional components, namely, MXene/CoNi/N-CNTs (nitrogen-doped carbon nanotubes). A uniform metal–organic-framework (MOF) ZIF-67/Co–Ni layered double hydroxide (LDH) core-shelled structure was first synthesized and then transformed into CoNi/N-CNTs via pyrolysis under a N₂ atmosphere. Then, CoNi/N-CNTs were deposited on the surface of 2D MXene by electrostatic assembly to acquire a 3D superstructure nanocomposite. The advantages of low-dimensional components are fully utilized in the unique 3D heterostructure. The 3D conductive network is formed from 1D N-CNTs, and the synergistic effect of multiple loss mechanisms significantly facilitates its microwave absorption (MA) properties. Specifically, the material shows an optimal reflection loss (RL) of −52.64 dB at 3.12 GHz at a thickness of 3.8 mm, and an effective absorption bandwidth (EAB) from 2.8 to 3.52 GHz, which covers the S-band. Importantly, adjustable and efficient MA between the S and C band can be realized by modulating the loads of the CoNi/N-CNTs. Accordingly, the feasibility of designing a hierarchical 3D superstructure from low-dimensional components to deal with electromagnetic pollution can be audaciously predicted.

Numerical investigations were conducted on the mixing efficiency of resonant acoustic mixing (RAM) technology using a high-viscosity mixture under vertically forced vibrations. The density distribution was analyzed for a mixture of high-melting explosive (HMX) and trinitrotoluene (TNT). The effects of mixing time, amplitude, frequency, fill level, and mixing vessel geometry were evaluated to determine their influence on the blend homogeneity and the efficiency of the mixing process. The results showed that amplitude and frequency both have significant influences on the mixing efficiency of the RAM process. With higher values of amplitude and frequency, the mixing efficiency was very good, and uniform mixing was achieved in a much shorter time. At the same time, it was seen that geometric changes did not affect the mixing process; in contrast, varying the fill level did have a significant effect. This approach could potentially be used for pharmaceutical blending, cosmetics, and explosive applications, where only small quantities of active particle ingredients (APIs) can change the behavior of the mixture.

A novel polymethacrylimide foam-filled square carbon fiber reinforced composite honeycomb core was proposed and prepared. Numerical simulations and theoretical predictions were conducted to study the quasi-static compressive strength of the hybrid core. The effects of material and structural parameters on the compressive strength of the core were analyzed. The results show that the failure modes of the core under quasi-static compression include elastic buckling and plastic fracture failure. The change law of the compressive strength of the core with the increase in the relative density can be divided into three phases, including post-buckling load bearing stage, buckling failure stage, and fracture stage. The failure modes of the core and the change law of the compressive strength with the increase of the relative density vary with the material and structural parameters. The research provides an accurate method to predict the compressive strength of the foam-filled composite honeycomb, which can help to guide the design and optimization of light weight and energy-efficient sandwich cores.

The state-of-the-art progress in photocatalytic ammonia synthesis is reviewed with a focus on the adsorption activation of nitrogen molecules, electron transfer pathways, and intermediate product regulation strategies.

The dynamic response of composite sandwich structures with honeycomb-foam hybrid cores subjected to underwater shock waves was investigated by numerical simulations. The deformation process, core compression, momentum transmitting characteristics, and energy absorbing properties of sandwich structures subjected to underwater shock waves with different initial pressures were analyzed. The dynamic responses of the composite sandwich with different core configurations were also compared. The results show that the composite sandwich structures can provide superior protection from underwater shock waves than mass equal laminate plates and the sandwich structures with hybrid cores have better performance than that with empty honeycomb cores when subjected to underwater shock waves. The research can provide reference for the lightweight design and optimization of protective structures against underwater blast loading.