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This study presents a novel star-shaped honeycomb meta-material (N-SSHM) that realizes improved static mechanical and vibration properties by introducing rings to the four sides of a traditional star-shaped honeycomb meta-material (T-SSHM). Optimization of the static and vibration suppression properties is achieved using the assembly concept. The static properties of the proposed meta-materials are initially investigated using the finite element method (FEM) and static compression tests. The results demonstrate that the N-SSHM exhibits a superior load-bearing capacity compared to the T-SSHM. Subsequently, the vibration properties of the meta-material are studied using simulations and experiments. The wave propagation characteristics of the meta-materials are explored by introducing the phase velocity and group velocity. The study also examines the effects of design parameters (ring size, metal pin size, and pin material) on the bandgap characteristics, and the vibration suppression properties of the meta-material are further enhanced by introducing particle damping. The simulation and experimental results confirm that the proposed N-SSHM has a lower starting frequency and wider bandwidth for the bandgap than the T-SSHM. In summary, the N-SSHM demonstrates significant improvements in both load-bearing and vibration suppression compared to the T-SSHM. This study provides support for the engineering applications of meta-materials.

A novel re-entrant honeycomb metamaterial based on 3D-printing technology is proposed by introducing chiral structures into diamond honeycomb metamaterial (DHM), named chiral-diamond-combined honeycomb metamaterial (CDCHM), and has been further optimized using the assembly idea. Compared with the traditional DHM, the CDCHM has better performance in static and vibration isolation. The static and vibration properties of the DHM and CDCHM are investigated by experiments and simulations. The results show that the CDCHM has a higher load-carrying capacity than that of the DHM. In addition, the vibration isolation optimal design schemes of the DHM and CDCHM are examined by experiments and simulations. It is found that the vibration suppression of the CDCHM is also improved greatly. In particular, the optimization approach with metal pins and particle damping achieves a wider bandgap in the low-frequency region, which can strengthen the suppression of low-frequency vibrations. And the introduction of particle damping can not only design the frequency of the bandgap via the alteration of the dosage, but also enhance the damping of the main structure. This work presents a new design idea for metamaterials, which provides a reference for the collaborative design of the static and vibration properties of composite metamaterials.

Based on the concept of component assembly, a novel star polygon-coupled honeycomb metamaterial, which achieves a collaborative improvement in load-bearing capacity and vibration suppression performance, is proposed based on a common polygonal structure. The compression simulation and experiment results show that the load-bearing capacity of the proposed metamaterial is three times more than that of the initial metamaterial. Additionally, metal pins are attached and particle damping is applied to the metamaterial to regulate its bandgap properties; the influence of configuration parameters, including the size, number, position, and material of the metal pins, on bandgaps is also investigated. The results show that the bandgap of the proposed metamaterial can be conveniently and effectively regulated by adjusting the parameters and can effectively suppress vibrations in the corresponding frequency band. Particle damping can be used to continuously adjust the frequency of the bandgap and further enhance the vibration suppression capacity of the metamaterial in other frequency bands. This paper provides a reference for the design and optimization of metamaterials.

An improved re-entrant negative Poisson’s ratio metamaterial based on a combination of 3D printing and machining is proposed. The improved metamaterial exhibits a superior load-carrying and vibration isolation capacity compared to its traditional counterpart. The bandgap of the proposed metamaterial can be easily tailored through various assemblies. Additionally, particle damping is introduced to enhance the diversity of bandgap design, improve structural damping performance, and achieve better vibration isolation at low and medium frequencies. An experiment and simulation were conducted to assess the static and vibration performances of the metamaterial, and consistent results were obtained. The results indicate a 300% increase in the bearing capacity of the novel structure compared to traditional structural metamaterials. Furthermore, by increasing the density of metal assemblies, a vibration-suppressing bandgap with a lower frequency and wider bandwidth can be achieved. The introduction of particle damping significantly enhanced the vibration suppression capability of the metamaterial in the middle- and low-frequency range, effectively suppressing resonance peaks. This paper establishes a vibration design method for re-entrant metamaterials, which is experimentally validated and provides a foundation for the vibration suppression design of metamaterials.

Damage localization methods for composite materials are a popular research topic at present. The time-difference-blind localization method and beamforming localization method are often individually utilized in the localization of the acoustic emission sources of composite materials. Based on the performances of the two methods, a joint localization method for the acoustic emission sources of composite materials is proposed in this paper. Firstly, the performance of the time-difference-blind localization method and the beamforming localization method were analyzed. Then, with the advantages and disadvantages of these two methods in mind, a joint localization method was proposed. Finally, the performance of the joint localization method was verified using simulations and experiments. The results show that the joint localization method can reduce the localization time by half compared with the beamforming localization method. At the same time, compared with the time-difference-blind localization method, the localization accuracy can be improved.

Florfenicol (FLO), which is widely used in veterinary clinics and aquaculture, can disrupt the protein synthesis of bacteria and mitochondria and, thus, lead to antibacterial and toxic effects in plants, insects, and mammals. FLO was found to repress chicken embryonic development and induce early embryonic death previously, but the underlying mechanism is not fully understood. Clarifying the mechanism of FLO-induced embryonic toxicity is important to the research and development of new drugs and the rational use of FLO to ensure human and animal health and ecological safety. In this study, the effects of FLO on pluripotency, proliferation, and differentiation were investigated in P19 stem cells (P19SCs). We also identified differentially expressed genes and performed bioinformatics analysis to obtain hub genes and conducted some functional analysis. FLO inhibited the proliferation and pluripotency of P19SCs and repressed the formation of embryoid bodies derived from P19SCs. A total of 2,396 DEGs were identified using RNA-Seq in FLO-treated P19SCs, and these genes were significantly enriched in biological processes, such as angiogenesis, embryonic organ development, and morphogenesis of organs. Kyoto encyclopedia of genes and genome-based pathway analysis also showed that five relevant pathways, especially the canonical Wnt pathway, were engaged in FLO-induced toxicity of pluripotent stem cells. We further analyzed modules and hub genes and found the involvement of ubiquitin-mediated proteolysis, DNA replication, and cell cycle machinery in regulating the pluripotency and proliferation of FLO-treated P19SCs. In summary, our data suggest that FLO disrupts the signaling transduction of pathways, especially the canonical Wnt pathway, and further inhibits the expression of target genes involved in regulating DNA replication, cell cycle, and pluripotency. This phenomenon leads to the inhibition of proliferation and differentiation in FLO-treated P19SCs. However, further experiments are required to validate our findings and elucidate the potential mechanisms underlying FLO-induced embryonic toxicity.

To explore the lightweight structures with excellent vibration and acoustic properties, corrugated composite panels with different fiber reinforcements, i.e., carbon and glass fibers, were designed and fabricated using a modified vacuum-assisted resin infusion (VARI) process. The vibration and sound transmission loss (STL) of the corrugated composite panels were investigated via mode and sound insulation tests, respectively. Meanwhile, finite element models were proposed for the verification and in-depth parametric studies. For the vibration properties of the corrugated composite panels, the results indicated that the resin layer on the panel surface, despite the extremely low thickness, showed a significant effect on the low-order bend modes of the entire structure. In addition, the difference in the mode frequency between the panels consisting of different fiber types became more and more apparent with the increase of the frequency levels. For the sound insulation property of the panel, the initial frequency of the panel’s resonant sound transmission can be conveniently increased by increasing the layer thickness of surface resin, and the fraction of fiber reinforcements is the most predominant factor for the sound insulation property, which was significantly improved by increasing the thickness of the fiber cloth. This work can provide fundamental support for the comprehensive design of vibration and acoustics of the composite sandwiched panel.

Metamaterials/Phononic crystals are used to control the propagation of elastic waves/sound waves, and can be used in fields such as vibration isolation, noise reduction, stealth, focusing, and acoustic wave devices. The realization of real-time, flexible and active adjustable control of elastic waves by mechanical reconstruction of metamaterials is a current research hotspot. Here, SMP metamaterials with mechanical reconstruction and self-recovery ability are proposed. Affected by the glass transition temperature of the material, the mechanical properties of the metamaterials are related to the geometric parameters of the lattice configuration and the external temperature. The metamaterials can adaptively switch mechanical properties and shapes without continuous external excitation of the physical field. The finite element method and experiments were used to analyze the deformation and self-recovery process of the metamaterials. The results show that the metamaterial can achieve mechanical programming and response recovery, and the bandgap of the metamaterial can be greatly adjusted by changing the external temperature.

The unusual properties of mechanical metamaterials are determined by the configuration of artificial periodic structures. However, the mechanical performance of conventional metamaterials is irreversible and cannot perceive and respond to the changes in the environment. In present study, a zero Poisson's ratio metamaterial with intelligent switching mechanical properties and vibration isolation effect is proposed. Based on a 4D printing method of shape memory polymer, this metamaterial is created that can sense temperature changes and switch mechanical properties. The macroscopic deformation and the morphology change of the metamaterial during compression tests are analyzed using experimental and finite element methods. The irregular buckling distortion of the metamaterial is eliminated by cylindrical design, and controllable and adjustable local deformation and stress-strain curve are achieved based on microstructure gradient design. Subsequently, this work focused on the vibration isolation performance of metamaterials, and found fascinating shock absorption performance. Compared with traditional linear spring, this metamaterial spring can effectively reduce the vibration amplitude of certain frequency bands before reaching the resonance peak, which provides a new realization method for low-frequency vibration isolation design.

In this paper, a dynamic model of the coefficient of friction (COF) is established from energy perspective and the principal friction mechanism of disc brake is investigated. The effects of temperature, normal pressure, and relative velocity between brake disc and pad on the COF are tested on a friction testing machine. The results show that the thermal effect is the main factor affecting the friction and wear process, and the thermal deformation and uneven heat distribution play key roles in the change of the COF. The proposed dynamic model can well describe the properties of the COF in friction process, and the work in this paper may provide some new insights into the brake friction mechanism and be helpful for the design of the brakes.

Selective coupling of thiols to produce disulfides is one very important and classic type of coupling reactions. Herein, an environmentally friendly and practical photocatalytic system for oxidative coupling of thiols to disulfides is developed. With no sacrificial agent, no additional additive, just sole water as solvent, performed in air at room temperature, excellent conversions of thiols and excellent selectivities of disulfides are obtained using a cheap and simple semiconductor material of bismuth sulfide (Bi2S3) under blue LED illumination. Excellent conversions and selectivities for coupling of thiols to produce disulfides are obtained, and the system is reusable. The as‐prepared photocatalyst is adequately characterized and the mechanism of photocatalytic reaction is discussed deeply.

The failure of strata with different strength under coal pillar in close distance coal seams has its particularity. Theoretical analysis, numerical simulation, and similar test were used to obtain the failure mechanism of the soft and hard stratification of floor strata under the boundary of wide coal pillar and make out the influence of the strata failure on roadway layout. It shows that the failure of the soft and hard stratification is not synchronous and with different failure forms. The deformation and plastic failure of the soft strata occurs at first; then the fracture of the main bearing hard stratum occurs. Based on the main bearing stratum unbalanced forces acted by upper and lower strata, the initial fracture position and broken blocks span were calculated by bending fracture mechanics model of ultimate span beam. The coal pillar side of the roadway under coal pillar forms “column-beam-column” superimposed structure. The roadway layout under coal pillar and under coal pillar boundary with close distance has large influence on the plastic extension of the “column-beam-column” superimposed structure and the broken of main bearing stratum. The influence of roadway arrangement in floor strata outside coal pillar is smaller than those under coal pillar. It is difficult to control the deformation of roadway surrounding rock if the roadway locates beneath the broken blocks of the main bearing stratum.