Brittle failure of fractured rock materials under quasi-static loading is characterized by strong suddenness and severe consequences, making accurate prediction of crack evolution and failure load critically important. However, conventional continuum mechanics-based methods encounter singularities when addressing discontinuities, while the widely adopted dynamic relaxation (DR) method within peridynamics is applicable solely to the continuous deformation stage. To address this limitation, this paper proposes a two-stage joint algorithm combining dynamic relaxation and conventional explicit analysis within the peridynamics framework. In this method, the DR method is employed exclusively during the continuous deformation stage before the onset of loading-induced bond failure, while the conventional explicit algorithm is activated to simulate the subsequent crack propagation process. The feasibility and stability of the proposed method are validated through the failure simulation of an L-shaped concrete plate. Subsequently, the quasi-static failure behavior of Brazilian discs with pre-existing central cracks and slope models containing steep-gently dipping pre-existing fissures is systematically investigated. For Brazilian discs, the influences of crack inclination angle and relative crack length on failure modes and bearing capacity are revealed. The numerical results are consistent with experimental observations. For the two specific slope models considered, the geometric configuration characterized by θ = 90°exhibits tensile coalescence failure, whereas that characterized by θ = 56°exhibits tensile–shear coalescence failure; both numerical results agree with the corresponding experimental observations. The findings demonstrate that the proposed joint algorithm combines the computational efficiency of dynamic relaxation during the continuous deformation stage with an explicit approximation of the quasi-static fracture process during damage evolution. This provides a simple yet effective numerical solution for quasi-static failure analysis of fractured rock materials.
Solid oxide fuel cells (SOFCs) are promising for efficient and sustainable energy conversion. However, their widespread utilization is limited by challenges such as sluggish electrode kinetics, thermal mismatch, and long-term degradation. Among SOFC components, cathodes play a pivotal role in governing overall performance and durability, demanding materials with exceptional electrochemical activity, structural stability, and chemical compatibility. Spinel oxides have emerged as attractive alternatives to conventional perovskite-based air electrodes due to their relatively low thermal expansion coefficients, typically in the range of ∼ 11–14 × 10−6 K−1 for many representative compositions, together with good structural stability, superior poisoning resistance, and increasingly competitive ORR activity after rational design. This work reviews recent progress in spinel-based SOFC cathodes, encompassing single-phase materials and composite electrodes. An in-depth analysis of key engineering strategies that have advanced spinel cathode performance, including nanostructure design method enhancing active surface area, cation doping strategy tailoring cation valence and oxygen vacancies, physical mixing/infiltration optimizing composite interfaces, self-assembly creating strong synergistic effect, and high-entropy design stabilizing lattice and defect configurations. The application of spinel-based cathodes in oxygen-ion conducting solid oxide fuel cells (O-SOFCs) and protonic ceramic fuel cells (PCFCs), direct ammonia solid oxide fuel cells (DA-SOFCs), symmetric solid oxide fuel cells (SSOFCs), and reversible solid oxide fuel cells (R-SOFCs) were systematically evaluated. Additionally, current limitations and future research directions are discussed, offering insights for the rational development of spinel-based electrodes in next-generation SOFCs.
In practical engineering applications, uncertainties in beam vibration systems induced by manufacturing tolerances and environmental variations are inevitable. However, conventional vibration response analysis typically assumes that parameters such as material properties and geometry are deterministic. To quantify the effect of multi-parameter uncertainty on the response of beam vibration systems, this study introduces an efficient and high-precision partition of unity finite element method for beam vibration analysis within the framework of the direct probability integral method, thus developing a novel stochastic response analysis scheme for beam vibration systems. The proposed scheme features a strong capability to capture waveform information within each element, a small system matrix size, and the ability to efficiently and accurately reflect the patterns of stochastic responses. Numerical examples show that the statistical characteristics of the beam vibration system response obtained using the proposed scheme agree well with those from the Monte Carlo simulation method, whilst exhibiting good computational accuracy and efficiency. Furthermore, the elastic modulus and the beam height exert a relatively significant effect on the statistical characteristics of the system response, and the effect of material properties is greater than that of geometric properties under multi-parameter coupling.
Ultrasonic impact treatment (UIT) was applied to induce local crystallization on an Fe-based (FeNiCrCoNbSiCB) amorphous coating, forming a composite with an amorphous matrix and Cr-rich butterfly-shaped crystalline grains. ABAQUS simulations and DSC analysis confirmed that the plastic dissipation energy from transient UIT exceeds the crystallization energy barrier, enabling surface crystallization. The UIT8 coating (amplitude: 8 μm) exhibited high hardness (∼14.15 GPa) and elasticity (183.41 GPa). It demonstrated good corrosion resistance in 3.5 wt% NaCl solution and strong wear resistance under linear reciprocating sliding at room temperature—attributed to enhanced plasticity, toughness, and reduced residual tensile stress. In the corrosive medium, the coating achieved excellent wear resistance (wear rate: 5.4 × 10⁻5 mm³/N·m). This performance arises from the coordinated deformation between butterfly crystals and the amorphous phase, as well as the formation of a dense Cr₂O₃ passivation film due to the Cr-rich nature of the butterfly crystals. This strategy of inducing local crystallization via UIT offers a new route for preparing amorphous/crystalline composite coatings with high plasticity and superior corrosive wear resistance.
RNA interference (RNAi) has shown great potential for pest control. However, the practical application of RNAi technology for pest control still faces challenges, such as target gene selection, dsRNA degradation, and low RNAi efficiency. In this study, with Callosobruchus maculatus as a model organism, the gene encoding fatty acid synthase (FASN) was selected as a target for insect control. After full-length sequence of CmFASN gene amplified using RACE technique, the gene structure and expression patterns were analyzed, which showed high conserved sequence structure and the spatiotemporal expression characteristics. Then, the dsFASN-CS-FCN nanoparticles were synthesized using ionic gelation methods with chitosan, fucoidan and dsFASN. The dsFASN-CS-FCN NPs exhibited excellent dispersibility, enhanced in vitro stability, and high RNAi efficiency. Compared to naked dsFASN, the dsFASN-CS-FCN nanoparticles significantly enhanced dsRNA stability in the insect's midgut fluid. Consequently, the dsFASN-CS-FCN nanoparticles could be effectively distributed in midgut. Importantly, dsFASN-CS-FCN exhibited high insecticidal activity against C. maculatus, leading to significantly increased mortality (58.00 ± 4.00% at 24 h post-treatment), reduced fecundity (77.6% reduction compared to the control), enhanced gene suppression efficiency (75.8% FASN knockdown), and decreased TAG synthesis (6.28 ± 0.28 ng/mg).Therefore, FASN could serve as a potential novel target for pest control. Not only did the dsFASN-CS-FCN NPs exhibit high stability and significantly enhance insecticidal efficacy, but they also improved dsRNA delivery efficiency, thereby establishing FASN as a promising target gene for pest control. Accordingly, these results could offer new perspectives for the application of RNAi technology in this field.
