Search

Ceramic matrix composites(CMC) have excellent application potential in the aerospace field as thermal structure material. The introduction of continuous fibers solves the problem of high brittleness of ceramics, and the interphase. A micro area between fiber and matrix, plays an important role in guaranteeing the high toughness of CMC. In the last decades, relevant research mainly has focused on the relationships between the interphase and the macroscopic mechanical properties of CMC. Due to the limitation of characterization technology, it is difficult to study deeply the micro-mechanical behavior in the interface region.With the development of micro-nano mechanical testing and focused ion beam (FIB) technology, the characterization of CMC interfacial layer bonding strength and its failure behavior have gradually increased in recent years. On this basis, the interphase roles, the influencing factors of interfacial shear strength and the regulation mechanism of interphase were reviewed. The current methods of testing interface shear strength by direct or indirect means were summarized. The applicable conditions and differences of fiber push-out/push-in and micro pillar compression methods were summarized empathetically. The progress in failure mechanism of the interfacial zone was revealed, and some remaining problems were pointed out. The fiber push-out/push-in test can reflect the influence of matrix stress on the interfacial shear strength, but the test results might be influenced by external factors.And the micro pillar compression test primarily reflects the intrinsic properties of the interphase, and can't reflect the influence of the matrix stress on the interfacial shear strength, nor can it reflect the fiber pull-out process.Finally, the future research directions are prospected: further expanding the characterization methods of the mechanical behavior of the interface micro-zone, while clarifying the influence mechanism between the micro-mechanical behavior and the macroscopic mechanical properties, and establishing relevant models, ultimately achieving the optimization of the interfacial zone of CMC.

In this work, the threshold photoionization cross sections from the excited states of lutetium and ytterbium atoms were investigated by the laser pump–probe scheme under the condition of saturated resonant excitation. We obtained the resonance enhanced multiphoton ionization spectra of the lutetium and ytterbium atoms of the lanthanide metals in the range of 307.50–312.50 nm and 265.00–269.00 nm, respectively; the photoionization cross sections of the 5d6s(1D)6p(2D05/2) and 5d6s(3D)6p(2P01/2) states of lutetium and the 4f13(2F0)5d6s2(J = 1) states of ytterbium above threshold regions (0.4–1.6 eV) were measured, and measured values ranged from 2.3 ± 0.2 to 17.7 ± 1.5 Mb. [ABSTRACT FROM AUTHOR]

Flexible perovskite solar cells (FPSCs) have gained considerable attention for potential applications in portable and wearable electronics. However, the design principles governing FPSCs remain incompletely understood. In this study, two critical factors—thermal conductivity and elastic modulus—that significantly influence the thermal and mechanical stabilities of FPSCs are identified. Achieving stress‐less conditions is crucial for enhancing the performance of FPSCs. To address this, a liquid crystal elastomer (LCE) is employed as a buffer interlayer to effectively mitigate residual thermal stress. This is achieved by improving the thermal conductivity of the electron transport layer from 0.76 to 1.07 W mK−1 and softening the perovskite layer, reducing the Young's modulus from 50 to 42 GPa. The optimized thin films are utilized in both rigid and flexible PSCs, resulting in efficiencies of 24.5% and 22.8%, respectively. Remarkably, these devices demonstrated excellent thermal stability, with unpackaged LCE rigid PSCs retaining 85.6% of their initial efficiency after 504 h of aging at 85 °C. Moreover, robust mechanical stability in FPSCs is exhibited, with 88.4% of the original efficiency retained after 5400 bending cycles. This investigation elucidates the profound impact of thermal conductivity and Young's modulus on the efficiency and stability of flexible electronics. [ABSTRACT FROM AUTHOR]

The present paper is concerned with the Rayleigh wave propagation in the machined surface with a thin damaged layer with residual stress. We assume that the layer and the half-space are bonded perfectly to each other. Biot's theory of small deformations influenced by initial stress forms the basis for this study. With the help of the effective boundary condition method, a third-order approximate secular equation of Rayleigh waves is established for the case that the layer and half-space are both orthotropic. In addition, an explicit third-order approximate formula for the Rayleigh wave velocity is derived from the secular equation. By considering a sample of silicon wafer by fine grinding with fine abrasive grains, the accuracy of the approximate formula has been verified. This study is meant to serve as the mathematical foundation for non-destructive testing of residual stress in the practical applications. [ABSTRACT FROM AUTHOR]

The presence of free gossypol (FG) in cottonseed meal (CSM) greatly limits the use of CSM as a high-quality protein feed. Microbial fermentation is an effective method to simultaneously reduce FG and improve the nutritional value of CSM. In this study, using potato dextrose agar containing acetic gossypol as a selective medium and humus soil from cotton fields as the source, we isolated six strains of fungi capable of tolerating FG. With an inoculation ratio of 8% (8 mL × 106 CFU/mL cells or spores in 100 g fermented CSM), 50% moisture content, and a temperature of 30 °C, CSM was fermented for 5 days. The results showed that strain F had the highest FG removal rate at 56.43%, which was identified as Rhodotorula mucilaginosa (R. mucilaginosa) and named R. mucilaginosa TG529. Further optimization revealed that when the fermentation time was extended to 11 days, TG529 achieved a maximum FG removal rate of 73.29%. Compared to the original sample, treatment with TG529 significantly increased the contents of crude protein, acid-soluble protein, and 18 amino acids, while significantly reducing the contents of crude fiber, neutral detergent fiber (NDF), and acid detergent fiber in fermented cottonseed meal (FCSM). Using atmospheric and room temperature plasma for mutagenesis of TG529, it was found that the mutated TG529 significantly increased the contents of acid-soluble protein and phenylalanine in FCSM, significantly reduced the NDF content, and enhanced the FG removal rate to 76.50%. In summary, this study screened and mutagenized a strain of FG detoxifying fungus, R. mucilagnosa TG529, which can effectively reduce the FG content and improve the nutritional value of CSM by solid-state fermentation. [ABSTRACT FROM AUTHOR]

Data‐driven materials and chemical studies have been predominantly confined to English‐language databases, posing challenges for researchers in non‐English‐speaking regions to access and comprehend literature and derive scientific insights. Herein, a machine learning approach designed for information extraction and knowledge acquisition in the materials and chemical science realm from non‐English literature databases, requiring minimal human intervention, is presented. The efficacy of language model through a case study centered on the prediction of solar cell materials using Chinese‐language sources is studied. The unsupervised learning model effectively extracts crucial latent chemical and materials data from non‐English literature resources. Subsequently, the language model successfully identifies existing solar cell materials and forecasts potential candidates from this non‐English corpus. To further validate the suitability of the proposed solar cell material candidates, we conduct ab initio density functional theory calculations to evaluate their structural and optoelectronic properties. The results validate both the efficacy of our language model and the predictability of our approach. This study represents a stride toward comprehensive data‐driven machine learning for materials and chemical predictions, transcending the limitations of English literature. Furthermore, it offers a solution to aid researchers in non‐English‐speaking regions in overcoming language barriers and accessing scientific discoveries. [ABSTRACT FROM AUTHOR]

This experiment was conducted to investigate the effects of a high‐fibre diet on growth performance, nutrients digestibility, intestinal health, and intestinal microbiota composition of growing pigs. Twelve healthy "Duroc × Landrace × Yorkshire" castrates (49 ± 1.35 kg) were randomly divided into two groups with six replicates and one pig per replicate. The two diet treatments were fed the basal diet (CON) based on corn and soybean meal and high fibre diet (HF) respectively. The nutritional levels of the two treatments were the same. The experiment lasted 28 days. The results showed that the addition of 16% wheat bran fibre to the diet of growing pigs did not affect growth performance (p > 0.05). Compared with the CON, contents of isobutyric and butyric acid, GSH‐PX and T‐AOC in serum were increased in the HF. It decreased the gross energy digestibility and acetic acid content in feces of growing pigs (p < 0.05), the contents of GSH‐PX and T‐AOC in serum. It decreased the gross energy digestibility and acetic acid content in feces of growing pigs (p < 0.05). Compared with the CON, the Shannon, and Chao1 indexes of the HF were increased (p < 0.05). At the phylum level, the abundance of g_Lactobacillus increased in the HF (p < 0.05). Correlation analysis showed that a total of 18 microbial genera were correlated with antioxidant capacity and volatile fatty acid levels (p < 0.05). In summary, this study showed that adding 16% wheat bran to the diet of growing pigs had no effect on growth performance but helped to improve the richness and stability of intestinal microbiota, promote posterior intestinal fermentation and increase serum antioxidant capacity. [ABSTRACT FROM AUTHOR]

In order to meet the need of high thrust ratio aero engine working in long term thermal oxidation environment and the stealth requirement of key thermal structural components of aero engine, silicon carbide ceramic matrix composites are developed towards crack self-healing and structure-wave absorbing integration. In this paper, the design principles of silicon carbide ceramic matrix composites in strengthening and toughening, crack self-healing and electromagnetic wave absorption are introduced. The research progress in these three aspects is reviewed. The future development trend of structural and functional CMC-SiC is the combination of high strength and toughness, self-healing antioxidation and electromagnetic wave absorption.