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Continuous SiC fibers reinforced SiC ceramic matrix composites have wide applications in the aerospace and nuclear fields owing to their excellent high-temperature resistance, good oxidation resistance and mechanical properties. The precursor-derived method has been the most important method for preparing continuous SiC fibers. The introduction of specific hetero elements could effectively improve properties of SiC fibers. Based on the research work on precursor-derived SiC fibers of high performance carried out by our group in the past forty years, this review firstly summarizes the addition methods of hetero elements, mainly including physical blending or chemical modification methods; The role and mechanism of hetero elements have been elucidated from several aspects: increasing the ceramic yield of the precursor, facilitating densification during sintering of the precursor-derived SiC fibers, improving high-temperature resistance of the final SiC fibers, and generating functions of SiC fibers; The composition, microstructure, properties, and developmental status of SiC fibers containing hetero elements, such as Ti, Al, Zr, Fe, B, as well as refractory metals (Hf, Ta, Nb), have been introduced. Furthermore, future research in the development of precursor systems, quantitative study of the relationship between the types and contents of hetero elements and properties of derived fibers, as well as engineering applications of the precursor-derived SiC fibers, has been prospected.

The strong potential of platinum single atom (PtSA) in gas sensor technology is primarily attributed to its high atomic economy. Nevertheless, it is imperative to conduct further exploration to understand the impact of PtSA on the active sites. In this study, the evolution of PtSA on (100)CeO2 and (111)CeO2 is examined, revealing notable disparities in the position and activity of surface PtSA on different crystal planes. The PtSA in (100)CeO2 surface can enhance the stability of Ce3+ and construct a frustrated Lewis pair (FLP) to form a double active site by combining the steric hindrance effect of oxygen vacancies, which increases the response value from 1.8 to 27 and reduce the response‐recovery time from 140–192 s to 25–26 s toward five ppm NO2 at room temperature. Conversely, PtSA tends to bind to terminal oxygen on the surface of (111)CeO2 and become an independent reaction site. The response value of PtSA‐(111)CeO2 surface only increased from 1.6 to 3.8. This research underscores the correlation between single atoms and crystal plane effects, laying the groundwork for designing and synthesizing ultra‐stable and efficient gas sensors. [ABSTRACT FROM AUTHOR]

The diffusion of credit cards may have relaxed households' liquidity constraints, thereby stimulating the diffusion of commercial insurance. By investigating Chinese urban households who had no commercial insurance in 2013, we find that their initial access to credit cards significantly increased the likelihood of their holding commercial insurance in 2015. Our instrumental variable (IV) estimations confirm the causality. This positive effect is more pronounced among more liquidity‐constrained households and among households with more financial knowledge. Last, the initial access to credit cards also significantly enhanced commercial insurance renewal in 2015 among those households who had commercial insurance in 2013. [ABSTRACT FROM AUTHOR]

The tripartite combination of a high density and stability of surface reaction sites, complemented by the longevity and efficient transfer of interface carriers, along with the effective adsorption and activation of target gas molecules, jointly determines the efficiency of chemiresistors. In this work, the strong metal–support interaction (SMSI) of Pt─Ce3+ is formed by the NaBH4 reduction method and thus prepares metal‐dynamically stable PtNR─CeO2 with Pt─Ce3+ and Pt─Pt reaction sites. The formation of SMSI induces the recombination of the chemical structure of the CeO2 surface causing the localization of electron‐rich Ce3+, which greatly increases the charge concentration at the interface. The experimental findings of the strong interaction of Pt─Ce3+ bonding and the catalytic effect of Pt optimized the adsorption mode of PtNR─CeO2 on target gas, which maintains stable catalytic activity at 20–500 °C and achieving a notable detection response value of 1.43 for 20 ppb NO2. This work offers fresh insights into designing stable oxide chemiresistors with efficiency and stability by customizing reaction sites at the atomic level. [ABSTRACT FROM AUTHOR]

The strong potential of platinum single atom (Pt SA ) in gas sensor technology is primarily attributed to its high atomic economy. Nevertheless, it is imperative to conduct further exploration to understand the impact of Pt SA  on the active sites. In this study, the evolution of Pt SA  on (100)CeO 2  and (111)CeO 2 is examined, revealing notable disparities in the position and activity of surface Pt SA  on different crystal planes. The Pt SA  in (100)CeO 2  surface can enhance the stability of Ce 3+  and construct a frustrated Lewis pair (FLP) to form a double active site by combining the steric hindrance effect of oxygen vacancies, which increases the response value from 1.8 to 27 and reduce the response-recovery time from 140-192 s to 25-26 s toward five ppm NO 2  at room temperature. Conversely, Pt SA  tends to bind to terminal oxygen on the surface of (111)CeO 2  and become an independent reaction site. The response value of Pt SA -(111)CeO 2  surface only increased from 1.6 to 3.8. This research underscores the correlation between single atoms and crystal plane effects, laying the groundwork for designing and synthesizing ultra-stable and efficient gas sensors., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Prolonging energetic hot electrons lifetimes and surface activity in the reactive site can overcome the slow kinetics and unfavorable thermodynamics of photo-activated gas sensors. However, bulk and surface recombination limit the simultaneous optimization of both kinetics and thermodynamics. Here tandem electric fields are deployed at (111)/(100)Au-CeO 2 to ensure a sufficient driving force for carrier transfer and elucidate the mechanism of the relationship between charge transport and gas-sensing performance. The asymmetric structure of the (111)/(100)CeO 2 facet junction provides interior electric fields, which facilitates electron transfer from the (100)face to the (111)face. This separation of reduction and oxidation reaction sites across different crystal faces helps inhibit surface recombination. The increased electron concentration at the (111)face intensifies the interface electric field, which promotes electron transfer to the Au site. The local electric field generated by the surface plasmon resonance effect promotes the generation of high-energy energy hot-electrons, which maintains charge concentration in the interface field by injecting into (111)/(100)CeO 2 , thereby provide thermodynamic contributions and inhibit bulk recombination. The tandem electric fields enable the (111)/(100)Au-CeO 2 to rapidly detect 5 ppm of NO 2 at room temperature with stability maintained within 20 s., (© 2024 Wiley‐VCH GmbH.)

Objective: To investigate the protective effect of quercetin (QR) on acute liver injury induced by diquat (DQ) poisoning in mice and its mechanism., Methods: Eighty healthy male C57BL/6 mice with SPF grade were randomly divided into control group, DQ model group, QR treatment group, and QR control group, with 20 mice in each group. The DQ poisoning model was established by a one-time intraperitoneal injection of DQ solution (40 mg/kg); the control and QR control groups received equivalent amounts of distilled water through intraperitoneal injection. Four hours after modeling, the QR treatment group and the QR control group received 0.5 mL QR solution (50 mg/kg) through gavage. Meanwhile, an equivalent amount of distilled water was given orally to the control group and the DQ model group. The treatments above were administered once daily for seven consecutive days. Afterwards, the mice were anesthetized, blood and liver tissues were collected for following tests: changes in the structure of mice liver tissue were observed using transmission electron microscopy; the levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were detected using enzyme linked immunosorbent assay (ELISA); the levels of glutathione (GSH), superoxide dismutase (SOD), and malondialdehyde (MDA) in liver tissues were measured using the water-soluble tetrazolium-1 (WST-1) method, the thiobarbituric acid (TBA) method, and enzymatic methods, respectively; the protein expressions of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), Kelch-like ECH-associated protein 1 (Keap1), and activated caspase-9 in liver tissues were detected using Western blotting., Results: Severe mitochondrial damage was observed in the liver tissues of mice in the DQ model group using transmission electron microscopy, yet mitochondrial damage in the QR treatment group showed significant alleviation. Compared to the control group, the DQ model group had significantly increased levels of MDA in liver tissue, serum AST, and ALT, yet had significantly decreased levels of GSH and SOD in liver tissue. In comparison to the DQ model group, the QR treatment group exhibited significant reductions in serum levels of ALT and AST, as well as MDA levels in liver tissue [ALT (U/L): 52.60±6.44 vs. 95.70±8.00, AST (U/L): 170.45±19.33 vs. 251.10±13.09, MDA (nmol/mg): 12.63±3.41 vs. 18.04±3.72], and notable increases in GSH and SOD levels in liver tissue [GSH (μmol/mg): 39.49±6.33 vs. 20.26±3.96, SOD (U/mg): 121.40±11.75 vs. 81.67±10.01], all the differences were statistically significant (all P < 0.01). Western blotting results indicated that the protein expressions of Nrf2 and HO-1 in liver tissues of the DQ model group were significantly decreased compared to the control group. On the other hand, the protein expressions of Keap1 and activated caspase-9 were conspicuously higher when compared to the control group. In comparison to the DQ model group, the QR treatment group showed a significant increase in the protein expressions of Nrf2 and HO-1 in liver tissues (Nrf2/β-actin: 1.17±0.08 vs. 0.92±0.45, HO-1/β-actin: 1.53±0.17 vs. 0.84±0.09). By contrast, there was a notable decrease in the protein expressions of Keap1 and activated caspase-9 (Keap1/β-actin: 0.48±0.06 vs. 1.22±0.09, activated caspase-9/β-actin: 1.17±0.12 vs. 1.59±0.30), the differences were statistically significant (all P < 0.01)., Conclusions: QR may reduce acute liver injury induced by DQ poisoning in mice via activating Keap1/Nrf2 signaling pathway.