Guo Rui,Li Shutong,Duan RongXia,Sun Yunjun,Li Jianhui,Wu Yanzhao,Wang Lianjun,Jiang Wan
Overcoming the challenge of decoupling impedance matching from attenuation for low-frequency (2–10 GHz) electromagnetic wave absorption, this work presents a defect-engineered multiphase medium-entropy sulfide composite. Synthesized via integrated mechanical alloying and surfactant-assisted hydrothermal sulfidation, the composite integrates sulfur vacancy-rich (Fe,Co,Ni) 9 S 8 , anisotropic FeCoNi alloy, CoFe₂O₄, and porous MoS 2 . This architecture creates abundant heterogeneous interfaces and interfacial sulfur vacancies, significantly enhancing defect-induced polarization and dielectric loss via the “Janus effect.” Concurrently, the magnetic components boost magnetic loss while optimizing impedance matching. Benefiting from this magneto-dielectric synergy, the composite achieves exceptional absorption: a minimum reflection loss ( RL min ) of -50.4 dB at 3.96 GHz and a remarkable RL min -77.5 dB at 9 GHz. Radar cross-section simulations confirm application potential. This work provides strategic insights for designing innovative low-/mid-frequency absorbers through synergistic dielectric-magnetic loss in polymetallic sulfide heterostructures.
Li Zhou,Fenglu Han,Kunyu Lu,Yanbing Qiao,Erchao Li
Prebiotic fermentation by gut microbiota is a key foundation for prebiotics exhibiting physiological functions. However, the relationship among prebiotic type, gut microbiota and gut microbiota metabolism remains unclear. In this study, the gut microbiota of shrimp ( Litopenaeus vannamei ) was inoculated into medium containing 1% fructooligosaccharide (FOS), galactooligosaccharide (GOS), mannanoligosaccharide (MOS), inulin, β-glucan, isomaltooligosaccharide (IMO) and xylooligosaccharide (XOS). The pH value, digestive enzyme activity, short-chain fatty acid yield and gut microbiota in the fermentation liquid were evaluated. The results showed that after 12 h of in vitro fermentation, β-glucan exhibited the lowest pH value and highest amylase activity among the other types of prebiotics. β-glucan had a higher ability to produce short-chain fatty acids (SCFA) and inhibit the formation of branched-chain fatty acids (BCFA) than the other types of prebiotics. At the genus level, β-glucan markedly promoted the growth of Bacillus . These findings suggest that β-glucan was the most suitable type of prebiotic and had greater prebiotic effects than the other types of prebiotics on the basis of in vitro fermentation by the gut microbiota of shrimp ( Litopenaeus vannamei ).
危险品化学品经营许可证（带存储）