Large-scale core-sheath heterostructural SiC nanowires were facilely grown on the surface of carbon fibers using a one-step chemical vapor infiltration process. The as-synthesized SiC nanowires consist of single crystalline SiC cores with a diameter of ∼30 nm and polycrystalline SiC sheaths with an average thickness of ∼60 nm. The formation mechanisms of core-sheath heterostructural SiC nanowires (SiC) were discussed in detail. The SiC-CF shows strong electromagnetic (EM) wave absorption performance with a maximum reflection loss value of -45.98 dB at 4.4 GHz. Moreover, being coated with conductive polymer polypyrrole (PPy) by a simple chemical polymerization method, the SiC-CF/PPy nanocomposites exhibited superior EM absorption abilities with maximum RL value of -50.19 dB at 14.2 GHz and the effective bandwidth of 6.2 GHz. The SiC-CF/PPy nanocomposites in this study are very promising as absorber materials with strong electromagnetic wave absorption performance.
This paper presents the first experimental results on the closed-loop characterization of a mode-localized microelectromechanical resonator system. Comparisons between the closed-loop oscillator approach and the open-loop frequency sweep approach show good agreement of output metrics including amplitude ratios and mode frequencies. This new approach enables real-time measurements using emerging mode-localized resonant sensors and represents an important step towards realizing sensors based on this measurement principle.Index Terms-Mode localized resonant sensor, self-sustained oscillator
The rapid development of next‐generation portable electronic devices urgently requires dual‐functional materials that possess both efficient heat dissipation and outstanding electromagnetic interference (EMI) shielding performances. In this study, anisotropically oriented carbon films with high thermal conductivity and excellent EMI shielding properties are prepared through an innovative glucose hydrogel‐controllable carbonization method. The horizontal alignment of nanocrystalline graphite results in oriented structures with an extremely high in‐plane thermal conductivity of 439.9 W m−1 K−1, exhibiting a more effective heat‐dissipating capacity on smartphones than their commercial graphite counterparts. Additionally, owing to multiple internal reflections arising from the oriented structures, the films exhibit an EMI shielding effectiveness (SE) of 21.72 dB at an ultrathin thickness of 480 nm in the X‐band and an extraordinarily high absolute shielding effectiveness (SSE/t) of 275 883 dB cm2 g−1, significantly outperforming most of the reported synthetic materials. Furthermore, the flexibility, high mechanical strength, and stability of the films are demonstrated and therefore show promising application prospects. This study offers a facile yet feasible strategy for preparing dual‐functional materials to address the heat emission and EMI problems of advanced electronic devices in a more economical and environmentally friendly manner.
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