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Although various stakeholder groups frequently advocate and call for greater heterogeneity among directors and managers, it remains unknown whether team heterogeneity can be beneficial for audit committee to exercise the auditor selection functions. This study aims to address this question.

Drawing on a sample of domestically listed nonfinancial A-share firms in China from 2008 to 2022, the authors empirically examine whether and how firm’s audit committee heterogeneity associates with the selection of auditors.

Firms with higher levels of audit committee heterogeneity are more likely to be associated with lower-quality auditors. Further examination reveals the mediating role of risk-taking: higher levels of heterogeneity are associated with higher levels of risk-taking, influencing firms to employ lower-quality auditors. Moreover, the authors document that increased audit committee heterogeneity is associated with more audit committee meetings and lower audit efficiency, and that hiring lower-quality auditors can influence the market value of firms with high audit committee heterogeneity.

To the best of the authors’ knowledge, this study is the first to examine whether and how audit committee erogeneity associates with the selection of auditors. Moreover, because China is a high-power distance, collectivism-oriented, more relations-based (i.e. guanxi-based) than rules-based society, it is critical to examine the influence of team heterogeneity based on the unique cultural context and transitional nature of China’s business environment.

This study aims to fabricate a novel electromagnetic interference (EMI) shielding composite aerogel with both thermal insulation and high temperature warning functions.

An emerging bio-based polypyrrole (PPy) gel/Fe₃O₄/calcium alginate (PFC) EMI shielding composite aerogel was prepared by freeze-drying and in situ polymerization method. First, Fe₃O₄/calcium alginate (CA) aerogel was obtained by freeze-drying the Fe₃O₄/CA mixture. Then, PPy/Fe₃O₄/CA was obtained by synthesizing PPy on the surface of CA/Fe₃O₄ aerogel through in situ polymerization. Finally, PPy/Fe₃O₄/CA was immersed in porphyrin solution (cross-linking agent) to get the final PFC EMI shielding composite aerogel.

Due to the matched impedance between Fe₃O₄ and PPy, the EMI shielding performance of PFC composite aerogel can reach up to −8 dB. In addition, the PFC EMI shielding composite aerogel also shows excellent self-extinguishing and thermal insulation properties. After leaving the flame, the burning PFC aerogel is quickly extinguished. When the PFC aerogel is placed on the heating plate at 230 °C, the temperature on the side of the aerogel away from the heating plate is only 90.3 °C after 5 min of heating. The electrical resistance of the PFC composite aerogel can be reduced from 3.62 × 104 O to 5 × 102 O to trigger the warning light after 3 s of exposure to the alcohol lamp flame. This reversible thermal resistance response characteristic can be used to give an early warning signal when the PFC encounters high temperature or flame.

This work provides a novel strategy for designing a multifunctional EMI shielding composite aerogel with repeatable high temperature warning performance. This PFC composite aerogel shows potential applications in the prevention of material combustion in high temperature electromagnetic environments.