Coal and rock dynamic disasters have been the main concern in underground engineering because these seriously threaten the safety of miners and industrial production. Aiming to improve the EMR and AE monitoring technology, the refined nonlinear characteristics of EMR and AE during coal splitting failure are studied using Hilbert-H and multifractal theory, and valuable information pertaining to coal fracture law contained in EMR and AE waveform was revealed. The results show that the EMR and AE of coal splitting failure are related to the process of coal crack propagation. They possess the same initiation time and frequency band, however, the signal duration of EMR is comparatively longer than AE, and the main frequency of AE is higher than EMR. The EMR of coal splitting failure has the same excitation source as AE; nonetheless, the excited forms display different behavior. In terms of signal duration, the distribution of EMR signal is relatively uniform, the proportion of large-signal is less, the amount of information is more than that of AE, and the multifractal characteristics are more complicated. During the coal splitting failure, AE is mainly generated in the process of wall vibration caused by crack propagation, while the generation of EMR includes piezoelectric effect, charge separation, free charge vibration, charge neutralization and other processes, making EMR more complicated than AE and has a relatively low frequency. The research provides an effective method for studying nonlinear refinement characteristics of coal EMR and AE, and can provide an important basis for the study of the mechanism of EMR generation.

Redox-stimuli responsive amphiphilic copolymers have recently emerged as promising drug carrier systems with controllable drug release. Herein, we first reported the synthesis of two well-defined redox-stimuli responsive ferrocene-containing polymers, amphiphilic diblock copolymer PN(Fc-b-TEG) and random copolymer PN(Fc-r-TEG), via ring-opening metathesis polymerization (ROMP), and compared their properties as drug carriers. Results showed that both of the obtained copolymers could self-assemble into globular nanoscale core–shell micelles in aqueous solution and showed tunable redox responses. The copolymer micelles were used to entrap the hydrophobic dye Nile red (NR) or anticancer drug doxorubicin (DOX). The DOX encapsulation efficiency of PN(Fc-b-TEG) is 66.7% which is higher than that of PN(Fc-r-TEG) (21.1%) under the same conditions. Meanwhile, the DOX-loaded micelles exhibited oxidation-controlled drug release, and the release rate could be mediated by the concentration of oxidants. Cell counting kit (CCK) assay and model organism zebrafish embryo studies were further performed to disclose the biocompatibility and safety of the copolymer micelles, and the results showed that the copolymers had excellent biocompatibility. The neoteric ferrocene-containing copolymer carriers with reversible redox-response are anticipated to have potential in targeted drug delivery systems for cancer therapy.