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Underground coal fires (UCFs) exist in almost all coal mining countries. In this paper, an optimised Thermal-Hydraulic-Chemical model, which includes variable reaction kinetics of coal and permeability variation in UCF zones, was developed for the simulation of dynamic temperature evolution of an actual UCF in Xinjiang, China. The model was also adopted in the analysis of the effect of surface coverage permeability on the temperature field, providing a theoretical reference for UCFs control. The results demonstrate that the temperature evolution included three distinct stages which were slow-heating stage, rapid-heating stage and stable-development stage. The slow-heating stage was occupied by the low-temperature oxidation of residual coal. During the rapid-heating stage, a hotspot (combustion centre) formed in residual coal zone and moved toward the air inlet side when the temperature reached a certain threshold. And before moving back into the deeper coal seam, the hotspot developed the temperature to the maximum when it got to the air inlet side. In the stable-development stage, the hotspot spread along the coal seam with the maximum temperature staying between about 800°C and 1000°C, creating elliptical temperature anomalies around the combustion centre. The simulation proved to be in good agreement with the in situ measurements. Surface covering will extinguish the UCF when the permeability of the coverage layer is lower than 10-10 m2, otherwise the fire will persist and continue to spread. [ABSTRACT FROM AUTHOR]

Flexible bending sensors are crucial components of flexible/wearable electronics. However, their broad application is restricted by their difficulty in sensing different bending directions and, more importantly, their significant output attenuation after long cycles. Herein, a new design of an All‐in‐One piezoelectric bending sensor is proposed, in which double‐deck, cross‐over 3D interdigital microelectrodes (silver nanowires (Ag NWs)) are embedded in a piezoelectric polymer film (poly(vinylidene fluoride‐trifluoroethylene (P(VDF‐TrFE))). The piezoelectric film with the embedded 3D microelectrodes exhibits a high anisotropy coefficient (η90∘${{\eta }_{90^\circ }}$ > 1) based on dual piezoelectric modes (d31 and d33), which renders it more sensitive to different bending directions. More importantly, the homogeneous interconnected interface and heterogeneous microinterlocked interface formed inside the sensor significantly enhance its interface mechanical properties, with at least a tensile strength of 51 MPa, a shear strength of 28 MPa, and an interfacial toughness of 300 J m−2, which are nearly two orders of magnitude greater than those of conventional sandwich architectures. The prepared All‐in‐One sensor shows an extremely stable piezoelectric output over as many as 16 00 000 bending cycles, which represents a remarkable breakthrough. Furthermore, a single sensor can be used to remotely control the multidirectional motion of a smart car, demonstrating enormous potential in practical applications. [ABSTRACT FROM AUTHOR]

Background: The survival rate of osteosarcoma therapy still lags behind overall cancer therapies due to the intrinsic or acquired drug resistance. Developing novel drug delivery systems that may overcome drug resistance would greatly facilitate osteosarcoma therapy., Methods: Poly(ethylene glycol) (PEG)-sheddable reduction-sensitive polyurethane (SS-PU-SS-PEG) was synthesized using a disulfide-containing polycaprolactone diol as the hydrophobic block and a cystamine-functionalized PEG as the hydrophilic block. SS-PU-SS-PEG micelles were then prepared to load the anti-tumor drug Doxorubicin (DOX) in order to achieve triggered intracellular drug delivery to improve the efficacy of osteosarcoma therapy., Results: When DOX was used as a model drug, the drug-loaded SS-PU-SS-PEG micelles were about 82∼94 nm in diameter and exhibited good stability in phosphate buffer saline (PBS). The micelles could release about 80% DOX in a quantitative fashion within 5 hours under a reductive environment. The intracellular drug release of DOX-loaded SS-PU-SS-PEG micelles increased upon incubation with Saos-2 cells in vitro. The micelles had good biocompatibility. In vitro, DOX-loaded SS-PU-SS-PEG micelles showed significant antitumor activity toward Saos-2 cells, which was close to that of free DOX. In vivo, DOX-loaded SS-PU-SS-PEG micelles exhibited better antitumor activity than free DOX., Conclusion: Findings from this study suggest that the SS-PU-SS-PEG micelles could achieve well-controlled triggered drug release in a reduction environment and could therefore improve the antitumor efficacy of osteosarcoma therapies., Translation Potential of This Article: In this study we developed PEG-sheddable reduction-sensitive polyurethane micelles (SS-PU-SS-PEG), which were able to achieve well-controlled triggered release of anti-tumor drug Doxorubicin (DOX) in an intracellular reduction environment. DOX-loaded SS-PU-SS-PEG micelles markedly improved the antitumor efficacy in a Saos-2 cells-bearing xenograft tumor model. Therefore, such micelles might be used as a novel drug delivery system for osteosarcoma treatment., (© 2019 The Author(s).)