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The power cable fire in an utility tunnel is difficult to control due to its characteristics of narrow and long structure, cable layer arrangement, and variable fire locations. Water mist system is one of commonly used method for fire control. This paper studied the fire extinguishing efficiency of high-pressure water mist system in utility tunnel by large eddy simulation (LES). In order to compare the fire extinguishing effect of the water mist system, two working conditions are designed, that is, the utility tunnel with water mist system and without water mist system. Results have shown that continuously operating of high-pressure water mist system can extinguish cable fires effectively. The cooling effect of the water mist is obvious and it can control fire development or extinguished fire. The temperature of utility tunnel would be reduced so as to prevent the structure from being destroyed.

Tunnel slope is an important factor affecting smoke spreading for a stopped subway train on fire. In this paper, a multi-scale method where one-dimensional (1D) network is coupled with three-dimensional (3D) field simulation is used to calculate smoke and temperature distributions for a fire occurred in the middle part of the subway train in tunnel. The tunnel slopes of 0‰, 12‰, 21‰ and 30‰ are considered. By comparing the temperature distribution in a condition with natural ventilation and with 2 m/s longitudinal ventilation, we comprehensively analyzed temperature, smoke spread characteristics. Results show that tunnel slope has a great influence on temperature and smoke profile when slope is higher than 12‰. The temperature at 1.8m would exceed the safe limit of 60°C at 60 s after fire ignition. The larger the slope, the higher temperature would be in the train carriage. For a train fire scenario with natural ventilation, within initial 120 s period the train compartment could keep a safe evacuation condition. This research would provide reference for making right evacuation plan of subway tunnel fire.

A Galinstan (GaInSn) liquid-metal-(LM-)based composite consisting of polydimethylsiloxane (PDMS) filled with GaInSn nanoparticles is developed for application as a tunable electromagnetic-(EM-)absorbing material. The minimum reflection loss (RL) of the GaInSn/PDMS composite is −19.3 dB at 14.8 GHz at a thickness of 2 mm, and the bandwidth over which the RL is lower than −10.0 dB is 9.9 GHz. The RL peak shifts from 14.8 GHz to 9.7 GHz under elongation by 30% shape deformation. After release, the absorption properties of the previously stretched sample almost returning to their original values suggests an approach to construct a reversibly tunable GaInSn LM-based EM-absorbing system.

Single crystalline wurtzite Mg0.47Zn0.53O films were grown on Ga:ZnO substrates by pulse laser deposition. The band gap of the films was measured to be 4.43 eV. Vertical devices were fabricated for solar blind photodetection, realizing a high responsivity of 2 A W−1 at 278 nm and −5 V bias as well as a rejection ratio (R 278 nm/R 350 nm) of over 6 × 103. A cut-off wavelength of 286 nm and a response time of 77 ms were also achieved. Besides, the devices showed stable response without degeneration under repeating illumination. The high performance of this photodetector was analyzed and attributed to the avalanche effect from high quality Mg0.47Zn0.53O/Ga:ZnO heterojunction at reverse bias. The avalanche gain was calculated to be 14.5 at −10 V.

The phase shift of the exit electron wave function at the Σ13 (510) tilt boundary of strontium titanate (SrTiO3) bicrystals was detected by electron holography. The results showed that there is a phase shift peak with a magnitude of ~0.3 rad at the centre of this grain boundary. Such a phase shift suggests that the potential barrier of ~3 V induced at the boundary core due to the interruption of the periodic potential of the crystal may be one of the intrinsic properties of grain boundary phenomena. Based on an electron dynamic diffraction, the phase of the exit electron wave function was simulated using a relaxed Σ13 (510) tilt boundary supercell with various occupancies of the atomic columns at the interface core. Coincidence of the measured and calculated results was achieved when the atomic columns are only half-occupied at the interface.

This study explores the large-area synthesis of controllable morphology, uniform, and high-quality monolayer. MoSe2 is essential for its potential application in optoelectronics, photocatalysis, and renewable energy sources. In this study, we successfully synthesized snow-like MoSe2 monolayers using a simple chemical vapor deposition method. Results reveal that snow-like MoSe2 is a single crystal with a hexagonal structure, a thickness of ~0.9 nm, and a lateral dimension of up to 20 μm. The peak position of the photoluminescence spectra is ~1.52 eV corresponding to MoSe2 monolayer. The growth mechanism of the snow-like MoSe2 monolayer was investigated and comprised a four-step process during growth. Finally, we demonstrate that the snow-like MoSe2 monolayers are ideal electrocatalysts for hydrogen evolution reactions (HERs), reflected by a low Tafel slope of ~68 mV/decade. Compared with the triangular-shaped MoSe2 monolayer, the hexangular snow-like shape with plentiful edges is superior for perfect electrocatalysts for HERs or transmission devices of optoelectronic signals.