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Core–shell Ni–Co(OH)F@NiCo2S4 nanorods with Ni doping and interface engineering have exhibited outstanding performances toward hydrazine-assisted hydrogen production.

Automatic obstacle detection is of great significance for improving the safety of train operation. However, the existing autonomous operation of trains mainly depends on the signaling control system and lacks the extra equipment to perceive the environment. To further enhance the efficiency and safety of the widely deployed fully automatic operation (FAO) systems of the train, this study proposes an intelligent obstacle detection system based on deep learning. It collects perceptual information from industrial cameras and light detection and ranging (LiDAR), and mainly implements the functionality including rail region detection, obstacle detection, and visual–LiDAR fusion. Specifically, the first two parts adopt deep convolutional neural network (CNN) algorithms for semantic segmentation and object detection to pixel-wisely identify the rail track area ahead and detect the potential obstacles on the rail track, respectively. The visual–LiDAR fusion part integrates the visual data with the LiDAR data to achieve environmental perception for all weather conditions. It can also determine the geometric relationship between the rail track and obstacles to decide whether to trigger a warning alarm. Experimental results show that the system proposed in this study has strong performance and robustness. The system perception rate (precision) is 99.994% and the recall rate reaches 100%. The system, applied to the metro Hong Kong Tsuen Wan line, effectively improves the safety of urban rail train operation.

Herein, a facile bottom–up approach for producing nitrogen-doped carbon quantum dots (N-CQDs) was carried out by the hydrothermal treatment of microcrystalline cellulose, in the presence of different nitrogen sources (blank/urea/ammonia water/ethanediamine(EDA)/Hexamethylenetetramine). The result showed that the fluorescence intensity and quantum yields (QYs) of N-CQDs with different nitrogen sources are all higher than that without nitrogen source. Compared with the other three nitrogen sources, N-CQDs prepared by EDA not only have the highest fluorescence intensity but also the largest QYs of 51.39%. Therefore, EDA was chosen as the nitrogen source to prepare N-CQDs. The obtained N-CQDs are uniform spherical particles with a diameter of 2.76 nm. The N-CQDs also exhibit excitation-dependent and long-wave emission properties. The emission range of N-CQDs is 470–540 nm. Moreover, N-CQDs as fluorescent agents successfully acted on purple LEDs (λem = 365 nm) to achieve white LEDs light emission. At the same time, a fluorescent thin layer chromatography plate was successfully prepared using N-CQDs, silica gel G and Sodium carboxymethylcellulose as raw materials. The separation trajectory of mixed sample of Sudan red III and kerosene on the fluorescent TLC plate is obviously clearer than that of the TLC plate.

Zinc phthalocyanine carrying sulfenyl and 6-sulfydryl linkers was firstly used to functionalize with sulfur vacancies MoS2. The synthesized MoS2/ZnPc composite was further prepared to be PVA (polyvinyl alcohol) thin films by a drop coating method. The microscopic structures and photophysical properties of novel MoS2/ZnPc composite were characterized. A series of analysis results indicate that zinc phthalocyanine with sulfenyl and 6-sulfydryl linkers is loaded to sulfur vacancies of MoS2 by ligand conjugation. The third order nonlinear optical properties of MoS2/ZnPc composite were studied by an open aperture Z-scan technique at 532 nm with 4 ns laser pulses width. In comparison with individual MoS2 or ZnPc, whether MoS2/ZnPc solution or MoS2/ZnPc/PVA film sample possesses larger third order nonlinear absorption coefficients (β) and lower limiting thresholds (F50). It can be ascribed to a combination of different NLO absorption mechanisms for MoS2/ZnPc composite, including one-photon absorption, two photon absorptions and nonlinear scattering of MoS2, triplet excited state absorption of ZnPc, nonlinear scattering of MoS2/ZnPc and the photo-induced electron transfer or energy transfer (PET/ET) process between MoS2 and ZnPc moieties.