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Porous CuO nanosheets were prepared on alumina tubes using a facile hydrothermal method, and their morphology, microstructure and gas sensing properties were investigated. The monoclinic CuO nanosheets had an average thickness of 62.5 nm and were embedded with numerous holes with diameters ranging 5 nm to 17 nm. The porous CuO nanosheets were used to fabricate gas sensors to detect hydrogen sulfide (H 2 S) operated at room temperature. The sensor showed a good response sensitivity of 1.25 with the respond/recovery time of 234 s and 76 s, respectively, when tested with the H 2 S concentrations as low as 10 ppb. It also showed a remarkably high selectivity to the H 2 S, but only minor responses to other gases such as SO 2 , NO, NO 2 , H 2 , CO and C 2 H 5 OH. The working principle of the porous CuO nanosheets based sensor to detect the H 2 S was identified to be the phase transition from semiconducting CuO to a metallic conducting CuS.

Objective To evaluate the bi‐planar robot navigation system for insertion of cannulated screws in femoral neck fractures. Method Between January 2016 and December 2016, 60 patients with femoral neck fractures were separately treated using percutaneous cannulated screws assisted by the bi‐planar robot navigation system (robot group) and conventional freehand surgery (freehand group). The fluoroscopy time, the number of drilling attempts, and the operation time were recorded during operations; the dispersion and parallelism of the cannulated screws on the posteroanterior and lateral images were measured after operations. Patients were followed up for 12–24 months and the Harris scores and the final results of the two groups were compared. Results During bi‐planar robot navigation system‐assisted surgery, the fluoroscopy time for acquisition of images was 2.3 seconds on average, and the time for planning screws during the operation was 2.8 min on average. The average fluoroscopy time during the placement of the guide pin was 5.7 seconds and 14.14 seconds (P = 0.00), respectively. The average time of the placement of the cannulated screws was 12.7 min and 19.4 min (P = 0.00), respectively, in the robot group and the freehand group. In the robot group, only one guide pin was replaced during the operation, and the average number of adjustments for each guide pin was 2.39 in the freehand group. The screw parallelism and dispersion measured by postoperative imaging in the robot group were significantly superior to those in the freehand group. From postoperative CT it was evident that there were 5 cases of screws exiting the posterior cortex in both groups. During the follow‐up phase, 1 case of femoral head necrosis and 5 cases of femoral neck shortening of more than 10 mm occurred in the robotic navigation group; 3 cases of femoral head necrosis, 1 case of fracture nonunion, and 2 cases of shortening of more than 10 mm occurred in the freehand group. At 18 months after surgery, the average Harris scores of the patients were 85.20 and 83.45, respectively, with no significant difference. Conclusion Using bi‐planar robot navigation system‐assisted placement of femoral neck cannulated screws can significantly reduce the time of intraoperative fluoroscopy, drilling attempts, and operation time. The placed screws are superior to the screws placed freehand in relation to parallelism and dispersion. However, it is still necessary for surgeons to have a good reduction of the femoral neck fracture before surgery and to be proficient in the operation of the robot navigation system. In summary, the bi‐planar robot navigation system is an effective assistant instrument for surgery.

The lack of new functional applications for metallic glasses hampers further development of these fascinating materials. In this letter, we report for the first time that the MgZn-based metallic glass powders have excellent functional ability in degrading azo dyes which are typical organic water pollutants. Their azo dye degradation efficiency is about 1000 times higher than that of commercial crystalline Fe powders, and 20 times higher than the Mg-Zn alloy crystalline counterparts. The high Zn content in the amorphous Mg-based alloy enables a greater corrosion resistance in water and higher reaction efficiency with azo dye compared to crystalline Mg. Even under complex environmental conditions, the MgZn-based metallic glass powders retain high reaction efficiency. Our work opens up a new opportunity for functional applications of metallic glasses.