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Proton exchange membrane fuel cells (PEMFCs) produce electrical energy using hydrogen as an energy source, characterized by enhanced energy conversion efficiency and diminished emissions, contributing to the sustainable development of energy. The hydrogen ejector is essential for improving the hydrogen utilization efficiency in PEMFCs. In this study, the theoretical design and simulation optimization of a hydrogen ejector used for a hydrogen fuel cell are performed in order to improve the efficiency of the hydrogen ejector. According to Sokolov's design method, the dimensions of the ejector nozzle and mixing chamber were calculated. A three-dimensional fluid simulation model of the ejector was established, and the accuracy of the model was verified by the experimental results. The influences of the nozzle outlet distance, the mixing chamber diameter, the length–diameter ratio of the mixing chamber, and the nozzle curvature on the ejector ratio were studied under multiple working conditions, and the optimal structural size of the ejector was obtained to satisfy the working conditions. It was found that the maximum ejector ratio of 1.21 could be achieved at a nozzle exit distance of 9 mm, a mixing chamber diameter of 7 mm, a mixing chamber length–diameter ratio of 9, and a nozzle curvature of 0.02. This work can provide some insights into the relationship between the structural parameters and performance of hydrogen ejectors. [ABSTRACT FROM AUTHOR] more...

A series of Mg2−xCoxTiO4 (x = 0.0, 0.5, 1.0, 1.5, 2.0) ceramics were synthesized by a conventional solid-state reaction route. The crystal structure, Raman vibrational characteristics, sintering behavior, microstructure, and microwave dielectric properties were systematically investigated. X-ray diffraction patterns and Raman spectroscopy indicated that the Mg2−xCoxTiO4 ceramics all exhibited a single-phase structure with cubic spinel (space group: Fd 3 ¯ m). The lattice parameters gradually increased with the continuous doping of Co2+ ions according to the Rietveld refinement results. Structure–property relationships were established based on Clausius–Mossotti equations, Raman spectroscopy, and bond valence theory. The εr values of Mg2−xCoxTiO4 ceramics were significantly affected by the ionic polarizability and the [Mg1/Co1O4] stretching vibration. The variation tendency of the Q × f values was closely related to the densification, and packing fraction. Moreover, the “rattling” effect at the A-site, the bond valence of the B-site, and the oxygen bond valence played an important role in controlling the τf values of Mg2−xCoxTiO4 single-phase ceramics. An excellent microwave dielectric property of εr = 15.88, Q × f = 38,157 GHz, and τf = − 32.21 ppm/°C can be obtained for Mg2−xCoxTiO4 ceramics with x = 1.0 sintered at 1350 °C for 4 h. [ABSTRACT FROM AUTHOR] more...

Dysfunction of the Hippo pathway is common in esophageal squamous carcinoma (ESCC). Chaetocin, a small molecular compound isolated from the marine fungus, exhibits potent anticancer effects. However, the anticancer effects of chaetocin on ESCC and its potential relationship to Hippo pathway remain unclear. Here, we demonstrated that chaetocin dramatically inhibited the proliferation in ESCC cells by causing cycle arrest in the M phase and activating the caspase-dependent apoptosis signaling pathway in vitro , and we also found that chaetocin induced the accumulation cellular reactive oxygen species (ROS). The RNA-seq analysis indicated that the Hippo pathway is one of the most enriched pathways after chaetocin treatment. We further revealed that chaetocin triggered the activation of Hippo pathway in ESCC cells, which is characterized by elevated phosphorylation levels of almost all core proteins in Hippo pathway, such as MST1 (Thr183), MST2 (Thr180), MOB1 (Thr35), LAST1 (Thr1079 and Ser909) and YAP (Ser127), ultimately leading to decreased nuclear translocation of YAP. Moreover, the MST1/2 inhibitor XMU-MP-1 not only partially rescued the inhibitory effect chaetocin-induced proliferation, but also rescued the chaetocin-induced apoptosis in ESCC cells. Furthermore, in vivo results confirmed the antitumor effect of chaetocin and its relationship with Hippo pathway. Taken together, our study demonstrates that chaetocin exhibits anticancer effects in ESCC via activation of Hippo pathway. These results provide an important basis for further research of chaetocin as a potential candidate for ESCC treatment. more...