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The catalytic performance of spinel oxide NiCo2O4 for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) was investigated. It shows that NiCo2O4 synthesized via hydrothermal treatment at 90 ℃ followed by calcination at 350 ℃ exhibits excellent catalytic activity. Furthermore, Fe-doped MnO2 (marked as Fe-M) was introduced as a modifier to further improve the performance of NiCo2O4. As expected, the 20% Fe-M hybrid catalyst (NiCo2O4 modified with 20 wt% Fe-M) displays the best ORR and OER catalytic activity. This is evidenced by its high OER current density of 265 mA cm−2, high ORR current density of 220 mA cm−2, low OER Tafel slope of 119 mV dec−1, low ORR Tafel slope of 167 mV dec−1. These exceptional results can be attributed to the synergistic effect between NiCo2O4 and Fe-M. Based on synergistic effect, the 20% Fe-M hybrid catalyst exhibits the best catalytic activity for oxygen evolution reaction and oxygen reduction reaction. [ABSTRACT FROM AUTHOR]

The paper conducted a destructive test and nonlinear finite element analysisfor four pieces of pre-stressed concrete hollow plate,which have served for 20 years in the freezing-thawing region. The results showedthattypical bending destruction occurred in the test beams under the action of bending load, and the bearing capacity of the test beams decreased by a littlecompared with finite element analysis results. The test beams showed typical bending response before the reinforcement yieldedunder the action of uniform load,andthe pre-stressed reinforcement in the bending-shearing zone slippedafter reinforcement yielded, the final ultimate bearing capacity of the test beam was only 75% of the finite element calculation value

Cement fly ash gravel (CFG) pile composite foundation is an effective and economic foundation treatment approach, which is significant to building a foundation, subgrade construction, and so forth. The present paper aims to investigate the temperature behaviours of high latitudes and low altitude island permafrost when the CFG pile was constructed, in which FEM and field temperature monitoring of permafrost was utilized. The proposed findings demonstrate that the temperature disturbance of permafrost is obvious when the CFG pile was constructed, and the temperature variation of CFG pile and permafrost in FEM has a good agreement with the results of field temperature monitoring. Additionally, the influence of different height subgrade on the temperature field of CFG pile composite foundation was analyzed by FEM. The proposed findings demonstrate that the height of subgrade affects the maximum temperature increase of permafrost and the re-frozen time of permafrost after the construction of CFG pile composite foundation.

The perovskite oxide La0.4Sr0.6Co0.8Ni0.2O3 was prepared by sol–gel method and applied to the oxygen electrode. To further improve its catalytic activity, N-doped graphene (NG) was coupled with La0.4Sr0.6Co0.8Ni0.2O3. The samples were characterized structurally and morphologically using XRD, SEM, and FT-IR. The electrochemical test results showed that the current densities for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalyzed by the hybrid catalyst 10%NG (NG in total catalyst mass ratio of 10%) were 359 mA·cm−2 (0.9 V vs. Hg/HgO) and 393 mA·cm−2 (− 0.6 V vs. Hg/HgO), respectively. The excellent ORR/OER activity and stability of the hybrid catalyst can be attributed to the synergistic effect between La0.4Sr0.6Co0.8Ni0.2O3 and NG. [ABSTRACT FROM AUTHOR]

Abstract Novel organic–inorganic mesoporous luminescent hybrid material N, N′-bis(salicylidene)-thiocarbohydrazide (BSTC-SBA-15) has been obtained by co-condensation of tetraethyl orthosilicate and the organosilane in the presence of Pluronic P123 surfactant as a template. N,N′-bis(salicylidene)-thiocarbohydrazide (BSTC) grafted to the coupling agent 3-(triethoxysilyl)-propyl isocyanate (TESPIC) was used as the precursor for the preparation of mesoporous materials. In addition, for comparison, SBA-15 doped with organic ligand BSTC was also synthesized, denoted as BSTC/SBA-15. This organic–inorganic hybrid material was well-characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (HRTEM), and photoluminescence spectra, which reveals that they all have high surface area, uniformity in the mesostructure. The resulting materials (BSTC-SBA-15 and BSTC/SBA-15) exhibit regular uniform microstructures, and no phase separation happened for the organic and the inorganic compounds was covalently linked through Si–O bonds via a self-assemble process. Furthermore, the two materials have different luminescence range: BSTC/SBA-15 presents the strong dominant green luminescence, while BSTC-functionalized material BSTC-SBA-15 shows the dominant blue emission.

In this paper, the surface creepage of high-voltage self-breakdown switch which is used in 500-kV pulse modulator is analyzed in theory by employing the method of distributed element equivalent recurrent circuit. Moreover, the field distortion of the connecting ring of the switch is simulated by using software. According to the theoretical analysis, several methods to avoid surface creepage are obtained: 1) the outer housing of the switch should have high surface resistivity; 2) when the surface breakdown electric field is a constant, it is better to decrease the diameter of the electrode and to increase outer diameter and thickness of the outer housing; 3) in order to avoid field distortion, it is recommended, as far as possible, not to use metal connecting ring on the outer housing of the switch; and 4) there should be a clean environment for switch to work. Index Terms--Gas switch, surface creepage, surface insulation, surface resistivity.

The double perovskite Sr2Ni0.4Co1.6O6 was prepared, and a set of α-MnO2/Sr2Ni0.4Co1.6O6 hybrids with different α-MnO2 loadings were fabricated. The electrochemical experiments illustrate that the hybrid catalyst (40 wt% of α-MnO2) exhibited the highest activity, and the current density for the oxygen reduction reaction and oxygen evolution reaction were 0.2389 A cm−2 (− 0.6 V vs. Hg/HgO) and 0.3951 A cm−2 (1 V vs. Hg/HgO), respectively. The synergistic effect between α-MnO2 and Sr2Ni0.4Co1.6O6 was responsible for the improved catalytic activity. [ABSTRACT FROM AUTHOR]