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Microwave technology is commonly used in many fields such as wireless communication and medical treatment, which are closely related to social development. However, electromagnetic pollution caused by microwaves is gradually increasing and the demand for high-performance microwave absorption materials is also increasing. Porous materials obtained by the pyrolysis of metal–organic frameworks (MOFs) at high temperatures exhibit good conductivity and magnetism, and the original skeleton structure of MOFs can be maintained; thus, MOF-derived materials can be considered viable candidates of microwave absorption materials. In this paper, Fe-CN@CoCN materials were prepared by pyrolyzing a ferrocene (Fc)-doped core–shell zeolite imidazole framework (Fc-ZIF-8@ZIF-67) at 700, 800, and 900 °C for 2 h in an Ar atmosphere. The obtained Fe-CN@CoCN-0.25-700 nanocomposite exhibited excellent microwave absorption (MA) performance with a minimum reflection loss (RLmin) of −42.27 dB at 5.68 GHz and an effective absorption bandwidth (EAB, RL < −10 dB) of 4.80 GHz at a thickness of 2.5 mm. The Fe-CN@CoCN-0.25-800 nanocomposite possessed optimized MA properties with an RLmin of −40.78 dB at 12.56 GHz and an EAB of 4.16 GHz at relatively low thickness of 2 mm. Fe-CN@CoCN nanocomposites are expected to be efficient materials for microwave absorption coatings. [ABSTRACT FROM AUTHOR]

Although there are many studies on the Jurassic source rocks in the northern margin of the Qaidam Basin, the characteristics of biomarkers and products with the same source rock in different evolutionary stages are still not well understood. Such an understanding is essential for accurately estimating oil and gas resources. In order to explore the hydrocarbon-generation potential of high-quality source rocks of the Middle Jurassic and the evolution of liquid hydrocarbons and biomarkers, we carried out simulation research (under hydrous conditions) at various temperatures (250, 300, 350, 400 and 450 °C) with the mudstone of the Yu 33 well in the Yuka Sag. The results revealed that the "oil window" of the Middle Jurassic source rocks in the Yuka area was 300 °C (simulation temperature, Ro = 0.84%), but this was not the peak of hydrocarbon expulsion, which was gradually reached and stabilized above 350 °C. Overall, the concentration of alkanes and aromatics increased with temperature; although the concentration of alkanes was complex in the low evolutionary stages, temperature (simulated maturity) was still the main factor controlling the change in alkanes and aromatics. Among the maturity parameters of biomarkers, the ratio of ∑tricyclic terpanes/∑hopanes was the most effective parameter for indicating the maturity evolution of the Yuka area, but others were complicated by the increasing temperature. Therefore, when evaluating maturity, the applicability of other parameters needed to be fully considered. The results obtained offer new insights in the research on liquid-hydrocarbon and biomarker evolution of the Middle Jurassic source rocks in the Yuka Sag of the Qaidam Basin. [ABSTRACT FROM AUTHOR]

A new NO2 nanohybrid of a gas sensor (CTAB-MoS2/rGO) was constructed for sensitive room-temperature detection of NO2 by 3D molybdenum disulfide (MoS2) and reduced graphene oxide (rGO), assisted with hexadecyl trimethyl ammonium bromide (CTAB). In comparison with MoS2 and MoS2/rGO, the BET and SEM characterization results depicted the three-dimensional structure of the CTAB-MoS2/rGO nanohybrid, which possessed a larger specific surface area to provide more active reaction sites to boost its gas-sensing performance. Observations of the gas-sensing properties indicated that the CTAB-MoS2/rGO sensor performed a high response of 45.5% for 17.5 ppm NO2, a remarkable selectivity of NO2, an ultra-low detection limit of 26.55 ppb and long-term stability for a 30-day measurement. In addition, the response obtained for the CTAB-MoS2/rGO sensor was about two to four times that obtained for the MoS2/rGO sensor and the MoS2 sensor toward 8 ppm NO2, which correlated with the heterojunction between MoS2 and rGO, and the improvement in surface area and conductivity correlated with the introduction of CTAB and rGO. The excellent performance of the CTAB-MoS2/rGO sensor further suggested the advantage of CTAB in assisting a reliable detection of trace NO2 and an alternative method for highly efficiently detecting NO2 in the environment. [ABSTRACT FROM AUTHOR]

The influence of rare earth element (RE) Y on the microstructure and corrosion behavior of extruded AZ91 Mg alloy was surveyed via morphology characterization and corrosion performance measurements. The results indicate the corrosion resistance of the transversal section of AZ91 Mg alloy containing Y was improved compared with AZ91 Mg alloy without Y. The corrosion resistance of the longitudinal section of AZ91 Mg alloy with Y was lower than that of AZ91 Mg alloy without Y. The change of corrosion resistance can be attributed to the dispersion and volume fraction of the second phase, the effect of cathodic reduction rate, and the refined second phase. [ABSTRACT FROM AUTHOR]