Core-Shell Structured Silica-Coated Iron Nanowires Composites for Enhanced Electromagnetic Wave Absorption Properties.

In this study, we successfully prepared core-shell heterostructured nanocomposites (Fe NWs@SiO2), with ferromagnetic nanowires (Fe NWs) as the core and silica (SiO2) as the shell. The composites exhibited enhanced electromagnetic wave absorption and oxidation resistance and were synthesized using a simple liquid-phase hydrolysis reaction. We tested and analyzed the microwave absorption properties of Fe NWs@SiO2 composites with varied filling rates (mass fractions of 10 wt%, 30 wt%, and 50 wt% after mixing with paraffin). The results showed that the sample filled with 50 wt% had the best comprehensive performance. At the matching thickness of 7.25 mm, the minimum reflection loss (RLmin) could reach -54.88 dB at 13.52 GHz and the effective absorption bandwidth (EAB, RL < -10 dB) could reach 2.88 GHz in the range of 8.96-17.12 GHz. Enhanced microwave absorption performance of the core-shell structured Fe NWs@SiO2 composites could be attributed to the magnetic loss of the composite, the core-shell heterogeneous interface polarization effect, and the small-scale effect induced by the one-dimensional structure. Theoretically, this research provided Fe NWs@SiO2 composites with highly absorbent and antioxidant core-shell structures for future practical applications.

Recent Progress in Iron-Based Microwave Absorbing Composites: A Review and Prospective.

With the rapid development of communication technology in civil and military fields, the problem of electromagnetic radiation pollution caused by the electromagnetic wave becomes particularly prominent and brings great harm. It is urgent to explore efficient electromagnetic wave absorption materials to solve the problem of electromagnetic radiation pollution. Therefore, various absorbing materials have developed rapidly. Among them, iron (Fe) magnetic absorbent particle material with superior magnetic properties, high Snoek's cut-off frequency, saturation magnetization and Curie temperature, which shows excellent electromagnetic wave loss ability, are kinds of promising absorbing material. However, ferromagnetic particles have the disadvantages of poor impedance matching, easy oxidation, high density, and strong skin effect. In general, the two strategies of morphological structure design and multi-component material composite are utilized to improve the microwave absorption performance of Fe-based magnetic absorbent. Therefore, Fe-based microwave absorbing materials have been widely studied in microwave absorption. In this review, through the summary of the reports on Fe-based electromagnetic absorbing materials in recent years, the research progress of Fe-based absorbing materials is reviewed, and the preparation methods, absorbing properties and absorbing mechanisms of iron-based absorbing materials are discussed in detail from the aspects of different morphologies of Fe and Fe-based composite absorbers. Meanwhile, the future development direction of Fe-based absorbing materials is also prospected, providing a reference for the research and development of efficient electromagnetic wave absorbing materials with strong absorption performance, frequency bandwidth, light weight and thin thickness.

Total Factor Productivity and High-Quality Economic Development: A Theoretical and Empirical Analysis of the Yangtze River Economic Belt, China.

This paper focuses on the total factor productivity (TFP) and high-quality economic development in China by examining 11 Chinese provinces and cities in the Yangtze River Economic Belt from 2007 to 2018. We use the Solow residual method to calculate the TFP growth rate of the 11 provinces and cities. Based on the panel data, we have analyzed the influencing factors of TFP theoretically and empirically from the overall region and upstream region, and midstream region and downstream region, respectively. The regression results show that: (1) The whole characteristics generally show the TFP growth trend of the upstream region, midstream region and downstream region are consistent with that of the overall region, and the growth rate of TFP slows down gradually. Meanwhile the differences in TFP growth between the upstream region, midstream region and downstream region show an increase at first and then a decrease. (2) Regarding the influencing factors, there are differences in the direction and extent of the impact of each factor such as the level of openness, R&D investment, industrial structure, government expenditure and human capital on the TFP of the overall region, upstream region, midstream region and downstream region. (3) Based on the results of the theoretical and empirical analysis, we have proposed a series of measures for the sustainable high-quality development of the Yangtze River Economic Belt.