Metasurface-based dual-sense circularly polarized antenna for MIMO/full-duplex applications.

This paper introduces a two-element antenna array with dual-sense circular polarization, wideband operation, and high isolation characteristics. The antenna consists of two conventional truncated corner patches and an extra layer of metasurface (MS) located above the radiating patches. The overall dimensions of the proposed antenna are 0.92 λ0 × 0.73 λ0 × 0.05 λ0 and the element spacings are 0.02 λ0 and 0.39 λ0 with respect to edge-to-edge and center-to-center spacings. For validation, measurements on a fabricated antenna prototype are carried out. The measured data demonstrate that the presented MS-based antenna has a wide operating bandwidth of 14.5% with high isolation of better than 26 dB. The excellent performance could be concluded from the results of the investigation, which indicates that the proposed MS-based antenna could be a good candidate for multiple-input multiple-output (MIMO) and full-duplex applications.

Natural Cellulose Fiber-Derived Photothermal Aerogel for Efficient and Sustainable Solar Desalination.

Aerogels are becoming a promising platform to fabricate photothermal materials for use in solar steam generation (SSG), which have remarkable application potential in solar desalination, due to their excellent thermal management, salt resistance, and considerable water evaporation rate. In this work, a novel photothermal material is fabricated by forming a suspension between sugarcane bagasse fibers (SBF) and poly(vinyl alcohol), tannic acid (TA), and Fe3+ solutions via hydrogen bonds of hydroxyl groups. After freeze drying, the fabricated SBF aerogel-based photothermal (SBFAP) material possesses a 3D interconnected porous microstructure, which could enhance water transportation ability, reduce thermal conductivity, and quickly dissolve salt crystals on the SBFAP surface. Thanks to the formation of micro/nanosized complexes between TA and Fe3+ ions on the SBFAP material, the SBFAP exhibits high light capture and water evaporation rate (2.28 kg m-2 h-1). In particular, due to strong hydrogen bonding and the SBF, the SBFAP material is reinforced, thereby exhibiting excellent structural stability in seawater. Moreover, the high salt tolerance of SBFAP favors its high desalination performance for at least 76 days of continuous evaporation under actual conditions. This research paves the way for the fabrication of natural cellulose fiber-based photothermal materials for application in solar desalination.

One-pot synthesis of manganese oxide/graphene composites via a plasma-enhanced electrochemical exfoliation process for supercapacitors.

In this work, a feasible one-pot approach to synthesize manganese oxide/graphene composites, the so-called plasma-enhanced electrochemical exfoliation process (PE3P), has been developed. Herein, a composite of graphene decorated with manganese oxide nanoparticles was prepared via PE3P from a KMnO4 solution and graphite electrode under a voltage of 70 V in an ambient environment. By controlling the initial KMnO4 concentration, we obtained distinct MnO2/graphene samples. The prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and Raman spectroscopy. The electrochemical measurements of the MnO2/graphene composites revealed that the specific capacitance of the samples is approximately 320 F g-1 at a scan rate of 10 mV s-1, which is comparably very high for manganese oxide/carbon-based supercapacitor electrode materials. Considering the simple, low-cost, one-step and environmentally friendly preparation, our approach has the potential to be used for the fabrication of MnO2/graphene composites as the electrode materials of supercapacitors.