Rate Splitting Multiple Access for GEO-LEO Coexisting Satellite Systems: Traffic-Aware Rate Maximization Precoder Design

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RIS-empowered LEO satellite networks for 6G: promising usage scenarios and future directions

Low-Earth orbit (LEO) satellite systems have been deemed a promising key enabler for current 5G and the forthcoming 6G wireless networks. Such LEO satellite constellations can provide worldwide three-dimensional coverage, high data rate, and scalability, thus enabling truly ubiquitous connectivity. On the other hand, another promising technology, reconfigurable intelligent surfaces (RISs), has emerged with favorable features, such as flexible deployment, cost & power efficiency, less transmission delay, noise-free nature, and in-band full-duplex structure. LEO satellite networks have many practical imperfections and limitations; however, exploiting RISs has been shown to be a potential solution to overcome these challenges. Particularly, RISs can enhance link quality, reduce the Doppler shift effect, and mitigate inter-/intra beam interference. In this article, we delve into exploiting RISs in LEO satellite networks. First, we present a holistic overview of LEO satellite communication and RIS technology, highlighting potential benefits and challenges. Second, we describe promising usage scenarios and applications in detail. Finally, we discuss potential future directions and challenges on RIS-empowered LEO networks, offering futuristic visions of the upcoming 6G era.</p

RIS-empowered LEO satellite networks for 6G: promising usage scenarios and future directions

Low-Earth orbit (LEO) satellite systems have been deemed a promising key enabler for current 5G and the forthcoming 6G wireless networks. Such LEO satellite constellations can provide worldwide three-dimensional coverage, high data rate, and scalability, thus enabling truly ubiquitous connectivity. On the other hand, another promising technology, reconfigurable intelligent surfaces (RISs), has emerged with favorable features, such as flexible deployment, cost & power efficiency, less transmission delay, noise-free nature, and in-band full-duplex structure. LEO satellite networks have many practical imperfections and limitations; however, exploiting RISs has been shown to be a potential solution to overcome these challenges. Particularly, RISs can enhance link quality, reduce the Doppler shift effect, and mitigate inter-/intra beam interference. In this article, we delve into exploiting RISs in LEO satellite networks. First, we present a holistic overview of LEO satellite communication and RIS technology, highlighting potential benefits and challenges. Second, we describe promising usage scenarios and applications in detail. Finally, we discuss potential future directions and challenges on RIS-empowered LEO networks, offering futuristic visions of the upcoming 6G era.</p

Electrodeposited Binder-free Mn-Co‑S Nanosheets toward High Specific-Energy Aqueous Asymmetric Supercapacitors

A simple single-step electrodeposition technique was followed for the three-dimensional (3D)-interconnected binary metallic manganese-cobalt sulfide nanosheets on nickel foam (MnCoS@NF). The architecture and chemical composition of the as-synthesized binder-free electrodes were analyzed by field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The MnCoS@NF achieves exceptionally high specific capacitance (1952.8 F g–1 at 2 A g–1) along with high cycle stability in a three-electrode cell measurement. Furthermore, an aqueous asymmetric supercapacitor (AAS) device was designed using electrodeposited MnCoS@NF in combination with reduced graphene oxide-coated NF (rGO@NF) as a positrode and negatrode, respectively. This device was able to provide very high specific energy (105.1 W h kg–1) at a specific power (7.25 kW kg–1) along with high cyclic stability (93.9% of specific capacitance retained after 3000 consecutive GCD cycles), which demonstrates its excellent candidature in supercapacitor applications

PDMS-ZnSnO₃/Ag₂O‑Based Nanocomposites for Mechanical Energy Harvesting and Antibacterial Applications

Bacterial fouling of self-powered implantable devices poses severe concerns for device implantation in the human body or water system installation. Here, a piezocomposite based on polydimethylsiloxane-zinc stannate/silver oxide (PDMS-ZnSnO3/Ag2O) has been fabricated and studied for its mechanical energy harvesting capability, as well as its antibacterial activity toward the Pseudomonas aeruginosa bacterium model. The surface decoration of n-type ZnSnO3 nanocubes with p-type Ag2O made an effective bulk p–n heterojunction, which augmented its energy harvesting and biological activities. The maximum output voltage, current, and power density of the fabricated piezoelectric nanogenerator (PENG) are ∼36 V, ∼1.9 μA, and ∼11.4 μW/cm2, respectively, under finger tapping. The enhanced energy harvesting property has been well explained by the high piezoelectric coefficient of modified nanoparticles obtained from the piezoresponse force microscopy (PFM) study. Moreover, the energy conversion efficiency of the PENG estimated during capacitor (10 μF) charging is ∼2.49%. Moreover, a Gram-negative bacterium model is chosen for the biofilm formation study. Biofilm assay, antimetabolite, and intracellular reactive oxygen species (ROS) studies reveal that the piezocomposite containing ZnSnO3/Ag2O is an excellent material for antibacterial activities. Thus, this work has proposed the idea of utilizing an electron-screen-enabled antibacterial piezocomposite, which could efficiently harvest human motion/blue energy incessantly with a specially designed electrode

PDMS-ZnSnO₃/Ag₂O‑Based Nanocomposites for Mechanical Energy Harvesting and Antibacterial Applications

Bacterial fouling of self-powered implantable devices poses severe concerns for device implantation in the human body or water system installation. Here, a piezocomposite based on polydimethylsiloxane-zinc stannate/silver oxide (PDMS-ZnSnO3/Ag2O) has been fabricated and studied for its mechanical energy harvesting capability, as well as its antibacterial activity toward the Pseudomonas aeruginosa bacterium model. The surface decoration of n-type ZnSnO3 nanocubes with p-type Ag2O made an effective bulk p–n heterojunction, which augmented its energy harvesting and biological activities. The maximum output voltage, current, and power density of the fabricated piezoelectric nanogenerator (PENG) are ∼36 V, ∼1.9 μA, and ∼11.4 μW/cm2, respectively, under finger tapping. The enhanced energy harvesting property has been well explained by the high piezoelectric coefficient of modified nanoparticles obtained from the piezoresponse force microscopy (PFM) study. Moreover, the energy conversion efficiency of the PENG estimated during capacitor (10 μF) charging is ∼2.49%. Moreover, a Gram-negative bacterium model is chosen for the biofilm formation study. Biofilm assay, antimetabolite, and intracellular reactive oxygen species (ROS) studies reveal that the piezocomposite containing ZnSnO3/Ag2O is an excellent material for antibacterial activities. Thus, this work has proposed the idea of utilizing an electron-screen-enabled antibacterial piezocomposite, which could efficiently harvest human motion/blue energy incessantly with a specially designed electrode