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The mobile fog-based cloud (MFBC) plays a major role for the Internet of Things (IoT) and is highly suitable for obtaining virtualized data without additional waiting time. However, the limited battery power of mobile devices limits access to abundant data. To address this problem, an energy-efficient and secure algorithm should be introduced to reduce energy consumption for the MFBC. In this paper, an energy-efficient and secure hybrid (EESH) algorithm is introduced for the MFBC to support the IoT. The EESH algorithm uses the voltage scaling factor to reduce energy consumption. The performance of the EESH algorithm is substantially better than the state-of-the-art contending algorithms when the number of IoT-tasks increases, and EESH consumes minimal energy. Furthermore, the identity of mobile cloud users is of paramount significance; therefore, the EESH is further secured by applying a malicious data detection (MDD) algorithm using blockchain technology. The capability of the processors on the server side of the MFBC is analyzed and improved for the IoT. The proposed EESH, MDD and underlying algorithms are programmed on the Java platform. Finally, the performance of the proposed algorithms on the MFBC is compared with that of known algorithms in terms of security, energy efficiency, throughput and latency.

Synergistic effect in alloys and plasmonic effect have both been explored for increasing the efficiency of water splitting. In depth understanding and comparison of their respective contributions in certain promising systems is highly desired for catalyst development, yet rarely investigated so far. We report herein our thorough investigations on a series of highly interesting nanocomposites composed of Pt, Au and C 3 N 4 nanocomponents, which are designed to benefit from both synergistic and plasmonic effects. Detailed analyses led to an important conclusion that the contribution from the synergistic effect was at least 3.5 times that from the plasmonic effect in the best performing sample, Pt 50 Au 50 alloy decorated C 3 N 4. It showed remarkable turnover frequency of >1.6 mmol h −1 g −1 at room temperature. Our work provides physical insights for catalyst development by rationally designing samples to compare long-known synergistic effect with recently emerging, attractive plasmonic effect and represents the first case study in the field.

Accurate detection of highly toxic aromatic nitro compounds in the water medium is urgent for the protection of human health and eco system. In the present study, we report the graphene oxide/ magnesium oxide nanocomposite (GO/MgO-NC) has been proposed for electrochemical analysis of nitrobenzene (NBZ) in water samples. The GO/MgO-NC was characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscope, transmission electron microscopy, and energy dispersive X-ray analysis. Likewise, the electrochemical behaviour of NBZ was investigated through cyclic voltammetry and differential pulse voltammetry. The GO/MgO-NC electrode shows an excellent NBZ sensing properties compared to other electrodes. Under optimized conditions, the GO/MgO-NC/GCE can well measure the concentrations of NBZ in the range of 0.1–38.9 µM and 58.5–2333.5 µM with a low limit of detection of 0.01 µM. Besides, the GO/MgO-NC/GCE exhibits excellent selectivity, repeatability, reproducibility and stability. More importantly, the proposed GO/MgO-NC/GCE was further expanded to quantify NBZ in water samples with recoveries between 99.35–99.80%, providing an effective approach for the trace of NBZ in environmental medium.

Although existing membrane filtration technologies offer practical solutions for the removal of heavy metal ions from wastewater, there remains a great need for the realization of a membrane simultaneously possessing excellent selectivity, high permeability, and antifouling capability. Towards this end, novel buckypaper (BP) membranes were fabricated from multi-walled carbon nanotubes (MWCNTs) via vacuum filtration technique and the capability of two biopolymers (i.e. chitosan and carrageenan) to facilitate the formation of aqueous dispersions of MWCNTs was investigated alone and in combination of each other. For the first time, this study shows that the combination of BP membrane and both biopolymers (MWCNTs/chitosan-carrageenan) performs remarkably in terms of mechanical properties and high rejection of heavy metals. At an applied pressure of one bar, the removal of copper and lead reached 94% and 91%, respectively. The MWCNTs/chitosan-carrageenan membrane was also found to be mechanically robust, with a tensile strength and Young’s modulus of 30.69 ± 2.6 MPa and 3.78 ± 0.03 GPa, respectively. However, the MWCNTs/chitosan membrane showed superior water permeate flux, reaching up to 180 L/h.m2. The morphological properties and surface area (193 ± 3 to 285 ± 5 m2/g) of the three membrane types were also characterized using scanning electron microscopy and Brunauer, Emmett, and Teller analysis.

A solid oxide fuel cell (SOFC) is an energy converter device that directly converts the fuel's chemical energy into thermal and electrical energies. However, the performance of a SOFC is sensitive to the operating conditions, which indicates the need to control the operating parameters such as the operating temperature and inlet gas physical and chemical properties. In this paper, a three-dimensional (3-D) computational fluid dynamics (CFD) model of a button SOFC has been developed based on fluid flow, mass and heat transfer, and current and potential transport to study the performance of the button SOFC at different operating temperatures and flow rates. The results of all the investigated operating conditions have been validated with an in-house button SOFC. The results showed that the current density of the button SOFC increased significantly, to about 108.5% at average cell voltage 0.6 V and at oxygen flow rate of 1.8 L min−1 and hydrogen flow rate of 0.6 L min−1, when the operating temperature increased from 973 to 1023 K. However, less sensitivity has been found at the same average voltage of 0.6 V and an operating temperature of 973 K, the increase in the current density was about 9.7% when the flow rate of the oxygen increased from 0.4 to 0.6 L min−1, and the hydrogen flow rate increased from 1.2 to 1.8 L min−1, respectively; this was in good agreement with the experimental results.