Selective oxidation of carbon monoxide over CuO–CeO2 catalyst: Effect of hydrothermal treatment

Copper oxide–ceria (CuO–CeO₂) catalyst for selective oxidation of carbon monoxide (CO) was prepared by co-precipitation and hydrothermal treatment methods and evaluated for catalytic activity in a reformate gas composition which simulated the produced gas from methanol steam reforming. By applying the condition of hydrothermal treatment, the catalytic activity of CuO–CeO₂ catalyst was increased and the operating temperature window, in which the concentration of carbon monoxide was lower than 10 ppm, was widened. From the thermogravimetric (TG) results of hydrothermally treated catalyst precursor, CuO–CeO₂ catalyst did not show any improvement in physical properties such as Brunauer Emmett Teller (BET) surface area, pore volume and average pore diameter, but the chemical stability might be enhanced by hydrothermal treatment. By hydrothermal treatment, cuprous ion in the CuO–CeO₂ catalyst migrated to the surface of catalyst resulting in increased surface concentration of copper and formation of cupric oxide on the surface of catalyst during calcination. While increasing the calcination temperature (i.e. above 800 °C), the phase separation occurred with a part of copper and cupric oxide was formed on the surface of catalyst which was observed in X-ray diffraction (XRD) analysis.     

UAV-assisted multi-hop D2D relaying for communication in large disaster area

An unmanned aerial vehicle (UAV)-assisted communication is a promising technique for enabling ground users in a non-functional area (NFA) or disaster area to communicate. All the base stations in the disaster area may be partially or fully damaged due to the natural calamity. Device-to-device (D2D) communication can be a viable solution for immediate connection between users in an NFA. We propose a UAV-assisted multi-hop D2D communication following a hybrid power-time switching (PTS) in this paper. Moreover, a D2D user of a cluster can communicate with another D2D user in a different cluster through UAVs. However, D2D users can harvest energy from their respective ad hoc energy stations and forward the information to the nearby D2D user following a hybrid PTS-based strategy. We propose a time frame for the same and show a node-based energy harvesting strategy. The expressions of outage probability, throughput, end-to-end energy consumption, and energy efficiency are developed for the Rician and Nakagami-m faded channel. The impact of several network parameters such as energy harvesting factor, energy harvesting efficiency, and fading parameter on the network performance is also indicated.     

Impacts of Cattaneo–Christov heat flux on the radiative MHD nanofluid flow past a stretched cylinder under multiple slip conditions

This investigation explores the features of velocity distribution, mass and heat transmissions of nanoliquid stream over a permeable cylinder accompanied by Cattaneo–Christov heat model and thermal radiation with nonlinear sort. Multiple slip conditions have been also encountered here. A magnetic force is oriented along vertically upward. The existence of thermophoresis together with Brownian motion has been assumed here. The foremost equations and associated boundary conditions have been normalized through the similarity technique. Then we solve the system numerically along with the fourth-order Runge–Kutta shooting scheme by using the software MAPLE-17 and round it with our preassigned accuracy level. The obtained outcomes are epitomized by tables and graphs. All of the impacts have been compared in suction and injection correspondingly and explained with proper reasoning. In charts, the physical consignments (such as Sherwood number, Nusselt number and skin friction) reveal the transference of mass and temperature and amount of friction by nanoparticles in the nanocomposition. For suction, the nanofluidic temperature gradually diminished due to the advanced thermal relaxation, whereas the contrary fact is exhibited in injection. The relaxation parameter of concentration provides a positive influence on mass transmission. The rates of amplification of this transportation are 1.99% and 3.87%, measured in consideration of injection and suction, respectively. Thermal radiation influenced the fluid's temperature in a positive direction. It increases Nusselt number with 41.75% in suction, and 45.21% is recorded for injection.     

Influence of multiple slips on magnetically driven nanofluid flow over an externally heated stretching cylinder

In this article, we have inspected multiple slippery consequences along a stretching cylinder. Brownian migration along with thermophoresis is clutched together with an external heat source. Magnetic influence is considered perpendicular to the cylinder. Standard flow systems are transfigured to ordinary differential equations by well-qualified similarity transformations. They are solved by the Runge–Kutta scheme of the fourth-order (shooting technique) method with the assistance of MAPLE software. The entire simulation is done with a proper accuracy rate and the upshots are portrayed by graphs and tables. All results are compared under no slip and with slip provisions. Augmentation in Reynolds number and magnetic parameter uprise the velocity lines and the slip effect reduces the magnitude decently. The thermal jump effect reduces the magnitude of the heat transfer rate. The solutal slip effect decreases the concentration boundary layer for magnetic and Brownian migration specifications. Approximately 6.69% and 6.79% drop in Nusselt number is spotted for Brownian migration and thermophoresis parameters. The external heat source parameter brings out 14.98% inflation in the Nusselt number significantly.     

Extreme Specific Stiffness Through Interactive Cellular Networks in Bi-Level Micro-Topology Architected Metamaterials

Architected lattice materials, realized through artificial micro-structuring, have drawn tremendous attention lately due to their enhanced mechanical performances in multifunctional applications. However, the research area on the design of artificial microstructures for the modulation of mechanical properties is increasingly becoming saturated due to extensive investigations considering different possibilities of lattice geometry and beam-like network design. Thus, there exists a strong rationale for innovative design at a more elementary level. It can enhance and grow the microstructural space laterally for exploiting the potential of geometries and patterns in multiple length scales, and the mutual interactions thereof. A bi-level design is proposed, where besides having the architected cellular networks at an upper scale, the constituting beam-like members at a lower scale are further topology-engineered for most optimum material utilization. The coupled interaction of beam-level and lattice-level architectures can enhance the specific elastic properties to an extreme extent (up to ≈25 and 20 times, depending on normal and shear modes, respectively), leading to ultra-lightweight multifunctional materials for critical applications under static and dynamic environments.     

Synthesis of Dihydrobenzofuro[3,2-b]chromenes as Potential 3CLpro Inhibitors of SARS-CoV-2: A Molecular Docking and Molecular Dynamics Study

The recent emergence of pandemic of coronavirus (COVID-19) caused by SARS-CoV-2 has raised significant global health concerns. More importantly, there is no specific therapeutics currently available to combat against this deadly infection. The enzyme 3-chymotrypsin-like cysteine protease (3CLpro) is known to be essential for viral life cycle as it controls the coronavirus replication. 3CLpro could be a potential drug target as established before in the case of severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). In the current study, we wanted to explore the potential of fused flavonoids as 3CLpro inhibitors. Fused flavonoids (5a,10a-dihydro-11H-benzofuro[3,2-b]chromene) are unexplored for their potential bioactivities due to their low natural occurrences. Their synthetic congeners are also rare due to unavailability of general synthetic methodology. Here we designed a simple strategy to synthesize 5a,10a-dihydro-11H-benzofuro[3,2-b]chromene skeleton and it's four novel derivatives. Our structural bioinformatics study clearly shows excellent potential of the synthesized compounds in comparison to experimentally validated inhibitor N3. Moreover, in-silico ADMET study displays excellent druggability and extremely low level of toxicity of the synthesized molecules. Further, for better understanding, the molecular dynamic approach was implemented to study the change in dynamicity after the compounds bind to the protein. A detailed investigation through clustering analysis and distance calculation gave us sound comprehensive data about their molecular interaction. In summary, we anticipate that the currently synthesized molecules could not only be a potential set of inhibitors against 3CLpro but also the insights acquired from the current study would be instrumental in further developing novel natural flavonoid based anti-COVID therapeutic spectrums.     

High-Throughput Exploration of Triple-Cation Perovskites via All-in-One Compositionally-Graded Films

Many devices heavily rely on combinatorial material optimization. However, new material alloys are classically developed by studying only a fraction of giant chemical space, while many intermediate compositions remain unmade in light of the lack of methods to synthesize gapless material libraries. Here report a high-throughput all-in-one material platform to obtain and study compositionally-tunable alloys from solution is reported. This strategy is applied to make all Cs_xMA_yFA_zPbI₃ perovskite alloys (MA and FA stand for methylammonium and formamidinium, respectively), in less than 10 min, on a single film, on which 520 unique alloys are then studied. Through stability mapping of all these alloys in air supersaturated with moisture, a range of targeted perovskites are found, which are then chosen to make efficient and stable solar cells in relaxed fabrication conditions, in ambient air. This all-in-one platform provides access to an unprecedented library of compositional space with no unmade alloys, and hence aids in a comprehensive accelerated discovery of efficient energy materials.     

Emergence of a Non-Van der Waals Magnetic Phase in a Van der Waals Ferromagnet

Manipulation of long-range order in 2D van der Waals (vdW) magnetic materials (e.g., CrI₃, CrSiTe₃ ,etc.), exfoliated in few-atomic layer, can be achieved via application of electric field, mechanical-constraint, interface engineering, or even by chemical substitution/doping. Usually, active surface oxidation due to the exposure in the ambient condition and hydrolysis in the presence of water/moisture causes degradation in magnetic nanosheets that, in turn, affects the nanoelectronic /spintronic device performance. Counterintuitively, the current study reveals that exposure to the air at ambient atmosphere results in advent of a stable nonlayered secondary ferromagnetic phase in the form of Cr₂Te₃ (T_C2 ≈160 K) in the parent vdW magnetic semiconductor Cr₂Ge₂Te₆ (T_C1 ≈69 K). The coexistence of the two ferromagnetic phases in the time elapsed bulk crystal is confirmed through systematic investigation of crystal structure along with detailed dc/ac magnetic susceptibility, specific heat, and magneto-transport measurement. To capture the concurrence of the two ferromagnetic phases in a single material, Ginzburg-Landau theory with two independent order parameters (as magnetization) with a coupling term can be introduced. In contrast to the rather common poor environmental stability of the vdW magnets, the results open possibilities of finding air-stable novel materials having multiple magnetic phases.