Impacts of slip and mass transpiration on Newtonian liquid flow over a porous stretching sheet

This article focuses on analytic solutions for Newtonian fluid flow with slip and mass transpiration on a porous stretching sheet using the differential transform method and Pade approximants of an exceptionally nonlinear differential equation. The impacts of different parameters including mass transpiration (suction/injection), Navier's slip, and Darcy number parameters on the velocity of the liquid and tangential stress are discussed. A comprehensive comparison of our results with the previous one in the literature is made, and the results showed good agreement. An investigation is conducted of a combination of magnetic liquids that are conceivably pertinent for wound medicines, skin repair, and astute coatings for natural gadgets. It is found that there is a decrease in the velocity profiles and the boundary layer thickness for the case of suction.     

Carbon-based TiO2-x heterostructure nanocomposites for enhanced photocatalytic degradation of dye molecules

Application of brown titanium dioxide (TiO_2-x) and its modified composite forms in the photocatalytic decomposition of organic pollutants in the environment is a promising way to provide solutions for environmental redemption. Herein, we report the synthesis of effective and stable TiO_2-x nanoparticles with g-C₃N₄, RGO, and multiwalled carbon nanotubes (CNTs) using a simple hydrothermal method. Among all the as-synthesized samples, excellent photocatalytic degradation activity was observed for RGO-TiO_2-x nanocomposite with high rate constants of 0.075 min^?1_, 0.083 min^?1 and 0.093 min^?1 for methylene blue, rhodamine-B, and rosebengal dyes under UV–Visible light irradiation, respectively. The altered bandgap (1.8 eV) and the large surface area of RGO-TiO_2-x nanocomposite impacts on both absorption of visible light and efficiency of photogenerated charge electron (e^?)/hole (h⁺) pair separation. This resulted in enhanced photocatalytic property of carbon-based TiO_2-x nanocomposites. A systematic study on the influence of different carbon nanostructures on the photocatalytic activity of brown TiO_2-x is carried out.     

Hydrothermal synthesis of α-SnWO4: Application to lithium-ion battery and photocatalytic activity

The high capacity anode material is required to replace the most commonly used anode - graphite to keep up the global demand to achieve the goal. Multi-metal oxide has gained keen attention for its higher theoretical capacity and relatively stable than a single metal oxide. α-SnWO₄ has a theoretical capacity of 850 mAh g^?1 which is greater than graphite (372 mAh g^?1). α-SnWO₄ has been synthesized through low-temperature hydrothermal method using tin chloride and sodium tungstate as a precursor in acidic medium (succinic acid) at 200 °C for 12 h. The obtained product has been characterized using various analytical tools such as XRD, FT-IR, UV-DRS, BET, PL, SEM, and HR-TEM. XRD analysis shows the orthorhombic phase with a crystallite size of ~25 nm α-SnWO₄has been examined as an electrode material for Li-ion battery (LIB) and displays an initial discharge capacity of 985 mAh g^?1. Columbic efficiency close to 100% has been observed for 100 cycles. The stability of the electrode material was studied at different C-rates. Band-gap calculated using UV-DRS (Eg = 1.9 eV) shows that α-SnWO₄ is a good candidate for photocatalytic degradation. Results of the photocatalytic experiment using methylene blue (MB) as a model pollutant in an aqueous medium shows good results. The above applications show that α-SnWO₄ is multifunctional materials for diverse applications.     

On oscillatory rotating convection of a couple-stress fluid with helical force

Linear and weakly nonlinear stability analyses of thermosolutal convection in a couple-stress fluid with effects of helical force and rotation are performed. The governing nondimensional equations are solved using the normal modes. We have shown the effect of the helical force parameter, solutal Rayleigh number, Couple stress parameter, Lewis number, Taylor number, and Prandtl number on stationary and oscillatory convection regions and presented graphically. Solutal Rayleigh number, Couple stress parameter, Lewis number, and Taylor number have a stabilizing effect on the system whereas the helical force parameter has a destabilizing effect on the system. To study heat transport by convection we have derived the Ginzburg–Landau equation.     

Low temperature ionothermal synthesis of TiO2 nanomaterials for efficient photocatalytic H2 production,dye degradation and photoluminescence studies

The photocatalytic hydrogen generation is a novel, eco-friendly and favourable method for production of green and clean energy using light energy. In this direction, we report low-temperature ionothermal method for the preparation of TiO₂ nanoparticles (NPs) using methoxy ethyl methyl imidazolium tris (pentafluoroethyl) trifluoro phosphate (MOEMINtf₂) as an ionic liquid (IL) at 120°C for 1 day. The synthesized nanomaterials were examined using different spectrochemical methods like UV-DRS, XRD, FT-IR, TEM, BET and TGA-DTA techniques. The mixed phase TiO₂ is obtained with 81.7% of anatase and 18.3% of rutile phase by the XRD studies, and average crystallite size is found to be ∼7 nm. The stretching of Ti-O bond (∼555 cm⁻¹) and few other bands related to ionic liquid were confirmed by FTIR spectrum. The band gap energy was observed to be ∼3.38 eV by UV-DRS analysis. TEM images reveal spherical shape with an average particles size of about 10 nm. Photocatalytic H₂ generation was carried out using TiO₂ NPs and observed the generation of 553 μmol h⁻¹ g⁻¹ via water splitting reaction. Furthermore, the prepared TiO₂ NPs employed for the photocatalytic degradation of methylene blue dye (84.54%), and photoluminescence studies confirms the obtained material can be used in optoelectronic applications with green emission.     

Synthesis of polyaniline/MWCNTs by interfacial polymerization for superior hybrid supercapacitance performance

Polyaniline/Multiwalled carbon nanotubes (PANI/MWCNTs) nanocomposite was prepared via liquid-liquid interfacial polymerization method. The morphology studies of the nanocomposite using SEM and TEM techniques confirmed the presence of PANI as aggregates along with MWCNTs and X-ray diffraction studies indicated the presence of graphitic planes of MWCNTs along with PANI in semi-crystalline emeraldine salt form. The PANI/MWCNTs nanocomposite electrode exhibited specific capacitance (Cs) of 1551 F/g at a scan rate of 2 mV/s in aqueous 1 M H₂SO₄ in a potential window of 0–1.2 V. The material exhibited good cycle life with 95% capacitance retention in a life cycle test conducted at 5 A/g for 1000 cycles. Further, an asymmetric supercapacitor device (ASD) was fabricated using PANI/MWCNTs as positive and activated carbon as negative electrodes in aqueous 1 M H₂SO₄. The ASD exhibited a Cs of 142 F/g at a scan rate of 5 mV/s in a wide potential range of 0–1.6 V. The device offered high energy and power densities of 29 Wh/Kg and 7.3 kW/Kg respectively and also demonstrated an excellent cyclic stability by retaining 97% of its initial capacitance after 5000 cycles at high current density of 20 A/g.

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Graphical abstract Schematic representation of design of asymmetric supercapacitor device, its cycle performance and Ragone plot

     

Multiple token‐based neighbor discovery for directional sensor networks

Directional sensor networks (DSNs) can significantly improve the performance of a network by employing energy efficient communication protocols. Neighbor discovery is a vital part of medium access control (MAC) and routing protocol, which influences the establishment of communication between neighboring nodes. Neighbor discovery is a challenging task in DSNs due to the limited coverage provided by directional antennas. Furthermore, in these networks, communication can only take place when the beams of the directional antennas are pointed toward each other. In this article, we propose a novel multiple token‐based neighbor discovery (MuND) protocol, in which multiple tokens are transmitted based on an area exploration algorithm. The performance of the protocol is evaluated using the Cooja simulator. The simulation results reveal that the proposed MuND protocol achieves lower neighbor discovery latency, with a 100% neighbor discovery ratio, and has a relatively low communication overhead and low energy consumption.     

Scalable Models for Redundant Data Flow Analysis in Online Social Networks

Wireless Personal Communications - Sharing and reception of identical video contents amongst the users of various online social media applications induce enormous amount of redundant data traffic...     

Process variability in surface roughening of SU-8 by oxygen plasma

This study investigates variability in the topography of SU-8 photoresist subject to surface roughening by oxygen plasma treatment. Surface roughness (expressed as root mean square deviation from the mean) under the range of experimental conditions varied from 8 nm for an untreated baseline to as high as 472 nm. At 200 W RF-power and 200 mTorr chamber pressure, the mean surface roughness was 295 nm with standard deviation less than 10 nm across the specimen and 15 nm across the plasma chamber. The standard deviation in surface roughness at higher power and pressure combinations including 500 W and 800 mTorr was as high as 80 nm, with mean surface roughness less than 200 nm. Replicate runs under identical conditions revealed that run-to-run repeatability can be compromised by chamber conditions, evidenced by second runs having higher standard deviation by nearly 20 % over first runs without intermediate chamber cleaning.