Enhanced Photocatalytic Activity of Two-Pot-Synthesized BiFeO<Subscript>3</Subscript>–ZnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> Heterojunction Nanocomposite

BiFeO₃–ZnFe₂O₄ heterojunction nanocomposites have been produced by a chemical synthesis method using one- and two-pot approaches. X-ray diffraction patterns of as-calcined samples indicated formation of pure zinc ferrite (ZnFe₂O₄) and bismuth ferrite (BiFeO₃) phases, each retaining its crystal structure. Diffuse reflectance spectrometry was applied to calculate the optical bandgap of the photocatalysts, revealing values in the range from 2.03 eV to 2.17 eV, respectively. The maximum photodegradation of methylene blue of about 97% was achieved using two-pot-synthesized photocatalyst after 120 min of visible-light irradiation due to the higher probability of charge separation of photogenerated electron–hole pairs in the heterojunction structure. Photoluminescence spectra showed lower emission intensity of two-pot-synthesized photocatalyst, due to its lower recombination rate originating from greater charge separation.     

Efficient multisecret sharing scheme using new proposed computational security model

A multisecret sharing (MSS) is a method for sharing a set of secrets among some participants. They can recover each of these secrets without endangering the other secrets. Two kinds of security models have been proposed for MSS schemes. These models are categorized into 2 types. The first security model is unconditional security. This approach decreases the efficiency of MSS schemes. Therefore, the second type of security, which is more relaxed, appeared. This approach is called computational security. In this paper, with 2 examples, we will show that the current definition of computational security does not satisfy all of our expectations from a secure MSS scheme. In fact, in these examples, recovering a secret leaks information to the other secrets while these schemes are considered secure in view of the computational security. After determining the shortcomings of the current security definition, we propose a new definition for computational security and present an MSS scheme that enjoys rigorous proof of security in terms of the new definition. In addition, a complete comparison in terms of share size, number of public values, and required operations for recovering a secret between our scheme and previous schemes indicates that the presented scheme is efficient.     

On selection of forwarding nodes for long opportunistic routes

Opportunistic routing is a promising routing paradigm which increases the network throughput. It forces the sender’s neighbors, who successfully overheard the transmitted packet, to participate in the packet forwarding process as intermediate forwarding nodes. As a seminal opportunistic routing protocol, MORE combines network coding idea with opportunistic routing to eliminate the need for strict coordination among active forwarding nodes. In this paper, we show that MORE performance does not scale well with the route length, especially when the route length goes beyond two hops. Also, we found that MORE fails to establish a working opportunistic route in sparse networks. Clearly, the network throughput is directly influenced by both the quantity and quality of forwarding nodes, and their cooperation order. In this paper, we propose a new forwarder selection mechanism which considers the route length, link qualities, the distance from the source, and nodes density. It eliminates the occasional route disconnectivity happening in MORE and improves the quality of the established opportunistic routes. The simulation result indicates that our proposal always outperforms MORE when dealing with long opportunistic routes.

     

Principal component analysis-based predictive modeling and optimization of permanent deformation in asphalt pavement: elimination of correlated inputs and extrapolation in modeling

Structural and Multidisciplinary Optimization - Permanent deformation in asphalt pavement is a function of material properties, loading, environmental conditions, and structural design (e.g.,...     

Effects of tool wear on friction stir welded joints of Ti–6Al–4V alloy

Tool wear behaviour on microstructure and mechanical properties of friction stir welded zones of Ti–6Al–4V alloy was evaluated. SEM examination, EDS analysis and X-ray diffraction results indicated that severe wear of the tool is indicated by the presence of WC-Co particles in the stir zone at rotational speed of 630?rev?min^?1 and travel speed of 8?mm?min^?1. Micro-hardness, tensile tests and fractographical examinations also reflected that these particles make the material more brittle and reduce the mechanical strength by 40%. However at travel speed of 22?mm?min^?1, tool wear is less, hardness distribution is more uniform and enhanced ductility and strength is achieved.     

Rapid biologically one-step synthesis of stable bioactive silver nanoparticles using Osage orange (Maclura pomifera) leaf extract and their antimicrobial activities

Synthesis of nanoparticles by using natural products as reducing and stabilizing agents have been widely used in various fields especially medicine, primarily because of its lower cost, simplicity, and less toxic byproducts. In the present work, silver nanoparticles (Ag NPs) were rapidly synthesized from silver nitrate in a green one-step synthesis by the aqueous extracts of Osage orange (Maclura pomifera) leaf as a reducing and stabilizing agent simultaneously. The effects of pH, extract quantity, and silver salt concentration were investigated to determine the optimum conditions of green synthesis of Ag NPs. The synthesized Ag NPs were characterized by different techniques including UV–Visible (UV–Vis) absorption spectroscopy, X-ray diffraction (XRD), Fourier transform Infrared (FT-IR) Spectroscopy, and Transmission Electron Microscopy (TEM). The Ag NPs showed surface plasmon resonance centered at 415?nm. The XRD pattern and TEM analysis revealed spherical, stable, and uniform Ag NPs with the average particle size of about 12?nm. The FT-IR spectroscopy showed that mainly hydroxyl functional groups, as both the reducing and stabilizing agent are responsible for silver nanoparticles synthesis. The antimicrobial activity of the synthesized Ag NPs showed a significant microbicidal effect on all clinical isolates especially, Gram-negative bacteria and fungi. These results suggest that such stable and uniform Ag NPs can be synthesized rapidly and simply for clinical as well as pharmaceutical applications.     

Adaptive Switch Image-based Visual Servoing for Industrial Robots

International Journal of Control, Automation and Systems - In this paper, an adaptive switch image-based visual servoing (IBVS) controller for industrial robots is presented. The proposed control...     

Self-Assembled Perovskite Nanoislands on CH3NH3PbI3 Cuboid Single Crystals by Energetic Surface Engineering

Organometal perovskite single crystals have been recognized as a promising platform for high-performance optoelectronic devices, featuring high crystallinity and stability. However, a high trap density and structural nonuniformity at the surface have been major barriers to the progress of single crystal-based optoelectronic devices. Here, the formation of a unique nanoisland structure is reported at the surface of the facet-controlled cuboid MAPbI₃ (MA = CH₃NH₃⁺) single crystals through a cation interdiffusion process enabled by energetically vaporized CsI. The interdiffusion of mobile ions between the bulk and the surface is triggered by thermally activated CsI vapor, which reconstructs the surface that is rich in MA and CsI with reduced dangling bonds. Simultaneously, an array of Cs-Pb-rich nanoislands is constructed on the surface of the MAPbI₃ single crystals. This newly reconstructed nanoisland surface enhances the light absorbance over 50% and increases the charge carrier mobility from 56 to 93 cm² V⁻¹ s⁻¹. As confirmed by Kelvin probe force microscopy, the nanoislands form a gradient band bending that prevents recombination of excess carriers, and thus, enhances lateral carrier transport properties. This unique engineering of the single crystal surface provides a pathway towards developing high-quality perovskite single-crystal surface for optoelectronic applications.     

Mangrove-mediated synthesis of silver nanoparticles using native Avicennia marina plant extract from southern Iran

The development of eco-friendly and nontoxic processes for the synthesis of nanoparticles is one of the most important discussed issues in nanotechnology science. This study reports the green synthesis of silver nanoparticles (AgNPs) using aqueous extract of leaf, stem, and root of Avicennia marina, the native and dominant mangrove plant in southern Iran. Among the different plant parts, the extract of leaves yielded the maximum synthesis of AgNPs. Synthesized AgNPs were investigated using UV–visible spectrophotometry, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. Absorption spectrum in 420?nm confirmed the synthesis of AgNPs. TEM images revealed that the synthesized AgNPs had the same spherical morphology with a size range between 0 and 75?nm. The distribution size histogram indicated that the most frequent particles were in the range of 10–15?nm and the mean size of nanoparticles was 17.30?nm. The results of SEM image showed nanoparticles with a size range between 15 and 43?nm. XRD pattern indicated the crystalline nature of synthesized nanoparticles. EDS results confirmed the presence of elements like silver, carbon, chlorine, nitrogen, and oxygen in the nanoparticles produced from leaf extract. Silver had the maximum percentage of formation, 51.6%. FTIR indicated the presence of different functional groups such as amines, alcohol, alkanes, phenol, alkyl halides, and aromatic loops in the synthesis process. Green biosynthesis of AgNPs using aqueous extract of native A. marina appears rapid, reliable, nontoxic, and eco-friendly.