Corrosion protection behaviour of sol–gel derived N,N-dimethylthiourea doped 3-glycidoxypropyltrimethoxysilane on aluminium

The present work describes the anticorrosion features of inhibitor doped sol–gel coating on Al metal. Sol–gel coatings were prepared by using 3-glycidoxypropyltrimethoxysilane (GPTMS) as parent precursor. In order to improve the corrosion resistance property of coating, N,N-dimethylthiourea was added into the sol–gel matrix. The corrosion inhibitor doped sol–gel coating on metal was characterized by Fourier transform infrared analysis (FTIR) and scanning electron microscope (SEM). Inhibition effect of N,N-dimethylthiourea doped GPTMS coating on Al substrates in 1% NaCl solution was investigated using electrochemical impedance (EIS) and polarization studies. EIS results showed that the corrosion resistance of sol–gel coating significantly improved upon addition of N,N-dimethylthiourea. The study had outlined the nuances of doping an organic inhibitor to enhance the protection ability of sol–gel coating on Al metal.     

Detection of quadratic phase coupling from human EEG signals using higher order statistics and spectra

Interactions among neural signals in different frequency components have become a focus of strong interest in biomedical signal processing. The bispectrum is a method to detect the presence of quadratic phase coupling (QPC) between different frequency bands in a signal. The traditional way to quantify phase coupling is by means of the bicoherence index (BCI), which is essentially a normalized bispectrum. The main disadvantage of the BCI is that the determination of significant QPC becomes compromised with noise. To mitigate this problem, a statistical approach that combines the bispectrum with an improved surrogate data method to determine the statistical significance of the phase coupling is introduced. The method was first tested on two simulation examples. It was then applied to the human EEG signal that has been recorded from the scalp using international 10–20 electrodes system. The frequency domain method, based on normalized spectrum and bispectrum, describes frequency interactions associated with nonlinearities occurring in the observed EEG.     

Synthesis of magnetic nanofibers using femtosecond laser material processing in air

In this study, we report formation of weblike fibrous nanostructure and nanoparticles of magnetic neodymium-iron-boron (NdFeB) via femtosecond laser radiation at MHz pulse repetition frequency in air at atmospheric pressure. Scanning electron microscopy (SEM) analysis revealed that the nanostructure is formed due to aggregation of polycrystalline nanoparticles of the respective constituent materials. The nanofibers diameter varies between 30 and 70 nm and they are mixed with nanoparticles. The effect of pulse to pulse separation rate on the size of the magnetic fibrous structure and the magnetic strength was reported. X-ray diffraction (XRD) analysis revealed metallic and oxide phases in the nanostructure. The growth of magnetic nanostructure is highly recommended for the applications of magnetic devices like biosensors and the results suggest that the pulsed-laser method is a promising technique for growing nanocrystalline magnetic nanofibers and nanoparticles for biomedical applications.     

Sol-gel synthesis and antibacterial study on BC/ZnO/TiO2 nanocomposite treated by DC glow discharge plasma

Nanocomposite material of bamboo charcoal (BC), zinc oxide (ZnO), and titanium dioxide (TiO₂) has prepared via sol–gel method. The synthesized nanocomposite surface was modified by a DC glow discharge plasma treatment. Characterization methods such as BET, SEM, XRD, FTIR, UV, and EDAX are utilized to examine the presence of all the three materials and their combination structure. The combined and plasma-modified surface structure of the bamboo charcoal/zinc oxide/titanium dioxide (BC/ZnO/TiO₂) nanocomposite has shown by microscopic images in step by step. The phase structure of the prepared nanocomposite has been identified by X-ray diffraction and the crystalline size of the composite falls between 20 and 30 nm. The antibacterial behavior of the prepared nanocomposite was assessed through disk diffusion plate method and best antibacterial performance was observed. The metal oxides and plasma treatment increased the property of the synthesized nanocomposite and also the results gave extended results compared to BC/ZnO and BC/TiO₂ in all formats.     

High performance electrospun PVdF‐HFP/SiO2 nanocomposite membrane electrolyte for Li‐ion capacitors

Electrospun poly[(vinylidene fluoride)‐co ‐hexafluoropropylene]/silica (PVdF‐HFP/SiO₂) nanocomposite polymer membranes (esCPMs) were prepared by incorporating different weight percentages of SiO₂ nanoparticles onto electrospun PVdF‐HFP by electrospinning technique. The surface morphology of electrospun PVdF‐HFP nanocomposite membranes was characterized by scanning electron microscopy. The effect of SiO₂ nanoparticles incorporation onto electrospun PVdF‐HFP polymer membranes (esPMs) has been studied by XRD, DSC, TGA, and tensile analysis. The electrospun PVdF‐HFP/SiO₂ based nanocomposite membrane electrolytes (esCPMEs) were prepared by soaking the corresponding esCPMs into 1 M LiPF₆ in EC:DMC (1:1 vol/vol %). The ionic conductivity of the esCPMEs was studied by AC‐impedance studies and it was found that the incorporation of SiO₂ nanoparticles into PVdF‐HFP membrane has improved the ionic conductivity from 1.320 × 10^?3 S cm^?1 to 2.259 × 10^?3 S cm^?1. The electrochemical stability of the esCPME was studied by linear sweep voltammetry studies and it was found to be 2.87 V. Finally, a prototype LiCo_0.2Mn_1.8O₄//C Li‐ion capacitor (LIC) cell was fabricated with esCPME, which delivered a discharge capacitance of 128 F g^?1 at the current density of 1 A g^?1 and retained 86% of its discharge capacitance even after 10,000 cycles. These results demonstrated that the esCPMEs could be used as promising polymer membrane electrolyte for LICs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45177.     

A subtree-based approach to failure detection and protection for multicast in SDN

Software-defined networking (SDN) has received tremendous attention from both industry and academia. The centralized control plane in SDN has a global view of the network and can be used to provide more effective solutions for complex problems, such as traffic engineering. This study is motivated by recent advancement in SDN and increasing popularity of multicasting applications. We propose a technique to increase the resiliency of multicasting in SDN based on the subtree protection mechanism. Multicasting is a group communication technology, which uses the network infrastructure efficiently by sending the data only once from one or multiple sources to a group of receivers that share a common path. Multicasting applications, e.g., live video streaming and video conferencing, become popular, but they are delay-sensitive applications. Failures in an ongoing multicast session can cause packet losses and delay, which can significantly affect quality of service (QoS). In this study, we adapt a subtree-based technique to protect a multicast tree constructed for OpenFlow switches in SDN. The proposed algorithm can detect link or node failures from a multicast tree and then determines which part of the multicast tree requires changes in the flow table to recover from the failure. With a centralized controller in SDN, the backup paths can be created much more effectively in comparison to the signaling approach used in traditional multiprotocol label switching (MPLS) networks for backup paths, which makes the subtree-based protection mechanism feasible. We also implement a prototype of the algorithm in the POX controller and measure its performance by emulating failures in different tree topologies in Mininet.