Structural investigation and giant dielectric response of CaCu<Subscript>3</Subscript>Ti<Subscript>4</Subscript>O<Subscript>12</Subscript> ceramic by Nd/Zr co-doping for energy storage applications

High performance dielectric materials are highly required for practical application for energy storage technologies. In this work, high-k pristine and modified calcium copper titanate having nominal formula Ca_0.95Nd_0.05Cu₃Ti_4?xZr_xO₁₂ (x?=?0.01, 0.03 & 0.10) were synthesized and characterized for structural and dielectric properties. Single phase formation of the synthesized compositions was confirmed by X-ray diffraction patterns and further analysed using Rietveld refinement technique. Phase purity of the synthesized ceramics was further confirmed by Energy-dispersive X-ray Spectroscopy (EDX) analysis. SEM images demonstrated that grain size of the modified CCTO ceramics was controlled by Zr⁴⁺ ions due to solute drag effect. Impedance spectroscopy was employed to understand the grain, grain boundaries and electrode contribution to the dielectric response. Nyquist plots were fitted with a 2R-CPE model which confirms the non-ideality of the system. Substitution of specific concentration of Nd and Zr improved the dielectric properties of high dielectric permittivity (ε′ ~?16,902) and minimal tanδ (≤?0.10) over a wide frequency range. The giant ε′ of the investigated system was attributed to internal barrier layer capacitance (IBLC) effect and reduced tanδ accredited to enhanced grain boundaries resistance due to substitution of Zr⁴⁺ ions at Ti⁴⁺ site.     

Cage like ordered carboxylic acid functionalized mesoporous silica with enlarged pores for enzyme adsorption

Cubic FDU-12 type mesoporous silicas with enlarged pores and carboxylic acid (–COOH) functionality in the pore channels (denoted as LP-FTC-x) are synthesized using tetraethyl orthosilicate (TEOS) and carboxyethylsilanetriol sodium salt (CES) as silica sources, Pluronic F127 triblock copolymer as template, and trimethylbenzene (TMB) as pore expander, and utilized them as supports for enzyme immobilization. When the –COOH content is increased from 0 to 30%, the pore size of LP-FTC-x decreases from 23.6 to 11.1 nm, and its particle size decreases from around 2 μm to 600–800 nm. The material exhibits a high papain adsorption capacity (895 mg g^?1) with a low leaching rate at pH 8.2 due to the well-defined surface chemistry in the pore channel. The adsorption kinetics and isotherms follow the pseudo-second-order model and the Langmuir isotherm model, respectively. The excellent structural properties of LP-FTC-x are also advantageous for enhancement in stability of enzyme toward the temperature, solution pH, and incubation time variations.     

Ion implantation effects of negative oxygen on copper nanowires

Copper nanowires of diameter 80 nm were synthesized in polycarbonate membrane using template technique. Samples were then implanted with 160 keV O^?1 ion beam with varying particle fluence of 1?×?10¹², 5?×?10¹² and 1?×?10¹³ ions/cm². The SRIM (Stopping and range of ions in matter) software was used to study the processes involved. Compositional analysis confirms implantation of oxygen ions and the stoichiometry of Cu:O was found to be 6:1 by weight % when implanted at 1?×?10¹³ ions/cm². Scanning electron microscopy reveals no changes in morphology of nanowires on implantation. X-ray diffraction analysis showed no shifting in the ‘2θ’ position of diffraction peaks however some new diffraction peaks of oxygen were seen. Implantation with oxygen ion led to the increased crystallite size and reduced strain. The conductivity of the nanowires was found to increase linearly with the ion fluence presenting constructive effect of negative ion implantation on copper nanowires.     

Engineering Catalytically Active Sites by Sculpting Artificial Edges on MoS2 Basal Plane for Dinitrogen Reduction at a Low Overpotential

Engineering catalytically active sites have been a challenge so far and often relies on optimization of synthesis routes, which can at most provide quantitative enhancement of active facets, however, cannot provide control over choosing orientation, geometry and spatial distribution of the active sites. Artificially sculpting catalytically active sites via laser-etching technique can provide a new prospect in this field and offer a new species of nanocatalyst for achieving superior selectivity and attaining maximum yield via absolute control over defining their location and geometry of every active site at a nanoscale precision. In this work, a controlled protocol of artificial surface engineering is shown by focused laser irradiation on pristine MoS₂ flakes, which are confirmed as catalytic sites by electrodeposition of AuNPs. The preferential Au deposited catalytic sites are found to be electrochemically active for nitrogen adsorption and its subsequent reduction due to the S-vacancies rather than Mo-vacancy, as advocated by DFT analysis. The catalytic performance of Au-NR/MoS₂ shows a high yield rate of ammonia (11.43 × 10⁻⁸ mol s⁻¹ cm⁻²) at a potential as low as −0.1 V versus RHE and a notable Faradaic efficiency of 13.79% during the electrochemical nitrogen reduction in 0.1 m HCl.     

Triboelectric nanogenerator based on polyaniline nanorods incorporated PDMS composites through a facile synthetic route

Journal of Materials Science: Materials in Electronics - Triboelectric nanogenerators (TENG) open up a new technique for developing green power sources through effective harvesting and conversion...     

Design and development of virtual instrument for fault diagnosis in fractal antenna array

This paper deals with the development of a virtual instrument for fault diagnosis in fractal antenna array using Lab‐VIEW software. Faults in antenna array are considered on the basis of the radiation pattern. In this study, theta and gain values of radiation patterns for each fault are used in Lab‐VIEW for curve fitting. An artificial neural network (ANN) has been developed for fitted data points using the Leavenberg Marquard algorithm in MATLAB software and mean square error (MSE) is minimized. The designed ANN model has been embedded in the virtual instrument. The proposed virtual instrument system gets test patterns as input and generates output for several faults present in antenna array. Simulated and measured results of the fractal antenna array are validated experimentally. This virtual instrument model has not been developed for fractal antenna array so far.     

Towards a Light Weight Routing Security in IoT Using Non-cooperative Game Models and Dempster–Shaffer Theory

Wireless Personal Communications - The internet of things (IoT) has become an emerging technology owing to the rapidly increasing number of devices and their connectivity to the internet. Routing...     

Big Data Framework for Zero-Day Malware Detection

Malware has already been recognized as one of the most dominant cyber threats on the Internet today. It is growing exponentially in terms of volume, variety, and velocity, and thus overwhelms the traditional approaches used for malware detection and classification. Moreover, with the advent of Internet of Things, there is a huge growth in the volume of digital devices and in such scenario, malicious binaries are bound to grow even faster making it a big data problem. To analyze and detect unknown malware on a large scale, security analysts need to make use of machine learning algorithms along with big data technologies. These technologies help them to deal with current threat landscape consisting of complex and large flux of malicious binaries. This paper proposes the design of a scalable architecture built on the top of Apache Spark which uses its scalable machine learning library (MLlib) for detecting zero-day malware. The proposed platform is tested and evaluated on a dataset comprising of 0.2 million files consisting of 0.05 million clean files and 0.15 million malicious binaries covering a large number of malware families over a period of 7 years starting from 2010.     

Temperature-dependent short-channel parameters of FinFETs

The remarkable development and continual proliferation of research in the nanotechnology field have led to improvement in the efficiency of elementary devices. To improve their performance, the parameters of such devices can be scaled down while optimizing their characteristics. However, this simultaneously results in degraded switching characteristics and the appearance of short-channel effects. Multigate-based fin-shaped field-effect transistors (FinFETs) represent a new option to address all these problems. However, thermal failure of FinFET devices under nominal operating conditions is an important issue in the design and implementation of high-speed semiconductor devices. It is also seen that bulk FinFETs exhibit better thermal performance compared with silicon-on-insulator FinFETs. In the work presented herein, various FinFET characteristics including the subthreshold swing, drain-induced barrier lowering, threshold voltage, and drain current were investigated as functions of temperature. The (effective) channel length is larger than the physical gate length (in off-state) due to the undoped underlap regions. This paper also discusses the effects of drain, source, and gate overlap.