A selective and sensitive electrochemical determination of catechol based on reduced graphene oxide decorated β-cyclodextrin nanosheet modified glassy carbon electrode

In the present work, we have demonstrated the fabrication of catechol (CC) biosensor based on reduced graphene oxide (rGO) decorated β-cyclodextrin (β-CD) nanosheet immobilized using nafion (Nf) on modified GCE (glassy carbon electrode). The rGO/β-CD nanocomposite is synthesized through sonochemical approach and characterized by spectral (UV–visible, FT-IR, and Raman), analytical techniques (XRD, SEM, SAED, mapping analysis, HR-TEM and EDX) and electrochemical studies. The rGO/β-CD/Nf modified GCE exhibit a prominent electrocatalytic activity towards selective and sensitive determination of CC than other modified electrodes. Besides, the electrochemical sensor was revealed an excellent current response for the determination of CC with wide linear ranges (0.1–0.7 µM), high sensitivity (19.1 µA µM^-1cm²) and very low detection limit (LOD) 0.0012 µM. The excellent reproducibility, selectivity, stability, and sensitivity results are achieved for the determination of CC.     

Synthesis and characterization of MWCNT/TiO2 /Au nanocomposite for photocatalytic and antimicrobial activity.

A novel combination of titanium oxide (TiO₂)/gold (Au)/multiwalled carbon nanotubes (MWCNTs) nanocomposite (NC) was synthesised by sol– gel method. MWCNT functionalisation by modified Hummers method. TiO₂ /Au nanoparticles (NPs) were synthesised by biological method using Terminalia chebula bark extract. MWCNT/TiO₂ /Au NC samples were characterised by X‐ray diffraction, ultraviolet–visible–diffuse reflectance spectra, microRaman, scanning electron microscopy and high‐resolution‐transmission electron microscopy analyses. The photocatalytic performance of the obtained for NC toward the decomposition of congo‐red and the antimicrobial activity for inhibition of Gram positive (Bacillus subtilis, Streptococcus pneumonia and Staphylococcus aureus), Gram negative (Shigella dysenderiae, Proteus vulgaris and Klebsiella pneumonia) and fungal strains have been evaluated and the results are compared with positive control ampicillin. The metal and metal–oxide NPs have a lower sorption capacity. The herbicidal bond to the tested CNTs by the combination of electron donor–acceptor interactions and hydrogen bonds. In particular, the dispersion of NC and control of sodium borohydride, it has more efficient effect on the photodegradation and antibacterial activity of positive control of ampicillin. The NC material has exhibited maximum photodegradation and antibacterial activity results of zone of inhibition when compared with control samples.Inspec keywords: nanocomposites, nanoparticles, titanium compounds, gold, multi‐wall carbon nanotubes, nanofabrication, sol‐gel processing, catalysis, photodissociation, antibacterial activity, microorganisms, X‐ray diffraction, reflectivity, Raman spectra, ultraviolet spectra, visible spectra, hydrogen bonds, scanning electron microscopy, transmission electron microscopy, dyes, sorption, nanobiotechnologyOther keywords: titanium oxide‐gold‐multiwalled carbon nanotubes nanocomposite, sol‐gel method, photocatalytic activity, antimicrobial activity, MWCNT functionalisation, modified Hummers method, nanoparticles, biological method, Terminalia chebula bark extract, X‐ray diffraction, ultraviolet‐visible‐diffuse reflectance spectra, microRaman spectra, scanning electron microscopy, high‐resolution‐transmission electron microscopy, congo‐red decomposition, Gram positive bacteria, Bacillus subtilis, Streptococcus pneumonia, Staphylococcus aureus, Shigella dysenderiae, Proteus vulgaris, Klebsiella pneumonia, fungal strains, Gram negative bacteria, sorption capacity, herbicidal bond, electron donor‐acceptor interactions, hydrogen bonds, sodium borohydride, photodegradation, metal‐oxide nanoparticles, C‐TiO₂ ‐Au     

New high permittivity and low loss ceramics in the BaO–TiO2–Nb2O5 composition

New dielectric ceramics with formula BaTi3Nb4O17 and Ba6Ti14Nb2O39 have been prepared and characterized. BaTi3Nb4O17 was densified to 92% of TD after firing at 1310 °C for 4 h. However, Ba6Ti14Nb2O39 fired under optimized conditions (1260 °C for 4 h) showed only 85% TD together with secondary phase. The crystal system of both of the compositions is orthorhombic. The BaTi3Nb4O17 has r56, Qu2100 (at 4.402 GHz), f+86 p.p.m. K-1 and Ba6Ti14Nb2O39 as r50, Qu650 (4.359 GHz) and f+165 p.p.m. K-1. © 1998 Kluwer Academic Publishers     

Bacterial degradation of naphtha and its influence on corrosion

The degradation problem of naphtha arises since hydrocarbon acts as an excellent food source for a wide variety of microorganisms. Microbial activity leads to unacceptable level of turbidity, corrosion of pipeline and souring of stored product. In the present study, biodegradation of naphtha in the storage tank and its influence on corrosion was studied. The corrosion studies were carried out by gravimetric method. Uniform corrosion was observed from the weight loss coupons in naphtha (0.024 mm/yr) whereas in presence of naphtha with water, blisters (1.2052 mm/yr) were noticed. The naphtha degradation by microbes was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). IR study reveals the formation of primary alcohol during degradation process. It was found that microbes degrade (CH₂CH₂)_n to RCH₃. Iron bacteria, manganese oxidizing bacteria, acid producers, and heterotrophic bacteria were enumerated and identified in the pipeline. SRB could not be noticed. Since water stratifies in the pipeline, the naphtha-degraded product may adsorb on pipeline, which would enhance the rate of microbial corrosion. On the basis of degradation and corrosion data, a hypothesis for microbial corrosion has been proposed.     

PTFE-SWNT composite for microwave absorption application

The Polytetrafluoroethylene-single walled carbon nanotube (PTFE-SWNT) composites are prepared and its dielectric properties are investigated as a function of SWNT loading both at 1 MHz and microwave frequencies. The relative permittivity and the conductivity increases with carbon nanotube loading. The addition of 0.02-volume fraction of SWNT increases the relative permittivity of the polymer from 2.1 to 7.5 × 10⁶ and the conductivity from 4.887 × 10^− 9 to 8.52 × 10^− 3 S/cm at 1 MHz. As the volume fraction of SWNT increases from 0.01 to 0.05 the relative permittivity of the PTFE-SWNT composite increases from 4 to 6.6 at X-band (8-12 GHz) and the power attenuation coefficient varies from 9.5 to 17 dB/mm.     

A new group of microwave dielectric ceramics in the RE(Ti0.5W0.5)O4 [RE=Pr, Nd, Sm, Gd, Tb, Dy, and Y] system

RE(Ti_0.5W_0.5)O₄ [RE=Pr, Nd, Sm, Gd, Tb, Dy, and Y] ceramics have been prepared as single-phase materials by a conventional solid-state ceramic route. The ceramics have been characterized by X-ray diffraction and microwave methods. The RE(Ti_0.5W_0.5)O₄ ceramics showed an increase in cell volume and a corresponding decrease in density with ionic radius of RE³⁺ ions. The dielectric constant varies from 21 to 25, Q_u×f from 6000 to 11 000 GHz and _f from –5 to –22 ppm °C^–1. The microwave dielectric properties indicate that these materials are possible candidates for dielectric resonator as well as substrate applications in microwave integrated circuits.     

Broadband dual frequency microstrip antenna

A new dual port microstrip antenna geometry for dual frequency operation is presented. The structure consists of the intersection of two circles of the same radius with their centres displaced by a small fraction of the wavelength. This antenna provides wide impedance bandwidth and excellent isolation between its ports. The gain of the antenna is comparable to that of a standard circular microstrip antenna operating at the same resonant frequency. A theoretical analysis for calculating the resonant frequencies of the two ports is also presented     

Microwave Characteristics of Polyaniline Based Short Fiber Reinforced Chloroprene Rubber Composites

This report presents the microwave characteristics of conducting polymer composites (CPCs) based on chloroprene rubber with special reference to dielectric properties. CPCs based on polyaniline (PANI), polyaniline-coated short nylon fiber (PANI-N) and chloroprene rubber (CR) were prepared by mechanical mixing. The important properties like dielectric permittivity, loss tangent, conductivity, and dielectric heating coefficient were evaluated and compared. It was found that PANI/CR composites had very good dielectric properties in the microwave range. The addition of PANI-N improved the mechanical properties of the composites with reasonably good dielectric properties. The CPCs were also found to have good microwave absorption.     

Effect of oxygen enrichment on the performance,combustion, and emission of single cylinder stationary CI engine fueled with cardanol diesel blends

We investigated the effect of intake air enrichment on the performance, combustion, and emission characteristics of a single cylinder direct-injection stationary diesel engine fueled with non- edible alternative fuel, namely, cardanol — diesel — methanol blend (B20M10). The results were compared with baseline diesel operations under standard operating conditions. The bio-fuel blend B20M10 (20% cardanol, 10% Methanol, and 70% diesel) was used as fuel and the combustion, performance, and emission characteristics were investigated by oxygen enriching of intake air with 3, 5, and 7 percentage by weight. With the increase of intake air oxygen concentration, CO, HC, and smoke were found to be decreased. But BTE and NOx emission were considerably increased. The blended fuel B20M10 with 7% oxygen enrichment of intake air was compared with diesel operation. The results show a 0.5% lesser BTE, 28% more NOx emission at full load condition. There is not much variation of smoke emission to be noticed for this fuel combination compared to diesel.     

Z number improved reference ideal method-based decision-making process for enforcing cooperation during data dissemination in mobile ad hoc networks

In mobile ad hoc networks (MANETs), cooperative communication and resource constraint are the two important core characteristics essential to guarantee trusted data dissemination. The cooperative communication between mobile nodes depends on the trust rendered by them towards the process of reliable data routing. However, stringent resource constraints of mobile nodes such as energy, memory, communications, and computations result in the introduction of selfish and malicious node that completely degrades the network performance in different dimensions. In this paper, Z number improved reference ideal method (RIM)-based decision-making process (NIRIMDMP) is proposed with the merits of maximizing deviation method (MDM) and best–worst method (BWM) to ensure reliable data routing by modeling the cooperation degree in terms of Z number. This NIRIMDMP adopted Z number to represent the information reliability and handle the problem of inherent uncertainty during the process of evaluating each mobile node in the routing process. In specific, MDM and BWM are included into the proposed NIRIMDMP to determine comprehensive attribute weights based on the calculated objective and subjective weights that could be possible derived in routing. It extended the merits of classical RIM using Z numbers to confirm reliable ranking of mobile nodes, even when the optimal solution exists amid extreme values taken into consideration for assessing the mobile nodes during decision making. Simulation investigations of the proposed NIRIMDMP confirmed improved throughput and network lifetime with reduced control overhead, energy consumptions, and delay independent of the amount of malicious and non-cooperative nodes.