Conducting polymer coated textile based multilayered shields for suppression of microwave radiations in 8.2–12.4 GHz range

Polypyrrole (PPY) based conducting textiles were prepared by in situ polymerization of pyrrole over cotton fabric. The SEM micrographs show smooth and uniform coating of PPY over fabric with only few loose dendrites. The elemental analysis and XRD patterns revealed the presence of iron whereas magnetization measurement shows ferromagnetic signature with well defined hysteresis loop and saturation magnetization (Ms) of 0.3 emu/g. The good antistatic property and rapid static charge dissipability was reflected by decay profile with decay time of only 0.16 sec. In addition, the microwave absorption studies of multilayered shields; made up of these conducting fabrics; show absorption dominated total shielding effectiveness (SE_T) value of ?43.9 dB (i.e. >99.99% attenuation) which can be attributed to the better impedance matching, high microwave conductivity, shallow skin depth, and multiple scattering of incident electromagnetic radiation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thermomechanically stable dielectric composites based on poly(ether ketone) and BaTiO3 with improved electromagnetic shielding properties in X‐band

High‐performance barium titanate (BaTiO₃) filled poly(ether ketone) (PEK) composites were prepared by melt compounding with an aim to investigate the effect of BaTiO₃ on thermal, thermomechanical, dielectric, and electromagnetic interference shielding behavior of PEK. The content of BaTiO₃ in the PEK matrix was varied from 0 to 18 vol %. Scanning electron microscopy studies shows that BaTiO₃ particles were uniformly distributed in the PEK matrix up to 13 vol % loading followed by the formation of agglomerates at higher loading (18 vol %). Rockwell hardness increased up to 13 vol % loading followed by a decrease at 18 vol % loading. Dynamic mechanical analysis revealed that storage modulus increases with increase in BaTiO₃ loading with a maximum value of 3192 MPa at 13 vol % compared to 2099 MPa for neat PEK. Dielectric constant of composites measured in the frequency range of 8.2–12.4 GHz increased approximately three times upon incorporation of 18 vol % of BaTiO₃. This increment in dielectric constant is reflected in improved electromagnetic shielding properties as loading of dielectric filler (BaTiO₃) increases. Total shielding effectiveness of ?11 dB (～92% attenuation) at loading of 18 vol % BaTiO₃ justifies the use of these composites for suppression of EM radiations. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46413.     

Poly(vinyl chloride)–Acacia bark flour composite: Effect of particle size and filler content on mechanical,thermal, and morphological characteristics

This article describes the effect of filler [obtained from bark of Acacia (Babool)] content and its particle size (ranging from 100 to 150 μm and <50 μm) on the properties of poly(vinyl chloride) (PVC) composites. Bark of the fast‐growing species Acacia was used as powder for making PVC composites, which may find applications as a substitute to high‐cost wood and to avoid deforestation. A two‐roll mill was used for mixing varying amounts of bark flour with PVC formulation. Samples for testing were prepared by compression molding. Tensile strength and percentage of elongation at break decreased, whereas modulus increased with an increasing amount of bark flour. A significant increase in storage modulus (E′) was observed upon incorporation of filler. Improvement in properties was significant in the presence of filler, having a particle size <50 μm as compared to filler, having a particle size ranging from 100 to 150 μm. Morphological characterization was conducted by using scanning electron microscopy. A uniform dispersion of filler was observed in PVC matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Engulfment Behavior of Inclusions in High-Carbon Steel: Theoretical and Experimental Investigation

Previous studies on inclusions behavior at the front of the solidifying steel shell have mainly focused on low-carbon steels. However, with the increasing applications of high-carbon steel in recent years because of its superior properties, it is crucial to understand this behavior in high-carbon steel. Most of the high-carbon steels are deoxidized by silicon, calcium treated, and contain higher sulfur percentage. Also, higher carbon content has a determining influence on the viscosity and surface tension, which will affect the inclusion behavior. In this study, we have investigated the engulfment behaviors of inclusions in front of the solidifying interface in high-carbon steels using concentric solidification method. The critical velocity of the growing shell, at which the particle is engulfed in the solidifying shell, instead of being pushed by this shell, was determined. The inclusion identified in this study is a bi-component form of CaO-SiO₂-based oxide and CaS. It was revealed that engulfment behavior is strongly affected by convection of liquid steel that originates from carbon push out in high-carbon steels. This study provides new crucial information to produce high-carbon steel with fewer inclusions, which opens new application pathways for this emerging grade of steel.     

Influence of self-doped poly(aniline-co-4-amino-3-hydroxy-naphthalene-1-sulfonic acid) on corrosion inhibition behaviour of iron in acidic medium

This paper presents the corrosion inhibition performance of soluble self-doped copolymers of aniline and 4-amino-3-hydroxy-naphthalene-1-sulfonic acid synthesized by chemical oxidative polymerization method. The corrosion inhibition behaviour of the copolymers in 1.0 M HCl has been evaluated using Tafel Extrapolation method and electrochemical impedance spectroscopy (EIS) which was also used to propose the mechanism besides surface morphology. The results showed that the copolymer film exhibited the significant shifting in the corrosion potential and greater charge transfer resistance. The corrosion inhibition efficiency was found to increase from 50% to 90% by increasing the concentration of copolymer from 10 to 70 mg/l in HCl medium. Moreover, the copolymer showed the larger degree of surface coverage onto the iron surface, reflecting the higher inhibition for corrosion of the iron in highly acidic medium.     

Random Forest Learning Based Indoor Localization as an IoT Service for Smart Buildings

Wireless Personal Communications - More buildings are becoming smart day by day which play a key role in development of smart cities and Internet of Things is essential in the development of such...     

Characterization of Male and Female Jojoba Plants Employing Antioxidants,Lipid Peroxidation and Physiological Studies

Jojoba, [Simmondsia chinensis (Link) Schneider] is a commercially important dioecious, desert shrub which is mainly cultivated for liquid wax (oil) present in its seeds (40–60 %). The oil is being utilized by the cosmetic, pharmaceuticals, and other industries for certain formulations. In this study, gender based differences in biochemical and physiological parameters were examined in relation to natural drought conditions. The amount of protein, proline, cysteine, chlorophyll a and b, carotenoids and enzymatic activities were evaluated in leaves of male and female Jojoba genotypes. Significant differences between genders were found which was attributed to higher drought tolerance of males than females. Males showed higher contents of protein (113.05 ± 0.88 mg g^?1 FW), proline (95.13 ± 2.33 µmol g^?1 FW), cysteine (42.47 ± 2.69 µmol g^?1 FW) than females (proteins: 70.77 ± 0.52 mg g^?1 FW, proline: 66.61 ± 1.75 µmol g^?1 FW, cysteine: 17.84 ± 3.00 µmol g^?1 FW). Malondialdehyde (MDA) content was lower in male genotypes (18.29 ± 0.53 µmol g^?1 FW) than female genotypes (23.02 ± 0.70 µmol g^?1 FW). Higher activities of catalase (CAT) [0.088 ± 0.005 nkat mg^?1 protein], guaiacol peroxidase (GPX) [0.006 ± 0.001 nkat mg^?1 protein], glutathione reductase (GR) [9.02 ± 0.04 nkat mg^?1 protein], ascorbate peroxidase (APX) [4.28 ± 0.08 nkat mg^?1 protein] and superoxide dismutase (SOD) [151.75 ± 3.58 nkat mg^?1 protein] were found in males compared to females [CAT: 0.007 ± 00 nkat mg^?1 protein, GPX: 0.003 ± 00 nkat mg^?1 protein, GR: 6.40 ± 0.06 nkat mg^?1 protein, APX: 3.08 ± 0.06 nkat mg^?1 protein, SOD: 52.51 ± 1.73 nkat mg^?1 protein]. Chlorophyll b content was also higher in males than females.     

The Effect of Particle Size Distributions on the Microstructural Evolution During Sintering

Microstructural evolution and sintering behavior of powder compacts composed of spherical particles with different particle size distributions (PSDs) were simulated using a kinetic Monte Carlo model of solid‐state sintering. Compacts of monosized particles, normal PSDs with fixed mean particle radii and a range of standard deviations, and log‐normal PSDs with fixed mode and a range of skewness values were studied. Densification rate and final relative density were found to be inversely proportional to initial PSD width. Grain growth was faster during the early stages of sintering for broad PSDs, but the final grain sizes were smaller. These behaviors are explained by the smallest grains in the broader PSDs being consumed very quickly by larger neighboring grains. The elimination of the small grains reduces both the total number of necks and the neck area between particles, which in turn reduces the regions where vacancies can be annihilated, leading to slower densification rates. The loss of neck area causes grain growth by surface diffusion to become the dominant microstructural evolution mechanism, leading to poor densification. Finally, pore size was shown to increase with the width of PSDs, which also contributes to the lower densification rates.     

Simulation of Grain Growth and Pore Migration in a Thermal Gradient

The Potts Monte Carlo simulation was used to simulate microstructural evolution in uranium dioxide fuel rods. During service, grain growth, pore migration, and thermal segregation of the pores and UO₂ occur in the rods in a thermal gradient. In this investigation, we developed a model which simulates simultaneous grain growth, pore migration, and thermal segregation of the pores and UO₂ in a temperature gradient. Grain growth in a thermal gradient was simulated using the Monte Carlo Potts model technique developed by Anderson, Srolovitz, and co-workers. Pore migration was simulated using conserved dynamics with minimum-energy exchanges at a finite temperature. A temperature gradient was introduced into the model via interfacial mobility gradient. Finally, thermal segregation of the pores and UO₂ was achieved by introducing a heat of migration term, Δ E _t, which biased the motion of porosity to the high-temperature region. The development of this model is described and the incorporation of the proper physics of pore migration and thermal segregation is discussed.