Synthesis and EMI shielding studies of polyaniline grafted conducting nanohybrid

Polyaniline (PANI) grafted conducting nanohybrids are successfully synthesized by emulsion graft polymerization. Maximum grafting of 644% is obtained on sepiolite at optimized concentrations and reaction conditions. The Fourier transform infrared (FT-IR) spectra of sepiolite grafted polyaniline (MS-g-PANI) nanohybrid revealed the presence of stretching vibrations of C=C bonds of polyaniline at 1580 and 1490 cm⁻¹ along with the characteristic peaks of sepiolite. Increased thermal stability of the nanohybrid is observed with the increase in polyaniline grafting. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to study the structural changes caused by grafting. A progressive increase in electrical conductivity is observed with the increase in grafting yield. Maximum electrical conductivity of 0.427 Scm⁻¹ is observed in the nanohybrid having 644% grafting. 24.2 dB (>99% attenuation) EMI shielding effectiveness has been exhibited by the developed nanohybrids in X-band frequency range.     

EFFECTS OF HALL CURRENT ON UNSTEADY FLOW OF A SECOND GRADE FLUID IN A ROTATING SYSTEM

Rotating flow of a second grade conducting fluid on an infinite oscillating plate is investigated when the fluid is permeated by a transverse magnetic field and the Hall effects are taken into account. It is once again found that an asymptotic solution exists in the presence of both suction and blowing at the plate. For fixed magnetic field parameter the boundary layer thickness increases with the increase in Hall parameter. The present analysis is more general than any previous investigations.     

Aluminum silicate fibers impregnated acrylonitrile butadiene rubber composites: Ablation,thermal transport/stability,and mechanical inspection

Variant concentrations of ceramic fibers (CerFs) were incorporated into acrylonitrile butadiene rubber (NBR) to fabricate elastomeric ablative composites for ultrahigh temperature applications. The CerFs introduction into the polymer matrix has enhanced the ablation resistance up to 59% and successfully reduced the backface temperature of the polymer composite up to 110^oC during the ultrahigh temperature ablation investigation. Thermal decomposition of the polymer composites was diminished up to 10% with increasing fiber concentration in the rubber matrix. Thermal conductivity was reduced equal to 63% while thermal impedance was enhanced up to 84% with the utmost fiber incorporation into the NBR matrix. The CerFs have adversely affected the mechanical properties of NBR matrix due to their brittle/inert nature and weak interface bonding with the host matrix. Scanning electron microscopy along with the energy dispersive x‐ray spectroscopy was used to examine the ablated specimens and the fiber dispersion within the host matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4392–4400, 2013     

Synthesis and characterizations of Ni0.8Zn0.2Fe2O4-MWCNTs composites for their application in sea bed logging

Sea bed logging is new technique for the detection of hydrocarbon reservoir. Magnitude of EM waves is important for the detection of deep target hydrocarbon reservoir below 4000 m from the sea floor. A new aluminium based EM transmitter is developed and NiZn (Ni_0.8Zn_0.2Fe₂O₄) ferrite with and with out multiwall carbon nano tubes (MWCNTs) polymer composites as magnetic feeders are used in a scaled tank. Nickel zinc ferrite plays an important role in many applications due to its best magnetic properties. Nanocrystalline NiZn (Ni_0.8Zn_0.2Fe₂O₄) ferrite and novel Ni_0.8Zn_0.2Fe₂O₄-MWCNTs composites were prepared by sol-gel route. The samples were sintered at 750-950 °C and were characterized by XRD, FESEM, HRTEM and Raman spectroscopy. Single phase of Ni_0.8Zn_0.2Fe₂O₄ having [3 1 1] major peak was obtained by sol-gel method at 750 °C and 950 °C. FESEM micrographs show that grain size increases with the increase of sintering temperature and ranges from 24 to 60 nm. FESEM and HRTEM results showed coating of Ni_0.8Zn_0.2Fe₂O₄ on MWCNTs and show better morphology at the sintering temperature of 750 °C. The magnetic properties measured from impedance vector network analyzer showed that sample (Ni_0.8Zn_0.2Fe₂O₄-MWCNTs) sintered at 750 °C have higher initial permeability (20.043), Q-factor (50.047), and low loss factor (0.0001) as compared Ni_0.8Zn_0.2Fe₂O₄-MWCNTs sintered at 950 °C. Due to better magnetic properties, Sample (Ni_0.8Zn_0.2Fe₂O₄-MWCNTs sintered at 750 °C) composites were used as magnetic feeders for the EM transmitter. It was found that magnitude of EM waves from EM transmitter increased up to 243% by using Ni_0.8Zn_0.2Fe₂O₄-MWCNTs polymer composites.     

Biosorption of copper(II) on prunus amygdalus shell: Characterization,biosorbent size analysis,kinetic, equilibrium and mechanistic studies

Deletion of Cu(II) from synthetic solution was investigated using ground Prunus Amygdalus shell (GPAS). FTIR revealed the probable functional groups for the binding of Cu(II). XRD revealed amorphous nature of the GPAS. SEM analysis furnished microscopic details of GPAS. GPAS size analysis was done using seven ASTM screens and three mean diameters, namely mass mean, volume mean and volume surface mean diameters. Kinetic study consisted of pseudo-first and pseudo-second order kinetics. Langmuir and Freundlich isotherms were used to elucidate the isotherm study of uptake of Cu(II) onto GPAS. Trend of Scatchard was used to verify the applicability of the Freundlich model, while D-R model helped to determine the nature of biosorption. A detailed analysis for rate controlling step was made. Various mean diameters were used to estimate the diffusion coefficient for the biosorption of Cu(II) onto GPAS.     

Experimental Visualization and Investigation of Multiphase Flow Regime Transitions in Two-Dimensional Trickle Bed Reactors

Different flow regimes are known to occur in the interaction of multiphase gas–liquid flows over packed beds of solid particles, such as those observed in trickle bed reactors (TBRs). There are four major flow regimes that are known to occur in downward cocurrent flow in TBRs, namely: trickle, pulse, bubble, and mist flow regimes. In this work, the focus is on macro-scale experimental visualizations and investigations of the flow regimes in a two-dimensional TBR.

Experimental observations are made to investigate the development and transition of these flow regimes over a wide range of liquid and gas velocities. Cylindrical particles are placed between two glass plates that are sealed on the sides, and water and air are injected over them using an injection manifold to simulate multiphase flow in a TBR. A diffused light emitting device (LED) light table is used to illuminate the experimental window, while real time images are obtained using a high-speed camera. Flow maps are reported depicting all four regimes and the transition regions between them. Transition regions occur where the characteristics of more than one flow regime coexist.

The 2D experimental results are then compared with the existing literature data of three dimensional results and found to be in good agreement. Emphasis is placed on the transition between the trickle and pulse regimes, since that is the most important mode of operation in industrial TBRs. It is observed that the change in diameters of the cylindrical particles in a two-dimensional TBR has little effect on the transition between the flow regimes when the porosity of the bed is kept constant.     

Design and fabrication of electro‐conductive polymer nanocomposites with mechanical and thermal resistance

The commencement of the industrial revolution paved the way for the fabrication of flexible polymers with high‐strength metalloceramics as novel materials of all kinds. Fabricating metal–ceramic/polymer conductive composites is one such dimension followed for the present research work making use of the properties of the three components. Electroless deposition, for permanent metallic coating, was performed to coat Al₂O₃ with metallic Cu followed by the inclusion of the Cu–Al₂O₃ filler into a poly(vinyl chloride) (PVC) matrix. X‐ray diffraction and energy‐dispersive X‐ray studies predicted a prominent growth of metallic Cu crystallites onto Al₂O₃ with an increased average size and variation in elemental composition, respectively, when compared to pristine Al₂O₃. Morphological behaviour via scanning electron microscopy also envisioned uniform Cu coating onto Al₂O₃ and a homogeneous dispersion throughout the polymer matrix. When incorporated into PVC, electrical conductivity analysis highlighted a distinct variation in composite phases from insulating (7.14 × 10^?16 S cm^?1) to semiconducting behaviour (8.33 × 10^?5 S cm^?1) as a function of Cu–Al₂O₃ filler. Mechanical behaviour (tensile strength, Young's modulus and elongation at break) and thermal properties of the prepared composites also indicated a substantial improvement in material strength with Cu–Al₂O₃ incorporation. The enhanced electrical conductivity along with improved thermomechanical status with significant filler–matrix interaction permits the potential usage of such novel composites in a range of state‐of‐the‐art semiconducting electronic devices. © 2018 Society of Chemical Industry     

Brain activation in restrained and unrestrained eaters: An fMRI study.

Restraint theory has been used to model the process that produces binge eating. However, there is no satisfactory explanation for the tendency of restrained eaters (REs) to engage in counterregulatory eating, an ostensible analogue of binge eating. Using functional magnetic resonance imaging (fMRI), the authors investigated brain activation of normal weight REs (N = 9) and unrestrained eaters (UREs; N = 10) when fasted and fed and viewing pictures of highly and moderately palatable foods and neutral objects. When fasted and viewing highly palatable foods, UREs showed widespread bilateral activation in areas associated with hunger and motivation, whereas REs showed activation only in the cerebellum, an area previously implicated in low-level processing of appetitive stimuli. When fed and viewing high palatability foods, UREs showed activation in areas related to satiation and memory, whereas REs showed activation in areas implicated in desire, expectation of reward, and goal-defined behavior. These findings parallel those from behavioral research. The authors propose that the counterintuitive findings from preload studies and the present study are due to the fact that REs are less hungry than UREs when fasted and find palatable food more appealing than UREs when fed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the influence of heat transfer in peristalsis with variable viscosity

This study concentrates on the heat transfer characteristics and endoscope effects for peristaltic flow of a third order fluid. Two models of variable viscosity are chosen. Both perturbation and numerical solutions are obtained in each case. A comparative study is also made between the two solutions. The importance of pertinent flow parameters entering into the flow modeling is discussed.     

A circularity measurement toolkit for manufacturing SMEs

The development and adoption of the concept of circular economy in the last two decades have been remarkable. However, despite its widespread adoption, little progress has been made regarding its measurement, especially in manufacturing SMEs. This paper, therefore, proposes a Circularity Measurement Toolkit (CMT) which enables the assessment of the degree of circularity in manufacturing SMEs. A conceptual CMT framework, which provided the basis for the proposed tool and that defined the different types of circular practices and a classification or levels of circularity was developed from an extensive literature reviewed. To ensure the structure's accuracy of the proposed CMT in terms of requirements to be measured, the monitoring process and actions involved, the tool was verified through a Delphi-study. Furthermore, its practicality was validated through a case study approach in a manufacturing SME. This paper contributes by filling a gap in the CE measurement field through the proposal of the CMT. Besides providing an evaluation of the degree of circularity in the practices of manufacturing SMEs, companies can also employ the proposed CMT to identify corrective actions or future efforts for the adoption of CE practices.