Preparation and characterization of biodegradable waterabsorbent PAN/SS nanocomposite

Polyacrylonitrile (PAN)/sodium silicate (SS) nanocomposite was prepared via nonconventional emulsion method using an in situ developed transition metal complex Cu(II)/glycine taking ammonium persulfate (APS) as initiator, with a novel motive of converting hydrophobic homopolymer PAN into hydrophilic nano material via nanotechnology by the inclusion of SS to the homopolymer. UV–visible spectral analysis was carried out which revealed various interactions between the in situ developed complex with other reaction components. The formation of the PAN/SS nanocomposite was confirmed by infrared spectra (IR). Furthermore, as evidenced by transmission electron microscopy (TEM), the composite so obtained was found to have nano scale structure. X‐ray diffraction (XRD) was carried out suggesting that the silicate layers were exfoliated during the polymerization process. An increase in the thermal stability for the developed nanocomposite was recorded by thermogravimetric analysis (TGA). Surprisingly, it was also found that the PAN/SS nanocomposite showed considerable amount of waterabsorbency and was biodegradable as tested by activated sludge and cultured media and further confirmed by scanning electron microscopy (SEM). POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Sol-gel auto-combustion synthesis of Ba–Sr hexaferrite ceramic powders

We report the mechanism involved in sol-gel auto-combustion synthesis of Ba–Sr-hexaferrite (Ba_1-xSr_xFe₁₂O₁₉; x = 0, 0.25, 0.5, 0.75 and 1, BSFO) ceramic powders through the analysis of the phases evolved during annealing of the as-synthesized powders, along with their structure and morphological studies. The XRD patterns of the as-synthesized samples indicate the formation of barium/strontium monoferrite ((Ba/Sr)Fe₂O₄) and maghemite (γ-Fe₂O₃) phases along with a minute amount of hematite (α-Fe₂O₃) phase. Annealing of these samples facilitates formation of BSFO phase through the solid state reaction between BaFe₂O₄ and γ-Fe₂O₃ phase. Interestingly, after annealing the samples with x = 0, 0.5 and 1, at 1000 °C for 2 h, we observed that phase pure Ba–Sr hexaferrite structure forms, but for samples with x = 0.25 and 0.75, high amount of hematite (α-Fe₂O₃) phase is observed, especially for x = 0.75. The reason associated with this could be the large difference between the ionic radii of Ba²⁺ and Sr²⁺ ions occupying the oxygen site. Furthermore, our study on annealing dependent phase evolution confirms that, this difference in ionic radii forbids the formation of a single phase Ba–Sr hexaferrite. The growth of clear hexagonal-shaped plate-like particles with varied particle sizes was observed for all the samples. The particle size variation may be due to the influence of the ionic radii difference on the sinterability of the samples. Our study provides a better understanding of synthesis mechanism of Ba–Sr hexaferrite samples.     

Industrial scale synthesis of few-layer graphene nanosheets (FLGNSs): an exploration of electrochemical exfoliation approach

Journal of Applied Electrochemistry - Industrial scale manufacturing with tunable properties of graphene nano-sheets has been a practical concern in many applications. This study focuses on, a...     

Tribological Performance Optimization of Electroless Ni–P Coatings Using the Taguchi Method and Grey Relational Analysis

The present article considers an experimental study of tribological performance of electroless Ni–P coatings and optimization of tribological test parameters based on the Taguchi method coupled with grey relational analysis. A grey relational grade obtained from the grey relational analysis is used as performance index to study the behaviour of electroless Ni–P coating with respect to friction and wear characteristics. Experiments are carried out by utilizing the combination of tribological test parameters based on L₂₇ Taguchi orthogonal design with three test parameters, viz., load, speed and time. It is observed that all the three test parameters have significant contribution in controlling the friction and wear behaviour of electroless Ni–P coating. In addition, the interaction of load and time has significant influence on tribological performance. The surface morphology, composition and wear mechanism of the coatings are studied with the help of scanning electron microscopy, X-ray diffraction analysis and energy dispersed X-ray analysis.     

$$E^{2} SR^{2}$$ E 2 S R 2 : An acknowledgement-based mobile sink routing protocol with rechargeable sensors for wireless sensor networks

Wireless Networks - The advances in hardware manufacturing technologies and wireless communications enabled the evolution of tiny, multi-functional, low-power and resource constrained sensor nodes...     

Direct and electromagnetically coupled compact microstrip antenna design with modified fractal DGS

This article proposes ultra‐miniature microstrip patches with direct and electromagnetically coupled feeding mechanism for wireless communications at 10 GHz. Antenna size reduction is achieved here by loading a modified Minkowski fractal (type‐2) defected ground structure (MFDGS‐II) exactly beneath the radiating patch. The proposed method involves the selection of best DGS configuration through sensitivity analysis of the antenna structure. From different applications point of view, three different designs: a single layer direct fed patch and two electromagnetically coupled fed multi‐layered microstrip patch antennas are proposed here and designed with MFDGS‐II. The resonant frequencies of the antenna designs are reduced in a significant manner incorporating MFDGS‐II without any change in the physical size of the antenna. The prototypes of the proposed antennas are fabricated, and the performance parameters are measured. Compared with other existing structures, with a lower patch size of 0.20 λ₀ × 0.15 λ₀, the proposed single layered antenna with microstrip feed achieves a patch size reduction up to 67% and an overall volumetric reduction of 84%, respectively. Similarly, the proposed multi‐layered patch with proximity feed exhibits a maximum impedance bandwidth of 600 MHz and the aperture coupled fed patch has a realized gain of 6.2 dBi with radiation efficiency of 91% centered at 10 GHz. All three proposed compact antenna structures are best in three different aspects and have the potential to meet the practical requirements for X‐band portable wireless applications.     

Application of Strong Arcs in m-Polar Fuzzy Graphs

Neural Processing Letters - Recently, m-polar fuzzy graph (mPF graph) becomes a growing research topic as the generalization of fuzzy graph. In this paper, at first mPF path, mPF cycle in an mPF...