Nanoporous zirconium oxide prepared using the supramolecular templating approach

Hexagonal (Hx-ZrO₂) and lamellar (L-ZrO₂) phases of zirconium oxide have been prepared using the supramolecular templating approach. Long chain primary alkyl amines led to the formation of lamellar phases, while quaternary ammonium surfactants gave hexagonal phases. The materials have been characterized by XRD, TG/DTG, IR, XPS, SEM and EDX techniques. The influence of various synthesis parameters such as (i) the ZrO₂ surfactant ratio, (ii) the surfactant/water ratio, (iii) the nature of surfactant, (iv) the crystallization temperature and (v) the crystallization time have been investigated. The final solid products were found to be thermally unstable regardless of their structure. Removal of the surfactant from the mesopores by solvent extraction without damaging the structure was not possible.     

Improved Network Traffic by Attacking Denial of Service to Protect Resource Using Z-Test Based 4-Tier Geomark Traceback (Z4TGT)

Wireless Personal Communications - Network security plays a vital role in protecting the resources available in the network against various threats. There are vulnerabilities in every system...     

WEB-Spline-based mesh-free finite element approximation for p-Laplacian

In this paper, we discuss the approximation of p-Laplace problem using WEB-Spline based mesh free finite elements. Along with usual weak formulation, we also consider the mixed formulation of the p-Laplace problem. We give existence, uniqueness results for both continuous and discrete problems. We also provide a priori error estimates for both the formulations.     

Modified octahedron shaped antenna with parasitic loading plane having dual band notch characteristics for UWB applications

The design of a compact modified octahedron shaped dual band notched ultra wide‐band antenna is presented in this article. The impedance bandwidth of the designed antenna has been enhanced by modifying the shape of the radiator by introducing fractal geometry and a modified ground plane. The proposed antenna offered an impedance bandwidth of 2.4 GHz–19.5 GHz (156% Fractional bandwidth). Two rectangular split ring resonator structures are introduced in the radiator to achieve two notched bands which ranges from 3.3 GHz to 3.7 GHz (WiMAX) and 5.15 GHz–5.85 GHz (WLAN) band. The antenna gain varies from 1 to 4 dBi over the operating band except the notched bands. The overall dimension of the designed antenna has a compact size of 33 × 40 mm². The experimental and simulation results are in good agreement. The proposed antenna has wider bandwidth and smaller dimension over the already reported in the literature. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:426–434, 2016.     

Investigation of multiphase polymeric systems of poly(vinyl chloride)/ethylene-propylene-diene-gp-(styrene-CO-acrylonitrile) blends

The graft copolymer, ethylene-propylene-diene rubber (EPDM)-gp-(styrene-co-acrylonitrile) has been synthesized by solution precipitation polymerization using benzoyl perixide as initiator. The graft copolymer has been characterized after separation through soxhlet extraction by IR, NMR, and elemental analysis techniques. The graft copolymer of EPDM is melt blended with PVC. The nature of compatibility of the graft copolymers with PVC has been studied by means of morphological analysis and by thermal analysis. The mechanical properties, Izod impact strength, tensile strength, and flexural modulus of the blends are extensively studied over the wide range of concentrations. The results of both compatibility and mechanical properties are compared with those of PVC/EPDM blends. The nature of compatibility obtained shows that PVC/EPDM blends are incompatible and the PVC/EPDM-gp-SAN system is semicompatible. Also, these results indicate that the PVC/EPDM-gp-SAN system has its highest impact strength at 14 wt% of EPDM/gp-SAN graft copolymer. The fractured surface analysis of the impact fractured samples is also undertaken by an SEM technique. The results of the mechanical properties are discussed in view of existing theories of impact modification, along with the morphological feature of fractographs.     

Selective oxidation of secondary amines over titanium silicalite molecular sieves,TS-1 and TS-2

Titanium silicalite molecular sieves, TS-1 and TS-2 having MFI and MEL structures, respectively, catalyze the oxidation of secondary amines to the corresponding hydroxylamines using hydrogen peroxide as the oxidant. Higher concentrations of H₂O₂ lead to further oxidation of hydroxylamine to nitrone. Diffuse reflectance spectroscopy shows the formation of a titanium peroxo complex upon addition of hydrogen peroxide to the TS-1 catalyst. The titanium peroxo complex oxidizes the substrate and reforms to a titanyl group.     

Syllable based text to speech synthesis system using auto associative neural network prosody prediction

This paper presents the design and development of an Auto Associative Neural Network (AANN) based unrestricted prosodic information synthesizer. Unrestricted Text To Speech System (TTS) is capable of synthesize different domain speech with improved quality. This paper deals with a corpus-driven text-to speech system based on the concatenative synthesis approach. Concatenative speech synthesis involves the concatenation of the basic units to synthesize an intelligent, natural sounding speech. A corpus-based method (unit selection) uses a large inventory to select the units and concatenate. The prosody prediction is done with the help of five layer auto associative neural network which helps us to improve the quality of speech synthesis. Here syllables are used as basic unit of speech synthesis database. The database consisting of the units along with their annotated information is called annotated speech corpus. A clustering technique is used in annotated speech corpus that provides way to select the appropriate unit for concatenation, based on the lowest total join cost of the speech unit. Discontinuities present at the unit boundaries are lowered by using the mel-LPC smoothing technique. The experiment has been made for the Dravidian language Tamil and the results reveal to demonstrate the improved intelligibility and naturalness of the proposed method. The proposed system is applicable to all the languages if the syllabification rules has been changed.     

Ion-irradiation-induced ferromagnetism in undoped ZnO thin films

We have introduced defects in ZnO epitaxial thin films by swift heavy ¹⁰⁷Ag⁹⁺ ion irradiation and investigated systematically their magnetic, electrical and optical properties. Oxygen annealed ZnO films are epitaxial single crystals that exhibit no long-range magnetic order. However, in this paper it is shown that room-temperature ferromagnetism (RTFM) can be introduced in a controlled manner in these films using ion irradiation and that the magnetization increases with ion dose. This qualitatively agrees with earlier studies which showed that RTFM could be induced in ZnO films through either vacuum thermal annealing or pulsed laser annealing below energy densities that lead to melting. Raman studies of the ion irradiated samples revealed dramatic changes in the vibration modes that correlated with increases in the carrier concentration, indicative of lattice disorder and defect creation. We compare these results with those observed in laser irradiated and vacuum annealed samples, and then discuss these findings in the context of defects and defect complexes created during the high-energy heavy ion irradiation process. We propose a unified mechanism to explain RTFM and n-type conductivity enhancements during irradiation, and laser and vacuum annealing.     

Effects of grape seed extract on the oxidative and microbial stability of restructured mutton slices

The antioxidant and antimicrobial efficacy of grape seed extract (GSE) was studied in restructured mutton slices (RMS) under aerobic and vacuum packaging conditions during refrigerated storage. The RMS treated with grape seed extract (GSE) had significantly (P < 0.05) lower thiobarbituric acid reactive substance (TBARS) values and free fatty acids (FFA) % compared to control (C) and butylated hydroxy anisole (BHA) treated RMS during storage at 4 ± 1 °C. Addition of GSE significantly (P < 0.05) reduced the total psychrophilic and coliform counts in RMS during refrigerated storage. The GSE treated mutton slices recorded significantly (P < 0.05) superior scores of color, flavor, juiciness and overall palatability than C and BHA treated RMS. The TBARS values, FFA % and microbial counts increased significantly (P < 0.05) during storage. It can be concluded that GSE has excellent antioxidant and antimicrobial properties compared to control and BHA treated RMS during refrigerated storage under aerobic and vacuum conditions.     

Melt processing and microstructural analysis of GdBa2Cu3Oy with varying amounts of Gd2BaCuO5 phase

Bulk samples of GdBa₂Cu₃O_y (Gd-123) with varying amount of Gd₂BaCuO₅ (Gd-211) phase are melt processed. The processing conditions and the resulting macro and microstructures were discussed. The T_c of the material is found to be sensitive to the processing atmosphere, and the percentage of 211 in the precursor powder. Pure Gd-123 samples behaved differently as compared to the compositions with excess 211 phase. The amount of porosity and the average size of pores in the samples decreases with the increasing amount of Gd-211 in the precursor powder. The densification of the melt textured material is ascribed to the densification process of the precursors prior to the texturing stage. Irrespective of the Gd-211 content macro-cracks within domains were observed in parallel to the intrinsic micro-cracks. At the melting stage refinement of the Gd-211 particles originating from the decomposition of Gd-123 was observed with the increasing amounts of external Gd-211 in the liquid. The quantitative analysis of the microstructural features, i.e., the residual Gd-211, platelet width, domain sizes of the resulting melt textured materials were presented. Addition of Ag resulted in mild refining of 211 particles.