Identification of microstructural zones and thermal cycles in a weldment of modified 9Cr-1Mo steel

This paper presents the results of a study on the microstructural and microchemical variations in a multipass Gas Tungsten Arc weld (GTAW) of modified 9Cr-1Mo steel. The changes brought about in the steel due to the heating and cooling cycles during welding and the subsequent effects due to reheating effects during multipass welding are described. Detailed analytical transmission electron microscopy has been carried to study the type and composition of the primary and secondary phases in this steel. The systematic changes in microstructural parameters such as Prior Austenite Grain Size, martensite lath size, number density, size and microchemistry of carbides, have been understood based on the different transformations that the steel undergoes during the heating and cooling process. Based on the observed microstructure, an attempt has been made to identify distinct microstructural zones and possible thermal cycles experienced by different regions of the weldment.     

Synthesis and metal uptake studies on poly(8‐hydroxy‐5‐azoquinolinephenylacrylate‐formaldehyde) resin and its metal complexes

8‐hydroxy‐5‐azoquinolinephenylacrylate‐formaldehyde (8H5AQPA‐F) macromonomer was prepared from acryloylchloride, with condensation products of 8‐hydroxy‐5‐azoquinolinephenol‐formaldehyde, and polymerized in DMF at 70°C using benzoyl peroxide as free radical initiator. Poly(8H5AQPA‐F) was characterized by infrared and nuclear magnetic resonance spectroscopic techniques. Polychelates were obtained in alkaline solution of polymeric ligand, with the aqueous solution of Cu(II) and Ni(II). Elemental analysis of polychelates suggests that the metal to ligand ratio is about 1:2. The polymer metal complexes were also characterized by IR, XRD, magnetic moments, and thermal analysis. The effects of pH and electrolyte on the metal uptake behavior of the resin were also studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 797–802, 2007     

Design of high-speed data transfer turbo code for body channel communication transceivers

In this work, a digital differential transmitter based on low-power wireless compensation transceiver for body channel communication (BCC) is proposed. Further, the proposed transceiver is composed of Touch Status Detection Unit (TSDU), Wireless Status Compensation Unit (WSCU), and a reconfigurable preamplifier. Initially, the human body channel environment for wireless communication is investigated based on properties from 1 to 100 MHz. Further, the turbo code-based encoding scheme is used to encode the data before transferring the data on the transmitter side. Also, the proposed error-correcting parallel turbo decoder using a modified step-by-step algorithm is presented. The turbo code-based decoding scheme is used to recover the error-free transmitted data at the receiver side. Results demonstrate that the proposed BCC transceiver is designed using 90 nm CMOS technology and it is observed that the proposed BCC transceiver has utilized an area of 600mm². Also, the maximum data rate achieved by a proposed BCC transceiver was 100 Mbps, and the overall transceiver power consumption is 0.42 mW, and energy for communication is 0.02 nj/b.     

Application of homotopy perturbation and variational iteration methods for nonlinear imprecise prey–predator model with stability analysis

The Journal of Supercomputing - A coupled nonlinear prey–predator system is presented. The system formulation is based on nonlinear ordinary differential equations with imprecise parameter...     

In‐situ fabrication of zirconium–titanium nano‐composite and its coating on Ti‐6Al‐4V for biomedical applications

In this study, nanocomposite powder consisting of zirconia and titania (Zr–Ti) have been synthesised by sol–gel method, with the aim of protecting Ti‐6Al‐4V surface. A simple and low cost electrophoretic deposition (EPD) technique has been employed for coating the nanocomposite material on Ti‐6Al‐4V. The prepared nanocomposite powder was characterised for its functional groups, phase purity, surface topography by Fourier transform infrared spectroscopy, powder X‐ray diffraction and scanning electron microscopy. Further, the biocompatibility nature of the composite powder was studied by [3‐(4, 5‐dimethylthiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide] colorimetric assay and fluorescence analysis with MG63 osteoblast cell lines. The electrochemical behaviour of composite coating was investigated by potentiodynamic polarization and electrochemical impedance method. The results obtained from the electrochemical techniques indicate more corrosion resistance behaviour with increase of R _ct value with the corresponding decrease in R _dl values. From the above findings, the composite coating acts as a barrier layer against corrosion by preventing the leaching of metal ions from a dense and defect free coating. A scratch test analyser was used to assess the integrity of the coating; the lower traction force value of composite coating with increase in load has confirmed the presence of thick adherent layer on the substrate.Inspec keywords: zirconium compounds, titanium compounds, titanium alloys, aluminium alloys, vanadium alloys, nanofabrication, nanocomposites, nanoparticles, sol‐gel processing, electrophoretic coating techniques, surface topography, Fourier transform infrared spectra, X‐ray diffraction, scanning electron microscopy, X‐ray chemical analysis, fluorescence, cellular biophysics, biomedical materials, electrochemical impedance spectroscopy, corrosion resistance, corrosion protection, corrosion protective coatings, adhesionOther keywords: in‐situ fabrication, zirconium‐titanium nanocomposite powder, biomedical applications, zirconia, titania, sol‐gel method, electrophoretic deposition, EPD, functional groups, phase purity, surface topography, Fourier transform infrared spectroscopy, powder X‐ray diffraction, scanning electron microscopy, energy dispersive X‐ray analysis, biocompatibility, 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide colorimetric assay, acridine range fluorescence analysis, MG63 osteoblast cell lines, electrochemical behaviour, composite coating, potentiodynamic polarization, electrochemical impedance spectroscopy, corrosion resistance, barrier layer, leaching, defect free coating layer, scratch test analysis, adherent layer, TiAlV‐ZrO₂ ‐TiO₂      

Biocompatibility assessment of SiO2 –TiO2 composite powder on MG63 osteoblast cell lines for orthopaedic applications

The objective of this study is to evaluate the biocompatibility of composite powder consisting of silica and titania (SiO₂ –TiO₂) for biomedical applications. The advancement of nanoscience and nanotechnology encourages researchers to actively participate in reinvention of existing materials with improved physical, chemical and biological properties. Hence, a composite/hybrid material has given birth of new materials with intriguing properties. In the present investigation, SiO₂ –TiO₂ composite powder was synthesised by sol‐gel method and the prepared nanocomposite was characterised for its phase purity, functional groups, surface topography by powder X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR) and scanning electron microscopy. Furthermore, to understand the adverse effects of composite, biocompatibility test was analysed by cell culture method using MG63 osteoblast cell lines as a basic screening method. From the results, it was observed that typical Si–O–Ti peaks in FT‐IR confirms the formation of composite and the crystallinity of the composite powder was analysed by XRD analysis. Further in vitro biocompatibility and acridine orange results have indicated better biocompatibility at different concentrations on osteoblast cell lines. On the basis of these observations, we envision that the prepared silica–titania nanocomposite is an intriguing biomaterial for better biomedical applications.Inspec keywords: bioceramics, nanocomposites, silicon compounds, titanium compounds, nanofabrication, sol‐gel processing, surface topography, X‐ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, X‐ray chemical analysis, cellular biophysics, nanomedicineOther keywords: MG63 osteoblast cell lines, orthopaedic applications, biomedical applications, nanoscience, nanotechnology, nanotoxicology, physical properties, chemical properties, biological properties, biological applications, biomaterial synthesis, composite‐hybrid materials, intriguing properties, sol‐gel method, surface properties, ceramic nanocomposite, phase purity, functional groups, surface topography, powder X‐ray diffraction, Fourier transform infrared spectroscopy, FT‐IR spectroscopy, scanning electron microscopy, energy dispersive X‐ray analysis, biocompatibility test, cell culture method, screening method, crystallinity, XRD, in vitro biocompatibility, acridine orange, silica‐titania nanocomposite powder, SiO₂ ‐TiO₂      

Electrical properties of ZnSe-CdS alloy films

Thin films of ZnSe _x CdS_1–x (t 0.6 m) over the entire range of x, were deposited on glass substrates at two temperatures, T _s (350 and 470 K) by vacuum evaporation. X-ray diffraction studies showed that all the films were polycrystalline in nature. Films prepared at 470 K were nearly stoichiometric. Grain size increased with substrate temperature, T _s. The electrical conductivity and Hall measurements were carried out by d.c. van der Pauw technique. Hall effect studies/hot probe test showed that all the films were of n-type conductivity. Hall mobility increased with T _s. In addition, mobilities increased with temperature in films of all compositions, indicating the dominance of grain-boundary scattering. Grain-boundary potentials were in range 0.03–0.06 eV.     

Evaluating the validity of data instances against ontology evolution over the Semantic Web

It is natural for ontologies to evolve over time. These changes could be at structural and semantic levels. Due to changes to an ontology, its data instances may become invalid, and as a result, may become non-interpretable. In this paper, we address precisely this problem, validity of data instances due to ontological evolution. Towards this end, we make the following three novel contributions to the area of Semantic Web. First, we propose formal notions of structural validity and semantic validity of data instances, and then present approaches to ensure them. Second, we propose semantic view as part of an ontology, and demonstrate that it is sufficient to validate a data instance against the semantic view rather than the entire ontology. We discuss how the semantic view can be generated through an implication analysis, i.e., how semantic changes to one component imply semantic changes to other components in the ontology. Third, we propose a validity identification approach that employs locally maintaining a hash value of the semantic view at the data instance.     

Study of transformation behavior in a Ti–4.4 Ta–1.9 Nb alloy

An alloy of composition Ti–4.4 wt.% Ta–1.9 wt.% Nb is being developed as a structural material for corrosion applications, as titanium and its alloys possess excellent corrosion resistance in many oxidizing media. The primary physical metallurgy database for the Ti–4.4 wt.% Ta–1.9 wt.% Nb alloy is being presented for the first time. Determination of the β transus, M_s temperature and classification of the alloy have been carried out, employing a variety of microscopy techniques, X-ray diffraction (XRD), micro-hardness and differential scanning calorimetry (DSC). The β transition temperature or β transus determined using different experimental techniques was found to agree very well with evaluations based on empirical calculations. Based on chemistry and observed room temperature microstructure, the alloy has been classified as an + β titanium alloy. The high temperature β transforms to either ′ or + β by a martensitic or Widmanstatten transformation. The mechanisms of transformation of β under different conditions and characteristics of different types of have been studied and discussed in this paper.