Effect of Oxide Defect Structure on the Electrical Properties of ZrO2

The defect structure of monoclinic ZrO₂ was studied by measuring the transfer numbers and electrical conductivity as functions of O₂ pressure and temperature. The data suggest a defect structure of doubly ionized oxygen vacancies at low pressures, i.e. <10⁻¹⁹ atm, and singly ionized oxygen interstitials at pressures >10⁻⁹ atm. Zirconia is primarily an ionic conductor below #700°C and an electronic conductor at 700° to 1000°C for 10⁻²²≤P_o2≤1 atm.     

Synthesis and characterization of stable aqueous dispersions of graphene

A stable aqueous dispersion (5 mg ml^?1) of graphene was synthesized by a simple protocol based on three-step reduction of graphene oxide (GO) dispersion synthesized using the modified version of Hummers and Offeman method. Reduction of GO was carried out using sodium borohydride, hydrazine hydrate and dimethyl hydrazine as reducing agents. The chemically synthesized graphene was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible absorption spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopy, thermogravimetric analysis (TGA), optical microscopy. The stability of aqueous dispersions of graphene was confirmed through zeta potential measurements and the negative zeta potentials of 55–60 mV were obtained indicating the high stability of aqueous graphene dispersions.     

Preparation and characterization of PAN–KI complexed gel polymer electrolytes for solid-state battery applications

The free standing and dimensionally stable gel polymer electrolyte films of polyacrylonitrile (PAN): potassium iodide (KI) of different compositions, using ethylene carbonate as a plasticizer and dimethyl formamide as solvent, are prepared by adopting ‘solution casting technique’ and these films are examined for their conductivities. The structural, miscibility and the chemical rapport between PAN and KI are investigated using X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry methods. The conductivity is enhanced with the increase in KI concentration and temperature. The maximum conductivity at 30°C is found to be 2.089 × 10^?5 S cm^?1 for PAN:KI (70:30) wt%, which is nine orders greater than that of pure PAN (< 10^?14 S cm^?1). The conductivity-temperature dependence of these polymer electrolyte films obeys Arrhenius behaviour with activation energy ranging from 0.358 to 0.478 eV. The conducting carriers of charge transport in these polymer electrolyte films are identified by Wagner’s polarization technique and it is found that the charge transport is predominantly due to ions. The better conducting sample is used to fabricate the battery with configuration K/PAN + KI/I₂+ C + electrolyte and good discharge characteristics of battery are observed.     

Gold nanoparticle-coated biomaterial as SERS micro-probes

We report for the first time, on the utility of plant-based biomaterial as enhanced-Raman scattering probes. The bio-substrate used in this study are commonly found in plant extracts, and are cost-effective, mechanically robust, flexible and easily transportable. The probe was fabricated by coating the plant extract with gold nanoparticles and characterized. By employing a ‘single-touch contact’ method, we reveal the ability of these probes to detect routinely used Raman markers such as 2-napthalenethiol and rhodamine B, at nano-molar concentrations, in dry and liquid forms, respectively. Reproducibility of the signals with variation <5%, and the ability to detect biomolecules are demonstrated herein. We envision these bio-probes as potential candidates for enhanced Raman sensing in chemical, environmental, and archaeological applications. By further engineering the shape, morphology, and surface chemistry of these micro-probes, we foresee their utility as miniaturized, natural SERS substrates.     

Structural characteristics of titanium coating on copper substrates

The growth characteristics of titanium films deposited on glass, silicon (100) and oxygen free high purity copper substrate using magnetron sputtering have been investigated using X-ray diffraction, electron microscopy and scratch indentation techniques. The study of interface between the titanium film and the substrate was carried out to determine coating thickness, as well as intermixing of the elements at the interface. Studies revealed that the interface is free from voids and intermixing of the film and the substrate. Microstructural and diffraction analysis showed that the Ti coating was polycrystalline and exhibited columnar growth. The Ti crystallite size varied between 24 and 58 nm depending on the substrate. The thickness of the films were typically about 4 μm. Scratch test indicated that the films are adherent and the first critical load to failure was observed to be 4·5 N ± 2 N.     

Balanced gait generations of a two-legged robot on sloping surface

In this paper, dynamically balanced gait generation problem of a 7-DOF two-legged robot moving up and down through the sloping surface is presented. The gait of the lower links during locomotion is obtained after assuming suitable trajectories for the swing leg and hip joint. The trunk motion is initially generated based on the concept of static balance, which is different from the well-known semi-inverse method and then checked for its dynamic balance calculated using the concept of Zero-Moment Point (ZMP). Lagrange–Euler formulation is attempted for the determination of joint torques. Average power consumption at each joint is then determined based on the computed torques. Moreover, the variations of dynamic balance margin and average power consumption are studied for both ascending and descending through the sloping surface. Both of them are found to be more for the ascending gait generation compared to those for the descending case. The effects of variations of the slope have also been studied on the average dynamic balance margin and power consumption for both the cases.     

Effect of loading condition,specimen geometry,size-effect and softening function on double-<Emphasis Type=BoldItalic>K</Emphasis> fracture parameters of concrete

This paper presents numerical investigation of the influence of the specimen geometry, loading condition, size-effect and softening function of concrete on double-K fracture parameters. The input data needed for computation of the double-K fracture parameters are obtained from the well-known version of Fictitious Crack Model (FCM). FCM is developed for three standard specimens: three-point bend test, compact tension specimen and four-point bend test of size range 100–600 mm at relative size of initial crack length 0.3. The analysis of numerical results shows some interesting behaviour of double-K fracture parameters.     

Improved cuckoo search with particle swarm optimization for classification of compressed images

The need for a general purpose Content Based Image Retrieval (CBIR) system for huge image databases has attracted information-technology researchers and institutions for CBIR techniques development. These techniques include image feature extraction, segmentation, feature mapping, representation, semantics, indexing and storage, image similarity-distance measurement and retrieval making CBIR system development a challenge. Since medical images are large in size running to megabits of data they are compressed to reduce their size for storage and transmission. This paper investigates medical image retrieval problem for compressed images. An improved image classification algorithm for CBIR is proposed. In the proposed method, RAW images are compressed using Haar wavelet. Features are extracted using Gabor filter and Sobel edge detector. The extracted features are classified using Partial Recurrent Neural Network (PRNN). Since training parameters in Neural Network are NP hard, a hybrid Particle Swarm Optimization (PSO) – Cuckoo Search algorithm (CS) is proposed to optimize the learning rate of the neural network.