A study of the influence of crystallite size on the electrical and magnetic properties of CuFe2O4

An attempt has been made to clarify the fundamental assumption that the properties of materials change as the crystallite size of the material is reduced below 100 nm. CuFe₂O₄ samples of different crystallite sizes were prepared by the sol–gel and combustion methods and then analyzed by X-ray diffraction (XRD), thermal analyses (TGA/DTG) and scanning electron microscopy (SEM) techniques. The magnetic properties were studied by measuring the AC magnetic susceptibility (χ) and the Mössbauer spectroscopy. The DC electrical resistivity, dielectric constant, dielectric loss tangent, Curie temperature and hyperfine splitting of the samples change with the crystallite size. The change in the electrical properties is attributed to the formation of discrete energy levels instead of the bands. However, the magnetic parameters change due to the existence of non magnetic surface layers. The isomer shift and the hyperfine splitting show gradual increase with the increase in crystallite sizes.     

Preparation of nanocrystalline Cu<Subscript>2</Subscript>O thin film by pulsed laser deposition

In this paper, the synthesis of nanocrystalline copper oxides Cu₂O and CuO thin films on glass substrates using a pulsed 532 nm Nd:YAG laser is presented. Deposition of films is achieved at two different substrate temperatures. The influence of substrate temperature on the structural and optical properties of copper oxide films are discussed and analyzed. The X-ray diffraction (XRD) results show that the deposited films are crystalline in nature. Films prepared at 300 °C substrate temperature were Cu₂O and has (111) and (200) diffracted peaks, while films grown at 500 °C were CuO and has (111) and (020) planes. The morphology of deposited films were characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). The optical energy gap of Cu₂O and CuO films have been determined and found to be 2.04 and 1.35 eV respectively.     

Synergistic catalytic effect of SrTiO3 and Ni on the hydrogen storage properties of MgH2

Study on the synergistic catalytic effect of the SrTiO₃ and Ni on the improvement of the hydrogen storage properties of the MgH₂ system has been carried out. The composites have been prepared using ball milling method and comparisons on the hydrogen storage properties of the MgH₂ – Ni and MgH₂ – SrTiO₃ composites have been presented. The MgH₂ – 10 wt% SrTiO₃ – 5 wt% Ni composite is found to has a decomposition temperature of 260 °C with a total decomposition capacity of 6 wt% of hydrogen. The composite is able to absorb 6.1 wt% of hydrogen in 1.3 min (320 °C, 27 atm of hydrogen). At 150 °C, the composite is able to absorb 2.9 wt% of hydrogen in 10 min under the pressure of 27 atm of hydrogen. The composite has successfully released 6.1 wt% of hydrogen in 13.1 min with a total dehydrogenation of 6.6 wt% of hydrogen (320 °C). The apparent activation energy, E_a, for decomposition of SrTiO₃-doped MgH₂ reduced from 109.0 kJ/mol to 98.6 kJ/mol after the addition of 5 wt% Ni. The formation of Mg₂Ni and Mg₂NiH₄ as the active species help to boost the performance of the hydrogen storage properties of the MgH₂ system. Observation of the scanning electron microscopy images suggested the catalytic role of the SrTiO₃ additive is based on the modification of composite microstructure.     

Cancelable fusion-based face recognition

Multimedia Tools and Applications - Biometric recognition refers to the automated process of recognizing individuals using their biometric patterns. Recent advancements in deep learning and...     

Dependence of Magnetic Hysteresis on Evolving Single-Sample Sintering in Fine-Grained Yttrium Iron Garnet

Mono-dispersed yttrium iron garnet nanoparticles have been synthesized via mechanical alloying technique, and some attendant qualitative relationships between evolving microstructural parameters and magnetic properties have been clearly revealed. A rarely employed single-sample sintering scheme was adopted where only one sample was sintered repeatedly from 600 °C to 1400 °C prior to an analysis of evolution of microstructure-dependent magnetic properties after each sintering. A brief, yet detailed characterization of the sample was carried out using Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and B–H Hysteresis graph. A scrutiny of the B–H Hysteresis graph results showed a transition from disordered to ordered magnetism which belongs to three different magnetically dominant groups, namely weak ferro-, moderately strong ferro-, and strongly ferromagnetic groups. Three factors were found to strongly influence the ordered magnetism of the sample, namely the crystallinity degree of the crystalline phase, the number of grains with size larger than a critical diameter, and the number of large enough grains for magnetic order accommodation.     

Development of antipeptide enzyme‐linked immunosorbent assay for determination of gelatin in confectionery products

The gelatin sources have become a controversial issue with regard to religious and health concern. Thus, the aims of this study were to develop and evaluate the efficiency of polyclonal antibodies against peptide immunogen of collagen α2 (I) chain for determination of gelatin sources in confectionery products by competitive indirect enzyme‐linked immunosorbent assay (ELISA). Collagen α2 (I) chain protein showed resistance against heat treatment and detectable in certain commercial products when analysed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE). The established ELISA exhibited low cross‐reactivity to fish and chicken gelatin. The IC₅₀ value was 0.39 μg mL^?1, and the limit of detection (IC₁₀) was 0.05 μg mL^?1. There were no false‐positive results from forty‐eight commercially processed products. The present method is useful for determination of gelatin in confectionery products.