Search

Abstract: We report on the 80-MeV nitrogen ion irradiation on spherical ZnO nanoparticles fabricated by way of solid state mixing. The structural and compositional analyses of the as-synthesized ZnO nanoparticles were done by X-ray diffraction, electron microscopy and energy dispersive spectroscopy studies. As evident from the optical absorption spectra, the energetic ion irradiation, on the nanoparticle system, is governed by evolution of new characteristic absorption features owing to modification in the electronic states. Again, in the luminescence spectra, though the near band-edge emission was not observable for pristine ZnO, it was recovered (at ∼385nm) upon irradiation. As far as the defect related emission is concerned, a competition between the formation and annihilation of different defects (especially, zinc vacancies and interstitials) at different ion fluences was realized. Correlating the luminescence spectra and the theoretical investigation, it can be understood that during irradiation the formation of zinc related defects are energetically favorable than the oxygen related counterparts. Exploration of defect related radiative features corresponding to definite structural organization/modification would help in making next generation light emitting and display devices, where a select emission response is desired. [Copyright &y& Elsevier]

This work highlights the low-cost fabrication and characterization of perovskite BaTiO3 nanoscale particles. X-ray diffraction studies show that an insufficient reaction time at ∼800°C will not result in the formation of the perovskite BaTiO3 structure, whereas over-sintering (∼900°C) results in BaTiO3 and by-products of BaTi2O5. The polyvinyl alcohol polymer-dispersed nano-BaTiO3 system exhibits a proportionately large remanent polarization (∼1μCcm−2) and coercive field (70kV cm−1). The inexpensive synthesis is attractive for large-scale production and device application. [Copyright &y& Elsevier]

Abstract: PbS quantum dots of average size 10nm are encapsulated in a matrix (polyvinyl alcohol (PVA)) following chemical route. They are irradiated with 160MeV Ni12+ ion beam with fluences 1012–1013 ions/cm2. Red shift in the absorption response in the optical absorption spectra reveal size enhancement of the quantum dots after irradiation and was confirmed by transmission electron microscopy (TEM). Photoluminescence (PL) study was carried out with excitation wavelength 325nm on both unirradiated and irradiated samples at different fluences and fluence-dependent surface states and excitonic emission is observed in the PL study. The Huang–Rhys coupling constant decreases significantly after swift heavy ion (SHI) irradiation and shows a decreasing trend with increase in ion fluence. [Copyright &y& Elsevier]

• Ag 2 O nanoparticle anchored UiO-66 metal organic framework (MOF) based electrodes have been fabricated. • The electrodes were employed for individual and simultaneous detection of Cd2+ and Hg2+. • Differential pulse stripping voltammetry (DPSV) data offered excellent selectivity and sensitivity. • The limit of detection (LOD) for the respective ions was estimated to be 0.008 μM and 0.003 μM. Herein, we come up with a new electrochemical sensing strategy for detecting heavy metal ions present in aqueous media using metal organic framework (MOF) electrode decorated with Ag 2 O nanoparticles (NPs). Post-synthesis modification route was followed to load the Ag 2 O NPs into zirconium-based MOF UiO-66 host. In the composite, the NPs were believed to act as the electric current enhancer while UiO-66 provided adsorption sites for heavy metal ions. The ITO electrodes were modified with as prepared composite for the electrochemical detection of Hg2+ and Cd2+ independently as well as simultaneously. The detection of heavy metals was performed by the modified electrodes through differential pulse stripping voltammetry (DPSV) which offered excellent selectivity and with sensitivity values up to 551 μA·μM−1·cm−2 for Cd2+ and 341.2 μA·μM−1·cm−2 for Hg2+. The limit of detection (LOD) for the respective cases, were estimated to be 0.008 μM and 0.003 μM. Technical viability of this approach can be further extended to real sample analysis in soil, river basin, waste land and even ground water for simultaneous detection of heavy metal ions as and when desired. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: In this work, we report on the surfactant assisted synthesis of gadolinium oxide (Gd2O3) nanoparticles and their characterization through various microscopic and spectroscopic tools. Exhibiting a monoclinic phase, the nanoscale Gd2O3 particles are believed to be comprising of crystallites with an average size of ∼3.2nm, as revealed from the X-ray diffraction analysis. The transmission electron microscopy has predicted a particle size of ∼9nm and an interplanar spacing of ∼0.28nm. Fourier transform infrared spectroscopy studies show that Gd–O inplane vibrations at 536.8 and 413.3cm−1 were more prominent for 80-keV Ar-ion irradiated Gd2O3 nanosystem than unirradiated system. The photoluminescence (PL) spectra of irradiated specimen have revealed an improvement in the symmetry factor owing to significant enhancement of surface-trap emission, compared to the band-edge counterpart. Irradiation induced creation of point defects (oxygen vacancies) were predicted both from PL and electron paramagnetic resonance (EPR) studies. Further, the Raman spectra of the irradiated sample have exhibited notable vibrational features along with the evolution of a new peak at ∼202cm−1. This can be ascribed to an additional Raman active vibrational response owing to considerable modification of the nanostructure surface as a result of ion bombardment. Probing nanoscale defects through prime spectroscopy tools would find a new avenue for precise tuning of physical properties with generation and annihilation of defects. [Copyright &y& Elsevier]

Biodegradable starch-pectin‑titanium oxide nanoparticles (TiO 2 - NPs) blend edible films were developed by casting filmogenic solution of sweet potato starch and lemon waste pectin incorporated with TiO 2 nanoparticles. The effect of incorporating different concentration of TiO 2 nanoparticle (0.5–4% wt) on the different properties of starch and pectin based edible film was evaluated. Surface color measurement, light transmission, scanning electron microscopy, fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis techniques were used to characterize the developed films. Increasing the level of TiO 2 -NPs led to significant decreases in the moisture content, solubility, and moisture uptake of the films. Addition of low concentration of TiO 2 - NPs into starch-pectin films significantly improved the mechanical and moisture barrier properties. SEM analysis also revealed that good particles dispersion could be obtained when nano-TiO 2 particles content was low (0.5–2% wt). The glass transition temperatures (Tg) shifted to higher temperature with increasing the TiO 2 concentrations and the thermal stability of the films was increased. The transmittance percentage was also decreased with increasing the TiO 2 concentrations which revealed that with UV prevention capacity, the developed films can be used as food grade UV screening biodegradable packaging material. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sensitive, stable, label free immunosensor fabricated using Au/GO/PEDOT-PSS. • Various charge transfer interfaces and interactions of electrode/electrolyte identified by impedance. • The limit of detection of the sensor by single frequency transient capacitance is 49 ng/mL. • Sensitivity range of the sensor is 9-363 ng/mL. In the present work, we have developed a cost effective, label free, sensitive and selective, capacitive immunosensor based on composites of conducting polymer PEDOT-PSS, graphene oxide (GO) and gold nanoparticles (AuNPs) deposited on ITO electrode. The composite electrode was fabricated by performing electrochemical polymerization of EDOT monomer in presence of PSS, keeping GO as dopant covered with chemically inert AuNPs. The composite electrode has been studied by using various structural characterization techniques to understand the improved composition and morphology. To investigate the electrochemical properties of modified electrodes Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were employed. New redox peaks and peak shifts in the CV of PEDOT-PSS indicated incorporation of GO and Au. Impedance data for all three electrodes was analyzed using a common equivalent circuit and suggested both kinetically and diffusion controlled processes. Specific interaction of antibody-analyte for all three electrodes was monitored directly via transient capacitance measurements at low and medium frequencies. Results showed that the AuNP/GO/PEDOT-PSS electrode is stronger mechanically and highly sensitive suggesting flexible sensor applications. With transient capacitance measurements, the proposed immunosensor exhibits high sensitivity in the range of 9–363 ng/mL with a detection limit of 49 ng/mL. [ABSTRACT FROM AUTHOR]