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[en] Graphical abstract: - Highlights: • A simple sol–gel method for the synthesis of SnO₂–MgO nanoparticles is reported. • Band gap of SnO₂ can be tuned by varying the magnesium content in SnO₂–MgO. • SnO₂–MgO shows good photocatalytic activity towards degradation of methylene blue. - Abstract: SnO₂–MgO mixed metal oxide nanoparticles were prepared by a simple sol–gel method. The nanoparticles were characterized by power X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The XRD results indicate the formation of mixed metal oxide nanoparticles and also a decrease of SnO₂ crystallite size in the mixed metal oxide nanoparticles with increasing magnesium oxide content. The reflectance spectroscopy results show a blue shift of the band gap of SnO₂ in the mixed metal oxide nanoparticles. The photocatalytic activity of the SnO₂–MgO nanoparticles was tested using the photodegradation of aqueous methylene blue in the presence of sunlight. The results indicate that the mixed metal oxide nanoparticles possess higher efficiency for the photodegradation of methylene blue compared to pure SnO₂ nanoparticles

[en] An analytic linear theory of the plasma dynamics in a external transverse magnetic wiggler field is presented. In this paper the modulational instability associated with propagation of intense laser pulses in plasma channel is analysed. The effect of the wiggler filed on plasma dynamics is studied and modified steady-state orbits and their stabilities have been analysed considering variation of electron energy and density. Wiggler magnetic field plays both a dynamic role in producing the traverse harmonic current and a kinematical role in ensuring phase-matching due to this the obtained the growth rate of modulation instability from laser beam propagating in plasma immersed in combined axial and longitudinal wiggler magnetic fields. The growth rate is substantially larger than the standard slow wave free electron laser scheme utilizing a transverse wiggler field. (author)

[en] Indium tin oxide thin films were deposited at room temperature on glass substrates by RF magnetron sputtering. The structural, electrical and optical properties of the films showed a dependence on target to substrate spacing and annealing temperature. Films deposited with a target to substrate spacing of 4 cm showed the lowest resistivity of 3.07x10^-3 Ω cm and maximum band gap of 3.89 eV on annealing at a temperature of 250 deg. C under high vacuum for 1 h

[en] Multicomponent oxide powders with nominal compositions of (45 − x)·SiO_2·24.5CaO·24.5Na_2O·6P_2O_5xFe_2O_3 (in wt.%) were prepared by a modified sol–gel procedure. X-ray diffraction (XRD) patterns and high resolution transmission electron microscope images of the sol–gel products show fully amorphous structure for Fe_2O_3 substitutions up to 2 wt.%. Sol–gel derived 43SiO_2·24.5CaO·24.5Na_2O·6P_2O_5·2Fe_2O_3 glass (or bioglass 45S5 with SiO_2 substituted with 2 wt.% Fe_2O_3), exhibited magnetic behavior with a coercive field of 21 Oe, hysteresis loop area of 33.25 erg/g and saturation magnetization of 0.66 emu/g at an applied field of 15 kOe at room temperature. XRD pattern of this glass annealed at 850 °C for 1 h revealed the formation of a glass–ceramic containing sodium calcium silicate and magnetite phases in nanocrystalline form. Temperature dependent magnetization and room temperature electron spin resonance data have been used to obtain information on the magnetic phase and distribution of iron ions in the sol–gel glass and glass–ceramic samples. Sol–gel derived glass and glass–ceramic exhibit in-vitro bioactivity by forming a hydroxyapatite surface layer under simulated physiological conditions and their bio-response is superior to their melt quenched bulk counterparts. This new form of magnetic bioglass and bioglass ceramics opens up new and more effective biomedical applications. - Highlights: • Bioglass 45S5 containing 2 wt.% Fe_2O_3 is prepared by sol–gel route. • Fully amorphous bioglass exhibits spontaneous magnetization. • Gel powders with more than 2 wt.% Fe_2O_3 formed glass–ceramics. • γ-Fe_2O_3 in bioglass transformed irreversibly to magnetite upon heat treatment. • In vitro bioactivity of sol–gel samples is superior to their bulk counterparts.

[en] Lithium Lead Alumino Borate (LiPbAlB) glasses doped with Dy³⁺ ions with varying concentration were synthesized by using the melt quenching technique to understand their feasibility in solid state lighting and laser devices. From the absorption spectra, bonding parameters (δ) were evaluated to understand the nature of bonding between Dy³⁺ ions and its surrounding ligands. Judd-Ofelt intensity parameters estimated from the experimental oscillator strengths were used to evaluate various radiative parameters for the fluorescent levels of Dy³⁺ ions. From the decay curves, the experimental lifetimes were measured and coupled with the radiative lifetimes to evaluate the quantum efficiency. The decay profile changes from exponential to non-exponential with increase in Dy³⁺ ion concentration resulting decrease in experimental lifetimes. Inokuti-Hirayama model applied to the decay spectral profiles confirm dipole-dipole interaction responsible for their conversion from exponential to non-exponential. By exciting the glasses with different n-UV radiations, the CIE chromaticity coordinates and correlated color temperatures (CCT) were calculated to understand the utility of as-prepared glasses in cool white light generation. From the evaluated radiative parameters, CIE co-ordinates, CCT temperatures, emission cross-sections, quantum efficiency and confocal images, it was observed that LiPbAlB glass with 0.5 mol% Dy³⁺ ions are more suitable for the development of w-LEDs and Lasers.

[en] Zinc oxide nanorods were grown employing a low cost hydrothermal method on microslide glass substrates pre-coated with ZnO seed layer. The as grown nanorods were annealed in air at 350 °C, 450 °C and 550 °C. The effect of annealing at different temperatures on morphology, structural, optical and electrical properties was investigated using field emission scanning electron microscopic, X-ray diffraction, UV–vis spectral, photoluminescence and electrical studies. The X-ray diffraction pattern of all the samples showed wurtzite structure preferentially oriented along the c-axis (0 0 2) direction. It was found that diameter of the nanorods increased with increasing of annealing temperature. The UV–vis absorption spectra showed a red shift from which it was inferred that the optical bandgap of the material decreases from 3.33 eV to 3.28 eV with increase in annealing temperature. Photoluminescence measurements showed increase in the UV emission intensity with respect to annealing temperature and also produced additional peaks attributed to defects and impurities. Annealing the ZnO nanorod structures at various temperatures evidently showed that the sample annealed at 550 °C acquired the lowest resistivity about 1.62 × 10"−"4 Ω-cm. - Highlights: • ZnO nanorods were synthesized by hydrothermal method on microslide glass substrates. • Pre-deposited ZnO seeds were used. • Structural, optical and electrical properties of ZnO nanorods were studied. • Crystalline structure of ZnO nanorods was improved with increase in annealing temperature. • Resistivity decrease was observed with increase in the annealing temperature.

[en] The influence of excess surfactant concentration on the uniformity and self-assembly of dip-coated FePt nanoparticle films on thermally oxidized Si substrates is reported. The nanoparticle solution in non-polar solvents contains excess surfactant, which is varied in a range from 10^-6 to 10^-1 parts by volume. Uniform, homogeneous films of nanoparticles are obtained only in a narrow range of excess surfactant concentration of about 10^-3 parts by volume

[en] The present studies were conducted to study the effect of growth regulators and gamma rays on carotenoid content in husk tomato (Physalis peruviana L. and P. angulata L.). Results indicated that carotenoid content (in fruits) increased in all the treatments (except 200 and 500 ppm coumarin in case of P. peruviana and 100, 200 and 500 ppm coumarin in case of P. angulata). It is concluded that low doses of gamma rays may show stimulatory effect on carotenoid content in fruits of husk tomato. (author). 10 refs., 1 tab

[en] FePt nanoparticles coated with 2 nm thick films of surfactant have been studied as candidates for magnetic recording media. The self-assembly of these nanoparticles is influenced by the properties of their surfaces which are coated with a layer of mixed oleic acid and oleyl amine. These surfactant coated FePt nanoparticles were characterized using Fourier transform infrared spectroscopy (FTIR). The observation of both ν(COO) and ν(C=O) vibrational modes indicates that oleic acid bonds to the FePt nanoparticles in both monodentate and bidentate forms. The oleylamine bonds to the FePt nanoparticles through electron donation from the nitrogen atom of the NH₂ group. The FTIR spectra indicate that there is a conversion of the alkyl chains from the oleyl form (cis-9-octadecenyl) to the elaidyl form (trans-9-octadecenyl) during the synthesis of the FePt nanoparticles. This is revealed by the presence of several vibrational absorption bands in the region of the olefinic C-H stretching modes. The presence of elaidyl groups on the FePt surfaces is very important because the structures of the oleyl groups and the elaidyl groups are quite different and are expected to pack differently around the FePt nanoparticles. This in turn will influence the self-assembly of nanoparticles on substrates