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Yekaterinburg, Russia

Aphesteguy J.C.,University of Buenos Aires | Kurlyandskaya G.V.,University of the Basque Country | Kurlyandskaya G.V.,Ural Federal University | de Celis J.P.,National Technology University | And 3 more authors.
Materials Chemistry and Physics | Year: 2015

Magnetic nanoparticles (MNPs) of pure magnetite (Fe3O4) were prepared in an aqueous solution (sample M-I) and in a water-ethyl alcohol mixture (sample M-II) by the co-precipitation method. The structure and magnetic properties of both samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), magnetic (M-H) and microwave measurements (FMR). The mean average particle diameter and particle size distribution was evaluated by the Dynamic Light Scattering (DLS) and Brunauer- Emmett-Teller techniques (BET). The Quantitative chemical analysis of iron was performed by Inductively Coupled Plasma (ICP)- Atomic Emission Spectroscopy (AES) technique. The MNPs prepared in aqueous solution show a higher grain than those prepared in the water-ethyl alcohol mixture. The type of phase structure in both cases can be defined as "defective spinel". The shape of the majority of M-I MNPs is octahedral. The shape of the majority of M-II MNPs is cubic. The specific surface area of MNPs was as high as 14.4m2/g for M-I sample and 77.8m2/g for sample M-II. The obtained saturation magnetization values of 75emu/g (M-I) and 68 emu/g (M-II) are consistent with expected values for magnetite MNPs of observed sizes. Ferromagnetic resonance (FMR) measurements confirmed that MNPs of both types are magnetically homogeneous materials. FMR lines' position and line widths can be understood by invoking the local dipolar fields, deviations from sphericity, magnetocrystalline anisotropy and stresses. M-I sample shows sizeable zero field microwave absorption which is absent in the M-II case. The differences in microwave behaviour of M-I and M-II MNPs can be used in the design of microwave radiation absorbing multilayers. © 2015 Elsevier B.V. Source

Rostov V.V.,Institute of High Current Electronics | Elchaninov A.A.,Institute of High Current Electronics | Romanchenko I.V.,Institute of High Current Electronics | Yalandin M.I.,Institute of Electrophysics UD RAS
Applied Physics Letters | Year: 2012

A two-channel source of Cherenkov superradiance pulses with the electron-wave systems of identical geometry which is capable of producing 2 × 0.3 GW pulses of duration 2 ns and center frequency 10 GHz has been developed and explored. The channels are powered by a high-voltage driver whose pulse is split into two pulses that are sent through parallel transmission lines. To shorten the voltage rise time in each channel, identical NiZn ferrite-loaded coaxial transmission lines with independently controlled axial bias fields are used. © 2012 American Institute of Physics. Source

Morozov I.A.,Perm State University | Mamaev A.S.,Institute of Electrophysics UD RAS | Osorgina I.V.,Perm State University | Lemkina L.M.,Russian Academy of Sciences | And 4 more authors.
Materials Science and Engineering C | Year: 2016

The surface of elastic polyurethane treated by plasma immersion N2 + ion implantation at different fluences has been investigated. A folded surface structure is observed in all cases. Analysis has been performed to study the structural (roughness, steepness and fraction of folds, fractal characteristics), mechanical (stiffness, adhesion force between the AFM probe and the material) and wetting properties of surfaces. Under uniaxial stretching the cracks orthogonal to the axis of deformation and longitudinal folds are formed on the examined surfaces. After unloading the initial structure of the surface of deformed materials exposed to low fluences becomes smoother and does not recover, i.e. it has plastic properties. By contrast, the structure of the surfaces of materials subjected to high-fluence treatment recovers without visible changes and the cracks are fully closed. The study of Staphylococcus colonies grown on these materials has demonstrated significant reduction (from 3 to 5 times) in the vitality of bacteria on treated surfaces. This result was repeated on samples after 11 months of storage. Such antibacterial properties are primarily related to the structural changes of the surfaces accompanied by the increased hydrophilicity. © 2016 Elsevier B.V. All rights reserved. Source

Kurlyandskaya G.V.,University of the Basque Country | Kurlyandskaya G.V.,Ural Federal University | Fernandez E.,University of the Basque Country | Safronov A.P.,Ural Federal University | And 6 more authors.
Applied Physics Letters | Year: 2015

Thin-film based magnetoimpedance (MI) sensors were used for quantitative determination of the concentration of magnetic nanoparticles (MNPs) in ferrogels. Ferrogels (model systems for biological tissue) were synthesized by radical polymerization of acrylamide in a stable aqueous suspension of γ-Fe2O3 MNPs fabricated by laser target evaporation. MI [FeNi/Ti]3/Cu/[Ti/FeNi]3/Ti sensitive elements were prepared by sputtering. Thorough structural and magnetic studies of MNPs, ferrogels, and multilayered sensitive element insure the complete characterization of biosensor prototype. The MI response of the sensitive element was carefully evaluated in initial state and in the presence of ferrogels with different concentration of iron oxide MNPs from 0 to 2.44 wt. %, which produced systematic changes of the MI in a frequency span of 300 kHz to 400 MHz. © 2015 AIP Publishing LLC. Source

Safronov A.P.,Ural Federal University | Kurlyandskaya G.V.,University of the Basque Country | Bhagat S.M.,University of Maryland University College | Beketov I.V.,Institute of Electrophysics UD RAS | And 3 more authors.
Solid State Phenomena | Year: 2015

Spherical nickel nanoparticles were prepared by the electrical explosion of wire. The as prepared nanoparticles were modified immediately after fabrication at room temperature in order to provide tunable surface properties with focus on the development of composites filled with nanoparticles. Following liquid modificators were used: hexane, toluene and the solution of polystyrene in toluene. In one case the surface modification by carbon was made in gas phase as a result of hydrocarbon injection. The average size of the nanoparticles was about 50 nm and unit cell parameters were close to 0.351 nm. Detailed characterization was done by X-ray diffraction, transmission electron microscopy, and magnetization measurements. Sphericity was also checked using microwave resonant absorption. © (2015) Trans Tech Publications, Switzerland. Source

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