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José de San Martín, Argentina

Soto Espinoza S.L.,National University of Quilmes | Arbeitman C.R.,Gerencia de Investigacion y Aplicaciones | Clochard M.C.,Ecole Polytechnique - Palaiseau | Grasselli M.,National University of Quilmes
Radiation Physics and Chemistry | Year: 2014

The application of swift-heavy ion bombardment to polymers is a well-established technique to manufacture micro- and nanopores onto polymeric films to obtain porous membranes. A few years ago, it was realized that, during ion bombardment, the high energy deposition along the ion path through the polymer reached cylindrical damage regions corresponding to the core trace and the penumbra. After the etching procedure, there are still enough active sites left in the penumbra that can be used to initiate a polymerization process selectively inside the membrane pores.In this study, we report the grafting polymerization of glycidyl methacrylate onto etched PET foils to obtain functionalized nanochannels. Grafted polymers were labeled with a fluorescent tag and analyzed by different fluorescence techniques such as direct fluorescence, fluorescence microscopy and confocal microscopy. These techniques allowed identifying and quantifying the grafted regions on the polymeric foils. © 2013 Elsevier Ltd. Source

Martinez E.D.,Gerencia de Quimica | Granja L.,Gerencia de Investigacion y Aplicaciones | Bellino M.G.,Gerencia de Quimica | Soler-Illia G.J.A.A.,Gerencia de Quimica
Physical Chemistry Chemical Physics | Year: 2010

The space-resolved electrical conductivity of patterned silver nanoparticle (NP) arrays embedded in mesoporous TiO2 thin films was locally evaluated using a conductive-tip AFM. A remarkable conductivity dependence on the film mesostructure and metal NP loading was observed, confirming a three-dimensional current flow throughout the nanocomposite. © 2010 the Owner Societies. Source

Weissmann M.,Gerencia de Investigacion y Aplicaciones | Weht R.,Gerencia de Investigacion y Aplicaciones | Weht R.,National University of San Martin of Argentina
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Ab initio calculations using the local spin-density approximation plus Hubbard U (LSDA+U) method have been performed for the three reported phases of Ti 4O 7. Using the experimental structural parameters, we find that the electronic and magnetic properties are qualitatively different for each phase. The low-temperature structure is an antiferromagnetic semiconductor, with bipolarons arranged symmetrically in chains, separated by other nonmagnetic ion chains. The intermediate-temperature structure also contains bipolarons, but in a much more complicated order, in addition to unpaired magnetic Ti3 + ions and nonmagnetic Ti4 + ions. It has a smaller band gap than the low-temperature one. The high-temperature structure is metallic, and different distributions of Ti3 + and Ti4 + ions can be found that are almost degenerate. © 2011 American Physical Society. Source

Minsky D.M.,Gerencia de Investigacion y Aplicaciones | Minsky D.M.,CONICET | Kreiner A.J.,Gerencia de Investigacion y Aplicaciones | Kreiner A.J.,CONICET
Applied Radiation and Isotopes | Year: 2014

Within the framework of accelerator-based BNCT, a project to develop a folded Tandem-ElectroStatic-Quadrupole accelerator is under way at the Atomic Energy Commission of Argentina. The proposed accelerator is conceived to deliver a proton beam of 30mA at about 2.5MeV. In this work we explore a Beam Shaping Assembly (BSA) design based on the 7Li(p,n)7Be neutron production reaction to obtain neutron beams to treat deep seated tumors. © 2013 Elsevier Ltd. Source

Rodriguez M.G.,Laboratorio Of Bajas Temperaturas | Polla G.,Gerencia de Investigacion y Aplicaciones | Ramos C.P.,Gerencia de Investigacion y Aplicaciones | Acha C.,Laboratorio Of Bajas Temperaturas
Journal of Alloys and Compounds | Year: 2015

Abstract We have carried out an investigation of the structural, magnetic, transport and superconducting properties of Fe1+zTe1-x-ySexSy ceramic compounds, for z = 0 and some specific Se (0 ≤ x ≤ 0.5) and S (0 ≤ y ≤ 0.12) contents. The incorporation of Se and S to the FeTe structure produces a progressive reduction of the crystallographic parameters as well as different degrees of structural disorder associated with the differences of the ionic radius of the substituting cations. In the present study, we measure transport properties of this family of compounds and we show the direct influence of disorder in the normal and superconductor states. We notice that the structural disorder correlates with a variable range hopping conducting regime observed at temperatures T > 200 K. At lower temperatures, all the samples except the one with the highest degree of disorder show a crossover to a metallic-like regime, probably related to the transport of resilient-quasi-particles associated with the proximity of a Fermi liquid state at temperatures below the superconducting transition. Moreover, the superconducting properties are depressed only for that particular sample, in accordance to the condition that superconductivity is affected by disorder when the electronic localization length ξL becomes smaller than the coherence length ξSC. © 2015 Elsevier B.V. Source

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