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Weissmann M.,Gerencia de Investigacion y Aplicaciones | Weht R.,Gerencia de Investigacion y Aplicaciones | Weht R.,National University of San Martín 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.


PubMed | Gerencia de Investigacion y Aplicaciones and Comision Nacional de la Energia Atomica
Type: Journal Article | Journal: Acta crystallographica. Section C, Structural chemistry | Year: 2016

Lamotrigine is a drug used in the treatment of epilepsy and related convulsive diseases. The drug in its free form is rather inadequate for pharmacological use due to poor absorption by the patient, which limits its bioavailability. On the other hand, the lamotrigine molecule is an excellent hydrogen-bonding agent and this has been exploited intensively in the search for better formulations. The formulation presently commercialized (under the brand name Lamictal) is rather complex and includes a number of anions in addition to the active pharmaceutical ingredient (API). The title salts of lamotrigine, namely 3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazin-2-ium 2-[(2-carboxyphenyl)disulfanyl]benzoate monohydrate, C


Jaroszewicz S.,Gerencia de Investigacion y Aplicaciones | Losada E.L.,Bariloche Atomic Center | Garces J.E.,Bariloche Atomic Center | Mosca H.O.,Gerencia de Investigacion y Aplicaciones
Journal of Nuclear Materials | Year: 2013

We present a study of structural, elastic and thermodynamic properties of tetragonal (C11b) U2Mo by means of density-functional theory based calculations using full-potential linearized augmented plane wave method. In this approach the generalized gradient approximation were used for the exchange-correlation potential calculation. The optimized lattice parameters are in excellent agreement with the experimental data. Through the Debye-Grüneisen model the temperature and pressure dependence of equation of state, bulk modulus, thermal expansion and specific heat have been obtained and discussed in the range of pressure 0-20 GPa and the temperature 0-800 K. © 2013 Elsevier B.V. All rights reserved.


Jaroszewicz S.,Gerencia de Investigacion y Aplicaciones | Mosca H.O.,Gerencia de Investigacion y Aplicaciones | Garces J.E.,Bariloche Atomic Center
Physica B: Condensed Matter | Year: 2012

An interatomic pair potential for Th was derived by using the Chen-Mobius lattice inversion of cohesive energy for fcc Th as a starting point to develop a free-parameter potential suitable to be used in molecular dynamic calculations for predicting microstructure evolution and thermal properties in multicomponent nuclear fuel. The cohesive energy versus lattice parameter of Th was computed from first principles electronic structure calculations. The elastic constants for fcc Th were calculated by applying different types of strain to the starting crystal. Based on this information, the shear modulus, the Youngs modulus and the Poissons ratio were obtained. The computed elastic constants of fcc Th are found to be in a good agreement with experiments and previous theoretical results. © 2011 Elsevier B.V. All rights reserved.


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.


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.


Minsky D.M.,Gerencia de Investigacion y Aplicaciones | Minsky D.M.,CONICET | Kreiner A.J.,Gerencia de Investigacion y Aplicaciones | Kreiner A.J.,CONICET | Valda A.A.,Gerencia de Investigacion y Aplicaciones
Applied Radiation and Isotopes | Year: 2011

A numerical optimization of a Beam Shaping Assembly (BSA) for Accelerator Based-Boron Neutron Capture Therapy (AB-BNCT) has been performed. The reaction 7Li(p,n)7Be has been considered using a proton beam on a lithium fluoride target. Proton energy and the dimensions of a simple BSA geometry have been varied to obtain a set of different configurations. The optimal configuration of this set is shown. © 2011 Elsevier Ltd.


Herrera M.S.,Gerencia de Investigacion y Aplicaciones | Herrera M.S.,CONICET | Gonzalez S.J.,Gerencia de Investigacion y Aplicaciones | Gonzalez S.J.,CONICET | And 4 more authors.
Physica Medica | Year: 2013

Purpose: Encouraging Boron Neutron Capture Therapy (BNCT) clinical results obtained in recent years have stimulated intense research to develop accelerator-based neutron sources to be installed in clinical facilities. In this work an assessment of an accelerator-based BNCT facility for the treatment of different tumor targets was performed, comparing the accelerator-derived results with reported reactor-based trials under similar conditions and subjected to the same clinical protocols. Materials and methods: A set of real image studies was used to cover clinical-like cases of brain and head-and-neck tumors. In addition, two clinical cases of malignant nodular melanoma treated at the RA-6 BNCT facility in Argentina were used to thoroughly compare the clinical dosimetry with the accelerator-derived results. Results: The minimum weighted dose delivered to the clinical target volume was higher than 30 Gy and 14 Gy for the brain tumor and head-and-neck cases, respectively, in agreement with those achieved in clinical applications. For the melanoma cases, the minimum tumor doses were equal or higher than those achieved with the RA-6 reactor for identical field orientation and protocol. The whole-body dose assessment showed that the maximum photon-equivalent doses for those normal organs close to the beam direction were below the upper limits considered in the protocols used in the present work. Conclusions: The obtained results indicate not only the good performance of the proposedbeam shaping assembly design associated to the facility but also the potential applicability of accelerator-based BNCT in the treatment of both superficial and deep-seated tumors. © 2013 Associazione Italiana di Fisica Medica.


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.


Ghenzi N.,Gerencia de Investigacion y Aplicaciones | Stoliar P.,Gerencia de Investigacion y Aplicaciones | Fuertes M.C.,Gerencia Quimica | Marlasca F.G.,Gerencia de Investigacion y Aplicaciones | Levy P.,Gerencia de Investigacion y Aplicaciones
Physica B: Condensed Matter | Year: 2012

We study the electric pulse induced resistance switching of TiO 2-Ag contacts at room temperature, exploring both unipolar and bipolar switching modes. Initially we observed unipolar response. After hundred pulsing cycles the unipolar switching response vanishes but the device can still be operated in bipolar switching regime. The underlying mechanism for resistance switching is modeled in terms of formation and rupture of filament, and movement of oxygen vacancies. © 2012 Elsevier B.V.

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