Now showing items 1-20 of 27

    • Magnetocaloric effect enhancement driven by intrinsic defects in a Ni45Co5Mn35Sn15 alloy 

      Sánchez-Alarcos Gómez, Vicente Upna; López García, Javier Upna; Unzueta, Iraultza; Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna; Beato López, Juan Jesús Upna; García, José Ángel; Plazaola, Fernando; Rodríguez Velamazán, José Alberto (Elsevier, 2019)   Artículo / Artikulua
      The influence of mechanically-induced defects on the magnetostructural properties is analyzed in a Ni-Co-Mn-Sn alloy subjected to soft milling and subsequent annealing treatments. It is found that, opposite to what occurs ...
    • Strong angular dependence of resonant states in 2D dielectric cylinder rings 

      Andueza Unanua, Ángel María Upna; Pérez Conde, Jesús Upna; Sevilla Moróder, Joaquín Upna (AIP Publishing, 2018)   Artículo / Artikulua  OpenAccess
      We investigate collective resonators made of dielectric cylinders assembled as two-dimensional regular octagons and decagons. These structures exhibit collective resonance states that change their intensity with the incident ...
    • Loss of ductility due to the decarburation and Mn depletion of a coarse-grained TWIP steel 

      Cuevas Jiménez, Fernando de las Upna; Gil Sevillano, Javier (Consejo Superior de Investigaciones Científicas (CSIC), 2017)   Artículo / Artikulua  OpenAccess
      Se ha observado una clara transición de la ductilidad a tracción con el tamaño de grano D del orden 15 μm - 20 μm (1,50 μm ≤ D < 50 μm) en un acero TWIP, 22% de Mn, 0,6% de C (% en masa). Este comportamiento es una combinación ...
    • Structurally oriented nano-sheets in Co thin films: changing their anisotropic physical properties by thermally-induced relaxation 

      Vergara Platero, José Upna; Favieres Ruiz, Cristina Upna; Magén, César; Teresa, José María de; Ibarra, Manuel Ricardo; Madurga Pérez, Vicente Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      We show how nanocrystalline Co films formed by separated oblique nano-sheets display anisotropy in their resistivity, magnetization process, surface nano-morphology and optical transmission. After performing a heat treatment ...
    • Entropy change caused by martensitic transformations of ferromagnetic shape memory alloys 

      L'vov, Victor A.; Cesari, Eduard; Kosogor, Anna; Torrens Serra, Joan; Recarte Callado, Vicente Upna; Pérez de Landazábal Berganzo, José Ignacio Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      In this paper, our most recent findings on the influence of magnetic order on the main transformational caloric and elastic properties of shape memory alloys (SMAs) are reviewed. It is argued that ferromagnetic order has ...
    • Study of optical fiber sensors for cryogenic temperature measurements 

      Miguel Soto, Verónica de Upna; Leandro González, Daniel Upna; López Aldaba, Aitor Upna; Beato López, Juan Jesús Upna; Pérez de Landazábal Berganzo, José Ignacio Upna; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      In this work, the performance of five different fiber optic sensors at cryogenic temperatures has been analyzed. A photonic crystal fiber Fabry-Pérot interferometer, two Sagnac interferometers, a commercial fiber Bragg ...
    • Giant direct and inverse magnetocaloric effect linked to the same forward martensitic transformation 

      Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna; Sánchez-Alarcos Gómez, Vicente Upna; Beato López, Juan Jesús Upna; Rodríguez Velamazán, José Alberto; Sánchez Marcos, J.; Gómez Polo, Cristina Upna; Cesari, Eduard (Springer Nature, 2017)   Artículo / Artikulua  OpenAccess
      Metamagnetic shape memory alloys have aroused considerable attraction as potential magnetic refrigerants due to the large inverse magnetocaloric effect associated to the magnetic-field-induction of a reverse martensitic ...
    • Low field magnetic and thermal hysteresis in antiferromagnetic dysprosium 

      Liubimova, Iuliia; Corró Moyá, Miguel; Torrens Serra, Joan; Recarte Callado, Vicente Upna; Pérez de Landazábal Berganzo, José Ignacio Upna; Kustov, Sergey (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      Magnetic and thermal hysteresis (difference in magnetic properties on cooling and heating) have been studied in polycrystalline Dy (dysprosium) between 80 and 250 K using measurements of the reversible Villari effect and ...
    • Interferometric vs wavelength selective optical fiber sensors for cryogenic temperature measurements 

      Miguel Soto, Verónica de Upna; Leandro González, Daniel Upna; López Aldaba, Aitor Upna; Beato López, Juan Jesús Upna; Pérez de Landazábal Berganzo, José Ignacio Upna; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel Upna (SPIE, 2017)   Contribución a congreso / Biltzarrerako ekarpena  OpenAccess
      In this work, a preliminary study of the behavior of two different interferometric fiber optic sensors and two different wavelength selective fiber optic sensors is performed. A photonic cristal fiber Fabry-Pérot interferometer, ...
    • 119Sn Mössbauer spectroscopy for assessing the local stress and defect state towards the tuning of Ni-Mn-Sn alloys 

      Unzueta, Iraultza; López García, Javier Upna; Sánchez-Alarcos Gómez, Vicente Upna; Recarte Callado, Vicente Upna; Pérez de Landazábal Berganzo, José Ignacio Upna (AIP Publishing, 2017)   Artículo / Artikulua  OpenAccess
      The influence of defects and local stresses on the magnetic properties and martensitic transformation in Ni50Mn35Sn15 is studied at macroscopic and atomic scale levels. We show that both the structural and magnetic properties ...
    • Thermal degradation of type I collagen from bones 

      Lambri, M. L.; Giordano, E. D.; Bozzano, P. B.; Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna (Tech Science Press, 2016)   Artículo / Artikulua  OpenAccess
      The denaturation processes of collagen in the temperature range between 450 K and 670 K are revealed through studies performed on cow rib bones by means of mechanical spectroscopy, differential scanning calorimetry, ...
    • Method for measurement of transition probabilities by laser-induced breakdown spectroscopy based on CSigma graphs. Application to Ca II spectral lines 

      Aguilera Andoaga, José Antonio Upna; Aragón Garbizu, Carlos Upna; Manrique Rosel, Javier (Elsevier, 2015)   Artículo / Artikulua  OpenAccess
      We propose a method for determination of transition probabilities by laser-induced breakdown spectroscopy that avoids the error due to self-absorption. The method relies on CSigma graphs, a generalization of curves of ...
    • Simple fabrication of ultrahigh aspect ratio nanostructures for enhanced antireflectivity 

      Domínguez Fernández, Sagrario; Cornago Santos, Ignacio; Bravo Larrea, Javier Upna; Pérez Conde, Jesús Upna; Choi, Hyungryul J.; Kim, Jeong-Gil; Barbastathis, George (American Vacuum Society, 2014)   Artículo / Artikulua  OpenAccess
      In this work, the authors present a novel fabrication process to create periodic nanostructures with aspect ratio as high as 9.6. These nanostructures reduce spectral reflectance of silicon to less than 4% over the broad ...
    • CSigma graphs: a new approach for plasma characterization in laser-induced breakdown spectroscopy 

      Aragón Garbizu, Carlos Upna; Aguilera Andoaga, José Antonio Upna (Elsevier, 2014)   Artículo / Artikulua  OpenAccess
      A generalization of curves of growth called CSigma (Cσ) graphs, which allows including several lines of various elements in the same ionization state at different concentrations, is proposed for laser-induced breakdown ...
    • Long-range atomic order and entropy change at the martensitic transformation in a Ni-Mn-In-Co metamagnetic shape memory alloy 

      Sánchez-Alarcos Gómez, Vicente Upna; Recarte Callado, Vicente Upna; Pérez de Landazábal Berganzo, José Ignacio Upna; Cesari, Eduard; Rodríguez Velamazán, José Alberto (MDPI, 2014)   Artículo / Artikulua  OpenAccess
      The influence of the atomic order on the martensitic transformation entropy change has been studied in a Ni-Mn-In-Co metamagnetic shape memory alloy through the evolution of the transformation temperatures under high-temperature ...
    • Síntesis, caracterización y aplicaciones de nanoestructuras magnéticas basadas en óxidos de metales de transición 

      Larumbe Abuin, Silvia Upna (2014)   Tesis doctoral / Doktoretza tesia  OpenAccess
      Como objetivo principal de esta tesis se plantea la preparación de sistemas híbridos constituídos por nanoestructuras del tipo NM@SiO2@X-TiO2 (NM: núcleo magnético; X: elemento dopante) con actividad fotocatalítica en el ...
    • People exposed to traffic noise in european agglomerations from noise maps: a critical review 

      Arana Burgui, Miguel Upna; San Martín Murugarren, Ricardo Upna; Salinas Hilburg, Juan Carlos (De Gruyter, 2014)   Artículo / Artikulua  OpenAccess
      Two of the main objectives of the European Directive on environmental noise are, firstly, to unify acoustic indices for assessing environmental noise and, secondly, to standardize assessment methodologies. The ultimate ...
    • Experimental Stark widths and shifts of Cr II spectral lines 

      Aguilera Andoaga, José Antonio Upna; Aragón Garbizu, Carlos Upna; Manrique Rosel, Javier (Oxford University Press, 2013)   Artículo / Artikulua  OpenAccess
      Stark widths and shifts of Cr II lines with wavelengths in the range 2000–3500 Å have been determined by laser-induced breakdown spectroscopy. The spectra have been measured at different instants of the plasma ...
    • A comprehensive analysis of the absorption spectrum of conducting ferromagnetic wires 

      Liberal Olleta, Íñigo Upna; Ederra Urzainqui, Íñigo Upna; Gómez Polo, Cristina Upna; Labrador Otamendi, Alberto; Pérez de Landazábal Berganzo, José Ignacio Upna; Gonzalo García, Ramón Upna (IEEE, 2012)   Artículo / Artikulua  OpenAccess
      A detailed analysis of the absorption spectrum of conductive ferromagnetic wires is presented. The absorption spectrum is computed from the solution to the scattering problem, and circuit models are formulated to clarify ...
    • Magnetic anisotropy in isotropic and nanopatterned strongly exchange-coupled nanolayers 

      Vergara Platero, José Upna; Favieres Ruiz, Cristina Upna; Madurga Pérez, Vicente Upna (Springer, 2012)   Artículo / Artikulua  OpenAccess
      In this study, the fabrication of magnetic multilayers with a controlled value of the in-plane uniaxial magnetic anisotropy field in the range of 12 to 72 kA/m was achieved. This fabrication was accomplished by the ...