Now showing items 21-40 of 112

    • New fractional step Runge-Kutta-Nyström methods up to order three 

      Bujanda Cirauqui, Blanca Upna; Moreta, M. Jesús; Jorge Ulecia, Juan Carlos Upna (Elsevier, 2020)   Artículo / Artikulua
      Fractional Step Runge–Kutta–Nyströ (FSRKN) methods have been revealed to be an excellent option to integrate numerically many multidimensional evolution models governed by second order in time partial differential equations. ...
    • A comparative study in the tribological behavior of DLC coatings deposited by HiPIMS technology with positive pulses 

      García Lorente, José Antonio; Rivero Fuente, Pedro Upna; Barba Areso, Eneko; Fernández, Iván; Santiago, Jose A.; Palacio, José; Fuente, Gonzalo G.; Rodríguez Trías, Rafael Upna (MDPI, 2020)   Artículo / Artikulua  OpenAccess
      During the last few decades, diamond-like carbon (DLC) coatings were widely used for tribological applications, being an effective tool for improving the performance and the useful life of different machining tools. Despite ...
    • On the nonlinear stability of the triangular points in the circular spatial restricted three-body problem 

      Cárcamo Díaz, Daniela Jacqueline; Palacián Subiela, Jesús Francisco Upna; Vidal Díaz, Claudio; Yanguas Sayas, Patricia Upna (Pleiades Publishing, 2020)   Artículo / Artikulua
      The well-known problem of the nonlinear stability of L4 and L5 in the circular spatial restricted three-body problem is revisited. Some new results in the light of the concept of Lie (formal) stability are presented. In ...
    • Effects of a soft-core coulomb potential on the dynamics of a hydrogen atom near a metal surface 

      Iñarrea, Manuel; Lanchares, Víctor; Palacián Subiela, Jesús Francisco Upna; Pascual, Ana Isabel; Salas, José Pablo; Yanguas Sayas, Patricia Upna (Elsevier, 2019)   Artículo / Artikulua
      The goal of this paper is to investigate the effects that the replacement of the Coulomb potential by a soft-core Coulomb potential produces in the classical dynamics of a perturbed Rydberg hydrogen atom. As example, we ...
    • Experimental Stark widths and shifts of MnII spectral lines 

      Manrique Rosel, Javier; Aragón Garbizu, Carlos Upna; Aguilera Andoaga, José Antonio Upna (Oxford University Press, 2019)   Artículo / Artikulua  OpenAccess
      Stark widths and shifts of MnII lines with wavelengths in the range 2300-3500 Å have been measured by laser-induced breakdown spectroscopy. The use of fused glass samples with varying Mn concentrations has allowed minimization ...
    • On fixed point theory in partially ordered sets and an application to asymptotic complexity of algorithms 

      Estevan Muguerza, Asier Upna; Miñana, Juan José; Valero, Óscar (Springer, 2019)   Artículo / Artikulua  OpenAccess
      The celebrated Kleene fixed point theorem is crucial in the mathematical modelling of recursive specifications in Denotational Semantics. In this paper we discuss whether the hypothesis of the aforementioned result can be ...
    • Thermostructural behavior in a series of lanthanide-containing polyoxotungstate hybrids with copper(II) complexes of the tetraazamacrocycle cyclam: a single-crystal-to-single-crystal transformation study 

      Martín Caballero, Jagoba; Artetxe, Beñat; Reinoso, Santiago Upna; San Felices, Leire; Vitoria, Pablo; Larrañaga, Aitor; Vilas, José Luis; Gutiérrez Zorrilla, Juan M. (ACS Publications, 2019)   Artículo / Artikulua  OpenAccess
      A series of 14 isostructural [Cu(cyclam)](2)[{Cu(cyclam)}4{(a-GeW11O39)Ln(H2O)-(OAc)(12)].18H(2)O (1-Ln, where Ln = La Lu; cyclam = 1,4,8,11-tetraazacyclotetradecane) polyoxometalate-based hybrids reported herein represent ...
    • Pretreatment and enzymatic hydrolysis for the efficient production of glucose and furfural from wheat straw, pine and poplar chips 

      Cornejo Ibergallartu, Alfonso; Alegría Dallo, Irantzu; García Yoldi, Íñigo; Sarobe Martínez, Íñigo Upna; Sánchez, David; Otazu, Eduardo; Funcia, Ibai; Gil Idoate, María José Upna; Martínez Merino, Víctor (Elsevier, 2019)   Artículo / Artikulua
      A flexible approach to a two-step biorefinery for the production of glucose and furfural from three different feedstocks is presented. Pretreatment conditions were selected to drive the production towards the generation ...
    • 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 ...
    • Online relative risks/rates estimation in spatial and spatio-temporal disease mapping 

      Adin Urtasun, Aritz Upna; Goicoa Mangado, Tomás Upna; Ugarte Martínez, María Dolores Upna (Elsevier, 2019)   Artículo / Artikulua  OpenAccess
      Background and objective: Spatial and spatio-temporal analyses of count data are crucial in epidemiology and other fields to unveil spatial and spatio-temporal patterns of incidence and/or mortality risks. However, fitting ...
    • Outstanding role of the magnetic entropy in arrested austenite in an ordered Ni45Mn36.7In13.3Co5 metamagnetic shape memory alloy 

      Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna; Sánchez-Alarcos Gómez, Vicente Upna; Jiménez Ruiz, M.; Cesari, Eduard (Elsevier, 2019)   Artículo / Artikulua
      The relevance of the entropy and in particular the outstanding role of the magnetic contribution is analyzed in a non-equilibrium arrested austenite phase in a Ni 45 Mn 36.7 In 13.3 Co 5 metamagnetic shape memory alloy. ...
    • Reeb’s theorem and periodic orbits for a rotating Hénon–Heiles potential 

      Lanchares, Víctor; Pascual, Ana Isabel; Iñarreta, Manuel; Salas, José Pablo; Palacián Subiela, Jesús Francisco Upna; Yanguas Sayas, Patricia Upna (Springer, 2019)   Artículo / Artikulua
      We apply Reeb’s theorem to prove the existence of periodic orbits in the rotating Hénon– Heiles system. To this end, a sort of detuned normal form is calculated that yields a reduced system with at most four non degenerate ...
    • Self-referenced optical fiber sensor for hydrogen peroxide detection based on LSPR of metallic nanoparticles in layer-by-layer films 

      Goicoechea Fernández, Javier Upna; Rivero Fuente, Pedro Upna; Sada Oreja, Samuel; Arregui San Martín, Francisco Javier Upna (MDPI, 2019)   Artículo / Artikulua  OpenAccess
      Intensity-based optical fiber sensors are one of the most studied sensor approaches thanks to their simplicity and low cost. Nevertheless, their main issue is their lack of robustness since any light source fluctuation, ...
    • Layer-by-layer nano-assembly: a powerful tool for optical fiber sensing applications 

      Rivero Fuente, Pedro J. Upna; Goicoechea Fernández, Javier Upna; Arregui San Martín, Francisco Javier Upna (MDPI, 2019)   Artículo / Artikulua  OpenAccess
      The ability to tune the composition of nanostructured thin films is a hot topic for the design of functional coatings with advanced properties for sensing applications. The control of the structure at the nanoscale level ...
    • Improvement of the adsorption properties of an activated carbon coated by titanium dioxide for the removal of emerging contaminants 

      Taoufik, Nawal; Elmchaouri, Abdellah; Anouar, Fatna; Korili, Sophia A.; Gil Bravo, Antonio Upna (Elsevier, 2019)   Artículo / Artikulua
      Three activated carbon coated titanium dioxide composites are evaluated as adsorbents for the removal of three pharmaceutical compounds: clofibric, gallic and salicylic acids from aqueous solutions. These composite materials ...
    • Comparative removal of emerging contaminants from aqueous solution by adsorption on an activated carbon 

      Gil Bravo, Antonio Upna; Taoufik, Nawal; García Mora, Ana María; Korili, Sophia A. (Taylor & Francis, 2019)   Artículo / Artikulua  OpenAccess
      Batch sorption experiments were performed to study the adsorption of six emerging pollutants from aqueous solutions using a commercial granular activated carbon as adsorbent. Caffeine, clofibric acid, diclofenac, gallic ...
    • Zeolite synthesis from industrial wastes 

      Yoldi Sangüesa, María; Fuentes Ordóñez, Edwin Gustavo; Korili, Sophia A.; Gil Bravo, Antonio Upna (Elsevier, 2019)   Artículo / Artikulua
      Conventional synthesis conditions for each type of zeolite are tabulated and reported by the International Zeolite Association Structure Commission (IZA) and most of them are synthesized from commercial reagents, but they ...
    • A comparative study of multifunctional coatings based on electrospun fibers with incorporated ZnO nanoparticles 

      Rivero Fuente, Pedro J. Upna; Iribarren Zabalegui, Álvaro; Larumbe Abuin, Silvia Upna; Palacio, José; Rodríguez Trías, Rafael Upna (MDPI, 2019)   Artículo / Artikulua  OpenAccess
      In this work, polymeric fibers of polystyrene (PS) with incorporated ZnO nanoparticles have been deposited onto an aluminum alloy substrate (6061T6) by using the electrospinning technique. In order to optimize the deposition ...
    • Phenyl siloxane hybrid xerogels: structure and porous texture 

      Moriones Jiménez, Paula Upna; Echeverría Morrás, Jesús Upna; Parra, Bernardo; Garrido Segovia, Julián José Upna (Springer US, 2019)   Artículo / Artikulua  OpenAccess
      The aim of this research is to investigate the effect of phenyltriethoxysilane (PhTEOS) and tetraethoxysilane (TEOS) molar ratios as silicon precursors on the structure and porous texture of xerogels. We have prepared ...
    • Identification of a Ni-vacancy defect in Ni-Mn-Z (Z = Ga, Sn, In): an experimental and DFT positron-annihilation study 

      Unzueta, Iraultza; Sánchez-Alarcos Gómez, Vicente Upna; Recarte Callado, Vicente Upna; Pérez de Landazábal Berganzo, José Ignacio Upna; Zabala, Nerea; García, José Ángel; Plazaola, Fernando (American Physical Society, 2019)   Artículo / Artikulua  OpenAccess
      By means of experimental positron-annihilation-lifetime measurements and theoretical density functional theory (DFT) positron-lifetime calculations, vacancy-type defects in Ni50Mn50−xSnx (x = 25, 20, 15, 13, 10) and ...