Persona:
Ortega Coloma, Francisco Javier

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0000-0002-7431-354X
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Ortega Coloma
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Francisco Javier
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2018 - 201922020 - 20242
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Mostrando 1 - 4 de 4
  • Miniatura
    Publicación
    Linear shear rheology of aging β-casein films adsorbing at the air/water interface
    (Elsevier, 2018-02-01) Martínez Pedrero, F.; Sánchez Puga, Pablo; Chulia Jordan, R.; González Rubio, Ramón; Tajuelo Rodríguez, Javier; Ortega Coloma, Francisco Javier; Rubio Álvarez, Miguel Ángel
    In this work, the viscoelasticity of fragile β-casein films has been followed using different macro- and microrheological techniques. The modulus of the complex surface viscosity varies with time, allowing for the monitoring of the protein adsorption and annealing. β-casein adsorption creates a soft glassy gel at the interface that experiences an aging process. Macrorheological experiments with multiple probe sizes in addition to microrheological experiments demonstrated the consistency of the surface rheological properties over a broad range of viscosities. Surface pressure measurements were performed to complement the characterization of the processes.
  • Miniatura
    Publicación
    Shear rheology of fluid interfaces: Closing the gap between macro- and micro-rheology
    (Elsevier, 2018-09) Guzmán Solís, Eduardo; Pastor Ruiz, Juan Manuel; González Rubio, Ramón; Tajuelo Rodríguez, Javier; Rubio Álvarez, Miguel Ángel; Ortega Coloma, Francisco Javier
    For many years the determination of the shear viscosity of interfacial layers has been source of strong controversy. This is mainly because different techniques provided different values of such parameter, which leads in many cases to a puzzling interpretation of the experimental results. One possible explanation of this is the non-correct analysis of the hydrodynamic conditions of the measurement and, in particular, the assumption of some approximations that may not be necessarily valid in all cases. The introduction of hydrodynamic consideration in the study of interfacial shear rheology has helped to clarify some of the existing discrepancies between measurements performed using different devices, thus allowing one to establish clearly the viscosity range in which different techniques can operate with enough sensitivity for determining the interfacial shear viscosity. This review puts in perspective the most recent developments on the studies of the interfacial shear rheology of fluid/fluid interfaces, analyzing the strength and weakness of the different approaches.
  • Miniatura
    Publicación
    A new Crocodyloidea from the middle Eocene of Zamora (Duero Basin, Spain)
    (Wiley, 2024-03-05) Narváez Padilla, Iván; Celis, Ane de; Escaso Santos, Fernando; Martín de Jesús, Santiago; Pérez García, Adán; Ortega Coloma, Francisco Javier
    The eusuchian crocodyliforms recorded in the Eocene levels of the Spanish Duero Basin belong to three lineages: Planocraniidae, with the species Duerosuchus piscator; Alligatoroidea, represented by several specimens of the genus Diplocynodon; and Crocodyloidea, which includes several specimens traditionally attributed to Asiatosuchus. The genus Asiatosuchus, established in 1940 based on a middle Eocene species from Mongolia, has subsequently served as a wastebasket taxon for Paleogene remains belonging to several species, not only from Asia but also belonging to the European and North American records. Many of these species are known by highly fragmentary remains, sharing the presence of characters such as a flat and triangular skull, and long symphyses in the lower jaw, recognized as characteristic for the crocodyloids. In addition to isolated cranial remains, among the material traditionally attributed to Asiatosuchus at the Duero Basin stands out a nearly complete skull and a left mandible, from the middle Eocene area of Casaseca de Campeán (Zamora Province). The present study analyses in detail these specimens, previously reported during the 1980s, but analyzed in a very preliminary way. They are included for the first time in a phylogenetic analysis to establish the systematic position of this Spanish form. The results confirm that it corresponds to a new species of basal crocodyloid, defined here as Asiatosuchus oenotriensis sp. nov.
  • Miniatura
    Publicación
    New data on the shell anatomy of Selenemys lusitanica, the oldest known pleurosternid turtle in Europe
    (Springer, 2024) Pérez García, Adán; Camilo, Bruno; Ortega Coloma, Francisco Javier
    One of the most diverse turtle lineages in the Upper Jurassic and Lower Cretaceous record of Europe is that of the stem turtles Pleurosternidae (Paracryptodira), also distributed in North America. The oldest European representative of this lineage is the Portuguese Selenemys lusitanica, known from upper Kimmeridgian to lower Tithonian levels (Late Jurassic). The information on the shell of this taxon is so far very limited, being exclusively restricted to that provided in the publication in which the taxon was defined. New specimens from several upper Kimmeridgian to Tithonian localities in the Consolação Sub-basin of the Portuguese Lusitanian Basin, both from the Leiria District and the Lisbon District, are studied here. They include the most complete shell of the species found so far, as well as several isolated plates that allow us to improve knowledge about it. Thus, new information about the shell anatomy of Selenemys lusitanica is provided, but also about its intraspecific variability.