Browsing by Author "Ortega, Francisco"

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    Alteración de signos vitales dentro de las 72 h previas a la activación de código azul en pacientes adultos hospitalizados de un hospital universitario
    (2018) Araos Baeriswyl, Esteban Andrés; Feuerhake, Teo; Mundaca, Manuel; Lara Hernández, Bárbara Alejandra; Ortega, Francisco; Aeschlimann del Río, Nicolás Alejandro; Eymin Lago, Gonzalo
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    Amphiphilic 2-ethyl hexyl methacrylate-b-N,N '-dimethylacrylamide diblock copolymer monolayer behaviour at the air-water interface
    (2015) Gargallo Gómez, Ligia Teresita; Becerra, Natalia; Encinas, Maria Victoria; Ortega, Francisco; Gonzalez Rubio, Ramon; Leiva Campusano, Ángel; Radić Foschino, Deodato D.
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    Equilibrium and Surface Rheology of Monolayers of Insoluble Polycations with Side Chains
    (AMER CHEMICAL SOC, 2009) Miranda, Beatriz; Hilles, Hani M.; Rubio, Ramon G.; Ritacco, Hernan; Radic, Deodato; Gargallo, Ligia; Sferrazza, Michele; Ortega, Francisco
    We have studied monolayers of poly(n-tetradecyl 4-vinylpyridinium-co-4-vinylpyridine) bromide with different degrees of quaternization at the air-water interface. The isotherms (surface pressure vs area) present several phase transitions: at low monolayer coverage, there is a phase transition over a characteristic area that increases on increasing the quaternization degree. This behavior can be rationalized in terms of a mean-field theory of 2D semiflexible polymeric chains and could be an indication of a disorder-order transition from a 2D isotropic liquid (IL) at low surface concentration to a 2D nematic phase (N) at higher concentrations, Low-frequency oscillatory strain experiments show that at low surface coverage the monolayers exhibit highly nonlinear behavior, even for low strain amplitude, whereas at higher surface coverage the response is linear for strains higher than 20%. In addition, stress relaxation experiments show a minimum in the characteristic times that coincide with the transition area. These unexpected results at low surface coverage might be characteristic of the system or related to the fact that the oscillatory experiments do not strictly correspond to constant surface-coverage conditions. However, they are in agreement with high-frequency viscoelasticity, obtained by surface quasielastic light scattering, that shows that the dilational viscosity is higher at low surface concentration than for concentrations beyond the surface phase transition. At higher coverage, there is a second phase transition, after which the isotherms present hysteresis, which is not observed below. Ellipsometry indicates that, after this transition, the monolayer thicken, which may be related to 3D growth into a multilayer.
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    Minimally Invasive Methods for Staging in Lung Cancer : Systematic Review and Meta-Analysis
    (2016) Labarca, Gonzalo; Aravena León, Carlos Andrés; Ortega, Francisco; Arenas, Alex; Majid, Adnan; Folch, Erik; Mehta, Hiren J.; Jantz, Michael A.; Fernandez Bussy, Sebastian
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    Thinking beyond implementation: context and culture in global mental health
    (BMJ Journals, 2020) Montenegro Cortés, Cristián; Ortega, Francisco