Flow Blurring-Enabled Production of Polymer Filaments from Poly(ethylene oxide) Solutions

Flow blurring (FB) atomizers are relatively simple yet robust devices used for the generation of sprays from solutions of a wide range of viscosities. In this work, we have demonstrated that FB devices may also be applied for massive production of liquid filaments from polymeric solutions. They can later be transformed into solid filaments and fibers, leading to the production of so-called fiber mats. The liquid precursors consisted of poly(ethylene oxide) (PEO) solutions of varying molecular weights (105 [100k] to 4 × 106 g/mol [4M]) and concentrations. The FB device was operated in the gas pressure range of 3−6 bar. Except for solutions of PEO 100k, all solutions exhibited a shear thinning behavior. For massive filament production, a threshold polymer concentration (ct) was identified for each molecular weight. Below such concentration, the atomization resulted in droplets (the classical FB functioning mode). Such a threshold value decreased as the PEO molecular weight increased, and it coincides with the polymer coil overlap concentration, c*. The viscoelastic nature of the solutions was also observed to increase with the molecular weight. A 3.2 dependency of the zero-shear rate viscosity on a so-called Bueche parameter was found for filament production, whereas a nearly linear dependency was found for droplet production. In general, the mean diameter of the filaments decreased as they traveled downstream from the atomization point. Furthermore, at a given distance from the atomizer outlet and gas pressure, the mean filament diameter slightly shifted toward larger sizes with increasing PEO molecular weight. The tendency agrees well with the calculated filaments’ Deborah number, which increases with PEO molecular weight. The approach presented herein describes a highthroughput and efficient method for the massive production of viscous filaments. These may be transformed into fibers by an on-line drying step.Ministerio de Economía y Competitividad DPI2016-78887-C3-1-

Los principios del conservadurismo político

Las pretensiones del autor son: (i) Mostrar cómo el conservadurismo político se sostiene en una concepción de la naturaleza humana de corte racionalista, que, oponiéndose al modelo antropológico de Hobbes, reconoce tanto el poder de la razón sobre los afectos como una debilidad intrínseca en el hombre que no ha de confundirse con inclinación natural al mal. En este sentido, la política moderada del conservadurismo resulta de su pesimismo mitigado. (ii) Señalar cómo de acuerdo con este paradigma político los criterios de legitimidad política son la protección de las minorías, la preservación de la igualdad de derechos y el mantenimiento de una libertad racional de la que participan por igual todos los miembros del cuerpo político; es decir, cómo la medida de la legitimidad es el imperio de la ley. (iii) Finalmente, subrayar que porque para que exista Estado de derecho la ley no puede estar sujeta a voluntad particular alguna, sea de un individuo o de una mayoría, el conservadurismo es baluarte de una democracia constitucionalista que es condición natural de la naturaleza humana

El giro epistemológico en la analítica

Las pretensiones del autor son: (i) Describir los rasgos metafilosóficos de las dos corrientes dominantes en el pensamiento analítico contemporáneo: el relativismo terapéutico y el naturalismo; subrayando la crisis de identidad de la filosofía que configura su trasfondo y deteniéndose especialmente en el análisis del programa quineano de naturalización de la epistemología. (ii) Realizar una evaluación de dichas tendencias que desemboca en la defensa de un humanismo crítico, de una concepción autónoma y sustantiva de la actividad filosófica y de la necesaria conciliación de lógica y ética. (iii) Mostrar cómo la superación del divorcio entre verdad y significado y la recusación del principio de aislamiento constituyen el hilo conductor de tres de los filósofos más sobresalientes en el panorama anglosajón del último siglo: Wittgenstein, Davidson y Sosa.We pretend: (i) To describe the metaphilosophical views pertaining to the two main trends in contemporary analytical philosophy: therapeutic relativism and naturalism; stressing how they must be understood against the background of the present crisis of identity in philosophy and focusing on Quine's project of a naturalized epistemology. (ii) To assess those trends, evaluation which results in our support to a critical humanism, to the autonomous and substantive character of philosophical theses and methods and to the agreement between logic and ethics. (iii) Finally, to show how the overcoming of the divorce between truth and meaning and the rejection of the principle of insulation are elements deeply ingrained in the writings of the most daring and original philosophers of the last century: Wittgenstein, Davidson and Sosa

Higher-order Cartan symmetries in k-symplectic field theory

For k-symplectic Hamiltonian field theories, we study infinitesimal transformations generated by certain kinds of vector fields which are not Noether symmetries, but which allow us to obtain conservation laws by means of a suitable generalization of the Noether theorem.Comment: 11 page