Sorption and spatial distribution of protein globules in charged hydrogel particles

We have theoretically studied the uptake of a non-uniformly charged biomolecule, suitable to represent a globular protein or a drug, by a charged hydrogel carrier in the presence of a 1:1 electrolyte. Based on the analysis of a physical interaction Hamiltonian including monopolar, dipolar and Born (self-energy) contributions derived from linear electrostatic theory of the unperturbed homogeneous hydrogel, we have identified five different sorption states of the system, from complete repulsion of the molecule to its full sorption deep inside the hydrogel, passing through meta- and stable surface adsorption states. The results are summarized in state diagrams that also explore the effects of varying the electrolyte concentration, the sign of the net electric charge of the biomolecule, and the role of including excluded-volume (steric) or hydrophobic biomolecule-hydrogel interactions. We show that the dipole moment of the biomolecule is a key parameter controlling the spatial distribution of the globules. In particular, biomolecules with a large dipole moment tend to be adsorbed at the external surface of the hydrogel, even if like-charged, whereas uniformly charged biomolecules tend to partition towards the internal core of an oppositely-charged hydrogel. Hydrophobic attraction shifts the states towards internal sorption of the biomolecule, whereas steric repulsion promotes surface adsorption for oppositely-charged biomolecules, or the total exclusion for likely-charged ones. Our results establish a guidance for the spatial partitioning of proteins and drugs in hydrogel carriers, tuneable by hydrogel charge, pH and salt concentration.Comment: 16 pages, 5 figure

Las cosas de Richard Ford. Estampas varias sobre la vida y obra de un hispanista inglés en la España del siglo XIX.

Reseña: Medina Casado, Carmelo, y Ruiz Más, José (Eds.) 2010. Jaén: Servicio de Publicaciones de la Universidad de Jaén.308 Páginas.ISBN:978-84- 8439-540-9

Un testimonio de la Guerra de la Independencia: los viajes por Andalucía de Sophia Barnard

Drawing on several critical studies on travel writing, this article analyses the sections that Sophia Barnard devoted to Andalusia in her Travels in Algeirs [sic], Spain, &c., published in London in the mid-1820s. Married to a merchant, Barnard spent over three years of her life abroad. She did not travel extensively in Andalusia, but her narrative is nevertheless a valuable testimony of the situation of the area during the Peninsular War. She visited Cádiz when it was under bombardment by the French in 1811, and a few months later she was in Algeciras on one of her husband’s business trips. During her stay in Gibraltar she also recorded her impressions of the refugees in the British colony, being of particular interest her account of the epidemic that took many lives across the area in late 1812. Barnard uses the conventions of travel writing and the discourses of femininity and imperialism to portray Andalusia not as a Byronic Romantic land saturated with pleasurable experiences, but rather as a scenario full of perils and hardships where the Protestant female traveller may test her virtue as mother and wife, demonstrate her unwavering Christian faith, and also assert the supremacy of Great Britain. The same conventions enable her to justify her long residence in wartime Andalusia by fashioning herself before her readers not as a hedonistic female tourist in search of the picturesque but rather as a suffering traveller who has derived a spiritual benefit from her journeys in the area.Este trabajo parte de varios estudios críticos sobre la literatura de viajes para llevar a cabo un análisis de las secciones que Sophia Barnard dedicó a Andalucía en Travels in Algeirs [sic], Spain, &c., publicado en Londres a mediados de la década de 1820. Casada con un comerciante, Barnard pasó más de tres años de su vida en el extranjero. No viajó mucho por Andalucía, pero su relato es sin embargo un valioso testimonio sobre la situación de la zona durante la Guerra de la Independencia. Visitó Cádiz cuando estaba bajo el bombardeo de los franceses en 1811 y unos meses más tarde estuvo en Algeciras en uno de los viajes de negocios de su marido. Durante su estancia en Gibraltar también registró sus impresiones de los refugiados en la colonia británica, siendo de particular interés su relato de la epidemia que causó muchas muertes en la zona a finales de 1812. Barnard utiliza las convenciones de la literatura de viajes y discursos femeninos e imperialistas para retratar Andalucía no como una tierra byroniana saturada de experiencias placenteras, sino más bien como un marco lleno de peligros y dificultades donde la viajera protestante puede probar su virtud como madre y esposa, demostrar su inquebrantable fe cristiana, y también afirmar la supremacía de Gran Bretaña. Las mismas convenciones le permiten justificar su larga residencia en Andalucía en tiempos de guerra presentándose ante sus lectores no como una turista hedonista en busca de lo pintoresco, sino como una sufrida viajera que ha obtenido un beneficio espiritual de sus viajes por esa zona

Aeroelastic study of the flutter conditions of an aircraft wing

Aircraft wings are the responsible for planes to fly, they are the main structures providing lift so that the gravity is overcome. Therefore, one must ensure that instabilities do not appear because they can lead to fatal outcomes. Flutter is the most common instability that aircraft face, being of utmost importance to delay or eliminate its appearance. This work aims to create a MATLAB computational aeroelastic code that allows to couple the finite element structural development to an aerodynamic vortex method so to run a dynamic modal analysis which computes the flutter velocity of a parametrized wing. First, the wing geometry and parameters that affect its performance are defined, being the taper ratio, the sweep angle, the span, root and tip chord dimensions and a point mass simulating, for example, the engine. Then, the structural and aerodynamic coupling formulation and computational development are presented and, finally, the results of the parametric study are analyzed. Flutter can occur basically for bending and twisting motions and the results show clearly how important it is to distribute the inertia of a wing when computing the flutter speed, apart from making it have the most stiffness possible without adding much weight to the structure

Un nou model de sacralitat ibèrica : els espais rituals bastetans

Títol original: Un nuevo modelo de sacralidad ibérica : los espacios rituales bastetano

Randomly branching theta-polymers in two and three dimensions: Average properties and distribution functions

Motivated by renewed interest in the physics of branched polymers, we present here a detailed characterization of the connectivity and spatial properties of 2- and 3-dimensional single-chain conformations of randomly branching polymers under theta-solvent conditions obtained by Monte Carlo computer simulations. The first part of the work focuses on polymer average properties, such as the average polymer spatial size as a function of the total tree mass and the typical length of the average path length on the polymer backbone. In the second part, we move beyond average chain behavior and we discuss the complete distribution functions for tree paths and tree spatial distances, which are shown to obey the classical Redner-des Cloizeaux functional form. Our results were rationalized first by the systematic comparison to a Flory theory for branching polymers and next by generalized Fisher-Pincus relationships between scaling exponents of distribution functions. For completeness, the properties of theta-polymers were compared to their ideal (i.e., no volume interactions) as well as good-solvent (i.e., above the theta-point) counterparts. The results presented here complement the recent work performed in our group [A. Rosa and R. Everaers, J. Phys. A: Math. Theor. 49, 345001 (2016); J. Chem. Phys. 145, 164906 (2016); and Phys. Rev. E 95, 012117 (2017)] in the context of the scaling properties of branching polymers