Thermodynamics and dynamics of flowing polymer solutions and blends

Passem revista a les idees bàsiques i els principals resultats dels nostres estudis sobre els efectes induïts per gradients de velocitat en dissolucions i mescles de polímers, en què es combinen les descripcions hidrodinàmica i termodinàmica. La contribució del flux hidrodinàmic a l'energia lliure de la dissolució és descrita en el marc de la termodinàmica irreversible estesa, que estableix una relació entre les equacions constitutives viscoelàstiques i una entropia de noequilibri que depèn del tensor de pressions viscoses. Per diferenciació d'aquesta, s'obté l'equació d'estat per al potencial químic de no-equilibri, el qual, en presència de gradients de velocitat, acobla el flux de difusió amb la pressió viscosa. En certes condicions, aquesta influència fa que un sistema que en repòs seria unifàsic esdevingui inestable i es descompongui en dues fases, tot provocant, així, un desplaçament de la línia espinodal en el diagrama de fases. L'anàlisi teòrica està basada en l'estabilitat de les equacions de balanç de massa i de quantitat de moviment, de les equacions constitutives per al flux de difusió i el tensor de pressions viscoses, i de l'equació d'estat per al potencial químic de no-equilibri. Les prediccions concorden qualitativament amb les observacions experimentals conegudes. Presentem resultats per a dissolucions polimèriques diluïdes i concentrades i per a mescles de polímers.We review the basic ideas and main results of our analysis of shear-induced effects in polymer solutions and blends. The analysis combines thermodynamic and hydrodynamic descriptions. The flow contribution to the free energy of the solution is described in the framework of extended irreversible thermodynamics, which relates the viscoelastic constitutive equations to a non-equilibrium entropy that depends on the viscous pressure tensor. This yields, by differentiation, the corresponding non-equilibrium equation of state for the chemical potential, which couples diffusion flux to viscous pressure in the presence of a flow. In some conditions, the one-phase system becomes unstable and splits into two phases, leading to a shift in the spinodal line. The theoretical analysis is based on the stability of the mass and momentum balance equations, the constitutive equations for viscous pressure tensor and diffusion flux, and the equation of state for the chemical potential. The resulting predictions corroborate qualitatively the known experimental observations. Results for dilute and entangled polymer solutions and for polymer blends are given

Legendre transform in the thermodynamics of flowing polymer solutions

We propose a Legendre transform linking two different choices of nonequilibrium variables (viscous pressure tensor and configuration tensor) in the thermodynamics of flowing polymer solutions. This may avoid some current confusions in the analysis of thermodynamic effects in polymer solutions under flow

Shear-induced shift of spinodal line in entangled polymer blends

We study the shear-flow effects on phase separation of entangled polymer blends by incorporating into the chemical potential a nonequilibrium contribution due to the flow. The results are compared with those of a previous analysis by other authors which did not modify the chemical potential but used a different assumption for the stress tensor of the blend

Thermodynamics and dynamics of flowing polymer solutions and blends

We review the basic ideas and main results of our analysis of shear-induced effects in polymer solutions and blends. The analysis combines thermodynamic and hydrodynamic descriptions. The flow contribution to the free energy of the solution is described in the framework of extended irreversible thermodynamics, which relates the viscoelastic constitutive equations to a non-equilibrium entropy that depends on the viscous pressure tensor. This yields, by differentiation, the corresponding non-equilibrium equation of state for the chemical potential, which couples diffusion flux to viscous pressure in the presence of a flow. In some conditions, the one-phase system becomes unstable and splits into two phases, leading to a shift in the spinodal line. The theoretical analysis is based on the stability of the mass and momentum balance equations, the constitutive equations for viscous pressure tensor and diffusion flux, and the equation of state for the chemical potential. The resulting predictions corroborate qualitatively the known experimental observations. Results for dilute and entangled polymer solutions and for polymer blends are given

Cooperación en innovación tecnológica: un análisis comparado

El objetivo de este trabajo consiste en analizar la cooperación en Investigación, Desarrollo e innovación tecnológica que realizan las empresas que forman parte de uno de los instrumentos de apoyo a la innovación más empleados por la política tecnológica en los últimos años, los Parques Científicos y Tecnológicos. En dichos parques se ubican empresas innovadoras y de base tecnológica, Centros e Institutos Tecnológicos, por tanto, en este espacio se da el caldo de cultivo idóneo para que surjan sinergias y se produzca dicha cooperación. Para lograr nuestro objetivo, primero caracterizamos a las empresas de los parques seleccionados, y posteriormente realizamos un análisis de la cooperación en Investigación, Desarrollo e innovación tecnológica que realizan dichas empresas con el fin de extraer conclusiones sobre la situación en la que se encuentra dicha cooperación.The aim of this paper consists of analyzing the cooperation in Investigation, Development and technological innovation that make the companies that in the last comprise of one of the instruments of support to the innovation more used by the technological policy years, the Science and Technology Parks. In these parks innovating companies are located and of technological base, Technological Centers and Institutes, therefore, in this space the broth of suitable culture occurs so this cooperation takes place. In order to obtain our objective, first we characterized to the companies of the selected parks, and later we made an analysis of the cooperation in Investigation, Development and technological innovation that make these companies with the purpose of drawing conclusions on the situation in which is this cooperation

Service learning and health education: Innovation in nursing education

In an interdisciplinary service-learning project, students from the Universitat de Barcelona held a series of workshops and lectures for secondary-school students. Lectures related to healthcare and education were offered within the framework of Community Nursing, a 3rd-year subject in the bachelor's degree programme in Nursing. The objectives were to share knowledge between university students and secondary-school students on topics of mutual interest for their training, to develop health education skills and teamwork skills

Aprendiendo a educar para la salud a través del aprendizaje servicio. Compartir ideas, la universidad va al instituto

Se parte de un proyecto de aprendizaje servicio transversal de desarrollo de un ciclo de conferencias taller a estudiantes de secundaria realizadas por estudiantes de la UB. Por parte del grado en enfermería se proponen conferencias relacionadas con el cuidar y la educación para la salud. Los objetivos son compartir conocimientos entre estudiantes universitarios y de secundaria sobre temas de interés mutuo para su formación; adquirir habilidades en educación para la salud y trabajo en equipo

Automatic quantification of cardiomyocyte dimensions and connexin 43 lateralization in fluorescence images

Cardiomyocytes’ geometry and connexin 43 (CX43) amount and distribution are structural features that play a pivotal role in electrical conduction. Their quantitative assessment is of high interest in the study of arrhythmias, but it is usually hampered by the lack of automatic tools. In this work, we propose a software algorithm (Myocyte Automatic Retrieval and Tissue Analyzer, MARTA) to automatically detect myocytes from fluorescent microscopy images of cardiac tissue, measure their morphological features and evaluate the expression of CX43 and its degree of lateralization. The proposed software is based on the generation of cell masks, contouring of individual cells, enclosing of cells in minimum area rectangles and splitting of these rectangles into end-to-end and middle compartments to estimate CX43 lateral-to-total ratio. Application to human ventricular tissue images shows that mean differences between automatic and manual methods in terms of cardiomyocyte length and width are below 4 µm. The percentage of lateral CX43 also agrees between automatic and manual evaluation, with the interquartile range approximately covering from 3% to 30% in both cases. MARTA is not limited by fiber orientation and has an optimized speed by using contour filtering, which makes it run hundreds of times faster than a trained expert. Developed for CX43 studies in the left ventricle, MARTA is a flexible tool applicable to morphometric and lateralization studies of other markers in any heart chamber or even skeletal muscle. This open-access software is available online.Fil: Oliver Gelabert, Antoni. Universidad de Zaragoza; EspañaFil: García Mendívil, Laura. Universidad de Zaragoza; EspañaFil: Vallejo Gil, José María. University Hospital Miguel Servet; EspañaFil: Fresneda Roldán, Pedro Carlos. University Hospital Miguel Servet; EspañaFil: Andelová, Katarína. Centre of Experimental Medicine; EslovaquiaFil: Fañanás Mastral, Javier. University Hospital Miguel Servet; EspañaFil: Vázquez Sancho, Manuel. University Hospital Miguel Servet; EspañaFil: Matamala Adell, Marta. University Hospital Miguel Servet; EspañaFil: Sorribas Berjón, Fernando. University Hospital Miguel Servet; EspañaFil: Ballester Cuenca, Carlos. University Hospital Miguel Servet; EspañaFil: Tribulova, Narcisa. Centre of Experimental Medicine; EslovaquiaFil: Ordovás, Laura. Universidad de Zaragoza; EspañaFil: Diez, Emiliano Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Pueyo, Esther. Biomedical Research Networking Center in Bioengineering; España. Universidad de Zaragoza; Españ

Chronological and biological aging of the human left ventricular myocardium: Analysis of microRNAs contribution

Aging is the main risk factor for cardiovascular diseases. In humans, cardiac aging remains poorly characterized. Most studies are based on chronological age (CA) and disregard biological age (BA), the actual physiological age (result of the aging rate on the organ structure and function), thus yielding potentially imperfect outcomes. Deciphering the molecular basis of ventricular aging, especially by BA, could lead to major progresses in cardiac research. We aim to describe the transcriptome dynamics of the aging left ventricle (LV) in humans according to both CA and BA and characterize the contribution of microRNAs, key transcriptional regulators. BA is measured using two CA-associated transcriptional markers: CDKN2A expression, a cell senescence marker, and apparent age (AppAge), a highly complex transcriptional index. Bioinformatics analysis of 132 LV samples shows that CDKN2A expression and AppAge represent transcriptomic changes better than CA. Both BA markers are biologically validated in relation to an aging phenotype associated with heart dysfunction, the amount of cardiac fibrosis. BA-based analyses uncover depleted cardiac-specific processes, among other relevant functions, that are undetected by CA. Twenty BA-related microRNAs are identified, and two of them highly heart-enriched that are present in plasma. We describe a microRNA-gene regulatory network related to cardiac processes that are partially validated in vitro and in LV samples from living donors. We prove the higher sensitivity of BA over CA to explain transcriptomic changes in the aging myocardium and report novel molecular insights into human LV biological aging. Our results can find application in future therapeutic and biomarker research