Segmental relaxation in semicrystalline polymers: a mean field model for the distribution of relaxation times in confined regimes

The effect of confinement in the segmental relaxation of polymers is considered. On the basis of a thermodynamic model we discuss the emerging relevance of the fast degrees of freedom in stimulating the much slower segmental relaxation, as an effect of the constraints at the walls of the amorphous regions. In the case that confinement is due to the presence of crystalline domains, a quasi-poissonian distribution of local constraining conditions is derived as a result of thermodynamic equilibrium. This implies that the average free energy barrier $\Delta F$ for conformational rearrangement is of the same order of the dispersion of the barrier heights, $\delta (\Delta F)$, around $\Delta F$. As an example, we apply the results to the analysis of the $\alpha$-relaxation as observed by dielectric broad band spectroscopy in semicrystalline poly(ethylene terephthalate) cold-crystallized from either an isotropic or an oriented glass. It is found that in the latter case the regions of cooperative rearrangement are significantly larger than in the former.Comment: 10 pages, 4 figures .ep

Un enfoque tolerante a interrupciones para la seguridad de la Internet de las cosas

La Internet de las cosas (IoT, Internet of Things) es un paradigma emergente que pretende la interconexión de cualquier objeto susceptible de contar con una parte de electrónica, favorecido por la miniaturización de los componentes. El estado de desarrollo de la IoT hace que no haya ninguna propuesta firme para garantizar la seguridad y la comunicación extremo a extremo. En este artículo presentamos un trabajo en progreso hacia una aproximación tolerante a retrasos (DTN, Delay and Disruption Tolerant Networks) para la comunicación en el paradigma de la IoT y planteamos la adaptación de los mecanismo de seguridad existentes en DTN a la IoT.Este trabajo ha sido parcialmente financiado por el Ministerio de Ciencia e Innovación Español, proyecto TIN2010-15764 y por la Generalitat de Cataluña, proyecto 2014SGR-619

Laser nanostructuring of polymers: Ripples and applications

Polymer nanostructures and nanopatterns are being profusely used for developing next-generation organic devices with analytical and biological functions and photonic applications. Laser based strategies constitute an advantageous approach for the assembly and control of this type of soft matter nanostructures as they afford the sought versatility and reliability. Recent and on-going research on laser nanostructuring of thin films of synthetic polymers and natural biopolymers will be exemplified by studies on the generation of laser induced periodic surface structures (LIPSS) and their use for surface enhanced Raman spectroscopy (SERS) based sensors. © 2012 American Institute of PhysicsFunded by MICINN, Spain, Projects CTQ2010-15680 and MAT2009-07789. MICINN, Spain, Juan de la Cierva contract and an FPI fellowshipPeer Reviewe

Osteocondritis disecante de la cabeza del 2º metacarpiano en un niño: a propósito de un caso

La osteocondritis disecante en articulaciones de la mano es un proceso muy raro, sólo existen dos casos previos publicados en la literatura. Presentamos un paciente de 10 años de edad con dolor e impotencia funcional de la articulación metacarpofalángica de la mano izquierda de semanas de evolución. Con el diagnós - tico final de osteocondritis disecante realizamos una resección del fragmento libre asociadas a perforaciones con aguja fina. Tras el primer año de seguimiento el paciente se encuentra asintomático y se observa remodelación casi completa de la superficie articular.Ostheocondritis in the hand is a rare process. Only two cases were reported in the previous litera - ture. In this report we present a 10 years old boy with pain and a few functional limitation in second metacarpal phalangeal joint for weeks. With the final diagnosis of osteochondritis dissecans we performed surgery. Intraope - ratively the cartilage flap was removed and some drilling was realized. Before one year the patient was asympto - matic and we observed an improvement of articular surface

Effect of jumbo squid (Dosidicus gigas) skin extract on the microbial activity in chilled mackerel (Scomber scombrus)

6 páginas, 4 tablas, 2 figurasDuring the industrial processing of jumbo squid (Dosidicus gigas), large amounts of by-products containing biological active compounds are generated. In this study, aqueous solutions including acetic acid-ethanol extracts of jumbo squid skin (JSS) were tested at three different concentrations as icing media. The effects of the JSS extracts on the quality evolution of chilled mackerel (Scomber scombrus) were monitored. A significant inhibition (p < 0.05) of microbial activity was determined in the fish batch corresponding to the icing condition including the highest JSS concentration. Additionally, fish specimens corresponding to batches including any of the JSS concentrations tested showed lower (p < 0.05) proteolytic counts and pH values than control mackerel. Sensory analysis revealed a marked shelf life extension in chilled mackerel stored in ice including the highest JSS concentration; specimens from such batch were found to be still acceptable after 13 days of storage, while all other mackerel batches were rejectable. The marked microbial activity inhibition observed could be explained on the basis of the presence in ice of lipophilic compounds obtained by acetic acid-ethanol extraction of JSSThis work was supported by the CONACYT-Mexico grant 154046 and the Consejo Superior de Investigaciones Científicas (CSIC) through Research Project PIE 201370E001Peer reviewe

Requirements for the development of school audiovisuals

En este trabajo se muestran algunos de los condicionantes que intervienen en la elaboración de documentales escolares. La producción de un material audiovisual es una tarea compleja que depende básicamente de los medios técnicos de los que se disponga, de los requisitos de calidad que se exijan y de los conocimientos que se manejen (Barroso, 1988). Nuestro objetivo es mostrar las técnicas audiovisuales en el desarrollo de contenidos educativos, analizar su aplicación en la enseñanza de la ciencia y facilitar el trabajo a aquellos profesores que perciban la necesidad de utilizar estos medios tan relacionados con el sustrato cultural de nuestra sociedad.This paper discusses some of the factors involved in the creation of documentaries for teaching purposes. The production of audiovisual material is a complex task which highly depends on the technical resources available, quality standards required and prior audiovisual experience (Barroso, 1988). Our aim was to show the technical requirements, to examine the implementation of audiovisual techniques in the teaching of Science (for secundary students) and helping teachers who perceive the need to use the media as related to the cultural matrix of our society

Expression Profiling Analysis Reveals Key MicroRNA– mRNA Interactions in Early Retinal Degeneration in Retinitis Pigmentosa

PURPOSE. The aim of this study was to identify differentially expressed microRNAs (miRNAs) that might play an important role in the etiology of retinal degeneration in a genetic mouse model of retinitis pigmentosa (rd10 mice) at initial stages of the disease. Methods. miRNAs-mRNA interaction networks were generated for analysis of biological pathways involved in retinal degeneration. RESULTS. Of more than 1900 miRNAs analyzed, we selected 19 miRNAs on the basis of (1) a significant differential expression in rd10 retinas compared with control samples and (2) an inverse expression relationship with predicted mRNA targets involved in biological pathways relevant to retinal biology and/or degeneration. Seven of the selected miRNAs have been associated with retinal dystrophies, whereas, to our knowledge, nine have not been previously linked to any disease. CONCLUSIONS. This study contributes to our understanding of the etiology and progression of retinal degeneration.Supported by the Fundacion Jesus de Gangoiti Barrera and from the Basque Government's Department of Industry and Education Grants SAIOTEK-PE11BN002, PC12BN001, and DEPLC13/002 (AA, JRE); funds from Foundation of Patients of Retinitis Pigmentosa of Gipuzkoa (Retinosis Gipuzkoa Begisare) (OB); a grant from the Fundacion Mutua Madrilena (OB); Basque Government's Department of Education grants DEDUC14/309 (MEI), Diputacion Foral de Gipuzkoa DFG15/006 (MM-C), and ELKARTEK 16/014 (MM-C); National Institute of Health Carlos III (Instituto de Salud Carlos III) Grants ISCIII: CP10/00572 (JRE), PI13/02621 (JRE); an Intensificacion Contract (ALdM) from the Basque Government's Department of Industry; and a grant from the Foundation of Patients of Retinitis Pigmentosa of Gipuzkoa (Retinosis Gipuzkoa Begisare) (JRE). JR-E is a Miguel Servet II Fellow, National Institute of Health Carlos III (Instituto de Salud Carlos III), ISCIII: CPII16/00012

Digit-only sauropod pes trackways from China - evidence of swimming or a preservational phenomenon?

For more than 70 years unusual sauropod trackways have played a pivotal role in debates about the swimming ability of sauropods. Most claims that sauropods could swim have been based on manus-only or manus-dominated trackways. However none of these incomplete trackways has been entirely convincing, and most have proved to be taphonomic artifacts, either undertracks or the result of differential depth of penetration of manus and pes tracks, but otherwise showed the typical pattern of normal walking trackways. Here we report an assemblage of unusual sauropod tracks from the Lower Cretaceous Hekou Group of Gansu Province, northern China, characterized by the preservation of only the pes claw traces, that we interpret as having been left by walking, not buoyant or swimming, individuals. They are interpreted as the result of animals moving on a soft mud-silt substrate, projecting their claws deeply to register their traces on an underlying sand layer where they gained more grip during progression. Other sauropod walking trackways on the same surface with both pes and manus traces preserved, were probably left earlier on relatively firm substrates that predated the deposition of soft mud and silt . Presently, there is no convincing evidence of swimming sauropods from their trackways, which is not to say that sauropods did not swim at all

Requisitos para la elaboración de audiovisuales escolares

En este trabajo se muestran algunos de los condicionantes que intervienen en la elaboración de documentales escolares. La producción de un material audiovisual es una tarea compleja que depende básicamente de los medios técnicos de los que se disponga, de los requisitos de calidad que se exijan y de los conocimientos que se manejen (Barroso, 1988). Nuestro objetivo es mostrar las técnicas audiovisuales en el desarrollo de contenidos educativos, analizar su aplicación en la enseñanza de la ciencia y facilitar el trabajo a aquellos profesores que perciban la necesidad de utilizar estos medios tan relacionados con el sustrato cultural de nuestra sociedad.This paper discusses some of the factors involved in the creation of documentaries for teaching purposes. The production of audiovisual material is a complex task which highly depends on the technical resources available, quality standards required and prior audiovisual experience (Barroso, 1988). Our aim was to show the technical requirements, to examine the implementation of audiovisual techniques in the teaching of Science (for secundary students) and helping teachers who perceive the need to use the media as related to the cultural matrix of our society