Sea anemone actinoporins: The transition from a folded soluble state to a functionally active membrane-bound oligomeric pore

Actinoporins are a family of 20-kDa, basic proteins isolated from sea anemones, whose activity is inhibited by preincubation with sphingomyelin. They are produced in monomeric soluble form but, when binding to the plasma membrane, they oligomerize to produce functional pores which result in cell lysis. Equinatoxin II (EqtII) from Actinia equina and Sticholysin II (StnII) from Stichodactyla helianthus are the actinoporins that have been studied in more detail. Both proteins display a beta-sandwich fold composed of 10 beta-strands flanked on each side by two short alpha-helices. Twodimensional crystallization on lipid monolayers has allowed the determination of low-resolution models of tetrameric structures distinct from the pore. However, the actual structure of the pore is not known yet. Wild-type EqtII and StnII, as well as a nice collection of natural and artificially made variants of both proteins, have been produced in Escherichia coli and purified. Their characterization has allowed the proposal of a model for the mechanism of pore formation. Four regions of the actinoporins structure seem to play an important role. First, a phosphocholine-binding site and a cluster of exposed aromatic residues, together with a basic region, would be involved in the initial interaction with the membrane, whereas the amphipathic N-terminal region would be essential for oligomerization and pore formation. Accordingly, the model states that pore formation would proceed in at least four steps: Monomer binding to the membrane interface, assembly of four monomers, and at least two distinct conformational changes driving to the final formation of the functional pore

Deposition of composite materials using a wire-bar coater for achieving processability and air-stability in Organic Field-Effect Transistors (OFETs)

Organic thin films based on composite materials of semiconducting dibenzo-tetrathiafulvalene (DB-TTF) and insulating styrenic matrices (Polystyrene (PS10k) and Poly-alpha methylstyrene (PAMS10k) ) have been fabricated by the wire-bar coating technique in ambient conditions (air, light, humidity) and contrasted with the ones prepared by thermally evaporating the organic semiconductor. The transistors fabricated with DB-TTF:PS10k composites show a clear fieldeffect behavior with p-type characteristics, exhibiting charge carriers mobilities in the range of 0.01 cm2/Vs, fully comparable with the films obtained by thermal evaporation. However, while the thermally evaporated films show poor stability in air, the wire-bar coated composites films and devices are highly reproducible and exhibit lower threshold voltage values. Thus, we demonstrate the suitability of the wire-bar technique for manufacturing large area devices.The authors thank the ERC StG 2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) with project BE-WELL CTQ2013-40480-R, and the Generalitat de Catalunya (2014-SGR-17). F. G. D. P. thanks Universidad Técnica de Ambato and Secretaría de Educación Superior, Ciencia, Tecnología e Innovación for funding through a doctoral scholarship “Convocatoria abierta 2010”.Peer Reviewe

Asentamientos poblacionales periféricos más seguros. Instrumental para el diseño y evaluación de la calidad ambiental

The vulnerability of settlement before any situation and territorial scope, is a concern, due inter alia to their strong influence on the development policies of management to disaster or adverse external events affecting the normal development of the people; Summary to diagnose the environmental quality of urbanization in a discrete space, as it is the case of the peripheral housing estates, allows analyze those factors that influence the vulnerability of these and make recommendations for implementing environmental policies that mitigate the risks. On the basis of that vulnerability is a dynamic concept that examines the risk factors, continues an instrumental for environmental assessment of settlements population peripherals (APP), in particular the conditions of the city Santiago de Cuba, where it has considered this component in its evaluative indicators. You expose instrumentation reference and his categorical system: variable, subvariables, evaluative parameters and scale of values, which is the essence of the instrumental designed theorist; likewise are histograms and arrays that comprise the instrumental assessment workshop. It will serve to assess settlements in operation and for the design of new ones, and can be generalized to other territories.Key words: Peripheral population settlements, environmental quality, vulnerabilityDOI: http://dx.doi.org/10.5377/nexo.v24i2.659La vulnerabilidad de un asentamiento ante cualquier situación y ámbito territorial, es una preocupación, debido entre otras cuestiones a su fuerte influencia en las políticas de desarrollo de gestión frente a desastres o eventos adversos externos que afectan el normal desarrollo de las personas; de ahí que diagnosticar la calidad ambiental de una urbanización en áreas espaciales específicas, como es el caso de las urbanizaciones periféricas, posibilita analizar aquellos factores que influyen en la vulnerabilidad de estas y formular recomendaciones para implementar políticas ambientales que mitiguen los riesgos. Partiendo de que la vulnerabilidad es una noción dinámica que examina los factores de riesgos, se presenta un instrumental para la evaluación ambiental de los Asentamientos Poblacionales Periféricos (APP), en las condiciones particulares de la ciudad Santiago de Cuba, donde se ha considerado esta componente dentro de sus indicadores evaluativos. Se expone el instrumental de referencia y su sistema categorial: variables, subvariables; parámetros evaluativos y escala de valores, lo que constituye la esencia del instrumental teórico diseñado; de igual forma se presentan los histogramas y matrices que conforman el instrumental práctico de evaluación. El mismo servirá para evaluar asentamientos en funcionamiento y para el diseño de nuevos, pudiendo ser generalizado a otros territorios.Palabras claves: Asentamientos poblacionales periféricos, calidad ambiental, vulnerabilidad.DOI: http://dx.doi.org/10.5377/nexo.v24i2.65

Deposición convectiva rápida a escala nanométrica de materiales compuestos activos para la fabricación de transistores orgánicos de efecto de campo

Transistores orgánicos de efecto de campo basados en un material compuesto han sido fabricados por medio de la técnica de deposición convectiva rápida. La fabricación fue llevada a cabo bajo condiciones ambientales (aire, luz y humedad). En todos los casos, los transistores fabricados muestran un claro comportamiento de efecto de campo con características de semiconductor tipo-p, y exhiben movilidades en el orden de 10−2 cm2/V.s, totalmente comparables con transistores obtenidos por evaporación térmica del mismo material activo. La técnica de deposición demuestra que se pueden obtener dispositivos con alta reproducibilidad y que en todos los casos muestran una baja tensión umbral de alrededor 1 V. Por lo tanto, se demuestra que la deposición convectiva rápida puede ser usada para la fabricación de transistores orgánicos de efecto de campo sobre áreas amplias, con indicadores de reproducibilidad entre dispositivos y alta estabilidad en condiciones ambiente.// Organic field-effect transistors based on composite materials has been manufactured using the rapid convective deposition technique. The manufacturing was carried out under environmental conditions (air, light and humidity). All manufactured transistors show a typical field-effect behavior with features of a p-type semiconductor, and exhibit field-effect mobilities around 10−2 cm2/V.s, fully comparable with transistors manufactured using thermal evaporation of the same active material. The deposition technique demonstrates that devices may be manufactured with high reproducibility and in all cases with a low threshold voltage of approximately 1V. Therefore, it is demonstrated here that rapid convective deposition can be used to manufacture organic fieldeffect transistors on large surface areas, showing high reproducibility among devices and high stability at environmental conditions

Política industrial y suelo industrial: especial referencia a Castilla y León

Los nuevos escenarios económicos que están surgiendo en el marco de una economía que prima la competitividad a gran escala cuestionan la necesidad de intervención de las autoridades públicas a favor de aquellas actividades que muestran signos de debilidad. La política industrial ha sido una de las políticas económicas cuya oportunidad y eficacia más ha sido debatida en los ámbitos económico, político y social en los últimos años, y muy especialmente en entornos en los que su dimensión de aplicación y, por tanto, sus objetivos finales han de adaptarse a espacios territoriales diferentes. Los instrumentos y fines de la política industrial han de variar su forma en función del espacio en el que deben actuar. Por esa razón, uno de nuestros objetivos será analizar la perspectiva de la política industrial desde la Europa Comunitaria en contraste con la dimensión que dicha política debe adoptar en el marco de una región como Castilla y León. En este último caso, nos referiremos más específicamente al papel jugado por uno de los instrumentos de política industrial regional; el suelo industrial

Prólogo

En 2013 se cumplían veinticinco años desde la publicación, el 29 de junio de 1988, del Real Decreto 659, por el que se creaba en la Universidad de León una Facultad de Ciencias Económicas y Empresariales. Este motivo llevó a un grupo de profesores y colaboradores del Centro a comprometerse en la elaboración de un Número Especial de la revista Pecunia en el que abordar diversos estudios sobre la economía de León. Aquél proyecto, que sufrió diversos avatares en su desarrollo, ha concluido en el ejemplar que ahora ve la luz (digital)

Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: Influence of local factors

One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing signal of the Global Flood Detection System for converting the flood detection signal into river discharge values. The study uses data for 322 river measurement locations in Africa, Asia, Europe, North America and South America. Satellite discharge measurements were calibrated for these sites and a validation analysis with in situ discharge was performed. The locations with very good performance will be used in a future project where satellite discharge measurements are obtained on a daily basis to fill the gaps where real time ground observations are not available. These include several international river locations in Africa: Niger, Volta and Zambezi rivers. Analysis of the potential factors affecting the satellite signal was based on a classification decision tree (Random Forest) and showed that mean discharge, climatic region, land cover and upstream catchment area are the dominant variables which determine good or poor performance of the measurement sites. In general terms, higher skill scores were obtained for locations with one or more of the following characteristics: a river width higher than 1km; a large floodplain area and in flooded forest; with a potential flooded area greater than 40%; sparse vegetation, croplands or grasslands and closed to open and open forest; Leaf Area Index > 2; tropical climatic area; and without hydraulic infrastructures. Also, locations where river ice cover is seasonally present obtained higher skill scores. The work provides guidance on the best locations and limitations for estimating discharge values from these daily satellite signals.JRC.H.7-Climate Risk Managemen

Calorimetric scrutiny of lipid binding by sticholysin II toxin mutants

The mechanisms by which pore-forming toxins are able to insert into lipid membranes are a subject of the highest interest in the field of lipid–protein interaction. Eight mutants affecting different regions of sticholysin II, a member of the pore-forming actinoporin family, have been produced, and their hemolytic and lipid-binding properties were compared to those of the wild-type protein. A thermodynamic approach to the mechanism of pore formation is also presented. Isothermal titration calorimetry experiments show that pore formation by sticholysin II is an enthalpy-driven process that occurs with a high affinity constant (1.7×108 M−1). Results suggest that conformational flexibility at the N-terminus of the protein does not provide higher affinity for the membrane, although it is necessary for correct pore formation. Membrane binding is achieved through two separate mechanisms, that is, recognition of the lipid–water interface by a cluster of aromatic residues and additional specific interactions that include a phosphocholinebinding site. Thermodynamic parameters derived from titration experiments are discussed in terms of a putative model for pore formation

A Rapid, Low-Cost, and Scalable Technique for Printing State-of-the-Art Organic Field-Effect Transistors

In the last few years exciting advances have been achieved in developing printing techniques for organic semiconductors, and impressive mobility values have been reported for the resulting organic field-effect transistors (OFETs). However, not all these techniques are scalable and some of them require additional crystallization steps. This study reports on the fabrication of OFETs employing blends of four benchmark organic semiconductors with polystyrene and demonstrates that applying the same formulation and experimental conditions for printing them, highly reproducible and uniform crystalline films exhibiting high OFET performance are successfully achieved. It is noted that the mobility values achieved here are not the highest reported for the studied materials; however, they are state-of-the-art values and could be regarded as exceptional considering the low cost and fast speed of the fabrication process involved here.This work was mainly funded by the ERC StG 2012 306826 e GAMES and ERC PoC 2014 640120 LAB TECH projects. The authors also thank the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER BBN), the DGI (Spain) project BE WELL CTQ2013 40480 R, the Generalitat de Catalunya (2014 SGR 17) and the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV 2015 0496). The authors would like to thank the ICTS "NANBIOSIS", more specifically to the Nanotechnology Platform, unit of CIBER BBN at the Institute for Bioengineering of Catalonia (IBEC) for their assistance in ToF SIMS analyses. I. T. acknowledges FPU fellowship from the Ministery and the Materials Science PhD Program of Universitat Autònoma de Barcelona. F. G. D. P. thanks Universidad Técnica de Ambato and Secretaría de Educación Superior, Ciencia, Tecnología e Innovación for funding through a doctoral scholarship “Convocatoria abierta 2010”.Peer reviewe