Polymeric self-assemblies based on tetra-ortho-substituted azobenzene as visible light responsive nanocarriers

Most of reported polymeric light-responsive nanocarriers make use of UV light to trigger morphological changes and the subsequent release of encapsulated cargoes. Moving from UV-to visible-responsive units is interesting for the potential biomedical applications of these materials. Herein we report the synthesis by ring opening polymerization (ROP) of a series of amphiphilic diblock copolymers, into which either UV or visible responsive azobenzenes have been introduced via copper(I) catalyzed azide-alkyne cycloaddition (CuAAC). These copolymers are able to self-assemble into spherical micelles or vesicles when dispersed in water. The study of the response of the self-assemblies upon UV (365 nm) or visible (530 or 625 nm) light irradiation has been studied by Transmission Electron Microscopy (TEM), Cryogenic Transmission Electron Microscopy (Cryo-TEM), and Dynamic Light Scattering (DLS) studies. Encapsulation of Nile Red, in micelles and vesicles, and Rhodamine B, in vesicles, and its light-stimulated release has been studied by fluorescence spectroscopy and confocal microscopy. Appreciable morphological changes have been induced with green light, and the subsequent release of encapsulated cargoes upon green light irradiation has been confirmed

Internal anatomy of an erg sequence from the aeolian-fluvial system of the De La Cuesta Formation (Paganzo Basin, northwestern Argentina)

Permian red beds of the De La Cuesta Formation in the Sierra de Narváez (Paganzo Basin, northwestern Argentina) are essentially composed of sandstones associated with mudstones and subordinate conglomerates. Facies distributions and stacking patterns indicate that these sediments resulted from the interaction between aeolian and ephemeral fluvial systems, and are represented by aeolian dune, dry aeolian interdune and Aeolian sand sheet, mudflat, wet aeolian interdune, and fluvial deposits. The De La Cuesta Formation is characterized by aeolian (erg) sequences alternating with non-aeolian (terminal alluvial fan - mudflat) sequences. Each erg sequence is bounded at its base by a regionally extensive sand-drift surface and at the top by an extinction surface. A number of architectural elements, including aeolian dunes limited by interdunes, grouped crescentic Aeolian dunes, longitudinal dunes, and draa with superimposed crescentic dunes are recognised in the erg sequences. The sand sea developed during phases of increasing aridity, whereas non-aeolian deposition might have occurred during more humid phases. Thus, the styles of aeolian-fluvial interaction are considered to result from cyclical climatic changes. Within the drier hemicycles, the rhythmic alternation between draa deposits and aeolian dune and interdune deposits indicates higher frequency cycles that could be attributed to subtle climatic oscillations and/ or changes in sand supply and availability. The development of the Permian sand sea in the inland Paganzo Basin seems to be related to the growth of a volcanic chain to the west. This topographic barrier separated the Paganzo Basin from the Chilean Basin, located along the western margin of Gondwana and characterised by shallow marine carbonate sedimentation. The correlation between the Permian erg and the shallow marine carbonates suggests a regional warming period during the Middle Permian in western Gondwana

Self-assembly of thermo and light responsive amphiphilic linear dendritic block copolymers

The synthesis and structural characterization of a new dual responsive linear-dendritic block copolymer (LDBC) is presented. The LDBC is constituted by a thermoresponsive linear block from polymethacrylate of oligo- and diethylene glycol, and a light responsive den- dron block of bis-MPA decorated at the periphery with 4-isobutyloxyazobenzene and alkyl chains in a 50:50 M ratio. Blocks are coupled together by copper(I) catalyzed alkyne–azide cycloaddition (CuAAC). The ability of the LDBC to form vesicle self-assemblies in water is described, as well as the effect of light and temperature on the vesicles morphology, on the basis of transmission electron microscopy (TEM), dynamic light scattering (DLS) and UV–vis spectroscopy studies. The effect of UV light and temperature on the vesicles struc- ture by SAXS and WAXS conducted on real time is also presented. Finally, the potential use of the vesicles to load and stimuli controlled release of small fluorescent molecules is probed

Hacia una nueva cultura de la seguridad y salud en las pymes del sector de la construcción: un camino más allá de la ley

Seguridad y salud en el trabajo (SST) es uno de los temas de más importancia en la agenda social de la Unión Europea (UE). Una de las principales razones para ello es la seriedad de las consecuencias de los accidentes laborales: trauma para los implicados, impacto financiero negativo para la compañía, para la economía nacional y personal, y una pobre imagen pública para la empresa, la cual puede extenderse a todo el sector. El coste total por accidentes graves y fatales en la UE en 1999 supuso pérdidas por 500 millones en días de trabajo perdidos. Ademas, España se sitúa en segundo lugar en el ranking de accidentes fatales en el trabajo con 370 muertos en 2003, sumando 110 muertes más que la media en la UE. El análisis secundario realizado a partir de los datos del Instituto Nacional de Seguridad e Higiene en el Trabajo (INSHT) correspondientes a la«IV encuesta sobre condiciones de trabajo» reveló que existen diferentes percepciones del riesgo entre la dirección y los empleados, aunque ambas partes trabajen en el mismo lugar. Los datos también muestran que la percepción del riesgo cambia tanto en un caso como en el otro si se tienen en cuenta sólo las actividades de SST o los aspectos estructurales, en lugar de considerar toda la empresa y el conjunto de las actividades y aspectos estructurales de la organización. La investigación parece indicar también que el tamaño de la plantilla está correlacionado con la percepción de riesgo tanto del trabajador como de la gerencia de la empresa. Además, el número de diferencias estructurales y de actividades en materia de SST marcan la diferencia en la forma en que la dirección y los empleados perciben el riesgo en el trabajo. Para implantar una cultura de SST es necesario mucho más que cambios estructurales en la organización de las empresas y/o cambios en la actitud de los individuos. Tras revisar los instrumentos existentes en España especializados en temas de SST, concluimos que éstos se dirigían sobre todo a cómo impulsar actividades específicas. Sin embargo, pensábamos que era importante orientarnos hacia cómo crear una cultura de SST que incorpore actividades concretas, mientras se mantienen los limitados recursos que tienen las pymes para este tipo de asuntos. Concluimos que era necesario estudiar las buenas prácticas en materia de SST y su implementación en pymes, con el fin de servir como un ejemplo real y promover normas basadas en buenas prácticas. El análisis de casos de buenas prácticas a partir del modelo TQM (Total Quality Management) puede ser de gran utilidad para entender cómo promover una cultura de SST que incorpore la participación de los trabajadores, para de esta forma cerrar la brecha existente en la percepción del riesgo en el trabajo. La posibilidad de compartir conocimientos entre las pymes es el primer paso hacia una nueva cultura de la SST

Multidisciplinary consensus statement on the clinical management of patients with pancreatic cancer

Pancreatic cancer (PC) remains one of the most aggressive tumors with an increasing incidence rate and reduced survival. Although surgical resection is the only potentially curative treatment for PC, only 15-20% of patients are resectable at diagnosis. To select the most appropriate treatment and thus improve outcomes, the diagnostic and therapeutic strategy for each patient with PC should be discussed within a multidisciplinary expert team. Clinical decision-making should be evidence-based, considering the staging of the tumor, the performance status and preferences of the patient. The aim of this guideline is to provide practical and evidence-based recommendations for the management of PC

Catastrophic senescence and semelparity in the Penna aging model

The catastrophic senescence of the Pacific salmon is among the initial tests used to validate the Penna aging model. Based on the mutation accumulation theory, the sudden decrease in fitness following reproduction may be solely attributed to the semelparity of the species. In this work, we report other consequences of mutation accumulation. Contrary to earlier findings, such dramatic manifestation of aging depends not only on the choice of breeding strategy but also on the value of the reproduction age, R, and the mutation threshold, T. Senescence is catastrophic when $T \leq R$. As the organism's tolerance for harmful genetic mutations increases, the aging process becomes more gradual. We observe senescence that is threshold dependent whenever T>R. That is, the sudden drop in survival rate occurs at age equal to the mutation threshold value