La jornada laboral : perspectiva histórica y valoración jurídica

La determinación de la jornada laboral sufre históricamente oscilaciones notables a partir de la caída del régimen gremial. La reivindicación de las ocho horas aparece como una reclamación unánime de los sindicalistas, de los socialistas, de los extremistas y de los moderados. El objetivo de este trabajo es un aproximación histórica a las repercusiones jurídicas. Diferentes elementos permiten confrontar el principio mismo de las ocho horas, legalmente consagrado, con la realidad que lo desvirtúa ante las apremiantes necesidades eco - nómicas y sociales que exigen en algunos momentos incrementar o reducir el número de horas de prestación de servicios._______________________________The determination of the working hours has historically experimented important changes since the fall of the guild regime. The claim for the eight hours appears as a unanimous demand of the trade-unionists, the socialists, the extremists and the moderates. The scope of this work is a historical approach to the legal effects. Several elements allow to confront the eight-hour principle itself, established by the law, to the reality that invalidates it due to the unavoidable economic an social needs, which require in certain moments to increase or reduce the number of hours of effective work

Estudio gramatical aplicado a un texto turístico en alemán

Universidad de Sevilla. Grado en Turism

Las barracas del Delta del Ebro. Un modelo de hábitat tradicional

En número dedicado a: Tarragona, comarcas del Baix Ebre y Montsi

Los accidentes de trabajo: perspectiva histórica

El objeto de esta colaboración va a centrarse en el análisis de una serie de normas históricas conectadas entre sí por una idéntica finalidad: las medidas destinadas a prevenir los accidentes de trabajo y a paliar sus consecuencias. El estudio de las leyes y las instituciones jurídicas que aparecen en cada período y su significado contribuye de forma evidente a completar una parte de la historia social. La evolución de la legislación laboral aporta una valiosa información sobre las condiciones de trabajo y de vida de amplias capas de la población obrera aunque será necesaria una reflexión posterior sobre su cumplimiento efectivo

Carbon materials as template for the preparation of mixed oxides with controlled morphology

Resumen del libro de actas del Congreso: 5th Czech-Italian-Spanish Conference on Molecular Sieves and Catalysis, celebrado en Segovia del 16 al 19 de junio de 2013Bulk mixed oxide catalysts are widely used for many applications, such as catalysts for selective oxidation processes, electrocatalysts for fuel cells, gas sensors, and solid oxide electrolysers for the production of hydrogen. VPO (vanadium and phosphorous oxides) are one of the bulk mixed oxide materials which are of interest nowadays since they are active catalysts for saturated hydrocarbon activation. With the conventional synthesis procedures for preparing bulk mixed oxides is really difficult to control the morphology and the porous structure of these materials. In practice, there are just a few works about the synthesis of mixed oxide materials with controlled morphology. The aim of this work was to describe new approaches for the preparation of VPO mixed oxides materials with spherical morphology. A carbon material was prepared using cellulose as starting material by hydrothermal treatment with phosphoric acid at 200ºC and carbonized at 500ºC. SEM analysis showed that carbon spheres with diameter up to 0.5 m were prepared by this procedure. These phosphorous containing carbon material was impregnated with the appropriate amount of vanadium oxide species in order to obtain a monolayer of VOx species on the surface of the carbon materials following a procedure described previously (1). By this manner, a carbon supported VOx material with spherical morphology was obtained (VPO/Csph). The calcination of this material was optimized in order to obtain VPO spheres with diameter up to 1-2 m and with BET area values close to 100 m2/g. Figure 1 shows a SEM image of this sample (VPOsph). The presence of vanadium pyrophosphate phase, which has been described as the active phase of this catalytic system, was identified by XRD and Raman spectroscopy. Thus, the chemical composition as well as the morphology and porous structure of these new spherical materials makes them quite promising as catalysts