Calizas micríticas devonianas utilizadas en históricamente en la producción de la cal hidráulica de Praga (‘pasta di Praga’): caracterización de las materias primas y procedimiento experimental de calcinación en laboratorio

The Devonian micritic limestones from the Prague Basin (Barrandian area, Bohemian Massif, Czech Republic), which were the primary raw material used for natural hydraulic lime burned in Prague, exhibit a feebly to eminently hydraulic character. Based on a laboratory experimental study, the burned product is composed of dominant free-lime (CaO) and/or portlandite (Ca(OH)2), larnite-belite (bicalcium silicate 2CaO.SiO2), and quartz (SiO2) - i.e. phases formed due to the decomposition of carbonate and quartz, present in the original limestones. Proportions of the newly formed phases depend on: the composition of the raw material, maximum burning temperature (the highest amount of larnite-belite appearing at a burning temperature of 1200 °C), and the granulometry of the experimental batches (a coarsely-ground batch exhibited a higher amount of larnite-belite compared to the finely-ground one). The presence of minor phyllosilicates in the raw material contributed to the formation of gehlenite, brownmillerite, wollastonite, calcium aluminate, and/or spurrite.Las calizas micríticas devonianas provenientes de la Cuenca de Praga (área de Barrand, macizo de Bohemia, República checa) que fueron la principal materia prima utilizada para la producción de la cal hidráulica natural calcinada en Praga, presentan un carácter hidráulico desde débil hasta alto. El estudio experimental de laboratorio, ha determinado que el producto calcinado está compuesto de cal viva (CaO) como componente predominante y/o cal hidratada (Ca(OH)2), larnita-belita (silicato bicálcico 2CaO.SiO2) y cuarzo (SiO2) – es decir, fases formadas como resultado de la descomposición de carbonato y cuarzo presentes en las calizas originales. Las proporciones de las nuevas fases formadas dependen de: la composición de la materia prima, temperatura máxima de calcinación (la mayor cantidad de larnita-belita se produce a la temperatura de calcinación de 1200 °C), y la granulometría de las muestras (las muestras con granulometría gruesa presentaron mayor cantidad de belita que las de granulometría fina). La presencia de bajas cantidades de filosilicatos en la materia prima contribuyó a la formación de gehlenita, brownmillerita, wollastonita, calcio aluminoso, y/o spurrita

Bullet impacts and built heritage damage 1640–1939

© 2018, The Author(s). Conflict damage to heritage has been thrust into the global spotlight during recent conflict in the Middle East. While the use of social media has heightened and enhanced public awareness of this ‘cultural terrorism’, the occurrence of this type of vandalism is not new. In fact, as this study demonstrates, evidence of the active targeting of sites, as well as collateral damage when heritage is caught in crossfire, is widely visible around Europe and further afield. Using a variety of case studies ranging from the 1640s to the 1930s, we illustrate and quantify the changing impact of ballistics on heritage buildings as weaponry and ammunition have increased in both energy and energy density potential. In the first instance, this study highlights the increasing threats to heritage in conflict areas. Second, it argues for the pressing need to quantify and map damage to the stonework in order to respond to these challenges

Hydrodynamics of fossil fishes

Fromtheir earliest origins, fishes have developed a suite of adaptations for locomotion in water, which determine performance and ultimately fitness. Even without data from behaviour, soft tissue and extant relatives, it is possible to infer a wealth of palaeobiological and palaeoecological information. As in extant species, aspects of gross morphology such as streamlining, fin position and tail type are optimized even in the earliest fishes, indicating similar life strategies have been present throughout their evolutionary history. As hydrodynamical studies become more sophisticated, increasingly complex fluid movement can be modelled, including vortex formation and boundary layer control. Drag-reducing riblets ornamenting the scales of fast-moving sharks have been subjected to particularly intense research, but this has not been extended to extinct forms. Riblets are a convergent adaptation seen in many Palaeozoic fishes, and probably served a similar hydrodynamic purpose. Conversely, structures which appear to increase skin friction may act as turbulisors, reducing overall dragwhile serving a protective function. Here,we examine the diverse adaptions that contribute to drag reduction in modern fishes and review the few attempts to elucidate the hydrodynamics of extinct forms

Magnetické IDA-modifikované poly(glycidyl-methakrylátové mikročástice pro IMAC čištění fosforproteinů

Newly prepared magnetic iminodiacetic acid modified poly(glycidyl methacrylate) microspheres with immobilized FE III+ ions were used for separation of phosphorylated pepsins