Conceptual design of three-dimensional scaffolds of powder-based materials for bone tissue engineering applications

Purpose - The purpose of this paper is to investigate the possibility to construct tissue-engineered bone repair scaffolds with pore size distributions using rapid prototyping techniques. Design/methodology/approach - The fabrication of porous scaffolds with complex porous architectures represents a major challenge in tissue engineering and the design aspects to mimic complex pore shape as well as spatial distribution of pore sizes of natural hard tissue remain unexplored. In this context, this work aims to evaluate the three-dimensional printing process to study its potential for scaffold fabrication as well as some innovative design of homogeneously porous or gradient porous scaffolds is described and such design has wider implication in the field of bone tissue engineering. Findings - The present work discusses biomedically relevant various design strategies with spatial/radial gradient in pore sizes as well as with different pore sizes and with different pore geometries. Originality/value - One of the important implications of the proposed novel design scheme would be the development of porous bioactive/biodegradable composites with gradient pore size, porosity, composition and with spatially distributed biochemical stimuli so that stem cells loaded into scaffolds would develop into complex tissues such as those at the bone-cartilage interface.

Behaviour of a puff of resuspended sediment: a conceptual model

The particulate matter concentration above the seabed is usually assumed to decrease with height, following an exponential or Rouse profile. Many particulate matter concentration profiles with a peak were found on the North Mediterranean bottom water at a few tens of metres above the bottom. A particle size signal at the same altitude was found in this area and on the New York Eight shelf. It is assumed that this unexpected shape is due to a cloud of resuspended cohesive sediments originating from an impulse resuspension process. A simplified three-dimensional numerical model is proposed to describe the behaviour of resuspended particulate matter that originates from a sediment impulse vertically injected in the bottom water. This model reproduces the concentration profile shape observed, and it gives indications concerning the length and time characteristics of such a cloud, depending on the water velocity and bottom boundary layer properties.

Derechos humanos: una aproximación conceptual y su relación con la salud

Resumen: Este trabajo tiene como objetivo principal desarrollar un análisis conceptual de “Derechos Humanos”. Primeramente se dará cuenta de las definiciones habituales, entre ellas, aquellas facultades e institutos que, en cada momento histórico, concretan las exigencias de libertad, igualdad y dignidad humana, y que deben ser reconocidos por los ordenamientos normativos interno e internacional. A su vez, se pasará revista a sus características (innatos, necesarios, inalienables, imprescriptibles, oponibles erga omnes , universales, laicos, carentes de connotación ideológica, ya sea religiosa o política, fundados en una filosofía humanista e indivisibles. Luego, se enunciarán y analizarán sus fuentes y antecedentes históricos: desde 1945 con la Carta de la ONU, hasta 1993 en la Conferencia de Viena. Además, se estudiarán los principales sistemas de protección tanto a nivel nacional como internacional. Finalmente -y como ejemplo ilustrativo de uno de los Derechos Humanos-, se explicitará a la Bioética, puntualizando el análisis en el derecho a la salud