76 research outputs found
Una cosa rara
Coreògraf i mestre de ball Joan MagrinyàDe cada obra s'ha digitalitzat un programa sencer. De la resta s'han digitalitzat les parts que són diferents.Empresa: Juan A. PamiasOrquestra del Gran Teatre del Liceu dirigida per Roy JessonÒpera de Vicente Martín y Soler amb llibret de Lorenzo Da Pont
Trait correlates and functional significance of heteranthery in flowering plants
Flowering plants display extraordinary diversity in the morphology of male sexual organs, yet the functional significance of this variation is not well understood. Here, we conducted a comparative analysis of floral correlates of heteranthery – the morphological and functional differentiation of anthers within flowers – among angiosperm families to identify traits associated with this condition. • We performed a phylogenetic analysis of correlated evolution between heteranthery and several floral traits commonly reported from heterantherous taxa. In addition, we quantified the effect of phylogenetic uncertainty in the observed patterns of correlated evolution by comparing trees in which polytomous branches were randomly resolved. • Heteranthery is reported from 12 angiosperm orders and is phylogenetically associated with the absence of floral nectaries, buzz-pollination and enantiostyly (mirror-image flowers). These associations are robust to particularities of the underlying phylogenetic hypothesis. • Heteranthery has probably evolved as a result of pollinator-mediated selection and appears to function to reduce the conflict of relying on pollen both as food to attract pollinators and as the agent of male gamete transfer. The relative scarcity of heteranthery among angiosperm families suggests that the conditions permitting its evolution are not easily met despite the abundance of pollen-collecting bees and nectarless flowers
The role of pharmacists in developing countries: the current scenario in Pakistan
During the past few years, the pharmacy profession has expanded significantly in terms of professional services delivery and now has been recognized as an important profession in the multidisciplinary provision of health care. In contrast to the situation in developed countries, pharmacists in developing countries are still underutilized and their role as health care professionals is not deemed important by either the community or other health care providers. The aim of this paper is to highlight the role of pharmacists in developing countries, particularly in Pakistan. The paper draws on the literature related to the socioeconomic and health status of Pakistan's population, along with background on the pharmacy profession in the country in the context of the current directions of health care
The Interaction of Nano-Composite Particles with a Polyester Resin and the Effect on Mechanical Properties
The effect of various organically modified silica (ormosil) nano-particle additions on the mechanical properties of a polyester resin has been investigated. For materials produced on such a fine scale, surface properties are known to dominate the manner in which they behave. This thesis presents results from two complementary areas of study: surface analysis and mechanical testing. The surface properties of the nano-particles and the interactions of the nano-particles with a polyester and adsorbed water have been investigated. These analyses have led to the development of a model which shows that the small organic groups grafted to the silica surface (methyl, ethyl and vinyl) are able to pack comparatively densely at the surface, effectively forming a continuous monolayer. This layer is sufficiently thick to prevent interaction of retained silanol groups with the polyester resin. When the silica is modified with phenyl functionality, however, the larger size leads to a more dispersed organic coverage that cannot be considered as a complete monolayer. Hence this layer reduces, but will not completely prevent interaction of the matrix with retained silanols of the silica. The particles have been dispersed in a polyester resin successfully. The dispersion process is an important step in producing viable nano-composites. Mechanical testing of such nano-composites has found a significant improvement in the toughness properties of the phenyl ormosil modified polyester, compared with the unmodified resin, whilst the other modified polyesters show smaller improvements. When considered with the surface analysis investigation, it is argued that the improvement is a result of a reduction of the strength of the interface (with reference to a commercial nano-silica) between the particles and the matrix. The phenyl ormosil is more strongly bonded than the other ormosils. Whilst these other ormosils are able to contribute to toughness through a crack pinning mechanism, the phenyl ormosil absorbs energy through debonding and promotes plastic deformation in the matrix, around and between particles, mechanisms which lead to a greater toughness enhancement
The Interface and Interphase in Polymer Matrix Composites: Effect on Mechanical Properties and Methods for Identification
The interface between the matrix and reinforcing phases can have a significant effect on the mechanical properties of the resulting composite material. The interface can be studied by a number of surface analysis techniques and the interaction modelled. Such studies, and such modelling, can help understanding of the mechanisms which composites undergo during their lifetime. The current review discusses the role of the interface and the methods by which it can be studied; two case studies are presented which illustrate these methods and the value that such knowledge of the interface has brought to larger investigations
The Interface and Interphase in Polymer Matrix Composites: Effect on Mechanical Properties and Methods for Identification
The interface between the matrix and reinforcing phases can have a significant effect on the mechanical properties of the resulting composite material. The interface can be studied by a number of surface analysis techniques and the interaction modelled. Such studies, and such modelling, can help understanding of the mechanisms which composites undergo during their lifetime. The current review discusses the role of the interface and the methods by which it can be studied; two case studies are presented which illustrate these methods and the value that such knowledge of the interface has brought to larger investigations
The use of a controlled multiple quasi-static indentation test to characterise through-thickness penetration of composite panels
During the quasi-static indentation of thin composite panels, well-defined flaps (sometimes called ‘‘petals’’) can develop on the exit face as a consequence of through-thickness penetration of the panel; such flaps can also be seen in impact tests. The flaps develop as four triangles, with the apex of each triangle at the point of impact. In this work, thin panels of CFRP with a 0/90 configuration have been subjected to quasi-static indentation tests and the development of the flaps has been monitored. The results show that the dependence of the flap compliance is proportional to the square of the flap length, which is in agreement with theoretical predictions. The determination of the compliance/crack-length relationship enables a toughness value for fracture of the composite panel to be derived that is directly relevant to through-thickness penetration of the panel
The use of a controlled multiple impact test to characterise through-thickness penetration of composite panels
The use of a controlled multiple impact test to characterise through-thickness penetration of composite panels
During the impact of thin composite panels, well-defined flaps can develop on the exit face as a consequence of through-thickness penetration of the panel. For certain materials (for example, CFRP panels based on plies of plain-woven fabric) the flaps develop as four triangles, with the apex of each triangle at the point of impact. As the impactor is driven through the panel, the flap (i.e. crack) lengths increase, until complete penetration of the panel by the impactor occurs. In the experiments described within this paper, CFRP panels fabricated from epoxy resin reinforced with plain-woven carbon fibre fabrics have been impacted using controlled multiple impact tests. During these tests, the impactor is driven at a controlled velocity to a particular depth of penetration through the composite panel, withdrawn, and then driven further through the panel subsequently. The experimental results show that the dependence of the flap compliance is proportional to the square of the flap length, which is in agreement with theoretical predictions. This compliance/crack-length also enables a toughness value for the composite panel to be derived that is directly relevant to through-thickness impact. The relationship of this toughness value to measurements of the mode I toughness of the composite panel using single edge notch specimens is also discussed
The use of a controlled multiple quasi-static indentation test to characterise through-thickness penetration of composite panels
During the quasi-static indentation of thin composite panels, well-defined flaps (sometimes called ‘‘petals’’) can develop on the exit face as a consequence of through-thickness penetration of the panel; such flaps can also be seen in impact tests. The flaps develop as four triangles, with the apex of each triangle at the point of impact. In this work, thin panels of CFRP with a 0/90 configuration have been subjected to quasi-static indentation tests and the development of the flaps has been monitored. The results show that the dependence of the flap compliance is proportional to the square of the flap length, which is in agreement with theoretical predictions. The determination of the compliance/crack-length relationship enables a toughness value for fracture of the composite panel to be derived that is directly relevant to through-thickness penetration of the panel
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