Fibre Distribution and the Process-Property Dilemma

The options for the fibre reinforcement of polymer matrix composites cover a range from short-fibre chopped strand mat, through woven fabric to unidirectional pre-impregnated (prepreg) reinforcements. The modelling of such materials may be simplified by assumptions such as perfect regular packing of fibres and the total absence of fibre waviness. However, these and other features such as the crimp or waviness in woven fabrics make real materials more complex than the simplified models. Clustering of fibres creates fibre-rich and resin-rich volumes (FRV and RRV respectively) in the composites. Prior to impregnation, large RRV will be pore-space that can expedite the flow of resin in liquid composite moulding processes (especially resin transfer moulding (RTM) and resin infusion under flexible tooling (RIFT). In the composite, the clustering of fibres tends to reduce the mechanical properties. The use of image processing and analysis can permit micro-/meso-structural characterisation which may correlate to the respective properties. This chapter considers the quantification of microstructure images in the context of the process-property dilemma for woven carbon-fibre reinforced composites with the aim of increasing understanding of the balance between processability and mechanical performance

In vitro propagation and germplasm conservation of wild orchids from South America

Orchids are an important part of plant biodiversity on this planet due to their high variability among species and their habitats. South America represents more than thirty percent of all known orchid species, Colombia, Ecuador, Brazil, Peru, and Bolivia being among the richest countries in the world in terms of orchid biodiversity. Nevertheless, concerning the orchid conservation status, in Colombia precisely orchids occupy the unlucky first place as the plant family with the highest number of threatened species. There is a similar situation in the rest of the South American countries. The two main threats to orchid survival are both anthropogenic: the first one is deforestation, and the second largest threat to orchids is collection from the wild. One desirable action to safeguard these endangered species is to develop procedures that make possible their massive propagation, which would provide material for both environmental restoration and commercial purposes avoiding extractions from nature. Likewise, the development of systems that allow the ex situ conservation of orchid germplasm is imperative. This chapter reviews the progresses of different in vitro approaches for orchid propagation and germplasm conservation, safeguarding the genetic biodiversity of these species. Several study cases are presented and described to exemplify the protocols developed in the Botanical Institute of Northeast (UNNE-CONICET) for propagating and long-term storing the germplasm of wild orchids from Argentina (Cattleya lundii, Cohniella cepula, C. jonesiana, Gomesa bifolia, Aa achalensis, Cyrtopodium brandonianum, C. hatschbachii, Habenaria bractescens). Moreover, it has been attempted to put together most of the available literature on in vitro propagation and germplasm conservation for South American orchids using different explants and procedures. There are researches of good scientific quality that even cover critical insights into the physiology and factors affecting growth and development as well as storage of several orchid materials. Moreover, studies are still necessary to cover a major number of South American species as well as the use of selected material (clonal) for both propagation and conservation approaches.Fil: Dolce, Natalia Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Medina, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Terada, Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: González Arnao, María Teresa. Universidad Veracruzana; MéxicoFil: Flachsland, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin