Polyacrylonitrile nanofibre yarn; electrospinning and their post-drawing behaviour

Polyacrylontrile nanofibre yarns have been successfully produced from an electrospinning setup composing positively and negatively charged spinnerets, a rotating funnel and a yarn winder. Through hot drawing, yarns show compact morphology and improved uniformity and have a significant decrease in both yarn and fibre diameters. The hot drawing has improved the molecular orientation and crystallinity of the fibres. The yarn drawn to 5 times of its original length has been found to have the highest tensile strength and modulus

The Mechanical Properties of Carbon Fibre With Glass Fibre Hybrid Reinforced Plastics

Merged with duplicate record 10026.1/2475 on 15.03.2017 by CS (TIS)Fibre composite hybrid materials are generally plastics reinforced with two different fibre species. The combination of these three materials (in this thesis they are carbon fibres, glass fibres and polyester resin) allows a balance to be achieved between the properties of the two monofibre composites. Over the fifteen years since the introduction of continuous carbon fibre as a reinforcement, there has been considerable speculation about the "hybrid effect", a synergistic strengthening of reinforced plastics with two fibres when compared with the strength predicted from a weighted average from the component composites. A new equation is presented which predicts the extent of the hybrid effect. Experiments with a variety of carbon-glass hybrids were undertaken to examine the validity of the theory and the effect of the degree of inter-mixing of the fibres. The classification and quantification of the hybrid microstructures was examined with a view to crosscorrelation of the intimacy of mixing and the strength. Mechanical tests were monitored with acoustic emission counting and acoustic emission amplitude distribution equipment. Some specimens were subjected to one thermal cycle to liquid nitrogen temperature prior to testing. Fracture surfaces were examined in the scanning electron microscope. Numerical analysis by finite element methods was attempted. A constant strain triangular element was used initially, but in the later analyses the PAFEC anisotropic isoparametric quadrilateral elements were used. The system was adapted so that a \Ir singularity could be modelled, and post processor software was written to allow nodal averaging of the stresses and the presentation of this data graphically as stress contour maps

The diversity of flower-visiting insects in the gardens of English country houses

Flower-visiting insects provide essential pollination services, ensuring both global food security and the continuity of wild plants. Recently documented declines in pollinators give cause for concern. Identifying previously unappreciated habitats that support diverse assemblages of these insects is an essential first step in mitigating further losses. This study evaluates, for the first time, the role that large English country-house gardens play in supporting flower visitors within expanses of intensively farmed agricultural land. Focussing on 17 properties in lowland Central England, the results show that these novel ecosystems are important sites for hoverflies, bees and butterflies. In 2010 almost 10,000 flower-visitors from 174 species were recorded Hoverflies were the only group to show a significant difference in species richness across the sites. An important characteristic of these rural gardens is the high diversity of flowering plants available. More than a fifth of the world's plant families were represented, of which approximately 68% were non-native. The results showed that flower visitors did not prefer native plants over aliens, and that the dominance by aliens was no barrier for extensive use by the insects present. Both the species richness and abundance of flower visitors increased as plant richness increased. The study revealed that half of all insect-plant interaction networks examined exhibited a nested structure, a common feature of natural environments that has not previously been assessed in rural gardens. In addition to flower resources influencing insect species richness, landscape-scale effects were also significant. Insect groups responded differently to components in the landscape according to the time of year and the spatial scale considered. Bumblebees exhibited the greatest response to landscape factors and did so at larger scales than other groups. The deployment of commercial trap-nests for solitary cavity-nesting red mason bees in walled gardens revealed new insights into the differential mortality suffered by male and female progeny. Female offspring were found to be disproportionately affected by a combination of development and parasitism losses. This finding suggests that effective mitigation strategies are needed before this species can be considered for use as a managed-pollinator. Further research assessing the benefits crops such as oilseed rape derive from the presence of insects in nearby rural gardens would be a useful addition to this work. Overall, the gardens of English country-houses emerge as sites of important natural as well as cultural heritage