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Tissue engineering offers a paradigm shift in the treatment of back pain. Engineered intervertebral discs could replace degenerated tissue and overcome the limitations of current treatments that disrupt the biomechanics of the spine. New materials, which exhibit sophisticated mechanical responses, are needed to provide templates for tissue regeneration. These behaviours include time-dependent deformation---facilitating shock absorption and nutrient transfer---and strong material anisotropy and tensile-compressive nonlinearities---providing flexibility in controlled directions. In this work, frameworks for the design of materials with controllable structure-property relationships are developed. The time-dependent mechanical properties of composites of agar, alginate and gelatin hydrogels are investigated. It is shown that the time-dependent responses of the composites can be tuned over a wide range. It is then demonstrated that materials mimicking the fibre-reinforced nature of natural tissues can be developed by infiltrating thick electrospun fibre networks with alginate. These fibre-reinforced hydrogels have tensile and compressive properties that can be separately altered. To better understand the mechanical behaviour of these hydrogel-based materials, improved methods for characterising poroelastic and poroviscoelastic time-dependent material properties using indentation are developed. It is shown that poroviscoelastic relaxation is the product of separate poroelastic and viscoelastic relaxation responses. The techniques developed here provide a methodology to rapidly characterise the properties of time-dependent materials and to create materials with complex structure-property relationships similar to those found in natural tissues; they present a framework for biomimetic materials design. The work in this thesis can be used to inform the design of clinically relevant tissue engineering treatments and help the quarter of a million people each year who undergo spinal surgery to reduce back pain.

This study investigates the variation in the spatial patterns of Diptera and Collembola throughout the forest canopy due to seasonal changes in temperature and humidity in the monsoon climate of West Africa. There is a very distinct turnover in climate from the end of the dry season (the hottest and driest time of the year) to the beginning of the rains and this coincides with significant increases and decreases in the overall abundance of many forest dwelling Diptera and Collembola species. The study investigates spatial patterns on two gradients; vertically from the ground to the high canopy and laterally from the edge of the forest to the core, with the added complexity of the affects of anthropogenic burning of adjacent savannah. The results show that seasonality and the starting of the rains significantly affect both the overall abundance and the spatial patterns, providing species with a strategic change in habitat niche. During seasonal conditions that are less conducive to species' overall abundance, spatial patterns are suppressed by environmental conditions. However when environmental conditions are optimum for increased species abundance, spatial patterns are only suppressed by the availability of resources within the habitat (feeding or reproductive resources for example). Successive late burning events may have changed the structure of the forest edge introducing a significantly more open forest structure changing environmental conditions and thus creating a habitat more suitable for species which prefer lower humidity and higher temperatures.