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The capacity for cumulatively complex and constructive technologies is a hallmark of human cognitive ability. Many species use tools, yet the breadth, adaptability, and inventiveness of human tool use distinguishes us. Such complex technological adaptations require the causal understanding to invent and perfect new techniques and the ability to copy perceived behaviours. This has led to considerable research comparing the social learning abilities of chimpanzees and young children on tool-using tasks, yet experimental studies directly investigating tool modification are rare. The studies outlined in this thesis sought to assess the social learning abilities of chimpanzees and children by manipulating both the complexity of a tool modification method and the amount of information available in a demonstration. Video demonstrations of conspecifics were used in lieu of live models, in order to manipulate the quality and quantity of information directly. Both chimpanzees and children presented with complete information about the modification process learned to combine two tools together to make a more efficient tool significantly more than those provided with less information. Unlike chimpanzees, children presented with a more perceptually opaque method of tool modification (twisting and extending an internal rod) were also able to socially learn the task, despite the fact that none of the children in the control condition successfully solved the task. Both children and chimpanzees who solved the task after seeing a demonstration also persisted in using the socially learned method two-weeks later, even when it was no longer necessary. These results identify potent social learning effects in both chimpanzees and children, however, children proved superior to chimpanzees in observationally learning finer manipulative techniques. This thesis also provides the first analysis of video stimuli in ravens. To assess the feasibility of the methodology, ravens were first presented with different types of video stimuli, varying in terms of the subject identity. Ravens showed a preference for video footage of other ravens over different species of birds. In a second study, ravens who saw a conspecific solve a two-step task were more likely to attempt a solution than those who had not. This represents the first evidence of social learning from a video demonstration in ravens and further supports the use of this medium to dissect social learning mechanisms in a range of species.

Hydrogen as an energy vector offers great potential for mobile energy generation through fuel cell technology, however this depends on safe, mobile and high density storage of hydrogen. The destabilised multi-component complex hydride system LiBH4 : MgH2 was investigated in order to characterise the destabilisation reactions which enable reduction of operating temperatures for this high capacity system (ca. 9.8 wt.%). In-situ neutron diffraction showed that regardless of stoichiometry similar reaction paths were followed forming LiH and MgB¬2¬ when decomposed under H¬2 and Mg-Li alloys (Mg0.816Li0.184 and Mg0.70Li0.30) when under dynamic vacuum. Hydrogen isotherms of the 0.3LiBH4 : MgH¬2¬ showed a dual plateau behaviour with the lower plateau due to the destabilised LiBH4 reaction. Thermodynamic data calculated from the isotherm results showed a significant reduction in the T(1bar) for LiBH4 to 322 C (cf. 459 C for LiBH4(l)). Cycling behaviour of 0.3LiBH4 : MgH2 system decomposed under both reaction environments showed very fast kinetics on deuteriding at 400C and 100 bar D2, reaching 90 % conversion within 20 minutes. In contrast 2LiBH4 : MgH2 samples had kinetics an order of magnitude slower and after 4 hours conversions <50 %. These results demonstrate the strong influence of stoichiometry in the cycling kinetics compared to decomposition conditions. Investigation of catalysts found dispersion of metal hydrides through long ball-milling times, or dispersion through reaction with metal halide additions provided the greatest degree of kinetic advantage, with pre-milled NbH providing the best kinetic improvement without reducing capacity due to Li-halide formation. Finally, additions of LiAlH4 to the system formed an Al dispersion through the sample during decomposition, which acted both as a catalyst and destabilising agent on the MgH2 component, forming Mg-Al-Li alloys. Decomposition under H2 also showed a destabilisation effect for the LiBH4 component.