This paper reviews the advantages and disadvantages of various thermal barrier coatings (TBC) systems, with the aim of custom designing a TBC system to be both strain tolerant and have a low thermal conductivity.Methods of heat transfer within zirconia based ceramics are discussed, including the influence of coating microstructure and ceramic composition. It is shown the addition of dopant atoms (colouring) is effective in reducing 'phonon' transport while that layered microstructures are effective in reducing 'photon' transport.Advanced processing, using EB-PVD coating methods has allowed both coloured and layered ceramic coatings to be produced. Measured thermal conductivities of 1.0 W/mK have been achieved using these methods, much lower than current commercial EB-PVD coatings at 1.5-1.9 W/mK.

The hearing of the salmon, Sulmo sular L., was studied by means of a cardiac conditioning technique. Fish were trained to show a slowing of the heart, on hearing a sound, in anticipation of a mild electric shock applied later. The minimum sound level to which the fish would respond was determined for a range of pure tones, both in the sea, and in the laboratory. The fish responded only to low frequency tones (below 380 Hz), and particle motion, rather than sound pressure, proved to be the relevant stimulus. The sensitivity of the fish to sound was not affected by the level of sea noise under natural conditions but hearing is likely to be masked by ambient noise in a turbulent river. Sound measurements made in the River Dee, near Aberdeen, lead to the conclusion that salmon are unlikely to detect sounds originating in air, but that they are sensitive to substrate borne sounds.Compared with the carp and cod the hearing of the salmon is poor, and more like that of the perch and plaice.

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