One of the major trends of development of solid oxide fuel cells is to reduce the operating temperature from the high temperature range (>950°C) and intermediate temperature range (750-850°C) to the low temperature range (450-650°C). Development of low temperature oxygen ion conducting electrolytes is focused on single-phase materials including Bi2O3 and CeO2-based oxides. These materials have high ion conductivity at the low temperature range, but they are unstable in reducing environments and they are also electronic conductors. In the present research, three types of multiphase materials, Ce0.887Y0.113O1.9435 (CYO)-ZrO2, CYO- yttria-stabilized zirconia (YSZ), and CuO-CYO were investigated. We found that the conductivity of multiphase electrolyte CuO-CYO with a mass ratio of 1:3 is at least 4 times greater than that of CYO and 10 times greater than that of YSZ, the most commonly used material, obtained in the present experiments at 600°C. The enhancement of conductivity in multiphase materials correlates with the level of mismatch between the two phases. Large mismatches in terms of valance and structure result in high vacancy density and hence high oxygen ion conductivity at grain boundaries. This study demonstrates that synthesis of multiphase ceramic materials is a feasible new avenue for development of oxygen ion electrolyte material for low temperature SOFCs.

Tailored wild watermelon (Citrullus lanatus) juice clarification process is a fundamental step in improving its appearance and consumer acceptability. The purpose of this research was to investigate the mineral and proximate composition of wild watermelon juice (Citrullus lanatus) and to design an optimum processing condition for the enzymatic clarification of the juice. This investigation will help identify the sustainable processing parameters (incubation time, incubation temperature, and enzyme concentration) for ultimate clarification. Wild watermelon juice was treated with pectinase enzyme at different concentrations (0.05 to 0.15 w/w%), incubation temperatures (30 - 50 ͦ C), and incubation times (60 - 180 min). The different process parameters were utilised with each sample treated individually to determine their effect on selected responses: turbidity, clarity, viscosity, L* value, and brix. It was determined that the incubation temperature was the most crucial factor affecting the physiochemical properties of the juice as it exerted a significant influence on most (turbidity, absorbance, and viscosity) of the clarity attributes of the juice. Incubation time significantly affected turbidity and percent brix, whereas enzyme concentration only significantly affected percent brix of the juice. The optimum conditions for juice clarification were established by the Response Surface Methodology at the following parameters: enzyme concentration 0.15 w/w%, incubation time 60 min, and incubation temperature 60 ͦ C. The optimum output parameters at the following: turbidity: 14.18 NTU; clarity: 0.04 Abs; colour: 52.30 L value; viscosity: 1.96 cps; brix: 3.08 %. It may be useful to investigate the optimum parameters for other juices. / Life and Consumer Sciences / M. Sc. (Consumer Science)