Polymer Light-Emitting Electrochemical Cells with Embedded Bipolar Electrodes: Visualizing Bipolar Electrochemistry in Solid State

The work presented in this thesis examines the properties of BPEs of various configurations and under different operating conditions in a large planar LEC system. Detailed analysis of time-lapsed fluorescence images allows us to calculate the doping propagation speed from the BPEs. By introducing a linear array of BPEs or dispersed ITO particles, multiple light-emitting junctions or a bulk homojunction have been demonstrated. In conclusion, it has been observed that both applied bias voltages and sizes of BPEs affected the electrochemical doping from the BPE. If the applied bias voltage was initially not sufficiently high enough, a delay in appearance of doping from the BPE would take place. Experiments of parallel BPEs with different sizes (large, medium, small) demonstrate that the potential difference across the BPEs has played a vital role in doping initiation. Also, the p-doping propagation distance from medium-sized BPE has displayed an exponential growth over the time-span of 70 seconds. Experiments with a linear array of BPEs with the same size demonstrate that the doping propagation speed of each floating BPE was the same regardless of its position between the driving electrodes. Probing experiments under high driving voltages further demonstrated the potential of having a much more efficient light emission from an LEC with multiple BPEs.

The white gene and locomotor recovery from anoxia in Drosophila melanogaster

Locomotor recovery from anoxia is complicated and little is known about the molecular and cellular mechanisms regulating anoxic recovery in Drosophila. For this thesis I established a protocol for large-scale analysis of locomotor activity in adult flies with exposure to a transient anoxia. Using this protocol I observed that wild-type Canton-S flies recovered faster and more consistently from anoxia than the white-eyed mutant w1118, which carries a null allele of w1118 in an isogenic genetic background. Both Canton-S and w1118 are commonly used controls in the Drosophila community. Genetic analysis including serial backcrossing, RNAi knockdown, w+ duplication to Y chromosome as well as gene mutation revealed a strong association between the white gene and the timing of locomotor recovery. I also found that the locomotor recovery phenotype is independent of white-associated eye pigmentation, that heterozygous w+ allele was haplo-insufficient to induce fast and consistent locomotor recovery from anoxia in female flies, and that mini-white is insufficient to promote fast and consistent locomotor recovery. Moreover, locomotor recovery was delayed in flies with RNAi knockdown of white in subsets of serotonin neurons in the central nervous system. I further demonstrated that mutations of phosphodiesterase genes (PDE) displayed wild-type-like fast and consistent locomotor recovery, and that locomotor recovery was light-sensitive in the night in w1118. The delayed locomotor recovery and the light sensitivity were eliminated in PDE mutants that were dual-specific or cyclic guanosine monophosphate (cGMP)-specific. Up-regulation of cGMP using multiple approaches including PDE mutation, sildenafil feeding or specific expression of an atypical soluble guanylyl cyclase (Gyc88E) was sufficient to suppress w-RNAi induced delay of locomotor recovery. Taken together, these data strongly support the hypothesis that White transports cGMP and promotes fast and consistent locomotor recovery from anoxia.