Recently, much attention has been directed toward the study of Sc-doped zirconia electrolyte for intermediate-temperature SOFCs ͑IT-SOFCs͒ due to its fairly good ionic conductivity compared with conventional Y-doped zirconia, which can reduce the internal ohmic loss of the cell. For improving unit cell performance, another important point to be considered is the selection of appropriate electrode materials to reduce the polarization loss at the electrode. In this study, we fabricated anode-supported SOFCs with a 1 mol % CeO 2 codoped 10 mol % Sc 2 O 3 -ZrO 2 ͑CeSSZ͒ electrolyte. Various kinds of cathode materials such as La-Sr-Mn-O, La-Sr-Co-O ͑LSCo͒, La-Sr-Co-Fe-O, and Sm-Sr-Co-O ͑SSCo͒ have been applied in order to identify the most suitable cathode material for Sc-doped zirconia. We evaluated the power-generating characteristics of 5 ϫ 5 cm scaled unit cells as well as the cathode polarization effect via a dc current-voltage measurement, a dc current interruption method, and ac impedance spectroscopy. We also thoroughly investigated the interfacial reaction between the electrolyte and the cathode in order to identify appropriate heat-treatment conditions for each candidate cathode material on the CeSSZ electrolyte. According to the investigation, unit cells with a SSCo and LSCo cathode showed superior power density of 1.13 and 1.33 W/cm 2 , respectively, at 700°C and fairly stable cell performance without any serious interfacial reaction.

Oxidative stress is an important pathogenic factor in diabetes. Bilirubin may serve a cytoprotective function as an anti-oxidant. The Gunn rat lacks the enzyme uridine-diphosphate glucuronosyltransferase that is responsible for conjugation of bilirubin, exhibiting elevation of plasma bilirubin. We examined the effect of hyperbilirubinemia on the pancreatic damage caused by streptozotocin (STZ) in the Gunn rat. Male Wistar rats and male Gunn rats were treated with STZ (WS and GS groups, respectively) or vehicle (WC and GC groups, respectively). All 5 rats in the WS group developed diabetes, defined as fasting blood glucose 300 mg/dL or more, at 3 days, whereas only 2 of the 5 GS rats became diabetic at 7 days after STZ injection. Without insulin supplement at 7 days after STZ injection, the WS group displayed higher levels of fasting blood glucose (510.3 ± 50.3 vs. 236.4 ± 42.5 mg/dL, p = 0.003) and HbA1c (5.0 ± 0.1 vs. 3.9 ± 0.1, p = 0.001), compared to those of GS group. In Wistar rats, STZ induced apoptosis of the pancreatic islet cells, accompanied with activation of NADPH oxidase and increased production of reactive oxygen species and nitric oxide, but not in Gunn rats. Moreover, in a rat insulinoma cell line (RIN-m5F), pre-treatment with bilirubin (0.1 mg/dL) decreased cell death and apoptosis caused by STZ, and also reduced H 2 O 2 production. Considering the protective effect of hyperbilirubinemia against STZ-induced injury, we postulate that bilirubin could be a potential therapeutic modality for oxidative stress of pancreas islets.

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