Polymer electrolyte fuel cells have attracted enormous interest as a primary power source for electric vehicles. Water management in the electrolyte is one of the complicated problems to be overcome. A new self-humidifying electrolyte membrane is proposed to solve this problem. Self-humidification allows the use of very thin membranes, simultaneously allowing high performance of the cell. Use of the new, thin membranes makes the system very simple and ready for cold starts and also amenable to abrupt load changes. The electrolyte is comprised of 50 p,m thick Nafion membrane containing 0.07 mg/cm2 of platinum catalyst particles (d = 1 to 2 nm) and a few weight percent of a hygroscopic material such as silica or titania (d = ca. 5 to 7 nm) . The platinum particles catalyze the oxidation of crossover hydrogen with oxygen to generate water, which in turn is adsorbed by the oxide particles. The cell shows exceptionally stable and high performance even under ambient pressure conditions when operated with hydrogen saturated with water at 20°C and dry oxygen. The internal resistance was measured to be 0.06 R cmY, and the output of the cell was 0.63 W/cmZ, i.e., 0.9 A/cm2 at 0.7 V with an energy efficiency of 60%. The output was 1 W/cm2 in the voltage region of 0.6 to 0.4 V yielding current densities of 1.6 to 2.5 A/cm2. Hydrogen depleted for self-humidification was estimated to be less than a few percent under these operating conditions.

Transcription networks composed of various transcriptional factors specifically expressed in undifferentiated embryonic stem (ES) cells have been implicated in the regulation of pluripotency in ES cells. However, the molecular mechanisms responsible for self-renewal, maintenance of pluripotency, and lineage specification during differentiation of ES cells are still unclear. The results of this study demonstrate that a phosphorylation-dependent chromatin relaxation factor, transcriptional intermediary factor–1β (TIF1β), is a unique regulator of the pluripotency of ES cells and regulates Oct3/4–dependent transcription in a phosphorylation-dependent manner. TIF1β is specifically phosphorylated in pluripotent mouse ES cells at the C-terminal serine 824, which has been previously shown to induce chromatin relaxation. Phosphorylated TIF1β is partially colocalized at the activated chromatin markers, and forms a complex with the pluripotency-specific transcription factor Oct3/4 and subunits of the switching defective/sucrose nonfermenting, ATP-dependent chromatin remodeling complex, Smarcad1, Brg-1, and BAF155, all of which are components of an ES-specific chromatin remodeling complex, esBAF. Phosphorylated TIF1β specifically induces ES cell–specific genes and enables prolonged main-tenance of an undifferentiated state in mouse ES cells. Moreover, TIF1β regulates the reprogramming process of somatic cells in a phosphorylation-dependent manner. Our results suggest that TIF1β provides a phosphorylation-dependent, bidirectional platform for specific transcriptional factors and chromatin remodeling enzymes that regulate the cell differentiation process and the pluripotency of stem cells.