Dual-voltage domain memory buffers, and related systems and methods are disclosed. Another embodiment of the invention provides a method of operating a solid oxide fuel cell, including providing a solid oxide fuel cell comprising an anode electrode containing nickel, periodically operating the fuel cell to generate electricity, and reducing an anode side of the fuel cell between electricity generation operation periods of the fuel cell. The upper tank portions are each provided with a recessed portion that is opened upward and inward. A first character of the paragraph is colored with the first replacement color. When the measured concentration of the functional water goes out of a set concentration range, the functional water is returned to the functional water generator through functional water returning pipe.