An engine control circuit includes a battery voltage detector, a signal supervisor, and a processor that operates in a normal mode and a power-down mode. This separation method minimizes the effects of radiation damage to the separation material and permits the reliable production of radionuclides of high chemical and radionuclidic purity for use in diagnostic or therapeutic nuclear medicine. The apparatus also includes a valve controller operable to regulate the flow of fluid in liquid phase at least partially through the valve. Its oscillating fin makes it possible to produce the reverse thrust in both the upward and downward leg strokes, thus maximizing the work out and enabling a simulated forward swimming experience. In some embodiments, a vial adaptor is coupled with the vial in order to remove the liquid.