A power supply apparatus includes a generator, lead-battery, and second-battery. In some embodiments, the methods and systems can include a viscosity in the ratio, determining a flow rate at ambient pressure using a factor based on a ratio of a gas pressure at the output and ambient pressure, andor, determining a flow rate at ambient temperature using a factor based on a ratio of a temperature at the output and ambient temperature. The port modules have configurable logic configured to process communications for routing communications. The electrical load includes at least one load hot conductor, a load neutral conductor, and a load ground conductor. The heated absorption liquid is flown into a vapor-liquid separator in a mixed state of vapor and liquid, and then separated into refrigerant vapor and further concentrated absorption liquid. Also provided are methods of predicting the activity or substrate specificity of putative O-methyl-transferases, methods of identifying potential substrates of O-methyltransferases, and methods of identifying potential inhibitors of methyltransferases.