[ASME ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting - Rio Grande, Puerto Rico, USA (Sunday 8 July 2012)] ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels - Monte Carlo Simulations to Determine Effective Gas Diffusivity of an Actual Porous Medium Image Obtained From Focused Ion Beam Scanning Electron Microscopy