The Cover shows drop-wise condensation taking place on a produced copper surface: spherical droplets form on the hydrophobic side (the upper part of the picture), and droplets gradually spread out to a wavy film when moving to the hydrophilic side (The lower part of the picture). The wettability gradient can improve the rate of condensation up to 30% when the gradient is synergetic with gravity. Further details can be found in the article by X. J. Hu et. al. on page 491.