Gas phase nanoparticle production, manipulation and deposition is of primary importance for the synthesis of nanostructured materials and for the development of industrial processes based on nanotechnology. In this review we present and discuss this approach, introducing cluster sources, nanoparticle formation and growth mechanisms and the use of aerodynamic focusing methods that are coupled with supersonic expansions to obtain high intensity cluster beams with a control on nanoparticle mass and spatial distribution. The implication of this technique for the synthesis of nanostructured materials is also presented and applications are highlighted.

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In this review we discuss the current state of the art in evaluating the fabrication and performance of biomimetic superhydrophobic materials and their applications in engineering sciences. Superhydrophobicity, often referred to as the lotus effect, could be utilized to design surfaces with minimal skin-friction drag for applications such as selfcleaning and energy conservation. We start by discussing the concept of the lotus effect and continue to present a review of the recent advances in manufacturing superhydrophobic surfaces with ordered and disordered microstructures. We then present a discussion on the resistance of the air-water interface to elevated pressures-the phenomenon that enables a water strider to walk on water. We conclude the article by presenting a brief overview of the latest advancements in studying the longevity of submerged superhydrophobic surfaces for underwater applications.

A mathematical framework is developed to predict the longevity of a submerged superhydrophobic surface made up of parallel grooves. Time-dependent integrodifferential equations predicting the instantaneous behavior of the air-water interface are derived by applying the balance of forces across the air-water interface, while accounting for the dissolution of the air in water over time. The calculations start by producing a differential equation for the initial steady-state shape and equilibrium position of the air-water interface at t = 0. Analytical and/or numerical solutions are then developed to solve the time-dependent equations and to compute the volume of the trapped air in the grooves over time until a Wenzel state is reached as the interface touches the groove's bottom. For demonstration, a superhydrophobic surface made of parallel grooves is considered, and the influence of the groove's dimensions on the longevity of the surface under different hydrostatic pressures is studied. It was found that for grooves with higher width-to-depth ratios, the critical pressure (pressure at which departure from the Cassie state starts) is higher due to stronger resistance to deflection of the air-water interface from the air trapped in such grooves. However, grooves with higher width-to-depth ratios reach the Wenzel state faster because of their greater air-water interface areas.

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