Exemplary embodiments of apparatus, source arrangement and method for, e. In one aspect, there is provided a mixture for the storage and delivery of at least one gas comprising: an ionic liquid comprising an anion and a cation; and at least one gas that is disposed within and is reversibly chemically reacted with the ionic liquid. A structure includes a bladed wheel including a plurality of circumferentially spaced blades extending from a hub, and a set of mid-span structures coupling adjacent blades of the plurality of circumferentially spaced blades. The stepped member is exemplified by functional bumps and dummy bumps having stepped regions.