The invention provides for methods for the production of isoprene in recombinant marine bacterial cells via the heterologous expression of isoprene synthase enzymes. The tantalum nitride compound layer is formed by thermally decomposing a tantalum containing metal organic precursor. The bilayer mouthguard has a U-shape base and is defined by inner lingual and outer labial walls, a channel for receiving the upper jaw and teeth, cushion pads laying within the U-shape base, and in certain designs a transition support portion extending forward from the posterior cushion pads connecting with an anterior impact brace that extends into the outer labial wall. A magnet mounted to the carrier also moves longitudinally with respect to the axis of the shaft, and relative to a magnetic field sensor configured to detect the magnet’s longitudinal position. Moreover, since the carbon plate is porous, it can provide a communication path between a vacuum source and an air-permeable, ink-impermeable layer on the ink passages to remove dissolved air from the ink in the passages.