Abstract: Embodiments described herein provide systems and methods for acoustically driving spin rotations of diamond nitrogen-vacancy (NV) centers using acoustic transducers. The acoustic transducers may comprise devices such as bulk acoustic resonators or surface acoustic resonators. The systems and methods may allow driving of ms=0 to ms=?1, ms=0 to ms=+1, ms=?1 to ms=0, and ms=+1 to ms=0 single-quantum (SQ) spin transitions without the need to apply magnetic field pulses. This may substantially reduce the size and power requirements of NV center-based sensors. The systems and methods may be used to conduct a variety of measurements, such as measurements of magnetic field, electric field, orientation, strain, or temperature.

Abstract: A check valve or backflow preventer has a valve mechanism mounted to a valve cover for removal and replacement as a unit. The valve clapper is resiliently supported to accommodate variations in tolerance. The valve seat is removably secured within the valve body by compression of a resilient seal ring to engage opposed walls of the seat and body. A spring pretensioning member facilitates safe replacement and removal of the valve mechanism.

Abstract: A check valve or backflow preventer has a valve mechanism mounted to a valve cover for removal and replacement as a unit. The valve clapper is resiliently supported to accommodate variations in tolerance. The valve seat is removably secured within the valve body by compression of a resilient seal ring to engage opposed walls of the seat and body. A spring pretensioning member facilitates safe replacement and removal of the valve mechanism.