Abstract: Disclosed is a process for the preparation of a composite including a room temperature vulcanizing silicone rubber and a chemically resistant polyester film which may be polyethylene terephthalate. The composite has particular utility as a part of medical equipment, for example as a component in an ultrasonic transducer. The susceptibility of the composite bond so formed to chemical challenge in the user environment is reduced or eliminated.

Abstract: The base for an array of piezoelectric crystals contains tungsten particles that are compression-molded in a binder, the size of the particles at and near the surface on which the crystals are mounted being smaller than the size of the particles remote from the surface.

Abstract: A method and apparatus utilizing a quartz crystal resonator with an orientation substantially equal to (yxwl) 21.93.degree./33.93.degree. vibrating simultaneously in two thickness modes to provide a stable frequency signal source. By combining a quartz crystal resonator of the above type with either digital or analog compensation, the frequency-temperature deviation of one of the crystal mode frequencies is used as an internal thermometer and the second crystal mode frequency as a reference frequency signal. The frequency signal for the thermometer function is utilized by the compensation network to stabilize the frequency of the reference signal. Additionally, the analog or digital compensation is accomplished by means of either a curve-fitting routine or an interpolation look-up table routine.

Abstract: A method and apparatus utilizing a quartz crystal resonator with an orientation substantially equal to (yxwl) 21.93.degree./33.93.degree. vibrating simultaneously in two thickness modes to accurately measure temperature and unknown frequencies or to provide a stable frequency signal source. By combining a quartz crystal resonator of the above type with either digital or analog compensation, the frequency-temperature deviation of one of the crystal mode frequencies is used as an internal thermometer and the second crystal mode frequency as a reference frequency signal. The frequency signal for the thermometer function is utilized by the compensation network to correct the measurements made with, or to stabilize, the frequency of the reference frequency signal. Additionally, the analog or digital compensation is accomplished by means of either a curve-fitting routine or an interpolation look-up table routine.