This work presents the results of investigations on different aspects of cryogenic operation of BAW resonators. For the quartz crystal resonators the losses mechanisms, the temperature sensitivity, the amplitude-frequency effect are described for liquid helium temperatures. The corresponding problems are discussed. To overcome some of these problems, the possible solution of operation at higher modes is considered. Some of these higher modes exhibit outstanding quality factors. The highest (for BAW resonators) quality factor value and quality factor-frequency product are measured for the 11th and 13th overtones respectively. In addition, two LGT resonators have been characterized in a wide temperature range. Finally, some preliminary results on utilization of cryogenic quartz resonators as a part of a frequency stabilization closed loop system are given.

How carbon nanotubes behave in an external electric field? What will be the relation between the intensity of the electric field and the tube's deformation? What are the geometry effects on the response of carbon nanotubes to electric fields? To answer these questions, we have developed a new combined computational technique to study electrostatic field induced deformations of carbon nanotubes. In this work, we find that the deflection angle of cantilevered semiconducting single-walled carbon nanotubes is proportional to the square of the electric field strength, and the tubes can be most bent when the field angle ranges from 45 to 60 degrees. Furthermore, the deflection angle is also found to be proportional to the aspect ratio L/R. Our results provide a good qualitative agreement with those of one previous experimental study.

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