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An important method to improve the sensitivity of a nuclear magnetic resonance (NMR) system is to increase the quality factor ( Q ) of the pickup coils. In this paper, we focus on the following three items: 1) effect of the surface resistance ( R s) of the YBa2Cu3O7-δ (YBCO) films on the Q of the NMR pickup coil; 2) relationship between coil line width and current flowing through coil; and 3) effect of Si-ion irradiation to YBCO films on the Q of the NMR pickup coils. In the study of 1), we examined the Q of the NMR pickup coils made by YBCO films with different R s and found that reduction of R s is useful in increasing the Q of the NMR pickup coils. In the study of 2), we simulated the current flowing in the NMR coils by an electromagnetic simulator, and found that wider microstrip lines of the NMR pickup coil increase the current. In the study of 3), we examined Si-ion irradiation effect to reduce R s of YBCO films, and found low irradiation energy and low irradiation density of Si-ion is useful to decrease R s and useful to obtain the high Q NMR pickup coils.

A high-temperature superconducting (HTS) radio frequency (RF) probe has been designed for nuclear magnetic resonance spectroscopy that is constructed of two newly developed HTS elliptical–coupled resonators that are placed on either side of the sample. The probe has a higher quality factor and a more uniform magnetic field along the z -axis than one with square resonators. The measured unloaded quality factor ( Qu ) of a pair of elliptical–coupled resonators fabricated using YBa2Cu3Oy thin films on an Al2O3 substrate was about 30 000 at 15 K, which is about 82 times higher than the simulated Qu of a copper counterpart at room temperature. Measurement of the input power dependence of Qu showed that a Qu of over 20 000 was obtained up to 16 dBm. Measurement of the RF magnetic field profile along the z -axis showed that the RF magnetic field was more than 85% uniform around the sample region.

Unimanual motor tasks change the corticospinal excitability of the trained and untrained side. However, whether the motor task type influences the modulation of the corticospinal excitability of the untrained side remains unclear. This study aimed to clarify the effects of motor tasks on the corticospinal excitability of the untrained side and the relationship between the excitability and motor function. In Experiment I, we measured the corticospinal excitability of the untrained side and motor function after 10 min of motor training in two conditions (gripping task and ball rotation task). The gripping task decreased the excitability. In contrast, excitability remained unchanged after the ball rotation task; further, the modulation of excitability and motor function showed a correlation. In Experiment II, we measured the corticospinal excitability of the untrained side and motor function after two sessions of the ball rotation task. The excitability increased, but motor function remained unchanged after the first session, whereas the excitability decreased to the level observed before training, and motor function improved after the second session. We suggest that the training condition modulates the corticospinal excitability of the untrained side and that this is related to the modulation of motor function.