Recently, a large variety of disease-model experimental animals, which are generated by gene modification or drug inducement, have become available for studying disease development and treatment. Biomagnetic measurement has been considered a powerful tool in the study of disease-model animals since it is a completely non-invasive and contact-free technique for the functional mapping of a living body. This paper reviews the biomagnetic studies of experimental animals for the purpose of elucidating the electrophysiological functions of the brain and heart, and introduces our newly developed magnetocardiogram (MCG) measurement system for mice. We have developed the system using a dc superconducting quantum interference device (SQUID) magnetometer to make comparative MCG studies of disease-model mice in order to clarify the mechanism of disease development in a living body. We measured the MCG of wild-type (control) and aconitine-induced arrhythmia model mice. The difference in the spatial distribution and time course of the MCG signals between regular sinus rhythm and arrhythmia was clearly evaluated. The results suggest that the system presented is capable of screening the cardiac excitation pathway of mice in good spatial and time resolution.
We have developed a system that uses a superconducting magnet to remove arsenic from geothermal water. The advantages of applying a high-field, high-gradient magnetic separator (HGMS) and a reciprocating high-gradient magnetic separator for practical use are presented. Finally, we demonstrate that the capture efficiency of the HGMS does not depend on dimensions, and show that properties of a large HGMS plant can be estimated from our experimental results.
The MOD process for producing YBCO-coated conductors using metal trifluoroacetate (TFA) precursors is expected to be a strong candidate as a fabrication process for coated conductors since the TFA-MOD process is a non-vacuum process that has succeeded in the providing high Jc films. In this paper, recent progress in R&D for long coated conductors using TFA-MOD processing is reported. Recently, in order to fabricate long tapes with high performance, continuous reel-to-reel systems have been developed for 1) coating system and calcinations, and 2) crystallization processes. In order to confirm the ability of this continuous reel-to-reel system, the Ic distribution of a 25 m-long tape was investigated. As a result, the uniformity of the textured YBCO layer was confirmed by maintaining a high Ic of over 200 A along the entire tape.
The metal organic deposition (MOD) method which uses solution materials including trifluoroacetates (TFA) as a solute, is one of the most promising methods to fabricate high-quality superconducting wires at low coast. In this study, a new combination of starting materials was developed using F-free salt of Cu and TFA salts of Y and Ba in order to shorten annealing time. Moreover, a new process temperature profile for this solution was developed as an advanced TFA-MOD process, in which a high heating rate was achieved. As a result, an overall transport Ic value of 210 A and a Jc value of 1.5 MA/cm2 at 77 K in a self-field similar to Ic and Jc values using TFA for all salts were obtained. In order to obtain higher Jc performance, the effect parameters such as partial pressure of the water vapor in the annealing process were investigated. Consequently, a YBCO film of 1.3 μm in thickness was fabricated on a CeO2/IBAD-Gd2Zr2O7 layer buffered Hastelloy substrate with Δφ =4°. Consequently, the Ic values increased as the water vapor pressure increased during the crystallization, and the overall transport Ic value of 340 A at 77 K in a self-field was obtained by annealing under a partial water vapor pressure of 6.3 vol%.