Rotating machines with high-temperature superconductors (HTS) usually consist of pole-field magnets having coils wound with Bi-2223 HTS wire. We have successfully used Gd–Ba–Cu–O bulk HTS in pole-field magnets in an axial-gap type rotating machine. These HTS pole-field bulk magnets were assembled in the rotor plate. They are cooled down with a liquid cryogen supplied via a rotary joint and circulated inside the rotor plate. The present design provides a small air gap and a bulk HTS gives a high magnetic field around the armature coils. Successful mechanical design has enabled us to magnetize the pole-field bulk to more than 1 T by using a pulsed current applied to the copper armature coils. These techniques imply the possibility of smaller and lighter rotating motors or generators with a HTS bulk magnet for a sub-megawatt class propulsion system. We report several essential techniques for both mechanical and cryogenic designs, and deduce the characteristic features of the present axial-gap type machine using a HTS bulk magnet.

We previously reported that μ-oxo N,N’-bis(salicylidene)ethylenediamine iron [Fe(Salen)], a magnetic organic compound, has direct anti-tumor activity, and generates heat in an alternating magnetic field (AMF). We showed that Fe(Salen) nanoparticles are useful for combined hyperthermia-chemotherapy of tongue cancer. Here, we have examined the effect of Fe(Salen) on human glioblastoma (GB). Fe(Salen) showed in vitro anti-tumor activity towards several human GB cell lines. It inhibited cell proliferation, and its apoptosis-inducing activity was greater than that of clinically used drugs. Fe(Salen) also showed in vivo anti-tumor activity in the mouse brain. We evaluated the drug distribution and systemic side effects of intracerebrally injected Fe(Salen) nanoparticles in rats. Further, to examine whether hyperthermia, which was induced by exposing Fe(Salen) nanoparticles to AMF, enhanced the intrinsic anti-tumor effect of Fe(Salen), we used a mouse model grafted with U251 cells on the left leg. Fe(Salen), BCNU, or normal saline was injected into the tumor in the presence or absence of AMF exposure. The combination of Fe(Salen) injection and AMF exposure showed a greater anti-tumor effect than did either Fe(Salen) or BCNU alone. Our results indicate that hyperthermia and chemotherapy with single-drug nanoparticles could be done for GB treatment.

Effects of cyclic stress on the mechanical properties of collagen fascicles were studied by in vitro tissue culture experiments. Collagen fascicles (approximately 300 microns in diameter) obtained from the rabbit patellar tendon were applied cyclic load at 4 Hz for one hour per day during culture period for one or two weeks, and then their mechanical properties were determined using a micro-tensile tester. There was a statistically significant correlation between tensile strength and applied peak stress in the range of 0 to 5 MPa, and the relation was expressed by a quadratic function. The maximum strength (19.4 MPa) was obtained at the applied peak stress of 1.8 MPa. The tensile strength of fascicles were within a range of control values, if they were cultured under peak stresses between 1.1 and 2.6 MPa. Similar results were also observed in the tangent modulus, which was maintained at control level under applied peak stresses between 0.9 and 2.8 MPa. The stress of 0.9 to 1.1 MPa is equivalent to approximately 40% of the in vivo peak stress which is developed in the intact rabbit patellar tendon by running, whereas that of 2.6 to 2.8 MPa corresponds to approximately 120% of the in vivo peak stress. Therefore, the fascicles cultured under applied peak stresses of lower than 40% and higher than 120% of the in vivo peak stress do not keep the original strength and modulus. These results indicate that the mechanical properties of cultured collagen fascicles strongly depend upon the magnitude of the stress applied during culture, which are similar to our previous results observed in stress-shielded and overstressed patellar tendons in vivo.

The effects of frequency or duration of cyclic stress on the mechanical properties of collagen fascicles were studied by means of in vitro tissue culture experiments. Collagen fascicles of approximately 300 microm in diameter were obtained from rabbit patellar tendons. During culture, cyclic stress having the peak stress of approximately 2 MPa was applied to the fascicles at 1 Hz for 1 hour/day (1 Hz-1 h group), at 1 Hz for 4 hours/day (1 Hz-4 h group), or at 4 Hz for 1 hour/day (4 Hz-1 h group). The frequency of 4 Hz and the duration of 1 hour/day are considered to be similar to those of the in vivo stress applied to fascicles in the intact rabbit patellar tendon. After culture for 1 or 2 weeks, the mechanical properties of the fascicles were determined using a microtensile tester, and were compared to the properties of non-cultured, fresh fascicles (control group) and the fascicles cultured under no load condition (non-loaded group). The tangent modulus and tensile strength of fascicles in the 4 Hz-1 h group were similar to those in the control group; however, the fascicles of the 1 Hz-1 h and 1 Hz-4 h groups had significantly lower values than those of the control group. There was no significant difference in the tensile strength between the 1 Hz-1 h and non-loaded groups, although the strength in the 1 Hz-4 h group was significantly higher than that of the non-loaded group. It was concluded that the frequency and duration of cyclic stress significantly affect the mechanical properties of cultured collagen fascicles. If we apply cyclic stress having the frequency and duration which are experienced in vivo, the biomechanical properties are maintained at control, normal level. Lower frequencies or less cycles of applied force induce adverse effects.

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