Magnetic alignment technology using the modulated rotating magnetic fields (MRF) enables formation of tri-axial grain arrangement of the substances with tri-axial magnetic anisotropy. In this review, we introduce a high potential of magnetic alignment technique as the fabrication process of tri-axially grain-oriented cuprate superconductors. As the first topic, we reported the tri-axial magnetic alignment of rare-earth-based and bismuth-based cuprate superconductors operated at room temperature. In the second topic, we show the importance of single-ion magnetic anisotropy of the rare-earth ions as a determination factor of magnetization axes and the tri-axial magnetic anisotropy in rare-earth-based cuprate superconductors. The final topic is the fabrication of tri-axially grain-aligned ErBa2Cu4O8 (Er124) ceramics under a modified MRF. To date, the Er124 ceramic with the degree of in-plane orientation with ~11 degree has been successfully fabricated by controlling the viscosity of slurry and introducing the oscillation type of MRF.
The magnetic field effects on the synthesis process, decomposition process, and the phase equilibrium of materials have been investigated via thermal analysis experiments in high magnetic fields (HF-DTA). In this review, the thermal analysis systems in high magnetic fields are described. The typical results obtained by HF-DTA are presented. The magnetic field effects on the synthesis process of the high-Tc superconductors and the phase equilibrium of ferromagnetic materials are described. The results of HF-DTA experiments show that the phase equilibriums of Bi-Mn system and Fe-C alloys are drastically changed by applying high magnetic fields. In addition, HF-DTA experiments were performed for various compositions of Bi-Mn alloys. BiMn binary phase diagrams in high magnetic fields were shown. The magnetic field effects on the phase equilibrium were discussed in the basis of Zeeman energy of the ferromagnetic phase.
This review provides an outline of the “high-efficiency/high-quality protein crystal formation system” project. Precise determination of protein structures provides significant information for R&D on drugs and enzymes. Protein crystals of high integrity grown with high efficiency can accelerate such R&D. At present, a condition suitable for a certain protein crystal growth can only be found after several thousands of different conditions are examined by changing various parameters such as solvents, coexisting materials, temperature, pH and so on. It is considered that the convection of solution prevents the formation of good-quality crystal. Therefore, the control of gravity force effect through large magnetic force may be one of the potential parameters for protein crystal growth because it should contribute to suppressing the convection. To exert large magnetic force on protein solution or crystals equivalent with gravity force, high magnetic fields using a superconducting magnet are required. Observation of the crystallization process is important for efficient crystal formation, but it is difficult to carry out in-situ optical observation inside the superconducting magnet bore due to the existence of the high magnetic field. To facilitate efficient protein crystal growth under magnetic force, we developed a microscopic optical observation apparatus for multiple samples placed in a high magnetic field. The system consists of a superconducting magnet, crystallization plates and an optical periscope. The superconducting magnet used for this system is a high magnetic force generation type. The developed crystallization plates can contain 24 different protein solutions and can be stacked on each other. The 3D controllable periscope is made mainly from feeble magnetic materials that can be operated in high magnetic fields.
Medical protein such as monoclonal antibody or immunoglobulin is an important substance as a medicine for cancer. However, the separation system of this medical protein has a very low separation rate and the cost of the product is extremely high. We have successfully developed a high gradient magnetic separation system for medical protein using affinity magnetic nanobeads. The system shows very high separation efficiency and can save costs based on a large production rate compared to the current system. The system consists of a 3 T superconducting magnet cooled by a cryocooler, a magnetic filter made of magnetic metal fibers of approximately 30 μm diameter, a demagnetization circuit for the filter, and a circulation pump for the medical protein solution. The medical protein is immobilized to affinity magnetic nanobeads after agitation of the protein and nanobeads mixture, then the mixture flows through the system and the beads are trapped in the filters by a high gradient magnetic field. The trapped beads flow out of the system by the AC demagnetization of the filters using LC resonance circuits after magnet discharge. The test results show 98% of the magnetic nanobeads in pure water were captured and 94% of total beads were collected.