Shigehiro Nishijima

The method of removing micro-plastics from sea water has been developed using electro-magnetic force. Plastics are difficult to decompose and put a great load on the marine environment. Especially a plastic with a size of 5 mm or less is defined as micro-plastic and are carried by ocean currents over long distances, causing global pollution. These are not easily decomposed in the natural environment. The Lorentz force was generated in simulated sea water and its reaction force was applied to the micro-plastic to control their motion. The basic principle of this separation method has already been confirmed by basic experiments. In this study, the magnetic field and current density required to treat seawater containing microplastics using a superconducting magnet with a bore diameter of 5 cm were investigated by simulation. Plastic particles with a diameter of more than 200 m were targeted for separation, and various conditions for separation were investigated by simulation. As a result, it was shown that good separation efficiency was obtained under the following conditions: flow velocity of 0.2 m/s, electrode size of 150 mm, current density of 0.93 A/cm2, and applied magnetic field of 3 T.

The removal of scale by high gradient magnetic separation (HGMS) has been investigated utilizing the magnetic properties of the scale. This study focuses on a thermal power plant with oxygen treatment (OT), which has been applied in many new power plants with large generation capacity in recent years. At high-temperature conditions where the HGMS system is expected to be installed, the viscosity of the fluid will be lower than that of at room temperature, which makes the separation ratio higher. In this study, the scale capture rate at room temperature (25°C) and 80°C was investigated by particle trajectory calculation and experiment, in order to design magnetic separation conditions suitable for the high-temperature environment of the chemical cleaning line of the thermal power plant adopting OT.

For the medical application of superconducting magnets, we investigated a new magnetic drug delivery system that utilizes a rotating magnetic field. To improve the efficiency of drug treatment, a technique that can accumulate the drug in a targeted area is needed. Recently, utilizing a magnetic field by combining ferromagnetic particles and the drugs (ferromagnetic drugs) and applying the magnetic field has been investigated (i.e., Magnetic Drug Delivery System: MDDS). In conventional MDDS, however, the drug can be accumulated only near the body surface because the magnetic field is applied from outside of the body. This indicates that it is difficult to accumulate the drug to a deep target inside the body. We aim to resolve this problem by means of MDDS utilizing a Rotating Magnetic Field (RMF) with superconducting magnets. With this technique it is possible to accumulate a drug selectively in a targeted area, preventing drug accumulation outside of the target by rotating the magnetic field around the central axis of the targeted area. As a fundamental study, we used multiple electromagnets in order to rotate a magnetic field inside the body by controlling the electric current. As a result, we established a fundamental technique to accumulate ferromagnetic particles (a model ferromagnetic drug) at the central axis of the RMF. The feasibility of the technique to accumulate ferromagnetic drugs selectively deep inside the body using the strong magnetic field of superconducting magnets was proven.

In the field of nursing care for the elderly or handicapped people, few service users to 1 care givers as legal standards of personnel positioning at every establishment in Japan. However, there is some lax attention caused by repititive job routine. The program is focused on the specific time and situation, which is guiding the service users to the dining room from each room and waiting for them until everybody is ready to eat. The program will watch each service users' face with a couple of observation points. One is to indentify a pain facial expression which is the main point and the other one is head motion. Both evaluations are analyzed one in different ways. In this study, firstly, a pain stimulation test where healthy adult subjects dipped their hands into ice water was carried out. A strong correlation between pain face factor calculated from the facial expressions digitized by the system and sensory evaluation shown by a pain score, VAS (visual analog scale) value, was observed for young adults. It indicates the validity of this system for the estimation of pain intensity. Secondly, a specific position and motion pattern was regarded as a critical region in each person was decided according to range of motion which was measured in each service user's head by an OT (occupational therapist) and a BS (bornsetter), in order to tell care givers when the service users' head moved in to a critical region or shifted unnaturally. Because there is a grat variation from individual to individual, the motion analysis requires an initial setting for each person. The study indicates the capability of the system by head traking accuracy.