Spiral-type magnetic micro-machines, which are driven by a rotating magnetic eld, are characterized by their wireless operation for swimming. The machines have to swim in a lower Reynolds number (Re) environment, when the machines are downsized, and work inside the human body. In this study, using various silicone oils whose kinematic viscosity ranged from 500 to 5 £ 10 5 mm 2 /s, the swimming performance of the machine in an environment characterized by a low Reynolds number was examined. The machine, with a cylindrical NdFeB magnet as main component, could swim in the oils with Re D 10 ¡7 . This Reynolds number is same as that of a micro-machine with micron size swimming in the water. In addition, the machine could turn by controlling the external rotational magnetic eld, therefore the swimming direction of the machine could be controlled. Using these principles, a magnetic micro-machine, which can run in a gel, was also fabricated.
In order to examine the relation between damage evolution and changes in microstructure, e.g. from creep cavities, surface micro‐cracks and dislocation structures at high temperature, strain controlled creep‐fatigue tests were performed and interrupted at several damage levels on Types 304 and 316 stainless steels. The creep‐fatigue tests on Type 304 stainless steel at a low strain level were conducted in a high‐temperature fatigue testing machine combined with a scanning electron microscope, and the micro‐crack initiation and growth behaviour were continuously observed to clarify the damage extension mechanism. It was found that even though many cavities were initiated and grew on the internal grain boundaries of the specimens during the strain‐controlled tests, the failure life was governed by the propagation of surface cracks. On the other hand, micro‐cracks of about the order of one grain size were initiated mainly along grain boundaries normal to the loading axis under low stress creep‐fatigue, and the crack propagation rate of the micro‐cracks was slow and random due to the nature of the microstructures. The micro‐cracks gradually opened in the loading direction with increasing number of cycles and coalescence contributed to growth.
Yellow nail syndrome is a relatively rare disease that is characterized by yellow nail, lymphedema and pleural effusion. These symptoms occur to various degrees, but occasionally pleural effusions are interactive and can become life-threatening. We report the case of a 15-year-old girl with yellow nail syndrome with interactive bilateral pleural effusions who was treated with pleuroperitoneal shunting. Drainage from the pleural cavity to the peritoneal cavity improved oxygenation and permitted removal of bilateral chest tubes that had been inserted for long term relief. We discuss the benefits and difficulties of this procedure and define the characteristics of patients with yellow nail syndrome who were treated with pleuroperitoneal shunt for pleural effusions, based on a literature review. The procedure may be an alternative rescue strategy for patients with interactive pleural effusions.
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