Biomedical subjects

Nobuyuki Magome

Publications and source records attributed to Nobuyuki Magome.

4 recordsLinked to original sources

PubMed2005

Chemosensitive running droplet.

Chemical control of the spontaneous motion of a reactive oil droplet moving on a glass substrate under an aqueous phase is reported. Experimental results show that the self-motion of an oil droplet is confined on an acid-treated glass surface. The transient behavior of oil-droplet motion is also observed with a high-speed video camera. A mathematical model that incorporates the effect of the glass surface charge is built based on the experimental observation of oil-droplet motion. A numerical simulation of this mathematical model reproduced the essential features concerning confinement of oil droplet motion within a certain chemical territory and also its transient behavior. Our results may shed light on physical aspects of reactive spreading and a chemotaxis in living things.

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PubMed2005

Self-running droplet: emergence of regular motion from nonequilibrium noise.

Spontaneous motion of an oil droplet driven by nonequilibrium chemical conditions is reported. It is shown that the droplet undergoes regular rhythmic motion under appropriately designed boundary conditions, whereas it exhibits random motion in an isotropic environment. This study is a novel manifestation on the direct energy transformation of chemical energy into regular spatial motion under isothermal conditions. A simple mathematical equation including noise reproduces the essential feature of the transition from irregularity into periodic regular motion. Our results will inspire the theoretical study on the mechanism of molecular motors in living matter, working under significant influence of thermal fluctuation.

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PubMed2004

Forward and backward laser-guided motion of an oil droplet.

Directed motion of an oil droplet floating in an aqueous solution is generated by using a laser beam. Interestingly, the direction of the droplet motion can be switched between forward and backward by changing the optical path of the laser through the droplet. This motion is caused above a certain critical power of the laser, and above this value the velocity increases almost linearly with the power. The mechanism of this directed motion is explained as follows: the oil droplet is locally heated by a narrow laser beam, this local heating induces a specific mode of convection inside the droplet, and this generated convective motion produces translational directed motion of the droplet.

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PubMed2002

Rhythmic bursting in a cluster of microbeads driven by a continuous-wave laser beam.

Rhythmic bursting on the order of seconds in a cluster of plastic beads under continuous irradiation of a focused neodymium-doped yttrium aluminum garnet (Nd:YAG) laser beam (1064 nm) is reported. The oscillatory instability is induced as a result of competition between trapping and scattering forces, where both forces are induced by the focused laser beam. Above a critical power of the laser beam, mode bifurcation from the stationary state into periodic bursting is observed. Our model employing ordinary differential equations reproduces the essential aspects of the experimental results.

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