20 research outputs found
Slowing and stopping of chemical waves in a narrowing canal
The propagation of a chemical wave in a narrow, cone-shaped glass capillary
was investigated. When a chemical wave propagates from the wider end to the
narrower end, it slows, stops, and then disappears. A phenomenological model
that considers the surface effect of the glass is proposed, and this model
reproduces the experimental trends.Comment: 8 pages, 5 figure
Mode Selection in the Spontaneous Motion of an Alcohol Droplet
An alcohol (pentanol) droplet exhibits spontaneous agitation on an aqueous
solution, driven by a solutal Marangoni effect. We found that the droplet's
mode of motion is controlled by its volume. A droplet with a volume of less
than shows irregular translational motion, whereas
intermediate-sized droplets of show vectorial motion. When
the volume is above , the droplet splits into smaller drops.
These experimental results regarding mode selection are interpreted in terms of
the wave number selection depending on the droplet volume.Comment: 4 pages, 5 figure
Chemo-Sensitive 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 within a certain
chemical territory of oil-droplet motion, and also its transient behavior. Our
results may shed light on physical aspects of reactive spreading and a
chemotaxis in living things.Comment: 17 pages, 10 figure
Plastic bottle oscillator: Rhythmicity and mode bifurcation of fluid flow
The oscillatory flow of water draining from an upside-down plastic bottle with a thin pipe attached to its head is studied as an example of a dissipative structure generated under far-from-equilibrium conditions. Mode bifurcation was observed in the water/air flow: no flow, oscillatory flow, and counter flow were found when the inner diameter of the thin pipe was changed. The modes are stable against perturbations. A coupled two-bottle system exhibits either in-phase or anti-phase self-synchronization. These characteristic behaviors imply that the essential features of the oscillatory flow in a single bottle system can be described as a limit-cycle oscillation
The accumulation rate and benthic fluxes for selenium in the marginal seas
This paper describes the concentrations of selenite, selenate and organic selenide in pore water, and selenium in sediment cores in the marginal seas. The selenium accumulation rates for the Sulu Sea and the South China Sea were 1.16 and 0.21 mg cm^yr^. The upward diffusive fluxes of dissolved selenium were estimated by using Fick’s first law. The calculated fluxes od dissolved selenium as selenate in the Sulu and South China Seas were estimated to be 0.17 and 0.88 μg cm^yr^, respectively.本文データは一部CiNiiから複製したものである
Survival versus collapse: Abrupt drop of excitability kills the traveling pulse, while gradual change results in adaptation
Excitable media show changes in their basic characteristics that reflect temporal changes in the environment. In the photosensitive Belousov-Zhabotinsky (BZ) reaction, excitability is decreased by illumination. We found that a traveling pulse failed to propagate when a certain level of light intensity was switched on abruptly, but the pulse continued propagating when the light intensity reached the same level gradually. We investigated the mechanism of adaptation of pulse propagation to the change in light intensity using two mathematical models, the Oregonator model (a specific model for the photosensitive BZ reaction), and the FitzHugh-Nagumo model (a generic model for excitable media). The appearance of a characteristic such as adaptation is shown to be a general feature for a traveling pulse in excitable media. © 2007 The American Physical Society