2007 Fiscal Year Final Research Report Summary
Interfacial control of various mode-switching for autonomous systems
| Project/Area Number |
18550126
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional materials chemistry
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| Research Institution | Nara University of Education |
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Principal Investigator |
NAKATA Satoshi Nara University of Education, Faculty of Education, Associate Professor (50217741)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Nonlinear / Nonequilibrium / Interface / Switching / Spatio-temporal development / autonomous motor / Chemotaxis / Hystereis |
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| Research Abstract |
As a simple autonomous motor, the self-motion of various ester boats was investigated on water. The time-variation of velocity and the duration of the motion decreased with an increase in the number of carbon atoms in the esters of acetic acid (propyl acetate, butyl acetate, and pentyl acetate). These characteristics of self-motion were qualitatively reproduced by a computer simulation based on the Newtonian motion equation that included the experimental results of surface tension depending on the concentration of ester of acetic acid and the enthalpy of evaporation. We believe that the present system regarding self-motion may be a ueful tool for better understanding surface tension in chemistry in relation to physics and biology.
The photosensitive Belousov-Zhabotinsky (BZ) reaction was investigated on a double rectangular field composed of two rectangular routes, which was drawn using computer software and then projected on a filter paper soaked with BZ solution using a liquid-crystal
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projector. When two chemical waves were generated on the rectangular routes as the initial condition, the nature of the collision of the waves could be theoretically classified into four categories depending on the initial phase difference between the two waves and the aspect ratio of the rectangular routes. The experimental results were consistent with the features of the theoretical prediction. These results suggest that the photosensitive BZ reaction maybe useful for studying spatiotemporal development that depends on the geometry of the excitable fields.
Using different chemical-sensing systems, we show that by observation of time-dependent nonlinear responses one can improve the sensor selectivity with respect to target samples. We discuss the nonlinear perturbation and the related response in two cases: 1. A periodic change in temperature was applied to a SnO2 semiconductor gas sensor. The resulting sensor response was analyzed by fast Fourier transformation and the higher harmonics are a source of abundant intimation for molecular recognition. 2. The measurements of synchronization in a Wien bridge circuit connected the electrode system or the semiconductor gas sensor coupled with an external sinusoidal operational force. In this case, sensing is based on the shape of return maps.
The surface structure of a soy milk skin, as a simple artificial film, was found to be characteristically sensitive to chemical stimuli. The surface structure of the film was imaged by AFM and the shape and size of concavities on the film were analyzed to characterize the chemical response. This characteristic pattern formation of the soy milk skin is discussed in relation to the surface aggregation, electronic charge, and solubility of soy protein molecules around the air/water interface. We believe that the investigation of such an artificial film prepared under nonequilibrium conditions could lead to the creation of a novel artificial film that can adapt to the chemical environment and that spatio-temporal information, such as in pattern formation, may be able to provide multi-dimensional information for use in a chemical-sensing system. Less
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