Average color rendering index (Ra) is often used in assessing the color reproduction of objects under a light source. A simple question about “Ra” is that color temperature of light sources is not taken into account to the assessment methodology of color reproducibility. Our study examined the impact of not only Ra but also the color temperature of LED light sources using three experimental methods : subjective assessment of color appearance, categorical color naming method, and measurements of color difference. The results of our three evaluation methods indicate a common suggestion that color appearance under various LED light sources is mainly affected by the color temperature of the light source, not by their Ra.

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Electropolymerized green-colored polycarbazole (PCz) film reacted with ordinary-temperature molten metals (Ga-Sn, Ga-Zn, Ga-In, and Ga) in air to form conducting films with a coloreless transparency (hybridization reaction). The reaction rate was in the increasing order of Ga-In<Ga<Ga-Sn<Ga-Zn, the reason of which was discussed on the basis of the kinetic and energetic aspects. The transmittance and electric conductivity of the resultant typical hybrid films were ca. 90% at a wavelength of 550nm and the order of 10^－3S/cm, respectively. Microanalyses (transmission electron microscopic observation, electron dispersive analysis of X-rays, and X-ray photoelectron spectroscopy) of the hybrid films revealed that they were composed of an undoped PCz backbone in which metal compounds (metal oxide/hydroxide and metal salt) were dispersed. Also, the interaction between the PCz and the metal compounds was suggested by their FT-IR measurements. This interaction explained well the small difference in electric conductivity of the films before and after the hybridization. Additionally, the hybrid films were applied to an electrode for the electrolysis of the solution species. Cyclic voltammetric response of the hybrid film electrodes demonstrated the feasibility of their use for the electrode material in electrochemistry.

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Biological diversity is the result of long evolutionary processes for adaptation to various environments. This diversity has been acquired by “biological processes and techniques” including “production processes”, “operation principles” and “operation systems”, all of which differ from the “human technology”. “Sub-cellular structures” that are often observed on the surface of insects and plants possess characteristic functions. The study of the “biological processes and techniques” will lead to a paradigm shift in “human technology”, and “biomimetic engineering” will solve urgent issues involving the environment, resources, and energy. An interdisciplinary collaboration of natural history, biology, agriculture, materials science, mechanical engineering, information science, and environmental science will open the door to a new engineering system through the combination of the knowledge “learning from biological diversity” and “human wisdom”. A “biomimetics database” as an innovation platform for new industries is required as well as education of new generation with expertise in biology and engineering.

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Living things are great models for manufacturing and products because they have excellent functions and systems, which we cannot turn out in our recent technologies yet. Biomimetics is based on scientific technologies inspired from structures, functions, productive processes, or systems in living things. We are interested in a self-assembly as a bottom-up process and emergent functions from hierarchical structures, those are very common in nature. Then we have focused on DNA, which is one of the essential parts on lives, and worked on the “DNA-templated syntheses”.
In this paper, several studies on formations of nano-structures and assemblies and alignments of molecules or nanoparticles using high molecular recognition ability as one of the excellent functions on DNA, preparations of nanoparticles or nanowires using DNA as templates, and transformations of base sequence information into positional or structural information through the base selective metallization are reviewed as DNA mimetics.

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It is one of the common interests between biologists and robotics engineers to understand the emergence of adaptive behavior. We struggle to realize autonomously adaptive agents in robotics, and should focus on biomimetics based on the neuronal function of animals. In order to understand how animals alter their behaviors on the demand of changing circumstances, I have focused on aggressive behavior in cricket. Cricket battle starts out slowly and escalates into a fierce struggle to establish dominant-subordinate relationship. Pharmacological experiments suggest that nitric oxide signaling mediates octopaminergic system in the brain, which in turn modulates aggressive motivation. In order to understand the mechanisms of group-size dependent aggression, dynamic behavior and neurophysiological models were established based on the results of biological experiments. The models suggests that important mechanism underlying behavior adaptability is a multiple-feedback structure that is composed of feedback loop in the nervous systems and through the social environment.

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Morpho butterfly is known with its conspicuous metallic blue coloration. However, this color is physically anomalous, because it is produced by optical interference effect, whereas always blue (not rainbow color) independent of the viewing angle. The clue to solve this mystery was found to be a specific nanostructures containing both of order and disorder. By extracting the optical essence, we reproduced successfully the artificial Morpho-color, which has recently been found to have various potential applications. This is because the Morpho-color makes colors qualitatively impossible by pigment, resistant to fading over longtime, and enables simultaneously high reflectivity and single color in wide angular range. Although there are many problems for industrial applications such as mass-production, cost, and “design of randomness”, etc., we approach the reality in applications step by step using the updated nanotechnologies. In this report, I summarize our several outcomes and perspective to realize the applications of the specific Morpho-color.

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Biomimicry, or innovation inspired by nature, has seen its applications in various industries. Sharp Corporation has been active in this field and has successfully put 17 “nature” technologies to practical use in its 22 home appliance products, creating and enhancing product values.
This article describes several examples of such applications.

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