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The effect of heat treatment on the taste of milk was investigated using a taste sensor. The transducer is composed of seven electrodes with different kinds of lipid membranes. Sensory evaluations by humans were made in terms of three taste characteristics of “richness (koku),” “cooked flavor” and “deliciousness” together with a measurement of whey protein denaturation. This study provided a quantitative description of the taste change caused by heat treatment of milk, because the output showed high correlations with richness and the degree of protein denaturation.

Taste of amino acids was studied using a multichannel taste sensor with lipid membranes as the transducer of taste substances. The study on taste of amino acids has drawn much attention so far because each of them elicits complicated mixed taste. The response of the sensor to amino acids was compared with results of panel tests, and response potentials from the eight membranes were transformed to terms representing five basic tastes by multiple linear regression. This expression of five basic tastes reproduced human taste sensation very well. The taste was expressed more quantitatively by assuming new channels, which are represented by multiplication of the response potentials of the original channels. This new set of channels implies the existence of processes involving the nervous system which is connected with taste cells.

An artificial excitable lipid membrane, which is composed of a porous filter filled with lipids, exhibits self-sustained oscillation of the membrane potential by DC electric current imposed across the membrane. The system yielded various electric oscillatory responses to sinusoidal AC electric currents superimposed on the DC current. At adequate frequency and amplitude of the sinusoidal stimulation, the oscillation was entrained (or synchronized) to the stimulation; the oscillation was desynchronized when the parameter (frequency or amplitude) was deviated to some extent from the initial value. Aperiodic oscillations appeared for parameter values located between entrained regions. Detailed analyses revealed that the aperiodic oscillations were chaotic, which was first shown quantitatively in artificial membrane systems.

It is known that thiol-containing compounds form monolayer membranes on a gold surface via chemisorption from organic solvents in terms of a strong connection ability between thiol and the metal. Here we prepared different kinds of thiol-containing lipids and fabricated monolayer membranes on the gold disk electrode whose surface structures were similar to biological membranes. Responses of this lipid-coated electrode to odor substances were examined by an electrochemical method of a cyclic voltammetry. Blocking ability for the redox reaction of Fe(CN)6 3- was found to change upon adsorption of odor substances into monolayer membranes. The order of threshold values to detect the odorants was β-ionone

The normalized decay rate R of magnetization due to thermally activated flux creep is typically given by R≃k B T/U c, where k B is the Boltzmann constant, T is the absolute temperature and U c is the effective pinning potential. Some observed data for high-T c superconductors show that R increases with increasing T, while in other studies, R takes a peak at a certain temperature T m below the critical temperature T c, where T m decreases with increasing external magnetic field. These temperature dependences of R are explained systematically on the basis of a recent theory of flux creep developed by the authors.

A correlation dimension and a distribution pattern of spectrum intensities of a self-sustained electric oscillation were studied for an aperiodic oscillation induced by an application of electric current on a membrane of a synthetic lipid, dioleyl phosphate. The estimated dimension showed a remarkable deviation in the presence of taste substances such as quinine (above a certain threshold value) from that in the absence of these taste substances; this deviation was accompanied by a change in spectrum pattern. The present result indicates that the two variables extracted from the aperiodic oscillations will be useful as sensing information in a chemical taste sensor using lipid membranes.

A formal theory of macroscopic pinning force FP is presented from a viewpoint that FP of is a value of Lorentz force FL at a bifurcation point, JT=Jc, above which a nondissipative state fluxoi'd lattice carrying a transport current with the density JT becomes unstable and a dynamic dissipative state called the flux flow appears. It is shown that correlation lengthes among pinned fluxoids diverge at the bifurcation point Jc, as these do in other bifurcation phenomena.