Self-assembled monolayers (SAM) of mercaptohydroquinone (MHQ) were constructed on a Au(111) surface. Redox charge due to hydroquinone/benzoquinone reaction of the MHQ SAM modified Au(111) electrodes was dependent on the concentration of atrazine contained in an electrolyte solution, indicating that the MHQ SAM modified Au(111) electrode functioned as an atrazine sensor.
Flattening processes of a commercially available Au(111) single crystal surface were step-by-step investigated using atomic force microscopy (AFM), scanning tunneling microscopy (STM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS) from a micron scale to an atomic dimension. AFM images in a micron scale showed that there were many scratches with a few nm depth on the as-received Au(111) disk surface. SEM, EDX, and XPS results indicated that there were surface contaminations such as carbon and silicon species. As a first, these contaminations could be removed by dipping the disk in concentrated H 2 SO 4 and then in boiling concentrated HF. The scratches described above were disappeared after annealing by a gas flame, which is a most popular method for Au(111) single crystal preparation. After the electrochemical polishing and annealing in an electric furnace under argon atmosphere, finally, atomically flat Au(111) surfaces with dimensions of more than 500 × 500 nm 2 were obtained. With increasing of annealing period, larger terraces were obtained.
Self-assembly process of a porphyrin derivative [5,10,15,20-tetra-(m-mercapto-p-methoxyphenyl) porphyrin; TMMPP], which was designed and synthesized to be flatly adsorbed on a gold substrate surface, on a Au(111) single crystal surface was investigated by ex situ scanning tunneling microscopy (STM) and electrochemical reductive desorption measurements. A small number of TMMPP molecules were randomly but flatly adsorbed on the Au(111) surface when the deposition time was less than 1 h as the initial stage of the self-assembly process. When the deposition time was more than 20 h as the final stage of the self-assembly process, the densely-packed and flatly adsorbed TMMPP SAM formed on the Au(111) surface via a phase transition from a random to an ordered structure. These results indicated that we succeeded in the formation of the flatly adsorbed and well-defined porphyrin selfassembled monolayer (SAM) on the Au(111) surface.
Toward analysis of multicell-turnover patterns by using multivariable polynomials Hirosi Yosida (Faculty of Math. Kyushu Univ.) Campbell, who performed many experiments in Hydra, noted: "The cells and tissues of hydra are in continuous flux. The polyp undergoes perpetual growth and tissue loss, coupled by balanced cell renewal patterns involving all cell types" [1]. I studied a bio-inspired model of patterns that regenerate in flux, namely regenerate through turnover in [2,3], where I parameterized the manner of the redistribution of Dachsous and Fat, and then derived equations to make turnover feasible. I here propose a method for analyzing multicell-turnover patterns by using multivariable polynomials.
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