Novel thiophene oligomers containing a redox active hexaarylethane unit

[structure: see text] Novel thiophene oligomers containing a redox active hexaarylethane unit have been prepared as a new class of molecular wires having a large electrochemical bistability and definitely characterized by using single-crystal X-ray structure analysis and redox potential measurements. They constitute reversible redox pairs with the corresponding bis(thioxanthyl) dications by undergoing C-C bond making/breaking. They show unique electrochromism and a fluorescence change during interconversion.     

Functional sulfur amino acid production and seawater remediation system by sterile Ulva sp. (chlorophyta)

Sterile Ulva, which is a macroalga, has the potential to grow stably; therefore, this seaweed is expected to be an efficient resource of functional food containing various nutrients such as sulfur amino acids, proteins, carbohydrates, and minerals. Ulva lactuca was selected from the “Marine Park” in Tokyo Bay, and its growth rate (g-dry/[m²·d]) was measured using model reactors located on the land or on the surface of the sea at Yokohama. The growth rate of U. lactuca was recorded to be approx 20 g-dry/(m²·d), which is estimated to be 10 times greater than that in a natural field in the Marine Park. In addition, this growth rate was higher than that of conventional crops such as corn and rice on a farm or paddy. These data led us to newly design and propose a floating type of labor-efficient U. lactuca production system. d-Cysteinolic acid, which is included in U. lactuca as a major sulfur amino acid, inhibited the Fenton reaction, resulting in suppression of hydroxyl radical production and singlet oxygen. Addition of the sulfur amino acid (1μM) to HepG2 cells markedly decreased the intracellular triglyceride level. Hence, this proposed facility also has the potential for industrial production of a valuable resource for the primary prevention of lifestyle-related diseases using enriched or eutrophied seawater.     

Effects of inversion asymmetry on electron-nuclear spin coupling in semiconductor heterostructures: possible role of spin-orbit interactions

We show that electron-nuclear spin coupling in semiconductor heterostructures is strongly modified by their potential inversion asymmetry. This is demonstrated in a GaAs quantum well, where we observe that the current-induced nuclear spin polarization at Landau-level filling factor nu=2/3 is completely suppressed when the quantum well is made largely asymmetric with gate voltages. Furthermore, we find that the nuclear spin relaxation rate is also modified by the potential asymmetry. These findings strongly suggest that even a very weak Rashba spin-orbit interaction can play a dominant role in determining the electron-nuclear spin coupling.     

Observation of the synchronization of chaos in mutually injected vertical-cavity surface-emitting semiconductor lasers

Synchronization of chaotic oscillations was observed in mutually injected vertical-cavity surface-emitting lasers (VCSELs) in a low-frequency fluctuation regime. In the experiments, only one of the two polarization modes (x mode) showed synchronized oscillations, and the other polarization components (y mode) were synchronized as a result of the effect of anticorrelated oscillations that is a characteristic feature of VCSELs.     

Exciton spectra in SrS1−xSex mixed crystals

Exciton reflection spectra are investigated at 2 K on single crystals of SrS_1?xSe_x over the whole composition range. All the exciton reflection structures are found to show an amalgamation-type behaviour. From the observed dependence of the reflection peaks on composition and temperature, it is concluded that the exciton spectra of these Sr-chalcogenides are composed of two kinds of the exciton multiplets, the lower one being associated with the X-point band-edge and the higher one with the г-point band edge. It is predicted that these crystals have an indirect band-gap for which phonon-assisted dipole transitions are parity-forbidden.     

Optical spectra of monomeric and polymeric diacetylene crystals in the synchrotron radiation region of 1–20 eV

Polarized reflection spectra have been measured on monomeric and polymeric crystals of bis (p-toluene sulfonate) diacetylene in the synchrotron radiation region of 1–20 eV. Assignments are given for the spectral features observed in both crystals. The one-dimensional Wannier exciton model is proposed to interpret the polymer spectra.