Beta-replacement reaction of serine-O-carbonate derivatives with thiols catalyzed by a pyridoxal model having an ionophore side-chain

Serine-O-carbonate derivatives, including peptides having a serine-O-carbonate residue at the N-terminal position, are catalytically transformed into S-substituted cysteine derivatives employing the pyridoxal model having an ionophore function in the presence of Li+; this is the first artificial model mimicking cystathionine Beta-synthase.     

Formation of the first monoanion and dianion of stannole

The first syntheses of mono- and dianions of stannole were accomplished by transmetallation or reduction of the novel bi(1,1-stannole).     

Luminescence and conduction charge in thin-film electroluminescent devices

The luminescence and conduction currents of a doubly-insulated thin-film electroluminescent device were studied under various excitation conditions. The conduction current waveform was calculated numerically from the luminescence waveform. It was composed of two components: a fast transient component j_fc, which rises and decays rapidly when a pulse is applied, and a dc-like component j_dc, which maintains a constant level during the duration of pulse. The ratio of these components varied considerably with applied voltage. Both the slow response of luminescence to voltage change and the change in j_fc when the excitation conditions were changed from repetitive pulses to a single pulse suggest an accumulation of charges inside the electroluminescence layer. This accumulation causes a space charge effect which explains the dominance of j_fc in the high-brightness region. The fact that luminescence intensity in this region is not related to the amplitude of individual pulses, but rather to the average amplitude of the pulse train also indicates that the space-charge-induced internal electric field is the main factor in accelerating the carriers which excite the luminescence centers. It was found that the two conduction current components showed similar characteristics in singly-insulated devices.     

Regio-specific total synthesis of (±)-2-hydroxyaklavinone

The tricyclic quinone 8 was successfully synthesized from naphthazalin, and the total synthesis of (±)-2-hydroxyaklavinone via 8 was accomplished in an overall yield of about 18% through the regio-controlled route.     

Kolmogorov spectrum of superfluid turbulence: numerical analysis of the Gross-Pitaevskii equation with a small-scale dissipation

The energy spectrum of superfluid turbulence is studied numerically by solving the Gross-Pitaevskii equation. We introduce the dissipation term which works only in the scale smaller than the healing length to remove short wavelength excitations which may hinder the cascade process of quantized vortices in the inertial range. The obtained energy spectrum is consistent with the Kolmogorov law.