Stark beats of Lyman-α emission of foil-excited hydrogen atom

The Stark beats of Lyman-α emission due ton=1 ? 2 transition of hydrogen atom have been studied by the beam-foil method. After passage through a thin carbon foil, the static electric field of 500 V/cm was applied to the beam in the direction either parallel to or anti-parallel to the the beam velocity. The linearly polarized emission was measured by using a toroidal mirror at a Brewster's angle reflection. When the direction of the applied electric field is reversed, an appreciable phase shift was observed. The analysis of the data leads to the complete determination of the density matrix of the H(n=2) atoms at the time of their production.     

New design of a radio-frequency plasma torch

A numerical model has been developed for predicting the two-dimensional flow and temperature fields in a radio-frequency (rf) plasma torch. The method employed here is based on Boulos' model with the exception of the boundary conditions for the electric and magnetic field equations. Calculations have been made for the confirmation of a new sample injection method, which is capable of completely evaporating refractory materials at high feeding rates without interfering with the stability of the plasma. In the newly designed torch, the reagent is radially injected into the hottest part of the plasma through quartz capillary tubes set symmetrically between an inductor coil. Experimental investigations have also been performed for verifying the proper function of the design. These results provide evidence that our radial injection method developed here is more effective in practical processing than the conventional axial injection methods.     

Enantioselective total synthesis of (-)-strychnine using the catalytic asymmetric Michael reaction and tandem cyclization

The enantioselective total synthesis of (-)-strychnine was accomplished through the use of the highly practical catalytic asymmetric Michael reaction (0.1 mol % of (R)-ALB, more than kilogram scale, without chromatography, 91% yield and >99% ee) as well as a tandem cyclization that simultaneously constructed B- and D-rings (>77% yield). Moreover, newly developed reaction conditions for thionium ion cyclization, NaBH3CN reduction of the imine moiety in the presence of Lewis acid to prevent ring opening reaction, and chemoselective reduction of the thioether (desulfurization) in the presence of exocyclic olefin were pivotal to complete the synthesis. The described chemistry paves the way for the synthesis of more advanced Strychnos alkaloids.     

Synthesis of Latia luciferin benzoate analogues and their bioluminescent activity

The bioluminescent system of the univalve shell Latia neritoides exhibits a luciferin-luciferase reaction. We study the enol formate structure of Latia luciferin, which is expected to be important for luminescent activity. The Latia luciferin analogues with an enol substituted benzoate moiety were synthesized and their bioluminescent activity was measured. The Latia luciferin benzoate analogues delay emission for natural luciferin in bioluminescence, indicating that the Latia bioluminescent activity can be controlled by the design of the enol ester.     

Isoflavonoids from Belamcanda chinensis

Four new isoflavonoids were isolated along with six known related compounds from a rhizome of Belamcanda chinensis (Iridaceae), and their structures were characterized as 6'-O-p-hydroxybenzoyliridin, 6'-O-vanilloyliridin, 5,6,7,3'-tetrahydroxy-4'-methoxyisoflavone and 2,3-dihydroirigenin, respectively, on the basis of spectroscopic methods and chemical evidence.