Observation of the effects of radially sheared electric fields on the suppression of turbulent vortex structures and the associated transverse loss in GAMMA 10

Vortexlike turbulent structures in hot-ion mode plasmas with several keV are observed in the case with a radially produced weak shear of electric fields E(r). However, a strong E(r) shear formation due to a high ion-confining potential phi(c) production clears up these vortices together with plasma-confinement improvement and disappearance of both drift-wave and turbulencelike Fourier spectral signals. These findings are based on three-time progress in phi(c) in comparison to phi(c) attained 1992-2002. The significant advance of phi(c) is well extended in line with proposed potential-formation physics scalings.     

O-selectivity and utility of phosphorylation mediated by phosphite triester intermediates in the N-unprotected phosphoramidite method

Previously, O-selective phosphorylation on polymer supports in the N-unprotected phosphoramidite method could not be carried out because the amino groups of dA and dC have high reactivity toward tervalent phosphorus(III)-type phosphitylating reagents. In this paper, we developed a new coupling strategy named the "activated phosphite method" in which the phosphitylation is mediated by phosphite triester intermediates 1. Application of 1-hydroxybenzotriazole as the promoter to the solid-phase synthesis resulted in excellent O-selectivity of more than 99.7%. This O-selectivity was explained by the frontier molecular orbital interactions between the reactive intermediates and the nucleophiles such as the amino or hydroxyl groups of nucleosides. Furthermore, longer oligonucleotides were synthesized not only by a manual operation but also by a DNA synthesizer. The utility of our new method was demonstrated by the successful synthesis of a base-labile modified oligodeoxyribonucleotide having 4-N-acetyldeoxycytidine residues. Finally, DNA 20-mers containing dA or dC could be synthesized in good yields by use of a combined reagent of 6-trifluoromethyl-1-hydroxybenzotriazole and benzimidazolium triflate.     

Experimental observation of soft X-rays and suprathermal ions from rare-gas cryogenic solid targets

We investigated characteristics of the soft X-ray emission in the wavelength range of 6–16 nm using various rare-gas cryogenic solid targets irradiated with a nanosecond laser pulse. Suprathermal ions having a maximum velocity of the order of 10⁷ cm/s were detected for three rare-gas targets (Ar, Kr, and Xe). The spatial distributions of the soft X-rays and the suprathermal ions were measured for Xe cryogenic solid targets and found to vary as cos² and cos⁵, respectively, where is the angle to the target normal. By integrating the observed cos² spatial distribution, the conversion efficiency of the soft X-ray emission in the wavelength range from 6 to 16 nm was evaluated to be 0.2%/pulse. PACS 52.38.ph; 52.50.Jm     

Glochidionionosides A-D: megastigmane glucosides from leaves of Glochidion zeylanicum (Gaertn.) A. Juss

Five megastigmane glucosides were isolated from the leaves of Glochidion zeylanicum. One of them was a known compound, blumenol C O-beta-D-glucopyranoside (1), and the structures of the four new compounds, glochidionionosides A-D (2-5), were mainly elucidated by spectroscopic methods, including a modified Mosher's method. The absolute configurations of the six-membered ring of glochidionionoside D (5) were deduced by beta-D-glucopyranosylation-induced shift trends in the (13)C-NMR spectra and confirmed by X-ray analysis as its p-bromobenzoate (5b), and the axis chirality of C-7 was determined to be R.