Abstract:We describe a new class of DNA-like oligomers made exclusively of nonnatural, stable C-nucleosides. The nucleosides comprise four types of nonnatural bases attached to a deoxyribose through an acetylene bond with the -configuration. The artificial DNA forms right-handed duplexes and triplexes with the complementary artificial DNA. The hybridization occurs spontaneously and sequence-selectively, and the resulting duplexes have thermal stabilities very close to those of natural duplexes. The artificial DNA might be applied to a future extracellular genetic system with information storage and amplifiable abilities.

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The characteristics of the ion beams produced in a plasma focus device were studied. In the experiment, a Mather-type plasma focus device was used which was prefilled with H 2 at 2.3 Torr. Ion species and their energy spectra were evaluated with a Thomson parabola spectrometer. The particle pinhole image was obtained with an aluminum filtered particle pinhole camera. The ion current density was measured with a biased ion collector. From the measurement, the proton beam energy was found to be distributed from 0.15 MeV to 2 MeV. The particle pinhole image of the proton beam with an energy of more than 1 MeV has spotlike patterns. The ion current density of 2400 A/cm 2 with a pulse width of 50 ns was observed on the axis at z = 260 mm from the top of the anode. The peak power brightness of the proton beams was evaluated to be 18 GW/cm 2 /sr/keV, and the total power brightness was evaluated to be 20 TW/cm 2 /sr.

A triple hydrogen-bonding module based on 6-alkynyl-2-amino-3H-pyrimidin-4-one was developed such as for selfdimerization and for nucleobase recognition processes. The strength of the module for the self-dimerization was determined by NMR and fluorimetric analyses in chloroform (ΔG 298 = -22 to -23 kJ/mol). DFT calculations and X-ray structure analysis showed that the self-dimerization consists of the three-point hydrogen-bonding including two kinds of

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