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Surface plasmon propagation and scattering on structured metal–dielectric interfaces are important tools for field confinement and enhanced atom–field interaction. In this paper, we demonstrate a new type of surface plasmon (SP) lasing that more closely resembles the usual mirror-based laser, in a geometry that comprises a central 50-μm-long flat region between two metal hole arrays that serve as reflecting mirrors. The lasing mode shows features of double-slit interference modulated by the radiation pattern of, and selection rules set by, the scattering of SPs on the 2D hole arrays. Our results also provide information on the group velocity of surface plasmons and their scattering and penetration in hole arrays.

2-(2-Deoxy-D-erythro-pent-1-enofuranosyl)pyridine and its methyl analogues have been prepared by treatment of the corresponding 2',3'-O-isopropylidene-D-ribofuranosyl derivatives with several bases such as sodium amide, tert.BuOK, EtONa, lithium tetramethylpiperidide (LTMP) and phenyl lithium (PhLi). PhLi and tert.BuOK gave the best results. The products thus obtained showed cytostatic activity against human tumor cell lines, in particular MT-4, a human T-lymphocyte cell line. No antiviral activity was noted at subtoxic concentrations.

During the course of our study on the synthesis of new pyridine-C-nucleosides with potential anti-viral and/or anti-tumourai properties, the preparation of 2-carbamoylmethyl-6-β-D-ribofuranosylpyridine 1, by means of a lithiation reaction on 2-(2,3-0-isopropylidene-β D-nbofuranosyl)-6-methylpyridine 2, was investigated (Scheme I). The latter compound was prepared by treating 6-methyl- toluenesulphonic acid. 2-(& D-ribofuranosyl)pyridine 1 2 with 2.2-dimethoxypropane in the presence of p-