. Can. J. Chem. 70, 1015 (1992). The synthesis of diaceperylene (I) from 5,6-dilithioacenaphthene via nickel or cobalt catalysed couplings proceeded in better yield than a multistep synthesis involving formation of 5,5'-diacenaphthene first. Dehydrogenation of 1 to dicyclopenta[l,2,3-cd: 11,2',3'-lmlperylene (2) proved a better route than coupling of 5,6-disubstituted acenaphthylene derivatives. Ultraviolet, proton, and carbon nuclear magnetic resonance spectra and electrode reduction potential data of 1 and 2 are discussed with respect to molecular mechanics calculations of strain in these and related bridged naphthalenes. Both 1 and 2 were found to be weakly mutagenic in an Ames microsome test, in contrast to cyclopenta[cd]pyrene. [Traduit par la redaction]

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Forty weaned male guinea pigs (Cavia porcellus) of 152.6 +/- 7.96 g mean body weight were divided into four equal groups and fed a common basal diet comprised of 25% ground cowpea (Vigna unguiculata) hay, 30% ground maize (Zea mays) grain, 22% ground gram (Cicer arietinum) grain, 9.5% deoiled rice (Oryza sativa) bran, 6% soybean (Glycine max) meal, 6% fish meal, 1.5% mineral mixture (without Se), and ascorbic acid at 200 mg/kg to meet their nutrient requirements along with 0, 0.1, 0.2, and 0.3 ppm of organic selenium (Se) in groups I, II, III, and IV, respectively. Experimental feeding lasted for a period of 10 weeks, during which, daily feed intake and weekly body weights were recorded. Intake and digestibility of dry matter, organic matter, ether extract, crude fiber, and nitrogen-free extract as well as uptake of calcium and phosphorus were similar (P > 0.05) among the four groups. Feed:gain ratio was also similar (P > 0.05) in the four groups. However, digestibility of crude protein was significantly (P < 0.001) higher in group II supplemented with 0.1 ppm organic Se as compared to other three group. Intake and absorption of Se was significantly (P < 0.001) higher in all the Se supplemented groups as compared to control group. Average daily gain (ADG) was significantly (P < 0.05) higher in group II (3.16 g/day) and III (3.38 g/day) as compared to group I (2.88 g/day). However, ADG in group IV (supplemented 0.3 ppm organic Se) was significantly (P < 0.05) lower (2.83 g/day) than group II and III, but comparable (P > 0.05) to group I. Findings of the present experiment suggests that Se requirements of guinea pigs are > or =0.2 ppm, as supplementation of 0.1 ppm organic Se in the diet (having 0.1 ppm Se) not only enhanced their growth rate but also improved the protein utilization.