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Using seven species of bacteria as test organisms, crude extracts of about forty two species of seaweeds collected from Saurashtra coast were screened for their antibacterial activity. Some of the extracts showed activity against gram positive bacteria, while none were active against gram negative bacteria. The antibacterial activity of seaweed extracts was well preserved even after extraction at 50°-55 °C. Seaweed extracts of selected seaweeds showed antibacterial activity throughout the year with a definite peak of activity between October and January.

Abstract.A study carried out on the occurrence of post midnight spread-F events at a low-latitude station, Waltair (17.7 • N, 83.3 • E), India revealed that its occurrence is maximum in the summer solstice months of the low solar activity period and decreases with an increase in the sunspot activity. The F-region virtual height variations show that 80% of these spread-F cases are associated with an increase in the Fregion altitude. It is suggested with the support of the night airglow 6300 A zenith intensity data obtained with co-located ground-based night airglow photometer and electron temperature data from the Indian SROSS C2 satellite that the seasonal variation of the occurrence and probable onset times of the post midnight spread-F depend on the characteristics of the highly variable semipermanent equatorial Midnight Temperature Maximum (MTM).