Evaluation of Hexane Extract of Tuber of Root of Cyperus rotundus Linn (Cyperaceae) for Repellency against Mosquito Vectors

Hexane extract of tuber of plant Cyperus rotundus (Cyperaceae) was screened under laboratory conditions for repellent activity against mosquito vector Anopheles culicifacies Giles species A (Diptera: Culicidae), Anopheles stephensi Liston (Diptera: Culicidae), and Culex quinquefasciatus Say (Diptera: Culicidae). The Cyperus rotundus tuber extract was used to determine their effect on mosquito vector, and comparison with the DEET (NN Diethyl 1-3 methyl Benzamide, formerly known as diethyl 1-m-toluamide). The tuber extracts showed more effective at all the dose. Result obtained from the laboratory experiment showed that the tuber extracts are more effective for repellency of allthe mosquito vector even at low dose. Clear dose response relationships were established with the highest dose of 10% tuber extract evoking 100% repellency. Percent protection obtained against An. culicifacies Giles species A 100% repellency in 4 hours, 6 hours, An. stephensi 100% repellency in 6 hours and Cx. quinquefasciatus was 100% repellency in 6 hours at the 10% concentration. Against DEET- 2.5% An. culicifacies A 100% repellency in 1 hour, 2 hours, 6 hours, An. stephensi have shown 100% repellency in 6 hours, and Culex quinquefasciatus have shown 100% repellency in 1 hour, 2 hours, 6 hours. The consolidated data of the repellency observed in different species is given and it is evident that the over all repellency rates varied between 80 and 100% for different repellents concentrations (2.5%, 5%, and 10%). The extract can be applied as an effective personal protective measure against mosquito bites

Ethnobotanical Studies on Orchids of Niyamgiri Hill Ranges, Orissa, India

Niyamgiri hills, the abode of the primitive Dongria Kandha tribe in southwest Orissa, is a unique forest ecosystem harbouring a rich flora and vast natural resources. The present ethnobotanical study concerns some 20 species of orchids including 16 epiphytes and 4 terrestrials that are used by the Dongarias of the Niyamgiri hill range to treat 33 kinds of diseases. This paper also discusses some of the threats to the orchids of this hill region, as well as some very serious problems regarding their conservation

Growth of Oriented Au Nanostructures: Role of Oxide at the Interface

We report on the formation of oriented gold nano structures on Si(100) substrate by annealing procedures in low vacuum (\approx10-2 mbar) and at high temperature (\approx 975^{\circ} C). Various thicknesses of gold films have been deposited with SiOx (using high vacuum thermal evaporation) and without SiOx (using molecular beam epitaxy) at the interface on Si(100). Electron microscopy measurements were performed to determine the morphology, orientation of the structures and the nature of oxide layer. Interfacial oxide layer, low vacuum and high temperature annealing conditions are found to be necessary to grow oriented gold structures. These gold structures can be transferred by simple scratching method.Comment: 13 pages, 3 figures, Accepted in J. Appl. Phy

Evidence of 1D behaviour of He4^4 confined within carbon-nanotube bundles

We present the first low-temperature thermodynamic investigation of the controlled physisorption of He$^{4}$ gas in carbon single-wall nanotube (SWNT) samples. The vibrational specific heat measured between 100 mK and 6 K demonstrates an extreme sensitivity to outgassing conditions. For bundles with a few number of NTs the extra contribution to the specific heat, C$_{ads}$, originating from adsorbed He$^{4}$ at very low density displays 1D behavior, typical for He atoms localized within linear channels as grooves and interstitials, for the first time evidenced. For larger bundles, C$_{ads}$ recovers the 2D behaviour akin to the case of He$^{4}$ films on planar substrates (grafoil).Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let

Effect of silver nanoparticles on growth of eukaryotic green algae

Silver nanoparticles, endowed with powerful antimicrobial property, are the most widely used nanomaterial in consumer products, with associated risk of their easy access to environment and freshwater ecosystems by surface runoff. Although toxic effects of nanosilver on bacterial, fungal and mammalian cells have been documented, its impact on algal growth remains unknown. Pithophora oedogonia and Chara vulgaris are predominant members of photosynthetic eukaryotic algae, which form major component of global aquatic ecosystem. Here we report for the first time that nanosilver has significant adverse effects on growth and morphology of these filamentous green algae in a dose-dependent manner. Exposure of algal thalli to increasing concentrations of silver nanoparticles resulted in progressive depletion in algal chlorophyll content, chromosome instability and mitotic disturbance, associated with morphological malformations in algal filaments. SEM micrographs revealed dramatic alterations in cell wall in nanoparticle-treated algae, characterized with cell wall rupture and degradation in Pithophora. Although these observations underscore severe deleterious effects of nanosilver on aquatic environment, the information can also be exploited as a bioengineering strategy to control unwanted and persistent growth of noxious algal weeds that clog the municipal water supply and water channels and produce fouling of water bodies