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Item Ovicidal and Larvicidal Effects of Ricinus communis L. (Euphorbiaceae) Extracts on Phlebotomus duboscqi(European Journal of Medicinal Plants, 2015-11-07) Mong’are, Samuel; Ng’ang’a, Zipporah; Ngumbi, Philip; Ingonga, Johnstone M. ; Ngure, Peter KamauAims: To evaluate the Ovicidal and larvicidal effects of Ricinus communis (Euphorbiaceae) extracts on Phlebotomus duboscqi. Study Design: A comparative experimental design using extracts obtained from the leaf and bark of Ricinus communis plant. Study Site: Kenya Medical Research Institute, Centre for Biotechnology Research and Development (CBRD), Nairobi Kenya from January to July, 2015. Methodology: Aqueous, methanol and ethyl acetate extracts were prepared from Ricinus communis plant. Freshly laid eggs were moistened with 1 ml of each extract separately during the incubation period. Larvae were also fed on larval food mixed with the powdered crude extract and a second group was fed on larval food sprinkled with 5 ml of each extract daily. Results: No significant difference when bark and leaf extracts were compared (P=0.061). 250 μg/ml and 500 μg/ml of extract eroded all the chorionic membranes of the egg shell while egg hatchability was significantly inhibited with only 7%, 9% and 26% of eggs hatching at 500 μg/ml of aqueous, methanol and ethyl acetate extracts respectively (P<0.001). 100% larval mortality noted when at 500 μg/ml methanol extract. The larval period was prolonged to 87 days with the life cycle lasting for 101 days. Conclusion: R. communis extracts have deleterious effects on hatching of eggs, larval and pupal development and adult emergence of P. duboscqi; hence R. communis should be used against sand flies and Leishmania in situ.Item Synthetic Methods for Titanium Dioxide Nanoparticles(IntechOpen, 2018-11-05) Nguu, John; Nyamukamba, P; Okoh, O; Mungondor, Henry; Taziwa, R; Zinya, STitanium dioxide (TiO2) semiconductor nanoparticles are one kind of important and promising photocatalysts in photocatalysis because of their unique optical and electronic properties. Their properties, which are determined by the preparation method, are very crucial in photocatalysis. In this chapter, an overview was carried out on the different methods that are used or have been used to prepare titanium dioxide nanoparticles. There are various methods that can be used to synthesize TiO2 and the most commonly used methods include sol-gel process, chemical vapor deposition (CVD) and hydrothermal method among others. This review will focus on selected preparation methods of titanium dioxide photocatalyst.