Volume 09 - 2014
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/13906
Browse
Item Cobal Ferrite Films as Described by Third Order Perturbed Heisenberg Hamiltonian(University of Kelaniya, 2014) Samarasekara, P.Magnetic properties of thick films of Cobalt ferrite have been investigated using third order perturbed modified Heisenberg Hamiltonian at different values of second and fourth order magnetic anisotropy. Thick films with up to 10,000 layers have been employed for this investigation. The magnetic energy versus number of layers, second and fourth order anisotropy have been plotted in order to find the magnetically easy and hard directions of cobalt ferrite films. Energy has minimum and maximum values at certain values of second and fourth order anisotropy values, indicating that that there are magnetically easy and hard directions. Energy shows the same type of variations with number of layers in the film. For the values considered in this manuscript, the easy direction of magnetization was found to be 1530 with the normal line drawn to the film surface. However, the easy axis direction depends on the values of parameters used in simulation. Determination of easy directions of magnetic films is important in applications of magnetic memory devices.Item Development of Suitable Propagation Systems for Tephrosia spp. in Sri Lanka(University of Kelaniya, 2014) Priyadarshan, A.I.S.; Senanayake, S.P.; Jayatilleke, M.P.; Rajapakse, S.Genus Tephrosia (Fabaceae) commonly known as ‘Pila’ in Sri Lanka. Some Tephrosia spp. are used in many traditional therapeutic preparations in Sri Lanka and also in other countries. Increased use of Tephrosia in traditional therapeutic systems has developed a great demand for these species. Thus production of planting materials for commercial cultivation has become a timely requirement. Therefore, this research was conducted to determine suitable propagation systems for four selected Tephrosia spp.; T. purpurea, T. villosa, T. noctiflora and T. pumila. Even though seeds of Tephrosia spp. showed high viability, lower germination percentage was observed on wet filter paper as well as in six different potting media [M0 (Coir: dust: Sand; 1:1:1), M1 (Coir dust: Sand: Top soil; 1:1:1), M2 (Coir dust: Sand: Top soil: Compost; 1:1:1:1), M3 (Coir dust: Sand: Top soil: Compost: Cow dung; 1:1:1:1:1), M4 (Coir dust: Sand: Compost; 1:1:1), M5 (Coir dust: Sand: Top soil: Cow dung; 1:1:1:1)] during a period of one week. Water impermeability of seed coats was identified as the main reason for the seed dormancy in Tephrosia spp. and soaking seeds in Con. H2SO4: H2O; 3:1 for 25 minutes and rubbing seeds on sandpaper for 2 minutes were determined as suitable dormancy breaking methods. Variation was observed in the growth performance of Tephrosia spp. in six different potting media. Growth performances of seedlings of Tephrosia spp. in hydroponic solution and soil medium were observed and soil medium was selected as the most suitable medium for the growth of Tephrosia species based on their growth performances.Item Intraspecific Variation of Flueggea leucopyrus Willd. Grown in Sri Lanka and Establishing a Suitable Propagation System(University of Kelaniya, 2014) Priyadarshan, A.I.S.; Senanayake, S.P.; Jayatilleke, M.P.; Rajapakse, S.Flueggea leucopyrus belongs to family Phyllanthaceae, commonly known as ‘Katupila’or ‘Heen katupila’ and has become increasingly popular as an ingredient in several traditional therapeutic systems in Sri Lanka as well as in other Asian countries. A questionnaire survey was carried out using a hundred population sample to determine the awareness of the distribution and therapeutic uses of F. leucopyrus in Sri Lanka as a preliminary survey. The aims of the present study were to interpret the phenetic variation and determine the variation of phenolic composition in leaf extracts of F. leucopyrus in different climatic zones in Sri Lanka and to develop a suitable propagation system for F. leucopyrus. Eleven floral and vegetative characters of F. leucopyrus were observed and cluster analysis was carried out to infer phenetic relationships among populations collected from localities, Colombo, Kurunegala, Puttalam and Hambanthota, .representing different climatic zones. Medicinal value of most of plants lies in phytochemicals such as phenolics, flavonoids and anthocyanidins. Thus, leaf samples were extracted into ether, and ether extracts were used to isolate phenolic compounds using 2-Dimensional paper chromatography in solvent systems, butanol: acetic acid: water; 6:7:3 and sodium formate: formic acid: water; 10:1:200. Colors of the spots were observed under UV (366nm), and Rf values were calculated. Intra specific variations were observed in the distribution of phenolics in leaves and phenetic characters of F. leucopyrus with respect to their habitats in different climatic zones. Due to low seed production in F. leucopyrus, stem cuttings (Semi-hardwood, hardwood and softwood) in three different potting media were used to evaluate the successfulness in propagation. Semi hardwood and hardwood cuttings of F. leucopyrus were well established within a period of one week in sand potting medium while softwood cutting has not responded in any of the media during the period. Medium with only coir dust was also not successful in establishing the cuttings.Item Microwave Assisted Dissolution of Sri Lankan Ilmenite: Extraction and Leaching Kinetics of Titanium and Iron Metals(University of Kelaniya, 2014) Premaratne, W.A.P.J.; Rowson, N.A.The kinetics of the leaching of titanium and iron from Sri Lankan ilmenite in a sulphuric acid medium heated by microwave energy is studied. The effects of the concentration of sulphuric acid, reaction temperature and particle size on the kinetics of dissolution of ilmenite are investigated. Results show that both the acid concentration and the temperature have significant effects on the rate of dissolutions of titanium and iron from ilmenite. The dissolution of both titanium and iron from ilmenite was controlled by a chemical reaction on the surface of ilmenite particles. Maximum extractions of 74.2 (±1.1) % of titanium and 71.3 (±0.8) % of iron from the ilmenite ore were achieved using a microwave leaching system of 600 W, 2.45 GHz. Experimental results further showed that the apparent activation energies for the dissolution of titanium and iron were 137 kJ mol-1 and 117.1 kJ mol-1 respectively. Therefore, microwave energy has a potential for the speedy and efficient leaching of ilmenite and in a commercial context it can be used as a more economical and environmental friendly process. The results of the mineralogical and chemical analysis studies for the ilmenite ore indicated that both ilmenite (FeTiO3) and pseudorutile (Fe2Ti3O9) minerals were present with a grade of 37.9% titanium.