http://ir.lib.ruh.ac.lk/handle/iruor/252 2026-05-13T18:14:37Z 2026-05-13T18:14:37Z Guruge, W.A.H.P. Amarasinghe, N.J. Priyantha, C.H. http://ir.lib.ruh.ac.lk/handle/iruor/278 2024-10-22T07:45:53Z 2003-01-01T00:00:00Z

Application of Rapid Bioassesment Protocol (RBP)II Guruge, W.A.H.P.; Amarasinghe, N.J.; Priyantha, C.H. Biological monitoring is more popular than chemical monitoring due to low cost, effectiveness and it is environmentally friendly. RBP, one of the biological monitoring tool is popular due to its efficiency, low cost and time saving. Present study was carried out to investigate the application of RBP (II) developed by United States Environmental Protection Agency using macro invertebrates, in surface runoff of freshwater bodies of head streams of Nilwala river basin, in Matara district. Four sites located in the upper and middle catchment areas of Nilwala river basin were sampled using artificial substrate samplers and conventional sampler from July 1999 to May 2000. Collected macro invertebrates were identified up to family level. The metric used in RBP (II) and the protocol used in Global Environmental Monitoring System (GEMS)/ Water system, were used to calculate points for each site. Water quality imparity of study sites was classified into four broad categories based on final percentage categories. Site ST 4 was moderately impaired while site ST 2 was non-impaired. Occurrence of the number of ephemeropteran, plecopteran and trichopteran families were higher in sites ST 1 and ST 2. Rapid Bioassesment Protocol (II) was successful in differentiating the water quality of the study sites.

2003-01-01T00:00:00Z Bulugahapitiya, V.P. Renaud, P. http://ir.lib.ruh.ac.lk/handle/iruor/277 2024-10-15T04:11:52Z 2003-01-01T00:00:00Z

Promising system to reduce epimerization Bulugahapitiya, V.P.; Renaud, P. Development of new system which could minimize the epimerization of the a-center at the a-amido radical stage is presented. To study the behaviour of this system, stereoselective synthesis of a-amino compounds via generating a-amido radicals of this system was attempted. The system was prepared by condensation of L-serin methyl ester with methyl phthaladehydate in the presence of triethyl amine. The desired system (tricyclic lactam) was formed in 70% yield and only as the exo isomer. This is the thermodynamically more stable "bowl-like" conformation. The a-alkylated derivative of this tricyclic lactam was prepared via enolate alkylation. The a-alkylated compound was formed in 30% yield and only as the endo isomer. This endo alkylation could be the result of the attack of alkyl group preferentialy from concave face of the "bowl-like" tricyclic lactam. Then methyl esters of tricyclic lactams were directly converted into selenoesters, the radical precursors and radical reactions were carried out via generating a-amido radicals under standared radical reaction conditions. The radical reductions a-unsubstituted system with Bu3SnH and Bu3SnD gave reduced and deuterated products respectively in good yield with higher selectivity favouring exo-isomer while similar reactions with asubstituted system produced reduced and deuterated products also with higher selectivity but favouring endo-isomer. These higher selectivities for the radical reactions could be attributed to the stereoelectronic effect of novel tricyclic system used. The difference of the selectivities between a-substituted and aunsubstituted stage could be rationalized by considering pyramidalization of the tertiary radical center in the transition state of the a-substituted stage.

2003-01-01T00:00:00Z Udugala, Ganehenege M.Y. Wanniarachchi, S. http://ir.lib.ruh.ac.lk/handle/iruor/276 2024-11-08T05:19:57Z 2003-01-01T00:00:00Z

Spectroscopic evidence for Metal-Metal electronic coupling of suspected L5RumCNFen(CN)5 System Udugala, Ganehenege M.Y.; Wanniarachchi, S. Inorganic donor-acceptor complexes containing inter-valence (IT) or metal-to-metal charge transfer bands have received significant attention in the last few decades due to their potential applications to solar energy conversions, photocatalysis and/or electrochromic materials. For this purpose, L5RulllCNFel,(CN) 5 complex (where L = H20, Cl), similar to Prussian blue, has been synthesized. By mixing aqueous solutions of brown-coloured RuCB and light yellow K4 [Fe(CN)6], the colour of the resultant solution suddenly changed to dark green. The electronic spectrum of the solution mixture showed an intense inter-valence (IT) charge transfer absorption with an extinction of 362 M^cm' 1 at approximately 742 nm. The absorption spectrum is totally different from that of the relevant monomers. Dark green solids were isolated after leaving the solution for few hours at room temperature. The solid is very insoluble in many common solvents. The estimated Ru/Fe ratio of the new polymetallic system, using the Job’s method, was found to belli.

2003-01-01T00:00:00Z Samarasekara, P. http://ir.lib.ruh.ac.lk/handle/iruor/274 2024-11-05T09:18:21Z 2003-01-01T00:00:00Z

Oxygen partial pressure dependence of the structure of RF sputtered Strontium Ferrite Samarasekara, P. Strontium hexaferrite (SrFe^Oig) is a prime candidate in the application of magnetic memory devices and microwave devices. The structure of rf sputtered Strontium ferrite strongly depends on the oxygen partial pressure during sputtering according to X-ray diffraction (XRD) measurements. The optimum oxygen partial pressure and the best target composition suitable to synthesize the Strontium hexaferrite have been investigated. A non-magnetic phase of Strontium ferrite (SrFe20 4) was completely crystallized at 10% of oxygen, as the oxygen partial pressure was increased from 0% (pure Ar) to 10%.

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