IPRC - 2015
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/156
Browse
2 results
Search Results
Item Selenium in rice consumed by Sri Lankans(Faculty of Graduate Studies, University of Kelaniya, 2015) Prasanna, E.G.J.; Wickramasingha, E.A.D.N.N.; de Silva, D.S.M.; Wimalasena, S.Selenium is an essential trace element found in the selenoproteins and as a component of enzymes such as glutathione peroxidase that could quench free radicals by acting as antioxidants and prevent free radical induced degenerative diseases such as diabetics, Alzheimer, rheumatism and the deficiency of selenium could result in iodine deficiency resulting goiter. It also proved that selenium is toxic in high concentrations resulting in damages to the nervous system and even some forms of cancer. Unlike most elements the essentiality and toxicity of selenium is shown in a narrow range the respective values being 40 μg day-1 and 400 μg day-1. Studies on selenium content in food have been reported from other countries but studies carried out in food consumed by Sri Lankans is rare. Hence, the objective of the present study is to determine the selenium content in different varieties of rice consumed by Sri Lankans. Parboiled rice is commonly consumed in Sri Lanka. Studies have not been carried out in Sri Lanka or any other country on the effect of parboiling on the selenium content. Hence, this study was extended to deduce the effect of parboiling on the selenium content in rice. Selenium content in fourteen varieties of rice namely Bg 250, Bg 352, Bg 358, Bg 359, Bg 360, Bg 379, Bg 450, Bg 094, Bw 361, Bw 363, Bw 364, Ld 408, At 306 and At 362 obtained from the Rice Research Institute, Batalagoda and subjected to acid digestion. Selenium contents of the samples were determined using Hydride Generation Atomic Absorption Spectrometric method. Experiments were carried out in triplicate. The selenium content (μg kg-1) in the rice samples analyzed ranged from 24.5 (At 362) - 40.5 (Bg 094). The selenium content in parboiled rice was analyzed by parboiling the above raw rice samples at home. The results of the present study showed that the selenium content (μg kg-1) in the grains from par boiled rice varied from 29.0 (Bw 361) to 42.0 (Bg 352). This study reveals that parboiling increased the selenium content in rice although a direct relation could not be obtained between the selenium content in raw rice and that in the parboiled rice.Item Growth of CdS and CdTe thin film semiconductors and fabrication of CdS/CdTe solar cells(Faculty of Graduate Studies, University of Kelaniya, 2015) Kumarasinghe, K.D.M.S.P.K.; de Silva, D.S.M.; Pathiratne, K.A.S.; Dharmadasa, I.M.; Salim, H.I.; Abdul-Manaf, N.A.; Ravirajan, P.; Balashangar, K.Thin films of CdS and CdTe semiconductor materials were electrodeposited onto glass/fluorine doped tin oxide conducting glass surfaces using a potentiostat/galvanostat equipped with a three electrode cell. Aqueous electrolytic bath containing CdCl2 and (NH4)2S2O3 was used for the electrodeposition of CdS thin films. CdTe thin films were electrodeposited onto glass/FTO/CdS substrates from aqueous solution having high concentrations of CdSO4 and low concentrations of TeO2 and CdCl2. The glass/FTO/CdS/CdTe/Cu-Au solar cell devices were prepared by thermal evaporation of Cu and Au on CdTe surface. CdS films grown were annealed at ~400 °C for 15 minutes in air and photo-electro chemical (PEC) cell measurements were performed to identify the electrical conductivity type. Both as-deposited and annealed CdS layers were identified as n-type in electrical conduction. CdS thin films were shown enhanced PEC responses upon heat treatment. The respective band gap values for as-deposited and heat treated CdS were 2.35±0.05 eV and 2.40±0.05 eV which were close to the band gap of bulk CdS. XRD analysis of as-deposited CdS layers revealed the presence of hexagonal CdS materials with the major peak arising from (002) plane. Following the CdTe deposition on glass/FTO/CdS substrate, the surface of CdTe layers were coated with a 0.1% CdCl2 solution and structures were annealed at ~400°C for 10 minutes in air. Band gaps for CdTe layers were found to be 1.45±0.02 eV for both as-deposited and annealed samples which exhibited the band gap of bulk CdTe. There was a little improvement in cubic (220) and (311) peaks of XRD spectra of annealed CdTe layers compared to the as-deposited material, but annealing exhibited a small reduction of cubic phase preferential orientation (111). SEM images showed that CdS and CdTe layers were fairly uniform. The fabricated solar cell devices showed the efficiency of 2.1% with Voc ~330 mV, Jsc~20 mA cm-2 and FF~33% under the illumination of air mass (AM) 1.5 conditions (100 mW/cm2, 1 Sun).