Volume 06 - 2011

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    Producing inter-specific hybrids between Brassica juncea (L.) Czern & Coss and B. oleracea (L.) to synthesize trigenomic (abc) Brassica
    (University of Kelaniya, 2011) Weerakoon, S.R.
    Polyploidy is recognized as a major mechanism in plant evolution. Polyploid crops often have wider adaptation, better quality and higher yielding capacity than their diploid counterparts. Although many successful natural and man-made hexaploid crops are existing, hexaploid Brassica are still not available. So far, relatively a limited work has been conducted to synthesize hexaploid Brassica with A, B and C genomes, which will provide a very good potential to create new crops for domestication. An investigation was conducted to evaluate the possibility of synthesizing trigenomic (AABBCC) hexaploid Brassica by crossing Brassica juncea (L.) Czern & Coss and B. oleracea (L.). Five genotypes of B. juncea (AC 0747, 0790, 1099, 2180 and 7700) and five genotypes of B. oleracea (Chinese Broccoli, Broccoli-var. Shogun, Cauliflower-var. Snowball and var., Phenomenon Early and Cabbage-var. Sweet Eureka) were selected for the study. Hand pollination was done by emasculating buds of one species and pollination using another species in both directions. Success of pod formation of the crosses of B. juncea (♀) x B. oleracea (♂) was 25%. Totally 893 putative hybrid seeds were harvested. Although 9% pod formation was observed in reciprocal crosses, no seeds were developed. Evaluation of 80 putative hybrids by molecular markers and agro-morphological characterization confirmed four true hybrids resulting crosses between AC 0747 x Chinese Broccoli, AC 0790 x Chinese Broccoli and AC 2180 x Broccoli-var. Shogun. The present investigation confirms that hybridization of tetraploid B. juncea (4x, AABB) with diploid B. oleracea (2x, CC) is a potential approach to produce hexaploid Brassica (6x, AABBCC) genotypes.
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    Stress induced anisotropy and applied field dependence of second order perturbed energy of thick ferromagnetic films
    (University of Kelaniya, 2011) Samarasekara, P.
    The energy of thick ferromagnetic films up to 10000 layers has been explained in this report using classical Heisenberg Hamiltonian with second order perturbation. Especially the effect of applied magnetic field and stress on energy of sc(001) ferromagnetic thick films has been investigated. Under the influence of perpendicular magnetic field given by  out H = 6, the sc(001) ferromagnetic film with 10000 layers can be easily oriented in 0.5 radians direction. The easy direction of sc(001) ferromagnetic film with 10000 layers was found to be 0.6 radians when the in-plane magnetic field of  in H = 4.2 is applied. Because the easy axis oriented magnetic films are useful in magnetic memory devices and monolithic microwave integrated circuits (MMIC), the determination of easy direction is important. If the stress given by  s K = 2.6 is applied in perpendicular direction to the film plane, the film can be easily oriented in direction of 3 radians. Energy under influence of perpendicular magnetic field is larger than the energy under the influence of in-plane magnetic field. After introducing the second order perturbation to the Heisenberg Hamiltonian, even some small variations of energy could be investigated as indicated in the graphs in this manuscript.
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    Synthesis of Chitosan Stabilized Silver Nanoparticles using Gamma Ray Irradiation and Characterization
    (University of Kelaniya, 2011) Hettiarachchi, M.A.; Wickramarachchi, P.A.S.R.
    Chitosan stabilized silver nanoparticles (AgNPs) were synthesized using gamma ray irradiation. Four different sample solutions were prepared [1 mM AgNO3 in 0.1% (w/v) chitosan, 1 mM AgNO3 in 0.5% (w/v) chitosan, 2 mM AgNO3 in 0.1% (w/v) chitosan 2 mM AgNO3 in 0.5% (w/v) chitosan] with controls maintaining dose of radiation at 20±2 kGy. The formation of AgNPs were determined by the appearance of the characteristic colour of the AgNPs, using the surface plasmon resonance band (SPR) at 400-432 nm range and the N-H band of the FT-IR spectrum. Stability of the maximum absorption wave lengths of the samples was monitored for three months by UV-visible spectroscopy. The particle size distribution of the stabilized sample, showed a wide distribution of 28-1106 nm. The sample, 2 mM AgNO3 in 0.5% (w/v) chitosan was stable for three months. FT-IR spectroscopic analysis revealed a shifting of N-H stretching vibration band from 3367-3228 cm-1 with the introduction of nanoparticles.
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    Automatic Segmentation of Separately Pronounced Sinhala Words into Syllables
    (University of Kelaniya, 2011) Priyadarshani, P.G.N.; Dias, N.G.J.
    Aligned corpora are widely used in various speech applications like automatic speech recognition, speech synthesis, as well as prosodic and phonetic research. The segmentation into syllables can be done manually or automatically. But it consumes significantly more time for a fully manual phonetic segmentation and practically it is a complicated task because in many cases it requires a large aligned speech corpus. If the manual syllabification is done by a group of individuals then the consistency is decreased because the analysis variations of the individuals. Consequently, there is a dire need for automatic syllabification and it is important because Sinhala language is syllable centric in nature. A method for syllabification of acoustic signals of separately pronounced Sinhala words has been given. Detecting the syllable boundaries was achieved by two main phases and those phases have been described with examples. Keywords:
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    Efficacy of essential oils from bark and leaf of Cinnamomum zeylanicum on root knot nematode, Meloidogyne graminicola in rice seedlings and young rice plants
    (Journal of Science of the University of Kelaniya, Sri Lanka, 2011) Amarasinghe, L.D.; Wijesinghe, W.K.A.G.A.; Jayawardhane, B.K.
    The present study was conducted to evaluate the efficacy of essential oils from leaf and bark of cinnamon, Cinnamomum zeylanicum in controlling Meloidogyne graminicola and their effects on rice seedlings and young rice plants. This study was done; to determine the LC50 of essential oils of the extracts of cinnamon leaf and bark to kill 50% of second stage juveniles (J2) of Meloidogyne graminicola in rice root galls; to determine the efficacy of essential oils of cinnamon; in controlling J2 in rice seedlings and young rice plants; and on the growth of rice plants. Cinnamon bark oil sample used in the current study contained about 72% cinnamaldehyde and the leaf sample contained about 86% eugenol. LC50 for cinnamon leaf oil and cinnamon bark oil for killing 50% of juveniles of M. graminicola in rice root galls after three days of the treatment was 0.326 ppm and 0.454 ppm respectively. Number of galls in the root system of nematode infested rice seedlings was significantly reduced when they were treated with 0.9 ppm of cinnamon leaf oil and bark oil compared to untreated controls. However, the nematicidal activity between the cinnamon leaf oil and bark oil was not significantly different. The root gall index of infested young rice plants was significantly lowered when they were treated with either cinnamon leaf oil or bark oil compared to untreated controls. It was revealed that the mean plant height and the mean number of roots of essential oil treated plants were positively correlated with the number of root galls whereas, the number of dead plants and the mean percentage chlorosis were negatively correlated. Nevertheless, the mean root length did not show any significant correlation with number of root galls. This study concludes that essential oils of cinnamon leaf which contained 86% eugenol and bark which contained 72% cinnamaldehyde are similarly effective in suppression of M. graminicola in rice seedlings and young rice plants. According to the rates of application of essential oils of cinnamon leaf and bark, none of them have significant negative effect on the plant growth. Hence, they can be used as an alternative nematicide against the rice root knot nematode, M. graminicola in early stage of rice plants.
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    An integrated approach to the management of rice root knot nematode, Meloidogyne graminicolain Sri Lanka
    (Journal of Science of the University of Kelaniya, Sri Lanka, 2011) Amarasinghe, L.D.
    This study was carried out to design tools for integrated management of root knot nematode, Meloidogyne graminicola, in rice in Sri Lanka. Rice varieties namely, At5, At353, Bg304, Bg305, Bg359, Bg450, Bg94-1, Bg379-2, Ld355 and Ld356 were tested for their reactions against M. graminicola. Effect of poultry manure, cow-dung and paddy husk with or without cinnamon-leaf oil in reducing M. graminicola was studied. It was revealed that rice varieties At5, At353, Bg304, Bg305, Bg450, Bg379-2, and Ld356 were tolerant to M. graminicola as compared to Bg94-1 which is highly susceptible with high rate of reproduction. Plants treated with poultry manure had significantly low nematode population. Plants grown in poultry manure enriched soil had lower yellow and dead leaves as compared to other plants. Addition of cinnamon-leaf oil improved the nematode control. This study concludes that rice varieties namely At353, Ld356, Bg304, At5, Bg305, Bg450 and Bg379-2 can be used for fields that are prone to M. graminicola infestation while poultry manure can be utilized at least occasionally as a nematicide cum fertilizer to reduce nematode infestation level in rice plants and to improve soil fertility.
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    Investigating the thermal efficiency of commercially available thermo-foils in Sri Lanka
    (Journal of Science of the University of Kelaniya Sri Lanka, 2011) Maduranga, A.D.; Sumathipala, H.H.; Jayatissa, N.W.K.
    The thermo-foil is an insulation material which can be used to insulate roofs of residential buildings which causes less energy to accomplish a comfortable temperature inside the building. It?s becoming popular in Sri Lankan building construction sector. In this research, an investigation of the efficiency of the thermo-foils is done for commonly used brands. The important thermal properties are analyzed for thermo-foils with a thickness of 3mm, 5mm and 8mm and it is tested using a miniature building model for the further evaluation of the efficiency. It was observed that the aluminium layer of the thermo-foil could reflect most of the radiation back and the polyethylene foam layer could keep a temperature gradient of a few degrees. A temperature drop of 1.6 to 2.8 degrees was noted. The results obtained were discussed with an analysis of the thermal insulation properties. A heat transfer model for a residential building was also proposed.