Journal of Science
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Item 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.Item 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.Item Simulation of nitrate leaching in Yala season in Batticaloa - A modeling approach(University of Kelaniya, 2010) Bawatharani, T.; Mowjood, M.I.M.; Dayawansa, N.D.K.; Kumaragamage, D.The leaching behaviour of NO3--N was evaluated through field experiments with those predicted by LEACHM-N, a uni-dimensional, water flow, solute transport and plant uptake model. Therefore, the objective of this study was to evaluate the application of LEACHM-N for predicting nitrate leaching in Batticaloa during Yala 2005. Field experiments were carried out from April 12th 2005 to June 30th 2005. The experimental treatments were 3 nitrogen rates (0, 70 and 140 kg N/ha) together with 3 irrigation rates (7, 14 and 30 mm) which resulted in 9 treatment combinations. The treatments were arranged in a split plot design in 3 replicates. Twenty seven cylindrical lysimeters with 1 m height and 50 cm diameter were built in at the experimental site. Outlets from each lysimeters were fixed with outflow pipes, directed to an underground sampling point, from where the water samples were collected. Red onion (Allium cepa; var. Vethalan) was planted in the lysimeters. Nitrogen fertilizer was applied 3 times during the cropping season. Irrigation water was delivered using a micro sprinkler system. Leachates from individual outlets were collected separately and NO3--N was determined spectrophotometrically by the Cadmium reduction method. A moderately good agreement has been found out in between the measured and the predicted NO3--N losses, but the model overestimated the losses. The treatment combination 140 kg N/ha with 30 mm of irrigation showed better simulation accuracy. It was also found out that the model was unable to predict preferential flow.Item Liquid junction photocells synthesized with dye coated zinc oxide films(University of Kelaniya, 2010) Samarasekara, P.Zinc oxide (ZnO) films fabricated using low cost methods were employed to synthesize a liquid junction photocell explained in this report. Methyl violet dye has been coated on ZnO films to enhance the light absorption. The thickness of the ZnO film and the separation between the Platinum electrode and ZnO film were varied in order to obtain the maximum efficiency of the photocell. The best photocurrent and photo-voltage could be measured for ZnO films coated with methyl violet dye for 12 hours. The optimum photocurrent obtained was 0.24 mA/cm2, which was a higher photocurrent for Methyl violet coated ZnO films. But the photo-voltage measured was comparable to the photo-voltage of ZnO films measured by some other researchers. Hence, a considerably higher optimum efficiency such as 2.4% could be obtained for these ZnO films consist of ZnO nanoparticles. The higher effective surface area provided by ZnO nanoparticles is the possible reason for this higher photocurrent.Item Impact of family income and size on per capita solid waste generation: A case study in Manmunai North Divisional Secretariat Division of Batticaloa(University of Kelaniya, 2010) Sivakumar, K.; Sugirtharan, M.The generation of solid waste has become an increasing environmental and public health problem everywhere in the world, especially in developing countries. The rate of generation of solid waste in the society is increasing with an increase of population, technological development, and the changes in the life styles of the people. As family size and income are the most significant factors affecting the quantity of solid waste from household consumption, a study on the relationship among these is vital in the decision making on waste management strategies. Therefore, a study was conducted at Manmunai North Divisional Secretariat areas of Batticaloa district to find out the correlation among residential solid waste generation, family size and income. The household sector is one of the primary sources of solid wastes in the study area. This study covered 100 houses with different socioeconomic levels such as income level and family size. There were six components of solid waste; food waste, paper, polyethylene, plastic, glass and metal which were evaluated in this study. Present study revealed that residential solid waste generation showed non-significant positive correlation (r = 0.184, p>0.05) with monthly income whereas significant positive correlation (r = 0.476, p<0.01) was found with the family size. Based on monthly income, generation of food, paper, plastic and glass waste showed non-significant positive correlation while non-significant negative correlation was found with polyethylene waste. Further, residential waste generation such as food, paper, plastic and metal showed significant positive correlation with family size whereas generation of glass and polyethylene waste showed non-significant positive correlation with family size.Item Effect of moisture stress at different growth stages of tomato plant (Lycopersicon esculentum Mill.) on yield and quality of fruits(University of Kelaniya, 2010) Vijitha, R.; Mahendran, S.There is a need to utilize the water efficiently and effectively because water availability is scarce in the dry zone of Sri Lanka. An experiment was conducted to determine the changes in fruit quality of tomato cv. KC-1 with moisture stress viz., determine the vitamin C, total soluble solids (TSS) and acid contents of tomato fruits during fruit ripening stage. Also, investigated in the present study was to find out the most critical stage/s of the plant growth to moisture stress in order to sustain the yield by efficient water management. Experiment was conducted at the agronomy farm of the Faculty of Agriculture, Eastern University, Sri Lanka. The experimental design was randomized complete block design with five treatments and four replications. Moisture stress was imposed during vegetative, flowering, early fruiting and fruit ripening stages of tomato for a period of four days in each growth stages. The control plants were watered daily to the field capacity. The stress cycle was single in which water was withheld completely at once. The result showed that moisture stress at fruit ripening stage reduced the vitamin C contents of fruits. The TSS and acid contents of the fruits were slightly affected by moisture stress when the stress was imposed during the fruit ripening stage but they were not significant. Vitamin C, TSS and acid contents of fruits were unaffected by moisture stress given during vegetative, flowering and early fruiting stages. Moisture stress reduced the yield of tomato and the stress during the flowering stage showed the highest yield reduction compared to the other growth stages. Hence, the flowering stage is the most critical stage of growth of tomato to moisture stress for the fruit yield.Item Detecting and preventing plagiarism in online assessment(University of Kelaniya, 2008) Wannige, C.T.; Sonnadara, D.U.J.; Usoof, H.A.; Hewagamage, K.P.Assessment is an important area in both teaching and learning. E-assessment is the foremost methodology for assessment in distance learning. This paper presents a method based on client-server architecture that can be used in capturing/preventing plagiarism in online assessments for distance learning centres. Among many possible scenarios of plagiarism, developed system focused on preventing or capturing unauthorised help obtained from online chat forms, websites or other types of communication mediums as well as use of stored text/restricted software. Bench tests show high degree of accuracy in capturing plagiarism scenarios by monitoring the change of grey values observed in edge detected screen shots. During pilot tests, participants attempted activities of plagiarism although the software was designed to prevent the act of plagiarism. The results show 97% accuracy in capturing plagiarism scenarios by the developed software in a restricted Ubuntu Linux environment.Item Mathematical structures in pattern organizations(University of Kelaniya, 2008) Kodituwakku, S.R.Since the introduction of design patterns, a large number of patterns have been identified and documented. As a result, patterns in the literature relate one another in different ways. Unfortunately, most of these patterns are not properly organized. In applying these patterns in to problems at hand novice designers encounter many difficulties such as identification and selection of collectively applicable set of patterns that suits the problem at hand. We investigate mathematical structures in existing pattern organization techniques such as pattern catalogues, pattern systems and pattern languages. Then we attempted to use these mathematical structures in developing a new organization technique. This paper proposes a new organization method and illustrates it with a collection of object oriented patterns drawn from the literature. Our investigation indicated that existing pattern organizations form graph structures and categorical structures. These structures are formed by patterns and relationships among them. The proposed organization method organizes patterns into sequences according to the relationships among patterns. This organization consists of two types of categories: major category and alternative category. The major categories are defined based on the Uses relationship and the alternative categories are defined based on the Variants, Refines and Conflicts relationships. Each major category consists of patterns that have potential to form a pattern system or a pattern language. So they assist practitioners in finding a sequence of related patterns that can be collectively applied to solve complex problems. Each alternative category consists of patterns that provide alternative solutions to the same problem or similar problems. It assists in finding a number of possible solutions (patterns) to a particular problem. The proposed organization combines these two types of categories by structuring them into pattern sequences. A pattern sequence consists of a major category and a collection of related alternative categories. Pattern sequences assist practitioners in finding a collectively applicable patterns and possible alternatives to them. So pattern sequences facilitate the selection of most appropriate sequences of patterns to solve complex problems without searching through the pattern literature.Item Sago as a medium for “in vitro” culture of some common soil bacteria(University of Kelaniya, 2008) Kapilan, R.; Thavaranjit, A.C.Nutrient agar (NA) medium is universally used as a general purpose medium for the culture of a broad range of bacteria and the cost of this commercially available medium is considerably high. Sago (Metraxylon sagu) contains a considerable amount of starch and a small amount of reducing sugars and is not used as a staple food in Sri Lanka. This study was aimed to find out the suitable composition of the sago medium compared with NA and to carry out growth studies of soil bacteria on sago medium. Media were prepared in different compositions by addition of different amount of sago in 100mL volume (25mL of distilled water + 75mL of young king coconut sap) separately. Bacterial suspensions (5.21×106 cfu/ml, SD=1.12) of Bacillus, Pseudomonas, Klebsiella, Enterobacter, Serratia and Staphylococcus were transferred on the selected sago medium separately by using spread plate techniques. There was no significant difference between sago and NA media in number of the colonies (t test; p = 0.05). Colonies appeared earlier in NA media than in sago media. But the colony morphological characters such as shape/form, margin, elevation, colour and size were almost similar to all bacteria selected on both media, except consistency. Thus, instead of NA the low cost and easily available sago medium could be recommended for the cultivation of soil bacteria.Item Applied magnetic field and stress induced anisotropy dependence of energy for oriented ferromagnetic thick films(University of Kelaniya, 2008) Samarasekara, P.The energy of perfectly oriented thick ferromagnetic films at different applied magnetic field and stress was studied using classical model of Heisenberg Hamiltonian. For the values of parameters used in this report, the energy required to orient the film with 1000 layers in 41.4° or 57.6° directions becomes minimum at applied magnetic fields of ω Hout = 4.8 or ω Hin = 4.8, respectively. The film can be easily oriented in 172° direction by applying the external stress ω Ks = 3.6 perpendicular to the film plane, for the values of parameters used in this report. These final results mainly depend on the values of other parameters used for calculations. The energy becomes minimum and maximum at almost the same values of oriented angle (θ), in plane magnetic field, out of plane magnetic field and stress for both sc(001) and bcc(001 lattice types. But the values of energies corresponding to maxima and minima are slightly different for the sc(001) and bcc(001) lattices.