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Development of soursop (Annona muricata L.) jam and evaluation of its quality parameters
(University of Peradeniya, 2019-09-12) Rodrigo, K. M. D. N.; Wijesinghe, W. A. J. P.; Jeewanthi, P. W.; Gunawardhana, C. R.
Soursop (Annona muricata L.) is a highly perishable underutilized fruit which is susceptible to postharvest losses. Postharvest losses can be minimized by processing the fruits into value-added products. Jam is a product with a process of combining fruit pulp, sugar, pectin and citric acid. This study aimed to develop a Soursop jam and assess its sensory, proximate and physicochemical properties. Soursop jam was produced by using a general recipe according to the Sri Lankan standard specification for jams, jellies and marmalades. Sensory attributes were evaluated during the storage time of two months using nine point hedonic scale. Proximate analysis was conducted for the final product. Total plate count and yeast and mold count were analyzed throughout the storage period at room temperature. Total soluble solids, titratable acidity, pH and ascorbic acid content were determined during the storage period. MINITAB 17 statistical software was used for data analysis. Sensory data were analyzed using Kruskal-Wallis test and physicochemical data were analyzed by one way ANOVA test with 95% confidence level. Only texture of Soursop jam was significantly changed (P<0.05) during the storage period. Proximate analysis revealed that Soursop jam contains carbohydrate (69.58%), moisture (29.46%), ash (0.4%), crude protein (0.29%) and fat (0.27%). Total plate count and yeast and mold counts were less than the standard maximum limits. Physicochemical results revealed that total soluble solids, titratable acidity and pH were not significantly changed (P>0.05) during the storage period while ascorbic acid content significantly decreased (P<0.05). In conclusion, Soursop jam is a better option for value addition to the Soursop fruit while minimizing postharvest losses.
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Multimineral fortification of chicken egg by supplementing sodium selenite, ferrous sulphate and zinc sulphate
(University of Peradeniya, 2019-09-12) Pushpamali, R. M. D.; Gunawardene, M.; Samarasinghe, K.; Chandrajith, R.; Himali, S. M. C.
The fortification of eggs can be used to alleviate micronutrients deficiencies in humans successfully. A study was conducted to investigate the effect of Sodium selenite (Na₂SeO₃), Ferrous sulphate (FeSO₄) and Zinc sulphate (ZnSO₄) incorporated diet on Selenium (Se), Iron (Fe) and Zinc (Zn) concentrations of eggs, egg quality and productivity traits of layers. The dietary treatments were basal diet and basal diet plus Na₂SeO₃, FeSO₄ and ZnSO₄ with the concentrations of Se 0.3 mg/kg, Fe 120 mg/kg and Zn 150 mg/kg. Concentrations of Se, Fe and Zn in egg samples were determined by using inductively coupled plasma mass spectrometer. The Haugh unit, shape index, yolk index, egg weight, eggshell strength, air cell depth, shell thickness and yolk color were measured weekly and a sensory evaluation of hard boiled eggs was carried out. Supplementation of minerals increased Se and Zn concentration in egg white by 28.6% and 50.9% (P<0.05) respectively. Fe concentration in egg yolk was increased by 15.7% (P<0.05). Feed intake/hen/day, egg production/hen/week and feed conversion ratio/kg eggs were not significantly different among the treatment and control (P>0.05). Egg quality characteristics showed a positive improvement, but with no statistically significant difference compared to the control group (P>0.05). Mineral supplemented diet markedly increased (P<0.05) egg weight and egg white weight than the control. Higher consumer preference was recorded to the yolk color (P>0.05) of mineral fortified eggs than the control. Mineral supplemented diet with Na₂SeO₃ (0.3 mg/kg), FeSO₄ (120 mg/kg) and ZnSO₄ (150 mg/kg) can be recommended to fortification of eggs with Se, Fe and Zn successfully and, it results positive improvements in egg quality. The egg production parameters are not affected by the fortification concentrations and combination used in the current study.
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Evaluation of food search behavior of cryptolaemus montrouzieri a predatory beetle of mealybugs
(University of Peradeniya, 2019-09-12) Wijekoon, W. M. S.; Warnasooriya, P. G. A. S.; Hemachandra, K. S.
Biological control of insect pest has been widely accepted as it is specific, residue free and eco-friendly nature and considered as the most promising approach in insect population management in agroecosystems. Parasitoids and insect predators are used as biocontrol agents and use of predators are more appropriate when the host population is increasing rapidly. Search and feed behavior of predator is a key factor that influences the efficacy of the approach. Cryptolaemus montrouzieri, a predatory coccinellid beetle which has been in use mainly in greenhouse pest control in European countries. This species is naturally available in Sri Lankan ecosystem and a potential candidate for mealybug control. This study was conducted with the objective of evaluating the search and feed behavior of C. montrouzieri on Phenacoccus manihoti. The maximum distance that C. montrouzieri larvae can respond for food and search behavior of the adults was examined under laboratory conditions. The time taken to reach the food source when given at 5, 10, 15 cm distances, was significantly different with second instar larva (L₂) (P<0.05), third instar larva (L₃) (P<0.05) and fourth instar larva (L₄) (P<0.05). All three instars could not find the food source when the distance was over 5 cm within a two hour period. With respect to the food search time by adults, adults took 42.5±5.7 minutes to locate food when the source was at 12.5±0.7 cm distance. Upon finding the food, most adults fed on food for 153.7±14.3 minutes and some beetles started the second search, and found them 10.6±0.9 cm away from the first food source by the end of the observation period. No significant difference was observed between males and females with respect to the search duration; however, the feeding (P<0.05) and resting durations (P<0.05) were significantly different. These data reveal the potential of C. montrouazieri as a predator of mealybugs.
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Impacts of sea level rise and bed level accretion on residence time of Negombo lagoon, Sri Lanka
(University of Peradeniya, Sri Lanka, 2015-11-06) Pushpakumara, P.K.P.; Nandalal, K.D.W.; Weerakoon, S.B.
Water quality of an aquatic system is highly influenced by residence time (RT), which indicates how long a constituent is retained inside the system. This paper focuses on the effect of climate change induced future sea level rise (SLR) and associated bed level variations on RT of Negombo lagoon, Sri Lanka. The hydrodynamic behaviour of the lagoon was numerically simulated using Delft3D surface water modelling suite. The time required to drop the concentration of a constituent to of its original value was calculated as the RT of the lagoon. Anticipated maximum SLR of 79 cm at the end of the 21st century, predicted by the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, was considered as the future sea level of the lagoon. Three bed level accretion conditions, namely, no bed level accretion, accretion of the lagoon bed level by 50% of the SLR (partial bed level accretion condition) and accretion of the lagoon bed level similar to the SLR (full bed level accretion condition), in response to the anticipated SLR were considered. RT was calculated for each bed level variation under low (5.64 ) and high (41.93 ) streamflow conditions. Model predicted RTs of the lagoon at present are 22.4 days and 12.4 days under low and high streamflow conditions, respectively. Under the absence of bed level accretion, RT is increased up to 32.2 days (+43.7%) and 17.8 days (+43.5%) due to SLR in low and high streamflow periods, respectively. Under partial bed level accretion, RT is decreased up to 18.1 days (-19.2%) and 12 days (-3.2%) in low and high streamflow periods, respectively. RT is decreased up to 13.4 days (-40.2%) and 8.5 days (-31.5%), under full bed level accretion, in low and high streamflow periods, respectively. The results reveal that the climate change induced future SLR and the associated bed level accretion influence the RT of the lagoon altering the lagoon water quality.
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Antibacterial activity of selected seaweed extracts against some selected infectious pathogens
(University of Peradeniya, 2019-09-12) Maria Nimalini, M.; Vasantharuba, S.; Kapilan, R.
The antibacterial efficacy of methanolic extracts of marine algae, Caulerpa racemosa (Chlorophyta), Sargassum polycystum and Turbinaria ornata (Phaeophyta) against some selected gram-positive and gram-negative human pathogenic bacteria was studied. Dried and powdered sample (3g) of the seaweeds collected at the Nachchikuda and Keerimalai coastal area in the Northern region of Sri Lanka was diluted with 60 ml 70% methanol. This mixture was homogenized at different duration and then filtered by using whatsman No 1 filter paper to obtain clear extract. This extract was used to test the antibacterial activity against appropriately diluted Gram-positive bacterial species Enterococcus faecalis (ATCC 29212) & Staphylococcus aureus (ATCC 29213) and Gram-negative bacterial species Escherichia coli (ATCC 25922) & Pseudomonas aeroginosa (ATCC 27853) using agar well diffusion method in triplicates. Results showed that significant amount of inhibition zone was obtained against all the tested bacterial species which was comparable with positive control streptomycin and negative control 70% methanol. Turbinaria ornata have significantly highest antibacterial activity against all test organisms followed by Caulerpa racemosa and Sargassum polycystum. The selected seaweeds showed their highest and lowest inhibition zone against Staphylococcus aureus (19.06±1.15mm) and Enterococcus faecalis (12.32±0.76mm).