IRSPAS 2019

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Effect of substrate temperature variation on opto-electronic properties of thermally evaporated CdS thin films
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Lakmal, A. A. I.; Kumarasinghe, R. K. K. G. R. G.; Maddumage, D. C.; Kumarage, W. G. C.; Munasinghe, M. A. H. M.; Seneviratne, V. A.; Dassanayake, B. S.
Cadmium sulfide (CdS) is a II-VI group semiconducting material which has been thoroughly investigated due to its superior optical and electrical properties that can be applicable in wide range of semiconductor devices including photonic devices. Due to its direct and wide bandgap (~ 2.42 eV), it is vastly used as the window layer in heterojunction thin film solar cells. Compared to other deposition methods such as electrodeposition, spray pyrolysis, chemical bath deposition; thermal evaporation is an attractive method of deposition due to its high deposition rate, low cost of operation, low material consumption, minimum number of impurities and straight-line propagation of vapors. In the present study, CdS thin films were deposited on cleaned FTO glass substrates using thermal evaporation technique at substrate temperatures ranging from 50 to 250 °C at a pressure of 2×10-5 torr. Deposition was carried out using CdS powder (Sigma-Aldrich, 99.995%) using an alumina boat. Deposited samples were then annealed at 300 °C for 30 minutes in vacuum (pressure of 3×10-5 torr). Structural, optical and electrical properties of annealed CdS thin films were studied by employing X-ray diffraction, UV-Vis spectrometry, I-V measurements and capacitance vs. voltage measurements. All the electrical characterizations were carried out using a photoelectrochemical cell of (CdS/0.1 M Na2S2O3/Pt). The XRD analysis shows all the grown films are preferably oriented in the direction of (002) of hexagonal CdS. The optical band gap values were found to increase with increasing substrate temperature from 50 to 175 °C. ISC and VOC values of (CdS/0.1 M Na2S2O3/Pt) cell were also found to increase up to the substrate temperature of 175 °C. The observed highest ISC and VOC values were 37.24 μA and 314.9 mV respectively. Results indicate that the CdS thin films deposited at the substrate temperature of 175 °C has yielded the best optical and electrical properties compared to the films grown at other substrate temperatures
Implications of Fall Armyworm epidemic in Sri Lanka: A case study in Rathnapura district
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Perera, R. N. N.; Magamage, M. P. S.; Siriwardhana, C.
The first emergence of the Fall Armyworm (FAW; Spodoptera frugiperda) was reported in Sri Lanka during August 2018 and caused a substantial yield loss in maize cultivation especially in Uva, Eastern, North Central, North Western, Northern and Sabaragamuwa provinces. During the 2018/19 Maha season, over 50 percent of the entire maize cultivation has been infested by the pest. The objective of the study was to understand the magnitude of FAW infestation, social response and its implications in Rathnapura district in Sri Lanka. This was considered as mandatory in terms of easiness in accessibility to close supervision by the university as well as with the objective of preventing infestations reaching economically catastrophic levels. Simultaneously to the field inspection programme, a survey was conducted in January-March 2019 in 13 maize growing agriculture instructor (AI) areas in the Rathnapura district to evaluate the severity of FAW infestation with the collaboration of the Provincial Department of Agriculture, Sabaragamuwa Province. University academia, students, and field officers from Department of Agriculture were participated to the survey and all 13 divisions were covered for collecting pest incidence information. GIS data were recorded in each point of infestation together with related other information such as land extent, host plant characteristics and the type of cropping system which plays important role in forecasting the pest occurrence in the subsequent cropping season. Based on the field survey, there were no evidences reported that pest occurrence in other crops apart from maize. Moreover, even in mixed cropping systems with little number of maize plants, heavy infestation was recorded only in maize. Data analysis was done based on the primary land infestation records obtained from each AI range by using MS office Excel 2010. Amount of land extent use for maize cultivation in Rathnapura district was estimated as 292.65 ha, while 32.95ha were infected with the pest (11.3%). Kaltota, Embilipitiya, Ambawila and Thimbolketiya were the AI areas with highest infestation recorded in the Ratnapura District reporting 5%, 4.8%, 4.5% and 3.85 % infestations respectively. Throughout the study period, attention was made by the research team for minimizing livelihood damage by conducting interactive awareness programs, which were directed to proper identification and control further spread of the pest. Even though maize was cultivated comparatively lower land extent in Rathnapura, effective and organized disaster management response in Rathnapura was able to minimize the pest impact to 11.3% from total losses. Mobilization of the whole agriculture community has wider implications in effective controlling of FAW while preserve the farmer trust on agriculture policy in Sri Lanka.
Cyanobacteria and 2-Methylisoborneol: the influence of Nitrogen and Phosphorous
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Ganegoda, S. S.; Chinthaka, S. D. M.; Manage, P.M.
2-Methylisoborneol (2-MIB) is a key compound, which causes taste and odour (T&O) issues in water. Despite of no recorded health hazards reported associated with 2-MIB, water consumers reject the water with 2-MIB due to its unpleasant musty (moldy) T&O. The aim of this study was to study the correlation between cyanobacteria abundance, 2-MIB levels coupled with Nitrogen and Phosphorous levels. 2-MIB contamination level in sixteen raw water bodies, which are being used for drinking in six districts (Anuradhapura, Pollonnaruwa, Ampara, Batticaloa, Trincomalee and Hambanthota) were analyzed using Gas Chromatography–Mass Spectrometry coupled with Solid-phase micro extraction. Enumeration and identification of cyanobacteria was carried out using standard microscopic methods. Anabaena, Microcystis, Oscillatoria, and Cylindrospermopsis species were identified as the most abundant cyanobacteria. 2-MIB levels ranged from 5.3 ± 0.94 to 139.4 ± 0.21 ppt throughout the dry season of the sampling period, where the highest level was recorded in Kondawatuwana tank (139.4 ± 0.21 ppt) and the lowest was detected in Ridiyagama tank (5.3 ± 0.94). At wet season, 2-MIB levels ranged from 4.4 ± 0.78 to 73.8 ± 0.65 ppt, where the highest level was recorded in Jayanthi tank (73.8 ± 0.65 ppt), while the lowest was detected in Ridiyagama tank (5.3 ± 0.39 ppt). Recorded 2- MIB level was greater in dry season compared to the wet season. Seventy five percent (75%) of the sampling locations exceeded the human threshold levels of 2-MIB (5 ppt). Questionnaire survey showed that more than 95% end water consumers rejected drinking water contaminated with 2-MIB. Further it was found that the total cyanobacterial cell density (T.C.D) was positively correlated with 2-MIB and total phosphorous levels (p<0.05). Moreover, cell densities of Oscillatoria, Anabaena and Cylindrospermopsis species showed significant positive correlations (p<0.05) with 2-MIB contamination levels along with Pearson Correlation Coefficients (P.C.C) of 0.788, 0.682 and 0.731. However, no significant correlation was observed between Microcystis sp. and 2-MIB. Further, 2-MIB showed significant positive correlation (p<0.05) with total phosphorous (P.C.C 0.876), electrical conductivity (EC) (P.C.C, 0.771), and pH (P.C.C, 0.825). Increment of pH value leading to alkalinity is a known optimum condition for cyanobacteria growth while the current study shows alkalinity is favorable for 2-MIB. No significant correlation was obtained between total nitrogen (Nitrate –N, Nitrite –N, Ammonia –N) and 2-MIB nor T.C.D and total nitrogen. Thus, the results of the study indicate there is a direct positive correlation between 2-MIB, cyanobacteria and total phosphorous.
Assessment of groundwater contamination with environmental toxicants in CKDu endemic area, Polonnaruwa, Sri Lanka
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Perera, W. P. R. T.; Dayananda, M. D. N. R; Botheju, W. S. M.; Liyanage, J. A.
Chronic Kidney Disease unknown etiology (CKDu) is one of the major health impacts predominantly confined to people in North Central Province in Sri Lanka. The root courses for the disease prevalence have not found yet. Therefore, this investigation was carried out to determine the groundwater contamination with environmental toxicants: Cadmium (Cd), Chromium (Cr), Copper (Cu), Lead (Pb), Zinc (Zn), Arsenic (As), Iron (Fe), Calcium (Ca), Magnesium (Mg) Fluoride (F), Sodium (Na) and Aluminium (Al) in Dimbulagala Grama Niladhari Division (GND) in Polonnaruwa District, Sri Lanka. The study investigated the groundwater quality of Dimbulagala GND in dry zone of Sri Lanka to assess its suitability for drinking purposes. Only Ten working tube wells were found in the studied area and groundwater samples were collected from the tube wells. Basic physicochemical parameters (pH, temperature, conductivity and dissolved oxygen), (Hatch HQ14d) and fluoride content were determined (Orion Star- 2014) onsite. Environmental toxicant concentrations were determined using Inductive Coupled Plasma Mass Spectrometry (ICP–MS, Agilent 7800). Results were analyzed using SPSS statistical software. descriptive statistics were performed on the data set and the Pearson correlation was applied. According to the results obtained from the onsite investigations the mean values of pH, conductivity and fluoride content were 7.78 (+1.28), 520 us/cm (+148) and 1.20 mg/l (+0.32) respectively. The mean value of the fluoride content has exceeded the permissible limit (1.0 mg/L), (SLS 614-2013). It was highlighted that significant toxic heavy metals such as Lead (Pb), Cadmium (Cd), Chromium (Cr) and Arsenic (As) levels as well as other metals like Fe, Cu, Zn, Na, Al have not been exceeded than permissible limits (SLS 614-2013). Statistically evaluation process proved none of the positive correlation is reported between heavy metal concentrations and Fluoride content of the groundwater in the studied area. But a negative correlation was reported between Fluoride and Cr (p= -0.05) in the groundwater in the studied area. Ca and Mg concentrations ranged between 3.43 mg/l to 130.56 mg/L And 6.54 mg/L to 75.32 mg/L respectively. Although mean Ca (10.12 mg/L) and Mg (15.45mg/L) did not exceed the permissible levels (100 mg/L and 30 mg/L for Ca and Mg), 40% and 50% of individual samples for Ca and Mg levels exceeded the permissible levels respectively. There is an urgent need for establishing proper long term drinking water treatment method for the studied area because of long term exposure to heavy metals such as Cd, Pb, Cr, As, and high levels of Fluoride as well as other environmental toxicants can be harmful to people. These findings can be used as a benchmark of raw water quality in the design processes of treatment plants
Determination of antimicrobial efficacy of some commercially available therapeutic mouthwashes
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Rathnayake, R. M. S. U.; Jayaratne, D. L.
Mouthwashes are medically formulated liquids, which are held in the mouth and swished by the action of perioral musculature to eliminate oral pathogens. Many mouthwashes are often used by people as they are prescribed by the dentistry, in order to prevent several oral conditions and to treat them. Many of the commercially available mouthwashes are claiming to have antimicrobial properties. This in vitro study, mainly aims to determine the different levels of antimicrobial efficacies in some commercially available therapeutic mouthwashes. The study included four commercially available mouthwashes and they were named as Mouthwash 1, 2, 3 and 4. A newly formulated Ayurvedic mouthwash was also included. The antimicrobial efficacies of these mouthwashes were tested against five selected microorganisms; namely, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Streptococcus pyogenes and Candida albicans. Many of the microorganisms used in the test are significant in dentistry for causing several oral problems. Original concentration of the mouthwashes used in the study was decided as per the medical directions given for each mouthwash. Agar well-diffusion method and agar disc-diffusion method were used to determine the antimicrobial efficacy levels of the mouthwashes. Each experiment was replicated thrice. Validation test was carried out to confirm that the analytical procedure employed in the test is suitable for its intended use, which ensured there is no effect of penetrability of the substances in agar that may affect the results. The diameter of the inhibition zones obtained from the agar well diffusion and disc-diffusion methods were measured in each case and the obtained results were statistically compared using the Tukey’s method. The results obtained from the Tukey’s method indicated that the highest antimicrobial effectiveness was shown by mouthwash 1 against C. albicans in both disc diffusion and well diffusion methods showing an average inhibition zone diameter of 20.67 cm in both methods. The second highest antimicrobial effectiveness was shown by the mouthwash 1 against S. pyogenes and the third highest antimicrobial effectiveness was also shown by the mouthwash 1 against E. coli. The active antimicrobial component contained in Mouthwash 1 was chlorohexidine gluconate. When comparing the two non-herbal mouthwashes, the least effectiveness was showed by the mouthwash 2 against P. aeruginosa. Mouthwash 2 contained chlorohexidine digluconate as the active antimicrobial ingredient. The herbal and Ayurvedic mouthwashes did not show any antimicrobial properties in the particular tests.
Phytoremediation of diazinon residues by Schoenoplectus grossus plant
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Rashmika, R. W. H. C.; MathotaArachchige, Y. L. N.
Diazinon is a common non-systematic organophosphorus insecticide used by present cultivators to protect crops like rice, fruit trees and potatoes. But, over exposure to diazinon mainly affects the inhibition of acetylcholinesterase of humans. Therefore, to remove these organic pollutants from soil several methods could be followed. Phytoremediation, soil flushing, thermal desorption, biopiles and land farming are some of the methods that can be carried out to decontaminate the polluted soil. In this study phytoremediation technique which is the use of plants for the cleanup pollutants was carried out since it is more cost effective and environment- friendly. This model study was conducted using the Schoenoplectus grossus plant. Twenty one pots with same amount of air dried medium loam soil (5.00 kg) were maintained. Plants Schoenoplectus grossus were planted in fourteen pots. There were three plants of Schoenoplectus grossus in each pot. New plants were grown naturally within two months causing the death of initially planted plants. The commercially available diazinon insecticide (624.35 g/L, 117.00 μL) was sprayed homogenously into seven pots with the plants. Other seven blank pots with plants which were filled with non-contaminated soil were maintained for obtaining data about background pesticide present in the plants. Seven pots without plants were maintained to calculate the loss of pesticide due to environmental factors like microbial degradation, evaporation, leaching and photolysis. After 2 hours, 1, 3, 5, 8, 10 and 12 days the diazinon residues remaining in soil (10.00 g), shoot (5.00 g) and root (5.00 g) samples were extracted using Soxhlet method and were quantified using high performance liquid chromatography in the presence of UV–DAD detector. Results showed that the concentration of diazinon residue at eight-day exposure reached 3.82 ±0.01 mg/kg in roots and 4.17 ±0.03 mg/kg in shoot. After eight days the concentration of diazinon residues in both root and shoot decreased. Results indicated a significant difference in the concentrations of diazinon residues in soil between the pots with Schoenoplectus grossus plant and the pots without the plant. The concentration of diazinon remained in pots with the plants (1.82 ±0.01 mg/kg in eighth day) was less than the pots without the plant (1.38 ±0.03 mg/kg in eight day). The plant Schoenoplectus grossus can tolerate 13.65 mg/kg of diazinon concentration and grows rapidly and produced high biomass. Therefore, the plant Schoenoplectus grossus can be recommended as a good candidate for the phytoremediation of diazinon residues.
Stable forecasting of tax revenues of selected countries assisted by Clustering Approach
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Karunarathne, A. W. S. P.; Liyanage, U. P.; Hewaarachchi, A. P.
Tax is one of the main income of a government that utilizes in public welfare and future investment. Taxation has goals: reducing the inequalities through a policy of redistribution of income, administrating the levels of inflation as well as deflation, protecting the local industries from foreign competitions through levies, and discouraging the undesirable activities such as consumption of tobacco. Additionally, taxation provides a major portion of Gross Domestic Product (GDP), depending on the country’s fiscal policy. Tax forecasting is essential towards strategizing government plans and future activities. However, tax revenue highly fluctuates due to many factors which include natural disasters, instability of political environment and government monitory policies. This study aims to find the set of best statistical forecasting models, by comparing the behavioral similarities of different tax revenues identified by clustering approach. Here, tax revenue data from 1972 to 2017 of 24 countries belonging to developing status: developed, developing and under-developed have been analyzed. Comparable and homogenize measure is obtained considering the tax revenue as a percentage of GDP. The countries with similar tax revenue are identified by using K-Means clustering. Consequently, the selected countries were clustered into five classes depending on their tax revenue as a percentage of GDP. The analysis shows that the tax revenue has similar behavior based on the similarities of countries’ developing status. Tax revenues data in each cluster were analyzed to identify the best fitted time series models. It has been found that models of the types Autoregressive Moving Average (ARMA) and Autoregressive (AR) are best fitted models for the representing tax revenue of the corresponding clusters. As an example, ARMA (2,2) model was fitted to one cluster and AR (1) model was fitted for another cluster of countries. According to the type of the model and their range of parameter values, it is found that similar models can be used to represent the tax revenue data within the underlying cluster. That is, there exist cluster specific models in the sense of model type and their parameter ranges. This finding can be utilized towards forecasting tax revenue in the case of the revenue data are highly affected with a qualitative factor, for example, political instability. In summary, through the clustering approach, stable forecasting of revenue data of a given country can be performed.
Effect of CaCO3 on mechanical properties and degradability of polythene manufactured from low density polyethylene
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Abeywickrama, M. S. J .; Yatawara, M. D. M. D. W. M. M. K.
One of the major drawbacks of polythene manufactured from low density polyethylene is its poor degradability in the environment. The present study was therefore planned to assess how the addition of CaCO3 effect on the mechanical properties and on the degradability in ambient air, soil and in compost. Two types of polythene films, one with 100% polyethylene (P001) and another with 86% polyethylene + 14% CaCO3 (P002) were manufactured by a film extruder machine. The mechanical properties including thickness, tensile strength, elongation, moisture and water absorption of the two types of films were analyzed at the beginning of the experiment (n=10 for each test). Half of each film (n=144) was immersed in food waste contaminated water while the other half (n=144) was used as the control. One third of each of food waste contaminated film (n=28) was kept in ambient air while another one third was buried at 10 cm depth in soil. The remaining one third was buried in compost. The same procedure was carried out for control films. The percentage degradability was assessed after two and four months’ time intervals and the percentage degradability was calculated with respect to weight losses of films with time. A significant reduction of machine direction (MD) and transverse direction (TD) of both tensile strengths and elongations were shown by P002 (p< 0.05; student t-test). In addition, P001 showed 0.20% moisture content while P002 showed 0.01% moisture. Both films showed 0.03 mm initial thickness and P002 showed a significantly highest water absorption. The food waste contaminated P002 kept in ambient air showed 0.13% degradability while P001 showed 0.12% degradability after 4 months. Nevertheless, the food waste contaminated P002 showed 2.4% (non-contaminated- 2.1%) degradability while the food waste contaminated P001 showed 0.8% (non-contaminated- 0.6%) in soil. The food waste contaminated P002 showed 0.8% (non-contaminated- 0.7%) degradability while the food waste contaminated P001 showed 0.5% (non-contaminated- 0.3%) in compost. Nevertheless, transparency reduction and dark spots were also observed from food waste contaminated P002 buried in both soil and compost. The results further revealed that the films contaminated with foods (buried in both soil and compost) degraded more than those of the non-contaminated films but their percentage degradability were less than 2.5% by 04 months. The overall results conclude that CaCO3 was able to significantly reduce the mechanical properties; but unable to increase the degradability in the environment. Therefore, the present study implies that the addition of CaCO3 to polyethylene only makes the manufacture cost effective
Mapping the land use land cover impacts by the war using remote sensing and GIS in Maritimepattu division, Sri Lanka in 1979, 2010 and 2018
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Sandamali, K. U. J.
Land cover is defined as the layer of soil and biomass, including regular vegetation, harvests, and human structures, that involves the land surface. Land use refers to the reasons for which people activity in the land cover. Land cover and land use (land use/cover) are firmly related and reliant, and much of the time treated conversely. Land use/cover change is the impact of many collaborating forms that are dynamic over a wide scope of scales in reality. Advances in remote detecting and spatial examination methods have profited specialists of incredible assets for mapping and distinguishing changes in land use/cover. Recent investigations have utilized these advanced strategies for the study of land use/cover changes. The Mullaitivu town of Maritimepattu division has been the point of convergence of the armed conflict between the administration of Sri Lanka and the Liberation Tigers of Tamil Eelam (LTTE) for more than two decades. Consequently, the Mullaitivu zone has been influenced seriously in contrast with different regions of Sri Lanka. Landsat satellite images were used due to freely available, reliable data source with longer time coverage. In this study, Landsat 2, 5 and 8 images of 1979, 2010 and 2018 were used as the data sources respectively. Digital image processing used to get ready land use/cover maps from satellite images contained various advances including digital image preprocessing for removal of errors in atmospherically and geometrically, image enhancement for increasing the accuracy of images, and image classification for identify relevant land use/cover classes. All these steps were done with the use of ENVI and ArcGIS 10.1 software. Supervised image classification of maximum likelihood classification was used for preparing land use/cover maps and the training samples of accuracy assessment and signature collection for classification done with historical maps, historical records, Google earth images, pan-sharpening technique, and false color and true color composite images. In addition the statistical analysis was performed to calculate the land use/cover variation within the period. Rendering to the study, it reveals that vegetation and settlements were getting highly decreased in the war period by 11.97% and 5.54% respectively and on the other hand forest area get increased by 2.86 %. Furthermore, according to the 2018 image (nearly after 10 years from the war), there were 10.52% and 13.10% of the increase in settlements and vegetation in the Mullaitivu area respectively.
Evaluation and comparison of antioxidant properties and total phenolic content of pomegranate (Punica granatum L.) peel and juice
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Panapitiya, P. D. S. N. H.; Weerasooriya, M.K.B.
Pomegranate peel is currently a waste but contains valuable, rich with a diverse range of bioactive compounds. The objective of the present study was to assess the antioxidant properties by IC50 value and FRAP value, total phenolic content (TPC), total flavonoid content (TFC) and total anthocyanin content (TAC) of the peel (PP) and the juice (PJ) of local pomegranate cultivars, Nayana, Nimali and Kalpitya red. Antioxidant properties were tested by FRAP and DPPH assay. TPC was measured spectrophotometrically using the Folin Ciocalteu method and expressed as mg Gallic acid equivalents (GAE)/gram. TFC was evaluated by the aluminum chloride assay. TAC was detected by the vanillin assay. The TAC and TFC of PP of Nimali, Nayana and Kalpitya red cultivars were 22.12 ± 0.20, 49.05 ± 0.30 and 69.08 ± 0.57 mg catechin equivalents (CE)/g and 67.67 ± 0.59, 59.58 ± 0.85 and 75.99 ± 0.85 mg rutin equivalent (RE)/g respectively. The TAC of PJ ranged from 0.40 ± 0.01 to 2.82 ± 0.03 mg CE/g was nearly 60 times less than that of PP of the same cultivar. The TFC of PJ ranged from 0.39 ± 0.00 to 0.80 ± 0.00 mg RE/g was nearly 100 times less than that of PP. The TPC and FRAP values of PP of Nimali, Nayana and Kalpitya red cultivars were 469.67 ± 8.97, 413.92 ± 4.75 and 318.82 ± 4.66 mg GAE/g and 6690.00 ± 153.00, 4270.60 ± 83.00 and 4512.00 ± 14.00 μmol Fe2+/g respectively. The TPC of PJ varied from 0.87 ± 0.02 to 1.98 ± 0.04 mg GAE/g was nearly 300 times less than that of PP. The FRAP values of PJ ranged from 15.57 ± 0.36 to 40.18 ± 0.29 μmol Fe2+/g were nearly 200 times less than that of PP. The IC50 values of PP of Nimali, Nayana and Kalpitya red cultivars were found to be 14.20, 20.40 and 18.00 μg/mL respectively. The IC50 values of PJ were in the range of 915-3098 μg/mL, nearly 100 times higher than that of PP. The results revealed that PP contains exceptionally high TPC and antioxidant properties observed by IC50 and FRAP values with respect to PJ of the same cultivar. The PP of Nimali cultivar had the highest antioxidant properties and TPC. The PP of Kalpitiya red cultivar possessed the highest TFC and TAC. Thus, PP has a high potential to be utilized as a resource of bioactive compounds. The results proved that there is no correlation between phenolic compounds and the antioxidant properties. All the parameters tested were significantly different (p<0.05) among the cultivars.
Release of curcumin from chickpea protein submicron particles at gastrointestinal pH values
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Shakoor, I. F.; Pamunuwa, G.; Karunaratne, D. N.
Activity of bioactive components such as curcumin, which is a natural polyphenolic compound, depends on their stability, solubility, absorption and bioavailability at specific sites. Development of natural polymer based oral delivery systems for controlled delivery of bioactives has become essential in order to improve the aforementioned characteristics of those compounds. Among the biopolymers used in the formation of delivery vehicles, protein holds a prominent place due to its high biocompatibility and biodegradability. Chickpea (Cicer arietinum L.) protein shows high protein bioavailability and it has been used successfully in drug encapsulation processes. Therefore, the purpose of the study was to develop curcumin-loaded submicron particles using chickpea protein, and to characterize, and to evaluate the release of curcumin via understanding its release kinetics from the protein matrix. To prepare chickpea protein isolates, alkaline extraction and subsequent precipitation of the proteins at the isoelectric point (4.5) was followed. Glyoxal was used as a cross-linker. In vitro release studies were carried out using the dialysis bag method, using UV-visible spectroscopy for quantification, at simulated gastric and intestinal pH buffers without enzymes. The release profiles were fitted in to eight different mathematical models namely Zero order, First order, Higuchi, Hixon-Crowell, Korsemeyer-Peppas, Baker-Lonsdale, Weibull and Gompertz, to determine and interpret the kinetics of the drug release from the protein matrix. Encapsulation efficiency showed a high value of 89 % and loading capacity approximated to 0.45 %. Average particle size, polydispersity index and zeta potential were found to be 466.9 nm, 290.5 % and -10.8 mV, respectively. Release of curcumin from the protein matrix showed a slower controlled release compared to the release of free curcumin at both pHs. Release of encapsulated curcumin at pH 2 showed a much higher release compared to the release at pH 6.8. In fact, maximum release at pH 2 and pH 6.8 were approximately 26 % and 16 % at the sixth hour, respectively. Release profiles of curcumin encapsulated protein fitted well with Higuchi and Weibull models at pH 2 and 6.8, respectively. At pH 6.8, release followed a Weibull sigmoidal pattern showing an asymptotic maximal release. At pH 2, release of encapsulated curcumin followed a diffusional release from the matrix. This study indicates differential release behaviour of curcumin from chickpea delivery vehicles at gastric and intestinal pH conditions
Generic assumption vs. actual stem carbon content in three selected street tree species in urban setting of Colombo, Sri Lanka
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Kulangana, T.; Bandara, W. A. R. T. W.
Current interest on removal of anthropogenic CO2 emissions from urban areas through plants, arises with the potential of trees in urban environments to sequester atmospheric carbon and offset the increasing CO2 concentrations within the cities. Prediction of carbon stocks in trees that indicate their relative capacities is based on estimations founded on assumptions. The widely used assumption is that the carbon content of stems accounts for 50% of the biomass. Present study investigates the extent to which the organic carbon estimates based on this assumption, for Mudhuca longifolia (Mee), Cassia fistula (Ehala) and Pongamia pinnata (Karanda), the most abundant species in Colombo Municipal Council area, deviate from the actual content of organic carbon in their stems. Streets with highest abundance of these species were selected for sampling (purposive method). Sixty individual trees of each species were randomly selected from the selected streets. Tree diameter at breast height (DBH), total height, crown height, and crown diameter were measured. Stem core samples were collected and the core carbon content per unit biomass was measured using loss on ignition method. The core carbon content was extrapolated to estimate the total carbon content in the stems by multiplying with the tree biomass. Carbon content of the stems were also calculated using the assumption of 50% of biomass is composed of carbon. Both values were compared using One way ANOVA followed by Tukey’s pairwise comparison. For M. longifolia, C. fistula and P. pinnata, results showed that stem carbon content only had a statistically significant relationship with DBH. Furthermore, there was a significant difference between the assumed and estimated carbon contents (P<0.05) in the stems of the three species. It was revealed that the assumption of 50% of the biomass to be composed of carbon, results an underestimation of the true carbon content of the stems
Preparation, characterization and properties of activated carbon derived from rice husk
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Perera, P. L. R. A.; Rajapakse, C. S. K.
Rice, the staple food of the Sri Lankans is one of the important crops occupying 34% of the total cultivated area in the country. Thus, rice processing generates a large quantity of rice husk as waste material. The main objective of the present work was to investigate the potential of using this agricultural waste, rice husk as a precursor for the production of low-cost activated carbon (AC) as an adsorbent for the removal of heavy metals (Pb(II), Cd(II) etc.). Therefore, the present study was carried out to evaluate the effect of carbonization time and activating agent on AC production from rice husk and its Pb(II) removal capacity. Cleaned and dried rice husks samples (12.00 g) were separately carbonized at 400 °C under constant nitrogen flow for 60 minutes -150 minutes (60 min, 90 min, 120 min, 150 min) and chemically activated by HCl. The AC yield was calculated in each sample. In order to determine the lead removal percentages (Pb%) of AC derived from rice husk at different carbonized temperatures, first AC samples were added (1.00 g) separately to a Pb(II) standard solution (5.00 mg L-1), stirred for 1 hour at pH 7 at room temperature. The solutions were filtered and the residual Pb was determined by Atomic Absorption Spectrophotometry (AAS). All the experiments were performed in duplicate. Further, the AC with the highest Pb removal capacity was characterized by Scanning Electron Microscopy & Energy Dispersive Spectroscopy (SEM/EDAX), and Fourier Transform Infrared Spectroscopy (FT-IR). Proximate analysis, of the AC were also studied. The percent yield of AC prepared from rice husk with HCl activation, and its corresponding % Pb removal potential were fluctuated with increasing carbonization time. The highest AC yield (20.50%), the highest % Pb removal (93.31%) was observed for the AC prepared by carbonization of rice husk at 400 °C for 120 minutes with HCl activation. The results of the proximate analysis revealed that the ash content, moisture content volatile matter content and fixed carbon content of the AC were 32.47%, 34.94%, 24.20%, and 8.39% respectively. Based on the results, it can be concluded that AC derived from rice husk can be considered as an efficient and cost-effective adsorbent for the removal Pb(II) from wastewater
Differential transform method for an immunology model of HIV
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Silva, M. B. G. M. K.; Peiris, C. M. B. I. N.; Wimaladharma, N. A. S. N.
Human Immunodeficiency Virus (HIV) mainly attacks a person’s immune system. The virus destroys 𝐶𝐷4+𝑇 cells, which mainly fight against the infection. As a result, the probability of facing the risk of various deadly infections increases and sometimes it leads to a cancer due to the weakening of the immune system. The main objective of the research is to solve a system of ordinary differential equations for a dynamic model of HIV using semi numerical analytical method, namely differential transform method (DTM). The solutions, which were obtained from DTM were compared with the solutions of modified Euler method and forth order Runge Kutta (RK4) method. Moreover, Pade approximation was applied for DTM. Pade approximated solutions were obtained by using a limited number of coefficients of solutions of power series given by DTM. The results of the research show that DTM is an efficient method to solve systems of nonlinear ordinary differential equation such as dynamic model of HIV. The solutions well behaved for small time intervals. Hence, the Pade approximation was applied with DTM in order to obtain accurate solutions for large time intervals.
Developing a scale to assess the Spiralling Whitefly, Aleurodicus disperses Russel (Hemiptera: Aleyrodidae), infestation on cassava (Manihot esculenta)
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Gunawardana, D. U. M.; Warnasooriya, P. G. A. S.; Hemachandra, K. S.
Spiralling whitefly, Aleurodicus dispersus Russel (Aleyrodidae) is a highly polyphagous quarantine pest, spread in tropical and subtropical region of the world. As direct feeders of cell sap whiteflies affect adversely on growth and act as vectors of viruses and spread plant diseases, of many agricultural and non-agricultural plants. This pest can be managed by the means of biological control with the use of coccinellid predators. In this process, it is necessary to make samples and assess the whitefly infestations in relation to many laboratory and field studies. In order to facilitate the assessment of whitefly populations, a study was conducted to develop a scale to measure the whitefly infestation in cassava. Whitefly infected cassava leaves were collected from cassava fields in Dholuwa-Kandy for one cropping season. Leaflets of collected leaves were separated (leaflet length 14.29 ± 0.43 cm, width 3.53 ± 0.21 cm and leaf area 57.86 ± 6.34 cm2 ) (n= 80). Each leaflet was examined separately under the binocular light microscope (10x4) and each growth stages (eggs, instar 1, instar 2, instar 3 and instar 4) of the whitefly were counted based on the four whitefly infestation levels (25%, 50%, 75% and 100%). The variation of eggs appears to have a more or less linear relationship with the area of infestation, but not the other growth stages. When total number of eggs is considered, a significant linear relationship (r2 = 87.1%, F (1, 78) = 524 p < 0.001) with infestation level was found which can be expressed as y =2.58 x +8.33. When total number of instars is considered, a significant linear relationship (r2 = 95.1%, F (1, 78) = 1521 p < 0.001) with infestation level was found which can be expressed as y =3.332 x +2.275. Eggs represented 80%, out of the total number of counted individuals. Significant relationships were observed between the area of infestation and instar 1, instar 2 and instar 3 but not with instar 4. Having considered these relationships, number of whitefly stages or the egg numbers can be predicted by examining the area of the infestation of the leaf, in this case cassava. There is a possibility, this pattern may be true for other crops but exact relationship is needed to be established, with a separate study
Assessing the substrate degradation specificity and life stage performances of black solider fly larvae (Hermetia illucens) in different bio-degradable waste substrates
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Magamage, M. P. S.; Ellawidana, D. M.; Perera, R. N. N.; Lakmini, P. K.; Priyadarshana, M. K. C.
Solid waste management has become decisive challenge in Sri Lanka where majority of the generated waste is dumped in an unsystematic way. It is highly encouraged to pursuit more reliable waste management methods in an effective way to mitigate this issue. The black solider fly (Diptera: Hermetia illucens) is a harmless insect proven for its larvae’s enormous bio-waste degradable ability and animal feed. This study intends to propose the most suitable substrate to breed the larvae by assessing substrate effect for the larval growth performance and substrate degradable specificity. Specially designed bin which facilitate brooding, aeration, leachate extraction and self-harvesting was used. As three different substrates, 100% swill (T1), 100% fish offal (T2) and rotten fruits and vegetables (T3) were used and maximum allowable height of 20 cm was marked inside the bin. Egg laying lap, eggs volume and length of egg masses, substrate consumption height, pH, average moisture % (wet/dry basis), temperature (inside /outside the substrate), length and width of different larval stages and larval proximate value (crude protein %) were recorded. During the egg laying and colonization period each bin was examined in two hours interval from 8.00 a.m. to 5.00 p.m. for two months. Once brooding initiated, new substrate was refilled by 1 kg in two day intervals. First eggs emergence sequence was recorded as T1, T2 then T3. There was no substrate dependent effect for the mean egg volume (0.97 eggs/mm3) and average egg length (895.389μm) in each bin using three replicates. The highest substrate consumption height was recorded in T1 (10.3 cm). Highest pH drop of the decaying substrates was recorded in T1 (5.82) where T2 (6.17) recorded the least pH drop of the substrate. On wet / dry basis, the highest moisture content was in T3 (20.04% and 25.06% respectively) whereas the lowest moisture level was in T2 (12.06% and13.71% respectively). The highest inner (37.1°C) and outer (30.9°C) substrate temperature was recorded in T1 and lowest value was recorded in T3. According to the larval growth performances, larval width and length were varying with respect to the larval stage. Larval crude protein % was highest in T3 (48.95%) and lowest in T1(33.06%). In conclusion, based on the mean comparison study 100% swill indicated the most favorable conditions for the larval growth whereas larvae grew in rotten fruits and vegetables were the most suitable substitute for animal feed as a protein source.
The cross-cultural adaptation of Morisky Green Levine Medication Adherence Scale for use with diagnosed patients of Ischemic Heart Disease in Sri Lanka
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Kumara, W. G. C.; De Zoysa, P.; Balasuriya, A.; Fernando, N. F. J.
Ischemic Heart Disease (IHD) has been classified as one of the major cardiovascular diseases in the world and it has become the main cause of death in Sri Lanka. Medication adherence is defined as the level to which the client's behaviour complies with the established endorsements from a health care professional. Poor medication adherence to IHD is related to increased re-hospitalization and mortality and continuous assessment of medication adherence is extremely important among these patients. Morisky Green Levine Medication Adherence Scale is a medication adherence tool comprised of four items with yes/no response which results in a score ranging from 0 to 4. The study aim was to translate Morisky Green Levine Medication Adherence Scale into Sinhala and cross-culturally adapt it to the Sri Lankan setting. Translation, back translation, and pretest were conducted prior to a Delphi process which assessed the content and consensual validity of the scale. The Delphi process included two consultant physicians, a cardiologist, a clinical psychologist, and a registered pharmacist. In consensual validity, each item was rated, on a scale of 0(total disagreement) to 9(total agreement) (i) if its conceptual meaning was retained after translation, (ii) if it was appropriate to be used with IHD patients, and (iii) if it was culturally relevant to Sri Lanka. For content validity, each item was rated on a scale of 0 to 9 (i) if each item was an appropriate indicator of its scale, and (ii) if the composite of items was adequate to measure medication adherence. The ratings received from stage one were listed and re-sent for a second round and the re-ratings were evaluated for the degree of consensus. Items for this Medication Adherence Scale’s Sinhala version were chosen based on the following criteria: (i) the item was reworded or removed if 70% or more of the re-ratings were in category 0–3. If reworded, the Delphi Process was repeated for that item, and (ii) the item was kept with no change if 70% or more of the re-ratings were in categories of 4–6 and 7–9. No items were removed from the original scale and some items were reworded according to suggestions made by the experts to retain the conceptual meaning when translated into Sinhala. The Sinhala version of the Morisky Green Levine Medication Adherence Scale can be used in research, medication adherence evaluations and IHD preventive programmes in Sri Lankan setting with confidence.
A new Sodium based electrolyte – PEO10NaBrO3
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Sankalpa, H. A. C.; Sumathipala, H. H.; Wijesundera, R. P.
The necessity of new and environmental friendly rechargeable batteries is increasing day by day due to the current technology development and power demand. Hence, efficient and low-cost new electrolyte materials have to be discovered and more attention has to be placed on searching environmental friendly, non-toxic materials. Sodium salts are the most potential materials due to their abundance and low-cost. This study focuses to investigate the electrical conductivity of a sodium-based electrolyte which can be used in solid state batteries. Composite of Poly Ethylene Oxide (PEO) and Sodium Bromate (NaBrO3) are used as the electrolyte and samples were prepared by the hot-pressed method. Electrical conductivity measurements were carried out for samples prepared by varying the molar ratio of PEO and NaBrO3. According to the results, PEO-NaBrO3 has the potential to be developed as a sodium-based electrolyte. Experimental results revealed that the highest electrical conductivity is being produced for PEO10NaBrO3 samples. Best sample exhibited 3.44×10-5 S cm-1 conductivity in room temperature (30 °C) and 2.14×10-2 S cm-1 conductivity at 100 °C. These results show the evidence of potential usage of PEO10NaBrO3 as an electrolyte in solid state Batteries. However, further investigations should be carried out to investigate the contribution of the Sodium ions for the observed conductivity
Exploiting local market as a strategy for uplifting Sri Lankan tea industry: A case of consumer buying behavior in Kegalle
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Dharmathilake, N. R. D. S.; Sivashankar, P.; Elapata, M. S.; Mahaliyanaarachchi, R. P.
Sri Lankan tea industry is not performing well in global tea market due to various imperfections. However, still enough attention is not paid to develop the local tea market. This is important in the case of drawbacks in global markets. There is a great potential to develop the local tea market with the best tea grades and value added products produced domestically as local economy and middle income consumer base is growing. This study focuses the potentials of local tea market through the lens of consumer behavior of tea. It studies the purchase decisions and buying behavior of local tea consumers in Kegalle district. About 120 respondents from two urban and two rural GN divisions were surveyed with interviewer directed questionnaires by purposive sampling. Demographic features including age, gender, living sector, education level, employment, monthly income and importance of seven pre-determined factors (quality, price, brand, package, past experience, others recommendations and the loyalty of the buying place) affecting decision making were recorded on five point Likert scales. Data on buying behavior dimensions including buying frequency, buying place, form of tea bought frequently, type of tea bought frequently and quality attributes considered when buying were also collected. Then, the consideration levels of seven pre-determined factors and buying behavior dimensions were separately analyzed against the demographic factors of the respondents by using Chi-square test and Spearman correlation test. It revealed that the local tea market can be fully exploited if the quality of tea is improved, especially the taste. The differences in buying behaviors of local tea consumers were driven by income levels and living sectors. Since the tea consumers with higher income levels are more conscious on brands, marketers must take more efforts on developing strong brand image. Also, it must be invested more on the brand promotions by supermarkets on the tea buying location. Popularity of flavored teas among local consumers found very low. Only 3.4% of the total respondents were buying flavored teas and all of them were urban dwellers. The study suggested to try out tea with special tastes at local tea shops for high end consumers and to induce tea consumption as a passion. Marketers can sell branded products to the consumers with lower income levels too, if they offer tea at lower prices. But much care should be taken when serving both market segments together as their perceptions are controversial. If the individual marketers put their maximum efforts to succeed their businesses, this will at least contribute to uplift the Sri Lankan tea industry
Development of organic inorganic hybrid water purification system
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Dikella, D. G. N. V.; Maddumaarachchi, M.
Water is one of the essential resources on earth. It is very important to protect water for the survival of all living beings. Textile industry is one of the most chemically intensive industries and a major polluter of drinking water. It generates huge quantities of complex synthetic dyes. A variety of methods have been developed for the treatment of textile waste water over recent years. However, colour removal from textile waste water by means of low cost and efficient technologies is still a major challenge. In this study, a novel organic-inorganic hybrid material was synthesized using polyacrylamide (PAM) and diatomite for efficient water purification system. Both PAM and diatomite have been studied extensively for waste water treatment separately. Series of polyacrylamide-diatomite composites (PAD) were successfully prepared through aqueous solution polymerization. The synthesized PAD composites were characterized by infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. Furthermore, the influence of PAM and diatomite content on the composite formation was investigated. The flocculation performance of PAD composite was studied in synthetic Rhodamine B dye water samples to evaluate the dye removal capacity. Among the studied compositions of PAD composites, the maximum dye removal was achieved for the PAD-4-4 which had the ratio of PAM and diatomite content of 80 wt. %:20 wt. %. The novel composite flocculant exhibited a significant capability of removing Rhodamine B than that by PAM alone. The optimum dosage of PAD composite that could make the transmittance of treated Rhodamine B dye water sample (50 cm3, 0.6 ppm) exceed 90%, was ranged from 0.2 g to 0.3 g, which was more than 25% increment of the transmittance, than that of untreated dye water sample. The dye removal by PAD composite at optimum composition can be due to the combined mechanism of two components; flocculation by PAM and adsorption on to nano-sized pores of diatomite