IRSPAS 2019
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/20453
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Item An alternative sulfur precursor for chemical bath deposition of CdS thin film(Gajanayake, G. K. U. P., De Silva, D. S. M and Atapattu, H. Y. R. (2019). An alternative sulfur precursor for chemical bath deposition of CdS thin film. 4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka. p98, 2019) Gajanayake, G. K. U. P.; De Silva, D. S. M.; Atapattu, H. Y. R.Solar energy is the most appropriate electrification method for a tropical county like Sri Lanka. At present, Sri Lanka generates more than 72% of its electricity needs at a high cost by burning coal and diesel. To overcome the major obstacle of high initial cost in installation of solar power plants, many research groups worldwide at present are focusing towards manufacture of low cost and highly efficient photovoltaic cells based on cadmium sulfide and cadmium telluride (CdS/CdTe) semiconductors. Among the range of methods available for fabrication of CdS window layer, the chemical bath deposition (CBD) is an ideal method due to its simplicity and low cost. In this study, CdS layers were deposited on the FTO glass substrate by CBD method, using an alternative sulfur precursor; ammonium thiosulfate ((NH4)2S2O3) against the well-established but costly precursor thiourea (CS(NH2)2). The CBD bath was prepared with 0.25 mol/L cadmium acetate (Cd(CH3COO)2), 1.00 mol/L ammonium acetate (NH4COOCH3), concentrated NH4OH (pH adjuster), and 0.50 mol/L (NH4)2S2O3. The best growth condition for CdS was identified by varying the parameters; Cd:S ratio, pH, deposition temperature, and deposition time while preserving a constant stirring speed. Uniform CdS layers rich in Cd, were observed in an alkaline electrolyte with Cd:S ratio of 2:5 at a temperature of 95 °C in 90 minutes. The spectrophotometric studies revealed the energy band gap of the material as 2.41 eV which is the typical value for CdS. Further, the X-ray diffractions observed at angles of 26°, 28°, 36°, and 53° representing the planes of (002), (101), (102), and (201) verified the cubic structure, while the scanning electron microscopic studies confirmed the uniform surface morphology of the material with average grains sized of 105 nm. However, the presence of pin-holes observed in the cross-sectional view implied the need of further optimization of parameters to obtain materials comparable to thiourea based chemical bath deposited CdS layers.Item Analysis of bus transport service reliability – Case Study from Gampaha bus halt for Veyangoda to Pasyala bus route (Route No -189).(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Athapaththu, A. M. P. L.; Waravita, S. H. H.; Weerasekara, T. C.; Sharic, A. H. S.The objective of this research is to measure the bus transport service reliability of a bus route at a bus halt. Three measures, Coefficient of Variation (CV), Earliness Index (EI) and Width Index (WI), were used to measure the bus service reliability of bus route 189 (Veyangoda to Pasyala) at Gampaha bus halt in weekday and weekends for different time intervals. CV is defined as the ratio of standard deviation of scheduled headway deviation and mean scheduled headway deviation of buses at the halt. Headway deviation is the difference between actual headway and scheduled headway of buses. The scheduled headway at a stop is defined as the difference between the scheduled stop times of the consecutive two buses at the same stop. Actual headway is defined as the difference between leave times of the consecutive two buses at the same stop. The EI (Earliness Index) is defined as the percentile rank of delay/headway deviation of zero. The percentile rank of a particular delay/headway deviation is the percentage of delay/headway deviations in its frequency distribution that are lower or equal to it. WI is defined as the difference between the 95th percentile of headway deviations and the 5th percentile of headway deviations divided by the average scheduled headway. The data for scheduled arrival time, scheduled leave time, actual arrival time and actual leave time of buses at Gampaha bus halt for Veyangoda to Pasyala route were collected from timekeepers for 10 days including week days, weekends and a holiday from 1st February to 10th February 2019 which consisted records of 488 buses that arrived and departed the Gampaha bus halt. Convenience sampling method was used to determine these days. Each day was divided into 4-time intervals. The time intervals were 6 a.m. – 9 a.m., 9 a.m. – 12 p.m., 12 p.m. – 3 p.m., and 3 p.m. -6 p.m. Data analysis revealed that buses operated between 9 a.m. – 12 p.m. were more reliable compared to the other buses operated in other time intervals on weekdays as the CV value was as lesser as 0.53. It was found that buses operated between 12 p.m. – 3 p.m. were more reliable compared to the other buses operated in other time intervals on weekends as the CV value was as lesser as 0.43. But buses were more unreliable between 3 p.m. -6 p.m. on both weekdays and weekends as the CV values were 1.00 and 0.78 respectively. EI analysis revealed that as large as 32% of the buses operated in between 12 p.m. – 3 p.m. on weekdays departed early and as large as 50% of the buses operated in between 3 p.m. -6 p.m. on weekends departed early. WI value was as large as 2.78 between 3 p.m. -6 p.m. while the WI value at the same stop between 9 a.m. – 12 p.m. was 1.42 on weekday. WI value was as large as 1.41 between 9 a.m. – 12 p.m. while the WI value at the same stop between 3 p.m. -6 p.m. was 0.35 on weekends. WI analysis revealed the changing pattern of service reliability in different times of the day. This research describes methods of measuring variations in bus service reliability using secondary dataItem Analysis of heavy metal levels in rice grown in CKDu effected Krambankulama in Medawachchiya, Sri Lanka(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Dilrukshi, A. A. S.; Weerasooriya, M. K. B.Chronic Kidney Disease of unknown etiology (CKDu) is a major health problem faced in agricultural areas in North Central Province, Sri Lanka. Among many different causative factors that suspects, heavy metal contamination of food is one of the major issues which can lead to the renal failures in human. Though number of studies have been reported on CKDu, exact causative factor still remains unknown. Since rice (Oryza sativa) is the staple diet in these areas, heavy metal content of rice grown in CKDu prone Karambankulama, Medawachchiya was aimed to investigate. Rice samples (n=45) were collected from 5 sites in Karambankulama and in Hettipola, Kuliyapitiya. From each site 9 samples were collected at random locations. For the comparison purpose, Hettipola was selected as negative control site. The rice samples were acid digested in a microwave digester and heavy metals were analyzed using Atomic Absorption Spectrophotometer. Cu, Cr, Pb were detected in flame mode whereas Cd was detected in furnace mode. According to the results obtained mean metal contents of rice samples were as follows. Cu- 0.864±0.090 mg/kg, Cr- 0.903±0.020 mg/kg, Pb- 0.144±0.010 mg/kg and Cd-0.089±0.003 mg/kg for the samples collected from Karambankulama and Cu- 0.804±0.050 mg/kg, Cr- 0.895±0.010 mg/kg , Pb- 0.133±0.001 mg/kg and Cd- 0.061±0.001 mg/kg for the samples from Kuliyapitiya. There were significant difference (p<0.05) of the mean levels of Cu, Pb and Cd in rice between Karambankulama and Hettipola while there was no significant difference (p>0.05) with respect to the mean levels of Cr. To assess the safety of dietary intake, weekly intake of Cu, Cr, Pb and Cd in rice samples were calculated separately based on the daily consumption of rice and compared with the Provisional Tolerable Weekly Intake (PTWI) established by the WHO/FAO. The results indicated that weekly intake of Cr was higher for ages between 4-5 years and 14 years for both sites and that of Cd was higher for ages between 4-5 years in Karambankulama than the maximum weekly intake levels recommended by WHO/FAO. During the survey 12 CKDu patients were recorded in Karambankulama whereas none was recorded in Hettipola. Hence, Cd accumulation in the body over long period of time could be one of the causes for the present increase in chronic renal failure in the North Central province.Item Analysis of queuing behaviour in commercial banks: a case study(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Rambandara, R. D. S. S.; Hansani, W. A. D. I.; Arachchige, K. G. B.; Rasanjana, K. A. N.; Sonali, A. L. D. D.Studying queuing behaviour has become a widely explored research area at the time. The practical scenario of waiting lines must be daily experienced by almost everyone. Banking services are foremost among the places where queues are formed. Proper management of banking queues is enhanced for improving customer satisfaction. This study was undertaken with the aim of reducing customer waiting time in a preferred commercial bank of Sri Lanka. The bank had two counters, thus two queues were experienced enabling the system to behave as a multi-server queueing system with limited waiting room capacity and unlimited population size. The system was observed for two hours during two consecutive weekdays. The sample comprised 150 observations on customer arrivals to the queues, arrivals to the counters and departures from the counters. The system was modelled using the student version of Rockwell ARENA 14.5. The study assumed customer arrivals were random and independent, there was no idle time for the counters and the customers were served on first-in-first-out basis. ARENA Input Analyser recorded the probability distributions of inter-arrival rates for queue 1 and queue 2 to follow Gamma and Exponential distributions while corresponding service rates followed Weibull and Normal distributions. The model was run for a replication length of one hour. The waiting times of customers in two queues were observed to be 10.48 and 2.51 minutes. The system permitted 57 customers into the bank and 42 were served and sent out recording a performance rate of 73.68%. Higher waiting times stimulated the necessity of improving the performance of the counters. Thus the quantity of the allocated resources was reformed to conclude an optimal result. When the number of resources was changed separately, the total time spent in the system was decreasing, but several waiting times recorded higher values than the current system. Consequently, the resources of both counters were changed at once resulting no waiting time in queue 1 and 0.22 minutes in queue 2. Further, the total waiting time in the system was observed as 2.79 minutes. Moreover, the system served 54 out of 57 customers. This recorded a performance rate of 94.74% which is more feasible than the current system. Thus the study proved that the bank can eliminate excessive waiting times of customers and improve its efficiency through proper utilization of resourcesItem Analyzing Outpatient Department Performance using ARENA Simulation: A Case Study(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Dilanthi., M. G. S.; Madhushan, W. A. P.; Ranathunga, R. A. R. Y.; Wijesiri, M. K. N. A.; Rathnayaka, R. M. H. P.Many public hospitals in Sri Lanka are becoming overcrowded and creating long waiting queues at their outpatient departments. Thus, they have faced the challenge of managing patients at their public health clinics and providing an effective service. Also, the patients become frustrated and make many complaints on the dissatisfied service. Therefore, this study identified the problem of unnecessary queuing in the selected public hospital. The investigations were done aiming to improve the performance of the department through probable solutions. Though the observed hospital had assigned eight doctors in the outpatient department, this study selected only two doctors considering the convenience of data collection. Then, the model was analyzed as a multi-server queuing system with infinite waiting room capacity and infinite population. The observations were recorded for patients’ arrivals to the queues at ticketing counter and service provisions of the two doctors in a one hour period of each for two days. The sample included 150 patients. Then the system was modeled using the student version of Rockwell ARENA 14.5. Moreover, the assumptions were made on arrivals to be random and independent. The service discipline was considered as First-In-First-Out. The Input Analyzer showed BETA distribution for all inter arrivals and service provisions. These results were used to define the modules chosen from both basic process and advanced transfer panels of ARENA. The model was simulated and obtained results for the respective average waiting times of patients in the queues at the ticketing counter, doctor 1 and doctor 2 as 4.82, 34.99 and 26.82 minutes. Furthermore, those values for the patients in the system were correspondingly 90.29, 104.97 and 182.22 minutes. Thus, the problem identified in the study was evident in the selected system emphasizing the necessity of improving the performance of the outpatient department. The study suggested to double the resources in the ticketing counter. The proposed model was then simulated and obtained reduced waiting times in the queues at ticketing counter, doctor 1 and doctor 2 respectively to be 0.64, 26.73 and 14.52 minutes. Further, the resource utilizations could be increased by 24%, 5% and 12% respectively to the above three observations. Therefore, the proposed model can be implemented in the outpatient department of the selected hospital to further improve its performance considering the financial feasibilityItem Antimicrobial activity of dried fruit rind extract of Garcinia zeylanica(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Sudesh, A. D. H.; Wanigasekara, D. N.; Karunarathne, E. D. C.Emergence of antibiotic resistance among pathogenic microorganisms has become a severe threat in the medical field. Therefore, search for potential antimicrobial agents, such as substances from medicinal plants with alternative modes of action, is of major interest. Garcinia zeylanica, which is an endemic plant to Sri Lanka, is mainly used as a culinary herb. Antimicrobial activity of G. zeylanica dried fruit rind extract was evaluated against five bacterial strains and a yeast using Agar well-diffusion method. The study was aimed to investigate any potential antimicrobial effect of the fruit rind extract comparatively with conventional antibiotics. Commercially available dried rinds of G. zeylanica were collected and methanolic extract was prepared using Soxhlet method followed by solvent evaporation. Turbidity adjusted (McFarland 0.5), log phase cultures of Methicillin Resistant Staphylococcus aureus (MRSA), Methicillin Sensitive Staphylococcus aureus (MSSA), Escherichia coli (ATCC 25922), Staphylococcus pyogenes (ATCC 19615) and Pseudomonas aeruginosa (ATCC 27853) were evenly inoculated as a uniform lawn on Mueller Hinton Agar plates, while Candida albicans was swabbed to obtain an even lawn on Sabouraud Dextrose Agar . Three wells of 8 mm diameter per each plate were made for positive control, negative control and for the test extract. Amoxicillin was used as the positive control for MRSA, MSSA, E.coli and S. pyogenes and Ciprofloxacin was used so for P. aeruginosa. Fluconazole was the positive control for C. albicans. Sterile distilled water was used as the negative control. The test was triplicated for each strain. After 24 hour incubation at 37ºC, all the bacterial strains and the yeast were found to be susceptible to the dried rind extract of G. zeylanica. The mean inhibition zone diameters of the test extract for MRSA, MSSA, E.coli, S. pyogenes, P. aeruginosa and C. albicans were 29.33 mm, 28.67 mm, 20.67 mm, 31.00 mm, 24.00 mm and 25.67 mm respectively when the average inhibition zone diameters of the standard antibiotics were 11.67 mm, 39.33 mm, 29.67 mm, 37.67 mm, 38.67 mm and 27.67 mm accordingly. This study concludes that G. zeylanica dried fruit rind extract exerts a significant antimicrobial activity against the bacterial strains and the yeast strain testedItem Antioxidant activity and physicochemical properties of Flacourtia indica (Uguressa) at different maturity stages(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Kasunmala, I. G. G.; Navarathne, S. B.; Wickramasinghe, I.Flacourta indica is an underutilized fruit, which grows wild in bush and its fruits are generally consumed fresh at fully matured and ripe stages. Physicochemical, antioxidant and sensory properties of fruits shows a significant different between each maturity stage. The aim of this study was to analyze the physicochemical and antioxidant properties of fruits at different maturity stages and to identify the best maturity stage for harvesting. Fruits were collected from Galle, Sri Lanka and three maturity stages were selected according to the progressive colour change during fruit development, such as immature – fully green in colour, mature - purple and green in colour and ripen – dark purple in colour. Fruits at each maturity stage were randomly divided into two subgroups for antioxidant analysis and physiochemical testing. Antioxidant analysis was performed on freeze dried fruit samples. Results revealed that weight, volume, length, width, total soluble solids and moisture content of fruits were increased while decreasing pH significantly (P < 0.05) with the maturation and ripening of the fruit. Color of the fruits in terms of lightness (L*) and yellowness (b*) decreased significantly (P < 0.05) while increasing the redness (a*) with maturity. According to antioxidant activity analysis, total phenol content (TPC) value (3.731 ± 0.20 mg gallic acid equivalents/g of dry powder) by Folin-Ciocalteu method showed no significant difference between immature and ripen stages but showed a slight increment in mature stage. 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, ferric reducing antioxidant power (FRAP) and Oxygen radical absorbance capacity (ORAC) values increased with the maturation and ripening of Flacourtia indica fruit. The study also revealed that dark purple (fully ripen) fruits contained significantly high amount of antioxidant activity in terms of, DPPH, FRAP, ORAC values which were 2280.701 ± 53.05 ppm, 141.775 ± 2.04 mg trolox equivalents/g of dry powder, 31.376 ± 1.35 mg trolox equivalents /g of dry powder respectively. Based on results it can be concluded that fully ripening stage was the best maturity stage for harvesting and can be used as a natural antioxidant in food industryItem Assessing neurotoxic potential of titanium dioxide nanoparticles and bulk form using the fish model, Nile tilapia (Oreochromis niloticus)(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Samanthika, A.L.C.; Pathiratne, A.Titanium dioxide nanoparticles (nano TiO2) and bulk TiO2 are widely used worldwide in various sectors. Hence they can be released inevitably into the inland water bodies posing health threats to the aquatic ecosystems. Cholinesterase (ChE) activity can be used as a biomarker for screening neurotoxicity in organisms exposed to the environmental contaminants. The objective of the present study was to evaluate the neurotoxic potential of environmentally relevant concentrations of nano and bulk TiO2 using Nile tilapia as the tropical fish model. Groups of fish which had been acclimated to the laboratory conditions for two weeks were exposed continuously to relatively low concentrations (50 and 100 μg/L) of nano or bulk TiO2 for 7 or 14 days (n= 7). The control fish were exposed only to aged tap water. The experimental design also included 7 day nano or bulk TiO2 exposure groups which had been transferred to aged tap water for another 7 days to evaluate potential recovery of the toxicity. Neurotoxic potential was assessed using ChE activity measurements in the brain, gill and liver tissues by a standard spectrophotometric method. ChE activities (mean±SEM in nmol/min/mg protein) in gills were elevated significantly(P <0.05) in the fish exposed to 50 and 100 μg/L bulk TiO2 for 7 days (102±9 and 105±7 respectively) compared to those of the control fish (71 ± 5) whereas brain ChE activities were not affected. Liver ChE activities were significantly elevated at 100 μg/L continuous exposure to bulk TiO2 for 7 and 14 days (279±15 and 315±15 nmol/min/mg protein respectively) compared to those of the control fish (155±12) and were not restored to normal levels after 7 days post exposure. A consistent ChE activity stimulation pattern was not evident with respect to bulk and nanoTiO2 exposures. In the fish exposed to both concentrations of nano TiO2, ChE activities in brain and gill tissues were not significantly different from those of the control fish. However ChE activity in liver tissues of the fish exposed to 100 μg/L of nano TiO2 was elevated significantly (P < 0.05) at 7 days exposure and post exposure periods. The results revealed that environmentally relevant concentrations of nano and bulk TiO2 may pose neurotoxic risks to the fish populations inhabiting the contaminated water bodies and the bulk form of TiO2 is not ecotoxicologically inert as previously assumedItem 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.Item 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 plantsItem Assessment of in vitro antioxidant activity and flavonoid content Vernonia cinerea(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Weerasinghe, P.; Abeysinghe, T.; Paranagama, P. A.Leafy greens are an essential part of a healthy diet. Eating a diet rich in leafy greens can offer numerous health benefits including reduced risk of obesity, heart diseases, high blood pressure and mental decline. In Sri Lanka, Kola kanda or herbal porridge is a traditional breakfast made up of green leaves or herbs. Out of many herbs used for Kola kanda, Vernonia cinerea (Monarakudumbiya) is used to treat various diseases on folklore levels in Sri Lanka. However, no much scientific validation is found for V. cinerea for its medicinal uses. The present study was carried out to access the in vitro antioxidant activities and flavonoid content of leaf, root, stem and flower parts of V. cinerea. In vitro antioxidant potential of methanolic extracts of V. cinerea was evaluated by means of total phenolics by the Folin-Ciocalteu assay and the DPPH radical scavenging assay using standard procedures with slight modifications. The highest phenolic content of 101.80 ± 7.74 mg GAE/g was observed in flowers and the stem having the least phenolic content (71.95 ± 5.72 mg GAE/g). The flavonoid content ranged from 17.67 mg GAE/g to 12.76 mg GAE/g in all parts. DPPH radical scavenging activity of extracts of V. cinerea increased in a dose dependent manner with IC50 values ranging from 800 μg/mL to 2350 μg/mL in different parts. The leafy green, V. cinerea under this study contains a significant amount of essential phytochemicals which possess anti-oxidant properties supporting its use as a medicinal herb.Item Assessment of selected biochemical parameters in a hybrid population of tea to predict the quality of processed tea(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Abeysekara, R. M. U. N.; Kottawa-Arachchi, J. D.; Ranathunga, M. A. B.; Amarakoon, A. M. T.Tea is made from the processed leaves of the mature tea plant, Camellia sinensis L. It is one of the most popular beverages in the world. Tea breeding programs constantly attempt to improve the yield and quality of tea by producing new cultivars. Biochemical and molecular markers are frequently used to assist the conventional tea breeding techniques. Chlorophyll a, b, total chlorophyll, carotenoids and total polyphenol content in tea leaves can be used as biochemical markers to predict the quality of processed tea. In this study, young shoots of 112 individuals from a hybrid progeny which was derived from TRI 2043 and TRI 3055 through controlled hybridization in Tea Research Institute of Sri Lanka were analyzed for chlorophyll a, b, total chlorophyll and carotenoid content. 102 individuals from the hybrid population were analyzed for total polyphenol content. Acetone (80%) extraction was used for the analysis of pigments and methanol (70%) extraction was used for the analysis of total polyphenol. Spectrophotometry (absorbance at 470 nm, 646 nm, 663 nm and 765 nm for chlorophyll a, b, carotenoids and total polyphenol respectively) was used with relevant standards for quantification. Statistical analysis (Minitab16 to determine frequency distributions using histograms and boxplots, SAS 9.1 to prepare dendrogram in cluster analysis) of the results had shown wide segregation of the measured parameters and some of the off springs had recorded higher values than the parents. According to the results, highest chlorophyll a content were recorded in accessions 134, 16 and 67 (3.25 mg/g, 3.10 mg/g and 2.92 mg/g respectively) and chlorophyll b in accessions 134, 16 and 67 were also higher than the others in the population (1.21 mg/g, 1.13 mg/g and 1.02 mg/g respectively). The total chlorophyll content in accessions 134, 16 and 67 were recorded as 4.46 mg/g, 4.23 mg/g and 3.95 mg/g respectively. Carotenoid content in accessions 77, 98 and 36 were higher than the others in the population (2.46 mg/g, 1.63 mg/g and 1.10 mg/g respectively). The highest total polyphenol content (33.13%) was recorded in parent TRI 3055. Total polyphenol contents in accessions 94, 72, 95, 92 and 102 were higher than the rest of the progeny (32.51%, 31.33%, 31.10%, 30.87% and 30.28%). Measured parameters of the hybrid population were subjected to cluster analysis. The resultant dendrogram clearly categorized the progeny into four clusters. Accessions with higher chlorophyll, carotenoid and polyphenol contents (accessions 150, 52, 35,134 and 16) could be candidates for the development of new cultivars with better quality teaItem Assessment of spatial variation of ground water quality in Colombo district, Sri Lanka(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Antalyn, B.; Weerasinghe, V. P. A.In Sri Lanka, groundwater resources are widely used for domestic, commercial and industrial purposes and the demand for ground water is steadily increasing, particularly for urban & rural domestic water supplies, irrigated agriculture and in the industrial sector. This rapid increase in demand and lack of management is exerting considerable pressure on the available groundwater resources. Therefore, it’s vital to monitor the quality of ground water for sustainable utilization. For ground water quality assessment, Colombo district was selected as the study area since it is urbanized rapidly in last decades. The main aim of the study was assessing spatial variation of ground water quality in Colombo district in year 2018. Some of the physicochemical parameters were selected namely pH, temperature, conductivity, total dissolved solids, salinity, COD, hardness, total phosphate, nitrate-N, DO and BOD5. Sampling was carried out during the south western monsoon from June 2018 to September 2018. With the availability 03 open wells were selected randomly, from each Divisional Secretary Division (DSD) and water samples were collected during the morning hours in between 0-3 m depths as 03 replicates from each well at once. Total 39 open well samples were tested using standard methods. The obtained results are compared with proposed ambient water quality standards for inland waters in Sri Lanka by the Central Environmental Authority (CEA). The results reveal that in most of the sites pH, COD and BOD5 are not meeting the standards. Lower pH levels can occur due to natural acidification as well as anthropogenic causes linked to the industrialization, atmospheric emissions or cultivation. Results of PCA analysis reveal that the sites which are surrounded with agricultural areas such as in Hanwella, Padukka, Homagama, Kaduwela, and Kesbewa showed higher nitrate-N, total phosphate levels and low pH values. In contrast higher pH values as well as low nitrate-N and total phosphate levels were observed in non-agricultural areas. Hence come to a conclusion that long-term agricultural practices may have acidified the ground water and elevated organic matter accumulation due to high urban runoff, sewage seepage from slums and poor maintenance of wells could have caused higher COD, BOD5 levels in urbanized areas such as in Thimbirigasyaya, Moratuwa, Dehiwala, and Kotte. The study of physicochemical characteristics of this ground water samples suggests that the evaluation of water quality parameters as well as water quality management practices should be carried out to protect the water resources. Unless the use of surface area is managed in a sustainable way, it will have adverse repercussions on the environmentItem Association between backache related quality of life and serum creatinine in Chronic Kidney Disease of unknown aetiology (CKDu) patients in the North Central Province, Sri Lanka(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Aslam, F.; Hakmanage, N. M.; Suriyakumara, V.; Sandaruwan, L.; Kumarasinghe, N.Chronic kidney disease of unknown aetiology (CKDu) is a slow progressive disease that cannot be detected until the later stages. This is commonly described among the agricultural communities in Sri Lanka. CKDu has been a burden over the past two decades and mainly affects the North Central province. This disease is spreading towards the Southern, North Western and Central provinces. CKDu is staged using the estimated-glomerular filtration rate (e-GFR) which is the standard test performed under the WHO guidelines using serum creatinine (SCr) measurement. Backache has been identified as a common symptom among patients suffering from any form of CKDu. It is postulated that backache can be used as an indirect measure to gain an insight about the patients’ health status. The pain measurement also allows an overall assessment of the individuals’ quality of life affecting activities of daily living and which can be used to measure total outcome of the disease. Using an interviewer-based questionnaire, backache was assessed among patients with CKDu. Roland-Morris low back pain and disability questionnaire (RMQ) was used, which had 24 questions and given scores ranging from 0-24. In addition to RMQ, five questions related to the body and pain derived from the KDQOL questionnaire (a standard tool used to determine quality of life (QOL) in kidney disease affected patients) was also used. The scores were combined and evaluated into four main types of backaches: no backache, intermittent, nociceptive and neuropathic backache. The questionnaire was categorized into four variables Correlation statistics were applied to determine the relationship between backache and SCr values in CKDu. IBM SPSS version 23 was used for the statistical analysis. Based on results, a predictive model was designed to understand the correlation between the severity of backache and serum creatinine in CKDu patients. A sample of 75 patients with CKDu were included in the analysis. R-square of 80.9% was observed only in RMQ model. The ANOVA test reported how well the regression equation fits the data. There was a positive relationship between SCr and severity of backache (p<0.001). Using the available findings, a predictive model was designed to understand the severity of backache with serum creatinine in CKDu patients. This may be used in early interventions to improve QOL. However, future studies and larger sample size are required to establish these findingsItem Bacterial degradation of tetracycline (TET) by TET resistant bacteria; A green solution for antibiotic pollution.(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Liyanage, G. Y.; Manage, P.M.Tetracyclines (TET) have been extensively used in aquaculture for chemotherapy against various fish diseases such as fin rot, skin ulcers. Overuse and misuse of antibiotics are widely regarded as two of the major factors promoting antibiotic resistance. Resistance to TET occurs via two primary mechanisms; ribosomal protection and enzyme inactivation. To minimize the development of resistance, excess amount of TET should be removed from the aquatic environment. Therefore, studies on the biodegradability of TET can be taken as a very first step of an environmental risk assessment. The present study reports the biodegradation of TET by Enterobacter sp., Micrococcus luteus, Enterobacter ludwigii, Bacillus sp. and Streptomyces sp., which were isolated as TET resistance, non-pathogenic bacteria. In a previous study, TET resistant bacterial isolates were identified using the 16s rRNA sequencing. Overnight bacterial cultures grown in a medium without TET, were introduced into a medium containing TET at final concentration of 5 μg/ml. Triplicate samples were incubated at 28 °C with shaking at 100 rpm under dark conditions. Subsamples (0.5 ml) were removed at 2 days interval for a period of 14 days. Remaining TET in the subsamples was analyzed using High Performance Liquid Chromatography (HPLC). Complete degradation of TET by M. luteus and E. ludwigii was detected at the end of 14 days of incubation. Descending degradation percentages were followed by Enterobacter sp. (74%), Streptomyces sp. (72%) and Bacillus sp. (70%) at 14 days, respectively. Lowest half-life time of TET was shown by M. luteus and E. ludwigii (6 days), whereas half-life time of 8 days, 11 days and 12 days were recorded for Enterobacter sp, Streptomyces sp. and Bacillus sp., respectively. According to the degradation results obtained, it can be concluded that the selected bacterial strains can be used as potential candidates to be introduced into wastewater effluents to remove TET in effluent water, before reaching natural environmentsItem Bacterial enzyme-mediated synthesis of silver nanoparticles and antimicrobial activity(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Peiris, M. M. K.; Gunasekara, T. D. C. P.; Jayaweera, P. M.; Fernando, S. S. N.Extracellular synthesis of silver nanoparticles (AgNPs) using bacteria has been explored for their unique physicochemical properties. Studies have shown that nitrate reductase enzyme catalyzes the bioreduction of Ag+ to Ag0 and formation of AgNPs. The objective of this study was to detect the presence/absence of nitrate reductase enzyme in selected bacteria and to study the formation of AgNPs. The antimicrobial activity of the biosynthesized AgNPs was also examined. Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Acinetobacter baumannii (confirmed clinical strain) and Staphylococcus aureus ATCC 25923 were cultured in Nutrient broth. After 72 h of incubation, AgNO3 was added into the culture supernatant. AgNP formation was confirmed by Energy Dispersive X-ray analysis (EDX) and Transmission Electron Microscopy (TEM). For the nitrate reductase assay, heavy inocula of the above selected bacteria were inoculated in Nitrate broth and incubated at 37°C for 24 h. One dropper full of sulfanilic acid and α-naphthylamine were added to each tube and the colour change was observed. If no color change was observed a small amount of zinc (Zn) powder was added and the color change was observed. Well-diffusion method was performed to study the antimicrobial activity of the synthesized AgNPs against E. coli ATCC 25922, S. aureus ATCC 25923, P. aeruginosa ATCC 27853, Candida albicans ATCC 10231 and selected clinical isolates of P. aeruginosa, S. aureus and C. albicans. Positive controls were 0.5% AgNO3 and chemically synthesized AgNPs (0.436 mg/ml). All biosynthesized AgNPs were spherical in shape. The average sizes of the NPs were 11.14 ± 6.59 nm (S. aureus-NPs 0.435 mg/ml), 11.71 ± 2.73 nm (P. aeruginosa-NPs 0.45 mg/ml), 12.87 ± 2.95 nm (E. coli-NPs 0.99 mg/ml) and 12.22 ± 2.45 nm (A. baumannii-NPs 0.665 mg/ml). In general, zones of inhibition (ZOIs) given for chemically synthesized AgNPs, were higher than biosynthesized NPs. According to the well diffusion results, AgNPs produced by S. aureus resulted in the largest ZOI against the selected pathogens. Biosynthesized AgNPs were highly effective against Gram negative bacteria compared to Gram positive bacterial and fungal species, as well as Candida albicans, which were opportunistic pathogens. A. baumannii, E. coli and S.aureus, except P. aeruginosa, gave red colour after adding the two reagents and when Zn dust was added to P. aeruginosa, no colour change was observed. AgNP synthesis with a narrow size distribution was observed for all tested bacterial strains. AgNPs of S. aureus gave highest ZOI. Nitrate reduction was observed with all organisms. Further characterization of NPs is required to study the physical properties of silver NPsItem Bench scale fixed-bed column adsorption studies and adsorption modelling: removal of methylene blue from aqueous solutions using glutaraldehyde cross - linked chitosan beads(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Amarasooriya, M. P. N. A.; Rajapakse, C. S. K.As dye-containing waste effluent is a big threat not only to the environment, but also to human life and the economical removal of dyes from wastewater has become an environmental challenge in nowadays. Therefore, this work focuses on the exploration of potential of using physically and chemically modified chitosan, glutaraldehyde cross-linked chitosan beads (GCLCBs) to remove a model dye, methylene blue (MB) from aqueous solutions using bench-scale fixed bed columns. GCLCBs (4.00±0.02 mm in diameter) were prepared by using glutaraldehyde as the cross-linking agent and it was characterized by Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR). FTIR analyses confirmed the cross-linking of chitosan beads with glutaraldehyde. The effects of initial MB concentration (10, 12, 15 mg/L) and inlet flow rate (5, 10, 15 mL/min) at neutral pH and at room temperature (30 ± 2 ºC) on the performance of column packed with GCLCBs were analysed using breakthrough curves. The breakthrough time (Tb), time required for full bed exhaustion (Tt), bed capacity (BC) and length of unused bed (LUB) were determined at each column operating conditions. The highest % MB removal of 72.80% was obtained at initial MB concentration of 10 mg/L and inlet flow rate of 5 mL/min at 6 cm bed height of the adsorbent. The breakthrough time, Tb increased with decreasing inlet flow rate and initial MB concentration. Two kinetic models namely the Thomas model and Yoon – Nelson model were used to predict the column performance and column parameters important in designing large-scale columns in water purification systems. The results revealed that the Thomas rate constant decreased with increasing initial adsorbate concentration and inlet flow rate. The time required to achieve 50% of adsorbate breakthrough (τ) seems to agree quite well with the experimental data (τ experimental) according to the results obtained from Yoon – Nelson model. Both the Thomas and Yoon – Nelson models fitted the experimental data with high regression coefficient values (R2 ~ 1) indicating the validity of both kinetic models for the studied column system. Based on the results it can be concluded that that the GCLCBs could be used as low-cost and environmentally friendly agent for the treatment of dye containing wastewaterItem Bioactive properties of Rambutan (Nephelium lappaceum L.) and Durian (Durio zibethinus Murr.) peel extracts(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Silva, A.G.; Wickramaarachchi, S.; Attanayake, R. N.; Rajapakse, C. S. K.Although these fruits are seasonal, a considerable amount of Rambutan (Nephelium lappaceum L.) and Durian (Durio zibethinus Murr.) fruit residues (mainly peels) are collected each year as waste materials, due to the significant volume of trade of these fruits. Therefore, present work was initiated with the aim of evaluating the impact of these residues lying as waste and possible re-use, by investigating the bioactive properties in peels of rambutan and durian. Methanol extracts of Rambutan and Durian peels were sequentially extracted with hexane, chloroform and methanol. First, methanol extracts of peels were subjected to phytochemical screening following standard procedures and results revealed that rambutan and durian peels were rich in polyphenols, flavonoids, steroids, coumarin, etc. Total phenolic content (TPC) and total flavonoid content (TFC) of methanol extracts of peels were determined using Folin-Ciocalteu and aluminium chloride method, respectively. Results showed that TPC and TFC in methanol extract of durian peels were (11.39 ± 0.49 mg GAE/g dry weight, 257.20 ± 5.14 mg Catechin /g dry weight) higher than those of Rambutan peels (2.73 ± 0.15 mg GAE/g dry weight, 198.00 ± 1.89 mg Catechin /g dry weight). Further, the antioxidant activity of methanol extracts of peels and its fractions were investigated using 1, 1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging assay and the correlation with their TPC and TFC were examined using Pearson’s correlation analysis. The strongest antioxidant activity was observed in hexane fraction of Rambutan peels with IC50 value of 13.49 ± 0.52 μg/mL, and which was lower than that of the control, butylated hydroxytoluene (43.70 ± 0.89 μg/mL). Significant positive correlations were observed between TPC and TFC in fractions of rambutan and durian peels with their DPPH radical scavenging activity indicating that phenolics and flavonoids in rambutan and durian peels may contribute to their strong antioxidant activities. The antimicrobial activity of the extracts of peels and its fractions were assessed by using disc diffusion method against a bacterial species of Staphylococcus aureus and fungal species, Fusarium oxyporum and Aspergillus flavus. The lowest concentration of methanolic extract of durian and rambutan peels that showed an inhibition against Staphylococcus aureus was 31.25 μg/mL. It was also found out that neither peels of rambutan nor durian had antifungal activity against the two selected fungal species. Results revealed that the peels of rambutan and durian are potential sources of antioxidants and antibacterial agentsItem A business analytical model to analyse customer churn in mobile telecommunication industry in Sri Lanka(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Ruwanika, D.; Mascrenghe, M. A.It is much important to an organization to identify the most affecting factors to lose their customers. This is a specific and practical problem for the group of organizations in telecommunication industry in all over the world. A mechanism should be implemented to early detection of the customer churn and prevention from the same. Attracting new customers is lot more difficult and expensive than retaining the existing customers, as it is well known. Most of the Telco service providers are concerned on customer retention, because most of the service industries founded on customer subscriptions, because network providing companies commonly depend on economies of scale and require a large number of customers to share the fixed costs. The primary objective of the study is to build a business analytical model to analyze and predict customer churn in mobile telecommunication industry in Sri Lanka. In order to do that the factors affecting for customer churn between networks has been focused. Researcher has identified five most influential factors which will impact on the consumer behavior in mobile market after a comprehensive literature review. Two models were derived for final test and evaluation; Binary logistic regression with accuracy of 95.8% and Naïve Bayes with accuracy of 92.7%. The model with the highest prediction accuracy rate has been selected as the final model to predict the customer churn possibility. Following a positivist methodology, the conceptual model was built and was verified by a survey. The answers were analyzed using traditional statistical techniques and state of the art business analytical – IT algorithms. It was found that there is no significant relationship between service quality, technology changes and customer churn, as the significant level of the above variables were higher than 0.1. Three factors; Price, inconvenience and influence have been identified as significant for customer churn between networks. Existed knowledge on the significance of churning factors has been extended from the current study. Customer churn should be addressed and treated as an important concern in the decision-making process since including the previous studies the current study found it held significant. The current study has contributed to filling the gap of analyzing customer churn in Telco industry in Sri Lanka and built a statistical model to predict customer churn which can be used by the mobile service providers.Item Changes in chemical composition of Vateria copallifera (Hal) seeds during the traditional debittering process(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Mihiranie, M. K. S.; Jayasinghe, J. M. J. K.; Wanasundara, J. P. D.; Jayasinghe, C. V. L.Vateria Copallifera is a valuable endemic herbal plant which belongs to the family of Dipterocarpaceae. Usage of Hal bark is abundant as a natural preservative and debittered Hal seeds are utilized for food processing as a healthy food source. Since Hal seeds contain a bitter taste, the traditional practice of removing the bitter taste is, packing scraped seeds in a jute bag and then placing the bag in a running water stream for at least overnight. Therefore, in this study changes of chemical composition occurred during the traditional debittering process was investigated. Freshly scraped Hal seeds were packed in jute bags and placed it in an artificially formulated running water stream (Stream velocity was 69.16 ml/sec) for 12 hours. Freshly scraped Hal seeds and de-bittered Hal seeds were used for the analysis of chemical composition. Standard methods were used to determine moisture content, carbohydrate content, total mineral content, protein content, fat content and crude fiber content. Changes in minerals, fatty acids, starch, sugars were determined by using, ICP-OES, GC-MS, spectrophotometry and HPLC methods respectively. According to the results, reduction percentages of carbohydrate content, ash content, fat content and crude fiber content were (15.5%), (0.84%),(1.07 %) and (0.92 %) respectively during the traditional de-bittering process. However, no change in protein content (4.025±2.89 g/100g) in between de-bittered and fresh Hal seeds was assessed. Results of the fatty acid profile showed that, fresh Hal seeds contain mainly, oleic acid (36.93%) and palmitic acid (29.74 %) and they were reduced up to 31.56 % and 20.10 % respectively during the de-bittering process. Total starch content was reduced by 0.09 % and amylose content was reduced by the same percentage. Only Sucrose (0.7%) was determined by HPLC in fresh Hal seeds and none of the sugars were detected in the de-bittered Hal seeds. Mineral contents (K, Ca, Mg) have fluctuated while Potassium content was significantly decreased during the debittering process. However, results revealed that, there was a significant reduction on the chemical composition of Hal seeds during the traditional practice of debittering process