IRSPAS 2017

Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/18078

Browse

Now showing 1 - 20 of 134

Occurrence of dengue vectors in school premises in Gampaha District, Sri Lanka.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Radhika, N.M.L.; Gunathilaka, P.A.D.H.N.; Kasturiratne, A.; Abeyewickreme, W.
Aedes aegypti and Aedes albopictus are the vectors responsible for the transmission of dengue virus in Sri Lanka. During the past decade, Gampaha district has been ranked the second on the number of reported dengue cases. Ae. aegypti is considered as the primary vector of dengue. Previous studies conducted in the Gampaha district have highlighted that high number of breeding habitats of dengue vectors are common among school premises. The present study was carried out over a period of seven months (June to December 2016) in order to identify the species of dengue vectors inhabiting selected school premises in Gampaha district. In this cross sectional study, 60 schools were randomly selected, representing four educational zones comprising 15 schools from each educational zone namely Gampaha, Minuwangoda, Kelaniya and Negombo. Samples were collected using standard dipping and siphoning methods depending on the nature of the breeding habitat. Developmental stages of dengue vectors were recorded and larval stages of III and IV instar were directly identified using a light microscope, while I and II instars were supplemented with larval food and reared up to III instar in confined cages. The adults emerged were identified under a dissecting microscope. The larvae of Aedes mosquitoes were observed at 28 schools (46.7%) of the sixty schools surveyed. Of them, 26 school premises in Gampaha, Minuwangoda and Kelaniya educational zones were positive only for Ae. albopictus. This predominating Ae. albopictus was identified from the school premises belonging to Gampaha (10%; n=6), Minuwangoda (11.66%; n=7), Kelaniya (15%; n=9), and Negombo (6.66%; n=4) educational zones. The total number of water holding containers found in school premises inhabited by Ae. albopictus was 39 (95.12%) while Ae. aegypti was found only from two containers (coconut husk, drain) collected from two urban schools situated in Negombo area (4.88%). From the schools surveyed, discarded water holding containers were the most abundant artificial breeding habitat of Ae. albopictus (69.23%) while water holding leaf axils of banana plants were the most abundant natural breeding habitat (20.51%; n=7). Ae. albopictus, was found as the predominant dengue vector within suburban school premises in Gampaha district along with Ae. aegypti in urban school premises. Therefore, school premises should be maintained clean and dry to prevent further spread of dengue vectors among schools in Gampaha district.
Development and characterization of a slow release fertilizer system using ammonium nitrate incorporated Gliricidia bark particles.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Premaratne, W.A.P.J.; Thisera, P.A.U.D.
Best management practices for fertilizers in the application of plant nutrients should always aim to avoid a surplus of plant available nutrients in the soil. This will promote the efficient use of nutrients and minimize unfavorable effects on the environment. These conditions could be achieved by using slow release fertilizer systems. Experiments were conducted to determine the nitrogen (N), phosphorous (P) and potassium (K) contents in leaf, mid rib, root, bark and stem of gliricidia (Gliricidia sepium) plant and to develop a new slow release fertilizer system using ammonium nitrate (NH4NO3) incorporated gliricidia bark particles. Gliricidia plants were obtained from Rathmalagara estate, Madampe in Coconut Research Institute (CRI), Sri Lanka. New slow release fertilizer system was prepared from gliricidia bark particles (< 5 mm) after treating with a saturated solution of ammonium nitrate (NH4NO3). The morphology and physicochemical parameters of treated gliricidia bark particles were investigated. The release patterns of nitrogen from ammonium nitrate incorporated gliricidia bark particles (10 g) in a soil matrix (200 g) were investigated using columns with deionized water (pH 6.7). Parallel studies were carried out to evaluate the leaching patters of commercially available three nitrogen fertilizers sold in Sri Lanka in the soil matrix using the columns. Control reactions were carried out with ammonium nitrate in a soil matrix alone. Each experiment was carried in triplicate. Experimental results indicated that the level of nitrogen content in different parts of the gliricidia plants varied from 4599 mg kg-1 to 24381 mg kg-1. It was found that phosphorous content in gliricidia plant varied from 1367 mg kg-1 to 3143 mg kg-1. Potassium in different parts of the gliricidia plants varied from 140 mg kg-1 to 2600 mg kg-1. Therefore, gliricidia plant can potentially be used as a fertilizer source of nitrogen, phosphorous and potassium. After treating gliricidia bark particles with saturated ammonium nitrate, the total nitrogen content in gliricidia bark particles increased by more than six times with a maximum value of 67830 mg kg-1 after 6 hours. The initial nitrogen content in the bark was 10080 mg kg-1. According to the experimental results, within 24 hours more than 80% of the nitrogen was eluted from ammonium nitrate and commercially available fertilizers in the soil matrix given. However, only 24% of nitrogen was eluted from NH4NO3 incorporated gliricidia bark particles within 24 hours. After 15 days eluted nitrogen amount was recorded as only 43% from treated gliricidia bark particles. Therefore, it could be inferred that nitrogen was released from NH4NO3 impregnated gliricidia wood chips in a slow-release pattern. According to research data, it could be concluded that gliricidia bark particles have a great potential as a fertilizer carrier for the development of a nitrogen rich new slow release biomass fertilizer system.
Microcystin -LR Contamination status of Nile tilapia (Oreochromis niloticus) collected from reservoirs in Polonnaruwa District, Sri Lanka.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Abeysiri, H.A.S.N.; Manage, P.M.
Microcystin-LR (MC-LR) is a cyanotoxin derived from some cyanobacteria. Nile Tilapia (Oreochromis niloticus) is the most popular freshwater fish in Sri Lanka. MC-LR accumulation in Nile tilapia from four reservoirs; Parakrama Samudraya, Halmilla Wewa, Kaudulla Wewa and Ambagas Wewa in Polonnaruwa District was determined to evaluate the risk posed by the MC-LR contamination in fish on human health. Sample collection, transportation and analysis were followed according to the standard protocols and MC-LR was quantified by High Performance Liquid Chromatography (HPLC). Fish skin, flesh and head were analyzed for MC-LR and Tolerable Daily Intake (TDI) values were calculated according to the WHO guidelines (0.04 μg/day/person). The standard lengths of 30 fish ranged between 15.2 cm and 21.5 cm. The mean concentration of MC-LR in skin, flesh and head were 18.41 ± 1.76 μg/g, 0.32 ± 0.01 μg/g and 6.69 ± 0.42 μg/g respectively in fish samples collected from Parakrama Samudraya. In Kaudulla Wewa, level of MC-LR in skin, flesh and head were 13.27 ± 0.56 μg/g, 16.21 ± 0.47 μg/g and 3.08 ± 0.35 μg/g respectively and in Halmilla Wewa, MC-LR in skin and flesh were not detected. However, MC-LR in head was recorded as 0.40 ± 0.03 μg/g. In Ambagas Wewa, MC-LR levels were not detected in the fish samples. TDI of MC-LR in fish skin and head in Parakrama Samudraya was 0.35 ± 0.02 μg/day/person, and 0.16 ± 0.01 μg/day/person respectively. TDI of MC-LR in fish skin, flesh and head in Kaudulla Wewa was 0.48 ± 0.03 μg/day/person, 0.41 ± 0.04 μg/day/person and 0.07 ± 0.01 μg/day/person respectively. These values exceeded the TDI value given by WHO. However, the TDI value in fish flesh in Parakrama Samudraya was 0.007 ± 0.001 μg/day/person and the value was below the given WHO standard. Thus the present study revealed that consumption of head, and skin part of fish has a potent risk on accumulation of MC-LR in human body. Therefore, removel of head part and skin is recommended prior to consumption, in order to avoid MC-LR contamination. Further public awareness is needed to minimize the potent risk on accumulations of MC-LR in human body.
Default risk and debt recovery strategies of microfinance providers: A comparative study in Sri Lanka.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Kalpani, B. L. W.; Abeysekera, R.
The objective of this research is to identify and compare strategies used by six different Microfinance Institutions (MFIS) in Sri Lanka in order to minimize the risk of loan default and to recover debt. It also evaluates the effectiveness of the debt recovery strategies. According to Fitch ratings, over exposure to microfinance at Sri Lankan non-bank financial institutions (NBFIs) could pose risk to their credit profiles. The exposure among Fitch-rated NBFIs stood at just 4% of total loans of these entities as recently as March 2014, but this had increased to 27% by December 2015. The case study method used in this study is motivated by the need to understand the strategies that the MFIs are adopting to deal with the issues of non-performing loans in their portfolios. In this research, the conceptualized model has been developed to form the basis and it has been modified according to the Sri Lankan context covering MFI’s categorization. The model has been developed with a comprehensive review of the literature. MFIs will be mainly categorized on the basis of ownership. Then, it will be further subcategorized under the basis of non-profit or profit organizations. Further, it will be filtered according to the mentioned Portfolio at Risk (PAR) classification. Lending method will also be a part of filtering the institutions since it also affects the recovery strategy formulation. The data will be gathered primarily based on in-depth interviews. The findings contributes to both the knowledge domain and the practical domain.
Creative fusion of scientific methods with mathematics and computing.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Karunananda, A.S.
The birth of the Scientific Method in the 17th century is considered as an unprecedented breakthrough by humankind in the discovery of new knowledge and inventions. The scientific method primarily emphasizes on proving the validity of a hypothesis through a systematically designed experiment. In the process of conducting scientific experiments, the results generated are analyzed statistically, to substantiate a hypothesis thereby forming a scientific theory. In the 17th century, Francis Bacon identified induction as the method of reasoning in science, and Newton extended the idea of induction with the hypothetico-deductive reasoning. Since then, Newton’s approach to Scientific Method has been practiced. From its inception, the scientific method has been influenced by developments in fields such as mathematics, statistics and computing. The penetration of developments in other disciplines into science has primarily been required by the challenging, hazardous, costly, and time consuming nature of experimental design in Scientific Method. In other words, developing experiments to prove multiple hypothesis has become a challenge. One classic example is the challenge faced by Faraday and Wright brothers when they experimented and proved their hypotheses on electricity and flying machines. Historically, Mathematics happened to be the first giant to address practical issues in experimental designs. Developments in Mathematics in 18th and 19th centuries greatly influenced the Scientific Method and paved the way for Theoretical Physics. In simple terms, theoretical physics can formulate and verify theories by mathematical techniques such as differential equations. Many theories in Quantum Mechanics and Theory of Relativity were developed under the umbrella of theoretical physics. Such theories have been subsequently proven by experiments. Emergence of the field of computing in the latter part of the 20th century has marked yet another breakthrough in knowledge discovery and inventions. Undisputedly, computing is identified as a subject area in which significant developments have been reported in 60 years. The latest advancements in all other disciplines including natural sciences, medicine, engineering, entertainment, and social sciences have been influenced by the developments in computing. More importantly, computing has introduced new means of designing experiments as computer-based simulations in research in almost all disciplines. Computer-based experiments have been cost effective, time saving, hazard free, and even provided insight for experiments in unseen dimensions. It has now been a tradition to go for computer based simulation (in-silico) before going into actual experiments (wet-lab). For example, designing of complex machines such as aircrafts and ships are now modeled and tested in computer-based simulators before being tested through real world experiments. Presently, the computer has become the most versatile laboratory for research in all disciplines. More importantly, computing can facilitate not only experimental design but also hypothesis development, sampling, data collection, data analysis and presentations in scientific research. In conclusion, it is emphasized that creative fusion of mathematics and computing with scientific method has discovered a new dimension for research and development for humankind.
A mathematical model for a lubricant approximation of the wet thin tear film.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Ranathunga, G. P.; Karunathilake, N. G. A.
The classical description of the tear film resides on the anterior surface of the eye between the upper and lower lids is a wet thin film. Various fluid dynamic model have been developed for the evolution of the surfactant concentration and the thickness of precorneal thin tear film on the eye surface after each blink. In this work we model tear film as an incompressible Newtonian fluid together with the surfactant equations with appropriate boundary conditions. On a lubricant framework we formulate the motion of the tear film mathematically using mass, momentum and transport equations with free surface boundary conditions. The conjoining pressure in the film is modelled by the standard Van der Waals force with Hamaker constant. The non-dimensional model is discretized using Finite volume method together with nonlinear multigrid approach. This Multigrid approach to the mathematical model with the conjoining pressure improves the results of the model. Study reveals that near the lower lid the thickness comes down from the initial condition but subsequently it advances to reach a maximum at somewhere around the middle and gradually decreases to its equilibrium level to the end. The surfactant concentration in contrast drops steady to zero from lower lid to upper lid. Several dry spots resulting from the evaporation can be observed in the numerical results.
Determination of Multiple Antibiotic Resistant (MAR) and MAR Index in bacteria isolated from aquaculture farms.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Liyanage, G. Y.; Manage, P.M.
Concurrent resistance to antibiotics of different structural classes has arisen in a multitude of bacterial species and cause complicating the therapeutic management for both human and animal. The objective of the study was to determine the Multiple Antibiotic Resistance (MAR) and MAR index of isolated tetracycline resistance bacteria from aquaculture sources. 42 tetracycline resistance bacteria, which were previously isolated from aquaculture farms were tested against Oxytetracyline (OTC), Tetracycline (TET), Amphicillin (AMP), Amoxicillin (AM.X), Sulfamethaxasol (SMX), Trimethoprim (TMP), Erythromycin (ERM), Cloxacillin (CLOX) and Ciprofloxacin (CJP). The MAR was determined by using Triphenyl Tetrazolium Chloride (TTC) assay and agar dilution method following CLSI guidelines. Then the MAR index was calculated. Among the isolates, 64.3% were resistant to three or more antibiotics and considered as multiple antibiotic resistant according to the WHO and CLSI guidelines. Among the MAR isolates, 93 % were resistant to OTC, 90% to TET, 34% to AMX, 14 % to AMP, 13 % to ERM, 11 % to SMX-TMP and 2% were resistant to CLOX were detected. None of the bacteria were resistance for CIP. The calculated MAR index was ranged from 0.03 to 0.42 for the isolated bacteria and the highest MAR index was recorded by Staphylococcus sp. (0.42), while the lowest was shown by Enterobacter sp. (0.03). The results of the study indicate that the overuse and misuse of antibiotics led to emergence of MAR bacteria and it compromises effectiveness of antibacterial therapy, leading infectious microorganisms to become resistant against antibiotics.
Production of bio-ethanol using pretreated lignocellulosic materials (rice husk, water hyacinth).
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Arasaretnam, S.; ayasundara, J. M. P. W.
Production from food sources such as corn, sugarcane etc. is the most predominant way of producing ethanol. This has led to a shortage in food, imbalance in food chain, increased food price and indirect land use. This study thus explores the use of alternative nonfood materials for the production of ethanol from cellulose. Rice husk and water hyacinth were selected as raw material in this study. The powdered rice husk and water hyacinth were subjected to physical pretreatment by washing with distilled water to remove all the soluble impurities in the materials followed by air-drying, cutting (water hyacinths), oven drying for 6 hours at 60 ℃ and finely powdered samples were stored inside a container at room temperature. Chemical pretreatment (acid pretreatment) was performed by physically soaking each lignocellulosic substrate in 1 M H2SO4 for 24 hours and shaking (150 rpm) at room temperature. Each solid sample was recovered by filtration and washing repeatedly with distilled water until the water pH was 7.0. Subsequently each sample was dried at 80 ℃ to a constant weight in oven prior to enzymatic hydrolysis. Both pretreatments were used to optimize the conditions for maximum ethanol productivity from rice husk and water hyacinth. Enzymatic hydrolysis of pretreated rice husk and water hyacinth gave the highest yield of reducing sugar. As a result of qualitative test, pretreatment methods had been applied on rice husk and water hyacinth in order to increase the available cellulose content and thus improve the enzymatic hydrolysis efficiency. The result of FTIR characterization of pretreated rice husk and water hyacinth implies that both samples contain bio-ethanol.
Distribution of Pemphis acidula to enhance conservation measures in Puttalam lagoon, Sri Lanka.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Gunathilaka, M. D. K. L.
Pemphis acidula have identified as a mangrove associate species, which is a rare species limited only to Puttalam lagoon area. This is identified as a near threatened species in Sri Lanka. The study aimed to identify the distribution of P acidula in Puttalam lagoon area and to suggest conservation measures using primary and secondary data. Field survey and interviews were used to obtain primary data. Hundred individuals, live along the periphery of lagoon were interviewed to evaluate threats and awareness of P acidula. Vegetation sampling were performed for randomly selected 25 sample sites (S1-S25) to find out the distribution of species in the lagoon area. The sample size was 5m ᵡ 5m. Water samples were also collected at the same locations to measure salinity of the lagoon water. Arc GIS mapping techniques and MS excel 2016 version were used for data analysis. The species were enumerated in identified four particular areas in Puttalam lagoon area. Higher distribution was identified towards to the ocean. In addition, the species was also present in Kalpitiya mainland. The preferable salinity level of the species was reported as between 26-30 g/L. Therefore, considering the salinity in the study area, Kala oya estuary area and Dutch bay area were identified as most suitable areas for the distribution of the plant. P acidula were not present in the sites where salinity was less than 20g/L, which indicated that the species prefer high salinity levels. P acidula, which has high potential to exterminate dengue larvae and have strong antibacterial activity has been reduced drastically due to clearings of mangroves. Though the species are important for industrial and pharmaceutical purposes, there are no conservation measures to protect the species at present. The unawareness of coastal residents live along the periphery of the lagoon was about 90% and the threat has been increased as people used to destroy the plant for firewood. Therefore, conservation measures should be introduced using appropriate methods such as demarcations of buffer zones, to prevent removing the plants. Regular research and observations are important to keep updated records on number and distribution of this species. Northern-most parts in the lagoon where the salinity level is high as 26-30 g/L were identified as possible restoration sites of P acidula. As it is an invaluable plant, it is timely important to conserve P acidula population in Puttalam lagoon area.
Soil nutrient availability in different vegetation types of Kunckles conservation forest in Sri Lanka.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Rajapaksha, R.P.S.K.; Madawala, H.M.S.P.; Gunathilake, S.K.; Ratnayake, R.R.
Estimates of soil nutrient availability in tropical land use types are critically important to understand the function of soil in the global nutrient cycles and the sustainable management of tropical ecosystems. The aim of this study was to quantify and compare the macro and micro nutrient availability in soils in different vegetation types in the Knuckles Conservation Forest (KCF) of Sri Lanka. Soil samples were collected within two depth layers (0-15 and 15-30 cm) considering the proportion and the accessibility to each vegetation type. The selected vegetation types were montane forest (MF), sub-montane forest (SMF), moist monsoon forest (MMF), open and sparse forest (OSF), grassland (GL) and forest plantation (FP). The macro nutrient (N, P, K, Ca and Mg) and micro nutrient (Fe, Mn, Cu and Zn) availabilities were analyzed for two soil depth layers (0-15 and 15-30 cm). A total of 1224 samples were collected from two depths and pooled to form 408 composite samples. General Linear Model in Analysis of Variance was performed using Minitab 16 to analyze the data. Availability of N and P in KCF soils ranged between 8.18 - 19.76 mg/kg and 0.21 - 0.45 mg/kg, respectively among the vegetation types in the 0-15 cm layer. N and P availability was significantly higher in SMF (21.23 and 0.49 mg/kg respectively) and OSF (22.08 and 0.47 mg/kg) soils compared to other vegetation types. Significantly low N availability was observed in both GL (5.07 mg/kg) and MF (7.32 mg/kg) soils. It was also found that P was significantly deficient in MF soils compared to other vegetation types in KCF. Vegetation types in KCF showed significant differences in the availability of K, Ca, Mg, Fe, Mn, Cu and Zn in soils. Fe availability in soils varied between 187.4 - 682.3 mg/kg while Mn varied from 28.52 - 85.26 mg/kg. Results concluded that spatial availability of nutrients such as N and P in mineral soil may be decreased in MF comparing to the other vegetation types due to the environmental conditions such as acidic soil pH, low temperature and microbial growth existing at high altitudes of KCF. This suggests limitation of plant growth in MF by deficiency of one or several nutrients at higher altitudes. Availability of K and Ca in KCF may be affected by parent material exposed on to the soil surface. This baseline information will address the dearth of data on soil nutrient availability of different ecosystems in the tropics, hence useful in future conservation purposes of the tropical forest ecosystems.
Equilibrium studies on the adsorption of heavy metals, dyes and phenol by phosphoric acid modified rice husk.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Parthiban, G.; Rifna, M. S. F.
The removal of contaminants from wastewater is still far away from a satisfactory solution. In fact, the selection of a particular wastewater treatment technology should not be based uniquely on its efficiency, but should rather integrate environmental and economical aspects. Within this framework, the main objective of this study is the removal of various contaminants in wastewater including heavy metals (Cadmium and Copper), dyes (Methyl Red and Methylene Blue) and Phenolic compounds via an environmental friendly green technology method. In this study, grounded rice husk was examined as sorbent material which was chemically modified with Phosphoric acid (1.0 M) and was found to be effective in removing the contaminants. Batch studies were performed on synthetic wastewater at room temperature to evaluate the effects of various parameters such as contact time, pH, initial concentration of the solution and adsorbent dose on removal efficiency of the pollutants. The experiment was also applied to treat two samples of industrial wastewater containing Cadmium and Carmoisine E122. The removal efficiency was found to be pH dependant. The removal efficiency was higher for Phenol and Methyl Red at low pH values and it was shown that the removal efficiency was higher for heavy metals and Methylene Blue at higher pH values. The equilibrium was reached approximately in 2 hours for all the contaminants. Equilibrium sorption data were fitted into Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherms. Of the four adsorption isotherms, the R2 value was higher for D-R isotherm for the adsorption of Cadmium (0.979), Freundlich and Temkin isotherms for the adsorption of Copper (0.945), Freundlich isotherm for the adsorption of Methyl Red (0.994), Temkin isotherm for the adsorption of Methylene Blue (0.953) and Langmuir isotherm for the adsorption of Phenol (0.987). Adsorption data were well described and adsorption isotherm constants were determined from the respective adsorption isotherm equations. The present study analyzed the adsorption of rice husk and concluded that treated rice husk gave comparatively better adsorption efficiency. The treated rice husk can be implemented on large scale industrial applications after field studies.
Intrusion of Cd, As, Cr, Pb & Hg into selected rice varieties (Oryza sativa L.) in relation to their status in two different agricultural management systems.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Navarathna, N. M .C. M.; Pathiratne, K. A. S.; De Silva, D. S. M.
Five traditional varieties (TRV) and five newly improved hybrid varieties of paddy (NIRV) were cultivated under both conventional and organic farming conditions during Yala and Maha seasons at selected areas in Anuradhapura district where chronic kidney disease was prevalent and Kurunegala districts where chronic kidney disease was not known to exist at the time of the study. The area used for cultivation under each organic and conventional farming condition in each district was approximately 11 m x 11 m and was well separated from each other. The contents of each of the selected toxic elements; Cd, As, Cr, Hg, and Pb in the soil, irrigation water, conventional and organic fertilizers and pesticides used for cultivation together with the relevant physicochemical parameters for soil were estimated before the beginning of the cultivation while the required physicochemical parameters and contents of the elements in irrigation water were estimated regularly during the cultivation. After the maturity periods at each cultivation, paddy were harvested and the contents of the elements in rice grains, straws and roots were determined. All samples for determination of the elements were processed and microwave acid digested according to US EPA 3052 method and analyzed using atomic absorption spectrometer. (Hitachi ZA3000 Zeeman Polarized). Analytical methods were validated using either standard reference materials or recovery tests. The study revealed that, the contents of any of the selected elements in any of the rice varieties grown did not exceed the safe limits of 200 μg kg-1 for Cd, 200 μg kg-1 for As, 300 μg kg-1 for Pb, 2000 μg kg-1 for Cr and 20 μg kg-1 for Hg recommended by the World Health Organization (WHO) and Food and Agricultural Organization (FAO) for milled rice. Hg, As and Pb were not detected in any of the rice varieties grown. The highest content of Cr detected was one tenth of the allowable WHO limit of 2000 μg kg-1. The contents of cadmium were in the range below the detection limit of 159 μg kg-1. Arsenic was below the detection limits in agrochemicals, soils and irrigation waters. Pb and Cr were present in fertilizers below the SLSI limits of 10 mg kg-1 and 250 mg kg-1, respectively. Slightly elevated levels of cadmium (1.80 mg kg-1 to 3.44 mg kg-1) were detected in Muriate of Potash (MOP) and Triple Super Phosphate (TSP) respectively. The green fertilizers contained Cd in the range from 0.44 mg kg-1 to 1.67 mg kg-1 . Irrigation water did contain Cd below the detection limits of 0.2 ± 0.0 μg L-1, while Cr contents were in the range of 13.8 ± 1.9 μg L-1 to 157.9 ± 22.7 μg L-1. The Cd contents in paddy soils were in the range 0.41 ± 0.02 mg kg-1 to 0.75 ± 0.03 mg kg-1 and while the Cr contents were in the range 1.33 ± 0.15 mg kg-1 to 1.63 ± 0.09 mg kg-1. Cd was detected in rice straws along with roots in the range, 12.2 ± 2.6 μg kg-1 to 1582 ± 74.3 μg kg-1.
Development of a hydroponic test system for rapid screening of plant growth promoting microorganisms.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Perera, U. I. D.; Imasha, M. I. N.; Welikala, N.
Plant-growth-promoting microorganisms (PGPMs) have become increasingly important in the agricultural production of many crops. It is envisioned that in the not too distant future, PGPMs will begin to replace the use of chemicals in agriculture, horticulture, silviculture, and environmental cleanup strategies. Nutrient mobilization, stimulation of root growth, enhanced resistance to environmental stress factors are discussed as possible mechanisms of plant growth promotion. The development of rapid screening tests to demonstrate the principle effectiveness of biofertilizers prior to set-up of laborious pot or field experiments is urgently required. In this study, a hydroponic-test system for rice plant was developed and verified to evaluate the effectiveness of plant growth promoting diazotrophic bacterial strains. Seven putative plant growth promoting diazotrophic bacterial (PGPB) strains (IN003, IN006, IN007, INS008, INS009, INS015, INS018) were tested as parameters based on their biochemical characteristics such as nitrogen fixation, acid and gas production, production of ammonia from urea using germination rate, average root and shoot length, average dry/fresh weight of roots and shoots, number of roots and average coleoptile length. The experiment was designed with three replicates. Hoagland’s solution was used as a hydroponic culture. Nitrogen-free broth media was used to grow diazotrophic bacterial strains. Equal volumes of bacterial cultures grown overnight were used as the inoculum. Rice seeds were inoculated for 6 hours before germination by immersing rice seeds in broth cultures and seeds treated with heat killed bacterial strains were used as a control. Seed trays with equal volume of Hoagland’s solution were used to grow the germinated rice seeds after inoculation. After 12 days of culture period, germination rate of rice seeds, number of roots, shoot length, root length, dry/fresh weight of shoots, and dry/fresh weight of roots, average length of coleoptile of the rice seedlings were measured. Inoculation of seeds with plant growth promoting bacteria did not show significant increase (p ≤0.05) in the germination rate of rice seeds compared to the control seeds. Strains INS015 and INS018 showed a significant increase (p ≤0.05) in shoot root dry/fresh weights compared to other strains. The highest average shoot length (0.23 ± 3.4×10-2) m was recorded in seeds treated with bacterial stain INS015. The results of this study indicate that certain plant growth promoting bacterial strains used in this study can promote the growth and vigor of rice seedlings which benefit early seedling development consequently the crop growth and development. Hydroponic test system is an effective and rapid method to study the effect of plant growth promoting bacteria on the growth and vigor of rice seedlings.
A conceptual framework to assess supply chain risk in the apparel industry.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Erandi, H.; Peter, S.
Along with the advent of globalization and the championing of free trade together with improved communication and transportation systems, enterprises have the ability to source supplies from a globally distributed supply chain. However, on the flip side, due to the complexities in dealing with a dispersed network of suppliers, manufacturing companies are facing risks of disruption to their supply chains. As risk is very context dependent, it is important to identify supply chain risks in different contexts and industries. Sri Lankan apparel industry plays a major role in the country’s economy, making it vital for companies to engage in proper identification and assessment of these risks. Therefore, the objective of this study is to conceptualize a model to assess identified supply chain risks and thereby to generate an overall risk assessment score for an apparel manufacturing company. The initial base for risk identification is through the use of the Ishikawa model. The cause and the effect for supply chain risks were established by analysing the initial data collected and via industry experts, a list of risk classes and sub classes were formed. Thereafter, a modified version of risk numeric analysis model is used to setup each and every class weight where industry experts’ opinion is taken for calculating the appropriate weights. Instead of using Analytical Process Hierarchy (AHP) which was used in the original model, Analytical Network Process (ANP) is used to prioritize the identified risk classes. The decision to use ANP is due to its ability to consider the complex inter relationships and linkages between risk classes and sub classes during the prioritization process. Finally, an aggregate score is developed for the overall company in terms of the supply chain risks by using the scores obtained for each risk class. The model will highlight the different types of supply chain risks that an apparel manufacturing company may face and how a proper mechanism can be developed to quantify these risks. The model would facilitate the company to directly identify the magnitude of each and every supply chain risk and the risk distribution via the overall risk score of the company. The risk score can be used by managers as a flag or an indicator that signals the company about potential risks. Apart from that, this model can be used to compare historical figures to monitor and evaluate the overall risk scores of the company. Furthermore this risk score can be used to compare the company performance with other competitors’ score values and to analyse how competitive the company is within the industry.
Applicability of Bluetooth routing ad-hoc networks for efficient communication.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Jayawardena, B.
In the age of Internet of Things, we expect devices other than computers to communicate with similar or different types of devices. These devices have to be designed in a specific way to communicate and achieve a predefined set of objectives. Hence, the devices need to be aware of with whom they should communicate and what, with what infrastructure and operational environments such as cars, door-locks, refrigerators, health information devices which could create intelligent systems that communicate over the Internet with information/computer systems. On the road, cars may move in a lane one after the other, swiftly engaging in lane changes, slowing down through intersections, accelerating when required, turning left and right after each block. If these vehicles can continuously communicate with each other to exchange status updates on its movement and drivers’ actions, smooth operation of vehicles on roads could become a reality. Cars need to know who is behind them, front of them, and passing them, in order to send messages forward, backward or around each one of them. The study describes two instances (event of braking and road condition of a location) where cars communicate depending on information collected through ad-hoc networks, built upon sharing critical information and a selection of topologies and protocols depending on the objective of the network. The study proposes Bluetooth routing ad-hoc network to provide conceptual framework for dynamic ad-hoc networks where a set of devices can quickly form in a network based on their relative position, continue to maintain the network as new nodes join and leave, and disband once the objective of the network is accomplished. Specialty of this situation is that each node should know who are directly nearby or next to them, and from which direction, in order to communicate specific messages, and when required, a node should be able to reach a group of nodes in a given direction, but out of direct communication range, through intermediary nodes that route communications. A signal such as Wi-Fi would reach longer distance than Bluetooth, confusing this critical discovery process by reaching irrelevant devices faraway. Currently, this area has not been studied specifically. Concept was validated by having a group of devices arranged in a line, being able to discover each other, communicate with each other based on their relative physical positon in the group, and pass simple messages between them. Bluetooth communication uses low power radio signals in a limited range, compared to strong Wi-Fi signals that travel longer distances. Bluetooth ad-hoc routing networks can handle discovery and peer negotiations efficiently and even let stronger, long-distanced Wi-Fi signals make communication between the nodes where required, based on the established Bluetooth ad-hoc network.
Anti-oxidant activity of selected endo lichenic fungi (ELF) in mangrove ecosystem of Puttalam lagoon.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Maduranga, H.A.K.; Attanayake, R.N.; Amarasinghe, M.D.; Weerakoon, G.; Paranagama, P.A.
Natural products based drug development has become an attractive area of research since there are limited options available to treat certain non-infectious diseases such as diabetes. Among these natural products, it has been reported that secondary metabolites of endolichenic fungi (ELF), have the ability to produce promising bioactive compounds. The objectives of this research were to isolate and identify ELF inhabiting mangroves in Puttalam lagoon, Sri Lanka using classical and DNA barcoding approach and to determine anti-oxidant activity of their secondary metabolites. Lichen hosts were collected from Puttalam lagoon in two different sites near, Athathale and around the NARA institute. The ELF were isolated following a standard procedure: a small piece of the thallus was surface sterilized, cut into pieces and dried on sterilized filter papers and then placed on malt extract agar in Petri dishes and incubated at room temperature (28 ⁰C – 30 ⁰C ) . Once pure cultures were obtained, seven isolates were randomly selected for DNA extraction following standard procedures. Quality of DNA was checked by agarose gel electrophoresis. Fungal internal transcribed spacer (ITS) region was amplified using polymerase chain reaction (PCR) with universal ITS 1 and ITS 4 primers and PCR products were sequenced using Sanger dideoxy chain-termination technology. DNA sequences were edited using BioEdit software and compared with the available sequences in the GenBank using Basic Local Sequence Alignment Search Tool (BLAST). In addition, morphological characterization of each fungal isolate was also carried out. Secondary metabolites from each isolate were extracted with ethylacetate separately and the solvent was evaporated under reduced pressure to obtain the crude extract. Free radical scavenging activity of the extracts were evaluated using 2, 2-diphenyl-1-picrylhydrdrazyl (DPPH) assay. Based on the highest sequence similarity to the GenBank sequences, isolates were identified as Diaporthe arengae (98 %), Neurospora crassa (100%), Lasiodiplodia theobromae (100 %), Schizophyllum commune (98 %), Diaporthe musigena (98 %), Hypoxylon anthochroum (98 %) and Nigrospora sphaerica (98%). IC50 values of extracts of Diaporthe arengae, Neurospora crassa and Lasiodiplodia theobromae were 375.9± 0.062μg/mL, 304.9±0.057 μg/mL and 211.2± 0.086 μg/mL respectively. Since percent inhibitions of the rest of the isolates were less than 50 % in the test doses, IC50 values were not calculated. All of the values were compared with standard Butylated Hydroxy Toluene (BHT) (IC50=108.0±0.072). Out of the seven ELF tested, L. theobromae showed the highest DPPH radical scavenging activity. Further testing of the rest of the isolates are being carried out and ELF may provide a good source of antioxidants for biotechnological applications.
Enhancement of the degradation of vulcanized natural rubber by natural fatty oils.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Ruhunage, C. K.; Jayasuriya, C. K.
The overall use of natural rubber for a large number of applications is constantly on the rise and results in a growing volume of rubber waste. The cross-linked structure of rubber and the presence of stabilizers cause rubber recalcitrance to both chemical and biological degradation. Landfill disposal of rubber materials leads to wastage of valuable rubber causing many environmental problems. Reclaiming and reusing are major approaches to solve this problem worldwide. The current study was focused on studying the degradation of vulcanized natural rubber using natural fatty oils which have the potential to be used as reclaiming agents. The process of degradation strongly suggests that rubbers are susceptible to attack by free radicals from peroxidizable organic compounds under an oxygen atmosphere. Hence the radicals produced from lipid hydroperoxides by lipid autoxidation of unsaturated fatty oils have the ability to promote degradation of rubber. Commercial grade coconut oil, corn oil and sunflower oil were used during the present research to study the degradation of Vulcanized Natural Rubber (VNR). VNR samples (10.6 cm x 10.6 x 0.2 cm) were prepared and immersed in fatty oils (300.0 mL) separately for various time periods such as 3, 6, 9 weeks at room temperature under dark environment and for 6 weeks in the presence of sunlight. At the end of the each time period, testing of mechanical properties was done by BS ISO 37-2010, BS ISO 34-1:2010 and BS ISO 48:2010 methods. Further characterization of the samples was performed using Fourier Transformed Infrared-Attenuated Total Reflectance spectroscopy (FTIR-ATR) and Scanning Electron Microscopy (SEM). Results revealed that mechanical properties of VNR decreased when samples were immersed in fatty oils for longer time periods. Also as the degree of unsaturation of fatty oil increases, the mechanical properties decreased dramatically. In addition, the presence of sunlight enhances the loss of mechanical properties. According to the present study, the loss of mechanical properties was higher when vulcanizates immersed in sunflower oil under sunlight. Scanning electron micrographs of surfaces of samples immersed in corn oil and sunflower oil for 6 weeks under sunlight revealed the samples were deteriorated. According to the results of the current study, the degradation of VNR can be enhanced by immersing vulcanized natural rubber in fatty oils such as sunflower oil and corn oil which are rich in polyunsaturated fatty acids. Therefore a new system can be developed for reclaiming and safe disposal of products derived from vulcanized natural rubber with the use of highly unsaturated fatty oils.
Polarizability of a metallic nano-cylinder: Local random-phase approximation (LRPA).
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Asela, A.U.; Hewageegana, P.S.
We develop a method to calculate the polarizability of a nano-cylinder by taking temporal and spatial dispersion in to account where dispersion due to the Landau damping. To describe these phenomena, we developed analytical theory based on local random-phase approximation. Our theory is very general in the sense that it can be applied to any material which can be characterized by a bulk dielectric function of the form ....... The theory is applied to calculate the polarizabilities of dielectric and metallic nano-cylinders. Here we focus on calculating the transverse static polarizability of a cylindrical nanowire by taking the temporal and spatial dispersion into account. To describe these phenomena, we developed an analytical theory by solving the well-known Lindhard formula which gives one of the closed solutions in the theory of Fermi systems that explicitly gives the nonlocal dielectric response function (longitudinal) ....... We developed a simple theoretical framework for the polarizability of a nanowire that allows the inclusion of nonlocal effects. Our results are significant for thin wires and small particles, where the nonlocal effects are much more relevant. We hope that our work will be useful in studying the optical properties of nano particles in particular nanowires.
Assessment of environmental and economic impacts of mangrove deforestation in Vidataltivu lagoon, Sri Lanka.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Marynathan, E.; Sosai, A. S.; Wickramasinghe, W. M. S.; Jayasinghe, G. Y.
Mangroves are unique plants that grow in specific topographic locations under special conditions. Most mangrove ecosystems are under threat because of human interventions. Since Sri Lanka is an island, the mangrove extent is high compared to other countries in the world. The study was aimed at assessing the environmental impact of mangrove deforestation, the effect of mangrove destruction on the economic status of local residents and the degree of awareness about mangroves in the nearby community. The researched location in Vidataltivu has optimal conditions for mangrove ecosystems along with fresh waterfronts entering the sea water. The area selected had 600 families and 90% of them were fishermen. A questionnaire survey was conducted using the stratified random sampling technique for 50 fishermen from Vidataltivu. According to the study 93% of the people had awareness on the damages, causes, human interaction, species diversity and the importance of mangroves to the economy of the community. 36% of the fishermen engaged in fishing for their freedom, 24% of them do not have any alternatives. However, the research has shown that the displacement of people from other parts of the Northern Province had increased the population in this area resulting in excessive consumption of mangroves for various needs. The younger generation (40%) of Vidataltivu has the awareness, but the feel of responsibility is absent as 25% people do not bother about the environment. Ninety two percent people have the basic awareness about mangroves but they do not want to take responsibility. The analysis of data shows a lack of passion for prevention of mangrove destruction. Ninety percent of the people stated that the destruction of mangroves cause a problem to the ecosystem and 92% people also acknowledge that mangrove destruction is one of the major reasons for why the quantity of species has gone down. They also believe that if the mangroves were not destroyed, they must have had a better yield in their fishing nets. However, contradictorily and surprisingly, 78% of them do not want to feel that they were responsible, and are still causing the destruction of most of these mangroves. Therefore, in conclusion this research makes several suggestions such as enabling community participation on mangrove protection and restoration, encouraging youngsters in the area as well as identifying leaders and focus groups within the peripheral community to be trained and motivated towards environmental protection together with enforcement of self-awareness. Eventually, this will lead to a protected mangrove ecosystem in Vidataltivu lagoon in future.
A census of diurnal primates in the villages located between Labugama-Kalatuwawa and Indikada forest reserves in Colombo District of Sri Lanka.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Panagoda, P.A.B.G.; Weerasinghe, V.P.A.
The diurnal primate populations which inhabit the villages, located between Labugama-Kalatuwawa and Indikada Forest Reserves in Colombo District of Sri Lanka, has a high conservation value due to the presence of critically endangered Semnophithecus vetulus nestor (Western purple-faced langur). In addition, these diurnal primate populations consisting of S. vetulus nestor and Macaca sinica (Toque macaque have caused many human-monkey conflict incidents within the area. No studies have assessed the local populations of diurnal primates within this area in spite of its importance in both above perspectives: conservation and conflict. Therefore, this study was aimed to assess the relative density and group size of diurnal primates and to statistically compare above two estimations between the two primate species. The census was carried out within a selected stripe of villages located between the two forests. Using reconnaissance walks, five trails (2 km each) were established to represent the study area, with a systematic sampling design. The trails were walked simultaneously, by five independent trained teams each consisting of five persons, in the morning and afternoon on 3rd of December, 2016. In addition, group counts of monkeys were made during 10 opportunistic field visits, from April to December 2016. For each species, the average group size and group and individual encounter rates (as a measure of relative density) were calculated. The group sizes and encounter rates of the two species were then statistically compared using Mann-Whitney U test. Group size of S. vetulus nestor (mean ± SE) was lower (4.46 ± 0.40 individuals) than that of M. sinica (8.29 ± 2.19 individuals), even though the median group sizes of the two species were not significantly different (p=0.1893). On the other hand, S. vetulus nestor was found to be more abundant in the area compared to M. sinica. The number of encounters of S. vetulus nestor and M. sinica during the census was 10 and 4 respectively. Further, the average group encounter rates (mean ± SE) of S. vetulus nestor and M. sinica, were 0.95 ± 0.31 and 0.33 ± 0.23 respectively (no. of groups/km) whereas the average individual encounter rates (mean ± SE) of S. vetulus nestor and M. sinica, were 4.23 ± 1.38 and 2.71 ± 1.89 (no. of individuals/km) respectively. However, no significant difference was found between the median group (p=0.470) and individual (p=0.4647) encounter rates of the two species. Yet, the higher abundance of S. vetulus nestor over M. sinica, could also be observed during the opportunistic observations made throughout the whole study period (opportunistic group encounters; 22 for S. vetulus nestor and 9 for M. sinica). The reliability of the results can further be improved by censusing at different times of the year. As this study sets a baseline, future studies are recommended to identify any growth or decline of this crucial population of primates.