IRSPAS 2016

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Assessing potential biological hazards associated with Kelani River water using Nile tilapia (Oreochromis niloticus) as an aquatic model species
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Ruvinda, K.M.S.; Pathiratne, A.
Kelani River receives complex mixtures of pollutants from diverse sources which include waste from industries, agriculture, domestic and municipal sources. However, scientifically based evidences on biological impacts associated with the Kelani River water are limited. Nile tilapia (Oreochromis niloticus) is a practically feasible aquatic model for toxicological assessments under tropical conditions. The present study assessed erythrocytic nuclear abnormalities (ENA), hepatic ethoxyresorufin O-deethylase (EROD) and hepatic glutathione S-transferase (GSTs) activities of Nile tilapia following exposure to selected surface water samples collected from the Kelani River and its tributaries in order to assess the potential biological impacts. Fingerlings of fish were exposed to surface water samples from an industrial effluent receiving canal (Menikagara ela; Site B), canal confluent (Site M), downstream of Kelani river at Sedawatta (contaminated with oil installation complex effluents and house hold waste; Site S) and up stream of Kelani river at Ruwanwella (reference site; Site R) and aged tap water (as controls) for 10 days under static renewal conditions. Physico-chemical parameters of exposed water were measured using standard analytical methods. Blood and liver samples of the exposed fish were collected from each treatment after 5 and 10 days of exposure, and ENA and EROD and GST tests were performed using standard methods. Water quality parameters indicated high levels of chemical oxygen demand, biochemical oxygen demand, total dissolved solid, salinity and conductivity and elevated levels of total phosphate content, nitrate content, heavy metal Cr, Cu and Pb levels in the water collected from the Sites B, M and S compared to tap water (P <0.05). Frequencies of total ENA were significantly higher in the fish exposed to water from the sites B, M and S compared those of the fish exposed to the tap water for 5 and 10 days. Blebbed and notched nuclei contributed mainly to the induction of total ENA than micronuclei and nuclear buds. Total number of nuclear abnormalities was elevated by the 10th day of exposure. Hepatic EROD and GST activities of the fish exposed to polluted water were not significantly different (P >0.05) from those of the fish exposed to tap water, but the enzyme activities were increased in each treatment at 10th day of exposure. Comparison of nuclear abnormalities and hepatic EROD & GST activities of O. niloticus together with physico-chemical analysis revealed that Sites B, M and S of Kelani River are contaminated with organic and inorganic xenobiotics, which may pose harmful cyto-genotoxic impacts on the feral fish populations.
Applicability of unsupervised learning algorithms for setting profiles for consumer buying behavior
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Paranavithana, I.R.; Rupasinghe, T.D.
The Consumer Buying Behaviour consists of a summation of attitudes, preferences, intentions and, decisions taken by them. The process that customer buys a product or service varies for each individual and each category of products they may purchase. With the development of Information Technology, the products and the behaviour of purchasing those products have drastically changed and become more unique to individuals. With respect to these changes, the data collection and analysis have become more dynamic and customer data has become larger and nosier in terms of volume and complexity. As a result of that, handling, analysing, and interpreting customer Point of Sale (POS) data has become a challenge for Retail Supply Chains (RSC) who wish to segregate customers into specific niche markets. Furthermore, it makes increasingly difficult for the retailer to find out when a person comes and buys the products from their outlets and to predict his/her behaviour for the subsequent purchases. As a solution for the aforementioned problems faced by the retailers, a novel a consumer buying behaviour profile mechanism is proposed. The profiles are created with respect to the frequency, time-stamp, and product category using a large POS dataset. The Unsupervised learning techniques were utilized in categorizing consumers in determining similar purchasing behaviour using K-means, Expectation Maximization, and Hierarchical Agglomerative Clustering (HAC). Along with the above clustering techniques, text mining techniques were used in categorizing the product descriptions to create the desired product categories. The study has used data from the UCI machine learning repository with 541,909 POS type records and has applied the aforementioned unsupervised learning techniques to setup the profiles. It has unveiled product related and non-product related charateristics for the given POS data and has laid a novel foundation to construct the profiles to determine buying behaviour. Furthermore, these profiles can be used in segmentation of consumers, RSC specific promotions, and to predict future possibilities to minimize inventory related problems.
A survey on usage of canteens of University of Kelaniya by students of Faculty of Science
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Dias, S.N.U.P.; Priyasad, H.A.D.; Manamperi, D.K.S.; Kumara, M.S.M.S.; Sandaruwan, D.M.S.; Pramoda, K. A.D.A.; Fernando, T.S.D.; Rashmi, W.A.D.; Ravindran, U.M.; Dhananjani, W.T.; Pitigalaarachchi, P.A.A.C.; Attanayake, A.M.C.H.
The university canteens while providing meals are an important meeting point for both students and staff members. There are several canteens within a university but service provided by canteens and therefore, students’ preferences for canteens may be different. This survey is based on five main canteens at the University of Kelaniya; Base, Gym, Hilton, Staff and Hostel canteens. The aim of this survey is to understand the usage of the canteens by students of the Faculty of Science. The objectives are to identify the frequently visited canteen of the students and the reasons for it, categorize the most visited canteen by gender, year of study, accommodation type, measure the satisfaction on available facilities of university canteens and classify the student expectations regarding the facilities. The survey was conducted during the period of September – November 2015. Among the 1394 students registered in the Faculty of Science, 255 respondents were randomly selected using simple random sampling method (without replacement). An appropriate questionnaire was developed in order to gather data and achieve the objectives. After a pilot survey was conducted, questionnaire was administered in person and online and also by interviewing busy students in order to collect data. The analysis reveals that the majority of students (41%) of the Faculty of Science visited Base canteen for their needs; whereas 25% visited Staff canteen and 22% visit the Gym canteen. The usage does not change irrespective of whether the student stays at the hostel, boarding place or home. The reason for using the Base canteen is convenience in reaching the canteen. Female students (49%) use the Base canteen whereas male students (38%) prefer to use Staff canteen. Lunch is the preferred meal compared to breakfast, dinner and other snacks. The majority of first year students visit the Base canteen, 2nd year students prefer to visit Gym and Staff canteens than the Base canteen and 3rd year students prefer the Base canteen. Majority of the students (29%) have ranked the condition of Base canteen as average and 14% have ranked as good. When considering the attitude of the staff members of the canteens, Base and Staff canteens’ employees have been highly ranked as ‘Average’ by most of the respondents (19% and 17% respectively) while ‘Good’ was marked by 15%. Most of the respondents have marked as ‘Average’ considering the service speed of canteens in the university and around 20% of students have claimed that the service speed is low over all canteens. In general, only 45% of the students are satisfied with the facilities provided by the canteens. Most of the students (23%) have requested to expand the space within the canteens and requested to have air conditioning, TVs and vending machines within the canteens. The survey discloses important findings about the usage of university canteens by students of the Faculty of Science.
“Save me”: Alternative payment method for in-app purchases
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Choxmi, S.; Peter, S.
The mobile smart phone has become the most sought after technology tool, among the younger generation of the world. Sri Lanka is no exception with mobile penetration at more than 100% with growth of smart phone usage growing exponentially. Gaming with the aid of computers has become a billion dollar business and the wide usage of mobiles meant that a wider audience has now access to such tools. Companies are moving away from broad based advertising to more targeted direct advertising to capture market share. Use of mobile apps is widespread and the potential for companies to generate revenue streams by tapping into these applications have huge potential. The business strategy adopted by some developers is to offer the game for free while progress in levels of the game require in-app purchases to improve the gaming success and gain competitive advantage among players. In the perspective of the developers, in-app purchasing done by the gaming individuals is the main revenue stream. In developing countries like Sri Lanka, players of these games are reluctant or unable to spend money to purchase these inapps, since there is no financial benefit other than succeeding in the game. The other reason is that credit card details should be provided to purchase them. Most young people do not have or have access to credit card facilities. Thus, developers of game products are inhibited due to the lack of monetary incentive to build new gaming products and the players are inhibited by not being able to utilize the total advantages provided by the game. “Save – me” is a product designed to overcome these constraints by introducing an alternative method for payment and thus provide an incentive for mobile game developers to expand their market and increase their revenues, leading to the development of the information technology sector in the country. The current revenue models used by game developers include, selling the game for a fixed amount as a onetime fee, generating revenue from advertising while providing the game at no cost, and product or service providers financing the cost of the game through use of virtual coins. The models were evaluated using cost-benefit and sensitivity analysis. The latter was selected for its innovativeness and the ability to address the issue in a cost effective manner. The web portal solution includes three stakeholders. i.e. gamers, developers and manufacturers of goods and services targeting the gaming segment of the population. The process will commence with manufacturers / distributors assigning a discount to their products, in order to boost their revenue. Instead of giving customers the monetary discounts, the manufacturers will purchase virtual coins from “Save me”, and assign those coins to selected games on the portal. Customers who have registered on the portal, can earn these virtual coins instead of the discount, by progressing through the game and collecting these virtual coins. They can then exchange these virtual coins by going to their local supermarket which acts as a distributor and exchange the coins for the physical product that the manufacturer wants to promote. The game developers will be sharing the revenue via the purchases done by the players together with the portal owner.
Localized modes of an electron by topological insulator defect
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Kumara, R.D.M.M.; Hewageegana, P.
Topological insulators, a new class of materials discovered recently, have very unique topological properties. While the surface states are gapless and are topologically protected by the time reversal symmetry, the bulk of topological insulator shows a full gap. We study the properties of reflected and transmitted electron waves on the surface of topological insulator nanofilm with a defect. We show that an electron incident on a defect produces modes, which are localized at the defect. Such modes result in an enhancement of electron density at the defect. If an electron with a given energy E is incident on a region of the TI nanofilm which does not support electron propagating waves at energy E, then there is a strong enhancement of local electron density near the boundary of such region. We calculate the reflectance and transmittance of an electron from such a defect for different parameters of the topological insulator nanofilm and different parameters of the defect. The amplitude of the electron wave strongly depends on the position of electron energy. If electron energy is in the energy gap of defect, then the reflectance is 1. This result corresponds to total internal reflection. If the electron energy is not in the energy gap of defect, then the reflectance is small and the electron is almost totally transmitted. The critical points dividing these two boundaries are defined by the condition that the electron energy is at the band edge of energy dispersion. The dependence of the electron wave on the parameters of the system, such as thickness of the nanofilm or electron energy, is dominated near the critical points.
Design and construction of low cost petri dish incubator
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wanigasekara, G.; Perera, N.W.; Abeysinghe, D.; Geegamage, S.S.; Wijekoon, D.; Jayathilaka, N.
Petri dish incubators are used in laboratories to keep petri dish samples at a stable and optimal temperature of 37 °C. Incubators are one of the frequently needed equipment. These incubators are expensive due to the use of complex systems. Many of the local universities do not have the necessary financial resources to purchase this equipment. Therefore, undergraduate students usually do not have access to incubators for academic learning. In order to surmount this challenge, it is necessary to look at a low cost, simple design for petri dish incubators. Hence, we have designed an incubator utilizing low cost microcontroller boards and sensors. Both microcontrollers and sensors were selected to provide adequate accuracy for the incubation at 37 °C. The incubator is constructed of three major components; sensors, controller and temperature regulation system. The incubator uses three LM35 temperature sensors to monitor the temperature with 0.5 °C accuracy and the system is controlled by Arduino Uno board with 16 MHz ATmega328P microcontroller. The microcontroller regulates the temperature of the incubation chamber utilizing 200W Nichrome heating element and two exhaust fans. Three temperature sensor readings were taken to acquire chamber temperature by averaging three values. Microcontroller uses these data to control the heating element, the fan for heating and the fan for cooling. The controller uses a PID (Proportional–Integral–Derivative) algorithm to stabilize the temperature. The sensor input wiring is highly shielded to avoid interference from the main powerline magnetic noise. The incubator body is shielded with porcelain to avoid fire hazards. The average temperature recorded by the incubator sensor and the chamber temperature as recorded with a thermometer was monitored at 2 hr intervals over a 16 hr period at 37.6 ± 0.5 °C and 37.6 ± 0.5 °C respectively indicating the accuracy of temperature regulation in the petri dish incubator over an extended period of incubation.
Growth of CuZnS thin films by sequential electrodeposition and sulphurisation
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Fernando, W.T.R.S.; Jayathilekea, K.M.D.C.; Wijesundera, R.P.; Siripala, W.
Copper Zinc Sulphide (CuZnS) is a promising new absorber material for solar cell applications. Indeed, this material is very attractive for low cost device applications due to abundance and low cost of the staring materials. Very recently, a CuZnS based solar cell with In2S3 window material has been reported having Voc of 0.41 V, Jsc of 10.6 mA/cm2, FF of 45% and  of 1.94%. This initial finding has proven the possibility of developing this material as a solar energy material. Among the CuZnS preparation techniques, electrodeposition is an attractive technique because of its simplicity, low cost and possibility of making large area thin films. In this study, possibility of growth of CuZnS thin films by sulphurisation of electrodeposited Cu and Zn stack layers using S powder has been investigated. Cu thin film was electrodeposited on Ti substrate at –700 mV Vs Ag/AgCl for 15 min in an electrochemical cell containing 0.05 M sodium acetate and 0.005 M cupric acetate. Deposition of Zn thin film on Ti/Cu electrodes was carried out at -1.2 V Vs Ag/AgCl for 1 min in an electrochemical cell containing 0.2 M ZnSO4. Deposition parameters of Cu and Zn have been obtained by voltammograms. Set of identical Ti/Cu/Zn thin film electrodes having Cu/Zn ratio of 3.2 were prepared by maintaining the respective Cu and Zn thin film deposition durations for studying the sulphurisation process. In order to grow CuZnS, Ti/Cu/Zn thin film electrodes were annealed at different temperatures (400 oC, 450 oC, 500 oC, 550 oC and 600 oC) with different S contents (10 mg, 20 mg, 30 mg, 40 mg and 50 mg) for a duration of 60 min. CuZnS thin films were characterized using dark and light current voltage measurements in a PEC containing 0.1 M sodium acetate to obtain the best sulphurisation condition. Dark and light I-V characteristics revealed that the films annealed at 600 oC with the S content between 10 to 20 mg exhibits photoactivity. Further, photocurrent was always cathodic confirming the formation of p-CuZnS thin films. It was revealed in this preliminary investigation that the best photoactive films could be produced when films are annealed at 600 oC for 60 min in 20 mg S content. We have found, that photoactive p-CuZnS thin films can be grown by employing the technique of annealing electrodeposited Cu and Zn stack layers using S powder. Cu/Zn ratio of the stack layers could be the crucial parameter in determining the structure, conductivity type and resistivity of CuZnS films and therefore the methodology developed in this study could be further investigated, in order to develop the material for wider applications.
Impact of teamwork quality on software development project success: Sri Lankan context
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Kumari, P.D.R.S.; Wijayanayake, W.M.J.I.
Software has become a very crucial in all facets of modern world by the growth of technology. A software development project (SDP) can be viewed as a set of activities performed by a set of developers. Software development is a complex activity that requires teamwork effectively. Teamwork is a dynamic process of working collaboratively with a group of people in order to achieve a goal. According to the literature, Software project success can be measured using four indicators namely, cost, quality, time and scope and there is a significant relationship between teamwork quality (TWQ) and SDPs success. Most of researchers have done their research works on teamwork for German and Dutch SDPs. However we cannot apply these findings direct to Sri Lankan context. As found literature of social and cultural factors can be effect to performance of software development project. The main objective of this research is to come up with a framework to explain impact of TWQ for SDPs success. To achieve that objective, conceptual model was developed as mention in the figure. The model was derived from different models which are found in literature. Then the indicators which are used to measure TWQ factors and the SDPs success are identified. This study focuses on Qualitative Research approach and questionnaire is used as the technique of data collection. Participation selection is done through snowball sampling, making use of our network to make contact with organizations to ask for their willingness to participate. TWQ on SDP success is gaining an increasing interest within both academia and industry. The reasons for making this kind of research supporting strategic and operational management of SDPs to organize teams more efficiently and effectively. Our research work has ability to solve actual delay incurred by a software project due to lack of TWQ due to lower performance of team members. This is useful for Sri Lankan software industry to build and manage teams more constructively and adjust their management activities to improve team collaborations and team performance.
The chromatic number of prime graph of a noncommutative ring Mn×n(Z2)
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Kolombage, K.A.D.D.B.V.; Wijesiri, G.S.
Graph theory is a significant area of Mathematics as its outstanding applications in many fields such as biochemistry, electrical engineering, computer science and operational research. Besides Graph theory, Ring theory is an abstract area in Mathematics. A ring consists of a set equipped with two binary operations that generalize the arithmetic operations of addition (+) and multiplication(∗). Theorems obtained as a result of abstract study of rings can be applied to solve problems arising in number theory, geometry and many other fields. The study of rings with the help of graphs began when a graph of a commutative ring was defined by I. Beck in 1988. Then a new bridge was formed between graph theory and the algebraic concept “ring” noted as prime graph of a ring 􀀌, denoted by 􀀍􀀎(􀀌) by B. Satyanarayana, K. Shyam Prasad, and D.Nagaraju in 2010. Later on with the help of existing concepts, K. Patra and S. Kalita investigated the chromatic number of prime graph, 􀀏􀀍􀀎(ℤ􀀐) of ring ℤ􀀐 for different values of 􀀑. Prime graph of a ring 􀀌 is a graph whose vertices are all elements of the ring and any two vertices 􀀒, 􀀔 of the vertex set are adjacent if and only if 􀀒 ∗ 􀀔 = 0 or 􀀔 ∗ 􀀒 = 0 and 􀀒 ≠ 􀀔 In this paper, we investigate the chromatic number of prime graph of some noncommutative rings 􀀘􀀐×􀀐(ℤ􀀙) for different values of n. The chromatic number of prime graph of some commutative rings are formed on the recognition of the conjecture that chromatic number, 􀀏(􀀌) and clique number are the same. But for non-commutative rings this is not always the case. Hence, in order to find the chromatic number of prime graph of a non-commutative ring, 􀀘􀀐×􀀐(ℤ􀀙), we have looked into MATLAB for a tactical solution.
Management of coastal resources: Lessons learnt from two coastal communities occupying the west coast of Sri Lanka
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Kodituwakku, K.A.R.K.; Wazir, S.R.; Aththanayake, A.M.H.L.; Silva, T.M.S.D.G.; Malshani, E.M.S.; Partheepan, K.; Thevendran, K.; Udayanga, N.W.B.A.L.; Sumanapala, A.P.; Jayanga, B.H.N.; Chandrasekara, W.U.
The livelihood of the coastal communities is mostly dependent upon the natural coastal resources. Questionnaire based field surveys were carried out focusing on the communities in two coastal towns on the west coast of Sri Lanka, Negombo and Chilaw, with an objective of evaluating and assessing the governance and the sustainable utilization and management of coastal resources there. The survey was carried out in December 2013, and consisted of face-to-face interviews and gathering information from households along the beach border that were selected through systematic sampling approach and from randomly selected stake holders on the beach, to satisfy the questionnaire. The chief executive officers of local government authorities viz. regional office of the Coast Conservation and Coastal Resources Management Department, Municipal Councils, Police Stations, and where necessary the incumbent of the Catholic Church in the area, were also interviewed to evaluate their role over the governance and management of the coastal resources. The analysis of survey data revealed that the major resource based income generation activities in Negombo beach was tourism (68%) while in Chilaw it was fisheries (75%). The major environmental issues in Negombo beach were pollution (35%), littering the beach by local tourists (27%) and illegal building constructions (20%), while those in Chilaw were pollution (43%), illegal house constructions (25%) and coastal erosion (26%). Therefore, the Negombo beach was cleaner (76%) than the Chilaw beach (27%). Since the major income generation activity in Negombo beach was tourism, the local government authorities paid special attention in maintaining law and order, carrying out beach cleaning programmes, daily removal of litter and waste, carrying out community awareness programmes on the importance of beach on tourism and usage of soft and hard engineering techniques to prevent coastal erosion. In addition, every tourist hotel was found to clean the beach façades under their purview, and beach vendors also supported these programmes. In fisheries dominated Chilaw, the inputs by the local government authorities were minimum except the Urban Council collecting household waste on weekly basis from the roadside bins. However, the village has a very strong community based management strategy led by the Catholic Church. The church plays a pivotal role in harmonizing the village, educating villagers on the proper disposal of garbage, preventing sand mining and use of harmful fishing practices, and coordinating the local government authorities to maintain proper sanitation as well as law, order and peace in the area. In contrast, the tourism dominated coastal zone in Negombo is managed by a strong co-management strategy that involves the contribution of the local government authorities and major stakeholders on the beach such as tourist hotels and the local community on the governess and sustainable management of the coastal zone.
Survey on ethnomedicinal uses of Eriocaulon ceylanicum in a selected division in Kuliyapitiya
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wijesinghe, W.A.M.S.; Jayakody, J.A.D.P.P.
Therapeutic effects and medicinal efficacy of the wild herbs were identified and administered by the ancient people to cure various ailments.Recently, the practice of herbal medicine has been diminishing, which may lead to the loss of valuable informations about healing herbs. There are many medicinal plants grown in semievergreen forests of Sri Lanka. This present study attempts to identify the use of traditional medicine and medicinal uses of Eriocaulon ceylanicum. A questionnaire survey was provided to randomly selected 200 people, of age between 30-80 years in Deegalla division located in Kuliyapitiya, West region of Kurunegla district. Study showed that only 36.5% of the respondents out of 200 were utilizing Eriocaulon ceylanicum for various ailments. Regarding the preparation method, 78.08% used the plant in fresh condition, 15.07% used both fresh and dry forms and 6.85% in dry form. According to the way of practicing, 60.28% used this plant as a source of food and 39.72% used as a remedy. Among those who utilized this plant as a remedy, it was used to treat Malnutrition (Māndama) (37.93%), burning sensation during urination (Mutra dāha ) (24.14%), leucorrhoea (Sweta pradara) (20.69%), anemia (Pāndu) (6.9%), skin disorders( Kushta ) (6.9%) and orthopedic conditions (Bhagna) (3.45%). .According to the indigenous medicnal texts Eriocaulon ceylanicum can be used to treat a wide range of ailments like Liver diseases (Yakrit roga), Spleenomegaly (Pleehāvriddi), Jaundice (Kāmalā), Alcohol-toxicity (Madātya), Pith roga, Dāha, Rathpith, Thirst (Trishnā), Vāta roga,Unmāda, Prameha, Pradara and, Soma roga. Despite its significant contributions, traditional medicine in Sri Lanka has attracted very little attention in research and development, and less effort has been made to uplift the role of traditional medicine practice. Thus, extensive research on such traditional plants is of prime importance to scientifically validate their ethnomedical claims.
Determination of polyphenol content in coconut milk by modified Folin-Denis assay
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Nadeeshani, R.; Seneviratne, K.N.; Jayathilaka, N.
Polyphenols are micronutrients which has nutritional value owing to their antioxidant activity. Polyphenol content is usually determined by the standard Folin-Denis Assay. Water soluble compounds commonly present in biological samples, such as proteins, ascorbic acid, DNA and RNA may interfere with this assay. Therefore, it is difficult to determine whether the antioxidant capacity of such samples are owing to these interfering compounds or other polyphenols present in the aqueous extracts (AE) like coconut milk (CM). In order to overcome these drawbacks, a modified extraction method was employed to remove proteins from the AE of CM to determine the polyphenol content in first (FE) and second (SE) extracts of both domestic and commercial preparations of CM using Folin-Denis assay. The results were reported as Gallic acid equivalents (mg/mL). Proteins/peptides present in the AE of CM (1.00 mL) was removed by organic extraction with chloroform (1.00 mL), distilled water (4.00 mL) and methanol (4.00 mL). Samples were mixed at 30 Hz for 01 min followed by centrifugation at 6000 rpm for 05 min. The methanolic layer was used for the Folin-Denis assay. The methanolic extracts (ME) were confirmed free of proteins by Bradford assay. Results showed significantly low polyphenol content in the ME compared to the AE indicating interference in the assay from proteins/peptides present in the AE of CM. Corresponding antioxidant activity of the ME of both FE and SE of domestic CM preparations were significantly higher compared to the commercial counterparts regardless of the presence of high polyphenol content in the AE. Therefore, the modified Folin-Denis assay reported here determine the polyphenol content in AE of food preparations that may contribute to their antioxidant potential.
Analysis of the error in an iterative algorithm for solution of the regulator equations for nonlinear parabolic control system
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Hansameenu, W.P.T.; Aulisa, E.; Gilliam, D.
This work is based on the classical geometric method, which in turn is based on the classical geometric regulation theory, which involves asymptotic tracking and disturbance rejection for nonlinear parabolic control systems. The classical geometric method is based on the solution of a coupled pair of operator equations referred to as regulator equations. In general, solving the regulator equations or even obtaining accurate numerical solutions for the simple control problem is not an easy task. In fact, most of the time the classical geometric method gives the solvability conditions of the regulator problem, rather than the actual solution. We present a methodology for tracking and disturbance rejection, which is more general than the one based on the regulator equations, and can be applied to general smooth signals. This methodology is based on an iterative method known as the 􀀈- iterative method for obtaining approximate solution for the regulator problems for a class of infinite dimensional linear control systems. This work describes the error analysis for this iterative method regarding more general references and disturbances. In this work we consider bounded input and output operators. In particular, we obtain estimates showing geometric convergence of the error, controlled by the parameter 􀀈. In addition, we demonstrate our estimates on a variety of control problems in multi-physics applications by numerically solving the 􀀈-iterative algorithm by using the finite element solver “COMSOL”.
Study on effect of microfauna and some abiotic parameters for the prevalence of mosquito larvae inhabiting marshlands
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Menike, P.M.I.D.; Amarasinghe, L.D.
This study was carried out in selected marshlands of Kelaniya in Sri Lanka to determine the prevalence of various mosquito species larvae and their association with biotic and abiotic parameters of the habitat. Larval sampling, recording of physico chemical parameters and microfauna identification were done at monthly interval from March 2015 to August 2015. The study was carried out in eight marshlands with varying Biochemical Oxygen Demand (BOD) levels and total number of 893 mosquito larvae were collected (n=144). Culex gelidus, Cx. whitmorei, Cx. tritaeniorhynchus, Cx. quinquefasciatus, Cx. fuscocephala and Anopheles sp. 1 were the species/taxa identified. Cx. gelidus, Cx. whitmorei, Cx. quinquefasciatus were found in mashes with BOD level ranging from 1.5-2 mg/L and Cx. fuscocephala with 1-1.5 mg/L. Anopheles sp. 1 was found in significantly low level. pH levels in these habitats did not vary significantly and lied between 6.5-7.0. When Cx. whitmorei and Cx. gelidus co-existed in one habitat, it was found a significant negative correlation between the populations of two species. Similar results were found when Cx. quinquefasciatus with Cx. gelidus present together in same habitat. However, Cx. fuscocephala and Cx. gelidus when present together in same habitat, it was shown a positive correlation. In marshlands, 14 genera of microfauna were identified (n=144). Among them Zoothamnium sp 1 was most common and found higher densities and followed by Difflugia sp 1, Nauplius larva, Cyclops sp 1, and Daphnia sp 1. Pearson correlation showed that there was a correlation between the density of mosquito larvae and associated microfauna. Zoothamnium sp. 1 was given negative correlation with the Cx. gelidus when they present in higher density. A significant positive correlation was obtained between Daphnia sp. 1, Difflugia sp. 1, Nauplius larva and Keratella sp. 1 with mosquito larvae. Hence, there is no relationship between microfauna and mosquito populations. However, this may depend on the BOD of the habitat.
A preliminary study of lip moisturizer rich in antioxidants produced using coffee leaf extract
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Gunasinghe, K.G.; Nadeeshani, R.; Jayathilaka, N.
As the body’s first environmental defense, the skin is exposed to various sources of free radical damage including the sun. In addition, to maintain healthy skin, it is important to maintain the moisture content not only in the deeper dermal and epidermal layers but also at the surface. As such, there are numerous skin moisturizers commercially available specially formulated to not only moisturize the body, face and the lips but also block the harmful rays from the sun to protect the skin surface. The composition of the lip moisturizers available in the market varies from brand to brand. These products often contain castor oil, carnauba wax and chemicals/ preservatives such as propyl paraben, methyl paraben, retinyl palmitate, tocopheryl acetate etc. as well as different agents to block the harmful rays from the sun. Antioxidants can be added to these products to neutralize the free radicals that can cause damage to the skin. Plant polyphenols are known to have high antioxidant activity. In this study, we have formulated a lip moisturizer with aqueous extracts from coffee leaves rich with polyphenols in an effort to develop a product that can neutralize free radical damage on the surface skin. The product was developed using bees wax, vaseline, coffee leaves and water (1: 2: 1: 11.5) with no other additional chemicals to formulate a natural healthy cosmetic. Polyphenols in the water extract was extracted in to methanol by removing the proteins using chloroform. The polyphenol content in the aqueous extract (0.18 ± 0.01 mg/ml) was measured by Folin-Denis assay as Gallic acid equivalent, using water as the control. The antioxidant activity of the extract was measured by DPPH radical scavenging assay. The percentage inhibition of DPPH radical scavenging activity of the aqueous extract of the coffee leaves measured using water as the blank gave 83.46 ± 0.11% of inhibition. Each sample was assayed three times for three biological replicates. The polyphenol content and the percentage inhibition of DPPH radical scavenging activity of the aqueous extracts, extracted from the formulated lip moisturizer were 0.14 ± 0.01 mg/ml and 83.44 ± 0.43% respectively. There is no statistically significant difference in the polyphenol content and the antioxidant activity between the aqueous extracts (p< 0.01). Lip moisturizer produced without the additon of coffee leaf extract was used as the control. According to the DPPH assay 99.97± 0.27% of percentage inhibition of DPPH radical scavenging activity was retained. Therefore, the lip moisturizer formulated with the coffee leaf extract retained the antioxidant properties.
In vivo expression of H69-targeting peptides in bacteria
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Muthunayake, N.; Dremann, D.; Colangelo, W.; Cunningham, P.R.; Chow, C.S.
Identifying novel drug targets within the bacterial ribosome is an important approach to overcome the well-known problem of antibiotic resistance. The specific region of the ribosome under investigation in this study is helix 69 (H69) of 23S ribosomal RNA. Considering the variety of functions of H69 in protein biosynthesis, as well as differences between the bacterial and human H69 sequences, this RNA is an attractive antibacterial drug target. In a previous study, short peptides that specifically bind to H69 were isolated by using phage-display libraries. In a second approach, modified variants of the selected parent peptide sequence were synthesized to identify more tight binders. The main objective of the current study was to express these H69-targeting peptides in E. coli to investigate the inhibitory effects on protein synthesis. H69-targeting peptides were expressed in vivo as Green Fluorescence Protein-fusion proteins and their activities were monitored through cellular fluorescence levels. The seven-mer peptide sequence was cloned behind the Tobacco Etch Virus (TEV) protease recognition sequence. Expression of TEV protease from another plasmid in the same cell cleaves the TEV-recognition peptide sequence, and the peptide is then exposed at the N-terminus of GFP. The construct was prepared in which a his tag was placed at the C- terminus of the GFP gene such that the peptide could be purified for further experiments. In order to further characterize selected peptides as potential drug leads it is necessary to determine their activity outside the context of the fusion protein. Therefore, currently we are using a different plasmid system which can be used to express short peptides as free peptides in bacteria cells. Expression of two different peptides was shown to have an inhibitory effect on bacterial cell growth. These findings will be helpful for future antimicrobial drug development.
Urban traffic simulation using agent-based modelling: A study in the Sri Lankan context
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Amarasinghe, U.G.L.S.; Rajapakse, C.
Traffic congestion is a crucial issue affecting the quality of life of individuals all over the world. In a country like Sri Lanka where the traffic is mostly unorganised and mixed, traffic congestion occurs due to various reasons such as the volume of traffic exceeding the capacity of the road, road accidents, temporary closures of roads due to constructions, as well as the behaviours of pedestrians and drivers. For example, careless lane changing behaviours of drivers and the bad practices of crossing streets of pedestrians account for a larger portion of urban traffic congestion every day. Due to the significant impact of traffic congestion to economic growth, various approaches have been taken by researchers and administrators to reduce the urban traffic congestion. Some popular approaches to solving this issue includes infrastructure development, introducing new traffic rules such as changing peak hour traffic plans in cities, as well as imposing heavy duties on vehicle imports to reduce the growing volume of vehicles on roads. However, despite all these attempts, the traffic congestion remains a serious issue in Sri Lanka. Traffic simulation is one of the most effective tools for the testing of traffic solutions and finds the reasons causing traffic congestion. Traffic conditions are different from region to region due to different factors: traffic laws, vehicle types, drivers’ and pedestrians’ behaviours. Therefore, researches have been done by focusing on modelling traffic simulators considering those factors specific to particular regions. We propose the Agent-Based Modelling and Simulation (ABMS) approach, which is a popular computational research method based on swarm intelligence to study complex social and economic systems, to model a traffic simulator simulating mixed traffic conditions in Sri Lanka which is an unaddressed area of research. In this approach, individual vehicles and pedestrians are modelled as software agents who have a set of individual (i.e. micro level) behavioural rules. When these agents are put together, they behave as the vehicles and pedestrians behave in the real world interacting with each other giving rise to emergent macro-level patterns, which we call traffic congestions. This study aims at modelling vehicle following behavior, seepage behaviour of vehicles and pedestrian’s behaviours at un-signalized crossings. We use the ABMS environment called NetLogo to develop our simulator and Kiribathgoda junction in Western Province, Sri Lanka as the test bed. Data collected from there will be used to calibrate the model with accurate parameter values. Macroscopic statistics such as the rate of traffic flow, average speeds and queue time will be used to validate the model by comparing data from real traffic situations with model outputs. The ultimate objective of this research is to come up with a cost-effective decision support tool for administrators and policy makers to understand various reasons behind congestion in unorganised mixed traffic environments in Sri Lanka, apply and evaluate different traffic control strategies and thereby to make better-informed decisions to control urban traffic congestion in Sri Lanka.
Comparison of different culture media in MPN method for the estimation of coliforms and E. coli in tea and herbs
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Perera, W.D.H.N.; Asalaarachchi, G.; Abeygunawardena, S.I.
Estimation of coliforms and E coli are two major parameters that are used in microbial quality processes in food and, generally these organisms are tested via Most Probable Number (MPN) method. This method is one of the standard enumerating techniques that perform with different culture media. The objective of this study was to compare some different media used to perform MPN technique to enumerate coliforms and E. coli in dried food products, which have water activity less than 0.95. The procedure-1 was performed with MacConkey broth, Brilliant Green Lactose Bile (BGLB) broth and indole test and this was very much similar to the previous standard procedure given as SLS 516 (part-3) 1982. Two other procedures were selected and denoted as procedure-2 (ISO 4831: 2006) and procedure-3 (ISO 7251: 2005). All three procedures are horizontal methods for detection and enumeration of coliforms and E. coli via MPN technique. The procedure -2 was performed using Lauryl sulphate tryptose (LST) broth and BGLB. The Procedure-3 contained LST broth and EC broth. Tea and herb samples (dried food products) were subjected to parallel testing by above mentioned procedures. Reference bacterial cultures were tested with each experiment as internal quality control measurements. Some Tea and herb samples were spiked with coliform organisms to obtain detectable counts. Total of Seventeen samples were tested according to these horizontal methods for the detection and enumeration of coliforms and E. coli and the results were subjected to statistical analysis (Paired-t test). According to Procedure 1, coliform counts in tea samples were in a range of 20 – 1100 MPN/g with a mean of 199 MPN/g and E. coli counts were in a range of 0.3 – 1100 MPN/g with a mean of 157 MPN/g. The results indicated that coliform counts obtained via procedure-2 for the same tea samples were in the range of 0.3 – 1100 MPN/g. However, E. coli counts obtained through procedure-3 were very much similar to that of procedure-1. The procedures -1 and -2 gave similar results for the coliform counts in herbal components. The average coliform counts as per procedure -1 was 320 MPN/g whereas procedure-2 gave 346 MPN/g. E coli counts estimated via procedure-1 and 3 for these samples were varied between 0.3-110 MPN/g and 0.3 – 900 MPN/g respectively. Although there were differences in culture media used, the statistical analysis indicated that results obtained from procedure 1 and procedure 2 for coliforms in tea samples were not significantly different (T-paired vale 0.037< T-table value, p =0.05). Similar results were also obtained for coliforms in herbs as well as E. coli in both tea and herb samples.
Evaluation of nutrient and fiber content of selected invasive plants in Sri Lanka with a potential for preparing compost
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Hewavitharana, N.; Kannangara, B.T.S.D.P.; Jayasekera, L.R.; Senanayake, S.P.
Based on availability, the amount of above ground bio-mass and the degree of use as compost in traditional farming systems Tithonia diversifolia, Chromolaena odorata, Mikania scandens, Lantana camara, Wedelia trilobata, Mimosa pigra and Panicum maximum were selected for nutrient analysis, with an attempt to investigate their potential to be utilized in preparation of cost effective, organic potting medium for cultivation of selected vegetables and ornamental plants. According to the preliminary surveys, Anuradhapura, Madawachchiya, Kandy, Gampaha, Kalutara and Kurunegala areas were selected for sample collection. Leaves and immature stem parts of the selected plants were analyzed by two samples per one location with three replicates. The total N, P and K contents were determined by Kjeldahl, vanadomolybdate and flame photometric methods respectively. Atomic absorption spectrophotometry was used for quantitative analysis of Mg, Ca, Cu Zn, and Fe. Crude fiber content was determined gravimetrically after chemical digestion and solubilization of the materials. Results obtained were statistically analyzed using SPSS statistics-22 software. The nutrient contents of T. diversifolia; N (3.28%), P (0.37%), K (2.50%), Mg (0.83%), Ca (4.92%), Cu (10 mg/kg), Zn (517 mg/kg) Fe (296 mg/kg) and M. scandens; N (3.44%), P (0.35%), K (3.30%) Mg (1.33%), Ca (3.39%), Cu (34 mg/kg), Zn (671 mg/kg), Fe (393 mg/kg) were significantly higher than that of other selected weeds. However, they showed significantly lower crude fiber contents 4.85% and 3.50% respectively. Although the nutrient content in P. maximum was significantly low N (1.27%), P (0.24%), K (1.44%) Mg (0.5%), Ca (1.55%), Cu (9 mg/kg), (Zn 181 mg/kg), Fe (267 mg/kg) and its crude fiber content (20.42%) was significantly higher than that of others. It can be concluded, T. diversifolia and M. scandens as plant materials which have higher amounts of nutrients. P.maximum which has higher content of crude fiber also can be incorporated in preparing compost in order to improve the physical properties of the potting medium.
An online news crawling framework for an aggregated news site
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wagawaththa, W.A.I.K.; Wijayanayake, W.M.J.I.
The internet has become one of the most widespread platforms for information exchange and retrieval as the number of news websites is increasing rapidly. During the last decade, most of the major newspapers have developed web sites providing news and other information. In addition, web-only newspapers have also appeared. News aggregator is a good substitute for news sites like BBC news. Because news aggregators can index not just the content of the BBC news but all other news sites, giving it a huge advantage in coverage. On the other hand, news aggregators may complement online news sites. Because news consumers incur costs (time and effort) in searching for news that are important to them and also they will compare the expected benefit from visiting a news site to the expected search cost, where that cost includes becoming aware of the existence of the site and finding how to navigate it. There are few news aggregators like Google News, News Look Up, Fark which provide news aggregation facilities, but they are proprietary and there are privacy concerns about the user along with the biasness of these aggregators. In order to benefit more from the available information, the objective of the research is to develop a technical framework, gathering online news and approach to recognize most important latest news and display the recognized news items that society is interested in without any bias. Presenting crawled news items in a way that it displays the trending topics in society will increase the awareness of the reader. In order to do that news classification and ranking is a needed. News items for the framework will be gathered through (RSS) feeds. Gathered news feeds will be stored and will be preprocessed. Keywords will be extracted from an algorithm that can be worked with any language that has basic Morphological tools for language processing. Category classification of the news items will be done using a method that is based on the keyword extraction algorithm. Topic detection and classification of the news items will be done to the category classified news items using an algorithm that requires no corpus for statistics or training data. The ranking of the news article, topic and source will be done using an approach which is based on the virtual graph model. In the ranking process, similarity between articles are calculated manually and it will be automated using the cosine similarity.