IRSPAS 2016

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    Analysis of a stochastic predator-prey model
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Prasadini, K.D.S.; Mallawa Arachchi, D.K.
    In biological systems Lotka-Volterra predator-prey model describes the population dynamics of two interacting species of predators and its preys. Classical predatorprey model is a primitive deterministic model governed by the two differential equations, namely, ���� = (������ − ��������) ���� and ���� = (�������� − ������) ���� where �� and �� denote prey and predator respectively, and ����, ����, ���� and ���� are parameters. This model can be improved by introducing stochasticity that accounts for the random fluctuations of a realistic predator-prey dynamical system. In this research work, we use Stochastic Differential Equation (SDE) approach. There are various ways, based on various assumptions, to incorporate SDE. One common approach is to use equations of the following form: ���� = (������ − ��������) ���� + ��(���� + ����)�� ������ ���� = (�������� − ������) ���� + ��(���� + ����)�� ������ These types of Stochastic Differential Equations (SDE) can be simulated in Matlab using numerical methods such as Euler-Maruyama method. Phase planes of the deterministic and stochastic models are carried out to demonstrate the behavior of this modified model. Our initial goal is to compare different stochastic models with the original deterministic model through simulations. The deterministic model has a positive equilibrium which is globally stable for positive values of the parameters. Nevertheless, in the stochastic model, the predator and prey populations may tend to extinction. Extinction percentages of predator or prey population are summarized and analyzed through this research work.
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    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.
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    Probiotic functional drink to control type 2 diabetes mellitus – A review
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Perera, M.A.E.G.; Lakmali, J.P.D.; Wanninayaka, L.J.M.K.T.; Kulathunga, N.U.; Wanninayake, P.C.U.; Jayarathne, W.M.S.C.; Yapa, P.N.
    Type 2 diabetes mellitus (T2D) is a major non- infectious disease in the world and a global concern. Diabetes is a condition of multifactorial origin, including genetic and environmental factors. Further, scientific evidence suggests that increased inflammatory stress related to molecular mechanisms leading to insulin resistance, the intestinal microbiota interacting with environmental factors and susceptible genetic factors contributes to the development of diabetes. Soft drink consumption is a controversial issue for public health. Over the years, numerous studies have been conducted to find the possible links between soft drink intake and diabetes. As a result, increasing emphasis is being placed on the health properties of soft drinks, which leads the production of functional drinks. Hence this review appraises the current literature with the aim of producing a functional drink with probiotic bacteria in order to control blood sugar and prevent type 2 diabetes. Since the efficacy of probiotics is directly linked to the type of strain, the identification of strains used in the intervention are most beneficial for patients with T2D. The study suggested that the probiotics Lactobacillus acidophilus and Bifidobacterium animalis may have health benefits in people with type 2 diabetes. A study has shown daily consumption of 200 ml of a shake containing 4x108 CFU/100ml of Lactobacillus acidophilus, 4x108 CFU/100ml of Bifidobacterium bifidum and 1 g/100 ml of fructooligosaccharides, resulted in blood glucose reduction in diabetes patients. Probiotic bacteria, which is facultatively anaerobic and microaerophilic is encapsulated and inoculated to the functional drink. Thus after ingestion the probiotics become active in the existing optimal temperature around 37⁰C, tolerating the conditions of the gastrointestinal tract. The evidence available from experimental studies and clinical trials supports our suggestion that the modulation of the intestinal microbiota by probiotics in functional drinks may be effective towards prevention and management of type 2 diabetes.
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    Enumeration of yeast and mold in tea and herbs using different methods and culture media
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Jayashantha, E.T.; Asalaarachchi, G.; Abeygunawardena, S.I.
    The International Standard Organization (ISO) has recommended the use of Dichloran 18% glycerol agar (DG-18) to enumerate yeast and mold in food (ISO 21527-2:2008) with reduced water activity (aw < 0.95). This ISO method uses the Surface Spread technique (SS-t). According to the ISO standard procedure, pour plate method is allowed to perform after a proper validation of results using the same medium. The objective of this study was to compare the Pour Plate technique (PPt) and spread plate technique using DG18 agar medium to enumerate yeast & mold in tea and herbs (e.g. lemongrass). The DG 18 agar medium was also compared with Yeast extract Dextrose Chloramphenicol (YDC) agar to enumerate these microorganisms. The tea samples and the herbs obtained from tea industry were used as the matrices for this study because these components have a water activity a less than <0.95. The sample preparation and the test were performed according to the ISO 21527-2:2008 standard procedures. Total of 20 samples of herbs and tea were used in this microbiological testing programme and the results were statistically analyzed using Paired-t test, with Minitab-14. The DG-18 medium gave average yeast and mold counts in tea samples as 2.58±0.42 CFU (log)/g in SS- technique whereas PP technique gave 0.41±0.08 CFU (log)/g. The fungal burden in herbs was 2.69 ±0.54 CFU (log)/g (SP-t) and 2.17 ±0.89 CFU (log)/g (PP-t). The YDC medium using pour plate technique gave average yeast and mold counts for tea and herb samples as 2.44 ±0.44 CFU (log)/g and 2.88 ±2 CFU (log)/g respectively. The DG-18 agar medium with the same technique gave 2.52±0.43 CFU (log)/g and 2.46±1.5 CFU (log)/g. The statistical analysis indicated that the results obtained either using two different media or using two different techniques with DG 18 medium were not significantly different.
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    A preliminary microbiological study of chicken-based short-eat food in Kadawatha, Sri Lanka
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wimalasekara, S.G.M.R.L.; Gunasena, G.D.D.K.
    Foodborne disease outbreaks caused by microbiological hazards are a growing public health concern in all around the world. It results in a significant number of deaths and hospitalizations in each year. According to the ‘Weekly Epidemiological Report: A publication of the Epidemiology Unit’ of Ministry of Health (2013: Vol. 40, No. 49), fast short-eat food are identified as a prominent source of foodborne illnesses as they do not undergo any effective treatment to ensure food safety prior to consumption. Therefore, the present study was conducted to determine the microbiological quality and safety of fast food sold in highly urbanized Kadawatha city, Sri Lanka. A total of six chicken based short-eat food products obtained from recognized restaurants at Kadawatha city were analyzed for Total viable count (TVC), Total coliform count (TCC), Escherichia coli count (ECC), Staphylococcus aureus count (SAC) and for the presence of Salmonella according to Sri Lanka Standards (SLS:516). The noncompliance of the food samples were determined according to the local microbiological guidelines for fast food by Sri Lankan Standards Institution (SLS:1218). Food, including burger, club sandwich, bread roll sandwich and rotty exceeded the proposed guideline (5 log CFU/g) for TVC and club sandwich found to bear the highest TVC of 7.51 log CFU/g, whereas hotdog with mustard cream had the lowest of 3.05 log CFU/g. All food, except from hotdog with mustard cream were detected TCC exceeding 10 MPN/g indicating cross contaminations by poorly sanitized food contact surfaces, poor quality ingredients and improper waste discard policies. E. coli were present only in burger (4 MPN/g), bread roll sandwich (4 MPN/g) and club sandwich (9 MPN/g) signifying the degree of ignorance from the food handlers for maintaining personal hygiene during food preparation. Further, the statistical analysis of the samples denotes a significant (P < 0.05) correlation between TVC, TCC and ECC. S. aureus was detected in four food samples where the highest SAC of 4.48 log CFU/g found to be in rotty. This may be attributed to extensive handling and temperature abuse during storage. However, Salmonella was not detected in any of the analyzed food. The present study demonstrates that the fast short-eat food implies a potential public health hazard and more importantly, the susceptible population is at a higher risk. Given the higher demand for these foods, it stresses the immediate attention of local authority in the area to emphasize on educating food vendors on the importance of adhering to strict food safety regulations and Food Safety Management Systems (FSMS) to ensure that the standard of the food is best achieved from farm to folk.
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    Cost effective research with bioinformatics
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Razick, S.
    Bioinformatics is now a research field itself, in addition to being an interdisciplinary field that develops methods and software tools for analyzing and interpreting biological data. At its introduction in 1970s, ‘bioinformatics’ was coined as a term to describe ‘information processes’ in biological systems, analogous to the term ‘biochemistry’ in which the ‘chemical processes’ in biological systems are studied. The importance of this field came to light with the advent of advanced sequencing techniques that produce large volumes of data. Later it has led to subfields like in silico biology where it helped more discoveries while reducing the need for expensive lab work and clinical trials, for example, in the field of medical sciences. Bioinformatics has a great potential in developing countries like Sri Lanka as it opens up a window to conduct high-end research with a fraction of what the conventional research would cost. It can also be used to design the experiments better, replacing certain steps and to perform data analysis in order to reach the most in depth and complete conclusions.
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    Biosynthesis of silver and zinc oxide nanoparticles from Plectranthus zeylanicus for the development of antimicrobial formulations
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) de Soyza, W.S.G.; Wijayaratne, W.M.D.G.B.; Napagoda, M.T.; Witharana, S.
    With the emergence of microbial resistance to currently employed antimicrobial agents, the recent trend is to search for novel antimicrobial substances from nature. The traditional applications of plants and plant based products as well as metals and metalloids suggest the potential of these sources for the discovery of new antimicrobial compounds with diverse chemical structures and novel mechanisms of action. Moreover, it is reasonable to hypothesize that the metal nano-preparations produced from these plant extracts could offer highly potent antimicrobial properties due to the synergistic effect of the plant extract and the metal nanoparticles. Thus the aims of the present investigation are to evaluate the antimicrobial potential of pharmacologically underexplored Plectranthus zeylanicus (Iruveriya), a plant claimed as an antimicrobial remedy in traditional medicine and the green synthesis of silver and zinc oxide nanoparticles as effective herbal disinfectants. The antimicrobial activity of the n-hexane, dichloromethane, ethyl acetate and methanol extracts of P. zeylanicus was determined by disc diffusion and broth microdilution methods against Enterococcus faecalis, Staphylococcus aureus and Staphylococcus saprophyticus. The dichloromethane extract displayed a MIC value of 31.25 μg/mL against S. saprophyticus and S. aureus while a MIC of 250 μg/mL against E. faecalis. Therefore this potent extract was then utilized for the green synthesis of silver and zinc oxide nanoparticles by treating with AgNO3 and ZnSO4 aqueous solutions respectively. The formation of metal nanoparticles was monitored by the measurement of the absorbance of the reaction mixture within the range of 200-600 nm using an ultraviolet-visible spectrophotometer at different time intervals for a period of three days. The silver nano-preparation displayed high absorbance in the range of 240-260 nm and 420- 440 nm and the absorbance of the reaction mixture increased with time. Similarly, the Zinc oxide nano-preparation has shown a high absorbance at 350-370 nm. Products of the green synthesis were evaporated in hot air oven. The scanning electron microscopy was employed to study the morphology of the nanoparticles. The antimicrobial potential of the nano-preparations will be studied in detail for the development of potent and eco-friendly herbal disinfectant/s.
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    Preliminary study on identification of region of production of Ceylon Tea using concentration of selected elements
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) de Silva, N.I.U.; Madhusha, R.K.D.; Waduge, V.A.; Mewan, K.M.; Amarakoon, A.M.T.
    Sri Lanka is one of the world's leading tea exporters and Ceylon Tea is acclaimed as the best tea in the world due to its unique flavor characteristics. Flavor characteristics of tea are mainly influenced by the variety of tea, climatic conditions and processing methods. Tea is grown in several geographical regions in Sri Lanka and tea produced in those regions acquire distinct flavor characteristics specific to the region. Due to the distinct flavor characteristics, Ceylon Tea fetches higher prices in the international markets than tea produced in other countries. Often Ceylon Tea is blended with tea from other origins and sold as Pure Ceylon Tea to obtain higher prices. In addition, tea produced in particular regions in Sri Lanka are blended with tea produced in other regions of Sri Lanka (e.g. Dimbulla and Uva) which are much sought after teas of Sri Lankan origin. At present, organoleptic assessments are used to identify such adulterations, which could be challenged in courts and arbitration panels. Although not essential, identification of chemical parameters specific to the region of production would facilitate obtaining geographical indications (GI) for tea produced in certain regions such as Dimbulla and Uva in Sri Lanka. Therefore, chemical parameters to distinguish Ceylon Tea from other origin teas and to identify the region of production in Sri Lanka would be invaluable for the marketing of Ceylon Tea. A combination of trace metal content and isotopic ratios of Nitrogen (N), Carbon (C) and oxygen (O) are often used to identify the geographical region of production. Therefore, content of selected metals in tea produced in five regions (Low country, Mid country, Udapussellewa, Up country and Uva) of Sri Lanka was measured as a preliminary investigation to find any relationship with the region of production. Potassium, calcium, manganese, iron, copper, zinc, rubidium, strontium and bromine content of fifteen tea samples representing the five regions were measured using Xray Fluorescence Spectroscopy (XRF) technique. The results obtained, in the present study indicated that there is a direct correlation between the rubidium content of tea and the region of production. Mean Rb content of tea in the five production regions (mg kg-1) were 45.43 (Low country), 39.31 (Mid country), 36.89 (Udapussellewa), 30.98 (Up country) and 20.29 (Uva) on dry weight basis. Tea produced in lower elevations had high Rb content and the Rb content of tea decreased with the increase in elevation. The differences of Rb content in tea could be due to the differences in Rb content in soils in these regions. Results obtained for concentrations of other elements did not indicate any relationship with the region of production. Results of this study indicate that Rb content could be used as one of the parameters for the identification of region of production in Ceylon Tea. Further studies using larger number of tea samples from each region along with soil samples from those regions is required for confirmation of the conclusion.
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    Evaluation of the efficacy of ‘Nimbadi Lepa’ with ‘Pinda oil’ in the management of scaling condition of Psoriasis (Sidhma Kushta)
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wijesinghe, W.A.M.S.; Jayakody, J.A.D.P.P.; Senevirathne, K.N.
    Psoriasis is a skin disease that causes itchy or sore patches of thick, red skin with silvery scales. Usually, the patches appear on elbows, knees, scalp, back, face, palms and feet, but can show up on other parts of body too. This study was conducted to evaluate the efficacy of Nimbādi lepa with Pinda oil in the management of scaling condition of the psoriasis.Study was carried out at Gampaha Wickramarachchi Ᾱyurveda Teaching Hospital,Yakkala.Sixty patients in age between 16-70 years were selected who were randomly divided into three groups A, B and C. All were given selected Ᾱyurveda regimen as an internal mode of therapy. In addition, separate external applications EA1, EB2 and EC3, were given for each group, for a period of one month. Healing effect was monitored by observing the clinical symptom of scaling.. Data were collected by using PASI scale. Clinical outcomes were statistically analyzed using Wilcoxon Sign Rank test and Minitab (V14). All the treatments showed positive response for the symptom of scaling. (P-value = 0.019 for Group A, P-value=0.023for Group B,P-value=0.019 for Group C).Healing effect in each group as percentage was as follows: group A=21%,group B=20%, and group C=50%.Considering all three treatments EC3 Nimbadi lepa with Pinda oil can be recommended as effective external application for the management of scaling of Psoriasis.
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    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.