ICAPS 2023

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Levels of Naphthalene and Phenanthrene in seawater along the coastal belt from Colombo to Mirissa in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Mallikarachchi, K. E. P.; Bandara, K. R. V.; Manage, P. M.
Polycyclic Aromatic Hydrocarbons (PAHs) are pervasive pollutants in marine and coastal settings. Naphthalene (NAP) and Phenanthrene (PHE) are among the sixteen PAHs recognized as priority pollutants by the United States Environmental Protection Agency. Due to their persistence, bioaccumulative capacity, and probable carcinogenicity, PAHs pose a serious threat to the health and wellbeing of humans when ingested. The present study was carried out to evaluate the levels of NAP and PHE in seawater along the coastal belt from Colombo to Mirissa, where coastal water pollution is considered to be high. Seawater samples collected from 19 distinct locations (n=3 each) along the selected area underwent HPLC analysis, followed by organic solvent extraction. Each of these locations provided three replicates, facilitating a reliable evaluation of the concentrations of NAP and PHE. The NAP concentration along the coastal belt was from 1.70 to 15.05 mg/L. The highest NAP concentration was recorded in Mirissa (15.05 ± 0.14 mg/L), followed by Galle Face, Bentota, Rathgama, Wellawatta, Gintota, Galle, Ambalangoda, Weligama, Kalutara, Unawatuna, Ratmalana, Moratuwa, Koggala, Hikkaduwa, Mount Lavinia, Panadura, and Wadduwa. In comparison, the lowest NAP concentration was detected in Dehiwala (1.70 ± 0.00 mg/L). The highest PHE concentration was recorded in Ambalangoda (5.36 ± 0.55 mg/L) followed by Mirissa, Galleface, Weligama, Rathgama, Gintota, Bentota, Galle, Koggala, Unawatuna, Hikkaduwa, Wellawatta, Dehiwala, Ratmalana, Wadduwa, Mount Lavinia, Panadura, and Moratuwa. However, PHE was not detected in Kalutara. Mirissa was heavily polluted, having the highest NAP concentration and the second highest concentration of PHE (5.25 ± 0.03 mg/L). The concentrations of NAP and PHE in all coastal water samples except Kalutara exceeded the maximum permissible concentration (􀂦PAHs = 0.030 μg/L) stated by the Environmental Quality Criteria for the United States. The high concentrations of PAHs might be due to high oil and grease content caused by engine oil leaks from fishing boats and boat repair stations, infrequent oil and sludge spills from nearby industries, unintentional oil spills when refueling, and tributary inflows. Since NAP has a higher solubility in water, the concentration of NAP in seawater is higher than that of PHE. This study provides valuable information for EIA programs and contributes to developing effective strategies to mitigate PAH pollution in coastal waters. Broader studies are recommended to pinpoint the sources of PAHs and explore strategies for reducing environmental emissions.
Pyrolysis of plastic waste into liquid fuel
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Uthpalani, P. G. I.; De Silva, D. S. M.; Weerasinghe, V. P. A.; Premachandra, J. K.
The accumulation of plastic waste in the environment has emerged as a significant global concern. The versatile properties of plastics, such as low weight, low cost and durability which led to their widespread use as substituents for traditional materials like wood, metals, ceramics, and glasses. However, the improper handling and disposal of plastic waste have imposed negative consequences for the environment. The non-biodegradable nature of plastics makes them persist in the environment for extended periods, causing pollution and posing threats to ecosystems. Pyrolysis of plastic waste has been studied extensively in recent years as an effective solution, by exposing the plastic waste to high temperatures in an oxygen-free environment to decompose it into fuel oil, char, and gases. In this study, the waste of four types of plastics samples, low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), and a mixture of these three types of plastics, were subjected to pyrolysis. Lab-scale, low-cost pyrolysis system was used to obtain liquid oils and herein, the non-condensed vapor was trapped into an organic solvent. Thermal pyrolysis or non-catalyzed pyrolysis resulted in a liquid yield of 65.64 ± 5.42 – 79.57 ± 1.66 wt.% at a temperature range of 340 – 360 ℃. Considering catalytic activity, high temperature stability, local availability, and abundance, four types of naturally available minerals were selected as potential catalysts for the pyrolysis of waste plastics. The mineral which resulted in the highest liquid yield was identified as the best-performing catalyst and used for further analysis. The catalyzed process resulted in an increased liquid yield of 71.79 ± 0.99 - 80.29 ± 1.76 wt.% at the temperature range of 290 – 320 ℃. The calorific value of the resulting oil in thermal and catalyzed pyrolysis processes were 10,850 -10,961 Kcal/kg and 10,556 - 11,473 Kcal/kg respectively. This reveals that the mineral selected is an ideal catalyst for pyrolysis of plastics and further indicates the quality enhancement of the fuel produced in catalyzed pyrolysis. Further, the fuel quality indicators; calorific values, density, kinematic viscosity, ash content, and water content of the resulting liquid oils under both catalyzed and uncatalyzed/thermal pyrolysis processes were significantly compatible with commercial grade diesel and kerosene fuel oils.
Assessment of contaminant levels of hazardous toxic metals and subsequent risk analysis in agricultural soil and selected comestibles within a region afflicted by CKDu in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Perera, M. A. S. N.; Kadigamuwa, C. C.; Gunathilaka, V. H. N. M.; Samaraweera, G. A.; Perera, W. P. R. T.; Perera, P. L. R. A.; Liyanage, J. A.; Premaratne, W. A. P. J.
Agricultural commodities constitute a pivotal component of the human daily sustenance, yet they are susceptible to contamination by pernicious heavy metals, notably Hg, Cd, Pb, and As. Consequently, agricultural products represent a substantive source of apprehension for human well-being and health. This study aims to evaluate related risk indices of agricultural soils (n=25) and selected comestible grains, namely Oryza sativa (n=25), Vigna radiata (n=25), Vigna unguiculata (n=25), and Vigna unguiculata subsp. (n=25), within the endemic region of Nikawewa Grama Niladhari Division (GND) in North Western Province (NWP) and the reference region, Wewagedara GND in NWP where no evidence for Chronic Kidney Disease of unknown etiology (CKDu). The concentrations of metals in the collected samples were determined by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and based on that risk indices were calculated. The mean geo-accumulation index (Igeo) for four metals in soil was As - 0.82, Cd - 1.47, Cu - 0.91, and Pb 1.31. That indicates no anthropogenic activities related to As, Cd and Cu while Pb is responsible for moderate pollution in endemic area. Estimated Daily Intake (EDI) values for these heavy metals were calculated with respect to the all grains. EDI means of As and Pb in the endemic and the reference areas for all grain samples were within the Tolerable Daily Intake (TDI) set by United States Environmental Protection Agency (USEPA) (As-0.300 􀁐g/kg/day) and World Health Organization (WHO) (Pb-3.600 􀁐g/kg/day) while Cd (EDI in endemic area; Oryza sativa-6.385 􀁐g/kg/day, Vigna unguiculata-3.386 􀁐g/kg/day and Vigna unguiculata subsp.-3.866 􀁐g/kg/day) highly exceeded the tolerable weekly intake (TWI) of European Food Safety Authority (EFSA) (Cd-2.5 􀁐g/kg/week) in both areas. EDI of Cr in rice samples (1.138 􀁐g/kg/day) in endemic area exceeded the TDI set by EFSA (1.0 􀁐g/kg/day) and all other values of Cr were below the TDI in both areas. According to the USEPA (intolerable cancer risk (CR) - > 1 x 10-4) cancer risk exist for all these staple grains. Igeo of Pb in the soil, raising concerns about their bioavailability and uptake by the food crops and EDI were indicated the long-term consumption of these foods especially Oryza sativa poses a serious threat to human health. Implementing proper soil management practices, monitoring heavy metal levels in crops, and raising public awareness about safe consumption practices are crucial steps towards mitigating the risk of CKDu.
Sea moss as an alternative gelling agent to develop a cost-effective in vitro culture medium for the propagation of Phalaenopsis cv. Pink lip
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Wishwakulathil, D. T.; Priyadarshan, A. I. S.; Senanayake, S. P.; Lakmali, G. B. T.
Genus Phalaenopsis is an ornamental orchid with the greatest commercial importance in the world floriculture industry. The propagation of Phalaenopsis is difficult by conventional breeding due to delayed flowering and uneven characteristics of flowers. Therefore, conventional Phalaenopsis cultivation is ineffective for large-scale production. At present, the tissue culture technique is extensively used for the mass propagation of Phalaenopsis. Tissue-cultured plants are more expensive than traditionally propagated plants due to the high cost of the chemicals used for the preparation of tissue culture media. Agar is widely used as a gelling agent and the most expensive ingredient in the preparation of tissue culture media. Developing a cost-effective invitro culture media using low-cost components is one strategy to reduce the production costs of tissue-cultured plants. The use of alternative gelling agents to replace the agar can highly contribute to reducing the cost of in-vitro culture media in tissue culture than other components. The main component of sea moss is carrageenan, a gelatinous substance used to thicken or as a solidifying agent. The ability of carrageenan-based hydrogels to produce thermos-reversible gels and viscous solutions makes them a desirable option for extensive use as a gelling agent. The objective of the present research was to assess the performance of sea moss as an alternative gelling agent to determine the effectiveness for in vitro propagation of Protocrom-like bodies (PLBs) of Phalaenopsis cv. Pink lip. Growth performance of PLBs of Phalaenopsis cv. Pink lip was used to assess the effect of sea moss as an alternative gelling agent. PLBs (0.020g) were transferred to ½ MS medium containing agar as a gelling agent, and ½ MS medium containing sea moss as a gelling agent. Cultures were maintained for four months and the growth performance of PLBs was evaluated, with fresh weight as a parameter at 30 days intervals. There was no significant difference observed in the mean fresh weight of PLBs throughout the fourmonth period, incubation in ½ MS medium containing agar, and medium containing sea moss as an alternative gelling agent. Moreover, there was no significant difference between the contamination percentages of the agar-containing medium and sea moss-containing medium. According to the cost calculation, the cost reduction resulting in the medium with sea moss as an alternative gelling agent was 79.81% compared to the conventional agar as the gelling agent. In conclusion, the application of sea moss as a gelling agent in tissue culture media can be utilized to achieve the optimum benefits for in vitro propagation of PLBs of Phalaenopsis cv. Pink lip. Based on the findings, sea moss can be recommended as a cost-effective alternative gelling agent for the propagation of Phalaenopsis cv. Pink lip using protocorm-like bodies.
Development of robust superhydrophobic plastic sheets using diatomaceous earth
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Jayaweera, D. H. T. S.; Maddumaarachchi, M.; Egodage, S. M.
Superhydrophobicity is the ability of a surface to repel water droplets. Surfaces that exhibit a static water contact angle (WCA) exceeding 150° and a sliding angle less than 10° can be defined as superhydrophobic surfaces. The unique properties of superhydrophobicity include selfcleaning, drag reduction, anti-fouling, anti-corrosion etc. Several methods are employed in developing superhydrophobic surfaces, yet incorporating a superhydrophobic filler is a more convenient method which is utilized in this research. This study discusses a progressive development of a method to enhance the hydrophobicity of plastic substrates using Diatomaceous Earth (DE) as the superhydrophobic filler. In this study, the focus was on developing superhydrophobic plastic substrates with enhanced mechanical durability and stability since one of the primary concerns of superhydrophobic surfaces is their mechanical performance. The fundamental requirements for producing superhydrophobic substrates are nanoscale surface roughness and low surface energy. The nanoscale surface roughness was obtained through DE, whereas low surface energy was attained by treating DE with hexadecyltrimethoxysilane (HDTMS). The surface wettability and morphology were evaluated through WCA measurements and scanning electron microscopy (SEM) analysis, respectively. By using HDTMS to DE ratio of approximately 38% (w/w), superhydrophobic properties were achieved for treated DE with WCA around 160°. In the first approach, treated DE was incorporated into plastic substrates through melt mixing process to achieve the inbuilt hydrophobic property. Incorporation of treated DE into high-density polyethylene through melt mixing process resulted in hydrophobic plastic sheets possessing WCAs of around 99° with treated DE particle loading of 10%. The treated DE amount was not further increased due to the reduction of mechanical properties of the plastic sheet. The hydrophobicity did not reach the expected level. As revealed by SEM and SEM coupled with energy dispersive X-ray analysis, the DE particles had been destroyed and trapped within the plastic matrix during the melt mixing process. Compression molding technique was also employed to fabricate a thin layer of treated DE on the plastic substrates. Yet, it was observed that the adhesion between the DE layer and the plastic substrate was not satisfactory and the WCAs were drastically reduced after removing the loosely bound DE powder of the coating. By utilizing the solvent casting method and a subsequent lamination step, robust superhydrophobic coatings on poly(vinyl chloride), which can be considered as a polar plastic substrate, were successfully developed. The coating consisted of treated DE particles held together by an epoxy resin binder, ensuring both the cohesion of the coating and its robust adhesion to the substrate. The prepared coatings showed a remarkable level of superhydrophobicity, surpassing the threshold WCA of 150° and good mechanical properties.
Investigation of antioxidant and antityrosinase activities of Premna serratifolia
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Katpaharajah, G.; Weerasiri, K. C.
In recent times, cancer and hyperpigmentation have been the most problematic issues faced by the people. As cancer is caused mostly by the free radicals in the body, antioxidants, which are radical scavengers, may reduce the mutations in the body. Hyperpigmentation is reduced by the compounds inhibiting the tyrosinase enzyme’s activity. So, the compounds responsible for antioxidant and antityrosinase activities are analysed. Many harmless bioactive compounds responsible for many bioactivities are present naturally in plants. For this research work, the Sri Lankan species Premna serratifolia was chosen as the focal subject with specific attention to its leaves, traditionally employed for alleviating ingestion related issues. Considering the absence of prior research on this plant in previous studies, the leaves and twigs were chosen to determine the antioxidant and antityrosinase activities. The leaves were extracted by maceration process (cold extraction) through a sequential extraction using hexane, ethyl acetate and methanol. The twigs were extracted using the Soxhlet apparatus (hot extraction) through a sequential extraction using ethyl acetate and methanol. The antityrosinase activity was determined by the tyrosinase enzyme’s catalytic reactions. The methanol extracts of leaves and twigs show higher antityrosinase activity (the IC50 value of leaves is 6.83 ± 1.31 mg/mL and the IC50 value of twigs is 8.20 ± 5.54 mg/mL) than their respective ethyl acetate extracts (IC50 value of leaves is 87.06 ± 54.90 mg/mL and IC50 value of twigs is 168.82 ± 2.60 mg/mL). The methanol extracts of leaves and twigs show similar antityrosinase activity within the concentration range of 0.200 – 1.600 mg/mL. At a concentration of 0.025 mg/mL, the methanol extracts of leaves and the twigs show higher antityrosinase activity than the standard Kojic acid yet, the twigs show more than the leaves. In ethyl acetate extracts, at a concentration of 0.025 mg/mL, twigs show higher antityrosinase activity than the standard Kojic acid and the leaves. The DPPH-radical scavenging method was employed to determine the antioxidant activity. The EC50 values of ethyl acetate extracts of leaves and twigs are higher (2.63 ± 1.61 mg/mL and 3.89 ± 1.57 mg/mL, respectively) than their respective methanol extracts (1.21 ± 0.64 mg/mL and 1.10 ± 0.65 mg/mL). Despite the methanol extracts having lower EC50 values, indicating high potent antioxidant activity, the ethyl acetate extracts of leaves and twigs exhibit higher antioxidant activity within the concentration range of 0.025 – 0.800 mg/mL. In ethyl acetate extracts of leaves and twigs, at a concentration of 0.025 mg/mL, the leaves show highest antioxidant activity than the twigs, but the twigs show higher antioxidant activity than the leaves within the concentration range of 0.100 - 0.200 mg/mL
Spatial distribution of soil and water quality in Eldeniya - East grama niladhari division
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Deraniyagala, P. E. P. S.; Heenkenda, H. M. D. S. D.; De Silva, R. C. L.
Water is becoming a consequential part of the daily life of humans. Therefore, mapping of soil and water quality parameters is required for regular monitoring of them to provide the necessary evidence to make decisions on managing water and soil quality today and in the future. Furthermore, mapping soil and water quality parameters is necessary for environmental monitoring, agricultural management, land use planning, water resource management, and conservation efforts. This research analyzes soil and water quality parameters in the EldeniyaEast grama niladhari division, Gampaha district. Fifty-six samples of soil and water were collected from the selected area. Water quality parameters pH, conductivity, nitrate content, phosphate content, and hardness were analyzed, and soil quality parameters pH, nitrate content, soil organic matter content, Na+, K+, and Ca2+ content in the soil were analyzed. Then their spatial distribution was represented as contour maps. pH was analyzed using a pH meter and the pH of water samples lies between 3.79 – 7.18. Except for one, all the other water samples gave acidic pH. Suggesting that Eldeniya-East has almost all acidic water sources. The conductivity of water samples was measured using a conductivity meter and the obtained values lie between 54.0 µS/cm – 403.0 µS/cm. All the samples gave extremely low conductivity values. Water-soluble phosphate was not detected in the water samples. This suggests that water sources within this area are not contaminated with excessive amounts of phosphates. Nitrate content was measured using an ionselective nitrate electrode and the obtained values lie between 59.5 ppm to 168.0 ppm. According to EPA, this area's water sources have nitrate contents higher than the safe levels for drinking water. The calcium hardness of water samples lies between 0.00 – 59.92 mg CaCO3/L, and Mg2+ was not detected. According to Sawyer and McCart's classification, all water samples are categorized as soft water. The pH of the soil samples lies between 3.07 – 6.68 where all are acidic pH values. Considering obtained soil and water pH values, it can be said that the study area has a considerable acidic nature. Nitrate content in soil samples lies between 52.2 – 217.0 ppm and a linear relationship exists between soil nitrate content and the water nitrate content. SOM of soil samples was measured using the Walkley–black method, and SOM lies between 0.000 – 12.930 %. According to the results, this area contains water-soluble calcium in a range of 0 - 2 mg/L, water-soluble sodium in a range of 6 - 18 mg/L, extractable sodium in a range of 1 - 56 mg/L, water-soluble potassium in a range of 1 - 12 mg/L and extractable potassium in a range of 9 – 108 mg/L. This analysis, which has been conducted as a pilot project covering only one grama niladari division can be further extended to map the entire country which then can be used for the continuous investigation of soil and water quality parameters.
Investigating the ability to purify wastewater by using Activated Porous Carbon (APC) produced from waste surgical masks
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Wellalage, D.K.; Bandara, L. R. A. K.; Dasanayake, N. L.
Since the early days of the year 2020, most people have been wearing face masks to protect themselves from COVID 19 pandemic. As a result of that, another environmental problem arises with waste face masks all over the world. Therefore, this study aims to convert commonly used, waste polypropylene surgical masks, into Activated Porous Carbon (APC) and compare its wastewater treatment applications with commercially available activated carbon (AC). Waste polypropylene surgical masks can be converted into APC through the two main processes called sulfonation and carbonization. First, waste masks were mixed with concentrated H2SO4 and heated under the temperature of 110 °C for the sulfonation. Then, the collected samples were carbonized by mixing with KOH in different mass ratios 1:1, 1:1.5 and 1:2 (samples: APC 1, APC 2 and APC 3 respectively) and again these samples were heated under the temperature of about 400 °C. Adsorption ability of activated carbon depends on porosity, surface area of the sample and also size of the substance that we want to remove from wastewater. According to the Scanning Electron Microscope (SEM) images of the samples, even though there is no any considerable porous structure on the all APC samples, roughly surface area of the APC 1 sample is higher than the other APC samples. This can be caused to the higher adsorption of the APC 1 sample. Here, the adsorption ability of the APC samples was tested by using two chemical dyes, four cations and four anions. According to the concentration reduction results of commercial AC sample and APC samples, a high concentration reduction was obtained from APC 1 for both Congo red and Methylene blue dyes. Molecular size of the two types of dyes can be caused to those results. Even though these two dyes are organic and aromatic compounds molecule size of the Congo red is larger than the Methylene blue. It allows to adsorb Congo red more effectively than the Methylene blue. When considering the results obtained for the cations and anions adsorption, APC samples showed lower capability compared to commercial AC. Among the tested APC samples, again APC 1 had the best adsorption ability. Further, obtained results for the ion adsorption clearly indicated there is high capability to adsorb large substances effectively than small substances. Ions in the solution directly affect the conductivity of the solution. Therefore, in this work conductivity values of three collected water samples were measured by changing the contacted time with the sample. According to the decrement of conductivity values, there is a considerable effect on the adsorption rate from the contacted time. Further, those conductivity results also showed the best ion adsorption ability of APC sample1 than the other samples. Hence, APC 1 sample with a 1:1 KOH mass ratio can be identified as the best adsorbent with good surface structure.
A quantitative characterization of sector-wise performance interdependencies in stock market using changepoint and performance-induced distant clustering
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Kavishka, R.T.; Liyanage, U. P.; Hewaarachchi, A. P.; Dissanayaka, D. M. P. V.
The Colombo Stock Exchange (CSE) is the Sri Lankan marketplace for companies to trade their stocks to the public. There are 19 sectors in the CSE before the Global Industry Classification Standard (GICS) classification. The stock market has become a significant icon in most of the country’s economy. Due to the enhancement of the data science discipline, quantitative research on the stock market has gained popularity among scholars in the recent past. Most of the studies were conducted to predict the value of a stock and its volatility. However, this study explored potential performance dependencies among the 19 industrial sectors registered at the CSE. In known literature, this scope has not been addressed quantitatively. The sectorial All Share Price Index (ASPI) is used to characterize the sector interdependencies, as the volatility of ASPI implies the sector performance at a given time or a short period. Because diverse sector movements can offset each other, leading to a stable index, while extreme sector-specific events or trends can result in increased index volatility. The ASPI indices published by CSE from 2005 to 2019 were considered in the analysis. The persistency of ASPI volatility in a compact interval indicates the consistency of the performance in each sector. Thus, the comparison of volatility changes and their changing time, i.e., changepoint analysis, describes the changes in the sectorial performances. Consequently, the interdependencies among the sector-wise performances can be recognized by the emerging patterns of the changepoints, i.e., the clustered behaviour of the changepoints. Through this approach, the investigation seeks to identify significant transitions or shifts in the behaviour of each sector. Non-parametric methods were employed in the identification of the changepoints of the ASPI series. The standard clustering approaches could not be utilized in grouping the changepoints as the clustering metrics defined by the variation of performances are interconnected. Thus, a new clustering approach was developed using a cluster performance-induced distant measure defined based on a reference industrial sector. This analysis resulted in interdependency among the industrial sectors. Further, variation patterns among the changepoints were identified using interval scaling, and dependent industrial sectors were identified with the help of the performance-induced distant clustering approach. For example, the Bank Finance & Insurance, Telecommunication, and Trading sectors exhibited strong interdependencies. Also, the Construction & Engineering, Oil palms, and Hotel & Travels sectors exhibited strong interdependencies. So far, in qualitative relations, these interdependencies were merely recognized by the gut feelings of financial analysts. Nevertheless, this study provides a clear quantitative characterization of performance dependencies, and thus, the findings are crucial for determining investment strategies and minimizing risk in stock exchanges.
An application of time series techniques to forecast the Open market weekly average retail price of lime in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Wickramarathne, R. A. S.; Wickramanayaka, M. P. A. T.; Mahanama, K. R. T. S.; Chandrasekara, N. V.
Limes are known for their acidic and tangy flavour and are commonly used in cooking, as a garnish, or to add flavour to drinks. The lime market in Sri Lanka is highly volatile, with prices fluctuating significantly on a weekly basis. In this research study, the main objective is to forecast the weekly lime price in Sri Lanka. Even though some research has been conducted on forecasting fruit prices in Sri Lanka, there is currently a lack of research on forecasting lime prices. The weekly price of lime from 1st week of January 2010 to 3rd week of February 2023 was considered for this study (632 observations). The first 600 observations were used as the training set and reserved data were used as the testing set. The time series plot of the weekly lime price of Sri Lanka indicates a slight upward trend and a non-constant variance with a seasonal pattern. The presence of a seasonal pattern motivated the development of a Seasonal Autoregressive Integrated Moving Average (SARIMA) model. When comparing Akaike’s Information Criterion (AIC), ARIMA(1,1,2)(0,1,1)[24] generated the minimum AIC value (-1.125469). Assumptions of autocorrelation and heteroscedasticity were not violated and the normality was violated. Although, the performance measures of ARIMA(1,1,2)(0,1,1)[24] were very low, ARIMA(1,1,2)(0,1,1)[24] was identified as the better model with mean absolute error of 40.799, mean absolute percentage error of 7.543, and root mean squared error of 49.793. The results obtained from this analysis would be helpful to mitigate price risks and uncertainties in the lime industry.
Characterization of adsorption properties of naturally occurring clay deposits in Mannar District to remove lead and cadmium from aquatic systems
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Chandrasiri, D. K.; Kadigamuwa, C. C.
Water is a fundamental resource for life on earth. Water pollution by heavy metal contamination has a major negative impact on human health due to its toxicity. To remove heavy metals from aquatic environments several methods have been implemented. From these methods, use of natural clays for adsorption of heavy metals is considered to be environmentally friendly and cost effective method. Montmorillonite is one major type of natural clays which is well known for its adsorption ability. Therefore, this study was basically focused on assessing the potential of lead and cadmium adsorption by MMT-rich clay in different places in Sri Lanka. Three soil samples from selected places of Mannar District were collected and conditions were optimised for Pb2+ and Cd2+ adsorption. Then the adsorption was assessed using Atomic Adsorption Spectrophotometer. 100 mg/L initial concentration, 0.10 g adsorbent dosage, and pH 4 as optimum conditions for Pb2+ adsorption, whereas 100 mg/L initial concentration, 0.10 g adsorbent dosage, and pH 6 as optimum conditions for Cd2+ adsorption were observed. Langmuir constants obtained for Pb2+ and Cd2+ were -1.233 L/mg and 0.0477 L/mg. Freundlich constants obtained for Pb2+ and Cd2+ were 2.489 mg/g and 0.764 mg/g respectively. Based on the values obtained for the constants, 1/n, qmax, and RL, it was assumed that both metal ions show multilayer adsorption on a heterogenous surface, which favours Freundlich isotherm. Optimized conditions were applied to the soil samples collected from Giant’s tank, Marvelankeni, and Allavankai areas areas of Northern province. Reduction percentages obtained for adsorption of Cd2+ by soil samples from Giant’s tank, Marvelankeni, and Allavankai areas were 91.385%, 98.381%, 68.152% respectively and adsorption capacities were 111.239 mg/g, 119.755 mg/g, 82.969 mg/g respectively. Reduction percentages obtained for adsorption of Pb2+ by soil samples from Giant’s tank, Marvelankeni, and Allavankai were 48.472%, 30.561%, 58.481% respectively and adsorption capacities were 211.807 mg/g, 133.561 mg/g, 255.286 mg/g respectively. The values obtained were compared with the control sample (reduction percentages 75.633%, 83.751% respectively for Cd2+ and Pb2+), adsorption capacities 92.076 mg/g and 365.986 mg/g respectively for Cd2+ and Pb2+. Based on these results, there might be a potential of using Montmorillonite rich soil in Mannar district to remove Pb2+ and Cd2+ from aquatic systems.
Effects of a commercial probiotic incorporated feed on growth performance and nutrient digestibility of fancy guppy, Poecilia reticulata (Poecilidae)
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Dissanayake, D. S.; Epa, U. P. K.; Kumara, K. R. P. S.
The ornamental fish industry is one of the most thriving industries worldwide. The incorporation of probiotics into the feeds to enhance the production performance of cultured aquatic organisms is a novel implementation of science and technology. The present study was conducted to investigate the effects of a commercial probiotic incorporated feed on the growth performance and nutrient digestibility of Poecilia reticulata. Three experimental diets (T1- 1.0 x 10-1 cfu/mL, T2- 1.0 x 102 cfu/mL, and T3- 1.0 x 105 cfu/mL of probiotic concentration with four strains of Bacillus subtilis and a control diet (without the probiotic) were fed to fish in three replication glass tanks (30 cm x 15 cm x 30 cm) for 75 days. In each tank, ten P. reticulata with weight and length of 0.09 ± 0.00 g and 0.9 ± 0.00 cm respectively, were stocked after one week of acclimatization. Fish were fed twice a day at 2% of their body weight. Dissolved oxygen (DO) and pH were measured weekly and the standard length and weight of fish were measured biweekly. Fecal matter was collected twice a week from each experimental tank. The nutrient digestibility of P. reticulata was determined using chromic oxide as an inert marker. The proximate composition of the diets was analyzed using standard methods. DO and pH were not significantly different between the treatment and the control tanks (p>0.05, One-way ANOVA) and were within the optimum ranges for guppy (DO> 6 mg/L, pH 6.8- 7.8). Incorporating the probiotic into the commercial feed positively affected the specific growth rate (SGR), average daily growth (ADG), % body weight increase (% BWI), and % total length gain (% TLG) of P. reticulata. T3 had the best growth performance with the highest final weight (3.25± 0.78 g), length (2.6 ± 0.06 cm), %SGR (1.69 ± 0.31), ADG (0.03 ± 0.01 g/day) and % BWI (71.28 ± 6.25). The lowest final weight (2.084 ± 0.22 g), length (1.8 ± 0.15 cm), % SGR (1.15 ± 0.14), ADG (0.02 ± 0.00 g/day), % BWI (56.51 ± 4.30) were recorded in the fish fed the control diet. All the growth parameters were significantly higher in the T1, T2 and T3 than in the control (p>0.05, One-way ANOVA). There was no significant difference in the nutrient digestibility of P. reticulata between each treatment and the control (p>0.05; One-way ANOVA). Further, the proximate analysis showed no significant difference in the crude protein and ash content among the different experimental feeds (p>0.05; One-way ANOVA). The commercial probiotic used in the study did not affect the nutrient digestibility of P. reticulata, water quality in rearing tanks or proximate composition of experimental feeds. The incorporation of a commercial probiotic into the diet of P. reticulata significantly increased its growth performance.
Assessment of level of public knowledge, attitude, and perception towards sustainable mangrove forest conservation: a case study from Negombo region, Sri Lanka
(Assessment of level of public knowledge, attitude, and perception towards sustainable mangrove forest conservation: a case study from Negombo region, Sri Lanka, 2023) Wickramasingha, W. S. B.; Perera, W. W. A. M. R.; Kodithuwakku, K. C.; De Silva, K. V. N. T.; Karunarathne, D. M. S. D.
Mangroves have been an essential vegetative component not only in sustaining the balance of ecosystems but also in providing significant socio-economic benefits to the local communities such as fish, timber, and tourism opportunities to the local communities. Quantifying knowledge, attitudes, and perception (KAP) supports sustainable mangrove conservation by informing conservation efforts to address local needs and priorities and monitoring interventions' effectiveness over time. Thus, this study aims to determine the level of knowledge, attitudes, and perceptions of the public toward sustainable mangrove forest conservation in the Negombo region, Sri Lanka. Prior to data collection, a pilot study was conducted in the study area with 40 respondents and Cronbach's alpha (α = 0.819) reliability test was followed to test the reliability of the data. Data were collected via face-to-face interviews with randomly selected 395 respondents living near and around the northern region of the Negombo lagoon, which involved 8 Grama Niladhari Divisions. 51.39% of the individuals were male, while the remaining 48.61% were female, reflecting a commitment to gender equality. A Likert scale and correlation analyses were implemented using SPSS version 26 software to determine the community's knowledge, attitude, and perception (1-lowest and 5-highest). The finding shows that the level of knowledge of the community on the importance of sustaining mangrove forests was high from 3.92 to 4.72, the level of attitude was between 3.2 to 4.88, and the perception components from 4.47 to 4.83. There were significant gender differences in both attitude and perception toward mangrove forest conservation, with the female respondents achieving better scores than the male respondents, although there was no significant difference in their knowledge levels. Also, about 96.2% of respondents agree that the loss of mangroves will have negative impacts on the environment and the economics of the livelihood. Furthermore, most respondents believed that chemical pollution, illegal clearing, and development activities have a significant impact on the degradation of mangroves in the area. The correlation test showed that there was a strong positive correlation between knowledge and attitude (r = 0.901, p < 0.001), knowledge and perception (r = 0.795, p <0.001), and attitude and perception (r = 0.864, p < 0.001) respectively. They suggest that the most effective approach for preserving this ecosystem's survival is to engage in mangrove replanting through proper scientific monitoring, while also recommending the rectification of policy deficiencies and the execution of comprehensive strategies for mangrove conservation. The findings from this study may provide valuable information for future research, as well as assist government and stakeholders in enhancing the effectiveness of campaigns and programs focused on the sustainable management of mangrove forests.
Preliminary study of antioxidant and anti-inflammatory properties of mistletoe (Dendrophthoe falcata) on mango host plant (Mangifera indica).
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Raseena, M. T. F.; Kadigamuwa, C. C.
Dendrophthoe falcata is a common mistletoe plant that has widespread use in Sri Lankan traditional medicines. With the escalating incidence of cancer, asthma, and chronic inflammatory ailments among patients, the exploration of natural remedies in developing nations has become increasingly important. Despite existing research focusing on the chemical composition and biological activities of mistletoe plants in general, a critical gap exists in understanding the specific anti-inflammatory and antioxidant properties of Dendrophthoe falcata when it thrives on its particular host, Mangifera indica. This preliminary study aims to investigate the antioxidant and anti-inflammatory properties of mistletoe, Dendrophthoe falcata leaves grown on the host, Mangifera indica in Sri Lanka. The methanolic extracts of Dendrophthoe falcata and Mangifera indica leaf samples were prepared using the cold extraction method. The antioxidant activity was assessed through the Folin-Ciocalteu assay, ammonium colourimetric method, 2,2- diphenylpicrylhydrazyl (DPPH) assay, and ferric-reducing power assays. Anti-inflammatory action was evaluated using heat-induced hemolysis and albumin denaturation assays. Pearson’s correlation test was performed to determine whether there is a linear relationship between total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity, antiinflammatory properties of Dendrophthoe falcata and Mangifera indica. A two-sample t-test was done to compare the results of TPC and anti-inflammatory and antioxidant properties of Dendrophthoe falcata and Mangifera indica to identify whether these values of mistletoe significantly vary from the host. TPC and TFC of mistletoe were determined to be 1531.0 ± 44.3 mg of gallic acid equivalents per g of extract and 210.7 ± 15.9 mg of catechin equivalents per g of extract through Folin-Ciocalteu assay, ammonium colourimetric method respectively. Mistletoe exhibited an IC50 of 239.70 ± 27.99 µg/mL for DPPH scavenging activity and an EC50 of 6921.0 ± 2419.0 µg/mL for ferric-reducing power. Additionally, mistletoe demonstrated an IC50 of 554.1 ± 42.4 µg/mL for antihemolytic activity and 0.45 ± 0.05 mg/mL for protection against albumin denaturation. Pearson’s correlation analysis revealed that phenols contribute to antioxidant activities. Furthermore, the presence of phenols and flavonoids contributed to the antiinflammatory properties. A t-test comparison between mistletoe and its host plant for bioactive compounds, antioxidants, and anti-inflammatory properties indicated that mistletoe’s bioactive compounds and their antioxidant and anti-inflammatory properties are significantly different from host plants. Dendrophthoe falcata leaves emerge as a promising source of anti-inflammatory and antioxidant properties. This avenue of study bears substantial potential for unlocking novel therapeutic benefits and can be further pursued by determining the chemical structure of the specific bioactive compounds responsible for anti-inflammatory and antioxidant properties.
Identification of factors leading to elephant deaths in human-elephant conflicts
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Lakshitha, W. A. D. M.; Chandrasekara, N. V.; Kavinga, H. W. B.; Withanage, N.
Human-elephant conflicts (HEC) have emerged as one of the main challenges that Sri Lanka faces throughout several decades. According to the official data of the Department of Wildlife Conservation (DWC), the number of elephant deaths is higher than the number of human deaths due to HEC per year. This research focused on the North Central Province, where the highest number of elephant deaths have been recorded. Hence, the objectives of this research are to identify the main factors that have affected the deaths of elephants and to identify suitable models to predict the causes of elephant deaths due to human-elephant conflict. Although there has been much research related to HEC worldwide, no published research studies were found in the literature that utilized advanced statistical techniques such as Multinomial Logistic Regression (MLR), LASSO regression, Decision Tree (DT), Support Vector Machine (SVM), and Probabilistic Neural Network (PNN) for their studies. However, this research will address that research gap by constructing models for classifying the causes of elephant deaths resulting from HEC. Data was collected from various departments, including DWC, the Department of Meteorology, and the crop calendar of the Department of Agriculture. Furthermore, Pearson's Chi-square and Fisher's exact tests were used to identify the association between the cause of death and influencing factors. Five variables, including the elephant age group, grass levels, gender, rainfall season, and place of death, were found to significantly influence the causes of death of an elephant. MLR and Data Mining (DM) techniques were initially utilized, but due to multicollinearity arising in MLR, the LASSO technique was employed as a remedial method. To overcome the class imbalanced problem, 90% of the data were randomly selected for model building while maintaining the class ratio of the response variable, and the remaining 10% of the data were used for testing. Performance measures, overall classification accuracy (OCA), and Misclassification Percentage of Critical Cases (MPCC) were used to evaluate and compare the classification potential of models. Models such as final MLR, LASSO, DT, SVM with Polynomial and Gaussian Kernels, and PNN with spread 0.801 illustrated 42.30%, 50%, 53.84%, 69.23%, 73.07%, and 73.07% of OCA. In addition, the above models showed 34.61%, 30.76%, 7.69%, 11.53%, 19.23%, and 26.92% MPCC respectively. Finally, the SVM model with Gaussian Kernel exhibited high OCA (73.07%) with 19.23% of MPCC as the better model since the PNN showed a high MPCC of about 26.92%. These findings will be helpful for authorities in their future and existing projects.
A comparative study of the nutritional, pharmaceutical and photoprotective properties of almond (Prunus dulcis) and tropical almond (Terminalia catappa) nuts
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Panditharathna, G. M.; Rajapakse, C. S. K.
This study focuses on the comparison of nutritional, pharmaceutical and photoprotective properties of methanolic extracts of Terminalia catappa (TC) commonly known as tropical almond or ‘kottamba’ and Prunus dulcis (PD) nuts (almond). TC is a popular folk medicine and has several proven biological properties. The objective of this research work was to evaluate in vitro antioxidant, α-amylase inhibitory, anti-lipase activities, and photoprotective properties of TC and PD nuts. First, the proximate composition of powdered nuts was determined by standard methods. Next, the phytochemicals in powdered nuts were extracted to methanol by cold extraction and phytochemical screening was conducted using standard biochemical tests. Further, 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS), and the ferric reducing power assays were used to determine the antioxidant activity of methanolic extracts of nuts. The α-amylase inhibitory activity and antilipase activity of extracts were determined by α-amylase inhibitory assay and anti-lipase assay respectively. Finally, the photoprotective property of the extracts was determined by a UV-Visible spectrophotometric method. Results showed that TC was significantly high in moisture (11.8%) with p value (0.00000097) less than 0.05 and low lipid content (32.16%) with p value (0.0000016) less than 0.05. There was no significant difference (p > 0.05) recorded in crude fiber (15.66% and 14.33%) (p value = 0.2000), protein (36.15% and 33.85) (p value = 0.2298), and carbohydrate (11.85% and 12.23%) (p value = 0.2690) for TC and PD, respectively. The present study revealed that both nuts are rich in phenols, alkaloids, flavonoids, steroids, terpenoids, glycerides, saponin, cardiac glycosides and triterpenes. PD extract showed significantly higher DPPH radical scavenging activity with an IC50 value of 78.55 ± 5.10 μg/mL while TC extract showed an IC50 of 89.22 ± 4.40 μg/mL. The ABTS radical scavenging activity of PD, with a value of IC50 57.19 ± 0.32 μg/mL is significantly higher than that of TC, (IC50 74.36±3.34 μg/mL). The ferric reducing power of TC (FRAP values of 41.6±0.23 mg potassium ferricyanide equivalents per gram (PFE/g) of dried extracts) is significantly lower than that of PD (39.15±0.21 mg PFE/g of dried extracts). The α-amylase inhibitory experiment demonstrated that the extracts of TC with an IC50 113.4±1.56 μg/mL and PD with IC50 128.3±1.12 μg/mL have inhibitory effects on the enzyme. In the anti-lipase assay, both samples showed anti-lipase activity (TC - 190.4 ± 5.22 μg/mL, and PD, 167.33 ± 6.35 μg/mL) indicating their potential to block the lipase enzyme, which aids in weight reduction. Compared to a commercially available sunscreen, both extracts exhibited moderate UV protection with SPF values of 14.52 ± 2.34 (TC) and 12.92 ± 1.78 (PD). These results suggested that not only PD, but also TC nuts are a great source of antioxidants, anti-diabetics, and antiobesity compounds despite not being commercially utilized. Therefore, Terminalia catappa can be used as an alternative to Prunus dulcis in food and pharmaceuticals.
Controlled 𝑲 −frames in quaternionic setting
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Khokulan, M.; Ramakrishnan, R.
Quaternion is an extension of complex numbers from the two-dimensional plane to fourdimensional space and forms non-commutative division algebra. A feature of quaternion is that the multiplication of two quaternions is non-commutative, from the non-commutativity the quaternionic Hilbert spaces are defined in two ways such as right quaternionic Hilbert space (𝑉𝐻𝑅) and left quaternionic Hilbert space (𝑉𝐻 𝐿). 𝐾 −frames are more general than ordinary frames in the sense that the lower frame bound only holds for the elements in the range of 𝐾, where 𝐾is a bounded linear operator in 𝑉𝐻 𝐿. Controlled frame is one of the newest generalizations of the frame which has been introduced to improve the numerical efficiency of interactive algorithms for inverting the frame operator. In this research, the notion of a controlled 𝐾 −frame is introduced in left quaternionic Hilbert space along the lines of their real and complex counterparts and some of their properties were analysed. Let 𝑉𝐻 𝐿 be a left quaternionic Hilbert space, 𝐾 ∈ 𝐵(𝑉𝐻 𝐿) and 𝐶 ∈ 𝐺𝐿+(𝑉𝐻 𝐿), where 𝐵(𝑉𝐻 𝐿)is the set of all bounded linear operators and 𝐺𝐿+(𝑉𝐻 𝐿) is the set of all positive bounded linear operators in 𝑉𝐻 𝐿 with bounded inverse. A sequence of family 𝛷 = {𝜑𝑘}𝑘∈𝐼 in 𝑉𝐻 𝐿 is called a 𝐶 − controlled 𝐾 − frame for 𝑉𝐻 𝐿 if there exist constants 𝑚, 𝑀 > 0 such that 𝑚‖𝐾†𝜑‖2 ≤ Σ𝑘∈𝐼 ⟨𝜑𝑘⟩⟨𝜑⟩ ≤ 𝑀‖𝜑‖2 , for all 𝜑 ∈ 𝑉𝐻 𝐿. First, we established a result that shows that any 𝐾 − frame is a controlled 𝐾 −frame under certain conditions. Let 𝐾 and 𝐶 be self -adjoint with 𝐶𝐾 = 𝐾𝐶. If 𝛷 = {𝜑𝑘}𝑘∈𝐼 is a 𝐾 − frame for 𝑉𝐻 𝐿 then 𝛷 = {𝜑𝑘}𝑘∈𝐼 is a 𝐶 − controlled 𝐾 − frame for 𝑉𝐻𝐿. Then we derived a necessary and sufficient condition for a sequence to be a controlled 𝐾 − frame and we have shown that every 𝐶 − controlled 𝐾 − frame is a 𝐶−1 − controlled 𝐾 − frame. Suppose that 𝐾 ∈ 𝐵(𝑉𝐻𝐿). A sequence 𝛷 = {𝜑𝑘}𝑘∈𝐼 is a 𝐶 − controlled𝐾 − frame for 𝑉𝐻𝐿 if and only if 𝑅(𝐾) ⊆ 𝑅(𝑇𝐶𝛷), where 𝑅(𝐾) is the range of 𝐾. Suppose that𝐶𝐾 = 𝐾𝐶. If 𝛷 = {𝜑𝑘}𝑘∈𝐼 is a 𝐶 − controlled 𝐾 − frame for 𝑉𝐻𝐿 then 𝛷 = {𝜑𝑘}𝑘∈𝐼 is a 𝐶−1 −controlled 𝐾 − frame for 𝑉𝐻𝐿. Finally, we proved that the sum of two controlled 𝐾 − framesremains a controlled 𝐾 − frame under certain conditions in left quaternionic Hilbert space. Let𝐶𝐾 = 𝐾𝐶. Suppose that 𝛷 = {𝜑𝑘}𝑘∈𝐼 and 𝛹 = {𝜓𝑘}𝑘∈𝐼are 𝐶 − controlled 𝐾 − frames for 𝑉𝐻𝐿 with bounds 𝑚, 𝑀 and 𝑚′, 𝑀′, respectively. If 𝑇𝛷𝑇𝛹 † = 𝐶−1𝐾𝐾†, then {𝜑𝑘 + 𝜓𝑘}𝑘∈𝐼 is also a 𝐶 − controlled 𝐾 − frame for 𝑉𝐻𝐿.
Detection of microcystins (cyanotoxin) in selected drinking water wells in the Gampaha district, Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Sinhapitiya, S. P. A.; Herath, H. M.; Bandara, W. M. S. N.; Rajapaksha, A. U.; Vithanage, M. S.; Magana-Arachchi, D. N.; Wanigatunge, R. P.
The prevalence of toxic cyanobacteria and various cyanotoxins, such as microcystins (MCs) in drinking water sources have gained considerable attention worldwide due to their potential health risk. Approximately 80% of the Sri Lankan rural population and 34% of the urban population rely on well water for their daily needs. Therefore, people could be exposed to cyanotoxins by consuming well water. This study investigated the presence of potentially toxic cyanobacteria and microcystin variants in the household well water samples collected from the 13 divisional secretariats in the Gampaha district, the second-most populated district in Sri Lanka. Twenty-six well water samples were collected, and physicochemical parameters such as temperature, salinity, pH, conductivity, and Total Dissolved Solids (TDS) were measured in triplicates, in situ using a multi-parameter. All samples met the Sri Lankan Standards (SLS) for drinking water in terms of pH, salinity, temperature and TDS. One well water sample collected from Wattala did not meet the SLS standards in terms of conductivity (829.00±2.05 μS/cm), indicating the well’s unsuitability for water consumption. Morphological identification of cultures originating from well water samples in cyano-specific BG11 medium indicated the presence of nine cyanobacterial genera, including Gloeobacter, Myxosarcina, Dermocarpa, Xenococcus, Synechococcus, Pseudanabaena, Chroococcus, Lyngbya and Geitlerinema. Among them, Synechococcus and Pseudanabaena are reported to be microcystin producers. The presence of extracellular MCs in water samples was detected by High-Performance Liquid Chromatography (HPLC). Extracellular MCs were extracted from water samples using 70% methanol. MC variants and their concentrations in each well water sample were determined using MC-RR-YR-LR standard mixture (Cat no. 33578; SIGMA ALDRICH) by comparing peak retention times and the area of the peaks. HPLC analysis revealed the presence of the microcystin variant MC-LR only in two water samples collected from wells located in the Divulapitiya and Katana areas with MC-LR concentrations of 195.1 μg/L and 278.3 μg/L, respectively. These values exceeded the standard guideline value of 1 μg/L for MC-LR set by the World Health Organization for drinking water. This indicates the potential health risk for consumers of those wells because there is a potential for hepatotoxic MCs to cause acute and chronic illnesses in humans.
In vivo and in silico analysis of inhibition of rice (Oryza sativa) bran lipase with guava leaf (Psidium guineense swartz) extract
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Sooriyawansha, A. M. S. C.; Munaweera, R.; Jayathilaka, N.; Seneviratne, K. N.
Rice (Oryza sativa) bran (RB) is one of the most important co-products in the rice milling industry. It is frequently utilized in animal feed or discarded as waste. After milling, the majority of RB cells are ruptured, and the bran layer is removed from the endosperm. Due to that, the RB lipids encounter highly reactive rice bran lipase (RBL) enzymes which hydrolyze the RB lipids into free fatty acids. Hence RB has a short shelf life. This is the major drawback of using RB as an animal feedstock. This study focused on inhibiting the RBL activity using natural potent inhibitors and determining the mechanism of inhibition to increase the shelf life of RB. The RBLs were isolated by ion-exchange chromatography at pH 10.0 buffer. Guava (Psidium guineense swartz) leaf ethanol: water extracts were tested for inhibition of RBLs. Orlistat, a human gastric and pancreatic lipase inhibitor was used as a positive control. The percent RBLs inhibitory activities were assessed using phenyl acetate assay and the guava leaf ethanol: water extract inhibited the RBL activity (47.81% ± 9.44%). The in vivo data were validated by computational analysis. Homology-modeling of RBLs size in 40 kDa and 32 kDa, and molecular docking (AUTODOCK4) were carried out with the lactone orlistat to determine the best docking poses with the lowest estimated Gibbs free energy values (ΔG) for the mechanism of inhibition. Orlistat lactone ring carbon bound covalently to the serine residue in the characteristic GXSXG pentapeptide sequence (where X=any amino acid) in the catalytic site of the RBLs enzyme. Therefore, lactones present in guava leaf ethanol: water extract has the potential to inhibit the activity of RBLs with a similar mechanism of orlistat. Our finding suggests that guava leaf ethanol: water extract can be applied as a natural solution to increase the shelf life of RB.
Microplastics in selected offshore pelagic fish in Indian Ocean
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Jayarathna, N. K. D. M. P.; Walpita, C. N.; Amarathunga, A. A. D.; De Silva, D. S. M.; Sivyer, D. B.
Microplastics (MPs) pollution in marine environment is an emerging threat to marine biota. Marine pelagic fish species such as tuna and tuna-like species caught during offshore fisheries in open seas, are known to be more commercially important and could be contaminated by MPs. As such, MPs could pose a risk to fish by themselves and to human health due to consumption of contaminated seafood. The present study was planned to investigate the MPs contamination of commercially important three pelagic fish species (Thunnus albacares, Katsuwonus pelamis, and Elagatis bipinnulata) caught from offshore fisheries using multiday boats from several locations of the Indian Ocean to fill the knowledge gap on MPs contamination of pelagic fish, especially in the Indian Ocean. Fish samples were collected from Beruwala, Galle, Panadura and Negombo fishery harbors in Sri Lanka, and the gastrointestinal tract (GIT) and gills were examined for possible MP contamination. A total of 40 samples belonging to three fish species were used for the study. The abundance and morphology (i.e. color, shape) of the MPs were assessed, and the polymer type of the MPs was investigated by using ATR-FTIR. Descriptive analysis was done by using IBM SPSS statistical version 26 and MS excel was used to calculate the percentages of MPs by color, shape and polymer type. There was a contamination of MPs in all three fish species. Nevertheless, 12.5% of E. bipinnulata and 21.7% of K. pelamis did not show MPs in analyzed tissues. T. albacares was found to have the greatest number of MPs (15±6 items individual-1). The morphology of the MPs found from the GIT and gills of all the three fish species were fibers (51%), followed by fragments (37%) and films (12%). In GIT, the most prominent color was blue in all the fish species. Moreover, the polymer types found belonged to three categories viz, thermoplastic elastomers (TPE), phenol formaldehyde resin (PF), and polyethylene copolymer (PE-Copolymer). Among them, the most prominent type of polymer was PF. PE-copolymer was found only in T. albacares. Therefore, continuous monitoring of marine environment and implementing stringent regulations are recommended to minimize plastic pollution in the Indian Ocean to protect both the marine ecosystem and humans.