ICAPS 2022

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Alleviation of drought stress on immature tea (Camellia sinensis) plants by exogenous application of Abscisic acid (ABA)
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Damayanthi, M. M. N.; Wijeratne, T. L.; Damunupola, J. W.
Phytohormones are chemical substances regulating various physiological and biochemical processes in plants. Abscisic acid (ABA) plays a major role in response to drought stress. This study was done to identify the role of exogenous ABA application in immature tea during progressive drought. The experiment was conducted in a glasshouse at the Tea Research Institute of Sri Lanka, using one-year-old potted tea cultivars, TRI 2025 (drought tolerant) and TRI 2023 (drought susceptible). Plants were brought to field capacity and exposed to a drying cycle by withholding water. When plants achieved moderate moisture stress (volumetric water content around 25% in soil), plants were foliar sprayed with ABA at various concentrations [0 (water-spray – WS), 50, 100, 150 and 200 ppm] along with well-watered (WW - positive control) and no-spray (NS - negative control) treatments. Data were collected at 18 hours and 3, 7, 14 and 21 Days After Spraying (DAS) from randomly selected plants arranged according to Randomized Complete Block Design with 2 blocks and 24 replicate plants per cultivar per treatment. At 21 DAS, plants were re-watered, and the recovery was visually assessed after another 7 days. Physiological and biochemical parameters were measured (9.00 am to 12.30 pm) along with soil moisture content. Maintenance of comparatively a higher relative water content was observed in tea plants treated with 100, 150 and 200 ppm ABA. Although the reduction of gas exchange parameters was initially higher in ABA treated plants, it was significantly lower at later stages with progressive drought. Application of ABA in concentrations of 100 - 200 ppm resulted in comparatively higher photosynthetic rates and stomatal conductance at latter stages (14 DAS and 21 DAS). It was observed that the application of ABA did not improve osmolytes accumulation in tea under drought. At latter stage, 100 - 200 ppm ABA treated plants exhibited comparatively higher total chlorophyll and polyphenolic content in both cultivars compared to NS and WS treatments. Similarly, ABA treatments significantly increased antioxidant activity over NS and WS treatments towards the latter stage of drought. The maintenance of significantly lower dark respiration and higher recovery percentages were also observed in ABA (100 - 200 ppm) sprayed plants. Therefore, it can be concluded that ABA foliar application improves water retention and gas exchange parameters while preserving antioxidant capacity resulting restricted risk of oxidative damage under drought. The exogenous ABA application ameliorates the adverse effects of drought stress and improves drought tolerance in immature tea plants. The levels of 100 - 200 ppm concentration of ABA was better in terms of physiological and biochemical alteration and recovery under drought stress in both tea cultivars. Accordingly, considering the cost factor, the application of 100 ppm ABA can be recommended to use as a potential tool to minimize the drought stress effects in immature tea plants.
Alpha-amylase and alpha-glucosidase inhibitory activities of a novel compound isolated from Murraya koenigii
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Sampath, S. N. T. I.; Jayasinghe, J. M. S.; Attanayake, A. P.; Karunaratne, V.
Herbal plants are composed of a vast amount of novel antidiabetic drugs for the management of diabetes mellitus. The leaves of Murraya koenigii L. Sprengel. which belongs to Family- Rutaceae (Common name- curry leaves) plant is known to be a promising source of natural bioactive compounds. In this research, we report the isolation and characterization of a new compound from hexane extract of leaves of M. koenigii and its in vitro antidiabetic activity. The new compound was identified as 3,3',5,5',8-pentamethyl-3,3'-bis (4-methylpent-3-en-1-yl)-3,3',11,11'-tetrahydro-10,10'-bipyrano [3,2-a] carbazole and the structure was elucidated based on extensive 13C and 1H NMR, high-resolution mass spectrometry (HRMS) and 2D NMR analysis. Investigated the in vitro antidiabetic activity of the new dimer using alpha-amylase and alpha-glucosidase enzyme inhibition activities. The compound exhibited significant alpha-amylase activity (IC50 = 30.32 ±0.34 ppm) and the alpha-glucosidase inhibition activity (IC50 = 30.91 ±0.36 ppm) when compared with the acarbose at 0.05 significant level. These results revealed that the new compound isolated from the hexane extract of leaves of M. koenigii could act as an antidiabetic agent.
Alternative gelling agents to develop cost effective medium for in vitro propagation of Dendrobium cv. “Big Jumbo White”
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Kanishka, W. S.; Lakmali, G. B. T.; Umesha, M. S. P.; Priyadarshan, A. I. S.; Senanayake, S. P.
In vitro propagation is the most common method of Dendrobium propagation. Commonly, agar is used as an effective gelling agent though, it is expensive. However, the developing a cost-effective method is beneficial for small-batch productions and is recommended. The objective of the current study was to evaluate the efficacy of ‘kithul’ flour (starch extracted from the pith of Caryota urens) and xanthan gum as alternative gelling agents to develop an efficient, cost-effective medium for in vitro propagation of Dendrobium. Seeds of Dendrobium cv. “Big Jumbo White” was cultured using full-strength Murashige and Skoog (MS) medium. After 90 days of incubation, 1g of Protocorm Like Bodies (PLBs) and plantlets of Dendrobium cv. “Big Jumbo White” were transferred to twelve different MS media supplemented with BAP (Benzyl Amino Purine) (2.5 mg/L) and NAA (Naphthalene Acetic Acid) (0.5 mg/L) and solidified with either agar (1:0) or with alternative agents; kithul flour (0:1) and xanthan gum (0:1) or a series of combinations of each alternative gelling agent with agar (1:4, 2:3, 3:2 and 4:1) totalling to 12 treatments with six number of replicates per each. The weight of plantlets and PLBs, number of plantlets, number of leaves, number of roots, and length of the roots were recorded as growth parameters in fortnight intervals for a period of 90 days to assess the growth performance. After 90 days of incubation, the MS medium of agar: kithul flour (1:4) of the treatment series with kithul flour and agar: xanthan gum (2:3) of the treatment series of xanthan gum, have shown significantly high performance in the growth and development of PLBs and plantlets. Four growth parameters, number of plantlets: 44, number of leaves per plantlet: 5, number of roots per plantlet: 12 and root length: 1.5 cm, were significantly high in the agar: kithul flour (1:4) medium than in the agar: xanthan gum (2:3) medium. Moreover, compared to the conventional tissue culture media prepared using only agar, the modified medium using agar: kithul flour (1:4) has shown 73% of cost reduction. In conclusion, the use of agar and kithul flour (1:4) as an alternative gelling agent can be recommended as a cost-effective medium for the development of PLBs into plantlets of Dendrobium cv. “Big Jumbo White” on a small scale in vitro culture system.
Analyse and design for water distribution network in community water supply using different simulation techniques
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Sutharsan, M. E.
The water supply scheme mainly supplies potable water to houses, commercial and industrial institutions. Supplying water to the consumers at the required quantity with adequate pressure is the prime purpose of any water distribution network (WDN). However, the performance of the WDN may vary from the original design in the long run. In this study, a WDN network model was built using WaterGEMS and WaterCAD computer simulators and hydraulic analyses were conducted to obtain an optimal WDN design for an existing community water supply scheme of a village called Poomalanthan in Sri Lanka. A series of steps such as; models, network representation, verification, problem identification, model application, and results analysis were carried out in developing the WDN simulation model. The demand for domestic, industrial, commercial and unaccounted for water was forecasted for twenty-five years while considering the average per capita daily demand as 100 litres. The analysis was carried out using the Hazen-Williams friction method and the hydraulic parameters such as pressure, flow velocity and flow rate were analysed under extended period simulation. The result revealed that all nodes in WDN operate above the threshold pressure limit of 10 mH2O pressure throughout the day, including peak hours. The pressure during peak hours is the critical output factor which shall give an idea of ensuring water supply to every consumer at an adequate pressure. The nodal pressure is negatively correlated with the ground elevation. Most pipes have a relatively low velocity than specified in the design guidelines, which may be due to the low daily water demand of the small community. However, the chance of silt deposition in the pipes is the disadvantage of maintaining low velocity in WDN. Hence frequent pipeline line washout is recommended to eliminate the silt deposition in the system. The water flow rate in the pipes depends on the water demand at every node. The same hourly flow rate was not observed since the demand in the system was not constant throughout the day. Instead, it varies with the time of the day, and usually, the peak demand arises in the morning and late evening hours when people consume water for bathing, washing, and cooking. The water tower was optimised at 10m height to supply water at sufficient pressure. The WDN was designed for optimised pipe sizes with pipe availability in the market. Statistical comparison through an ANOVA test reveals that there is no significant difference in the nodal pressure, flow velocity and flow rate results derived from WaterGEMS and WaterCAD simulation techniques. Water network computer simulators used during this design can handle various water supply network problems. Computer-aided WDN simulation techniques provide significant advantages over conservational computations in terms of optimisation, results in accuracy, monitoring of the system during operation, time consumption and room for future modification.
Analyses of biometric growth parameters, feeding ecology and fisheries aspects of Frigate Tuna (Auxis thazard), a Neritic Tuna species found off the east, west and south coasts of Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Rathnayaka, A. P. H. B.; Perera, H. A. C. C.; Perera, U. L. K.
Frigate tuna (Auxis thazard) is a commercially important neritic tuna species in Sri Lanka contributing to over 40% of the total neritic tuna catch of the country. Only a few studies have been conducted on biometric parameters of frigate tuna in Sri Lankan waters. Therefore, the present study was conducted to study the growth condition indices and fisheries aspects of A. thazard in selected coastal waters around Sri Lanka and the feeding ecology of A. thazard in the West coast of the country. The study was based on a primary data analysis where the data were collected from the West coast from November 2021 to February 2022 and a secondary data analysis in which the data were obtained from the Department of Fisheries and Aquatic Resources (DFAR) following the year 2017 for a comparative study off the Western, Southern and Eastern coasts of Sri Lanka. The Length–weight relationship (LWR) and Fulton’s condition factor (K) were estimated using the equations 𝑊 = 𝑎𝐿𝑏 and 𝐾=100𝑊/𝐿3 to assess the condition of the fish. The total weight ranged from 124.90 g -1405.05 g, 157.00 g -1475.00 g and 152.60 g - 890.40 g and further total lengths ranged from 23.8 cm - 44.2 cm, 21.5 cm - 46.5 cm and 25.5 cm - 44.1 cm for Western, Southern and Eastern coasts respectively. The LWRs were 𝑊= 0.0012𝑇𝐿3.6586, 𝑊 = 0.0026𝑇𝐿3.4846 and 𝑊 = 0.0147𝑇𝐿2.951, in which the pooled ‘b’ values 3.6586 and 3.4846 for the West and South coasts indicating positive allometric growth (b>3, t-test, p<0.05) and 2.951 for the East coast indicating isometric growth (b=3, t-test, p>0.05). Both male and female fish on each coast followed the same growth pattern without any difference. The K values 1.21 ± 0.42 and 1.43 ± 0.98 calculated for the West and South coasts indicated relatively healthy conditions and 0.94 ± 0.51 on the East coast indicated comparatively poor conditions. The gillnets accounted for 98% of catches on the West coast and ring nets accounted for 68% and 67% for South and East catches based on the total landings in 2017. In the primary data analysis, the estimated Relative Gut Length (RGL) confirmed the frigate tuna as a carnivore. The size classes of 30.0 - 31.50 cm and 23.50 - 24.50 cm had the highest and lowest feeding intensities based on the Gastro Somatic Index (GaSI). The most preferred prey item was shrimps. The Fishbase reports length at first maturity as 29.5 cm. The percentages below 29.5 cm include 18.83%, 39.18% and 33.99% for the West, South and East coasts, respectively. Therefore, continuous monitoring of fish landings and data collection is recommended for a sustainable fishery.
Assessment of human health risk of cylindrospermopsin by consuming Oryza sativa (rice) from selected CKDu endemic areas in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Bandara, W. M. S. N.; Wanigatunge, R. P.; Rajapaksha, A. U.; Vithanage, M. S.; MaganaArachchi, D.N.
The proliferation of toxic cyanobacterial blooms in freshwater bodies can seriously threaten human health. Many studies have been carried out on cyanotoxins in water sources, but studies on cyanotoxins in terrestrial plants are limited. Cyanotoxins in water sources can enter terrestrial plants when irrigated with cyanotoxin-contaminated water and cultivated in cyanotoxin-contaminated soil. As the main staple food in Sri Lanka, Oryza sativa (rice) is widely grown island-wide, mainly in the country's dry zone. The rice fields are irrigated with raw water from the reservoirs throughout their cultivation. Previous literature reported the presence of cyanotoxins, and potential cyanotoxin-producing cyanobacterial species in reservoirs in the dry zone in Sri Lanka. Moreover, cyanotoxins are hypothesized as one of the risk factors for chronic kidney disease of unknown aetiology (CKDu) in Sri Lanka. Cylindrospermopsin (CYN) is a cyanotoxin and negatively affects on several organs in the human body, including the kidneys. Therefore, the current study investigated CYN in O. sativa samples (n=102), including the most cultivated variants, samba (n=20), nadu (n=61), rathu kekulu (n=12) and keeri samba (n=9) collected from CKDu endemic Girandurukotte and Dehiattakandiya areas. As a control, rathu kekulu samples (n=22) were collected from CKDu non endemic Sewanagala area. CYN was extracted and analysed by high-performance liquid chromatography (HPLC) with reference to the CYN standard (SIGMA ALDRICH 32087). Estimated Daily Intake (EDI) of CYN was then calculated to determine the potential human health risk, for an adult by consumption of CYN-contaminated rice. Results of the HPLC analysis revealed that the mean ± SE values of CYN concentrations in samba, nadu, rathu kekulu, keeri samba rice from CKDu endemic areas and rathu kekulu from the control area were 6235.74 ± 1289.15, 6821.44 ± 694.80, 6538.66 ± 1797.81, 3702.51 ± 1321.02, and 3460.99 ± 359.91 μg/kg, respectively. Mean ± SE of estimated daily intake when exposure to CYN via consumption of samba, nadu, rathu kekulu, keeri samba rice in CKDu endemic areas and rathu kekulu from the control area were 30.45±6.29, 33.31±3.39, 31.93±8.77, 18.08±6.44 and 16.90±1.75 μg/kg of body weight per day, respectively. All these values exceeded the provisional Tolerable Daily Intake (TDI) of CYN value established by the World Health Organization (0.03 μg/kg of body weight per day), which can pose a health risk to consumers. The present study revealed that the consumption of O. sativa in the studied areas has a potential risk of accumulation of CYN in the human body. However, it emphasized the importance of investigating the uptake of CYN into rice, in large sample sizes in the study areas.
Assessment of pollutant removal efficiencies of municipal landfill leachate treatment techniques in the tropics
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Pathirana, K. P. J. J.; Yatawara, M. D. M. D. W. M. K.
Leachate generation is a major problem for municipal solid waste (MSW) landfills and causes a significant threat to surface and groundwater. Therefore, the treatment of leachate is essential to ensure the protection of both environmental and human health. Different treatment techniques as individual or integrated techniques, are being used in the world prior to the discharge of the leachate into the environment. This study was planned i) to explore the individual and integrated leachate treatment techniques used in the tropical region of the world, ii) to compare the percentage removals of key pollutants among leachate treatment techniques considered, iii) to determine the factors affecting the selection of appropriate leachate treatment technique/s and, iv) to evaluate the removal efficiencies of the key pollutants of the leachate discharged at the sanitary landfill at Dompe by the integrated technique of sequential batch reactors (SBR) and constructed wetland (CW). The first three the objectives were achieved through a comprehensive literature survey. The leachate samples for the fourth objective were collected at three locations within the treatment system and analyzed for selected parameters using standard methods. The statistical analysis for the data obtained from the sanitary landfill at Dompe was done using Minitab 17. Results revealed that, the aerated lagoons, aerated sludge reactor, SBR, and reverse osmosis (RO) were the more effective methods in removing the key pollutants such as chemical oxygen demand (COD), bio-chemical oxygen demand (BOD5), phosphate and sulfate, while adsorption, coagulation-flocculation, and membrane filtration were effective in removing COD, ammonia, heavy metals as well as total suspended solid (TSS) and total dissolved solid (TDS). The integration of leachate treatment techniques showed higher removal efficiencies than any individual (physical, chemical, or biological) treatment technique. In addition, the composition, age of the waste material, precipitation, and climate were the determinants for an appropriate leachate treatment facility identified in the literature survey. Results further revealed that the leachate treated with SBR at Dompe showed significant reductions of BOD5, COD, TDS, phosphate, and sulfate compared with influent leachate (p>0.05; One way ANOVA). Nevertheless, integration of SBR with CW produced effluents with significant reductions of BOD5 (79.84%), COD (69.57%), TDS (38%), TSS (35.73%), phosphate (56.35%), sulfate (61.16%), and Pb (84.46%) (p>0.05; Student’s t-test). Results revealed that the selected parameters were within the maximum permissible limits of effluent water quality standards for discharge into inland surface water bodies. Although the appropriate integration of leachate treatment techniques showed higher removal efficiencies of the key pollutants than any individual treatment technique, taking into consideration of factors including age, leachate volume and composition of waste are recommended for future designs of MSW leachate treatment plants.
Assessment of the potential distribution areas for two endemic plant species of Sri Lanka under climate change by species distribution modelling
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Kodikara, K. N.; Vidanage, S. P.; Kadupitiya, H. K.
Climate Change is arising as a major threat on biodiversity. Long term climatic conditions have direct links with the occurrence or prevalence of a species in a particular locality. Early predictions facilitate making necessary management options to reduce the negative impacts of this phenomenon. Calophyllum walkeri is a severely affected species from the dieback. It has a conservation status as vulnerable. Syzygium rotundifolium is a range restricted species. Both are endemic to Sri Lanka and dominant species in montane forests. The objective of this study was to predict the best suitable areas for both species currently and by 2070. Maximum Entropy (MaxEnt) modelling method was used, due to its accuracy and well performance even with small sample sizes as the number of records for Calophyllum walkeri was very low. Secondarily obtained data from the National Herbarium for the whole country were used for Calophyllum walkeri (n=29) and primarily obtained presence only data by field surveys covering the whole study area namely Horton Plains National park along with secondary data for less accessible places for Syzygium rotundifolium were used as species occurrence data (n=55). Climate data were obtained through the databases of WorldClim website which contains climate data as spatial data with high resolution, specifically have been developed for spatial modelling activities. Average monthly weather data for 2010-2018 with 2.5 minutes spatial resolution were used as current climate data and future climate data for 2070 for MIROC6, Global Circulation Model climate projection with 30s spatial resolution were used as future climate data. All the cllimate data were converted into ascii format by using ArcMap 10.2.2 and occurrence data were converted into csv format and introduced into the model while selecting random test percentage as 25%. Nuwara Eliya district along with some parts of Kandy and Matale districts were resulted as the best areas for Calophyllum walkeri currently, while Ratnapura and Kegalle districts show moderate suitability. There is a possibility in reduction of suitability in Kandy and Matale districts in 2070 while Nuwara Eliya district will remain as the best area. There is a possibility of wet zone of the country to become suitable for Calophyllum walkeri including Batayaya, Denuwakanda, Dolekanda. For Syzygium rotundifolium, Nuwara Eliya district was the best suitable area and Ratnapura district indicated slight suitability under both current and future climate conditions. The resulting value for the Area Under Curve test which is a main statistical test of this modelling method for Calophyllum walkeri was 0.947 and it was 0.968 for Syzygium rotundifolium. Since these values are greater than 0.5, the models have performed accurately. This study recommends further studies to check the possibility of the wet zone of the country including Western and Southern regions which was resulted as a suitable region with the changing climate, to introduce Calophyllum walkeri in a requirement to take more conservation efforts. Conservation efforts for Syzygium rotundifolium can be increased within the montane region, since it is the most suitable area for it, according to the results of this study.
Assessment of the potential utility of sugarcane distillery spent wash as a liquid nutrition source for agricultural crops
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Kuruppuarachchi, H. D.; Ruvinda, K. M. S.; Manathunga, J.
Spent wash generated from sugarcane molasses-based ethanol industries has the potential to be used as an organic fertiliser for various crop types due to its nutritional qualities. The present study evaluated the potential of raw spent wash as a liquid nutrition source to improve the growth of the commonly grown vegetable variety, tomato (Solanum lycopersicum). Selected physicochemical characteristics of the spent wash of the raw spent collected from a distillery industry in Sri Lanka were measured using APHA (2017) standard procedures. The crop experiment was conducted in the open field using agricultural guidelines provided by the Department of Agriculture. Tomato plants were treated with different spent wash doses (0.5, 1.5, 2.5, 5.0, 7.5 and 10 mL) divided into six treatment categories. Certified organic fertiliser and tap water were used as positive and negative control categories, respectively. Growth morphometric attributes of the plants and fruits were monitored for 60 days. The data were statistically analyzed using univariate statistical methods. The physicochemical analysis revealed a highly acidic nature (pH, 3.3 ± 0.08) with Nitrate (255 ± 0.04 mg/L), Phosphate (38 ± 0.07 mg/L), and Potassium (3.39 mg/L) levels. The physicochemical characterization of the raw spent wash proves that the spent wash may contain minerals and nutrients where the land application can enhance the crop yield of selected crops. Among growth-related morphometric attributes of tomato plants, shoot lengths, the number of leaves, and the number of buds and flowers were found to have less significant variations (p > 0.05). In contrast, other treatment categories recorded significantly reduced fresh fruit weight compared with the positive control (p < 0.05). Measured fresh fruit weight was more favourable towards high-end doses. The experiment results indicate that the sugarcane spent wash could be more favourable during the fruiting stage than in the vegetative stage. However, these findings should be solidified through repeated scientific studies. A recent study recommends mixing raw spent wash with other organic ingredients to improve the nutritional qualities. Continuous soil testing should be conducted in future studies to identify the effects on soil characteristics while conducting further experiments using the raw spent wash for different crop types.
Assessment of water quality status in a tropical river mouth: Special reference to Kalu Ganga, Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Batugedara, B. D. I. M.; Senanayake, S. A. M. A. I. K.
Land-based pollutants are released into rivers and eventually reach coastal waters. As a result, these pollutants contaminate coastal waters in a non-point manner. Therefore, assessing river mouth water quality is crucial for managing coastal waters. Kalu Ganga is one of the major rivers in Sri Lanka, which starts from Adam's Peak and flows for about 129 km before being connected with the Indian Ocean at Kaluthara. The objective of the present study was to assess the current water quality status in the Kalu Ganga river mouth. Surface water sampling was carried out from August 2020 to October 2020 (Wet months) and January 2021 to February 2021 (dry months) every month. Six sampling locations were selected at the Kalu Ganga river mouth based on the random sampling technique, which included three locations along the right-side river mouth bank and three locations along the left-side river mouth bank. Altogether sixty water samples were subjected to the analysis of eleven water quality parameters, viz., temperature, pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, dissolved oxygen (DO), biological oxygen demand (BOD5), and the concentrations of nitrate, orthophosphate (OP), total phosphate (TP), and chlorophyll-a (Chl-a) at each location using standard methods. Water temperature, EC, TDS, salinity, and pH were measured onsite using portable meters. In the laboratory, DO and BOD5 were measured using standard titrimetric methods, while nitrate, OP, TP, and Chl-a concentrations were measured according to standard spectrophotometric methods. During the wet months, the average values for the temperature, pH, EC, TDS, and salinity were recorded as 30.1±0.2 °C, 7.42±0.39, 0.21±0.07 mScm-1, 0.24±0.08 ppt, 0.0±0.0 ppt respectively. DO and BOD5 were recorded as 9.2±0.4 mgL-1 and 0.4±0.3 mgL-1day-1 respectively. The average nitrate, OP, TP and Chl-a concentrations were obtained as 0.15±0.01 mgL-1, 0.16±0.06 mgL-1, 0.31±0.06 mgL-1 and 0.66±0.19 μgL-1 respectively. During the dry months, the average values for the temperature, pH, EC, TDS, and salinity were recorded as 31.1±0.1°C, 7.98±0.04, 25.34±7.33 mScm-1, 6.54±0.11 ppt, and 8.8±0.1 ppt respectively. DO and BOD5 were recorded as 8.5±0.8 mgL-1 and 0.4±0.2 mgL-1day-1 respectively. The average nitrate, OP, TP and Chl-a concentrations were reported as 0.02±0.01 mgL-1, 0.13±0.01 mgL-1, 0.31±0.08 mgL-1 and 0.56±0.25 μgL-1 respectively. Except for BOD5, OP, TP, and Chl-a, all other parameter values were significantly different between wet and dry months (paired t-test, p<0.05). The elevations of EC, TDS, and salinity that have been noticed during the dry months indicate the saltwater intrusion into the Kalu Ganga river mouth. Studies including microbial contamination, bottom water quality analysis, etc., are recommended in the study area. Based on the findings, it can be concluded that the Kalu Ganga river mouth exhibits a low level of pollution in terms of the evaluated water quality parameters. At the same time, it is necessary to establish water quality standards for river mouths in Sri Lanka.
Atmospheric chemical composition of bulk precipitation in different regions of Gampaha District
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Edirisinghe, E. A. C. P; Deeyamulla, M. P.
Wet and dry deposition, both referred to as bulk precipitation, are the two methods of removing gases and particulates from the atmosphere. This research primarily focuses on bulk precipitation analysis to evaluate the pollution sources and the extent of seasonal characteristics of precipitation for air quality monitoring in the vicinity of Kerawalapitiya-Yughadhanavi Power Plant, the largest oil-fired power plant, and Sapugaskanda Oil Refinery, the single largest oil refinery in Sri Lanka. During the northeast and first intermonsoon seasons, 30 rainwater samples were collected over a five-month period from November 2021 to March 2022, in Kerawalapitiya (site A), Sapugaskanda (site B), and Kadawatha (site C), all densely populated and heavily industrialized areas, and Keragala (background site D), a rural area in Gampaha district where anthropogenic influence is minimal. Based on volume weighted mean (VWM) pH variation, Kadawatha area showed acidic precipitation (5.21±0.3) during the study period, while sites A (6.81±0.3), B (5.75±0.8) and D (6.12±0.2) had alkaline pH values. The neutralization factors (NFs) for the major cations (Na+, K+, Mg2+,Ca2+, and NH4+) in the precipitation indicated that higher levels of Na+ and NH4+ contributed to the neutralization of the acidic components at sites A and D, respectively. The VWM concentrations of ionic species were determined by ion chromatography followed the order of Na+> Ca2+>SO42-> Mg2+>NO3->Cl->NH4+>K+>Br-> F- in Kerawalapitiya, NO3->SO42->Ca2+>Na+> Cl-> K+> NH4+>Mg2+> Br->F- in Sapugaskanda and SO42->NO3->Na+> K+>Cl->Ca2+>Mg2+>Br->F- in Kadawatha. Nevertheless, Keragala showed a relatively low ionic composition, and it was in the order of NO3->NH4+>Na+>Cl->Ca2+>K+> SO42->Mg2+>Br->F-. There was a reduction in the VWM SO42- concentration in the Sapugaskanda site compared to a previous study done in this area in 2021. This may be due to the time-to-time shutdown of the Sapugaskanda oil refinery during the study period for the first time since 1969. Enrichment factors (EFs) associated with the sea (EFsea)and crust (EFcrust) confirmed that the Cl- ions at all four sites were marine in origin, although Ca2+, K+, and SO42- were not from marine sources. In addition, the values of EFsea and EFcrust for SO42- and NO3- showed greater than 1 in all four sites. This may be due to human activities in the study area. Also, Mg2+ has a significant contribution from both marine and soil at sites B, C, and D, while it is of anthropogenic origin at site-A. VWM metal concentrations determined by ICP-MS revealed that all sites had higher values for Al, Mg, K, and Zn, but lower concentrations of Cd, As, Co, and Cr. The results of this study further confirmed that rainwater analysis is an indirect indicator of air quality in a given area.
Attitudinal and behavioural changes in Coconut (Cocos nucifera) oil consumption with the occurrence of Aflatoxin contamination in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Sandupama, M. W. P.; Munasinghe, H. M. D. H.; Silva, M.
In the recent past, there was a serious controversy within the Sri Lankan community since certain imported coconut oil brands were detected unsafe for consumption as they exceeded the permissive aflatoxin levels. The present study investigates the noticeable changes in consumption patterns and behaviours as well as the degree of awareness of households on basic information regarding aflatoxin contamination. The survey study was conducted with the participation of 521 households representing Western and Southern provinces. A simple random sampling method was used as the sample design. Data were gathered using a self-administered questionnaire which was distributed through different media. Collected data were analyzed using the social science statistical program IBM SPSS 25, along with Microsoft Excel with Data Analysis Add-in. The results showed that 91.2% of respondents are aware of aflatoxin as a potential hazard, while only 42.8% were concerned about different aspects of aflatoxin contamination, up to a considerable level. Out of the coconut oil consumers, 12.6% did not have a proper idea about the reasons for the aflatoxin contamination. A few participants (1.6%) stated that aflatoxin has no adverse effect on human health, while the majority (91.6%) believed the main effect is the carcinogenic effect. Many agreed that buying a local reputed oil brand (54.6%) and preparing your own at household levels (66.8%) are the best control measures that can be taken at household levels. Although 93.3% of respondents showed a positive interest in learning more about this food safety concern, there is no significant association (p > 0.05) between the highest education level of the consumers and the awareness of aflatoxin contamination as per the cross-tabulation and Chi-square test. According to the Paired sample T-test, the purchasing places, factors affecting purchasing decisions, and the buying frequency have changed significantly (p < 0.05) based on the different perceptions regardless of educational level. But most of the consumers did not shift to an alternative oil instead of coconut oil, while 22% have started using different oils. The significant factor considered at the purchasing point was changed from brand to standards and specifications, and the concern for the nutritional attributes has also increased after the incident. There is no correlation between the factors that affected the purchasing decisions before and after the issue (p > 0.05). The study concluded that the majority of coconut oil consumers have a satisfactory awareness of the potential hazard of aflatoxin, and the consumption patterns and purchasing decisions have deviated significantly after the incident. The trends and habits rather than knowledge and greater awareness on the matter are seemed to be accountable for these behavioural changes. Therefore, the relevant authorities should induce consumer education campaigns to enhance the awareness of consumers on these food safety issues, which will lead them to assure health safety and confidence in coconut oil products. Moreover, quality and safety analyses of coconut oil manufactured on small, medium, and large scales will be conducted to gain in-depth knowledge as future projects align.
Comparative study of recycled papers to be used as an alternative for food packaging: quality assessment and heavy metal migration testing
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Indunil, G. M.; Bandra, W. R. T. W. R.
The permanence and durability of recycled papers are important as virgin papers are chosen for the definitive end-use. The main objective of this study was to assess the paper quality of recycled papers used as an alternative for food packaging. Three types of recycled papers, Brown Kraft papers (R1), Yellow Kraft papers (R2), and White papers (R3), were collected. Physical parameters; grammage, thickness, burst strength, tensile strength, water absorptiveness, chemical parameters; pH and optical parameters; opacity, brightness, and whiteness of the selected papers were tested using standard methods. At first, sample papers were subjected to accelerated ageing by keeping them in a closed ageing chamber at 50 % relative humidity and 90°C (ASTM D4714 method). Samples were tested after accelerated ageing of 3 days, 7 days, 14 days, 21 days, and 28 days, similar to the natural ageing of 0, 384 days, 2.5 yrs., 3.5 yrs., 4.9 yrs., 7.4 yrs., and 9.8 yrs., respectively. Heavy metal migration test was done to evaluate the suitability of the recycled papers as food packaging material. Five different food types, burgers, pizza, Sausages, candy, and chocolates, were selected, and 500 g of each food type was wrapped with 2 dm2 sized recycled papers stated above and kept for 72 hours in normal laboratory conditions. Three replicates were used for each food type. The presence of heavy metals in food samples was extracted using a 3% (v/v) metal¬ free solution of acetic acid for 24 hours at 40℃. At the end of the treatment, contact liquid was collected and analyzed for heavy metals using atomic absorption spectroscopy (AAS). The presence of heavy metals in food packaging materials was compared with four different food packaging standards. Opacity has increased in all the recycled papers with accelerated ageing. Other parameters showed a decreasing trend over time. All three types of recycled papers failed the water absorptiveness test after accelerated ageing on day 3. Changes in pH varied from alkaline to neutral (pH 9.1 to 7.4) in recycled papers over time. In conclusion, all the recycled papers are not suitable for printing and writing as they fail water absorptiveness. As parameter changes can be observed after accelerated ageing of 21 days in recycled papers, they can be used as archival or artist’s paper for 7.4 years without discolouring or deteriorating. The Recycled papers produced in this study can be recommended for food packaging as they show the highest permanence in terms of tensile and burst strength. However, as recycled papers fail the water absorptiveness, it is recommended to use them to pack dry food. The available amounts of heavy metals present Cu, Zn, Mn, and Cr are not exceeded within the EU, EC, EPA, and SLS food packaging standards for recycled papers. Ni was not detected in R1, R2, and R3 recycled papers. However, according to the Council of Europe standard, it exceeds the permissible Pb level in food packaging materials. When considering the migration of heavy metals from recycled papers into food, R1, R2, and R3 recycled papers can be recommended for food packaging as per the EPA, EC, and SLS standards without further treatments. Food items with high levels of fatty acids facilitate the higher migration of heavy metals compared to food items with lower fatty acid levels.
Comparison between the Machine Learning Algorithms to determine the suitable input features for personal theft, sexual assault, and house burglary victimization prediction
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Lakshan, W. S. V.; Weerakoon, W. A. C.
The crime-related predictions can be vastly supported by most of the available supervised machine learning models. The possibility of becoming a victim increases daily in each crime category. The main difficulty is to find how severe the impact is upon the victim after the crime. Here, the Random Forest, Support Vector Machine (SVM), K-Nearest Neighbour (KNN) algorithm, and Neural Network models were compared with the use of available features found from a secondary dataset to build a better prediction model, which has been implemented in four main phases over two aspects based on the possibility of becoming a victim and severity of the crime. The available features were used as the inputs for phase I and Principal Component Analysis and correlation tests were performed to identify the appropriate and essential feature combinations for the rest of the phases. The pre-processed datasets were used to implement and train the models. Moreover, the Random Forest model was proven to be the most efficient model with an accuracy of 85.33% in phase four when comparing the accuracy levels of the models over different phases, while the KNN and Neural Network models obtained an accuracy of over 70% and SVM obtained the least accuracy in the same phase. In phase one, the Random Forest algorithm was executed with a precision of 76%, while KNN and Neural Network model obtained around 70%. The final outputs obtained for phase four showed that factors such as age, year, gender, race, and relationship with the perpetrator will be the most suitable features to build an accurate machine learning model for victimization prediction. The mentality level of the offender and intention of doing it has the main impact on the severity level. Also, authorities need to keep track of the fact whether it is a repeat offence or not, the main offender or not and the contribution of the offender to support better information inputs for the prediction models. This study developed a victimization prediction model with reference to personal theft, sexual assault, and house burglary. This would be a step forward from previous research works of rule-based victimization possibility index prediction for small victim clusters. Further, new features were identified in the last phase, which can be used to develop models to predict criminal behaviour after sending them back to the society. This will greatly benefit the authorized bodies to monitor them and reduce the possibility of victimization.
Comparison of sensitivity of Lemna perpusilla (minute duckweed) to chromium, nickel, and zinc ions
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Ariyawansha, J. M. M. S.; Pathiratne, A.
In recent times, the pollution of tropical aquatic ecosystems due to heavy metals has become a great issue. The major sources of heavy metal pollution in aquatic ecosystems are effluents from metal-based industries and municipal wastewater. Duck weeds (Lemna species) are widely used in the treatment of wastewater and sewage effluents as they have the ability to absorb nutrients in the wastewater effectively. The species, Lemna minor and L. gibba generally represent temperate areas while L. perpusilla is native to Southeast Asia. Objective of the present study was to compare the sensitivity of L. perpusilla to chromium (Cr), nickel (Ni), and zinc (Zn) ions under tropical temperature exposure based on standard laboratory ecotoxicity tests. Growth reduction of L. perpusilla under Cr, Ni, and Zn exposure was assessed using a standard ecotoxicity procedure with a range of metal ion concentrations (Cr6+: 0, 12, 30, 60, 90 and 120 mg/L; Ni2+: 0, 0.03, 0.06, 0.15, 0.30 and 0.60 mg/L; Zn2+: 0, 0.1, 0.25, 0.5, 1.0 and 2.0 mg/L). Toxicity thresholds of Cr6+, Ni2+ and Zn2+ for the duckweed L. perpusilla under tropical temperature exposure (27°C - 29°C) were estimated based on multiple endpoints (total number of fronds, percentage of green fronds and green frond area). Triplicate test vessels were used for each concentration and the controls. The average specific growth rate and percent inhibition growth rate for each treatment and control replicate were determined. Metal contents in the exposure media were analytically verified using atomic absorption spectrophotometry. One way ANOVA followed by Dunnett’s test was used to estimate the lowest observed effect concentration (LOEC) for each endpoint. Effective concentrations of metals at different percentile effect levels (EC50, EC20, EC10 and EC5) were estimated through nonlinear regression modelling using USEPA Toxicity Relationship Analysis Program software. Based on different endpoints used for the toxicity assessments, lowest observed adverse effect concentrations (7 day LOAEC) for growth reduction of L. perpusilla for Cr6+, Ni2+, and Zn2+ were estimated as 21 mg/L, 0.06 mg/L, and 0.26 mg/L, respectively. For growth reduction of L. perpusilla, the most sensitive 7-day effective concentration for 10% effect (EC10) for Cr6+, Ni2+, and Zn2+ were 21 mg/L, 0.021 mg/L, and 0.2 mg/L, respectively. In conclusion, the sensitivity of L. perpusilla to the three metal ions followed the decreasing order: Ni2+ > Zn2+ > Cr6+. This study revealed that L. perpusilla is more sensitive to Ni2+ than Cr6+ and Zn2+. Of the three metals tested, Cr6+ exposure could be most tolerated by L. perpusilla.
Computational assessment of novel derivatives of epigallocatechin gallate as potential anti-Alzheimer agents
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Rajapaksha, R. P. G. A. P.; Dahanayake, J. N.
Alzheimer's disease (AD) is a chronic, neurodegenerative disease that affects memory, thinking, and behaviour problems. The neuroprotective effects of natural products against AD have been studied in preclinical and clinical studies using in vitro and in vivo models. This computational chemistry study explores the effects of epigallocatechin gallate (EGCG) and its novel derivatives as potential anti-Alzheimer agents using computational chemistry. Among natural products that are tested against AD in clinical studies, catechins are a very commonly found constituent of green tea. Catechins are a bioactive ingredient of green tea and potential anti-oxidative and anti-inflammatory agents. In addition, various putative features associated with AD prevention and modification have been discovered in preclinical in vitro and in vivo studies of catechins. Due to its anti-inflammatory and antioxidant properties, EGCG has neuroprotective effects on AD patients’ brains. EGCG inhibits the formation of neurotoxic beta-amyloid and regulates the formation of a soluble form of amyloid protein (sAPP) and prevents AD progression. Effects of EGCG and its derivatives on Amyloid precursor protein (APP), Amyloid β-protein (Aβ), Alzheimer's Beta A fibrils (Aβ - fibrils), Acetylcholine esterase (AChE), Butyryl choline esterase (BChE), and Tau protein were investigated in this study. Those proteins are highly associated with AD. The Density Functional Theory (DFT) calculations were used to get energy-optimised structures of EGCG and derivative EGCG-G1, EGCG-G2, PEGCG, EGCG-EPA, 5,3,4,3,4,5-O-ethyl-EGCG, and (-)/ (+)-epicatechin-3-O-gallate. The binding interaction of those ligands with each protein can be understood by molecular docking studies. To compare protein-ligand interactions, the protein-donepezil complex was used as a reference in molecular docking. Donepezil is a clinically approved drug for AD. Among considered ligands, EGCG, PEGCG, and (-)/ (+)-epicatechin-3-O-gallate showed better docking scores with AChE, BChE, and APP proteins. Those protein-ligand complexes that showed the best docking scores and protein-donepezil complexes were taken to further analysis of Molecular Dynamics simulations (MD). MD simulations were done for a 50 ns period on protein-ligand complexes which are selected according to docking scores. In MD simulations, CHARMM36 forcefield was used for protein. For ligands, external sources were used for generating topology. The parameters that were used for MD analysis to determine the stability of protein-ligand complexes were Radius of gyration (Rg), Root Mean Square Deviation (RMSD), and Root Mean Square Fluctuation (RMSF). The MD analysis, along with docking studies, revealed that the EGCG and derivative PEGCG can act as anti-Alzheimer agents due to their effects on important AD-related proteins.
Computational assessment of novel derivatives of gingerol as potential anti Alzheimer agents
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Disanayaka, D. M. I. M.; Dahanayake, J. N.
Ginger (Zingiber officinale) is commonly used as a spice and folk medicine, which helps to prevent heart diseases, high blood pressure and lung diseases. Gingerols, zingiberene, shogaols and monoterpenes are the principal components of the extract of ginger. Gingerol is known to provide protective effects against Alzheimer’s disease (AD). AD is a neurodegenerative disease, resulting in loss of cognitive activity and memory and impaired signalling among brain cells. There are only a few approved drugs available for AD. Since developing synthetic chemicals as drugs is a challenging task, many pharmaceutical companies are now focused on the development of plant-derived drugs. Therefore, discovering natural products with medicinal properties for AD as lead compounds can be considered as an important task. There are five main proteins involved in AD: Amyloid precursor protein (APP), Tau protein, Amyloid β-protein (Aβ), Alzheimer's Beta A fibrils (Aβ - fibrils) and Acetylcholine esterase (AChE). In this study, the effects of 6-gingerol eight gingerol derivatives on those five main proteins highly associated with AD were considered to investigate anti-Alzheimer activities. Donepezil which is commonly used as a clinical drug in Alzheimer was considered as a reference compound. Initially, energy minimized structures of 6-gingerol, and its derivatives were obtained using molecular mechanical calculations. Docking studies were carried out for the 6-gingerol and suggested derivatives with AD related proteins. Through docking studies, secondary interactions with target proteins and amino acid residues in binding pockets were identified. The binding affinities of derivatives with proteins were compared with the binding affinity of the parent molecule (6-gingerol). According to the results, the parent molecule and studied derivatives have good binding affinities with Acetylcholinesterase. Therefore, further studies of molecular dynamic (MD) simulation studies were performed for the Acetylcholinesterase-ligand complexes for 50 ns using the CHARMM36 force field. The trajectories obtained from MD simulations were used to calculate the radius of gyration (Rg), root mean square deviation (RMSD) and root mean square fluctuation (RMSF). According to the Rg and RMSD results, the studied protein-ligand complexes were stable throughout the simulation time. Further, RMSF results of derivatives were compared with the results of 6-gingerol parent molecule, in order to investigate the higher binding affinities of the derivatives. The stability of the complexes is an essential feature which can provide information about the lifetime of the complex. Therefore, the ligand bound to the proteins can act as an inhibitor and inhibit the specific function of that protein. Since Rg and RMSD results showed the stability of the protein-ligand complexes, it can be stated that the studied gingerol derivatives have the ability to inhibit AChE. Therefore, the MD analysis results, along with docking results, indicated that the studied gingerol derivatives have the potential to act as promising anti-Alzheimer agents.
Design of heat sink and simulation of electronic cooling of power transistor circuit
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Gunasinghe, L. M.; Samaranayake, W. J. M.; Hansameenu, W. P. T.
Heat sinks are utilized in industrial equipment to disperse surplus heat from heat-generating components to the surrounding environment. In recent years, efforts have been made to develop mechanical or electronic devices that are lighter, smaller, and more affordable. Heat dissipation from the heat sink is a major issue that many researchers are attempting to address. In this work, a traditional heat sink design technique of computer power supplies, which is extending fin topology, is used with four power transistors. This study attempts to improve the cooling of power transistor circuits by designing a new heat sink attached to four power transistors and seeing how the joule heating profile of the power transistor circuit and heat sink are changed. COMSOL Multiphysics version 5.6 software is used to graphically design the heat sink, four-transistor circuit and simulate the heat profile of the design. An electric currents interface and a heat transfer in solids interface are included in the Multiphysics interface. The multiphysics couplings add electromagnetic power dissipation as a heat source and investigate the joule heating and the temperature distribution on power transistors without the heat sink and with the heat sink. Transistors without the new heat sink get heated more than the transistors with the new heat sink with the same applied current density to the circuit board. It shows that joule heating is minimized with the new heat sink design. Here, the results of several studies of a new geometrical 3D model that focus on four power transistors attached to an aluminium heat sink are discussed. The results show the impact of the heat sink area and surface-to-ambient radiation to the power transistors and the circuit board. Based on the simulation results, four transistors become very cooled with the new heat sink design. How the heat-sink thermal performance is affected by shapes and space between fins is also reviewed. It could be observed that in the proposed design, the joule heating was reduced remarkably.
Design of novel perfect metamaterial absorber for Radio Frequency energy harnessing
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Karunathilaka, M. G. M. T.; Ranaweera, A. L. A. K.; Jayathilaka, K. M. D. C.; Seneviratne, J. A.
Due to the rapidly growing wireless communications and sensing applications, the frequency spectrum has already been saturated. Consequently, the abundance of Radio Frequency (RF) signals in the ambient environment made the concept of wireless energy harnessing to be emerged as an attractive solution to energize low-power wireless devices. In this study, a novel tuneable perfect metamaterial absorber (PMA) unit cell was designed by combining two C-shaped split-ring resonators (SRR) embedded with simple electronics circuitry. The feasibility of harnessing energy from 1.8 GHz signals was investigated through electromagnetic (EM) simulations. The design and numerical analysis of the proposed PMA structure is carried out with the aid of the commercially available EM simulation software, High Frequency Structure Simulator (HFSS). The proposed structure’s capability to absorb EM energy as a perfect metamaterial absorber is studied. According to the simulation results, it shows a high absorption coefficient of around 99%. This verifies that the proposed tuneable PMA structure encompasses a high absorption of RF energy. It can be used for the harnessing of RF energy to power up low-power devices and wireless sensor networks.
Detecting abrupt changes in thermal electricity production data in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Sumathipala, P. L. N. S.; Hewaarachchi, A. P.; Dissanayaka, D. M. P. V.
A changepoint or an abrupt change is a distributional change in a time series data structure. Over the past years, many studies have been conducted to search these changepoints and many researchers proposed several multiple changepoint detection methods. One such search method is the Pruned Exact Linear Time (PELT) method, which is exact and under mild conditions, has a computational cost which is linear in the number of data points. This method is a more accurate and faster method to detect multiple changepoints. The objectives of this study are to detect abrupt changes in thermal electricity data in Sri Lanka and predict thermal electricity production accurately. Since undetected changepoints may cause incorrect modelling or prediction, the accurate analysis of electricity data is vital. In this study, electricity production (Hydro, Thermal oil and coal, and wind) by Ceylon Electricity Board (CEB) in Sri Lanka for the period 2000 to 2019 was used to find abrupt changes. The PELT method is used to detect these changepoints and their location in the variance of electricity data. First, the total electricity production of oil and thermal data were used and a changepoint was found in April 2011. This is a documented changepoint since, according to CEB Annual Report 2011, 1487 GWh of thermal (oil) power was added to the system during 2011, which was a significant change. Moreover, two models, for the periods 2000 to 2019 and 2011 to 2019 (after the detected changepoint) were fitted for forecasting the production. Root Mean Square Error (RMSE) and Mean Absolute Percentage Error (MAPE) were calculated to compare the forecasting accuracy of these models. The first model (ARIMA (2,1,3)), which does not consider the changepoint structure, results in RMSE and MAPE values of 0.911 and 6.009, respectively, for the period 2000 to 2018 for the thermal electricity data. For the second model (ARIMA (1,0,3)), RMSE and MAPE were 0.244 and 3.267, respectively, for the period 2011 to 2018. It can be seen that the models fitted by considering changepoints give more accurate results for forecasting electricity production.