PGIS Research Congress

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Fostering education for environmental sustainability: level of competencies on reducing environmental pollution of junior secondary students in Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2014-11-01) Liyanage, T. I. S. S.
Education for Environmental Sustainability (EES) aims to develop students' sensitivity, awareness, knowledge, attitudes, skills, and practices related to the environment and the sustainable use of its resources. It not only empowers students on environmental concerns but also connects them to more sustainable lifestyles, enabling them to become environmentally literate. This cross-sectional survey was conducted to assess the environmental literacy of junior secondary students (Grades 6 to 9) in selected Sri Lankan schools. The aim of the study was to determine students' competency levels in reducing environmental pollution. The sample included 442 students from three districts in the Western Province (Colombo, Gampaha, and Kalutara), selected using random stratified sampling techniques. A questionnaire with multiple-choice questions was used as the research instrument. Students' competency in organic farming, eco-friendly energy sources, reducing/recycling, and judgment on eco-friendly practices was assessed. Competency was measured by students' ability to identify and analyse environmental issues, ask relevant questions, evaluate and make personal judgments, and use evidence and knowledge to defend their positions. The findings revealed that students' competency levels in the focused areas improved with more effective EES implementations in school education. Students in the Colombo District recorded the highest competency level (μ = 0.55 ± 0.26), while the lowest was recorded in the Gampaha District (µ = 0.53 ± 0.26). Competency varied from 0 to 1 across all three districts. Grade 8 students showed the highest competency (μ = 0.55 ± 0.22), while Grade 6 students recorded the lowest (µ = 0.48 ± 0.28). A significant association was observed between the student category and organic farming (p < 0.05), as well as reducing/recycling and willingness to engage in pollution reduction activities (p < 0.05). There were significant variations across districts and among the three grades (p < 0.05). In conclusion, the findings underscore the critical role of EES in enhancing students' environmental literacy and greater awareness and promoting active participation in sustainable practices, paving the way for a more environmentally responsible generation.
Effective corrosion barrier of cinnamon leaf oil incorporated polypyrrole layers for mild steel
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya, Sri Lanka, 2020-11-01) Palipana, P. W. G. K.; Revon, M. H. N.; Priyantha, N.
Mild steel, a type of steel commonly used in industry, is prone to corrosion under certain environmental conditions, which has limited its industrial applications, necessitating intensive study into corrosion prevention techniques. In recent years, conducting polymers and green corrosion inhibitors have been independently identified as corrosion inhibitors, and less consideration has been given over the past years on the combined effect of polymers and natural inhibitors. This study aimed to investigate the corrosion inhibition efficiency by cinnamon leaf oil embedded polypyrrole layers. The electrodeposition of polypyrrole on mild steel was employed using cyclic voltametric scans from -0.2 V to 1.0 V in oxalic acid medium and polymer-coated specimens were subsequently dipped in cinnamon leaf oil to incorporate into the polymer film. Under moderate acidic conditions of HCl medium, mass loss measurements of rectangular mild steel specimens embedded with cinnamon leaf oil, polypyrrole, and the combination of both over one-week period were obtained. The results revealed a superior corrosion inhibitory behaviour of the combined layer having the decreasing order of corrosion inhibition efficiency: polypyrrole and cinnamon leaf oil > polypyrrole > cinnamon leaf oil. Polarization resistance determined by electrochemical impedance spectroscopy, a more reliable method, further supports the strong corrosion inhibitory action of the combined layer on mild steel when compared to polypyrrole and cinnamon leaf oil alone. Open circuit potential measurements also indicate a lower corrosion rate when mild steel specimens are coated with the polymer and cinnamon leaf oil.
Magnetic field-induced deformation of castor oil-based ferrofluids
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya ,Sri Lanka, 2024) Ratnayake, R. M. R.; Ranawaka, T. P.; Liyanage, J. P.
In the field of astronomy, optics is essential and adaptive optics is gaining prominence for its efficiency. This research includes the synthesis and characterization of a castor oil-based ferrofluid and the investigation of the magnetic field-induced deformation of ferrofluids and their potential as a base for liquid telescopes. Depending on the method of obtaining magnetic nanoparticles, the rheological behaviour of the ferrofluid changes significantly. Therefore, to obtain sufficiently small particles, pH level and temperature control were explored. This study proposes a novel surfactant coating method using castor oil as an alternative to oleic acid, given its ricinoleic acid content, which is chemically similar to oleic acid. Castor oil and kerosene are used as carrier liquids, with subsequent characterization of their magnetic and rheological properties. The ferrofluid particle size was studied with scanning electron microscopy (SEM). The rheological properties were studied using Rosensweig instability peaks under the precisely controlled magnetic field of a cavity magnetron electromagnet. The deformation was monitored using optical microscopy and analysed to understand the correlations between the magnetic field characteristics and the resulting deformation patterns. Based on the characterization, the pH control method proved better for obtaining smaller particles, as indicated by the sedimentation rate and confirmed by SEM data. This demonstrated that castor oil is a viable alternative to oleic acid, providing a stable base for ferrofluids that respond effectively to magnetic fields. Castor oil as the carrier liquid proved more stable due to longer response time and stable modelled surfaces. Kerosene, which was more volatile but was more rapid in response to the change in magnetic field, achieving faster response time. Data obtained were modelled using MATLAB, revealing the ferrofluids deformed relative to magnetic field strength. The outcomes of this study may be used as leverage for future studies on tunable liquid surfaces.
Prevalence of depression among undergraduate students: a case study of first-year undergraduates of a university in Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11) Gunarathna, Y. R. I. A.; Fernando, W. B. N. T.; Tennakoon, S. U. B.
University undergraduates are an important group of people for the future of a country. Therefore, their mental health is an important health concern. Students in the first academic year are at the threshold of the profession-targeted education where the transformation of the education system from school education to university education occurs. Depression is a common and serious mental disorder that affects nearly 300 million people worldwide. It may lead to a variety of emotional and physical problems among university undergraduates. It is found that depression causes people to feel a loss of energy, a change in appetite, sleep more or less, anxiety, reduced concentration, indecisiveness, restlessness, feelings of worthlessness, guilt, hopelessness and thoughts of self-harm or suicide. The objective of this study was to evaluate the prevalence of depression among first-year undergraduates. Additionally, it was focused on finding any significant associations between depression and its contributing factors. A cross-sectional study based on a self-administered questionnaire which contained questions to gather information on age, gender, hometown, type of accommodation, satisfaction with the degree program following, economic status, physical activities, alcohol and substance usage and relationship status was used on a random sample of undergraduates from the first academic year of nine faculties in a state university. The Peradeniya Depression Scale (PDS) was used along with the socio-demographic questionnaire to detect depression and factors associated with it among undergraduates. A total of 354 undergraduates participated in the study, and the overall prevalence of depression among them was 9.0% (n = 32). According to the Chi-square test, depression was found to be significantly associated with a diminished level of satisfaction with the enrolled degree program (p = 0.010) and lower monthly income of the family (p = 0.047). A higher percentage of daily drug users (daily liquor users 28.5%, daily smokers 18.7% and 33.3% of daily other drug users) were found to be depressed. Further studies need to be conducted to identify other factors associated with depression. It is recommended to implement scheduled systematic screening for depression and promote counselling services among undergraduates.
Investigation of the presence of humic substances and their metal binding ability in water
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya, Sri Lanka, 2024-11-01) Vijesundara, V. M. T. N.; Makehelwala, M.; Jayarathne, I. P. L.; Weerasooriya, R.; Bandara, W. M. A. T.
Recent research suggests that humic substances (HSs) in water can effectively bind with metal ions, potentially increasing the solubility of metal ions in aquatic ecosystems, hence posing health risks. They are a fraction of dissolved organic carbon that has seen notable changes in concentration across various regions in Sri Lanka. Hence, there is an urgent need to identify the presence of HSs and their metal-binding capabilities within Sri Lankan waters. Further, recent studies have highlighted the increase of Mn levels in groundwater samples, which pose health hazards upon excessive exposure. Given the challenge of Mn removal in the filtration process, understanding HSs-Mn interaction becomes imperative. Therefore, this study mainly focused on the ability of HSs to bind with Mn. Samples were taken from two distinct water sources (groundwater and lake water). The sample preparation, extraction of HSs, and fractionation into humic acid and fulvic acid were carried out using the method available in the International Humic Substances Society (IHSS). Characterization was done using FTIR and Raman spectroscopy. Batch adsorption studies at different pH values and comparisons of FTIR and Raman spectra after metal binding were performed. Furthermore, kinetic studies were conducted. Characterization revealed functional groups of –COOH (C=O stretching: 1740-1770 cm-1, O-H stretching: 3630-3760 cm-1), –CONH2 (N-C=O stretching: 1550-1560 cm-1, N-H stretching: 3070-3140 cm-1), and –NH2 (N-H stretching 3190-3220 cm-1), which facilitate effective metal binding and indicate the heterogeneity of these fractions, extracted from different sources. Although effective Mn-binding was possible at neutral pH, the highest binding was observed at lower pH values (pH 2-3). Significant variations in several spectral bands were also observed, suggesting composition changes after metal binding. As this followed pseudo-second order kinetics, chemisorption is the rate determining step. However, the exact binding mechanism remains unclear, necessitating further investigations.
Precipitation, sea surface temperature (sst), and their relationship over the tropical Indian ocean from 1982 to 2020
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Randombage, A. G.; Thilakarathne, E. P. D. N.; Jayarathna, W. N. D. S.; De Silva, T. D. T.
Precipitation, sea surface temperature (SST) and their interactions contribute to the climate, ecology, economy, and social aspects of a given area. The precipitation over the tropical Indian Ocean fluctuates with SST. The evaporation, wind direction, wind speed, Indian Ocean dipole, El Niño, and La Niña are influenced by SST. This study aimed to identify the prevailing patterns and annual trends of precipitation and SST of the tropical Indian Ocean region (30°N, 20°S, 40°E, 110°E) from 1982 to 2020. Monthly precipitation and SST data were obtained from Asia-Pacific Data-Research Center. MATLAB R2020a version was used to analyse data. Monthly anomalies of the precipitation and SST were calculated by removing the seasonal cycle of the data set. Annual trends of precipitation and SST were analysed by annual means. The highest and lowest (driest) monthly precipitation was in July (4.30 mm) and March (2.69 mm), respectively. The precipitation range of June-July-August is 3.69 mm to 4.86 mm, and December-January-February data varied from 2.69 mm to 3.62 mm. May (28.5 °C) and January (26.4 °C) months represented the highest (warmest) and lowest (coldest) monthly SST, respectively. The annual trend of precipitation and SST showed a ± 0.004 mm/year and a positive 0.02 °C/year, respectively. The mean annual SST of the tropical Indian Ocean during recent years (2000-2020) was 0.4 °C higher compared to the past 17 years (1982-1999). A significant positive correlation was observed between the annual SST and precipitation (+ 0.34 at 0.05 level of significance). Therefore, increasing SST due to global warming may change normal precipitation pattern, and these changes can have substantial implications for ecosystems, weather patterns and climate dynamics.
Thermoelectric properties of dodecylbenzene sulfonic acid sodium salt (dbsa) doped polyaniline & reduced graphene oxide(rgo)-dbsa doped polyaniline composites
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya, Sri Lanka, 2024-11-01) Weerasinghe, W. G. T. L.; Samarasekara, P.; Bandara, T. M. W. J.; Narangammana, L. K.
Polyaniline (PANI) is a highly adaptable conducting polymer. An effort has been made to enhance the thermoelectric properties of PANI by doping it with dodecylbenzene sulfonic acid sodium salt (DBSA). DBSA is a protonic organic acid, and it has a sulphonic group and a long alkyl side chain which interacts with amine/imine hydrogens. It helps to enhance the electrical properties of the polymer and ionization of charges. The sheet like structure of reduced graphene oxide (rGO) supports uniform distribution of polymer matrix and it improves the interfacial interactions between the rGO and the polymer matrix. In this work, rGO incorporated DBSA-PANI was introduced and it was compared with the DBSA doped PANI. The chemical oxidative polymerization method was used to synthesise three different DBSA doped PANI (DBSA-PANI) samples (1.0, 1.5 and 2.0 g) with 2 mL of aniline. rGO was synthesised using the modified Hummer’s method. rGO-DBSA-PANI composites were prepared using the chemical oxidative method. Three different weight percentages of rGO (24%, 35% and 50%) relative to aniline (2ml) were used, with a constant DBSA mass of 1.5 g in all three synthesis processes. The resulting powders were pressed into pellets, and room temperature electrical conductivity and temperature-dependent Seebeck coefficients were measured. The successful synthesis of DBSA-PANI was observed by Fourier Transform Infrared Spectroscopy (FTIR). Characteristic peaks observed at 2914, 2829, 792 and 673 cm ⁻ ¹ confirmed the presence of DBSA anion. Peaks at 3441, 3201, 1553 and 1293 cm-1 confirmed the successful synthesis of PANI. Synthesised rGO was characterized using X-ray diffraction (XRD) and Raman Spectroscopy. Characteristic XRD peak at 25° and D and G vibrational bands observed in the range of 1700 and 1353 cm-1 confirmed the successful synthesis of rGO. Our previous study shows an electrical conductivity of 3.5 S/m for undoped PANI. The highest electrical conductivity values of 80.7 S/m and 54.4 S/m were observed for 2.0 g DBSA-PANI and 35% rGO-1.5 g DBSA-PANI at 300 K, respectively, indicating 23 times and 16 times increments compared to that of the undoped material. The highest Seebeck coefficient values of 1.40 × 10 ⁻ ⁴ V/K and 1.85 × 10 ⁻ ⁴ V/K were observed for 2.0 g DBSA-PANI at 300 K and 24% rGO-1.5 g DBSA-PANI at 300 K, respectively. The highest power factor values of 1.58 × 10 ⁻ ⁶ Wm ⁻ ¹K ⁻ ² and 1.32 × 10 ⁻ ⁶ Wm ⁻ ¹K ⁻ ² were obtained for 2.0 g DBSA-PANI and 24% rGO-1.5g DBSA-PANI at 300 K, respectively.
Colour correction model in deep learning for fish habitat monitoring
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Sarathchandra, W. M. E. Y.; Siyambalapitiya, R.; Munasinghe, C.S.
This study investigated the use of deep learning techniques for fish habitat monitoring, focusing on the impact of a Colour Correction Model (CCM) on underwater imagery. The primary objective was to assess whether the CCM can enhance the performance of the You Only Look Once (YOLOv8m) framework in fish species classification and marine environment assessment. The results reveal that the integration of the CCM does not enhance the performance of the YOLO framework. While the CCM improved image clarity and fidelity, the classification accuracy increased only marginally from 65% to 66%, and metrics such as precision, recall, and F1-score showed minimal improvement. Subsequent models, including YOLO and TensorFlow, do not exhibit significant improvements in classification accuracy. The evaluation of various deep learning models was rigorously conducted, highlighting the strengths of each model and the challenges addressed in marine habitat monitoring. While training and validation loss were effectively reduced by the CCM, this did not translate into improved performance metrics for fish classification. These findings underscore the complexity of underwater imagery and the need for further refinement in preprocessing techniques. This research contributes a nuanced understanding of the role of colour correction in deep learning applications for environmental monitoring. Future work should focus on exploring alternative preprocessing methods and integrating more sophisticated deep learning architectures to enhance classification outcomes. Despite setbacks, the potential for advanced deep learning models to revolutionize marine biology remains significant, promising valuable contributions to the preservation and understanding of marine ecosystems.
Fabrication and optimization of nanoporous membranes for zinc-bromine flow battery
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya, Sri Lanka, 2024-11-01) Serasinghe, V. U. H.; Rajapakse, R. M. G.; Kumarasinghe, K. D. M. S. P. K.
Zinc-bromine flow batteries are crucial for large-scale energy storage. A key challenge is to develop a membrane that selectively allows bromide ions (Br⁻) to pass through while preventing bromine (Br₂) without compromising efficiency. Commercial membranes, while effective, tend to be expensive. This study focused on enhancing nanoporous membranes made from poly(methyl methacrylate) (PMMA) Perspex for application in zinc-bromine redox flow batteries. The method involved initially dissolving PMMA in dichloro methane (DCM) by varying both PMMA (from 1.000 ± 0.001 g to 3.000 ± 0.001 g) and DCM (from 20 to 35 cm³). After determining the optimal formulation for PMMA, silica (particle size range of 40-120 nm confirmed by a particle size analyser, with 99% purity determined by XRF analysis) synthesised from rice husks was added (1% to 10%). The solution was cast into an iron glass mould, and the pore size was measured. The data analysis revealed that the pore size is significantly decreased when silica concentration is increased. The optimal membrane formulation, consisting of 1.000 ± 0.001 g of PMMA and 25 cm³ of DCM, produced an average pore size of 30.84 μm. Upon incorporating 6% rice husk silica into this formulation, the average pore size was further reduced to 6.68 μm (confirmed by SEM), making this combination the most effective for achieving the smallest pore size. However, the commercial polyethylene membranes have pore sizes ranging from 0.17 to 0.85 μm. Further, a bromine diffusion test conducted over three hours showed that approximately 45% of the bromine diffused through the membrane, whereas the commercial polyethylene showed 5% bromine diffusion. Although the pores were in the micrometre range from SEM data, the overlapping layers of PMMA created a distinct nanostructure and would be the reason for moderate bromine diffusion. The findings of this research provide valuable insights into the factors influencing the optimization of nanoporous membranes and highlight the positive impact of incorporating silica nanoparticles on membrane performance in zinc-bromine redox flow batteries.
Determination of antioxidant and enzyme inhibitory activities of Osbeckia octandra L., Cissus quadrangularis, and Vitex negundo in Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya ,Sri Lanka, 2024-11-01) Mallawa Arachchi, M. A. K. H.; Mendis, B. E. P.; Siriwardhane, U.; Kalinga, J.; Piyasena, N. P.; Marikkar, J. M. N.; Adikaram, N. K. B.; Jayasinghe, L.
Medicinal plants have gained much attention for their therapeutic properties and diverse pharmacological effects. They are widely used in herbal healthcare practices for treating diseases. This study investigated three selected medicinal plants in Sri Lanka, traditionally used for digestive issues, bone ailments, and inflammatory conditions, to assess their in vitro bioactive potential: antioxidative, anti-hyperglycaemic, anti-obesity, and cytotoxic properties. Dried powdered samples of leaves from three medicinal plants, namely Osbeckia octandra L. (“Heen bovitiya”), Cissus quadrangularis L. (“Heeressa”), and Vitex negundo L. (“Nika”) was extracted with methanol (MeOH) via ultrasonication, followed by rotary evaporation to obtain crude extracts. The extracts were evaluated for total phenolic content (TPC) and total flavonoid content (TFC), which were separately quantified using the Folin Ciocalteu method [pyrogallol equivalent (PE)] and AlCl₃ colorimetric method [quercetin equivalent (QE)] respectively. Among the extracts, O. octandra possessed the highest TPC (291.69 ± 11.41 mg of GAE/g) and TFC (2.48 ± 0.17 mg of CE/g) values. Further, O. octandra exhibited the highest antioxidant activity in both FRAP assay (7268.00 ± 95.6 mmol FeSO4/g), positive control Trolox (13447.00 ± 19.80 mmol FeSO₄/g) and the DPPH radical scavenging assay (IC₅₀ = 11.43 ± 0.79 mg/L; positive control ascorbic acid; IC₅₀ = 3.46 ± 0.45 mg/L). Furthermore, of the three plants, only O. octandra exhibited minor inhibitory activity against α-amylase (IC₅₀ = 1129.8 ± 140.2 mg/L, positive control acarbose, IC₅₀ = 8.51 ± 0.67 mg/L). All three extracts showed significant α-glucosidase inhibitory activity at a concentration of 1000 mg/L, in which the O. octandra extract showed the highest inhibition of 99%. However, none of the extracts showed lipase inhibitory activity or brine shrimp lethality. Based on the findings, Osbeckia octandra L. demonstrated the most promising antioxidant potential among the three medicinal plants studied, which has the potential to be developed as an ingredient in functional foods and as an alternative remedy for managing non-communicable diseases.
Feeding guild composition of birds in selected urban, suburban, and forest ecosystems in Kandy, Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Rathnasiri, S. N.; Yatigammana, M. W. S. K.; Wijesundara, W. M. C. S.
Presence of different feeding guilds of birds is an indicator of the overall health of an ecosystem. This study aimed to investigate the health of three ecosystems representing different urbanization levels, Udawattakele forest, Talwatta suburb with fragmented tree cover, and Kandy downtown with scattered trees, by analysing bird feeding guild composition. The encounter transect method was employed with two-kilometre transects weekly during activity peaks (0600h-0900h and 1500h-1800h) from May to December 2023 in each ecosystem. Field guides were used to identify birds and their feeding guilds. Data were analysed using BioDiversity Professional (v. 2). Shannon H’ of Udawattakele, Talwatta, and Kandy downtown was 1.28, 1.44, and 0.58, and Shannon J’ was 0.69, 0.82, and 0.50, respectively. Of the 22 feeding guilds recorded, 17 were from Udawattakele and Talwatta, and 10 were from Kandy downtown. Five were exclusively from Udawattakele, seven were shared by Udawattakele and Talwatta, five were shared by Talwatta and Kandy downtown, and five were shared by all (67.7% Bray-Curtis similarity between Udawattakele and Talwatta; 36.11% between these and Kandy downtown). Insectivores were the dominant feeding guild in Udawattakele (28%) and Talwatta (22%), while the least abundant in Kandy downtown (7%). The scavengers were dominant in Kandy downtown (29%), whereas low in Udawattakele and Talwatta (0% and 5%). High numbers of raptors in Udawattakele (7 species) and Talwatta (4 species) indicate healthy ecosystems with abundant prey species. Frugivores, nectarivores and granivores were found in all three ecosystems. The insectivore-frugivore guild was highly prevalent in Udawattakele (12%) and Talwatta (19%). Udawattakele and Talwatta showed 72.7% similarity in feeding guilds of endemic species while reflecting the above general pattern. Higher feeding guild diversity in Udawattakele and Talwatta indicates their stability and health, whereas Kandy downtown shows poor ecosystem health with lower feeding guild diversity and biotic homogenization.
Effects of climatic variation on epiphytic cryptogamic diversity in the Kottawa rainforest, Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Dilrukshi, H. A. C.; Ruklani, N. C. S.; Rubasinghe, S. C. K.
Cryptogams offer early warning signals to identify climate change mitigation and adaptation strategies. Studying the responses of epiphytic cryptogams to changing environmental conditions is pivotal for conserving biodiversity. The Kottawa Rainforest in Sri Lanka hosts a rich diversity of epiphytic cryptogams, including fungi, lichens, bryophytes (mosses, liverworts, hornworts) and pteridophytes (ferns and fern allies). The present study investigated the impact of temperature, precipitation and humidity on the diversity of these organisms. Nine permanent sampling plots (10 m × 10 m) were randomly established in the Kottawa Rainforest. The presence and coverage of epiphytic cryptogams (fungi, lichens, bryophytes, and ferns) on the bark of each tree, from the base to Diameter at Breast Height (DBH), were determined using a transparent grid quadrat (20 cm × 20 cm). Sampling was conducted once a month from January to December 2023. Climatic factors, including precipitation, humidity and temperature, were recorded throughout the year. Specimens of epiphytic cryptogams in the study plots were collected and observed using a stereo microscope and identified to the species level using taxonomic keys. Pearson correlation coefficients and multiple regression analysis were conducted to assess the correlation between temperature, precipitation, humidity, and species diversity. The analysis revealed a significant negative correlation between temperature and species diversity (r = -0.92, p < 0.05), indicating higher temperatures are associated with lower cryptogam diversity. Conversely, precipitation positively correlated with species diversity (r = 0.35, p < 0.05), suggesting that increased precipitation supports greater cryptogam diversity. There was no significant correlation between humidity and species diversity (r = 0.42, p > 0.05). These findings indicate the sensitivity of cryptogam diversity to climatic variations, particularly temperature and precipitation. Therefore, conservation efforts are crucial to safeguard the biodiversity of epiphytic cryptogams in the face of ongoing climatic changes.
Adverse psychological effects of Kameshwari Modaka: a case study in Colombo district using the challenging experience questionnaire via online survey
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Manohara, M. G. R. K.; Sandunka, A. G. G.; Munasinghe, D. A. L.
“Kameshwari Modaka” (KM), an Ayurvedic drug traditionally used for its aphrodisiac properties, has recently been misused in Sri Lanka, particularly among youth seeking ecstasy-like effects. This study investigated the psychedelic experiences, specifically "bad trips", associated with KM misuse using the Challenging Experience Questionnaire (CEQ). From January to March 2024, an online survey gathered responses with a snowball sampling technique from 102 participants in the Colombo district (average age: 28.59 years; 96% male, 4% female). Results showed KM induces mild challenging experiences, including fear, isolation and, physical distress, with an average CEQ score of 21.31%. Most participants (60.8%) reported no or mild bad trip symptoms, but 13.7% experienced severe bad trips. Paranoia was significantly elevated compared to other serotonergic psychedelics (p < 0.05), suggesting potential psychological risks. KM's psychoactive effects are attributed to its high cannabis content, which can lead to acute psychosis and addiction in chronic use, especially with doses surpassing the therapeutic range of 3-6 g. Findings highlight the need for caution and regulatory measures in KM use, especially among younger demographics, despite the limitations of small sample size, lack of brand-specific data, recall bias, and variations in KM dosage of the present study. Further research is essential to explore demographic, psychological, and dosage-related factors influencing these adverse reactions. Clinical studies should validate findings and clarify KM's pharmacological mechanisms.
Comparative evaluation of water hyacinth, vegetable waste and gliricidia as nitrogen sources for composting paddy husk
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Shamudika, H. U.; Nadeesha, M. A. Y. L.; Hewawasam, H. P. C. P.; Jayasanka, D. J.
Paddy husk is one of the most widely produced agricultural wastes in rice production. The co-composting of paddy husk is an effective method for addressing this waste issue. This study aimed to transform ordinary paddy husk into high-quality compost using water hyacinth (Eichhornia crassipes), vegetable waste, and gliricidia (Gliricidia sepium) as nitrogen sources. The quality of the compost was compared using pH, electrical conductivity (EC), organic carbon (C), total nitrogen (N), available phosphorus (P), and exchangeable potassium (K). The experiment followed a Completely Randomized Design (CRD) with four treatments: T1 = paddy husk only, T2 = paddy husk + water hyacinth, T3 = paddy husk + Gliricidia, and T4 = paddy husk + vegetable waste, mixed in a 1:1 ratio. The mixtures were aerobically decomposed using the compost pile method and analysed after 67 days. The results were compared with the compost standards provided by the Sri Lanka Standards Institution. A pot experiment was conducted to evaluate the effect of the prepared compost on the growth of water spinach (Ipomea aquatica). The pH values of all trials ranged between 6.5 and 7.9, and EC values ranged from 0.13 dS/m to 0.977 dS/m. The T2 compost mixture (paddy husk + water hyacinth) showed significantly higher (p < 0.05) levels of total nitrogen (1.15% ± 0.03) and potassium (0.466% ± 0.01) compared to other mixtures. The T3 compost mixture (paddy husk + gliricidia) exhibited the highest phosphorus level (1.33% ± 0.08). Low potassium levels were consistent across all compost mixtures. Considering the pH, EC, total nitrogen, and phosphorus levels obtained for the T2 mixture (pH 7.96, EC 0.977 dS/m, N 1.15%, and P 1.257%), along with the highest fresh weight (6.836g ± 0.373) and dry weight (0.6075g ± 0.037) of plant samples from the pot experiment, the compost mixture containing paddy husk and water hyacinth was found to be the most suitable for field application.
Bioactivity of Strychnos potatorum seeds and derived product: antioxidant, anti-inflammatory and cytotoxic properties
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Pathirana, G. H. P. S. S.; Herath, K. K. D. P.; Kuruppu, A. I.
Strychnos potatorum is widely recognized for its medicinal and industrial applications due to its bioactivity, which includes antioxidant, anti-inflammatory, and anti-microbial properties. This study evaluated the bioactivity of S. potatorum seeds, and a product derived from the seeds was evaluated. Ethanolic extracts were subjected to bioassays in vitro. The total phenolic content (TPC) was measured by the Folin-Ciocalteu assay, and the seed extract showed a TPC value of 0.58 ± 0.05 GAE/g, while the product showed a TPC of 0.68 ± 0.13 GAE/g (p > 0.05). The total flavonoid content (TFC) was determined by the aluminum chloride colorimetric method, in which the TFC values for the seed extract and the product were 0.12 ± 0.01 QE/g and 0.30 ± 0.06 QE/g, respectively (p < 0.05). The antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, where a maximum radical scavenging value of 70.48% ± 1.86 at 1 mg/mL was found for the seed extract. A similar value was obtained for the product extract; 70.70% ± 0.93 at 1 mg/mL (p > 0.05), while ascorbic acid which was the standard showed 75.55% ± 2.18 (1 mg/mL). The Human Red Blood Cell Membrane Stabilization (HRBC) assay was conducted, and the anti-inflammatory results depicted 78.41% ± 3.13 for the seed extract and 83.16% ± 1.73 for the product extract for 1 mg/mL (p > 0.05). Standard Ibuprofen showed a value of 5-diphenyltetrazolium bromide (MTT) assay against the HepG2 liver cancer cells. The seed extract showed a maximum cancer cell inhibitory value of 37.19% ± 0.80 at 1 mg/mL, and the product showed a value of 40.18% ± 0.90 at 1 mg/mL (p > 0.05). The product generally showed higher bioactivity than the seed extract, although the differences were not always statistically significant. The bioactivity of the derived product is similar to that of the raw seeds, highlighting the potential health benefits of the derived product.
Morphological characterization of two promising lines of common bean, Phaseolus vulgaris L.
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Ekanayake, E. M. B. N.; Daundasekera, W. A. M.; Dissanayaka, N. B. U.
The common bean, Phaseolus vulgaris L., is widely grown in Sri Lanka. The Horticultural Crop Research and Development Institute (HORDI) at Gannoruwa, Sri Lanka, follows the “Variety Releasing Protocol (VRP)” to ensure the uniformity of new bean varieties before their market release. During this process, testing for uniformity based on morphological characters is an important aspect. CP-3 and CP-4 are two new bean accessions currently under Variety Adaptability Testing (VAT) by the HORDI. The objective of this study was to compare the morphological characteristics of these two selected bean accessions. Morphological characters in flowers, leaves, pods and seeds were studied using descriptors prepared by the Plant Genetic Resource Centre at Gannoruwa. Flower characters, including the number of flower buds per inflorescence and the colour of the standard and wing petals, were determined using the Royal Horticultural Society colour chart. Pod characters measured included length (cm), width (mm), the shape of cross-section, colour, curvature, suture strings, beak length, surface, and beak orientation. Ten replicates were evaluated for each parameter. Data were analysed using One-way ANOVA followed by Mann-Whitney pairwise test at a 95% confidence level (p ≤ 0.05) using PAST statistical software. Results revealed that characteristics such as hypocotyl colouration, growth type, time of flowering, number of flower buds per inflorescence, the colour of standard petal, pod shape in cross-section, pod ground colour, pod beak position, pod wall fibre constrictions, texture of pod surface, seed colour and seed shape were similar in both bean accessions. In contrast, inflorescence length, pod length, width, suture strings, beak length, pods per inflorescence, seeds per pod, seed width, length and height were different between the CP-3 and CP-4 accessions. The pod length and width in CP-3 were significantly (p ≤ 0.05) greater than those in CP-4, highlighting these parameters as important for distinguishing between the two accessions during the variety release process.
Morphological and biochemical characterization of efficient diesel-degrading bacteria isolated from petroleum-contaminated subsurfaces
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Nugapitiya, E. M. M. R. P. V.; Samaraweera, P.
The widespread use of petroleum products like diesel has led to environmental contamination, necessitating studies aimed at minimizing its impact upon release into the environment. Among the potential petroleum-degrading microbes, previous studies have identified bacteria as the most effective. However, bioremediation success relies on identifying native bacteria from contaminated sites, as they are better suited to local conditions. Degradation of complex hydrocarbons like diesel requires multiple bacterial species, as no single strain can break down all its components. Thus, this study aimed to characterize and identify efficient diesel-degrading bacteria from petroleum-contaminated soil collected from garages in Kandy, Sri Lanka, and to design bacterial consortia that can efficiently degrade diesel. Diesel-utilizing bacteria in collected soil samples were enriched using Bushnell Haas broths supplemented with diesel. Potential diesel-degrading bacteria were isolated using spread plating and streak plating techniques. These isolates were subjected to turbidity assay and 2,6-Dichlorophenolindophenol (2,6-DCPIP) assay to quantitatively determine the most effective degrading bacteria. The recognised efficient bacteria were characterised using morphological and biochemical tests and were used to design bacterial consortia. Based on the findings of the quantitative tests, three of the isolated diesel-degrading bacteria were determined to be the most efficient. The morphological and biochemical test results led to the subsequent identification of these three isolates as belonging to the genera Klebsiella, Enterobacter, and Staphylococcus. Of these, Klebsiella was shown to be 5.87% and 10.87% more effective than the other two isolates, respectively. Of the four bacterial consortia that were designed using pure bacterial isolates, three consortia were more successful at degrading diesel than the individual bacterial isolates based on the 2,6-DCPIP assay. It showed that the consortium consisting of Enterobacter and Klebsiella was the most successful. The findings of this study can be employed for bioremediation of diesel-contaminated sites.
Quantification of ascorbic acid content in Ziziphus oenoplia (l.) Mill. (“Eraminiya”) seeds grown in the wet zone of Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Sewwandi, W. V. L.; Gunathilake, B. M. H.; Gunarathna, W. G. I. M.; Jayasundara, J. M. R. D.; Rasanjanee, D. D. Y.; Jinadasa, B. K. K. K.
Ziziphus oenoplia (L.) Mill., commonly known as "Eraminiya" in Sinhala, is a traditional medicinal plant found in the Wet Zone of Sri Lanka. This study quantified the ascorbic acid content in its seeds as part of broader research on the antioxidant properties of its fruit and seeds, highlighting their potential health benefits, such as enhancing immune function and reducing oxidative stress. A representative sample of 1 kg was collected, consisting of 150 g each of yellow-green and black fruits (four months post-flowering) from different districts in the Wet Zone. Seeds were separated from the fruits and the Indophenol dye method was used for quantification. Statistical analysis revealed a significant difference (p < 0.05) between ascorbic acid content in Z. oenoplia seeds (56.7 mg 100 g ⁻ ¹) and the fruit (195 mg 100 g ⁻ ¹). This value is lower than common fruits such as lemons (199.81 mg 100 g ⁻ ¹) and oranges (141.34 mg 100 g ⁻ ¹), possibly due to differences in antioxidant requirement between seeds and fruits, variations in biochemical compositions, and the specific plant part analysed. However, Z. oenoplia seeds have relatively higher ascorbic acid content than other seeds like pomegranate (12.5 mg 100 g ⁻ ¹), orange (20 mg 100 g ⁻ ¹), and watermelon (8.5 mg 100 g ⁻ ¹) due to the plant’s unique phytochemical composition and its adaptability to the Wet Zone climate in Sri Lanka. While the seeds are not typically consumed, their antioxidant properties suggest potential for use in dietary supplements. Further research could explore their application in the pharmaceutical industry.
Cause and effect analysis of impacts of land cover changes on Belihuloya mini-catchment area
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Gunathilake, L. W. I.; Jayawardhana, D. T.; Chandrasekara, C. M. K. N. K.
The rapid expansion of human activities has significantly transformed landscapes, leading to major impacts on water resources and ecosystem health. This study comprehensively assessed the transformations within the Belihuloya mini catchment, focusing on the effects of land use and land cover changes. The primary objectives included identifying changes, analyzing trends, and evaluating human perceptions of the impacts on the mini catchment. The study utilised remotely sensed data from 1959, 1988, 2000, and 2020 to assess land use and cover changes over time. A questionnaire survey was conducted among 60 randomly selected households across six Grama Niladhari Divisions within the catchment area. Correlation-based pair-wise analysis, paired t-test analysis, vulnerability value calculation, and interpolation mapping were employed to interpret the data. A cause-and-effect analysis was conducted using the Drivers-Pressures-State-Impacts-Responses (DPSIR) framework. The results revealed significant changes in land cover and use over the study period. Forest cover decreased dramatically, from 80% in 1959 to 33% in 1988, primarily due to the expansion of paddy fields and home gardens. Nine major driving forces were identified, highlighting the pressures on the natural environment and wildlife from land and forest clearance for construction. High-altitude areas surrounding the young Belihuloya river faces significant risk due to rapid land use changes, threatening the river's energy flow. The southern region, including Sabaragamuwa University and the Samanalawewa reservoir, is equally vulnerable, potentially compromising the mini-catchment's health. The findings underscore the urgent need for conservation efforts and informed land management practices to mitigate adverse impacts on the mini-catchment ecosystem and ensure sustainable development for future generations.
Preparation and characterization of microbeads from post-consumer poly(ethylene terephthalate) bottles
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya, Sri Lanka, 2024-11-01) Ananda, N. D. W. Y.; Nikahetiya, I. U. S.; Gunathilake, W. S. S.
Plastic pollution is a formidable challenge to the environment, posing threats to humankind. The demand for plastic continues to surge, with poly(ethylene terephthalate) (PET) serving as a prominent contributor to the problem. Due to its impressive durability, it has a wide range of applications in packaging, mainly as PET bottles. The objective of this study was to derive and characterize microbeads from post-consumer PET bottles. In this study, first, a solvent system was developed to dissolve PET using dichloromethane (DCM) and trifluoroacetic acid (TFA) by varying the ratio of DCM to TFA. The PET concentration optimization was carried out by varying the PET mass dissolved in the optimized solvent system. The microbead synthesis was carried out with an ionotropic gelation technique using two methods: manual process and electrospraying process using the electrospraying unit. In each process, a collector solution, which consisted of distilled water, glutaraldehyde, and sodium dodecyl sulphate (SDS), was used to collect the microbeads. The optimization of glutaraldehyde and SDS concentrations was carried out by varying the concentration of glutaraldehyde between 0% to 0.5% and SDS concentration from 1 × 10 ⁻ ⁴ g/mL to 1 × 10 ⁻ ¹ g/mL. The bead size optimization was carried out by varying the distance between the needle tip and the collector solution between 5.0 cm and 30.0 cm. The beads were characterised using digital microscopic imagining, Fourier transform infrared spectroscopy and thermogravimetric analysis. According to the results, the optimized solvent system was recorded as 1:5 DCM to TFA, PET concentration was 15% (w/v), and optimized concentrations of glutaraldehyde and SDS were 0.1% (v/v) and 1×10 ⁻ ⁴ g/mL, respectively. Spherical beads were formed with both methods with an average diameter of 744.9 ± 38.6 μm and a wide service temperature range of up to 450 °C, which collectively underscores the potential of repurposing PET to microbeads.

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