Research Papers - School of Natural Sciences
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Publication Open Access Coconut Shell Waste-Derived Porous Carbon-Supported Sn Catalysts for Efficient Electrochemical CO2Reduction to Formic Acid and Deuterated Formic Acid(American Chemical Society, 2025-11-05) Qin, C; Masakorala, G; Mohideen, M; Samarasekara, T; Zhang, L; Zhu, W; Zhou, Y; Thambiliyagodage, CIndustrial-level electrochemical CO2 reduction reaction (CO2RR) to form HCOO– and DCOO– requires robust Sn catalysts with high performance. In this study, the hydrothermal method was employed to load varying amounts of Sn precursors onto waste biomass-derived porous carbon to investigate the structure–activity relationship between Sn loading forms and HCOO– selectivity. Through comprehensive ex/in situ characterizations, we discovered that with 5% Sn precursor addition, highly dispersed SnO2 nanoparticles formed on the carbon support, enabling the catalyst to exhibit exceptional HCOO– activity (Faradaic efficiency exceeding 90%) across a broad potential window. In situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and in situ Raman spectroscopy revealed that the highly dispersed SnO2 nanoparticles enhance the stability of the *OCHO intermediate. Furthermore, when H2O was replaced with D2O, the generation of DCOO– was observed, and good selectivity was maintained. This study provides a facile strategy for waste biomass conversion and the design of Sn-based catalysts for DCOO– production.Publication Open Access ZIF-8 confined carbon dots/bilirubin oxidase on microalgal cells to boost oxygen reduction reaction in photo-biocatalytic fuel cells for pollutants removal(Elsevier B.V., 2026-01) Qing, S; Lu, X; Jiang, Y; Thambiliyagodage, C; Song, B; Xia, A; Zhang, J.R; Zhu, W; Jiang, L.P; Wu, XPhotocatalytic fuel cells provide promising opportunities for sustainable wastewater treatment and energy conversion. However, their applications are challenged by the sluggish oxygen reducton reaction (ORR) kinetics at cathodes owning to the low O2 solubility and diffusion rate. Herein, we proposed a photo-biocatalytic fuel cell (PBFC) with a novel hybrid biocathode based on artificially engineered algal cells coated by ZIF-8 confined carbon dots/bilirubin oxidase (ZIF-8/CDs/BOD@algae). Microalgae absorbed CO2 and provided O2 in situ for BOD catalysts. Due to effective absorption of O2 by imidazole and confinement of hydrophobic porous ZIF-8, oxygen diffusion has been accelerated in MOF/enzyme systems. Importantly, the introduction of CDs alleviated the poor conductivity of ZIF-8 and improved the electron transfer rate of BOD. Thus, the biocathode exhibited a high current density of 1767 μA/cm2, a 2.26-fold increase compared with that of CDs/BOD/algae biocathode. Also, it displayed enduring operational stability for up to 60 h since the firmly wrapped ZIF-8 shells could encapsulate proteins and protect algae from the external stimulation. When coupled with Mo:BiVO4 photoanodes, the PBFC exhibited a remarkable power output of 131.8 μW/cm2 using tetracycline hydrochloride (TCH) as a fuel and an increased degradation rate of TCH. Therefore, this work not only establishs an effective confinement strategy for enzyme to enrich oxygen, but also unveils new possibilities for modified microalgal cells aiding photoelectrocatalytic systems to recover energy from wastewater treatment.Publication Open Access Early Diagnosis and Severity Assessment of Weligama Coconut Leaf Wilt Disease and Coconut Caterpillar Infestation Using Deep Learning-Based Image Processing Techniques(Institute of Electrical and Electronics Engineers Inc., 2025-02-03) Vidhanaarachchi, S; Wijekoon, J. l; Abeysiriwardhana, W. A. S.P; Wijesundara, MGlobal Coconut (Cocos nucifera (L.)) cultivation faces significant challenges, including yield loss, due to pest and disease outbreaks. In particular, Weligama Coconut Leaf Wilt Disease (WCWLD) and Coconut Caterpillar Infestation (CCI) damage coconut trees, causing severe coconut production loss in Sri Lanka and nearby coconut-producing countries. Currently, both WCWLD and CCI are detected through on-field human observations, a process that is not only time-consuming but also limits the early detection of infections. This paper presents a study conducted in Sri Lanka, demonstrating the effectiveness of employing transfer learning-based Convolutional Neural Network (CNN) and Mask Region-based-CNN (Mask R-CNN) to identify WCWLD and CCI at their early stages and to assess disease progression. Further, this paper presents the use of the You Only Look Once (YOLO) object detection model to count the number of caterpillars distributed on leaves with CCI. The introduced methods were tested and validated using datasets collected from Matara, Puttalam, and Makandura, Sri Lanka. The results show that the proposed methods identify WCWLD and CCI with an accuracy of 90% and 95%, respectively. In addition, the proposed WCWLD disease severity identification method classifies the severity with an accuracy of 97%. Furthermore, the accuracies of the object detection models for calculating the number of caterpillars in the leaflets were: YOLOv5-96.87%, YOLOv8-96.1%, and YOLO11-95.9%.Publication Open Access Event Detection and Classification for Long Range Sensing of Elephants Using Seismic Signals(Institute of Electrical and Electronics Engineers Inc., 2025-09-08) Wijayaraja, J.L; Wijekoon, J.L; Wijesundara, MDetecting elephants through seismic signals is an emerging research topic aimed at developing solutions for Human-Elephant Conflict (HEC). Despite the promising results, such solutions heavily rely on manual classification of elephant footfalls, which limits their applicability for real-time classification in natural settings. To address this limitation and build on our previous work, this study introduces a classification framework targeting resource-constrained implementations, prioritizing both accuracy and computational efficiency. As part of this framework, a novel event detection technique named Contextually Customized Windowing (CCW), tailored specifically for detecting elephant footfalls, was introduced, and evaluations were conducted by comparing it with the Short-Term Average/Long-Term Average (STA/LTA) method. The yielded results show that the maximum validated detection range was 155.6 m in controlled conditions and 140 m in natural environments. Elephant footfall classification using Support Vector Machine (SVM) with a Radial Basis Function (RBF) kernel demonstrated superior performance across multiple settings, achieving an accuracy of 99% in controlled environments, 73% in natural elephant habitats, and 70% in HEC-prone human habitats, the most challenging scenario. Furthermore, feature impact analysis using explainable AI identified the number of Zero Crossings and Dynamic Time Warping (DTW) Alignment Cost as the most influential factors in all experiments, while Predominant Frequency exhibited significant influence in controlled settings.Publication Open Access The photocatalytic and antibacterial activity of graphene oxide coupled CoOx /MnOx nanocomposites(Elsevier B.V., 2025-02) Liyanaarachchi, H; Thambiliyagodage, C; Jayanetti, M; Ekanayake, G; Wijayawardana, S; Samarakoon, UCoOx and MnOx metal oxide composites were fabricated via co-precipitation varying the Co:Mn (CM) weight ratio as 4:1, 2:1, 1:1, 1:2 and 1:4, and they hydrothermally coupled with 30 wt% of graphene oxide (GO). XRD analysis revealed the presence of Co3O4 and CoO, and Mn2O3 and Mn3O4 phases in pure CoOx and MnOx metal oxides, respectively. The irregularly shaped metal oxide nanocomposites comprised Co3O4, Mn2O3 and Mn3O4 phases and were immobilized on GO. The band gap values of the composites varied in the range of 1.86 – 2.22 eV. The highest photocatalytic activity with a rate constant of 3.5 × 10−3 min−1 was obtained with CMG (1:4). The total removal of MB increased by 55.8 % when CM (1:4) were coupled with GO. The rate of photocatalysis was dramatically increased in the presence of S2O82- and was decreased in the presence of EDTA and isopropyl alcohol. The effect of catalyst dosage was determined by varying the weight to 25, 50, 75, and 100 mg, and the dye concentration was varied in the range of 25, 50, 75 and 100 mg/L. The presence of Pb2+ and Rhodamine B decreased the photocatalytic activity, while it remained the same in the presence of Cl- and PO43- as co-pollutants. The photocatalytic activity of CMG (1:4) was reduced to 72 % upon using the catalyst for five cycles. All the synthesized nanocomposites exhibited greater sensitivity to the Gram-positive strain than the Gram-negative strains.Publication Embargo A Comprehensive Investigation of Microplastic Contamination and Polymer Toxicity in Farmed Shrimps; L. vannamei and P. monodon(Springer Nature, 2025-02-20) Jayaweera, Y. U; Hennayaka, H. M.A.I; Herath, H.M.L.P.B; Kumara, G. M.P; Mahagamage, M.G.Y.L; Rodrigo, U.D; Manatunga, D. CMicroplastic (MP) pollution poses a significant threat to marine ecosystems, seafood safety, and human health. This study investigates the accumulation of microplastics in two commercially important shrimp species, Litopenaeus vannamei (L. vannamei) and Penaeus monodon (P. monodon), sourced from cluster farming sites in Puttalam, Sri Lanka. Shrimp exoskeletons and edible soft tissues underwent rigorous microplastic analysis, including density separation, alkali digestion, stereo microscopy, and Raman spectroscopy. The results revealed high microplastic contamination, with L. vannamei containing an average of 4.99 ± 1.81 MP particles/g and P. monodon containing 1.87 ± 0.55 MP particles/g. Microplastic sizes varied, with L. vannamei predominantly contaminated with 100–250 µm particles and P. monodon with 500 µm—1000 µm particles. Fiber morphotypes were prevalent in L. vannamei, while blue-colored microplastics were dominant in P. monodon. These comprised polystyrene (PS), nylon 6,6, and polyethylene (PE) which were identified by Raman spectroscopy. Additionally, the study investigated the acute toxicity effects of microplastic polymer combinations using a zebrafish embryo model (FET236 assay). Zebrafish embryos exposed to polyethylene-nylon 6,6 combinations exhibited significant adverse effects on hatching, survival, and heart function at lower concentrations, while polyethylene terephthalate-polystyrene combinations showed no considerable effects. These findings underscore the urgent need for monitoring and managing microplastic contamination in shrimp farming areas. Future research should focus on elucidating the ecological impacts and human health risks associated with microplastic exposure.Publication Embargo Facile synthesis of silver/iron-TiO2 nanoparticles for sterilization of Nodal explants of Dracaena sanderiana Sander ex Mast. cvs ‘Gold’ and ‘Victory’ and growth regulator effects on in vitro growth(OICC Press, 2025-02-08) Seneviratne, K.L; Peiris, S. E.; Peiris, C. N; Shashikala, R. P. A; Jayasinghe, S; Kottegoda, NThis study investigates the application of silver/iron-titanate (Ag/Fe-TiO2) nanoparticles (NPs) as a sterilizing agent for in vitro cultures of Dracaena sanderiana cultivars ‘Gold’ and ‘Victory’. The motivation behind this research is to find an effective sterilization method that does not harm plant growth. The Ag/Fe-TiO2 NPs, activated by visible light, exhibit catalytic properties that eliminate harmful microbes such as Escherichia coli, Staphylococcus aureus, and Fusarium spp. The main findings indicate that the combination of Benzyl Amino Purine (BAP) at 1.5 mg/L and Indole Acetic Acid (IAA) at 0.01 mg/L significantly enhances shoot number and length in both cultivars. The use of 200 mg/L Ag/Fe-TiO2 NPs achieved 90% contamination-free cultures in the first cycle, with a slight decrease to 80% in the second cycle and 70% in the third cycle. Importantly, the treatment not only sterilizes but also promotes plant growth, suggesting that Ag/Fe-TiO2 NPs could be a sustainable solution for in vitro plant mass production. © 2025 The Author(s)Publication Open Access Kinetic Study of In Vitro Release of Neem from Chitosan Biopolymer and Assessment of Its Biological Effectiveness(Multidisciplinary Digital Publishing Institute (MDPI), 2025-03-06) Nishshanka, Y; Thambiliyagodage, C; Jayanetti, MThe study examined the sustained release of neem from the polymeric carrier system chitosan by varying the drug content, ionic strength of the release medium, and pH. Six different kinetic models, i.e., Korsmeyer–Peppas (KP), Peppas–Sahlin (PS), Higuchi, Hixson–Crowell, Zero order, and First order were used to investigate the drug release kinetics. Based on the R2 values, the KP and PS models were chosen from the examined models to study the drug release mechanism from the chitosan biopolymer. The values found for model parameters n and m in the KP and PS models differ noticeably, suggesting that Fickian diffusion and Case II relaxation are important components of the neem release mechanism from chitosan. At lower ionic strengths and lower pH values, neem is released from the composite mostly by Fickian diffusion. The diphenyl-2-picrylhydrazyl assay served to assess the composite’s antioxidant properties. The composite’s antioxidant properties ranged from 3.56 ± 1.89% at 10 μg/mL to 51.28 ± 1.14% at 70 μg/mL. The ability of the composite to inhibit the denaturation of egg albumin was also tested and it ranged from 59.68 ± 0.93% at 25 μg/mL to 187.63 ± 3.53% at 1600 μg/mL. The drug composite has exhibited antibacterial activity against Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, and proved to be highly effective against P. aeruginosa at lower concentrations and against S. aureus at higher concentrations. The resulting inhibition zones for P. aeruginosa at 5 and 10 mg/mL concentrations were 16.5 ± 2.25 mm, and 14.83 ± 0.6 mm, respectively, whereas for S. aureus, it was 16.67 ± 0.33 mm at 20 mg/mL. The neem–chitosan composite’s minimum inhibitory concentration/minimum bactericidal concentration ratio for K. pneumoniae, P. aeruginosa, and S. aureus was greater than 4, suggesting that they trigger bacteriostatic outcomes, whereas for E. coli, it was 4, which means that bactericidal effects were evident.Publication Embargo Phylogenetic reassessment and epitypification of Exobasidium vexans causing blister blight of tea(Springer Nature, 2025-05-02) Sinniah, G.D; Kulatunga, D. C.M; Pandey, A. K; Sharma, H. K; Colombage, N. P; Udayanga, DExobasidium vexans is an important tropical phytopathogenic fungus that causes blister blight in tea. Despite its devastating impact on tea cultivation, this pathogen remains poorly studied. In this study, fresh symptomatic leaf samples of blister blight were collected from the main tea-growing regions of Sri Lanka and from Northeast and Eastern India, where the disease was originally reported. Fresh collections obtained from each locality were characterized based on micromorphological characters and molecular data and an epitype was designated. A molecular phylogeny based on the ITS (ribosomal nuclear internal transcribed spacer 1, 5.8S, internal transcribed spacer 2), 28S rDNA (largest subunit of ribosomal gene partial sequence), and TEF-1α (translation elongation factor-1 alpha) revealed that E. vexans collections represent a monophyletic clade closely related to E. reticulatum. This study provides crucial insights into the phylogenetic position and genetic diversity of E. vexans, offering a foundation for future studies on its biology, epidemiology, and management to mitigate impact on global tea production.Publication Open Access Utilization of E-Health Technology in Optimizing Health Services to Increase Patient Satisfaction(Cahaya Ilmu Cendekia, 2025-06-13) Kelegama, T; Ona, R.E; Abdullahi, M. Rurpose of the study: This study aims to explore the utilization of e-health technology in health service delivery and its impact on patient satisfaction through a comprehensive and contextual qualitative approach. Methodology: The approach used in this study is a qualitative approach with the aim of providing a comprehensive and in-depth picture of e-Health-based Health Service Innovation in Increasing Public Satisfaction at Community Health Centers. Main Findings: This study shows that e-health utilization is influenced by the type of service, age, and digital literacy. Online registration is the most preferred, while other features are less understood. Patient experiences include efficiency, digital literacy barriers, technical constraints, and satisfaction that vary. The main influencing factors are age, access to technology, health worker attitudes, and application design. Health workers play a key role in facilitating the digital transition, with patients expecting a simpler, more inclusive, and trained system. Novelty/Originality of this study: This study offers new insights into how digital literacy, patient context, and health worker support affect the acceptance and effectiveness of e-health services. It contributes to knowledge by highlighting the importance of user-centered implementation and the role of health professionals in facilitating digital transitions in healthcare.