http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/5713 2026-08-30T13:43:03Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12900 Title: Na2FeSiO4 as a sodium-ion battery material: A computational perspective Authors: Sriraam, R.; Abiman, P.; Iyngaran, P.; Kuganathan, N. Abstract: Polyanionic silicate-based cathode materials have attracted considerable attention due to their intrinsic structural stability, strong thermal and chemical resistance, and ability to achieve high operating voltages through the inductive effects of polyanion groups. In this study, atomistic simulations were conducted to explore the energetics of intrinsic point defect formation, Na-ion migration pathways, and dopant incorporation in Na2FeSiO4, providing key insights into its viability as a cathode material for sodium-ion batteries (SIBs). Among the native defects, the Na Frenkel pair exhibited the lowest formation energy, suggesting a natural preference for vacancy-mediated Na-ion migration. The calculated migration energy barriers of 0.38 and 0.41 eV further support the material’s capability for efficient sodium-ion transport. Doping analysis identified K, Zn, and Ge as the most favorable isovalent dopants at the Na, Fe, and Si sites, respectively, while Ga showed a strong tendency to substitute at Fe sites and facilitate Na-vacancy formation. Furthermore, Al substitution at the Si site was found to increase the overall sodium content in the lattice. The electronic structure of these promising dopants was further investigated using density functional theory (DFT), offering deeper insights into their influence on the electrochemical behavior of Na2FeSiO4. 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9558 Title: Ruthenium (Ru) Doped Titanium Dioxide (P25) Electrode for Dye Sensitized Solar Cells Authors: Rajaramanan, T.; Natarajan, M.; Ravirajan, P.; Senthilnanthanan, M.; Velauthapillai, D. Abstract: In this study, P25-titanium dioxide (TiO2) was doped with ruthenium (Ru) by systematically varying the Ru content at 0.15, 0.30, 0.45 and 0.6 mol%. The synthesized Ru-doped TiO2 nanomaterials have been characterized by X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray (EDX) analysis, UV-visible (UV–Vis) spectroscopy, and electrochemical impedance (EIS) spectroscopy. The XRD patterns of undoped and Ru-doped TiO2 nanomaterials confirm the presence of mixed anatase and rutile phases of TiO2 while EDX spectrum confirms the presence of Ti, O and Ru. Further, UV-visible absorption spectra of doped TiO2 nanomaterial reveal a slight red shift on Ru-doping. The short circuit current density (JSC) of the cells fabricated using the Ru-doped TiO2 photoanode was found to be dependent on the amount of Ru present in TiO2. Optimized cells with 0.3 mol% Ru-doped TiO2 electrodes showed efficiency which is 20% more than the efficiency of the control cell (η = 5.8%) under stimulated illumination (100 mWcm−2 , 1 sun) with AM 1.5 filter. The increase in JSC resulted from the reduced rate of recombination upon doping of Ru and this was confirmed by EIS analysis. 2020-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9557 Title: Antimicrobial activity of Azadirachta Indica (neem) leaf, bark and seed extracts Authors: Raja Ratna Reddy, Y.; Krishna Kumari, C.; Lokanatha, O.; Mamatha, S.; Damodar Reddy, C. Abstract: Screening of medicinal plants for bioactive compounds leads to development of less expensive new antimicrobial agents with improved safety and efficacy. Azadirachta Indica (neem) is a multipurpose tree with multiple health benefits. Different parts of the plant are shown to exhibit antimicrobial effects against a wide variety of microorganisms. In the present study we compared the antimicrobial efficacy of aqueous extracts of leaf, bark and seeds of A. Indica against human pathogenic bacteria (Staphylococcus aureus, Enterococcus feacalis, Proteus mirabilis and Pseudomonas aeuroginosa) and fungi (Aspergillus fumigatus and Candida albicans). Agar well diffusion method and micro-broth dilution methods were used to determine the minimum inhibitory concentration (MIC). Results showed that leaf extract exhibited strong antimicrobial activity against bacteria and fungi at all the concentrations tested (500, 1000 and 2000µg/ml). Antimicrobial activity of bark extract was found to be moderate on bacteria and fungi (effective at 1000 and 2000µg/ml), whereas seed extract exhibited least antimicrobial activity. Minimum inhibitory concentration (MIC) of leaf and bark extract was found to be in the range of 500 to 2000µg/ml for all the tested microorganisms, where as the seed extract did not inhibit the microorganisms at all the concentrations tested except Candida albicans (1000µg /ml). Our results suggest that aqueous extracts of Azadirachta Indica leaf and bark exhibit high antimicrobial activity. 2020-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/9539 Title: Impact of water quality on Chronic Kidney Disease of unknown etiology (CKDu) in Thunukkai Division in Mullaitivu District, Sri Lanka Authors: Kalaivani, G.; Prabagar, S.; Uthpala Apekshani, J.; Gobalarajah, R.; Sittampalam, R.; Prabagar, J. Abstract: Background: Increase in the number of cases in Chronic Kidney Disease of Unknown etiology (CKDu) in Sri Lanka has become a health issue of national concern. Even though, Northern Province is not identified as a high-risk province, there is an increasing trend of CKDu after the end of civil war in the Northern Province. Methods: The present study was conducted in Thunukkai Division in Mullaitivu District to investigate the socio demographic and clinical pattern of CKDu patients and to evaluate the quality of their water sources. The samples were selected by using stratified purposive random sampling method which represented 29% of total CKDu patients in Thunukkai Division. Pretested structured questionnaire was administered to collect the data from the CKDu patients. The association between serum creatinine excreted by CKDu patients and the water quality parameters were determined by using linear regression model. Results: Among the patients, 80% were male with over 68% falling in the age range of 50–70. Majority (90%) were involved in agriculture related occupation. Smoking and alcohol consumption were detected as common habits among 40% of the patients. Secondarily developed, hypertension (60%) and diabetes (34%) were reported as common diseases in the area. Dug wells served as the commonest source of drinking water in the area (90% households) together with few tube wells. Physicochemistry of more than 50% of the water samples revealed higher electric conductivity, salinity, total dissolved solids, total hardness and Na levels compared to drinking water standards in Sri Lanka. Conclusions: Serum creatinine levels of the CKDu patients were significantly and negatively correlated with phosphate while positively correlated with total dissolved solids (TDS) and arsenic content of the drinking water. Geospatial mapping of TDS and arsenic in drinking water with the occurrence of higher serum creatinine levels confirmed the same trend. Thus, the total dissolved solids and arsenic in drinking water may have positive correlation with the occurrence of CKDu in Thunukkai region in the Mullaitivu District of Sri Lanka. 2020-01-01T00:00:00Z