Research Papers - School of Natural Sciences
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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 Embargo Visible Light Active Silver Decorated Iron Titanate/Titanium Dioxide Nanohybrid for Sterilization of Explants Grown by In Vitro Technique(John Wiley and Sons, 2022-12-04) Seneviratne, K .L; Munaweera, I; Peiris, S. E; Kodithuwakku, P; Peiris, C. N; Kottegoda, NVisible light (VL) active silver decorated iron titanate/titanium dioxide (Ag-FeTiO3/TiO2) nanohybrids derived from natural ilmenite sand effectively cleanse the exophytic plant pathogens in explants grown by in vitro techniques. VL active nanohybrid is synthesized by acid-hydrolysis of natural ilmenite, followed by precipitation of the lixivium and decoration with Ag onto FeTiO3/TiO2 nanoparticles, and finally calcination under a nitrogen environment to obtain Ag-FeTiO3/TiO2. A morphological study conducted using transmission electron microscopy (TEM) confirms the formation of Ag-FeTiO3/TiO2. Powder X-ray diffraction (PXRD) analysis shows that the nanohybrid primarily consists of anatase, iron titanate (FeTiO3), Ag2O, and Ag. X-ray photoelectron spectroscopy (XPS) study suggests the presence of Ag0/Ag2O/Fe2O3 composites on the FeTiO3/TiO2 particle surface. The optical band gap significantly changes from 3.14 eV (ilmenite) to 2.80 eV after the decoration of FeTiO3/TiO2 with Ag. This nanohybrid is utilized as a surface-sterilizing agent for in vitro establishment of the Dracaena sanderiana Sander ex Mast plant. Findings illustrate Ag-FeTiO3/TiO2 nanohybrid-based photo-sterilization leads to the survival of 90% of the microbes’ free cultures while the material can be re-used due to its photocatalytic behavior. Thus, the newly synthesized nanohybrid can replace harmful sterilization agents used in tissue culture techniquesPublication Open Access THE USE OF BLOOM’S TAXONOMY TO ASSESS STUDENTS’ PERFORMANCE EFFECTIVELY IN WRITTEN EXAMINATIONS(2017) Peiris, S; Peiris, C. N; Wickramasinghe, SBloom’s Taxonomy is widely used, to bring out thinking ability in students, as an assessment method. In this article we emphasize four types of methods generally used in evaluating the intended learning outcomes in written examinations. How questions should be structured in each level of cognitive domain is discussed with an example in multiple choice questions (MCQ), short answer question (SAQ), structured type questions (STQ) and essay type questions (ETQ). Common biological applications were used as example questions. The questions were developed to show how students’ thinking ability was brought out when questions were structured in line with the levels of cognitive domain in Bloom’s Taxonomy. In conclusion, this paper defines how the application of Bloom’s Taxonomy helps in developing complete answers which come out not from the students’ memory but from applying, analyzing, synthesizing and evaluating.Publication Open Access GUIDANCE FOR PERFORMING TEACHER SELF-EVALUATION IN ORDER TO ENHANCE THE QUALITY OF TEACHING AT HIGHER EDUCATION INSTITUTIONS IN THE ASIA-PACIFIC REGIONS(Asia-Pacific Quality Network, 2017) Jayakodyarachchi, D. K; Jayatilake, H. H; Malalage, B. A; Peiris, C. NAdaptation to globalization and diversification in Higher Education opens new horizons and leads to re-engineering of the existing higher education (both teaching and learning) in order to cope with the expanding scope and differences. Consequently, Higher Educational Institutes (HEIs) will need to adopt new theories and practices to dissolve the boundaries of quality in HE. The Internal Quality Assurance subdivitions of HEIs play an important role in these processes and will need to focus on and guide the ‗enhancement‘ of teaching and learning quality. This enhancement could be achieved by a variety of ways with the aim to develop quality in teachers. This is bound to result in the quality of the teaching process. When developing the quality in teachers‘, it is vitally important to have positive perceptions towards the changing needs. Thus, the Teacher Self Evaluation method (TSE) directly helps individuals improve their perceptions in the positive way and thereby achieve most of the characteristics of a quality teacher. Therefore the guidelines of good practices applicable to IQA units/evaluators for effective teacher evaluations/assessments ,the characteristics of a quality teacher, the enhancement of the teaching quality at HEIs in the AsiaPacific regions as well as the issues which disrupt the TSE have become vitally important for the teaching practice.Publication Open Access A gap analysis to measure service quality of university libraries through user perspectives: a case study at the University of Colombo(KDU Library, 2010) Somaratna, H. M. D. S. D; Peiris, C. N; Jayasundara, C. CUser expectations and perceptions are important measures of service quality in academic libraries and service quality is frequently defined in terms of reducing the gap between user expectations and the service provided. The assessment of service quality through user perspectives provides an important feedback for libraries. The aim of this research was to determine the gap between user desired service expectations and actual service perceptions of the University of Colombo Library System to provide a better service to satisfy their expectations. This study conducted as a user survey covered 614 users of the Colombo University Library system. A modified version of a SERVQUAL model was used to ascertain the views of library users about service level. They were asked to assess the actual service delivered by the library; to establish the importance of the service to them as users; and, to identify to what extent the service met their expectations. The largest service quality gap among all the attributes applied to the Colombo University Library System was “Access to electronic journals”. The author’s fervent hope is that this research would provide insights for further research in this field which in turn would eventually help decision makers to improve service quality in our academic libraries.Publication Open Access WEB BASED MONITORING AND EVALUATION SYSTEM FOR EXTERNAL QUALITY ASSESSMENTS IN UNIVERSITIES(INQAAHE Conference, 9-11 April, 2013-Chinese Taipei, 2013-04-09) Peiris, C. N; Wickramasinghe, S; Peiris, S; Meegama, R; Upeksha, G; Hettiarachchi, SExternal Quality Assessment (EQA) is the major component of QA framework in Sri Lanka. The main function of EQA is to review the standard and quality of the HEIs and its programmes of study and to provide the outcome to stakeholders to observe their expectations. Due to lack of organized mechanism to monitor and evaluate the outcome of the EQA conducted in universities the improvement in quality is not visible. Also the System users are in different geographical locations and therefore, no access to observe the outcome of EQA’s. A web based approach was developed, as a method to achieve the expected outcomes of EQA’s. The system provides user friendly, accurate and up-to date information of EQAs and also it provides a feedback mechanism through online forms/questionnaires. The easy access of information would provide the authorities a basis for decision making to improve higher education sector in Sri Lanka.Publication Open Access Effect of hot ethral-dip treatment for improving peel colour development and reducing stem-endrot of ‘Karuthacolomban’mango(Sri Lanka Department of Agriculture, 2004) Sarananda, K. H; Wijesinghe, W. A. J. P; Dulani, H. N; Peiris, C. NPoor colour development of the peel and high incidence of stem-end-rot development are the major reasons for excessive postharvest losses in mango, variety” Karuthacolomban ‘. Experiments were conducted to investigate the effect of artificial ripening by application of ethral at ambient (26ºC), 48º and 52ºC on reducing postharvest losses. Time taken for ripening was shortened when the treated temperature was increased. Peel colour development was improved when fruits were treated at 52 C. Total soluble solids and titratable acidity of induced fruits remained similar to those of control at table ripe stage. No difference observed in the sensory evaluation of ripe mango indicated that the taste, smell and flavour were not affected by the application of ethral. Fruits inoculated with Lasiodiplodia theobromae showed less severity of stem-endrot when those fruits were induced for ripening at 52 C with ethral. When inoculated fruits were allowed to ripen naturally a high disease severity was observed. Therefore, after harvesting, mature” Karuthacolomban ‘mangoes could be treated with hot ethral (1 ml/l H2O) at 52 C for 3 minutes to induce ripening resulting in an attractive peel colour and a low severity of stem-end-rot.Publication Open Access Breeding and selection of tomato F1 hybrids for yield and fruit quality characters(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 2005) Alwis, L. M. H. R; Perera, A. L. T; Fonseka, H; Peiris, C. NTomato (Lvcopersicon esculentum Miller) of the family Solanaceae is one of the most important vegetable crops grown in Sri Lanka. To understand the actual consumer requirements, especially in terms of fruit quality characters, an extensive survey was carried out. Results revealed that for home consumption, a majority preferred acidic, round to flatshaped, medium-sized fruits, red in colour for curries, salads and sandwiches. The Government of Sri Lanka has also identified the production of local vegetable hybrids as a matter of high priority. With this information, a half diallel genetic crossing design was carried out to produce 36 F, hybrids using nine local and foreign varieties at the Agricultural Biotechnology Centre, University of Peradeniya. These were evaluated in the Meewatura farm of the Faculty of Agriculture, University of Peradeniya. Yield and fruit quality characters including brix, acidity and fruit shape and colour were evaluated. General combining ability (GCA) and specific combining ability (SCA) were significant indicating the importance of both additive and dominance gene action. Out of the 36 Fi tomato genotypes; T068 was selected as the best hybrid for the tourist industry as it showed heterobeltiosis for yield (48%) and low acidity, while T025 was selected as the best hybrid for local consumption as it too showed heterobeltiosis for yield (76%) with high acidity. Both hybrids showed that yield potentials were much higher than the currently used varieties.Publication Open Access Development of new high yielding chilli hybrids (Capsicum annuum L.) based on heterobeltiosis and characterization of parental germplasm for DNA polymorphisms(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 2006) Millawithanachchi, M. C; Perera, A. L. T; Peiris, C. N; Fonseka, H. MTwenty-eight hybrids of chilli (Capsicum annuum L.) were produced through the half Diallel genetic design using improved chilli varieties, MI 1, MI 2, KA 2, Arunalu, MI Hot, IR, Thiwari and Hot Pepper. Hybrids and parents were evaluated for yield characteristics using a 7 x 7 lattice design under the field conditions of Meewathura farm, University of Peradeniya, from June to November 2004. Performance for total yield, total number of pods, average pod weight, plant height, plant width, pod length, and dry matter percentages were significantly different among tested genotypes. High heterobeltiosis was observed for total yield, while heterosis for total number of pods, average pod weight, and dry matter percentage was low. H 42 was the best performing hybrid with 113.24% heterobeltiosis for total yield having early flowering characteristics. PCR, based on RAPD primers OPM 05 and OPM 11 gave polymorphic …Publication Open Access Need for quality assurance and accreditation in Sri Lankan Universities(Quality Assurance & Accreditation Council of the University Grants Commission, Sri Lanka, 2007-01) Peiris, C. NThis paper presents a brief description of the Quality Assurance framework introduced into the Sri Lankan higher education system recently. At present, the Sri Lankan Quality Assurance framework composed of four main components, namely Codes of Practice, Subject Benchmarking, Credit and Qualification Framework and External Quality Assessments. The paper discusses some of the lessons learnt and experience gained at the initial phase of the External Quality Assessment Process. Finally, it provides some suggestions for the future development of the Quality Assurance programme in Sri Lanka.