RESCON 2023

Permanent URI for this collectionhttps://ir.lib.pdn.ac.lk/handle/20.500.14444/5953

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Anaplasmosis in dogs: a review on South and Southeast Asian Countries
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Perera, V.N.; Rajakaruna, R.S.; Dangolla, A.
Anaplasmosis affects dogs worldwide, varying from asymptomatic infection to a severe illness. Despite the high prevalence and socioeconomic impact, canine anaplasmosis is often neglected. This review provides insights into existing information and identifies knowledge gaps and future directions for research. All studies published on anaplasmosis in dogs from 2011 to 2023 in South and Southeast Asian countries were identified by searching scientific databases PubMed, Springer, Elsevier, Google Scholar, and Web of Science with ‘anaplasmosis in dogs’, ‘seroprevalence of anaplasmosis in dogs’, canine vector-borne diseases, ‘canine vector-borne diseases’ with country names. Forty-five articles were reviewed. Anaplasmosis in dogs was reported in all countries in these regions except Afghanistan, Bhutan, Brunei, Cambodia, and Timor-Leste. Twenty-six and nineteen articles were retrieved from Southeast Asian and South Asian regions, respectively. Thirty-six studies were based on dogs, three on the tick vector collected from dogs, and six on both dogs and ticks. Most (73%) of the articles were published between 2017 and 2023. Anaplasma platys was the predominantly identified Anaplasma species infecting dogs, and the brown dog tick, Rhipicephalus sanguineus, as the vector of A. platys, the most common dog tick species. Only three studies have been conducted in Sri Lanka on the prevalence, clinical, and laboratory findings of anaplasmosis in pets, stray, and working dogs reporting A. platys infections. The prevalence of anaplasmosis varied widely from 39% in Malaysia to 0.25% in Myanmar. Most studies (80%) were based on molecular identification and prevalence estimation, including PCR (62%) of the studies, ELISA in 8.8%, microscopy in 15.5%, and 13.3% combination of the above tests. The available studies provide only basic research instruments; many significant knowledge gaps on the pathogen and tick transmission were identified. A better understanding of these will improve immunological mediations, aiding the design and production of effective vaccines and alternative pharmacological interventions against the pathogen.
Evaluation of traditional and skill-oriented teaching and assessment in enhancing generic skills of students in chemistry components in grade seven science: a case study in Central Province, Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Balasritharan, K.; Jayasundera, A. C. A.; Chandrasena, W. D.
Formative and summative assessments are used to evaluate students’ learning process to fulfil intended learning outcomes. This research examines the effectiveness of traditional teaching and assessment versus skills-oriented instruction and assessment in enhancing generic skills in learning Chemistry in Grade Seven class in the Central Province of Sri Lanka. This is an experimental study employing a mixed methods approach. Two subunits from the Grade Seven science curriculum were selected for instruction. Nine Schools were selected from the central province with a sample size of 636 students by convenience sampling. Two parallel classes of Grade Seven in each school were selected. A Pre-test was administered to both classes to ensure comparability of the groups. One class was considered a control group, and the other class was an experimental group. In the 2nd sub-unit, these groups were interchanged. The first lesson was conducted using the traditional method for the control group and using skill-oriented instructional and assessment methods for the experimental group. The parallel classes were switched over in the second lesson, employing the same teachers. After the teaching-learning process, post-tests were administered to both groups for both lessons. While conducting both traditional and skill-oriented learning, generic skills were observed by the researcher with the help of three other teachers with scoring rubrics. The difference between the mean scores of pre-tests, post-tests and generic skill tests were compared. According to the results, skilloriented groups showed significantly higher performance than the traditional group. Furthermore, the observational data analysis demonstrated that the students of the skill-oriented instructional group demonstrated better orientation to real-life situations. Findings from focus group discussions with students and teachers reveal that skill-oriented instruction and assessments cultivate much higher generic skills than traditional instructions and assessments. According to the above, the current teaching-learning process has to be re-evaluated to enhance students’ meaningful learning in the chemistry component of Grade Seven science.
The effectiveness of online teaching and learning compared to in-person instructions on science for junior secondary students: a case study at a chosen school in the Kurunegala Education Zone
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Shifana,M.H.; Ganehenege,M.Y.U.
Schools and Universities in Sri Lanka have been closed intermittently during the past three years due to COVID-19 and fuel shortages. During this period, in-person teaching became impossible, and online teaching was developed. Schools have been reopened for in-person teaching and learning at present. In contrast, other countries adopted both methods, online and in-person. Declining test scores among junior secondary students in some education zones during online learning were noticed. This study aimed to assess and compare the effectiveness of online and in-person teaching and learning science among junior secondary students in a selected school within the Kurunegala education zone. The objectives of the study were to conduct both online and in-person science lessons for two groups separately and to compare grade eight students' performance in both settings; Compare teacher-student interaction, learning resources, peer group interaction, and motivation in both sittings; and make suggestions for effective teaching and learning process. Two equally weighted courses were used to teach the two groups. A convenience sample of 72 Grade 8 students was used in the data collection with mixed methods approach. Pre-tests, post-tests, and questionnaires were used in the quantitative data collection. Qualitative data were collected via interviews with ten randomly selected students. The findings indicated that the in-person group achieved slightly higher performance scores in Unit 4 (Properties of Matter) than the online group. Both groups demonstrated similar performance levels in Unit 8 (Changes in Matter). However, in-person teaching exhibited significantly higher scores (p < 0.05) than the online group for factors such as teacher-student interaction, peer group interaction, learning resources, and motivation. Students achieved high results in both settings but needed more resources, reliable internet, and adequate technology skills for online teaching and learning. The study suggests adapting effective instructional methods, technology usage, resource availability, training, participation, peer interactions, and monitoring well-being for effective online science teaching.
Impact of social isolation on mental health, social interactions, and academic performance among adolescents during covid-19 pandemic
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Dissanayake,K.M.K.S.; De Silva,W.A.P.P.; Rajakaruna, R.S.
The effect of COVID-19 took a toll on the efficiency of delivering education due to the change from traditional classrooms to online learning. While the shift to online education was relatively successful, the efficiency of its deliverance was questionable, especially in developing countries like Sri Lanka. This study aims to assess the effect of social isolation during the pandemic on student mental health, social interactions and academic performance. For the study, students following secondary education from 2020-2021, during the peak of the COVID pandemic, were considered. The survey conducted received 1,500 responses representing students of 21 districts with multiple economic backgrounds. To visualise the influence of virtual education, academic performance was measured via examination results from the years 2018 to 2021 (considering 2018 and 2019 as pre-virtual education and 2020 and 2021 as post-virtual education). Survey results indicate that mental health played a crucial role in distinguishing the productivity of respondents, with a majority (72%) showing severe stress and panic with the start of online learning. Forty seven percent of students were not satisfied with the communication during social isolation due to a lack of social interactions caused by the increased use of virtual platforms to conduct academics. Factors such as change in environment, motivation, guidance, and communication had similar contributions (F= 28.31; p= 0.001) to an overall decrease in performance (46%). The combined effect of mental and social factors affected all students irrespective of socio-economic status. Time management was a key issue with online learning. Thirty seven percent of the study population stated that technology became a barrier to their productivity, while 25% disagreed. Results indicate the absence of a significant impact on the overall results of O/L and A/L. Higher pass rates among males and females in almost all considered districts for both O/L and A/L exams (paired t-test for A/L- p = 0.007; O/L- p = 0.006) were seen after the virtualisation of classrooms. This study provides crucial insight into exactly which factors have the most significant effect on student performance in terms of virtual education and whether that effect is significant.
The effect of intrinsic motivation on science aspirations in grade eleven students in Dehiowita Education Zone
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11) Narangoda,N.W.L.; Chandrasena,W.D.
Students’ aspirations are strongly associated with their intrinsic motivation. Thus, this quantitative study was conducted to identify the effect of intrinsic motivation on science aspirations in Grade Eleven students in two 1AB schools and two 1C schools in the Dehiowita education zone to compute the relationships of the above two psychological factors of students. The convenience sampling technique was used to select 435 students from Grade Eleven who sat for G.C.E. (O/L) in 2023. A Likert-type multidimensional questionnaire was administered to measure students’ aspirations and intrinsic motivation. Descriptive and regression analyses were conducted according to the G.C.E. (Advanced level) subject stream and across gender. Results showed a high positive relationship between intrinsic motivation and aspirations of the science stream (R2 =.953 (186), t=61.165, p=.000). Moreover, there was a low positive relationship of the above aspect in subjects other than science (R2 =.519 (247), t=16.301, p=.000). The results demonstrated a high positive relationship of female students when compared to the male students (Female; R2 =.910 (183), t=42.943, p=.000 and Male; R2 =.920 (250), t=53.496, p=.000). Thus, the effect of intrinsic motivation on aspirations in science is more substantial than other subjects. As such, student intrinsic motivation is to be enhanced to empower students’ aspirations.
Enhancement of student achievement in science of a 1ab school in Dehiowita Education Zone: an action research
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Narangoda, N.W.L.; Chandrasena,W.D.
Intrinsic motivation is a fundamental element of student learning, and teachers could assist in increasing and developing intrinsic motivation for optimal achievement in the classroom. As there were students with deficient levels of achievement in science, this action research was conducted to enhance their achievement in science in Grades 7, 8 and 9 through interventions. A purposive sampling technique was used. Participants comprised 16 students in each Grade, totalling 48 students. A multidimensional questionnaire was used to measure intrinsic motivation, along with pre-test papers, post-test papers, and continuous assessment test papers to measure achievement before and after the intervention. Students were identified with low achievement in science as the first phase of the intervention. Positive reinforcement, positive feedback, verbal rewards and other strategies were used to enhance intrinsic motivation in the second phase. Furthermore, activity-based learning methods were applied in the third phase. Focus group interviews were conducted for qualitative data. Post-test papers and other measurement tools were used to measure their progress in the fourth phase of the intervention. The mean statistics of the pre-test and intrinsic motivation of students were 26.63 and 1.33 prior to the intervention, respectively. The mean statistics of the post-test and intrinsic motivation were 35.73 and 4.26 after the intervention, respectively. Results showed a significant difference in intrinsic motivation and achievement of students prior to the intervention and after the intervention (p=25.67 (47), t=.000 and p=8.93 (47), t=.000). Three themes were derived from the thematic analysis, including enhancement of intrinsic motivation through attractive teaching-learning methods; teacher’s verbal rewards for intrinsic motivation; and enhancement of students’ achievement through a student-centred approach. Thus, the intervention process improved the intrinsic motivation and achievement of the students who demonstrated low achievement in science in Grades 7, 8, and 9. Thus, Student-centered teaching-learning methods and teaching strategies to enhance students’ intrinsic motivation are highly effective in teaching science to meet 21st-century educational goals.
Improving school attendance of a grade eight student empowering competence, autonomy support and relatedness through science activities: an action research
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Narangoda, N.W.L.; Chandrasena,W.D.
Teachers’ support of students’ basic psychological needs for autonomy, competence and relatedness facilitates students’ autonomous self-regulation for learning, empowering academic performance and well-being. Teachers can nurture these needs by autonomy-supportive behaviours. Thus, it creates more opportunities for students to work on their own. Autonomy- supportive teachers promote the relevance of schoolwork, provide more opportunities for choice, ask more questions about what students want to do, and praise signs of improvement. As there was a Grade eight student with meagre attendance, this action research was conducted to improve the attendance of a student who was absent from school regularly (only once in two weeks) by enhancing three innate needs of intrinsic motivation: Competence, Autonomy support, and Relatedness (CAR). This was accomplished through various science activities in a 1AB school in the Dehiowita education zone. Discussions were held with the student, the teacher of Grade Eight, the sectional head, and the child’s mother to explore the reasons for poor attendance, interests of the child, learning style, and level of achievement as the first phase of the intervention process. Existing CAR was estimated using a multidimensional questionnaire as pre-intervention. Different activities in science with the supportiveness of CAR were conducted with the students with the support of the school community as lab-based activities, innovations with the support of technology teachers, scientific drawings with other science teachers, and equipment handling with lab assistants as the steps of interventions. The same multidimensional questionnaire was administered to measure student CAR after the intervention. The mean statistics of CAR were 1.5, 1.85, and 1.43, respectively, prior to the intervention, and related mean statistics of CAR were 3.35, 3.54, and 3.26 after the intervention. Thus, student’s interest in engagement in science has been improved while increasing student’s school attendance with the enhancement of science performance. As such, this study concludes that the empowerment of CAR is highly effective in the enhancement of student school attendance and performance while developing student’s intrinsic motivation.
The impact of school resources on the performance of students’ G.C.E. O/L (Ordinary Level) mathematics results
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Meera, S.; Udagedera,I.G.K.
The reports of the Central Bank of Ceylon and other sources emphasise the substantial amount of financial and human resources spent on the Sri Lankan free education system. It is crucial to find out whether this expenditure is worthwhile and effective. This study aimed to identify the impact of school educational resources on students’ G.C.E. (O/L) mathematics performance. The data was collected from 27 principals and 52 mathematics teachers from 27 selected schools in the Vadamaradchy Education Zone. Schools were selected using the cluster sampling method. Information regarding school resources and their efficient use was collected from principals and teachers through structured questionnaires. The G.C.E. (O/L) mathematics results in the last five years were used to evaluate students’ performance. The statistical analysis was conducted using the Statistical Package for Social Science (SPSS) 17.0, employing Spearman’s correlation coefficient to determine the correlation between variables. This study revealed that 1 AB schools had the highest average pass percentage in mathematics (85.55%) than 1 C schools (70.32%) and Type II schools (47.36%). The classroom size and teacherstudent ratios did not have a significant impact on the pass percentage. More than 75% of scholarship-holding students got admission to 1AB schools, and this had an impact on the pass percentage. Considering the relationship between educational resources and mathematics performance as a whole, there was a significant and large correlation (r=0.514, p=0.000) between the availability of school buildings and classrooms and students’ mathematics performance. A positive, moderate, but significant correlation (r=0.489, p=0.000) between the availability of instructional space and mathematics performance was observed. Availability of instruction materials also showed a positive moderate correlation (r=0.481, p=0.000) with G.C.E. (O/L) mathematics performance. The factors of developing their own lessons by the teachers, frequency of using computer software or applications for teaching, and frequency of using library resources demonstrated negative correlations with students’ mathematics performance. Based on the results, it can be concluded that several school resource factors significantly impact G.C.E. (O/L) mathematics performance, although the magnitude of these impacts is not substantial. Thus, it remains uncertain that educational resources have a significant impact on students’ G.C.E. (O/L) mathematics achievement. This conclusion suggests that while school resources play a role in shaping student performance in mathematics, they are only part of the equation, and other factors may also contribute to overall outcomes. This study encourages further research to delve deeper into the specific aspects of school resources that have a significant impact and explore strategies to optimise their effectiveness.
Effectiveness of integrating STEM education into science teaching and learning process
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Alahakoon,M.G.K.; Yatigammana,T.M.S.S.K.
Vital elements of STEM education are the integration of Science, Technology, Engineering and Mathematics into the curriculum with a commitment to hands-on learning. Science national cognitive achievement tests were conducted for Grade 8 students in 2005 and 2008, and the lowest mean score was achieved in sub-skill synthesis due to weakness in the application of concepts to real life. Therefore, high scientific literacy can be achieved through STEMintegrated teaching-learning activities. This study aimed to investigate the effectiveness of STEM integration into the science teaching-learning process of Grade 8 students of three selected 1C schools (named A, B and C) in Wattegama Educational Zone. The study employed mixed methods to triangulate information. The soil erosion subunit (15.3) was selected under Natural Disasters (unit 15) of the Grade 8 science textbook. The purposive sampling process was utilised to select 136 Grade 8 students for the study. Quantitative data were collected from pre-test and post-test. Qualitative data were collected using activity sheets, teacher interviews and observations. The quantitative data were analysed using SPSS, and qualitative data were analysed using Thematic Analysis. It was identified that STEM-integrated teaching-learning activities enhanced the performance of students in schools B (p< 0.05) and C (p< 0.05). However, there was no significant difference in performance of the school A (p >0.05). The reason for not increasing student performance in school A may be due to crowded classrooms. An independent sample t-test showed that post-test marks of experimental and control groups of school A (p> 0.05) and C (p> 0.05) were not significantly different. However, post-test marks of the control and experimental group of school B were significantly different (p< 0.05). The highest performance of students was shown in school B, and student performance was not at a significant level in schools A and C. It may be due to various reasons, such as crowded classrooms and differences in teaching qualities in STEM-integrated teaching. It was also revealed that there was no considerable difference in the science performance of students who were taught with STEM integration in schools A, B and C (p >0.05). This may be due to similar social and cultural settings in school sub-systems. Furthermore, it was revealed that the highest performing were male students (School B mean = 98.77), the second highest was female students (School C mean= 97.94), and the lowest was School A (mean male =95.71 & mean female = 91.80). The low student number and male students in the classroom is the most influential factor for the highest students’ performance in school B, sequentially followed by school C and A. additionaly, the important aspects of STEM-integrated teaching-learning activities were revealed, which are helpful for students and teachers to develop personal qualities in authentic learning for solving real-life problems
Implementing inquiry-based learning approach to improve synthesis skills among science undergraduates
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Wijesinghe,K.J.
Analysis, evaluation, and synthesis are higher-order cognitive processes which require the active participation of students and inquiry-based learning (IBL) activities are an efficient means to improve them. IBL involves exposing the students to an issue or a concept, and the students are encouraged to ask questions and generate hypotheses or predictions. This process is followed by experimentation to collect data and analysis of data to draw conclusions. The learning process involves analysis, critiquing, designs, and reflections. An IBL activity was implemented on a group of 19 fourth-year undergraduates enrolled in the Membrane Biology course and were following the BSc Honours degree in Biochemistry and Molecular Biology at the University of Colombo. For the IBL activity, students were provided with several research articles relevant to the taught material. They were requested to conduct a poster presentation on an experiment in the research article, assuming they were one of the authors in the article, providing context to what is already known, gap-in-the-knowledge, hypotheses, experimental method, results, conclusion/s and future direction/s for the study encouraging them to synthesise their own hypotheses and experimental designs. To ensure that students are not developing misconceptions during their inquiry, they were requested to submit a short manuscript on what they are proposing. Following the feedback from the instructor, students conducted their poster presentations, which were evaluated based on predetermined evaluation criteria. A cross-sectional survey involving the students who participated in the IBL activity recorded their positive learning experience, with all agreeing that the assignment helped them to learn how to analyse data presented in a journal article critically. In the study sample, 19% of students strongly agreed, and 76.2% of students agreed that they were able to synthesise their own hypotheses and experimental designs. All students agreed that the assignment led to an increase in their scientific creativity. In conclusion, the implemented IBL activity was highly constructive in developing students’ higher-order cognitive skills. Considering the intellectual effort that needs to be invested in an IBL activity, the entire course can be benchmarked by incorporating another IBL-based assignment, such as developing a research proposal forgoing the necessity of an end-semester examination.
Cost-effective CIGS thin films: electrodeposition and characterization for efficient solar cells
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11) Londhe,P.U.; Rane, S.; Chaure,N.; Kale,B.
The present work explores the electrodeposition of copper indium gallium diselenide (CIGS) thin films using a non-aqueous electrolyte at a higher working temperature of 130 °C. The cyclic voltammetry (CV) experiment revealed a broad potential window beyond -0.8 V relative to the Ag/AgCl reference electrode, suitable for CIGS deposition. X-ray diffraction (XRD) analysis confirmed the formation of a tetragonal chalcopyrite structure in the annealed layers, while secondary phases, such as CuSe and In₃Se₄, were observed in as-prepared films deposited at higher potentials. Upon annealing, all layers became highly crystalline, with the removal of secondary phases depicting the formation of the tetragonal structure of CIGS. The annealing process enhanced the crystallinity and confirmed the presence of the A1 mode of the tetragonal structure in CIGSe films. The uniform and compact morphology seen in films deposited at higher potentials suggests their potential for solar cell applications. Furthermore, the annealing process enhanced the crystallinity and supports the formation of nearly stoichiometric CIGS films. These findings contribute to the advancement of cost-effective and efficient thin-film solar cell technology, offering a promising avenue for sustainable and renewable energy solutions
Performance enhancement in ultrathin CIGS solar cells using plasmonic nanoparticles – a finite difference time domain analysis approach
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Desarada,S.V.; Chaure,N.B.
The plasmonic effect in photovoltaics is gaining attention because of its optical absorption enhancement properties in solar cells. Plasmonic structures exhibit wavelength-selective photon scattering based on their shape, size, and the surrounding dielectric medium. Plasmonic enhancement is achieved through the collective oscillations of the free-electron cloud in metallic materials when the size is smaller than the wavelength of the incident radiation. This study explores the application of plasmonic gold (Au) nanoparticles (NPs) in CuInGaSe2 (CIGS) solar cells using the finite-difference time-domain (FDTD) analysis method for simulation. The study was carried out using ANSYS LUMERICAL to simulate optoelectronic properties, solving Poisson's and continuity equations coupled with Maxwell's equations. Au (NPs) exhibit different resonance frequencies in semiconductor materials, making them suitable for selective wavelength-absorption enhancement. The results demonstrate that the unabsorbed light in the base CIGS was effectively captured in the devices with embedded Au NPs. In particular, when 20 nm diameter spherical Au particles were incorporated into CIGS solar cells, they achieve a higher efficiency increase of 4% compared to CIGS solar cells without plasmonic nanoparticles. This study highlights the effective utilization of plasmonic nanoparticles for efficient light absorption, which enables thickness reduction of high-efficiency thin-film solar cells.
Synthesis of cerium oxide nanoparticles by hydrothermal method and investigation of their antibacterial activities
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Gajbhiye, S.S.; Ghadage,V.H.; Salve, M.V.; Khater,M.S.; Gaikwad, M.D.; Rasage,A.R.; Chaure,N.B.
Metal oxide nanoparticles have been suggested as promising candidates for the development of antibacterial agents. Among metal oxides, cerium oxide (CeO₂) nanoparticles have been utilised in different applications due to their physical, chemical and redox properties. Cerium nitrate hexahydrate and sodium hydroxide were used as a precursor and reducing agent for the synthesis of CeO₂ using the hydrothermal method. The synthesised samples were characterised using various techniques to understand their structural, optical and antibacterial properties. From XRD analysis, the average crystallite size ̴25 nm was determined from the DebyeScherrer relation. Raman peak was observed (F₂g) at 464 cm−1 , attributed to the symmetric stretch of the Ce–O vibration. The optical energy band gap of the CeO₂ nanoparticles was estimated to be ̴ 3.3 eV by the UV- V reflectance spectrum. The FTIR spectrum of the prepared CeO₂ nanoparticles identified the chemical bonds as well as functional groups in the sample. Also, the signature bands due to the stretching frequency of Ce–O can be seen in between 400 to 500 cm−1 , indicating the formation of CeO₂nanoparticles. The antibacterial activity was studied by disc diffusion assay against common pathogens (Escherichia coli and Staphylococcus aureus), and a strong antibacterial effect against Gram-positive pathogen S. aureus was observed.
Hydrothermal synthesis of HgTe thin films for possible applications in thin film CdTe solar cells
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Ukarande, A.S.; Chaure, S.N.; Chaure, N.B.
HgTe is a compound semiconductor of the II-VI group with the narrowest direct band gap ranging from 0.2 to 1.2 eV. The material has uses in photodetectors and thin-film solar cells. A simple method for synthesizing pure HgTe powder samples using hydrothermal processes is presented in the current study. In double distilled water (DDW), mercury nitrate and tellurium oxide were used as precursors, along with NaBH4 as the reducing reagent. The chemicals were mixed at ambient temperature before being placed in an autoclave at 200 °C for 72 hours. Precipitate was dried at 80 ℃ in a vacuum oven for 12 hours. The obtained solution was washed three times by centrifugation with DDW and ethanol. The optical, structural, and morphological properties of the synthesized powder samples were studied using an X-ray diffractometer, Raman microscopy, scanning electron microscope, and energy dispersive spectroscopy. A highly crystalline pure cubic crystal phase was revealed by XRD analysis. The TO and LO modes observed in Raman spectra at 116 and 137 cm-1 confirmed the formation of HgTe. SEM images showed that the formed agglomerated particle nanoparticles are spherical, uniform, and dense. The elemental composition determined using EDS was found to be 1:1 in stoichiometry. The synthesized material could be utilized to deposit thin films to examine their applications in solar cells and IR detectors.
CeO2/MnO2 Composite material for asymmetric supercapacitor applications
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Bhosale, S.; Gajbhiye, S.; Khandare,L.; Ghadage,V.; Chaure,N.
Supercapacitors have attracted significant attention to play prominent roles in resolving the energy crisis, global warming, and environmental pollution. MnO₂ is the most abundant material on earth, with high theoretical capacitance. It has multiple oxidation states that contribute to redox reactions. CeO₂ is a good redox stability, which can help to improve the conductivity of MnO₂. CeO₂ helps to improve the cyclic stability of the composite material. In the present study, the composite material consisting of CeO₂ nanoparticles decorated with MnO2 nanowires was synthesized using the low-cost, wet chemical hydrothermal technique. The synthesized materials were characterized and analyzed by Raman spectroscopy, XRD, SEM, and XPS. XRD pattern and Raman spectroscopy analysis of CeO₂ nanoparticles decorated MnO₂ nanowires revealed the presence of tetragonal α- MnO₂ phase. The electrochemical supercapacitor performance of pristine MnO₂, CeO₂, and CeO₂ nanoparticles decorated MnO₂ nanowires are analyzed by cyclic voltammetry, galvanostatic charge- discharge, and electrochemical impedance spectroscopy. The specific capacitance of the composite material was approximately 145.19 F/g. The combination of these two materials in a composite can lead to synergistic effects, resulting in improved electrochemical performance, and it can be an outstanding active electrode material for supercapacitor applications.
Layered marigold-flower-like CdS/MoS2-reduced graphene oxide nanocomposite as an efficient electrode material for supercapacitor
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Khandare, L.N.; Late,D.J.; Chaure,N.B.
Technological advances have become a fundamental part of everyday life, and the demand for energy-storing devices has grown exponentially. Therefore, the development of energy storage devices is needed to fulfil global energy demands. Consequently, materials and devices for energy storage have long-term clean and renewable energy sources, which are widely accessible owing to their cost-effective and environmentally friendly nature. Transition metal chalcogenides are useful as active electrode materials for enhancing the capacity for energy storage. Considering the requirement of a large surface for energy storage, we have synthesized Marigold flower-like CdS/MoS₂ nanoflowers on rGO nanosheets by simple hydrothermal synthesis. The CdS/MoS₂-rGO nanocomposite symmetric supercapacitor device exhibited increased capacitance of 102 F g⁻¹ at a current density of 0.1 A g⁻¹, and 83.4% of the capacitance was retained up to 16 × 10⁻³ cycles at the current density of 5 A g⁻¹. The resulting CdS/MoS₂- rGO nanocomposite can deliver excellent electrochemical performance. Supercapacitors under study demonstrated high energy storage capabilities, resulting in an efficient device for electrochemical energy storage.
Synthesis of activated carbon and titanium dioxide-based composite from coconut shell for optimized and cost-effective supercapacitors
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Bandara,L.M.D.K.; Alahakoon, A.M.B.S.; Bandara,T.M.W.J.
The energy landscape today grapples with two significant challenges - the unsustainability of fossil fuel energy and the mounting costs of energy storage materials. In response, researchers are pioneering the use of economically viable, environmentally benign materials for energy storage applications, with a marked rise in interest in activated carbon, particularly supercapacitor electrodes. In general, the synthesis and raw material cost of activated carbon derived from coconut shell charcoal is lower. The present study aims to prepare cost-effective supercapacitor electrodes by omitting problematic organic binders. This research elegantly employs locally sourced coconut shells, a widely available resource with high carbon content, as an optimized base material for 90 wt.% activated carbon (AC) and 10 wt.% titanium dioxide (AC-TiO₂) composite fabrication. The locally sourced coconut shells underwent a series of transformations, heating, grinding, and a chemical activation involving KOH as an activation catalyst and heating process. The surface morphology was examined through the utilization of scanning electron microscopy (SEM) images. The activated carbon was then coated on a fluorine-doped tin oxide coated (FTO) glass slide using an aqueous and slurry, and its performance was evaluated through cyclic voltammetry (CV) tests over a range of scan rates 2, 5, 10, 20, 50 and 100 mV s⁻¹, and within a potential window between 0.0 and 0.8 V. The highest discharge capacitance value recorded at these scanning rates was 168.0 F g⁻¹ at 2 mV s⁻¹, demonstrating robust capacitive behaviour. Notably, the study achieved an impressive peak specific capacitance of 168.0 F g-1, an energy density of 13.29 W h kg⁻¹, and a power density of 255.85 W kg⁻¹ at the current density of 1 mA cm⁻². The (AC-TiO₂) electrodes synthesized in this study outperformed those documented in prior research, exhibiting the highest specific capacitance. The supercapacitors demonstrated exceptional endurance and rate capability, maintaining approximately 95% of their initial capacitance even after a rigorous cycle of 1000 charges and discharges. As confirmed by cyclic voltammetry, this performance underscores their excellent cycling stability. Nyquist plot of the supercapacitor exhibited represented a semicircle with a diameter of about 11 and a low-frequency spike. Therefore, this work makes a meaningful contribution toward advancing sustainable and cost-effective energy storage solutions.
Thickness effect on the physicochemical properties of electrodeposited ZnTe layers
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Olusola, O.I.; Adesiji, N.E.; Olusola, O.O.; Faremi, A.A.; Oluyamo, S.S.; Bandara,T.M.W.J.; Chaure, N.B.; Furlani,M.; Mellander, B.E.; Dissanayake,M.A.K.L.; Albinsson,I.
In this paper, we report the effect of different deposition durations on the physicochemical properties of electrodeposited ZnTe thin films. Varying thicknesses of the films were obtained at deposition durations of 0.25, 0.50, and 1.00 hours. ZnTe thin films were prepared from an aqueous electrolyte comprising 0.1 M ZnSO₄.7H₂O as the Zn ion source and 10 ml of dissolved TeO₂ solution as the Te ion source. The physicochemical properties of the electroplated materials were investigated using selected analytical techniques relevant to this study. Properties such as optical, structural, compositional, morphological, and electrical were studied using UV–visible spectrophotometer, X-ray diffractometer, energy dispersive X-ray spectrometer, scanning electron microscope, and current-voltage (I – V) / capacitance-voltage (C – V) analyser respectively. The optical results revealed that the energy band gap of the thin films decreases as the deposition duration increases. The grain sizes and the crystallinity improved with increasing duration. The EDX analysis showed that the Te concentration decreases with increasing deposition duration while the Zn concentration moderately increases. The resistivity of the investigated thin films were within the range of accepted resistivity values for semiconductors, and they were found to be moderately doped based on the result from the C – V measurements. The study revealed that the variation in the deposition duration significantly influences the thin films’ physicochemical properties. From the results, it can be concluded that the explored materials have the potential for optoelectronic applications.
Nanococrystallization of urea:4-hydroxybenzoic acid using sonochemical methods
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Walpala, M.D.M.; Adassooriya, N.M.
With the increase in global population, agriculture plays a vital role bounding to consume larger quantities of slow-release fertilizers. Urea is a widely used fertilizer with higher water solubility; crystal engineering has recently gained interest towards the cocrystallization of urea to overcome the premature decomposition of urea. The study focuses on the cocrystallization and nanococrystallization of urea:4-Hydroxybenzoic acid (4-HBA) and their characterization using powder X-ray diffraction (PXRD), fourier transform Iifrared (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) and optimize the sonication process to improve the quality of nanococrystals. Urea:4-HBA 1:2 cocrystal was synthesized using the liquid -assisted grinding method with acetonitrile and reduced the particle size using the sonochemical method (optimum frequency: 35-40 kHz, Time: 30 minutes) with the employment of hexane, stearic acid, and sodium dodecyl to obtain nanococrystals. The 1:2 ratio was confirmed in the crystallinity data in the Cambridge Structure Database. Successful cocrystallization and nanococrystallization were confirmed by PXRD and FT-IR analysis. PXRD patterns revealed the presence of a new crystalline phase, which is different from the starting compounds. The presence of new peaks in FT-IR spectra validated the formation of new bonding interactions in the cocrystal. SEM micrographs revealed the presence of irregular particles less than 500 nm, despite the presence of agglomerates. Nanococrystals with surfactants demonstrated a smooth surface compared with those without surfactants. TGA highlighted that cocrystal and nanococrystal had improved thermal stability than the parent material (around 150-160 °C). This study represents valuable insights into forming cocrystals and nanococrystals using urea, emphasizing the importance of selecting surfactants sonication parameters for synthesizing urea nanococrystals. Further research with high frequency sonication would improve the properties of nanococrystals, and the effectiveness of the urea nanococrystal could be identified using a soil release study.
Adsorptive removal of amoxicillin using montmorillonite barium titanate nanocomposite in an aqueous medium
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2023-11-03) Bandara, R.M.R.T.; Adassooriya, N.M.
Amoxicillin, one of the most widely used antibiotics in Sri Lanka, significantly contributes to antibiotic resistance upon discharge into natural water bodies. This emerging concern over antibiotic resistance is expected to impose substantial financial burdens globally in the foreseeable future. Among various methods, adsorption has gained significant attention for antibiotic removal. Among the leading materials for wastewater adsorption, montmorillonite (MMT) emerges as one of the most widely used adsorbents due to its high surface richness and nanolayered structure. In this study, barium titanate (BT), a ferroelectric substance with a polar surface having positive and negative charges, was selected as a potential material for synthesizing nanocomposite with MMT for amoxicillin removal. Four nanocomposites were synthesized by doping MMT with varying percentages of BT (2,4,6 and 8%). The nanocomposites were characterized using fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) techniques. In addition isothermal studies were conducted. SEM images confirmed the presence of BT nanoparticles layered on the surface of the MMT. The adsorption experiments conducted with 25 ppm amoxicillin samples revealed that the synthesized nanocomposite exhibited enhanced amoxicillin adsorption as the dosage of BT increased from 2% to 8%. The pH study indicated a positive correlation between the adsorbance and pH value, with the average pH value of 7.55 in the hospital effluent falling within a favourable range for adsorption. The isothermal study results were inconclusive due to the presence of nanoparticles in the final test sample for absorbance, which affected the absorbance readings and the overlapping absorbance peak of MMT with that of amoxicillin. Despite these challenges, overall findings suggest that the nanocomposite holds great potential as an effective adsorbent for removing amoxicillin from hospital effluent water. Overcoming the challenges encountered during the isothermal study and optimizing nanocomposite holds promise for the efficient removal of amoxicillin.

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