http://repository.rjt.ac.lk/handle/123456789/3391 2026-04-12T01:00:09Z http://repository.rjt.ac.lk/handle/123456789/3576 Interaction between Graphite Oxide and Sand Granules: The Effect of Temperature Bandara, P. M. C. J.; Kumarasinghe, A. R.; Balasooriya, N. W. B.; Bandara, A.; Weerasooriya, R. Graphite oxide (GO) coated sand composites were used to remove contaminants in water. We used GO coating on the sand by heat treatment without adding a binder. GO was synthesized by improved Hummer’s method. The GO was then coated on acid-purified sand as a function of system temperature for 2 hr (i.e., 50, 90, 110, 130, 150, 180, 250, and 300 0C). Repeated coating of graphite oxide onto sand granules at different temperatures resulted in a composite with enhanced stability in water. Raman, FTIR, XRD, and SEM analyses were used to characterize the composites and other precursors used. The characteristic D and G bands of GO are observed at 1350 cm-1 and 1595 cm-1, respectively, in GO and GO sand composites. With the heating of the reaction system, the G band position redshifts and reaches an optimal at 120 0C. The redshifts indicate the reduced number of GO layers on the sand. However, the higher stability of GO on the sand was maximized at 110 0C and the lowest 𝐼𝐷𝐼𝐺 ratio was observed at 180 0C. The Raman spectra confirmed that GO is present on the sand surface. Turbidity data confirmed the stability of GO sand composites. The exact reasoning for these observations is not fully resolved yet. 2021-12-01T00:00:00Z http://repository.rjt.ac.lk/handle/123456789/3574 Gamma-Aminobutyric Acid (GABA)-induced Growth Performance in Zebrafish Larvae via GABAA and GABAB Receptors Athapaththu, A. M. G. K.; Jayasooriya, R. G. P. T.; Choi, Y. H.; Kim, G. Y. Insulin-like growth factor-1 (IGF-1) primarily increases the release of gamma-aminobutyric acid (GABA) in neurons vice versa and is also responsible for the promotion of longitudinal growth in children and adolescents. Hence, we, in this study, investigated whether exogenous GABA supplementation activates IGF-mediated growth performance. Treatment with GABA in zebrafish larvae at 3 days post fertilization (dpf) significantly increased total length from 6 to 12 dpf concomitant with the upregulation of growth-stimulating genes, including IGF-1, growth hormone-1 (GH-1), growth hormone receptor-1 (GH-R1), and cholecystokinin (CCKA). In peculiar, at 9 dpf, GABA increased growth rate from 3.60 ± 0.02 to 3.79 ± 0.03, 3.89 ± 0.02, and 3.92 ± 0.04 mm at 6.25, 12.5, and 25 mM comparable to 4 mM β-glycerophosphate (GP)-treated larvae (3.98 ± 0.02 mm). Additionally, the highest concentration of GABA (50 mM) induced 50% death in zebrafish larvae at 12 dpf. GABA also enhanced IGF-1 expression and secretion in preosteoblast MC3T3-E1 cells concomitant with high level of IGF-1 receptor (IGF-1R). In zebrafish larvae, GABA-induced growth performance remarkably decreased in the presence of an IGF-1R inhibitor, picropodophyllin (PPP), which indicates that GABA-induced IGF-1 enhances growth performance via IGF-1R. Furthermore, we investigated which GABA receptors affect growth performance along with IGF-1 activation. The inhibitors of GABAA and GABAB receptors, bicuculline and CGP 46381, considerably inhibited GABA-induced zebrafish growth rate accompanied by a marked decrease of growth-stimulating genes, including IGF-1, GH-1, GHR-1, and CCKA, but not with an inhibitor of GABAC receptor, TPMPA. Additionally, IGF-1 and IGF-1R expression was also impaired in bicuculline and CGP 46381-treated MC3TC-E1 cells, but not with TEMPA. Furthermore, treatment with bicuculline and CGP 46381 significantly downregulated GABA-induced IGF-1 release in MC3T3-E1 cells. These data indicate that GABA stimulates IGF-1 release via GABAA and GABAB receptors, leading to promotion of growth performance via IGF-1R. 2021-12-01T00:00:00Z http://repository.rjt.ac.lk/handle/123456789/3571 Visualization of Doubling times and Comparison of Control measures for COVID-19 in Sri Lanka and China Gunarathne, M. V. H. S.; Dilakshana, K.; Jayathilake, R. M. S. D. L. Coronavirus disease 2019 (COVID-19) is an emerging infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Epidemic doubling time is a measure of disease transmissibility and characterizes the sequence of intervals at which the cumulative incidence doubles. These metrics could be used to integrate real-time information regarding the epidemic's spread over time. This study aims to analyze the effect of control measures on the COVID-19 pandemic in Sri Lanka evaluating the fluctuation of calculated doubling times (td, in days) of cases and deaths with time by comparing the corresponding epidemic data with China in hope of benefiting from fighting against the pandemic. This was a descriptive study. The data of cumulative incidence of cases and deaths related to COVID-19 in Sri Lanka and China were extracted, doubling times were calculated and compared about key events during the corresponding period and the control measures implemented in the two countries. The calculated doubling times for the total number of cases in Sri Lanka were td1=60, td2=19, td3=12, td4=13, td5=23, td6=105, td7=40, td8=14, td9=27, td10=43, td11=102, td12=40 and td13=81 whereas the doubling times for China were td1=1, td2=2, td3=2, td4=2, td5=4, td6=3, td7=4, td8=7 and td9=397. Doubling times for the total number of deaths in Sri Lanka were td1=2, td2=3, td3=31, td4=175, td5=13, td6=10, td7=106, td8=44, td9=53, td10=70, td11=23, td12=44 and td13=33 while for the China; doubling times for deaths were obtained as td1=5, td2=3, td3=2, td4=0, td5=3, td6=2, td7=1, td8=4, td9=4, td10=6, td11=9 and td12=59. After the first case in Sri Lanka, the government imposed stringent public health measures and social distancing leading to a drastic drop in the transmission rate at the beginning showing a high doubling time. The second wave was largely due to local transmissions and their contacts and the government-controlled the spread of the pandemic by imposing an island-wide quarantine curfew. With the spread of the Delta variant, the previously controlled pandemic became more virulent, thus leading to an aggressive third wave. Doubling timelines for both cases and deaths in China indicate a gradual increase in doubling times which in turn confirms an efficient national COVID-19 control policy and economic strategies implemented in China. The findings of the study show that China’s COVID-19 control measures are more effective since their doubling time in both cases and deaths are getting higher remarkably with time. Although Sri Lanka has shown successful disease management at the beginning of the pandemic, the implementation of strict control measures would be more beneficial. 2021-12-01T00:00:00Z http://repository.rjt.ac.lk/handle/123456789/3570 Views and Experiences of Lifestyles of Overweight and Obese People A Qualitative Study in a Selected Group of Sri Lankans Bookoladeniya, D. R.; Perera, R. H.; Senevirathne, K. A.; Silva, S. M.; Gunawardana, H. A. K. S. Overweight & obese people have different perspectives on weight management. Stigma and discrimination toward obese persons are pervasive and pose numerous consequences for their psychological and physical health. This qualitative study has been conducted to explore the views and experiences of lifestyles of overweight and obese people. Ethical approval was obtained from the Ethics Review Committee of CINEC Campus, Malabe. A purposive sample of 30 (17 overweight and 13 obese) from selected walking paths in Colombo District was taken and semi-structured interviews were conducted to collect the data. Data analysis was done by using thematic analysis. 03 major themes emerged; living with increased body weight is challenging, unrealistic expectations, social pressures. Difficulty in performing normal daily activities, difficulty in finding clothes as per preference where the sub-themes derived under life with increased body weight is challenging. Under the major theme of unrealistic expectations, the majority of the participants expect to lose weight, most of them stated that they find it difficult to control the food intake & do weight monitoring regularly. Under the major theme of social pressures, respondents were being criticized, humiliated by the closed people, and making them feel negative were the subthemes. Weight loss is a difficult task with physical, social, behavioral & environmental elements that appear to assist and inhibit weight-loss efforts concurrently. The findings suggested the critical role of support in the obesity self-management process. Awareness of the perception of the people who have excess body weight is needed for society to minimize the psycho-social impact on them. Society can play a major role to increase the quality of life of people with increased body weight. 2021-12-01T00:00:00Z