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Comparative analysis of major indoor air pollutants across residences, schools, and offices in Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka., 2024) Senanayake, T. A. A. W.; Nandasena, S.; Kalpage, L. U.; RanawakaArachchci, V.
Indoor air pollution poses significant health risks, yet comprehensive data on exposure levels in Sri Lanka remains scarce. The study aimed to determine the predominant indoor air pollutant levels in 25 residences, 11 schools, and 23 offices across six districts in Sri Lanka, selected based on their geographical proximity and activities. The methodology involved monitoring a range of pollutants, including PM2.5, PM10, HCHO, Total Volatile Organic Compounds (TVOC), O3, CO, NO2, and SO2. Each monitoring session, conducted over a single day, involved eight hours of continuous sampling. Eight-hour mean values were PM2.5 (24 ± 1.53 μg/m3), PM10 (40 ± 1.63 μg/m3), HCHO (0.03 ± 0.03 mg/m3), TVOC (0.12 ± 0.10 mg/m3), O3 (0.021 ± 0.008 mg/m3), CO (1.11 ± 1.17 mg/m3), NO2 (13.30 ± 6.35 μg/m3), SO2 (33.39 ± 14.01 μg/m3). According to the “Guidelines for Indoor Air Quality in Sri Lanka 2022,” the results revealed that PM2.5 and PM10 levels in residences were below the reference values of 100 μg/m³ and 150 μg/m³, respectively. Schools and offices showed PM10 levels within the acceptable 200 μg/m³ limit. TVOC and CO levels across all locations were below 1 mg/m³ and 10 mg/m³, respectively, while SO2 and NO2 levels were below 200 μg/m³. The highest mean CO2 concentration of 692.47 ppm was observed in offices. Correlation analyses were conducted to identify potential relationships among pollutants, providing insights into their sources, pathways, and interactions within indoor environments. Statistical analyses using the Spearman rank correlation coefficient indicated strong positive correlations between PM2.5 and PM10 (R = 0.99) and between TVOC and HCHO (R = 0.73), while CO2 showed a moderate positive correlation with HCHO (0.496). Notably, there was a moderate negative correlation between RH and temperature (-0.528), and between CO2 and temperature (-0.484). This study highlights the need for targeted interventions to improve indoor air quality in various settings in Sri Lanka.
Evaluation of a cellulose-based dipstick method for DNA extraction from Leptotrombidium mites: A comparative study
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka., 2024) Ambanpola, N.; Manilgama, T.; Premaratna, R.; Seneviratne, K. N.; Jayathilaka, N.
The Leptotrombidium mites are vectors of Orientia tsutsugamushi and a significant public health threat worldwide: scrub typhus is endemic in Sri Lanka. In this respect, the need to extract DNA from the Leptotrombidium mites in the field is critical for rapid diagnosis and surveillance; nevertheless, this presents some difficulties, including sample degradation and lack of specialist equipment. This study aims to validate a cellulose-based dipstick method against a commercial kit for efficient DNA extraction from Leptotrombidium mites. The DNA extraction from samples was thus performed with three methods: the cellulose-based dipstick method, the simple heat-lysis method, and the DNeasy Blood and Tissue Kit as a commercial benchmark. Assessments of DNA quality and quantity were done spectrophotometrically. Real-time PCR was done with primers of 16S rRNA targeting O. tsutsugamushi DNA. Agarose gel electrophoresis was conducted for the determination of the amplification. Descriptive statistics, paired Wilcoxon signed rank tests for DNA concentration and purity ratios, and Kruskal-Wallis tests for cycle threshold values were computed from the data. The DNA concentration and the total yield were highest in the DNeasy method. The dipstick method had a DNA concentration of 0.933 ± 0.138 μg/mL, while the mean values of the DNeasy and the heat-lysis methods were 3.240 ± 0.276 μg/mL and 0.840 ± 0.035 μg/mL, respectively. The dipstick method had the most variable A260/A280 ratios at 1.773 ± 0.215, while that of the DNeasy and the heat-lysis methods were 1.496 ± 0.087 and 1.418 ± 0.000, respectively. The comparison of Ct values did not show any statistically significant difference between methods, P = 0.2697. In conclusion, the cellulose-based dipstick method performed comparably to the heat-lysis method. Despite DNA yield and purity differences, all three methods produced similar PCR results. This method encompasses simplicity in conduct, cost-effectiveness, and field applicability, showing promising further developments in on-site DNA extraction.
Salivary miR-150-5p as a Thymus-influenced early non-invasive prognostic marker for severe dengue: A bioinformatics analysis
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka., 2024) Ambanpola, N.; Manilgama, T.; Seneviratne, K. N.; Jayathilaka, N.
MicroRNAs play important roles in regulating gene expression and cellular functions during viral infections, including dengue fever. While miR-150-5p has been identified as a circulating biomarker in blood, its potential in saliva as an early, non-invasive prognostic marker for severe dengue (SD) has yet to be explored. We analyzed multiple NCBI GEO datasets (GSE150623, GSE190749, GSE123336, GSE209670, and GSE139242) to examine miR-150-5p expression across bio-fluids. Differentially expressed genes and miRNAs were determined according to a threshold log2 fold change (logFC) > 1 and adjusted p-value (adj. p) < 0.05. We utilized mirDIP, miRDB, and TargetScanHuman to predict miR-150-5p target genes, which were cross-verified with human genes interacting with Dengue viral proteins using the DenHunt Database. The KEGG pathway analysis was performed in the NetworkAnalyst platform. Overlapping genes identified through Venn diagrams were considered as the candidate thymus-specific proteins potentially involved in dengue viral interactions. We observed significant upregulation of miR-150-5p plasma samples from SD patients compared to dengue fever patients, with logFC = 1.214798 and adj. p = 0.0368. In non-dengue samples, we found high expression in saliva compared to serum with logFC = 2.349937 and adj. P = 6.30E-05, and plasma with logFC = 2.036475 and adj. P = 0.0014. We identified 15 Specific Dengue-Related Genes (SDRGs) as miR-150-5p targets, 7 of which directly interact with dengue proteins: ANKRD12, CCNT1, CD38, CTNNB1, PDIA6, STAT1, and TNF. KEGG analysis revealed enrichment in immune pathways, such as T-cell receptor signaling, implicating miR-150-5p in the immune response to dengue. Differential expression of SDRGs revealed STAT1, overexpressed in CD4+ and CD8+ thymic T-cells. The results implicate the interplay between miR-150-5p, thymic activity, and immune response during dengue infection. These findings suggest that salivary miR-150-5p, through its regulation of immune-related genes and thymic activity, may serve as a reliable early prognostic marker for SD, warranting further clinical validation.
Optimization of total anthocyanidins quantification using HPLC and selection of suitable cultivars for purple tea production
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka., 2024) Basnayake, P.; Piyasena, K. G. N. P.; Amarakoon, A. M. T.; Ranatunga, M. A. B.
Optimization of a protocol to extract anthocyanins and to quantify anthocyanidins present in five selected standard tea cultivars established in Tea Research Institute, Talawakelle, Sri Lanka, using HPLC was carried out in this study. The main aim of the present study was to evaluate the potential of tea cultivars to produce purple tea. The quantification of anthocyanidins were carried out in the fresh leaf and in processed tea samples of the five standard cultivars. The anthocyanins were extracted using acidified methanol/HCl (99:1 v/v) as the extractant. The extracted anthocyanins were further purified using C18 solid phase extraction cartridges followed by immediate acid hydrolysis using 2N HCl. Characterization of anthocyanidins were done using HPLC, and they were identified based on the retention times and the order of elution compared to the four anthocyanidin standards used in the study. Malvidin chloride was not detected in any of the five cultivars. Delphinidin chloride and cyanidin chloride were detected in all five cultivars, but pelargonidin chloride was detected only in TRI 26 and TRI 2043 cultivars. The highest anthocyanidin content, which was 0.847 mg g-1, was recorded in the fresh leaf of the TRI 5006 cultivar, and the lowest anthocyanidin content was detected in the fresh leaf of the TRI 3055 cultivar, which was 0.044 mg g-1. According to the results, TRI 5006, TRI 26 and TRI 2043 are potential cultivars to produce purple tea. Therefore, the present study is useful for quantifying anthocyanins and anthocyanidins to screen suitable cultivars for the processing of purple tea.
Optimization of sulfuric acid electrolyte concentration for coconut shell charcoal-derived activated carbon-based supercapacitors
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka., 2024) Jayathilaka, A. P. S. P.; Bambaradeniya, R. R. M. M. N. B.; Medagedara, A. D. T.; Kumara, G. R. A.
Supercapacitors differ from regular capacitors due to their high capacitance values (>1F), whereas the capacitance of regular capacitors is limited to microfarad values. Various factors affect the electrochemical properties of a supercapacitor, such as electrode material, electrolyte, electrolyte concentration, and separator. Among other aqueous electrolytes like KOH and Na2SO4, sulfuric acid (H2SO4) has several advantages, including high ionic conductivity, cost-effectiveness, and ease of handling. Recent studies have focused on using biomass materials to prepare activated carbon electrodes for supercapacitors because of their renewability, low cost, and abundance. In this study, we prepared activated carbon-based supercapacitors using coconut shell charcoal and optimized the H2SO4 electrolyte concentration. First, charred coconut shells were heated at 900 ℃ for 20 minutes in a low-oxygen environment and then immediately put into a water bath for activation. Next, the activated carbon chips were dried and ground into a fine powder. Afterward, a thin layer of activated carbon suspension (0.05 g of polyvinylpyrrolidone, 10 ml of isopropyl alcohol, and 0.5 g of activated carbon powder) was deposited on two preheated titanium plates (20 × 10 × 0.45 mm) and sintered at 300 ℃ for 20 minutes. Then, they were immersed in 2.0 M H2SO4 for 2 minutes. Finally, the supercapacitor was assembled by sandwiching a medium-retention filter paper (separator) between the electrodes and wetting it with 2.0 M H2SO4 electrolyte. Four more supercapacitors were prepared by repeating the last three steps for 2.5 M, 3.0 M, 3.5 M, and 4.0 M H2SO4 concentrations. Cyclic voltammetry (5 mV s-1 scan rate) and galvanostatic charge-discharge analysis (1.0 A g-1 current density) were performed on supercapacitors, resulting in specific capacitance values of 20.17, 22.17, 29.77, 14.94, and 12.04 F g-1 for the 2.0 M, 2.5 M, 3.0 M, 3.5 M, and 4.0 M supercapacitors, respectively. Hence, the 3.0 M supercapacitor exhibited the highest specific capacitance of 29.77 F g-1 with the highest energy density of 4.14 Wh kg-1, lower power density of 342.09 W kg-1, and long cycle stability with a capacity retention of 69.67% after 1000 charge-discharge cycles. These results warrant that 3.0 M is the optimal H2SO4 electrolyte concentration for the coconut shell charcoal-derived activated carbon-based supercapacitors.