Athapattu B.C.L.,The Open University of Sri Lanka |
Thalgaspitiya T.W.L.R.,National Water Supply and Drainage Board |
Yasaratne U.L.S.,National Water Supply and Drainage Board |
Vithanage M.,Sri Lanka Institute of Fundamental Studies |
Vithanage M.,University of Southern Queensland
Environmental Geochemistry and Health | Year: 2017
The objectives were to investigate the potential remedial measures for reverse osmosis (RO) rejected water through constructed wetlands (CWs) with low-cost materials in the media established in chronic kidney disease of unknown etiology (CKDu) prevalent area in Sri Lanka. A pilot-scale surface and subsurface water CWs were established at the Medawachchiya community-based RO water supply unit. Locally available soil, calicut tile and biochar were used in proportions of 81, 16.5 and 2.5% (w/w), respectively, as filter materials in the subsurface. Vetiver grass and Scirpus grossus were selected for subsurface wetland while water lettuce and water hyacinth were chosen for free water surface CWs. Results showed that the CKDu sensitive parameters; total dissolved solids, hardness, total alkalinity and fluoride were reduced considerably (20–85%) and most met desirable levels of stipulated ambient standards. Biochar seemed to play a major role in removing fluoride from the system which may be due to the existing and adsorbed K+, Ca+2, Mg+2, etc. on the biochar surface via chemisorption. The least reduction was observed for alkalinity. This study indicated potential purification of aforesaid ions in water which are considerably present in RO rejection. Therefore, the invented bio-geo constructed wetland can be considered as a sustainable, economical and effective option for reducing high concentrations of CKDu sensitive parameters in RO rejected water before discharging into the inland waters. © 2017 Springer Science+Business Media Dordrecht
Perera K.A.R.S.,The Open University of Sri Lanka |
Amarasinghe M.D.,University of Kelaniya
Atmospheric Environment | Year: 2016
Characterization of the micro-tidal mangrove forests in Negombo estuary, located on the west coast of Sri Lanka, with respect to its capacity to remove atmospheric carbon and sequestration in above and below ground plant components is the objective of this study. These mangroves constitute both natural stands (e.g. Kadolkele) and woodlots planted, protected and managed by fishermen (e.g. Wedikanda) to extract twigs and branches to construct "brush parks", a traditional method of fishing in this estuary. Both types of mangrove stands support high species richness and structural diversity, indicating planted mangrove areas have reached a semi-natural state. Allometric relationships were used to calculate biomass increment. Differences in litterfall, above and below ground biomass increment and net primary productivity (NPP) of the two types of mangrove areas were statistically insignificant, thus indicating that they are structurally and functionally comparable. Average rate of mangrove litterfall in Negombo estuary was 802 ± 25 g m-2y-1. The average above ground biomass increment was 1213 ± 95 gm-2y-1 and below ground increment was 267 ± 18 gm-2y-1, thus the average NPP of these mangroves was 2282 ± 125 g m-2y-1. NPP showed a decreasing trend from water towards land, in line with plant density and leaf area index. A statistically significant relationship was found between vegetation structure (represented by complexity index), NPP and rate of organic carbon accumulation in mangroves. Potential carbon accumulation capacity of mangroves of Negombo estuary was estimated to be approximately 12 t ha-1y-1, which is equivalent to the amount of carbon emitted as CO2 through combustion of 19,357 L of diesel or 22,212 L of gasoline in motor vehicles. Potential atmospheric carbon removal capacity of Negombo estuarine mangroves (350 ha in extent) therefore was estimated to be 4143 t y-1, which is equivalent to removal of CO2 emitted through combustion of 6,779,000 L of diesel or 7,779,000 L of gasoline within a year. © 2016 Elsevier Ltd.
Dileepa Chathuranga P.K.,Sri Lanka Institute of Fundamental Studies |
Priyantha N.,University of Peradeniya |
Iqbal S.S.,The Open University of Sri Lanka |
Mohomed Iqbal M.C.,Sri Lanka Institute of Fundamental Studies
Environmental Earth Sciences | Year: 2013
This study reports the potential ability of non-living biomass of Cabomba caroliniana for biosorption of Cr(III) and Cr(VI) from aqueous solutions. Effects of contact time, biosorbent dosage, pH of the medium, initial concentration of metal ion and protonation of the biosorbent on heavy metal-biosorbent interactions were studied through batch sorption experiments. Cr(III) was sorbed more rapidly than Cr(VI) and the pH of the medium significantly affected the extent of biosorption of the two metal species differently. Surface titrations showed that the surface of the biosorbent is positively charged at low pH while it is negatively charged at pH higher than 4.0. Protonation of the biosorbent increased its capacity for removal of Cr(III), while decreasing that of Cr(VI). FT-IR spectra of the biosorbent confirmed the involvement of -OH groups on the biosorbent surface in the chromium removal process. Kinetic and equilibrium data showed that the sorption process of each chromium species followed pseudo second-order kinetic model and both Langmuir and Freundlich isothermal models. A possible mechanism for the biosorption of chromium species by non-living C. caroliniana is suggested. © 2012 Springer-Verlag Berlin Heidelberg.
Dias T.,University of Manchester |
Delkumburewatte G.B.,The Open University of Sri Lanka
Journal of the Textile Institute | Year: 2010
The absorbency properties of knitted structures are very important in designing garments that both remove liquid sweat from the skin and provide tactile and sensorial comfort to the wearer. Water absorbency by knitted spacer structures was experimentally investigated using a gravimetric absorbency tester to record absorbency rate, total absorbency and time taken to saturate the structure. The geometry of spacer structures was analysed and a model created to define the capillary characteristic in the spacer yarn. Absorbency into the spacer structures was modelled using the fabric parameters, the capillary radius and the properties of water. Experimental and theoretical results were compared to validate the models. © 2010 The Textile Institute.
Delkumburewatte G.B.,The Open University of Sri Lanka |
Dias T.,Nottingham Trent University
Journal of the Textile Institute | Year: 2012
This paper presents the working principle of a wearable miniature cooling system investigated by us for managing heat and sweat effectively and efficiently under extreme conditions. The cooling system consists of peltier units and mini refrigerant channels incorporated in a knitted spacer structure. The knitted spacer structure absorbs sweat and accumulates it to keep the skin dry. The cold side of the peltier units absorbs heat from the skin and transfers the heat to the refrigerant, which is converted to gas by the absorption of evaporative heat. The mini refrigerant channels are connected to a high pressure liquid refrigerant cylinder and to a gas receiver via polymer tubes. The wearable cooling system was evaluated using a test rig designed to simulate the origination of human body heat and a sealed environment similar to that inside a CBRN garment. Test results show that the temperature remains constant, when the cooling system is active even though the heat energy was produced continuously. This wearable cooling system can be used to manage heat and sweat under extreme conditions. © 2012 Copyright The Textile Institute.
Jayawardana H.A.R.K.,The Open University of Sri Lanka |
Weerahewa H.L.D.,The Open University of Sri Lanka |
Saparamadu M.D.J.S.,The Open University of Sri Lanka
Journal of Horticultural Science and Biotechnology | Year: 2015
Resistance to anthracnose disease was investigated in Capsicum annuum L. ‘Muria F1’ by adding silicon (Si) to the nutrient solution in a hydroponic system. Four different concentrations of potassium silicate (K2Si2O5): 0 mg l-1 (control), 50 mg l-1, 75 mg l-1, or 100 mg l-1 were used to find the optimum concentration of Si that suppressed anthracnose disease. Disease resistance in the fruit of plants treated with different concentrations of Si was assessed by artificial inoculation with Colletotrichum gloeosporioides or C. capsici. Significant reductions in lesion areas were observed in fruit from plants treated with Si compared to fruit from Si-free plants. There were 75% and 64% reductions in disease caused by C. gloeosporioides in the fruit from plants treated with 75 mg l-1 or 100 mg l-1 Si, respecively, and the equivalent reductions were 78% and 84% for C. capsici. Potassium silicate at 75 mg l-1 was also applied at different stages of plant development (vegetative growth or flowering), or at both stages, as separate treatments to determine the effect of the stage of Si application on the severity of anthracnose disease. Reductions in lesion areas of 76% and 71% were observed on fruit from plants treated with 75 mg l-1 Si at both stages, or at the flowering stage, respectively, compared to control fruit (0 mg l-1 Si). However, the application of Si during the vegetative growth stage did not reduce lesion areas significantly. Si had no significant effect on plant growth or on fruit quality parameters in Capsicum. The mechanisms underlying the effect of Si treatment were investigated by measuring the thickness of the cuticle and by analysing total and cell wall-bound phenolic compounds. The concentrations of cell wall-bound phenolic compounds and cuticle thickness were significantly greater in fruit from plants treated with Si than in fruit from Si-free (control) plants. © 2015, Headley Brothers Ltd. All rights reserved.
Senadheera P.,The Open University of Sri Lanka |
Tirimanne S.,University of Colombo |
Maathuis F.J.M.,University of York
Rice Science | Year: 2012
Salinity stress induces oxidative stress caused by reactive oxygen species (ROS): superoxide radicals, hydrogen peroxide (H 2O 2) and hydroxyl radicals. Activities of both enzymatic and non-enzymatic components of the antioxidant system and related growth parameters were studied in the roots of the salt tolerant rice variety FL478 and the sensitive variety IR29 in response to long term stress (12 d) induced by 50 mmol/L NaCl. The comparative study showed that FL478 maintained higher relative growth rate and lower Na +/K + in the roots than IR29 due to a higher membrane stability index that effectively exclude Na +. Lower TBARS (thiobarbituric acid reactive substance) content in FL478 roots indicated that its membrane was relatively unaffected by ROS despite high H 2O 2 content recorded under the salinity stress. Relatively higher superoxide dismutase activity along with a parallel increase in transcript level of superoxide dismutase (Os07g46990) in FL478 indicated that this protein might make a vital contribution to salt stress tolerance. Although the content of ascorbic acid remained unchanged in FL478, the activity of ascorbic peroxidases (APOXs) was reduced comparably in the both varieties. Transcriptomic data showed that a larger number of peroxidase genes were upregulated in FL478 compared to IR29 and several of which might provide engineering targets to improve rice salt tolerance. © 2012 China National Rice Research Institute.
Senadheera P.,The Open University of Sri Lanka
Methods in molecular biology (Clifton, N.J.) | Year: 2012
Exposure to high ambient levels of NaCl affects plant water relations and creates ionic stress. To a large extent, responses to such stress depend on the action of membrane transporters, particularly those that move cations such as Na(+) and K(+). A genomics approach can greatly help with the identification of important membrane transporter genes. This can be done by comparing transcriptomes of salinized and non-salinized plants, by comparing tolerant and non-tolerant species, or by using intraspecies variation. This chapter describes a protocol using oligo-microarrays to compare salinity treated (50 mM NaCl) and non-treated rice roots, presenting protocols for growth, RNA isolation, cDNA synthesis and labeling, and a summary of data collection, analysis, and interpretation. Although focused on rice root tissue, the described procedures can be applied to many different treatments, tissues, and plant species.
Kahandagamage G.A.,LTL Transformers Pvt Ltd |
Senanayake N.S.,The Open University of Sri Lanka |
Jatunarachchi T.S.S.,The Open University of Sri Lanka
International Review of Mechanical Engineering | Year: 2013
This paper presents the results of a study carried out to determine the variations of Specific Fuel Consumption (SFC) and fuel efficiency in day time and night time operation of an intercooled direct injection diesel engine of 17MW used for electrical power generation. In the study pressure development curves for 18 cylinders were obtained and the Mean Indicated Pressure (MIP) and crank positions for the Peak Pressure, Kinetic Burning (KB), and Diffusive Burning (DB) points were analyzed. The results showed a reduction of 1.9% in SFC in the night time operation in which the charge air temperature was lower and relative humidity was higher than those of day time. The reasons for changes in SFC are explained with the changes in the incylinder pressure curves. Further, the fuel efficiency was found to be increased in the night time by 0.8%. © 2013 Praise Worthy Prize S.r.l. - All rights reserved.
PubMed | University of Colombo, The Open University of Sri Lanka and University of Sri Jayewardenepura
Type: Journal Article | Journal: Asian nursing research | Year: 2016
To validate the Cardiff Wound Impact Schedule (CWIS) to assess the health-related quality of life (HRQoL) of Sri Lankan patients with diabetic leg and foot ulcers.English version of CWIS was examined for cultural compatibility, translated into Sinhala and pretested. The Sinhala version was administered in parallel with the validated Sinhala version of SF-36 by an interviewer to all patients (n= 140) at baseline to determine the construct validity. Reliability of CWIS was measured by internal consistency and test-retest stability. The instrument was readministered in 2 weeks on 33 patients with nonhealing ulcers to determine the test-retest stability and in 3 months on 50 patients with healed ulcers to determine the ability of CWIS to discriminate HRQoL between patients with healed versus nonhealed ulcers. Acceptability of CWIS was assessed by the response rate, completion rate and the average time taken to complete a single interview.The construct validity demonstrated moderately significant correlations between related subscales of CWIS and SF-36 (Spearmans r= .32-.51, p= .021 to p < .001) for the whole study sample. Internal consistencies (Cronbach = .68-.86) and test-retest stability (.56-.70) were acceptable. The tool was sensitive in discriminating the impact of the wound on HRQoL in healed versus nonhealed status (p .001). The tool showed good acceptability.The Sinhala version of CWIS is valid, reliable and acceptable for assessing the impact of wound on HRQoL. This instrument is sensitive in detecting the differences of the impact of healed and nonhealed ulcers on QoL in patients with diabetic leg and foot ulcer.