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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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Journal of Science of the University of Kelaniya Sri Lanka
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1391-9210
Published by Sri Lanka Journals Online Homepage  [71 journals]
  • Low-cost microfluidic electrochemical paper-based device to detect glucose

    • Abstract: Continuous monitoring of the level of glucose is essential to maintain the health of a diabetic patient. The use of invasive methods to obtain blood samples to detect glucose is the current method, but such methods may not be preferred by patients. Non-invasive methods such as the determination of glucose based on saliva or sweat can be preferred by patients for continuous monitoring. A low-cost electrochemical microfluidic paper-based analytical device (µPAD) suitable to monitor glucose levels using sweat and saliva is introduced. This device is extremely low-cost due to the use of a paper matrix and varnish for the fabrication of paper. Pseudo-reference stainless steel is used with a working electrode anodized using sodium potassium tartrate tetrahydrate for the development of a three-electrode system. Cyclic voltammetric-based analysis of glucose with µPAD produced a linear response in the working range of 1-10 mmol dm-3 with a limit of detection of 0.058 mol dm-3. The detection of diabetic conditions using saliva and sweat is possible using the device by correlating to the blood glucose levels using prior literature data. Published on 2022-04-05 00:00:00
       
  • The abundance of mosquito larvae in relation to associated microbiota and
           physicochemical parameters of marshland habitats in Kelaniya in Gampaha
           district of Sri Lanka

    • Abstract: The abundance of mosquito larvae in relation to associated microbiota and physicochemical parameters of water in marshes from selected habitats in Kelaniya divisional secretariat area, of the Gampaha district, Sri Lanka were studied. Culex gelidus was found to be the dominant mosquito species found in marshes followed by Culex whitmorei, Culex tritaeniorhynchus, Culex quinquefasciatus, Culex fuscocephala, and Anopheles peytoni. Fourteen species/taxa of microbiota were identified. There was a significant positive correlation between the abundance of Cx. gelidus larvae and level of organic pollution in marshes as measured by the five-day Biological Oxygen Demand. A positive correlation for the presence of Cx. fuscocephala and Cx. gelidus in the marshland was also observed. Nevertheless, abundance of Cx. gelidus was negatively correlated with Cx. quinquefasciatus and Cx. whitmorei. The presence of Culex gelidus and Cx. tritaeniorhynchus were positively correlated with Daphnia magna indicating their co-existence in the same habitat requirement. Culex gelidus was negatively affected by the epibiont, Vorticella microstoma, when the latter organisms were present in higher densities. In contrast, the presence of Cx. whitmorei was positively influenced by the Vorticella microstoma, Difflugia corona, nauplius larva, and Keratella valga. There was a negative correlation between Cx. whitmorei and Monostyla bulla (Rotifera; Monogononta) and between the abundance of Cx. fuscocephala and Lecane luna in the same marshland. This study concludes that mosquito larvae and some microbiota are interdependent in marshlands. The level of abundance of mosquito larvae and microbiota varied with the level of water pollution. Cx. gelidus larvae are biologically affected by Vorticella microstoma. Many microbiota species compete with mosquito larvae for the same food items. Published on 2022-04-05 00:00:00
       
  • Population dynamics and breeding preference of Aedes aegypti and Ae.
           albopictus attributing to dengue threat in Kelaniya medical officer of
           health area in Sri Lanka

    • Abstract: Aedes aegypti and Ae. albopictus are the two species of dengue vector mosquitoes in Sri Lanka. Indoor and outdoor distribution of these species, their population dynamics and breeding preference are important factors determining the dengue transmission. Gampaha district in Sri Lanka reported to have frequent dengue epidemics from recent past, hence this study was conducted. Ovitrap surveillance was conducted to determine the vector species distribution in indoor and outdoor in Kelaniya Medical Officer of Health (MOH) area of the Gampaha district. Larvae were reared until emergence of adults in the laboratory to identify species morphologically. Breeding preference of vector mosquitoes were carried out by physically observing the presence of mosquito larvae in water accumulated  receptacles in  the area. Aedes aegypti and Ae. albopictus were reported to distribute throughout Kelaniya MOH area as a mixed population. Ae. albopictus is the most abundant species both indoor and outdoor in Kelaniya MOH area compared to Ae. aegypti. Weather factors, rain days and wind positively correlated with Aedes population. High risk areas were identified as Kiribathgoda and Hunupitiya in this study. Published on 2021-12-31 00:00:00
       
  • Calcium ion adsorption of Leucaena leucocephala wood biochar activated
           with coconut vinegar

    • Abstract: A positive correlation has been reported recently among the number of Chronic Kidney Disease of Unknown Etiology (CKDu) patients and the levels of groundwater hardness. Hence, the need for a low cost and a simple domestic process to reduce the hardness of potable water is identified to improve living standards of low-income communities in these disease affected areas. Biochar has emerged as a low cost adsorbent for water treatment, because of its abundance and cost-effectiveness. This study was aimed to evaluate the ability of natural coconut vinegar, in activating Leucaena leucocephala wood biochar to be used in calcium ion (Ca2+) removal from potable water. Column tests showed a 1.7 fold increase of Ca2+ adsorption capacity and a 7 fold increase of Ca2+ retaining capacity upon the vinegar treatment. Batch studies matched with both Langmuir (R2 = 0.9761) and Freundlich (R2 = 0.9785) isotherm models. Ca2+ amount in solutions were measured using flame photometry. Ca2+ adsorption capacities of raw biochar and activated biochar determined by column tests ranged from 3.10-3.82 mg/g and 5.27-6.68 mg/g respectively while Ca2+ retaining capacities ranged from 0.16-0.22 mg/g and 1.28-1.4 mg/g respectively. Fourier transform infrared spectra, suggests hydration of the C-O-C bridges of the biochar surface introducing new -O-H groups and possible introduction of carbonyl/ ester/carboxylic functional groups to the biochar surface upon vinegar treatment. According to scanning electron microscopy porosity of the biochar remained stable after the vinegar treatment. Published on 2021-12-28 17:04:44
       
  • Photocatalytic activity of GO/Fe3O4 fabricated by Sri Lankan graphite
           under visible light irradiation

    • Abstract: Graphene oxide (GO) was synthesized using Sri Lankan naturally available graphite and Fe3O4 nanoparticles were successfully incorporated fabricating magnetically separable GO/Fe3O4 nanocomposite. The synthesized nanocomposites were characterized by X-ray diffractometry (XRD), Scanning electron microscopy (SEM), and FT-IR spectroscopy. Crystalline phases of GO and Fe3O4 nanoparticles were identified by XRD patterns, while the presence of functional groups such as –COOH, OH, CH2 was confirmed by FT-IR spectroscopy. SEM images show that Fe3O4 nanoparticles with an average particle size of 107 nm ranging between 56-150 nm are dispersed on GO while restacking and folding of the nanosheets have been observed with incorporation of Fe3O4 nanoparticles. The photocatalytic performance of the photocatalysts was evaluated on photodegradation of methylene blue under visible light irradiation. The GO/Fe3O4 shows better adsorption behavior and excellent photocatalytic activity where it could be successfully used for three cycles without significant activity loss. This is due to the enhanced charge separation resulted due to the presence of GO sheets and better interactions between GO and Fe3O4. Published on 2021-11-03 00:00:00
       
  • Magnetic properties of ferromagnetic thin films with three spin layers as
           described by fourth-order perturbed Heisenberg Hamiltonian

    • Abstract: The magnetic properties of ferromagnetic thin films with three spin layers were investigated for the first time using fourth-order perturbed Heisenberg Hamiltonian. Total magnetic energy was determined for ferromagnetic materials with simple cubic lattice. The simulation was carried out for Heisenberg Hamiltonian with different second-order magnetic anisotropy constants in different spin layers. The total magnetic energy periodically varies with spin-exchange interaction, azimuthal angle of spin, and the second-order magnetic anisotropy constant in each spin layer. The peaks along the axis of the angle are closely packed except in the 3-D plot of energy versus angle and second-order magnetic anisotropy constant of the middle spin layer. 2-D plots were perceived by rotating 3-D plots in MATLAB. According to the 3-D plot, the angle between magnetic easy and hard directions is 90 degrees. The minimum energy range was found in the 3-D plot of energy versus angle and the second-order anisotropy constant of the middle spin layer. The samples with the minimum magnetic anisotropy energies have potential application in transformer cores, magnetic switching, and magnetic amplifiers. Published on 2021-09-10 00:00:00
       
  • Domestic electricity usage estimation model using socio-economic factors

    • Abstract: In this empirical study, socioeconomic factors that can easily be extracted from families have been used to build a "home electricity usage prediction" model based on two variables, family monthly income and family size. Each of these factors was evaluated individually. Two machine learning models were built using those factors as features. Models are based on “Linear regression” and “Random Forest” algorithms. This study revealed that the socioeconomic factors such as family size and family income are very effective in domestic electricity usage prediction model building, where the end usages are not known. Furthermore, the random forest algorithm was found to be more effective for unseen data than the linear regression algorithm. The accuracy of the models can be further improved by adding more data into the both models. Published on 2021-06-18 00:00:00
       
  • Field Evaluation of Selected Common Household Containers as Oviposition
           Attractants of Aedes Albopictus (Diptera: Culicidae

    • Abstract: Dengue is a fatal arthropod-borne disease that affects humans worldwide. The mosquito Aedes albopictus (Skuse) is the secondary vector of dengue in Sri Lanka, however, studies on oviposition preferences of Ae. albopictus is scarce. The objective of the current study was to investigate the oviposition attraction of Aedes albopictus to selected household containers; black colour basins, metal cans, rain gutter parts, curd pots, coconut shells and yoghurt cups. For this, water containers for oviposition were placed in three outdoor shady sites and at three different heights. The mosquito larvae were collected after 5 days. The larvae were reared to adult stage and then they were identified and enumerated. Wing lengths of adult female mosquitoes that developed in different containers were measured. In the meantime, temperature, pH, dissolved oxygen (DO) and total dissolved solids (TDS) were measured in each container. The Ae. albopictus larval density was higher in coconut shells. The maximum mean number of mosquito larvae was observed in the containers at ground level. The oviposition attraction of Ae. albopictus was increased with the aging of coconut shells and old coconut shells were preferred than new coconut shells. Highest TDS level and neutral pH were observed in coconut shells which support the mosquito oviposition. The highest wing lengths were observed in female Ae. albopictus that developed in curd pots, representing higher fecundity. In conclusion, discarded coconut shells and curd pots should be carefully managed as means of eliminating dengue vector mosquito breeding sites. Published on 2021-02-12 14:25:07
       
  • Nemato-toxic potential of Trichoderma harzianum and T. viride
           extra-cellular metabolites and Annona glabra crude extraction on
           Meloidogyne incognita infestation

    • Abstract: Root-knot nematode, Meloidogyne incognita (Kofoid and White) is one of the most destructive plant parasitic nematode species in almost all agriculture and horticulture crops in Sri Lanka. Biologically sound controlling measures against this nematode species has been attempted from long past with ambiguous efficacy. This paper highlights the nemato-toxic potential of crude leaf extract of Annona glabra, and extracellular metabolites of Trichoderma harzianum and T. viride on root-knot nematode species, Meloidogyne incognita infesting in spinach plants under semi-field conditions. Results revealed that nematode infested plants treated with T. harzianum extract showed a significantly higher plant growth together with reduced root galling compared to that of T. viride and A. glabra crude extract. Both T. harzianum and T. viride treatments significantly increased the root growth of the nematode infested plants compared to that of A. glabra crude extract. Annona glabra crude leaf extract at the rate of 125 g/L and fungus mycelium of T. viride and T. harzianum at the rate of 140 mg/L and 100 mg/L respectively resulted the highest nemato-toxic potential against M. incognita. This study concludes positive effect of antagonists tested against M. incognita and suggests that activity of lytic enzymes of T. harzianum and T. viride has enhanced the nemato-toxic effect. Published on 2021-03-24 00:00:00
       
  • Selenium content in Bg 350 variety of rice consumed by Sri Lankans

    • Abstract: Selenium is considered as an essential micronutrient. The daily requirement of selenium is 55 µg. As a result, the World Health Organization (WHO) has drawn their attention to establish the micronutrient range of selenium, required by the human body. Report from China has shown that an ecological correlation exists with the selenium content in the soil and increased mortality due to cancer and cardiovascular diseases with light intake of selenium. This led to the interest in assessing the nutritional status of selenium. Rice is the staple food of Sri Lankans and studies on selenium content in rice grown in Sri Lanka have not been reported. The present study reports the selenium content in Bg 350 variety of rice and soil obtained from twelve districts (Gampaha, Colombo, Matara, Hambantota, Kegalle, Matale, Anuradhapura, Pollanaruwa, Kurunegalle, Puttalam, Ampara and Moneragalle), in Sri Lanka determined using Hydride Generation Atomic Absorption spectrometer (HGAAS). The results of the study showed that selenium content in rice and soil obtained from Gampaha and Colombo districts were very low and less than the detectable levels of the instrument (0.5 μg/kg). Except for rice and soil from Pollanaruwa district that had a very high selenium content in rice (61.2 μg/kg) and soil (69.8 μg/kg), the respective values from other districts were low [13.8 μg/kg (Kegalle) -6.3 μg/kg (Anuradhapura)] and [20.3 μg/kg (Matara) -9.5 μg/kg (Matale)]. Published on 2020-07-20 00:00:00
       
 
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