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  Journal of the National Science Foundation of Sri Lanka
  [SJR: 0.16]   [H-I: 5]   [1 followers]  Follow
  This is an Open Access Journal Open Access journal
   ISSN (Print) 1391-4588
   Published by Sri Lanka Journals Online Homepage  [45 journals]
  • Third National Workshop on Lichens: over fifteen years of progress in
           lichen research in Sri Lanka

    • Abstract: J.Natn.Sci.Foundation Sri Lanka 2015 43 (2):195-196 Published on None
  • ACE-inhibitory activity of milk fermented with Saccharomyces cerevisiae K7
           and Lactococcus lactis subsp. lactis NBRC 12007

    • Abstract: The angiotensin-I converting enzyme (ACE) inhibitory activity of the milk fermented with Lactococcus lactis subsp. lactis NBRC 12007 and Saccharomyces cerevisiae K7 in monoculture and co-culture was evaluated. Bovine full-fat milk was fermented with each strain in monoculture and co-culture at 30 ºC for 72 h, and the in vitro ACE inhibitory activity (%) of each milk sample was determined by a fluorogenic assay using H-(2)Abz-Acp(6)-Ala-Phe(4-NO2)-Leu-OH as the substrate. The ACE inhibitory percentages of the milk samples fermented with L. lactis subsp. lactis NBRC 12007 and S. cerevisiae K7 monocultures and the co-culture was 33, 27 and 25 %, respectively, which varied significantly (p < 0.05). Each milk sample was fractionated by semi-preparative HPLC analysis and the ACE inhibitory activity (%) of each fraction was determined using the same substrate, which varied from 20 - 47 %, 16 - 37 % and 16 - 31 % in the milk fermented with L. lactis subsp. lactis NBRC 12007, S. cerevisiae K7 and the co-culture, respectively. The highest ACE-inhibitory activity (47 %) was observed in fraction-2 of the milk fermented with L. lactis subsp. lactis NBRC 12007. The results concluded that the two strains tested were able to hydrolyze milk proteins into ACE-inhibitory peptides in order to produce fermented milk products with ACE-inhibitory activity, both in monoculture and co-culture. Therefore, it can be suggested that these strains can be successfully utilized in the dairy industry in manufacturing fermented milk products with ACE-inhibitory activity as a dietary supplement and/or as an alternative approach for antihypertensive medication.J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 141-151 Published on None
  • Toxicity assessment of industrial wastewaters reaching Dandugan Oya, Sri
           Lanka using a plant based bioassay

    • Abstract: Industrial waste may contain complex chemical mixtures with potential cytotoxic and genotoxic effects. The Dandugan Oya, a water canal located in the Western Province of Sri Lanka receives industrial waste from multiple sources. In the present study potential toxicity of selected industrial wastewaters reaching the Dandugan Oya, and the downstream water was assessed using a plant based bioassay with onion (Allium cepa L. var. ascalonicum) as the test organism. Of the physico-chemical characteristics tested, temperature, pH, biochemical oxygen demand, chemical oxygen demand, cadmium and chromium levels of the wastewaters collected during three sampling occasions in the year 2012 were within the national tolerance limits specified for the discharge of industrial effluents into inland surface waters. The exposure of A. cepa bulbs to wastewater and downstream water from the Dandugan Oya resulted in the reduction of root growth (24 – 62 %) and mitosis (31 – 55 %), induction of micronuclei (up to 0.6 %), nuclear abnormalities (3 - 14 folds) and chromosomal aberrations (3 - 21 folds) in the root tip meristematic cells compared to those exposed to the control and the upstream water, indicating cytotoxic and genotoxic effects. No significant difference between the control and the upstream water was found in relation to the measured biological effects (p > 0.05). The present study revealed that the tested wastewaters contained cyto-genotoxic contaminants and, the inherent dilution/detoxification capacity of Dandugan Oya during the study period was not adequate to eliminate the toxic effects in the downstream water. In addition to the conventional physico-chemical analyses, inclusion of suitable bioassays as additional assessments in water quality monitoring programmes could alert cyto-genotoxic impacts in wastewater receiving inland surface waters.J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 153-163 Published on None
  • Evaluation of bio-acetal as a sustainable alternative jet fuel

    • Abstract: The European Council’s strict regulation on carbon dioxide (CO2) emission-allowances for all flights taking off and landing on EU countries has encouraged the development of bio-jet fuels from plant oil due to its advantage of carbon neutrality. The common production methods of bio-jet fuel involve the thermo-chemical cracking of plant oil into short carbon chain fragments of around C8 to C10 compounds. This is often conducted at high reaction temperature and pressure.In the present study a milder approach using ozonization and electrolysis has been applied for the cracking of fatty acid methyl esters derived from sunflower oil, and the acceptability of the reaction products in bio-blend jet fuel was evaluated. The major chemical compounds generated were aldehydes, but the thermal stability of these compounds was too poor to be utilized as a bio-jet fuel. Acetal, which can be derived from aldehyde, has a high thermal stability and at the same time its flash point, specific energy and freezing point are comparable to that of Jet A-1 fuel. A 10 % blend of 1,1- dimethoxynonane (acetal derived from nonanal) did not change the important fuel properties of Jet A-1. The high thermal stability of this blend was also confirmed.J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 165-171 Published on None
  • Effect of endophytic fungi on plant growth and blast disease incidence of
           two traditional rice varieties

    • Abstract: Traditional rice varieties, although low producers of yield, are more amenable to organic farming practices that cause less damage to the environment and human health. Improved growth and reduced disease incidence would produce higher yields, and endophytic fungi have proven to be effective in achieving these ends in wheat. With this in view, endophytic fungal assemblages of two traditional rice varieties of Sri Lanka i.e. Suwandel and Kaluheenati were evaluated for their effect on the growth and disease incidence of rice plants, because the endophytic mycoflora of these two traditional rice varieties and their effects have not been studied before. The most common and the highest occurring endophytes of both rice varieties i.e. Absidia and Cylindrocladium were tested to determine their effect on rice plant growth and the results showed that the plants inoculated with both fungal isolates showed significant increases (p ≤ 0.05) in plant height, fresh weight and dry weight. Twenty two endophytic fungal isolates common to both rice varieties were screened using dual culture assay for their ability to control the mycelial growth of Magnaporthe grisea, the causative agent of rice blast disease. All tested endophytes controlled pathogen growth by coiling the hyphae around the pathogen and forming clamps and loops. However, Absidia and Acremonium showed the highest growth inhibition of the pathogen (100 %) and showed an abundance of the above inhibitory structures. The effect of crude culture filtrates of thirteen endophytic fungi tested using the diffusion plate method indicated antagonistic activity against the rice pathogen. In planta tests were carried out to assess the effect of three endophytic fungi i.e. Acremonium, Absidia and Penicillium on infection by M. grisea. Disease symptoms were observed only on the leaves of the rice plants grown from Penicillium inoculated seedlings and controls treated with 1×107 spores/mL suspension of the pathogen. Pre-inoculation with Acremonium and Absidia were effective in preventing infection by the blast fungus. No disease symptoms were observed in plants pre-inoculated with endophytes and in plants used as controls sprayed with a 1×105 spores/mL suspension of the pathogen. Twenty one endophytic fungi common to both rice varieties were assessed by the culture plate method in this study.J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 173-187 Published on None
  • Evaluation of cover soil properties of solid waste dumpsites in Colombo
           District, Sri Lanka

    • Abstract: Landfill cover soils have to serve multiple purposes such as operational safety, environmental protection, recultivation and integration of the sites into the landscape. Cover soil properties must therefore be defined with respect to the thickness, bulk density, air permeability and the available field capacity. The primary objective of this study is to examine the cover soil properties of three selected landfill sites (dumpsites) in Sri Lanka in order to propose suitable cover soil properties for similar applications in future dumpsites. Soil samples were obtained from three landfill sites in and around the city of Colombo. Laboratory tests to establish compaction characteristics, air permeability, particle size distribution and Atterberg limits were performed to assess the suitability as landfill cover soils. The study showed that landfill covers with well graded soils comply with the dry density and air permeability values, as per the guidelines. In the absence of proper gas venting facilities, it is essential to study the permeability properties of the cover soil. All three landfill sites tested need to be retrofitted with leachate and gas collecting systems that meet the standards stipulated in the guidelines.J.Natn.Sci.Foundation Sri Lanka 2015 43 (2):189-194 Published on None
  • Assessment of body composition of Sri Lankan Australian children using
           ethnic specific equations

    • Abstract: Since ethnic differences exist in body composition, assessment methods need to be validated prior to use in different populations. This study attempts to validate the use of Sri Lankan based body composition assessment tools on a group of 5 - 15 year old Australian children of Sri Lankan origin. The study was conducted at the Body Composition Laboratory of the Children’s Nutrition Research Centre at the Royal Children’s Hospital, Brisbane, Australia.Height (Ht), weight (Wt), segmental length (Lsegment name) and skinfold thickness (SFT) were measured. The whole body and segmental bio impedance analysis (BIA) were also measured. The body composition determined by the deuterium dilution technique (criterion method) was compared with the assessments done using prediction equations developed on Sri Lankan children. 27 boys and 15 girls were studied. All predictions of body composition parameters, except percentage fat mass (FM) assessed by the SFT-FM equation in girls gave statistically significant correlations with the criterion method. They had a low mean bias and most were not influenced by the measured parameter. Although living in a different socioeconomic state, the equations developed on children of the same ethnic background gives a better predictive value of body composition. This highlights the ethnic influence on body composition.J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 111-118 Published on None
  • Two new antioxidant active polyketides from Penicillium citrinum, an
           endolichenic fungus isolated from Parmotreama species in Sri Lanka

    • Abstract: Bioassay guided fractionation of the ethyl acetate extract of a laboratory culture of Penicillium citrinum, an endolichenic fungal strain isolated from a Parmotrema species in Sri Lanka, led to the isolation of two new fungal polyketides (1 and 2). The structures of these compounds were determined on the basis of their 1D NMR, 2D NMR and FABMS spectroscopic data. The two compounds (1 and 2) showed radical scavenging activity with IC50 values of 159.7 ± 22.3 μg/mL and 68.6 ± 4.3 μg/mL, respectively in DPPH antioxidant assay. The antioxidant activity of compound 2 was comparable to the standard antioxidant compound butylated hydroxytoluene (BHT).Natn.Sci.Foundation Sri Lanka 2015 43 (2): 119-126  Published on None
  • Computation of the different topological indices of nanostructures

    • Abstract: In this research study, several topological indices have been investigated for linear [n]-Tetracene, V- Tetracenic nanotube, H-Tetracenic nanotube and Tetracenic nanotori. The calculated indices are first, second, third and modified second Zagreb indices. In addition, the first and second Zagreb coindices of these nanostructures were calculated. The explicit formulae for connectivity indices of various families of Tetracenic nanotubes and nanotori are presented in this manuscript. These formulae correlate the chemical structure of nanostructures to the information about their physical features.J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 127 - 133 Published on None
  • Traffic composition and variability of road traffic noise levels in the
           vicinity of Colombo, Sri Lanka

    • Abstract: A study was conducted to determine the contribution of different types of vehicles to road traffic noise levels. Measurements were carried out on three different categories of roads at six separate locations, approximately 30 km away from the city of Colombo. At each location, continuous noise measurements were taken for a duration of 13 hours on weekdays and several key noise level descriptors (Leq, L10, L50, L90) were measured simultaneously. It was observed that A-weighted equivalent noise level (Leq) along main roads and secondary roads reached ~70 dB(A), which is the maximum permissible noise level prescribed for road traffic by Japan for residential areas. Similar to previous studies, a linear correlation was observed between Leq and other noise descriptors. Specially L10, which can be related to annoyance, can be estimated with an accuracy of ± 1 dB(A) by measuring Leq. The correlation between the rate of vehicle flow and the measured noise level showed a logarithmic relationship. It is shown that the key noise descriptors can be estimated with an accuracy of ± 2.5 dB(A) by measuring the flow rate of vehicles. The vehicle composition showed that heavy vehicles such as lorries, buses and containers contribute significantly to the average noise levels.J.Natn.Sci.Foundation Sri Lanka 2015 43 (2): 135-140 Published on None
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