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Journal Cover Journal of the National Science Foundation of Sri Lanka
  [SJR: 0.166]   [H-I: 8]   [2 followers]  Follow
  This is an Open Access Journal Open Access journal
   ISSN (Print) 1391-4588
   Published by Sri Lanka Journals Online Homepage  [49 journals]
  • Quantitative measurement of bioactive compounds from leaves of Syzygium
           samarangense with antioxidant efficacy

    • Abstract: Botanicals have been explored for their multitude of pharmaceutical and therapeutic potential. In this study, crude methanolic extract (MSSL) and organic soluble fractions of Syzygium samarangense leaves were evaluated for antioxidant activity using in vitro and in vivo models. To evaluate the antioxidant activity, total antioxidant capacity, free radical scavenging ability (DPPH) and reducing power, assays were conducted in vitro. Lipid peroxidation and activities of different antioxidant enzymes were measured in vivo. Quantitative phytochemical analyses such as the measurement of total phenolic, flavonoid, flavonol, and proanthocyanide contents were also evaluated. The ethyl acetate fraction (ESSL) showed significant effects in DPPH assay (IC50 = 38.84 ± 0.08 μg/mL) and reducing power assay. The effect of ESSL was found to be concentration-dependent with remarkable antioxidant activity as compared to other tested samples. In addition, administration of the extract/fractions (200 and 400 mg/kg body weight) to male Wistar rats increased the percentage of inhibition of reduced glutathione, superoxide dismutase and catalase significantly (p < 0.05). The level of lipid peroxidation decreased at 400 mg/kg body weight after seven days in hepatotoxic rats. The pharmacological findings of this study clearly indicate that extracts and/or fractions of Syzygium  samarangense leave could be a source of natural antioxidants.    Published on 2017-06-30 03:45:37
  • Facilitated colonisation of the diazotroph Azorhizobium caulinodans in
           rice roots detected through GFP-labelling

    • Abstract: Rice being a non-legume, does not possess the capacity to carry out biological nitrogen fixation in symbiosis with rhizobia. Azorhizobium caulinodans is a micro-symbiont of Sesbania rostrata with several unique and beneficial characteristics that makes it a potential candidate to induce biological nitrogen fixing associations with the rice plant.  Maximum colonisation of rice by the bacterium is important for high benefit. This study was aimed at finding the maximum colonisation levels of A. caulinodans detected by GFPlabelling of the bacterium. A. caulinodans was labelled with green fluorescent protein to facilitate accurate and real time observations of the bacterium in and around the root hairs. GFPlabelling was carried out by inserting the gfp-gene-containing plasmid pBBR5-hem-gfp5-S65T into A. caulinodans ORS 571, with a helper plasmid (pRK2013) by tri-parental-mating. The bacterium was observed to colonise rice roots by bright green fluorescence emitted by the bacterium under blue light. The fluorescence intensities reflecting the degree of colonisation of the bacteria were quantified using Zen light image analysis software and were statistically analysed. Highest colonisation was observed when 5 mL of the labelled Azorhizobium was applied twice a week, and the observations were made 15 days after application of the inoculum in the presence of the  flavonoid naringenin.     Published on 2017-06-30 03:37:25
  • Geo-statistical models for determining spatial variation and spatial
           dependency of soil arsenic in Bangladesh

    • Abstract: Arsenic (As) toxicity has become a major problem since a few decades in different parts of Bangladesh mainly due to the massive groundwater extraction for both drinking and irrigation purposes. This study was undertaken to investigate the spatial variation and spatial dependency of soil As at four locations in Bangladesh. Composite soil samples were collected at 0 ‒ 45 cm depth in a grid area of 1 m2 to conduct the study of a shallow tube well command area (micro level). Based on composite soil sampling in four different study locations, laboratory analysis and statistical modelling, the spatial variation and dependency of soil As was estimated. Four study area maps were digitised using ArcGIS. Arsenic concentration varied widely within the study areas. The extent and propensity of As concentration was higher in areas with a high concentration of As in groundwater and soil. About 15.01 ppm of As is loaded into soils through groundwater irrigation every year in the As affected areas. The semi-variogram model for describing spatial dependency of soil As was found to be scale dependent. At study area scale, the appropriate model was identified as spherical. Kriging method appeared to be more suitable to create an interpolated surface for study area scale.  Development of As tolerant rice varieties, promoting cropping  patterns that require less irrigation water, and alternate wetting  and drying (AWD) method can be remedial measures to reduce  As contamination in soil as well as in the food chain.   Published on 2017-06-29 11:53:40
  • Effect of T-shaped spur dike on flow separation in a 90° bend using
           SSIIM model

    • Abstract: Spur dikes are used widely as flow control structures in rivers. The main direction of the flow is changed by a spur dike, which is accompanied by formation of separation and reattachment zones around the spur dike. This study was focused  on the effect of a submerged single T-shaped spur dike and the  influence of the distance between non-submerged T-shaped spur  dikes, in determining the separation and reattachment zones in  a 90° bend using the SSIIM (sediment simulation in intakes  with multi-block option) numerical model. The spur dike was installed at the middle of the outer bank in a movable-bed channel. It was observed that by increasing the submergence ratio, the length of separation and reattachment zones can be reduced, and by increasing the distance between two spur dikes the length of reattachment zone downstream of spur dikes can be increased. For all submergence ratios, from the bed level upwards to the crest level of the spur dike, the length of flow separation zone decreases, but the length of flow reattachment zone increases (dike crest level is equal to water depth level on the dike). By changing the dike submergence, the dimensions of the vortices around the dike can be changed due to variations in the flow separation and reattachment zones.     Published on 2017-06-29 11:21:45
  • Development of a Sri Lankan rice variety Bg 94-1 harbouring cry2A gene of
           Bacillus thuringiensis resistant to rice leaffolder [Cnaphalocrocis
           medinalis (Guenée)]

    • Abstract: The rice leaffolder (RLF) [Cnaphalocrocis  medinalis (Guenée)] is a major lepidopteran insect pest of  rice in Sri Lanka and the larvae cause significant yield losses  annually. Insecticidal crystal protein gene, cry2A driven by the  35S cauliflower mosaic virus (CaMV) promoter with a double  enhancer sequence was transformed into scutellum derived  embryogenic calli of Bg 94-1 via Agrobacterium tumefaciens  mediated transformation procedure. Transformation vector pCAMBIA 1305.1 containing the transgene construct CaMV 35S d-cry2A-NOS, hygromycin phosphotransferase and β-glucuronidase (GUS)-Plus was employed in this study. Transformed calli were subjected to 4 ‒ 5 rounds of hygromycin selection. Molecular analysis of the generated plants together with an insect bioassay using RLF larvae confirmed successful transformation and expression of this transgene in T0 generation of rice plants. A total of 19 putative transgenic plants could be confirmed from a total of 60 T0 generation plants examined.  Insect feeding bioassay demonstrated that T0 transgenic rice plants are effective against RLF larvae, and showed approximately 89 % larval mortality after 3 days and 100 % mortality after 5 days of feeding. Further molecular analysis of T1 generation of the transgenic lines confirmed the stable integration of cry2A transgene into the Bg 94-1 genome.  Findings of this study demonstrated that the cry2A gene of Bacillus thuringiensis (Bt) was successfully transformed into Bg 94-1 via Agrobacterium mediated transformation and have developed resistance against the RLF larvae. Thus, this study highlights the importance of developing transgenic rice, which can provide insect resistance against a major lepidopteran insect pest of rice in Sri Lanka.     Published on 2017-06-29 11:10:11
  • In vitro clonal propagation of Coscinium fenestratum (Gertn.) Colebr.
           (Weniwel) through nodal explants

    • Abstract: An in vitro clonal propagation protocol for Coscinium  fenestratum was developed using shoot explants detached from  1 − 2 year old vines maintained under plant house conditions, by  successfully surface sterilising with 0.2 % solution of mercuric  chloride for 30 minutes followed by two successive washings  with sterilised distilled water. McCowns woody plant medium (WPM) incorporated with 1.0 mgL-1 polyvinylpyrrolidone to minimise browning, was the best medium for establishment of nodal cuttings.  Mature double nodal cuttings resulted in the highest shoot  proliferation rate (3.90 shoots/explant) when cultured on WPM  medium supplemented with 2.0 mgL-1 6-benzylaminopurine,  1.0 mgL-1 thidiazuron and 0.4 mgL-1 2,4-dichlorophenoxyacetic  acid. Shoots were separated and transferred to WPM medium devoid of plant growth regulators for regeneration into plantlets. The plantlets were successfully acclimatised on coir dust: sand (1:1) potting media with over 60 % survival rate. The results proved that the protocol developed is effective for clonal propagation of C. fenestratum.   Published on 2017-06-29 10:58:09
  • Incorporation of nanoclay into field latex to develop nanoclay filled dry
           rubber compounds

    • Abstract: Two types of nanoclay filled dry rubber compounds were prepared by incorporating sodium montmorillonite (MMT) into natural rubber (NR) at latex stage. Nanoclay filled rubber sheets prepared by acid co-coagulation (ACC) and acid free co-coagulation (AFCC) rubber production methods were milled and compounded to develop nanoclay filled dry rubber compounds. The MMT loading was varied from 0 to 20 phr.  Both the above methods are not used as filler incorporation methods in dry rubber industry. AFCC rubber vulcanisates, compared to ACC rubber vulcanisates showed improved mechanical properties mainly due to increased crosslink density associated with the presence of natural accelerators and nano-scale dispersion obtained under acid free environment.  The AFCC method is proposed as a new route in filler incorporation, which shows the best mechanical properties at a MMT loading of 8 phr. At higher MMT loadings, due to the formation of aggregated clay structures associated with filler-filler interactions, tensile strength and elongation at break decreased. Modulus and hardness increased with the increase of MMT loading, while tear strength remained unchanged.  XDR deffractograms and SEM images revealed that the AFCC rubber at optimum loading has partially exfoliated clay structures with fine phase morphology. DSC analysis revealed that no significant rubber-filler interactions are formed in the rubber vulcanisates. Published on 2017-06-29 10:49:24
  • Association of iron and vitamin A status with birth weight and anaemia
           among 6 month old infants in an urban population of Sri Lanka

    • Abstract: Iron and vitamin A deficiencies are the commonest nutrition related problems in childhood, leading to severe health consequences. The objective of this study was to assess the relationship of iron and vitamin A status with birth weight and anaemia at 6 months of age of Sri Lankan infants. Ninety six healthy infants, aged 6 ‒ 6.5 months, were recruited from two Well-Baby Clinics in the Colombo Municipal Council area. Anthropometric parameters were assessed and an interviewer administered questionnaire was used to obtain data on their basic characteristics and feeding practices. Haemoglobin, serum ferritin, and retinol concentrations were estimated. The mean concentrations (CI) of haemoglobin, serum ferritin and serum retinol at 6 months were 11.2 g/dL (95 % CI 9.0, 13.3), 15.5 μg/L (95 % CI 11.0, 20.0) and 34.8 μg/dL (95 % CI 19.3, 50.3), respectively. The prevalence of anaemia (haemoglobin < 11 g/dL) was 43.0 % (95 % CI 33, 53), while iron deficiency (serum ferritin < 12 μg/L) was 36.8 % (95 % CI 27, 47). Both were relatively high. In contrast, only one child had vitamin A deficiency (serum retinol < 20 μg/dL). A significantly higher prevalence of anaemia (47 versus 41 %) and lower serum ferritin [11.5 (95 % CI 6.4, 16.6) versus 15.8 (95 % CI 11.5, 20.1) μg/L] was seen among low birth weight infants compared to normal birth weight infants. The prevalence of iron deficiency was higher among anaemic infants compared to non-anaemic infants (49 versus 29 %), and among low birth weight infants compared to normal weight infants (60 versus 33 %). However, these differences were not significant (p > 0.05). Although anaemia and iron deficiency were observed in these infants, vitamin A deficiency was not observed. Starting iron supplementation at six months could be beneficial while vitamin A supplementation programme needs re-evaluation.  Published on 2017-06-29 10:42:02
  • Impact of Madden Julian oscillation (MJO) and other meteorological
           phenomena on the heavy rainfall event from 19th − 28th December, 2014
           over Sri Lanka

    • Abstract: This study revealed the influence of Madden Julian oscillation (MJO) and cold surge (CS) on the extreme rainfall events that occurred in Sri Lanka from 19th to 28th December 2014. During this period, the Northeast Monsoon winds over the Bay of Bengal were strengthened by a CS, which intensified convective activity over the Bay of Bengal. Simultaneously, convective phase 3 of the MJO, which was located over the eastern Indian Ocean is associated with a positive rainfall anomaly over Sri Lanka. Westerly wind anomalies associated with MJO phase 3 shifted southward due to the strengthening of northeasterly winds by the CS, forming an incipient vortex to the southeast of Sri Lanka. The low level moisture transport was enhanced by this vortex circulation together with strong cross-equatorial moisture flux transportation. The convectively active phase of MJO provided favourable conditions such as low level convergence, cyclonic relative vorticity, and deep convection for the intensification of vortex into a tropical depression over the southwest Bay of Bengal. Strong upward motion and combination of strong low level convergence with upper-level divergence allowed evacuation of the ascending air mass, aiding the intensification of deep convection. This persistent vertical coupling structure allowed deep convection of moist warm air, which led to heavy rainfall during the period. Combination of a number of factors, such as local terrain effects, CS at low levels, MJO wet phase and a vortex to southeast of Sri Lanka led to an intensification of the tropical depression that caused an extreme rainfall event over the Eastern and Northeastern parts of Sri Lanka. Published on 2017-06-29 10:13:40
  • Biodegradation of microcystin analogues by Stenotrophomonas maltophilia
           isolated from Beira Lake Sri Lanka

    • Abstract: Bacterial strain 4B4 capable of degrading microcystin-LR (MC-LR) was isolated from the Beira Lake (N 6° 55’ 46’’, E 79° 51’ 15’’) in Sri Lanka. Based on phylogenetic analysis of the 16S rRNA gene sequence, the isolate 4B4 was identified as Stenotrophomonas maltophilia. The bacterium showed 100 % removal of MC-LR in 10 and 8 days of incubation at 28 °C and 32 °C, respectively. Optimisation studies confirmed that the addition of nitrates (0.4 ppm) and phosphates (0.02 ppm) to the medium can increase the microcystin removal rate of the bacterial strain. Further evaluation of S. maltophilia revealed that it is capable of degrading other microcystin analogues; microcystin-RR, -LW, -LF and nodularin (NOD) as well. Published on 2017-06-29 10:03:33
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