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Journal Cover 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  [46 journals]
  • Effect of Zn as soil addition and foliar application on yield and protein
           content of wheat in alkaline soil

    • Abstract: Zinc (Zn) deficiency in plant tissues is a reflection of both genetic and soil-related factors and is the most widespread problem in cereal crops worldwide, resulting in severe losses in the yield and nutritional quality. Developing cost-effective and quick solutions to Zn deficiency is, therefore, highly important. An experiment was conducted during 2009 − 2010, to assess the effects of various modes and concentrations of applied Zn on wheat yield and nutritional quality grown in alkaline soils. Both soil addition and foliar spray of ZnSO4 significantly increased grain yield, 1000 grain weight and grain protein content, while its effect on biological yield and grain protein composition was not significant. Foliar spray of 0.5 % and 1.0 % ZnSO4 increased grain yield by 10 and 18.8 %, respectively while its soil application at the rate of 5, 10 and 15 kg ha-1 increased grain yield by 18, 32 and 41%, respectively over the control. The treatments receiving ZnSO4 as 5 kg ha-1 soil + 1.0 % foliar, 15 kg ha-1 soil + 1.0 % foliar and 5 kg ha-1 soil + 0.5 % foliar application recorded 29.5, 29.0 and 27.5 % higher protein contents, respectively over the control. Comparing the value cost ratios (VCR) for the treatments showing higher grain yield and protein content, the VCR for 5 kg ha-1 ZnSO4 as soil + 1.0 % ZnSO4 as foliar (10.23) was three times higher than the VCR for 15 kg ha-1 ZnSO4 as soil + 1.0 % ZnSO4 as foliar (3.46), thus confirming the superiority of the former over the latter in terms of effectiveness. The results further revealed that despite presumably sufficient native Zn concentration in the soils under study (1.95 mg kg-1), the crop responded positively to Zn treatment and therefore the Zn level of sufficiency (1 mg kg-1) should be reconsidered in accordance with the nature and type of soils.J.Natn.Sci.Foundation Sri Lanka 2015 43 (4): 303 - 312 Published on 2016-01-01 09:37:39
  • Effect of pressure on the valency of cerium in cerium monochalcogenides
           and cerium monopnictides

    • Abstract: Application of pressure on a material changes its properties due to the modification of the electronic states of the constituent atoms. Various effects of pressure on the properties of solid material have been identified, and valency change of an element in a compound is one of the effects of pressure. This study was aimed at finding the valency change as a function of pressure of some compounds. The valency changes of cerium in cerium monochalcogenides CeX (X = O and S) and cerium monopnictides CeX (X = P and As) as functions of pressure have been calculated utilising the reported data. For calculating the valency change of Ce, the reported experimental pressure-volume relationships of CeO, CeS, CeP and CeAs have been reproduced using the Birch equation of state. The corresponding pressure-volume relationships of these compounds for stable trivalent cerium have also been calculated using the same Birch equation. The change in valency is calculated by a technique, which considers the difference between the calculated and experimental lattice parameters at each pressure value of the concerned compound. Clear effect of pressure on the cerium valency has been obtained for each compound from the present calculation.J.Natn.Sci.Foundation Sri Lanka 2015 43 (4): 313 - 317 Published on 2016-01-01 09:45:51
  • Transcriptome analysis for discovering candidate genes involve in
           embryogenesis in coconut (Cocos nucifera L.) through 454 pyrosequencing

    • Abstract: Coconut, Cocos nucifera L. is a major plantation crop, which ensures income for millions of people in the tropical region. Detailed molecular studies on zygotic embryo development would provide valuable clues for the identification of molecular markers to improve somatic embryogenesis. Since there is no ongoing genome project for this species, coconut expressed sequence tags (EST) would be an interesting technique to identify important coconut embryo specific genes as well as other functional genes in different biochemical pathways. The goal of this study was to analyse the ESTs by examining the transcriptome data of the different embryo tissue types together with one somatic tissue. Here, four cDNA libraries from immature embryo, mature embryo, microspore derived embryo and mature leaves were constructed. cDNA was sequenced by the Roche-454 GS-FLX system and assembled into 32621 putative unigenes and 155017 singletons. Of these unigenes, 18651 had significant sequence similarities to non-redundant protein database, from which 16153 were assigned to one or more gene ontology categories. Homologue genes, which are responsible for embryo development such as chitinase, beta-1,3-glucanase, ATP synthase CF0 subunit, thaumatin-like protein and metallothionein-like protein were identified among the embryo EST collection. Of the unigenes, 6694 were mapped into 139 KEGG pathways including carbohydrate metabolism, energy metabolism, lipid metabolism, amino acid metabolism and nucleotide metabolism. This collection of 454-derived EST data generated from different tissue types provides a significant resource for genome wide studies and gene discovery of coconut, a non-model species.J.Natn.Sci.Foundation Sri Lanka 2015 43 (4): 319-336 Published on 2016-01-01 09:54:50
  • Modelling and analysis of dengue disease transmission in urban Colombo: a
           wavelets and cross wavelets approach

    • Abstract: Transmission of dengue is a complex dynamic process. Dengue virus is transmitted to humans by the female Aedes aegypti mosquitoes. Dengue was first identified in Sri Lanka during 1960s and the risk due to dengue has increased rapidly during the past few decades mainly in the urban areas. There are several studies on dengue transmission based on mathematical and statistical models. However they are not capable of describing the complex dynamics of transmission since its transmission mechanism is highly dependent on various external factors such as climate, demography, geography and human mobility. Wavelet analysis is a powerful tool in mathematics, which can be used to reveal useful information of a highly non-stationary epidemiological time series. Wavelet theory can be used to obtain vital signals in a noisy epidemiological time series, which is useful to implement early warning systems to control the spread of epidemics. This particular study was aimed at investigating the applicability of wavelet theory to analyse dengue transmission in urban Colombo. The wavelet transformation was performed with data from weekly dengue cases time series from year 2006 to 2012 in the Colombo Municipal Council (CMC) area, and significant regions were observed in the spectrum that correspond to approximately 25 week cycles during the time period from year 2009 to 2012. The cross wavelet power spectrum showed that rainfall was leading the dengue cases in Colombo during the time period 2010 to 2012.  J.Natn.Sci.Foundation Sri Lanka 2015 43 (4): 337-345   Published on 2016-01-01 10:00:32
  • Coordinated inertia response from permanent magnet synchronous generator
           (PMSG) based wind farms

    • Abstract: A simplified model of a wind turbine connected to the grid through a power electronic interface was developed to carry out inertia response studies. This model was validated using the detailed model simulation and experimental results. The results show that wind turbines provide inertia response for 3 − 4 s and then operate at reduced power until they return to their steady state operating point. As this could hinder the frequency recovery of the power system, the aggregated inertia response from a wind farm was investigated by delaying the frequency signal to the inertia controller of each turbine based on their status of operation. How local frequency measurements can be used for a wind farm connected through an AC network is also discussed. By connecting a number of wind turbine models in parallel and operating them under different wind speeds, frequency commands and inertia controller gains, it was demonstrated that an inertia response of more than 10 s can be provided by coordinating the inertia response of individual turbines.J.Natn.Sci.Foundation Sri Lanka 2015 43 (4): 347-355 Published on 2016-01-01 10:04:45
  • Simulation study of a novel method for comparing more than two independent
           receiver operating characteristic (ROC) curves based on the area under the
           curves (AUCs)

    • Abstract: Receiver operating characteristic (ROC) graphs are useful for organising binary classifiers and visualising their performance. In order to compare classifiers it may be needed to reduce the ROC performance to a single scalar value representing expected performance. Such a commonly used summary statistic is the area under the curve (AUC) of the ROC curve. The AUCs can be estimated either parametrically or non-parametrically. The parametric approach assumes that the signal present (positive) and signal absent (negative) groups can be represented as two overlapping Gaussian distributions. If the observations of two or more ROC curves are obtained from the same region of interest, their AUCs are considered to be correlated.A novel asymptotic test for comparing multiple AUCs of several ROC curves was proposed by Meyen and Sooriyarachchi in 2014, and it was of interest to study the behaviour of the test statistic for various sample sizes and varying degrees of overlap between the Gaussian distributions via a simulation study. Hence this study was carried out to test the properties of the test statistic when the AUCs were estimated parametrically by Dorfman and Alf’s method. This simulation was carried out for the case where the AUCs are independent.Inferences were made regarding the distribution of the test statistic for various sample sizes. The test statistic performed better when the spread between the two Gaussian distributions increased, while the test statistic was valid with respect to sample sizes above 100 when 2 ROC curves were being compared simultaneously.J.Natn.Sci.Foundation Sri Lanka 2015 43 (4):357-367 Published on 2016-01-01 10:09:22
  • Subject Index Vol 43-2015

    • Abstract: Published on 2016-01-01 10:18:56
  • Author Index Vol 43-2015

    • Abstract: Published on 2016-01-01 10:18:33
  • List of Referees Vol 43-2015

    • Abstract: Published on 2016-01-01 10:16:44
  • The effect of cefazolin on biogas production from thermophilic and
           mesophilic anaerobic co-digestion of dairy manure and waste milk

    • Abstract: Antibiotic residues in animal waste from concentrated animal feeding operations are of considerable concern because of the potential development of antibiotic resistant bacteria in the environment and the effect of these residues on manure treatment systems. The objective of this study was to determine the effect of cefazolin (10 mg L-1) during thermophilic and mesophilic anaerobic co-digestion of manure and waste milk from cows treated with cefazolin for mastitis. The collected antibiotic free manure samples were mixed with slurry and milk obtained from a healthy cow accordingly to form manure mixture (slurry 50 % and manure 50 %) and milk mixture (slurry 50 %, manure 45 % and milk 5 %), each of which was further separated as the control and cefazolin spiked (10 mg L-1), loaded into triplicate 1 L batch digesters and anaerobically digested at 37 °C and 55 °C for 22 days separately. Control and cefazolin spiked milk mixtures always produced significantly (p < 0.05) higher total and methane gas yields compared to the respective manure mixtures. Compared to the control in both digester types, no significant (p > 0.05) differences in total and methane gas yields were observed in the respective cefazolin spiked digesters despite the temperature at which the digestion was carried out. Volatile fatty acid (VFA) accumulation and reduction of pH were not observed in any digester of both substrates at both temperatures at the end of the experiment, which confirmed the process stability. However, further investigations are necessary to analyse the effects of increased concentrations of cefazolin in the substrates on digester stability.J.Natn.Sci.Foundation Sri Lanka 2015 43 (4):369-376 Published on 2016-01-01 10:15:42
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