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Journal of the National Science Foundation of Sri Lanka
   [3 followers]  Follow    
  This is an Open Access Journal Open Access journal
     ISSN (Print) 1391-4588
     Published by Sri Lanka Journals Online Homepage  [41 journals]   [SJR: 0.144]   [H-I: 4]
  • First Report of white root disease of Artocarpus nobilis in Sri Lanka
           caused by Rigidoporus microporus

    • Authors: HKI Madushani, THPS Fernando, RLC Wijesundara, D Siriwardane
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 197-198    
      PubDate: 2014-06-10
      Issue No: Vol. 42 (2014)
  • Density functional theory (DFT) and time - dependent density functional
           theory (TDDFT) studies of selected ancient colourants as sensitizers in
           dye-sensitized solar cells

    • Authors: Muhammad Raziq Rahimi Kooh, Voo Nyuk Yoong, Piyasiri Ekanayake
      Abstract: Ancient dyes such as brazilin, brazilein, haematoxylin and haematein have wide applications such as dyestuff, microscopy stains, and also as traditional and modern medicines. However these dyes have not yet been explored as sensitizers in dye sensitized solar cells. In the present work theoretical studies of these dyes have been performed using concepts such as density functional theory and time-dependent density functional theory, with Gaussian’09W software at B3LYP/6-31g(d) level. All the calculations are with the inclusion of geometric optimization and solvation effect of ethanol. Various energy levels of the dyes, electron cloud density, dominant energy transition states, optical properties and deprotonation order (proton affinity) of the dyes were obtained. This information was helpful to evaluate the feasibility of the dyes in dye sensitized solar cell (DSSC) applications. The dominant energy transition state of all dyes was found to be HOMO → LUMO at the first excitation state. For all four dyes electron clouds at the lowest unoccupied molecular orbital (LUMO) level were found to be localized near or at the most probable hydroxyl group that may anchor to the semiconductor. Among the four dyes, brazilein and haematein displayed excellent optical properties (λ max, oscillator strength, absorption band at visible spectrum) exhibiting their potential in DSSC application.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 169-175  
      PubDate: 2014-06-10
      Issue No: Vol. 42 (2014)
  • Macrophage migration inhibitory factor (MIF) in seminal fluid as a marker
           of male factor infertility: a pilot study in Sri Lankan men

    • Authors: Maheshi P Obeysekera, Dulshara S Amarasekara, Sumedha Wijerathna, Chandrika Fernando, Preethi V Udagama
      Abstract: Recent clinical and epidemiological studies worldwide suggest an increasing incidence of male factor infertility (MFI). Paucity of information on the biochemical analysis of seminal fluid in Sri Lanka prompted undertaking a pilot study to establish a clinical marker for the male fertility status in Sri Lanka based on the level of the cytokine, macrophage migration inhibitory factor (MIF) in seminal fluid, an area hitherto unexplored locally. The analysis was carried out on the semen samples of infertile males (N = 61) where age matched individuals (N = 30) with proven past paternity served as controls. D-dopachrome tautomerase assay was performed to assess the MIF level in semen while other seminal fluid parameters were assessed according to the standard WHO criteria. The present study revealed an abnormal biphasic profile of MIF in the seminal fluid of individuals with impaired sperm parameters, which was either significantly below or above the range of MIF tautomarase activity typical of normal fertile men (p < 0.000). This is the first report in a Sri Lankan population. The receiver operating characteristic (ROC) plot analysis established a cutoff point of 3.375 μg MIF/mL of semen (at 90 % sensitivity: 81.2 % specificity; 0.923 accuracy) to differentiate fertile from infertile males (excluding azoospermics and severe oligozoospermics). The MIF concentrations significantly correlated with the semen pH in the azoospermic and severe oligozoospermic group. As MIF was clearly indicative of the male fertility status by estimates of sensitivity and specificity of the D-dopachrome tautomerase assay, MIF may be developed as a potential marker of male infertility in Sri Lanka.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 149-154
      PubDate: 2014-06-10
      Issue No: Vol. 42 (2014)
  • Performance variation of Li rechargeable cells having polypyrrole cathodes
           doped with different anions

    • Authors: KP Vidanapathirana, Kumudu Perera
      Abstract: Electrochemically synthesized polymers such as polypyrrole (PPy), polyaniline (PANI) and polyNmethyl pyrrole (PNMP) are considered as one of the most promising polymer electrode material groups for the development of advanced electrochemical devices such as electrochemical cells, super capacitors, electrochromic devices and solar cells. The properties of electrochemically synthesized polymers are known to be largely dependent on the dopant anion used and hence, their performance in applications also depend greatly upon the dopants. In this study, the role of the anion used to dope the PPy cathode on the performance of a lithium (Li) rechargeable cell is reported. Anions were varied from small inorganic anions (CF3SO3 -) to large anions (alkilsulphonate, AS- and dodeclybenzenesulphonate, DBS-). PPy was electropolymerized and the cells were fabricated with a polyacrylonitrile (PAN) based solid polymer electrolyte (SPE) while Li served as the anode. Cyclic voltammetry and continuous charge discharge tests were carried out to characterize the cells. The cycling results showed better cycling charge and long cycle life with the cells fabricated with PPy doped with large anions. The cells with large anions showed higher cycle numbers while the cells with inorganic anions could not be cycled over 350 cycles. Even with electrodes having larger anions, better results can be obtained with slow scan rates. Scanning electron microscopy (SEM) studies revealed that electrodes have a porous morphology with smaller anions and a dense morphology with larger anions, which also affect the performance variations.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 143-147
      PubDate: 2014-06-10
      Issue No: Vol. 42 (2014)
  • Hypoglycaemic effect of the methanolic extract of Aporusa lindleyana
           leaves on rats

    • Authors: BLC Samanmali, Mangala Gunatilake, Ranil D Guneratne, TRK Perera
      Abstract: Aporusa lindleyana is a medicinal plant, which is claimed to have a hypoglycaemic potential. This study was carried out to determine the hypoglycaemic effect, toxicity of long term usage and the phytochemistry of tender leaves of A. lindleyana. The hypoglycaemic effect of the methanolic leaf extract of A. lindleyana on the fasting and random blood glucose concentrations and the glucose tolerance were tested using three oral doses of the extract (100, 400, 800 mg/kg) in Sprague-Dawley rats. Sub-acute toxicity studies were performed after treating the rats for 28 consecutive days with the highest dose and were tested for different parameters. The results exhibit a dose dependent hypoglycaemic effect with the maximum blood glucose reduction observed at the 4th hour after the treatment. All three tested doses significantly reduced the fasting blood glucose concentration 4 hours after treatment. Only the intermediate and the highest doses showed a significant reduction in random blood glucose concentration in normoglycaemic non-fasted rats and a significant glucose tolerance, when tested on an oral glucose load. There was no significant difference in the physical and biochemical parameters in rats treated with the extract for 28 days compared to the control group. The extract contained alkaloids, saponins, flavonoids and leucoanthocyanins as revealed by phytochemical screening. It can be concluded that A. lindleyana leaves exhibit hypoglycaemic activity since they significantly (p < 0.05) reduce the blood glucose concentration in normoglycaemic rats and significantly (p < 0.05) enhances the glucose tolerance. The long term use of the leaf extract does not produce any toxic signs in rats.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 129-135  
      PubDate: 2014-06-10
      Issue No: Vol. 42 (2014)
  • Enzyme inhibitory and immunomodulatory activities of the depsidone lobaric
           acid extracted from the lichen Heterodermia sp.

    • Authors: Vinitha M Thadhani, Qamar Naaz, M Iqbal Choudhary, M Ahmed Mesaik, Veranja Karunaratne
      Abstract: This study evaluates the enzyme inhibitory and immunomodulatory activities of the lichen specific depsidone, lobaric acid. Lobaric acid was extracted with methanol from Heterodermia sp. found in Labukelle, Sri Lanka with a yield of 0.67 %. It was subjected to enzyme inhibition assays using acetyl and butyryl-cholinesterase, phosphodiesterase, β-glucuronidase, α-glucosidase and urease. In the β - glucuronidase inhibitory activity it showed an IC50 value of 3.28 ± 0.05 μM, which was significantly lower than that of the standard, D-saccharic acid 1, 4-lactone (IC50 = 48.4 ± 1.2 μM). Lobaric acid showed a significant inhibition of phosphodiesterase enzyme with an IC50 = 313.7 ± 2.2, when compared with the two standards EDTA (IC50 = 274.0 ± 0.1 μM) and cysteine (IC50 = 748.0 ± 0.1 μM). Lobaric acid showed a moderate actyl and butyryl -cholinesterase inhibitory activity while it showed no activity against the enzymes α-glucosidase and urease. In the immunomodulatory assay, lobaric acid exhibited a potent oxidative burst inhibitory activity in human polymorphonuclear (PMN) cells. It suppressed both the myloperozidase dependant and myloperozidase independent reactive oxygen species (ROS) production of PMNs. The results indicate the pharmacological potential of lobaric acid as a lead compound for further studies.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 193-196  
      PubDate: 2014-06-09
      Issue No: Vol. 42 (2014)
  • Performances of data mining techniques in forecasting stock index –
           evidence from India and US

    • Authors: B Senthil Arasu, M Jeevananthan, N Thamaraiselvan, B Janarthanan
      Abstract: Forecasting the stock market is a challenging task because of its stochastic and complex nature. Various statistical models and data mining techniques have been developed in the recent years and applied to stock market forecasting. A review of the relevant literature shows that only a very few studies have applied high frequency data to forecast the stock market and among these studies, only one or two have applied data mining techniques. There are no studies on forecasting high frequency data of stock index using multivariate adaptive regression splines. In this paper we study the applicability of the following four data mining techniques: backpropagation neural network (BPNN), support vector regression (SVR), multivariate adaptive regression splines (MARS) and Markov chain incorporated into fuzzy stochastic (MF), for one-stepahead forecast of S&P CNX Nifty index of India and Nasdaq composite index of USA with every sixtieth minute data. The results of the study shows that SVR is better than the others for forecasting high frequency data of both indices with an accuracy of 99.7 %.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 177-191  
      PubDate: 2014-06-09
      Issue No: Vol. 42 (2014)
  • Karyomorphological studies of Aponogeton appendiculatus Bruggen and
           Aponogeton crispus Thunb.

    • Authors: SP Gaikwad, SR Yadav, RD Gore, KU Garad
      Abstract: The study focused on the correct taxonomic identification and the determination of somatic chromosome numbers of Aponogeton appendiculatus Bruggen and Aponogeton crispus Thunb. A somatic chromosome number of 2n = 30 and 2n = 32 was observed in A. appendiculatus and A. crispus, respectively. The chromosomes of both species were short with median to submedian primary constriction. The karyotypes were reasonably symmetrical, indicating the primitiveness of the family in general.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 163-167  
      PubDate: 2014-06-09
      Issue No: Vol. 42 (2014)
  • Trajectory planning for multi-input-multi-output linear systems subject to
           nonlinear inequality constraints on the output

    • Authors: R Palamakumbura, CF Martin
      Abstract: Trajectory planning is an imperative aspect in aviation, robotic manipulation, navigation of mobile robots, and unmanned arial and underwater vehicles. A popular approach to trajectory planning is to formulate it in the setting of a constrained optimization problem. In this approach the cost of control is minimized subject to path constraints specified by nonlinear inequality constraints on the output trajectory at predefined time instances. This problem was first solved for the case of single-input-multi-output linear systems. In the present study the results have been extended to the more general multiinput- multi-output linear systems. The convex nature of the resulting optimization problem ensures a unique solution. A methodology based on the Lagrange multiplier technique is used for the computation of the unique solution. An explicit solution for the optimal output trajectory as well as the controller that will ensure the real time generation of the solution are derived in terms of the solution to the nonlinear equations. An example ubiquitous in the field of nonholonomic mobile robots is used to illustrate the results derived.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 155-161
      PubDate: 2014-06-09
      Issue No: Vol. 42 (2014)
  • Releasing thyroid cancer patients from the hospital based on dose rate
           measurement after 131I activity administration

    • Authors: R Hewamanna, Naalini Loganathan, DKA Perera
      Abstract: The treatment of thyroid cancer generally comprises total thyroidectomy and oral administration of radioiodine (131I). One consideration in this therapy is the radiation exposure risks, which have led the Sri Lankan Regulatory Authority to lay down criteria on releasing patients from hospitals when the therapy procedure involves 131I activities greater than 1.85 GBq (50 mCi). This study was carried out to assess the time dependent dose rate following the administration of 131I activities and estimate the radioiodine effective half-life (Teff) inside the patient’s body, which would be useful for releasing patients from hospitals and guide radiation protection recommendations as well. External whole body dose rates at 1.0 m from 60 patients were measured immediately after 131I administration and at 24 hour intervals up to 5 days. These dose rates were used to estimate the Teff . The results demonstrated a bi-exponential radioiodine clearance pattern up to 5 days with Teff values of 15.9 and 25.3 hours in the first and second phase, respectively. Also, majority of the patients could be released from the hospital after 72 hours post-therapy administration as they reach the permissible dose rate limit recommended by the regulatory authority of Sri Lanka by this time.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 137-141  
      PubDate: 2014-06-09
      Issue No: Vol. 42 (2014)
  • Adaptation to the vulnerability of paddy cultivation to climate change
           based on seasonal rainfall characteristics

    • Authors: RD Chithranayana, BVR Punyawardena
      Abstract: This study was aimed at identifying adaptation measures to the vulnerability of paddy cultivation in the Dry and Intermediate Zones of Sri Lanka, based on rainfall. The spatial distribution of the onset time of rains, the length of the Yala and the Maha seasons and the number of dry weeks within seasons were determined using weekly rainfall data from 36 rainfall stations in the Dry and Intermediate Zones. Based on the seasonal rainfall characteristics, the cropping calendars for rice crops for each agro-ecological region (AER) were prepared. This study discloses a high spatial variability of the onset time of both the Yala and Maha seasons. Many AERs in the Dry Zone and some AERs in the Intermediate Zone do not have a distinct Yala season. The Yala rains in the Dry Zone are highly variable and the most probable length of the season may not exceed four weeks from the onset time. During the Maha season, there is enough rain water for paddy cultivation. The proposed cropping calendars can be used as a tool in farming activities from the land preparation to harvesting. Such information could assist to reduce the amount of irrigation water required and the frequency of water issued from the tanks in the respective regions without a wide margin of errors. It can also be used as a decision support tool in planning rainfed upland agricultural systems as well. The identification of dry periods within a season is necessary for the farmers to be aware and adapt to recent advanced technologies to reduce the water use for rice cultivation. Periodical checking and revision of the cropping calendars with future climate predictions are recommended.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 119-127  
      PubDate: 2014-06-09
      Issue No: Vol. 42 (2014)
  • Pre-harvest chemical elicitor treatment enhances induced resistance in
           harvested banana fruit cv. ‘Embul’ and reduces anthracnose
           caused by Colletotrichum musae

    • Authors: UWNP Wanigasekara, NKB Adikaram, CL Abayasekara
      Abstract: Developing banana fruits cv. ‘Embul’ were treated in the field with chemical elicitors, Bion®, salicylic acid (SA) or K2HPO4 at two stages, 2 and 4 or 9 and 11 weeks after bunch emergence. Fruits harvested 14 – 15 weeks after bunch emergence were inoculated with Colletotrichum musae, and the development of anthracnose was assessed during ripening. Treatment with Bion® or SA at 9 and 11 weeks after bunch emergence while delaying the disease incidence significantly reduced (p < 0.05) the severity of the disease by 43 % and 65 %, respectively compared to the control. SA (500 mg/L) treatment was 22 % more effective than Bion® (200 mg/L) while the treatment with K2HPO4 (20 mg/L) increased the disease severity by 5 %. Bion® or SA-treated fruits when challenge inoculated with C. musae after harvest showed a significantly enhanced chitinase activity (p < 0.05). There was also an increased β–1,3–glucanase activity and antifungal activity of the fruit peel compared to the controls. The elicitor treatment did not affect the fruit weight or postharvest quality.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 101-110  
      PubDate: 2014-06-09
      Issue No: Vol. 42 (2014)
  • Enhanced production of ethanol by high gravity glucose fermentation at
           temperatures above 40 oC by Saccharomyces cerevisiae S1 using a soya flour
           supplemented medium

    • Authors: Sandrasegarampillai Balakumar, Vasanthy Arasaratnam
      Abstract: A locally isolated strain of Saccharomyces cerevisiae S1 in peptone, yeast and mineral nutrient (PYN) medium with 100 gL-1 of glucose showed optimum growth at 36 oC and efficient ethanol production at 40 oC. To investigate the effect of soya flour supplementation on ethanol fermentation, PYN medium containing different concentrations of glucose (50 to 400 gL-1) with and without soya flour (26.8 gl-1) were used at 40 ºC for 48 h. The above experiment was repeated at different temperatures (40, 43 and 45 ºC) for 48 h to find the effect of soya flour supplementation on ethanol production at higher temperatures and sugar levels. The highest ethanol production efficiency (96.5 %) and the highest ethanol yield (149.3 gL-1) with efficient glucose utilization (100 %) was observed in soya flour supplemented medium with a sugar concentration of 300 gL-1 at 40 ºC. Further, it was observed that at higher temperatures (43 and 45 ºC) and higher sugar concentrations, soya flour supplemented media performed well. With 300 gL-1 glucose at 43 and 45 oC the amounts of ethanol produced in soya flour supplemented media was 80 and 30 gl-1, respectively while in unsupplemented media it was only 28 and 18 gL-1, respectively. In glucose (400 gl-1) – PYN medium supplemented with soya flour, 78 (48 h) and 25 gl-1 (48 h) ethanol was produced at 43 and 45°C, respectively. The study revealed that supplementation of media with soya flour has not only improved the glucose fermenting capacity but has also increased the efficiency of ethanol production and the ethanol production rate at higher temperatures and high sugar levels.
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 111-117
      PubDate: 2014-06-09
      Issue No: Vol. 42 (2014)
  • Solar cell development research: a Sri Lankan perspective

    • Authors: Withana P Siripala
      DOI : J.Natn.Sci.Foundation Sri Lanka 2014 42 (2): 99-100

      PubDate: 2014-06-09
      Issue No: Vol. 42 (2014)
School of Mathematical and Computer Sciences
Heriot-Watt University
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