Science
Permanent URI for this communityhttp://repository.kln.ac.lk/handle/123456789/1
Browse
Item 2-Tuple Fuzzy Linguistic Model to Evaluate the Risk of Invasive Plant Species(Department of Statistics & Computer Science, University of Kelaniya, Sri Lanka, 2016) Peiris, H.O.W.; Perera, S.S.N.; Chakraverty, S.; Ranwala, S.M.W.Management of invasive species can appear to be a complicated and unending task. In order to manage the spread, these species need to be undergone any risk assessment during their introduction. The aim of this study is to evaluate the aggregate risk of Invasive Alien Species (IAS) using invasive attributes. We use the 2-tuple fuzzy linguistic representation to develop the model without loss of information in which occur in ordinary linguistic operators. These risk values are compared with the National Risk assessment scores which are in the form of Linguistic labels. The proposed model is validated using few known noninvasive species in Sri Lanka. The model gives significant predictions and it is found to be a better tracking system for identifying potential invaders than the conventional risk assessment methods.Item The 3D atomic scale and electronic structure characterization of novel fcc ruthenium nanoparticles using synchrotron light source(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Kumara, L.S.R.; Sakata, O.; Kohara, S.; Song, C.; Yang, A.; Kusada, K.; Kobayashi, H.; Kitagawa, H.Ruthenium (Ru) is a 4d transition metal that in the bulk adopts hexagonal closepacked (hcp) structure at all temperature ranges, and novel face-centered cubic (fcc) Ru nanoparticles (NPs) have been observed to be more efficient than conventional hcp Ru NPs larger than 3 nm. It has recently attracted much attention as a potential application in removal of car exhausts due to high catalytic activity for CO oxidation and preventing CO poisoning in fuel-cell system. We here report the 3-dimentational atomic-scale structures of fcc and hcp Ru NPs using high-energy X-ray diffraction (HEXRD), Rietveld analysis, pair distribution function (PDF), and reverse Monte Carlo (RMC) modelling. Hard X-ray photoelectron spectroscopy (HAXPES) can provide important information on the influence of NP size on electronic properties. The HEXRD and HAXPES of Ru NPs were performed at BL04B2 and BL15XU at SPring-8, the world largest third-generation (8 GeV) synchrotron radiation facility located in Hyōgo prefecture, Japan. We observed higher stability of the lattice distortion of fcc Ru NPs with increasing particle size. The PDF analysis results show that the structural disordered Ru NPs at short- to intermediate-range atomic distances. The order parameter for fcc Ru NPs decreased with increasing particle size due to the loosely packing atomic arrangement and may explain an origin of higher catalytic activity of fcc Ru NPs. In this study, the observed trend of increasing catalytic activity of fcc Ru NPs was also discussed using their core-levels and valence band electronic structures. This work was partly supported by ACCEL, Japan Science and Technology Agency (JST) and also partly supported by Ministry of Education, Culture, Sports, Science and Technology of Japan (OS: 15K04616).Item 3D Imprint Lithography Using Sixny Molds(2002) Jayatissa, N.W.K.; Alkaisi, M.M.; Blaikie, R.J.Three-dimensional patterning reduces more complicated alignment steps in the fabrication of micro and nano-scale structures. Multiple lithography processes with interlevel alignment or single lithography with multi layer resist is essential for three dimensional patterning. A number of 3D structures have found immediate applications in a range of microelectronic systems such. as micro-optics, micro-electromechanical systems, and in monolithic microwave integrated circuits. We have previously demonstrated that imprint at low temperatures (well below the glass transition of the resist) is possible for a number of structures using silicon nitride (SixNy) molds. A low temperature process is important for pattering substrates or polymer-based materials that are intolerant of high temperatures. The advantages of using SixNy for mold making are the capability of forming reliable nanoscale structures and its surface properties that allows imprint without sticking. In this work we will present pattering results for three-dimensional structures using nanoimprint lithography with SixNy molds. The mold material consists of a 1?m thick low stress SixNy layer deposited by low-pressure chemical vapour deposition (LPCVD) on to a silicon substrate. Patterning of the SixNy was performed using electron beam lithography at 50keV into ma-N 24033 negative tone resist.Item A comparative assessment of the fisheries in lacustrine inland waters in three Asian countries based on catch and effort data(Fisheries Research, 1991) de Silva, S.S.; Moreau, J.; Amarasinghe, U.S.; Chookajorn, T.; Guerrero, R.D.The catch and effort data of the artisanal fisheries of the natural lakes and reservoirs in the Philippines, and reservoirs in Sri Lanka and Thailand are evaluated. The yield (kg ha?1 year?1) to effort relationship of the Philippines lakes and Thai reservoirs conformed to a second-order curve, and that of Sri Lankan reservoirs was linear. Similarly, the catch per unit effort (CPUE) to effort per unit area relationships for the Philippines and Thai fisheries were similar and conformed to the Fox model. The relationship of the mean annual yield (kg ha?1) to mean effort in the Sri Lankan reservoirs when considered as a whole, on a yearly basis, conformed to the Schaefer model. On the basis of these relationships the effort which gave the maximum yield per annum was computed for each fishery. The yields were 515, 256 and 93 kg ha?1 for efforts of 20, 6.4 and 10 fishermen for the fisheries of the Philippines, Sri Lanka and Thailand, respectively. An attempt is made to explain the reasons for the apparent differences in these three artisanal fisheries, and the importance of the models in the management of the respective fisheries are discussed. 1 Present address: Deakin University, Warrnambool Faculty of Applied Science and Environmental Technology, P.O. Box 423, Warrnambool 3280, Australia.Item A comparative chemosystematical study of the genus Shorea in Sri Lanka(Proceedings of the sixth Round Table Conference on Dipterocarps, Bangalore, India, 1999) Perera N I S; Senanayake S PThe genus Shorea of the Dipterocarpaceae family is represented by 15 species in Sri Lanka, of which 13 are endemic. Because of the existence of different classification systems for this genus, proposed by several authors (Trimen 1974, Ashton 1980, Kostermann 1992), the aim of this study was to determine the taxonomic position of the genus Shorea using flavonoid composition. Flavonoid composition of the leaves of 11 species was studied using chromatographic techniques and UV visible spectroscopy. It was revealed that 48% flavonols, 36% flavones, 63% proanthocyanidins and 13% deoxy compounds were present in the leaves. In this study, a comparison of the flavonoid glycoside distribution patterns of Shorea stipularis and S. hulanidda suggested that the two species should be treated as different entities. However, several authors treat the taxonomic positions of these two species differently.Item A Comparative Preliminary Study on the Prevalence of Overweight-Obese with Socio-Economic Status (SES) Among the Adult Females(1st International Conference on Unani, Ayurveda, Siddha and Traditional Medicine, On Natural Solutions for Health Challenges, 2013) Manuha, M.I.; Iqbal, N.Z.; Nageeb, B.M.; Paranagama, P.A.This study was to determine how the SES influenced on overweight and obesity in adult women. The analysis was done by ISBM SPSS. BMIwas categorized according to WHO criteria such as normal weight: 18.5-24.9 kg/m2; overweight: 25.0- 29.9 kg/m2; or obese > 30.0 kg/m2. Obese further categorized to obese-I (30-34.9 kg/m2), obese-II (35-39.9 kg/m2) and morbid obese ( > 40 kg/m2). 206 participants were participated. In this study 32.5% were overweight and 67.5% were obese. Out of this 67% of obese 43.2% were belong to obese I, 17.5% were belong to obese II and 6.8% were in the morbidly obese. 43.3%, 40.3% of overweight were found in the age group 31-40 and 41-60 respectively. Similarly 35.7%, 47.4% of obese were found in the similar age groups. 53.7% was overweight and 68.3% was obese found in the participants who completed or below level of primary education. Further in the participants who completed the secondary education or above, the percentage of overweight (31.4%) was found lesser amount than obesity (46.3%). Family income concerned both 33.3% overweight and 37.4% obese were found in less income family (LKR < 25000). 29.8% overweight and 31.7% obese were found in the families who received the income between LKR 25000 - 50000. Inthis study 71.8%, 22.3 %, 5.8% were house wives, employees and students respectively. Overweight/obese found more in the age groups between 31-60. Overweight/obese found higher percentage in poor educated group. This study indicates that with the increasing of the age the overweight condition is transforming into obese condition. Therefore a study on wide range of the population is needed to come to a conclusion.Item A comparative study of the effects of benzene, toluene and xylenes on their in vitro metabolism and drug metabolizing enzymes in rat liver(Toxicology and Applied Pharmacology, 1986) Pathiratne, A.; Puyear, R.L.; Brammer, J.D.Item A comparative study of the food and feeding habits of Puntius Bimaculatus and P.Titteya (Pisces, Cyprinidae)(brillonline.com, 1976) de Silva, S.S.; Kortmulder, K.; Wijeyaratne, M.J.S.Item A comparison of proximate composition and water stability of three selected Shrimp feeds used in Sri Lanka(Asian Fisheries Society, Manila Philippines, 2007) Epa, U.P.K.; Wijeyaratne, M.J.S.; de Silva, S.S.Item A Correlation between activation energy and light absorption of WO3 incorporated TiO2(2002) Dharmaratna, W.G.D.; Roshan, P.W.C.; Siripala, W.; Wijesundera, R.P.The variation of electrical conductivity properties and light absorption properties are studied in W 6+ incorporated Ti02, Both conductivity and light absorption depend on the percentage of W 6+ incorporated into the crystal matrix of Ti02. The activation energy decreased by a maximum of 30% as a result of doping and the lowest activation energy was measured when the dopant concentration was 0.2%. The light reflectance decrease with the dopant percentage, but not in a monotonically decreasing passion. The variation of light reflectance as a function of dopant concentration showed a minimum when the dopant concentration was 0.2%. Both features are quite important in improving the photocatalytic properties of Ti02.Item A Cu2O/TiO2 heterojunction thin film cathode for photoelectrocatalysis(Solar Energy Materials and Solar Cells, 2003) Siripala, W.; Ivanovskaya, A.; Jaramillo, T.F.; Baeck Sung-Hyeon; McFarland, E.W.A thin film heterojunction photocathode was developed consisting of 100nm of n-type titanium dioxide (TiO2) cathode surface deposited on p-type cuprous oxide (Cu2O). The cuprous oxide was deposited electrochemically on Ti foil. A photocurrent of 0.7mA/cm2(at -1V bias) and an open circuit photovoltage of 460mV were obtained under an illumination of 700W/m2. The photoresponse as a function of pH demonstrated that the TiO2 film protected the Cu2O underlayer against corrosion. These results suggest that using a simple and inexpensive heterostucture configuration, the corrosion limitations of Cu2O alone may be overcome while maintaining a relatively high efficiency for photoelectrolysis.Item A Determination of air pollution in Colombo and Kurunegala, Sri Lanka, using energy dispersive X-ray fluorescence spectrometry on Heterodermia speciosa(Scientific and Technological Research Council of Turkey (TÜBİTAK), 2011) Gunathilaka, P.A.D.H.N.; Ranundeniya, R.M.N.S.; Najim, M.M.M.; Seneviratne, S.Sri Lanka is facing severe environmental problems such as air and water pollution due to rapid industrialisation and urbanisation. Because there have not been many studies on heavy metal pollution in Sri Lanka, the present study attempts to contribute to the literature a determination of metal pollution using indicators found in lichen specimens. Our study utilised energy dispersive X-ray l uorescence spectrometry to determine element concentrations resulting from air pollution in the lichen species Heterodermia speciosa Wulfen. h ese samples, collected from Colombo and Kurunegala, Sri Lanka, were analysed using the energy dispersive X-ray l uorescence (EDXRF) method in order to determine the concentrations of 13 dif erent elements. A radioisotope excited X-ray l uorescence analysis was applied to the elemental analysis of lichens using the method of multiple standard addition. Our qualitative analysis of spectral peaks showed that the samples contained potassium, calcium, titanium, iron, manganese, copper, zinc, lead, bromine, rubidium, strontium, yttrium, and gallium. Samples from the environment around Colombo, which is a highly congested urban area with much industrial development, were found to be more polluted when compared with Kurunegala, a city that is less congested and without industries. Concentrations of K, Ca, Ti, and Fe were always higher than other elemental concentrations in the lichens we analysed, a fact attributed to the proximity to the sea or exposed earth crustal sources. From the elements reported from the 2 cities, K, Ca, Ti, Fe, Mn, Zn, and Pb were reported at concentrations higher than background levels. Levels of Pb and Zn in samples from Colombo were higher than those from Kurunegala, relecting the increased vehicular trai c. h is study reveals that the common lichen species Heterodermia speciosa can be used as an indicator lichen to analyse the pollution level and other elements in the atmosphere.Item A Fundamental Study of the Transport Properties of Aqueous Superacid Solutions(Journal of Physical Chemistry B, 2010) Suarez, S.N.; Jayakody, J.R.P.; Greenbaum, S.G.; Zawodzinski, T.; Fontanella, J.J.An extensive investigation of the transport properties of aqueous acid solutions was undertaken. The acids studied were trifluoromethanesulfonic (CF3SO3H), bis(trifluoromethanesulfonyl)imide [(CF3SO2)2NH], and para-toluenesulfonic (CH3C6H4SO3H), of which the first two are considered superacids. NMR measurements of self-diffusion coefficients (D), spin?lattice relaxation times (T1), and chemical shifts, in addition to ionic conductivity (?), viscosity (?), and density measurements, were performed at 30 �C over the concentration range of 2?112 water to acid molecules. Results showed broad maxima in ? for all three acids in the concentration range of 12?20 water to acid molecules. This coincided with minima in anion Ds and is attributed to a local molecular ordering, reduced solution dielectric permittivity, and increased ionic interactions. The location of the maxima in ? correlates with what is observed for hydrated sulfonated perfluoropolymers such as Nafion, which gives a maximum in ionic transport when the ratio of water to acid molecules is about 15?20. Of the three acids, bis(trifluoromethanesulfonyl)imide was found to be the least dependent on hydration level. The occurrence of the anticorrelation between the ionic conductivity maximum and the anion self-diffusion minimum supports excess proton mobility in this region and may offer additional information on the strength of hydrogen bonding in aqueous media as well as on the role of high acid concentration in the Grotthuss proton transport mechanism.Item A Home Made Double Slab Pyranometer for Irradiance Measurements(Proceedings of the 44th Technical Session of the Sri Lanka Association for the Advancement of Science (SLAAS), 1988) Punyasena, M.A.; Jayasuriya, K.D.Item A methodology for identifying ?Web metrics? for ?Web analytics?(2006) Wickramarachchi A P R; Malavisooriya L MThe need for perusing sound business practices when adopting an organizational web strategy is highlighted by many authors. Measuring effectiveness of business activities is a standard practice of any organization. However, few organizations actively take steps to assess successfulness of their web strategy. The main reason for this is due to the lack of a standard approach to measure the effectiveness of web sites. Many authors have come up with different types of metrics (measurements) for measuring the effectiveness of web sites. Two common approaches identified are; user centric measurements which depend on consumer surveys and site centric measurements which depend on server logs. The latter approach is preferred by many organizations Software tools have also been developed for collecting and analyzing results from web metrics. But still Organizations are faced with problems of identifying appropriate metrics for their web site. Different sections of a web site have different functions and objectives. Therefore different metrics are needed to measure the effectiveness of different sections of a web site. Thus a formal methodology for identifying suitable web metrics for a particular web site is invaluable for measuring the effectiveness of web sites. The research proposes a methodology for identifying appropriate web metrics for measuring the effectiveness of a web site; based on the objectives and functionalities of the web site. A set of metrics have been identified by combining the findings of previous researches which are evaluated through expert opinions. These metrics are the input for methodology development where a step wise approach is proposed to identify appropriate web metrics based on the functions of a particular web site.Item A Mössbauer effect study of barium ferrite ball-milled in air(Hyperfine Interactions, 1994) Jayasuriya, K.D.; Kaczmarek, W.A.; Wu, E.; Campbell, S.J.The effects of dry-milling BaFe12O19 in air for periods of 190, 360, 590, 690 and 1000 h have been investigated by X-ray diffraction and M�ssbauer effect measurements. The sizes of the BaFe12O19 particles decrease on milling, as expected, although a partial decomposition of BaFe12O19 to ?-Fe2O3 is found to take place on extended milling (1000 h). The room temperature M�ssbauer spectra are consistent with superparamagnetic relaxation associated with the fine BaFe12O19 and ?-Fe2O3 particles. The X-ray diffraction patterns of all the milled samples exhibit features indicative of a disordered structural state, consistent with the nanoscale particles and a nanostructured state.Item A Mössbauer study of ball-milled Co?Fe?Si?B: I: dry milling(Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1993) Jayasuriya, K.D.; Campbell, S.J.; Calka, A.; Jing, J.X-ray diffraction and M�ssbauer effect measurements of ball-milled Co?Fe?Si?B material which had first been re-crystallized from amorphous melt-spun ribbon are presented. Fully amorphous powders have been obtained after only 50 h milling with a ball-to-powder ratio of BPR ? 84. The amorphous powders exhibit chemical and structural inhomogeneities compared with the starting melt-spun amorphous ribbons.Item A Mössbauer study of ball-milled Co?Fe?Si?B: II: with surfactants(Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1993) Jayasuriya, K.D.; Campbell, S.J.; Calka, A.; Jing, J.The use of a range of organic surface active substances in the ball milling of Co?Fe?Si?B has been studied by X-ray diffraction and M�ssbauer effect measurements. Effects characteristic of superparamagnetic relaxation of the magnetic moments are observed in the M�ssbauer spectra of samples milled with either an anionic or a cationic surfactant. This behaviour is linked with the decreased particle size and high shape homogeneity of surfactant-aided milled samples compared with the amorphous powders resulting from standard dry milling. Impurity iron-oxide phases are also found to occur in samples milled in the presence of surfactants.Item A Mössbauer study of the oxidation state of Fe in silicate melts(American Mineralogist, 2004) Jayasuriya, K.D.; O-Neill, H.S.C.; Berry, A.J.; Campbell, S.J.Fe3+/?Fe ratios were determined from M�ssbauer spectra recorded for a series of 17 anorthite-diopside eutectic glasses containing 1 wt% 57Fe2O3 quenched from melts equilibrated over a range of oxygen fugacities from fO2~ 105 bars (Fe3+/?Fe = 1) to 10?13 bars (Fe3+/?Fe = 0) at 1682 K. Fe3+/Fe2+ was found to be proportional to fO2 to the power of 0.245 � 0.004, in excellent agreement with the theoretical value of 0.25 expected from the stoichiometry of the reaction Fe2+O + 0.25 O2 = Fe3+O1.5. The uncertainty in the Fe3+/?Fe ratios determined by M�ssbauer spectroscopy was estimated as � 0.01 (1?) from the fit of the data to the theoretical expression, which is significantly less than that quoted for previous measurements on silicate glasses; this results from fitting the spectra of a large number of systematically varying samples, which allows many of the ambiguities associated with the fitting procedure to be minimized. Fe3+/?Fe ratios were then determined for samples of the anorthite-diopside eutectic composition equilibrated at selected values of fO2, to which up to 30 wt% Fe2O3 had been added. Fe3+/?Fe was found to vary with ?Fe (or FeOT), but both the 1 wt% and high FeOT data could be satisfactorily fit assuming the ideal stoichiometry (i.e., Fe3+/Fe2+ ?fO2 1/4) by the inclusion of a Margules term describing Fe2+-Fe3+ interactions. The large negative value of this term indicates a tendency toward the formation of Fe2+-Fe3+ complexes in the melt. The resulting expression, using the ideal exponent of 0.25, gave a fit to 289 Fe3+/?Fe values, compiled from various literature sources, of similar quality as previous empirical models which found an exponent of ~0.20. Although the empirical models reproduce Fe3+/?Fe values of glasses with high FeOT reasonably well, they describe the data for 1 wt% FeOT poorly. The non-ideal values of the exponent describing the dependence of Fe3+/?Fe on fO2 at high FeOT are an artifact of models that did not include a term explicitly to describe the Fe2+-Fe3+ interactions. An alternative model in which Fe in the silicate melt is described in terms of three species, Fe2+O, Fe3+O1.5, and the non-integral valence species Fe2.6+O1.3, was also tested with promising results. However, at present there is no model that fits the data within the assessed accuracy of the experimental measurements.Item A multinuclear NMR study of ion transport in P(EO)nLiBETI complexes(Solid State Ionics, 2005) Suarez, S.N.; Abbrent, S.; Jayakody, J.R.P.; Greenbaum, S.G.; Shin, J.H.; Passerini, S.A study of ion transport in P(EO)nLiBETI complexes was undertaken, using both AC impedance and nuclear magnetic resonance (NMR) spectroscopy. 1H, 7Li and 19F NMR techniques were used to investigate structure and dynamics as a function of temperature for n=3, 6, 8, 12 and 20. Spin?lattice relaxation times (T1) and spectral information were obtained from ?50 to 100 �C. Variable temperature self-diffusion coefficients (D) and ionic conductivity (?) measurements were also performed. Anion diffusion (DF) results displayed a dependence on available free volume, increasing with decreasing salt concentration. On the other hand, cation diffusion (DLi) results did not follow this trend. DLi for n=3 and 6 suggest the presence of ionic mobility in the crystalline phase, with a significant rise above the melting point. A transition from a crystalline to amorphous phase dominated ion transport occurs at n=8. This is supported by ? results, which exhibited a VTF type of behavior for n?8 that is associated with ion transport in the amorphous phase.