Showing papers in "Vidyodaya Journal of Science in 2016"

Towards a Steady State Economy in Sri Lanka

Abstract: In general, it is desired that Sri Lankan economy shows growth. A growing economy brings waste production which leads environmental pollutions such as air pollution water pollution etc. At present, increasing population in Sri Lanka requires more natural resources to meet the market demand. The ultimate result is an imbalance in the biological cycles, and an irreversible change in both economic process and environment. An irreversible economic process increases entropy. Ultimately, the entropy will reach its maximum value. Then everything will become standstill since there would not exist more energy to continue the economic process. As a solution, the concept of a steady state economy is structured.Sri Lankan economy was assessed within steady state economics to evaluate the present economic situation of Sri Lanka. A statistical analysis was carried out on Gross Domestic Product (GDP), population, energy use, CO2 emission through time series analysis and regression analysis,to identify the extent to which Sri Lankan economy has deviated from a steady state economy. Regression analysis indicates a strong relationship between GDP and CO2 emission. Total population size in Sri Lanka is increased from 9.9 million in 1960 to 20.48 million in 2013. CO2 emission per capita is increased from 0.25 metric tons in 1960 to 0.65 metric tons in 2010. CO2 emission is increased from 2259 kiloton in 1960 to 12831 kiloton in 2010. Rapid growth rates, CO2 emissions, population growth rates reveal that Sri Lankan economy is far apart from the concept of steady state.Transition to a steady state economy would require the implementation of new policies to restrict the utilization of nonrenewable resources. On the other hand it is mandatory to have legal regulations encouraging renewable resource use, energy efficiency, and reuse and recycling.

Antifungal activity of secondary metabolites present in Psidium guajava leaves against dermatophytes

Abstract: Dermatophytes are a group of fungi that commonly cause skin diseases in animals and humans. Psidium guajava is a fruit tree with high medicinal value commonly used to cure various skin ailments. Methanol leaf extract of Psidium guajava was used to screen for the antifungal activity against five species of dermatophytes; Epidermophyton floccosum, Trichophyton rubrum, T. mentagrophytes, Microsporum gypseum and M. canis . The antifungal activity of the extract was tested using the agar well diffusion method from which the methanol crude extract revealed the highest antifungal activity exhibiting 22.5 mm against E. floccosum . Preliminary analysis of secondary metabolites was performed for the methanol crude extract which revealed the presence of many bio-active compounds including saponins, steroids and alkaloids. It was then subjected to fractionation and hexane, chloroform, ethyl acetate and aqueous fractions were obtained. Ethyl acetate fraction exhibited the highest antifungal activity against the test organisms recording 27.13 mm against M. canis . The secondary metabolites present in this chosen fraction were separated using thin layer chromatography (TLC) followed by the detection under UV light (365 nm and 254 nm). Contact bioautography was performed against the tested dermatophyte species using the detected spots from UV to determine the growth inhibitory activities. The secondary metabolites that were separated by TLC were identified using specific spray reagents which revealed the presence of alkaloids, steroids and flavonoids. Thus, P. guajava possesses different types of secondary metabolites which are effective antifungal compounds against dermatophytes.

Distribution of the vibration effect within the stacked boxes during vehicular road transportation of tomatoes

Abstract: Parameters of the Road-Vehicle-Load system influence the vibration effects generated at vehicular road transportation. Vertical vibration acceleration (PSDmax) experienced by the tomato boxes and tomatoes within the box was studied using the popular transport means in Illukkumbura area in Matale. The road quality was estimated using the International Road Roughness Index (IRI). Fully loaded Mitsubishi Canter truck at an average speed of 20 kmh-1 on a road rated at IRI between 2 to 3.5 mm/m registered increasing trend in the PSD of vibration from the front side towards the rear side of the truck in the horizontal direction. The observed average PSD values are in the approximate ratio, front : middle : rear ≈ 1 : 3: 6. Also the PSD of the vibration was found to be amplified from the bottom stack towards the topmost stack in the vertical direction. The observed average PSD values at 1st, 2nd, 3rd, and 4th stacks are in the approximate ratio, 1 : 1 : 1.5 : 2.5. PSD of vibration was studied with a fully loaded truck at different speeds on a road consisting of segments rated at varying IRI. The fully loaded truck at different speeds on a road consisting of segments rated at varying IRI registered varying PSD values of vibration. Even at lower speeds such as 25 kmh-1 the vibration acceleration produced at “poor” quality (IRI > 5 mm/m) roads was nearly 4 times higher compared to that produced at “fair” (IRI 2 to 3.5 mm/m) or “good” quality (IRI 0.9 to 2 mm/m) roads. Registered pattern of the PSD appears to be similar at the tomato boxes and at the tomatoes within the same box.

Nucleotide Sequence and Secondary Structure Variations in ITS2-rDNA Region of the Members of Anopheles culicifacies (Diptera: Culicidae) Species Complex

Abstract: Anopheles culicifacies, major vector of malaria in Sri Lanka is a five member species complex. Differences of the vector competence of siblings, is still poorly delineated. Therefore, the current study was carried out to observe any relationship of the variations in vector competence to ITS2 nucleotide sequences and secondary structure characteristics of the species complex. DNA was extracted from sibling species B and E, the ITS2 region was amplified and sequenced. Sequences for A, C and D siblings were retrieved from NCBI GenBank. The complex divided into two groups, AD and BCE based on primary and secondary structure of the ITS2 sequences. Secondary structures of all species had three helices where pyrimidine-pyrimidine mismatch in Helix II and a UUUGG motif at 5‘ of Helix III were displayed only for B, C and E. Among five types of loops, interior and exterior loops were more conserved than other loop types. Results showed the major vector sibling E and poor or non vector sibling B shares identical nucleotide sequence and secondary structure. Therefore, ITS2 secondary structure is independent of the vector competence of the sibling species.

Utilization of Ruta graveolens and Azadirachta indica leaf powders and their binary combinations for the management of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) in stored maize in Sri Lanka

Abstract: Maize weevil (Sitophilus zeamais, Motsch.) is a ubiquitous and cosmopolitan field-to-store pest of maize of economic importance in tropical and subtropical regions of the world. The current renewed interest to replace synthetic insecticides has served as the impetus for the evaluation and intensification of eco-friendly anti-weevil measures such as the use of plant based bio-insecticides. This study was therefore, designed to investigate the insecticidal and repellent potency of leaf powders of Ruta graveolens and Azadirachta indica in single treatments and combinations of various proportions under ambient laboratory conditions against Sitophilus zeamais in both contact and vapour forms. For both plants, 100 g each of maize grains were mixed with leaf powders at different doses of 1.0, 3.0, 5.0, 7.0 and 10.0 g. The bio-potential of three combinations of 1:1, 1:2 and 2:1 of R. graveolens and A. indica leaf powders incorporating into the dosage level of 10.0g was also evaluated. Maize grains treated with R. graveolens leaf powder caused 100 % contact and 68 % fumigation mortalities within 24 hours of exposure whilst repelling 97 % and 96 % weevils within an hour in both contact and vapour forms respectively. A. indica powder was less efficacious compared to that of R. graveolens causing significantly lower repellency within an hour and mortalities after 10 days of storage. Application of 2:1 combination of R. graveolens and A. indica produced respective levels of 100 % and 73% contact and fumigation mortalities within 24 hours and highly significant repellent effects on S. zeamais, offering greater potential for large-scale storage since such combinations are relatively cheaper than using either of the botanicals singly. Leaf powders of the two plants under present investigation revealed their improved grain protecting capacity when used individually and in mixtures as bio-rational leads in large-scale protection of stored maize.

Novel member of Ras family proteins from Disk Abalone (Haliotis discus discus): Structural profiling and its transcriptional modulation under host pathologic conditions

Abstract: Among small GTPases, the Ras family proteins capture a remarkable place in dictating cellular proliferation, differentiation and survival in development of an organism. Major members of the Ras family include Ras (H-Ras, K-Ras, N-Ras), Rap1, and Rap2, all of which can act as oncogenes upon mutation. In the present study, a novel Ras family protein (AbRFP) was characterized from Disk Abalone (Haliotis discus discus), an economically important, edible marine gastropod; further analyzing its transcriptional profile in healthy and immune-challenged animals. The full-length cDNA of AbRFP is 2704 bp and it consists of an open reading frame of 552 bp, encoding a 184 amino acid peptide with a calculated molecular mass of ~21 kDa and isoelectric point of 8.63. The amino acid sequence resembles the characteristic features of typical Ras family proteins, including GTP/Mg2+ binding sites and guanine nucleotide exchange factor (GEF) interaction sites, as predicted by the NCBI-conserved domain database server. Phylogenetic study of AbRFP showed the generally accepted relationships, with AbRFP exhibiting highest proximity to a Ras protein from Portuguese oyster. Quantitative real-time PCR detected ubiquitous AbRFP mRNA expression, with strongest levels in muscle along with mantle and the lowest level in hepatopancreas. The AbRFP transcriptional profile in gills of Abalone challenged with Vibrio parahaemolyticus or viral hemorrhagic septicemia virus (VHSV) demonstrated significant up-regulations (p < 0.05) at 12 h and 24 h post-injection (p.i.), respectively. Moreover, significant elevation (p < 0.05) of mRNA expression was detected in hemocytes at 72 h p.i. with V. parahaemolyticus. These findings suggest that AbRFP may play a role under pathological conditions in Disk Abalone

Android Application: Sound Pressure Level Meter and Frequency Spectrum Analyzer

Abstract: In this paper we present the development of Sound Pressure Level Meter and Frequency Spectrum Analyzer application for Android based devices. The developed application can visualize real time waveform and frequency spectrum of an input audio signal in both linear and dB scale. The GPS location, current date and time are also embedded to the application for convenience. A comparison was carried out with currently available smartphone apps of similar type and the results are in good agreement with the app developed in this project. The current version of the app is capable of capturing signal of maximum frequency up to 4000Hz. Therefore, analysis of frequency spectrum of the voice transmission which range between 300Hz to 3400Hz can be carried out successfully.

Diversity and abundance of Small Mammals in Giritale Nature Reserve (North-Central Sri Lanka)

Abstract: The composition of small mammal communities in forest, shrub land, grassland and anthropogenic habitats of the Giritale Nature Reserve of north central Sri Lanka was studied from June 2006 to August 2007 to estimate the abundance and diversity of small mammals inhabiting this nature reserve. Live trapping using Sherman traps and Pitfall traps were adopted to catch the small mammals. A total of 71 individuals representing two orders (Insectivora and Rodentia) and three families (Soricidae, Muridae, Scuridae) was captured. Species recorded included Suncus murinus murinus Linnaeus, 1766 (Common Indian Musk Shrew), Mus cervicolor fulvidiventris Blyth, 1852 (Ceylon Field Mouse), Mus mus culuscastaneus Waterhouse, 1843 (Indian Field Mouse), Mus fernandoni Phillips, 1932 (Ceylon Spiny Mouse), Rattus blanfordi Thomas, 1881 (White Tailed Rat), Funambulus palmarum Linnaeus, 1766 (Indian Palm Squirrel) and Rattus rattus . The species Rattus rattus consisted of two subspecies Rattus attusrattus Linnaeus, 1758 (Common House Rat) and Rattus rattus rufescens Gray, 1837 (Indian House Rat). Highest and lowest abundances were recorded in the grasslands (0.08) and shrub lands(0.01), respectively. Highest diversity index was recorded in anthropogenic habitats (1.62), which included paddy fields, home gardens and buildings, while lowest diversity index was recorded in shrub lands (0.67). The number of small mammals captured was significantly different in the four habitat types (χ2 = 22.69, df = 3, p<0.05). This study, which is the first detailed examination of terrestrial small mammals in a dry zone forest of Sri Lanka, indicated that the Giritale Nature Reserve is home to six species of small mammals.