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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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Ruhuna Journal of Science
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1800-279X
Published by Sri Lanka Journals Online Homepage  [71 journals]
  • Exploring marketing channels and market margins of tuna species: A case
           study of Negombo fishery harbour in Sri Lanka in 2018

    • Abstract: This study was carried out to determine the domestic level marketing channels, marketing cost, and marketing margin for four commercially important marine fish species in Negombo fishery harbour, Western Province, Sri Lanka, with a focus on marketing efficiency. Data related to fish catch and prices were collected by direct observation during the period of January to December 2018. About 80 to 105 tons of fish catch per day were being landed. The annual average wholesale prices of fish (kg-1)g varied from LKR 450 to 670 for Yellowfin tuna, LKR 233 to 414 for Skipjack tuna, LKR 320 to 385 for Frigate tuna, and LKR 140 to 190 for Indian scad, which is typical market behaviour. Though the net profit per 100 kg of fish received by the wholesaler was higher than the assembler, the retailer has made a significant amount of profit, nearly six times higher than the assembler. Ten marketing channels were identified from fish producers to the ultimate consumer and some channels involved more than three intermediaries. As typical for long marketing channels, high prices were paid by the consumer for the low freshness quality of fish. Though, the retail price of skipjack tuna at the Negombo landing center is moderately correlated (r=0.634), the other three fish species did not give a clear indication. Thus, the price factor of selected marine fish at the landing site was not having a significant impact on the market integration. Consumers were concerned about both price and quality when purchasing the fish. To improve the marketing efficiency of the marine fish market, it is recommended to implement shortening of the fish market channel with less involvement of intermediaries and to develop the fish market facilities appropriately. Published on 2021-12-31 00:00:00
  • Formulation and quality assessment of tomato (Lycopersicon esculentum)
           cordial with xanthan stabilizer

    • Abstract: Tomato fruit is a nutritious part of the human diet providing a variety of health benefits. Searching for other means of utilization than direct consumption of tomatoes seems a timely need to reduce post-harvest losses caused by the rapid perishability of ripened tomatoes. In the present study, three tomato cordial formulations with xanthan gum as a stabilizer were tested for sensory properties, and the best formula was tested for its physico-chemical properties and stability over one month period. Well-ripened and healthy fruits were chosen to prepare the cordial. According to the Sri Lankan Standards (SLS 730), three different cordial samples were prepared only changing the concentration of xanthan gum stabilizer as 0.3%, 0.4% and 0.5% (w/v). Using 30 semi-trained panellists, prepared samples were subjected to sensory testing on a 5-point Hedonic scale, and 0.5% of xanthan gum containing cordial was selected as the best formula. The shelf-life evaluation of the best sample was conducted weekly for one month through physicochemical and microbiological analysis. Significant changes (p<0.05) were observed only in vitamin C content and total soluble solids (TSS) during the shelf-life evaluation. At end of the storage period, the cordial with 0.5% xanthan gum possessed pH 3.26, titratable acidity 1.35%, vitamin C 31.9 mg/100ml, TSS 44.9 °Brix, total sugar 19.8% and polyphenol content 0.0021 mg/ml GAE. Changes in the total plate counts during the one month of storage are within the acceptable limit (less than 50 per ml) according to the Sri Lankan Standards (SLS 516). It can be concluded that tomato cordial can be formulated by using 5% of xanthan gum stabilizer and that was found to be stable for one month without any deterioration. Published on 2021-12-31 00:00:00
  • Analysis of physicochemical parameters and selected potentially toxic
           elements to assess the water quality of Kattakaduwa reservoir in
           Hambanthota district, Sri Lanka

    • Abstract: The study was aimed to assess the water quality of Kattakaduwa reservoir in Hambantota district, Sri Lanka. Reservoir water is not directly used for drinking purposes until purification, but people use it for different purposes such as bathing and irrigation. A comprehensive study on the water quality of this reservoir water was timely needed due to the scarcity of such information. Monthly variation in seven physicochemical parameters and five potentially toxic elements (Mn, Fe, Cu, Cd and Pb) of water at five different sites compared to treated reference water samples were studied for 2017. Sediment analysis of the five elements at four different sites was also carried out. At the site closer to the inlet of the pump house before purification (site 3S), the mean values (± SD) of water temperature, pH, dissolved oxygen, sulphate concentration, turbidity, conductivity, and alkalinity were 33 ± 1°C, 7.5 ± 0.1, 7.19 ± 1.80 mg/L, 57.40 ± 23.60 mmol/L, 36.74 ± 18.87 NTU, 605.3 ± 119.8 µS, and 176.0 ± 32.0 mg/L, respectively. The maximum Fe concentration was observed in March (1.73 mg/L) while the minimum was in January (0.70 mg/L) exceeding the United States federal limits (USFL) and Sri Lankan Standard level (SLSL) of Fe (0.3 mg/L) throughout the year. However, Mn concentration in the same site exceeded the USFL and SLSL (0.05 mg/L) slightly in May, July, and October. The concentrations of the rest of the elements were below the minimum detection limit (MDL) of 1 mg/L. All elements in the treated reference water sample (TR) were below MDL. The concentrations of Fe (15291 ± 10486 mg/kg) in sediments were greater than Mn (1178 ± 1007 mg/kg). These values reflect the higher Fe concentration in the reservoir water compared to Mn concentration that may be due to the leaching of Fe from the sediments to the water. Published on 2021-12-31 00:00:00
  • Air pollution affects lichen species richness, species density, relative
           growth form abundance and their secondary metabolite production: a case
           study in Kandy district, Sri Lanka

    • Abstract: Lichens are symbiotic associations between fungi and algae and/or cyanobacteria, consisting of three forms, viz: fruticose, foliose and crustose. Air pollution affects lichen diversity, percent cover, and density. The current study mainly compared the lichen species richness, density and relative abundance of each growth form among three selected sites with different degrees of pollution, viz: a site located in the Kandy City (S1), a site located 11 km away from the city (S2) and a site within a forest patch located ~12 km away from the Kandy city (S3). A random sampling method was used to collect lichens within a two km distance in the three selected sites. Percent cover and density were determined using a quadrat ladder. Acetone extracts of lichens were subjected to thin-layer chromatography (TLC), and secondary metabolites were identified by visualizing under UV (254 and 365 nm) and by Rf values. A total of 24 lichen species were collected (S1=8, S2=12, and S3=4). Percentage richness of crustose and foliose lichens was higher in S2 compared to S1, while Leparia sp. and Lecanora sp. were common in S1 and S2. Atranorin, salazinic acid, and zeorin were detected as common compounds from lichens in S1 and S2 sites, exhibiting photoprotecting and antioxidant properties. Fumarprotocetraric acid, which tolerates harsh environmental conditions, and Physodalic acid, which is produced in response to pollution stress were detected from lichens from S1. Norstictic acid was identified in lichens from S2. The results show a difference between the lichen community and secondary metabolites among the three sites. Published on 2021-12-31 00:00:00
  • Community perception, awareness, and knowledge of coastal erosion with
           special reference to the South-Eastern coastal region, Oluvil, Ampara, Sri

    • Abstract: Coastal erosion is an environmental issue that has been aggravated by anthropogenic activities, leading to a worrying situation in the coastal zones of Sri Lanka in recent decades. The present study attempted to determine the community perception and awareness of coastal erosion in the South Eastern coastal region around Oluvil, Sri Lanka. 120 residents of Oluvil were selected following a random sampling method to conduct a survey using a structured questionnaire in 2020. The survey results revealed that 95% of the residents were aware of the coastal erosion while 50% were extremely concerned about it, particularly because it has worsened over the last 10 years. Awareness was significantly correlated with the level of education of the residents. About 77% of residents noted that coastal erosion in the last ten years had rapidly increased. Construction of the Oluvil fishery harbour was believed to be the major cause of coastal erosion in Oluvil, with 81% of respondents strongly agreeing in this regard. Further, 88% of residents believed that the existing conservation measures were not providing effective protection from coastal erosion. Many of the affected people had suggested permanent closure of the harbour as a measure to address coastal erosion. Knowledge and awareness about conservation measures to control coastal erosion were limited. It is suggested to provide adequate knowledge and awareness through training, workshops, and campaigns in future to protect their livelihoods and the local economy from the effects of coastal erosion. The findings of the study would be helpful to the responsible authorities and government to adopt appropriate measures to minimize the impacts of coastal erosion in Oluvil. Published on 2021-12-31 00:00:00
  • Determination of the distribution of Calotropis gigantea (L.) in Sri Lanka
           using MaxEnt modelling technique

    • Abstract: Calotropis gigantea is a drought-resistant, salt-tolerant, native plant in Sri Lanka with ayurvedic medicinal values. The plant is used for fiber, fodder and fuel, as well as a fertilizer. Despite its benefits, C. gigantea has become an emerging problem in countries where it has been introduced because of its invasiveness. Although C. gigantea is widely distributed in Sri Lanka, precise information on its distribution is lacking. Therefore, the present study was aimed at determining the distribution of C. gigantea in Sri Lanka. Field surveys were conducted in 120 sites covering all provinces in Sri Lanka from December 2014 to June 2015 to record the occurrence of C. gigantea. C. gigantea was distributed in all provinces except the Central province. It was more widespread along coastal regions, but its occurrence was low in the Western and Sabaragamuwa provinces. MaxEnt modelling predicted that the entire coast of Northern, North-Central and Eastern provinces contain the highest probability of C. gigantea distribution whereas the low probability was in North-Western, Western, Southern, Uva, Central, and Sabaragamuwa provinces. No occurrence probability was predicted in certain regions of Southern, Sabaragamuwa, Uva, and Central provinces of Sri Lanka. The study provides information on the current and potential distribution range of C. gigantea in Sri Lanka. Published on 2021-12-31 00:00:00
  • Effect of Nitrogen fertilizer, weed control and seed rate on incidence and
           severity of narrow brown leaf spot in rice cultivation under the dry zone
           of Sri Lanka

    • Abstract: Narrow Brown Leaf Spot (NBLS) caused by Cercospora janseana is a common disease of rice causing severe yield loss. In order to identify the factors favourable for disease development under field conditions, a study was carried out during the 2017/2018 Maha and 2018 Yala seasons. Effects of mineral N fertilizer, weed control, and seed rate on the incidence and severity of NBLS disease were determined. Two levels of mineral N, i.e., Department of Agriculture, Sri Lanka (DOF) recommended level and half of the DOF level were used with weedy and weed-free conditions, under four different seed rates, 100 kg/ha, 125 kg/ha, 150 kg/ha and 175 kg/ha. NBLS incidence was significantly higher (p<0.0001) in the Maha season compared to the Yala season. In the Maha season, mineral N fertilizer by weed interaction was significant on disease severity. In the Yala season, the disease incidence was significantly (p<0.05) higher in weedy conditions and fertilizer, weed and seed rate interaction and fertilizer and seed rate interaction were significantly (p<0.05) higher. The lowest disease severity was recorded in both seasons with the 100kg/ha seed rate, 100% fertilizer and weed-free conditions. When the weedy conditions prevailed in the field in Maha season, a disease severity scale value of 2 was observed at the highest frequency. Although only the weed condition affects NBLS incidence, it was found that the seed rate, fertilizer and, weed condition interaction was critical to control the severity of NBLS in paddy cultivation. Published on 2021-12-31 00:00:00
  • List of Reviewers- RJS Volume 12 (2021)

    • Abstract: No abstract available Published on 2021-12-31 00:00:00
  • Elastic and mechanical properties of cubic metal arsenides (Ga, In and Al)
           under high-pressure: a simulation study

    • Abstract: Semiconducting materials have played an important role in modern technological age. Group III-V materials have attracted much attention in electronic industry due to their structural, mechanical, electronic and thermodynamic properties predicted by calculations. This paper simulated the effect of pressure within the range of 0-100 GPa on the elastic constants and other related parameters, such as Young’s, bulk and shear moduli, Pugh ratio, Poisson ratio, anisotropy factor, degree of anisotropy and Kleinman parameter for gallium arsenide (GaAs), indium arsenide (InAs) and aluminum arsenide (AlAs) materials, using the Tersoff classical potential within ATK-force field.  Results showed that, increase in pressure enhanced the ductility of GaAs and InAs within the entire pressure domain, and between 10-40 GPa for AlAs material. AlAs was found to be brittle under 50-90 GPa, and unstable at 100 GPa. This may be due to occurrence of phase transition at these pressures. The obtained results at zero pressure are consistent with available experimental and theoretical data in literature. Published on 2021-09-15 00:00:00
  • Mass production of the nematode Acrobeloides longiuterus using Tribolium
           castaneum and artificial solid media

    • Abstract: Free-living nematode Acrobeloides longiuterus (Rhabditida: Cephalobidae) exhibits a potential to kill some insect pests. Mass production of this species is a requirement for use it in pest management programs. Tribolium castaneum has been used as a primary host for this nematode as an alternative for Galleria mellonella. Use of artificial media is another option for mass culturing and such recipes based on soy flour are available. Production of A. longiuterus using cost effective method and easily available insect host is important in setting up of small-scale production unit. Therefore, this study has the objectives of evaluating the production feasibility of A. longiuterus on T. castaneum larvae, pupae and adults as in vivo production method. Further, feasibility of using different solid media such as soy flour, palmyra tuber flour, corn flour, black gram flour and dhal flour with other basic ingredients as in vitro conditions system was evaluated. Results revealed that pupa of T. castaneum yielded the highest number of infective juveniles (36112 IJs/ pupa) compared to other life stages tested. In vitro production of A. longiuterus on soy flour and black gram flour media yielded 21530 and 16538 IJs/20g, respectively. Pathogenicity against T. castaneum was shown up to 93% by the infective juveniles produced from the in vitro cultures. In conclusion, T. castaneum is an alternative insect that can be used as a host to produce the A. longiuterus. In addition, soy flour and black gram flour can be used as the sources for this nematode production without losing their entomopathogenicity. Published on 2021-09-15 00:00:00
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