An Investigation into the Effect of the Shell on SALM Processed Parts

Shell Assisted Layer Manufacturing (SALM) is a novel process for rapid prototyping/ tooling/ manufacture (RP/RT/RM) which is presently undergoing feasibility studies. SALM is based on layered manufacturing technology (LMT). Initially it develops the shell (boundaries) of a selected layer using a technique similar to fused deposition modelling (FDM). The developed shell is filled with a UV curable resin and is exposed to UV radiation for curing. This procedure is repeated until the complete part is built. This paper compares and contrasts properties of parts made using two options available with the SALM technique: building the part using a soluble shell (FDM support structure material, finally dissolved to recover the part); or using a polymer material such as ABS that is bonded with the resin whilst making the part.Mechanical Engineerin

The impact of inappropriate soil management on river water quality: a case study in the Kurundu Oya Sub-catchment of the Upper Mahaweli Catchment, Sri Lanka

The results of many studies have revealed that intensive farming on steep slopes, coupled with over application of fertilizers and accumulation of nutrients in downstream water bodies due to soil erosion, have contributed to environmental hazards in the Upper Mahaweli Catchment Area (UMCA) of Sri Lanka. The encroachment of riparian zones for exotic vegetable cultivation has aggravated this situation. In view of this, a study was conducted in the Kurundu Oya catchment, a micro-catchment of the UMCA, to investigate the soil management practices within the farming systems and their impacts on river water quality. Three villages were selected along the Kurundu Oya: Mahakudugala, Kumbalgamuwa and Batagolla. The study consisted of a survey of 150 households in 2007 and 2008, to gather information on the characteristics of householders and on soil management practices. A soil survey was carried out to analyze the soil fertility of farmlands. Water quality parameters were measured periodically in different sections of a selected stream. The results revealed that nearly 50 % of the riparian zones in the upper catchment of the Kurundu Oya stream are encroached to cultivate potato and other exotic vegetables. In addition, it was observed that over application of fertilizers on the vegetable plots was causing nutrient accumulation and the plots also recorded high levels of phosphorous (P) (above 75 ppm). Results of the water quality analysis showed that nitrate and available P levels were within the standard limits, but nitrate nitrogen (NO3-N) levels were close to the upper level of the standard limit. Therefore, in order to minimize water pollution, it is strongly recommended that fertilizer application is based on soil tests. In addition, encroachment of sensitive lands has to be addressed. Priority should be given to strengthening institutional capacity in order to facilitate the implementation of existing environmental legislation.Length: pp.49-60Soil managementSoil degradationCatchment areasErosionSedimentationWater pollutionFertilizer applicationNitrogenVegetable growing

Double beta decay of 48^{48}Ca

$^{48}$Ca, the lightest double beta decay candidate, is the only one simple enough to be treated exactly in the nuclear shell model. Thus, the $\beta\beta(2\nu)$ half-life measurement, reported here, provides a unique test of the nuclear physics involved in the $\beta\beta$ matrix element calculation. Enriched $^{48}$Ca sources of two different thicknesses have been exposed in a time projection chamber, and yield T$_{1/2}^{2\nu} = (4.3^{+2.4}_{-1.1} [{\rm stat.}] \pm 1.4 [{\rm syst.}]) \times 10^{19}$ years, compatible with the shell model calculations.Comment: 4 pages, LaTex, 3 figures imbedded, PRL forma

Household water security through stored rainwater and consumer acceptability: a case study of the Anuradhapura District

Rainwater harvesting has increased in popularity in Sri Lanka over the past two decades due to the number of water supply projects funded by the government and non-governmental organizations (NGOs). The stored rainwater can provide accessible, reliable, timely and adequate supplies of water to households but there are uncertainties as to safety, in terms of water quality, and consumer acceptability. A study was, therefore, conducted in the Anuradhapura District, in the dry zone, to assess consumer acceptability of stored rainwater for household purposes and to conduct rainwater quality tests in a laboratory. The majority of households in Anuradhapura meet their drinking water requirements from protected wells (59.6 %). Prior to the project, people greatly preferred open wells as a source of domestic water, followed by tubewells, because they believed that water in open wells is of good quality and drinkable. However, stored rainwater has become the priority source now, especially through roof rainwater harvesting (RRWH), which is used during the dry periods. The study revealed that more than 85 % of households use stored rainwater for drinking although some have concerns over the quality and only drink it after boiling. The easy accessibility of water and the assurance by the project team that it is of good quality are the main reasons that people are willing to drink it. The acceptability of stored rainwater for consumption was very high in water-scarce areas and with the increasing distance to the nearest and alternative sources of good-quality water. Of those who felt that they had adequate water, 84 % of the sample households found it adequate in the wet season but only 21 % in the dry season. Water quality analysis revealed that the chemical and physical quality of stored rainwater is within the acceptable range with respect to Sri Lankan Standards, SLS: 614, for potable water quality (SLIS 1983). Other domestic water sources exceeded standards for electrical conductivity, total alkalinity, hardness, ammonium nitrogen, fluorides and total iron. However, stored rainwater was of lower biological quality than other domestic water sources.Length: pp.87-97Domestic waterWater securityWater harvestingWater qualityRural areasCase studies

Evaluation of in vitro anti-inflammatory activity of five selected marine sponges against denaturation of protein-A pilot study

Background: Marine sponges are well renowned for producing bioactive secondary metabolites with drug leads. Screening of anti-inflammatory compounds from marine sponges is highly appreciated in the field of marine pharmacognosy due to their effectiveness and specificity over the most of synthetic non-steroidal anti-inflammatory drugs. In vitro models to test anti-inflammatory activity are considered obligatory prior to pre-clinical studies. Objective: To evaluate in vitro anti-inflammatory effect of crude extracts of five marine sponge samples (N=5), collected from Dehiwala, Colombo, Sri Lanka. Methodology: Identification of sponge species were based on morphology, spicule and skeleton analysis, using light microscopy. Each sponge crude extract (SCE) was tested for selected zoo- chemicals and against the denaturation of albumin to assess the anti-inflammatory activity. Diclofenac sodium was used as the reference drug. Results: Sponge samples were identified as 1) Stylissa sp, 2) Stylissa carteri, 3) Axinella sp., 4) Phakellia sp. and 5) Family Axinellidae. Zoo-chemical analysis indicated the presence of alkaloids, saponins, terpenoids, and sterols in sponge extracts in varying degree. Heat induced egg albumin denaturation was inhibited by 4 SCEs specifying marked anti-inflammatory activity. Accordingly, the 3 sponge crude extracts were more potent (IC50 = 22.74 for Sp. 02, 3.98 for Sp. 03 and 63.665\u3bcgmL -1for Sp. 05) than the of standard reference drug, Diclofinac sodium (IC50=147.02 \u3bcg/mL). Conclusions: Thus, the present study for the first time investigated in vitro anti-inflammatory activity of crude extract of 5 selected marine sponge species from Sri Lanka, out of which 3 were more potent than the reference diclofenac sodium. Therefore, isolation and characterization of bioactive compounds which are responsible for anti- inflammatory activity will lead to discover novel marine derived anti-inflammatory drugs in the future