Reduction of lipid peroxidation and H2O2‐mediated DNA damage by a red alga (Grateloupia filicina) methanolic extract

The antioxidant activity of an extract of Grateloupia filicina was evaluated using linoleic acid and fish oil as substrates in an induct period at 65 °C. Furthermore, the algal extract was subjected to comet assay to evaluate its protecting ability for H₂O₂‐induced DNA damage in rat lymphocytes. Progression of oxidation was examined using weight gain, peroxide value (PV), 2‐thiobarbituric acid reactive substances and conjugated diene data. Effectiveness of the extract at 0.03 and 0.05% levels was superior to that of α‐tocopherol at 0.01% and the activity of 0.05% extract was higher than that of butylated hydroxyanisole and butylated hydroxytoluene at 0.01%. Also, the algal extract significantly inhibited H₂O₂ induced DNA damage in comet assay. The maximum DNA damage inhibition (68.9%) was recorded from the 50 µg ml⁻¹ alga extract when the rat lymphocyte cells were treated with 50 µM H₂O₂. Copyright © 2005 Society of Chemical Industry     

Estimating short and long-term residential demand for electricity: New evidence from Sri Lanka

This study investigates the short-run dynamics and long-run equilibrium relationship between residential electricity demand and factors influencing demand – per capita income, price of electricity, price of kerosene oil and price of liquefied petroleum gas – using annual data for Sri Lanka for the period, 1960–2007. The study uses unit root, cointegration and error-correction models. The long-run demand elasticities of income, own price and price of kerosene oil (substitute) were estimated to be 0.78, ? 0.62, and 0.14 respectively. The short-run elasticities for the same variables were estimated to be 0.32, ? 0.16 and 0.10 respectively. Liquefied petroleum (LP) gas is a substitute for electricity only in the short-run with an elasticity of 0.09. The main findings of the paper support the following (1) increasing the price of electricity is not the most effective tool to reduce electricity consumption (2) existing subsidies on electricity consumption can be removed without reducing government revenue (3) the long-run income elasticity of demand shows that any future increase in household incomes is likely to significantly increase the demand for electricity and (4) any power generation plans which consider only current per capita consumption and population growth should be revised taking into account the potential future income increases in order to avoid power shortages in the country.     

A matrix in life cycle perspective for selecting sustainable materials for buildings in Sri Lanka

This paper presents a matrix to select sustainable materials for buildings in Sri Lanka, taking into consideration environmental, economic and social assessments of materials in a life cycle perspective. Five building elements, viz., foundations, roofs, ceilings, doors and windows, and floors are analyzed based on materials used for these elements. Environmental burdens associated with these elements are analyzed in terms of embodied energy and environmental impacts such as global warming, acidification and nutrient enrichment. Economic analysis is based on market prices and affordability of materials. Social factors that are taken into account are thermal comfort, interior (aesthetics), ability to construct quickly, strength and durability. By compiling the results of analyses, two building types with minimum and maximum impacts are identified. These two cases along with existing buildings are compared in a matrix of environmental, economic and social scores. Analysis of the results also indicates need for higher consideration of environmental parameters in decision-making over social and economic factors, as social and economic scores do not vary much between cases. Hence, this matrix helps decision-makers to select sustainable materials for buildings, meaningfully, and thus helps to move towards a more sustainable buildings and construction sector.     

Extraction and fractionation of alkylresorcinols from triticale bran by two-step supercritical carbon dioxide

Bran from triticale cultivars Ultima and Pronghorn and Canadian Prairie Spring (CPS) wheat were fractionated using a two-step sequential supercritical carbon dioxide (SC-CO₂) extraction technique with and without ethanol to selectively extract and enrich high-value alkylresorcinols (ARs). Pure SC-CO₂ (70 °C; flow rate 25 g/min; pressure 35 MPa), was used for the first extraction step. The non-polar lipids yield ranged from 3.08 to 3.26 g/100 g and they were composed mainly of C18:2 (33-41 g/100 g), C18:1 (15-21 g/100 g), C16:0 (15-19 g/100 g), and C18:3 (4-5 g/100 g) fatty acids. The second extraction step, performed on the bran remaining after the first extraction, was carried out with SC-CO₂ plus 0.5 mL/min ethanol (70 °C; flow rate 5 g/min; pressure 35 MPa). The resulting total polar lipid yield of bran samples ranged between 0.62 and 0.86 g/100 g and the main compounds present in the polar lipids were ARs. The total AR contents of triticale cv Ultima, wheat, and triticale cv Pronghorn were 70, 68 and 36 mg/100 g, respectively. Saturated and unsaturated AR homologues of C15:0, C17:0, C19:0, C19:1, C21:0, C21:1, C23:0 and C25:0 were detected in all samples. Over 98% of the triticale ARs and over 95% of the wheat ARs were extracted under the SC-CO₂ conditions used.     

Reactive ion etching of dielectrics and silicon for photovoltaic applications

This paper investigates the reactive ion etching of SiO₂, Si₃N₄, and Si using CHF₃/O₂ plasma. In particular, we have characterized the time and rf power dependence of the carrier lifetimes in n‐ and p‐type FZ Si. The time dependence of reactive ion etching (RIE) at different rf powers provide insight into the two competing processes of damage accumulation and damage removal in the near‐surface region of the Si during plasma etching. The carrier lifetime, measured using the quasi‐steady‐state photoconductance (QSSPC) technique, has a quadratic dependence on the rf power, which can be related to changes in the dc self‐bias generated by the plasma at different rf powers. The change in carrier lifetime is similar in both n‐ and p‐type Si of the same doping concentration. Using this fact, together with the electronic properties of defects obtained by deep level transient spectroscopy (DLTS), we have modeled the injection‐dependence of the measured carrier lifetimes using the Shockley–Read–Hall model. The isochronal annealing behavior of plasma etched Si has also been studied. Copyright © 2006 John Wiley & Sons, Ltd.     

The Need for Gender Analysis in Strategic Planning for Effective Water Management in Sri Lanka

With diminishing investments both the irrigation and water supply sector in Sri Lanka has had to resort to participatory management with enhanced stakeholder interaction. The use of gender participation in capacity building varies in the two major state agencies involved in water resources management:the National Water Supply and Drainage Board (NWSDB) and the Dept of Irrigation (ID). The differing gender needs and contributions are recognized to a considerable extent and incorporated into planning, operation and maintenance of rural water supply, but the same recognition is not accorded to gender considerations as an issue affecting capacity building in the irrigation sector.     

Extraction,purification and characterization of wax from flax (Linum usitatissimum) straw

The chemical composition and selected physical parameters of wax extracted from flax straw with supercritical CO₂ (SC‐CO₂) and hexane have been determined. From the GC/MS results, clear variations in composition and component distributions were observed between SC‐CO₂‐ and hexane‐extracted samples. The major components of the SC‐CO₂ and hexane extracts from three flax cultivars were: fatty acids (36–49%), fatty alcohols (20–26%), aldehydes (10–14%), wax esters (5–12%), sterols (7–9%) and alkanes (4–5%). Purification of SC‐CO₂‐extracted wax with silica gel chromatography yielded 0.4–0.5% (dry matter) and was composed primarily of wax esters (C₄₄, C₄₆ and C₄₈) and alkanes (C₂₇, C₂₉ and C₃₁). UV‐Vis scans of the purified wax samples exhibited two main peaks indicating the presence of conjugated dienes and carotenoids or related compounds. Fourier transform infrared results showed prominent peaks at 2918 (‐C‐H), 2849 (‐C‐H), 1745 (‐C=O), 1462 (‐C‐H), 1169 (‐C‐O) and 719 cm^–1 (‐(CH₂)_n‐), with NorLin wax showing a slightly deviating pattern compared to the other samples. Thermal analysis by differential scanning calorimetry revealed a mean melting point of 55–56 °C and oxidation temperatures of 146–153 °C for purified wax from flax straw processed using different procedures.     

Experimental Depiction of the Hypothesis of Flake-Like Wear Debris Generation in Rolling Contact Fatigue of the Rail–Wheel Contact Interface

Flake-like particles represent a common type of wear debris generated during the rolling contact fatigue wear test using a twin-disc test rig. It is argued that these flake-like particles are generated during the delamination process due to plastic shear strain accumulation at the wearing surfaces. This hypothesis has been developed in the last decades to explain the particle generation mechanism, yet it has not been proven conclusively. This research provides strong experimental evidence of the creation processes of wear debris propagation, aggregation, transfer, and compaction, therefore confirming the existing hypothesis and enhancing the understanding of wear mechanisms in the rolling contact interface.     

Pesticide poisoning: a major health problem in Sri Lanka

Acute pesticide poisoning is a major public health problem in Sri Lanka. In several agricultural districts, it precedes all other causes of death in government hospitals. Most of the acute poisoning cases are intentional (suicide) and occur among young adults, mainly males. Poisoning due to occupational exposure is also common, but less well documented. In an irrigation area in Sri Lanka a very high incidence of serious pesticide poisoning was observed, with 68% due to intentional ingestion of liquid pesticides. It is argued that the easy availability and widespread use of highly hazardous pesticides is the most important reason for this high number of poisoning cases. The frequent application of highly hazardous pesticides in high concentrations was often irrational and posed serious health and financial risks to the farmers. Sales promotion activities and credit facilities promoted this excessive pesticide use, which was not counteracted by an agricultural extension service. Hazardous practices when spraying pesticides were due to the impossibility of applying recommended protective measures under the local conditions, rather than to lack of knowledge. Current emphasis on programs that promote the safe use of pesticides through education and training of farmers will be ineffective in Sri Lanka because knowledge is already high and most poisoning cases are intentional. Instead, enforcement of legislation to restrict availability of the most hazardous pesticides would result in an immediate health benefit. Improved agricultural extension services to promote alternative non-chemical methods of pest control is the most important strategy, in the long term, to prevent acute pesticide poisoning.     

Environmental,economic and social analysis of materials for doors and windows in Sri Lanka

This paper compares the environmental, economic and social impacts of two types of doors and windows (elements), namely timber and aluminum taking into consideration the life cycle perspective. These elements are widely used for the buildings in Sri Lanka. Thus, it will help in the decision-making process when selecting materials for these elements. Major materials used for these elements are timber, brass, glass, paint, aluminum, rubber, steel and PVC boards. Environmental burdens associated with these materials are analyzed in terms of embodied energy, and environmental impacts that are relevant to Sri Lanka, such as global warming (GWP), acidification (ACP) and nutrient enrichment (NEP). Economic analysis is done using market prices of materials and affordability for those materials. Social concerns such as thermal comfort, good interior (aesthetics), ability to construct fast, and durability are analyzed based on the data collected through the questionnaires and also, interviews with the stakeholders of the buildings such as engineers, architects, building contractors and building users. It was found that timber elements are superior to aluminum elements in environmental scores (GWP, ACP and NEP). On economic score, also, timber elements are better. But on social score, aluminum elements are better than timber. It was also found that the higher the recycling percentage of aluminum, the higher the environmental favorability of the aluminum.