Sri Lanka Association for the Advancement of Science

Serum Uric Acid Concentrations of Newly Diagnosed Breast Cancer Patients

2015-11-01T00:00:00Z

Serum Uric Acid Concentrations of Newly Diagnosed Breast Cancer Patients Akalanka, H.M.K.; Ekanayake, S. Toxicity caused by oxygen radicals is considered to be associated with carcinogenesis. Uric acid (UA) is an antioxidant which could scavenge the oxygen radicals formed in the body and thus may have a protective role against cancer development. It is hypothesized that low serum UA may be associated with cancer risk. Altered serum UA concentrations are also reported in other disease status as well. As no data related to serum UA concentration and breast cancer (BC) is reported in Sri Lanka the objective of the study was to assess serum UA concentrations of BC patients and to compare with age matched apparently healthy females. Newly diagnosed BC patients (n=150) were selected for the study after consent was obtained. Information on other diseases suffered by the BC patients were collected Patients with diseases that could affect UA level (renal failure and cardiovascular diseases, etc) were excluded from the study. Apparently healthy age matched females (n=75) were selected as controls. Serum UA concentrations were measured using Kone 20XT biochemical analyzer. Statistical significances were determined when p<0.05 using SPSS version 16. Mean serum UA concentration of BC patients was 200±57 µmol/L and a significant difference in UA according to the menopausal status was not observed. The mean serum UA of age matched healthy women was 256 ± 72 µmol/L and serum UA of breast cancer patients was significantly lower (p=0.000) compared to healthy women. However, both groups had serum UA within the normal reference range (142-339 µmol/L) while BC women had UA levels closer to the lower reference margin. The UA concentration among BC and normal women studied via ROC curve showed 76% (p=0.000, CI 0.68-0.83) of area under the curve with UA cutoff value of 194 µmol/l, with 92% sensitivity and 63% specificity. In conclusion, it can be stated that serum UA concentrations of breast cancer patients are significantly low compared to healthy females.

Investigation of Chloride Ion Penetration Resistance of Silica Fume Mix Concrete

2015-12-01T08:39:17Z

Investigation of Chloride Ion Penetration Resistance of Silica Fume Mix Concrete Krishnathilaka, R.K.S.; Perera, L.A.; Amarakoon, A.M.M.W.; Udamulla, K.M.L.A.; Karunananda, P.A.K. Sri Lanka, being an island with well developed coastal areas, has a large number of reinforced concrete (RC) structures in the coastal zone. Chloride attack on such concrete structures has become a significant issue in the construction sector and it has become necessary to curtail the adverse effects of chloride ions which lead to corrosion of reinforcing steel and subsequent reduction in the strength, serviceability, and aesthetics of structures and finally the failure of structures. The level of chloride ion penetration is related to concrete permeability and with increasing permeability, an increase of chloride ion penetration occurs. Studies have indicated that the addition of materials such as fly ash, ground granulated blast furnace slag and silica fume in certain proportions in the mix reduces the penetrability of concrete. Hence, a possibility exists for the retardation of chloride ion penetration under such conditions. In this study, the chloride ion penetration resistance of silica fume mix concrete was examined. The physical properties of silica fume (fineness, specific gravity and water absorption) were determined in the study. Concrete mix of Grade 25 was tested according to the BS Mix Design Method. Specimens with Ordinary Portland Cement (OPC) concrete and specimens with OPC replaced by silica fume at the levels of 5%, 10% and 15% by weight of cement were tested. Compressive strength tests (according to BS 1881-116-1983) were carried out on concrete cubes of size 150 mm x 150 mm x 150 mm. Workability was measured by the slump test, compacting factor test and VB test. Chloride Ion Penetration test was carried out according to the procedure given in ASTM C-1202. The results indicated that the workability reduces with the increase of silica fume for Grade 25 concrete. The compressive strength of silica fume mix concrete decreased with the increase of silica fume content in the concrete. However, the results of Chloride Ion Penetration test revealed that the addition of silica fume reduced the chloride ion penetration indicating a reduced level of chlorine attack in concrete.

Detection of Artificially Ripened Bananas

2015-12-01T08:38:02Z

Detection of Artificially Ripened Bananas Pavithra, A.P.C.; Pasqual, H.; Athapattu, B.C.L. Bananas are a main source of vitamins and minerals among various kinds of tropical fruits. However, its consumption is becoming less due to intentional chemical usage for artificial ripening which causes serious health hazards. Ripening is normally a natural process through which the fruits gradually become sweet, colored, soft and palatable. Fruit sellers artificially ripen the fruit to meet customers’ demand and to overcome transportation and distribution issues. Ethylene is the major ripening agent produced naturally within the fruits which initiates the process of ripening. However, ethanol, methanol, ethylene glycol, ethephon and calcium carbide are used to ripen fruits artificially. The use of calcium carbide has been banned in many countries due to its high toxicity. Ethephon has been used in Sri Lanka for artificial ripening of mostly bananas, papaw and mangoes. When ethephon (2 chloroethylphosphoric acid) is used for ripening of fruits, ethylene gas is released which helps to accelerate ripening. Ethephon is hazardous and there are no reliable methods to detect such chemically treated fruits in the Sri Lankan market. This research proposes a design of an electronic device which will automatically carry out the detection process and provide an indication of the concentration of the applied chemicals. The detection is done electronically by measuring the conductivity of the water in which the banana is rinsed. The design consists of three main units, detection unit, controller unit and power supply unit. In the testing, the banana sample is rinsed with distilled water and the conductivity of the rinsed water is measured by using a conductivity sensor. The reading is then displayed on a digital screen with the indication on the presence of chemicals to assess whether chemically treatment has been carried out. The testing process is automated by using a microcontroller. The preliminary testing was conducted for two types of artificially ripened bananas (Ambul and Suvandel) with known ethephon solutions. Significant differences were recorded in comparison with the readings obtained for naturally ripened bananas. The detection method can also be extended to other fruits to investigate the use of ethophone or artificial ripening. It is expected that the proposed device would be useful for inspectors of food and consumer safety for detecting illegally ripened bananas without destructing of the fruit.

Technical Feasibility of Operating Organic Rankine Cycle with waste Heat

2015-12-01T08:36:56Z

Technical Feasibility of Operating Organic Rankine Cycle with waste Heat Madaluwage, L.; Prasad, D.M.; Senanayake, N.S.; Jatunarachchi, T.S.S. Sri Lanka has to rely on thermal power generation for reliability of the national electricity grid, especially during droughts or dry seasons, due to frequently changing climatic patterns. For thermal power generation, the country is entirely dependent on imported fuels and therefore, it is vital that the thermal power plants of Sri Lanka should be operated in a cost effective manner. The exhaust gas temperatures of thermal power plants are usually in the range of 290 C – 320 C which indicates that a considerable amount of thermal energy is wasted without being used. This study was undertaken at a power station where a part of this energy is recovered and used to produce saturated steam using waste heat boilers, which are used for heating heavy fuel oil used for gas turbines in order to increase the efficiency. The practical limitation of recoverable heat from exhaust gasses can be determined by the sulfur dew point of the fuel which is usually 135 oC.The study was conducted with the objective of recovering the maximum possible heat from the exhaust of a diesel engine and utilizing the recovered heat to operate a power plant based on the Organic Rankine Cycle, with the working fluid being toluene, which is best suited for low temperature heat sources. The Organic Rankine Cycle was optimized using Engineering Equation Solve Software based on the constraints imposed by the sulfur dew point of the fuel and the pinch point temperature difference. The study established the parameters of the Organic Rankine Cycle as: pinch point temperature difference - 2.011 oC, turbine power - 570.6 kW, condenser pressure -0.07 bar, mass flow rate of toluene - 3.298 kg/s and thermal efficiency - 20.95% for optimum conditions.