PURSE

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Browsing PURSE by Author "Abeykoon, A. M. S. B."

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    A Study of electrical conductivity of Peo-X solid polymer electrolytes with X= LiCf3 So3 ZnC7 H5 O3 and PbI 2
    (University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Bandara, L. R. A. K.; Abeykoon, A. M. S. B.; Bokalawela, R. S. P.; Dissanayake, M. A. A. K.
    Solid polymer electrolytes occupy a unique posrtion in the development of a new generation of power source applications ranging from small portable electronic equipment to larger electric vehicles. These polymers, in thin film form, display many advantages over liquid electrolytes such as leakage proof and gassing. further, they show dual action both as ionic conductors and mechanical separators, which make them the most attractive solid polymer electrolyte in conducting polymer-based batteries. A wide range of salts can be dissolved in poly(ethylene oxide) (PEO) to form solid polymer electrolytes whose transport ions may be cations or anions. In this work, PEO based electrolyte films with three types of salts, namely lithium triflorosulfonate (LiCF3S03), zinc salizelate (ZnC7Hs03) and lead iodide (Pbh) were used and their electrical conductivity measurements were carried out. Samples have been prepared by the solvent casting technique. The complex impedance measurements were performed over the frequency range of 5 Hz to 13 MHz, using a computer controlled HP4192A impedance analyzer with an applied signal of 0.1 V. The impedance data were collected in the temperature range of 25°C to 85 "C. DC polarization test was carried out on all the samples, using both the blocking and non blocking electrodes, to estimate the tranfrerency numbers of the polymer electrolytes. Compared to the other two systems, PEO-LiCF3S03 system shows higher ionic conductivities. With both ZnC7Hs03 and Pbl- salts, PEO based solid polymer electrolytes show almost the same conductivity values within the studied temperature range. In all three systems, the ionic conductivity increases linearly with increasing temperature. The knee observed in these conductivity curves are assumed to be due to the melting of the crystalline phase of pure PEO. It was observed that the ionic conductivity is high in the amorphous phase above 55°C, in the presence of a flexible polymer chain. Results of the dc polarization test showed that all the studied samples had low electronic conductivities. According to the above results, PEO- LiCF3S03 and PEO-ZnC7Hs03 systems can be mainly considered as cationic conductors while the PEO-PbI2 system acts as anionic conductors.
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    Absence of dengue virus NS 1 Antigen in Aedes aegypti and Aedes albopictus mosquitoes collected from urban areas of Peradeniya and Kegalle
    (The University of Peradeniya, 2013-07-04) Ekiriyagala, W. R. S. K.; Noordeen, F.; Abeykoon, A. M. S. B.; Ariyaratne, C. S.
    Dengue fever (DF) is an important mosquito-borne disease that affects humans causing morbidity and mortality. With neither vaccines nor treatment available, prevention of the disease relies heavily on surveillance and control of mosquito vectors. Aedes aegypti is considered to be the major vector for dengue virus (DENV) transmission, whereas Aedes albopictus is considered to be the secondary vector. Both Aedes spp. are responsible for carrying any of the four serotypes of DENVs (DENV1, DENV2, DENV3, and DENV4). Firstly, we examined the Aedes mosquitoes collected outdoors to identify which of the Aedes species was abundant in the urban areas of Kegalle and Peradeniya. Secondly, we evaluated NS1 antigen detection (SD BIOLINE Dengue NS1 test) in field caught Aedes aegypti and Aedes albopictus mosquitoes (n=165) to gather evidence for DENV carriage. Aedes albopictus was more abundant (115/165; 70%) than Aedes aegypti (50/165;30%) in the urban areas of Kegalle and Peradeniya. However, we were unable to detect Dengue NS1 antigen in the field caught Aedes aegypti and Aedes albopictus mosquitoes. The reason for not detecting the Dengue NS1 Ag in the field caught Aedes spp. May be twofold. First, these field caught mosquitoes may not be carrying the DENV or our test was unable to detect the low level of DENV found in the field- caught mosquito pools. However, supernatants obtained from the same mosquito pools that were tested for Dengue NS1 antigen are stored at -80oC for DENV RNA extraction and RT-PCR to confirm the validity of Dengue NS1 antigen detection test in the field caught mosquitoes.