http://www.digital.lib.esn.ac.lk//handle/123456789/1260 2026-04-21T12:54:07Z http://www.digital.lib.esn.ac.lk//handle/123456789/1669 Projective and part metric techniques in proving the existence of unique positive solutions for non-linear integral equations. T.Sritharan We will present the existence and uniqueness of a non-negative solution of non- linear integral equations of the type u(x) — f^K(x,y) F(y,u(y)} dy, where O is a closed and bounded domain in JJ^, K(., .) is non-negative and satisfies some integral inequalities and F(x, u(x)} is a-concave in the variable u. As an application, the existence of a unique positive solution of boundary value problem for a uniformly elliptic differential equation with the forcing function F(x^u(x)) is given 2000-01-01T00:00:00Z http://www.digital.lib.esn.ac.lk//handle/123456789/1666 Preparation and resistance measurements of BSCCO superconductors. Ganesan, N.Pathmanathan,; J.C.N.Rajendra, B.S.B.Karunaratna. Three Bismuth based superconducting samples with the composition.rPbQ.sSrCaCui.sOy were prepared using different solid state reaction techniques. The BiiOz* P6O, SrCOz and CuO powders o/99% purity were used as starting raw materials. The powders were mixed with the nominal cation ratio Bi : Pb : Sr : Ca : Cu = 0.7 : 0.3 : 1 : 1 : 1.5 and then mixed well using dry grinding, wet grinding and wet ball milling methods. The powders were calcined at 820°C and pallets of diameter 13 mm and thickness 1 — 2 mm were prepared from the calcined powder under 300 kg cm~2 pressure. The samples were then sintered at different appropriate temperatures. The resistance measurements at low temperatures were performed on three samples using a resistivity probe in the temperature range from 55K to 200 JFf. The samples prepared by dry grinding, wet grinding and wet ball milling methods have shown the superconducting transition Temperatures TC at 112K, 115X and IWK respectively. TCO of the three samples were found to be 7QK,8QK and 6&K respectively. In this work we developed a technique and successfully achieved a temperature as low as 55K while the resistivity probe was in liquid nitrogen. 2000-01-01T00:00:00Z http://www.digital.lib.esn.ac.lk//handle/123456789/1663 Investigation of the free steroid from palmyrah (Borassus flabellifer L.) fruit pulp J.K.Nikawala, P.Baeckstrom,; E.R.Jansz, A.M.Abeysekera The study describes the isolation of a Steroid from, palmyrah fruit pulp(PFP) by MPLC. Spectroscopic studies using 1H-NMR and 13C-NMR showed its structure to be (3 SitosteroL The steroid was isolated from PFP by extracting with methanol, cleaning with petroleum ether followed by desugaring with dry cellulose chromatography and separated by medium pressure liquid chromatography (MPLC), Mass spectrometry shown a molecular weight of 4^4- ^e rncun problem of whether the ethyl group in position 24 was a or ft was deduced from study of the literature and data banks of 13C-NMR. This was confirmed by 1H-NMR data. 2000-01-01T00:00:00Z http://www.digital.lib.esn.ac.lk//handle/123456789/1660 Glutathione is an essential metabolite required for resistance to oxidative stress and induction of stress tolerance in yeast Saccharomyces cerevisias S.Judy Arasanila, Kenneth Watson Yeast cells were depleted of glutathione by treatment with iodoacetamide and were markedly more sensitive to damage caused by free radicals generated by AAPH (2,2 f-azobis(2-amidinopropane) dihydrochloride) and H^Oi- However intrinsic tolerance to heat and ethanol were not affected. Glutathione depletion inhibited the induction of tolerance to all four stresses and the induction of heat shock protein (hsp) synthesis. It was concluded that glutathione was essential for oxidative stress tolerance and induction of tolerance to oxidative, heat and ethanol stresses. 2000-01-01T00:00:00Z