http://dr.lib.sjp.ac.lk/handle/123456789/1165 2026-05-06T14:27:03Z 2026-05-06T14:27:03Z Hapuhinna, H.K.G.K.D.K http://dr.lib.sjp.ac.lk/handle/123456789/12726 2023-04-11T05:04:35Z 2022-01-01T00:00:00Z

SYNTHESIS AND CHARACTERIZATION OF CERAMIC COMPOSITES DERIVED FROM EPPAWALA APATITE FOR AUTOMOTIVE AND INDUSTRIAL APPLICATIONS Hapuhinna, H.K.G.K.D.K The Sri Lankan Eppawala rock phosphate deposit, found in the North Central province, is a non-renewable natural resource that does not replenish over humanly meaningful time scales. It contains nearly 34% to 40% phosphorous pentoxide (P2O5). Even though there are numerous viable and value-added phosphorous (P) industries, Sri Lanka exports rock phosphate as a raw material at lower prices to other developed nations. Considering its resource-related wealth, it is a timely requirement to obtain the proper compensation for this non-renewable resource. Therefore, it is crucial to consider developing and commercializing fresh P-related finds from the Eppawala rock phosphate deposit. In order to value add Eppawala high-grade rock phosphate (HERP), this dissertation thoroughly and critically discusses three patented innovative processes (sol-gel alcoholic route, solgel acidified route, and solid-state sintering technique) for synthesizing three patented nano-hydroxyapatite (HAp) ceramic varieties. It provides significant insights into processcomposites incorporating those synthesized HAp ceramic varieties withdifferent polymers [methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA)], polyester, epoxy, glass fibers, silicon carbide (SiC) and boron nitride (BN) which can be used for several biomedical, automotive and industrial applications. Synthesized nanoHAp ceramic varieties and processed HAp incorporated composites were characterized using X-ray fluorescence spectroscopy (XRF), particle size analysis (PSA), X-ray diffraction spectroscopy (XRD), fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM with EDS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), tensile tests, and impact tests in order to find out composition, the size distribution of particles, crystallographic structure, identification of functional groups, the morphology of micro/nanostructures, glass transition temperatures, thermal stability, thermomechanical properties, tensile properties, and impact strength. American society for testing and materials (ASTM) standards were applied for all mechanical analyses. This dissertation compared those results with human hard tissues, commercial products, and literature according to their nature of applications. It has been concluded that HAp can be synthesized using the three routes to add value, HERP. These methods are highly cost-effective. Synthesized hexagonal, nano-HAp products perform similarly in chemical composition and structure to mammalian hard tissues via exhibiting different characteristics as bioceramic. The resulting composite materials obtained after reinforcing hydroxyapatite ceramic products with MMA and HEMA orderly for orthopedics and dentistry applications have proven that their performances are better than commercial products. It shows the highly profitable possibility of introducing Eppawala HAp products into the market as value-added bioceramic and its composites. Processed HAp incorporated E-glass fiber reinforced polyester matrix composites and ceramic (HAp/SiC/BN) incorporated epoxy matrix composites in this study demonstrate better properties than pure polyester and epoxy materials. Resulted composites can be used for automotive and aircraft applications. Also, it has confirmed the possibility of processing SiC and BN incorporated HAp composites under high temperatures (1600°C-1650°C), for other relevant industrial applications.

2022-01-01T00:00:00Z SUMATHIPALA, M.P.R. http://dr.lib.sjp.ac.lk/handle/123456789/3093 2023-03-21T05:56:51Z 2016-10-05T09:31:52Z

STUDY ON THE CHEMISTRY AND BIO ACTIVITY OF SOME MEDICINAL PLANTS OF SRI LANKA SUMATHIPALA, M.P.R. Attached; Centella asiatica (Umbelliferae) and Aegle marmelos (Rutaceae) are widely used as a ve~etable and a fruit respectively. These two plants are used in Ayurvedic and indigenous medicinal systems in Sri Lanka. Earlier researchers have reported the effect of aqueous extracts of these two plants on the classical and alternative pathways of activation of human complement in vitro. Activity directed fractionation of the aqueous extracts indicated that most of the activity was confined to the polysaccharide fraction. This thesis reports the preliminary chemical analysis of the polysaccharide fraction of Centella asiatica and Ae~le marmelos. These polysaccharides were hydrolysed and methanolysed. T.L.C and H.P.L.C analysis were done for analysing their monomer composition. The immunomodulating activity and Biological activity of these fractions using the .~emia bio assay were studied.

2016-10-05T09:31:52Z MENIKE, A.M.S.C. http://dr.lib.sjp.ac.lk/handle/123456789/3092 2023-03-24T05:20:13Z 2016-10-05T09:30:08Z

Study of The Chemistry and Technology of Ayuruvedic Preparations MENIKE, A.M.S.C. Attached; Vasakarishtaya is a fermented ayurvedic drug prepared by using the root bark extract or A. vasica as the main ingredient with 10 other secondary (Kalka) plant ingredients. Vasakarishtaya showed significant activity on three selection in-vitro immunoassays involving human complement and polymorphonuclear leukocytes indicating that this drug may influence both the humoral and the cellular components of the human immune system. The main ingredient of Vasakarishtaya A. vasica showed moderate activity on the three immune assays. On prolonged boiling, the root bark extract of A. vasica showed decreased inhibition of the classical pathway of complement activation and increased inhibition of the production of chemiluminescence by activated polymorphonuclear leukocytes. Thus the standardadization of the boiling time is an important factor in the quality control of this drug. Some practitioners use a combination of root bark and leaves as the main ingredient for the preparation of Vasakarishtaya. A mixture of root bark and leaves of A. vasica showed higher inhibitory activity in classical pathway compared to the root bark. Compared to the immune activity of the main ingredient most of the secondary plants showed higher immunomodulatory activity. During fermentation immunomodulatory activity of Vasakarishtaya remarkably increased after addition of secondary plants. Secondary plants play a major role in the Vasakarishtaya fermentation. W. fruticosa flowers which represent 54% of the secondary plants are responsible for important changes in the fermentation medum. It lowers the pH by releasing gallic acid into the fermentation medum. This pH drop is important to the activity of invertase enzyme. At low pH (3.5-4.5) sucrose was hydrolysed to glucose and fructose by invertas present in the W. fruticosa flowers. This accelerates the initiation of fermentation by yeasts. Irradiation experiments clearly demonstrated that the source of invertase was not microbial, of the secondary plants. W. fruticosa plays the major role in the fermentation. On the other hand secondary plants increases the immunomodulatory activity of Vasakarishtaya significantly increased after the addition of secondary plants. Secondary plants add some immune active compounds into the preparation such as gallic acid. Vanillie acid and syringic acid. These phenolic acid are inhibitors of chemiluminescence production by polymorphonuclear leukocytes induced by serum treated zymosan. Alkaloide of A. vasica were found to be immune active. During prolonged extraction, the alialoid contents increased however, 90% of vasicine, 83% of vasicinone and 76% of vasicinolone were extracted at the end of the first day. During fermentation the vasicine content slightly decreased and vasicinone and vasicinolone contents slightly increased. Fermentative organisms were not found in the ingredients. Saccharomyces cerevisiae yeast was identified in the commercial and standard Vasakarishtaya. Zyoosaccromyces bisporus was also found in the standard (laboratory prepared) Vasakarishtaya. Bscillus cereus was found in one of the commercial (Bimal) samples as well as in the standard Vasakarishtaya. It would appear that the source of microorganisms for this traditional fermentation is the environment. Immunomodulatory activities were similar in both commercial Vasakarishtaya samples. The standard preparation showed highest anticomplementary activity. Most of the physicochemical parameters were similar to each other in the commercial products and the standard product. Maximum immunomodulatory activity and constant values of physic-chemical parameters were obtained at the end of the traditional 30 days fermentation period in the standard preparation of Vasakarishtaya.

2016-10-05T09:30:08Z De Silva, K. Tuley http://dr.lib.sjp.ac.lk/handle/123456789/3086 2023-03-21T05:54:29Z 2016-10-05T09:21:13Z

PHAMACOGNOSTIC AUTHENTICATION AND STANDARDIZATION OF CRUDEPRODUCTS FROM INGIBERACEAE AND RUTACEAE De Silva, K. Tuley Attached

2016-10-05T09:21:13Z