PURSE 1996

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https://ir.lib.pdn.ac.lk/handle/20.500.14444/43

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Browsing PURSE 1996 by Author "Chandrasena, W. D."

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    Chemical Variations of Uncaria Ellipitca
    (University of Peradeniya, Peradeniya, 1996-08-10) Chandrasena, W. D.; Diyabalanage, T. K. K.; Wannigama, G. P.
    Uncaria elliptica is a woody climber, widely distributed in South and South East Asia. The species collected in Thailand and the species collected in Malaysia show chemical variations. This investigation reports chemical variations of the species within Sri Lanka itself Samples of the species were collected from the Kanneliya (KN) and Udawattakelle (UK) forest reserves. The KN plant and the UK plant showed minor differences in their triterpenoid compositions. The alkaloids of the two plants showed more striking differences. The KN plant gave ajmalicine, incorporating one molecule of tryptamine and one molecule of secologanin. The UK plant gave no ajmalicine, but gave the roxburghines, incorporating two molecules of tryptamine and one molecule of secologanin. The roxburghines are unique to the genus and among its 34 species, are found only in Uncaria elliptica.
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    Construction of an Improved Automatic Burette
    (University of Peradeniya, Peradeniya, 1996-08-10) Tennakoon, D. T. B.; Bandara, H. M. N.; Chandrasena, W. D.; Ilangantilake, A. N.
    We have previously described the construction of an automatic burette with the ability to detect the colour change at the end point. An ordinary burette modified for the purpose was used to control the addition of the titrant and the vohune was read visually. This instrument is now improved and the burette is replaced with a motor-driven plastic syringe. Once calibrated, the instrument is able to add and measure the vohune of the titrant with a high degree of accuracy. The process is fully computer controlled.