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  • Hepatoprotective cerebroside  (1)
  • numerical algorithm  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 19 (1987), S. 549-559 
    ISSN: 1573-8868
    Keywords: nonnegative kriging weights ; kriging equations ; nonlinear optimization ; numerical algorithm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Under a constant drift, the linear kriging estimator is considered as a weighted average ofn available sample values. Kriging weights are determined such that the estimator is unbiased and optimal. To meet these requirements, negative kriging weights are sometimes found. Use of negative weights can produce negative block grades, which makes no practical sense. In some applications, all kriging weights may be required to be nonnegative. In this paper, a derivation of a set of nonlinear equations with the nonnegative constraint is presented. A numerical algorithm also is developed for the solution of the new set of kriging equations.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-203X
    Keywords: Key wordsLycium chinense ; Hepatoprotective cerebroside ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Suspension cultures derived from Lycium chinense Miller seedlings produced significant amounts of a hepatoprotective cerebroside. Callus was induced from the stem of aseptic seedlings of L. chinense and maintained on MS solid media supplemented with 1.0 ppm 2,4-D and 0.1 ppm kinetin. Suspension cultures were established, and the cells were grown in the same liquid media in the dark. Lyophilized cells were extracted with a combined reagent of chloroform and methanol (2:1, v/v). An aqueous suspension of the evaporated cell extract was partitioned with chloroform, and the chloroform layer was subjected to silicic acid column chromatography followed by semi-preparative reverse phase C8 high pressure liquid chromatography. The purified compound showed hepatoprotective activity comparable to that shown by silymarin, and the structure was identified as 1-O-(β-d-glucopyranosyl)-(2S,3R,4E,8Z)-2-N-2′-hydroxy-(palmitoyl)-4,8-sphingadiene on the basis of spectral data. The content of the compound in cultured cell was tenfold higher than that of the fruit of L. chinense. The biosynthesis of the compound in cultured cell systems appears to parallel cell growth.
    Type of Medium: Electronic Resource
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