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M. Leite T. Eremeeva A. Treimanis V. Egle T. Bykova L. Purina U. Viesturs 《Engineering in Life Science》1995,15(2):199-209
Some effects of the xylanase treatment on the separate birch ORGANOSOLV pulp fibre wall morphological layers were examined. These investigations were focused on the outer layers, i.e. the primary wall (P) and the outer layer of the secondary wall (S1), as well as the central layers, i.e. the central layer of the secondary wall (S2) and the tertiary wall (T). Step by step, the fractionation of the pulp components in the polar solvents N,N-dimethylformamide (DMFA), dimethylsulphoxide (DMSO) and DMSO/H3PO4 was used as a mild technique for the isolation of the lignin-carbohydrate complexes. The different residual amounts of lignin and hemicelluloses in the outer and central pulp fibre wall layers as well as the different lignin-hemicellulose ratios were determined. The size-exclusion chromatographical (SEC) analysis showed a higher initial lignin content in the region of the high molecular mass (MM) fibre wall fraction extracted with “DMSO/H3PO4” than the outer cell wall layers. In the central layers, the amounts of soluble lignin (calculated on the mass of total dissolved substance) were approximately the same for all the three solvents. The xylanase treatment brought the most considerable changes in the high MM part of the residual lignin (the lignin carbohydrate complex). This was true for both the P-S1 and S2-T layers. The careful brightness comparison of the outer and central fractions after the X-E-P-P bleaching sequence showed a surprisingly low bleachability of the outer layer fraction. The xylanase action depended on the composition of the lignin-carbohydrate complex (LCC) and the extent of the maintenance of the outer layers during the pulping process. 相似文献
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Purina Ingrida Balode Maija Béchemin Christian Põder Tõnis Vérité Celine Maestrini Serge 《Hydrobiologia》2004,514(1-3):127-137
Hydrobiologia - A mesocosm experiment was used to investigate the effect of terrestrial-origin dissolved organic matter (DOM) on the development of dinoflagellates in natural summer phytoplankton... 相似文献
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Effects of nutrient enrichment on the growth rates and community structure of summer phytoplankton from the Gulf of Riga, Baltic Sea 总被引:9,自引:0,他引:9
Balode Maija; Purina Ingrida; Beechemin Christian; Maestrini Serge Y 《Journal of plankton research》1998,20(12):2251-2272
Sea water collected in mid-July was spiked with different combinationsof nutrients. Dissolved inorganic nitrogen (DIN) became exhausted,while significant amounts of P-PO4 and Si-SiO3 remained available.NH4 was taken up before NO3, but, in some cultures, NO3 uptakeappears to have started in the presence of 相似文献
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