Xyloglucans are water-soluble polysaccharides that serve as storage in cotyledonary tissues from seeds of Hymenaea courbaril among other Leguminosae. The use of xyloglucans is dependent on their solution properties. We now examine the influence of different times of extractions on its properties. Xyloglucans were obtained from milled and defatted cotyledons of H. courbaril by aqueous extraction at 25 degrees C for 0.25, 0.5, 1, 5, 15, 24, and 48 h. Composition data showed that increase in time lead to the increased protein contamination and arabinose content. Xyloglucans obtained with longer times of extraction had an average molar mass greater than those obtained with shorter times. The hydrodynamic radius and the radius of gyration also increased with the increase in the time of extraction. The ratio R(g)/R(h) was calculated and the values decreased slightly for increasing times of extraction. The effect of time also affected the viscosity which increased with the increase in time of extraction, and the longer ones probably contributing to the aggregation of xyloglucans.
β-tricalcium phosphate based ceramics (β-TCP) are resorbable biomaterials used as bone substitutive materials. Several ions can substitute specific Ca positions in the crystalline structure of TCP, so that general Me-TCP can be obtained. Particularly, magnesium can increase the temperature of β-α-TCP transformation while zinc stimulates the bone formation. In this work, the influence of magnesium or zinc ions on the sintering behavior of Me-TCP was investigated. The powders were produced through wet chemical synthesis with a freeze drying process. The powders were calcined and subsequently uniaxially pressed into pellets. The pellets were sintered up to 1300°C/1h. The influence of Mg or Zn doping was investigated by dilatometric studies, thermal analysis and XRD. The microstructure was evaluated through SEM. The results suggest that Mg increased temperature of β-α-TCP phase transformation. The Me-doped TCP samples can be considered as promising biomaterials, having stimulatory effect of Zn or suitable densification due to Mg addition.
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