Vacuum press drying studies on two fast-growing Indian wood species

Two fast-growing Indian species, Melia composita Benth. and Eucalyptus tereticornis Sm., which have different sets of physical properties, were dried together in a vacuum press dryer(VPD) under two drying conditions,i.e., above boiling point(ABP) and below boiling point(BBP). The ABP and BBP conditions were maintained by keeping the temperature constant at 75 ℃ and maintaining two pressure levels: 300 mm of Hg(ABP) and 450 mm of Hg(BBP). In order to understand pressure conditions at the core during vacuum drying, a cylindrical brass pipe was inserted in both wood cores and attached with pressure gauges placed outside of the VPD. The results indicate that the Melia wood core attained equilibrium pressure immediately with the pressure of VPD, while Eucalyptus attained it very slowly, reaching equilibrium at later stages of drying when cracks and checks advanced to the core.The drying rate was higher for Melia than Eucalyptus under both drying conditions. The drying rate of Melia(ABP) was higher than Melia(BBP), however, the drying rate for Eucalyptus(ABP) was not significantly different from the BBP drying rate.

Preparation and characterization of bioactive glass tablets and evaluation of bioactivity and cytotoxicity in vitro

In this study, the SiO2eCaOeP2O5 ternary component of bioactive glass particles were successfullysynthesized by sol-gel method, then the bioactive glass particles were pressed into tablets with drypressing molding technology. The physicochemical structure, in-vitro bioactivity and biocompatibility ofBG tablets were characterized by various methods, such as XRD、SEM、FTIR, etc. The results showedthat the sol-gel bioactive glass particle was distinguished with its amorphous structure and micron-size.After being soaked in Tris-Hcl solution for 15 d, the bioactive glass tablets didn't collapse. Also, themineralization assay in vitro showed that the bioactive glass tablets had good capability of inducing theformation of hydroxycarbonate apatite (HCA) after being immersed in simulated body fluid (SBF). Inaddition, the cytotoxicity assay indicated that the osteoblast (MC3T3) grew well on the surface ofbioactive glass tablets. According to the above results, the bioactive glass tablets presented good mechanicalstrength, excellent apatite-forming activity and high biocompatibility, which demonstratedtheir potential applications in the field of bone defect repairing.