Papers by Keyword: Cryo-SEM

Abstract: Bone healing and growth are controlled by the rate of deposition of hidroxiapatite (HA). This process have been so far accredited to the work of osteoblasts, which are attracted by the electrical dipoles produced either by piezoelectricity, due to deformation of the bone, specially the collagen in it, or due to outside electrical stimuli. The present work shows that even without osteoblasts present, the piezoelectric dipoles produced by deformed collagen, can produce the precipitation of HA by electrochemical means, without catalyzer as in biomimetic deposition. These findings could clarify the contribution of osteoblasts in bone growth as compared to the electrochemical action by itself. Further studies ascertaining the osteoblastic activity due to the electric field are being advanced.

Abstract: Roman mortars from the industrial archaeological site of Tróia (Portugal) have been studied by means of chemical, mineralogical and microstructural analysis. The mortars are calcitic aerial lime mortars differing in the type and proportion of aggregates used, including crushed carbonaceous rocks (limestone and dolomite), siliceous sand and crushed ceramics. The results show that although these mortars have been subjected to a very aggressive environment they are still in a very good state of conservation.

Abstract: PI-SiO2 hybrid seamless tubular films with gradient microstructure were prepared by sol-gel insitu polymerization and rotational moulding process. Energy Dispersive X-Ray Spectrometry (EDS) and Field Emitter Scanning Electron Microscope (FE-SEM) were used to evaluate the spatial gradient distribution of SiO2 in the PI-SiO2 hybrid tubular films. The experimental results showed that the SiO2 particles were dispersed at nanoscale in the PI matrix, and that the size and the dispersivity of the SiO2 particles changed gradiently along the tubular film cross-section. The lower the SiO2 distribution density, the smaller the SiO2 particles. When the SiO2 content exceeded a certain value, some SiO2 nano-particles aggregated into nano-clusters with thyrsiform structure, and the nano-clusters aggregated more into limbate globoids.