PubMed · 2288685
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L Baggi, L Cianconi, L Venanzi. [Ceramic onlays: light microscope study].. https://pubmed.ncbi.nlm.nih.gov/2288685/
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When single crystals of two different materials are in contact at a sharp interface, the orientation relationship between them is said to be epitaxial and the configuration of the atoms at the two sides of the interface is such that the lattice mismatch between them is accommodated in the least energetic way. Among other factors, this depends on the bonding between the atoms on the two sides of the interface. In this paper, the relaxation of strain in thin films grown epitaxially on dissimilar substrates is first discussed theoretically for cases of small and large lattice mismatch. In a following section, two metal-ceramics heteroepitaxial systems are investigated in detail by various techniques of transmission electron microscopy. One case, vanadium on MgO, corresponds to a small-mismatched system and the interface changes from coherent to semicoherent above a critical thickness; this turns out to be much larger than the expected value. In the other case-vanadium on the basal and rhombohedral (R) planes of sapphire-the lattice mismatch is large and misfit dislocations exist from the very initial stages of deposition. It is argued that although misfit dislocations in small and large lattice-mismatched systems are geometrically similar, their physical nature is different.
Glass-reinforced HA composites were produced using phosphate-based glasses, and a structure refinement was carried out to determine the effect of the glass on the structure of the residual HA. Quantitative phase analysis showed that the glass causes some of the HA to decompose to beta-TCP and, at higher temperatures, to alpha-TCP. It also was indicated that when three phases were present, the formation of the alpha-TCP arose from decomposition of the beta-TCP and not from further decomposition of HA to alpha-TCP. The unit cell dimensions showed a decrease in the a axis and an increase in the c axis, giving an overall unit cell decrease in volume. There also was a significant effect based on the amount of glass added. The changes found in the composite containing the 4 wt% glass were attributed to the loss of carbonate and loss of hydroxyl. This was expected to cause shrinkage in the unit cell; however this was not seen, and therefore the major changes in the unit cell were attributed to the ions from the glass taking an interstitial role in the HA structure, thus not allowing the unit cell to shrink as much as expected.
Non-thermal effect of a ceramics radiation on glucose-6-phosphate dehydrogenase has been investigated using the enzyme, glucose-6-phosphate and NADP+ separately irradiated at 10 degrees C by a ceracompo R plate and a ceramics un-sewed cloth (sheet). The Km for glucose-6-phosphate was increased 20% after 6 h of irradiation by the plate, but the Vmax/Km was decreased 24%. After 3 h of irradiation by the sheet, the Km was increased 17%, but after 6 h of irradiation it was decreased 11%. The 3 h of irradiation by the sheet slightly increased both enthalpy and entropy changes of the reaction, but the 6 h of irradiation significantly decreased them. Both thermodynamic parameters in the activated state were increased by the sheet irradiation. The promotion energy for both formations of the enzyme-substrate and their activated complex depended on enthalpy. The different effects of two ceramics radiators on G6PDH activity were discussed.