Curtin University of Technology - Department of Mechanical Engineering including Mechatronics - Staff - Dr Ian Davies - Publications

[50] I. M. Low, N. Duraman, and I. J. Davies, "Microstructure–property relationships in human adult and baby canine teeth", Key. Eng. Maters., 309-311 pp. 23-26 (2006).

Abstract: Structure-property relationships in baby and adult teeth have been characterised using grazing-incidence synchrotron radiation diffraction and Vickers indentation. Similarities and differences between both types of teeth have been highlighted and discussed. Depth profiling results indicated the existence of contrasting but distinct gradual changes in crystal disorder, phase abundance, crystallite size and hardness within the baby and adult canine enamel, thus confirming the graded nature of human teeth. When compared to the adult tooth, the baby enamel is softer, more prone to fracture, but has larger hydroxyapatite grains.

[49] I. M. Low, W. K. Pang, and I. J. Davies, "Mapping the microstructure–property relationships in cortical bone", Key. Eng. Maters., 309-311 pp. 523-526 (2006).

Abstract: Structure-property relationships in bovine cortical bone have been characterised using grazing-incidence synchrotron radiation diffraction, Vickers indentation and mechanical testing. Depth profiling results indicated the existence of distinct gradual changes in crystal disorder, phase abundance, and texture of hydroxyapatite whilst the crystallite size was depth-independent.

[48] T. Umeda, K. Itatani, H. Mochizuki, I. J. Davies, Y. Musha, and S. Koda, "Properties of calcium phosphate powder prepared from phosphoryl oligosaccharides of calcium", Key. Eng. Maters., 309-311 pp. 515-518 (2006).

Abstract: The phosphoryl oligosaccharides of calcium (POC), extracted from potato starch, are composed of phosphorus oligosaccharides and calcium ions. Ultrafine calcium phosphate particles, whose main phase was hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂: HAp), could be prepared through the hydrothermal-treatment of POC solution at a temperature between 110 and 130 ^oC; X-ray diffraction indicated the crystallinity of HAp in the resulting powder to be poor and similar to that of living bone. The present HAp powder was regarded to be calcium deficient carbonate apatite with the OH group being partly substituted by a carbonate (CO₃^2-) group. The solubility of the resulting powder in dilute hydrochloric acid was higher compared to that of commercially available HAp.

[47] K. Itatani, H. Itokazu, T. Umeda, I. J. Davies, Y. Musha, K. Mizutani, and S. Koda, "Preparation of hollow and spherical β-calcium orthophosphate agglomerates: Effect of organic compound addition to the spraying solution", Key. Eng. Maters., 309-311 pp. 129-132 (2006).

Abstract: Hollow and spherical β-calcium orthophosphate (β-Ca₃(PO₄)₂: β-TCP) agglomerates were prepared by the spray-pyrolysis of solution containing 1.8 mol∙dm^-3 of Ca(NO₃)₂, 1.2 mol∙dm^-3 of (NH₄)2HPO₄, 0.1~0.4 mol∙dm^-3 of organic compounds (citric acid, L-maleic acid and glutaric acid) and concentrated HNO₃ at 600 ^oC, using an air-liquid nozzle. This spray-pyrolyzed β-TCP powder was further heat-treated at 900 ^oC for 10 min in order to produce the porous agglomerates following burnout of residual carbon. Regardless of the different organics compound utilized (concentration in the starting solution: 0.2 mol∙dm^-3), most of the agglomerate diameters were in the range of 1 to 4 µm. The specific surface areas were arranged as follows: 10.5 m²∙g^-1 (glutaric acid) > 8.4 m²∙g^-1 (L-maleic acid) > 6.5 m²∙g^-1 (citric acid) > 1.7 m²∙g^-1 (no addition). Pore-size distributions for the three kinds of agglomerates indicated the majority of pore sizes to be approximately 1 µm. The dissolution of Ca and P ions from the β-TCP powder into physiological saline was faster compared to that of powders spray-pyrolyzed without the use of an organic compound, suggesting excellent bioabsorbability for the present powders.

[46] N. Duraman, I. M. Low, J. Fulton, N. Tezuka, and I. J. Davies, "A comparative study of the microstructure-property relationship in human adult and baby teeth", Ceram. Eng. Sci. Proc., 26(6) pp. 145-152 (2005).

Abstract: The structure-property relationship in human adult and baby teeth was characterised by grazing-incidence synchrotron radiation diffraction, optical and atomic-force microscopy, in addition to Vickers indentation. Similarities and differences between both types of teeth have been highlighted and discussed. The depth profiling of hardness indicated a gradual change in microhardness from the enamel to dentine, thus confirming the graded nature of human teeth. Vickers hardness of the enamel was load-dependent but load-independent in the dentine. The use of a “bonded-interface” technique revealed the nature and evolution of deformation-microfracture damage around and beneath Vickers contacts.