Structure and properties of ilmenite from first principles

Published versio

Anisotropic diffusion of water molecules in hydroxyapatite nanopores

Funded by EPSRC Grant EP/K000128/1

Association of body weight and physical activity with blood pressure in a rural population in the Dikgale village of Limpopo province in South Africa

Africa is faced with an increasing burden of hypertension attributed mainly to physical inactivity and obesity. Paucity of population based evidence in the African continent hinders the implementation effective preventive and control strategies. The aim of this study was to determine the association of body weight and physical activity with blood pressure in a rural black population in the Limpopo Province of South Africa. A convenient sample of 532 subjects (396 women and 136 men) between the ages 20?95 years participated in the study. Standard anthropometric measurements, blood pressure, and physical activity were recorded by trained field workers. Anthropometric measurements showed that a high percentage of women were significantly (p < 0.001) overweight and obese than men. Hypertension was significantly high among women (38.1%) compared to men (27.9%). In the univariate analysis mean body mass index (BMI), waist circumference (WC), hip circumference (HC) and waist hip ratio (WHR) showed a significant positive association with systolic and diastolic BP in women, and only WHR was statistically significant in men. The odds of being hypertensive also increased with BMI, WC and WHR in both women and men, including HC in women. No relationship was found between physical activity and high blood pressure. In the multivariate analysis only increase in HC and WHR was consistently associated with increase in SBP in women and WHR with hypertension in men. The study findings indicate that women in this black South African rural population are overweight and obese than men and are at higher risk of hypertension as determined by selected anthropometric parameters.

Double trouble for couch potatoes: high blood pressure in a rural population in South Africa

Africa is faced with an increasing burden of hypertension, but a paucity of population-based evidence hinders effective preventive and control strategies for hypertension, write SETH MKHONTO, MUSA MABASO AND DEMETRE LABADARIOS.

Surface Characteristics of Nanocrystalline Apatites: Effect of Mg Surface Enrichment on Morphology, Surface Hydration Species, and Cationic Environments

The incorporation of foreign ions, such as Mg2+, exhibiting a biological activity for bone regeneration is presently considered as a promising route for increasing the bioactivity of bone-engineering scaffolds. In this work, the morphology, structure, and surface hydration of biomimetic nanocrystalline apatites were investigated before and after surface exchange with suchMg2+ ions, by combining chemical alterations (ion exchange,H2OD2O exchanges) and physical examinations (Fourier transform infrared spectroscopy (FTIR) and highresolution transmission electron microscopy (HRTEM)). HRTEM data suggested that the Mg2+/Ca2+ exchange process did not affect the morphology and surface topology of the apatite nanocrystals significantly, while a new phase, likely a hydrated calcium and/or magnesium phosphate, was formed in small amount for high Mg concentrations. Near-infrared (NIR) and medium-infrared (MIR) spectroscopies indicated that the samples enriched withMg2+ were found to retain more water at their surface than the Mg-free sample, both at the level of H2O coordinated to cations and adsorbed in the form of multilayers. Additionally, the H-bonding network in defective subsurface layers was also noticeably modified, indicating that the Mg2+/Ca2+ exchange involved was not limited to the surface. This work is intended to widen the present knowledge on Mg-enriched calcium phosphate-based bioactive materials intended for bone repair applications

Modelling the formation of fission tracks in apatite minerals using molecular dynamics simulations

We introduce a simple method to simulate the “ion explosion spike” mechanism of fission track formation within the framework of classical molecular dynamics. The method is applied to six apatite compositions and the resulting tracks are compared with each other as well as with the damage produced by another mechanism—the “Displacement spike”. In contrast to experimentally observed tracks, the radii of simulated tracks are not dependent on their direction in the crystal. Since the simulations model accurately the elastic response of apatites, this suggests that the experimentally observed difference in track radii for tracks along different crystal directions is not entirely caused by anisotropy in the elasticity of apatite. We suggest that anisotropy in the interactions between the electric fields of fission fragments and the crystal ions is a major factor in the final radii of fission tracks. In fluorapatite, the simulations also reveal the formation of small clusters of fluorite-like material in the core of the fission track, a phenomenon which has yet to be confirmed experimentally