Curved mineral platelets in bone.

Bone is a composite material principally made up of a mineral phase (apatite) and collagen fibrils. The mineral component of bone occurs in the form of polycrystalline platelets 2-6 nm in thickness. These platelets are packed and probably glued together in stacks of two or more, ranging up to >30 platelets.

Improved Method for Electron Powder Diffraction-Based Rietveld Analysis of Nanomaterials.

Multiphase nanomaterials are of increasing importance in material science. Providing reliable and statistically meaningful information on their average nanostructure is essential for synthesis control and applications. In this paper, we propose a novel procedure that simplifies and makes more effective the electron powder diffraction-based Rietveld analysis of nanomaterials.

A novel image processing procedure for the quantitative evaluation of dental enamel prism arrangement.

Enamel prism is the main microstructural unit of mammalian enamel which composed of hundreds of bioapatite nanocrystals. Prism structure plays a key role in the excellent mechanical performance of dental enamel during millions of chewing cycles without significant remodeling. Thus, quantitative understanding of prism architecture is of utmost importance for biomechanical materials design.

Acquisition and evaluation procedure to improve the accuracy of SAED.

The achievement of this work is that fine tuning of experimental and evaluation parameters can improve the absolute accuracy and reproducibility of selected area electron diffraction (SAED) to 0.1% without using internal standard. Due to the proposed procedure it was possible to reach a reproducibility better than 0.

Study of the Microstructure of Amorphous Silica Nanostructures Using High-Resolution Electron Microscopy, Electron Energy Loss Spectroscopy, X-ray Powder Diffraction, and Electron Pair Distribution Function.

Silica has many industrial (i.e., glass formers) and scientific applications.

Magnesium incorporation into primary dental enamel and its effect on mechanical properties.

Cross-sectional study of sound primary dental enamel revealed hardness zonation and, in parallel, significant change in the Mg content below the prismless layer. Mg content is known to play an important role in enamel apatite biomineralization, therefore, Mg ion exchange experiments were carried out on the outer surface of sound primary molars and on reference abiogenic Ca-phosphates using MgCl solution. Effects of Mg incorporation on crystal/particle size, ionic ratio and morphology were compared and the observed changes were explained by parallel diffusion and dissolution/reprecipitation processes.

The Influence of Preparation Conditions on the Hydrogen Sorption of Mg-Nb₂O-CNT Produced by Ball Milling and Subsequent High-Pressure Torsion.

High energy ball milling and subsequent high-pressure torsion method was carried out on nanocrystalline Mg powders catalyzed by 5 wt.% Nb₂O and 5 wt.% carbon nanotubes.

HRTEM study of individual bone apatite nanocrystals reveals symmetry reduction with respect to P6/m apatite.

In this study we present the first crystal structure model for bone apatite based on the analysis of individual nanocrystals by high resolution transmission electron microscopy (HRTEM). Crystallographic image processing of the obtained HRTEM images from different projections indicates symmetry reduction with respect to P6/m stoichiometric apatites and the presence of threefold symmetry along the c axis. Based on HRTEM observations and the measured Ca/P = 2 ratio we propose a structural model with phosphate-to-carbonate substitution and O vacancies localized along c axis, which explains the observed loss of 6 screw axis parallel, and the shift of mirror plane perpendicular to the c axis.

Association of individual soil mineral constituents and heavy metals as studied by sorption experiments and analytical electron microscopy analyses.

Sorption characteristics of bulk soil samples and discrete soil mineral constituents were studied by Cu, Zn and Pb batch sorption experiments and analytical electron microscopy analyses. Copper and zinc sorbed mostly on soil mineral constituents, while lead was associated mainly to soil organic matter. Additionally, the competitive situation resulted in increase of the role of iron oxides in Pb sorption.

Sorption of copper, zinc and lead on soil mineral phases.

Soil mineral phases play a significant role in controlling heavy metal mobility in soils. The effective study of their relation needs the integrated use of several analytical methods. In this study, analytical electron microscopy analyses were combined with sequential chemical extractions on soils spiked with Cu, Zn and Pb.