Tomographic X-ray scattering based on invariant reconstruction: analysis of the 3D nanostructure of bovine bone

Small-angle X-ray scattering (SAXS) is an effective characterization technique for multi-phase nanocomposites. The structural complexity and heterogeneity of biological materials require the development of new techniques for the 3D characterization of their hierarchical structures. Emerging SAXS tomographic methods allow reconstruction of the 3D scattering pattern in each voxel but are costly in terms of synchrotron measurement time and computer time. To address this problem, an approach has been developed based on the reconstruction of SAXS invariants to allow for fast 3D characterization of nanostructured inhomogeneous materials. SAXS invariants are scalars replacing the 3D scattering patterns in each voxel, thus simplifying the 6D reconstruction problem to several 3D ones. Standard procedures for tomographic reconstruction can be directly adapted for this problem. The procedure is demonstrated by determining the distribution of the nanometric bone mineral particle thickness (T parameter) throughout a macroscopic 3D volume of bovine cortical bone. The T parameter maps display spatial patterns of particle thickness in fibrolamellar bone units. Spatial correlation between the mineral nanostructure and microscopic features reveals that the mineral particles are particularly thin in the vicinity of vascular channels.

Development of Nanosized Mica Particles from Natural Mica by Sonication/Organic Intercalation Method for Pearlescent Pigment

In this study, the possibility of reducing natural mica particles to nanosizes without damaging its surface properties and smooth flake shape for pearlescent pigment application was investigated by using the sonication delamination method. For this purpose, the layer charge density of the natural mica mineral was reduced using surfactant intercalation followed by maximum exfoliation of mica interlayers with the help of sonication. Therefore, the delamination was achieved in a simple and more energy-efficient way by the sonication process and, in turn, the dimensions of mica were reduced to nanoscale with smooth surface features. With this new delamination process, the lowest particle thickness values were obtained as 0.061 microns after only 1 h sonication period. The results were found to be much significant when compared to the literature. Furthermore, the unique pearlescent pigment properties of mica particles were attributed to the characteristic shape and nanosized mica, which are coated with TiO2.

In situ detection of protein corona on single particle by rotational diffusivity

The volume-dependent rotational diffusion coefficient of gold nanorod was used to monitor the formation of protein corona in homogeneous solution in real time. The detection of particle thickness change could reach subnanometer sensitivity.

Influence of fabric variables on clay–water–air capillary meniscus

The mechanical behavior of unsaturated clays is strongly governed by capillary water and the resulting capillary forces. In this paper, the influence of fabric variables on the air–water capillary meniscus between clay particles is studied using molecular dynamics. Considering a system of two clay particles, the fabric variables studied are the angle between particles, edge-to-face separation, clay–water contact length, and particle thickness. The molecular dynamic results are analyzed to determine the contact angle and radius of curvature of the meniscus. It is found that the values of the contact angle fall within a narrow range for the fabric variables considered. The radius of curvature varies with the spacing and angle, but is derivable from knowledge of the contact angle.

Effects of Polyvinyl Pyrrolidone on Electromagnetic Properties of Hexagonal Ferrite Prepared by the Sol-Gel Method

Ba(Zn0.3Co0.7)2Fe16O27hexagonal ferrites have been prepared by sol-gel method. Effects of polyvinyl pyrrolidone (PVP) on crystalline phase, natural surface and electromagnetic properties were analyzed. The XRD patterns of samples with and without PVP added both showed the single phase of hexagonal ferrite. The particle thickness increased when PVP was added. Moreover, Ferrites prepared with 2.0g PVP added into the sol solution had lower complex permittivity. Addition of PVP can be an effective way to obtain the electromagnetic match of hexagonal ferrites.