Transverse thermoelectric devices produce electric fields perpendicular to an incident heat flux. Classically, this process is driven by the Nernst effect in bulk solids, wherein a magnetic field generates a Lorentz force on thermally excited electrons. The spin Seebeck effect also produces magnetization-dependent transverse electric fields. It is traditionally observed in thin metallic films deposited on electrically insulating ferromagnets, but the films' high resistance limits thermoelectric conversion efficiency. Combining Nernst and spin Seebeck effect in bulk materials would enable devices with simultaneously large transverse thermopower and low electrical resistance. Here we demonstrate experimentally that this is possible in composites of conducting ferromagnets (Ni or MnBi) containing metallic nanoparticles with strong spin–orbit interactions (Pt or Au). These materials display positive shifts in transverse thermopower attributable to inverse spin Hall electric fields in the nanoparticles. This more than doubles the power output of the Ni-Pt materials, establishing proof of principle that the spin Seebeck effect persists in bulk nanocomposites.

Xenon plasma focused ion beam (FIB) technology has the potential to investigate large volumes, hundreds of micrometers in size whilst retaining the high resolution of SEM imaging. Three different materials, an aluminum alloy, a zirconium-based metallic glass, and a tungsten carbide-cobalt hard metal, were subject to serial sectioning to build up 3D microstructural images. Lastly a sample of human dentine was shaped into a pillar for analysis using nanoscale X-ray CT. The plasma FIB broadens the range of length scales, which can be investigated and holds significant promise for bringing new understanding of complex microstructures.

We provide the first conclusive evidence for the presence of exogenous calcium fatty acid deposits, which not only form in-between the cuticle layers in the lipid-rich cell membrane complex, but also grow to dimensions large enough to cause the structure to bulge, thereby impacting the optical and mechanical properties of the hair fiber. The composition and phase of these deposits were probed using a multimodal analytical approach with spatially resolved techniques including synchrotron micro X-ray fluorescence coupled with X-ray scattering, focused ion beam (FIB)-scanning electron microscopy (SEM), scanning transmission electron microscopy, X-ray energy dispersive spectroscopy, and Fourier transform infrared and Raman imaging where the collective analysis is consistent with a meso-phase composed of calcium C16/C18 saturated fatty acids from natural sources such as sebum. X-ray microtomography and serial “slice and view” FIB/SEM both reveal the location and volumetric shape of the deposits.

3D characterization [1, 2] is of particular importance in the study of mineralized tissues such as teeth and bones due to the presence of channels, pores and features that span millimeter, micrometer and nanometer length scales. The major component in human teeth, by weight and volume, is dentine. This hydrated hard tissue encloses the central pulp and has microscopic channels, dentineal tubules that radiate from the pulp to the cementum on the surface of the dentine that connects with the hard outer enamel. The permeability provided by these tubules can cause dental hypersensitivity. The object of our current work is to understand how treatments for dental hypersensitivity act on these tubules.This requires and understanding of chemical changes on the nanometer scale using techniques such as scanning transmission electron microscopy (STEM) combined with analytical methods such as energy dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS). In particular, techniques such as x-ray computed tomography (micro-CT/nano-CT), S/TEM-HAADF imaging, Focused Ion Beam (FIB) sample preparation, Super-X XEDS and dual-EELS have been used to investigate the ultrastructure and chemistry of the human dentine specimen. Results on the 3D characterization of human dentine including the segmentation of dentine microtubules, peritubular dentine, as well as the role of dentine "nano-tubules" that branch off from the primary microtubules, will be discussed.The human tooth sample was provided by GlaxoSmithKline Oral Healthcare, Weybridge, UK and was obtained with appropriate informed consent. Specifically the sample was a coronal dentine disc taken from below the enamel dentine junction and above the pulp cavity of the tooth by sectioning with a diamond tipped saw and the cut surfaces polished to a 2500 silicon carbide finish. The multi-scale correlative approach for this work consisted of five different steps at increasingly smaller length scales. The multi-scale correlative approach, seen in Figure 1, are divided into subcategories: a) Whole Dentine b) Micro-drilled (MD) Dentine c) Pillar d) Micro-cylinder and e) TEM sample. When the datasets were collected, organized, and prepped for correlation, the combination of MIPAR™ and Avizo™ software programs were used to combine all of the 3D visualization datasets. The volume -of -interest was located and visualized across all five datasets in video format.In order to reliably and reproducibly identify the specific region and orientation for the FIB-SEM studies we utilized 3-D datasets using micro-CT and nano-CT methods from dentine specimens with suitable fiducial markers. Following XMT examination and FIB sample preparation, a monochromated Titan™ 60-300 STEM equipped with a Super-X XEDS collection system was used to investigate the dentine at the atomic scale.This work has resulted in unparalleled characterization of human dentine at four different length scales. The combination of micro-CT, nano-CT, FIB, Super-X XEDS, has been applied successfully to characterize t...

Preparing hair samples for electron microscopy has been problematic for various reasons. Keratinized hair is densely packed and inherently dry with the proteins heavily cross-linked[1]. This eliminates the need for primary and secondary fixation. However, the inability to uniformly stain through the cuticle layers and throughout the central cortex has shown varying results[1]. The hair samples in this investigation were treated with an oxidative permanent colorant and washed in tap water containing low levels of copper (Cu). The amount of Cu in the hair was confirmed using inductively coupled plasma optical emission spectroscopy (ICP-OES). In order to optimize and better understand the effect of sample preparation on maintaining the native hair structure as well as internal chemical composition, analytical electron microscopy (AEM) characterization was performed [2,3]. In particular, techniques such as S/TEM-HAADF imaging and Super-X XEDS were used to investigate the ultrastructure and chemistry of the cross sectional surface of several hair fibers.