Water Mediated Collagen and Mineral Nanoparticle Interactions Guide Functional Deformation of Human Tooth Dentin

Dentin in teeth is a bone-like nanocomposite built of carbonated hydroxyapatite (cHAP) mineral particles, protein, and water. It does not remodel nor heal and is excellently adapted for decades of mechanical function, due to the interplay between its constituents. Using samples of human origin, we combine heat treatments with synchrotron X-ray diffraction, second-harmonic generation microscopy, Raman spectroscopy, and phase contrast-enhanced nanotomography to study the water-assisted functional coupling of the biocomposite components. Across roots we find a gradual reduction in the <i>c</i>-lattice parameter of the cHAP nanocrystals, from 6.894 Å externally down to 6.885 Å on the inside. Thus, the tissue formed at later stages of tooth development around the pulp contains crystals with smaller unit cells. In all regions, a compressive strain of ∼0.3% is observed upon drying by mild heating (125 °C). Dehydration also results in a substantial increase in the averaged microstrain fluctuations in the mineral nanoparticles. The mineral crystallite platelet lengths fall off from ∼36 nm externally to ∼26 nm closer to the pulp. Our results suggest that both morphology and tight mineral–collagen coupling allow mineral nanoparticles in dentin to sustain rather large stresses of 300 MPa, far exceeding mastication loads

Alloy design for additive manufacturing: Continuously reinforced Al-Ce nanocomposites

The composition Al-16Ce-1Mg has been developed as a dedicated alloy for processing by laser powder bed fusion (LPBF). Guided by thermodynamic considerations and exploiting the unique conditions during LPBF, the strongly hypereutectic alloy features nm-scale aluminum dendrites reinforced by a continuous intermetallic network. The unique temperature stability of Al-Ce alloys as well as the microstructure topology and scale grant the alloy high strength in as-printed state with excellent thermal stability. The superior mechanical properties of the continuously reinforced nanocomposite were established by comparison with the spheroidized, microstructure of similar scale

Using digital outcrops to make the high Arctic more accessible through the Svalbox database

The high Arctic is a remote place, where geoscientific research and teaching require expensive and logistically demanding expeditions to make use of the short field seasons. The absence of vegetation facilitates the use of modern photogrammetric techniques for the cost-effective generation of high-resolution digital outcrop models (DOMs). These georeferenced models can be used in pre-fieldwork activities to help prepare for traditional geological fieldwork, during fieldwork to record observations, and post-fieldwork to conduct quantitative geological analyses. Analyses of DOMs range in scale from mm-cm (e.g., size and spacing of dinosaur footprints), to hundreds of meters (e.g., seismic modeling of outcrops and outcrop-well-seismic correlations) and can advance research objectives. This integration is strengthened if key geoscientific data, like geological and topographical maps, subsurface profiles, borehole data, remote sensing data, geophysical data and DOMs can be integrated through a common database, such as the Svalbox database that we present in this commentary. Svalbox geographically targets the Svalbard archipelago, where fieldwork is challenging due to the harsh polar environment, risk of polar bear encounters and demanding transport to the field area. The University Centre in Svalbard nonetheless relies on utilizing the natural Svalbard environment for its field-based education, and now makes use of Svalbox to make geological fieldwork more efficient and post-fieldwork analyses more quantitative. Experience and usage of such tools in geoscientific education, particularly in the polar regions, is not well documented. Therefore, we share experiences on both developing and optimizing Svalbox, and on student and lecturer usage. Svalbox includes a web-based interface through which DOMs are shared and displayed together with relevant public-domain geoscientific data sets. Svalbox also serves as a platform to share student and teacher experiences on the entire DOM workflow, from acquisition to data distribution. For the Svalbox users questioned by the project group, DOMs were found to provide many benefits, including quantitative analyses, extended field season, appreciation of scale and data sharing that significantly outweigh present-day challenges, such as the need for expensive hardware and lack of easily accessible interpretation software, the latter being surmountable within the near-term