Nanoscale 3D mapping of biomineral composition and properties in human bone
Bibliographic record
Abstract
Bone has a complex hierarchical structure with structural motifs ranging from the nm-mm scale, giving rise to the unique mechanical and biological properties of bone. Many other biological materials present such hierarchical structures, which are very challenging to unravel. While the structure of human bone is well characterized down to the microscopic scale, the bone structure at the sub-100 µm is still debated with many structural and medical questions remaining unanswered. Studying this nanostructured hierarchical material at the nanoscale is challenging due to its complex 3D structure. One route to study such materials is X-ray powder diffraction computed tomography (XRD-CT) that reveals the 3D distribution of crystalline phases and X-ray fluorescence computed tomography (XRF-CT) that provides element distributions. We will present how we have used this technique at beamline P06, DESY, to map spatio/temporal variations in the biomineral across an osteon of human bone with 400 nm voxel size1. This allowed us to show that the microstructural properties of bone mineral is non-homogeneous and highly dependent on the time point at which it was laid down. Through further development of combined XRD-CT and XRF-CT, we have increased the 3D resolution of the technique below 120 nm opening the path for studying the next structural regime in bone2. With upgraded synchrotron sources, fast scanning motors, and high quality sample stages, the scan time of scanning XRD and XRF could decrease significantly allowing for probing larger volumes and multiple samples. This would enable new possibilities for unravelling the structure of hierarchical materials, both biological and synthetic. Γ 1. Wittig, N. K.; Palle, J.; Østergaard, M.; Frølich, S.; Birkbak, M. E.; Spiers, K.; Garrevoet, J.; Birkedal, H., Bone Biomineral Properties Vary across Human Osteonal Bone. ACS Nano 2019, 13, 12949-12956. 2. Palle, J.; Wittig, N. K.; Kubec, A.; Niese, S.; Rosenthal, M.; Burghammer, M.; Grünewald, T. A.; Birkedal, H., Nanobeam X-ray fluorescence and diffraction computed tomography on human bone with a resolution better than 120 nm. J. Struct. Biol. 2020, 212, 107631.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".