Cortical and Trabecular Bone Modeling and Implications for Bone Functional Adaptation in the Mammalian Tibia

Bone modeling involves the addition of bone material through osteoblast-mediated deposition or the removal of bone material via osteoclast-mediated resorption in response to perceived changes in loads by osteocytes. This process is characterized by the independent occurrence of deposition and resorption, which can take place simultaneously at different locations within the bone due to variations in stress levels across its different regions. The principle of bone functional adaptation states that cortical and trabecular bone tissues will respond to mechanical stimuli by adjusting (i.e., bone modeling) their morphology and architecture to mechanically improve their mechanical function in line with the habitual in vivo loading direction. This principle is relevant to various research areas, such as the development of improved orthopedic implants, preventative medicine for osteopenic elderly patients, and the investigation of locomotion behavior in extinct species. In the present review, the mammalian tibia is used as an example to explore cortical and trabecular bone modeling and to examine its implications for the functional adaptation of bones. Following a short introduction and an exposition on characteristics of mechanical stimuli that influence bone modeling, a detailed critical appraisal of the literature on cortical and trabecular bone modeling and bone functional adaptation is given. By synthesizing key findings from studies involving small mammals (rodents), large mammals, and humans, it is shown that examining both cortical and trabecular bone structures is essential for understanding bone functional adaptation. A combined approach can provide a more comprehensive understanding of this significant physiological phenomenon, as each structure contributes uniquely to the phenomenon

The three Sterkfontein tibiae (StW 358, 389, 567) (upper row) and their trabecular structure 1 mm (2^nd row), 5 mm (3^ed row) and 10 mm (bottom row) below the cortex, as reveled in transverse slices by the microCT scanning.

<p>Scale bar for microCT scans is 1; thus it did not affect our segmentation process (binarization of CT slices). On the bottom right corner of the figure is an inset showing two identical enlargements of an area in StW 567; the upper image is the original, showing typical sedimentation and the bottom image is the same area after segmentation. Note the distinct and clear separation in appearance, consistency and X-ray absorption between the sediments and the actual trabecular structure in the original image.</p

Differences in ankle angle (dashed line) at midstance in humans walking normally (a), with a bent-hip bent-knee gait (b) and chimpanzees walking quadrupedally (c).

<p>Note that the ankle is more extended (plantarflexed) during midstance in humans walking normally than chimpanzees walking quadrupedally. The bottom part of the figure shows representative vertical ground reaction force traces plotted as a percentage of body weight over stance duration.</p

Polarized emission in II–VI and perovskite colloidal quantum dots

The polarized emission of colloidal quantum dots from II–VI and perovskite semiconductors were investigated thoroughly, revealing information about the optical transitions in these materials and their potential use in various opto-electronic or spintronic applications. The studies included recording of the micro-photoluminescence of individual nanostructures at cryogenic temperatures, with or without the influence of an external magnetic field. The experimental conditions enabled detection of circular and/or linear polarized emission to elucidate the exciton manifolds, angular momentum of the emitting states, Landé g-factors, single exciton and bi-exciton binding energies, the excitons’ effective Bohr radii, and the unique influence of the Rashba effect. The study advances the understanding of other phenomena such as electron–hole dissociation, long diffusion lengths, and spin coherence, facilitating appropriate design of optical and spin-based devices

Polarized emission in II-VI and perovskite colloidal quantum dots

ISSN:1361-6455ISSN:0368-3508ISSN:0953-4075ISSN:0022-370

Polarized emission in II–VI and perovskite colloidal quantum dots

The polarized emission of colloidal quantum dots from II–VI and perovskite semiconductors were investigated thoroughly, revealing information about the optical transitions in these materials and their potential use in various opto-electronic or spintronic applications. The studies included recording of the micro-photoluminescence of individual nanostructures at cryogenic temperatures, with or without the influence of an external magnetic field. The experimental conditions enabled detection of circular and/or linear polarized emission to elucidate the exciton manifolds, angular momentum of the emitting states, Landé g-factors, single exciton and bi-exciton binding energies, the excitons’ effective Bohr radii, and the unique influence of the Rashba effect. The study advances the understanding of other phenomena such as electron–hole dissociation, long diffusion lengths, and spin coherence, facilitating appropriate design of optical and spin-based devices