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Aim of the present study was the establishment of an efficient and reproducible model for irradiation of rat femora as a model for impaired osteogenesis and angiogenesis. Four different irradiation protocols were compared: single irradiation of the left femur with 20 Gy and explantation after 4 or 8 weeks (group A, B) and three irradiation fractions at 3-4 days intervals with 10 Gy and explantation after 4 or 8 weeks (group C, D). The contralateral, unirradiated femur served as control. Evaluation included histology, microcomputertomography (μCT), and real-time polymerase chain reaction. Histology showed a pronounced increase of vacuoles in bone marrow after irradiation, especially after 4 weeks (group A and C), demonstrating bone marrow edema and fatty degeneration. Irradiation provoked a decrease of total cell numbers in cortical bone and of hypoxia-inducible factor 1 alpha (HIF1α)-positive cells in bone marrow. The expression of several markers (osteocalcin [OCN], runt-related transcription factor 2 [RUNX2], transforming growth factor beta 1 [TGFβ1], tumor necrosis factor alpha [TNFα], vascular endothelial growth factor A [VEGFA], and HIF1α) was decreased in group A after irradiation. This might suggest a decreased metabolism after irradiation. A significant decrease in small-sized vessels was seen in μCT evaluation in group A and D. Single irradiation with 20 Gy had the most severe and reproducible impact on osteogenesis and angiogenesis after 4 weeks while being well tolerated by all animals, thus making it an excellent model for evaluation of bone healing and vascularization in irradiated tissue.

The small‐signal direct piezoelectric coefficient and dielectric permittivity are characterized as a function of temperature from 25 to 450 °C and uniaxial compressive stress up to 80 MPa in porous Pb(Zr,Ti)O3 (PZT; 10, 20, 30, 40, and 50 vol% porosity). Results show retention of piezoelectric response throughout the temperature range with increasing porosity up to 30 vol%, above which a subsequent decrease is observed. Similarly, increasing porosity did not result in a significant change of the depolarization temperature, although a slight increase in the Curie point is observed with increasing porosity. Macroscopic experimental results are discussed together with microcomputed tomography, which shows the 3D pore structure. These results are important for sensing applications that operate at elevated temperatures and apply compressive stress to the electroactive element.

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