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A method utilizing an embedded sensing system to determine the dynamic load is proposed to address the problem of not being able to directly obtain the dynamic load time history of a crawler driving structure in the harsh underground working environment of a coal mine roadheader robot. A crawler driving structure and its embedded sensing system are designed. A rigid–flexible coupling simulation model of the roadheader robot is established, and the dynamic load time history parameters of the crawler obtained from the simulation and test data are compared and analyzed. Results show that the load fluctuation of the tested track plate at the idler and sprocket is significant. By contrast, the fluctuation of the free segment is minimal. The load fluctuation range of the support segment of the hard road is −5–15 MPa, and that of the soft sand road is −10–25 MPa. Moreover, the track plate exhibits noticeable warping and winding phenomenon relative to the road wheel on the soft sand road. The changing trend of the crawler dynamic load time history obtained from simulation and test is relatively consistent. This study provides a reference for the crawler driving structure's structural optimization and reliability research. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the efficacy of human Wnt10b (hWnt10b) transgene expression in ovariectomized (OVX) rats to accelerate osseointegration around titanium implants, and to provide a new strategy for treating osteoporosis with implants. An in vivo osteoporosis model was generated via bilateral ovariectomy in rats, and changes in expression of Wnt pathway-related genes were investigated. In OVX rats with a femur defect, hWnt10b expressed from an adenovirus vector was locally delivered to the defect site prior to implant placement. Surrounding femur tissues were collected 1 and 3 weeks after implantation for imaging, biomechanical testing, and molecular and histological analyses. In an in vitro model, bone-marrow stromal cells (BMSCs) transfected with adenovirus containing hWnt10b (Ad-hWnt10b) were cultured for 2 weeks in adipogenic medium followed by 2 weeks in osteogenic induction medium. Alizarin Red staining and Oil Red O staining, as well as reverse transcription polymerase chain reaction and Western blot analyses, were performed to assess the effect of hWnt10b expression on BMSC differentiation. Expression of Wnt pathway genes was significantly downregulated in OVX rats. OVX rats treated with Ad-hWnt10b prior to induction of a femur defect showed markedly increased ALP, Runx-2, and osteocalcin expression and decreased cathepsin K expression. Histological and imaging analysis showed increases in the number of osteocalcin-positive cells and the density of newly formed bone surrounding the implant in the Ad-hWnt10b group relative to the untreated control. Meanwhile, Ad-hWnt10b-BMSCs showed significantly increased osteogenesis and decreased adipogenesis. hWnt10b may accelerate osseointegration around implants and subsequently enhance bone regeneration and implant stabilization under OVX conditions. [ABSTRACT FROM AUTHOR]

Objectives Previous studies have demonstrated the dual effects of strontium ranelate ( SR) on osteoporotic and undisturbed bone. However, reports of its effect on titanium implant osseointegration in osteoporotic bodies were limited. This study was designed to investigate the effects of SR on osseointegration of titanium implant in ovariectomized rats. Material and methods Twelve weeks after bilateral ovariectomy in female Sprague-Dawley rats, each animal received two titanium implants in the distal metaphysis of femur. All rats were then randomly divided into two groups: Control and SR (625 mg/kg/day). Twelve weeks after implantation, serum levels of osteocalcin (OCN) and tartrate-resistant acid phosphatase ( TRAP) 5b, implant osseointegration and peri-implant trabecular microarchitecture were analyzed by histomorphometry, micro-computerized tomography (micro- CT), and biomechanical test. Results Compared with control, SR treatment increased serum levels of OCN by 29.2%, and decreased the levels of TRAP 5b by 25.5% in serum analysis; SR treatment increased percent bone volume by 63.1% and percent osseointegration by 48.3% in micro- CT assessment, and increased bone area density by 55.6% and bone-to-implant contact by 49.0% in histomorphometry; SR treatment also increased the maximal push-out force by 117.7% and the ultimate shear strength by 103.5% in push-out test. Conclusions Strontium ranelate treatment could improve titanium implant osseointegration in osteoporotic rats. [ABSTRACT FROM AUTHOR]