This paper reports an investigation of the effects of surface conditions of forward-facing steps (FFS) on turbulent flows. Three surface conditions including one smooth step and two rough step surfaces created using sandpapers were studied. A particle image velocimetry (PIV) technique was used to conduct velocity measurements at several locations downstream, and the statistics up to 60 step heights are reported. The step height was maintained at 6 mm, and three Reynolds numbers of Reh = 1600, 3200, and 4800, where Reh is based on the step height and freestream mean velocity, were studied. The results indicate that the reattachment length of a FFS increases with Reynolds number but decreases with increasing surface roughness. The proper orthogonal decomposition (POD) results showed the step roughness affects even the large-scale structures.

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ObjectiveThis study aimed to explore whether peripheral blood stem cells (PBSCs) infused through the medial circumflex femoral artery to treat osteonecrosis of the femoral head (ONFH) could migrate into the necrotic area of femoral head.MethodsWe collected PBSCs from a patient who had bilateral ONFH by apheresis technique using COBE spectra apheresis system (COBE BCT Inc, Lakewood, CO, USA) after subcutaneous injections of granulocyte-colony stimulating factor (G-CSF) at a dosage of 10 μg/kg for 4 days to mobilize PBSCs. After that, 100 MBq 2-[18F]-fluoro-2-deoxy-D-glucose (18F-FDG) was used to label PBSCs. 18F-FDG labeled PBSCs were infused into the left femoral head via the medial circumflex femoral artery to treat ONFH. Then the patient was underwent three-dimensional positron emission tomography (3D-PET) examination 60 min after cell infusion to monitor the biological distribution of 18F-FDG-labeled PBSCs, and to observe whether the transplanted PBSCs could migrate into the necrotic area of femoral head.ResultsThe total number of monouclear cells in the peripheral blood stem cell suspension was 1.95 × 108 which contained 2.20 × 106 CD34+ cells. The activity of 18F-FDG in the labeled cells was 1.8Bq/103 monouclear cells. 3D-PET imaging showed that 18F-FDG radioactivity was detected in the necrotic area of femoral head, acetabulum and femoral bone marrow cavity after transplantation of 18F-FDG-labeled PBSCs via the medial circumflex femoral artery. It is worth noting that although PBSCs labeled with 18F-FDG were widely distributed around the hip, such as femoral bone marrow cavity, femoral head and acetabulum, PBSCs were generally located in the necrotic area of femoral head.ConclusionsPBSCs could enter into the femoral head and migrate into the necrotic field of femoral head participating in the repair of osteonecrosis after infusion through the medial circumflex femoral artery.

This paper reports an investigation of the effects of rough forward facing steps on turbulent flows. The surfaces of the rough steps were covered with sandpapers. A particle image velocimetry technique was used to conduct measurements at the mid-plane of the test section and at several locations downstream to 68 step heights. A Reynolds number of Reh = 4800 and δ/h = 4.7 were employed, where h is the mean step height and δ is the incoming boundary layer thickness. The results indicate that mean reattachment length decreases with increasing roughness. In addition, the effect of the step roughness decreases with downstream distance. The proper orthogonal decomposition results showed that the step roughness affects even the large scale structures. Furthermore, the reconstructed turbulence quantities suggest that the step roughness suppresses the large scale turbulence.