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The orientation of hydroxyapatite whiskers ( HAw ) is one of key to design and develop bioactive ceramics for bone regeneraction. Guided behavior based on the construction of magnetic anisotropy. In this study, magnetic nanoparticles Fe3O4 were loaded onto the surface of HAw by hydrothermal method, and magnetic HAw composites with excellent magnetic response characteristics were successfully prepared. The physicochemical properties and biological properties of magnetized HAw were systematically studied, and its orientation behavior in weak magnetic field was explored. The results show that ferric oxide ( Fe3 O4) nanoparticles are successfully loaded onto the surface of HAw, and the magnetized HAw has superparamagnetism and good magnetic response at room temperature, which can be manupulated by conventional permanent magnets. The alignment direction applied by the external magnetic field is effectively fixed by combining the magnetic field-induced grouting molding technology. The results of CCK-8 experiment show that magnetized HAw has no cytotoxicity. [ABSTRACT FROM AUTHOR]

Open in new tab Download slide OBJECTIVES The aim of this work was to investigate the impact of machine-learning-derived baseline lean psoas muscle area (LPMA) for patients undergoing thoracic endovascular aortic repair. METHODS A retrospective study was undertaken of acute and subacute complicated type B aortic dissection patients who underwent endovascular treatment from 2010 to 2017. LPMA (a marker of frailty) was calculated by multiplying psoas muscle area and density measured at L3 level from the computed tomography. The optimal cut-off value of LPMA was determined by the Cox hazard model with restricted cubic spline. RESULTS A total of 428 patients who met the inclusion criteria were included in this study. Patients were classified into low LPMA group (n  = 218) and high LPMA group (n  = 210) using the cut-off value of 395 cm2 Hounsfield unit. An automatic muscle segmentation algorithm was developed based on U-Net architecture. There was high correlation between machine-learning method and manual measurement for psoas muscle area (r  = 0.91, P  <   0.001) and density (r  = 0.90, P  <   0.001). Multivariable regression analyses revealed that baseline low LPMA (<395 cm2 Hounsfield unit) was an independent positive predictor for 30-day (odds ratio 5.62, 95% confidence interval 1.20–26.23, P  =   0.028) and follow-up (hazard ratio 5.62, 95% confidence interval 2.68–11.79, P  <   0.001) mortality. Propensity score matching and subgroup analysis based on age (<65 vs ≥65 years) confirmed the independent association between baseline LPMA and follow-up mortality. CONCLUSIONS Baseline LPMA could profoundly affect the prognosis of patients undergoing thoracic endovascular aortic repair. It was feasible to integrate the automatic muscle measurements into clinical routine. [ABSTRACT FROM AUTHOR]

To prolong the longevity of rotary blades, Fe-based-Al2O3-B4C coatings were prepared on 65Mn substrate using high-velocity arc spraying technology. The coatings were subsequently heat-treated at 350, 450, 550, 650, and 750 °C for 2 hours. The effect of heat treatment temperatures on the microstructure, phase composition, microhardness, tensile bonding strength, and wear resistance of Fe-based-Al2O3-B4C coatings was studied by scanning electron microscope, x-ray diffractometer, Vickers microhardness tester, tensile tester, and friction wear tester, respectively. The results showed that with the increase in heat treatment temperature, the porosity of the coating gradually decreased while the compactness of the coating increased. At 650 °C, the tensile bonding strength of the coating was the highest at 35.6 ± 3.5 MPa, which was 1.2 times higher than that of the as-sprayed coating. When the coating crystallized at 550 °C, the average microhardness and Weibull modulus reached the peak values of 1508 ± 171 HV0.1 and 23.8, respectively. The wear resistance of the heat-treated coating was the best at 550 °C, the wear rate reached a minimum of (8.2 ± 0.7) ×10−6 mm3N−1m−1, which was 0.6 times lower than that of the as-sprayed coating. The main wear mechanism was adhesive wear and abrasive wear. [ABSTRACT FROM AUTHOR]

Fe-based-Al2O3-B4C coating was prepared on the low-carbon steel substrates using high-velocity arc spraying. The effects of voltage, current, and distance on the porosity and microhardness of the coating were studied by an orthogonal test, and the optimum spraying parameters were determined. The microstructure and properties of Fe-based-Al2O3-B4C coatings prepared under optimum process parameters were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), microhardness and friction wear tester. The results showed that the optimum process parameters were a spraying voltage of 41 V, a spraying current of 200 A, and a spraying distance of 150 mm. The porosity was 2.24 ± 0.32%, and the microhardness was 1543 ± 145 Hv0.1, which was 8 times that of the substrate. Under the same load of 4.2 N and varying sliding speeds of 500 t/min, 750 t/min, and 1000 t/min, the coefficient of friction of the coating was less than that of the low-carbon steel, and the wear rate of the coating was 65%, 70%, and 63% lower than that of the low-carbon steel, respectively. The main wear mechanism of the coating was material spalling, accompanied by slight oxidative wear and abrasive wear. [ABSTRACT FROM AUTHOR]