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Digital twin (DT) technology has become an effective means of industrial digital transformation due to its ability to realize virtual-real mapping, data fusion, etc. In recent years, the application of DT technology to the assembly process of complex mechanical products in multiple fields can effectively overcome the drawbacks of the current assembly method, which is a new strategy for achieving high-precision and high-efficiency intelligent assembly. However, there are few reviews of DT's intelligent assembly technology and application for complex mechanical products. Based on the composition of the DT assembly system, the paper systematically summarizes the critical technologies of DT assembly, including DT model representation of the assembly objects, DT model construction of the assembly process, and DT data collection/management. The application of the DT assembly model based on virtual and real fusion in online monitoring, quality prediction, process planning, real-time control, etc. is comprehensively reviewed. Finally, the challenges faced by DT intelligent assembly of complex mechanical products are described, and future research directions are predicted. [ABSTRACT FROM AUTHOR]

In order to harmonize the functions of both anticoagulation and accelerating endothelialization simultaneously, the micropatterns were fabricated by photoimmobilizing heparin, functionalized with a photoreactive moiety, on 3-aminopropylphosphonic acid modified titanium oxide (Ti-O) substrates. The amount of heparin immobilized on the surfaces was determined using the toluidine blue assay. And the surface morphology of the patterns was examined using scanning electron microscopy and surface profiler. The platelet adhesion and endothelial cell behavior in terms of adhesion, proliferation, and orientation were investigated in vitro. It is clear that the heparin patterns can reduce the platelet adhesion, and promote endothelial cells spreading and proliferation compared to nonpatterned heparin sample. Furthermore, the microstripes with appropriate size can induce the cells to elongate and arrange along the stripe direction. This may suggest a new modification method for blood-contacting device. [ABSTRACT FROM AUTHOR]