Stem cells (SCs), the undifferentiated biological cells, have the infinite capacity to self-renew and the pluripotent ability to differentiate. SCs and their derived products offer great promise for biomedical applications such as cell therapy, tissue engineering, regenerative medicine and drug screening. However, the clinical applications of SCs require a large amount of SCs with high quality and the number of SCs from their tissue resources is very limited. Large-scale expansion is needed to generate homogeneous SCs with good biological characteristics for clinical application. This necessitates a bioreactor system to provide controllable and stable conditions for stem cell (SC) culture. Traditional methods of bioreactor for maintenance and expansion of cells rely on two-dimensional (2-D) culture techniques, leading to loss self-renewal ability and differentiation capacity upon long-term culture. New approaches for SC expansion with bioreactor employ three-dimensional (3-D) cell growth to mimic their environment in vivo. In this review, we summarize the application of bioreactors in SC culture.
Coastal grounding electrodes are currently an important means to alleviate land grounding electrode land constraints. In order to better invert the terrestrial geodesic resistivity in the coastal region, this paper proposes a complete set of inversion technology schemes. First, this paper proposes a layered land model for the coastal region, and a composite geodetic model is modeled by the fold junction of the land model and the ocean. Based on this, an adaptive subdivision boundary element method is proposed for solving the composite soil grounding calculation problem, and the accuracy and advantages of the method are demonstrated by examples. Finally, the paper uses the differential evolutionary algorithm to invert the exploration data of the four-point method in the coastal area, and obtains the parameters of the terrestrial layered geodetic model that meet the engineering requirements. The comparison with the grounding software CDEGS illustrates the effectiveness of the method. This paper carries out the research on the modeling and inversion methods of composite layered soil model, combining advanced numerical calculation methods and artificial intelligence algorithms to provide the support of computational tools for coastal resistivity inversion.
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