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Parts are often warped and deformed when they are molded using selective laser melting (SLM) technology. Thus, it is necessary to study the addition support modes of parts molded using SLM. Consequently, we designed dendritic, E-stage and conical supports, having different structural parameters and different partitions using Magics, and then, we analyzed their performances using the finite element software Abaqus. The structural parameters of the supports were optimized and finally tested using SLM molding technology. The maximum stress concentration was found for dendritic supports, followed by E-stage supports, and then conical supports. The stress concentration and deformation level of Scheme 2 were less than those of Scheme 1. The stress intensity and deformation levels for two partitions were less than those for three partitions. For parts molded by SLM, the deformation was maximum for conical supports, followed by dendritic supports, and then E-stage supports. When gradient supports of similar volumes were added, additional partitions did not effectively improve the molding quality. When supports of similar volumes were added, adding gradient supports did not effectively improve the molding quality. The results provide a basis for the application of SLM in molding high-precision parts.
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In order to generate a high-performance personalized biological fixation plate with matching mechanical properties and biocompatibility, reverse reconstruction and fracture reduction of a femur were performed by combining reverse and forward approaches, and the surface was extracted according to the installation position of the plate to complete plate modeling by shifting, thickening, and performing other operations. Subsequently, topology optimization and three-dimensional (3D) printing were performed, and the properties of the manufactured plate were probed. The results showed that the maximum displacement of the plate was 4.13 mm near the femoral head, the maximum stress was 5.15e2 MPa on both sides of the plate across its entire length, and the stress concentration decreased following topology optimization. The plate with optimized topology and filled with porous structure has a good filling effect. The final mass of the H-shaped plate was 12.05 g, while that of the B-shaped plate was 11.05 g, which dropped by 20.93% and 27.49%, respectively, compared with the original plate. The surface of the 3D-printed plate was bright and new, with a clear pore structure and good lap joint. The B-shaped and H-shaped plates were closely dovetailed with the host bone, which met the assembly requirements. This lays a foundation for the direct application of a high-performance personalized biological fixation plate.
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Engaging in physical activity and exercise is one of the important ways for health promotion.However,older adults are often physically inactive or have a sedentary lifestyle and have poor compliance with physical activity.Exergaming program with their unique advantages could make physical activity a more joyful experience and motivate older adults to participate in physical activity.Promoting older adults'health through engagement in exergaming programs is still in the early stage,and still faces many challenges.Analyzing the challenges and difficulties faced by exergaming program for older adults and exploring in-depth strategies to promote the implementation of exergaming program for older adults are of great significance for the design and implementation of sports games for older adults.
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To further improve the quality of parts in metal 3D printers, it is necessary to optimize the structure and study the performance of their gas circulation filtration systems. First, we used the parametric modeling method to complete the formed cavity modeling. We then optimized the design of the air inlet structure of the formed cavity using the moldflow simulation method, and finally, we evaluated the optimized design results through assembly experiments and measurements of the molded parts' components. The combination of parametric modeling and moldflow simulation methods produced a high modeling efficiency and had a good effect on the optimized design of the gas circulation filtration systems. After optimizing the design, the turbulence intensities and distribution areas of the formed cavities were reduced. During the 3D printing of the curved guide plate, the plane of the guide plate holder was inclined 55° relative to the machining datum plane, which improved the form quality. The 3D printed curved guide plate closely matched the inlet end of the printer's air duct, and the upper guide plate was fixed at a suitable position using screws. The niobium contents of the parts formed by the guide plate in Design 2 were low, which lays a foundation for the 3D printing of high-performance metal parts.
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To obtain high performance (matching, mechanical properties, and biocompatibility) of personalized biomechanical fixation-type tibial implants, three-dimensional reconstruction was performed using a combination of reverse and positive methods. The implant design was optimized using a topological optimization method, the shape-optimized B-unit structure was filled, and the performance was evaluated for implants prepared by direct forming technology of Selective Laser Melting (3D Printing). The results show obviously reduced weight of the tibial implant, increased stress and displacement, yet with a more uniform distribution. The mechanical properties of the tibial implant were lower than those of the B-units, the weight was lighter, and the stress distribution was more uniform. The surface of the tibial implants prepared by SLM appeared clean and bright, the metal texture was good, the structure between the porous struts was clear, the surface had low powder adhesion, the lap joint was good, and no obvious warping deformation or forming defects were observed. The results of this study provide a foundation for the direct application of high performance personalized biofixation implants.
Asunto(s)
Prótesis e Implantes , Titanio , Porosidad , Impresión Tridimensional , TibiaRESUMEN
Objective To study the inductive effect of Cortex Periplocae extract(CPE) on apoptosis of human gastric cancer cells BGC-823 and its mechanism.Methods The cell morphology and super-microstructural changes of apoptosis were analysed by Giemsa staining and electric microscope,respectively.The BGC-823 apoptosis ratio,cell cycles,and changes of apoptosis in DNA level were studied by Flow Cytometry and agarose gel electrophoresis.The genes mRNA and protein expression of apoptosis-related genes bcl-2,bax,and survivin were studied by RT-PCR and immunology cell chemistry method.Results After treatment with CPE,BGC-823 cells showed some typical morphologic features and super-microstructural changes of apoptosis.DNA agarose gel electrophoresis showed characteristic "DNA ladder" pattern.Most BGC-823 cells were arrested at G_2/M phase.Some typical subdiploid peaks before G_0/G_1 phase were observed.The apoptotic rate of BGC-823 was 18.9% after 250 ?g/mL CPE treated for 48 h.The gene mRNA and protein expression of bcl-2 and survivin were inhibited by CPE,whereas that of bax was up-regulated.CPE could enhance the life span of S_(180) bearing mice in a dose-dependent manner.Conclusion(CPE can) inhibit the tumor growth by arresting the BGC-823 cell cycle at G_2/M phase and inducing BGC-823 apoptosis.Its mechanism is related to the inhibition on gene mRNA and protein expression of bcl-2 and survivin,and enhancement of those of bax.