Materials & Design最新文献

Porous poly (lactic-co-glycolic acid)/β-tricalcium phosphate icaritin (PTI) scaffold is an ideal alternative for repairing bone defects, but their osteoinductive activity are limited. In this study, we fabricated a MXene (Ti₃C₂T_x) composite PTI (TPTI) scaffold and evaluated its characterization. We co-cultured the scaffolds with rat bone marrow mesenchymal stem cells to access the biocompatibility and osteogenic potential of the TPTI scaffold under on-demand near-infrared (NIR) irradiation. Then TPTI scaffold was implanted in a femoral condyle defect model to evaluate the osteogenic properties by micro-computed tomography, histological and immunohistochemical analysis. The results of experiments reveal that MPTI scaffold has appropriate spatial structure, suitable mechanical strength, and superior photothermal properties. It can maintain the temperature at 42.0 ± 0.5 °C and promote the release of ICT from scaffold under 0.85 W cm⁻² NIR irradiation. Furthermore, the scaffold is biocompatible and could promote cell proliferation, osteogenic differentiation, and biomineralization in vitro, as well as the repair of bone defects in vivo, and its effect is further enhanced under NIR irradiation. In conclusion, the MPTI scaffold has the potential to be applied in bone defects repairing, and its osteogenic property can be promoted under NIR irradiation through mild photothermal therapy.

Amidst the rapid advancements in materials science, the exploration of aerogel-based biomaterials has garnered extensive attention across diverse sectors, including biomedicine, energy, architecture, and sensing. Comprehensive studies have unveiled the utilization of organic, inorganic, and hybridized materials for aerogel preparation, catapulting aerogel-based biomaterials to global prominence. Endowed with distinctive properties, including low density, a hierarchical porous network, high porosity, and nanoscale micropores, aerogels have exhibited a broad spectrum of applications, particularly in the realm of tissue engineering. The deployment of aerogel-based biomaterials in tissue engineering is in a dynamic phase of development, with available reports indicating varying degrees of exploration in fields such as blood vessels, soft tissues, nerves, skin, muscles, heart, bronchial tubes, bone, and cartilage—an evolutionary process. This paper offers a comprehensive review of the evolution of aerogel properties and preparation processes, encapsulating strategic insights for the application of aerogel-based biomaterials in tissue engineering. It succinctly summarizes recent developments in tissue engineering research, emphasizing their significance. Additionally, the review outlines future prospects for the application of aerogels in tissue engineering and envisions challenges arising from current studies. Through this thorough exploration of aerogel-based biomaterials in tissue engineering, the paper aspires to make a profound impact on regenerative medicine, offering innovative and effective application strategies for biomedicine.

Additive manufacturing techniques have gone beyond their reputation for rapid prototype production and are increasingly adopted for the manufacture of functional components comprising high-end materials and intricate lattice structures. Silicon nitride, renowned for its exceptional mechanical properties and thermal stability, has emerged as a promising candidate for lightweight structural applications. Nonetheless, its high refractive index and density have limited the fabrication of highly complex structures using extrusion and photopolymerization based techniques. In this work, a highly reactive silicon nitride-based ink with high solid loading is developed for the fabrication of ultra-lightweight, truss-based structures. By employing a robot UV-assisted direct ink writing process, it is possible to control the printing head orientation, thus overcoming the limited curing depth of silicon nitride-based inks. The failure behavior of the sintered lattice beam structures under 4-point bending loading has been modeled by applying a linear elastic fracture mechanics (LEFM) based approach to the results of finite element (FE) simulations.

A fatigue cumulative damage prediction model with multi-parameter correlation, which introduces eight parameters in the action coefficients, including adjacent stresses and their corresponding lifespans (counting to four parameters), previous level of fatigue cumulative damage, S-N logarithmic slope of the material, ultimate stress, and life of the fatigue limit, is proposed in this study. The new model is not a simple nonlinear fitting. It establishes the correlation between multiple parameters and the fatigue damage model. To comprehensively evaluate the proposed model, we conducted numerous experiments to compare the proposed model with a group of baseline models. By analyzing the verification data that compared the statistical value and distribution of the difference between the fatigue prediction damage and test damage of each model, we verified that the fatigue damage prediction effect of the proposed model is the best overall. Additionally, the proposed model preliminarily demonstrated that the evolution of fatigue damage accumulation during multistage stress loading is a complex process with multiple parameters that are highly correlated.

We propose a high efficiency wideband three-fold geometric phase metasurface for versatile operation of transmission and reflection. The transmission coefficient as high as 87 % is achieved in the frequency range of f₁ (15.4–15.8 GHz), while equal transmission and reflection are achieved in two frequency bands represented by f₂ (14.6–15.2 GHz & 16–17 GHz) with maximum coefficient reaches 49 %. With geometric rotation, the phase shifts of the cross-polarized transmission and co-polarized reflection are six times the rotation angle within the frequency range of 14.6–17 GHz. Furthermore, by elaborately breaking the mirror symmetry while preserving rotational symmetry, interesting features of resonance frequency shift and mode splitting are observed, offering a more fruitful approach for versatile operations. To substantiate the proposed design, a metasurface prototype for vortex beam generation is fabricated and verified by microwave measurement.

How to precisely modulate the morphology and distribution of precipitated phases to have long-term antibacterial activity and outstanding strength-ductility has slowed the overall development and engineering applications of Cu-bearing biomedical titanium alloys. For the first time, the electron beam powder bed fusion (EBPBF) was employed to design titanium alloys with a completely solid solution, and containing fine Ti₂Cu precipitates in both uniform and layered structures. The mechanical properties of the designed alloy with the layered (α-Ti and Ti₂Cu) structure are superior to the other structures, especially with an outstanding compressive yield strength of 1221.9 MPa. Simultaneously, the wear resistance of the heterogeneous structures containing Ti₂Cu precipitates was significantly improved, with a specific wear rate only half of that of the EBPBF-fabricated Ti6Al4V alloy. The compact arrangement of Ti₂Cu phases created a large number of interfaces conducive to the formation of corrosion channels, which provided the capacity of continuous Cu²⁺ release. This work comprehensively analyzes the effects of heterogeneous structures on enhancing the sustained antibacterial capacity and optimizing the mechanical properties of a Cu-containing titanium alloy, laying a good foundation for their application in clinical and implantable devices.

Partially aromatic polyamides owing to their excellent thermal stability are widely used in high temperature applications, however, like their aliphatic counterparts, they are readily flammable and more challenging to process. In this work, several organophosphorus flame retardants were synthesized and compounded with partially aromatic polyamide and evaluated for their processability, thermal, and fire behaviour. The compounds containing a commercial flame retardant, Exolit® OP 1230 (EX), and two new flame retardants, namely 1,4-phenylenebis(diphenylphosphine oxide) (MP) and (1,1′-biphenyl]-4,4′-diylbis(diphenylphosphine oxide) (BP), showed self-extinguishing capability (i.e., UL94 V0 class) with 4 wt% phosphorus (P) loading, together with a substantial reduction in the pHRR (up to 47 %), with respect to the pristine PAP. Rheological measurements on extended timescales were used to assess the melt stability of partially aromatic polyamide compounds. The presence of MP and BP in the polymer matrix did not trigger any excessive degradation phenomena such as chain scission, branching, or crosslinking reactions, thus, allowing a stable processability similar to a pristine partially aromatic polyamide sample. Finally, analysis of evolved gases during thermal decomposition revealed that MP and BP mainly exert a flame inhibition effect quite early in the decomposition process.

CoCrMo is a prevalent alloy in prosthesis manufacturing, characterized by its favorable biocompatibility, high resistance to corrosion and high wear-resistance. Material Extrusion (MEX) Additive Manufacturing allows control over microstructural homogeneity, minimizing material waste and enabling the selection of the geometry and size of the parts, key features in the biomedical field. Granule-based MEX has been recently developed and uses a granulated metal-polymer composite as starting material that is extruded to fabricate complex parts. The binder is eliminated and the final part is obtained after sintering. This research aims to investigate the potential of MEX as a promising route for fabricating CoCrMo parts for prosthesis manufacturing. A feedstock based on Paraffin Wax and High-Density Polyethylene as binder, was prepared with optimized solid loading, then screw based MEX printing parameters, in terms of printing temperature and extrusion flow, were explored to maximize density after sintering. The microstructure development was evaluated based on carbon content, shrinkage, density, grain size, and hardness and wear performance of the optimized samples investigated. Almost fully dense parts with a microstructure free of carbides and secondary phases has been developed, which enables an excellent wear response in terms of wear rate and wear coefficient.

The objective of this paper is to propose a fiber-level modeling method for simulating tensile fracture of 3D needled composite. The complex fiber structure of 3D needled nonwoven preform is reproduced using virtual fibers. Micro-scale model of the composite is established by embedding virtual fiber structure into the voxel meshes of matrix material. The novel stiffness correction method is developed to solve the problems of volume redundancy and loss of reinforcing effect in transverse and shearing directions of the virtual fiber embedded element. The stiffness of the virtual fiber is not changed by the stiffness correction, ensuring that the stress of the virtual fibers is accurate. Damage initiation and evolution for fiber and matrix materials are characterized by the development of damage constitutive models. The tensile behavior of 3D needled composite is simulated. Influence of modeling parameters, including virtual fiber diameter and voxel mesh density on calculation accuracy is analyzed. Experimental tests are conducted to verify the simulation results. It is indicated that the predicted stress–strain response, strength, and fracture mode all agree well with the experimental results.

The study successfully developed thermoset materials utilizing acrylate epoxidized soybean oil (AESO) and allyl cinnamate (ACIN) with tert-butyl peroxybenzoate (TBPB) as the initiator. Isothermal curing at temperatures between 110 °C to 140 °C of the developed formulations, showed that higher temperatures accelerated the conversion process. The higher curing temperature increased the degree of conversion, leading to obtain the best flexural strength for samples cured at 130 °C. However, samples cured at 120 °C exhibited better impact properties due to a lower degree of conversion, which allows for a more mobile reticular network. In addition, morphological observations confirmed these mechanical property trends. Dynamic thermal characterization revealed changes in glass transition temperature and exothermic reactions due to unreacted products appeared for materials cured at low temperature. Increasing curing temperature allowed to enhance thermal stability by increasing molecular weight. Finally, thermomechanical analysis confirmed stiffness and glass transition temperature increases observed during flexural tests and thermal characterization.