Materials & Design最新文献

Effective UV protection is a key aspect of substrates directly exposed to UV radiation. Therefore, in the present study, fibrous substrates of core–shell morphology (PCL-core, PVP-shell) containing peptides based on tryptophan, tyrosine and cysteine (W6, YYC2 and YYC3) were prepared. Spectrophotometric studies showed UV absorption by peptides containing tyrosine and tryptophan in the UVB (up to 80%) and UVA (up to 40%) ranges. Cysteine, in turn, contributed to high antioxidant properties, confirmed by DPPH assay. The presence of peptides contributed to a nonwoven fabric characterized by the ability to absorb UV radiation and prevent the occurrence of oxidative stress (caused by the presence of free radicals). In turn, the increase in the surface zeta potential of the nonwoven after UV irradiation and higher thermal stability (demonstrated by DSC studies) indicated the crosslinking of the PVP layer under UVR, which further contributes to the increased protection of the nonwoven against its effects. In summary, obtained nonwoven exhibited functional similarity to the native cornea, providing a potential solution for enhancing corneal tissue engineering and regenerative medicine applications.

The two deformation modes of meta-biomaterials during cyclic loading have been revealed: stochastic and deterministic strut failure processes. Biomimetic Voronoi structures with a range of strut thicknesses and number of cells per unit volume are printed. We show that when the strut thickness is 200 μm or above, the fatigue fracture process of the lattice is deterministic and the fatigue scatters are below 15%. As the strut is thinned to 150 μm, the local failures occur randomly within the structure, which may lead to a high fatigue scatter (>30%). The two distinct behaviours result from the processing limit of the laser powder bed fusion technique. We demonstrate that the fatigue scatter and the location of the failure process within the lattice are related to the probability that a cluster of unconnected struts larger than a critical value can exist within the lattice. Unlike solid parts, porosity hardly triggers any damage in metallic lattices during cyclic deformation. The discovery of the Janus-like failure process opens up our understanding of meta-biomaterials and defines the pathway towards the design of mechanically durable intricate implants.

Bone defect repair and tumor recurrence are the main challenges in the postoperative treatment of bone tumors. The incorporation of zoledronate (ZOL) into scaffolds presents a promising approach, attributed to its osteogenic and anti-tumor properties. However, there are still some unfavorable factors that make it difficult to eradicate tumor cells at the surgical site, including drug rapid release, the insufficient anti-tumor efficacy of ZOL and the multidrug resistance of chemotherapy. Herein, a novel nano drug delivery platform mesoporous silicon-coated graphene oxide (GO/MSN) and ZOL loaded nanoparticle (GO/MSN-ZOL) were developed. Then PLLA/ GO/MSN-ZOL scaffold that integrates photothermal therapy (PTT) and chemotherapy was fabricated using poly (L-lactic acid) as raw materials by selective laser sintering (SLS) technology. The GO not only imparted scaffold with photothermal properties for localized tumor cell ablation but also significantly enhanced its anti-tumor efficacy through synergistic effects in combination with chemotherapy. The mesoporous structure and large specific surface area of MSN contribute to the sustained release of ZOL. Additionally, GO could promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), which in combine with ZOL’s osteoclast inhibition, enhances the bone repair capacity. This study offers a straightforward and promising strategy for treating tumor-related bone defects.

Novel concepts for efficient compact spectroscopy are extensively researched due to their fundamental applications in prominent fields such as chemistry, biology, and physics. Here, with an unprecedented spectral-azimuthal resolution, such a concept is introduced and exemplified in the mid-infrared, in which its advantages are paramount and have yet to be established industrially. The concept is based on the design and instrumentation of optical absorption spectral tuning (or sensitivity) to the relative azimuthal component of light impinging on specifically designed metamaterials (MMs). The inversely-designed MMs offer perfect photo-absorption inside ${\lambda }_0/200$ ultra-thin layer of lead telluride. Two small-footprint system designs are proposed to instrument the spectral-azimuth-angle tuning for spectrometry. The first is based on a single or few spinning MM layout elements, and the second, to avoid spinning, utilizes a fixed focal-plane-array approach. The latter exploits the inherent variations in the local azimuthal-incidence angle. While low absorption is the Achilles heel of conventional mid-infrared photodetector spectrometers, the optimized MMs, besides their unique spectral-azimuth-angle tuning functionality, provide giant absorption enhancement, facilitating higher resolution and even smaller in-plane form factor. The highlighted concept opens an additional dimension to encode-decode spectral information, yielding profound advantages over conventional designs, such as those based on diffraction gratings.

Concrete has been a material of choice when it comes to building materials for decades. However, concrete has a number of challenges in which a major challenge being microcracking leading to excess damage and wastes. The development and advancement of self-healing technology throughout the past decade have seen the popular use of immobilization as a way of protecting bacteria from the harsh environments found in cementitious materials. This paper reviews the materials used for immobilization, categorising into organic materials and inorganic materials, and investigates the various immobilization techniques used to immobilize bacteria into polymeric structures and porous materials. The study evaluates the key findings in literature surrounding immobilization materials and methods as well as highlighting possible alternative sustainable materials and methods including waste/by-product resources. It was found that inorganic materials were superior to organic material in terms of self-healing and mechanical properties, with nanomaterials producing the highest crack closure of 1.20 mm. Various immobilization techniques efficiency was tested comparing microencapsulation, vacuum impregnation and adsorption methods. Further studies are needed to understand the relationship between carrier materials and cementitious matrix and explore the possible use of nanomaterials as a way of uniformly distributing bacteria in cementitious matrix.

The influence of prior austenite grain (PAG) orientation on the deformation behavior of a low-carbon martensitic steel is investigated using crystal plasticity (CP) modeling with hierarchical representative volume elements (RVEs). The Kurdjumov-Sachs (K-S) relationship is refined for accurate PAG reconstruction in martensitic steel. A robust calibration strategy for CP parameters based on nanoindentation tests is developed by integrating analytical calculations with inverse methods. Virtual polycrystalline aggregates are subsequently generated by manipulating initial PAG orientations. The simulations reveal that assigning cube texture to PAGs enhances strain hardening of martensite under plane strain tension. Moreover, the RVEs with brass and copper orientated PAGs exhibit similar deformation behavior, and a more homogeneous strain distribution is realized in the RVE with PAG cube orientation. The influence of PAG orientation on stress and strain fields is correlated with lattice rotation behavior during deformation. Notably, different strain paths elicit distinct lattice rotation trajectories, wherein uniaxial tension and plane strain tension favor grains reorientation toward hard $\gamma \text{-fiber}$, whilst equi-biaxial tension drives the crystal matrix to concentrate on $〈\text{001}〉$ and $〈\text{011}〉$ directions. These findings provide insights into the intricate relationship between microstructural orientation and deformation behavior in martensitic steels, which is crucial for performance optimization.

Mechanical properties of additively manufactured alloys are momentously affected by the fabrication defects, thus limiting their applications in extreme conditions. Here we report on a near fully dense 316L stainless steel via optimized laser processing parameters. The results reveal that the dynamic mechanical response exhibits much greater sensitivity to defects than the quasi-static one. The densest specimen (porosity < 0.01 %, 260W-316L) exhibits superior spall strength of 3.87 GPa and negligible damage fraction of 0.03 % at peak stress of 4.8 GPa, which are 12 % higher and 92 % smaller than those of 0.18 % porosity specimen (300W-316L). For both horizontal and vertical impacts, hardly any anisotropy of spall strength is observed in 260W-316L, demonstrating the crucial role of the pore defects on the dynamical behavior. Moreover, dislocation slip dominated spallation mechanisms have been observed in the additively manufactured 316L specimens, accompanied by a small amount of deformation twinning and martensitic transitions. This comprehensive understanding of the defect-dependent spallation behavior and deformation mechanisms provides valuable insights for optimizing the dynamic mechanical properties of additively manufactured metals and alloys.

Rheumatoid arthritis (RA) is a chronic and refractory autoimmune disease that primarily affects the synovium of diarthrodial joints. Inflammatory macrophages and fibroblast-like synoviocytes (FLS) in the synovial microenvironment produce pathogenic mediators such as cytokines and proteases that perpetuate immune-mediated inflammation and contribute to the destruction of cartilage and bone. Polydatin (PD), a natural active compound, has demonstrated potential anti-inflammatory and anti-arthritic effects. However, drug development and delivery of PD is still a great challenge owing to its low solubility, short half-life, and high dose requirement. In order to overcome these drawbacks, we developed a novel nanodrug system named HA-M@PB@Ag@PD NPs. This system is composed of hybrid membrane (M), hyaluronic acid (HA), Prussian blue nanoparticles (PB NPs), PD, and chitosan-silver (Chi-Ag). In vitro experiments demonstrated that HA-M@PB@Ag@PD NPs effectively cleared ROS, promoted the repolarization of inflammatory macrophages, and induced apoptosis of RA-FLS. Using a rat model of RA, HA-M@PB@Ag@PD NPs markedly suppressed joint inflammation, inhibited synovial hyperplasia, and protected joints against destruction of cartilage and bone. Moreover, HA-M@PB@Ag@PD NPs significantly improved the synovial microenvironment of arthritic rats by reducing the number of RA-FLS and inflammatory macrophages, and facilitating the repolarization of inflammatory macrophages.

The influence of Er content on mechanical properties and microstructural evolution of highly-alloyed Mg-10Gd-5Y-xEr alloys (x = 0, 2, 3.5, 5, and 6.5 wt%) are investigated. The tensile strength is found to increase monotonously with increasing Er content, while the ductility is slightly reduced due to the increased formation of block precipitates. The maximum tensile yield strength and ultimate tensile strength are achieved to be 296 MPa and 374 MPa, respectively, within the studied concertation interval. Solid solution strengthening and grain refinement are demonstrated to dominate the increase of tensile yield strength upon Er content, where the latter becomes the primary strengthening mechanism at relatively high Er contents (> 5 wt%). It is closely related to the consumption of Gd and Y in solid solution by the precipitation of Mg₂₄RE₅ particles and alloying element segregation at grain boundary. The significant reduced grain size of dynamic recrystallized grains upon Er content is attributed to the promoted dynamic recrystallization via particle stimulation nucleation and the retardant grain growth emerging from the drag and pinning effect of alloying element segregation and nano-precipitates at grain boundary.