International Journal of Mechanical and Materials Engineering最新文献

Objective

Three-dimensional (3D) decellularized scaffolds, providing Supportive matrices for cell growth and tissue regeneration, have gained attention as promising methods in tissue engineering and regenerative medicine. It has been established that plants are more dependable sources than animal tissues. Among various plant species, Aloe Vera stands out due to its biocompatibility and wound-healing properties, making it a viable candidate for sourcing 3D scaffolds. This study assessed the mechanical stability, drug release kinetics, and tissue integrity of decellularized Aloe Vera scaffolds coated with CMC.

Methods and materials

Sodium dodecyl sulfate (SDS) facilitated the creation of 3D decellularized scaffolds from the Aloe Vera plant. Post-evaluation of the decellularized tissue, alendronate sodium (Aln), an osteogenic drug, was incorporated into the 3D scaffold via the wet impregnation method. An oligosaccharide derived from Rosa Canina was added to Aln, serving as an agent to promote cell proliferation and differentiation. To improve mechanical stability and ensure a sustained release of alendronate sodium, the decellularized scaffolds were coated with carboxymethyl cellulose (CMC) hydrogel in 1% and 2% containing the drug.

Results

The decellularization process underwent optimization, resulting in improved physicochemical characteristics of the scaffolds. Incorporating alendronate sodium, oligosaccharide, and hydrogel coating, on the one hand, increased the swelling capacity, mechanical strength, and reduced the degradation time of the scaffold, and on the other hand, provided a controlled drug release mechanism. Also, this group exhibited suitable compatibility with cells and blood, and an increase in the migration and proliferation of MG63 cells was noted within the modified scaffolds.

Conclusion

These findings Suggest that the 3D decellularized scaffold, which incorporates Aln and oligosaccharides with a CMC hydrogel coating, offers a fresh outlook for future research in bone tissue engineering and holds significant potential for clinical use.

Graphical Abstract

Titanium dioxide (TiO₂) is a key material in biomedical applications, but its conventional synthesis by sol–gel method requires thermal treatments to induce crystallization, which can affect the stability of sensitive encapsulated bioactive compounds. In this work, the incorporation of crown ethers 12C4, 15C5, and 18C6 was explored as a strategy to promote TiO₂ crystallization at room temperature without the need for calcination. An amorphous TiO₂ matrix was synthesized by sol–gel, and the crown ether-induced crystallization was analyzed by HRTEM, IR, and UV–Vis spectroscopy. The results demonstrated the formation of anatase and rutile nanocrystals in all samples with crown ethers, with sizes ranging from 2 to 4.5 nm, confirming the ability of these ligands to modify TiO₂ nucleation. In particular, the TiO₂/15C5 complex showed a higher degree of crystallization, suggesting that the flexible geometry of this crown ether influences its interaction with the titanium matrix. These materials have potential applications in energy, catalysis, and drug storage. Furthermore, antimicrobial activity of TiO₂ makes it ideal for using in medical implants, antibacterial coatings, and wound healing. Its photocatalytic capacity could also be applied in photodynamic therapy against tumor cells, providing an innovative alternative in oncology. Finally, its biocompatibility and functionalization open new possibilities in tissue engineering and the development of biosensors for disease diagnosis.

The aim of this study is to propose a novel method for the synergetic seismic retrofitting and energy upgrade of existing masonry buildings based on multi-performance and sustainable materials. The method is based on the use of a novel type of flax-fiber-reinforced, cement-free concrete that uses clay, produced by earth excavated during construction, as a natural replacement of cement. The addition of natural fibers produced by the plant flax increases the strength of the cement-free concrete, which is characterized by substantially lower thermal conductivity and carbon footprint compared to conventional concrete. The material is integrated as an infill in a novel composite wall configuration that manifests high seismic and energy performance, as demonstrated in a large-scale experimental campaign at ETH Zurich. The obtained results show that the novel cement-free material and the novel mechanical wall configuration combine high seismic and energy performance with low environmental impact, thus facilitating the multi-performance rehabilitation of existing buildings.

Hemp-lime (HL) construction is a rapidly evolving field in biomaterials. This study systematically investigates the intellectual landscape and advancements in HL research from 2000 to 2024, analyzing 309 studies using bibliometric and meta-analytical approaches in conjunction with a literature review. The analysis identifies trends, intellectual linkages, and research gaps within the HL construction domain. With a 19% annual growth rate since 2007 and 75% of publications emerging after 2015, the field demonstrates significant momentum, driven by global initiatives such as the Paris Climate Agreement. Six major research categories have been identified, with notable contributions from France and the UK, focusing on thermal, hygrothermal, and mechanical performance. The findings reveal a shift from foundational studies to application-oriented research; however, gaps persist in construction technologies, economic modeling, and social dimensions. Advanced manufacturing techniques, predictive modeling, and circular economy frameworks are essential for scaling HL adoption. Unlike conventional reviews focused on technical synthesis, this study prioritizes mapping the field’s intellectual structure and development to reveal research patterns and guide future inquiry.

This study presents an experimental investigation into the friction stir welding (FSW) of AA6061 aluminum alloy reinforced with 10 wt% boron carbide (B₄C) particles, aiming to optimize process parameters for enhanced mechanical performance. A square tool profile was introduced and compared with cylindrical tapered and cylindrical full-threaded profiles to assess its influence on weld quality. Using the Taguchi method with an L27 orthogonal array, the effects of tool rotational speed (700, 1000, 1400 rpm), welding speed (40, 50, 63 mm/min), and tool profile were systematically examined with respect to the ultimate tensile strength (UTS) of the welded joints. The results revealed that tool rotational speed (N) had the most significant influence on UTS, followed by welding speed (S) and tool profile (P). The optimal combination of 700 rpm rotational speed, 40 mm/min welding speed, and square tool profile (N1S1P2) achieved a Maximum ultimate tensile UTS of 126.88 MPa. Statistical validation using analysis of variance (ANOVA) and signal-to-noise (S/N) ratio analysis confirmed the significance of the selected parameters. Furthermore, microstructural and fractographic analyses demonstrated a uniform dispersion of B₄C particles and enhanced load-bearing characteristics. This study highlights the effectiveness of using B₄C reinforcement and square tool geometry in improving FSW joint strength, offering valuable insights for advanced composite welding applications.

High slag concrete (HSC) offers substantial benefits in terms of durability and reduced carbon footprint, but its late strength gains delayaccurate 28-day strength prediction from early strength. This study aims to develop accelerated oven curing regimes to predict the 28-day compressive strength of HSC accurately. The research focuses on the fundamental question of whether the application of accelerated curing at specific temperatures would help estimate HSC’s long-term strength. To achieve this, a series of concrete specimens were subjected to accelerated oven curing at 50 °C and 70 °C. The compressive strength development was observed and correlated with standard curing conditions. Additionally, the hydration kinetics of the cementitious paste under these elevated temperatures were examined by using the isothermal calorimetry method. This research will produce a predictive model correlating accelerated curing data with 28-day strength. The findings of this study will provide a reliable method for estimating the strength of HSC at an early age, enabling more efficient construction planning.

Atmospheric pressure plasma (APP) etching has been developed recently into a manufacturing technique for silicon-based materials used for large optical lenses. However, there are few reports published regarding APP etching of non-silicon-based materials. We report here the development of an APP process using SF₆ for the etching of Ti-6Al-4 V metal alloy. Ti-6Al-4V is extensively used in aerospace and biomedical fields for its excellent properties; however, these properties also make it difficult to machine. Current techniques such as precision grinding and laser polishing can be slow, energy intensive, and cause damages and defects which reduce the lifetime of vital components. The results in this paper demonstrate effective material removal and little surface damage by APP etching of Ti-6Al-4V. Material removal rates between 0.5 and 2 mm³ min⁻¹ were obtained, and the proposed material removal mechanism is through the formation of volatile VF_x and TiF₄. These results show that APP etching is a promising technique for surface finishing of Ti-6Al-4V, particularly for large- and complex-shaped components.

Graphical Abstract

This paper presents the development of alkali-hydroxide-free (AHF) geopolymer concrete made of fly ash and spent coffee grounds (SCG) mix. Geopolymers are often formulated with the use of alkali hydroxides, which may have health and safety risks, durability, and workability issues. The addition of acidic materials such as SCG may neutralize the alkali content in geopolymer concrete, hence producing an AHF geopolymer. In this work, the effect of SCG addition ranging from 0 to 10% on the geopolymer strength cured from 7 to 90 days was studied. The optimum curing period and SCG addition that can yield the highest strength were optimized using response surface methodology (RSM). It was found that the geopolymer concrete containing 1.85% SCG cured for 75 days has the highest compressive strength of 12.78 MPa. The AHF geopolymer demonstrated 6.8% higher acid resistance than the control mix. This work demonstrated the contribution of SCG in the formation of an AHF geopolymer with enhanced strength.

Nowadays, the development of safety systems for passenger protection in the automotive industry relies heavily on numerical simulations. FE simulation was widely used to study the sensitivity of design parameters and their influence on costs and/or overall weight in new car models through the inspection of different scenarios developed. In this article, crash simulations were conducted to simulate a car accident via the finite element method. The aim was to analyze the performance of a car structure deforming during the collision in the presence of dummy, belted or not, to determine the degree of safety provided to the occupants of the car. The CAD model of the car and the dummy was made using LS-DYNA software; the collision impulse of the vehicle and the speed of the driver's seat were observed and compared. Various incoming speeds were taken into account when the car was modeled to crash into a wall.

The primary objective of this study was to employ the plasma focus (PF) technique to synthesize iron-tantalum (Fe-Ta) thin films while mitigating the reduction of iron content. The investigation focused on two variable parameters: the number of plasma shots and the type of irradiation source (electron or ion). Notably, this work introduced the innovative approach of positioning the iron substrate inside the hollow anode, which distinguishes it from previous experiments. The resulting thin films were characterized comprehensively using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Vickers hardness testing (VHT), and optical microscopy (OM) imaging of Vickers indentations. XRD analyses indicated that the observed stress, strain, and microcracks were minimal and could be considered negligible as the number of electron beam shots increased. Additionally, two distinct intermetallic structures—FeTa and Fe₂Ta—formed during the synthesis process. In all samples, the FeTa phase was found to increase proportionally with the number of shots. SEM observations revealed that higher oxygen content within the films was associated with the formation of improved alloy structures. Consistent with this, EDS and VHT measurements demonstrated that increased oxygen content contributed to enhanced hardness of the films. Importantly, only the ion-irradiated samples exhibited a clear trend of increasing hardness with an increasing number of shots. Overall, the findings indicate that incorporating the iron substrate within the hollow anode enabled the fabrication of ion-irradiated thin films with higher hardness, while maintaining high iron content in electron-irradiated samples.