Materials最新文献

The aim of this work is to develop structurally enhanced and highly hydrophobic polyurethane (PU) foams for the efficient remediation of liquid organic pollutants. For this purpose, PU foams were modified with renewable activated biochar derived from marine algae (AC) and a hydrophobic polydimethylsiloxane (PDMS) coating, producing four systems: pristine PU, PU-AC, PU/PDMS, and the hybrid PU-AC/PDMS composite. The study evaluates how AC incorporation and PDMS surface functionalization influence the microstructure, chemical composition, wettability, thermal stability, and sorption behavior of the foams. SEM images revealed progressive reductions in pore size from 420 ± 80 μm (PU) to 360 ± 85 μm (PU-AC/PDMS), with AC introducing heterogeneity while PDMS preserved open-cell morphology. FTIR confirmed the presence of urethane linkages, carbonaceous structures, and PDMS siloxane groups. Surface hydrophobicity increased markedly from 88.53° (PU) to 148.25° (PU-AC/PDMS). TGA results showed that PDMS improved thermal stability through silica-rich char formation, whereas AC slightly lowered degradation onset. Sorption tests using petroleum-derived oils and hydrophobic organic liquids demonstrated a consistent performance hierarchy (PU < PU/PDMS < PU-AC < PU-AC/PDMS). The ternary composite achieved the highest uptake capacities, reaching 44-56 g/g for oils and up to 35 g/g for hydrophobic solvents, while maintaining reusability. These findings demonstrate that combining activated biochar with PDMS significantly enhances the functional properties of PU foams, offering an efficient and sustainable material for oil-water separation and organic pollutant remediation.

Biomass liquefaction is a thermochemical process that converts lignocellulosic materials into reactive liquid intermediates, enabling the production of bio-based polyols as a sustainable alternative to petroleum-derived chemicals. This study investigates the liquefaction of two lignocellulosic biomasses, Red Angico (Anadenanthera colubrina) and Mahogany (Swietenia macrophylla), using a glycerol-ethylene glycol polyalcohol system, chosen for its renewable origin and high solvating efficiency. The resulting polyols were used to produce polyurethane (PU) foams, and their properties were evaluated in relation to biomass composition. The chemical composition of each biomass significantly influenced its liquefaction behavior and polyol characteristics. Mahogany achieved higher liquefaction efficiency, whereas Red Angico polyols generated PU foams with superior mechanical performance, highlighting the influence of species-specific chemistry. Water content and isocyanate index were found to modulate foam structure and compressive strength. This work demonstrates how tailored liquefaction strategies using polyalcohol systems can optimize bio-based PU foam properties, providing a sustainable route for high-performance polymer materials.

Zinc-based alloys are promising candidates for biodegradable implant applications; however, their rapid initial corrosion and limited cytocompatibility remain major challenges. In this study, a Zn-Ca-P layer in a form of parascholzite (CaZn₂(PO₄)₂·2H₂O) was prepared on a Zn-0.8Mg-0.2Sr alloy via anodic oxidation followed by short-time biomimetic calcium-phosphate deposition. The formation mechanism, corrosion behaviour, and preliminary biological response of the modified surface were systematically investigated. The Zn-Ca-P layer formed a compact and crystalline phosphate layer that significantly altered the corrosion response of the zinc substrate in Leibovitz L-15 medium containing foetal bovine serum. Electrochemical measurements revealed a pronounced improvement in corrosion resistance and a transition from rapid active dissolution to a controlled, ion-exchange-driven degradation mechanism. The moderate solubility of parascholzite enabled the gradual release of Zn²⁺ and Ca²⁺ ions while maintaining surface stability during immersion. Preliminary cell adhesion experiments demonstrated a clear enhancement of cytocompatibility for the Zn-Ca-P-layer-coated samples, where cells readily adhered and spread, in contrast to the bare alloy surface, which showed lower cell attachment. The improved biological response is attributed to the phosphate-rich surface chemistry, favourable surface morphology, and moderated corrosion behaviour. Overall, the parascholzite-like layer provides an effective strategy with which to regulate both corrosion and early cell-material interactions of zinc-based biodegradable alloys, highlighting its potential for temporary biomedical implant applications.

Tunnel Oxide-Passivated Back Contact solar cells represent a next-generation photovoltaic technology with significant potential for achieving both high efficiency and low cost. This study addresses the challenge of low bifaciality inherent to the rear-side structure of TBC cells. Using the Quokka3 simulation and assuming high-quality surface passivation and fine-line printing accuracy, a systematic optimization was conducted. The optimization encompassed surface morphology, optical coatings, bulk material parameters (carrier lifetime and resistivity), and rear-side geometry (emitter fraction, metallization pattern and gap width). Through a multi-parameter co-optimization process aimed at enhancing conversion efficiency, a simulated conversion efficiency of 27.26% and a bifaciality ratio of 92.96% were achieved. The simulation analysis quantified the trade-off relationships between FF, bifaciality, and efficiency under different parameter combinations. This enables accurate prediction of final performance outcomes when prioritizing different metrics, thereby providing scientific decision-making support for addressing the core design challenges in the industrialization of TBC cells.

Recently, with concern for the environment and the request for sustainable materials, more researchers and manufacturers have focused on the substitute solution of synthetic fiber reinforcement composites in industry applications. Green hybrid composites with natural components can present excellent sustainability, possess superior mechanical behavior, and reduce hazards. Hybridization technology allows new materials to inherit their raw materials' characteristics and generate new properties. The current study designed novel double-walled shell structures (DS1R4L, DS2R8L, and DS5R12L), containing two thin walls and different numbers of ring and longitudinal stiffeners, as unmanned maritime vehicle (UMV) components. A normal single-walled cylindrical shell was used as a control. These models will be made of hybrid kenaf/flax/glass-fiber-reinforced composites, GKFKG and GFKFG, created in the ANSYS Workbench. The mechanical responses (deformation, stress, and strain characteristics) of models were examined under three loading conditions (end force, end torque, and hydrostatic pressure) to evaluate the influence of both material change and structural configuration. Compared to the single-walled structure, the double-walled configurations display minimized deflection and torsional angle. Moreover, GKFKG-made structures are better than GFKFG-made ones. The research contributes positively to advancing the application of hybrid kenaf/flax/glass-fiber-reinforced composites in UMV structures and promotes the development of green sustainable materials.

We employ the Dynamical Projective Operatorial Approach (DPOA) to investigate the ultrafast optical excitations of germanium under intense, ultrashort pump pulses. The method has very low resource demand relative to many other available approaches and enables detailed calculation of the residual electron and hole populations induced by the pump pulse. It provides direct access to the energy distribution of excited carriers and to the total energy transferred to the system. By decomposing the response into contributions from different multi-photon resonant processes, we systematically study the dependence of excited-carrier density and absorbed energy on key pump-pulse parameters: duration, amplitude, and photon energy. Our results reveal a complex interplay between these parameters, governed by resonant Rabi-like dynamics and competition between different multi-photon absorption channels. For the studied germanium setup, we find that two-photon processes are generally dominant, while one- and three-photon channels become significant under specific conditions of pump-pulse frequency, duration, and intensity. This comprehensive analysis offers practical insights for optimizing ultrafast optical control in semiconductors by targeting specific multi-photon pathways.

Multi-axial forging (MAF) and aging were employed to process a high-strength aluminum alloy. The tensile properties, microstructure, and corrosion behavior were researched. After MAF, the strength of the alloy was observably increased, but the elongation was decreased. The strengthening mechanism resulted from dislocation multiplication and grain size reduction. After aging, strength was enhanced further, and elongation was improved. The strength and elongation are 561 MPa and 12.3%. Moreover, the corrosion resistance was obviously enhanced. The further strengthening is mainly attributed to the precipitation strengthening. The larger size and discontinuous distribution of grain boundary precipitates resulted in the alloy having higher corrosion resistance.

In this study, we created multifunctional bone tissue engineering scaffolds that combine prophylactic antifungal action with structural support. We produced PVA/CS/HA/BA nanofiber matrices via a specifically designed electrospinning technique to stop early cross-linking. Through SEM, our examination of fiber shape revealed diameters ranging from 178 ± 53 nm to 330 ± 69 nm. We discovered that this variation was closely correlated with the Boric Acid (BA) level. Our EDS and FTIR studies further showed that HA and BA were effectively mixed, with a specific focus on the production of borate-ester linkages inside the network. Mechanical examination revealed that 0.25 wt.% BA maximizes the tensile strength at 9.15 MPa, thereby closely matching HA-reinforced standards, while HA incorporation improved thermal stability. Moreover, in vitro hFOB experiments showed sustained cytocompatibility at 0.25 wt.% BA. While 0.5 wt.% BA showed strong antifungal action against Candida albicans, it sadly harmed cell viability. The 0.25 wt.% BA concentration ultimately offers a better balance between mechanical integrity and antibacterial action, therefore presenting a potential method for scaffold generation for bone regeneration in immunocompromised patients.

Composite laminates possess complex anisotropic behavior, motivating the development of simplified yet accurate modeling approaches. In this paper, we present a study that introduces a stiffness-invariants-based constitutive model for symmetric, balanced composite laminates, highlighting a novel "quasi-Poisson's ratio" parameter as a key innovation. The proposed method reconstructs the laminate stiffness matrices using invariant theory (trace of stiffness tensor) and a Master Ply concept, thereby reducing the number of independent material constants. The methods and assumptions (e.g., neglecting minor bending-twisting couplings) are outlined, and the model's predictions of critical buckling loads are compared to classical laminate theory (CLT) results. Good agreement is observed in most cases, with a consistent conservative bias of CLT. The results confirm that the invariant-based model captures the dominant stiffness characteristics of the laminates and can slightly overestimate stability margins due to its idealizations. In conclusion, this work provides an efficient constitutive modeling framework that can be integrated with finite element analysis and extended to more general laminates in future studies.

This study evaluated the influence of various surface treatments on the bonding performance and mechanical behavior of zirconia, with particular emphasis on the effect of laser surface texturing (LST) compared with conventional 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) and airborne particle abrasion (APA) methods. Two zirconia compositions, 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) and 5 mol% partially stabilized zirconia (5Y-PSZ), were subjected to four surface treatment protocols: as-milled, 10-MDP, APA, and LST (n = 12). Shear bond strength (SBS) to titanium and biaxial flexural strength (BFS) of zirconia were measured. Surface morphology, failure mode, and phase composition were analyzed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Data were analyzed with two-way ANOVA and Tukey's post hoc test (α = 0.05), and the reliability of flexural strength was assessed using Weibull analysis. Surface treatment significantly affected SBS (p < 0.05). The LST groups exhibited the highest SBS values and a higher proportion of mixed failures, whereas other groups predominantly showed adhesive failures. However, LST-treated specimens, particularly 5Y-PSZ, showed reduced BFS. XRD confirmed phase stability, although localized microstructural changes were observed after LST. LST enhanced the zirconia-titanium interfacial bond strength and promoted mixed failure modes; however, this improvement was accompanied by a reduction in flexural strength, particularly in 5Y-PSZ.