Frontiers of Materials Science最新文献

Calcium ion-crosslinked alginate hydrogels are widely used as a materials system for investigating cell behavior in 3D environments in vitro. Suspensions of calcium sulfate particles are often used as the source of Ca²⁺ to control the rate of gelation. However, the instability of calcium sulfate suspensions can increase chances of reduced homogeneity of the resulting gel and requires researcher’s proficiency. Here, we show that ball-milled calcium sulfate microparticles (MPs) with smaller sizes can create more stable crosslinker suspensions than unprocessed or simply autoclaved calcium sulfate particles. In particular, 15 µm ball-milled calcium sulfate MPs result in gels that are more homogeneous with a balanced gelation rate, which facilitates fabrication of gels with consistent mechanical properties and reliable performance for 3D cell culture. Overall, these MPs represent an improved method for alginate hydrogel fabrication that can increase experimental reliability and quality for 3D cell culture.

In recent years, research on self-healing polymers for diverse biomedical applications has surged due to their resemblance to the native extracellular matrix. Here, we introduce a novel self-healing hydrogel scaffold made from collagen (Col) and nano-hydroxyapatite (nHA) via a one-pot-synthesis approach under the influence of heating in less than 10 min. Process parameters, including the quantities of Col, guar gum, solvent, nHA, borax, and glycerol in the system were optimized for the minimization of the self-healing time. The synthesized hydrogel and polymers underwent characterization via FTIR, SEM, EDS, TGA, and ¹³C-NMR. Additionally, the hydrogel showed hemocompatibility with only 6.76% hemolysis at 10 µg·mL⁻¹, while the scaffold maintained cellular metabolic activity at all concentrations for 24 h, with the optimal viability at 1 and 2.5 µg·mL⁻¹, sustaining 93.5% and 90% viability, respectively. Moreover, the hydrogel scaffold exhibited rapid self-healing within 30 s of damage, alongside a tough and flexible nature, as indicated by its swelling rate, biodegradation under various biological pH solutions, and tensile strength of 0.75 MPa. Hence, the innovative Col and nHA self-healing hydrogel scaffold emerges as an ideal, non-toxic, cost-effective, and easily synthesized material with promising potential in cartilage repair applications.

Ionized amine group (R-NH₂) and carboxyl group (R-COOH) within the active layer of polyamide (PA) nanofiltration membranes result in the formation of positive (R-NH ⁺₃ ) and negative (R-COO⁻) functional groups, respectively, which determines membrane performance and is essential for membrane fabrication and modification. Herein, a facile dye adsorption/desorption method using Orange II and Toluidine Blue O dyes was developed to measure the densities of R-NH₂, R-NH ⁺₃ , R-COOH, or R-COO⁻ on surfaces of six PA membranes, and the correlation between the density of such groups and the zeta potential was established. The dye adsorption method was proven reliable due to its lower standard deviation, detection limit, and quantification limit values. Furthermore, the densities of R-NH ⁺₃ or R-COO⁻ under different pH values were measured, fitting well with results calculated from the acid-base equilibrium theory. Additionally, a correlation was established between the net surface density ([R-NH ⁺₃ ] − [R-COO⁻]) and the surface charge density (σ) calculated via the Gouy–Chapman model based on zeta potential results. The resulted correlation (σ/(mC·m⁻²) = (3.67 ± 0.08) × ([R-NH ⁺₃ ] − [R-COO⁻])/(nmol·cm⁻²) + (0.295 ± 0.08)) effectively predicts the σ value of the membrane. This study provides a facile and reliable dye adsorption method for measuring the density of R-NH₂, R-NH ⁺₃ , R-COOH, or R-COO⁻, enabling an in-depth understanding of membrane charge properties.

TC11, with a nominal composition of Ti–6.5Al–3.5Mo–1.5Zr–0.3Si, is the preferred material for engine blisk due to its high-performance dual-phase titanium alloy, effectively enhancing engine aerodynamic efficiency and service reliability. However, in laser powder bed fusion (L-PBF) of TC11, challenges such as inadequate defect control, inconsistent part quality, and limited optimization of key processing parameters hinder the process reliability and scalability. In this study, computational fluid dynamics (CFD) was used to simulate the L-PBF process, while design of experiments (DoE) was applied to analyze the effect of process parameters and determine the optimal process settings. Laser power was found to have the greatest impact on porosity. The optimal process parameters are 170 W laser power, 1100 mm·s⁻¹ scanning speed, and 0.1 mm hatch spacing. Stripe, line, and chessboard scanning strategies were implemented using the optimal process parameters. The stripe scanning strategy has ∼33% (∼400 MPa) greater tensile strength over the line scanning strategy and ∼12% (∼170 MPa) over the chessboard scanning strategy. This research provides technical support for obtaining high-performance TC11 blisks.

Cathodoluminescence (CL) characterization technology refers to a technical approach for evaluating the luminescent properties of samples by collecting photon signals generated under electron beam excitation. By detecting the intensity and wavelength of the emitted light, the energy band structure and forbidden bandwidth of a sample can be identified. After a CL spectrometer is mounted on a scanning electron microscope (SEM), functions are integrated, such as high spatial resolution, morphological observation, and energy-dispersive spectroscopy (EDS) to analyze samples, offering unique and irreplaceable advantages for the microstructural analysis of certain materials. This paper reviews the applications of SEM-CL systems in the characterization of material microstructures in recent years, illustrating the utility of the SEM-CL system in various materials including geological minerals, perovskite materials, semiconductor materials, non-metallic inclusions, and functional ceramics through typical case studies.

Due to high theoretical capacity and low lithium-storage potential, silicon (Si)-based anode materials are considered as one kind of the most promising options for lithium-ion batteries. However, their practical applications are still limited because of significant volume expansion and poor conductivity during cycling. In this study, we prepared a double core–shell nanostructure through coating commercial Si nanoparticles with both amorphous titanium dioxide (a-TiO₂) and amorphous carbon (a-C) via a facile sol–gel method combined with chemical vapor deposition. Elastic behaviors of a-TiO₂ shells allowed for the release of strain, maintaining the integrity of Si cores during charge–discharge processes. Additionally, outer layers of a-C provided numerous pore channels facilitating the transport of both Li⁺ ions and electrons. Using the distribution of relaxation time analysis, we provided a precise kinetic explanation for the observed electrochemical behaviors. Furthermore, the structural evolution of the anode was explored during cycling processes. The Si@a-TiO₂@a-C-6 anode was revealed to exhibit excellent electrochemical properties, achieving a capacity retention rate of 86.7% (877.1 mA·h·g⁻¹ after 500 cycles at a 1 A·g⁻¹). This result offers valuable insights for the design of high-performance and cyclically stable Si-based anode materials.

Electrospinning has been widely used in the field of biomedical materials characterized with high porosity and good breathability as well as similarity to the natural extracellular matrix. This study employs the microsol-electrospinning technology combined with the self-induced crystallization method to fabricate the functionalized bilayer poly(ε-caprolactone) (PCL) fibrous membrane with a shish-kebab (SK) structure. The outer layer consists of the antibacterial SK-structured fibrous membrane showing favorable mechanical properties and notable inhibitory effects on the growth of E. coli and S. aureus, while salvianic acid A sodium (SAS) is encapsulated in the inner core–shell and SK-structured PCL fibrous membrane, achieving the controlled and sustained release of SAS. Moreover, good biocompatibility and enhanced cell adhesion of this membrane are also revealed. This antibacterial and drug-loaded bilayer PCL fibrous membrane with a SK structure demonstrates superior mechanical characteristics, exceptional antibacterial properties, and notable biocompatibility, suggesting its favorable outlook for future development in the area of tissue engineering.

The utilization of photocatalytic nitrogen fixation, a process celebrated for its environmental friendliness and sustainability, has emerged as a promising avenue for ammonia synthesis. The rational design of photocatalysts containing single atoms and heterojunctions has been a long-standing challenge for achieving efficient nitrogen fixation. This study innovatively constructs composite catalysts integrating single-atom copper within metal–organic frameworks (Fe-MOF, NH₂-MIL-101) and carbon nitride nanosheet (CNNS). The nitrogen fixation efficiency of the Cu@MIL-CNNS heterojunction was 8 and 12 times those of the original MOF and CNNSs, respectively. Through detailed characterization, we unveil a unique charge transfer pathway facilitated by the synergy between single-atom copper and heterojunctions, highlighting the critical function of copper centers as potent active sites. Our findings underscore the transformative potential of single atomic sites in amplifying charge transfer efficiency, propelling advancements in the photocatalyst design.

Copper has good electrical conductivity but poor mechanical and wear-resistant properties. To enhance the mechanical and wear-resistant properties of the copper matrix, a strategy of in-situ generation of graphene was adopted. Through ball-milling processes, a carbon source and submicron spherical copper were uniformly dispersed in a dendritic copper. Then, a uniform and continuous graphene network was generated in-situ in the copper matrix during the vacuum hot-pressing sintering process to improve the performance of composites. The graphene product exhibited lubrication effect and provided channels for electrons to move through the interface, improving the wear resistance and the electrical conductivity of composites. When the graphene content in the composite material was 0.100 wt.%, the friction coefficient and the wear rate were 0.36 and 6.36 × 10⁻⁶ mm³·N⁻¹·m⁻¹, diminished by 52% and reduced 5.11 times those of pure copper, respectively, while the electrical conductivity rose to 94.57% IACS and the hardness was enhanced by 47.8%. Therefore, this method provides a new approach for the preparation of highly conductive and wear-resistant copper matrix composite materials.

Novel advanced nanocomposites formed by associating graphene oxide (GO) nanosheets with other nanomaterials such as titanium dioxide nanoparticles, cellulose nanofibers, cellulose nanocrystals, and carbon nanotubes were incorporated in nanofiltration (NF) and reverse osmosis (RO) membranes for wastewater treatment and desalination. GO-based nanocomposite has promising potential in membrane technology due to its high hydrophilicity, absorption capacity, good dispersibility in water and organic solvents, anti-biofouling properties, and negative charge. Moreover, additional properties can be obtained depending on the nanohybrid formed. This review paper highlights the recent breakthrough in membranes functionalized with GO-based nanohybrids, focusing on membrane performance in terms of permeability, selectivity, and antifouling properties. Although GO-based nanohybrids have made significant progress in membrane technology, improvements are still needed, especially regarding trade-off effects. Furthermore, the studies presented here are limited to laboratory scale, which leads to suggestions for new studies evaluating the possibility of commercial application and the potential environmental impact caused by nanocomposites.