The solar energy conversion based on semiconductor photocatalysis suffers from the low absorption of visible light, the quick recombination of charge carriers, the slow surface reaction kinetics and the low long-term stability. Although defect engineering has become an exciting approach to address these challenges, the link between the design of defects at the atomic level, computational modelling, and the use of AI to discover materials has yet to be fully established. It critically examines the intrinsic and extrinsic defects including vacancies, interstitials, substitutional dopants, antisite defects, grain boundaries and dislocations, and their effects on the electronic structure, charge separation, surface reaction pathways, stability and scalability of representative semiconductor photocatalysts. The oxygen-vacancy engineering always delivers excellent photocatalytic efficiency, with the heteroatom doping and interface modulation, from the comparative analysis. This review also brings together recent developments in operando characterization, DFT, molecular dynamics, high throughput screening, machine learning, digital twins, and AI-assisted inverse design for predictive development of catalysts for clean energy. Finally, important challenges related to stability of defects, reproducible synthesis, techno-economic feasibility and commercialization are identified providing a roadmap for the development of scalable, intelligent and high-performance photocatalysts for hydrogen evolution, CO2 reduction and nitrogen fixation.
This study investigates the bonding behavior of bulk Cu single crystals under varying surface roughness and proposes a scalable construction strategy for single crystal integration based on atomic level bonding principles. Surfaces with distinct roughness from 6 nm to 185 nm were prepared using diamond turning and acid pickling. Results revealed that 20 ∼ 30 nm roughness allows three interface types—recrystallized, incomplete, and atomic level bonding—through parameter tuning. In contrast, 60 ∼ 80 nm roughness yields only recrystallized and incomplete interfaces, with atomic level bonding unattainable regardless of parameter adjustments. Based on these findings, a physical criterion is established, defining a critical surface roughness threshold of approximately 35 nm for atomic level bonding in Cu single crystals. The bonding process evolves through three stages: elastic contact expansion, creep-driven void elimination, and interfacial reconstruction for atomic continuity. This criterion can predict critical roughness for other metallic and alloy single crystal systems, including Ni-based superalloys and PST TiAl. Thus, this provides a reliable basis for producing large-sized, high-performance components from engineering alloy single crystals.
Residual-life assessment of Ni-based single-crystal superalloys is challenging because local temperature and stress histories in turbine blades are difficult to measure, while the creep-degraded γ/γ′ microstructure records prior thermo-mechanical exposure. Here, γ/γ′ degradation descriptors are used as experimentally accessible morphological state descriptors to develop a microstructure-informed two-stage physics-regularized model for the DD6 Ni-based single-crystal superalloy. In the first stage, γ-matrix channel width, rafting degree, γ′ volume fraction and creep exposure time are used to reconstruct the equivalent service state in terms of temperature and stress consistent with the current microstructural state. In the second stage, the reconstructed service state and microstructural descriptors are combined to predict creep residual life, with a condition-dependent channel-width relation and a channel-width-dependent Orowan–Garofalo formulation introduced as low-order physics regularization. Stage-wise validation, hold-out full-pipeline tests, and strict leave-one-condition-out validation show that introducing γ/γ′ degradation features and physics regularization improves the accuracy and consistency of service-state reconstruction and residual-life prediction within the investigated temperature–stress window. The proposed framework links microstructural degradation, equivalent service-state information, and creep life response, providing an interpretable route for creep residual-life assessment within the investigated DD6 experimental domain.
The annulus fibrosus (AF) is a hierarchically organized, anisotropic load-bearing tissue whose structural disruption contributes to intervertebral disc degeneration (IVDD) and recurrent disc herniation. Effective AF repair requires a scaffold that not only fills the defect but also provides directional structural guidance, mechanical support, and regulation of the inflammatory-catabolic microenvironment. Here, we developed a composition-programmed polyvinyl alcohol/silk fibroin/chondroitin sulfate (PVA/SF/Cs) aligned electrospun nanofiber scaffold based on structure–property-biofunction relationships. By tuning the PVA/SF ratio and Cs loading, P5S5C10 was identified as the optimized formulation, producing uniform, highly aligned nanofibers and the best overall tensile, shear, and cyclic mechanical performance among the tested compositions. The aligned architecture provided native-like topographical cues that directed AF cell elongation and orientation while maintaining cell viability and proliferation. Under IL-1β-induced degenerative stimulation, Cs-containing scaffolds, particularly P5S5C10, attenuated inflammatory and catabolic responses and promoted extracellular matrix-related anabolic activity. In a rat AF defect model combined with local IL-1β challenge, P5S5C10 preserved disc height and hydration, maintained AF lamellar organization, promoted collagen I and aggrecan deposition, and reduced local IL-1β expression. These findings demonstrate a rational materials-design strategy in which compositional tuning integrates anisotropic structure, mechanical reinforcement, and immunoregulatory biofunction within a single scaffold for AF regeneration.
Hydrogel patches have emerged as a skin-interfaced platform that bridges soft materials, bioelectronics, and therapeutic technologies. Due to their high water content, extracellular-matrix-like structure, and skin-matched mechanical compliance, hydrogels enable stable integration with the skin surface, supporting a broad range of healthcare functions. This review provides a comprehensive overview of recent advances in hydrogel patches for skin-interfaced healthcare technologies, with emphasis on material platforms, design strategies, functional integration, and translational considerations. We first summarize hydrogel material systems, highlighting principles governing material design and mechanical robustness, adhesiveness, conductivity, and biocompatibility.We analyze the associated mechanisms, including hydrogen bonding, electrostatic interactions, and topological entanglements that govern adhesion, as well as ionic migration and percolation theory that underpin conduction.We then discuss key physicochemical requirements for skin-interfaced applications, such as mechanical durability, controlled drug release, and long-term tissue compatibility,with mechanistic insights into stimuli-responsive volume phase transitions triggered by pH, temperature, or biomolecular cues.Applications in transdermal drug delivery, chronic wound healing, physiological signal monitoring, human motion detection, human–machine interfaces, and soft robotic systems are critically discussed.Particular attention is given to the biological mechanisms underlying wound healing, including ROS scavenging, regulation of inflammatory cytokines, and promotion of angiogenesis, as well as to conductive, ionic, and stimuli-responsive hydrogels that enable multifunctional sensing, actuation, and therapeutic feedback. Finally, we address current challenges and regulatory considerations associated with clinical translation, including long-term stability, manufacturing scalability, and safety evaluation, to provide a roadmap for developing multifunctional hydrogel patches.
K439B is a γ′-strengthened Ni–Co–Cr-based cast superalloy developed for hot-end components operating at 800 °C. In this work, the effect of post-weld secondary aging duration at 845 °C on the microstructures and 800 °C tensile strength of laser-welded K439B joints were experimentally investigated, and the contributions of strengthening mechanisms to the yield strength (YS) were evaluated using a microstructure-based model. The as-welded joint exhibited pronounced microstructural heterogeneity, and the absence of γ′ phase in fusion zone (FZ) resulted in relative low strength. The post-weld heat treatment (PWHT) promoted γ′ precipitation throughout the joint, together with M23C6 precipitation along grain boundaries (GBs), thereby reducing regional microstructural heterogeneity. With increasing secondary aging duration, the mean γ′ diameter increased from approximately 31 to 62 nm, while its fraction increased slightly from approximately 21% to 23%. The YS and ultimate tensile strength (UTS) first increased and then decreased, reaching peak values of 763.8 MPa and 781.3 MPa, respectively, after 10 h of aging. Meanwhile, the fracture location shifted from the FZ to base metal (BM) or heat-affected zone (HAZ). The predicted YS evolution agreed well with the experimental results, providing a quantitative basis for optimizing PWHT of precipitation-strengthened nickel-based superalloy weldments.
Explosive welding of alternating Grade 1 titanium and AA1050 aluminium sheets produces chemically heterogeneous solidified-melt regions at all interfaces, ranging from large vortex-confined melt zones to ultrathin interfacial layers. These regions contain metastable melt-derived structures with ultrafine-grained or near-amorphous character. Using scanning and transmission electron microscopy combined with synchrotron X-ray diffraction, this study shows that annealing at 903 K transforms these regions into heterogeneous Al3Ti reaction layers. Short-term annealing promotes rapid Al3Ti formation, whereas annealing for 103 h produces a multilayer Ti–Al3Ti–Al composite with residual Al and Ti layer thicknesses of approximately 130 and 370 µm, respectively.Al3Ti growth is governed by an evolving crystallographic architecture across the reaction zone. Synchrotron X-ray diffraction and local orientation measurements reveal coupled gradients in superstructure, texture, and grain size. Fine-grained regions enriched in Al48Ti16 and Al24Ti8 develop preferentially near the Ti side, whereas coarser regions containing Al24Ti8 and D022-ordered Al3Ti form toward the centre and Al side. These findings indicate that long-term Al3Ti growth is controlled by transport anisotropy evolving across the layer thickness, rather than by diffusion through a structurally homogeneous intermetallic phase.
To clarify non-equilibrium solute partitioning in alloys with partition coefficient k > 1 during laser additive manufacturing, a Ti-Nb alloy was investigated using a coupled macro–micro modeling framework. The segregation behavior and microstructural evolution of a k > 1 Ti–Nb alloy were quantitatively characterized under non-equilibrium solidification. Particular attention was paid to Nb enrichment within dendrite cores and the development of depletion layers ahead of the advancing interface. At the macroscale, a computational fluid dynamics (CFD) model combined with the volume of fluid (VOF) method was employed to obtain the temperature gradient G and solidification velocity V. At the microscale, a phase-field model incorporating an anti-trapping flux was developed to simulate interface evolution and solute transport. The results indicate that Nb preferentially partitions into the solid phase, forming a solute-depleted zone ahead of the interface, which enhances interfacial stability. By calibrating the solute trapping intensity parameter A and the solute-interface kinetic coupling parameter α within the quantitative thin-interface limit, the segregation behavior is accurately captured. Furthermore, a solidification map was constructed, revealing a characteristic transition sequence of “planar-cellular-dendritic-cellular −planar” with varying G/V. This framework quantitatively links processing conditions, solute partitioning, and microstructure evolution in k > 1 alloy systems.
Dust accumulation on photovoltaic panels reduces light transmission and power output, whereas many cleaning methods rely on water consumption or mechanical contact. Although single-walled carbon nanotubes (SWCNTs) networks provide electrical pathways for electrostatic cleaning, pristine SWCNT films suffer from a transmittance–conductivity trade-off and relatively strong dust adhesion, limiting integrated performance. Here, thickness-engineered SWCNT/MgF2 bilayer transparent conductive films were designed for non-contact electrostatic dust removal. A bar-coated SWCNT network served as the conductive layer, and an MgF2 overlayer was deposited by electron-beam evaporation. Moderate MgF2 deposition preserved the continuous SWCNT network and improved surface uniformity, reducing the root-mean-square roughness from 5.316 to 3.747 nm. The MgF2 layer increased the water contact angle to 111°, reduced the surface energy to 19.68 mN/m, and enhanced antireflection, giving a maximum transmittance of 91.4 % and a minimum haze of 0.12 %. The comprehensive optoelectronic performance index reached 0.898 at 80 nm. In electrostatic tests, the dust-removal rate increased from 84.08 % to 96.36 %, and the normalized photovoltaic output after cleaning reached 91.97 %. These results identify 80–120 nm as an effective MgF2 thickness range for balancing optical, surface, and electrostatic cleaning performance.
Ni-base superalloys with high γ′ volume fraction, such as CM247LC, manufactured by powder bed fusion–laser beam (PBF–LB) are highly susceptible to strain-age cracking (SAC) due to the combination of process-induced residual stress (RS) and rapid γ′ precipitation during post-processing heat treatment. This work establishes a relationship between γ′ precipitation and RS relief across a matrix of ex-situ isothermal heat treatments (650–1050 °C, 1–8 h) to identify a candidate processing window for SAC mitigation in CM247LC. This is done using a correlative approach combining scanning electron microscopy, atom probe tomography and synchrotron X-ray diffraction. The as-built microstructure exhibits nano-scale spinodal-like clustering of Cr–Co-rich and Al-(Ni, Al, Ti, Ta, Hf)-rich regions, which evolve into well-defined γ′ precipitates above 750 °C, while RS relief is negligible at 650 °C, partial at 700 °C and substantial at ≥ 750 °C. Critically, heat treatment at 700 °C for 1–4 h provides partial RS relief without extensive γ′ precipitation and SAC, whereas prolonged holding or higher temperatures promote SAC. These findings establish a qualitative map of γ′ precipitation–RS relief–SAC, enabling design of post-processing heat treatments to mitigate SAC in PBF–LB processed high γ′ superalloys.
Titanium-based alloys are essential for biomedical applications due to their low stiffness and biocompatibility, yet conventional manufacturing often faces challenges with phase segregation and high costs. This study optimized TiNb scaffolds produced via a Direct Ink Writing (DIW) using elemental powders, identifying an ink formulation with 75 wt% metallic loading as optimal for printability and shape fidelity. Sintering at 1400 °C was determined to be the critical condition for promoting effective diffusion and stabilizing the β-phase. Advanced TEM analysis revealed that this stabilization anchored by the formation of a chemically ordered superlattice structure, which inhibits diffusional transformations. Mechanically, the scaffolds exhibited a Young’s modulus matching human cortical bone, effectively addressing stress-shielding concerns. Furthermore, the TiNb scaffolds demonstrated a responsive behaviour to mechanical stimuli, showing superior time-dependent pseudo-creep and recovery kinetics when compared to pure Ti. Cyclic nanoindentation further identified a potential superelastic response inherent to the newly formed β-phase, characterized by high work and depth recovery ratios. In vitro assays with SaOS-2 osteoblastic cells confirmed that Nb incorporation significantly improves cell attachment and viability. These findings demonstrate DIW’s potential as a cost-effective method for manufacturing customized TiNb scaffolds with advanced microstructural and biomechanical properties for bone regeneration applications.
Carbon fiber reinforced polymer (CFRP) composites are essential for high-performance lightweight applications, yet traditional fiber sizings often face thermal degradation at high processing temperatures. This study investigates an approach to enhance interfacial adhesion by intercepting the cationic polymerization mechanism of poly(benzoxazine) (PBZ). This was achieved by covalently modifying the fiber surface with electron rich aromatic molecules, able to participate in the cationic polymerization mechanism. Single-filament tensile testing demonstrated that the electrochemical modification preserved the tensile strength of the fiber while significantly increasing the tensile modulus by up to 9.7%. Determination of interfacial adhesion in an epoxy (non-ionic polymerization) vs polybenzoxazine (ionic polymerization), all modified fibers showed improvements, the largest was 52% (51.3 MPa vs. 37.2 MPa for the control). SEM was consistent with strong fiber–matrix adhesion for the modified fiber samples, suggesting that the presence of designed electron rich aromatic compounds on the fiber surface is a suitable means to improve adhesion for polymers which undergo cationic polymerization.
Ceramic coatings on tantalum alloys are prone to premature failure under extreme conditions due to their inherent brittleness and weak interfacial adhesion. Herein, this paper reports a strategy for enhancing the deformation resistance and adhesion strength of HfO2/Ta2O5 composite coatings by constructing a semicoherent interface structure. A controllable hafnium source is introduced into the electrolyte, enabling in-situ synthesis of HfO2 reinforcing phases during plasma electrolytic oxidation (PEO). By quantitatively regulating Hf4+ concentration, a (111) HfO2 // (200) Ta2O5 semicoherent interface structure is achieved in PEO coating. The results indicate that the constructed (111) HfO2 // (200) Ta2O5 semicoherent interface structure has remarkable lattice distortion, which induces dislocation pinning characteristics. Compared with conventional PEO coatings, the optimized composite coating exhibits a 71% increase in deformation resistance (H3/Er2) and a 56.6% enhancement in adhesion strength. The semicoherent interface dislocation effectively alleviates stress concentration and suppresses crack initiation, which improves the deformation resistance and adhesion strength of the coating. This work demonstrates that interface engineering via controlled in-situ phase formation offers a viable pathway to overcome the strength-toughness trade-off in ceramic coatings, with significant potential for applications in aerospace and nuclear industries.
Cobalt decorated graphene nanosheet (CoGNS) reinforced Sn-0.3Ag-0.7Cu composite solder was developed to address reliability limitations caused by intermetallic compound (IMC) coarsening and interfacial layer growth during thermal aging. During isothermal aging at 110 °C for 50–1000 h, CoGNS incorporation promoted formation of a Co substituted (Cu,Co)6Sn5 phase that chemically stabilized IMCs, while graphene nanosheets physically obstructed diffusion pathways. This dual mechanism reduced bulk IMC coarsening by 51% and decreased interfacial (Cu,Co)6Sn5 and Cu3Sn growth rates by approximately 33% and 60%, respectively. Kinetic modeling confirmed that CoGNS reinforcement lowered effective interdiffusion coefficients for these layers by approximately 60% and 78%, demonstrating strong suppression of atomic transport across the solder/Cu interface. EBSD analysis showed CoGNS constrained Sn grain boundary mobility, promoting a more stable substructured grain state after prolonged aging. Mechanically, the composite maintained 13–25% higher hardness and up to 73% greater creep strength after prolonged aging. The tensile shear strength was higher in the as reflowed and early aging conditions, while the difference became small after 320 h. This work presents a combined chemical and physical reinforcement strategy in which Co substitution stabilizes the (Cu,Co)6Sn5 IMC through chemical interactions, while graphene nanosheets can physically obstruct atomic diffusion pathways, collectively improving the microstructural stability and mechanical reliability of low Ag solder joints during thermal aging.
With the development of wireless communication systems, advanced electronics, and high-power electromagnetic wave technology, electromagnetic pollution has posed significant harm to the natural environment and human health. Developing lighter, wider-bandwidth, and more stable high-efficiency microwave absorbing materials has become a research hotspot in recent years. This article first details the principles of microwave absorption, including the mechanisms of dielectric loss and magnetic loss, laying the foundation for the subsequent introduction of novel materials. Subsequently, it focuses on ferromagnetic metal/carbon composites, including composites of single ferromagnetic metals with carbon and composites of magnetic alloy with carbon of different structures. Subsequently, the review highlights ferromagnetic metal/carbon composites, including composites of single ferromagnetic metals with carbon, composites of ferromagnetic alloys with carbon, and the influence of structural design on these composites, and finally summarizes the current challenges and potential future research directions for ferromagnetic metal/carbon composites. Looking forward, the integration of bioinspired architectures and multifunctional concepts, particularly electromagnetic–thermal coupling, will provide new opportunities for advancing high-performance microwave absorbers.
Controlling the subsurface microstructure by introducing ultrasonic vibration during the machining process is essential for achieving the surface integrity required for fatigue resistance. This study investigates how vibration-induced intermittent contact and dislocation evolution jointly affect the competition between continuous and discontinuous dynamic recrystallization (CDRX/DDRX) in 12Cr2Ni4A gear steel during ultrasonic vibration-assisted gear grinding. A competitive evolution model was developed by coupling two mechanisms to capture these ultrasonic effects: (1) the thermomechanical history driven by gear geometry and intermittent grinding motion; and (2) acoustic softening-modified dislocation dynamics governing substructure formation. Model predictions of thermal response and grain refinement were validated through temperature measurements, EBSD, and TEM. Results indicate that ultrasonic vibration reduces thermomechanical loads while producing a finer subsurface gradient microstructure. This is primarily attributed to intermittent contact and enhanced dislocation motion shifting the process toward CDRX-dominated recrystallization, thereby promoting the formation of dislocation cells and subgrain rotation. The influence of machining parameters on grain structure characteristics was further analyzed. This work provides a practical framework for tailoring refined surface layers in the grinding of high strength gear steels.
Water-soluble Cu-doped ZnSe quantum dots are promising low-toxicity emitters, yet their applications are limited by defect-mediated nonradiative recombination, Cu-induced charge imbalance and lattice distortion, and poor long-term stability. Here, we develop a synergistic strategy combining substitutional Al3⁺ co-doping with stepwise growth of a multilayer ZnS shell through sequential precursor injections. Al3⁺ incorporation compensates the charge imbalance associated with Cu⁺ doping, while the multilayer ZnS shell enables progressive surface passivation and enhances carrier confinement via a graded interface. The optimized ZnSe:Cu,Al/ZnS/ZnS/ZnS quantum dots exhibit a 258% increase in photoluminescence (PL) intensity, a 10.52% enhancement in photoluminescence quantum yield (PLQY), and a 98% extension of the average lifetime (τavg) compared with ZnSe:Cu QDs. Notably, ZnSe:Cu,Al/ZnS/ZnS/ZnS QD powders retain 92% of their initial PL intensity after 300 days of storage under ambient conditions, demonstrating excellent long-term stability. This work provides a defect-engineering strategy for the rational design of highly luminescent and stable water-soluble ZnSe-based quantum dots.
The rapid advancement of in-memory computing and nanophotonics demands advanced non-volatile photonic memory materials capable of multi-level switching and exceptional thermal stability for reliable high-density data storage. Chalcogenide-based Ge-Sb-Se-Te systems have recently gained significant attention for their high optical contrast and superior glass-forming ability. Phase-change materials with superlattice-like structures (SLL) have been shown to exhibit structural tunability, resulting in low-power consumption and multi-level transition characteristics. However, the vast design space and the intricate structural evolution–property relationship pose significant challenges, particularly given the scarcity of high-quality experimental data. In this work, we have developed an interpretable data-driven approach for precise design of Ge-Sb-Se-Te SLL thin films that integrates high-quality experimental data with SHapley Additive exPlanations (SHAP) enhanced machine learning. The composition Ge0.5Sb0.15Se0.2Te0.15, offering a large refractive index contrast (Δn > 1.7) alongside a distinctive multi-stage (Fm-3 m to R-3 m) phase transition is screened rapidly. We further demonstrate that the Se → Te → Ge → Sb sequence enables exceptional amorphous stability, while the Se → Sb → Ge → Te sequence enables precise optical control for programmable multi-level photonic memory. This data-driven framework also offers a transferable methodology that may be applicable to the discovery of functional materials with tailored properties.
Sepsis-associated vascular endothelial dysfunction is a core driver of lethal organ injury, and vascular cell adhesion molecule-1 (VCAM1), a pivotal mediator of leukocyte adhesion and cytokine amplification. Herein, we confirmed in a cecal ligation and puncture (CLP)-induced murine sepsis model that VCAM1 expression significantly increased as early as 4 h post-CLP. This temporal characteristic suggests that early intervention could block the VCAM1-mediated inflammatory cascade. To efficiently degrade VCAM1, we engineered extracellular vesicles (EVs) to display the VCAM1-specific binding peptide VHPKQHR for precise anchoring to lesion sites, and avidin to enable efficient conjugation with biotinylated mannose-6-phosphate (M6P). This design hijacks the cation-independent mannose-6-phosphate receptor (CI-M6PR) to direct membrane-bound VCAM1 to lysosomes for degradation. In vitro and in vivo experiments demonstrated that this nanosystem efficiently degrades VCAM1. Notably, when administered within 6 h post-CLP, it significantly reduced VCAM1 protein levels in multiple organs of septic mice. Combination therapy with meropenem further reduced inflammatory cell infiltration and proinflammatory cytokine release, markedly ameliorated various organs’ functions, and optimized septic mice survival. In summary, this study clarifies VCAM1′s early expression pattern, develops an innovative bifunctional EV-based system for targeted VCAM1 degradation, and confirms this early intervention strategy effectively mitigates sepsis-related organ injury.
Stress relaxation is a key factor contributing to connector failure in high-strength, high-elasticity copper alloys. However, the stress relaxation behavior is influenced by numerous complex factors, making it challenging to study effectively. In this study, a high-precision predictive model for the stress relaxation behavior of copper alloys was developed to accelerate stress relaxation prediction and optimize new alloys. Through algorithmic optimization, a Cu-Ni-Si-Mg-Mn alloy was developed that combines excellent mechanical properties with high resistance to stress relaxation. Experimental results show that the designed alloy contains a high density of dislocations and uniformly distributed nanoscale Ni2Si precipitate phases. After 100 h of service at 150 ℃ and 250 ℃, the stress relaxation rates of the Cu-Ni-Si-Mg-Mn alloy remained at 4.87% and 19.1%, respectively. The addition of Mg and Mn promotes the formation of Cottrell atmospheres and the Mn6Si7Ni16 phase, which together exert a pronounced pinning effect on the motion of dislocations and substructures, thereby improving the stress relaxation resistance of the alloy. The high-precision stress relaxation behavior predictive model achieves an R2 value of 0.96 and can effectively uncover the hidden nonlinear mathematical relationships in the stress relaxation process and is expected to partially replace traditional long-term stress relaxation experiments.
