Search Results (526)

In this study, a composite powder explosion suppressant (MVTS–NaHCO₃) was prepared via the wet coating method of the solution–crystallization (WCSC) process, using modified vanadium–titanium slag (VTS) as the carrier and NaHCO₃ as the active suppressive component. A 20 L spherical explosion apparatus and a transparent pipeline explosion propagation test system were employed to investigate the effects of the composite powder explosion suppressant with different mass fractions (0%, 10%, 20%, 30%, 40%, 50%) on the explosion pressure and micro-mechanism of polyacrylonitrile (PAN) dust. The experimental results indicated that the MVTS–NaHCO₃ composite powder exhibited a significant suppression effect on PAN dust explosions. In the confined 20 L vessel, complete suppression was achieved when the mass fraction of the composite powder explosion suppressant exceeded 30%, with a maximum explosion pressure reduction of 53.2%. In the semi-open pipeline, 40% composite powder explosion suppressant reduced the maximum explosion pressure to 0.08 MPa (a reduction rate of 82.6%), and complete suppression was achieved at a mass fraction of 50%. Microstructural analysis revealed that the suppression performance of the composite powder explosion suppressant is attributed to the synergetic effects of physical and chemical mechanisms. Physically, NaHCO₃ decomposes endothermically (100 kJ/mol), releasing CO₂ and H₂O and thereby diluting the oxygen concentration, while the porous structure of MVTS enhances dispersibility. Chemically, the hydroxyl groups on the surface of MVTS bond with NaHCO₃, delaying its decomposition, while metal hydroxides (e.g., Al(OH)₃) decompose thermally to form Al₂O₃, which adsorbs and quenches free radicals (e.g., ·OH, ·H), thereby inhibiting chain reactions. This study provides new insights for the resource utilization of VTS and the prevention and control of industrial dust explosions. The findings have important reference value for optimizing explosion suppressant formulations and improving the intrinsic safety. Full article

Titanium implants are widely used in orthopedic and dental fields but often face challenges such as insufficient osseointegration and peri-implant inflammation. While Strontium (Sr) possesses potent bioactive properties, achieving its controlled delivery at the implant-tissue interface remains technically challenging. To address this, we engineered a multidimensional composite coating by constructing a micro/nano-porous TiO₂ substrate via micro-arc oxidation (MAO), followed by polydopamine (PDA)-assisted Sr immobilization. This integrated architecture significantly enhanced surface hydrophilicity and facilitated high-content Sr loading with sustained release kinetics. Biological evaluations demonstrated that the PDA-mediated interface promoted superior initial adhesion and spreading of bone marrow mesenchymal stem cells (BMSCs), synergizing with released Sr²⁺ to markedly upregulate core osteogenic markers (Runx2, ALP). Crucially, the functionalized surface actively optimized the immune microenvironment by inducing M1-to-M2 macrophage polarization and comprehensively suppressing RANKL-induced osteoclastogenesis via the downregulation of TRAP and DC-STAMP. By integrating these pro-osteogenic, anti-inflammatory, and anti-resorptive capabilities, this tri-functional system effectively rebalances the bone remodeling microenvironment. Consequently, it provides a robust, universally applicable strategy for enhancing the therapeutic efficacy of next-generation orthopedic and dental implants. Full article

Thermally induced self-healing technology is regarded as an effective approach to mitigating the frequent occurrence of asphalt pavement distresses. Its efficiency, however, is highly dependent on the thermal conductivity of asphalt mixtures, which conventional aggregates can hardly satisfy. Meanwhile, high-titanium heavy slag (HTHS), an industrial solid waste rich in TiO₂, has been stockpiled in large quantities, and its large-scale resource utilization remains a critical challenge. Against this background, HTHS was employed in this study to replace limestone at equal mass ratios for the preparation of seven asphalt mastics (replacement rates of 0%, 20%, 40%, 60%, 80%, 100%, and neat asphalt) and four types of asphalt mixtures differentiated by coarse and fine aggregate compositions. The results indicate that with increasing HTHS content, the proportion of structural asphalt in the mastic increased markedly, leading to significant improvements in temperature susceptibility, high-temperature stability, and rutting resistance. Compared with the 100% limestone system, the penetration index (PI) of the 100% HTHS mastic increased by 8.4%, the softening point rose by 18.0%, and the rutting resistance factor at five temperatures from 46 °C to 70 °C increased by 21.8%, 56.8%, 79.2%, 171.7%, and 169.6%, respectively. Although low-temperature ductility decreased by 21.3% due to the reduction in free asphalt, it remained within acceptable limits. Regarding asphalt mixture performance, both high-temperature stability and low-temperature cracking resistance improved progressively with increasing HTHS replacement, showing increases of 75.56% and 11.75%, respectively, at full replacement. Water stability decreased by approximately 9% owing to the porous and water-absorptive nature of the slag, yet still satisfied specification requirements. In addition, the incorporation of HTHS significantly enhanced the thermal conductivity of the system, with increases of 0.125 W/(m·K) for asphalt mastics and 0.666 W/(m·K) for asphalt mixtures, corresponding to improvements of 33.7% and 32.2%, respectively. This study confirms that HTHS can serve as a viable asphalt pavement material capable of meeting the thermal conductivity requirements of thermally induced self-healing technology, while simultaneously providing a promising pathway for its large-scale resource utilization. Full article

Background: Interbody spinal fusion is a common surgical treatment for degenerative, traumatic, and deformity-related spinal pathologies. Despite advances in cage geometry and fixation strategies that improve alignment and early stability, reliable fusion remains limited by the mechanical and biological constraints of conventional interbody implant materials. Traditional titanium and polymer-based cages often fail to optimally balance load sharing, osteointegration, and biological activity within the mechanically demanding interbody environment. This narrative review examines the development and translational potential of 3D-printed interbody fusion devices, with emphasis on how additive manufacturing enables the integration of mechanical performance with biologically active scaffold design. Methods: A thorough literature review was performed to evaluate the evolution, design principles, material properties, and translational outcomes of three-dimensional (3D)-printed interbody fusion devices. Results: Additive manufacturing enables precise control over implant architecture, allowing for the fabrication of porous, lattice-based cages with tunable stiffness, optimized load sharing, and enhanced bone–implant integration. Preclinical and early clinical studies suggest that 3D-printed porous titanium cages may reduce subsidence, promote osteointegration, and improve fusion-related outcomes compared with conventional designs. Emerging evidence indicates that scaffold porosity, surface microtopography, and bioactive coatings influence macrophage polarization, angiogenesis, and osteogenic signaling. Polymeric and composite constructs, particularly hybrid designs incorporating surface functionalization, represent promising adjuncts, though clinical evidence remains limited. Conclusions: Three-dimensional printing represents a paradigm shift in interbody fusion device design. Continued translational research and longer-term clinical follow-up are required to validate efficacy and guide widespread clinical adoption. Full article

Nickel-titanium (NiTi) alloys are attractive for functional and biomedical applications due to their shape memory effect, superelasticity, and favorable corrosion resistance and biocompatibility. In this work, the influence of strut size on the compressive response of laser-based powder bed fusion (PBF-LB/M) fabricated NiTi ortho-octahedral porous scaffolds was systematically investigated using combined experiments and finite element simulations. Four scaffold designs with identical unit-cell size (2 mm) but different strut sizes (280, 320, 360, and 400 μm) were fabricated, and their forming quality and deformation behaviors were examined. The as-built scaffolds exhibited high geometric fidelity to the CAD models and stable manufacturability across the investigated parameter range. Quasi-static compression tests revealed a typical three-stage response (linear-elastic regime, plateau/collapse regime, and densification), with both elastic modulus and compressive strength increasing markedly with strut size. Specifically, the modulus increased from 1.17 to 4.28 GPa and the compressive strength increased from 155 to 564 MPa as the strut size increased from 280 to 400 μm. A pronounced oscillatory plateau was observed for the 280 μm scaffolds, indicating progressive layer-by-layer collapse, whereas larger struts promoted a shear-band-dominated failure mode characterized by an approximately 45° fracture zone. Explicit quasi-static simulations reproduced the experimentally observed collapse sequence and demonstrated that stress preferentially concentrates at nodal junctions, with load transfer dominated by struts aligned with the loading direction. The agreement between experiments and simulations confirms the predictive capability of the proposed modeling framework and provides mechanistic insights into geometry-controlled failure. These findings establish a structure-property-failure relationship for PBF-LB/M-fabricated NiTi octahedral scaffolds and offer practical guidance for tailoring stiffness, strength, and collapse mode through strut-size design. Full article

A major quality challenge in the application of titanium alloys is the persistence of substances known as “hard-alpha inclusions”. Although hard-alpha inclusions are extremely rare and typically small in size in high-quality titanium alloys for aero-engine disks, their hard and brittle nature poses a non-negligible threat to the structural integrity of the disks. Due to the extreme scarcity of natural hard-alpha inclusions, most previous studies have focused on “synthetic dense hard-alpha particles” rather than “real porous hard-alpha inclusions”, inevitably over-looking the differences between them. In this work, a method of introducing titanium nitride sponge preforms into the electrode preparation step of the smelting process is proposed and implemented, successfully fabricating real porous hard-alpha inclusions in TC4 titanium alloy disks. On this basis, the detection characteristics of ultrasonic non-destructive testing for such porous hard-alpha inclusions are investigated, and a probability of detection (POD) model for these defects is established for the first time. A defect distribution model of porous hard-alpha inclusions for the probabilistic damage tolerance assessment of disks is also derived. This work reveals that, unlike the “linear” behavior of traditional models, the new defect distribution model adheres to a “cubic polynomial” relationship. Full article

The corrosion behavior and passive-film stability of a β-TiZrNbTa (β-TZNT) alloy were investigated in artificial seawater (ASW), focusing on the effects of pH, temperature, immersion time, fluoride ion concentration, and potential scan rate. In addition to electrochemical methods such as open-circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed for surface characterization. The establishment of a stable and efficient passive layer enriched in Zr-, Nb-, and Ta-oxides was responsible for the β-TZNT alloy’s superior corrosion resistance in fluoride-free ASW when compared to commercially pure titanium. Reduced passive-film resistance resulted from corrosion kinetics being greatly accelerated by decreasing the pH and increasing the temperature. The presence of fluoride ions strongly affected the passivity of the alloy due to the chemical dissolution of TiO₂ through the formation of soluble fluoride complexes, resulting in an increase in the corrosion current densities by more than one order of magnitude. A bilayer passive structure with a compact inner barrier layer and a porous outer layer was identified by EIS analysis. The stability of this structure gradually decreased with increasing fluoride concentration and acidity. Over time, passive-film degradation was dominant in fluoride-free seawater, whereas prolonged exposure in fluoride-containing media promoted partial re-passivation. Overall, these results highlight the potential and limitations of the β-TZNT alloy for marine and offshore applications by offering new mechanistic insights into the synergistic effects of fluoride ions and environmental factors on corrosion performance. Full article

Direct borohydride fuel cells (DBFCs) are emerging as a promising source of clean energy; however, their performance depends heavily on efficient anode catalysts for the oxidation reaction of sodium borohydride (BOR). In this study, we developed and tested the Au–NiZn/Ti electrocatalyst designed to improve the performance of DBFCs. Electrodeposition and alkaline leaching were utilized to transform a zinc-rich nickel coating into a porous dendritic structure on a titanium substrate. By adding a small amount of gold crystallites through galvanic displacement, the surface roughness and the number of active sites available for the reaction were significantly increased. Electrochemical tests confirmed that this modification enhances BOR and effectively suppresses unwanted side reactions like hydrogen evolution. The resulting catalyst demonstrated high stability, maintaining over 88% of its current density during extended operation. Ultimately, the study positions this gold-modified material as a cost-effective and durable solution for clean energy conversion technologies. Full article

Titanium alloys are widely used as bone graft materials due to their excellent corrosion resistance and biocompatibility. Implant failure can result from long-term exposure to body fluids and inflammation-induced pH decreases, both of which compromise the material’s corrosion resistance and mechanical stability. To address this issue, porous Ti-6Al-4V alloy was selected in this work. Immersion tests were conducted in Hank’s solution with different pH values (3, 5, and 7) for 90 days to simulate the in vivo microenvironment under various physiological conditions. The degradation behavior of porous Ti-6Al-4V alloy during the 90-day immersion period was systematically investigated using a combination of characterization techniques. The results indicated that TiO₂, Ca₃(PO₄)₂, and Ca(H₂PO₄)₂ phases were formed on the surface of the after 90 days of immersion. Massive dissolution of TiO₂ was observed in solutions with high H⁺ concentration (low pH). Ion release tests revealed that the concentration of titanium ions released was significantly higher in acidic solutions, suggesting that the passive film formed on porous Ti-6Al-4V alloy was unstable and prone to dissolution under acidic conditions. Consequently, a large amount of corrosion products accumulated on the specimen surfaces immersed in acidic solutions for a long duration. Moreover, the compression properties of the samples deteriorated after immersion. Specifically, the compressive strength decreased by 12.68 MPa, 11.67 MPa, and 5.84 MPa for sample immersed in solutions with pH = 3, 5, and 7, respectively. The significant reduction in compressive performance of the alloy in high H⁺ concentration solutions was attributed to the decreased compactness caused by ion release. The fracture mode of the porous Ti-6Al-4V alloy after immersion was identified as a mixed mode of ductile and brittle fracture. Full article

Rapid depressurization and warming during recovery can trigger stress in deep-sea microbes and accelerate RNA degradation. We developed a remotely operated vehicle (ROV)-oriented multi-sequence microbial sampler for 2000 m sampling (20 MPa, 2 °C) that integrates in situ filtration with immediate RNAlater injection (an RNA stabilization reagent), collecting up to 12 samples per dive. A Dirichlet sampling–B-spline–SVM framework was used to optimize the cam profile of the sequence trigger for robust actuation under geometric constraints and realistic tolerances in both manufacturing and assembly. Relative to the baseline 3-4-5 motion law, the optimized design reduces nominal peak driving torque by ~18–20% and lowers the maximum torque under tolerance perturbations; tests show a further ~10–25% reduction using a SiC ball–ZrO₂ block pair versus a MoS₂-lubricated titanium pushrod–ZrO₂ block pair. A Darcy–Forchheimer porous-media computational fluid dynamics (CFD) model predicts earlier clogging on the lower membrane and a fast-to-slow RNAlater displacement process; greater membrane resistance mismatch delays 95% displacement and increases RNAlater loss. Simulations and Rhodamine B tests suggest an RNAlater consumption of 0.9 L per parallel filter (one membrane per side), and 20 MPa chamber tests confirm stable operation and membrane retrieval. Full article

Porous photocatalysts from agricultural waste, i.e., apricot and peach shell, with titanium dioxide were prepared by a carbonaceous method, the adsorption and photocatalytic degradation and its kinetics about methylene blue (MB) were studied systematically. The properties of the prepared composite sorbents were characterized using Brunauer–Emmett–Teller, surface area, scanning electron microscopy, and energy dispersive spectroscopy analyses. Several key factors, including radiation, pH, temperature, initial MB concentration, contact time, and sorbent dosage, as well as photocatalytic activity were investigated. All the waste-TiO₂ adsorbents showed improved adsorption and photodegradation performance compared to commercial charchoal-TiO₂. The produced materials presented high specific surface areas especially those derived from apricot shell-TiO₂ with a combination of type I and IV adsorption isotherms with a hysteresis loop indicating micro and mesopore structures. In addition, under UV radiation, the composite sorbents exhibited greater MB removal efficiency than non-radiated composite sorbents. The examined conditions have shown the best MB adsorption results at pH greater than 7.5, temperature 30 °C, contact time 120 min, initial concentration 0.5 mg/L MB, and sorbent dosage equal to 2.0 g/L C/MB. The total removal rate of MB is 98.5%, while the respective amount of commercial charcoal-TiO₂ is equal to 75.0%. The kinetic model that best describes the experimental data of MB degradation from the photocatalytic materials is the pseudo-second order model. In summary, this work highlights the effectiveness and feasibility of transforming agricultural waste into carbonaceous composite sorbent for the removal of cationic dyes from wastewater. Future work will involve scaling up the synthesis of the catalyst and evaluating its performance using bed reactors for industrial processes. Full article

To address the conflicting demands of lightweight materials and high load-bearing capacity in high-end fields such as aerospace and biomedical engineering, there is an urgent need to conduct research on the mechanical behavior and response mechanism of porous titanium alloy structures. In this paper, a combination of experimental testing, numerical simulation, and theoretical analysis was employed to conduct the research. A titanium alloy porous structure with different porosities was constructed based on classical three-period minimal surface optimization, and its preparation was completed using advanced selective laser melting technology. A multidimensional characterization experimental device was established to accurately obtain its mechanical performance data. It was found that the mechanical behavior of the structures is insensitive to loading rates, but more sensitive to their structural volume fraction. The quantitative characterization of microstructure damage and fracture morphology, as well as the identification of failure modes, indicates that the microstructure damage of the porous metal exhibits a ductile–brittle synergistic damage characteristic. By combining high-precision numerical simulation technology, the damage modes and damage evolution laws of porous metal structures in titanium alloys were comprehensively elucidated. By analyzing energy dissipation and constructing evaluation indicators for energy absorption efficiency, the energy absorption characteristics of the porous metal structure were elucidated, and the interaction behavior and correlation mode between the platform stress and the structural volume fraction of the porous metal structure were accurately described. Full article

Orthognathic surgery restores functional balance and facial esthetics in patients with dentofacial deformities. The use of adjunctive facial implants—made from materials such as porous polyethylene, titanium, or polyetheretherketone (PEEK)—has increased to enhance contour and projection, although standardized guidelines for their selection and integration remain scarce. Following PRISMA-ScR guidelines, a systematic search of PubMed, Scopus, Embase, and LILACS identified studies reporting facial implants placed concomitantly with orthognathic surgery. Eligible studies included case reports, case series, observational studies, clinical trials, and reviews involving human patients, without language or date restrictions. Seventeen studies published between 1998 and 2025 met the inclusion criteria, comprising retrospective and prospective designs, case series, and one technical note. Implants were used in the malar, infraorbital, paranasal, chin, mandibular body, and angle regions. Materials included PEEK, porous polyethylene, silicone, hydroxyapatite, polymethylmethacrylate, and titanium. PEEK was mainly used for patient-specific implants, while porous polyethylene was commonly used as stock implants. Follow-up time, outcome reporting, and study design varied widely, reflecting substantial methodological heterogeneity and predominantly observational evidence. As a result, outcomes were primarily reported qualitatively, limiting comparative assessment and long-term inference. Overall, the available literature suggests that alloplastic facial implants may serve as useful adjuncts to orthognathic surgery for contour enhancement, with outcomes influenced by implant design, surgical expertise, fixation, and soft tissue conditions. However, the current evidence base remains limited, underscoring the need for standardized outcome measures, comparative studies, and longer follow-up to better inform clinical decision-making and future research. Full article

Metallic implants used in orthopedics, such as titanium alloys, possess excellent mechanical strength but suffer from corrosion and poor bio-integration, often necessitating revision surgeries. Bioactive coatings, particularly hydroxyapatite, can enhance implant osteoconductivity, but high-purity synthetic hydroxyapatite is costly. This study investigates the development and characterization of a low-cost, biocompatible coating using hydroxyapatite derived from an unconventional natural source dromedary bone applied onto a titanium substrate via plasma spraying. Hydroxyapatite powder was synthesized from dromedary femurs through a thermal treatment process at 1000 °C. The resulting powder was then deposited onto a sandblasted titanium dioxide substrate using an atmospheric plasma spray technique. The physicochemical, structural, and morphological properties of both the source powder and the final coating were comprehensively analyzed using Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, X-ray Diffraction, and Fourier-Transform Infrared Spectroscopy. Characterization of the powder confirmed the successful synthesis of pure, crystalline hydroxyapatite, with Fourier-Transform Infrared Spectroscopy analysis verifying the complete removal of organic matter. The plasma-sprayed coating exhibited good adhesion and a homogenous, lamellar microstructure typical of thermal spray processes, with an average thickness of approximately 95 μm. X-ray Diffraction analysis of the coating revealed that while hydroxyapatite remained the primary phase, partial decomposition occurred during spraying, leading to the formation of secondary phases, including tricalcium phosphate and calcium oxide. Scanning Electron Microscopy imaging showed a porous surface composed of fully and partially melted particles, a feature potentially beneficial for bone integration. The findings demonstrate that dromedary bone is a viable and low-cost precursor for producing bioactive hydroxyapatite coatings for orthopedic implants. The plasma spray method successfully creates a well-adhered, porous coating, though process-induced phase changes must be considered for biomedical applications. Full article

Porous Ti-6Al-4V foams are excellent materials due to their low density, high specific strength, and excellent biocompatibility. This study investigates the fabrication of open-cell Ti-6Al-4V foams using the replica impregnation method with polyurethane templates of varying pore sizes (20, 25, and 30 ppi) and sintering temperatures (1170 °C, 1200 °C, 1250 °C, and 1280 °C). The effects of these parameters on microstructural evolution, phase composition, and mechanical properties were examined. Microstructural analysis showed that optimum densification occurred at 1250 °C. However, at 1280 °C, excessive grain growth and pore coarsening were observed. XRD, SEM, and EDS analyses confirmed that α-Ti was the matrix phase, while titanium carbide formed in situ as a result of the carbon residues released from the decomposed polyurethane template. With the development of the TiC phase and enhanced interparticle bonding due to sintering, the compressive strength progressively increased up to 1250 °C. At 1280 °C, strength decreased due to excessive TiC growth, causing brittleness and pore coarsening, reducing structural integrity. Maximum compressive strength of 40.2 MPa and elastic modulus of 858.9 MPa were achieved at 1250 °C with balanced TiC dispersion and pore structure. Max density of 1.234 g/cm³ was obtained at 1250 °C. Gibson-Ashby analysis and the fracture surfaces confirmed the brittle behavior of the foams, which is attributed to the presence of TiC particles and microcracks in the structure. The study concludes that 1250 °C provides an ideal balance between densification and structural integrity, offering valuable insights for biomedical and structural applications. Full article