Search Results (2,355)

Background: Bonding to sclerotic dentin remains one of the most challenging procedures in restorative dentistry due to tubular occlusion and hypermineralization, which limit resin infiltration. This study evaluated the influence of adhesive system, surface treatment, storage time, and substrate position on microtensile bond strength (µTBS) to natural sclerotic dentin. Methods: Sixteen extracted human molars with sclerotic dentin were selected and randomly assigned to nine experimental groups according to the adhesive system and surface treatment. Three adhesives were tested: a two-step self-etch adhesive (Clearfil SE Bond 2, Kuraray Noritake Dental, Tokyo, Japan) and two universal adhesives, one containing 10-MDP (G-Premio Bond, GC Corp., Tokyo, Japan) and one without 10-MDP (iBond Universal, Kulzer GmbH, Hanau, Germany). Each adhesive was applied under three conditions: no pretreatment (control), Al₂O₃ air-abrasion, and Bioglass 45S5 (ProSylc^®, Velopex International, London, UK) air-abrasion. Composite build-ups were performed, and the specimens were sectioned into 1 mm² beams for microtensile testing either after 24 h or after 6 months of storage in distilled water at 37 °C of hypertonic solution. The effect of beam position (central vs. peripheral) was also analyzed. Bond strength was measured by µTBS testing, and the results were analyzed using multifactorial ANOVA and Tukey’s test (α = 0.05). Failure modes were examined under stereomicroscopy, whereas optical microscopy was used for qualitative evaluation of representative fractured interfaces. Results: Significant main effects were found for adhesive system and surface treatment (p < 0.001), with a notable interaction between them (p < 0.05). Al₂O₃ air-abrasion produced the highest bond strengths, particularly for the self-etch adhesive containing functional monomers (53.4 ± 6.1 MPa), representing a 53% increase over the untreated control. Bioglass air-abrasion did not enhance adhesion and led to irregular hybrid layers. The position of the beams affected only one universal adhesive, with higher µTBS in peripheral regions. After six months of water storage, bond strengths remained stable across most groups, indicating good hydrolytic resistance of the interfaces. Conclusions: Both the adhesive system and the surface treatment significantly influenced bonding effectiveness to sclerotic dentin. The combination of Al₂O₃ air-abrasion with an MDP-containing self-etch adhesive achieved the most durable and homogeneous bond interface. providing a clinically reliable protocol for restorative treatments in sclerotic dentin. Within the limitations of this in vitro study, this combination may represent a potentially useful strategy for improving adhesion to sclerotic dentin, although further investigations are required to confirm its clinical applicability. Full article

This study proposes a process combining alkali-activated potassium feldspar, acid leaching, and sol–gel coupling with supercritical drying to prepare high-performance silica–alumina composite aerogel. The optimal parameters for potassium feldspar alkali-melt activation are a calcination temperature of 350 °C, mass ratio of potassium feldspar to sodium hydroxide of 1:1.2, and calcination time of 120 min, achieving an acid-leaching efficiency of 97.3% for the activated potassium feldspar. The acid leachate, using propylene oxide as a gelling promoter, was processed through aging, solvent exchange, and supercritical drying to yield SiO₂-Al₂O₃ aerogel with typical three-dimensional nanoporous network structure. EDS spectroscopy revealed that the spatial distributions of aluminum and silicon elements were highly coincident and uniformly dispersed. XPS and FTIR further confirmed the formation of Si-O-Al bonds, indicating that aluminum atoms were successfully incorporated into the silico-aluminate tetrahedral network, constructing silicon–aluminum composite framework. The SiO₂-Al₂O₃ aerogel exhibits specific surface area of 660.841 m²/g and a pore volume of 1.321 cm³/g. Its mass loss within the 0–1000 °C range is only 9.55%, far lower than the 28% mass loss of pure aluminum oxide aerogel, indicating that the silicon–aluminum composite structure effectively suppresses high-temperature phase transitions and framework collapse. Full article

This study investigates the synthesis, phase evolution, and high-temperature oxidation behavior of multi-component aluminide coatings on EP670 (Fe-Ni base), EP718 (Ni-Fe base), and EP648 (Ni-base) superalloys. The coatings were produced using an economical hot-dip aluminizing method, followed by diffusion heat treatment at 1100 °C. In the as-deposited state, the coatings exhibit a heterogeneous structure consisting of an aluminum matrix with various Al-rich intermetallic inclusions. Subsequent heat treatment promotes the redistribution of chemical elements, leading to the elimination of free aluminum and the stabilization of a protective β-phase matrix. Long-term oxidation tests were performed at 900 °C, 1100 °C, and 1300 °C for up to 1000 h. At 1100 °C, the coatings on EP670 and EP648 demonstrated high stability, following a near-parabolic oxidation law and significantly reducing mass gain compared to uncoated substrates. However, at 1100 °C, the EP718 alloy underwent catastrophic failure within 200 h due to pest oxidation, disintegrating into an oxide powder—a phenomenon quantitatively confirmed by the kinetic exponent dropping below 1.0. At 1300 °C, the thermal limit for all coatings was established, with protective properties failing after 50 h. Based on the aluminum depletion kinetics, the service life at 1100 °C was estimated at 1300 h for EP670 and 2200 h for EP648. Scratch testing confirmed a complete absence of interfacial adhesive cracks across all systems. Contact loading triggered only cohesive cracks localized within the near-surface zone of the coatings. The results highlight the superior thermodynamic compatibility of the EP670 and EP648 systems with aluminide coatings, making them the most suitable candidates for extreme high-temperature applications. Full article

The impact of the oxide film in the remelted zone of a seed on the epitaxial solidification of single-crystal superalloys was investigated, with a specific focus on clarifying the hindrance mechanism of complex compositional oxide films during the epitaxial growth process. Experimental findings indicated that the oxide film was composed of multiple constituents, such as WO₃ and Al₂O₃, and displayed no remarkable texture in its crystal orientation. The formation mechanism of coherent oxides during the alloy oxidation process and their potential as nucleation sites for solidification were analyzed. Owing to disparities in symmetry along the growth direction, the γ phase formed through oxide nucleation that deviated from its original orientation. Moreover, the existence of polycrystalline oxide films impeded the effective transfer of single-crystal seed orientation information, leading the epitaxial growth to mainly rely on the mechanism where dendrites penetrate through the damaged areas of the oxide film to reach the upper region. Significantly, aluminum oxide within the oxide film could act as new nucleation sites, potentially triggering the formation of stray grains in the central region of the casting. Full article

This in vitro study evaluated the effects of four surface treatments (no treatment, hydrofluoric acid [HF] etching, aluminum oxide [AlO] air abrasion, and tribochemical silica coating [TSC]) and two bonding agents (dedicated silane vs. silane-containing universal adhesive) on the microshear bond strength of four CAD/CAM glass-ceramic materials, including two zirconia-reinforced lithium silicate ceramics and two conventional glass-ceramics. Four CAD/CAM materials (Celtra Duo, IPS e.max CAD, IPS Empress CAD, and Vita Suprinity) were subjected to four surface treatments (no treatment, HF, AlO air abrasion, and TSC) and further divided according to bonding agent application: dedicated silane (Clearfil Ceramic Primer Plus) or silane-containing universal adhesive (Single Bond Universal). Microshear bond strength testing was performed after 24 h of water storage (n = 10). Failure modes were classified under stereomicroscopy, and surface topography was evaluated by SEM. Data were analyzed using three-way ANOVA and Tukey’s HSD test (α = 0.05). All three main factors and their interactions significantly affected bond strength values (p < 0.05; R² = 0.863). HF etching with silane produced the highest values for most materials. However, IPS Empress CAD treated with TSC and silane yielded the highest overall bond strength (25.2 MPa). Dedicated silane consistently outperformed the universal adhesive across all combinations. ZLS ceramics showed intermediate values with distinct etching patterns compared with conventional glass-ceramics. Optimal bonding protocols for CAD/CAM glass-ceramics are material-dependent. Dedicated silane application is recommended over silane-containing universal adhesives for maximum bond strength. Full article

This investigation meticulously examines the influence of activation energy, thermophoresis, Brownian motion, and magnetic fields on the flow dynamics and heat transfer characteristics of a non-Newtonian hybrid nanofluid comprising aluminum oxide (Al₂O₃), copper (II) oxide (CuO), and ethylene glycol over a horizontally stretching porous wedge. This research addresses the imperative need for enhancing energy transfer and thermal management systems, which possess considerable technical significance and industrial relevance. The flow equations were formulated into ordinary differential equations through the use of similarity transformations, which in turn were solved numerically by employing the spectral relaxation (SR) scheme. The findings indicate that the Brownian motion, activation energy, wedge angle, and magnetic field intensity are pivotal determinants of the system’s flow and thermal behavior. In particular, an increase in the wedge angle correlates with an augmentation of the Nusselt number while concurrently diminishing the thermal and diffusion profiles. A comparative analysis of the current investigation and earlier scrutiny revealed that hybrid nanofluids enhance mass and energy transfer rates in both studies. The novelty of this investigation is anchored in its comprehensive exploration of magneto-flow dynamics and the characteristics of hybrid nanofluids within the context of porous wedge-shaped geometries and external magnetic influences. The findings of this study extend previous research by offering quantitative elucidation regarding how pivotal parameters, such as wedge angles, activation energy, thermophoresis, and Brownian motion, affect heat and mass transfer phenomena, thus laying a robust groundwork for the optimization of hybrid nanofluid applications in engineering and industrial environments. The results are in robust agreement with the existing body of literature, thereby affirming the contributions of this study to the academic discourse in the field. Full article

This work provides a comprehensive review of the development and current research status of micro-arc oxidation (MAO) coatings on 6061 aluminum alloy. It presents research findings on the enhancement of wear resistance, corrosion resistance, and other functional properties (e.g., hydrophobicity, thermal control performance, and electrical insulation) using three main strategies: insitu growth via electrolyte composition modification or electrical parameter adjustment, incorporation of nanoparticles into the electrolyte, and hybrid processes combining MAO with other surface treatment techniques (e.g., pre-/post-treatments). The performance of coatings obtained under different strategies is summarized, and a prospective outlook on future development trends in this field is offered. Full article

This study investigates the effects of phosphorus (P) on the phases developed during sintering and their impact on the stability of key phases in iron ore sinter, particularly the silico-ferrite of calcium and aluminum (‘SFCA’) series of phases. Two complementary systems were studied: an industrially representative blend of natural iron ores (JSM) and a synthetic high-purity SFCA analogue (SA) system designed to promote controlled SFCA formation. Phosphorus was added as hydroxyapatite (HA) at levels of 0.5, 1.0, 1.5 and 5 wt.%. To simulate a standard sintering profile, experiments were conducted over a range of temperatures for 3 min in a controlled low-oxygen-potential atmosphere of pO₂ = 5 × 10⁻³ atm. A modified Bond Abrasion test was used to evaluate the tumble index (TI) strength of the samples, and the chemistry, mineralogy and microstructure of all sintered products were analyzed. Results indicated that all P-doped JSM samples fired within the temperature range of 1300 to 1330 °C met the minimum strength requirement (TI = 80%) for producing high-quality sinters. Adding small to medium amounts of HA (≤1.5 wt.%) to both compositions had a limited impact on the overall mineral phases. Conversely, adding a high amount of HA (5 wt.%) encouraged the creation of Ca–Si–P phases. Analysis of the microstructure, minerals, and microchemistry indicated that P tended to segregate phases rich in phosphorus by interacting with calcium oxide and silica. The findings from the study highlight that at the low levels of P typically found in iron ores, there is no significant impact on the strength, mineralogy and phases formed during sintering. Full article

Plasma electrolytic oxidation (PEO) is an effective method for developing protective conversion coatings on magnesium and its alloys. The efficiency of this process is governed by several factors, including electrical parameters and electrolyte composition. Typically, PEO has been performed in alkaline silicate or phosphate solutions, often enriched with simple fluoride ions (F⁻) to improve the mechanical and anticorrosive properties of the resulting layers. Recently, the positive impact of complex fluoride ions (such as ZrF₆²⁻, TiF₆²⁻, SiF₆²⁻, AlF₆³⁻ and PF₆⁻) on the properties of conversion coatings on magnesium substrates has been shown. This review analyzes how these complex precursors influence the phase composition, morphology, and corrosion resistance of coatings. Furthermore, these parameters are compared with those obtained by using electrolytes composed of a mixture of simple fluorides and additional constituents that provide the incorporation of the appropriate elements into the coating structure (phosphorus, silicon, zirconium, titanium, or aluminum). It was indicated that when using complex fluoride salts, an important aspect is the stability of the electrolyte, which depends on pH and the presence of stabilizing additives. Ensuring that the decomposition of the complex fluoride occurs during the PEO process increases the amount of fluorine incorporated into the layers formed, leading to the formation of a coating with enhanced properties. Full article

Plasmonic nanostructures offer a practical solution for solar-to-thermal conversion, yet simultaneously achieving ultra-broadband absorption, scalable fabrication, and long-term stability using earth-abundant aluminum remains difficult. In this work, we present a three-dimensional (3D) crown-like aluminum nanostructure absorber that achieves an experimental average absorption of 92% across the solar spectrum (200–2500 nm), with only 1.9% degradation in average absorption over 24 months. The structure is fabricated via a scalable anodic aluminum oxide (AAO) template-assisted method, enabling large-area production without costly lithography and exhibiting broad fabrication tolerance to deposition-thickness variations. Electromagnetic simulations and structure analysis reveal that the ultra-broadband absorption arises from three synergistic mechanisms: multi-mode electric resonances, magnetic resonance behavior within the metal–dielectric–metal architecture, and a graded-refractive-index profile. Proof-of-concept photothermal experiments under simulated sunlight offer experimental confirmation of the absorber’s solar-to-thermal conversion capability, showing substantially enhanced solar-to-thermal energy utilization compared to pure-water references. This work provides a scalable, durable, and cost-effective platform for ultra-broadband solar absorption and solar-to-thermal conversion, and offers a viable design strategy for plasmonic absorbers based on earth-abundant materials. Full article

Pork jerky is vulnerable to quality deterioration during distribution, particularly under hot and humid conditions. This study investigated the deterioration pattern and associated mechanisms for vacuum-packaged pork jerky sealed in aluminum foil pouches during accelerated high-temperature and high-humidity storage (65 °C and relative humidity of 85%). The sensory quality, physicochemical properties, oxidation-related changes, non-enzymatic browning, and protein digestibility were evaluated, and multivariate analyses were performed to characterize the deterioration process. Sensory acceptability declined markedly, and the rejection rate reached 50% on day 14, indicating the shelf-life endpoint under the test conditions. Deterioration in quality was mainly characterized by color darkening, texture hardening, water redistribution, and microstructural disruption. Lipid oxidation, protein oxidation, myoglobin oxidation, and non-enzymatic browning progressively intensified during storage and were associated with the observed color deterioration and sensory decline. Microbiological indicators remained below the detection limit throughout storage, suggesting that quality deterioration was primarily associated with chemical rather than microbial changes. Multivariate analyses further suggested that lipid oxidation, protein oxidation, myoglobin oxidation, and non-enzymatic browning were key processes potentially associated with quality loss. These findings provide a basis for shelf-life evaluation and quality control for pork jerky under extreme storage conditions. Full article

A strategy combining imprinting with anode oxidation is proposed for preparing an aluminum template with a negative compound-eye array. Injection compression molding with the aluminum template mounted on the mold cavity surface is applied to fabricate polystyrene replicas with a biomimetic compound-eye array on their surfaces. It is demonstrated that orderly microlenses and dense nanopillars with average diameters of approximately 225 μm and 63 nm, respectively, are formed on the polystyrene replicas. The polystyrene replica surfaces with the compound-eye array exhibit both hydrophobicity, with a water contact angle of 151 ± 2° and a rolling angle of 4 ± 1°, and excellent antireflectivity, showing an average reflectance of approximately 4% across the 400–1000 nm wavelength range. The microlens and nanopillar structures on the PS replicas are therefore key to achieving both hydrophobicity and antireflectivity simultaneously. The proposed fast mass-replication approach, which combines imprinting, anode oxidation, and injection compression molding, offers an efficient route for producing bioinspired compound-eye arrays. This strategy shows potential for applications in optoelectronics, photovoltaics, and self-cleaning optical surfaces. Full article

Copper–aluminum (Cu-Al) wire-bonded devices are widely used in microelectronic packaging; however, corrosion at exposed Cu-Al bimetallic interfaces can lead to Al pad degradation, undercutting, and eventual ball-bond lift-off or open-circuit failure under humid, halide-contaminated conditions. This work presents a scalable post-wire-bond wet-chemical passivation process using octadecylphosphonic acid (ODPA) to simultaneously modify exposed Cu/Pd-coated Cu (PCC) and Al surfaces. The passivation process includes a hydroxylation pretreatment to generate reactive oxide/hydroxide surface sites, followed by ODPA treatment and solvent rinsing to remove weakly adsorbed species. Surface modification was evaluated using contact-angle measurements, reflection–absorption infrared spectroscopy (RAIRS), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). ODPA treatment increased the water contact angle on Cu and Al, confirming a substantial increase in surface hydrophobicity following coating formation. RAIRS identified ODPA-associated aliphatic C-H bands, AFM showed treatment-induced nanoscale surface changes, and XPS supported metal–oxygen–phosphorus interfacial bonding. Under aggressive 100 ppm chloride-ion immersion, ODPA passivation strongly suppressed corrosion-induced ball-bond lift-off across both device platforms. Lift-off decreased from 99.0% to 0.73% for Cu-Al devices and from 23.3% to 0.42% for PCC-Al devices. Collectively, these findings establish an effective, process-compatible post-wire-bond strategy for substantially protecting corrosion-susceptible interfaces and thereby improving the reliability of wire-bonded interconnects in halide-containing environments. Full article

Aluminum/magnesium (Al/Mg) hybrid structures are promising candidates for lightweight engineering, but reliable joining is still limited by brittle intermetallic compounds (IMCs), oxide films, pores, cracks, and corrosion-related degradation. This review summarizes recent advances in Al/Mg dissimilar-metal joining, including solid-state welding, fusion welding, brazing, resistance-based joining, and mechanical joining. Emphasis is placed on process characteristics, interfacial reactions, defect formation, mechanical properties, service reliability, and simulation-assisted process understanding. The reviewed studies indicate that joint reliability cannot be interpreted solely from IMC thickness; phase type, continuity, spatial distribution, interfacial morphology, and involvement in the fracture path are also critical. Solid-state and high-speed impact processes can restrict continuous Al–Mg reaction layers by reducing thermal exposure and promoting plastic contact, whereas fusion-based processes provide greater manufacturing flexibility but require stricter control of molten-pool behavior, Mg evaporation, porosity, and interlayer stability. Recent numerical simulations and data-driven studies are further discussed as tools for mechanism-guided parameter design. This review provides an integrated comparison of joining routes and highlights future needs for standardized testing, fatigue and corrosion evaluation, thermal-cycling assessment, coupled service-performance analysis, and process selection for engineering applications. Full article

Electrocoagulation (EC) is a promising technology for hypereutrophic wastewater treatment, yet reactor geometry, electrode passivation, and energy inefficiency remain key limitations. This study developed a graphene oxide–phosphomolybdate (GO–POM) composite cathode integrated into an asymmetric electrode configuration (anode:cathode area ratio = 1:10) to simultaneously address charge-transfer resistance, passivation, and energy consumption in the EC treatment of Lake Mariut wastewater (Cairo, Egypt). The GO–POM composite exhibited a charge-transfer resistance of 2.34 ± 0.09 Ω·cm², significantly lower than that of a graphite rod (4.12 ± 0.31 Ω·cm²), carbon felt (3.28 ± 0.24 Ω·cm²), and SS316 (6.84 ± 0.45 Ω·cm²). Under optimized conditions (j = 10 mA/cm², pH 6.0, 60 min), the asymmetric GO–POM system achieved 92.2 ± 1.8% TOC removal with a specific energy consumption of 4.4 ± 0.3 kWh/m³—a 37% reduction compared to the symmetric conventional baseline (6.1 ± 0.4 kWh/m³). The treated effluent met the discharge limits set by Egyptian Law 48/1982 for COD, BOD, and TSS. Preliminary techno-economic and life-cycle analyses identified Al electrode consumption as the dominant cost and carbon driver, with a solar-powered continuous-flow operation as the priority pathway for further energy reduction. Full article