Search Results (166)

High-entropy ceramic (HEC) thin films generally refer to multi-component solid solutions composed of multiple metallic and non-metallic elements, existing in forms such as carbides, nitrides, and borides. Benefiting from the high-entropy effect, lattice distortion, sluggish diffusion, and cocktail effect of high-entropy systems, HEC thin films form simple amorphous or nanocrystalline structures while exhibiting high hardness/elastic modulus, excellent tribological properties, and thermal stability. Although the mixing entropy increases with the number of elements in the system, a higher number of elements does not guarantee improved performance. In addition to system configuration, the regulation of preparation methods and processes is also a key factor in enhancing performance. Arc ion plating (AIP) has emerged as one of the mainstream techniques for fabricating high-entropy ceramic (HEC) thin films, which is attributed to its high ionization efficiency, flexible multi-target configuration, precise control over process parameters, and high deposition rate. Through rational design of the compositional system and optimization of key process parameters—such as the substrate bias voltage, gas flow rates, and arc current—HEC thin films with high hardness/toughness, wear resistance, high-temperature oxidation resistance, and electrochemical performance can be fabricated, and several of these properties can even be simultaneously achieved. Against the backdrop of AIP deposition, this review focuses on discussions grounded in the thermodynamic principles of high-entropy systems. It systematically discusses how process parameters influence the microstructure and, consequently, the mechanical, tribological, electrochemical, and high-temperature oxidation behaviors of HEC thin films under various complex service conditions. Finally, the review outlines prospective research directions for advancing the AIP-based synthesis of high-entropy ceramic coatings. Full article

Urban morphology plays a decisive role in regulating microclimate and outdoor thermal comfort in arid cities, where extreme heat and intense solar radiation amplify thermal stress. This study examines the influence of four contrasting urban fabrics in Béchar (Algerian Sahara): the vernacular Ksar, the regular-grid colonial fabric, a modern large-scale residential estate, and low-density detached housing, on local microclimatic conditions. An integrated methodological framework is adopted, combining qualitative morphological analysis, quantitative indicators including density, porosity, height-to-width ratio, and sky view factor, in situ microclimatic measurements, and high-resolution ENVI-met simulations performed for the hottest summer day. Results show that compact urban forms, characterized by low sky view factor values, markedly reduce radiative exposure and improve thermal performance. The vernacular Ksar, exhibiting the lowest SVF, records the lowest mean radiant temperature (approximately 45 °C) and the most favorable average comfort conditions (PMV = 3.77; UTCI = 38.37 °C), representing a reduction of about 3 °C, while its high-thermal-inertia earthen materials ensure effective nocturnal thermal recovery (PMV ≈ 1.06; UTCI = 27.8 °C at 06:00). In contrast, more open modern fabrics, including the colonial grid, large-scale estates, and low-density housing, experience higher thermal stress, reflecting vulnerability to solar exposure and limited thermal inertia. Validation against field measurements confirms model reliability. These findings highlight the continued relevance of vernacular bioclimatic principles for sustainable urban design in arid climates. Full article

Spinel-based glass-ceramics face challenges such as a narrow crystallization window for the target phase and the difficulty in suppressing the competitive Li_xAl_xSi_1−xO₂ crystals. This study proposes a method to regulate the phase formation in ZnO-MgO-Al₂O₃-SiO₂ glass by precisely controlling the heat treatment temperature. The microstructural evolution was analyzed by DSC, XRD, Raman spectroscopy, SEM, TEM, and XPS. The results indicate that the heat treatment at a nucleation temperature of 780 °C for 2 h and a crystallization temperature of 880 °C for 2 h effectively inhibits the precipitation of the Li_xAl_xSi_1−xO₂ secondary phase, yielding a glass-ceramic with nano-sized MgAl₂O₄, ZnAl₂O₄ spinel as the primary crystalline phase. The obtained glass-ceramic exhibits excellent mechanical properties, including a Vickers hardness of 922.6 HV, a flexural strength of 384 MPa, and an elastic modulus of 113 GPa, while maintaining a high visible light transmittance of 84.3%. This work provides a clear processing window and theoretical basis for fabricating high-performance, highly transparent spinel-based glass-ceramics through tailored heat treatment. Full article

Arabinoxylans (AX) are polysaccharides capable of forming covalent gels stable under variations in pH and temperature. They are fermentable by the colonic microbiota, making them appropriate carriers for colon-targeted oral drug delivery, including insulin. This study aimed to fabricate covalent AX nanoparticles loaded with insulin (NPAXI) using a 0.25 (AX/insulin) mass ratio and to evaluate their colon-targeted capacity to improve glycemic control in diabetic rats. In parallel, we assessed gut microbiota modulation as a secondary outcome, derived from the prebiotic fermentation of AX, considered an additional benefit. NPAXI, produced by coaxial electro spraying, displayed a mean diameter of 661 nm, a zeta potential of −31 mV, and high insulin encapsulation efficiency. Bioassay demonstrated that a single oral NPAXI dose restored normoglycemia for 9 h, starting 15 h post-administration. Gut microbiota analysis revealed that while insulin alone increased Lactobacillaceae, it failed to suppress Enterobacteriaceae. NPAXI treatment, however, promoted beneficial taxa such as Muribaculaceae and Prevotellaceae and reduced proinflammatory families like Desulfovibrionaceae and Helicobacteraceae. These microbial shifts paralleled the improved glycemic profile, suggesting a synergistic interaction between AX and insulin in reestablishing gut microbial homeostasis and metabolic regulation. Overall, NPAXI represents a promising strategy for colon-targeted oral insulin delivery, offering additional microbiota-modulating benefits. Full article

The Zn-3Mg alloy fabricated by laser powder bed fusion (LPBF) additive manufacturing is widely used in biomedical implants due to its excellent biocompatibility and favorable mechanical strength. However, its application is hindered by limited ductility and a relatively rapid degradation rate. This study investigated the influence of annealing heat treatment on the microstructure, mechanical properties, and degradation behavior of LPBF-fabricated Zn-3Mg porous implants. A systematic analysis of various annealing parameters revealed the evolution mechanisms of the microstructure, including grain coarsening and the precipitation and distribution of secondary phases Mg₂Zn₁₁ and MgZn₂. The results indicated that appropriate annealing conditions (such as 250 °C for 1 h) significantly enhanced the compressive strain by 10%, while maintaining a high compressive strength of 24.72 MPa. In contrast, excessive annealing temperatures (e.g., 365 °C) promoted the formation of continuous brittle phases along grain boundaries, leading to deterioration in mechanical performance. The degradation behavior analysis illustrated a substantial increase in the corrosion rates from 0.6973 mm/year to 1.00165 mm/year after annealing at 250 °C for 0.5 h and 365 °C for 1 h, which can be attributed to the micro-galvanic effect induced by the presence of fine or coarse secondary phases that promoted localized corrosion. This study demonstrated synergistic regulation of mechanical properties and degradation behavior in the Zn-3Mg porous structures through optimized heat treatment, thereby providing essential theoretical and experimental supports for the clinical application of biodegradable zinc-based implants. Full article

This work presents a fused-filament fabrication (FFF) hot end that combines an unrestricted-rotation C-axis with a rectangular-slot nozzle and an induction-heated melt sleeve. The architecture replaces the popular resistive cartridge and heater block design with an external coil that induces eddy-current heating in a thin-walled sleeve, threaded to the heat break and nozzle, reducing thermal mass and eliminating wired sensors across the rotating interface. A contactless infrared thermometer targets the nozzle tip; the temperature is regulated by frequency-modulating the inverter around resonance, yielding stable control. The hot end incorporates an LPBF-manufactured nozzle, which transitions from a circular inlet to a rectangular outlet to deposit broad, low-profile strands at constant layer height while preserving lateral resolution. The concept is validated on a desktop Cartesian platform retrofitted to coordinate yaw with XY motion. A twin-printer testbed compares the proposed hot end against a stock cartridge-heated system under matched materials and environments. With PLA, the induction-heated, rotating hot end enables printing at 170 °C with defect-free flow and delivers substantial reductions in job time (22–49%) and energy per part (9–39%). These results indicate that the proposed approach is a viable route to higher-throughput, lower-specific-energy material extrusion. Full article

The roll-to-plate (R2P) hot-embossing process is a newly developed molding technique for the high-throughput, high-efficiency fabrication of large-area microstructured optical elements. However, this technology is limited to flat surfaces, because the thickness of the freeform optical plate varies constantly due to its specific optical design, while the roll stays cylindrical during rolling. Therefore, we developed a new profile-tunable roll with several groups of semiconductor heater/coolers (SHCs) attached around the inside wall of the roll. These SHCs can achieve tunable roll profiles at desirable positions by regulating the current for the semiconductor and then the roll temperature, thereby producing optics with a selected freeform. In this paper, the circumferential bulging profiles and corresponding roll temperature fields were thoroughly investigated under various heater/cooler layouts and roll sizes. A circumferential finite element model of the profile-tunable roll was established using the finite element software MSC.MARC 2020 and then verified on the experimental platform. In addition, the fundamental relationship between the bulging values and temperature distributions of the roll and parameters, such as the outer diameter and inner diameter of the roll, the temperature of the semiconductor heater/cooler, and the single piece influence angle, was eventually established. This paper offers a unique fabrication method for high-volume optical freeform plates at extremely low cost and builds a foundation for further research on the axial deformation and temperature distribution of the developed roll for freeform optics and R2P hot-embossing experiments for freeform optical components. Full article

Body-contouring devices deliver controlled thermal energy to treat cellulite, reduce localized fat, and improve skin elasticity. Since the thermal effect is closely related to the delivered RF output power, precise control of the output power is critical for both efficacy and safety. In this study, we propose a 2.4 GHz CMOS pulse-mode transmitter for body-contouring device applications, featuring precise control of the average power delivered to the body. The transmitter comprises a fully integrated phase-locked loop (PLL) synthesizer, pulse modulator (PM), and 10 mW power amplifier (PA). It is fabricated in a 65 nm CMOS with a compact die area of 3.75 mm². The PA provides four-level continuous-mode output control from −0.3 dBm to 11.1 dBm, and the PM performs programmable PA switching for pulse-mode operation of the PA with a wide range of pulse rates and duty ratios. By combining the continuous-mode output power control and pulse-mode on–off time regulation, the average output power delivered to the skin is finely controlled, managing the delivered power within a safe skin temperature below 65 °C. The PLL loop filter is fully integrated with a wide programmability, improving the form factor and bill of materials for the target devices. Measurement results confirm that the designed transmitter can accurately control both the average output power and pulse profile across the 2.4 GHz ISM band, demonstrating its suitability for compact home-use RF body-contouring devices. Full article

This study fabricated six types of NiCr–Cr₃C₂ composite coatings using high-velocity oxygen fuel (HVOF) spraying and systematically evaluated their tribological behavior at 350 °C and 500 °C, along with their electrochemical corrosion performance in 3.5 wt.% NaCl solution. The objective was to elucidate how compositional design regulates the coatings’ microstructure, mechanical properties, and service performance. Results indicate that the 75NiCr–25Cr₃C₂ coating (C) formed a stable oxide film under both temperatures, exhibiting oxidation-dominated wear and the lowest friction coefficient and wear rate. When the temperature increased from 350 °C to 500 °C, the wear rates of coatings C, B, E, and F decreased significantly. Notably, coatings E and F, which contained CoCrFeNiMo high-entropy alloy, showed more than a 50% reduction in wear rate, demonstrating the contribution of the high-entropy phase to high-temperature wear resistance. At 350 °C, coatings B, D, E, and F experienced primarily abrasive wear; at 500 °C, however, E and F shifted to oxidative wear as the dominant mechanism, leading to a marked improvement in wear resistance. Electrochemical measurements revealed that coating E exhibited the best corrosion resistance, while the NiCr coating (A) performed the worst. The findings highlight that optimizing Cr₃C₂ content and incorporating high-entropy alloy elements can synergistically enhance both high-temperature tribological properties and corrosion resistance. Full article

Yttrium oxide (Y₂O₃) films have been widely used as protective layers in plasma etching equipment, but achieving stoichiometric films with high deposition rates remains a challenge. In this study, Y₂O₃ films were fabricated by a medium-frequency reactive magnetron sputtering (MF-RMS) technique. The oxygen flow and target control voltage were regulated through a closed-loop feedback control system, which effectively solved the problem. The microstructure, mechanical, optical, and plasma etching properties were systematically investigated. The results showed that near-stoichiometric films can achieve a relatively high deposition rate. Increasing the deposition temperature induced a structural transition in the Y₂O₃ film from a predominantly cubic phase to a mixture of cubic and monoclinic phases. For Y₂O₃ films deposited at room temperature, increasing the bias voltage increased the deposition rate but reduced hardness and elastic modulus. The Y₂O₃ film deposited at 300 °C in the near-metallic mode exhibited the highest hardness and elastic modulus, reaching 13.3 GPa and 222.0 GPa, respectively. All Y₂O₃ films exhibited excellent transmittance and resistance to plasma etching. This study provides an effective protective strategy for semiconductor etching chambers. Full article

The escalating climate change and extreme weather conditions have highlighted the limitations of conventional textiles in body temperature regulation Phase-change thermoregulatory fibers can maintain constant temperature when environmental conditions fluctuate, effectively meeting human comfort requirements. To investigate the temperature-regulating properties of TempSolution viscose/cotton thermoregulatory yarn in seamless knitted fabrics, this study examined three different knitted fabric structures along with varying blend ratios and linear densities of TempSolution viscose/cotton yarn as experimental variables. According to a full factorial experimental design, eighteen fabric samples and corresponding garment prototypes were produced on a seamless circular knitting machine. Differential scanning calorimetry (DSC) and thermal manikin tests were conducted to compare the thermoregulatory performance and thermal comfort of seamless knits with different yarn compositions and structures. The results demonstrated that among the fabric structures, the 1 + 3 mock rib configuration exhibited superior thermal resistance and comfort properties. Regarding yarn types, the 50/50 TempSolution blend with 50 s yarn count showed relatively superior performance across all test parameters, providing a theoretical foundation for developing phase-change knitted fabric. Full article

Graphene, owing to its exceptional mechanical properties and interfacial modulation capability, is considered an ideal material for enhancing the interfacial strength and damage resistance during the fabrication of ultra-thin lithium foils. Although previous studies have demonstrated the reinforcing effects of graphene on lithium metal interfaces, most analyses have been restricted to single-temperature or idealized substrate conditions, lacking systematic investigations under practical, multi-temperature environments. Consequently, the influence of graphene coatings on lithium-ion conductivity and mechanical stability under real thermal conditions remains unclear. To address this gap, we employ LAMMPS-based molecular dynamics simulations to construct atomic-scale models of pristine lithium and graphene-coated lithium (C/Li) interfaces at three representative temperatures. Through comprehensive analyses of dislocation evolution, root-mean-square displacement, frictional response, and lithium-ion diffusion, we find that graphene coatings synergistically alleviate interfacial stress, suppress crack initiation, reduce friction, and enhance ionic conductivity, with these effects being particularly pronounced at elevated temperatures. These findings reveal the coupled mechanical and electrochemical regulation imparted by graphene, providing a theoretical basis for optimizing the structure of next-generation high-performance lithium metal anodes and laying the foundation for advanced interfacial engineering in battery technologies. Full article

To address challenges such as temperature rise, operational instability, and premature failure in rolling bearings caused by retainer friction, this study designed and developed a high-performance polyimide (PI)-based composite self-lubricating retainer to enable “ultra-stable” bearing operation. Both solid and oil-porous self-lubricating retainers were fabricated through material composition and structural design. Systematic tests under controlled load and speed conditions were conducted to compare their temperature rise behavior and wear morphology. The results demonstrated that the temperature rise in the YSU-PI1 bearing with a solid retainer decreased by approximately 57% compared to a conventional bearing. The YSU-PA2 bearing with an oil-porous retainer exhibited a further improvement in thermal performance. Notably, under high-speed conditions, the equilibrium temperature of the YSU-PA2 bearing was lower than that under low-speed conditions, confirming a centrifugal-force-driven self-regulating oil-supply mechanism. Wear surface analysis revealed that the porous structure promoted the formation of a continuous and uniform transfer film, effectively mitigating wear and pitting. This study successfully integrates “material–structure–function” innovation. The oil-porous PI-based composite retainer transforms centrifugal force—typically considered detrimental—into a beneficial lubrication mechanism, effectively suppressing temperature rise and enabling “ultra-stable operation”. These findings provide crucial theoretical and technical support for developing bearings for high-end equipment. Full article

Laser melting deposition (LMD), one of the novel powder-to-powder welding technologies, has emerged as an ideal method for fabricating lightweight high-temperature Ti₂AlNb alloy. However, the high thermal gradients and heat accumulation during the LMD process typically promote grain growth along the deposition direction, resulting in coarse columnar grains and high internal residual stress. This study investigates the influence of prolonged aging treatment and internal cyclic heat on the microstructure and mechanical properties of Ti₂AlNb alloys. Both long-term aging and internal cyclic heat induce the columnar-to-equiaxed grain morphology transition. A 48 h aging heat treatment at 750 °C facilitates the formation of a B2 + O dual-phase lamellar structure, leading to a significant improvement in room-temperature strength. Internal cyclic heat effectively reduces the cooling rate, eliminates internal stress, and suppresses the precipitation of the brittle and detrimental α₂ phase. This results in a more homogeneous distribution of O-phase laths, raising the room-temperature tensile strength from 938 MPa to 1215 MPa and achieving a high-temperature strength of 1116 MPa at 650 °C. These improvements demonstrate a synergistic enhancement in both room- and high-temperature strength and ductility, which provides an efficient strategy for in situ regulation of the microstructure and mechanical properties of laser-deposited Ti₂AlNb alloys. Full article

Pickering emulsions have emerged as promising multiphase systems owing to their high stability and diverse applications in materials and chemical engineering. However, achieving precise and stimuli-responsive regulation of emulsion type, particularly reversible phase inversion between oil-in-water and water-in-oil states under fixed formulation without additional stabilizers, remains a considerable challenge. In this work, we developed a sol–gel strategy, i.e., in situ hydrolysis and condensation of silane precursors to form a silica shell directly on responsive microgels, to produce H-SiO₂@P(NIPAM-co-MAA) hybrid microgels. The resulting hybrid particles simultaneously retained pH and temperature responsiveness, enabling the transfer of these properties from the polymeric network to the emulsion interface. When employed as stabilizers, the hybrid microgels allowed the controlled formation of Pickering emulsions that remained stable for one week under testing conditions. More importantly, they facilitated in situ reversible phase inversion under external stimuli. Overall, this work establishes a sol–gel approach to fabricate organic–inorganic hybrid microgels with well-defined dispersion and uniform silica deposition, while preserving dual responsiveness and enabling controlled phase inversion of Pickering emulsions. Full article