Search Results (4,086)

To enhance the long-term corrosion resistance of micro-arc oxidation coatings on magnesium alloys, this study regulated the ionic composition of the electrolyte based on the solubility product rule. In the silicate system, a micro-arc oxidation coating mainly composed of magnesium silicate was successfully prepared on AZ31A magnesium alloy by synergistically optimizing the ratio of SiO₃²⁻/F⁻. The results show that the addition of KF significantly promotes coating growth, with the thickness increasing from 19.32 μm to a maximum of 46.86 μm. As the Na₂SiO₃ concentration increases, the main phase of the coating changes from MgO to Mg₂SiO₄. Electrochemical tests indicate that the coating prepared with 30 g/L Na₂SiO₃ and KF addition exhibits the best corrosion resistance, demonstrating the lowest corrosion current density of 3.89 × 10⁻⁹ A·cm⁻², which is approximately four orders of magnitude lower than that of the uncoated substrate. However, when the Na₂SiO₃ concentration is too high, the corrosion resistance decreases due to increased pore size and defects, confirming a non-monotonic relationship between silicate concentration and coating performance. Full article

Background: Platelet-rich fibrin (PRF) is an autologous platelet concentrate (APC) produced through blood centrifugation. Despite the development of various centrifugation systems, protocol variability continues to pose challenges in selecting the optimal method. This study investigated the effects of three different centrifuges and collection tubes on the fibrin characteristics and growth factor release in leukocyte- and platelet-rich fibrin (L-PRF) and advanced platelet-rich fibrin plus (A-PRF+). Methods: Blood samples from six healthy female volunteers were processed using three centrifuges (Duo, IntraSpin, and LMC-3000) and three collection tubes (Pyrex, A-P, and silica-coated plastic) under high- (~700× g for 12 min) and low-speed (~200× g for 8 min) protocols. Fibrin clot weight and length were assessed. Growth factor release of platelet-derived growth factor-BB (PDGF-BB) and vascular endothelial growth factor (VEGF) was quantified using ELISA. Fibrin architecture was examined via scanning electron microscopy (SEM). Results: High-speed protocols tended to produce larger clots, whereas low-speed protocols generated smaller but more biologically active matrices. The IntraSpin and Duo centrifuges yielded greater clot dimensions and higher growth factor release than the LMC-3000. While tube type had no significant effect on growth factor levels, silica-coated tubes tended to produce the largest clots. The Pyrex tubes demonstrated comparable or superior growth factor release. Conclusions: PRF quality is influenced by centrifuge design, g-force, and tube material. Low-speed protocols with certified centrifuges are recommended, and FDA-approved glass tubes may provide a reliable alternative to reduce silica-related risks. Standardization and appropriate material selection are essential for consistent, safe, and effective regenerative outcomes. Full article

In this study, two types of gas sensors—silicone-based interdigital electrode and silicon micropillar sensors based on rGO and rGO/SnO₂—were fabricated. Their gas-sensing performance was investigated at room temperature. First, interdigital electrodes of different channel widths were fabricated to investigate the impact of the channel width parameter. Subsequently, the rGO/SnO₂ doping ratio in the composite material was varied to identify the optimal composition for gas sensitivity. Additionally, triangular and square-arrayed silicon micropillar substrates were fabricated via photolithography and inductively coupled plasma etching. The rGO/SnO₂-based gas sensor on a silicon micropillar substrate exhibited an ultra-high specific surface area. The triangular micropillar arrangement of rGO/SnO₂-160 demonstrates the best performance, showing approximately 14% higher response and a 106 s reduction in response time compared with interdigital electrode sensors spray-coated with the same concentration of rGO/SnO₂ when tested at room temperature under 250 ppm NO₂. The optimized sensor achieves a detection limit as low as 5 ppm and maintains high responsiveness, even in conditions of 60% relative humidity (RH). Additionally, the repeatability, selectivity, and stability of the sensor were evaluated. Finally, structural and morphological characterization was conducted using XRD, SEM, TEM, and Raman spectroscopy, which confirmed the successful modification of rGO with SnO₂. Full article

This review establishes a comprehensive technical framework for aerogel-based fire-resistant coatings, from fundamental mechanisms to industrial applications. It analyses the multi-mode flame-retardant and thermal insulation mechanisms achieved through aerogels’ synergistic suppression of heat conduction, convection, and radiation, establishing their theoretical basis. The work compares the intrinsic characteristics of silica-based, carbon-based, and bio-based aerogels, providing rational selection criteria for fire protection systems. The study examines key integration challenges: balancing nanopore preservation with interfacial compatibility, inherent mechanical weaknesses, conflicts between high filler loading and workability, and scalability issues. It evaluates targeted strategies including interface engineering, mechanical reinforcement, workability optimization, and low-cost production routes. Application prospects in construction, tunneling, and cable protection are outlined. This review provides a coherent progression from mechanisms and material properties to challenges and solutions, offering theoretical guidance and a technical roadmap for developing next-generation high-performance fire-resistant coatings. Full article

The aim of this research was to extend the freshness of pistachio (Pistacia vera L.) by using edible coatings during cold storage. Different coatings—chitosan with potassium sorbate, alginate with propionic acid, and zein with EDTA—were used for both in-hull and dehulled pistachios. Effects of coatings on Aspergillus flavus count, peroxide, free fatty acids (FFA), water activity, and aflatoxin levels were investigated. Principal component analysis (PCA), correlation analysis, and multi-objective optimization were applied to interpret the data. The used coatings and pistachio hulls were effective in slowing down the formation of FFA and peroxides (p < 0.05). Zein and chitosan coatings prevented Aspergillus flavus growth up to 5 months while the alginate coating provided superior sensory preservation. PCA revealed that pistachio hulls decreased the aflatoxin, FFA, and peroxide formation, and the hulls of the pistachios showed a protective effect. Also, sensory parameters had negative correlations with FFA and peroxide value. From the optimization study, the best way to increase the freshness of pistachio is through the use of an alginate coating for in-hull. This study showed that alginate and chitosan coatings combined with ozone treatment and vacuum packaging can be used to prolong the freshness of pistachio. Full article

UV radiation is responsible for acute and chronic adverse effects on the skin. In recent years, it has been shown that various phenolic acids, particularly cinnamic acid derivatives, prevent some of these effects. In the present study, the design and synthesis of three esters of ferulic acid, analogues of the octyl methoxycinnamate (OMC), one of the most commercially used filters, are presented. The esters were evaluated for their photoprotective activity against UVA and UVB radiation. The ester 3b exhibited an SPF of 9.22 and a λ_c value of 343.9, higher than the values of OMC (SPF value: 8.19, λ_c value: 337.7). The development and optimization of a novel encapsulation process of the synthesized esters in nanostructured lipid carriers (NLCs) and coating of the NLCs with chitosan was also performed. The optimization of the coating processes was performed using a Box–Behnken experimental design. The optimal nanosystems exhibited a size of 117.0 ± 5 nm, enhanced stability in dispersion, and 78% encapsulation efficiency. The nanoparticles were characterized by ATR/FT–IR, TGA, and TEM. Incorporation of the nanoparticle dispersions in a sunscreen formulation increased the SPF factor of the formulation up to 48%. The esters and nanosystems also showed a satisfactory ability to inhibit the peroxidation of linoleic acid (AAPH induced lipid peroxidation assay) (74–91% inhibition). Full article

Cryopreservation is a well-established method for extending platelet shelf-life and addressing supply shortages. Traditionally, this involves dimethyl sulfoxide (DMSO) as a cryoprotective agent (CPA), but recent studies suggest that using controlled rate freezing (CRF) with only NaCl may offer a less toxic alternative. To explore further optimization, this study assessed whether adding 10% choline chloride–glycerol, a deep eutectic solvent (DES), could enhance platelet quality in CRF/NaCl cryopreservation. Ten double-dose buffy coat platelet units were divided into test (DES-treated) and control (NaCl-only) groups. After DES exposure (10% for 20 min), all units were prepared using the NaCl protocol and frozen at −80 °C with CRF equipment, then stored for over 90 days. Upon thawing and reconstitution in AB plasma, no significant differences were observed in platelet content post-thaw between control and test units (255 ± 43 vs. 257 ± 41 × 10⁹/unit), post-thaw recovery (>85%): respectively, Δψ (JC-1% pos 63 ± 15 vs. 68 ± 17), LDH (% of total 10 ± 6 vs. 9 ± 6), (CD63% 77 ± 9 vs. 82 ± 7), (CD62P % 72 ± 15 vs. 76 ± 11), (CD42b % 78 ± 9 vs. 80 ± 9), (CD61% 79 ± 9 vs. 78 ± 9), (CD41% 81 ± 11 vs. 83 ± 7), (PAC-1% 33 ± 10 vs. 32 ± 8), (Pecam-1% 78 ± 11 vs. 80 ± 8), (GPIV % 72 ± 10 vs. 74 ± 11), (LAMP-1% 26 ± 14 vs. 11 ± 9), (MPCD61+ % 41 ± 11 vs. 46 ± 10), (ROTEM CT 56 ± 7 vs. 55 ± 6), (ROTEM CFT 110 ± 70 vs. 106 ± 67) and (ROTEM MCF 35 ± 6 vs. 36 ± 6). These findings support the feasibility of CPA-free CRF-based platelet cryopreservation while maintaining functional integrity. Full article

To reduce the lightness and enhance the thermal resistance of Al-pigmented low-emissivity coatings, CuCr₂O₄ pigment was introduced into the coating system via ball milling. The results revealed that both ball milling time and Al: CuCr₂O₄ mass ratio significantly affect the optical and infrared properties of the coatings. When the milling time reached 9 h, the pigment attained an optimal flake morphology, leading to the best infrared performance of the composite coating. Additionally, the CuCr₂O₄ content effectively suppressed the lightness of Al-pigmented coatings. Compared to Al-pigmented low-emissivity coatings, the composite coating with an Al:CuCr₂O₄ ratio of 10:2 exhibited a reduction in L* value from 90 to 65. Meanwhile, it retained a low average infrared emissivity of 0.42 in the 3–5 μm and 8–14 μm ranges. Moreover, the incorporation of CuCr₂O₄ significantly improved the Al-pigmented coating’s thermal resistance from 500 °C to 600 °C. The composite coating maintained a Grade 1 adhesion rating with heat treatment of 600 °C due to a self-healing effect_. These composite coatings with low emissivity, low lightness, and high-temperature resistance are highly suitable for high-temperature and infrared stealth applications. Full article

Accumulation of dust on PV panels is a big challenge, especially in dry and semi-arid environments like Morocco, where the number of dust particles in the atmosphere diminishes the efficiency of solar panels severely. The review analyzes 30 recent studies, which provide insight into performance degradation by dust, as well as the search for solutions that mitigate this effect. Results show that dust reduced solar panel efficiency by between 10% and 40% based on environmental conditions, including dust density, composition, and length of exposure. Many technological approaches have been provided for the problem, including autonomous cleaning systems and advanced coatings, yet economic and scalability barriers are still in existence. Also, using AI in predictive maintenance provides good opportunities to optimize solar panel cleaning schedules to enhance energy production. This review concludes with the observation that, going forward, more research on long-term solutions and the development of sustainable and cost-effective cleaning technologies is urgently needed in order to better exploit solar energy in dusty environments. Full article

Aluminium plays a key role in developing modern energy technologies, from electrical systems to high-energy materials, providing a combination of functionality, economy, and reliability, but the oxide film on its particles reduces the effective reactivity. This work aims to increase the reactivity of aluminum powder by mechanochemical treatment using modifiers. The materials used were aluminum powder of the ASD brand and graphite of the GL-1 brand. The experiment subjected aluminum powder to mechanochemical treatment (MCT) with different graphite contents. It was shown that MCT significantly increases active aluminum content in the powder due to partial destruction of the oxide film on its surface. In addition, morphological analyses confirm the destruction of the oxide, the graphite coating, and the appearance of lamellar structures measuring 0–58 µm. Thermal analysis shows that the primary exothermic peak shifts from 662.6 °C to 653.9 °C for Al + 10% graphite, and the heat released increases by 27%, which means lower activation energy and more complete oxidation. However, at 20% graphite, the thermal gain decreases, since carbon shields the metal areas. Thus, the optimal content is 10% graphite: at this ratio, the best thermochemical behavior of the powder is achieved. The data obtained indicate that the MCT of aluminum powder with graphite effectively increases its reactivity. The resulting aluminum powders with modified particle surfaces facilitate the development of new technologies for the creation of various high-energy solid propellant systems. For rocket engines, preference is given to solid rocket propellant (SRP), which is a mixture of substances (components) capable of burning in the absence of air, producing a large amount of gaseous working fluid heated to a high temperature, providing thrust. Full article

This study aimed to develop an industrially scalable coating route for enhancing the oxidation resistance of carbon fiber fabrics, a critical requirement for next-generation aerospace and high-temperature composite structures. To achieve this goal, synthesis of hexagonal boron nitride (h-BN) layers was achieved via a single wet step in which the fabric was impregnated with an ammonia–borane/THF solution and subsequently nitrided for 2 h at 1000–1500 °C in flowing nitrogen. Thermogravimetric analysis coupled with X-ray diffraction revealed that amorphous BN formed below ≈1200 °C and crystallized completely into (002)-textured h-BN (with lattice parameters a ≈ 2.50 Å and c ≈ 6.7 Å) once the dwell temperature reached ≥1300 °C. Complementary XPS, FTIR and Raman spectroscopy confirmed a near-stoichiometric B:N ≈ 1:1 composition and the elimination of O–H/N–H residues as crystallinity improved. Low-magnification SEM (100×) confirmed the uniform and large-area coverage of the BN layer on the carbon fiber tows, while high-magnification SEM revealed a progressive densification of the coating from discrete nanospheres to a continuous nanosheet barrier on the fibers. Oxidation tests in flowing air shifted the onset of mass loss from 685 °C for uncoated fibers to 828 °C for the coating produced at 1400 °C; concurrently, the peak oxidation rate moved ≈200 °C higher and declined by ~40%. Treatment at 1500 °C conferred no additional benefit, indicating that 1400 °C provides the optimal balance between full crystallinity and limited grain coarsening. The resulting dense h-BN film, aided by an in situ self-healing B₂O₃ glaze above ~800 °C, delayed carbon fiber oxidation by ≈140 °C. Overall, the process offers a cost-effective, large-area alternative to vapor-phase deposition techniques, positioning BN-coated carbon fiber fabrics for robust service in extreme oxidative environments. Full article

This study examines the impact of varying pulse conditions on the properties of titanium diboride (TiB₂) coatings deposited by high-power impulse magnetron sputtering (HiPIMS). The coatings were prepared on steel substrates using an industrial-scale system. During the experiments, the HiPIMS frequency and pulse width were systematically varied to examine their influence on the coating’s microstructural, mechanical, and tribological properties. The obtained results show a correlation between process parameters and coating performance. A maximum hardness of 39.7 GPa and a coefficient of friction (CoF) as low as 0.68 were achieved. The best combination of mechanical properties was observed for coatings prepared in a frequency range of 600–1000 Hz and with a pulse width of 50 µs. Notably, the optimal tribological properties and surface roughness were obtained at 800 Hz and a 50 µs pulse width. This work demonstrates that fine-tuning HiPIMS pulse conditions is crucial for achieving high-quality TiB₂ coatings with enhanced functional performance. Full article

Fe–Cr–Nb–Al–C alloy coatings were firstly fabricated on a high-carbon forged steel surface via coaxial laser cladding. The morphological evolution with varying Nb contents and wear mechanisms of the coatings were systematically investigated through comprehensive analysis. The results indicate that Nb content critically governs the coating microstructure and mechanical properties. At low Nb levels, coarse grain-boundary networks of (Fe,Cr) solid solution embrittled by Cr₂₃C₆ are formed. Moderate Nb addition produces finely dispersed rod-shaped NbC precipitates. At higher Nb levels, the morphology evolves into a segregated martensite–ferrite dual-phase structure. The coating wear rate exhibits a parabolic dependence on Nb content, initially decreasing with moderate addition and then increasing with further Nb. Consequently, optimal wear resistance is achieved at a critical Nb content (3 wt.%) that establishes an optimal balance between NbC precipitation and phase uniformity, thereby minimizing debris generation and spalling. Full article

This study investigates the fabrication of a Cu-Mn-Al alloy coating on 27SiMn steel using Cold Metal Transfer (CMT) technology with an innovative Ar-B(OCH₃)₃ mixed shielding gas, focusing on the effect of the gas flow rate (5–20 L/min). The addition of B(OCH₃)₃ was found to significantly enhance process stability by improving molten pool wettability, resulting in a wider cladding layer (6.565 mm) and smaller wetting angles compared to pure Ar. Macro-morphology analysis identified 10 L/min as the optimal flow rate for achieving a uniform and defect-free coating, while deviations led to oxidation (at low flow) or spatter and turbulence (at high flow). Microstructural characterization revealed that the flow rate critically governs phase evolution, with the primary κI phase transforming from dendritic/granular to petal-like/rod-like morphologies. At higher flow rates (≥15 L/min), increased stirring promoted Fe dilution from the substrate, leading to the formation of Fe-rich intermetallic compounds and distinct spherical Fe phases. Consequently, the cladding layer obtained at 10 L/min exhibited balanced and superior properties, achieving a maximum shear strength of 303.22 MPa and optimal corrosion resistance with a minimum corrosion rate of 0.02935 mm/y. All shear fractures occurred within the cladding layer, demonstrating superior interfacial bonding strength and ductile fracture characteristics. This work provides a systematic guideline for optimizing shielding gas parameters in the CMT cladding of high-performance Cu-Mn-Al alloy coatings. Full article

Accurate thermal modeling of Terminal Test Masses (TTMs) is crucial for optimizing the sensitivity of gravitational wave interferometers like Virgo. In fact, in such gravitational wave detectors even minimal laser power absorption can induce performance-limiting thermal effects. This paper presents a detailed investigation into the steady-state thermal behavior of TTMs. In particular, future scenarios of increased intracavity laser beam power and optical coating absorption are considered. We develop and compare two numerical models: a comprehensive model incorporating volumetric heat absorption in both the multilayer coating and the bulk substrate, and a simplified reduced model where the coating’s thermal impact is represented as an effective surface boundary condition on the substrate. Our simulations were focused on a ternary coating design, which is a candidate for use in next-generation detectors. Results reveal that higher coating absorption localizes peak temperatures near the coating–vacuum interface. Importantly, the comparative analysis demonstrates that temperature predictions from the reduced model differ from the detailed model by only milli-Kelvins, a discrepancy often within the experimental uncertainties of the system’s thermo-physical parameters. This finding suggests that computationally efficient reduced models can provide sufficiently accurate results for thermal management and first-order distortion analyses. Moreover, the critical role of accurately characterizing the total power absorbed by the coating is emphasized. Full article