Search Results (12,480)

The surfaces of beech wood samples were treated with polyethylenimine (PEI) solutions at three different concentrations—0.5%, 1% and 2%—and two molecular weights—low molecular weight (LMW) and high molecular weight (HMW). The effects of PEI surface treatment of wood were characterized by FT-IR spectroscopy, the penetration depth of PEI (EPI fluorescence spectroscopy), the bonding position of PEI (by SEM), the wetting and surface energy, and the water uptake. After PEI treatment, the samples were coated with a water-based transparent acrylic coating (WTAC). The dry film thickness, the penetration depth of the coating, the adhesion strength and the surface roughness of the coated wood surface were evaluated. EPI fluorescence and SEM micrographs showed that PEI HMW chains were deposited on the surface, in contrast to PEI LMW, which penetrates deeper into layers of the wood cells. Treatment with a 1% PEI HMW solution resulted in a 72% reduction in water uptake of the wood (compared to untreated samples after 5 min of applying water droplets to the surface) and a 23.2% reduction in surface energy (compared to untreated samples) while maintaining the adhesion strength of the applied WTAC. The lower water uptake of the treated wood samples reduced the roughness of the coated surface, which is particularly important when the wood surface is finished with water-based coatings. Full article

Hydrogels are three-dimensional polymeric matrices capable of absorbing significant amounts of water or biological fluids, making them promising candidates for biomedical applications such as drug delivery and wound healing. In this study, novel hydrogels were synthesized using a photopolymerization method and modified with cisplatin-loaded protein carriers, as well as natural extracts of nettle (Urtica dioica) and chamomile (Matricaria chamomilla L.). The basic components of the hydrogel were polyvinylpyrrolidone and polyvinyl alcohol, while polyethylene glycol diacrylate was used as a crosslinking agent and 2-methyl-2-hydroxypropiophenone as a photoinitiator. The hydrogels demonstrated high swelling capacities, with values up to 4.5 g/g in distilled water, and lower absorption in Ringer’s solution and simulated body fluid (SBF), influenced by ionic interactions. Wettability measurements indicated water contact angles between 51° and 59°, suggesting balanced hydrophilic properties conducive to biomedical applications. Surface roughness analyses revealed that roughness values decreased after incubation, with Ra values ranging from 6.73 µm before incubation to 5.94 µm after incubation for samples with the highest protein content. Incubation studies confirmed the stability of the hydrogel matrix, with no significant structural degradation observed over 20 days. However, hydrogels containing 2.0 mL of protein suspension exhibited structural damage and were excluded from further testing. The synthesized hydrogels show potential for application as carriers in localized drug delivery systems, offering a platform for future development in areas such as targeted therapy for skin cancer or other localized treatments. Full article

The electrodes of thin film transistors (TFTs) have evolved from conventional single Cu layers to multi-layered structures formed by Cu and other metals or alloys. Different etching rates of various metals and galvanic corrosion between distinct metals may cause etching defects such as rough or uneven cross-sectional surfaces of stacked electrodes. Therefore, the etching of stacked electrodes faces new challenges. CD Bias and profile angle (PA) are two main performance indicators for the wet etching of TFT electrodes. Adjusting CD Bias and PAs quantitatively and evaluating their stability accurately is crucial to ensure the performance and yield of TFTs. In this work, the bilayer MoNb/Cu-stacked electrodes with different MoNb thicknesses and the MoNb/Cu/MTD triple-layered electrodes were prepared, and the influence of MoNb thickness and stacked structure on the CD Bias and PAs was investigated. It is found that in the H₂O₂-based etchant, the order of corrosion potential is E_MTD < E_MoNb < E_Cu; both MoNb/Cu and Cu/MTD will form a primary cell with MoNb or MTD as the anodes. The CD Bias and PAs of the MoNb/Cu bilayer structure also increase with MoNb thickness, but those of the MoNb/Cu/MTD triple-layered structure decrease with the introduction of the top MTD film. Finally, regression equations between CD Bias or PA and etching parameters were established based on the results of uniform experiments, and the 95% confidence intervals for CD Bias and PA were proposed after the Monte Carlo simulation. These obtained results provide a basis for quantitative adjustment of CD Bias and PA and precise control of etching stability. Full article

The fundamental notions of the intuitionistic hesitant fuzzy set (IHFS) and rough set (RS) are general mathematical tools that may easily manage imprecise and uncertain information. The EDAS (Evaluation based on Distance from Average Solution) approach has an important role in decision-making (DM) problems, particularly in multi-attribute group decision-making (MAGDM) scenarios, where there are many conflicting criteria. This paper aims to introduce the IHFR-EDAS approach, which utilizes the IHF rough averaging aggregation operator. The aggregation operator is crucial for aggregating intuitionistic hesitant fuzzy numbers into a cohesive component. Additionally, we introduce the concepts of the IHF rough weighted averaging (IHFRWA) operator. For the proposed operator, a new accuracy function (AF) and score function (SF) are established. Subsequently, the suggested approach is used to show the IHFR-EDAS model for MAGDM and its stepwise procedure. In conclusion, a numerical example of the constructed model is demonstrated, and a general comparison between the investigated models and the current methods demonstrates that the investigated models are more feasible and efficient than the present methods. Full article

Conjugated donor–acceptor (D-A) copolymers are widely used in optoelectronic devices due to their influence on the resulting properties. This study focuses on the synthesis and characterization of the conjugated D-A copolymer constructed with fluorene and di-2-thienyl-2,1,3-benzothiadiazole units, resulting in Poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4,7-di(2-thienyl)-2,1,3-benzothiadiazole)] (PFDTBT). The synthesis associated with reaction times of 48 and 24 h, the latter incorporating the phase-transfer catalyst Aliquat 336, was investigated. The modified conditions produced copolymers with higher molar masses (Mw > 20,000 g/mol), improved thermal stability and red emission at 649 nm. Furthermore, the resulting D-A copolymers exhibited uniform morphology with low surface roughness (P2—Ra: 0.77 nm). These improved properties highlight the potential of D-A copolymers based on PFDTBT for various optoelectronic applications, including photovoltaics, light-emitting devices, transistors and biological markers in the form of quantum dots. Full article

The emerging thermoplastic composite material PEKK exhibits superior thermal stability compared to PEEK. In this work, CF/PEKK laminates were fabricated using laser-assisted heating in AFP, and the effects of repass treatment on the mechanical properties and microstructure of the laminates were compared. The results show that after a single repass treatment, the tensile strength of the laminates increased by 28.39%, while the interlaminar shear strength increased by 11.9%, likely due to the distinct load-bearing components under the two loading conditions. Additionally, the repass treatment significantly improves the fiber/resin interface and surface roughness of the laminates. Full article

The development of a constitutive model for soil–structure contact surfaces remains a pivotal area of research within the field of soil–structure interaction. Drawing from the Gudehus–Bauer sand hypoplasticity model, this paper employs a technique that reduces the stress tensor and strain rate tensor components to formulate a hypoplastic model tailored for sand–structure interfaces. To capture the influence of initial anisotropy, a deposition direction peak stress coefficient is incorporated; meanwhile, a friction parameter is introduced to address the surface roughness of the contact. Consequently, a comprehensive hypoplastic constitutive model is developed that takes into account both initial anisotropy and roughness. Comparative analysis with experimental data from soils on contact surfaces with diverse boundary conditions and levels of roughness indicates that the proposed model accurately forecasts shear test outcomes across various contact surfaces. Utilizing the finite element software ABAQUS 2021, an FRIC subroutine was developed, which, through simulating direct shear tests on sand–structure contact surfaces, has proven its efficacy in predicting the shear behavior of these interfaces. Full article

In the article, the authors attempted to analyze the impact of such materials factors as surface emissivity, surface roughness, air gap thickness, and type of concrete on heat transport in the microstructure of vertical multilayer building walls. The surface analysis conducted using three-dimensional modeling tools provided information about the formation of its microstructure before and after the application of a reflection-smoothing coating, which has a direct impact on the emissivity of the surface and was reduced from 0.93 to 0.29. Thermal analyses demonstrated that after applying the reflective coating, thermal resistance increased significantly in the air gap, by approximately 86%, which resulted in a 28% improvement of the evaluated walls samples. The studies have shown that increasing the gap thickness between concrete and thermal insulation results in a thermal resistance increase. It is feasible to enhance the thermal insulation of walls while simultaneously reducing their thickness, a development that holds significant potential for application in the production of prefabricated sandwich panels. The statistical analyzes performed showed significant differences between the analyzed configurations. Full article

Si/SiO₂ interfaces, an important functional part of silicon-based devices, are the structures most likely to cause failure. Under external load in the service state, Si/SiO₂ interfaces can degrade in different forms, and they can change from an ideal symmetrical structure to an asymmetric structure with defects. To systematically analyze the Si/SiO₂ interface, the research methods of microstructure, including characterization and modeling, are first introduced. Then, the effects of irradiation, high field stress, mechanical stress, and high temperature on Si/SiO₂ interfaces are studied. Chemical bonds, conductive band structure, and interface roughness can be changed under high field and mechanical stress loads. In addition, defect initiation and impurity migration may occur due to irradiation and temperature loads, which can lead to the failure of devices. Under multiple types of loads, the degradation mechanisms are complex, and the interfaces become more sensitive, which makes investigations into interface degradation laws difficult. For improving the reliability of devices, a systematic analysis of the influence on Si/SiO₂ interfaces under complex loads is summarized. Full article

Focusing on advancements in additive manufacturing, this Special Issue explores the role of novel materials and surface technologies in improving functionality, performance, and sustainability. The research papers highlight innovative approaches to understanding and overcoming material limitations, particularly in the areas of surface engineering, process optimisation, and multi-material applications. Key topics include the tribological behaviour, wear resistance, and surface quality of coated components, the effects of process parameters on mechanical strength and surface roughness, and advanced methods for surface characterisation and quality control. By addressing challenges, such as material efficiency, friction reduction, and structural integrity, the researchers emphasise the crucial role of novel materials and technologies to push the boundaries of additive manufacturing. Looking to the future, integrated strategies that prioritise sustainability, material innovation, and application-driven optimisation will be crucial. Through collaboration and technological advancement, this Special Issue provides valuable insights that will contribute to a more efficient, sustainable, and versatile future of additive manufacturing. Full article

This study evaluated the color stability, surface roughness, and hardness of 3D-printed and heat-polymerized denture materials. A total of 90 samples were prepared, with equal numbers of 3D-printed and heat-polymerized disks. The initial hardness, surface roughness, and color values of the samples were measured. After 14 days of immersion in distilled water, natural orange juice, or commercial orange juice, the measurements were repeated. Based on the findings, 3D-printed samples exhibited a greater reduction in Vickers hardness (56.24 ± 15.81%) compared to heat-polymerized samples (18.93 ± 11.41%). Materials immersed in commercial orange juice exhibited a greater reduction in hardness compared to those in other solutions (43.13 ± 23.66). Surface roughness increased by 46.66 ± 26.8% in heat-polymerized samples and by 26.16 ± 20.78% in 3D-printed samples, with the highest increase observed in commercial orange juice (50.73 ± 28.8%) (p < 0.001). The color change (ΔE) was significantly higher in heat-polymerized samples (ΔE = 5.05 ± 0.28) than in 3D-printed samples (ΔE = 3.9 ± 0.26) (p < 0.001). This study demonstrates that the material type and immersion solutions play a critical role in determining the mechanical and optical properties of denture materials, with commercial orange juice having the most pronounced effect on surface roughness and hardness. Full article

Wear resistance and optical properties are the key point for the application of titanium alloys as structural materials in the aerospace field. To enhance the wear resistance and optical properties of titanium alloys, a black plasma electrolytic oxidation (PEO) coating incorporating MoSi₂ nanoparticles was fabricated on the TC4 alloy via the PEO process, with the MoSi₂ nanoparticles being in situ doped into the coating. The doping of MoSi₂ nano-particles can effectively reduce the pore size of the PEO layer. The nPEO coating exhibited lower surface roughness than that of the PEO layer. The surface hardness of the nPEO coating increased to 42.5 HRC, significantly enhancing the wear resistance of the PEO layer (40.7 HRC). Furthermore, the PEO coatings exhibited better optical property compared to TC alloy, and the incorporation of MoSi₂ particles further improved the performance in most wavelength ranges. The infrared emissivity of the nPEO coating was 0.87, a dramatic increase from the 0.38 value of the TC4 alloy. This coating strategy effectively enhances the wear resistance and optical performance of TC4 alloy, which is critical for the surface design of titanium alloys used in aerospace applications. Full article

Background: 3D-printed (3DP) resins for permanent restorations are increasing in availability and gaining popularity. Aesthetic stability is an issue of dental resins that may compromise the long-term success of restorations. A staining test has been performed to evaluate gloss, roughness, and color staining of a permanent 3DP resin, and the effects of repolishing. Methods: Squared specimens of one 3DP permanent resin (Crown permanent, Formlabs) have been CAD-designed and 3D-printed. After the roughness, gloss, and color measurements, they were immersed in a coffee staining bath at 44 °C for 24 h and then measured again. Subsequently, they were repolished with three different systems: prophy cup and Nupro prophy paste, HiLuster Plus 2-step, and Opti1Step Polisher 1-step polishing systems. Results: Gloss and Roughness were not significantly affected by the staining procedure. No significant changes were observed for gloss after repolishing, while one of the tested systems (prophy cup and paste) produced a worsening effect on roughness. Color was affected by the staining procedure. After repolishing, b* changes were almost completely recovered, while L* changes were recovered only partially. Conclusions: Color stability still represents a challenge, and 3DP resins for permanent use are affected. Repolishing systems should be further developed and tested. Full article

In this research, we mainly increase the adhesion of PMMA substrate and film, which is reflected in the environmental test. This study used plasma-enhanced atomic layer deposition (PEALD) to find the relationship between the intensity of XRD reflection peak and the root-mean-square surface roughness (σ_RMS) of hafnium dioxide (HfO₂) at different thicknesses by reducing the plasma power at different process temperatures. In this experiment, HfO₂ was found to have the highest intensity of XRD at its maximum thickness. According to the different intensities of XRD of HfO₂ at different thicknesses, aluminum oxide (Al₂O₃) was inserted as crystallization cutoff layers, and the two materials were combined into nanolaminates. The corresponding σ_RMS value also changed from 1.25 to 0.434 nm after treatment under the fourth experimental design. This study improved this mismatch between interfaces by adjusting the yield strength and ductility using Al₂O₃ layers and by creating an inhibition layer. In addition, through the processing of inserted Al₂O₃ layers, the degree of crystallization was changed so that the material and substrate could maintain their normal surfaces without cracking after the environmental tests. After inserting five 1 nm thick Al₂O₃ layers, the environmental test results were improved. The test time was increased from the original 56 h to 352 h. Full article

The study evaluates models produced using fused deposition modeling (FDM) technology in five orientations, fabricated from polycarbonate (PC) material with a FORTUS 360mc printer. The models included simple shapes (planes and cylinders) and complex free-form surfaces. Accuracy was assessed using a GOM Scan 1 scanner and GOM Inspect 2019 software, focusing on 3D deviations and dimensional and geometric deviations (form, position, and orientation, which have not yet been analyzed in similar studies and may limit the usage of the printed elements). Surface roughness was analyzed using a MarSurf XR profilometer, measuring Ra and Rz parameters. All models were characterized by a predominance of negative 3D deviations. The analysis of variance showed no effect of model orientation on the values of linear dimensional deviations and geometric deviations. The largest deviations were negative and associated with the size of the models. The average value of the absolute deviation of linear dimensions associated with the size of the model was 0.30 mm. The average value of the absolute deviation of other linear dimensions was 0.07 mm. The average value of orientation and position deviations for each model varied in the range of 0.15–0.20 mm, and for form deviation 0.16–0.20 mm. One of the models had a higher surface roughness (Ra = 17.2 µm, Rz = 71.3 µm) than the other four models (Ra in the range of 12.7–13.8 µm, Rz in the range of 57.2–61.2 µm). During the research, three distinct surface types were identified on the models. The research indicated the validity of taking surface type into account when analyzing its microgeometry. Full article