Wood is a natural material with structural and aesthetic roles in indoor and outdoor constructions. Wood treatments are performed to improve the material's natural drawbacks, such as biodeterioration, water absorption, microbial colonization, and flame sensitivity.

Conventional wood treatments, especially when wood is used outdoors, must normally be repeated regularly, because the compounds that are used are leached away, since a stable link between the wood and chemicals added is lacking. This leaching may also produce environmental pollution.

To improve the stability of wood treatments by promoting a stable coating, a new biotech method is proposed: the use of laccase to stably graft chemical compounds onto a wood surface. Laccase is an enzyme that can oxidize phenolic compounds to produce chemical radicals that may then link to a polymer chain, such as wood components, by means of covalent bonding. If the phenolic compounds also contain another functionality, it could be conferred to the wood after the grafting. This principle has been used to link several phenolic compounds to wood samples and, therefore, to modify their chemical composition and properties.

Using this biotechnological tool, a range of wood treatments were tested and analysed: the modification of the surface composition of wood, the hydrophobization of wood surfaces, the grafting of flame retardants, the design of new wood durability treatments, etc.

This new method opens up new possibilities in wood treatments by means of a mild and sustainable process.

Road markings (RMs) are infrastructure elements positioned to guide road users, regulate traffic, and enhance road safety. Significant advances in materials technology, such as the use of several types of paints and retroreflective materials, have contributed to improving the durability and day and night visibility of RMs. However, challenges in this field still remain, and recent developments have focused on using smart materials to incorporate innovative functionalities into RMs. Notable examples include semiconductors, which can photo-oxidize surface pollutants and provide self-cleaning properties, and thermochromic materials, capable of changing color at specific transition temperatures (TTs), offering visual feedback on pavement surface conditions. In this context, the objective of this study was to develop RM paints with self-cleaning properties (to enhance visibility and durability) and thermochromic properties (to indicate the potential presence of ice or snow on asphalt pavements). For the self-cleaning RM paint, different amounts of TiO₂ were incorporated into a water-based acrylic RM paint. The self-cleaning ability was assessed using CIELAB colorimetry to monitor the degradation of a model pollutant under UV light irradiation. For the thermochromic RM paint, thermocapsules with a TT equal to the freezing point of water (0 °C) were incorporated into a water-based acrylic RM paint. The thermochromic behavior was analyzed by the CIELAB system while the paints were exposed to negative and positive temperatures. The results showed that the self-cleaning RM paint achieved pollutant degradation capacity up to 3.2 times higher than the reference paint. The thermochromic RM paint demonstrated the ability to change to a pinkish color at temperatures below 0 °C, reversibly returning to the original white color at positive temperatures. Both properties showed potential to enhance road safety by improving visibility and providing visual feedback on usage conditions.

The investigation and construction of complex hierarchical structures from advanced composite materials through various additive manufacturing processes is developing rapidly worldwide and plays a particularly crucial role in the manufacturing and industrial sector. One of the most popular 3D printing techniques is Fused Filament Fabrication (FFF), which utilizes thermoplastic filaments as printing material. The mediocre mechanical performance of thermoplastic polymers has resulted in the rapid research and progress of advanced nanocomposite materials with the aim of improving the mechanical properties of complex structures. The objective of the current study is firstly to design and manufacture FFF 3D-printed hierarchical honeycomb and spiderweb constructs, using two advanced composite materials, polylactic acid reinforced with nanodiamonds (PLA/uD) and acrylonitrile butadiene styrene with carbon fibers as reinforcement (ABS/CF). At the second stage, there was an examination of the mechanical performance of these involute structures under experimental and theoretical tests. In particular, the compression behavior of the fabricated hierarchical honeycombs and spiderwebs was assessed by experiments along with finite element analysis (FEA) simulations. According to the results, the hierarchical cellular structures exhibited enhanced mechanical properties in comparison with the spiderweb structures. Specifically, augmented stiffness and compressive strength were observed. In addition, the increase of hierarchy in the honeycomb structures resulted in an improvement in the mechanical behavior in contrast to the spiderweb constructs. Finally, the convergence between the experimental and theoretical results was quite good for both hierarchical structures and materials.

Energy-dispersive X-ray (EDX) analysis is an elemental analysis technique associated with Field Scanning Electron Microscopy (FESEM); it is frequently used in material science and engineering. EDX analysis enables both qualitative and quantitative studies to be carried out for a variety of applications. In this study, aluminum and fluorine (Al, F) co-doped zinc oxide nanoparticles were grown using the sol–gel route via the spin-coating method with various (Al, F) contents (1 at.%, 1 at.%), (3 at.%, 3 at.%), (5 at.%, 5 at.%), and (7 at.%, 7 at.%). The as-grown samples were characterized by energy-dispersive X-ray (EDX) and Scanning Electron Microscopy (FESEM) techniques. The results revealed that the nanoparticles have uniform morphology and hexagonal structure with a homogenous distribution. We can observe the incorporation of Al and F into the zinc oxide lattice when (Al, F) content is (1 at.%, 1 at.%) and (3at.%, 3 at.%) while the presence of Al and F peaks in the spectrum of EDX results was demonstrated in the two dopants with (Al, F) content (5 at.%, 5 at.%) and (7 at.%, 7 at.%), indicating the film's microstructure quality degradation. Grain sizes ranged from 10 to 13 nm. In conclusion, simultaneous co-doping improved the microstructure of FAZO nanoparticles when the (Al, F) content was (1 at.%, 1 at.%) and (3 at.%, 3 at.%); thus, EDX can be considered as a useful technique in all research works that require element determination.

This study investigates the electrical properties of polypropylene (PP) composites produced via melt-processing, incorporating varying concentrations of as-grown carbon nanofibers (CNFs). The electrical conductivity of PP/CNF composites exhibits a notable increase with the addition of CNFs, reaching approximately ~ 6×10^-6 S m^-1 for composites containing 3 wt.% CNFs [1]. In addition to electrical conductivity, the dielectric properties of PP/CNF composites were systematically analyzed. The results indicate a gradual increase in dielectric permittivity with CNF loading, reaching a maximum value of ~ 13 for composites with 3 wt.% CNFs at 1 MHz. This enhancement is primarily attributed to the development of interfacial polarization, also known as the Maxwell–Wagner–Sillars effect, which arises from the presence of conductive nanofibers within the insulating polymer matrix, significantly influencing charge distribution and dielectric behavior. Furthermore, the Cole–Cole model, applied through the electrical modulus formalism, is used to examine the influence of CNF content on the dielectric relaxation behavior and frequency-dependent response of the composites. The analysis reveals that incorporating CNFs increases the material's heterogeneity and relaxation dynamics while also prolonging relaxation times and modifying charge-transport mechanisms [2]. This work aims to enhance the fundamental understanding of the electrical behavior of polymer composites filled with as-grown CNFs synthesized via chemical vapor deposition (CVD) without thermal post-processing.

Titanium alloys like TiAlV are biocompatible materials widely used in dental implants [1]. Hydrophilic surfaces enhance adhesion between the implant screw and tissue, promoting osseointegration and improving success rates through optimized chemical properties [2].

A novel multilayer coating approach is developed to avoid early implant failure by optimizing surface properties. This research focuses on creating innovative TiO_xC_y organometallic multilayer coatings on Ti₉₀Al₆V₄ substrates to improve osseointegration. These coatings are prepared using Plasma-Enhanced Chemical Vapor Deposition (PECVD), varying deposition parameters such as reactive gas flow, power, and time to modify the chemical composition, hydrophilicity, and layer thickness.

Comprehensive characterization of the surface is conducted using X-Ray Photoelectron Spectroscopy (XPS) to determine the chemical environment, and using the contact angle to evaluate wettability. To further understand the chemical composition within each layer, XPS depth profiling analyses are performed.

The preliminary results revealed that a multilayer designed with a decreasing reactive gas flow exhibits a gradient in its composition. Near the substrate, the layers display a mineral-like, low-carbon structure, transitioning to an organic-like, high-carbon composition (with a carbon percentage 3 times higher) at the outermost surface. This outer layer, engineered to interact with organic tissue, has a higher hydrophilic surface, resulting in superior osseointegration.

This innovative multilayer design not only represents a significant advancement in dental implant technology but also sets a precedent for the development of functional coatings for biomedical applications.

References

[1] Marin, E., & Lanzutti, A. (2023). Biomedical applications of titanium alloys: a comprehensive review. Materials, 17(1), 114.

[2] Gittens, R. A., Scheideler, L., Rupp, F., Hyzy, S. L., Geis-Gerstorfer, J., Schwartz, Z., & Boyan, B. D. (2014). A review on the wettability of dental implant surfaces II: Biological and clinical aspects. Acta biomaterialia, 10(7), 2907-2918.

Nanocrystalline diamond-like carbon (nc-DLC) films were synthesized using CH₄ and H₂ precursor gases in a capacitively coupled plasma chemical vapor deposition (CCP-CVD) system at 450 °C and 250 W RF power. Plasma pressure optimization (1–7 Torr) identified 4 Torr as optimal, yielding films with intensity ratios, with a ratio of disordered to graphitic structures (I_D/I_G) of 0.63, diamond-like to graphitic structures (I_Dia/I_G) of 0.69, diamond to the disordered structures (I_Dia/I_D) of 1.09, and a high sp³ content of 66.75%. These films were coated on vertically oriented Si nanowire (SiNW) arrays, previously optimized via a metal-assisted chemical etching (MACE) process, to investigate the impact of coating time (T_DLC = 10–60 min) on field emission (FE) performance. At T_DLC = 40 min, Raman and XPS analyses revealed an I_D/I_G ratio of ~0.67 and an sp³ content of 68.73%, correlating with enhanced FE properties, including a reduced turn-on field (E_ON) of 4.60 V/µm, increased current density (J), and an elevated field enhancement factor (β) of 1676.01, compared to uncoated SiNWs (E_ON = 5.80 V/µm, β = 1107.93). Heating the hybrids to 150 °C further improved performance, reducing E_ON to 3.2 V/µm and increasing J to 4500.67 µA/cm². The DLC layer at T_DLC = 40 min, featuring ~5 nm diamond <111> nanocrystals and ~68% sp³ content, significantly lowered the potential barrier for electron emission, demonstrating SiNW/nc-DLC hybrid structures have a strong potential for applications in flat-panel displays and advanced electron emitters, such as electron microscopes.

Additive manufacturing (AM) is presented as a great alternative to produce new metal alloys. Mg alloy WE43 is one of most relevant alloys for bioimplants due to its good mechanical properties and biocompatibility. However, its low corrosion resistance requires the use of coatings that can improve the corrosion behaviour of these alloys. Plasma electrolytic oxidation (PEO) is based on the growth of an oxide layer by means of high voltages (300V ‒ 600V) that incorporates various species from the electrolyte that can enhance corrosion resistance. Nevertheless, PEO coatings usually require an additional procedure post treatment in order to seal their external porous layer. Hydroxyapatite (HAp) is usually employed to promote bone growth and biocompatibility; additionally, its porous microstructure allows for the adhesion of other sealings that might improve the corrosion resistance. Polycaprolactone (PCL) is one of most used polymers for biomedical applications, mainly because of its biocompatibility and limited production of acid by-products. This study focuses on the development of a multilayer PEO/HAp/PCL system to investigate its effect on the corrosion behaviour of an AM WE43 Mg alloy after a heat treatment of 400ºC over 24h. The substrate before and after the heat treatment is characterized using several techniques such as: optical and scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The coatings were also characterized by SEM, EDS, and XRD, their roughness was measured with an optical profilometer, and water contact-angle measurements were performed. For the corrosion evaluation, electrical impedance spectroscopy (EIS) measurements were performed up to 3 days on Hank’s solution at 37ºC. The results reveal the influence of the multilayer coating on the corrosion behaviour, providing a comparative analysis with the substrate.

The evolution of substrate surface temperature during coating deposition is a decisive property-determining factor in thermal spraying. Local heat development is influenced by various factors such as thermal conductivity and substrate thickness. High fluctuations in surface temperatures promote the formation of residual stresses in the coating layers during cooling. Therefore, the risk of oxidation, cracking, or delamination increases. Therefore, limiting the surface temperature appears beneficial for quality assurance. Infrared (IR) thermography offers the possibility to determine the surface temperature in the coating process without contact. Determining factors in temperature evolution during the thermal spray process were identified by using IR thermography. The interaction between the substrate and coating material was taken into account. Furthermore, application limits for IR thermography (Optris XI80) in comparison to thermocouple measurements for the temperature range of 0–250 °C were determined. For this purpose, the stainless steel AISI 316L was coated on aluminum and steel sheets by atmospheric plasma spraying (APS). The influence of substrate thickness was evaluated. A correlation between the temperature history during the coating process and the corrosion properties was established. Current density potential measurements using gel electrolytes were used for this purpose. Clear correlations between the development of the surface temperature and the resulting coating properties werederived.

Developments in processing technology and feedstocks are key drivers for new product innovations in the field of additive manufacturing. In the area of complex and filigree geometries, additive manufacturing technologies are often superior to conventional processes. Selective laser melting (SLM) as a powder bed process allows components of different scales to be manufactured by variation in the grain size range of the feedstocks. However, the surface quality achieved is a critical factor. The powders used as feedstock in the selective laser melting (SLM) process fundamentally limit the surface quality of these components. Particle contamination on the surfaces of the parts can remain rounded or agglomerated, contributing to a very rough surface at the microscale. Furthermore, the manufacturing advantages of a closed component design lead to limitations in the mechanical finishing process, especially regarding undercuts and cavities. In addition to corrosion protection requirements, demands for wear resistance become increasingly important. This study deals with the development of a process chain for the surface functionalization of selective-laser-melted 17-4 PH by plasma polishing and interstitial diffusion hardening. In this context, both the leveling of the surface topography and the development of graded coating properties are of particular interest. In addition, this technology can be used to protect thin films against locally acting forces by providing sufficient support for the substrate materials.