Synthetic products are becoming more popular in daily life as economic development levels rise. However, to create appropriate materials that may satisfy this need, researchers have been forced to concentrate on sustainable raw materials [1]. Therefore, this study focuses on the use of renewable raw materials to create novel CMs (composite membranes) with tailored properties for water purification [2-3]. Thereby, we propose a method for the modification of chitosan scaffolds by sol–gel, which can improve the stability of membranes. This method creates a one-phase solution when metal alkoxides and water react with an acid or base [4-5]. For the preparation of the CM coated with sol–gel, commercial chitosan (CC), TEOS (tetraethylortosilicate), and MPTMS (mercaptopropyl trimethoxysilane) were used. For chitosan dissolution, acetic acid was used. The chitosan membrane was coagulated in a sodium hydroxide solution and lyophilized, after which it was immersed into the mixture of silanes; the sol–gel reaction was performed in basic catalysis. A swelling study was performed at four values of pH (10 until 13) to determine if the chitosan membranes can withstand the basic conditions employed for the secondary step of coating by sol–gel. With the aim of highlighting the improvement inproperties for the CM, several characterization techniques were emplyed. FTIR spectra of the CMs confirmed the characteristic bands for chitosan and silane network, while TGA indicated that the CMs acquired higher thermal stability. SEM images confirmed that the chitosan membranes were coated with a thin sol–gel layer, and BET results highlighted the increase in the specific surface area and pore surface area after sol–gel coating of chitosan scaffolds; this indicates a potentially higher capacity for pollutant retention. New CMs based on chitosan coated with an organosilane layer, deposited by sol-gel, were developed. These materials show promising properties in terms of stability and capacity for pollutant adsorption, making them potential candidates for water purification.

A two-step hydrothermal process was employed to fabricate a highly efficient TiO2 film. In the first hydrothermal step, a bi-layer structure was synthesized, consisting of well-aligned one-dimensional (1D) rods and three-dimensional (3D) flower-like structures on an FTO substrate. Both morphologies exhibited a robust rutile phase, which is believed to provide direct conductive pathways and reduce electron-hole recombination. However, the compact nature of the bi-layer TiO2 structure limited dye absorption, resulting in suboptimal performance of Dye-Sensitized Solar Cells (DSSCs). To address this issue, an etching treatment using a highly acidic hydrochloric acid (HCl) medium was implemented as the second hydrothermal step. The samples’ morphology was carried out using field emission scanning electron microscopy (FE-SEM). A 4Point Probe (Signatone Pro4-440N) was connected to the source meter to ascertain the resistivity properties of the samples. The etching treatment effectively increased the surface area of the TiO2 bi-layer, facilitating improvements in DSSC performance. The etching process transformed the morphology into a needle-like structure as revealed by FESEM images, while the reduction in electrical resistivity indicated a significant enhancement in the material's properties. The etched sample demonstrated superior performance, achieving a power energy conversion (PEC) efficiency of 10.05%, compared to 6.41% for the non-etched sample.

In the study of hard protective coating materials, the pursuit of higher hardness often comes at the expense of reduced toughness, leading to brittle fracture failure. To address this challenge, we propose a nanoscale structural regulation strategy from the perspective of material microstructure design to resolve the trade-off between hardness and toughness. Specifically, we employed a layered deposition process to activate the "solid-state dewetting" method, successfully fabricating a 3D coherent TaC@Ta nano-core-shell micro/nano-structured coating. This structure effectively suppresses interfacial crack initiation from three dimensions and overcomes the limitations of thermal-driven phase separation methods on toughening metals, thereby avoiding hardness deterioration caused by toughening efforts. Next, we proposed an atomic-scale tailoring strategy using "high negative mixing enthalpy + high lattice distortion" to induce localized disordered clusters. This approach transforms the topologically ordered structure of transition-metal high-entropy alloys into a novel high-entropy paracrystalline structure, with sub-nanoscale sub-crystals as structural units. This innovation achieved a 100% increase in hardness and a 69.2% increase in compressive strength, along with a significant enhancement in ultimate plastic deformation capacity. Furthermore, we developed a vertically aligned "bamboo-like" nanocolumnar copper coating material reinforced by an amorphous boron framework through bottom-up growth using magnetron co-sputtering. This structure achieved an indentation hardness of 10.8 GPa while maintaining excellent strength (yield strength ~1.36 GPa, flow stress ~2.58 GPa) and ductility (failure strain exceeding 50%). This series of works demonstrates the simultaneous enhancement of hardness, strength, and toughness in coating materials through the design of 3D coherent, nanoscale sub-crystalline structures, and "bamboo-like" structures. These findings provide new insights and approaches for the microstructural design and fabrication of toughened structural coating materials.

The two most significant techniques for producing carbonaceous materials with exceptional conductivity for use in electrochemical devices are chemical vapor deposition and mechanical cleavage of graphite. The main advantage of using the CVD technique is represented by the ability to obtain materials that can be used on larger surfaces, with a uniformity superior to cleavage techniques. However, films of carbonaceous materials are hydrophobic, which makes it difficult to integrate nanoparticles. By adding nanoparticles (e.g., metallic, oxide), the electrochemical characteristics of carbonaceous materials can be improved, as a result of the increase in the specific surface of the electrode, catalytic effect, and enhanced electron transfer. In this paper, we present the methodology for modifying the wetting capacity of a graphene film grown on a copper substrate, which we transferred through a chemical process to the SiO₂/Si substrate. To modify the wetting capacity of these materials, both plasma treatment using reactive ion etching equipment and a chemical treatment in acid medium were carried out. For fundamental investigations of the graphene–liquid interface, it is necessary to ensure that the graphene surface is free of any kind of residue. This is important not only to ensure the persistence of favorable properties, but also to ensure an ideal sp² carbon surface to allow suitable chemical interactions with NPs, precursors, and analytical molecules. The research has focused on the use of spectroscopy, SEM, and goniometry as techniques for structural, morphological, wetting capacity, and percolation analyses of carbonaceous materials. Their applicability in the electrochemical field was studied by cyclic voltammetry after the incorporation of nanoparticles.

Acknowledgements: This work was supported by a grant from the Ministry of Research, Innovation and Digitization, CNCS-UEFISCDI, project number PN-IV-P2-2.1-TE-2023-0417, within PNCDI IV, and by the Core Program within the National Research Development and Innovation Plan 2022-2027, project no. 2307.

Nickel-based alloys, including Inconel 718 and alloy 625, are indispensable in industries such as aerospace, marine, and nuclear energy due to their exceptional mechanical strength, high-temperature performance, and corrosion resistance. Despite their advantages, these alloys present significant challenges during machining owing to their hardness, and low thermal conductivity. To address these issues, advancements in tool coatings and materials have become critical, driving innovation in machining technologies. Coatings such as Titanium Aluminum Nitride (TiAlN) and Titanium Silicon Nitride (TiSiN) are recognized for their high thermal stability, hardness, and oxidation resistance, making them ideal for high-speed and elevated-temperature machining. Nano-Composite Coating (nACo) provides enhanced wear resistance, while Titanium Nitride (TiN) and Titanium Carbonitride (TiCN) offer anti-friction properties and toughness, respectively. Aluminum Oxide (Al₂O₃) delivers superior thermal stability and resistance to abrasive wear. Advanced solutions include multilayer coatings like TiAlN/TiN, which combine thermal resistance and toughness, and doped Ti₃AlN coatings enhanced with chromium or vanadium to improve hardness and machining efficiency. Tool materials have also seen significant advancements. Cemented carbides remain widely used due to their balance of hardness and toughness, while ceramic tools offer exceptional thermal stability for high-speed operations. Polycrystalline Cubic Boron Nitride (PCBN) excels in machining hardened alloys, and Polycrystalline Diamond (PCD) extends tool life significantly, particularly in milling applications. Nanoscale structured tools, often combined with optimized coatings, provide enhanced cutting efficiency. Tool wear caused by the hardness and work-hardening nature of nickel-based alloys necessitates robust coatings like TiAlN and multilayer systems to maintain thermal and mechanical stability. The integration of innovative coatings and tool materials has significantly improved the machinability of nickel-based alloys. Technologies such as TiAlN, TiSiN, and advanced multilayer systems, coupled with cutting-edge materials like PCD, continue to enhance wear resistance, reduce cutting forces, and ensure superior surface integrity.

INTRODUCTION

Reducing agrifood waste has become an important goal, considering that up to 50% of total production is lost due to contamination by harmful microorganisms. In this context, controlling the interface between food products and the external environment can be a powerful tool to prevent waste. The aim of this study was to produce a bio-based and biodegradable food packaging material loaded with copper particles, which act as a reservoir of cupric ions.

METHODS

A green one-pot approach was used to synthesize copper particles using poly(N-vinylpyrrolidone) (PVP) as a capping agent (Cu@PVP), preventing aggregation through steric hindrance and eliminating the need for an inert atmosphere. The influence of PVP and reductant concentrations, as well as reaction time, on the oxidation state of copper phase, synthesis kinetics, and particle size was investigated by varying each of these parameters individually. Optimal conditions were identified to obtain an average particle diameter above 200 nm, while minimizing reagent and time consumption, to prevent nano-cytotoxicity effects. After a purification step, the Cu@PVP particles were suspended in ethanol and embedded in a chitosan (CS) polymeric matrix.

RESULTS

Composite films were obtained by solvent casting. The polymer solution concentration was adjusted to maintain good rheological properties even in the presence of inorganic particles. Torsional rheology and water uptake measurements were performed to assess the mechanical behavior of the self-standing films obtained after solvent evaporation. The antimicrobial capabilities were demonstrated by ionic Cu²⁺ release kinetics, and in vitro by growth inhibition of three different model fungi responsible for agrifood spoilage.

CONCLUSIONS

This innovative material could be used for the production of biodegradable bags and envelopes destined for the storage of fruits and vegetables, extending the shelf-life of these horticultural products.

Introduction: Optimizing the properties of amorphous optical coatings through thermal annealing is crucial particularly in the field of gravitational wave detection (GWD)^1,2. Traditionally, the effects of annealing protocols on interferometry mirror coatings have been studied post-process, leaving the real-time dynamics during annealing largely unexplored. This study introduces a novel technique for real-time monitoring of optical properties during annealing, applicable to all transparent thin-film materials. We applied this technique to Titania–Tantala, Hafnia–Tantala and Titania–Germania thin films to investigate the impact of annealing parameters on their optical properties.

Methods: We employed real-time, in situ spectroscopic ellipsometry (SE) to track changes in the refractive index and thickness of transparent thin-film coatings during a controlled annealing process. The standard annealing protocol for current GWD mirrors was utilized, involving a heating ramp from room temperature to 500°C, a 10-hour plateau at 500°C, followed by cooling. Continuous SE measurements were recorded throughout the cycle. Additionally, various annealing protocols were tested on multiple samples to fine-tune the annealing parameters.

Results: For Titania–Tantala coatings, significant changes in thickness and refractive index were observed during the heating ramp, beginning at approximately 200°C and accelerating between 250°C and 350°C. A smaller, steady evolution was noted during the 10-hour high-temperature plateau. Similar trends were observed for other materials, each exhibiting interesting characteristic behavior.

Conclusion: Our results suggest potential improvements to the current annealing protocols for Titania–Tantala and other candidate materials for GWD mirrors, such as Titania–Germania and Hafnia–Tantala. Traditional ex post analysis fails to capture these real-time dynamics, highlighting the necessity of our approach for systematic, real-time investigations. This method not only enhances our understanding of how annealing parameters influence optical coating but also facilitates the optimization of protocols for new GWD mirror materials.

Over the years, climate change has been intensifying global temperature fluctuations, bringing significant heatwaves to certain parts of the planet and vastly contributing to the Urban Heat Island (UHI) effect, while other parts of the world have experienced extreme cold spells. These global changes have impacted cities, leading to significant thermal discomfort and rising energy demands in heating and cooling. Developing sustainable solutions for these rising challenges has become crucial for enhancing urban living conditions and achieving good energy efficiency while keeping the population comfortable. One of the most promising solutions that has arisen in the last couple of years has been the incorporation of Phase-Change Materials (PCMs) into Civil Engineering materials. These materials can be encapsulated into Phase-Change Fibers (PCFs), which represent a novel technology in the literature. These PCFs utilize the latent heat principle, absorbing or releasing energy during phase transitions to maintain a stable temperature. In this context, this study produced PCFs via wet-spinning with commercial Cellulose Acetate (Mn 30,000) and polyethylene glycol (PEG 400 and 600). The fibers’ structures were optically evaluated using Bright-Field microscopy and Attenuated Total Reflectance–Fourier Transform Infrared Spectroscopy (ATR-FTIR). The first test confirmed the PCFs' coaxial morphology and the proper PEG encapsulation within the CA sheath. Through ATR-FTIR, it was possible to confirm the key functional groups of the virgin materials and their successful integration during the production of the fibers. Thermal testing was conducted through Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). PCFs incorporating PEG 400 and PEG 600 demonstrated phase-change temperatures of around -4 °C and 12 °C and an enthalpy of 26 J/g and 29J/g, respectively, showing great potential applications for different climates. The degradation temperatures were 234 °C and 300 °C, ensuring their resilience for integration into construction materials such as cementitious materials.

The aluminised coatings obtained on steels by the method of electrospark alloying (ESA) are investigated. Carbon steels were tested for the influence of the discharge energy and productivity (classic regimes, 2- and 4-fold reduction values) of the treatment process on the thickness of the hardened layer, its microhardness, continuity and surface roughness. Optical and scanning metallography, X-ray diffraction analysis, micro-X-ray diffraction analysis and micro hardness distribution tests were used for the study. Metallographic analysis showed that the structure of ESA coatings is layered, with a white layer not detectable in the reagent, diffusion zone or the substrate. The chemical and phase composition of the coating change when the discharge energy is increased during ESA. At low discharge energies, a layer consisting mainly of a-Fe and aluminium oxides is formed; as the discharge energy rises, the layer consists of iron and aluminium intermetallics and free aluminium. If the ESA productivity is reduced by factor 2, the thickness of the "white" layer increases to 75–110 µm, and its microhardness to 7450 MPa; the continuity of the coating approaches 100%. The deterioration of the coating quality parameters and the increase in roughness are due to a 4-fold decrease in process productivity. In order to improve hardening technology, it is important to study the influence of the energy parameters of ESA and the alloying time ('productivity') of the process. Aluminum-based coatings produced by the proposed ESA methods are recommended for use at high temperature.

Introduction:
The performance of optical coatings in cryogenic environments is critical for advanced applications such as high-precision optical systems; however, little data are available in the literature about their properties at low temperatures. At low temperatures, changes in refractive index and potential ice formation on coatings can significantly impact their optical properties, requiring a dedicated characterization. Silicon nitride coatings have been extensively studied in diverse fields, for applications both at room and low temperatures. In this work, the optical properties of non-stochiometric silicon nitride coatings at low temperatures are presented. SiN_x coatings are candidate materials for the mirrors of next-generation interferometric gravitational wave detectors such as the Einstein Telescope.

Methods:
A custom setup was employed for cryo-optic measurements to systematically study the optical properties of coatings at cryogenic temperatures. A cryostat with optical access, capable of reaching temperatures as low as 4 K, was designed to operate in ultra-high vacuum (10⁻⁸ mbar). In this study, we used real-time, in situ spectroscopic ellipsometry (iSE) coupled with the optical cryostat.

Results:

We acquired broadband SE spectra from room temperature down to liquid nitrogen temperatures. We modeled the ellipsometry spectra by means of a Cody–Lorentz dispersion function, obtaining the refractive index, extinction coefficient, and thickness of the samples as a function of the temperature.

Conclusion:
This study focuses on characterizing ion-beam-sputtered SiN_x optical coatings to investigate their behavior under cryogenic conditions. Characterization of the coatings at low temperatures assisted in the design of multilayer coatings operating at cryogenic temperatures. The accurate determination of the optical properties of the coatings was made possible by means of a proper modeling of few-nanometer cryodeposits (mainly water ice) that form on the cold surface of the coatings.

Acknowledgments:

We gratefully acknowledge the Project Einstein Telescope Infrastructure Consortium (ETIC)(IR0000004)-MUR call n. 3264 PNRR, Miss. 4-Comp. 2, Line 3.1.