In this work, single-crystalline copper telluride Cu_2-xTe (0 ≤ x ≤ 1) nanowires were synthesized on a copper substrate using a one-step, catalyst-free chemical vapor deposition method without a reducing agent. The produced nanowires had a uniform diameter of 226.2 ± 12.0 nm with a mean length of 13.89 ± 1.02 µm. X-ray diffraction pattern analysis using the Rietveld refinement revealed a composite phase composition comprising three distinct phases of mass fraction as follows: hexagonal Cu₂Te (81.50 ± 6.47%), orthorhombic CuTe (17.31 ± 7.59%), and cubic Cu₂O (1.18 ± 1.72%). X-ray photoelectron spectroscopy found evidence of the presence of both Cu²⁺ and Cu⁺ oxidation states of Cu. Moreover, the influence of Cu substrate thickness was investigated under the same experimental conditions. The thickness of the Cu substrate significantly impacted the copper telluride nanostructures’ morphology. When the Cu substrate thickness increased by ten, structures such as 1D nanowires, 2D hexagon sheets, and 3D dendrites became evident. UV–visible absorption studies showed that as Cu thickness increased from 0.15 mm to 1.5 mm, the absorption peak shifted from 533 nm to 614.70 nm. The detailed growth mechanisms of the 1D nanowires, 2D sheets, and 3D dendrites were discussed. Finally, the electrochemical performance of the produced nanostructured electrodes was evaluated using a three-electrode configuration, demonstrating superior electrochemical performance as a viable electrode material for electrochemical supercapacitors.

Fly ash (FA), a common type of industrial waste, has garnered significant interest due to its high value-added potential. These micron-sized materials serve as inorganic fillers to enhance mechanical and shielding performance and have diverse applications in the coatings industry. However, research has shown that FA possesses high porosity and low interface-binding ability, which diminishes its barrier efficacy and can lead to the corrosion of the underlying metal. To mitigate this issue, a popular approach involves combining FA with nanomaterials or modifying the surface of the fillers. In this study, we utilized FA in conjunction with metal oxide nanoparticles (MNs) and performed surface modifications on the FA fillers with silica (sFA) and polyaniline (pFA), and on MNs with stearic acid (sMN). We then evaluated their impact on corrosion resistance, barrier, and mechanical performance. The findings revealed that coatings using unmodified FA and MNs showed minimal improvement in barrier performance during long-term exposure to a corrosive environment (3.5 wt% NaCl). In contrast, the surface modification of the fillers resulted in excellent anti-corrosion performance, demonstrating a five-order increase (10¹⁰ Ω.cm²) in coating resistance and ~69% less water uptake compared to the unmodified system. Accelerated corrosion tests indicated that coatings with surface-modified fillers could achieve up to 95% protection efficiency. The developed coatings exhibited robust properties, showing an increase in impact strength of about ~118% and an adhesion strength of about ~112% compared to blank coating, surpassing the performance reported in several other studies. The use of mixed fillers and their homogeneous dispersion in the coating matrix as a result of surface modification increased the diffusion path length for corrosive media by creating numerous tortuous paths, leading to enhanced corrosion resistance, barrier performance, and mechanical properties. This research underscores the utilization of high-value FA as a solution for solid waste management.

High-quality and large-size single crystals of lead-free Na_0.5Bi_0.5TiO₃ were grown using the Czochralski technique. The crystals had a pure perovskite structure with rhombohedral symmetry (R3c) and were translucent in the visible and near-infrared spectral ranges recorded in the interval 350-1050 nm. The energy gaps determined from the X-ray photoelectron spectroscopy (XPS) and optical measurements were approximately 2.92 eV. The density of the electronic states and energy band structures were investigated using an ab initio method. The energy gap calculated for NBT (R3c) was 2.8 eV, which is comparable to those determined from XPS and optical measurements. As calculations have shown, when the potentials intended for perovskites are applied to Na and Ti atoms, the energy gap value increases by 68% from 1.9 eV to 2.8 eV. The frequency/temperature dependent electrical properties were also measured and analyzed through complex impedance spectroscopy. An overlapping reversible insulator–metal transition (resistive switching) on nanoscales, caused by the electric field, was detected. This was the first time that most of these investigations were performed for this material. The activation energy values determined from the conductivity data, the imaginary part of the electric impedance and the modulus indicate that the relaxation process in the high-temperature range is attributable to both single and double ionized oxygen vacancies, in combination with the hopping of electrons between Ti⁴⁺ and Ti³⁺. P-type electrical conductivity was also found. These discoveries create new possibilities of reducing the electrical conductivity of NBT and improving the process of effectively poling this material.

Tooth-whitening treatments in contemporary dentistry are often challenged by enamel demineralization and sensitivity. This study explores the potential of using Rochelle salt (potassium sodium tartrate), a piezoelectric material, as a non-invasive alternative to traditional peroxide-based whitening methods. While peroxide-based treatments eliminate extrinsic stains through chemical oxidation, Rochelle salt leverages its piezoelectric properties to produce controlled mechanical vibrations, thereby gently removing stains without damaging the enamel. This method is mechanically distinct from peroxide-based approaches.

In vitro experiments compared three toothpaste formulations: one without a whitening agent, one containing Rochelle salt, and one with peroxide carbamide as a control. Results demonstrated that the Rochelle-salt-enriched toothpaste was as effective as the peroxide carbamide-enriched formulation in removing stains. Specifically, the Rochelle salt formulation removed 30% of extrinsic stains after the equivalent of one week of brushing. Importantly, no enamel damage was observed following the long-term application of the Rochelle salt formulation. In contrast, the peroxide carbamide-enriched toothpaste reduced enamel microhardness by 16%, according to the Martindale test.

These findings indicate that Rochelle salt is a safe and effective alternative for eliminating tooth stains. However, further research is necessary in order to investigate the long-term effects of using this piezoelectric material in tooth-whitening treatments.

Tooth decay or erosive wear often results from the contact of acid with hydroxyapatite in tooth enamel. Traditional methods for restoring enamel involve fluoride-based products, but frequent fluoride intake can lead to fluorosis, deterring consumers. This study aimed to investigate the potential of chitosan hydrochloride (mushroom-sourced, vegan-friendly) and chitosan (chitin-sourced) in enhancing the acid resistance of bovine enamel blocks in vitro. Enamel blocks were sectioned from bovine teeth, and the percentage of relative erosion resistance (%RER) was measured. After demineralizing them in a solution at a pH of 4.5 for 60 minutes, the enamel samples were treated with the respective solutions for 16 hours at a pH of 6.5. Acid exposure involved immersing the samples in 8 ml of citric acid solution for 1 hour at 37°C. The results indicated that chitosan hydrochloride at concentrations of 0.25% (-41.9±11.8; p<0.05) and 0.5% (-30.67±16.34; p<0.05) provided protection against acid erosion comparable to the positive control, fluoride (-44.44±15.89; p<0.05), while the result for deionized water was -91.25±30.01; p<0.05. To understand the mechanism, the ability of the compounds to adhere to the enamel surface was examined using a light microscope. Representative images of the enamel samples were captured before and after a single 3-minute application of the test compound, followed by immersion in deionized water three times and reimaging. The images showed that 0.2% chitosan hydrochloride remained on the sample surfaces. In conclusion, chitosan hydrochloride demonstrates potential as a vegan alternative to fluoride for enhancing acid resistance by adhering to the tooth surface.

Soft tissues form the building blocks of the human body. They include the most widely distributed skin and muscle tissues, as well as the connective and supporting tissues found in the organs. Experimental work with soft tissues has numerous biosafety and ethical issues due to which several synthetic simulants have been developed. To date, human tissue simulants have been fabricated with materials such as gels and polymers like gelatin, polydimethylsiloxane (PDMS), and polyurethane, whose mechanical properties are widely different from those of natural tissues. In addition, pigskin and cowhides have been used extensively in experiments; they not only have different mechanical properties from most human tissues, but also carry ethical and biosafety concerns. Recently, a patented elastomeric biofidelic skin simulant and conductive soft tissue surrogates were developed, and they are the only products capable of high-fidelity tissue mimicking. They have been widely used for soft tissue mechanical characterization and computational studies. Based on this, a range of biofidelic artificial soft tissues were developed to mimic the skin, muscles, fat, brain (both grey and white matter), artery, and foot pad. This presentation will cover the development, characterization, and applications of such novel materials.

Heterojunction-based gas sensors have drawn significant interest due to their more sensitive nature as compared to tetrahedral metal oxide. However, developing homogenous and durable heterojunctions by conventional synthesis techniques is challenging. This work
intended to generate MnO 2-loaded Co 3 O 4 composites under specific conditions using the mechanochemical synthesis technique. The structural, morphological, optical, and gas-sensing properties of pure MnO 2, pure Co 3 O 4, and 0.5 wt. % MnO 2-loaded 0.5 wt.% Co 3 O 4 composite were investigated. X-ray diffraction (XRD) examination revealed that the self-synthesized samples were crystalline and had no secondary phases. Scanning electron microscopy (SEM) of selected samples revealed a high degree of agglomeration. Moreover, research on gas sensing has demonstrated that oxygen vacancies preferentially occur close to Co- ions, which reduces the Co-ion charge, and a neutral structure is formed as a result. Due to MnO 2's influence corroborating the local Co-to-Mn charge transfer mechanism, a response and recovery time of 79 and 273sec was observed at 25ppm acetone and at 200 o C. It was concluded from the data that constructing heterojunctions would be an effective approach to enhance the prepared gas sensor's sensitivity. Furthermore, the present research offers a simple, versatile, and adaptable method for synthesizing heterojunctions with excellent structural uniformity for use in a variety of industrial applications.

The introduction of the Haber—Bosch (HB) process in the early twentieth century enabled the large-scale production of NH₃, swiftly becoming one of the most crucial chemical products worldwide due to its extensive application in agriculture as a fertilizer. Moreover, NH₃ has recently garnered significant interest as a potential renewable energy storage system, given its capacity to serve as a source of hydrogen [1].
However, the Haber—Bosch process, reliant on atmospheric nitrogen and fossil fuel, requires H₂ for NH₃ production, as well as high process temperature and pressure, contributing to approximately 1.6% of the annual global CO₂ emissions [2]. A promising alternative lies in the electrochemical nitrogen reduction reaction (E-NRR) to synthesize NH₃ under ambient conditions. However, to date, this process has a limited yield production and a low selectivity due to the high stability of the N2 molecule and the presence of parasitic reactions, primarily leading to water (solvent) conversion into hydrogen [4].
A more recent focus has emerged towards the reduction of NO₃^‒, as it can be more easily converted into NH₃ with a significant Faradaic efficiency (FE) and high yield. Moreover, owing to the prevalent use of nitrogen-based fertilizers, this process possesses a significant real-case application towards wastewater treatment, where high NO₃^‒ levels have often been detected [3].
This study presents the utilization of a nanostructured NiO electrocatalyst, prepared by precipitation in an aqueous medium and calcinated at 600 °C, for the reduction of NO₃^‒ into NH₃, achieving an average FE of 36% and a production rate ranging from 28 to 107 μg h cm^‒2, depending on the initial NO₃^‒ concentration. The experiments were conducted in an H-type cell, utilizing three different concentrations of KNO₃ (NO₃^‒ source), i.e. 0.1, 0.05, and 0.008 M. A second investigated experimental parameter was the concentrations of the supporting electrolyte (i.e., K₂SO₄), which was used at 0.4, 0.45, and 0.492 M. The tests were conducted under an applied potential (E) of ‒1.4 V vs. Ag/AgCl for a duration of 2 h.
In this contribution, we will show the main outcomes derived from this newly explored electrocatalyst, highlighting the main structure--performance correlations.

References:
[1] H. Shen, C. Choi, J. Masa, X. Li, J. Qiu, Y. Jung and Z. Sun, Chem, 2021, 7, 1708–1754.
[2] P. Zhang, W. Xiong and M. Zhou, Nano Materials Science, 2020, 2, 353–359.
[3] Q. Liu, Q. Liu, L. Xie, Y. Ji, T. Li, B. Zhang, N. Li, B. Tang, Y. Liu, S. Gao, Y. Luo, L. Yu, Q. Kong and X. Sun, ACS Appl Mater Interfaces, 2022, 14, 17312–17318.
[4] B. Yang, W. Ding, H. Zhang and S. Zhang, Energy Environ Sci, 2021, 14, 672–687.

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948769, project title: SuN2rise).

The increasing demand for eco-friendly and sustainable materials in the industrial sector has driven a shift from synthetic fossil-based materials to natural fibers and motivated the use of recycled polymer textiles. This research presents an innovative method for repurposing end-of-life textiles, such as polyester and polyamide fabrics, in the production of composite materials. The goal is to reduce textile waste and improve material longevity. The mechanical properties of composite laminates made from flax fabric (FF), flax/recycled polyamide fabric (F/RPA), and flax/recycled polyester fabric (F/RPES) were evaluated using tensile, flexural, interlaminar shear, and Charpy impact tests. Results indicate that incorporating end-of-life synthetic fibers enhances tensile strength, while flax contributes significantly to stiffness, moderated by synthetic fibers. This effect is observed in both tensile and flexural tests, with a more pronounced impact on bending stiffness. The inclusion of polyester fibers notably improved the composites, with an 11.1% increase in interlaminar shear maximum force, a 17.4% increase in interlaminar shear strength, and a 67.1% increase in un-notched impact energy compared to composites made solely with flax fiber (FF). Microscopic examination revealed a robust internal structure with a strong bond between polyester, polyamide, and flax fibers. Furthermore, the life cycle assessment showed that the F/RPES composite has a lower environmental impact than FF and F/RPA across all 18 categories analyzed, indicating a smaller environmental footprint for producing F/RPES compared to both FF and F/RPA.

With rapid advancements in materials science, new materials are emerging constantly. It is important to characterize the mechanical properties of new materials to guide their application and design. In this study, a parameter calibration method assisted by machine learning is proposed to quickly and accurately obtain the parameters of constitutive models of materials. A physics-informed neural network (PINN) with an embedded constitutive model is constructed. The PINN outputs elastic strain, plastic strain, and stress. The loss function incorporates both elastic and plastic constitutive models, with the constitutive parameters set as trainable variables. This approach allows the network to automatically adjust these parameters during training. The finite element method is applied to simulate published quasi-static and dynamic compression experiments on materials to enrich a dataset of response curves and constitutive parameters. The dataset, composed of 1600 numerical examples and nearly 100 published experimental results, is used to test the method. By fine-tuning the network structure, the data-driven neural network solution was able to achieve an accuracy of 93% on the test set. Compared to the traditional data processing methods, the time spent using this method for parameter identification is reduced to one percent of the conventional duration, significantly improving the working efficiency. A calibration method assisted by machine learning shows great potential in quickly obtaining a mechanical constitutive model of materials, avoiding the waste of human resources and preventing human-induced errors.