Search Results (174)

Titanium dioxide (TiO₂) is a versatile material that exhibits a high refractive index, strong light-scattering capability, effective UV-absorption, wide band gap semiconductor behavior (3.0–3.2 eV), and excellent chemical stability. Owing to this unique combination of properties, TiO₂ is widely used in applications such as cosmetic and healthcare products, architectural and automotive coatings, and photocatalytic degradation of environmental pollutants. In photocatalytic applications, the crystal structure, phase composition and electronic properties of TiO₂ play a critical role in determining its performance. In the present study, TiO₂ nanotubes were synthesized by anodization of Ti° coatings deposited via a semi-industrial arc-PVD process. A post-anodization heat treatment was carried out at 430 °C for 1 h to promote the formation of the anatase phase within the TiO₂ nanotube structures. The structural characterization of the synthesized film was performed using X-ray diffraction (XRD) and Rietveld refinement. This methodology enabled the identification of the formed oxide phases, structure, and crystalline, confirming the formation of mixed oxides in the coating. To address the difficulty of refinement of these crystalline phases, the Le Bail method was applied. This refinement strategy allowed the identification of the crystalline phases that are present in the Ti_xO_y coating, including a hexagonal structure characteristic of α-Ti (space group P63/mmc, No. 194), the tetragonal anatase TiO₂ (space group I41/amd, No. 141) phase, and the trigonal Ti₂O₃ phase (space group R-3/c No. 167). Key crystallographic parameters such as lattice constants, bond lengths and angles, crystallite sizes, unit cell distortion and electron density were systematically evaluated for each phase. In addition, the Wyckoff positions and interatomic distances of the constitutive atoms were calculated, providing a comprehensive description of the TiO₂+Ti₂O₃/Ti° crystallographic system. The topographic and surface oxidation states were recorded by using profilometry and X-ray photoelectron spectroscopy, respectively. Full article

Titanium and its alloys are widely used in endoprostheses. The naturally formed titanium dioxide film on titanium surfaces improves chemical stability and enhances implant biocompatibility. However, oxidised titanium surfaces may also promote bacterial adhesion and biofilm formation, contributing to implant-associated infections. Therefore, surface modification represents a key strategy for controlling microbial–implant interactions. This article focuses widely used titanium alloy Ti-6Al-4V treated with a laser beam, which induces surface colour changes as a result of oxide formation. Laser processing enables controlled formation of micro- and nanoscale features, structural reconstructions, and defects that may influence the surface electrical charge and, consequently, cell immobilisation. Thus, the surface colour, electrical potential, and cell immobilisation capacity are likely interrelated. From a manufacturing perspective, titanium oxide colouring facilitates quality control and process reproducibility, as surface colour provides a rapid, non-destructive visual indicator of oxide thickness and treatment consistency. This study aims to identify correlations among surface colour, electrical potential, and cell immobilisation capacity on laser-treated titanium alloys. A relationship between the optical properties, electronic structure, and biological response of laser-processed titanium oxide films is established. Specifically, the blue colour saturation of the oxide film is inversely correlated with the electron work function. A more saturated blue corresponds to a lower work function, indicating a higher positive surface charge density. This shift is attributed to changes in electron affinity, likely resulting from laser-induced structural reconstruction and defect formation within the oxide layer. The proposed changes in electronic structure are supported by modifications in the electronic density of states, analysed using near-threshold photoelectron spectroscopy. The biological response is directly linked to these physical changes: enhanced immobilisation of yeast (Saccharomyces cerevisiae) cells on the treated alloy surface correlates with the electron work function. These results may assist in the development of controlled titanium oxide surfaces with enhanced biocompatibility. Full article

Background/Objective: Photocatalytic oxidation is often interpreted as evidence of microplastic degradation, yet whether surface chemical modification under dry conditions corresponds to meaningful bulk polymer breakdown remains unclear. To help fill that gap, this study investigates the concentration-dependent photocatalytic aging of polystyrene (PS) microplastics incorporated into Titanium dioxide-coated hollow glass microsphere (TiO₂–HGM) composites under solid-state UV irradiation, with emphasis on distinguishing surface oxidation from bulk degradation. Methods: Thin-film composites containing 1 wt%, 5 wt%, and 10 wt% TiO₂–HGMs were exposed to UV-A irradiation (365 nm) for 183.5 h under dry conditions. Chemical and structural changes were evaluated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and UV–visible spectroscopy. The carbonyl index (CI) was calculated from baseline-corrected integrated absorbance areas relative to an invariant aromatic reference band. Results: CI values increased from 0.483 (1 wt%) to 0.702 (5 wt%) and slightly decreased to 0.645 (10 wt%), indicating non-linear oxidation behavior and partial saturation. XPS showed a corresponding rise in the O/C ratio from 0.42 to 0.51. In contrast, UV–visible spectra exhibited minimal changes in aromatic absorption. Conclusions: Increasing photocatalyst concentration enhances surface oxidation but does not induce proportional bulk polymer degradation under solid-state conditions. Full article

Nickel–titanium (NiTi) shape memory alloys offer transformative functionality for biomedical and aerospace systems, yet their adoption in additive manufacturing (AM) remains constrained by powder reactivity, compositional sensitivity, and the high energy of feedstock production. This work establishes a unified, data-driven evaluation of how powder-state evolution during reuse and ultrasonic plasma atomization (UPA) affects both functional behavior and environmental performance. Virgin, reused, and UPA-recycled NiTi powders were systematically characterized based on particle-size distribution (PSD), SEM morphology, sphericity, oxygen content (ONH), and differential scanning calorimetry (DSC), and these results were coupled with a process-level life-cycle assessment (LCA) spanning cradle-to-gate feedstock generation. Reused powder showed finer but broadened PSD, surface oxidation, and elevated transformation temperatures; these degradation mechanisms limited its reuse despite reducing energy demand by ~30% relative to virgin powder. UPA provided a more effective regeneration pathway: UPA-recycled NiTi recovered high sphericity and smooth particle surfaces while lowering cradle-to-gate energy from 100 ± 10 to 50 ± 5 MJ·kg⁻¹ (≈50%) and reducing CO₂-equivalent emissions by ≈45%, with ~95% material recovery. Although the UPA condition exhibited a higher oxygen content in this study due to system-level atmosphere limitations, prior work indicates that optimized inert-gas control can suppress oxidation, suggesting clear avenues for improvement. Sustainability Index analysis confirmed UPA as the most favorable route, integrating reductions in energy demand and emissions with recovery of powder morphology and reconditioning of thermal transformation behavior. More broadly, the ability of UPA to promote compositional and microstructural redistribution highlights its potential to deliberately re-tune or “reprogram” transformation temperatures for application-specific requirements when alloying and processing atmospheres are carefully managed. Full article

Early oxidative stress caused by titanium implants can impair osseointegration. Manganese dioxide (MnO₂) nanozyme coatings have the potential to scavenge H₂O₂ and simultaneously generate O₂ to alleviate hypoxia, but their activity is mostly static, and the ion release is detrimental. A nano-MnO₂/Ti/P(VDF-TrFE) sandwich-structured composite was fabricated, and ferroelectric polarization was applied to preset a tunable surface potential. Kelvin probe force microscopy (KPFM) verified a presettable potential within ±500 mV. Steady-state kinetics confirmed an enhancement in overall catalytic efficiency (higher V_max and lower K_m). This translated to a faster initial decomposition rate at a low, physiologically relevant H₂O₂ concentration (300 μM). Correspondingly, under these oxidative stress conditions, cell survival in the polarized group was higher than that in the unpolarized group, indicating that the enhanced initial rate can have a positive effect in such conditions. Overall, this study demonstrates a proof-of-concept strategy to tune MnO₂ nanozyme catalysis using a polarization-preset surface potential, targeting implantation-relevant ROS-rich conditions. Full article

This study investigates the effects of Ti addition on the microstructures, melting temperature ranges, thermal expansion behavior, high-temperature creep and oxidation resistances of an equimolar CoNiFeCr alloy of a foundry origin. The addition of 1.5 wt.% Ti does not really change the single-phase state of the reference quaternary alloy but induces a significant decrease in the melting start and melting end temperatures. The thermal expansion coefficient is slightly lowered. The creep resistance at 1100 °C is significantly enhanced. The oxidation at 1200 °C is controlled by species diffusion through a continuous chromia layer. The parabolic constant is higher than for the quaternary alloy, due to external and internal Ti oxidation. The presence of a thin layer of titanium oxide covering the chromia scale is suspected to limit chromia volatilization and the scale spallation at cooling. Globally, Ti demonstrated the beneficial influence of the high-temperature properties of the alloy. Full article

The integration of polymer coatings with metal and metal oxide nanoparticles represents a significant advancement in nanotechnology, enhancing the stability, biocompatibility, and functional versatility of these materials. These enhanced properties make polymer-coated nanoparticles key components in a wide range of applications, including biomedicine, catalysis, environmental remediation, electronics, and energy storage. The unique combination of polymeric materials with metal and metal oxide cores results in hybrid structures with superior performance characteristics, making them highly desirable for various technological innovations. Polymer-coated metal and metal oxide nanoparticles can be synthesized through various methods, such as grafting to, grafting from, grafting through, in situ techniques, and layer-by-layer assembly, each offering distinct control over nanoparticle size, shape, and surface functionality. The distinctive contribution of this review lies in its systematic comparison of polymer-coating synthesis approaches for different metal and metal oxide nanoparticles, revealing how variations in polymer architecture and surface chemistry govern their stability, functionality, and application performance. The aim of this paper is to provide a comprehensive overview of the current state of research on polymer-coated nanoparticles, including metals such as gold, silver, copper, platinum, and palladium, as well as metal oxides like iron oxide, titanium dioxide, zinc oxide, and aluminum oxide. This review highlights their design strategies, synthesis methods, characterization approaches, and diverse emerging applications, including biomedicine (e.g., targeted drug delivery, gene delivery, bone tissue regeneration, imaging, antimicrobials, and therapeutic interventions), environmental remediation (e.g., antibacterials and sensors), catalysis, electronics, and energy conversion. Full article

Background and Objectives: Currently, the development of local drug delivery systems for the treatment of cancer patients is a pressing issue. Such systems allow for the targeted delivery of anticancer drugs directly to the tumor site, ensuring prolonged drug release or reducing the risk of recurrence after tumor removal, minimizing the impact on healthy tissues and thereby reducing the overall toxic load on the body. This work is devoted to evaluating the prospects of using scaffolds based on low-modulus titanium Ti-15Mo alloy with a biomimetic coating as a platform for the local administration of the cytostatic drug cisplatin into the patient’s body. Methods: Porous coatings were obtained by plasma electrolytic oxidation in an aqueous solution of sodium phosphate and calcium acetate with the addition of various components. The influence of coating parameters on the corrosion resistance of samples and on the antiproliferative effect of cisplatin-loaded scaffolds was evaluated. Human K562 hemoblastosis, HT116 intestinal cancer, and SKOV3 ovarian cancer cell lines were used as cell models. Results: It was shown that the addition of sodium phosphate (the PS type electrolyte) provides the formation of a coating with a developed system of interconnected pores characterized by an attractive combination of parameters: high porosity (17%), high pore size (3.9 μm), and considerable thickness (17.4 μm). This coating demonstrated the best corrosion resistance in a Ringer solution as compared to the other tested states. In addition, the PS coating loaded with cisplatin exhibited a pronounced cytotoxic effect on cancer cells. This effect was attributed to its ability to fix cisplatin on the surface, which slows down its release into the extracellular environment, increasing the time of its action, thereby contributing to a more effective (by more than 3 times) suppression of tumor cell proliferation compared to the action of the standard form of the drug in the form of a solution when changing the growth medium and subsequent incubation for 48 h. Conclusions: PS scaffolds made of low-modulus titanium alloy Ti-15Mo with a biomimetic surface in an electrolyte based on an aqueous solution of sodium phosphate and calcium acetate with the addition of sodium silicate can be used as an advanced platform for the local delivery of the cytostatic drug cisplatin, which makes them promising for application in orthopedic oncology. Full article

Transmetalation, the exchange of metal ions between coordination complexes and biomolecules, has emerged as a powerful design lever in cancer metallopharmacology. Using thiosemicarbazones (TSCs) as a unifying case study, we show how redox-inert carrier states such as zinc(II) or gallium(III) can convert in situ into redox-active copper(II) or iron(III/II) complexes within acidic, metal-rich lysosomes. This conditional activation localizes reactive oxygen species (ROS) generation and iron deprivation to tumor cells. We critically compare redox-active and redox-inert states, delineating how steric and electronic tuning, backbone rigidity, and sulfur-to-selenium substitution govern exchange hierarchies and kinetics. We further map downstream consequences for metal trafficking, lysosomal membrane permeabilization, apoptosis, and ferroptosis. Beyond TSCs, iron(III)-targeted transmetalation from titanium(IV)-chelator “chemical transferrin mimetics” illustrates a generalizable Trojan horse paradigm. We conclude with translational lessons, including mitigation of hemoprotein oxidation via steric shielding, stealth zinc(II) prodrugs, and dual-chelator architectures and outline biomarker, formulation, and imaging strategies that de-risk clinical development. Collectively, these insights establish transmetalation as a central therapeutic principle. We also highlight open challenges such as quantifying in-cell exchange kinetics, predicting speciation under non-equilibrium conditions, and rationally combining these agents with existing therapies. Full article

This study applies circular and sustainable principles to the formulation of biopolymer-based materials using naturally occurring additives. To improve the affinity between the host matrix and additives such as metal oxides, the work involves adding stearic acid-modified zinc oxide (f-ZnO) and sonicated titanium dioxide (s-TiO₂) to a polylactic acid and bio-derived polyamide 11 (PLA/PA11 = 70/30 w/w biopolymer blend via melt mixing. To evaluate the impact of the functionalization and sonication on metal oxides (i.e., f-ZnO and s-TiO₂) introduced into the PLA/PA11 blend, composites containing unmodified ZnO and TiO₂ prepared under the same processing conditions were compared with the modified ones. All of the composites were characterised in terms of their solid-state properties, morphology, melt behaviour, and photo-oxidation resistance. The addition of both f-ZnO and s-TiO₂ appears to exert a plasticising effect on the rheological behaviour, in contrast to unmodified ZnO and TiO₂. The presence of stearic acid tails on ZnO has been estimated at approximately 4%, whereas sonication reduces the diameter of TiO₂ particles by half. In the solid state, both unmodified and modified particles can reinforce the biopolymer matrix, enhancing the Young′s (elastic) modulus. Calorimetry analysis suggests that unmodified and modified metal oxide particles do not influence the glass transition of the PLA phase but affect the melt temperatures of both biopolymeric phases by reducing macromolecular mobility. Morphology analysis shows that the presence of both f-ZnO and s-TiO₂ particles does not reduce the size of the PA11 droplets. The f-ZnO particles, which have long stearic tails and are more compatible with the less-polar phase (PLA), are probably located at the interface between the two biopolymeric phases or in the PLA phase. Furthermore, s-TiO₂ particles, like TiO₂, do not reduce the dimensions of PA11 droplets, suggesting that there is no preferential location of the particles. Due to the presence of both f-ZnO and s-TiO₂, an increase in the hydrophobicity of the PLA/PA11 blend has been detected, suggesting enhanced water resistance. The photo-oxidation resistance of the PLA/PA11 blend is significantly reduced by the presence of unmodified metal oxides and even more so by the presence of modified metal oxides. This suggests that metal oxides could be considered photo-sensitive degradant agents for biopolymer blends. Full article

Cold-spray additive manufacturing (CSAM) is an emerging solid-state deposition technology that effectively mitigates common defects associated with conventional thermal processes, such as oxidation, phase transformation, and residual stresses. In this study, copper–titanium (Cu-Ti) composite coatings were fabricated via high-pressure CSAM using mixed powders with Ti contents of 3, 6, and 10 wt.%. The influence of Ti content and post-heat treatment (350–400 °C) on the tensile properties of the composites was systematically investigated. The results indicate that the ultimate tensile strength (UTS) remained consistently within the range of 265–285 MPa under all conditions, showing only a mild positive correlation with Ti content. In contrast, ductility was significantly influenced by Ti addition, with elongation decreasing markedly as the Ti content increased. Notably, the composite with 3 wt.% Ti heat-treated at 400 °C exhibited a well-balanced combination of tensile strength (270 MPa) and ductility (20% elongation). These findings demonstrate that CSAM-fabricated Cu-Ti composites possess attractive mechanical properties, which can be tailored through Ti content and heat treatment. Full article

This study investigated the variation in precipitation in Fe-25Cr-5Al-Ti-RE ferritic stainless steel under different quenching heat treatment temperatures. Quenching heat treatments were performed at five temperatures, namely 600 °C, 700 °C, 800 °C, 900 °C, and 1000 °C. To analyze the alloy’s microstructure and precipitation behavior, comprehensive characterization techniques were employed, including X-ray Diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results demonstrated that after quenching at these temperatures, the main precipitation in the alloy was a chromium-rich phase (α′), aluminum oxide (Al₂O₃), titanium carbide (TiC), and titanium nitride (TiN). Specifically, Al₂O₃ was detected exclusively after heat treatments at 800 °C, 900 °C, and 1000 °C, with its particle size ranging from 10 nm to 100 nm. During high-temperature heat treatment, aluminum atoms and oxygen atoms in the matrix interacted with each other, and fine Al₂O₃ particles precipitated through a solid-state phase transition. Regarding titanium-containing precipitates, TiC precipitated after heat treatments at 700 °C, 800 °C, and 900 °C, whereas TiN was only observed after the quenching treatment at 1000 °C. The size of TiC particles fell within the range of 100 nm to 400 nm, while TiN particles exhibited a significantly larger size, spanning from 5 μm to 10 μm. Thermodynamic and kinetic analyses revealed that at elevated temperatures, nitrogen (N) exhibited a relatively high diffusion coefficient in the matrix; meanwhile, titanium (Ti) demonstrated an extremely strong chemical affinity for N. Consequently, even when the N content in the alloy was at a low level, N tended to preferentially react with Ti rather than with carbon (C) to form TiN. Full article

In 3.5 wt% NaCl solution used to simulate seawater, the individual (self-corrosion) and coupled (galvanic) corrosion behaviors of TA22 titanium alloy and 304 stainless steel were systematically investigated at 25 °C, 35 °C, 45 °C and 55 °C. Post-corrosion surfaces were characterized by scanning electron microscopy (SEM), three-dimensional profilometry and X-ray photoelectron spectroscopy (XPS). The results demonstrated that elevating temperature decreased the compactness and protective quality of the passive film on both alloys, as indicated by increasing donor densities and positive shifts in flat-band potentials. Distinct pitting corrosion occurred on 304 SS above 45 °C. Upon galvanic coupling, the passive film on TA22 was modified in both structure and composition, exhibiting a decreased TiO₂ content and increased lower valence oxides (Ti₂O₃, TiO). The galvanic effect intensified with temperature, leading to progressively aggravated corrosion of 304 SS, characterized by increased pit density, diameter, and depth compared to its self-corrosion state. Full article

This study explores the differences in oxidation color, oxidation products, and high-temperature oxidation resistance between TA1 and Ti-6Al-4V (TC4) titanium alloys following a 50 h oxidation treatment at 450 °C and 750 °C. A combination of analytical techniques—optical microscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and micro-Vickers hardness testing—was employed to characterize the morphology of the oxide layers, elemental distribution, phase composition, and microhardness variations. The results reveal that at 450 °C, both alloys develop relatively compact oxide films. TA1 exhibits a yellow–gray coloration, while TC4 displays a characteristic blue–violet interwoven color. At 750 °C, however, the oxide layers become porous and prone to spallation, with a brown appearance and predominance of TiO₂. XPS analysis confirms that Ti⁴⁺ (TiO₂) is the dominant oxidation state on both alloy surfaces at 750 °C, with TC4 showing a significantly higher content of Al₂O₃. Microhardness measurements indicate that high-temperature oxidation increases the hardness of both alloys, with TC4 consistently exhibiting higher hardness than TA1. TC4 demonstrates superior oxidation resistance: at 450 °C, it forms a denser oxide layer with lower oxygen uptake, while at 750 °C, its oxide layer thickens more significantly, likely due to increased brittleness and spallation. This study underscores the profound impact of high-temperature oxidation on the microstructure and mechanical properties of titanium alloys and highlights the critical role of oxide layer density and stability in determining oxidation resistance. These findings provide valuable insights for the application of TA1 and Ti-6Al-4V alloys in high-temperature environments. Full article

Catalysis plays a pivotal role in green chemistry practices, particularly in reducing waste generated during chemical synthesis. Decatungstate (DT) emerges as a potent photocatalyst for Type I oxidations, exhibiting remarkable resilience to oxygen quenching, a characteristic that sets it apart from other excited triplet state photocatalysts. While homogeneous DT catalysis demonstrates effectiveness, its solubility poses challenges for its separation and recycling. To address these limitations, we focus on the development and comparison of heterogeneous DT photocatalysts, aiming to optimize their yield, recovery, and reusability. We synthesized tetrabutylammonium decatungstate (TBADT)-supported catalysts using silica, alumina, titanium dioxide, and glass wool and characterized them using diffuse reflectance measurements. Subsequently, we evaluated their photocatalytic performance by monitoring the oxidation of 1-phenylethanol and cyclohexanol under UVA irradiation. Our findings reveal that TBADT@silica emerges as the most effective catalyst, achieving approximately 20% conversion of cyclohexanol and 50% conversion of 1-phenylethanol with good reusability. Interestingly, we observed that 3-aminopropyl-triethoxysilane (APTES) treatment, intended to enhance DT anchoring, unexpectedly quenches the ³DT* triplet state, reducing catalytic activity. This unexpected finding underscores the importance of careful consideration in designing robust and recyclable heterogeneous decatungstate catalysts. Our research contributes significantly to the advancement of heterogeneous photocatalysis, paving the way for future applications in flow photochemistry. Further, we share a Python code (Google 3.12.11) to correct spectra obtained in Cary spectrometers. Full article