Search Results (5,887)

Numerous surface modification strategies, particularly nanoengineering approaches, have been explored to tailor the physicochemical and topographical properties of titanium surfaces in order to enhance osteogenic responses at the implant interface. In this study, we propose an alkaline ozonation strategy as a novel approach to generate nanostructured TiO₂ layers on Ti-6Al-4V alloy surfaces. Titanium discs were treated in a 6 M KOH solution under continuous bubbling of ozone, allowing the formation of reactive oxygen species (ROS) responsible for oxidative surface restructuring. Scanning electron microscopy (SEM) revealed the formation of a homogeneous three-dimensional TiO₂ nanonetwork composed of intertwined nanofibers. X-ray photoelectron spectroscopy (XPS) confirmed the oxidative reconstruction of the Ti alloy surface. The fraction of Ti⁴⁺ species characteristic of TiO₂ increased markedly from 44.2 at% to 92.2 at%, accompanied by a strong reduction in Ti⁰ (from 40.2 at% to 5.8 at%) and Ti³⁺ (from 15.7 at% to 2.1 at%). Concomitantly, lattice oxygen associated with Ti–O–Ti bonding increased from 48 at% to 78 at% as deduced from the O 1s signal, while the surface carbon content decreased from 48 at% to 18 at%. The modification induced a pronounced increase in surface hydrophilicity, with the water contact angle decreasing from 85° to 32° and the surface free energy increasing from 40.8 mJ/m² to 69.8 mJ/m². In vitro studies demonstrated good cytocompatibility and enhanced osteogenic differentiation of human mesenchymal stem cells, with twice as much alkaline phosphatase activity after 14 days and mineralization of the extracellular matrix after 28 days than those on TCPS, and also significantly higher than those on the nonmodified Ti alloy control. These findings indicate that the generated three-dimensional TiO₂ nanonetwork acts as a surface-confined nanoscaffold providing nanoscale cues that promote osteogenic cell responses on titanium implant surfaces. Full article

Lignin is one of the most abundant biopolymers in nature. The major challenge in lignin depolymerization lies in the formation of complex mixtures that require extensive downstream separation. Selective depolymerization strategies aim to overcome this limitation by promoting controlled bond cleavage while suppressing undesired secondary reactions. In this work, a series of rare-earth-free, perovskite-type mixed metal oxides with general compositions Zn_xNi_1–xTiO₃ and Cu_yNi_1–yTiO₃ were synthesized and evaluated as heterogeneous catalysts for the base-catalyzed depolymerization of lignin. Among the investigated materials, CuTiO₃ exhibited superior catalytic performance, enabling the formation of vanillin as the dominant monomer with high selectivity. The selected catalyst was further characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. The combined effects of key reaction parameters, including temperature, pressure, lignin-to-catalyst ratio, NaOH concentration, and reaction time, were systematically investigated using response surface methodology (RSM). Under the optimized conditions (154 °C, 0.3 MPa, lignin-to-catalyst ratio of 24.5:1, 10 mL of 0.5 M NaOH, and 12 h reaction time), a monomer yield of 11.5 ± 0.46% with ~81% GC-selectivity toward vanillin was achieved. These findings demonstrate that perovskite-type titanates can serve as robust and reusable catalysts. Full article

Heavy metal contamination in water remains a major environmental concern due to the persistence, toxicity, and bioaccumulation potential of metal ions such as Ni²⁺ and Cu²⁺. Therefore, the development of sustainable membrane materials with improved permeability and metal ion retention capacity is of significant interest for advanced water purification applications. In this research, crown ether-functionalized cellulose acetate membranes were developed by employing cyanuric chloride as a linker in order to enable advanced heavy metal ion retention capacity. In order to achieve this, the modification process involved a multi-step approach comprising successive hydroxylation, silanization, triazine activation, and crown ether grafting. The successful functionalization was confirmed by FTIR (Fourier Transform Infrared Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) analyses, while thermal characterization demonstrated improved stability over a wide range of temperatures without compromising the integrity of the cellulose acetate backbone. The crown-ether-functionalized membranes exhibited enhanced performance in terms of heavy metal ion separation, demonstrating significantly higher retention of Ni²⁺ (30%) and Cu²⁺ (27%) as compared to pristine CA membranes (<10%) over repeated filtration cycles. These results demonstrate that crown ether functionalization is a versatile approach for tuning the interfacial features of cellulose acetate membranes in order to achieve increased permeability and selectivity toward heavy metal removal, highlighting their potential for advanced water purification applications. Full article

The subject of this study is the electrochemical synthesis of samarium–cobalt (Sm-Co) alloy coatings on a copper substrate from aqueous solutions using chronoamperometric methods. The study focused on assessing the effect of ecological complexing agents—L-arginine and glycine—on the deposition kinetics and quality of the deposits obtained within a potential range of −1.1 V to −1.8 V vs. Ag/AgCl. Morphological analyses indicated that the type of amino acid used determines the layer growth mechanism. It was found that exceeding the potential of −1.4 V results in a rapid increase in samarium content in the alloy, reaching maximum values of 29 at.% for the system with L-arginine and 35 at.% for the system with glycine at a potential of −1.8 V. X-ray Diffraction (XRD) structural studies confirmed the successful synthesis of the Co_8.5Sm intermetallic phase directly by electrodeposition, while X-ray Photoelectron Spectroscopy (XPS) analyses indicated the presence of oxides and hydroxides on the deposit surface. Despite obtaining a high samarium content, it was observed that intense hydrogen co-evolution at low potential leads to a decrease in current efficiency and the formation of internal stresses and cracks in the structure of the coatings. Full article

A critical challenge in coalbed methane (CBM) extraction is the severe formation damage induced by conventional foam fracturing fluids, primarily through polymer retention and hydrogen bond disruption within the microporous matrix. This study presents a molecularly engineered, low-damage foam fracturing fluid that leverages synergistic nanoparticle–surfactant interactions to construct a robust interfacial pseudo-gel network, thereby decoupling effective fracture stimulation from adverse geochemical damage. The primary novelties of this work are threefold: (i) establishing a direct, quantitative cause-and-effect relationship between molecular interfacial architecture and reservoir protection, (ii) proposing a comprehensive “interfacial control” design paradigm that engineers viscoelasticity at the gas–liquid interface rather than through bulk polymer gelation, and (iii) demonstrating the complete decoupling of foam stability from formation damage in a polymer-free system. A systematic optimization methodology was employed: initial foaming agents were screened via the Waring Blender method, evaluating foam volume, half-life, and a derived comprehensive index; subsequently, synergistic binary surfactant mixtures and foam stabilizers were assessed to formulate the final systems. An optimized formulation, designated Foam System I (0.5 wt.% fluorosurfactant FK + 0.5 wt.% nano-silica RX + 2.0 wt.% KCl), demonstrated exceptional foam quality (Γ = 77.1 ± 1.5%) and kinetic stability (T₁/₂ > 350 s). Rheological characterization confirmed shear-thinning behavior conforming to the Herschel–Bulkley model (n = 0.38–0.42, R² > 0.98) and a structural recovery of 92.5 ± 2.1%—comparable to crosslinked polymer gels but achieved without any bulk viscosifier. Core flood analyses revealed that Foam System I induced a permeability damage of only 12.75 ± 1.8%, representing a 55–75% reduction compared to polyethylene glycol (PEG)-stabilized reference fluids (28.36–51.91%). X-ray photoelectron spectroscopy (XPS) correlated this enhanced reservoir compatibility with an 18.0 ± 2.0% suppression of oxygen-containing functional group adsorption, attributed to the steric hindrance conferred by the fluorinated hydrophobic moieties. This work establishes an “interfacial control” paradigm wherein gel-like stabilization for proppant transport is achieved via interfacial viscoelasticity rather than bulk polymer gelation, thereby directly addressing the critical imperative to harmonize fracture conductivity with reservoir protection in unconventional energy development. The findings are validated for shallow CBM reservoir conditions (25–35 °C), with extension to higher-temperature formations identified as a priority for future investigation. Full article

Carbon nano-onions (CNOs) were synthesized at ambient conditions using the wick-pyrolysis technique with ghee as a precursor. A high-purity copper substrate produced unique CNOs, differing from those obtained with other metals. To purify the nanoparticles, they underwent treatment with a solvent mixture of acetone and deionized water or were pyrolyzed at 1000 °C under nitrogen without a catalyst. Various characterization techniques, including X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), High-Resolution Transmission Electron Microscopy (HR-TEM), and Raman Spectroscopy, confirmed the successful formation of CNOs. Energy Dispersive Spectroscopy (EDS) and Elemental analysis (CHN) indicated the presence of oxygen in treated CNOs. X-ray photoelectron spectroscopy (XPS) revealed binding energies linked to C-O and C=O bonds. The average particle size was found to be 30–50 nm, with some agglomeration in pyrolyzed samples. A significant increase in surface area from 79.7 m²/g to 261.8 m²/g was observed, along with changes in pore radius and volume via Brunauer–Emmett–Teller (BET) analysis. Water contact angles on the CNO surface were measured at 125° and 138°, indicating hydrophobicity. Electrochemical tests on CNO-based composite electrodes yielded a specific capacitance of 109.7 F/g with 96% capacity retention over 5000 cycles. Full article

This study investigates spherical methyl silicone resin, a potentially environmentally friendly additive free of sulfur, phosphorus, and chlorine, as a lubricant additive in polyethylene glycol 200 (PEG 200) base oils. We evaluated concentration-response characteristics and tribological performance across PEG base oils containing 0.01–0.05 wt% resin. Tribological testing was conducted with a four-ball wear tester at 98 N and 1450 rpm for 30 min. All tested concentrations demonstrated excellent friction-reduction and anti-wear performance, with an optimal efficacy observed at 0.02 wt%. Surface characterization was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. This friction-reducing and anti-wear performance is attributed to the formation of silicon-oxygen species and graphene-like carbon structures, thereby effectively suppressing direct surface contact and mitigating wear. Consequently, spherical methyl silicone resin demonstrates considerable potential as a green lubricant additive for bearing steel applications. Full article

Localized surface plasmon resonance (LSPR) is an optical phenomenon that occurs when light interacts with free electrons on the surface of metallic thin films, producing intensified electromagnetic fields at specific sites, often called “hot spots”. LSPR-based sensing technologies respond to chemical and associated optical interfacial changes. Inherent advantages include enhanced sensitivity, compact size, low production cost, and strong potential for integration into portable, point-of-care diagnostic systems. This study focuses on a detailed investigation into the surface functionalization of localized surface plasmon resonance (LSPR)-based nanohole array (NHA) sensors for biomedical applications. Gold-coated NHA surfaces were functionalized using polyethylene glycol (PEG) self-assembled monolayers (SAMs), enabling specific attachment of biomolecular species. As a proof-of-concept, bovine serum albumin (BSA) and SARS-CoV-2 nanobody proteins were successfully immobilized on the PEGylated surfaces. Individual steps of surface modification including PEGylation, protein immobilization and nanobody immobilization were validated through a dual-method approach which combined measurement of LSPR optical spectral shifts and x-ray photoelectron spectroscopy (XPS) chemical analyses. Reproducibility was assessed across multiple sensors and repeated trials, confirming the repeatability of each functionalization and binding process. The sensor system, consisting of NHA-based plasmonic platform, microfluidics, and a portable optical spectrometer, exhibits the capability for reliable and sensitive, label-free detection of biomolecular targets, including viral antigens, in liquid-phase environments. Full article

The sustainable development of nuclear energy requires a secure long-term uranium supply. Seawater uranium extraction offers a nearly inexhaustible resource; however, its commercialization is limited due to high costs. To improve economic viability, this study proposes a synergistic strategy for simultaneously recovering uranium and vanadium using amidoxime-based adsorbents, with vanadium as a valuable co-product. Herein, a porous silica-supported poly(amidoxime) adsorbent was synthesized and characterized. The material possesses a well-developed porous structure with a specific surface area of 49.8 m² g⁻¹. Spectroscopic analyses confirmed the successful grafting of amidoxime groups onto the silica framework, whereas X-ray photoelectron spectroscopy revealed that uranium adsorption occurs via coordination with nitrogen and oxygen donor atoms. Batch experiments demonstrated rapid adsorption equilibrium within 2 h and a maximum Langmuir uranium capacity of 48.5 mg g⁻¹ at 45 °C. The adsorbent exhibited high selectivity toward uranium over vanadium and competing ions at near-neutral pH. Dynamic column experiments demonstrated efficient stepwise separation using 0.1 mol L⁻¹ HNO₃ for uranium and a Na₂CO₃–H₂O₂ system for vanadium, even in simulated seawater containing high concentrations of competing ions. Under the controlled model conditions employed, this study demonstrates a promising adsorbent and a feasible co-recovery strategy that may contribute to enhancing the economic feasibility of seawater uranium extraction, warranting further validation in natural seawater. Full article

Oil sands tailings from tailings solvent recovery units (TSRU) contain elevated sulfide minerals and can generate acid mine drainage (AMD) upon atmospheric exposure. This study investigated how prior weathering influences acidity and solute release under controlled laboratory conditions. A six-month column leaching experiment was conducted using TSRU tailings with distinct exposure histories: weathered and semi-weathered tailings from a previous greenhouse-scale reclamation capping experiment, along with weakly weathered tailings stored in sealed barrels. Columns were subjected to repeated wet–dry cycles, analyzing the geochemistry of the leachate and solid-phase changes using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). All treatments produced highly acidic leachates (pH < 2), indicating that TSRU tailings retain the capacity to generate acidity regardless of prior exposure. However, the dominant geochemical mechanisms differed by weathering history. Weakly weathered tailings generated progressive increases in acidity and solute release, consistent with active sulfide oxidation. Semi-weathered tailings had more stable responses, suggesting partial sulfide depletion and secondary phase formation. Weathered tailings produced leachates showing evidence of rapid flushing with limited new solute generation. After leaching, residual pyrite remained in all materials, with shifts in surface sulfur speciation providing evidence of progressive surface sulfur oxidation, transformation, and the redistribution of sulfate phases. These results demonstrate the mechanisms involved in AMD generation in TSRU tailings, highlighting the importance of the weathering history and the need for field-scale validation. Full article

Bearings in electric motors are exposed to stray currents and shaft voltages, which can accelerate surface damage and reduce service life. This study examines how pulsed direct current (DC) direction affects early-stage degradation in rolling bearings under low-speed operation. A dedicated test rig was used in which the bearing inner and outer rings were connected directly to the positive and negative terminals of a pulsed DC power supply. Unipolar excitation was applied at 20 kHz with a nominal current of 3 A and shaft-voltage peaks of about 3 V for 3 h, with current flowing in only one direction during each test. After testing, the bearings were sectioned and examined by optical microscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results showed that when current flowed from the outer ring to the inner ring, visible electrical discharge machining (EDM)-type damage was mainly found on the outer raceway. When the current direction was reversed, the damaged region shifted to the inner raceway. The affected areas showed crater-like discharge features and surface chemical changes, while the opposite raceway showed much less change under the same test conditions. These observations indicate that current direction influences where EDM-type damage more likely forms in the bearing under the present low-speed unipolar excitation conditions. Full article

Carbon materials are regarded as cost-effective adsorbents due to their ability to remove heavy metals and organic pollutants from contaminated water. In this study, a novel phenol–formaldehyde resin-derived carbon microsphere (HCM_2.5) was designed and synthesized via a hard-template method combined with KOH activation. The prepared HCM_2.5 exhibits high selectivity and removal efficiency toward heavy metal ions and delivers an ultrahigh specific surface area of 2165 m²/g. A Cr(VI) removal efficiency exceeding 99.6% could be achieved in 50 ppm acidic solution, with excellent performance at pH 2–5. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption analysis, and scanning electron microscopy (SEM) were used to confirm its porous structure with a high specific surface area. The results of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) reveal that the efficient heavy metal removal performance of HCM_2.5 is mainly attributed to its high specific surface area, as well as coordination and redox reactions between oxygen-containing functional groups and heavy metal ions. Furthermore, benefiting from its outstanding specific surface area and well-developed pore structure, a physical–chemical synergistic adsorption mechanism was proposed and systematically elucidated. Full article

A series of Mg-Al LDH-based photocatalysts were synthesized via a one-pot steam-assisted method, including pure Mg-Al LDH (MA), Zn-In ion-exchange-modified Mg-Al LDH (MAZ), BiOCl-loaded pristine Mg-Al LDH (MAB), and Zn-In-modified Mg-Al LDH co-loaded with TiO₂ and BiOCl (MA/Zn-In/TiO₂/BiOCl, MAZB). The one-pot synthesis facilitated the in situ intercalation and uniform loading of BiOCl/TiO₂/Zn-In, while Zn²⁺/In³⁺ modified the MA layers via ion exchange, leading to an expansion of the interlayer spacing. The innovation of this work is reflected in two aspects: first, all raw materials are added via a one-pot strategy to achieve in situ preparation of modified hydrotalcite; second, this synthetic route features simple post-treatment without complicated washing, pressure filtration, and other tedious operations. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and N₂ adsorption–desorption isotherms. The bismuth chloride oxide/TiO₂/LDHs exhibited a layered structure, with the active components uniformly distributed between the layers and on the MA surface. Under simulated sunlight irradiation, MAZB achieved 97.5% degradation of 20 mg/L MB within 120 min, with an apparent rate constant of 0.0297 min⁻¹, which is 7.2 times, 2.4 times, and 2.9 times that of MA, MAZ, and MAB, respectively. The degradation rate of MAZB still remained at 89.5% after five cycles, demonstrating excellent stability and reusability. Compared with traditional hydrothermal methods, this steam-assisted system features mild reaction conditions (180 °C, atmospheric pressure), sodium-free raw materials, no washing requirement, and zero waste discharge, showing prominent green advantages. Full article

A novel water treatment agent, ethylenediamine–benzenesulfonic acid-modified polyaspartic acid (PASP-S), was controllably synthesized using an amino ring-opening reaction. The controllable synthesis methods, conditions for polymerization degree, and the molecular weight of the new polymer were explored. The structure was characterized using Fourier-transform infrared spectroscopy (FT-IR), ¹H nuclear magnetic resonance (¹H-NMR), and gel permeation chromatography (GPC). The scale inhibition, corrosion inhibition, and fluorescence properties of the new polymer, as well as the corresponding mechanisms, were investigated using static scale inhibition tests, electrochemical measurements, X-ray photoelectron spectroscopy (XPS), density functional theory (DFT), and frontier molecular orbital (FMO) theory. The results indicate that PASP-S exhibits strong Ca²⁺ chelation ability and can effectively inhibit CaCO₃ and CaSO₄ scaling. At 50 mg/L, the scale inhibition efficiency for Ca₃(PO₄)₂ reaches 99.50%. At 30 mg/L, its corrosion inhibition efficiency is 33.19% higher than that of PASP. Unexpectedly, the polymer shows remarkable selective antibacterial activity. At 100 mg/mL, the inhibition rate against Escherichia coli (E. coli) is 71%, while no obvious inhibition is observed for Bacillus cereus. A good linear relationship is found between fluorescence intensity and concentration. Mechanistic studies demonstrate that PASP-S adsorbs on the scale surface, suppressing crystal growth and distorting crystal morphology. Meanwhile, it forms a protective film on the electrode surface, thus reducing the dissolution and corrosion of carbon steel. Full article

In this work, the atomic layer deposition (ALD) of an ultra-thin AlN film on the surface of monolayer EG grown on-axis 4H-SiC(0001) substrates has been investigated as a function of the number of ALD cycles. The formation of a homogeneous film with a 10 nm thickness and crystalline wurtzite structure was obtained after 320 cycles, as demonstrated by atomic force microscopy (AFM) mapping, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. Raman mapping revealed a significant reduction in the native compressive strain of as-grown EG (ε ≈ −0.36%) with increasing ALD cycles, down to a value of −0.16% after full coverage. Finally, Kelvin Probe Force Microscopy (KPFM) surface potential mapping allowed the evaluation of energy band alignment of the AlN/EG heterojunction, with a conduction band offset of ~2.6 eV between the crystalline AlN film and the underlying EG. Such a large offset confirms AlN as a promising gate dielectric for EG-based devices. Full article