Search Results (165)

Background/Objectives: This in vitro study examined the potential enhancement in resistance to accelerated aging in room-temperature vulcanized (RTV) maxillofacial silicone, intrinsically pigmented in two skin tones, through the use of zirconium oxide (ZrO₂) nanoparticles. Methods: A total of 128 disc-shaped specimens were created in rose silk and soft brown shades, each containing zirconium oxide concentrations of 0%, 1%, 2%, and 3% by weight. Color variation (ΔE*) was assessed initially and following 252, 750, and 1252 h of artificial aging, tested with a colorimeter. Surface roughness characteristics (R_a, R_q, R_t) were evaluated before and after 1252 h using atomic force microscopy (AFM). Structural, vibrational, and morphological characteristics were analyzed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM). Results: Non-parametric tests (Friedman, Kruskal–Wallis, and Bonferroni-adjusted paired testing; p < 0.05) indicated that accelerated aging significantly increased ΔE* in all specimens. The addition of ZrO₂ reduced these changes; however, the optimal concentration differed by pigment: 1% for rose silk and 3% for soft brown. The effect on surface roughness depended on pigment type. Higher nanoparticle concentrations generally improved post-aging smoothness in soft brown samples, whereas rose silk showed a more variable response. XRD and FTIR analyses confirmed successful nanoparticle incorporation without altering the fundamental silicone structure, while FESEM demonstrated improved filler–matrix interaction in modified groups. Conclusions: Adjusting ZrO₂ concentration according to pigment type can improve the future color retention and surface characteristics of maxillofacial silicone. Full article

In this research, aluminium-doped biphasic calcium phosphate (Al-BCP) was synthesized by co-precipitation and formulated with hydrolyzed collagen and acetylsalicylic acid (ASA) to yield composites designed as a new class of bone-regenerative biomaterials with enhanced biological performance. Undoped and Al-modified powders (5/10 wt% Al precursor) were prepared at 40 °C (pH ~ 11) and calcined at 700 °C, and composites were produced at a 1:1:0.1 mass ratio (ceramic–collagen–ASA). Structure and chemistry were assessed by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Raman spectroscopies, and X-ray photoelectron spectroscopy (XPS). Morphology and elemental distribution were examined by scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX). Biological performance was preliminarily evaluated using HaCaT (immortalized human keratinocytes) viability and antibacterial assays against Staphylococcus aureus and Escherichia coli. XRD confirmed a biphasic hydroxyapatite/β-tricalcium phosphate system and showed that Al incorporation shifted the phase balance toward hydroxyapatite (HAp fraction 54.8% in BCP vs. ~68.6–68.7% in Al-doped samples). FTIR/Raman preserved BCP vibrational signatures and revealed collagen/ASA bands in the composites. XPS/EDX verified the expected composition, including surface N 1s from organics and Al at ~2–5 at% for doped samples, with surface Ca/P ≈ 1.15–1.16. SEM revealed multigranular microstructures with homogeneous Al distribution. All composites were non-cytotoxic (≥70% viability); M_Al10_Col_ASA exceeded 90% viability at 12.5% dilution. Preliminary antibacterial assays against Gram-positive and Gram-negative strains showed modest, time-dependent reductions in CFU relative to controls. These results corroborate the compositional/structural profile and preliminary biological performance of Al-BCP–collagen–ASA composites as multifunctional bone tissue engineering materials that foster a bone-friendly microenvironment, warranting further evaluation for bone regeneration. Full article

Chitosan is a biopolymer with excellent properties such as biodegradability, biocompatibility, bioactivity, and non-toxicity, making it an attractive material for various applications. In this study, to enhance these properties particularly for the development of food coatings chitosan derivatives (1,2,3-triazoles) were synthesized via microwave-assisted 1,3-dipolar cycloaddition (CuAAC) using different terminal alkynes. The resulting compounds were obtained in high yields 79.7–88.0% and characterized by vibrational (IR) and electronic (UV–Visible) spectroscopy. Films were formed by combining the derivatives with PVA and characterized using differential scanning calorimetry (DSC), tensile strength testing, and water vapor permeability analysis. The resulting films exhibited improved mechanical properties, homogeneous thicknesses, low-porosity surfaces, and favorable barrier properties, highlighting their potential applicability as food coating materials. Full article

The Raman spectrum of adenine and the surface-enhanced Raman spectrum (SERS) upon adsorption of adenine on an Ag₈ cluster in aqueous solution were calculated using the DFT/PBE0/Def2-TZVP method with the IEF-PCM solvent model. TD-DFT calculations were performed to determine the excitation wavelengths of adenine and the Ag₈•A complex, thereby selecting excitation wavelengths compatible with available experimental Raman spectroscopy instruments. In addition, excitation wavelengths with the maximum oscillator strength were chosen to propose characteristic spectra for experimental studies. The calculated Raman activities were converted into Raman scattering intensities, and the enhancement factor EF_int was determined. The results show that an excitation wavelength of 325 nm gives the strongest and most distinct SERS signal, 532 nm provides stable signals suitable for commercial instruments, while 442 nm significantly reduces several characteristic vibrational bands. Moreover, the Ag₈ cluster exhibits excellent enhancement of the Raman signal for adenine. This study provides a basis for selecting excitation wavelengths and characteristic vibrational modes to identify adenine, supporting the development of label-free biosensors based on silver clusters. Full article

This research investigated the sustainable biosynthesis of silver nanoparticles (AgNPs) using Zinnia elegans L. extracts to demonstrate the potential of plant-based methods in nanotechnology. The antioxidant and antibacterial properties of the plant extracts were evaluated, and the phytocompounds that react as natural reducing agents in the synthesis of AgNPs were characterized. This approach has demonstrated the potential of Zinnia elegans L. as an environmentally friendly source for the production of AgNPs. The biosynthesized AgNPs were characterized based on their optical, structural, and morphological properties using various techniques, including scanning electron microscopy (SEM), attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), and thermogravimetric and differential thermal analysis (TGA/DTA). X-ray diffraction (XRD) analysis confirmed the presence of pure silver phases exhibiting a face-centered cubic (FCC) crystalline structure. Ultraviolet–visible (UV–Vis) spectroscopy revealed an absorption peak at 462 nm, which is characteristic of the surface plasmon resonance associated with AgNPs. ATR-FTIR analysis identified several vibrational peaks corresponding to the functional groups of the constituents present in the biosynthesized AgNPs. The size distribution of the AgNPs was found to range from 10 to 30 nm, and both SEM and TEM confirmed their predominantly spherical morphology. Energy dispersive X-ray spectroscopy (EDX) analysis corroborated the predominance of silver as the principal element within the composition of the nanoparticles. This technique provided quantitative elemental analysis, confirming the high purity and concentration of silver in the synthesized AgNPs. The study effectively elucidated the synthesis of AgNPs utilizing plant extracts as natural reducing agents. The synthesized AgNPs exhibited significant antibacterial and antioxidant activities, indicating their potential applicability in diverse biomedical and environmental contexts. Employment of the advanced characterization techniques facilitated a thorough understanding of the multifaceted properties of the synthesized AgNPs, thereby enhancing their viability for future research and application in nanomedicine and bioremediation. Using Zinnia elegans L. for the biosynthesis of plant-synthesized AgNPs is a sustainable and eco-friendly technique that offers a viable alternative to conventional chemical processes. Full article

This research successfully synthesized a novel n-n heterojunction Bi₂O₂CO₃/AgVO₃ nanocomposite photocatalyst via the in situ chemical deposition process. Characterization results strongly confirmed the formation of a tight heterojunction at the Bi₂O₂CO₃/AgVO₃ interface. The nanocomposite exhibited characteristic XRD peaks and FT-IR vibrational modes of both Bi₂O₂CO₃ and AgVO₃ simultaneously. Electron microscopy images revealed AgVO₃ nanorods tightly and uniformly loaded onto the surface of Bi₂O₂CO₃ nanosheets. Compared to the single-component Bi₂O₂CO₃, the composite photocatalyst exhibited a red shift in its optical absorption edge to the visible region (515 nm) and a decrease in bandgap energy to 2.382 eV. Photoluminescence (PL) spectra demonstrated the lowest fluorescence intensity for the nanocomposite, indicating that the recombination of photogenerated electron–hole pairs was suppressed. After 90 min of visible-light irradiation, the degradation efficiency of Bi₂O₂CO₃/AgVO₃ toward methylene blue (MB) reached up to 99.55%, with photodegradation rates 2.51 and 2.79 times higher than those of Bi₂O₂CO₃ and AgVO₃, respectively. Furthermore, the nanocomposite exhibited excellent cycling stability and reusability. MB degradation was gradually enhanced with increasing the photocatalyst dosage and decreasing initial MB concentration. Radical trapping experiments and absorption spectroscopy of the MB solution revealed that reactive species h⁺ and ·O₂⁻ could destroy and decompose the chromophore groups of MB molecules effectively. The possible mechanism for enhancing photocatalytic performance was suggested, elucidating the crucial roles of charge carrier transfer and active species generation. Full article

Fe-CNT composites were synthesized via mechanical ball milling, incorporating varying amounts of carbon nanotubes (CNTs) into iron powder at concentrations of 1 wt%, 2 wt%, and 3 wt%. The impact of different CNT contents on the phase structure, microstructure, and magnetic properties of the composites was examined. Raman spectroscopy and X-ray diffraction (XRD) analyses revealed that despite some damage, CNTs retained a predominantly one-dimensional nanostructure post-ball milling. Moreover, an increase in CNT content led to a gradual rise in grain size and lattice strain of the iron powder, attributed to the formation of solid solutions and iron–carbon compounds. Scanning electron microscopy (SEM) observations demonstrated that the majority of CNTs were integrated within the iron matrix particles, with a minority either partially embedded or entirely unembedded on the iron powder surface. With higher CNT concentrations, local CNT agglomeration emerged and intensified. Vibrating sample magnetometer (VSM) measurements indicated that Fe-CNT composites exhibited enhanced saturation magnetization (2.25%) and reduced coercivity (91.74%) compared to pure iron, underscoring the potential of CNTs in enhancing the magnetic properties of iron powder. Full article

Electrochemical CO₂ reduction reaction (CO₂RR) is a key technology for achieving carbon neutrality and efficient utilization of renewable energy, capable of converting CO₂ into high-value-added carbon-based fuels and chemicals. Copper (Cu)-based catalysts have attracted significant attention due to their unique performance in generating multi-carbon (C₂₊) products such as ethylene and ethanol; however, there are still many controversies regarding their complex reaction mechanisms, active sites, and the dynamic evolution of intermediates. In situ Raman spectroscopy, with its high surface sensitivity, applicability in aqueous environments, and precise detection of molecular vibration modes, has become a powerful tool for studying the structural evolution of Cu catalysts and key reaction intermediates during CO₂RR. This article reviews the principles of electrochemical in situ Raman spectroscopy and its latest developments in the study of CO₂RR on Cu-based catalysts, focusing on its applications in monitoring the dynamic structural changes of the catalyst surface (such as Cu⁺, Cu⁰, and Cu²⁺ oxide species) and identifying key reaction intermediates (such as *CO, *OCCO(*O=C-C=O), *COOH, etc.). Numerous studies have shown that Cu-based oxide precursors undergo rapid reduction and surface reconstruction under CO₂RR conditions, resulting in metallic Cu nanoclusters with unique crystal facets and particle size distributions. These oxide-derived active sites are considered crucial for achieving high selectivity toward C₂₊ products. Time-resolved Raman spectroscopy and surface-enhanced Raman scattering (SERS) techniques have further revealed the dynamic characteristics of local pH changes at the electrode/electrolyte interface and the adsorption behavior of intermediates, providing molecular-level insights into the mechanisms of selectivity control in CO₂RR. However, technical challenges such as weak signal intensity, laser-induced damage, and background fluorescence interference, and opportunities such as coupling high-precision confocal Raman technology with in situ X-ray absorption spectroscopy or synchrotron radiation Fourier transform infrared spectroscopy in researching the mechanisms of CO₂RR are also put forward. Full article

The fracture behavior of a locking pin used in the penultimate-stage blades of a 600 MW steam turbine in a thermal power plant was investigated through microstructural and microhardness characterization, fracture surface and energy-dispersive spectroscopy (EDS) analysis, as well as finite element load simulation. The microhardness values measured on the cross-section of the service pins ranged from 528 to 541 HV0.1, showing little difference from the unused pins. Scanning electron microscopy analysis revealed that approximately 70% of the fracture surfaces exhibited an intergranular “rock candy” morphology. The results indicate that pin failure was primarily caused by the combined effects of fretting wear and stress corrosion cracking (SCC). Specifically, vibration at the blade root, impeller, and pins due to start–stop cycles and load variations led to fretting wear, forming pits approximately 75 μm in size. Under the combined effects of weakly corrosive wet steam environments and shear stresses, SCC initiated at the high stress concentration points of these pits. Early crack propagation primarily followed original austenite grain boundaries, while later stages mainly extended along martensite plate boundaries. As cracks advanced, the cross-sectional area gradually decreased, causing the effective shear stress to increase until it exceeded the shear strength, ultimately leading to fracture. These findings not only provide a scientific basis for enhancing the reliability of steam turbine locking pins and extending their service life, but also contribute to a broader understanding of the failure mechanisms of key components operating under corrosive and fluctuating load environments. Full article

One of the major challenges in diagnosing various diseases, including neurological and neurodegenerative disorders, as well as carcinogenesis, is detecting unlabeled neurotransmitters. Surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared spectroscopy (SEIRA) are promising methods for neurotransmitter biosensing and bioimaging. These methods are unique in that they are non-destructive and can identify molecular fingerprints. In this study, these methods were used to detect the following potent bradykinin (BK) antagonists: [D-Arg⁰,Hyp³,Thi⁵,D-Tic⁷,Oic⁸]BK, [D-Arg⁰,Hyp³,Thi⁵,D-Phe⁷,Thi⁸]BK, [D-Arg⁰,Hyp³,Igl⁵,D-Phe(5F)⁷,Oic⁸]BK, and [D-Arg⁰,Hyp³,Igl⁵,D-Igl⁷,Oic⁸]BK. The peptides were immobilized on a sensor surface consisting of silver (AgNPs) and gold (AuNPs) nanoparticles. These sensors have uniform particle sizes and small size distributions. Thanks to fast synthesis, easy handling, and reproducible results, these sensors enable routine testing. The vibrational structure of these peptides could not be determined using classical vibrational methods (Raman and IR) or surface-enhanced methods (SERS and SEIRA). This work presents the results of that research. Additionally, the SEIRA spectrum for BK or its analogs has not yet been published. This study presents research using SERS and SEIRA that shows that AgNP and AuNP sensors can detect the peptides under investigation. SERS is a more selective method than SEIRA because it allows for the differentiation of peptides based on the enhancement of certain bands in the SERS spectra. Furthermore, each peptide uniquely interacts with AuNPs, whereas all peptides bind to AgNPs via the C-terminus in different orientations. Consequently, the AuNP sensor is more selective than the AgNP sensor. Some bands were selected as markers for the sensing of specific peptides. Full article

This study investigates the impact of oxygen-containing functional groups (COO-Li, CO-Li, and O-Li) on the electronic and optical properties of graphene, with a focus on hydrogen sensing applications. Using density functional theory (DFT) calculations, we evaluated the thermodynamic feasibility of the functionalization and hydrogen adsorption processes. The Gibbs free energy changes (ΔG) for the functionalization of pristine graphene were calculated as −1233, −1157, and −1119 atomic units (a.u.) for COO-Li, CO-Li, and O-Li, respectively. These negative values indicate that the functionalization processes are spontaneous (ΔG < 0), with COO-Li being the most thermodynamically favorable. Furthermore, hydrogen adsorption on the functionalized graphene surfaces also exhibited spontaneous behavior, with ΔG values of −1269, −1204, and −1175 a.u., respectively. These results confirm that both functionalization and subsequent hydrogen adsorption are energetically favorable, enhancing the potential of these materials for hydrogen sensing applications. Among the functional groups we simulated, COO-Li exhibited the largest surface area and volume, which were attributed to the high electronegativity and steric influence of the carboxylate moiety. Based on the previously described results, we analyzed the interaction of these functionalized graphene systems with molecular hydrogen. The adsorption of two H₂ molecules per system demonstrated favorable thermodynamics, with lithium atoms serving as active sites for external adsorption. The presence of lithium atoms significantly enhanced hydrogen affinity, suggesting strong potential for sensing applications. Further, electronic structure analysis revealed that all functionalized systems exhibit semiconducting behavior, with band gap values modulated by the nature of the functional group. FTIR (Fourier-Transform Infrared Spectroscopy) and Raman spectroscopy confirmed the presence of characteristic vibrational modes associated with Li-H interactions, particularly in the 659–500 cm⁻¹ range. These findings underscore the promise of lithium-functionalized graphene, especially with COO-Li, as a tunable platform for hydrogen detection, combining favorable thermodynamics, tailored electronic properties, and spectroscopic detectability. Full article

We present a dual biosensing strategy integrating Quartz Crystal Microbalance (QCM) and Surface-Enhanced Raman Spectroscopy (SERS) for the quantitative and molecular-specific detection of FKBP12. Silver nanodendritic arrays were electrodeposited onto QCM sensors, optimized for SERS enhancement using Rhodamine 6G, and functionalized with a custom-designed receptor to selectively capture FKBP12. QCM measurements revealed a two-step Langmuir adsorption behavior, enabling sensitive mass quantification with a low limit of detection. Concurrently, in situ SERS analysis on the same sensor provided vibrational fingerprints of FKBP12, resolved through comparative studies of the free protein, surface-bound receptor, and surface-bound receptor–protein complex. Ethanol-induced denaturation confirmed protein-specific peaks, while shifts in receptor vibrational modes—linked to FKBP12 binding—demonstrated dynamic molecular interactions. A ratiometric parameter, derived from key peak intensities, served as a robust, concentration-dependent signature of complex formation. This platform bridges quantitative (QCM) and structural (SERS) biosensing, offering real-time mass tracking and conformational insights. The nanodendritic substrate’s dual functionality, combined with the receptor’s selectivity, advances label-free protein detection for applications in drug diagnostics, with potential adaptability to other target analytes. Full article

Coatings that are tolerant of poor surface preparation are often used for rapid, real-time maintenance of aging steel surfaces. In this study, a modified epoxy (EP) anti-rust coating was proposed, utilizing methyl gallate (MG) as a rust conversion agent, graphene oxide (GO) as an active functional material, and epoxy resin as the film-forming material. The anti-rust mechanism was investigated using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), and the scanning vibration electrode technique (SVET). The results demonstrated that over a period of 21 days, the impedance of the coating increases while the corrosion current density decreases with prolonged soaking time. The coating exhibited a maximum impedance of 2259 kΩ, and a lower corrosion current density of 8.316 × 10⁻³ A/m², which demonstrated a three-order magnitude reduction compared to the corrosion current density observed in mild steel without coating. LSCM demonstrated that MG can not only penetrate the tiny gap between the rust particles, but also effectively convert harmful rust into a complex. SVET showed a much more uniform current density distribution in the micro-zones of mild steel with the anti-rust coating compared to uncoated mild steel, indicating that the presence of GO not only enhanced the electrical conductivity of the coating, but also improved the structure of the coating, which contributed to the high performance of the modified epoxy anti-rust coating. This work highlights the potential application of anti-rust coating in the protection of metal structures in coastal engineering. Full article

An anion exchange-assisted technique was used for the synthesis of platinum-decorated SnO₂ supports, providing nanocatalysts with enhanced activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). In this study, a series of SnO₂ supports, namely SnA (synthesized almost at room temperature), SnB (hydrothermally treated at 180 °C), and SnC (annealed at 600 °C), are systematically investigated, all loaded with 1 mol% Pt from H₂PtCl₆ under identical mild conditions. The chloride ions from the SnCl₄ precursors were efficiently removed via a strong-base anion exchange reaction, resulting in highly dispersed, crystalline ~5 nm cassiterite SnO₂ particles. All Pt/SnO₂ composites displayed mesoporous structures with type IVa isotherms and H₂-type hysteresis, with SP1a (Pt on SnA) exhibiting the largest surface area (122.6 m²/g) and the smallest pores (~3.5 nm). STEM-HAADF imaging revealed well-dispersed PtOx domains (~0.85 nm), while XPS confirmed the dominant Pt⁴⁺ and Pt²⁺ species, with ~25% Pt⁰ likely resulting from photoreduction and/or interactions with Sn–OH surface groups. Raman spectroscopy revealed three new bands (260–360 cm⁻¹) that were clearly visible in the sample with 10 mol% Pt and were due to the vibrational modes of the PtOx species and Pt-Cl bonds introduced due the addition and hydrolysis of H₂PtCl₆ precursor. TGA/DSC analysis revealed the highest mass loss for SP1a (~7.3%), confirming the strong hydration of the PtOx domains. Despite the predominance of oxidized PtOx species, SP1a exhibited the highest catalytic activity (k_app = 1.27 × 10⁻² s⁻¹) and retained 84.5% activity for the reduction of 4-NP to 4-AP after 10 cycles. This chloride-free low-temperature synthesis route offers a promising and generalizable strategy for the preparation of noble metal-based nanocatalysts on oxide supports with high catalytic activity and reusability. Full article

Cellulose nanofiber (CNF) treatments can enhance the structure and performance of regenerated cellulose fibers. This study investigates the effects of CNF treatment on the mechanical properties, water absorption behavior, and humidity dependence of regenerated cellulose fibers. Tensile testing demonstrated that CNF-treated fibers exhibit improved elasticity and reduced swelling in aqueous environments. Scanning electron microscopy revealed the adsorption of CNF components onto the fiber surfaces. Microbeam X-ray diffraction indicated structural differences between untreated and CNF-treated fibers, with the latter containing cellulose I crystals. Small-angle X-ray scattering revealed alterations in the internal fibrillar structure due to CNF treatment. FT-IR spectroscopy highlighted humidity-dependent variations in molecular vibrations, with peak intensities increasing under higher humidity conditions. Additionally, CNF treatment inhibited water absorption in high-humidity conditions, contributing to reduced expansion rates and increased elastic modulus during water absorption. Overall, CNF treatment enhanced both the mechanical strength and water resistance of regenerated cellulose fibers, making them suitable for advanced textile applications. This study provides valuable insights into the role of CNF-treated fibers in improving the durability and functional performance of regenerated cellulose-based textile. Full article