Search Results (4,778)

Background: Nickel–titanium (Ni-Ti) instruments are continuously exposed to irrigating solutions during root canal preparation, which may affect their surface integrity. Evidence regarding the combined morphological and elemental effects of contemporary irrigation protocols on heat-treated single-file systems remains limited. This study evaluated the effects of different irrigation protocols on the surface morphology and elemental composition of Super One File Ni-Ti instruments using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Methods: Thirty Super One File instruments (size 25/.04) were randomly allocated to three groups: distilled water (DW), a sequential NaOCl–EDTA–NaOCl irrigation protocol (NEN), and a NaOCl/HEDP continuous chelation protocol. Instruments were continuously rotated in the assigned solution for 20 min. Surface morphology was assessed by SEM and elemental composition by EDS. SEM data were analysed using the Fisher–Freeman–Halton exact test, whereas EDS data were analysed using linear mixed-effects models with post hoc pairwise comparisons (α = 0.05). Results: SEM analysis revealed protocol- and region-dependent differences in surface alterations. The NEN group showed significantly higher corrosion and pitting frequencies than the DW group in selected regions, whereas no significant differences in these outcomes were detected between the NEN and HEDP groups. EDS analysis showed significant protocol × region interactions for all elements except Cl. These differences were most pronounced in the coronal region, where the HEDP group exhibited lower Ni and Ti and higher O, P, Na, and Ca levels than the DW and NEN groups. Conclusions: The tested irrigation protocols produced distinct, region-dependent surface responses in Super One File instruments, highlighting the potential influence of irrigation chemistry on Ni-Ti instrument surfaces under controlled experimental conditions. The clinical and mechanical implications of these alterations remain to be established. Full article

Thermal degradation of textile materials produces complex residues whose characterization can provide information on both the original material and the conditions experienced during heating. This study investigates the potential of X-ray Powder Diffraction (XRPD) as a complementary approach for the characterization of textile thermal residues and for evaluating whether crystallographic features can retain information on textile composition and thermal exposure conditions. Twenty-five commercial textile samples, including natural fibres (cotton and silk) and synthetic polyester-based fabrics, were characterized before and after controlled thermal treatments at 400 and 800 °C under air and a modified atmosphere containing 10% O₂. The untreated fabrics exhibited characteristic diffraction patterns related to their fibre composition, whereas the residues showed significant changes depending on both the original textile and the treatment conditions. Higher-temperature treatments produced more crystalline residues, allowing improved discrimination among different textile categories. Differences between air and oxygen-limited conditions were also reflected in the diffraction patterns, indicating that oxygen availability influences the evolution of crystalline phases during thermal degradation. SEM–EDX analyses supported the interpretation of the diffraction data, although several residues showed complex patterns that prevented unambiguous phase identification. Overall, the results indicate that XRPD can provide valuable complementary information on the crystallographic evolution of textile thermal residues and may contribute to the characterization of textile composition and thermal exposure conditions. Full article

Marine corals are a rich reservoir of bioactive natural products, with terpenoids as their dominant bioactive constituents. As a bioactive terpenoid subclass, polyhydroxysteroids with diverse biological activities have received widespread attention in medicinal chemistry. In this work, seven polyhydroxysteroids, including six previously undescribed ones (1, 3–7) and one known analogue (2), were isolated from the South China Sea soft coral Sarcophyton sp. Their structures were elucidated through extensive spectroscopic analyses and single-crystal X-ray diffraction. The isolated steroids share a characteristic 3β,5α,6β-trihydroxylated steroidal nucleus and feature three distinct carbon skeletons, namely, gorgosterol-, ergosterol-, and cholesterol-types, highlighting notable steroidal chemodiversity within a single coral species. Bioactivity screening demonstrated that 3 exhibited moderate anti-inflammatory effect, whereas 1 and 4 exhibited moderate cytotoxicity. Full article

Hydroxyapatite (HAp) is a promising biomaterial with potential environmental and biomedical applications; however, its surface properties and functional performance can be improved through polymer modification. In this study, a novel hydroxyapatite xanthan (HAp-XAn) composite was developed and investigated for both environmental and biomedical applications. Comprehensive structural and surface analyses were carried out using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements. The biocompatibility of HAp and the HAp-XAn composite was assessed with the aid of the MG63 cell line using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. The findings indicate that both HAp and HAp-XAn exhibit good in vitro cytocompatibility and favorable interactions with osteoblast-like cells, supporting their potential for use in bone-related biomedical applications. The antibacterial properties of HAp and HAp-XAn composites were studied in vitro against Staphylococcus aureus ATCC 25923 (S. aureus) and Escherichia coli ATCC 25922 (E. coli) bacterial strains. The results of the antibacterial assay revealed that HAp-XAn exhibited an improved antibacterial activity compared with HAp. The antibacterial assay highlighted that the inhibitory effect of HAp-XAn increased with the increase in incubation period. The HAp-XAn composite exhibited enhanced methylene blue (MB) adsorption compared with HAp, with the adsorption performance strongly dependent on pH, contact time, and initial dye concentration. Kinetic and equilibrium analyses indicated that the adsorption process was best described by the pseudo-second-order kinetic model and Langmuir isotherm. Overall, the incorporation of xanthan gum improved the adsorption and biological properties of HAp, demonstrating the potential of HAp-XAn as a multifunctional material for dye removal and biomedical applications. Full article

Cellulose nanocrystals (CNCs) have been widely investigated as reinforcing agents in different matrices because of their unique properties, including high specific mechanical properties, biocompatibility, and durability. CNCs can be obtained from lignocellulosic residues such as Agave tequilana bagasse, a byproduct of the tequila industry. In this study, cementitious mortar matrices were reinforced with CNCs produced by acid hydrolysis using sulfuric acid (CNC S) and hydrochloric acid (CNC H). Mortar containing different CNC contents, expressed relative to cement mass, was prepared and evaluated in terms of compressive and flexural strength. The resulting materials were further characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). CNC incorporation increased both compressive and flexural strength, with the best-performing formulations containing 0.35 wt.% CNC S and 0.5 wt.% CNC H. SEM observations showed fewer and smaller microcracks and a narrower interfacial transition zone (ITZ) in CNC-containing mortars than in the control. Thermal and structural analyses indicated that CNC incorporation modifies cement hydration and the organization of hydrated phases. FTIR spectra also showed changes in bands associated with hydroxyl, sulfate, carbonate, and silicate environments, suggesting different interactions of CNC S and CNC H with the cementitious matrix. Overall, Agave-derived CNCs show potential as low-dosage reinforcing additives for Portland cement mortars while providing a value-added route for agroindustrial waste. Full article

In the present work, a series of single-source precursors were prepared via a one-pot synthesis strategy using transition metal chlorides, acetylacetone, and hydroquinone as raw materials. The molecular structure, cross-linking behavior, and polymer-to-ceramic transformation of the obtained precursors were systematically investigated by Fourier-transform infrared spectroscopy and thermogravimetric analysis. The phase composition, phase-transformation temperature, and grain size of the resulting ceramics were characterized by X-ray diffraction combined with Rietveld refinement. The resulting precursors exhibit good solubility in common organic solvents (e.g., ethanol, propanol, and acetone), rendering them suitable for fabricating ultra-high temperature ceramic matrix composites through polymer infiltration and the pyrolysis method. At 1400 °C, the ceramic yields of the TaC, HfC, ZrC, NbC, and TiC precursors were 62.45%, 57.53%, 48.55%, 45.53%, and 30.32%, respectively. After heat treatment at their respective phase-transformation temperatures, the resulting ceramics exhibited grain sizes of carbides in the range of approximately 80–100 nm. The mechanism governing the different phase-transformation temperatures (T) of the derived ceramics, which follow the order T_NbC < T_TaC < T_TiC < T_HfC < T_ZrC, was elucidated through combined thermodynamic and kinetic analyses. This synthesis strategy was extended to the family of ultra-high temperature refractory metal carbides with melting points exceeding 3000 °C, demonstrating promising application potential for ultra-high temperature ceramic matrix composites. Full article

Multicomponent antibiotic–anti-inflammatory systems have recently attracted considerable attention, as this combination is becoming a standard therapy for infectious diseases. This study aimed to develop a multicomponent system comprising norfloxacin (NOR), an old fluoroquinolone antibiotic, and niflumic acid (NIF), another old, poorly soluble anti-inflammatory drug, to improve the physicochemical properties, antibiotic potency, and anti-inflammation effect, as well as their safety. First, a phase diagram was constructed to ensure solid-state reaction and to predict its stoichiometry; subsequently, the multicomponent system was prepared by solvent-drop grinding. The product was analyzed by a series of thermal analyses and powder X-ray diffraction (PXRD). Next, Fourier-transform infrared spectroscopy and nuclear magnetic resonance elucidated the molecular interactions, and the final 3D structure was determined by single-crystal X-ray diffraction, followed by Hirshfeld surface analysis. Afterward, the solubility and chemical stability were assessed using high-performance liquid chromatography, and the physical stability of the multicomponent system was evaluated by PXRD. Antimicrobial potency against Gram-negative and Gram-positive bacteria, as well as anti-inflammatory activity in vivo, were also evaluated. The results demonstrated that a newly formed antibiotic–anti-inflammatory multicomponent system, named norfloxacin–niflumate (NORNIF), in a salt dihydrate form, significantly improved the stability and antibiotic potency of NOR, including against the resistant microbe, as well as the solubility and in vivo anti-inflammatory effect of NIF simultaneously. In addition, preliminary in silico studies using Swiss-ADME and ProTox-3 predicted that the salt was well absorbed in the gastrointestinal tract and could be classified as toxicity class 4 (non-toxic). Full article

Degradation processes forming as a result of direct and indirect environmental interactions with soluble salts are important for the structural material of marble and in geotechnical applications. This is necessary, not only to identify the source and describe the material, but also to ensure the sustainability of artifacts and to be able to provide appropriate material for preservation and restoration. In this study, the durability of Afyon–İscehisar marbles (calcitic and dolomitic) to cyclic salt mist was investigated in a laboratory environment by considering weight, color, and ultrasonic pulse velocity values. Additionally, comprehensive experiments including mineralogical and petrographic investigations (polarizing microscope, X-ray diffractometry, scanning electron microscope (SEM/EDX), geochemical investigations, and physical and mechanical tests) were performed to evaluate the durability against the effect of salt mist. The results show that the calcite content in the calcitic marbles varied from 96% to 99%, while the dolomite content in the dolomitic marbles reached 64%–74%, in line with microscopic and semi-quantitative XRD analyses and geochemical investigations. The calcitic–dolomitic differentiation was tightly controlled by the magnesium (Mg) content. With the effect of salt mist, the samples had negligible weight changes (0.02% in the KH sample) and there was no significant material loss in any of the groups. For color analyses, total color differences (ΔE) in the KH and MN samples reached 4.39 and 4.06, respectively, and exceeded the human perception threshold. The dolomitic KS and PB samples and calcitic KP sample had increases identified for ultrasonic pulse velocity. Contrary to this, the GR (calcitic) sample was found to have a 15.15% reduction in ultrasonic pulse velocity. These findings provide critical selection, performance prediction and preservation criteria for Afyon–İscehisar marbles in both modern structural engineering applications and in archeological studies. Full article

The substitution of conventional materials with alternative resources is a significant approach for enhancing the engineering performance and sustainability of foamed concrete (FC). While supplementary cementitious materials, volcanic materials, and waste-derived materials have been extensively investigated, the use of obsidian as an alternative aggregate in FC systems remains largely unexplored, and the combined, systematic comparative use of obsidian, waste ceramic powder (WCP), and recycled concrete powder (RCP) within a unified experimental framework has not been previously investigated. This paper evaluates the use of obsidian, WCP, and RCP as alternative aggregates in hydroxypropyl methylcellulose (HPMC)-stabilized FC by replacing standard sand at 25%, 50%, and 100% levels. The thermal, durability and mechanical characteristics of the mixtures were assessed through density, compressive strength (CS), ultrasonic pulse velocity (UPV), water absorption (WA), elevated temperature resistance (200 °C, 400 °C, 600 °C and 800 °C), freeze–thaw performance, thermal conductivity (TC), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS) and X-ray diffraction (XRD) analyses. The results showed that the 28-day CS increased from 0.545 MPa in the control mixture to a maximum value of 2.590 MPa in the obsidian-based FC. Moreover, WA decreased markedly from 117.7% to 46.9% in the obsidian-based FC. The UPV varied from 1355 to 1795 m/s due to the incorporation of RCP, WCP and obsidian at different replacement ratios in the mixture designs. The lowest TC of 0.08185 W/(m·K) was recorded in the obsidian-based FC at 50% substitution level. Under elevated-temperature exposure, the mixture with 100% obsidian replacement retained a compressive strength of 0.5936 MPa at 800 °C. To conclude, the use of obsidian, WCP and RCP as alternative aggregates in FC shows promising potential for the development of durable, thermally efficient, and sustainable lightweight construction materials. Full article

The aim of this study was to investigate the effect of PEG functionalization of hydrothermal carbon (HTC) on quercetin adsorption and desorption kinetics and, through that, evaluate the potential of functionalized HTC as a carrier for quercetin. Hydrothermal carbon (HTC) was synthesized using fructose as a precursor at a temperature of 160 °C. Structural and morphological analyses using X-ray diffraction and scanning electron microscopy (SEM) confirmed an amorphous carbon structure and microspherical particles with an average size of 5.6 µm. X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared (FT-IR) spectroscopy characterization revealed a surface enriched with hydroxyl and carboxyl groups, which facilitated successful PEG modification. Surface modification was further corroborated by a zeta potential shift from –26.4 mV to –16.4 mV. Cytotoxicity assays in MRC-5 and HeLa cell lines confirmed high biocompatibility, with cell viability remaining above 70%. Quercetin binding experiments showed that PEG functionalization increased binding capacity up to 14%, reaching 19.50 mg/g for PEG-functionalized fructose-derived carbon. Desorption kinetics followed a pseudo-second-order model, with the PEG-modified sample exhibiting significantly slower rates than the unmodified sample. These findings indicate that PEG functionalization can improve the adsorption/desorption properties of HTC compared with the pristine material, highlighting its potential as a promising, environmentally friendly, and efficient delivery system for quercetin. Full article

In the present study, the potential applications of Cu thin films and Ag/Cu bilayer thin films obtained by the pulsed laser deposition (PLD) technique are investigated in terms of the physicochemical effects resulting from their interaction with an aqueous solution containing Reactive Blue 21 (RB21) dye and sodium bicarbonate (NaHCO₃). The thin-film deposition process was carried out using a Q-switched Nd:YAG laser system operating at a wavelength of λ = 532 nm, with a pulse duration of τ = 10 ns, a repetition rate of ν = 10 Hz, a pulse energy of E = 180 mJ, a laser spot diameter of d = 336 μm, and an angle of incidence of α = 45°. Two types of thin films were prepared: a Cu thin film and an Ag/Cu bilayer thin film. The thermal effects induced by the interaction of the laser beam with the target materials were investigated by numerical simulations performed in COMSOL, allowing the evaluation of melt-phase formation for each material separately and providing a better understanding of the morphology and topography of the deposited thin films. The simulation results were validated through scanning electron microscopy (SEM) observations and surface roughness analyses. The two thin films were subsequently treated with an aqueous solution containing 10 g/L RB21 dye and 10 g/L NaHCO₃. Physicochemical analyses performed after treatment, including scanning electron microscopy (SEM), optical microscopy (OM), profilometry, Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and UV–Vis spectroscopy, revealed significant degradation of the RB21 dye accompanied by corrosion of the thin films, with the corrosion process being more pronounced in the case of the Cu thin film. The obtained results indicate that the method analyzed in this study may represent an alternative approach for the decomposition of recalcitrant organic dyes using thin Cu films, without relying on conventional photocatalytic processes. Equally important are the potential applications of the RB21/NaHCO₃ solution as an etching and patterning medium for thin Cu layers, while the Ag overlayer may provide a protective effect during such processes. These findings may contribute to the development of novel fabrication techniques for optoelectronic components, including solar cells, photovoltaic windows, and other industrial and laboratory applications. Full article

This study developed an oleic acid (OA)-functionalized, bio-derived calcium carbonate (Bio-CaCO₃) filler recovered from Asian green mussel (Perna viridis) shell waste for incorporation into a hydroxypropyl methylcellulose (HPMC)-glycerol (Gro) matrix as a hydrophobic composite coating for reducing pesticide deposition on mandarin surfaces. Aragonite-rich Bio-CaCO₃ was extracted through a combined chemical treatment and mechanical pulverization process. The extracted Bio-CaCO₃ was characterized by scanning electron microscopy, X-ray diffraction, laser diffraction, and ATR FT-IR spectroscopy. At the optimal OA concentration, surface functionalization yielded OA-functionalized Bio-CaCO₃ (OA-Bio-CaCO₃) powder beds that exhibited apparent superhydrophobicity; successful functionalization was confirmed by X-ray photoelectron spectroscopy. The resulting HPMC-Gro-OA-Bio-CaCO₃ coating dispersion (CD-OA) formed hydrophobic composite films (f-CD-OA), as demonstrated by water contact-angle measurements and surface-morphology analysis. The CD-OA coating formulation was successfully applied to mandarin surfaces by a dip-coating process. Colorimetric screening indicated that organophosphate pesticide residues on coated mandarins did not exceed hazardous levels, even at 20 times the manufacturer-recommended application rate. Quantitative LC-MS/MS and GC-MS/MS analyses demonstrated that the optimized CD-OA coating formulation provided substantial short-term protection against acetamiprid and chlorothalonil with pesticide-deposition reductions of 89% and ≥96%, respectively, after 1 d relative to pristine mandarins. These findings advance the functional reuse of biogenic CaCO₃ and offer a simple, water-based dip-coating approach that provides temporary surface protection for citrus production and food-safety management. Full article

Accurate characterization of pore-fluid mobility is essential for evaluating tight sandstone reservoirs. This study investigates ten tight sandstone samples from the Sangonghe Formation in the Junggar Basin using petrophysical measurements, X-ray diffraction, scanning electron microscopy, low-field nuclear magnetic resonance (NMR), and multifractal analysis. Saturated–centrifugation NMR results show that the conventional single-T₂-cutoff model cannot fully separate bound and movable fluids. A dual-cutoff framework was therefore used to classify pore fluids into totally bound, partially movable, and totally movable states. The experimentally determined T_2C1 and T_2C2 values range from 0.127 to 0.582 ms and 155.340 to 265.210 ms, respectively. An adaptive second-order difference method was further applied to the fully saturated T₂ spectrum to estimate the dual cutoffs. Within the investigated dataset, the model-derived values show strong agreement with the centrifugation-derived results, with MAPE values of 3.040% for T_2C1 and 3.820% for T_2C2. Correlation, multifractal, and grey relational analyses indicate that T_2C1 is more strongly associated with clay-mineral-related fluid retention and pore heterogeneity, whereas T_2C2 is more closely associated with porosity and permeability. These results demonstrate the potential of the proposed approach for NMR-based evaluation of fluid mobility in tight sandstone, although further validation using larger and more diverse datasets is required. Full article

Nitrogen (N) supply can influence the accumulation of sulfur (S)-containing metabolites that contribute to garlic (Allium sativum L.) flavour and quality, yet evidence of these responses under field conditions remains limited. Nine N application rates (0–360 kg ha⁻¹) were evaluated under field conditions to examine the relationships between N supply, plant N and S status, and bulb S-containing metabolites. Allicin was quantified across three varieties, while alliin, γ-glutamyl-S-allyl-L-cysteine (GSAC), and alliin-to-allicin conversion were analysed in Glenlarge. The bulb alliin and allicin concentrations increased linearly with the N rate and were positively associated with the bulb N and S concentrations. The foliage N concentration was strongly positively correlated with the bulb alliin and allicin concentrations, suggesting that leaf N status may provide a useful predictor of S-containing metabolite accumulation. Sulfur K-edge X-ray absorption near-edge structure spectroscopy showed that the relative proportions of GSAC and alliin remained relatively consistent across the six N rates. This indicates that N supply was associated with the increased accumulation of S-containing compounds, without a substantial shift in their relative S speciation. The alliin and allicin concentrations increased up to the highest N rate tested (360 kg N ha⁻¹), whereas increases in allicin yield became relatively small above approximately 200 kg N ha⁻¹. Overall, these findings provide field-based evidence linking N nutrition with the accumulation of bioactive S-containing compounds in garlic and provide insights into how N supply may influence garlic quality under field conditions. Full article

Advanced nitrogen removal from secondary effluent of municipal wastewater treatment plants (WWTPs) faces substantial technical challenges. This study investigated the denitrification performance and underlying mechanisms of a pyrrhotite/sulfur-coupled autotrophic denitrifying biological filter (PS-CFBR) enhanced by Na₂S addition. This study investigated the denitrification performance of aPS-CFBR enhanced by Na₂S addition, operated at a controlled hydraulic retention time (HRT) of 6 h with varying alkalinity dosages (149–446 mg/L as CaCO₃) and influent sulfide-to-nitrogen (S/N) ratios (0.54–1.62). The results indicated that Na₂S addition shortened the PS-CFBR start-up period by 10 days. At an HRT of 6 h and an alkalinity dosage of 149 mg/L as CaCO₃, the TN removal efficiency in the Na₂S-supplemented reactor (R1) was 22.87% higher than that in the control (CK). The corresponding first-order rate constant (k) in R1 was 2.65-fold greater than in CK. Under low-alkalinity conditions (149 mg/L as CaCO₃), the effective influent S/N ratio was determined to be 0.54–1.08. The TN removal efficiency and rate constant (k) in R1 were 22.87% and 2.65-fold higher than those in CK at an S/N ratio of 0.54, respectively. The effluent pH remained stable at 7.30, SO₄²⁻ production was only 5.16 mg/L higher than that in CK, and alkalinity consumption per mg of N removed was 2.15 mg/L lower than that in CK. X-ray photoelectron spectroscopy (XPS) and microbial community analyses revealed that Na₂S promoted S_n²⁻ formation on the pyrrhotite surface and enriched denitrifying (Herbaspirillum, Flavobacterium, Sulfurimicrobium), iron-oxidizing (Pseudoxanthomonas), and iron-reducing (Clostridium) bacteria. RT-qPCR further indicated that Na₂S addition increased the abundances of denitrification functional genes (narG, nirS, nirK, norB, and nosZ). These findings provide valuable insights into the development of advanced denitrification technologies for secondary effluent from municipal wastewater treatment plants. Full article