Marina Vuković

This study evaluated the effects of thermocycling and staining on the optical behavior, chemical stability, and surface morphology of three commercial dental composites manufactured using different polymerization protocols: a light-cured composite (Omnichroma, OMNI) and two digital light-processed (DLP) 3D-printed composites intended for permanent (SprintRay CROWN, SPRINT) and temporary (GC Temp PRINT, TEMP) clinical applications. Disc-shaped specimens were subjected to thermocycling (0, 5000, 10,000, and 30,000 cycles) and immersion in coffee, Coca-Cola, or red wine for 1 and 7 days. Color change (ΔE₀₀) and translucency parameter (TP) were determined spectrophotometrically, while Fourier-transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were employed to assess the polymerization efficiency (expressed as the relative conversion index) and surface morphology, respectively. Thermocycling induced material-dependent changes in color stability and translucency. After 30,000 cycles, ΔE₀₀ values reached 2.77 ± 0.89 for OMNI, 0.74 ± 0.34 for SPRINT, and 3.30 ± 0.89 for TEMP. SPRINT maintained the highest TP values throughout the aging protocol, ranging from 26.09 ± 0.33 to 23.81 ± 1.93, whereas OMNI and TEMP exhibited lower TP values. The most favorable optical performance and the highest resistance to beverage-induced coloration were detected for SPRINT, whereas TEMP showed the greatest susceptibility to aging- and staining-induced optical degradation. Red wine and coffee produced substantially greater color changes and reductions in translucency than Coca-Cola. AFM analysis demonstrated progressive surface degradation and increased roughness following prolonged thermocycling, highlighting the significant influence of material composition and manufacturing protocol on the long-term optical stability of the investigated dental composites.

Graphical Abstract Overview of possible locations of microbiologically influenced corrosion in water utility systems: potable water systems, heating water systems, fire sprinkler systems, and wastewater systems. Illustration showing where microbiologically influenced corrosion may occur in water utility systems. Microbiologically influenced corrosion (MIC) is a persistent and often underrecognized challenge across water utility systems. This review presents an integrated cross-system assessment of MIC in potable water, heating water, fire sprinkler systems and wastewater infrastructure, drawing on knowledge from materials science, microbiology, corrosion engineering and operational practice. The analysis identifies shared corrosion drivers such as water stagnation, oxygen concentration gradients, heterogeneous biofilm development and the formation of protective or corrosive deposits, as well as system-specific vulnerabilities linked to design, operating conditions and material combinations. The review also highlights inconsistencies across existing standards and diagnostic practices, particularly regarding sampling, interpretation of microbial activity, and evaluation of material performance. A cross-system synthesis reveals recurring gaps in data accessibility, limitations of bulk water monitoring and the need for diagnostic approaches that integrate chemical, microbiological, and material evidence. Although emerging molecular techniques offer promising improvements, their use remains uneven across sectors. Key knowledge gaps are identified, and pathways are outlined for harmonized, sector-specific protocols that support more reliable detection, improved mitigation strategies and stronger alignment between scientific understanding and operational practice. The synthesis provides a foundation for future research, standard development and coordinated action to enhance the resilience and sustainability of water infrastructure.

This study comparatively evaluated the influence of processing routes on the optical stability of three dental resin composites: a light-cured direct composite—G-ænial A’CHORD (LCC), a CAD-CAM milled composite—BreCAM.HIPC (MC), and a 3D-printed composite—Saremco Print Crowntec (PC). Specimens were analyzed before (T0) and after hydrothermal aging for 5000 (T1), 10,000 (T2), and 30,000 cycles (T3). Optical stability was assessed through the change in color (ΔE₀₀) and translucency parameter (TP) after aging and immersion in beverages. Surface topography was evaluated using atomic force microscopy (AFM), while Raman spectroscopy was employed to detect aging-induced molecular changes. After aging and staining, all composites exceeded the acceptability threshold for color change. ΔE₀₀ values of 6.8 ± 1.1 (PC), 4.6 ± 0.9 (MC), and 2.1 ± 0.9 (LCC), obtained after initial aging, further increased following prolonged immersion in coffee. After 1 day of immersion in Coca-Cola, MC exhibited the highest ΔE₀₀ values, which slightly exceeded the clinically acceptable threshold. Prolonged immersion (7 days) significantly increased staining for all materials. TP values significantly differed among materials, with the highest values detected for LCC (20.6 ± 3.6) and PC (19.1 ± 1.5) and the lowest values detected for MC (4.9 ± 0.8). Overall, the results demonstrated that ΔE₀₀ was strongly influenced by the processing route and surface topography, whereas changes in translucency parameter (TP) were predominantly governed by the intrinsic properties of the resin composites.

Mechanically activated strontium titanate (SrTiO3) powders with various iron (III)oxide (Fe2O3) doping levels (1.5, 3, and 6 wt%) were prepared by solid state method. Due to the possibility of iron ion incorporation in SrTiO3 onto Sr2+ and/or Ti4+ sites a detailed analysis of the influence of dopants on the microstructure, morphology, optical properties and photocatalytic activity was conducted. The XRD analysis showed that iron was incorporated into the lattice of SrTiO3 particles. In the case of a lower concentration of dopant (1.5 wt%), there was a significant relative contribution of the substitution of Sr2+ ions by Fe3+ ions. In contrast, substituting Ti4+ ions with Fe3+ ions dominated samples with an increased concentration. Optical measurements indicated a shift of the absorption edge to higher values of wavelengths where the lowest value of the band gap (Eg=1.85 eV) was for the longest activation time (120 min) and the highest weight percentages of dopant (6 wt%). All samples have degraded tetracycline (TC) where degradation increases with longer irradiation time and dopant concentration. The highest degradation at 43 % was for 120 min activated sample with 6 wt% of Fe2O3.

Y_0.8−xGd_xF₃:Yb/Er mesocrystals with a biocompatible surface and diverse morphological characteristics were successfully synthesized using chitosan-assisted solvothermal processing. Their structural properties, studied using X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and energy dispersive X-ray analysis, were further correlated with the up-conversion emission (λ_exc = 976 nm) recorded in function of temperature. Based on the change in the visible green emissions originating from the thermally coupled ²H_11/2 and ⁴S_3/2 levels of Er³⁺, the corresponding LIR was acquired in the physiologically relevant range of temperatures (25–50 °C). The detected absolute sensitivity of about 0.0042 °C⁻¹, along with the low cytotoxicity toward both normal human lung fibroblasts (MRC-5) and cancerous lung epithelial (A549) cells, indicate a potential for use in temperature sensing in biomedicine. Additionally, their enhanced internalization in cells, without suppression of cell viability, enabled in vitro labeling of cancer and healthy cells upon 976 nm laser irradiation.

Hydroxyapatite attracts great attention as hard tissues implant material for bones and teeth. Its application in reconstructive medicine depends on its biocompatibility, which is in a function of composition and surface properties. The insertion of a protein element in the composition of implants can improve the cell adhesion and the osseointegration. Having this in mind, the proposal of this work was to develop L-alanine-grafted hydroxyapatite nanoparticles and to study their biocompatibility. Two L-alanine sources and three grafting methods were used for hydroxyapatite surface functionalization. The efficiency of grafting was determined based on X-ray powder diffraction, Fourier-transform infrared spectroscopy, thermal analyses, and field-emission scanning electron microscopy. The results indicated the formation of hydroxyapatite with 8–25 wt% of organic content, depending on the grafting method. Protein adsorption, cell adhesion, and viability studies were carried out to evaluate biological properties of grafted materials. The viability of MG-63 human osteoblastic cells following 24 h incubation with the alanine-grafted hydroxyapatite samples is well preserved, being in all cases above the viability of cells incubated with hydroxyapatite. The alanine-grafted hydroxyapatite prepared in situ and by simple mixture showed higher protein adsorption and cell adhesion, respectively, indicating their potential toward use in regenerative medicine.

The synthesis of lanthanide doped up-converting nanoparticles (UCNPs), whose morphological, structural, and luminescence properties are well suited for applications in optoelectronics, forensics, security, or biomedicine, is of tremendous significance. The most commonly used synthesis method comprises decomposition of organometallic compounds in an oxygen-free environment and subsequent infliction of a biocompatible layer on the particle surface. In this work, hydroxyl–carboxyl (—OH/—COOH) type of chelating agents (citric acid and sodium citrate) are used in situ for the solvothermal synthesis of hydrophilic NaY_0.5Gd_0.3F₄:Yb,Er UCNPs from rare earth nitrate salts and different fluoride sources (NaF, NH₄F, and NH₄HF₂). X-ray powder diffraction showed crystallization of cubic and hexagonal NaY_0.5Gd_0.3F₄:Yb,Er phases in nano- and micro-sized particles, respectively. The content of the hexagonal phase prevails in the samples obtained when Na-citrate is used, while the size and shape of the synthesized mesocrystals are affected by the choice of fluoride source used for precipitation. All particles are functionalized with citrate ligands and emit intense green light at 519 nm and 539 nm (²H_11/2, ⁴S_3/2 → ⁴I_15/2) under near infrared light. The intensity of this emission is distressed by the change in the origin of phonon energy of the host matrix revealed by the change in the number of the excitation photons absorbed per emitted photon.

Macroporous silica ceramic was obtained using clay and diatomite. Boric acid as a low-cost additive in the amount of 1 wt% was used. These porous materials were obtained at low forming pressure (40-80 MPa) and lower sintering temperature (850-1300 ?C) for 4h in air. The influence of boric acid, forming pressure, and sintering temperature on the microstructure, porosity parameters, and mechanical properties of obtained porous monoliths were investigated. As-received and the modified samples were characterized by X-ray diffraction, FTIR, SEM, and mercury porosimetry measurements. As for modified clay and diatomite, they were pressed at 60 MPa and then sintered at 1150 ?C, obtaining porosities of about 10 % and 60 %, respectively. Both of the analyzed samples had the pore diameter in the range of macroporous materials. The pore diameters of clay samples are ranging from 0.1-10 ?m, whereas the pore diameter of diatomite samples was slightly lower with values ranging from 0.05-5 ?m. Modified diatomite samples have a lower Young modulus in comparison to modified clay samples.

Single phase β‐NaY _{0.8‐ x} Gd _x Yb _0.18 Er _0.02 F ₄ nanoparticles with different concentrations of gadolinium ions were prepared via PVP‐assisted solvothermal treating at 200°C (PVP‐ polyvinylpyrrolidone). With the increase in Gd ³⁺ concentration, size of the nanoparticles decreased. The up‐converting spectra recorded upon 980 nm irradiation showed the green (510‐560 nm) and red (640‐690 nm) emissions, due to ² H _11/2 , ⁴ S _3/2 → ⁴ I _15/2 and ⁴ F _9/2 → ⁴ I _15/2 transitions, respectively. The strongest up‐conversion luminescence was detected in 15 mol% Gd ³⁺ ‐doped nanoparticles obtained after 20 hours of solvothermal treating. With the rise of Gd ³⁺ content up‐conversion emission decreased due to increased defect concentration in the NaYF ₄ matrix. Fourier transform infrared spectroscopy proved in situ generation of hydrophilic nanoparticles as a result of PVP ligands retention at the particle surface.

Co-Mo carbides were prepared by impregnation with aqueous solution of metal salts and sucrose into ordered mesoporous SBA-15 silica template using carbothermal hydrogen reduction. Bimetallic Co-Mo carbide obtained by using carbothermal hydrogen reduction of Co-Mo precursors is formed when the Co-Mo molar ratio is 1.0. The obtained samples were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Electrochemical characterization of obtained materials w?re performed by cyclic voltammetry in acid solution.