Search Results (1,446)

Dental restorative resins available today still have limitations that may affect their durability. This study explores reinforcing a universal microhybrid dental composite resin with organomodified nanoclay at low filler loadings (0, 0.5, 1, 3, and 5 wt%). The morphology, structural features, and light transmittance of the composites were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), attenuated total reflection–Fourier transform infrared (ATR–FTIR), and UV–Vis spectroscopy. The degree of conversion and polymerization shrinkage were measured with ATR–FTIR and a linear variable displacement transducer (LVDT). Water sorption and solubility parameters and flexural properties were assessed gravimetrically and with a dynamometer, respectively. The composites mainly showed exfoliated structures and an improved degree of conversion. Polymerization shrinkage and solubility were lower than those of unmodified dental resin. The highest degree of conversion was observed in composites with 0.5–1 wt% nanoclay. The incorporation of 1 wt% nanoclay resulted in the lowest shrinkage and sorption, along with the highest flexural modulus and strength. Overall, the results suggest that low nanoclay concentrations can improve the physicochemical and mechanical properties of dental composites, highlighting their potential to develop advanced restorative materials that can address current clinical challenges. Full article

MXenes, with a high surface area, abundant active sites, and excellent ion transport properties, have demonstrated excellent electrochemical performance. However, systematic comparisons of the structural evolution process and electrochemical performance for MXene are lacking. In this study, multilayer MXene (M-Ti₃C₂T_x) was successfully fabricated by in situ etching. During the subsequent centrifugation process, the thicker and heavier multilayer sheets settled due to their faster sedimentation rate, while the lighter, surface-functionalized monolayer sheets remained colloidally stable in the supernatant due to solvation and electrostatic repulsion, thereby achieving separation and obtaining delaminated MXene (D-Ti₃C₂T_x). Structural analysis indicates that the removal of the aluminum layer synergizes with the exfoliation of the nanosheets, significantly increasing the interlayer spacing and making the sheet structure more pronounced, and the pore structure is more abundant. Especially, in three-electrode and two-electrode systems at an identical mass loading of 5 mg on carbon paper, D-Ti₃C₂T_x delivered a higher specific capacitance, more pronounced pseudocapacitive behavior, and a superior rate capability compared to Ti₃AlC₂ and M-Ti₃C₂T_x. Such excellent electrochemical performance of D-Ti₃C₂T_x is due to the shortened ion diffusion path in the delaminated structure, which enables rapid ion migration, an extremely large specific surface area, and a mesoporous structure that provides abundant active sites. This study underscores the significant potential of D-Ti₃C₂T_x in emerging energy storage systems and offers insights into guiding MAX phase synthesis during its preparation. Full article

Polyethylene terephthalate is a prominent polymer known for its mechanical properties, chemical resistance, and recyclability, and it is widely utilized across various industries. Enhancing the properties of polyethylene terephthalate (PET) through nanocomposite technology, particularly with the inclusion of nanoscale fillers, has garnered significant attention. This study investigates synthetic layered double hydroxides (LDHs), specifically MgAl LDH modified with calcium dodecylbenzene sulphonate in n-butyl alcohol (CDS) organic surfactant, as an alternative to natural clays for PET nanocomposites. Additionally, modified LDH serves a dual role as both a catalyst and a dispersive agent, promoting effective exfoliation within the PET matrix. A polymerization process was employed to ensure proportional and effective dispersion of the nanofillers, addressing the critical challenge of achieving uniform distribution. The resulting nanocomposites demonstrated superior mechanical strength, thermal stability, and barrier properties compared to traditional intercalated counterparts. Moreover, synthetic LDHs present a more sustainable solution, reducing the environmental footprint associated with natural clay mining, which includes land degradation, water pollution, energy consumption, and biodiversity loss. This research provides a promising pathway for developing high-performance, environmentally friendly PET nanocomposites, with significant implications for various industrial applications, from packaging to automotive and electronics. The findings highlight the potential of synthetic LDHs to advance material science while aligning sustainable development goals. Full article

The high-temperature corrosion behavior of A1, T22, and T91 steels was investigated in molten nitrate salts at 400, 500, and 600 °C during 100 h of exposure. The combined influence of temperature and chromium content on corrosion kinetics and oxide-scale stability was evaluated using open-circuit potential (OCP), linear polarization resistance (Rp), electrochemical impedance spectroscopy (EIS), scanning electron microscopy, X-ray diffraction, and cross-sectional elemental mapping. OCP measurements showed a progressive shift toward more negative potential with increasing temperature, indicating enhanced oxidation tendency. Electrochemical measurements revealed a systematic decrease in Rp and impedance magnitude as temperature increased, confirming accelerated corrosion kinetics and reduced interfacial resistance. EIS spectra exhibited two characteristic time constants associated with the outer corrosion products and the inner metal/oxide interface. Significant differences in scale growth were observed depending on alloy composition. At 600 °C, oxide thickness reached approximately 700–800 μm for A1, ~100 μm for T22, and ~10 μm for T91. Chromium-containing steels promoted the formation of a compact Cr-rich inner oxide layer that improved scale adhesion and suppressed the exfoliation phenomena observed in A1 steel. Overall, temperature controls corrosion kinetics, whereas chromium content governs oxide-scale compactness and long-term stability in molten nitrate environments. Full article

Succinic acid (SA) is a naturally occurring dicarboxylic acid with diverse biological roles, including participation in cellular energy metabolism and signaling. Despite its wide industrial use, clinical and in vivo evidence supporting the application of SA in cosmetics, cosmetology, dermatology, and aesthetic medicine remains limited, although mechanistic and experimental studies describing its biological activity are increasingly available. This review summarizes the chemical properties, natural occurrence, and physiological functions of SA, with a focus on its potential in topical and intradermal applications. The use of SA in cosmetic formulations, including personal care products, moisturizers, and masks, is discussed, alongside its emerging roles in the management of acne vulgaris and rosacea, hyperpigmentation, and as a chemical exfoliant and biostimulatory agent. Available studies suggest that SA can modulate inflammation, enhance microcirculation, support fibroblast proliferation, and stimulate collagen and elastin production, although most clinical evidence derives from small-scale or preliminary studies. Looking forward, the growing market and increasing scientific interest indicate a potential expansion of SA-based products in aesthetic dermatology. Further clinical and mechanistic studies are required to validate its applications and establish standardized protocols for its use in cosmetic and medical settings. The aim of this article is to summarize the existing knowledge on the use of succinic acid in cosmetics and aesthetic dermatology. Despite the growing interest in this compound, no comprehensive review addressing its applications in these fields is currently available. Therefore, this work responds to this gap by integrating and discussing the limited but emerging scientific reports concerning the cosmetic and dermatological potential of succinic acid. Full article

Glycolic acid (GA), a widely used alpha-hydroxy acid in cosmetic formulations, promotes exfoliation and stimulates fibroblasts in the dermis to synthesize collagen. However, its hydrophilic nature limits penetration through the stratum corneum, reducing its overall efficacy. This study aimed to develop and optimize an ethanol-based niosomal system to enhance GA skin delivery and formulation stability for cosmetic applications. Brij 97 combined with cholesterol at a 1:1 ratio and 10% ethanol produced the optimal formulation. Blank vesicles exhibited a mean vesicle size of 170.53 ± 5.05 nm and a zeta potential of −37.77 ± 2.21 mV, indicating favorable colloidal stability. Incorporation of 10% GA resulted in vesicles with a mean size of 176.93 ± 1.51 nm, a polydispersity index of 0.12 ± 0.02, and an entrapment efficiency of 75.48 ± 0.21%. In vitro permeation studies using Strat-M^® membranes demonstrated significantly higher cumulative skin penetration (49.56 ± 8.95 mg/cm²) and sustained release over 24 h compared with a conventional GA solution. Stability testing under heating–cooling cycles and storage at 4 °C showed slight increases in vesicle size while maintaining homogeneity (polydispersity index (PDI) < 0.3). These findings highlight ethanol-based niosomes as an effective strategy for enhancing GA cosmetic performance. Full article

The ability to efficiently tailor the surface properties of layered transition metal dichalcogenide (LTMD) dispersions is critical for optimizing performance and enabling scalable manufacturing techniques, such as spray coating and inkjet printing, for optoelectronic, energy storage, and sensing applications. Group VI LTMDs, owing to their unique properties in the monolayer architecture, offer exceptional potential; however, the properties of exfoliated dispersions are strongly dependent on the specific solution-processing techniques employed. These techniques determine the choice of subsequent surface functionalization strategies and, consequently, the characteristics of the resulting functionalized hybrids. Furthermore, the inherent heterogeneity of solution-processed dispersions—manifested, among other factors, in broad distributions of flake thickness and lateral size—remains a significant challenge and strongly influences the behavior of hybridized materials. As a result, exfoliation-method-dependent properties and dispersion heterogeneity introduce substantial complexity in the selection of appropriate surface-tailoring strategies, characterization methodologies, and data interpretation. To address these challenges, we systematically classify exfoliated Group VI LTMD dispersions according to their exfoliation methods and highlight recent findings that challenge previously accepted assumptions in the field. Finally, we provide perspectives on surface functionalization approaches for Group VI LTMDs and discuss key limitations associated with the characterization of these newly hybridized materials. Full article

With the opening of complex service routes, the importance of the service performance of brake pads under long slope braking conditions is increasing. It is necessary to analyze the slope braking adaptability of current brake pad products. This work takes the copper-based powder metallurgy brake pads of a certain in-service high-speed train as the research object and conducts friction and wear behavior tests of the brake pads based on a full-scale brake test bench. Through microscopic observation and damage analysis, the differences in friction and wear behavior of the brake pads under stop braking and slope braking conditions are compared, revealing the wear mechanism and damage evolution characteristics of the brake pads. The results show that under the impact of high speed, high braking force, and severe thermal load in the stop braking conditions, the uneven wear of brake pads is high, and the eccentric wear of friction blocks is affected by both the friction radius and friction direction. The friction surface has a large number and size of damages, and the stability of the friction interface is poor. The brake pad exhibits a composite wear mechanism dominated by abrasive wear and brittle fracture induced exfoliation. In the slope braking condition, under the action of low speed, low braking force, and long-term stable thermal load, the uneven wear of the brake pads is relatively low, the surface damage size is small, and the friction block only has eccentric wear along the friction direction. The brake pad mainly initiates cracks along the interface of the components, which propagate parallel to the friction surface, exhibiting a progressive delamination and flaking exfoliation mechanism with a low wear rate. Although the friction interface of the brake pad is relatively stable under slope braking conditions, the cumulative delamination wear of the brake pads under long-term braking action needs further attention. Full article

This study aimed to develop new catalysts, based on MoS₂, for the hydrogenation of bromoquinolines without C-Br bond cleavage. The mechanochemical exfoliation of the bulk MoS₂ in the presence of NaCl resulted in the formation of the material (MoS₂-1), consisting of flat plates of size between ca. 40 × 100 and ca. 250 × 400 nm². Similar grinding of MoS₂ in the presence of NH₄Cl produced smaller nanoplates of size between ca. 10 × 30 and ca. 50 × 300 nm² (MoS₂-2). These materials were characterized using powder XRD, TEM, SEM, Raman spectroscopy and XPS. The specific surface area of the MoS₂-1 and MoS₂-2 samples was estimated using the analysis of N₂ adsorption isotherms. Both materials were catalytically active in the hydrogenation of quinoline; 1,2,3,4-tetrahydroquinoline (THQ) was the sole product and its yield grew proportionally to the accessible surface area of the catalyst. The hydrogenation of 5- and 8-bromoquinolines in the presence of MoS₂-1 and MoS₂-2 led to the respective bromo-THQs with almost quantitative yields, while the hydrogenation of 6-bromoquinoline resulted in the formation of the respective 6-bromo-THQ with the yield up to 30%. In the case of 7-bromoquinoline, N-methylated 7-bromo-THQ was formed almost quantitatively. Full article

Background: Exfoliation syndrome (XFS) is a common age-related disorder and a major risk factor for glaucoma and cataract. This study describes the hospital-based frequency and clinical associations of XFS among patients aged 40 years and older attending a regional ophthalmology outpatient clinic in the Northeastern Black Sea coastal region of Turkey. Methods: This cross-sectional observational study included 938 eligible participants aged ≥40 years with registered birth records and continuous residence within the defined catchment area who underwent a comprehensive ophthalmological examination. XFS was defined by characteristic exfoliative material at the pupillary margin and/or on the anterior lens capsule (phakic eyes) or capsular bag/IOL complex (pseudophakic eyes), with pupillary assessment before and after pharmacologic dilation. Systemic comorbidities were extracted from national medical records. Multivariable logistic regression adjusted for age and gender. Results: XFS was diagnosed in 20.8% (195/938; 95% CI: 18.2–23.5%). The XFS-positive (XFS+) group was older than the XFS-negative (XFS−) group (71.76 ± 0.61 vs. 63.25 ± 0.40 years; p < 0.001). Hypertension was more common in XFS+ participants (57.4% vs. 45.6%; p: 0.002) and remained associated after adjustment (OR: 1.49; 95% CI: 1.05–2.11; p: 0.024). Glaucoma was more frequent in XFS+ participants (23.6% vs. 14.9%; p: 0.005); it remained associated after adjustment (OR: 2.00; CI: 1.31–3.05; p: 0.001). Conclusions: In this hospital-based surveillance, approximately one in five clinic attendees aged ≥40 years had XFS. Findings should not be extrapolated to population prevalence; population-based studies are required to estimate regional prevalence accurately. Nonetheless, these data highlight a substantial clinical burden of XFS in a regional care-seeking population and support vigilant glaucoma surveillance in affected patients. Full article

Polyester resin composites containing expanded graphite often exhibit reduced mechanical strength due to the porous structure of the filler. The aim of this study was to enhance mechanical performance without compromising electrical behaviour. Although carbon fibre and expanded graphite are chemically identical carbon allotropes, their distinct morphologies motivated the use of carbon fibre to reinforce expanded graphite-filled polyester composites. To examine the role of expanded graphite porosity, ultrasonicated EG was used to produce exfoliated, lower-porosity particles, while vacuum processing was applied to remove entrapped air prior to curing. Adding 0.5–5 wt% milled carbon fibre increased electrical conductivity by up to three orders of magnitude relative to neat polyester while maintaining 70–80% of the original specific strength at moderate fibre contents. Ultrasonicated EG reduced tensile strength by more than 50% at 5 wt% loading and decreased conductivity due to additional grain boundary formation. Vacuum-processed EG not only provided slight mechanical enhancements but also significantly improved electrical properties by lowering surface resistance by 6–10 orders of magnitude, reaching the tens-of-Ω range at 3–5 wt% EG. This performance is comparable to previously reported conductive EG/polymer systems, which exhibit surface resistances of 10–10² Ω at 5 wt% EG. This systematic comparison offers practical guidelines for balancing conductive percolation and mechanical reinforcement in expanded graphite polyester composites. Full article

Icing poses significant operational and safety risks in aviation, especially for engine components such as cowls and baffles. This study explores the potential of a chemically exfoliated graphene-rich carbon platelet epoxy coating to improve the anti-icing and de-icing performance of 3003-H14 aluminum alloy, which is widely used in such applications. Chemically exfoliated graphite was incorporated into an epoxy resin, then applied to aluminum substrates. Characterization of the coated samples revealed ~30% improvement in surface Vickers hardness (HV) (HV 75.6 ± 1.15 vs. HV average of 98.3 ± 1.5) and enhanced thermal dissipation, with coated surfaces cooling from 104 °C to 22 °C in 530 s compared to 870 s for uncoated samples. While anti-icing performance was not directly evaluated, the observed improvements in thermal dissipation and surface hardness suggest that chemically exfoliated graphene-rich carbon platelet coatings could be promising for passive anti-icing applications. The literature suggests that graphene coating improves hydrophobicity, reducing ice adhesion and delaying nucleation due to its low surface energy and nanoscale roughness, thereby supporting potential passive anti-icing functionality for aircraft engine components. SEM analysis confirmed a uniform, compact coating layer. These preliminary findings indicate that chemically exfoliated graphene-rich carbon platelet coatings can deliver multifunctional performance—mechanical, thermal, and surface—making them promising candidates for passive anti-icing/de-icing solutions in engine components where conventional systems are ineffective. Full article

Stem cell heterogeneity represents a critical yet underexplored variable in laser-assisted regenerative strategies. While photobiomodulation has been shown to influence mesenchymal stem cell (MSC) behavior, it remains unclear whether stem cell maturation status modulates responsiveness to Er,Cr:YSGG irradiation. This study investigated the differential response of magnetically separated STRO-1⁺ and STRO-1⁻ SHED subpopulations to low-power Er,Cr:YSGG laser stimulation (0.10 W and 0.25 W), focusing on viability, extracellular matrix production, and lineage commitment. STRO-1⁺ cells comprised 13.4% ± 1.2% of the total Stem Cells from Human Exfoliated Deciduous teeth (SHED) population. Laser exposure did not impair metabolic activity in either subpopulation. Collagen synthesis demonstrated a power- and time-dependent increase, with maximal enhancement observed in STRO-1⁺ cells at 0.25 W after 7 days. Laser irradiation selectively promoted osteogenic differentiation, as evidenced by increased alkaline phosphatase (ALP) expression at 0.10 W and enhanced mineral deposition, while chondrogenic potential remained unaffected and adipogenesis was reduced following 0.10 W exposure. These findings suggest that ALP expression is temporally and power-dependently modulated during osteogenic progression. Overall, Er,Cr:YSGG photobiomodulation does not uniformly affect heterogeneous SHED populations but modulates lineage allocation and extracellular matrix deposition in a maturation- and power-dependent manner. Integrating stem cell subpopulation selection with laser-based bioactivation may represent a strategy to refine regenerative endodontic and biomaterial-guided therapies. Full article

Intergranular corrosion (IGC) and exfoliation corrosion (EXCO) limit the durability of 2219 Al–Cu in chloride-rich, cyclic-humidity aerospace environments, and conventional thermal stress relief can worsen grain boundary precipitates and grain boundary non-precipitation zones (PFZs), motivating evaluation of low-temperature resonant vibration stress relief. Using polarization tests and microstructural analysis, we show that RRV lowers corrosion current, strengthens passivation, and reduces IGC and EXCO susceptibility. Alternating tensile–compressive stresses build dislocation networks that convert continuous or semi-continuous grain boundary precipitates into discrete distributions, increasing corrosion path tortuosity and slowing intergranular attack. A more discrete cathodic phase, a narrowed solute-enriched anodic band, and reduced PFZs disrupt corrosion channel continuity, weaken microgalvanic driving forces via a more uniform θ′ distribution, and limit corrosion product wedging, while homogenized precipitates suppress local galvanic coupling in EXCO-like media. Overall, RRV synergistically optimizes dislocation configuration and precipitate redistribution to intrinsically enhance corrosion resistance and offers a practical, low-temperature, scalable route to improve the durability of high-strength aluminum alloy structures in aerospace service. Full article