Search Results (428)

Developing efficient and eco-friendly catalysts for peroxymonosulfate (PMS) activation to degrade persistent antibiotics in water remains a major challenge. Herein, acid-base etched montmorillonite is employed to activate PMS for sulfamethoxazole (SMX) degradation under neutral to weakly alkaline conditions. Compared with pristine montmorillonite and acid-etched montmorillonite (A-Mon), base-etched montmorillonite (B-Mon) achieves the highest removal efficiency, eliminating 92% of SMX within 120 min. The degradation rate constant of the B-Mon/PMS system is 0.19 min⁻¹, which is 2.7 times that of the pristine montmorillonite/PMS system. Reactive species analysis reveals that the B-Mon/PMS system increases the singlet oxygen (¹O₂) concentration by 10.3-fold compared to PMS alone. Electron spin resonance (ESR), temperature-programmed desorption (TPD), and quenching experiments demonstrate that medium-weak Lewis basic sites on the B-Mon surface play a pivotal role in PMS activation and SMX degradation. Moreover, these medium-weak Lewis basic sites facilitate ¹O₂ generation via the self-decomposition mechanism of PMS. Stability tests confirm that B-Mon exhibits excellent cycling stability and anti-interference capability. This work provides a deeper mechanistic insight into the development of environmentally friendly aluminum-based catalysts for practical remediation of complex water. Full article

Background: Bonding to sclerotic dentin remains one of the most challenging procedures in restorative dentistry due to tubular occlusion and hypermineralization, which limit resin infiltration. This study evaluated the influence of adhesive system, surface treatment, storage time, and substrate position on microtensile bond strength (µTBS) to natural sclerotic dentin. Methods: Sixteen extracted human molars with sclerotic dentin were selected and randomly assigned to nine experimental groups according to the adhesive system and surface treatment. Three adhesives were tested: a two-step self-etch adhesive (Clearfil SE Bond 2, Kuraray Noritake Dental, Tokyo, Japan) and two universal adhesives, one containing 10-MDP (G-Premio Bond, GC Corp., Tokyo, Japan) and one without 10-MDP (iBond Universal, Kulzer GmbH, Hanau, Germany). Each adhesive was applied under three conditions: no pretreatment (control), Al₂O₃ air-abrasion, and Bioglass 45S5 (ProSylc^®, Velopex International, London, UK) air-abrasion. Composite build-ups were performed, and the specimens were sectioned into 1 mm² beams for microtensile testing either after 24 h or after 6 months of storage in distilled water at 37 °C of hypertonic solution. The effect of beam position (central vs. peripheral) was also analyzed. Bond strength was measured by µTBS testing, and the results were analyzed using multifactorial ANOVA and Tukey’s test (α = 0.05). Failure modes were examined under stereomicroscopy, whereas optical microscopy was used for qualitative evaluation of representative fractured interfaces. Results: Significant main effects were found for adhesive system and surface treatment (p < 0.001), with a notable interaction between them (p < 0.05). Al₂O₃ air-abrasion produced the highest bond strengths, particularly for the self-etch adhesive containing functional monomers (53.4 ± 6.1 MPa), representing a 53% increase over the untreated control. Bioglass air-abrasion did not enhance adhesion and led to irregular hybrid layers. The position of the beams affected only one universal adhesive, with higher µTBS in peripheral regions. After six months of water storage, bond strengths remained stable across most groups, indicating good hydrolytic resistance of the interfaces. Conclusions: Both the adhesive system and the surface treatment significantly influenced bonding effectiveness to sclerotic dentin. The combination of Al₂O₃ air-abrasion with an MDP-containing self-etch adhesive achieved the most durable and homogeneous bond interface. providing a clinically reliable protocol for restorative treatments in sclerotic dentin. Within the limitations of this in vitro study, this combination may represent a potentially useful strategy for improving adhesion to sclerotic dentin, although further investigations are required to confirm its clinical applicability. Full article

Three-dimensional (3D) graphene foams are attractive as lightweight conductive scaffolds with large surface area and broadband light absorption but achieving reproducible porosity and preserving the architecture after metal-template removal remain challenging. Here we report a stepwise route to freestanding 3D multilayer graphene foams based on (i) hydrogen-bubble-assisted electrodeposition of porous Ni on Cu foils, (ii) time-controlled pre-annealing at 1000 °C to drive Cu diffusion and form porous Ni-Cu alloy templates, (iii) in situ graphene CVD at 1000 °C under fixed growth conditions, and (iv) wet etching to remove the metal scaffold without a polymer support. The influence of pre-annealing (0, 1, 3, and 7 h) on template evolution, graphene growth, and foam stability was systematically investigated via SEM, EDS, XRD and Raman studies. Before etching, Raman spectroscopy indicates low-defect graphenic coatings with locally heterogeneous few-layer-like to multilayer-like signatures. Only samples pre-annealed for at least 3 h preserved the porous 3D architecture after metal removal, indicating the formation of self-supporting graphenic networks with improved post-etch morphological stability. Raman and XRD analyses further revealed a progressive reduction in structural degradation, residual strain, and stacking disorder with increasing pre-annealing time. Among the investigated samples, the foams obtained after 3 and 7 h of template pre-annealing combined preserved 3D morphology with low sheet resistance (10–20 Ω/□), negligible optical transmittance (<5%), and strong broadband visible-light absorption (75–90%). Full article

Evaluating the shear bond strength (SBS) of contemporary universal adhesive systems on different substrates is critical for understanding their clinical applicability. In this study, the SBS of universal adhesives was assessed on 144 human and bovine tooth specimens, comparing enamel and dentin across etch-and-rinse and self-etch protocols. Following single-step or two-step adhesive application and resin cementation, the specimens were subjected to 5000 thermocycles before being evaluated with a universal testing machine. Failure modes and surface morphology were additionally characterized using stereomicroscopy and scanning electron microscopy (SEM). Statistical analyses revealed that both tissue type (p = 0.043) and tooth type (p < 0.001) significantly influenced SBS, while the main effect of the adhesive protocol was not significant (p = 0.485). A significant interaction occurred between tissue type and adhesive protocol (p = 0.013); Post hoc analyses revealed that Group A enamel had significantly higher bond strength than both Group D enamel (p = 0.026) and Group A dentin (p = 0.001). Observed failures were predominantly adhesive or mixed, and SEM confirmed expected acid-induced surface roughness. Human teeth yielded higher bond strengths than bovine teeth, meaning absolute SBS values from bovine lab studies should be used with caution. Full article

Chlorhexidine (CHX) has been widely reported as an inhibitor of matrix metalloproteinases (MMPs), contributing to the preservation of dentin bond integrity, while chitosan (CS) has been proposed as a natural biomodifier with potential collagen-stabilizing and cross-linking effects on the dentin matrix. These properties make both agents relevant candidates for improving the durability of adhesive interfaces. This in vitro study evaluated the effect of CS- and CHX-containing cavity disinfectants on the microtensile bond strength (µTBS) of a two-step self-etch adhesive applied to superficial and deep dentin. Forty-eight sound human molars were randomly assigned to superficial and deep dentin groups, which were further subdivided according to surface treatment: control (no treatment), 2% CHX, and 2.5% CS. A two-step self-etch adhesive system (Clearfil SE Bond) and resin composite were applied according to the manufacturers’ instructions. After storage and thermocycling, beam-shaped specimens were prepared and subjected to µTBS testing. Data were analyzed using appropriate statistical methods, and significance was set at p < 0.05. CS pretreatment resulted in higher µTBS values compared with the control group in both superficial and deep dentin, with statistically significant differences observed (p < 0.05), while CHX-treated groups showed intermediate values, with no consistent statistically significant difference compared with CS. In general, superficial dentin exhibited higher bond strength values than deep dentin (p < 0.05). Within the limitations of this in vitro study, chitosan-containing cavity disinfectant was associated with significantly higher µTBS values compared with the untreated control in both superficial and deep dentin when used with a two-step self-etch adhesive. However, these findings should be interpreted with caution and should not be generalized beyond the specific materials and experimental conditions evaluated. Full article

The objective of this study was to evaluate the antioxidant and antibacterial profiles of Picea orientalis (Oriental spruce) resin extracts collected from three distinct geographical sites (Artvin, Borçka, and Çaykara) within the Eastern Black Sea region of Türkiye. Additionally, it aimed to assess the viability of these extracts as natural antibacterial agents against cariogenic pathogens and to determine their subsequent effect on dental bond strength performance. Quantitative phytochemical analysis of the ethanolic extracts included the determination of total phenolic content, coupled with individual phenolic profiling by HPLC-PDA. The antioxidant potential was assessed through DPPH and FRAP assays. Additionally, the antibacterial activity against a panel of oral and systemic pathogens was evaluated using agar well diffusion. Furthermore, to evaluate mechanical performance, composite bond strengths were tested on 180 dentin specimens using both self-etch and etch-and-rinse adhesive strategies, following cavity pre-treatment with a control, chlorhexidine, or the resin extracts. The results revealed that the resin from the Artvin region exhibited the highest phenolic content, characterized by an abundance of trans-cinnamic, caffeic, and ferulic acids, which correlated with their superior antioxidant capacity. Furthermore, while the extracts demonstrated potent inhibitory effects against Staphylococcus aureus, their antibacterial activity against Streptococcus mutans was found to be comparatively moderate. In bond strength evaluations, the non-aged control group exhibited the highest values (p = 0.000); however, no statistically significant difference was observed between the chlorhexidine and resin extract groups (p > 0.05). Consequently, the phenolic-rich P. orientalis resin represents a promising natural antibacterial alternative for dental applications. Full article

Because superficial and deep dentin differ in their structural characteristics and bonding behavior, optimizing adhesive strategies for both substrates is clinically important. The aim of this in vitro study was to evaluate the effects of different application strategies of a universal adhesive system and single-shade resin composites on the micro-shear bond strength (μSBS) to superficial and deep dentin. A total of 240 extracted human third molars were prepared to obtain superficial or deep dentin specimens. A universal adhesive system (Gluma Bond Universal) was applied using etch-and-rinse (E&R), self-etch (SE), and selective dentin etch (SDE) strategies. Four commercially available single-shade resin composites (Omnichroma, Zenchroma, Charisma Diamond One, and Vittra APS Unique) were evaluated. After 24 h of water storage, μSBS was evaluated and failure modes were analyzed. Dentin depth, adhesive strategy, and composite type significantly affected μSBS values (p < 0.05). Superficial dentin exhibited significantly higher bond strength than deep dentin (p < 0.001). The effect of adhesive strategy depended on dentin depth; in deep dentin, SDE provided significantly higher bond strength than both E&R and SE applications (p < 0.001). Significant interactions were observed among dentin depth, adhesive strategy, and composite type (p < 0.05). The predominant mode of failure across most experimental groups was adhesive failure. Within the limitations of this in vitro study, dentin depth, adhesive strategy, and single-shade composite type significantly influenced dentin bond strength. Selective dentin etching was associated with increased bond strength in deep dentin under the experimental conditions of this study. Full article

Fracturing is the dominant stimulation technique for low-porosity, low-permeability dolomite gas reservoirs, yet the lack of systematic laboratory research on multistage alternating acid etching mechanisms restricts field construction parameter optimization. Targeting the low-permeability Xixiangchi Formation dolomite reservoir in the eastern Sichuan Basin, this work develops a high-temperature, high-pressure core acid etching system coupled with 3D surface scanning. A reliable lab-to-field parameter conversion is established based on the Reynolds and Froude similarity criteria. Four-factor three-level orthogonal tests are conducted to quantify the impacts of pad fluid-to-acid viscosity ratio, total acid volume, pumping rate, and alternating injection stages on JRC-characterized wall roughness and fracture conductivity. The results show an identical factor dominance ranking for both indicators: viscosity ratio > pumping rate > injection stages > total acid volume. The optimal stimulation scheme is determined as a 50:1 viscosity ratio, 120 mL total acid volume, 12.54 mL/min laboratory pumping rate (equivalent to 8 m³/min in field operations), and 3 alternating injection stages. An elevated viscosity ratio intensifies viscous fingering, induces heterogeneous dolomite dissolution, and forms abundant irregular asperities on fracture surfaces. These self-supporting rough structures sustain stable seepage channels and markedly improve conductivity, verifying the positive roughness-conductivity correlation and revealing the core mechanism of heterogeneous etching-driven conductivity enhancement. The findings provide direct experimental support and parameter guidance for multistage alternating acid fracturing design in the Xixiangchi Formation and analogous tight dolomite reservoirs. Full article

Cementation of indirect restorations has undergone a profound change over the past century, evolving from a philosophy of purely mechanical cementation to sophisticated biomaterials science based on adhesion. The aim of this narrative review is to provide essential context for understanding contemporary clinical decision-making. A key aspect is the structural and compositional characteristics of enamel and dentin as bonding substrates, underlining why enamel remains the gold standard, while dentin continues to present significant challenges. The synthesis is based on evidence of adhesive strategies for the four main classes of contemporary restorative materials, such as glass-ceramics (lithium disilicate and leucite), polycrystalline zirconia, resin-matrix ceramics (hybrid ceramics), and indirect composites. Each material was detailed in terms of surface penetration (e.g., hydrofluoric acid etching and air abrasion), chemical coupling (e.g., silanization and MDP-based primers), and appropriate resin cement selection (light-cured, dual-cured, or self-adhesive). A step-by-step clinical protocol is synthesized based on current evidence, integrating critical techniques such as immediate dentin sealing and optimized polymerization. This review concludes that while adhesive resin cements provide predictable long-term results, significant challenges remain, guiding future clinical research and innovation. Full article

Hydrophobic and superhydrophobic surfaces have emerged as key solutions for fluid transport, biofouling prevention, and energy efficiency, with market forecasts projecting a compound annual growth rate (CAGR) of over 15% through 2030 due to their broad range of applications. This review critically examines the principles of natural hydrophobicity, as exemplified by lotus leaves and shark skin, and their translation into engineered surfaces via micro/nanofabrication techniques, such as laser patterning, etching, and self-assembly. Recent advances in hybrid nanomaterials have demonstrated WCAs in the range of 140–160°, along with enhanced mechanical strength and chemical stability, enabling applications in self-cleaning, anti-corrosion, and oil–water separation technologies. Superhydrophobic coatings are particularly important for reducing ice adhesion by more than 80%, while drag reduction in pipelines can reach up to 30%, contributing to energy savings. Despite these advances, challenges remain in achieving long-term stability under harsh environmental conditions, minimizing environmental impact, and developing cost-effective, scalable fabrication techniques. Future directions focus on environmentally friendly, multifunctional nanocomposites with switchable wettability, including pH- and light-responsive coatings capable of reversibly transitioning between superhydrophilic (<5°) and superhydrophobic (>150°) states, paving the way for sustainable and adaptable surface technologies. Full article

Adhesive dentistry has undergone a significant evolution, transitioning from classical multi-step adhesives to simplified single-bottle or universal adhesives and now towards self-adhesive composites that no longer require a separate adhesive. This review focused on clinical applications, recent developments, and future trends in peer-reviewed articles identified through database searches in PubMed, Web of Science Core Collection, EBSCO DOSS, and Google Scholar without date restrictions. Reference mining of the identified articles was also used. Significant advances in the clinical performance of simplified adhesives are challenging the status of “gold standard” adhesives, although their long-term reliability in load-bearing (Class II) composite restorations remains uncertain due to a lack of longitudinal real-world data and extended survival metrics. Integration of acidic functional monomers like 10-MDP is becoming a standard to create a more stable chemical bond with dentin hydroxyapatite, rather than relying solely on micromechanical retention. Ensuring long-term stability of the hybrid layer against degradation remains a challenge. When enamel is present, etching with phosphoric acid is still recommended, while the necessity of enamel beveling is being questioned. As the clinical success of self-adhesive flowable composites is limited to non-load-bearing areas, further developments are moving toward self-adhesive bioactive composites for bulk-filling that combine self-adhesive properties with load-bearing capacity. Full article

Self-adhering flowable composites (SAFCs) were developed to simplify restorative procedures by eliminating separate adhesive steps; however, their bonding performance, mechanical properties, and biological properties remain controversial. This study evaluated a newly developed SAFC (SA-100R) compared with three commercial SAFCs (Fusio Liquid Dentin, Constic, and Vertise Flow) and a conventional composite (Clearfil AP-X used with a two-step self-etch adhesive). Microtensile bond strength (μTBS) to dentin, failure modes, Knoop microhardness, resin–dentin interfacial morphology (SEM), elemental composition (EDX), and cytocompatibility (CCK-8, LIVE/DEAD staining) were assessed. The conventional composite system exhibited significantly higher µTBS than all SAFCs (p < 0.05). Among SAFCs, SA-100R showed the highest bond strength and no pre-testing failures. SEM revealed abundant resin tag formation only in the conventional system, while all SAFCs showed interfacial gaps, with SA-100R exhibiting the least pronounced gaps. SA-100R showed no significant cytotoxic effects across all tested concentrations. Within the limitations of this short-term in vitro investigation, SA-100R demonstrated improved bonding performance and favorable biocompatibility compared with existing SAFCs, suggesting its potential as a simplified restorative material. However, the conventional adhesive/composite system remains the reference standard for dentin bond strength, and long-term clinical performance remains to be established through further studies. Full article

Additively manufactured definitive restorative materials have gained popularity recently. The current in vitro study evaluated the effects of surface treatment and thermocycling on the shear bond strength (SBS) between four 3D-printed definitive restorative materials and a self-adhesive resin cement (SARC). Disc-shaped specimens were fabricated from four printable materials: two composite materials, Crowntec (Crowntec) and CRS Composite (Custom Resin Solutions), and two ceramic-filled composites, Alias Dental Crown (Alias) and Permanent Crown (PC) (n = 12 per subgroup). Specimens were divided into four surface treatment subgroups: control, 9% hydrofluoric acid etching (HF), 50 µm aluminum oxide (Al₂O₃) airborne-particle abrasion (S50), and 110 µm Al₂O₃ airborne-particle abrasion (S110). SARC was applied using Teflon molds ($\varnothing 3 \times 3 \mathrm{m}\mathrm{m}$). After all specimens were stored in water at 37 °C for 24 h, half of the specimens were subjected to 10,000 thermocycles. Subsequently, SBS testing was performed for all specimens. Data were analyzed using Kruskal–Wallis and Mann–Whitney U tests (α = 0.05), and failure modes were classified microscopically. Before thermocycling, compared with control groups, HF significantly decreased SBS in Crowntec, whereas S110 significantly increased SBS in Alias (p < 0.05). After thermocycling, surface-treated CRS and Alias groups showed significantly higher SBS than controls (p < 0.05); Crowntec showed increased SBS after HF and S50, and Permanent Crown only after S50. No significant differences were found among control groups (p > 0.05). Surface-treated groups exhibited mainly mixed and cohesive failures. Surface treatments generally improved the SBS after thermocycling. Full article

This study aimed to assess the effect of etching protocols on the bonding performance of three universal adhesives to dentin under different aging conditions. Specimens were obtained from human molars and randomly allocated to 6 groups (n = 10) according to adhesive type (Clearfil S3 Bond Universal (CBU), Clearfil Universal Bond Quick (CUBQ), and Zipbond Universal (ZBU)) and application strategy (self-etch or etch-and-rinse). Each adhesive was applied according to the manufacturer’s instructions for the respective strategy, followed by composite resin build-up. Resin–dentin beams were prepared and subjected to three aging conditions: storage in distilled water at 37 °C for 24 h, 10,000 thermocycles, or pH cycling. Microtensile bond strength was measured, and the degree of conversion was evaluated using Fourier-transform infrared spectroscopy. Data were evaluated using analysis of variance and Weibull statistics (α = 0.05). Both adhesive type and application protocol significantly influenced bond strength (p < 0.05), whereas aging conditions had no significant effect (p > 0.05). At 24 h, ZBU in the etch-and-rinse strategy showed the highest bond strength and significantly outperformed CUBQ. After thermocycling and pH cycling, no significant differences were found among adhesives. All adhesives demonstrated higher reliability when used in the self-etch mode. Weibull analysis indicated that ZBU in the self-etch mode had the lowest probability of failure, with fractures occurring at higher stress levels. CUBQ showed the lowest degree of conversion. Full article

Gate definition is a major challenge in p-GaN gate AlGaN/GaN HEMT structures because of the high selectivity and low plasma damage required during the etching process. In this work, self-terminated etching, developed to limit surface damage and loss of the underlying AlGaN layer, is investigated. A comparison of two over-etch chemistries (Cl₂/O₂/N₂ and BCl₃/SF₆) revealed that the oxygen-based process yields superior results in terms of AlGaN surface morphology, producing a smoother surface and a more conformal p-GaN profile, while the fluorine-based process exhibited more anisotropic behavior, leading to p-GaN residues and surface pitting. To address across-wafer non-uniformity, a temperature gradient strategy using the tunable electrostatic chuck was developed. The optimized process was evaluated through automatic defect control and device robustness under drain bias-stress. A total reduction in defectivity and reliable HEMT devices across the wafer under high drain-source bias were achieved. These results demonstrate the effectiveness of the proposed solution, offering significant improvements in process efficiency and manufacturability. Full article