Search Results (578)

Extremely hydrophobic fluoromonomers are highly prone to phase separation during emulsion polymerization. Overcoming macroscopic experimental limitations, this study employs all-atom molecular dynamics (AA-MD) simulations to investigate the molecular-level solubilization behavior and thermal adaptability of the novel eco-friendly zwitterionic fluorocarbon surfactant-perfluorohexyl (butyl) sulfonyl carboxy propylamino dimethyl betaine (PFSC) and the traditional hydrocarbon surfactant SDS toward the monomers tetrafluoroethylene (TFE) and perfluoromethyl vinyl ether (PMVE). Simulation results indicate that fluorinated monomers in the SDS system exhibit a more dispersed spatial distribution, with weaker local association in surfactant-enriched regions. In contrast, fluorinated monomers in the PFSC system tend to distribute within regions rich in perfluorinated segments. This spatial characteristic is consistent with thermodynamic analysis results dominated by solubility parameter matching and van der Waals interactions. Under high-temperature conditions, the perfluorohexyl sulfonyl carboxy propylamino dimethyl betaine (C6) system maintains relatively stable local spatial characteristics, with the fluorinated monomers exhibiting low migration behavior. These spatial distribution characteristics and thermal response behaviors suggest that a fluorine-rich environment may help preserve the local distribution of fluorinated monomers under high-temperature conditions. These findings provide molecular-level insights into the structure–property relationships of eco-friendly fluorinated surfactants and offer computational guidance for their rational design. Full article

Background/Objectives: Acute liver failure (ALF) rapidly induces hepatic encephalopathy (HE), a severe neurological syndrome associated with astrocytic dysfunction and glutamatergic dysregulation. Guanosine (GUO), an endogenous guanine-based nucleoside, has neuroprotective properties, but its effects on astrocyte-associated glutamate regulation in ALF-induced HE remain incompletely understood. This study tested whether GUO attenuates neurological deterioration and glutamatergic dysfunction in an experimental model of ALF-induced HE. Methods: Male Wistar rats underwent 92% subtotal hepatectomy and received intraperitoneal GUO (7.5 mg/kg) or saline at prespecified time points after surgery. Neurological severity and survival were monitored for 72 h. Astrocytic morphology was assessed by GFAP immunofluorescence. Cerebrospinal fluid (CSF) albumin, glutamate, and glutamine levels, cortical Na⁺-dependent glutamate uptake, GLAST immunocontent, and the 67 kDa GLT-1 monomer immunocontent were evaluated. Results: Subtotal hepatectomy induced progressive neurological impairment, high mortality, GFAP-associated astrocytic remodeling, increased CSF albumin, glutamate, and glutamine levels, and reduced cortical glutamate uptake. GUO attenuated neurological deterioration and increased 72 h survival from 10.5% to 39.0% (log-rank p = 0.03). GUO also reduced CSF albumin, glutamate, and glutamine concentrations and improved cortical Na⁺-dependent glutamate uptake without altering GLAST or GLT-1 monomer immunocontent. Conclusions: GUO attenuated astrocyte-associated glutamatergic dysregulation and improved survival in ALF-induced HE. These findings support further mechanistic and translational investigation of GUO as an experimental modulator of astrocyte-associated glutamate handling in ALF-induced HE. Full article

Monomer sequence strongly influences copolymer properties, but direct block formation from a monomer mixture requires a large reactivity contrast. Here, fluorination was used to regulate anhydride reactivity in the cesium pivalate-catalyzed ring-opening alternating copolymerization (ROAC) of tetrafluorophthalic anhydride (FPA), phthalic anhydride (PA), and 3-perfluorohexyl-1,2-epoxypropane (PFE). Time-resolved nuclear magnetic resonance (NMR) spectroscopy showed that FPA reached >99% conversion before detectable PA incorporation. With 1,4-benzenedimethanol as a bidirectional initiator, this sequential consumption generated a central poly(FPA-alt-PFE) segment followed by poly(PA-alt-PFE) growth from both chain ends. Molar mass evolution, end-group analysis, and diffusion-ordered spectroscopy (DOSY) NMR collectively supported covalent block formation. Sequential incorporation was retained across three different FPA:PA feed ratios, and Beckingham–Sanoja–Lynd analysis yielded large and reciprocal effective reactivity-ratio descriptors ($r_{\mathrm{F}\mathrm{P}\mathrm{A}}\approx 8.3–8.6\times {10}^2$ and $r_{\mathrm{P}\mathrm{A}}\approx 1.2\times {10}^{-3}$), consistent with the experimentally observed real-block regime. Matched model reactions further indicated faster FPA ring-opening and higher observed epoxide-opening reactivity in a fluorinated aromatic carboxylate model system. These results demonstrate that H-to-F substitution can provide the kinetic bias required to program block copolyester sequence within a single ROAC platform. Full article

Acrylonitrile butadiene styrene (ABS) has emerged as a widely adopted solid fuel for hybrid rocket propulsion due to its compatibility with fused deposition modeling and favorable regression characteristics. As a terpolymer, however, ABS monomer mass fractions vary across commercial sources, introducing thermochemical variability that is rarely accounted for in propulsion modeling. This study presents a sensitivity analysis examining how compositional variability among ten commercially available ABS feedstock propagates into hybrid rocket performance predictions. Each source was characterized using bomb calorimetry and Fourier-transform infrared spectroscopy to derive source-specific constituent mass fractions and enthalpies of formation, which were supplied to NASA’s Chemical Equilibrium with Applications code to evaluate characteristic velocity under gaseous oxygen combustion. The second objective of this work is to determine which characterization and modeling workflow is sufficient for that purpose by quantifying the sensitivity of characteristic velocity predictions to the enthalpy of formation values derived from bomb calorimetry versus Fourier-transform infrared spectroscopy combined with the Van Krevelen group-contribution method. The two pathways yield enthalpy estimates that differ by 2.4–25.9 kJ/mol, but these differences propagate to less than 0.5% in predicted characteristic velocity across all 3D-printed filaments, indicating that the simpler group-contribution approach is adequate for routine performance prediction while direct calorimetry retains independent values for material qualification. The results demonstrate that assuming a single canonical ABS formulation introduces meaningful uncertainty in predicted characteristic velocity and that experimental feedstock characterization should be considered standard practice in hybrid propellant development. Full article

Dry eye disease (DED) is a complex ocular surface disorder characterized by tear film instability, discomfort, hyperosmolarity, inflammation, and neurosensory dysfunction. Since individuals spend a significant amount of time inside buildings, exposure to indoor environments has emerged as a noteworthy and adjustable factor influencing ocular surface disorders. This analysis consolidates recent findings connecting indoor air contaminants, such as particulate pollutants, volatile organic substances, formaldehyde, and other gaseous irritants, as well as tobacco and cooking fumes, heavy metals, organophosphate flame retardants, and liquid crystal compounds, with the mechanisms and symptoms associated with DED. Research suggests that indoor environmental factors can exacerbate DED by triggering interconnected mechanisms such as oxidative damage, inflammation, lipid degradation, meibomian gland issues, decreased tear production, impairment of goblet cells and the mucin layer, disruption of tight junctions, and damage to the corneal or conjunctival epithelium. The most robust clinical evidence currently pertains to tobacco smoke, particulate matter, indoor air pollution, low humidity, and poor ventilation. In contrast, although biological plausibility exists for heavy metals, flame retardants, and liquid crystal monomers, the supporting data remain relatively sparse, indirect, and less comprehensive. Harmonized exposure assessments, prospective cohort studies, analyses of pollutant mixtures, and experimental intervention trials are needed to better characterize dose–response relationships and to establish effective preventive measures. Assessment of environmental history and improvement of indoor air quality should be regarded as integral and interrelated components in the prevention and management of DED. Full article

The ultrafast photochemical reaction dynamics of a cyclic(alkyl)(amino)carbene–carbon disulfide (CAAC–CS₂) dimer containing two adjacent S–S bonds were investigated using femtosecond time-resolved infrared spectroscopy in combination with multireference electronic structure calculations. Time-resolved vibrational spectra and global kinetic analysis reveal that photoexcitation of the S–S n → σ* transition at 375 nm induces subpicosecond (<0.3 ps) homolytic cleavage of one S–S bond, generating a bis-thiyl diradical intermediate. This intermediate undergoes two competing pathways: recombination to regenerate the parent dimer with a time constant of 5.7–8.5 ps, or secondary cleavage of the remaining S–S bond to yield two CAAC–CS₂ monomers with a time constant of 30–35 ps. Wavelength- and temperature-dependent kinetic measurements demonstrate that the branching between these pathways is governed by excess excitation energy and thermally driven radical-pair fluctuations. Multireference electronic structure calculations support a sequential S–S bond cleavage mechanism, in good agreement with the experimental observations. These findings provide direct spectroscopic evidence for a bis-thiyl diradical intermediate and offer new mechanistic insight into the ultrafast photochemistry of adjacent S–S bonds. Full article

Background and Objectives: This narrative review aims to evaluate the correlation between dental luting cements, peri-implantitis and the molecular mechanisms governing tissue destruction, with a specific focus on the role of autophagy and nanotechnology. Methods: A comprehensive literature search was conducted across electronic databases, including PubMed, Scopus and Web of Science, to identify relevant studies on cement cytotoxicity, cellular responses and nanomaterial integration. Results: Residual cement in the peri-implant sulcus promotes biofilm accumulation and severe inflammation. At a cellular level, resin-base monomers (e.g., Bis-GMA) impair human gingival fibroblasts via oxidative stress and mitochondrial dysfunction. Autophagy serves as a vital cytoprotective mechanism against cement toxicity and titanium particle accumulation. Experimental studies suggest that incorporating nanomaterials, specifically graphene oxide and silver nanoparticles (≤1 wt.%), has shown promising results in enhancing antimicrobial efficacy without compromising biocompatibility in vitro. Conclusions: To minimize peri-implantitis, clinical protocols should prioritize the meticulous removal of excess cement and the development of nano-reinforced luting agents. Optimizing these molecular pathways offers actionable preventive strategies, guiding clinicians toward safer cementation protocols and enhanced long-term implant success. Full article

Background: Polymerization shrinkage stress remains one of the main limitations of methacrylate-based dental resin composites, as it may lead to marginal gap formation, interfacial debonding, and long-term restoration failure. In recent years, numerous experimental monomers and alternative polymerization strategies have been proposed to mitigate stress development during polymer network formation. This scoping review aimed to map and summarize experimental and modified monomer systems investigated for reducing polymerization shrinkage stress in dental methacrylate-based composites. Methods: A comprehensive literature search was conducted in PubMed/MEDLINE, Scopus, Web of Science Core Collection, Embase, and Google Scholar to identify relevant studies published between 2010 and 2025. The search strategy combined terms related to dental resins, polymerization shrinkage, shrinkage stress, and experimental monomers (1678 papers found). After duplicate removal and screening of titles and abstracts, potentially relevant articles were assessed for full-text eligibility according to predefined inclusion criteria. In vitro studies investigating experimental monomers or modified resin systems with reported polymerization shrinkage stress measurements were included. Data extraction focused on monomer composition, chemical strategy for stress reduction, measurement methods, and reported shrinkage stress values. Results: A total of 33 studies met the eligibility criteria and were included in the qualitative synthesis. The reviewed studies investigated a wide range of molecular strategies, including thiol–ene and thiourethane chemistries, addition–fragmentation chain transfer (AFCT) networks, ring-opening or expanding monomers, high-molecular-weight dimethacrylates, ether-based monomers, and alternative reactive diluents. Reported polymerization shrinkage stress outcomes varied widely across studies because of differences in testing methods, specimen geometry, system compliance, curing protocols, reporting units, and control materials. Therefore, the results were synthesized descriptively, with emphasis on within-study comparisons between experimental systems and their respective controls rather than on direct numerical comparisons across studies. Thiol-based systems and adaptive polymerization mechanisms consistently demonstrated the greatest reductions in shrinkage stress compared with conventional dimethacrylate resin matrices. Conclusions: Experimental monomer design represents a promising strategy for controlling polymerization shrinkage stress in dental composites. Chemical approaches that modify polymerization mechanisms or network architecture may significantly reduce stress development during curing. Further studies are required to evaluate the long-term chemical, physical, and mechanical stability, as well as the clinical applicability, of these experimental and modified resin systems. 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

This study aimed to explore the protective effects of different concentration combinations of four traditional Chinese medicine (TCM) monomers (Eleutheroside E, Anemoside B4, Forsythoside A, and Esculin) on porcine intestinal epithelial cell (IPEC-J2) damage induced by soybean 7S globulin, providing preliminary in vitro evidence for future studies on dietary-allergen-induced intestinal injury in piglets. An L₉ (3⁴) orthogonal experimental design was implemented to identify the optimized ratio of these monomers. IPEC-J2 cells were co-cultured with 5 mg/mL 7S globulin and the selected combinations for 24 h. Cell viability was determined via Cell Counting Kit-8 (CCK-8) assay, while cytokine secretion, oxidative status, and mechanical barrier markers were assessed using enzyme-linked immunosorbent assay (ELISA) and RT-qPCR. The optimal combination was determined to consist of Eleutheroside E at 50 mg/L, Anemoside B4 at 25 mg/L, Forsythoside A at 80 mg/L, and Esculin at 20 mg/L. This formulation significantly alleviated inflammatory damage, upregulated tight-junction-related mRNA expression, and reversed the decrease in cellular viability caused by 7S globulin. Furthermore, Western blot and transcript analyses suggested that this combination exerted its protective effects by modulating the nuclear factor-kappa B/mitogen-activated protein kinase (NF-κB/MAPK) pathway-related markers, reducing the expression of p38 MAPK, c-Jun N-terminal kinase (JNK), NF-κB p65, and inducible nitric oxide synthase (iNOS). In conclusion, this optimized combination of TCM monomers successfully alleviates both inflammatory injury and oxidative stress in IPEC-J2 cells in vitro and holds potential as a promising dietary additive candidate for mitigating dietary-allergen-induced enteropathy in piglets. Full article

The glass transition temperature (Tg) is a pivotal design parameter for polymer performance across diverse applications, yet its rapid prediction within expansive chemical spaces remains a challenge. We present a machine learning (ML) framework for the high-throughput prediction of Tg in binary copolymers, trained on experimental datasets encompassing both homopolymers and copolymers. We evaluate various ML architectures, including graph-based algorithms, to effectively capture non-linear composition–property relationships. The optimized model achieves high predictive accuracy with an RMSE of ~14K and an R² of ~0.98. Crucially, the framework accounts for the chemical diversity of monomeric units by integrating structural descriptors with molar composition ratios, enabling the model to capture complex dependencies of thermal stability on chemical structure and composition. We validate the model’s robustness using physics-based molecular dynamics (MD) simulations. To showcase the platform’s scalability, we generated a library of approximately 148,000 binary copolymer compositions and predicted their Tg, facilitating the rapid mapping of vast design spaces. This extensive virtual library enables the identification of optimal monomer pairings that would be experimentally inaccessible through traditional trial-and-error methods. Through these large-scale exploration studies, we demonstrate the ability to design copolymers for targeted applications, including a specific case study on elastomeric systems. This integrated approach, combining experimental data, ML modeling, and physics-based validation, offers a transformative path for the accelerated discovery and multi-property optimization of functional copolymers. Full article

Objectives: This scoping review summarized the evidence on the biocompatibility of pit and fissure sealants, focusing on cytotoxicity, genotoxicity, and overall biological safety of commercial and experimental materials evaluated in vitro and in vivo. Methods: Following the PRISMA-ScR guidelines, eligibility was defined using the Population, Concept, and Context (PCC) framework: the population comprised cell cultures, animal models, or human participants exposed to sealants; the concept was biocompatibility, including cytotoxicity, genotoxicity, and inflammatory or tissue response; and the context encompassed commercial and experimental pit and fissure sealants used in preventive dentistry, particularly in pediatric populations. PubMed and Scopus platforms were searched without restrictions on publication year or language. Studies assessing biocompatibility (cytotoxicity, genotoxicity, inflammatory or tissue response) in cell cultures, animal models, or humans were eligible; those evaluating only clinical efficacy were excluded. Two reviewers independently performed study selection and data extraction. Results: Of 406 records (291 after deduplication), 10 studies were included—nine in vitro and one in vivo. Resin-based sealants predominated, mainly assessing residual monomers (TEGDMA, Bis-GMA) and their effects on fibroblasts, keratinocytes, periodontal ligament cells, and buccal epithelial cells. TEGDMA was released most frequently, whereas Bis-GMA showed the highest cytotoxicity. Experimental sealants containing nano-calcium fluoride, calcium phosphate, bioactive glass, or antibacterial monomers generally showed favorable biocompatibility, although high additive concentrations reduced cell viability. The single in vivo study reported good biocompatibility without significant genotoxicity. Conclusions: Pit and fissure sealants generally show acceptable biocompatibility and remain safe for caries prevention, although the biological response depends on composition, degree of polymerization, and residual monomer release. Further standardized long-term in vivo research is needed, particularly in pediatric populations. Full article

Buried mass-resonator systems, including metafoundations, have attracted increasing attention as an effective approach for mitigating vibrations induced by seismic waves in structural systems. In this study, a series of shaking table tests are conducted on a small-scale metafoundation to experimentally evaluate its vibration reduction performance under seismic excitation. The metafoundation model was fabricated using acrylic plastic and ethylene propylene diene monomer (EPDM) rubber foam, and its dynamic characteristics were examined through white noise and sine sweep tests. The attenuation zones identified from the experiments were validated through comparison with the frequency band gaps (FBGs) of the metamaterial obtained from numerical simulations. A simple small-scale structure was subsequently installed on the metafoundation, and the dynamic behavior of the combined system was investigated using white noise and sine sweep signals. The effectiveness of the metafoundation in reducing the seismic response of the structural system was further evaluated using earthquake ground motions. The experimental results demonstrate that the metafoundation significantly reduces the seismic response of the structural system at frequencies corresponding to the attenuation zone of the structural system with metamaterial. Full article

The long-term effects of water immersion on the physicochemical and functional properties of ethylene-propylene-diene monomer (EPDM) elastomer, widely used as insulation in medium-voltage electrical cables, were investigated over a period of 140 days at room temperature. A multi-scale experimental approach combining complementary characterization techniques was employed to establish quantitative correlations between moisture-induced physicochemical changes and the resulting evolution of functional performance. Water uptake, governed by Fickian diffusion kinetics, remained limited to 0.30 wt%. At the surface, progressive roughening was observed alongside the formation of microcavities and microcracks. Leaching of mineral fillers and an increase in surface polarity were found to enhance wettability. These combined physicochemical alterations translated into measurable degradation of functional properties, with two distinct kinetic regimes identified. Shore hardness, volume resistivity, and dielectric strength underwent rapid deterioration within the first few days of immersion, whereas tensile strength, elongation at break, dielectric permittivity, and dielectric loss factor evolved more gradually over timescales of several tens of days. Temporal profiles for each property were fitted to appropriate models, and characteristic degradation timescales were estimated. These findings provide a structured, physically grounded picture of EPDM degradation under water exposure and offer quantitative data to support the development of service-life prediction models for cable insulation systems. Full article

To resolve the discrepancy between the measured strain and the actual surface strain of wind turbine blades when using rubber-encapsulated fiber Bragg grating (FBG) sensors for strain monitoring, this study establishes a surface-bonded strain transfer model for such sensors. The total strain transfer efficiency of the sensor is decomposed into two components: the strain transfer efficiency from the rubber substrate to the FBG core (encapsulated grating strain transfer efficiency) and that from the wind turbine blade to the rubber substrate (strain transfer efficiency between the rubber substrate and the blade). Based on the theory of mechanics of materials, the strain transfer equation is derived, and the key factors influencing strain transfer efficiency—FBG bonding length and rubber substrate thickness—are analyzed via the control variable method. Three ethylene propylene diene monomer (EPDM)-encapsulated FBG sensors with rubber substrate thicknesses of 3 mm, 4 mm, and 6 mm were fabricated. Tensile strain transfer tests were conducted using fiber-reinforced plastic (FRP) strips to simulate the material properties of wind turbine blades, so as to validate the effectiveness of the proposed model. The experimental results demonstrate that the strain transfer efficiency of the sensor increases with the extension of FBG bonding length and decreases with the increase in rubber substrate thickness, with 4 mm determined as the optimal substrate thickness for EPDM-encapsulated FBG sensors. On the basis of the aforementioned findings, an EPDM-encapsulated FBG strain rosette sensor was developed, which can effectively measure the complex stress of a wind turbine blade model. This study provides a theoretical foundation for the structural design and engineering application of rubber-encapsulated FBG sensors in the strain monitoring of wind turbine blades. Full article