Search Results (4,090)

This study aimed to evaluate the penetration and bonding performance of three restorative materials—high-viscosity glass ionomer cement (Riva Self Cure HV), resin-modified glass ionomer cement (Riva Light Cure) and a bioactive resin (Activa BioActive Restorative™)—in the healthy and carious dentine of permanent molars. Forty extracted human molars with sound or decayed dentine were restored following standardised protocols and subsequently divided into slices. So, twenty-four samples were used for each group (sound and carious dentine) for interface analysis using confocal laser scanning microscopy, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy, and another eight simples were used for each group (sound and carious dentine) for Vickers microhardness testing. Results showed that both glass ionomer cements achieved consistent chemical bonding in healthy dentine and demonstrated better interfacial adaptation compared to carious dentine, where partially demineralised areas showed weaker bonding. The bioactive resin exhibited good adhesion in sound dentine due to the adhesive system but showed poorer interaction in decayed dentine with signs of interfacial separation. Elemental analysis revealed similar compositions among materials, with no significant differences in material concentrations among the ionomers, while there were significant differences with the other materials. On the other hand, some variations were observed in the sulphur, fluoride and strontium content depending on dentine condition. Microhardness values were higher in healthy dentine than in carious dentine for all materials (p < 0.001), except the high-viscosity glass ionomer, which maintained stable hardness in both substrates (36.33 ± 6.23 VHN vs. 34.56 ± 4.31 VHN; p = 0.605). These findings highlight the relevance of material selection and dentine condition in minimally invasive restorative dentistry. Full article

This study investigates the strength and microstructural evolution of SRX-stabilized aeolian sand–gravel mixtures for flexible base applications in desert roads. CBR, UPS (uniaxial penetration strength), and compressive resilient modulus tests were conducted under varying SRX dosages (0.4–1.0%) and aeolian sand contents (30–50%). The results show that increasing the SRX dosage significantly improves all three indices, with the 0.5% SRX and 30% aeolian sand mixture yielding the CBR (385.89%) and UPS (0.938 MPa) and achieving a compressive resilient modulus that meets the requirements for graded aggregate base layers. XRD FTIR and SEM–EDS analyses reveal that the SRX enhances material structure primarily through physical mechanisms, forming dense films and bonding networks without inducing significant chemical reactions. Extended curing improves structural integrity, while excessive aeolian sand reduces compactness. SRX-stabilized aeolian sand gravel is a viable base and subbase material for desert highways. Full article

Cobalt-based alloys such as Stellite 6 are widely applied in demanding conditions because of their good resistance to wear, erosion, and corrosion, but further improvements in erosion resistance are still required. This work analyzes the effect of adding titanium and tungsten on the structure and properties of Stellite 6 coatings produced by laser cladding, aiming to enhance their erosion resistance. Penetrant tests confirmed that the additions did not reduce coating quality, and macroscopic observations showed that appropriate process parameters allowed for defect-free coatings with strong bonding to the substrate. Microstructural studies carried out by SEM/EDS (Scanning Electron Microscopy/ Energy Dispersive Spectroscopy) and XRD (X-ray Diffraction) revealed that the reference Stellite 6 coating consisted of a cobalt-based austenitic matrix with interdendritic chromium carbides, while Ti and W additions led to the in situ formation of primary and eutectic (Ti,W)C carbides. Transmission electron microscopy showed a gradient in tungsten concentration inside the primary carbides, with progressive tungsten dissolution into the TiC lattice. Although different powder compositions had only a moderate effect on hardness, erosion tests demonstrated that the coatings with Ti and W exhibited clearly improved resistance. In particular, the in situ carbides enhanced erosion resistance at 30° impingement angles, while also maintaining high resistance under 90° impact. These findings confirm that modifying Stellite 6 with Ti and W during laser cladding is an effective way to improve its durability in erosive conditions. Full article

Seeding depth is a critical factor influencing the uniformity and vigor of wheat seedlings. To address inconsistent seeding depth in wide-row uniform seeding agricultural practices, we performed parameter analysis and optimization experiments on the seeding depth device of a wheat wide-row uniform seeding machine. The structure and working principle of the device were described, soil movement during operation was analyzed, and the models of rotary tiller blades and soil retention plates were investigated, identifying three key factors affecting seeding quality. Using the discrete element method, a model of the seeding depth device was established, and experiments were conducted, yielding the following conclusions: 1. Single-factor experiments were conducted under different seeding rate conditions, and it was found that the effects of various factors on the two indicators, namely the seeding depth qualification rate and the coefficient of variation for seeding uniformity, were regular. 2. A quadratic orthogonal rotated combination experiment with three factors determined the optimal structural parameters: tillage device penetration depth of 120 mm, rotational speed of 310 rpm, and soil retention plate inclination angle of 27°. Under these parameters, the seed depth qualification rate exceeded 90%, and the coefficient of variation for seed distribution uniformity was below 25%. 3. Field validation tests under optimal parameters confirmed a seed depth qualification rate ≥90% and variation for seed distribution uniformity was below ≤20.69%. 4. The error between simulation and field tests was ≤5%, validating the reliability of the discrete element method-based optimization for the seeding depth device. Full article

Apigenin (AP) is a natural flavonoid with senomorphic potential and neuroprotective action; however, poor aqueous solubility (<1 μg/mL) limits its bioavailability and therapeutic use. Therefore, the aim of this study was to obtain an amorphous dispersion of AP and evaluate its biological properties. Screening of AP solubilization capabilities under supercritical carbon dioxide processing conditions showed that the system with Soluplus (SOL) achieved the greatest improvement in AP dissolution (6455.4 ± 27.2 μg/mL). Using optimized process parameters (50 °C, 6500 PSI), the AP solubility increased to 8050.2 ± 35.1 μg/mL. X-ray powder diffraction (XRPD) confirmed amorphization, aligning with improved dissolution of AP in both acidic and neutral pH media. As a result, using the PAMPA model, an improvement in AP penetration through membranes simulating gastrointestinal and blood–brain barriers was demonstrated. The significant stability of the obtained amorphous AP dispersion (12 months at room conditions) was associated with stabilizing AP–solubilizer intermolecular interactions, mainly expressed as the shifts in the bands of AP in the range of 1018–1269 cm⁻¹ observed in ATR-FT-IR spectra. Chromatographic analysis confirmed the lack of AP decomposition immediately after the preparation of the amorphous dispersion, as well as after 12 months. As expected, the improvement of AP solubility is correlated with better biological activity assessed in selected in vitro tests such as antioxidant properties (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and cupric ion reducing antioxidant capacity (CUPRAC) assays) and anticholinesterase inhibition capabilities (AChE and BChE assays). The effect of the studies on improving AP solubility under supercritical carbon dioxide processing conditions is obtaining a stable amorphous AP dispersion (up to 12 months). Regardless of the pH of the media, an improvement in AP dissolution and penetration, conditioned by the passive diffusion process, through biological membranes was noted. Moreover, a more efficient antioxidant and neuroprotective effect of AP in the developed amorphous dispersion can also be suggested. Full article

In high-altitude corrosive environments, weathering steel is widely applied due to its excellent corrosion resistance. However, the welded joint regions, where the chemical composition and microstructure undergo changes, are susceptible to the corrosion-induced degradation of mechanical properties. This study investigates the corrosion–mechanical synergistic degradation behavior of a 16 mm thick Q500 qENH base metal and its V-type and Y-type welded joint specimens. Periodic immersion corrosion tests were conducted to simulate plateau atmospheric conditions, followed by mechanical performance evaluations. Corrosion metrics—including corrosion rate, cross-sectional loss, penetration depth, and corrosion progression speed—were analyzed in relation to mechanical indicators such as the fracture location, yield load, ultimate load, yield strength, and tensile strength at varying exposure durations. The results indicate that the corrosion process exhibits distinct layering, with a two-stage characteristic of rapid initial corrosion followed by slower progression. Welded joints consistently exhibit higher corrosion rates than the base metal, with the rate difference evolving nonlinearly in an “increase–decrease–stabilization” trend. After corrosion, the mechanical performance degradation of welded joint specimens is more severe than that of base metal specimens. Full article

Concrete sleepers are essential components of railroad infrastructure, yet their service life has been reduced by one-third due to deterioration caused by internal swelling reactions (ISR), leading a major Brazilian railroad to replace millions of sleepers within a decade. This study investigates the reliability of various non-destructive testing (NDT) techniques to estimate damage levels in concrete sleepers. The methods evaluated include surface hardness testing, stress wave propagation, electromagnetic wave propagation using ground-penetrating radar (GPR), electrical resistivity, and resonant frequency. These techniques were applied to assess sleepers diagnosed as affected by alkali-silica reaction (ASR) and delayed ettringite formation (DEF) at different deterioration degrees. Although findings indicate that most NDT methods are limited and unreliable for quantifying ISR-induced damage, resonant frequency testing combined with energy dissipation analysis provided the highest accuracy across all damage stages and was able to capture microstructural changes before significant expansion occurred. These results support the use of vibration-based screening tools to enhance early detection and guide condition assessment of railroad infrastructure, helping to reduce the premature replacement of ISR-affected concrete sleepers. Full article

Bentonite materials are extensively used in cutoff walls at landfill sites. This study calculates the stress and permeability characteristics of bentonite materials using the piezocone penetration test (CPTU) and ABAQUS simulations. The lateral effective stress of bentonite materials is evaluated using arching models, lateral squeezing models, and a modified lateral squeezing model. Pore pressure dissipation types are categorized into standard and non-standard, with the coefficient of consolidation obtained using the half dissipation time of excess pore pressure (t₅₀) method. In the standard dissipation type, the excess pore pressure gradually dissipates over time after the cone stops penetrating. In contrast, the non-standard dissipation type is characterized by an initial increase in pore pressure until it reaches a maximum value, followed by a decrease to hydrostatic pressure. Additionally, the pore pressure dissipation process in bentonite cutoff walls is recorded and analyzed over various time intervals. Finally, the relationship between hydraulic conductivity and t₅₀ at landfill sites is established based on standard and non-standard dissipation types using CPTU and ABAQUS methods. The t₅₀ method is used for the standard dissipation type, while a modified t_50m method is used for the non-standard dissipation type from CPTU and a t_50m method is used in the non-standard dissipation type from CPTU. The t_50m is the modified value derived from t₅₀. Cutoff walls made from bentonite materials offer the advantage of enhancing the isolation effects and meeting the design requirement of permeability (1.0 × 10⁻⁷ cm/s). Full article

Road safety in cities is becoming a bigger concern worldwide. As more people own cars and traffic congestion increases on old roads, the risk of accidents also grows, which severely affects victims and their families. In 2023, data from the Société de l’Assurance Automobile du Québec (SAAQ) reported that 380 people died in traffic accidents in Quebec. A study of road accidents in Montreal between 2012 and 2021 looked at the most dangerous locations, times, and traffic patterns. In this paper, we investigate the role of autonomous vehicles (AVs) vs human-driven vehicles (HDVs) in reducing road accidents in mixed traffic situations. The reaction time of human drivers to road accidents at signalized intersections affects safety and is used to compare the difference between the two situations. Microscopic traffic simulation models (MTMs) namely the Krauss car-following model is developed using SUMO to assess the vehicles performance. Case study 1 assesses the effect of reaction time on human-driven vehicles. The findings show that longer reaction times lead to more collisions. Case study 2 looks at autonomous vehicles and how human-driven vehicles interact in mixed traffic. The simulations tested various levels of AV penetration (0%, 25%, 50%, 75%, and 100%) in mixed traffic and found that more AVs on the road improve safety and reduce the number of accidents. Full article

Microneedles represent an emerging transdermal drug delivery platform offering painless, minimally invasive penetration of the stratum corneum. This study addresses limitations of conventional lidocaine hydrochloride formulations, such as slow onset and poor patient compliance, by developing lidocaine hydrochloride-loaded dissolvable microneedles (LH-DMNs) for rapid local anesthesia. LH-DMNs were fabricated via centrifugal casting using polyvinyl alcohol (PVA) as the matrix material in polydimethylsiloxane (PDMS) negative molds, which imparts high mechanical strength to the microneedles. Biocompatibility assessments showed negligible skin irritation, resolving within 3 min. And drug-loading capacity reached 24.0 ± 2.84 mg per patch. Pharmacodynamic evaluation via mouse hot plate tests demonstrated significant analgesia, increasing paw withdrawal latency to 36.11 ± 1.62 s at 5 min post-application (p < 0.01). The results demonstrated that the LH-DMNs significantly elevated the pain threshold in mice within 5 min, surpassing the efficacy of conventional anesthetic gels and providing a rapid and effective solution for pain relief. These findings validate the system’s rapid drug release and efficacy, positioning dissolvable microneedles as a clinically viable alternative for enhanced transdermal anesthesia. Full article

Stone cleaning for cultural heritage monuments is a critical conservation intervention that must effectively eliminate harmful surface contaminants while preserving the material’s physical, chemical, and historical integrity. This study investigated the removal of tenacious black biofilms formed by Nocardia species previously isolated from deteriorated limestone from the Bastet tomb in Tell Basta, Zagazig City, Egypt, using a Q-switched 1064 nm Nd:YAG laser. Experimental limestone specimens were systematically inoculated with Nocardia sp. under controlled laboratory conditions to simulate biodeterioration processes. Comprehensive testing revealed that a laser fluence of 0.03 J/cm² with a 5 ns pulse duration, applied under wet conditions with 500 pulses, achieved the complete elimination of the biological black film without damaging the underlying stone substrate. The cleaning efficacy was evaluated through an integrated analytical framework combining stereomicroscopy, scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX), X-ray diffraction (XRD), and laser-induced plasma spectroscopy (LIPS). These analyses demonstrated a remarkable transformation from a compromised mineralogical composition dominated by gypsum (62%) and anhydrite (13%) to a restored state of 98% calcite, confirming the laser treatment’s effectiveness in reversing biodeterioration processes. SEM micrographs revealed the complete elimination of mycelial networks that had penetrated to depths between 984 μm and 1.66 mm, while LIPS analysis confirmed the restoration of elemental signatures to near-control levels. The successful application of LIPS for real-time monitoring during cleaning provides a valuable tool for preventing overcleaning, addressing a significant concern in laser conservation interventions. This research establishes evidence-based protocols for the non-invasive removal of Nocardia-induced black biofilms from limestone artifacts, offering conservation professionals a precise, effective, and environmentally sustainable alternative to traditional chemical treatments for preserving irreplaceable cultural heritage. Full article

Soil void ratio is a key parameter in geotechnical engineering design and geological hazard prevention. However, existing methods for determining void ratio are plagued by issues such as difficulty in sampling, susceptibility of samples to disturbance, and heavy experimental workload. The cone penetration test, with its advantages of simple operation, high survey efficiency, and high accuracy, has gradually become a commonly used in situ testing method in engineering investigations. Based on data from the Yellow River Delta, this paper evaluates the applicability of several models related to void ratio. Combined with the Robertson density prediction model, a semi-empirical model for predicting void ratio based on the piezocone penetration test (CPTu), in situ testing is proposed, which enables efficient evaluation by establishing a conversion mechanism between soil density and void ratio. Verification using a database built from six types of nearly saturated sedimentary soil data shows that underestimation of predicted density will amplify the error of soil void ratio. The prediction accuracy is significantly improved after coefficient correction. Finally, a simple model for predicting void ratio that only requires CPTu data is developed, providing a sampling-free evaluation tool for estuarine and marine sedimentary areas. Full article

Background: A major challenge in adhesive dentistry, often leading to restoration failure, is microleakage. This in vitro comparative study was designed to assess microleakage at the tooth–composite interface. The investigation aimed to compare the sealing efficacy of two commonly used adhesive systems. Methods: Standardized Class I cavities were prepared on 20 extracted human molars and randomly divided into two groups (n = 10 each). Group A was treated with a fifth-generation total-etch adhesive (OptiBond™ Solo Plus, Kerr Corporation, Orange, CA, USA), and Group B received a seventh-generation self-etch adhesive (Adhese® Universal VivaPen®, Ivoclar Vivadent AG, Schaan, Liechtenstein). All restorations were completed using Herculite XRV composite resin. Microleakage was evaluated using dye penetration analysis after immersion in 2% methylene blue for 10 days, followed by longitudinal sectioning and microscopic measurement at 500× magnification. Results: The fifth-generation adhesive group showed a mean microleakage of 0.2503 ± 0.1921 mm, while the seventh-generation group recorded 0.2484 ± 0.1764 mm. Statistical analysis using an independent t-test revealed no significant difference between the groups (p = 0.696). Conclusions: Both adhesive systems demonstrated comparable performance in minimizing microleakage under standardized conditions. Although the total-etch group exhibited slightly lower numerical values, the difference was not statistically significant. These findings suggest that both adhesive approaches can be clinically effective when applied appropriately. Full article

This article presents experimental studies on the characterization of geopolymer composites intended for applications in aquatic environments, with particular emphasis on underwater infrastructure. The motivation for conducting the research was the growing need to develop durable and ecological building materials that will be resistant to long-term exposure to moisture and aggressive chemical agents, typical for the underwater environment, where traditional cement concretes undergo gradual degradation due to long-term water impact, including hydrotechnical and underwater infrastructure. Geopolymer binders were produced based on metakaolin activated by alkaline solutions containing sodium hydroxide. Several series of mixtures with additives such as blast furnace slag, amphibolite and carbon fibers were developed to evaluate the effect of these components on mechanical strength, water absorption and chemical durability. The conducted studies showed that slag additions improved mechanical properties, for the best composition it across 50 MPa. In contrast, the addition of amphibolite had an unfavorable effect, which probably results from introducing inhomogeneity into the material structure. The presence of carbon fibers promoted matrix cohesion, but their uneven distribution could lead to local strength differences. Water absorption tests have shown that geopolymers reach full water saturation within 24 to 48 h, which indicates rapid establishment of capillary equilibrium and limited further water penetration. The conclusions from the work indicate that geopolymer composites with a moderate amount of blast furnace slag and subjected to appropriate curing conditions. High strength, water and chemical resistance make them suitable for, among others, the construction of marine foundations, protection and structural shields of submerged applications. Full article

While autonomous driving systems and intelligent transportation infrastructures become increasingly software-defined and network-connected, ensuring their cybersecurity has become a critical component of traffic safety. Large language models (LLMs) have recently shown promise in automating aspects of penetration testing, yet most existing approaches remain limited to simple, single-step exploits. They struggle to handle complex, multi-stage vulnerabilities that demand precise coordination, contextual reasoning, and knowledge reuse. This is particularly problematic in safety-critical domains, such as autonomous vehicles, where subtle software flaws can cascade across interdependent subsystems. In this work, we present CurriculumPT, a novel LLM-based penetration testing framework specifically designed for the security of intelligent systems. CurriculumPT combines curriculum learning and a multi-agent system to enable LLM agents to progressively acquire and apply exploitation skills across common vulnerabilities and exposures-based tasks. Through a structured progression from simple to complex vulnerabilities, agents build and refine an experience knowledge base that supports generalization to new attack surfaces without requiring model fine-tuning. We evaluate CurriculumPT on 15 real-world vulnerabilities scenarios and demonstrate that it outperforms three state-of-the-art baselines by up to 18 percentage points in exploit success rate, while achieving superior efficiency in execution time and resource usage. Our results confirm that CurriculumPT is capable of autonomous, scalable penetration testing and knowledge transfer, laying the groundwork for intelligent security auditing of modern autonomous driving systems and other cyberphysical transportation platforms. Full article