Search Results (7,801)

This paper presents a technique for enhancing the cracking resistance of reinforced concrete (RC) beams through the external application of liquid rubber. To evaluate the influence of this coating on flexural performance, four-point bending tests were conducted on seven RC beams, comprising six coated beams and one uncoated control beam. The effects of coating position (beam soffit, beam sides, or both) and number of coating layers (3 or 6) on the flexural response were investigated. The results indicate that the external application of liquid rubber improves the cracking load and ductility of the RC beams to some extent, and the degree of improvement is related to the number of coating layers. Moreover, the application of liquid rubber to the tensile zone of the RC beams can moderately restrain tensile deformation of the concrete. When the coating was applied only to the beam soffit, the concrete strain at the soffit was lower than that in the tensile zone on the beam sides, resulting in a non-linear distribution of tensile strain along the section height within the pure bending region. Full article

Transmissible gastroenteritis (TGE) and pseudorabies (PR) remain important viral diseases causing massive economic losses and posing a continuous burden on the global swine industry. The continuous emergence of variant strains of transmissible gastroenteritis virus (TGEV) and pseudorabies virus (PRV) has gradually weakened the protective efficacy of traditional vaccines, highlighting the urgent need for next-generation preventive vaccine candidates. Here, we constructed a recombinant pseudorabies virus named rPRV-AD expressing the major neutralizing epitopes A and D of the TGEV spike protein via homologous recombination combined with CRISPR/Cas9-gene editing technology and then evaluated its biological characteristics in vitro and immunogenicity in piglets. The results showed that this recombinant virus exhibited similar replication kinetics and biological properties to the parental strain. Immunization of 2-week-old piglets with rPRV-AD caused no obvious adverse effects and induced specific antibody and neutralizing antibody responses against both TGEV and PRV. Following virulent TGEV challenge, compared with the DMEM control group, rPRV-AD immunization alleviated clinical signs of piglets and significantly reduced viral load in intestine and feces, although its protective efficacy was lower than that of the commercial TGEV vaccine. Moreover, rPRV-AD provided effective clinical protection against challenge with the virulent PRV NY strain. In summary, these findings suggest that rPRV-AD represents a vaccine candidate that provides partial protection and warrants further optimization, and yet shows short-term protective efficacy against both PRV and TGEV in pigs. Full article

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease characterized by parenchymal scarring, increased tissue stiffness, and impaired gas exchange. This study investigates the fluid dynamics and structural response of central airways in both healthy and fibrosis-inspired lungs under a 50% increased flow demand. A three-dimensional airway geometry was reconstructed from computed tomography (CT) scans up to the fifth bronchial generation using a hybrid modeling approach. Transient computational fluid dynamics (CFD) simulations of inhalation and exhalation were performed using ANSYS Fluent with the SST k-ω turbulence model. A complementary static structural analysis was conducted to assess deformation and stress under pleural pressure loading. The results indicate that fibrosis-inspired lungs required 92% higher inlet pressure losses compared to healthy lungs, highlighting the increased energetic cost of breathing. Flow patterns remained qualitatively similar. Structurally, fibrosis-inspired tissue exhibited 17% lower equivalent elastic strain under the same pressure load, confirming the impact of increased stiffness on bronchial distensibility. Maximum principal stress concentrations of 22.1 kPa were identified at the left main bronchus bifurcation, indicating potential mechanical stress hotspots. Full article

Background: Hypervirulent Klebsiella pneumoniae (K. pneumoniae) easily causes bacteremia and liver abscess, and invades the eye via blood circulation to trigger blinding endogenous endophthalmitis. Widespread multidrug resistance limits antibiotic treatment, while traditional capsular polysaccharide vaccines cannot provide cross-serotype protection. Methods: We established a mouse model of intraperitoneal infection-induced endogenous endophthalmitis. BALB/c mice received two intramuscular injections of LNP-encapsulated PstS-YidR fusion mRNA vaccine, followed by challenge with hypervirulent K1 or K2 strains. We monitored body weight, quantified multi-tissue bacterial loads, detected IL-1β, IL-6 and TNF-α, and performed slit-lamp observation and liver/ocular histopathology. Results: The vaccine relieved systemic symptoms and weight loss, suppressed bacterial dissemination across peritoneal, blood, liver, lung and eye tissues, and reduced excessive inflammatory factor release. It alleviated intraocular suppurative lesions, preserved ocular structure, and mitigated liver abscess and hepatocellular necrosis, with equal protective efficacy against K1 and K2 and favorable in vivo safety. Conclusions: The PstS-YidR fusion mRNA vaccine blocks systemic spread and intraocular invasion of hypervirulent K. pneumoniae and alleviates multi-organ inflammatory damage. It serves as a safe candidate vaccine for preventing K1/K2-type hypervirulent Klebsiella infections and endogenous endophthalmitis. Full article

Nanocrystalline (NC) alloys hold significant promise as structural alloys due to their superior mechanical properties over the traditional coarser grained microcrystalline alloys. Often, there is an optimal range of mean grain size for most metals about which maximum material strength can be realized. In the context of NC alloys, stabilization of the grain size in this optimal range is one of the primary synthesis challenges. A large volume fraction of NC alloy microstructure is occupied by grain boundaries (GBs). Since GBs increase the internal surface energy of the system, during solidification and grain growth phases, there is a tendency to minimize GBs through grain coarsening. However, in NC alloys, phenomena like GB–solute segregation and solute precipitation are active and mitigate grain growth and thus stabilize the desired small grains. Numerically modeling these phenomena of GB–solute interactions, and the evolution of these stabilized GBs under mechanical load, is of immense interest to the NC alloy community. To enrich the numerical modeling formulations available in this space, we present here a phase-field-method-based numerical framework to model GB segregation, solute precipitation and effect of external loading on NC alloys. While some of these effects have been modeled in isolation, a unified treatment of the solute–GB segregation-related effects and its coupling with mechanics has not be considered in the literature. We present a three-dimensional, finite element method (FEM)-based, finite-strain phase-field formulation for modeling grain evolution and microstructure stabilization in NC alloys. Beyond the formulation and its computational implementation, various case studies demonstrate the applicability of this framework. Further, thermodynamic and kinetic arguments are provided based on the evolution of GB energy to explain the effects of solute drag, GB pinning and mechanical deformation. Full article

Porcine rotavirus A (PoRVA) is an important cause of diarrhea in neonatal piglets, resulting in significant economic losses in the swine industry. In this study, a PoRVA strain, designated QY, was isolated from diarrheic piglets and systematically characterized. The virus was propagated in MA104 cells and identified by immunofluorescence assay and transmission electron microscopy, showing typical cytopathic effects and spherical particles of approximately 70 nm. Whole-genome sequencing and phylogenetic analysis revealed that QY was a G4P[13] strain with a genotype constellation of G4–P[13]–I1–C1–M1–R1–A8–N1–T1–E1–H1. Several genome segments showed close phylogenetic relationships with human- or bat-associated RVA strains, a pattern consistent with a possible reassortment history of QY. Experimental infection showed that QY caused watery diarrhea, intestinal lesions, and viral shedding in neonatal piglets under the experimental conditions used in this study. High viral loads were detected in small intestinal tissues, accompanied by villous atrophy and epithelial degeneration. These findings provide new insights into the genetic diversity and evolution of PoRVA and further characterize the pathogenicity of the G4P[13] QY strain in neonatal piglets. Full article

Ultra-deep circular shafts are increasingly deployed in congested urban environments, yet their structural performance in highly sensitive soft clay remains susceptible to diaphragm wall panel joints, structural imperfections, and complex interactions with adjacent structures. This study presents a high-fidelity three-dimensional (3D) numerical investigation into the excavation behavior of an ultra-deep circular shaft with a diameter of 30 m and an excavation depth of 56.3 m in Shanghai soft clay by synthesizing high-resolution field monitoring with advanced finite element modeling. The numerical framework was established in PLAXIS 3D utilizing the Hardening Soil model with small-strain stiffness (HSS), explicitly incorporating an equivalent structural stiffness reduction scheme (0.8 vertically and 0.5 circumferentially) to capture panel segmentation, joint compliance, and concrete cracking. The reduced-stiffness model successfully reproduces the measured deep-seated bulging profiles and internal force distributions with high fidelity. The findings reveal exceptional deformation control capabilities of the circular geometry, yielding a maximum lateral wall deflection of merely 9.1 mm (0.016%H_e), which is significantly smaller than the normalized deformation ratio of 0.3%H_e observed in five analogous rectangular excavations in Shanghai. The numerical results indicate that circumferential compression governs the overall load transfer behavior, while vertical bending response remains relatively limited. Furthermore, a pronounced circumferential anisotropy in wall deformation is governed by asymmetric boundary conditions, where localized Metro Jet System (MJS) ground improvement significantly restrain movements, whereas the non-grouted area experience peak deflections. Crucially, interaction with the adjacent external diaphragm walls of ancillary structures induces a complex 3D stress redistribution rather than a beneficial shielding effect, amplifying the peak shaft wall displacement by nearly 62.8% (from 4.73 mm to 7.70 mm). These insights underscore the criticality of integrating small-strain soil mechanics, equivalent structural degradation, and adjacent structural boundaries into predictive design protocols for ultra-deep circular retaining systems. Full article

GFRP-reinforced concrete structures often suffer from insufficient ductility and limited crack control capability. This study investigates the flexural behavior of ECC–concrete composite beams reinforced with steel–FRP composite bars (SFCBs) using finite element analysis. A three-dimensional nonlinear finite element model was developed in ABAQUS and validated against four-point bending tests of eight composite beam specimens. The model incorporated a bilinear constitutive relationship for SFCBs and a cohesive interface model to simulate the interaction between ECC and concrete. Based on the validated model, the effects of reinforcement type and ECC replacement height on the flexural performance of composite beams were evaluated. The results showed that the proposed model accurately reproduced the load–deflection responses, strain development, and failure processes of the tested beams. The reinforcement type significantly affected the overall structural behavior, resulting in different load-carrying characteristics and deformation responses. Increasing the ECC replacement height mainly improved the cracking resistance by increasing the cracking load and promoting a more uniform crack distribution, while its effects on the yield and ultimate loads were limited. ECC primarily contributed to crack control and damage mitigation, whereas SFCBs influenced the overall load-carrying behavior of the composite beams. These findings provide insights into the design and performance evaluation of ECC–concrete composite beams reinforced with SFCBs. Full article

Grouted connection segments are key load-transfer components in offshore wind jacket structures, and their axial compressive performance is essential for the safety and reliability of the foundation system. This paper develops a finite element model of a grouted connection segment incorporating steel-fiber-reinforced high-strength grout to investigate its mechanical behavior and parametric effects under axial compression. A 1:7-scale model test is conducted to verify the numerical model through comparisons of the load–displacement response and strain responses at key locations. The steel tubes are simulated using a trilinear hardening elastoplastic model, while the steel-fiber-reinforced high-strength grout is represented using the concrete damaged plasticity model with corresponding tensile and compressive constitutive relationships and damage parameters to characterize its nonlinear response. Based on the validated model, a full-scale numerical model is established to analyze the effects of steel tube thickness, shear key spacing, shear key height, and shear key width using the control variable method. The results indicate that steel tube thickness has the most significant influence on the ultimate bearing capacity and can improve the load-bearing capacity and ductility of the structure. Shear key spacing mainly affects axial stiffness and deformation compatibility, while shear key height and width have limited effects on the ultimate bearing capacity but contribute to local deformation control and stiffness enhancement. The findings provide a validated numerical basis for evaluating the axial compressive behavior of steel-fiber-reinforced grouted connections and offer a useful reference for the design and parameter optimization of grouted connection segments in deep-water offshore wind jacket structures. Full article

Coral aggregate seawater concrete (CASC) capitalizes on locally sourced aggregates in marine and reef engineering, enabling in situ material utilization and conferring marked benefits in curbing conventional resource consumption and construction expenditures—a combination that underpins its considerable promise for reef infrastructure development. To date, research efforts have largely been confined to macroscopic mechanical characterization and qualitative microstructural inspections, and quantitative assessments of mesoscopic damage evolution across the full loading-to-failure process remain relatively scarce. In response, to quantitatively characterize the mesoscopic damage evolution mechanism of CASC with different natural aggregates, the present study draws upon statistical damage theory and incorporates uniaxial compressive stress–strain responses from CASC mixtures formulated with four replacement ratios (0%, 33%, 67%, and 100%) of natural coarse and fine aggregates, thereby establishing a statistical damage constitutive model. The model is intentionally structured to decipher the intricate interplay that translates progressive mesoscopic deterioration into the eventual macroscopic mechanical signature, rather than merely describing phenomenological curves. The outcomes reveal favorable concordance between model-generated predictions and experimental measurements. Introducing natural aggregates appreciably modulates the cumulative damage trajectory at the mesoscale; with rising replacement ratios, the macroscopic mechanical performance of CASC is systematically fortified, concomitant with orderly shifts in characteristic damage indices (ε_a, ε_b, ε_h and H). Specifically, when the replacement ratio of natural fine aggregate is fixed at 0%, as the replacement ratio of natural coarse aggregate increases from 0% to 100%, the values of ε_a, ε_b, ε_h, and H increase by 35.8%, 36.9%, 32.2%, and 66.5%, respectively. Additionally, both the fracture damage variable D_R and the integrated transverse strain area derived from digital image correlation (DIC) exhibit monotonic ascending trends as loading advances. Collectively, these contributions offer a theoretical foundation for performance optimization and a deeper mechanistic understanding of damage behavior in CASC. Full article

Carbon-fiber-reinforced polymer (CFRP) composites fabricated with bio-based epoxy resins represent a promising approach for sustainable lightweight structures produced by out-of-autoclave (OoA) technologies. The curing schedule influences the state of the epoxy matrix and, consequently, can affect the fiber–matrix interaction and laminate performance. This study investigates the effect of practical curing conditions on 2 × 2 twill woven carbon fiber laminates fabricated by vacuum infusion using a commercially available bio-based epoxy resin IB2. The manufacturer’s recommended room-temperature conditions (25 °C for 24 h) were compared with accelerated mold heating schedules at 40, 50, 60, and 70 °C for 12 h. The laminates were characterized by three-point tensile and flexural tests, heat deflection temperature (HDT) measurements, differential scanning calorimetry (DSC), and SEM fractography. The tensile response showed limited sensitivity to the investigated curing conditions, with mean tensile strengths ranging from 634.01 to 672.95 MPa; T60 exhibited the highest mean numerical tensile strength (672.95 ± 53.60 MPa) and tensile modulus (53.39 ± 11.53 GPa), although the differences were small relative to the experimental spread. In contrast, the flexural response was more sensitive to the processing conditions. T70 exhibited the highest average flexural strength (980.60 ± 129.03 MPa), strain at maximum flexural stress, and strain energy density to maximum stress (8.75 ± 1.89 MJ/m³). The heat deflection temperature (HDT) systematically increased from 65.20 °C for T25 to 85.83 °C for T70. DSC revealed clear differences in the calorimetric response after curing during the first heating cycle, while the glass transition temperatures at the middle of the second heating occupied a relatively narrow range of 80.9–85.6 °C. SEM fractography revealed mixed tensile failure mechanisms related to fibers, matrix, and interface under all curing conditions. Overall, the results demonstrate that accelerated 12 h heated mold programs can reduce cure time while maintaining tensile performance generally comparable to the 24 h room-temperature IB2 reference condition and providing higher average flexural performance and thermal deformation resistance under load. These findings establish processing–property relationships relevant to the development of biomass-based CFRP OoA laminates for lightweight aerospace applications. Full article

A demand-oriented spatial reinforcement scheme was developed for circular anti-slide piles subjected to a known dominant direction of landslide thrust. Based on the depth-dependent bending-moment and shear-force demands, the proposed scheme integrates uniformly distributed full-length base bars, supplementary longitudinal reinforcement concentrated within the principal tension sector, depth-dependent termination of longitudinal bars, and variable-pitch spiral reinforcement. A three-dimensional nonlinear finite-element model was established to compare the proposed scheme with a conventional circumferentially uniform reinforcement arrangement under identical geometrical, material, loading, and boundary conditions. The results showed that the proposed scheme reduced the total reinforcement volume from 1.243 to 1.041 m³, corresponding to a reduction of 16.3%. At 40% of the design load, the pile-head displacement increased slightly by 3.96%, indicating a minor reduction in initial stiffness. Under the full design load, however, the pile-head displacement, maximum longitudinal-bar stress, and maximum equivalent plastic strain decreased by 5.48%, 15.7%, and 34.5%, respectively. The concrete damage distribution also became more localized and discontinuous near the critical region. These results demonstrate that demand-oriented spatial reinforcement can improve reinforcement utilization, reduce local response concentration, and enhance deformation control under high load levels while achieving substantial steel savings. Full article

Reinforced concrete (RC) beams undergo axial elongation during inelastic flexural deformation. In frame structures, this elongation is restrained by adjacent columns and slabs, inducing axial compression and beam overstrength, thereby amplifying force demands on columns and joints. Although previous studies have examined beam elongation restraint in planar frames and slab participation in isolated beam–column subassemblies, the combined restraint provided by columns and continuous floor slabs in spatial frame systems remains insufficient. This study conducted static vertical loading tests on twelve restrained RC beams within a three-dimensional frame system. The beams were detailed to reduce the mid-span flexural resistance, allowing the beam-end plastic hinges to contribute predominantly to the response. Compared with the unrestrained beams, the restrained frame beams developed more pronounced flexural–shear crack patterns in the beam-end plastic hinge regions and were more prone to premature concrete crushing before tensile rebar yielding under stronger spatial restraint. Higher spatial restraint also limited the tensile strain development of slab rebars, reducing the effective overhanging flange width. The restraint-induced axial compression ratios ranged from 0.13 to 0.46, and the combined effect of axial compression and slab contribution increased the beam-end flexural strength by 57% to 225%. Compared with the tensile contribution of slab rebars, restraint-induced axial compression was the dominant source of strength enhancement, accounting for 64% to 86% of the total enhancement. These findings highlight the need to consider spatial restraint in RC beam design. Full article

Unsaturated polyester polymer concrete (UPPC) is a promising rapid repair material for pavement engineering, while the age-dependent and rate-dependent bonding behaviors between UPPC and ordinary Portland concrete (OPC) substrate remains poorly understood, restricting its application in heavy-traffic scenarios. This study systematically investigates the quasi-static and dynamic bond performance of the UPPC-OPC interface at four curing ages (1 d, 3 d, 7 d, 28 d) under flexural loads. Quasi-static three-point bending tests show that the 28 d interfacial bond strength reaches 4.62 MPa, 97% higher than that of the OPC-OPC control group. Dynamic flexural tests via a 100 mm diameter split Hopkinson pressure bar reveal the strain-rate effect of the dynamic increase factor (DIF). DIF decreases below 1.0 at low strain rates (<10 s⁻¹) due to weakened viscoelastic stress relaxation of partially cured unsaturated polyester resin, while it rises above 1.0 at higher strain rates induced by polymer hardening and inertial confinement. Combined with scanning electron microscopy characterization, the coupling relationship between curing age, strain rate and interfacial failure mode is further clarified. This work provides fundamental insights into the rate-dependent behaviors of polymer–cement heterogeneous interfaces, and offers theoretical guidance for the design of UPPC-based rapid repair systems. Full article

This paper presents a case study of a road embankment affected by landslide activity that was subsequently stabilised using geocell reinforcement. The project involved a temporary accessway, approximately 80 m long and 8 m wide, located along Wattamolla Road, NSW, Australia. Stability assessments were undertaken using finite element modelling to evaluate the influence of geocell confinement on embankment performance. Unlike conventional approaches, in which geocell reinforcement is represented as an equivalent composite soil layer with increased apparent cohesion and unchanged friction angle, this study explicitly models the reinforced layer as granular soil subjected to externally applied lateral confining pressures. The behaviour predicted using this methodology was compared with that obtained from the traditional equivalent composite soil approach. The analyses indicate that even relatively low confining pressures significantly reduce lateral spreading of the infill material, promoting a more uniform strain distribution and reducing localised deformation. The results further demonstrate that geocell-induced confinement improves stress transfer within the reinforced layer and enhances embankment performance under traffic loading. In addition, the study shows that confinement is stress-dependent, with increasing surcharge loads mobilising greater hoop stresses within the geocell system and, consequently, generating higher levels of lateral confinement. The results suggest that modelling geocell reinforcement through stress-based confinement provides a more realistic representation of reinforcement mechanisms and offers valuable insights for the analysis and design of reinforced earth structures. By improving embankment stability and controlling deformation, geocell reinforcement may also extend infrastructure service life, minimise disruption associated with maintenance or slope failure and reduce dependence on more material-intensive stabilisation solutions. Collectively, these benefits contribute to resource efficiency, infrastructure resilience, and reduced whole-of-life intervention requirements. Full article