Search Results (88)

Due to their high strength-to-weight ratio and corrosion resistance, glass fiber reinforced polymer (GFRP) composites have been used in various civil structures. However, the GFRP profiles may be perforated to allow bolting, wiring, and pipelining, causing stress concentration and safety concerns in load-carrying scenarios. A fundamental understanding of the stress concentration mechanisms and the efficacy of mitigation techniques in such anisotropic materials remains limited, particularly for the complex stress states introduced by perforations and mechanical fasteners. This study investigates the effectiveness of three techniques, adhesive filling, bolt reinforcement, and elliptical perforation design, in mitigating stress concentration and enhancing the strength of perforated GFRP plates. The effects of perforation geometry, filler modulus, bolt types, and applied preloads on the stress concentration and bearing capacity are investigated through experimental and finite element analysis. The results reveal that steel bolt reinforcement significantly improves load-bearing capacity, achieving a 13.9% increase in the pultrusion direction and restoring nearly full strength in the transverse direction (4.91 kN vs. unperforated 4.89 kN). Adhesive filling shows limited effectiveness, with minimal load improvement, while elliptical perforations exhibit the lowest performance, reducing strength by 38% compared to circular holes. Stress concentration factors (SCF) vary with hole diameter, peaking at 5.13 for 8 mm holes in the pultrusion direction, and demonstrate distinct sensitivity to filler modulus, with optimal SCF reduction observed at 30–40 GPa. The findings highlight the anisotropic nature of GFRP, emphasizing the importance of reinforcement selection based on loading direction and structural requirements. This study provides critical insights for optimizing perforated GFRP components in modular construction and other civil engineering applications. Full article

The thermal, thermomechanical, and viscoelastic properties of continuous unidirectional (UD) glass fiber/high-density polyethylene (GF/HDPE) and ultra-high-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) tapes are characterized in this paper in order to support their use in extreme environments. Unlike prior studies that focus on short-fiber composites or limited thermal conditions, this work examines continuous fiber architectures under five operational environments derived from Army Regulation 70-38, reflecting realistic defense-relevant extremes. Differential scanning calorimetry (DSC) was used to identify melting transitions for GF/HDPE and UHMWPE/HDPE, which guided the selection of test conditions for thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA). TMA revealed anisotropic thermal expansion consistent with fiber orientation, while DMA, via strain sweep, temperature ramp, frequency sweep, and stress relaxation, quantified their temperature- and time-dependent viscoelastic behavior. The frequency-dependent storage modulus highlighted multiple resonant modes, and stress relaxation data were fitted with high accuracy (R² > 0.99) to viscoelastic models, yielding model parameters that can be used for predictive simulations of time-dependent material behavior. A comparative analysis between the two material systems showed that UHMWPE/HDPE offers enhanced unidirectional stiffness and better low-temperature performance. At the same time, GF/HDPE exhibits lower thermal expansion, better transverse stiffness, and greater stability at elevated temperatures. These differences highlight the impact of fiber type on thermal and mechanical responses, informing material selection for applications that require directional load-bearing or dimensional control under thermal cycling. By integrating thermal and viscoelastic characterization across realistic operational profiles, this study provides a foundational dataset for the application of continuous fiber thermoplastic tapes in structural components exposed to harsh thermal and mechanical conditions. Full article

Peach (Prunus persica (L.)) fruits are abundant in nutrients, with fruit shape and sugar content serving as critical indicators of fruit quality. Melatonin plays a pivotal role in peach fruit development; however, the mechanisms by which it regulates fruit shape development, sugar metabolism, and secondary metabolites remain largely unknown. In this study, peach trees were sprayed with 150 µM melatonin 20 days after pollination. Traditional methods were used to investigate fruit morphology, total soluble solids (TSSs), and titratable acidity content (TAC), while liquid chromatography–mass spectrometry (LC-MS) was employed to analyze sugar metabolites during fruit development. The results indicated that melatonin treatment augmented the transverse and longitudinal diameters of peach fruits by 12% and 6%, respectively, and elevated the contents of soluble solids and titratable acid by 7% and 6%, respectively. The single fruit weight experienced a significant increase of 29.4%, whereas fruit firmness at maturity remained unchanged. Metabolite analysis demonstrated that melatonin decreased the levels of sucrose and D-sorbitol in mature fruits but enhanced the accumulation of D-fructose, L-rhamnose, and xylose. Significantly, melatonin expedited the degradation of galactose, D-mannose, and methyl-D-pyranogalactoside prior to maturity (all three substances naturally decline with fruit ripening), highlighting its role in promoting fruit ripening. In conclusion, exogenous melatonin improves the internal nutrition and flavor quality of fruit by regulating the accumulation of primary and secondary metabolites during fruit ripening. Specifically, the increase in D-fructose (a major contributor to sweetness) and L-rhamnose (a potential precursor for aroma compounds) enhances fruit flavor profile. The accelerated degradation of galactose, D-mannose, and methyl-D-pyranogalactoside (components of cell wall polysaccharides) prior to maturity, alongside the metabolic shift favoring fructose accumulation over sucrose, highlights melatonin’s role in promoting fruit ripening and softening processes. It also promotes fruit enlargement and single fruit weight without affecting fruit firmness. This study establishes a theoretical basis for the further investigation of the molecular mechanisms underlying melatonin’s role in peach fruits and for enhancing quality-focused breeding practices. Full article

Introduction: This manuscript addresses the limitations of traditional orthognathic surgery in achieving both functional and aesthetic correction in patients with Class II malocclusion and severe mandibular retrusion. Current techniques often struggle to simultaneously address mandibular deficiency and inadequate transverse dimension, leading to unsatisfactory outcomes. Methods: Seven male patients underwent bimaxillary osteotomy with mandibular advancement. A novel surgical plate, Implate, was used, which was designed to facilitate precise osteotomy and stabilization. Pre-surgical planning included CBCT scanning, 3D modeling, and surgical simulation. Postoperative assessments included clinical examinations, CT and OPT scans. Results: Implate successfully addressed the challenges of conventional techniques, minimizing the formation of bony steps and achieving a more harmonious facial profile. The minimally invasive procedure, with careful periosteal and muscle management, contributed to stable outcomes, and no complications were reported. At the 6-month follow-up, OPT analysis showed a mean mandibular width increase of 18.1 ± 6.2 mm and vertical ramus height gains of 6.0 ± 3.1 mm (left) and 5.8 ± 1.7 mm (right). Conclusions: According to our preliminary experience, the integration of Implate into surgical practice offers a significant improvement in treating complex Class II malocclusions. By simultaneously correcting mandibular retrusion and width while minimizing complications, Implate provides a superior solution compared to traditional methods. This innovative approach highlights the potential of combining advanced surgical techniques with personalized 3D-printed implants to achieve optimal functional and aesthetic outcomes. Further prospective studies with controls and longer follow-up are needed to validate the efficacy and reproducibility of Implate in wider clinical use. Full article

Background: The behavior of soft tissues following recession type 1 (RT1) and/or non-carious cervical lesions (NCCLs) treated with class V restorations is not well understood. These conditions cause both functional and esthetic issues. Recent studies show that increased cervical thickness can influence gingival tissue response. This suggests that restoration design has a key impact. This study aims to evaluate the effect of tooth shape modification on gingival tissue response and periodontal health with 3D analysis. Methods: Seven patients with buccal gingival recession and NCCL were selected, resulting in 50 treated teeth. Patients underwent class V buccal restorations using the BOVR technique. Three-dimensional evaluation through scanned dental impressions was performed at baseline and at T1 to monitor tissue profile changes in the buccal zenith sagittal plane. The average observation period was 4 months. Following the assessment, linear measurements were calculated according to standard planes. These measurements aimed to monitor transverse and axial tissue modifications. Probing depth, plaque index, and bleeding index were also recorded. Results: Increased tooth thickness led to tissue alteration. Greater composite thickness was significantly associated with an increase in tissue thickness (p ≤ 0.001) and gingival creeping (p ≤ 0.001) at the free gingival margin. Periodontal health remained unaffected, and 50% of the teeth required no additional surgical treatment due to satisfactory outcomes. Conclusions: Class V restorations that increase cervical thickness may promote soft tissue volume gain over a 4-month period without compromising periodontal health. A 4-month observation period is recommended before considering the surgical correction. Full article

Digital light processing (DLP) technology has emerged as a promising approach for fabricating high-precision microfluidic chips due to its exceptional resolution and rapid prototyping capabilities. However, UV energy penetration and resin flow dynamics during layer-by-layer printing introduce significant challenges for microchannel printing, particularly in controlling microchannel over-curing. In this study, a novel 3D DLP over-curing interaction model (DLP-OCIM) was developed to investigate the coupled effects of UV energy penetration and directional resin flow on the over-cured structure formation of microchannels. COMSOL Multiphysics 6.1 simulations incorporating UV light propagation, photopolymerization kinetics, and resin flow dynamics revealed that microchannel over-curing is a result of both energy infiltration through previously cured layers and periodic resin flow induced by the peeling process. Experimental validation using linear and annular microfluidic chips demonstrated that increasing layer thickness induces progressive over-curing, leading to inclined cross-sectional structures. Additionally, the microchannel geometry and size significantly influence resin flow patterns, with shorter transverse microchannels producing flatter over-cured profiles compared to their longitudinal counterparts. This study provides the first comprehensive analysis of the dynamic interplay between UV energy penetration and resin flow during DLP-based microchannel fabrication, offering valuable process insights and optimization strategies for enhancing shape fidelity and printing accuracy in high-resolution microfluidic chips. Full article

This study focused on analyzing the impact of ground-penetrating radar (GPR) scan spacing on accurately assessing the reinforcement of concrete bridge girders, providing practical insights. A decommissioned bridge box beam was evaluated to unveil rebars and tendons’ depth and spacing. The box beam was decommissioned from the West Virginia Division of Highways inventory. An innovative algorithm was developed to fully automate the analysis of survey grid data across all sides of the beam. Implementing this algorithm into a computer code has paved the way for comprehensive automation of GPR data analyses. Comparing GPR data analyses from various profile line offsets, this study assists in producing optimal protocols for inspecting box beams. Transverse profile line offsets between 4 in. and 24 in. yielded nearly identical results, setting a new standard for precision. Utilizing more than one longitudinal profile line was highly beneficial in accurately assessing prestressed concrete box beams. This research helps redefine bridge evaluation by precisely finding rebar spacing, concrete cover, and other internal characteristics. This study’s findings offer invaluable advancements and equip state departments of transportation with the knowledge to accurately assess in-service concrete bridge box beams, empowering them to make informed decisions. Full article

Linerless composite pressure vessels, or type V pressure vessels, are gaining increased interest in the transportation industry because they offer improved storage volume and dry weight, especially for low-pressure cryogenic storage. Nevertheless, the design and manufacturing of this type of pressure vessel bring several challenges due to the inherent difficulties in the manufacturing process implementation, assembly, and related analysis of structural integrity due to the severe operating conditions at cryogenic temperatures that should be taken into consideration. In this work, a novel analysis procedure using a finite element model is developed to perform an end-to-end simulation of a linerless pressure vessel, including the relevant features associated with automated fiber placement manufacturing processes regarding thickness and tape profiles, followed by an analysis of the structural response under service conditions. The results show that residual stresses from manufacturing achieve values near 50% of the composite ply transverse strength, which reduces the effective ply transverse load carrying capacity for pressure loading. Transverse damage is triggered and propagated across the vessel thickness before fiber breakage, indicating potential failure by leakage, which was confirmed by hydrostatic tests in the physical prototype at 26 bar. The cryogenic condition analysis revealed that the thermal stresses trigger transverse damage before pressure loading, reducing the estimated leak pressure by 40%. These results highlight the importance of considering the residual stresses that arise from the manufacturing process and the thermal stresses generated during cooling to cryogenic conditions, demonstrating the relevance of the presented methodology for designing linerless cryogenic composite pressure vessels. Full article

In this work, we conducted a numerical analysis to investigate the combined effect of thermal lensing and bending-induced mode distortion on transverse mode instability in conventional large-mode-area (LMA) step-index fibers. Utilizing the finite element method, conformal mapping, and thermal conduction equations, we simulated the mode profiles in LMA 20/400 and 25/400 fibers subjected to both bending and thermal lensing effects; the corresponding evolution of mode loss and effective area were explored as well. Additionally, by introducing the derived mode profiles to the TMI coefficient calculations, we analyzed the influence of bending and thermal lensing (TL) on TMI; the simulation results indicate that the mode distortion caused by bending and the TL effect, under the bending conditions commonly encountered in practice, do not have pronounced impacts on TMI coefficient and TMI threshold. Full article

Due to its inherent advantages, shield tunnelling has become the primary construction method for urban tunnels, such as high-speed railway and metro tunnels. However, there are numerous technical challenges to shield tunnelling in complex geological conditions. Under the disturbance induced by shield tunnelling, sandy pebble soil is highly susceptible to ground loss and disturbance, which may subsequently lead to the risk of surface collapse. In this paper, large-diameter slurry shield tunnelling in sandy pebble soil is the engineering background. A combination of field monitoring and numerical simulation is employed to analyze tunnelling parameters, surface settlement, and deep soil horizontal displacement. The patterns of ground disturbance induced by shield tunnelling in sandy pebble soil are explored. The findings reveal that slurry pressure, shield thrust, and cutterhead torque exhibit a strong correlation during shield tunnelling. In silty clay sections, surface settlement values fluctuate significantly, while in sandy pebble soil, the settlement remains relatively stable. The longitudinal horizontal displacement of deep soil is significantly greater than the transverse horizontal displacement. In order to improve the surface settlement troughs obtained by numerical simulation, a cross-anisotropic constitutive model is used to account for the anisotropy of the soil. A sensitivity analysis of the cross-anisotropy parameter α was performed, revealing that as α increases, the maximum vertical displacement of the ground surface gradually decreases, but the rate of decrease slows down and tends to level off. Conversely, as the cross-anisotropy parameter α decreases, the width of the settlement trough narrows, improving the settlement trough profile. Full article

The L-shaped partially encased steel–concrete composite (PEC) stub column, composed of profile steel, concrete, and transverse links, tends to occupy less space than the rectangle-shaped PEC column when used as side or corner columns. In this study, an axial compression test involving three L-shaped PEC stub columns was conducted to investigate the influence of critical factors on axial compression performance. The test results indicated that the axial compression capacity can be effectively enhanced with an increase in material strength. Furthermore, finite element (FE) analysis was carried out with parameters such as material strength, steel thickness, transverse link spacing, transverse link diameter, transverse link distribution, and longitudinal rebar diameter. The results revealed that the primary failure modes of L-shaped PEC columns were concrete spalling and local buckling of the flange. Additionally, it was found that the increase in steel strength, steel thickness, and transverse link diameter, as well as the decrease in transverse link spacing, significantly improved the axial compression capacity and concrete confinement effect. However, an increase in concrete strength diminished the concrete confinement effect. Additionally, the accuracy of the axial compression capacity calculation methods in the Eurocode 4 and T/CECS719-2010 specifications for L-shaped PEC stub columns was verified. Finally, a calculation method based on the superposition principle incorporating the concrete confinement effect was proposed, and validated by comparing with experimental and FE results. Overall, this study could provide a theoretical basis for the engineering application of L-shaped PEC columns. Full article

The cartographic landscape analysis of Lake Doshne employs geographic landscape methods, GIS cartographic modeling, and geo-ecological analysis. This study includes hydrochemical analysis of the lake’s water mass, focusing on saline blocks, tropho-saprobiological indicators, and specific toxic action indicators. Three geological sections of anthropogenic and pre-Quaternary complexes, along with a geological–lithological transverse profile of the lake basin, were developed. Additionally, a geographical landscape model of the lake’s natural aquatic complex was presented, distinguishing littoral–sublittoral and profundal aquatic sub-tracts and five types of aquafacies with landscape metric assessments. This approach enables a comprehensive analysis and the creation of cartographic models that can serve as a basis for lake cadastre and optimization of the ecological and landscape conditions in local territories. Full article

The presented paper focuses on testing the performance of a SLAM scanner Zeb Horizon by GeoSLAM for the creation of a digital model of a bridge construction. A cloud acquired using a static scanner Leica ScanStation P40 served as a reference. Clouds from both scanners were registered into the same coordinate system using a Trimble S9 HP total station. SLAM scanner acquisition was performed independently in two passes. The data acquired using the SLAM scanner suffered from relatively high noise. Denoising using the MLS (Moving Least Squares) method was performed to reduce noise. An overall comparison of the point clouds was performed on both the original and MLS-smoothed data. In addition, the ICP (Iterative Closest Point) algorithm was also used to evaluate local accuracy. The RMSDs of MLS-denoised data were approximately 0.02 m for both GeoSLAM passes. Subsequently, a more detailed analysis was performed, calculating RMSDs for several profiles of the construction. This analysis revealed that the deviations of SLAM data from the reference data did not exceed 0.03 m in any direction (longitudinal, transverse, elevation) which is, considering the length of the bridge of 133 m, a very good result. These results demonstrate a high applicability of the tested scanner for many applications, such as the creation of digital twins. Full article

The pathogenesis of cyclophosphamide (CY)-induced cardiotoxicity remains unknown, and methods for its prevention have not been established. To elucidate the acute structural changes that take place in myocardial cells and the pathways leading to myocardial damage under high-dose CY treatments, we performed detailed pathological analyses of myocardial tissue obtained from C57BL/6J mice subjected to a high-dose CY treatment. Additionally, we analysed the genome-wide cardiomyocyte expression profiles of mice subjected to the high-dose CY treatment. Treatment with CY (400 mg/kg/day intraperitoneally for two days) caused marked ultrastructural aberrations, as observed using electron microscopy, although these aberrations could not be observed using optical microscopy. The expansion of the transverse tubule and sarcoplasmic reticulum, turbulence in myocardial fibre travel, and a low contractile protein density were observed in cardiomyocytes. The high-dose CY treatment altered the cardiomyocyte expression of 1210 genes (with 675 genes upregulated and 535 genes downregulated) associated with cell–cell junctions, inflammatory responses, cardiomyopathy, and cardiac muscle function, as determined using microarray analysis (|Z-score| > 2.0). The expression of functionally important genes related to myocardial contraction and the regulation of calcium ion levels was validated using real-time polymerase chain reaction analysis. The results of the gene expression profiling, functional annotation clustering, and Kyoto Encyclopedia of Genes and Genomes pathway functional-classification analysis suggest that CY-induced cardiotoxicity is associated with the disruption of the Ca²⁺ signalling pathway. Full article

Acoustic emission monitoring (AEM) has emerged as an effective technique for detecting wire breaks resulting from, e.g., stress corrosion cracking, and its application on prestressed concrete bridges is increasing. The success of this monitoring measure depends crucially on a carefully designed sensor layout. For this, the attenuation of elastic waves within the structure’s material is ideally determined in situ through object-related measurements (ORMs) with a reproducible signal source, typically a rebound hammer. This assumes that the attenuation coefficients derived from rebound hammer tests are comparable to those from wire breaks, thus allowing their results to be directly applied to wire break detection without further adjustments. This study challenges this assumption by analysing attenuation behaviour through an extensive dataset. Employing time-domain and frequency analysis, the research generates attenuation profiles from laboratory experiments and in situ measurements across various girders and bridge structures, extracting the slope and residual standard deviation (RSD). While generally validating this approach, the findings highlight differences in attenuation behaviour from among wire break signals and rebound hammer impulses, whereby the latter potentially underestimates the relevant attenuation of wire breaks by approximately 20%. Consequently, a transfer factor is proposed to adjust ORM results obtained with the rebound hammer for wire break scenarios. It consists of a scaling factor of 1.2 to modify the average attenuation coefficient and a constant term of ±1.0 dB/m to cover a 95% confidence interval, and thus, account for sample scattering. Moreover, the anisotropic attenuation behaviour across different structures was studied, showing that transverse attenuation consistently exceeds the longitudinal, significantly influenced by structural features such as voids. In prefabricated concrete bridges with in situ-cast concrete slabs, transverse signal transmission remains unhindered across multiple elements. Finally, the results provide a valuable reference for the design of sensor layouts in bridge monitoring, particularly benefiting scenarios where direct in situ experiences are lacking. Full article