Search Results (395)

Welded joints in API 5L X70 pipeline steel represent critical locations for pipelines intended for hydrogen service because welding can create microstructural inhomogeneity, stress concentrations, and uneven mechanical properties that can promote hydrogen-assisted degradation. In hydrogen-containing environments, these effects may manifest as reduced ductility, loss of fracture resistance, and increased cracking susceptibility, particularly in the weld metal and heat-affected zone. Therefore, welding procedures for X70 intended for hydrogen applications must be evaluated using systematic mechanical testing and microstructural characterization under defined hydrogen exposure conditions. The study investigates the detrimental effects of hydrogen on the mechanical integrity of pipeline materials, focusing on welded joints of the API 5L X70 steel, a candidate material for use in hydrogen-containing environments. The weldability and structural performance of the X70 pipeline steel joints in hydrogen environments, produced using automated multi-pass metal active gas (MAG) welding, was experimentally studied. Welding was performed on a DN800 pipe with precise control over welding parameters. Comprehensive analyses were conducted on the welded joints, including microstructure examinations, hardness measurements, slow strain rate testing in high-pressure gaseous H₂ with a N₂ baseline and fracture toughness testing. In high-pressure hydrogen SSRT showed a moderate reduction in ductility relative to nitrogen, with reduction of area decreasing from 81.2% (N₂) to 69.1 and 71.5% (H₂), while time-to-failure remained comparable (475 min in N₂ vs. 497 and 496 min in H₂) Ultimate tensile strength was not reduced (579 MPa in N₂ vs. 609 and 597 MPa in H₂). Secondary surface cracks were observed only on specimens tested in hydrogen. Fracture mechanics testing after hydrogen exposure yielded K_IH values of 58–59 MPa√m in the weld metal and 57–61 MPa√m in the HAZ, exceeding the 55 MPa√m acceptance threshold applied in this study. The results highlight the necessity of optimized welding techniques and targeted material analyses to ensure the safety and durability of pipelines in hydrogen-rich environments, thereby contributing to the development of reliable infrastructure for sustainable energy systems. Full article

Atypical joint spaces, such as those encountered in complex segmental bone loss and large structural defects, remain challenging to manage with conventional implants within divisions across orthopedics, including arthroplasty, tumor reconstruction, trauma, and spine. Additive manufacturing advances have made patient-specific implants a possibility, and this promising solution has enabled the creation of implants with customized geometry and controlled surface porosity to enhance osseointegration, reduce rejection rates, optimize biomechanics, and promote longevity. Despite its potential, patient-specific implants are still eclipsed in use by conventional, “off-the-shelf” implants due to their lower cost, documented long-term durability, insurance coverage, and the strength of available clinical evidence supporting their use. This narrative review summarizes current materials and manufacturing approaches for additively manufactured metal porous implants, including imaging and design workflows, lattice and pore architecture, and how the printing process influences implant stiffness, fatigue strength, surface roughness, and porosity. We also discuss the experimental and preclinical data on mechanical performance, fatigue resistance, and osseointegration for new developments in the field. Emerging trends such as material innovation, streamlined digital planning-to-implant workflows, 4D printing and other advanced additive manufacturing concepts, and cost-reduction efforts are examined in the context of clinical practicality. In this review, the integration of engineering principles with early clinical outcomes will provide orthopedic surgeons with a realistic understanding of the benefits and limitations of the future utilization of additive manufacturing in clinical practice. Full article

Welding is a fundamental technique for joining materials in industrial applications and large-scale construction. Various methods are employed to ensure robust connections. Resistance spot welding is ideal for thin sheets due to its speed, low cost, short processing times, and easy integration into automation systems. Stainless steel is widely used in many food and beverage industries because of its durability and ability to withstand diverse conditions. However, despite the existence of modeling approaches, predictive models linking weld parameters to the simultaneous improvement of stiffness and tensile strength in different joint regions remain limited in published studies. Many studies treat the weld as a single homogeneous region or focus primarily on general indicators such as tensile strength or weld diameter. The spatial variation in properties between the weld region, the heat-affected region, and the base metal is often not modeled separately. This study examines the effect of welding current and welding time on the mechanical properties of weld beads. Scanning electron microscopy (SEM) was also used to characterize the weld microstructure. The combination of mechanical evaluation and microstructural analysis provides deeper insight into the relationship between welding parameters and weld quality. Among the conditions studied (6–8 kA, 60–120 ms), the optimal parameters (6 kA, 120 ms) produced the maximum hardness of 178.16 HV observed in the weld zone and a tensile strength of 12 kN. The experimental results demonstrated that welding parameters significantly influence weld bead quality, and the optimization study allowed us to identify the parameters that achieve the best possible mechanical properties and optimal operating conditions. The experimental results demonstrated that welding parameters significantly influence weld bead quality, and the optimization study using Response Surface Methodology (RSM) allowed us to identify the parameters that achieve the best possible mechanical properties and optimal operating conditions. Full article

Background/Objectives: Sacroiliac joint (SIJ) dysfunction is a common yet frequently underdiagnosed cause of chronic low back pain. This study aimed to compare the clinical effectiveness of ultrasound-guided corticosteroid and ozone injections in patients with chronic low back pain due to SIJ dysfunction. Methods: This comparative clinical study included 64 patients with chronic sacroiliac joint (SIJ) dysfunction who received ultrasound-guided SIJ injections with either corticosteroid (n = 31) or ozone (n = 33). Participants had a mean age of 45.0 ± 7.7 years, and the sex distribution was 42/22 (female/male). Pain intensity was assessed using the Numeric Rating Scale (NRS), disability using the Oswestry Disability Index (ODI), and quality of life using the Short Form-12 Physical (PCS) and Mental (MCS) Component Summary scores. Outcomes were evaluated at baseline, 3 months, and 6 months. Longitudinal changes were analyzed using two-way repeated-measures ANOVA (group × time) with Bonferroni-adjusted post hoc comparisons. Effect sizes were calculated using Cohen’s d. Normality and homoscedasticity were assessed (Shapiro–Wilk and Levene tests), and baseline comparisons were performed using appropriate parametric or non-parametric tests. Results: Both treatments significantly improved pain, disability, and quality of life at 3 months (p < 0.01). However, improvements were significantly greater and more durable in the ozone group across all outcomes at both 3 and 6 months (p < 0.01). At 6 months, between-group differences favored ozone for NRS (mean difference −2.81; Cohen’s d = −2.36), ODI (−6.05; d = −1.46), SF-12 PCS (+4.24; d = 1.24), and SF-12 MCS (+4.22; d = 0.83). A ≥50% pain reduction was achieved at 3 months in 97.0% of ozone-treated patients versus 45.2% of corticosteroid-treated patients (p < 0.01) and persisted at 6 months in 18.2% and 0% of patients, respectively (p < 0.05). The magnitude of improvement in the ozone group exceeded commonly reported Minimal Clinically Important Difference (MCID) thresholds for chronic low back pain outcomes, supporting clinical relevance. Conclusions: Ultrasound-guided ozone injection provided greater and more durable improvements in pain relief, functional status, and quality of life compared with corticosteroid injection in patients with SIJ dysfunction. Full article

Polymer–ceramic hybrid composites are emerging as attractive candidates for lightweight, corrosion-resistant absorber components in solar thermal collectors; however, their adoption is constrained by the intrinsically low thermal conductivity of polymers, processing-induced anisotropic heat transport, interfacial thermal resistance at tube/laminate joints, and durability challenges under outdoor exposure. This review provides a collector-centered synthesis of polymer–ceramic hybrid materials, emphasizing the translation of composite properties into collector-level outcomes rather than conductivity enhancement alone. A structure–property–performance mapping approach is presented to connect directional thermal conductivity ((k_in-plane), (k_perp)), thermal diffusivity, heat capacity, coefficient of thermal expansion, and service temperature with collector performance parameters such as heat removal effectiveness, overall heat losses, and stagnation behavior. Ceramic fillers (e.g., boron nitride, aluminum nitride, silicon carbide, alumina) are examined for stable conduction-network formation, coating compatibility, and long-term reliability, while carbon fillers (graphite, graphene nanoplatelets, carbon nanotubes) are evaluated for combined heat spreading and solar absorption benefits, with attention to emissivity penalties. Hybrid ceramic–carbon architectures and multilayer absorber designs are identified as the most promising routes to balance thermal transport, optical selectivity (high solar absorptance and low thermal emittance), manufacturability, and durability under UV, humidity, and thermal cycling. Full article

Articular cartilage is a highly specialized connective tissue essential for joint function, providing load-bearing capacity, shock absorption, and near-frictionless motion. Due to its avascular nature, articular cartilage has a limited intrinsic healing capacity, and focal injuries often progress to degenerative joint diseases such as osteoarthritis, leading to chronic pain and functional impairment. This review examines current and emerging scientific, clinical, and technological strategies for articular cartilage repair and regeneration, with particular emphasis on their translational relevance. This narrative review integrates data from peer-reviewed literature, clinical trial registries, and patent databases. Preclinical and clinical approaches are discussed, including orthobiologics, cell-based therapies, advanced biomaterials, and three-dimensional tissue-engineered scaffolds. Bibliometric and keyword network analyses are used to identify dominant research themes, technological trends, and emerging innovations. The findings reveal a clear paradigm shift from conventional surgical interventions, often associated with fibrocartilage formation and suboptimal biomechanical performance, to multifactorial regenerative strategies combining cells, bioactive signals, and biomimetic scaffolds designed to recapitulate the native extracellular matrix. This convergence of regenerative medicine, tissue engineering, and biomaterials science is reflected in growing clinical translation efforts and intellectual property activity. Overall, although articular cartilage repair remains a significant clinical challenge, integrated regenerative approaches show great potential for achieving durable and functional cartilage regeneration. Full article

Recently, epoxy resin concrete (ERC) has shown significant potential in rapid repair applications, such as bridge expansion joints, owing to its early strength gain, rapid hardening, excellent adhesion, and durability. Based on the background of rapid repair scenarios for small- and medium-span bridges, this study designed a mix proportion of ERC. A systematic investigation was conducted on its mechanical properties and constitutive model under various curing temperatures (5 °C, 20 °C, and 35 °C) and ages. Experimental results indicate that the designed ERC cures within 2 to 6 h and achieves a compressive strength of 15 MPa at 1 day, meeting the requirement for early traffic reopening. Both material strength and elastic modulus increase significantly with age, reaching a compressive elastic modulus of 16 GPa at 90 days. Based on the measured uniaxial compressive and tensile stress–strain data, a temperature-dependent constitutive model was established. The fitting parameters exhibit a quadratic functional relationship with curing temperature. The model demonstrates high fitting accuracy under all tested conditions (R² ≥ 0.9293). This study provides a theoretical basis and data support for the application and numerical simulation of ERC in bridge engineering. Full article

Introduction: Disc displacement with reduction (DDwR) and myalgia are among the most common temporomandibular disorders, frequently affecting young adults. While conservative therapy is considered the first-line approach, the evidence on long-term outcomes is still limited. Case Presentation: A 22-year-old female had a 7-month history of left-sided TMJ clicking, deviation to the left during opening, and 2 months of bilateral masticatory pain, which was worsened by mastication. During clinical examination, reproducible left TMJ clicking and tenderness of the masseter and temporal muscles were observed. Based on DC/TMD Axis 1, DDwR with myalgia diagnosis was made. Intervention and Results: A full maxillary stabilization splint was constructed and delivered together with patient education, dietary adjustments, and guided mandibular exercises. At baseline, pain intensity was VAS 6/10 with a maximum unassisted mouth opening of 41 mm and reproducible joint clicking. After 2 weeks, the patient reported a decrease in pain, VAS 2/10, mouth opening was 44 mm, and joint sounds were absent. After 1 year, the patient was asymptomatic (VAS 0/10) with stable function, preserved mouth opening, and completion of daily activities without limitations. Clinical Relevance and Conclusions: This case shows that multi-directional non-invasive therapy can result in complete and long-term remission of DDwR with myalgia. It emphasizes the need for careful diagnosis, through standardized instruments such as DC/TMD, and the need for personalized treatment to ensure durable clinical success. Full article

The use of carbon fiber-reinforced plastic (CFRP) components has increased significantly in civilian aviation, necessitating effective maintenance and repair strategies to ensure durability and performance. While prior studies have focused on composite repair methods, such as stepped scarf patch and bolted joint repairs, these were limited to specimen and panel levels without addressing full-scale wing models. This study bridges that gap by evaluating stepped-lap repairs on a full-scale composite wing model under realistic loading conditions and exploring various repair scenarios. To reduce computational cost, two-dimensional shell elements were employed to simulate repairs, with results validated using experimental tensile test data from stepped-lap repaired specimens. Numerical models were developed for single regions and two closely located repair regions. For single-region repairs, adding up to two extra layers enhanced mechanical strength, but three extra layers increased strain, diminishing performance. For two closely located repairs, additional layers improved strength, though less effectively than single-region repairs. Square-shaped repairs exhibited higher strain due to stress concentrations at the corners, while circular repairs showed more uniform stress and strain distribution. These findings emphasize the importance of optimizing repair geometry and layer configurations using numerical simulations to ensure optimal structural performance of CFRP components. Full article

The application of MXene–polymer composites to wearable and implantable medical devices requires the development of hydrophilic and biocompatible MXene–polymer hydrogel composites with high electromechanical response, flexibility, and durability. Here, we formulate low weight percentage MXene–hydrogel copolymer inks enabling the direct light processing (DLP) of Ti₃C₂T_x MXene–polyvinyl alcohol (PVA)–polyacrylic acid (PAA)–hydrogel composites. The low wt% MXene–PVA–PAA composites demonstrate high biocompatibility, mechanical flexibility, high sensitivity and high precision for sensing acute bending angles. The sub-millidegree angle resolution of these electromechanical sensors demonstrates their suitability for applications such as the highly precise tracking of joint movements. In addition, the synthesized MXene membranes show promise for applications in osmotic energy conversion, with a harvested electric power density of 6.79 Wm⁻². Full article

Crust Ash Triad Clay (CATC) is a traditional construction material commonly used for jointing coastal stone masonry in Southeast China. Its surface is prone to blackening in coastal environments. This study focused on traditional stone masonry residences within the protection area of Quanzhou Shihu Ancient Wharf. A systematic detection and analysis were conducted using combined technologies: XRD, Raman, SEM-EDS, and 16S rRNA sequencing. The results revealed that the CATC substrate is mainly composed of quartz and feldspar minerals, with calcite and other substances as binding components. The black coating on the surface is a loose material attached to the substrate, retaining some of the original minerals. The core mechanism of blackening lies in the coastal environment’s abundance of salt spray and humidity. The sulfate substances carried by rainwater react synergistically with metal ions such as Cu, Fe, and Mn in the substrate under the metabolic action of anaerobic bacteria, producing metal sulfide minerals. Photoautotrophic bacteria generate oxygen through photosynthesis, promoting the oxidation and acidification of metal sulfide. This process directly triggers the chain deterioration of the CATC substrate. Based on the principle of “minimal intervention”, physical waterproofing or laser stain removal can be implemented. This study provides scientific support for optimizing the durability and achieving precise protection of traditional building materials in coastal stone structure heritage. Full article

The aim of this study is to experimentally evaluate the damage mechanisms occurring in the adhesive-bonded regions of glass fiber-reinforced polymer (GFRP) and carbon fiber-reinforced polymer (CFRP) composites, which are widely used in marine and offshore wind turbine applications, under environmental conditions. In particular, this study focuses on the degradation caused by long-term seawater exposure and its effects on the bending behavior and load-carrying capacity of adhesive joints. For this purpose, the specimens were prepared in accordance with ASTM D5868-01, using 7-layer GFRP and 8-layer CFRP laminates. Single-lap adhesive joints were fabricated. To simulate marine environmental conditions, the single-lap adhesive joints were immersed in natural seawater obtained from the Aegean Sea (22 °C temperature and 3.3–3.7% salinity) for 1, 2, and 3 months in separate containers. Three-point bending (3PB) tests were performed on specimens representing marine applications, while four-point bending (4PB) tests were conducted on specimens representing offshore wind turbine blade structures. The results quantitatively revealed the influence of seawater on adhesive-bonded composite joints. In 3PB tests, the reductions in the Young’s modulus of GFRP specimens after 1, 2, and 3 months of exposure were measured as 5.94%, 8.90%, and 12.98%, respectively. For CFRP specimens, degradation was more limited, with corresponding reductions of 1.28%, 3.39%, and 3.74%. A similar trend was observed in 4PB tests representing offshore wind turbine applications, where GFRP joints exhibited modulus reductions of 3.15%, 6.42%, and 9.45%, while CFRP joints showed reductions of 1.29%, 2.62%, and 3.48% for the same exposure durations. Overall, the findings demonstrate that CFRP composites exhibit more stable mechanical behavior under environmental exposure, whereas GFRP structures undergo more pronounced performance losses, particularly in moisture- and salt-rich environments. These results highlight the critical importance of material selection for long-term durability in offshore composite structures. The outcomes of this study contribute to a better understanding of the damage processes occurring in composite adhesive joints under environmental conditions and provide a scientific basis for developing more reliable design and material selection strategies in both the marine and wind energy sectors. Full article

Due to the brittleness and volume sensitivity, segmentation is necessary for the cement concrete pavement slabs currently in widespread use to mitigate thermal stress and deformation. The dimensions of segmented pavement slabs are typically constrained to 4∼6 m, which results in a large number of joints. These joints cause damages such as corner spalling and fracture under the impact of repeated loads and environmental factors. In addition, maintenance costs are significantly increased due to the numerous joints. To enhance pavement performance and extend service lifespan, this paper proposes a design methodology for large pavement slabs. This method breaks the dimensional constraint and significantly reduces the number of joints, thereby improving comfort and durability, lowering maintenance costs, and meeting the operational requirements of new aircraft types. In this paper, pavement slab thermal stress is divided into curling stress and thermal expansion stress according to different deformation types. The diurnal and annual distributions of these two types of stresses are also investigated. Moreover, the maximum dimension design of pavement slabs comprehensively considers aircraft loads, thermal stresses, and fatigue characteristics. The results indicate that the diurnal and annual distributions of curling and thermal expansion stresses exhibit sinusoidal patterns. Under different temperature gradients and slab thicknesses, the allowable maximum slab dimension is presented. It is feasible to break the 4∼6 m limit for the maximum dimension of the pavement slab, which provides a new reference for improving pavement performance and lifespan. Full article

Thermal degradation of the interfacial microstructure critically limits the service life of Zn-Al brazed Cu/Al joints. This work elucidates the stabilizing role of trace Ni (0.3 wt.%) in retarding interfacial deterioration during 200 °C isothermal aging for up to 1000 h. Microstructural evolution and micromechanical responses were probed via SEM, EDS, and nanoindentation. In Ni-free joints, continuous Zn influx triggers the decomposition of the massive CuAl₂ phase into a defect-ridden, Zn-rich lamellar structure, precipitating a sharp decline in shear strength from 57 MPa to 37.5 MPa. Conversely, Ni doping constructs a robust fine-grained interfacial architecture. The Ni-bearing coral-like layer exhibits exceptional morphological stability, while the underlying Cu-based transition layer undergoes in situ stratification and Zn ejection, functioning as a chemical buffer to intercept Zn diffusion. This microstructural reconfiguration enables Ni-doped joints to sustain a shear strength of ~55.2 MPa after 1000 h—matching the initial strength of Ni-free counterparts. The superior durability stems from the modulus softening of the stratified transition layer and a multi-stage crack deflection mechanism, offering a viable metallurgical strategy for robust Cu/Al interconnects. Full article

The rapid aging of bridges has increased interest in real-time, data-driven monitoring for predictive maintenance and safety management; however, practical deployment on in-service bridges remains limited. This paper presents lessons learned from long-term field deployment of real-time bridge joint monitoring systems on three in-service highway bridges and demonstrates how these insights can support the transition toward Industry 5.0. A unified framework is introduced to integrate key enabling technologies, including Internet of Things (IoT), digital twins, and artificial intelligence (AI), into a practical, human-centric monitoring architecture. Best practices for achieving durable, site-compliant, and cost-effective system design are summarized, with emphasis on sensor selection, wireless communication strategies, modular system development, and maintaining seamless operation. The development of a Docker-based analytics and visualization platform illustrates how interactive dashboards enhance human–machine collaboration and support informed decision-making. The role of advanced analytical tools, including digital twins, AI, and statistical modeling, in providing reliable structural assessments is highlighted, along with guidance on balancing cloud and edge computing for energy-efficient performance under constraints such as limited power, weather exposure, and site accessibility. Overall, the findings support the development of scalable, resilient, and human-centric real-time monitoring systems that advance data-driven decision-making and directly contribute to the realization of Industry 5.0 objectives in bridge health management. Full article