Search Results (108)

Asphalt pavement cracking represents a prevalent form of deterioration that significantly compromises road performance and safety under the combined effects of environmental factors and traffic loading. Crack sealing has emerged as a widely adopted and cost-effective preventive maintenance strategy that restores the pavement’s structural integrity and extends service life. This paper presents a systematic review of the development of crack sealing technology, conducts a comparative analysis of conventional sealing materials (including emulsified asphalt, hot-applied asphalt, polymer-modified asphalt, and rubber-modified asphalt), and examines the existing performance evaluation methodologies. Critical failure mechanisms are thoroughly investigated, including interfacial bond failure resulting from construction defects, material aging and degradation, hydrodynamic scouring effects, and thermal cycling impacts. Additionally, this review examines advanced sensing methodologies for detecting premature sealant failure, encompassing both non-destructive testing techniques and active sensing technologies utilizing intelligent crack sealing materials with embedded monitoring capabilities. Based on current research gaps, this paper identifies future research directions to guide the development of intelligent and sustainable asphalt pavement crack repair technologies. The proposed research framework provides valuable insights for researchers and practitioners seeking to improve the long-term effectiveness of pavement maintenance strategies. Full article

Industries are leveraging the wire laser-beam-directed energy deposition (DED-LB) additive manufacturing (AM) process to manufacture and repair high-quality, defect-free, and cost-effective parts. However, expensive, non-easily accessible, and complex metrology equipment is needed to quantify part-related performance metrics such as cross-sectional dimensional accuracy and intrinsic defects. This information is necessary for establishing the operating process window and for the quality characterization of the part. Therefore, this work presents a methodology that combines information captured from a vision-based monitoring system with the output of Computed Tomography (CT) towards the knowledge generation and process optimization of wire DED-LB. The design of experiments as well as the interpretation of the results are achieved by employing Nested ANOVA where the dependency of cross-sectional stability on the laser power parameter is demonstrated, enabling, at the same time, the understanding of unstructured datasets where multiple parameters vary at different levels. Finally, this work can be the pillar for adopting new production and part requirements while also giving directions about the effect of control strategies on the part quality. Full article

This study addresses the procurement problem in mechanical manufacturing enterprises, considering both supply chain disruption risks and carbon emissions. Based on a multi-product, multi-supplier procurement planning optimization problem, a high-dimensional multi-objective optimization model is developed with procurement cost, total loss, number of quality defects, and carbon emissions as objectives. The model is solved using an improved integer-coded NSGA-III algorithm, which includes four mechanisms: heuristic population initialization, infeasible solution optimization and repair, a weight-matrix-based crossover operator, a multi-column exchange mutation operator, and Pareto simulated annealing. Through numerical experiments, the performance of this algorithm is compared with NSGA-III and NSGA-II, demonstrating its superior ability to handle multi-objective, multi-constraint optimization problems. Ablation experiments further validate the effectiveness of the four improved mechanisms. Case study results show that the optimized procurement plan balances economic and environmental benefits while considering supply chain risks. Full article

Research on nano-sustained-release factors for bone tissue scaffolds has significantly promoted the precision and efficiency of bone-defect repair by integrating biomaterials science, nanotechnology, and regenerative medicine. Current research focuses on developing multifunctional scaffold materials and intelligent controlled-release systems to optimize the spatiotemporal release characteristics of growth factors, drugs, and genes. Nano slow-release bone scaffolds integrate nano slow-release factors, which are loaded with growth factors, drugs, genes, etc., with bone scaffolds, which can significantly improve the efficiency of bone repair. In addition, these drug-loading systems have also been extended to the fields of anti-infection and anti-tumor. However, the problem of heterotopic ossification caused by high doses has led to a shift in research towards a low-dose multi-factor synergistic strategy. Multiple Phase II clinical trials are currently ongoing, evaluating the efficacy and safety of nano-hydroxyapatite scaffolds. Despite significant progress, this field still faces a series of challenges: the immunity risks of the long-term retention of nanomaterials, the precise matching of multi-factor release kinetics, and the limitations of the large-scale production of personalized scaffolds. Future development directions in this area include the development of responsive sustained-release systems, biomimetic sequential release design, the more precise regeneration of injury sites through a combination of gene-editing technology and self-assembled nanomaterials, and precise drug loading and sustained release through microfluidic and bioprinting technologies to reduce the manufacturing cost of bone scaffolds. The progress of these bone scaffolds has gradually changed bone repair from morphology-matched filling regeneration to functional recovery, making the clinical transformation of bone scaffolds safer and more universal. Full article

Tendon defect is one of the common clinical diseases related to the growing population mean age and the number of athletes. Due to an increasing demand for tendon repair surgical interventions, several tendon augmentation products, capable of guaranteeing the necessary biological and visco-elasticity properties and mechanical support, have been developed. In this regard, commercially available products may be grouped into three main categories: (i) natural, (ii) synthetic, and (iii) hybrid biomaterial-based products. Firstly, to better define the research area of this work, common search engines were employed to acquire information from reports or website portfolios of important competitors in the global tendon repair market. Secondly, public registries and bibliographic databases were also employed to analyse data from registered clinical trials and published clinical studies performed to evaluate the safety and efficacy of each product. Ten new products have been launched on the market in the last fifteen years: advantages, disadvantages, and future perspectives regarding their use for tendon augmentation treatment are discussed. Although hybrid biomaterial-based products may be considered as more oriented to the new frontiers of tendon augmentation technology, future improvements, especially focused on both mechanical properties and biocompatibility, are needed. However, scientific innovations must navigate convoluted clinical regulatory paths, which, due to high costs for investors, long development timelines, and funding shortages, hinder the translation of many scientific discoveries into routine clinical practice. Full article

Lithography is crucial to semiconductor manufacturing, enabling the production of smaller, more powerful electronic devices. This review explores the evolution, principles, and advancements of key lithography techniques, including extreme ultraviolet (EUV) lithography, electron beam lithography (EBL), X-ray lithography (XRL), ion beam lithography (IBL), and nanoimprint lithography (NIL). Each method is analyzed based on its working principles, resolution, resist materials, and applications. EUV lithography, with sub-10 nm resolution, is vital for extending Moore’s Law, leveraging high-NA optics and chemically amplified resists. EBL and IBL enable high-precision maskless patterning for prototyping but suffer from low throughput. XRL, using synchrotron radiation, achieves deep, high-resolution features, while NIL provides a cost-effective, high-throughput method for replicating nanostructures. Alignment marks play a key role in precise layer-to-layer registration, with innovations enhancing accuracy in advanced systems. The mask fabrication process is also examined, highlighting materials like molybdenum silicide for EUV and defect mitigation strategies such as automated inspection and repair. Despite challenges in resolution, defect control, and material innovation, lithography remains indispensable in semiconductor scaling, supporting applications in integrated circuits, photonics, and MEMS/NEMS devices. Various molecular strategies, mechanisms, and molecular dynamic simulations to overcome the fundamental lithographic limits are also highlighted in detail. This review offers insights into lithography’s present and future, aiding researchers in nanoscale manufacturing advancements. Full article

The management of segmental bone defects presents a complex reconstruction challenge for orthopedic surgeons. Current treatment options are limited by efficacy across the spectrum of injury, morbidity, and cost. Regional gene therapy is a promising tissue engineering strategy for bone repair, as it allows for local implantation of nucleic acids or genetically modified cells to direct specific protein expression. In cell-based gene therapy approaches, a variety of different cell types have been described including mesenchymal stem cells (MSCs) derived from multiple sources—bone marrow, adipose, skeletal muscle, and umbilical cord tissue, among others. MSCs, in particular, have been well studied, as they serve as a source of osteoprogenitor cells in addition to providing a vehicle for transgene delivery. Furthermore, MSCs possess immunomodulatory properties, which may support the development of an allogeneic “off-the-shelf” gene therapy product. Identifying an optimal cell type is paramount to the successful clinical translation of cell-based gene therapy approaches. Here, we review current strategies for the management of segmental bone loss in orthopedic surgery, including bone grafting, bone graft substitutes, and operative techniques. We also highlight regional gene therapy as a tissue engineering strategy for bone repair, with a focus on cell types and cell sources suitable for this application. Full article

Organoid technology, as an innovative approach in biomedicine, exhibits promising prospects in disease modeling, pharmaceutical screening, regenerative medicine, and oncology research. However, the use of tumor-derived Matrigel as the primary method for culturing organoids has significantly impeded the clinical translation of organoid technology due to concerns about potential risks, batch-to-batch instability, and high costs. To address these challenges, this study innovatively introduced a photo-crosslinkable hydrogel made from a porcine small intestinal submucosa decellularized matrix (SIS), fish collagen (FC), and methacrylate gelatin (GelMA). The cost-effective hydrogel demonstrated excellent biocompatibility, tunable mechanical properties, rapid gelation properties, and low immunogenicity. Importantly, the proliferation and differentiation capacities of small intestinal organoids cultured in hydrogel were comparable to those in Matrigel, with no significant disparity observed. Furthermore, after one week of transplantation in nude mice, the hydrogel–organoid complex exhibited sustained structural and functional stability while preserving the differentiation characteristics of small intestinal organoids. Our study also demonstrated the effective potential of FC/SIS/GelMA hydrogel in accelerating the repair process of small intestinal defects, reducing the area of scar formation, and promoting the regeneration of both intestinal villi and smooth muscle tissue. In summary, this study presents a novel protocol for culturing small intestinal organoids, offering potential implications for future clinical applications and serving as an experimental foundation for the development of tissue-engineered intestines based on small intestinal organoids. Full article

Background and Objectives: Cartilage repair remains a critical challenge in orthopaedic medicine due to the tissue’s limited self-healing ability, contributing to degenerative joint conditions such as osteoarthritis (OA). In response, regenerative medicine has developed advanced therapeutic strategies, including cell-based therapies, gene editing, and bioengineered scaffolds, to promote cartilage regeneration and restore joint function. This narrative review aims to explore the latest developments in cartilage repair techniques, focusing on mesenchymal stem cell (MSC) therapy, gene-based interventions, and biomaterial innovations. It also discusses the impact of patient-specific factors, such as age, defect size, and cost efficiency, on treatment selection and outcomes. Materials and Methods: This review synthesises findings from recent clinical and preclinical studies published within the last five years, retrieved from the PubMed, Scopus, and Web of Science databases. The search targeted key terms such as “cartilage repair”, “stem cell therapy”, “gene editing”, “biomaterials”, and “tissue engineering”. Results: Advances in MSC-based therapies, including autologous chondrocyte implantation (ACI) and platelet-rich plasma (PRP), have demonstrated promising regenerative potential. Gene-editing tools like CRISPR/Cas9 have facilitated targeted cellular modifications, while novel biomaterials such as hydrogels, biodegradable scaffolds, and 3D-printed constructs have improved mechanical support and tissue integration. Additionally, biophysical stimuli like low-intensity pulsed ultrasound (LIPUS) and electromagnetic fields (EMFs) have enhanced chondrogenic differentiation and matrix production. Treatment decisions are influenced by patient age, cartilage defect size, and financial considerations, highlighting the need for personalised and multimodal approaches. Conclusions: Combining regenerative techniques, including cell-based therapies, gene modifications, and advanced scaffolding, offers a promising pathway towards durable cartilage repair and joint preservation. Future research should focus on refining integrated therapeutic protocols, conducting long-term clinical evaluations, and embracing personalised treatment models driven by artificial intelligence and predictive algorithms. Full article

Distraction osteogenesis (DO) is a process which uses the bone’s natural healing tendencies to repair and lengthen pathologic, missing, or malformed bone. The mechanism of DO mimics the pathway that the body uses in any other fracture repair however the location of the fracture is carefully controlled by a surgical osteotomy. Postoperatively, the bone is allowed to begin its natural healing process, with the lengthener applying constant tension and thus re-initiating the process of healing along the length of the distraction gap. Current clinical indications for DO include limb length discrepancy, congenital bone length deformity, large bone defects, and extremity reconstruction due to hypoplasia or limb salvage procedures. The risks of DO include soft tissue complications, relapse or improper correction, cost or resource-related challenges, and psychosocial stigmas surrounding long treatment durations and the necessity of wearing the distraction lengthening hardware. Future directions for DO include supplements to the bone regeneration process (such as growth factors and/or mechanical stimulation) or improvements to the distractor device itself (changes in material and/or the structure of the device itself). This review aims to offer a comprehensive summary of the indications, underlying biological mechanisms, and practical considerations when implementing the use of distraction osteogenesis in clinical practice. Full article

Consumer dissatisfaction and damage are increasing worldwide due to the increase in defects caused by the decline in housing quality, and disputes over housing defects are expanding. The number of housing units, a representative standard related to housing quality, is used in Canada, Japan, and Korea. Generally, quality costs increase as the number of housing units increases, and each country’s laws apply stricter management standards. Therefore, the quality is expected to be better as the number of units increases. In 2020, South Korea added a new regulation requiring inspections by a quality inspection team by a public institution only when building housing complexes with more than 300 households. There is a debate about whether this direction of regulation is appropriate. This study examines whether the number of households is being used appropriately as a criterion related to housing quality. It aims to determine whether the limit of 300 households is appropriate for distinguishing housing quality. In addition, since the contractor’s role is vital in housing construction, the contractor’s capabilities and supply–demand relationship were also considered as factors affecting housing quality. The ratio of defect repair costs to construction costs was used as a quality measure for 285 housing complexes in Korea. Generally, the lower the defect repair–construction costs ratio, the better the quality. A comparative study was conducted through a variance analysis on the scale of 300 households and the status of the contractor’s capability, whether they were among the top 10 construction companies with excellent construction performance, and whether a sole contract was made. The results showed that the quality was better in the cases with 300 or more households than in the cases with fewer than 300 households. The quality was better in the cases built by higher-ranking contractors than in those built by other contractors, but there was no difference according to supply-and-demand relationships. The results of the comprehensive analysis indicated that the quality was better when higher-ranking contractors built housing complexes with 300 or more households than when lower-ranking contractors built housing complexes with fewer than 300 households. Therefore, the direction of the Korean regulation requiring quality inspections for housing complexes with more than 300 households is incorrect and should be improved to regulate housing complexes with fewer than 300 households, and of low quality. In addition, the standard of determining housing quality based solely on the number of households should be revised, and the direction should be changed to strengthen quality control and the public supervision of housing built by low-capacity contractors. If the results of this study are utilized with this view in mind, a reasonable system to protect housing consumers will be promoted. Full article

Cartilage repair techniques for chondral defects in the hip are crucial for treating conditions like femoroacetabular impingement, developmental dysplasia, and osteonecrosis, especially in young patients to delay the progression of osteoarthritis. This study aims to present age and sex distributions and trends in hip-preserving surgeries in Germany from 2006 to 2022, analyzing 116,179 procedures using the German OPS coding system. The procedures were categorized into three groups: debridement, refixation, and regeneration. Arthroscopy was more common than arthrotomy (98,916 vs. 17,263). Males underwent more procedures than females (63,771 vs. 52,408). Debridement had a monomodal age distribution peaking at 43.42 years, while refixation and regeneration exhibited bimodal patterns. Regenerative procedures were primarily performed on younger patients (average 27.73 years). A Joinpoint analysis showed an initial increase in procedures, peaking around 2013, followed by a decline. Arthroscopic procedures peaked at approximately 9000 in 2013, whereas arthrotomies peaked at around 1200 after 2014. The decline in procedures post-2013 may reflect refined surgical indications and a shift towards outpatient settings. These findings underscore the trend towards minimally invasive, scaffold-based treatments, with regenerative techniques showing promising outcomes in younger patients. Future research should focus on prospective comparative studies and cost–benefit analyses to guide clinical decision-making. Full article

Despite stiff competition in the construction industry, housing quality remains a problem. From the consumer’s perspective, these quality problems are called defects. Homeowners experience inconvenience and suffering due to home defects, and developers and builders also experience severe damage in time, costs, and reputation due to defect repairs. In Korea, lawsuits are increasing due to the rise in housing defects, and the cost of repairing defects determined by lawsuits is of great concern. Litigation is a burden to consumers and producers, requiring a hefty court fee, as well as attorneys and specialist firms, and takes some years. Suppose it is possible to predict the repair costs based on the outcome of a lawsuit and present it as objective supporting data. In that case, it can be of great help in bringing a settlement between consumers and producers. According to previous studies on housing repair costs, linear regression models were mainly used. Accordingly, in this study, a linear regression model was adopted as a method to predict housing repair costs. We analyzed the defect repair costs in 100 cases in which lawsuits were filed and the verdict was finalized for housing complexes in Korea. Previous studies investigated using the following independent variables: elapsed period, litigation period, claim amount, home warranty deposit, total floor area, households, and main building’s quantity, construction cost, region, and highest floor. Among these, the floor area, elapsed period, and litigation period were determined to be valid independent variables. In addition, the construction period was discovered as a valid independent variable. The present research model, which combines these independent variables, was compared with previous research models. The results showed that the earlier research model was found to have a multicollinearity issue among some independent variables. Also, the coefficients of some independent variables were not statistically significant. This research model did not have a multicollinearity problem; all independent variables’ coefficients were statistically significant, and the coefficient of determination was higher than other linear research models. Our proposed regression model, which accounts for the interaction of each independent variable, is a significant step forward in our research. This model, using the number of households multiplied by the construction period, the construction period multiplied by the litigation period, and the litigation period multiplied by the litigation period as independent variables, has been rigorously tested and found to have no multicollinearity issue. The coefficients of all independent variables are statistically significant, further bolstering the model’s reliability. Additionally, the explanatory power of this model is comparable to the previous model, suggesting its potential to be used in conjunction with the existing model. Therefore, the linear regression model predicting the repair cost of housing defects following litigation in this study was considered the best. Utilizing the model proposed in this study is expected to play a major role in reconciling disputes between consumers and producers over housing defects. Full article

Semiconductors with visible light catalytic characteristics can realize the degradation of pollutants, CO₂ reduction, and hydrogen preparation in sunlight. They have huge application value in the fields of environmental repair and green energy. Graphite phase nitride (g-C₃N₄, CN) is widely used in various fields such as photocatalytic degradation of pollutants due to its suitable gap width, easy preparation, low cost, fast visible light response, and rich surface activity sites. However, the absorption rate of ordinary CN on visible light is low, and the carriers are easy to recombination, making the lower optical catalytic activity. Therefore, in order to improve the photocatalytic characteristics of the CN, it is necessary to make the surface modification. This article first introduces several main methods for the current surface modification of CN, including size regulation, catalyst embedding, defect introduction, heterostructure construction, etc., and then summarizes the optical catalytic application and related mechanisms of CN. Finally, some challenges and development prospects of CN in preparation and photocatalytic applications are proposed. Full article

Partial discharge is a fault that occurs at the site of insulation defects within a transformer. Dual instances of partial discharge origination discharging simultaneously embody a more intricate form of discharge, where the interaction between the discharge sources leads to more intricate and unpredictable insulation damage. Conventional piezoelectric transducers are magnetically affixed to the exterior metal tank of transformers. The ultrasonic signals emanating from partial discharge undergo deflection and reverberation upon traversing the windings, insulation paperboards, and the outer shell, resulting in signal attenuation and thus making it difficult to detect such faults. Furthermore, it is challenging to distinguish between simultaneous discharges from dual partial discharge sources and continuous discharges from a single source, often leading to missed detection and repairs of fault points, which increase the maintenance difficulty and cost of power equipment. With the advancement of MEMS (Micro-Electro-Mechanical System) technology, fiber-optic ultrasonic sensors have surfaced as an innovative technique for optically detecting partial discharges. These sensors are distinguished by their minute dimensions, heightened sensitivity, and robust immunity to electromagnetic disturbances. and excellent insulation properties, allowing for internal installation within power equipment for partial discharge monitoring. In this study, we developed an EFPI (Extrinsic Fabry Perot Interferometer) optical fiber ultrasonic sensor that can be installed inside transformers. Based on this sensor array, we also created a partial discharge ultrasonic detection system that estimates the directional information of single and dual partial discharge sources using the received signals from the sensor array. By utilizing the DOA (Direction of Arrival) as a feature recognition parameter, our system can effectively detect both simultaneous discharges from dual partial discharge sources and continuous discharges from a single source within transformer oil tanks, meeting practical application requirements. The detection methodology presented in this paper introduces an original strategy and resolution for pinpointing the types of partial discharges occurring under intricate conditions within power apparatus, effectively distinguishing between discharges from single and dual partial discharge sources. Full article