MDPI - Publisher of Open Access Journals

17 pages, 2508 KiB

Open AccessReview

Mathematical Modeling of the Rail Track Superstructure–Subgrade System

by Dmytro Kurhan, Szabolcs Fischer and Vladyslav Khmelevskyi

Geotechnics 2025, 5(1), 20; https://doi.org/10.3390/geotechnics5010020 (registering DOI) - 16 Mar 2025

The “rail track superstructure–subgrade” system is a sophisticated engineering structure critical in ensuring safe and efficient train operations. Its analysis and design rely on mathematical modeling to capture the interactions between system components and the effects of both static and dynamic loads. This [...] Read more.

The “rail track superstructure–subgrade” system is a sophisticated engineering structure critical in ensuring safe and efficient train operations. Its analysis and design rely on mathematical modeling to capture the interactions between system components and the effects of both static and dynamic loads. This paper offers a detailed review of contemporary modeling approaches, including discrete, continuous, and hybrid models. The research’s key contribution is a thorough comparison of five primary methodologies: (i) quasi-static analytical calculations, (ii) multibody dynamics (MBD) models, (iii and iv) static and dynamic finite element method (FEM) models, and (v) wave propagation-based models. Future research directions could focus on developing hybrid models that integrate MBD and FEM to enhance moving load predictions, leveraging machine learning for parameter calibration using experimental data, investigating the nonlinear and rheological behavior of ballast and subgrade in long-term deformation, and applying wave propagation techniques to model vibration transmission and evaluate its impact on infrastructure. Full article

► Show Figures

Figure 1

23 pages, 736 KiB

Open AccessArticle

Innovative Power Generation System for Large Ships Based on Fuel Cells: A Technical–Economic Comparison with a Traditional System

by Alessandro Ruvio, Stefano Elia, Manlio Pasquali, Roberto Pibiri, Stephen McPhail and Matteo Fontanella

Energies 2025, 18(6), 1456; https://doi.org/10.3390/en18061456 (registering DOI) - 16 Mar 2025

Abstract

At present, shipping companies are aiming to meet better energy and environmental requirements when designing large cruise ships, thus decreasing emissions, increasing efficiency and reliability and greatly reducing maintenance time and costs. This paper provides a technical–economic comparison for a real case study, [...] Read more.

At present, shipping companies are aiming to meet better energy and environmental requirements when designing large cruise ships, thus decreasing emissions, increasing efficiency and reliability and greatly reducing maintenance time and costs. This paper provides a technical–economic comparison for a real case study, including a complete feasibility study regarding the sizing of a generation system to supply base hotel loads, between two power plant architectures focused on fuel cells and diesel generators for a cruise ship. The paper describes, in detail, an innovative solid oxide fuel cell(SOFC) generation system, which offers high efficiency and low emissions, assessed for its technical, economic and environmental performance. This study examines generators for hotels, requiring continuous service at constant load and a 1 MW power supply. The work relates to ships with a tonnage of more than 100,000 tons. Subsequently, considering that, in the case study, the diesel generators are powered by LNG (liquefied natural gas), there will also be a comparison with a case where both systems are simply powered by LNG. The main technical specifications required by shipbuilders for choosing the most suitable system for on-board generation (weight, volume, maintenance intervals and operations, as well as investment and operational expenses)are analyzed and described. The economic comparison is based on two extreme assumptions of the purchase and operating costs of the fuel cell system and returns a different result depending on the assumption adopted. The usefulness of the proposed solution based on fuel cells is demonstrated on the basis of an accurate technical, energetic and economic comparison with the conventional technologies based on diesel generators. The work is completed by evaluating the overall power-generating reliability improvement achievable with the new technology, in comparison with the traditional system. The comparison between the fuel cell system and the diesel system shows that the former has a higher weight (+40%), volume (+75%) and initial investment cost (3–6 times higher). However, the lower LNG consumption reduces the annual operating cost and the size and weight of the on-board tanks or, with the same tank capacity, increases the system’s range. The overall reliability of the fuel cell system is significantly higher than that of the traditional system. Full article

(This article belongs to the Special Issue Future of Transport: Hybrid Electrification and Hydrogen Integration in Vehicles and Infrastructure)

21 pages, 2624 KiB

Open AccessArticle

Experimental Study of Rock Failure and Fractal Characteristics Under True Triaxial Unloading

by Chongyan Liu, Guangming Zhao, Cheng Pan, Xiangrui Meng and Wensong Xu

Fractal Fract. 2025, 9(3), 182; https://doi.org/10.3390/fractalfract9030182 (registering DOI) - 16 Mar 2025

Abstract

In order to study the failure and fractal characteristics of unloaded rocks, with the help of the true triaxial unloading rock test system and the acoustic emission (AE) monitoring system, rock failure tests were conducted under varying intermediate principal stress and the mechanical [...] Read more.

In order to study the failure and fractal characteristics of unloaded rocks, with the help of the true triaxial unloading rock test system and the acoustic emission (AE) monitoring system, rock failure tests were conducted under varying intermediate principal stress and the mechanical response features of the rocks were analyzed. An investigation was conducted into the rocks’ AE patterns and multifractal features. The results showed that the rocks’ AE macroscopic and microscopic main failure modes differed slightly under unloading. As the intermediate principal stress σ₂ increased, the fractal dimension of the cracks in the rocks first increased and then decreased. The distribution of rock failure was initially concentrated, then dispersed, and concentrated again at the end. As the σ₂ increased, the number of failure events within a specified area in the rock samples under unloading, as represented by the ring-down count, first increased and then decreased. Meanwhile, the fractal dimension Δα first decreased and then increased. These results characterized the process whereby the failure distribution pattern of the rocks changed from being concentrated to dispersed and back to concentrated again. Full article

(This article belongs to the Special Issue Fractal Analysis and Its Applications in Rock Engineering)

23 pages, 6092 KiB

Open AccessArticle

Exploiting Paradoxical Activation of Oncogenic MAPK Signaling by Targeting Mitochondria to Sensitize NRAS Mutant-Melanoma to Vemurafenib

by Laura Francisca Leite do Prado-Souza, Letícia Silva Ferraz, Tharcísio Citrangulo Tortelli, Jr., César Augusto João Ribeiro, Danilo Trabuco do Amaral, Denise Costa Arruda, Érica Aparecida de Oliveira, Roger Chammas, Silvya Stuchi Maria-Engler and Tiago Rodrigues

Int. J. Mol. Sci. 2025, 26(6), 2675; https://doi.org/10.3390/ijms26062675 (registering DOI) - 16 Mar 2025

Abstract

Vemurafenib is a BRAF (rapidly accelerated fibrosarcoma B-type)-targeted therapy used to treat patients with advanced, unresectable melanoma. It inhibits the MAPK (mitogen-activated protein kinase)/ERK (extracellular signal-regulated kinase) pathway and tumor proliferation in BRAF^V600E-mutated melanoma cells. Resistance to vemurafenib has been reported [...] Read more.

Vemurafenib is a BRAF (rapidly accelerated fibrosarcoma B-type)-targeted therapy used to treat patients with advanced, unresectable melanoma. It inhibits the MAPK (mitogen-activated protein kinase)/ERK (extracellular signal-regulated kinase) pathway and tumor proliferation in BRAF^V600E-mutated melanoma cells. Resistance to vemurafenib has been reported in melanoma patients due to secondary NRAS (neuroblastoma RAS viral oncogene homolog) mutations, which lead to paradoxical MAPK pathway activation and tumor proliferation. However, the impact of this paradoxical activation on mitochondrial dynamics and function in NRAS-mutated melanoma is unclear. Here, we investigated the effects of vemurafenib on NRAS^Q61R-mutated melanoma cells, focusing on mitochondrial dynamics and function. As expected, vemurafenib did not exhibit cytotoxicity in SK-MEL-147 NRAS^Q61R-mutated melanoma cells, even after 72 h of incubation. However, it significantly enhanced the MAPK/ERK signaling through paradoxical activation, accompanied by decreased expression of mitochondrial fusion proteins and activation of the fission protein DRP1 (dynamin-related protein 1), leading to small, rounded mitochondrial morphology. These observations were corroborated by transcriptome data obtained from NRAS-mutated melanoma patients, showing MFN1 (mitofusin 1) and OPA1 (optic atrophy 1) downregulation and DNM1L (DRP1 gene) upregulation. Interestingly, inhibition of mitochondrial fission with mdivi-1 or modulation of oxidative phosphorylation via respiratory chain inhibition or uncoupling significantly sensitized NRAS^Q61R-mutated melanoma cells to vemurafenib. Despite vemurafenib’s low cytotoxicity in NRAS-mutated melanoma, targeting mitochondrial dynamics and/or oxidative phosphorylation may offer a promising strategy for combined therapy. Full article

(This article belongs to the Special Issue State-of-the-Art Molecular Oncology in Brazil, 3rd Edition)

► Show Figures

Graphical abstract

20 pages, 8566 KiB

Open AccessArticle

Simultaneous Removal of Heavy Metals and Dyes on Sodium Alginate/Polyvinyl Alcohol/κ-Carrageenan Aerogel Beads

by Taesoon Jang, Soyeong Yoon, Jin-Hyuk Choi, Narae Kim and Jeong-Ann Park

Gels 2025, 11(3), 211; https://doi.org/10.3390/gels11030211 (registering DOI) - 16 Mar 2025

Abstract

Industrial textile wastewater containing both heavy metals and dyes has been massively produced. In this study, semi-interpenetrating polymer network structures of sodium alginate (SA)/polyvinyl alcohol (PVA)/κ-carrageenan (CG) aerogel beads were synthesized for their simultaneous reduction. The SA/PVA/CG aerogel beads were synthesized through a [...] Read more.

Industrial textile wastewater containing both heavy metals and dyes has been massively produced. In this study, semi-interpenetrating polymer network structures of sodium alginate (SA)/polyvinyl alcohol (PVA)/κ-carrageenan (CG) aerogel beads were synthesized for their simultaneous reduction. The SA/PVA/CG aerogel beads were synthesized through a cost-effective and environmentally friendly method using naturally abundant biopolymers without toxic cross-linkers. The SA/PVA/CG aerogel beads were spheres with a size of 3.8

\pm

0.1 mm, exhibiting total pore areas of 15.2 m²/g and porous structures (pore size distribution: 0.04–242.7 μm; porosity: 93.97%) with abundant hydrogen bonding, high water absorption capacity, and chemical resistance. The adsorption capacity and mechanisms of the SA/PVA/CG aerogel beads were investigated through kinetic and isotherm experiments for heavy metals (Cu(II), Pb(II)), cationic dye (methylene blue, MB), and anionic dye (acid blue 25, AB)) in both single and binary systems. The maximum adsorption capacities of the SA/PVA/CG aerogel beads based on the Langmuir model of Cu(II), Pb(II), and MB were 85.17, 265.98, and 1324.30 mg/g, respectively. Pb(II) showed higher adsorption affinity than Cu(II) based on ionic properties, such as electronegativity and hydration radius. The adsorption of Cu(II), Pb(II), and MB on the SA/PVA/CG aerogel beads was spontaneous, with heavy metals and MB exhibiting endothermic and exothermic natures, respectively. Full article

(This article belongs to the Special Issue Eco-Friendly Gels for Adsorption)

► Show Figures

Graphical abstract

14 pages, 269 KiB

Open AccessArticle

Indirect Impact of Pandemic on the Diagnosis of New Primary Melanoma: A Retrospective, Multicenter Study

by Luca Nespoli, Lorenzo Borgognoni, Virginia Caliendo, Dario Piazzalunga, Piero Rossi, Marco Clementi, Stefano Guadagni, Corrado Caracò, Serena Sestini, Maria Gabriella Valente, Franco Picciotto, Cosimo Di Raimondo, Davide Ferrari, Irene Tucceri Cimini, Amy Giarrizzo, Salvatore Asero, Matteo Mascherini, Franco De Cian, Francesco Russano, Paolo Del Fiore, Francesco Cavallin, Sara Coppola, Elisabetta Pennacchioli, Pietro Gallina and Marco Rastrelli Show full author list Hide full author list

J. Clin. Med. 2025, 14(6), 2017; https://doi.org/10.3390/jcm14062017 (registering DOI) - 16 Mar 2025

Abstract

Background/Objectives: The indirect impact of the pandemic on the diagnosis and treatment of new primary melanoma has been carefully evaluated in recent years. The aim of the present study was to investigate if the indirect impact of the pandemic in Italy could [...] Read more.

Background/Objectives: The indirect impact of the pandemic on the diagnosis and treatment of new primary melanoma has been carefully evaluated in recent years. The aim of the present study was to investigate if the indirect impact of the pandemic in Italy could be detectable also in the second year of the pandemic, as suggested by the characteristics of melanoma at diagnosis. Methods: Retrospective analysis of 1640 diagnoses of cutaneous melanoma in pre-pandemic period and 1292 diagnoses in the pandemic period from 10 centers (from 1 March 2019 to 28 February 2022). Results: Our findings confirmed an indirect impact of the pandemic on characteristics of incident melanoma, also in the second year of the pandemic in Italy (Breslow thickness p < 0.0001, tumor stage p = 0.002, ulceration p = 0.04, SNLB p = 0.03), without statistically significant differences between centers. A statistically significant reduction in the time interval from diagnosis to surgical treatment was observed, but only in centers that had to modify their case mix to address the needs of treating COVID-19 patients (p = 0.0002). Conclusions: Our study confirmed the indirect impact of the pandemic on melanoma characteristics at the diagnosis in the second year of the pandemic in Italy. We also found no differences in melanoma characteristics between hospitals with different organization. Diagnostic delays may be related to a delayed access of the patient to the entire diagnostic pathway, and therefore, especially in the case of a pandemic, policies to support early diagnosis are crucial. Full article

(This article belongs to the Special Issue Clinical Consequences of COVID-19: 2nd Edition)

19 pages, 7898 KiB

Open AccessArticle

Impact of Standing Water Level and Observation Time on Remote-Sensed Canopy Indices for Rice Nitrogen Status Monitoring

by Gonzalo Carracelas, John Hornbuckle and Carlos Ballester

Remote Sens. 2025, 17(6), 1045; https://doi.org/10.3390/rs17061045 (registering DOI) - 16 Mar 2025

Abstract

The observation time and water background can affect the remote sensing estimates of the nitrogen (N) content in rice crops. This makes the use of vegetation indices (VIs) for N status monitoring and topdressing recommendations challenging, as the timing of panicle initiation and [...] Read more.

The observation time and water background can affect the remote sensing estimates of the nitrogen (N) content in rice crops. This makes the use of vegetation indices (VIs) for N status monitoring and topdressing recommendations challenging, as the timing of panicle initiation and the water level in bays usually differ between farms even when managed using the same irrigation technique. This study aimed to investigate the influence of standing water levels (from 0 to 20 cm) and the time of image acquisition on a set of N-sensitive VIs to identify those less affected by these factors. The experiment was conducted using a split-plot experimental design with two side-by-side bays (main plots) where rice was grown ponded for most of the growing season and aerobically (not permanently ponded), each with four fertilization N rates. The SCCCI and SCCCI² were the only indices that did not vary depending on the time of the day when the multispectral images were collected. These indices showed the lowest variation among water layer treatments (5%), while the Clg index showed the highest (20%). All VIs were significantly correlated with N uptake (average R² = 0.73). However, the SCCCI² was the index that showed the lowest variation in N-uptake estimates resulting in equal N-fertilizer recommendations across water level treatments. The consistent performance of SCCCI² across different water levels makes this index of interest for different irrigation strategies, including aerobic management, which is gaining increasing attention to improve the sustainability of the rice industry. Full article

(This article belongs to the Special Issue Quantitative Remote Sensing and Its Applications in Agriculture and Vegetation)

► Show Figures

Figure 1

22 pages, 11556 KiB

Open AccessArticle

Enhanced Methodology and Experimental Research for Caged Chicken Counting Based on YOLOv8

by Zhenlong Wu, Jikang Yang, Hengyuan Zhang and Cheng Fang

Animals 2025, 15(6), 853; https://doi.org/10.3390/ani15060853 (registering DOI) - 16 Mar 2025

Abstract

Accurately counting chickens in densely packed cages is a major challenge in large-scale poultry farms. Traditional manual counting methods are labor-intensive, costly, and prone to errors due to worker fatigue. Furthermore, current deep learning models often struggle with accuracy in caged environments because [...] Read more.

Accurately counting chickens in densely packed cages is a major challenge in large-scale poultry farms. Traditional manual counting methods are labor-intensive, costly, and prone to errors due to worker fatigue. Furthermore, current deep learning models often struggle with accuracy in caged environments because they are not well-equipped to handle occlusions. In response, we propose the You Only Look Once-Chicken Counting Algorithm (YOLO-CCA). YOLO-CCA improves the YOLOv8-small model by integrating the CoordAttention mechanism and the Reversible Column Networks backbone. This enhancement improved the YOLOv8-small model’s F1 score to 96.7% (+3%) and average precision_50:95 to 80.6% (+2.8%). Additionally, we developed a threshold-based continuous frame inspection method that records the maximum number of chickens per cage with corresponding timestamps. The data are stored in a cloud database for reliable tracking during robotic inspections. The experiments were conducted in an actual poultry farming environment, involving 80 cages with a total of 493 chickens, and showed that YOLO-CCA raised the chicken recognition rate to 90.9% (+13.2%). When deployed on a Jetson AGX Orin industrial computer using TensorRT, the detection speed increased to 90.9 FPS (+57.6 FPS), although the recognition rate slightly decreased to 93.2% (−2.9%). In summary, YOLO-CCA reduces labor costs, improves counting efficiency, and supports intelligent poultry farming transformation. Full article

(This article belongs to the Special Issue Real-Time Sensors and Their Applications in Smart Animal Agriculture)

► Show Figures

Figure 1

31 pages, 4790 KiB

Open AccessArticle

Assessing the Technical–Economic Feasibility of Low-Altitude Unmanned Airships: Methodology and Comparative Case Studies

by Carlo E. D. Riboldi and Luca Fanchini

Aerospace 2025, 12(3), 244; https://doi.org/10.3390/aerospace12030244 (registering DOI) - 16 Mar 2025

Abstract

The current growing interest in lighter-than-air platforms (LTA) has been fueled by the significant development of some enabling technologies, in particular electric motors and on-board electronics. The localization of multiple thrust forces in the layout of the airship, as well as the ability [...] Read more.

The current growing interest in lighter-than-air platforms (LTA) has been fueled by the significant development of some enabling technologies, in particular electric motors and on-board electronics. The localization of multiple thrust forces in the layout of the airship, as well as the ability to manage them through automatic control, promises to mitigate the controllability issues connatural to this type of flying craft. Employed on unmanned missions and close to the ground, LTA vehicles now appear to be a technically viable alternative to other unmanned aerial vehicles (UAVs) or low-flying manned machines and are similarly capable of effectively achieving the corresponding mission goals. A key step in establishing the credibility of LTA vehicles as industrial solutions for an end user is an assessment of the economic effort required for producing and operating them. This study presents an analytic approach for evaluating these costs, based on the data available at a preliminary design level for an airship. Three missions currently flown by other types of flying machines were considered, and for each mission the sizing and preliminary design of a LTA platform capable of providing the same mission performance was carried out. Correspondingly, a newly introduced method for the estimation of the cost of a LTA platform was applied. Also, an estimation of the costs currently sustained by operators for each mission was obtained from the available data and with the support of relevant companies, who currently do not fly LTA platforms but operate with more standard flying machines (in particular, multicopter or fixed-wing UAVs or manned helicopters). Finally, the costs corresponding to both currently flying non-LTA vehicles and suitably designed LTA solutions were compared, yielding indications of the emerging economic trade-offs. Full article

(This article belongs to the Special Issue Design, Characterization and Operations of Lighter-than-Air Flying Vehicles)

31 pages, 14896 KiB

Open AccessArticle

Evolution of Overlying Strata Bed Separation and Water Inrush Hazard Assessment in Fully Mechanized Longwall Top-Coal Caving of an Ultra-Thick Coal Seam

by Shun Liang, Xuepeng Zhang, Fahong Ke, Jinhui Liu, Qiangling Yao, Hongye Luo, Xuehua Li and Yingnan Xu

Water 2025, 17(6), 850; https://doi.org/10.3390/w17060850 (registering DOI) - 16 Mar 2025

Abstract

Bed-separation water hazards are a common and very harmful mining disaster in the mining areas of western China in recent years, which seriously threatens the safe mining of rich and thick coal seam resources in the West. The Yonglong mining area has become [...] Read more.

Bed-separation water hazards are a common and very harmful mining disaster in the mining areas of western China in recent years, which seriously threatens the safe mining of rich and thick coal seam resources in the West. The Yonglong mining area has become a high-risk area for bed-separation water hazards due to its particularly thick coal seams and strong water-rich overlying strata. In view of this, this paper investigates the development height of a water-flowing fractured zone in the fully mechanized caving mining of an ultra-thick coal seam in the Yonglong mining area, the evolution law of the bed separation of overlying strata, and the process of water inrush from a bed separation. Based on the measured water-flowing fractured zone height data of the Yonglong mining area and several surrounding mines, a water-flowing fractured zone height prediction formula suitable for the geological conditions of the Yonglong mining area was fitted. By using discrete element numerical simulation and laboratory similarity simulation, the evolution law of overlying strata separation under the conditions of fully mechanized caving mining in the study area was analyzed, and the space was summarized into “four zones, three arches, and five zones”. Through the stress-seepage coupling simulation of the water inrush process of the roof separation in the fully mechanized caving mining of an ultra-thick coal seam, the migration, accumulation, and sudden inrush of water in the aquifer in overlying strata under the influence of mining were analyzed, and the variation in the pore water pressure in the process of water inrush during coal seam mining separation was summarized. The pore water pressure in the overlying strata showed a trend of first decreasing, then increasing, and, finally, stabilizing. Combined with the height, water inrush volume, and water-rich zoning characteristics of the water-flowing fractured zone of the 1012007 working face of the Yuanzigou Coal Mine, the danger of water inrush from the overlying strata separation of the working face was evaluated. It is believed that it has the conditions for the formation of water accumulation and separation, and the risk of water inrush is high. Prevention and control measures need to be taken on site to ensure mining safety. The research results have important guiding significance for the assessment and prevention of water inrush hazards in overlying strata during fully mechanized longwall top-coal caving of ultra-thick coal seams with similar geological conditions worldwide. Full article

► Show Figures

Figure 1

14 pages, 943 KiB

Open AccessArticle

Preparation and Improved Properties of Vanillin-Crosslinked Polyvinyl Alcohol/Chitosan Active Packaging Films

by Yina He, Xiaojun Zhang, Zhan Zhang, Bing Lin and Haitao Yu

Molecules 2025, 30(6), 1334; https://doi.org/10.3390/molecules30061334 (registering DOI) - 16 Mar 2025

Abstract

Using chitosan and polyvinyl alcohol (PVA) as substrates, active packaging composite (VPC) films based on vanillin-crosslinked PVA/chitosan with different concentrations of added vanillin were prepared and characterized. The results show that the VPC films exhibited higher tightness and hydrophobicity, lower water content and [...] Read more.

Using chitosan and polyvinyl alcohol (PVA) as substrates, active packaging composite (VPC) films based on vanillin-crosslinked PVA/chitosan with different concentrations of added vanillin were prepared and characterized. The results show that the VPC films exhibited higher tightness and hydrophobicity, lower water content and water vapor permeability, as well as better UV resistance. The potential interactions between the film groups were analyzed by SEM, FTIR, and XRD, and the results showed that the formation of Schiff base and hydrogen bond interactions affected the properties of the films. The VPC films also showed excellent antioxidant activity. Therefore, vanillin-crosslinked PVA/chitosan active films have broader application prospects as packaging materials for food preservation. Full article

19 pages, 1815 KiB

Open AccessArticle

Boosting Coordination and Employee Motivation in Mega-Project Sustainable Performance Through Quality Relationships: The Key Role of Quality Management System

by Li Ma, Azhar Ali, Muhammad Shoaib Farooq and Jonathan Musonda

Buildings 2025, 15(6), 936; https://doi.org/10.3390/buildings15060936 (registering DOI) - 16 Mar 2025

Abstract

Coordination and employee motivation play vital roles in a mega-project’s sustainable performance, particularly in the construction industry. With increasing demands from stakeholders and employees in the construction sector, sustainable performance has emerged as a priority. However, the importance of quality relationships and quality [...] Read more.

Coordination and employee motivation play vital roles in a mega-project’s sustainable performance, particularly in the construction industry. With increasing demands from stakeholders and employees in the construction sector, sustainable performance has emerged as a priority. However, the importance of quality relationships and quality management systems is often overlooked. This research addresses this gap by establishing a predictive model for sustainable performance. Data from 261 respondents in Pakistan’s construction industry were collected, and hypotheses were tested using partial least squares structural equation modeling. The results indicate that coordination and employee motivation exert a positive impact on sustainable performance. Furthermore, quality relationships partially mediate the relationship between coordination and sustainable performance and between employee motivation and sustainable performance. Additionally, quality management systems significantly moderate the relationship between coordination and sustainable performance, whereas the relationship between employee motivation and sustainable performance is insignificant. This study provides valuable insights for project coordinators, project managers, and policymakers on enhancing the stability of construction projects in emerging economies through quality relationships and quality management systems. Full article

(This article belongs to the Special Issue Strategic Planning and Control in Complex Project Management)

► Show Figures

Figure 1

21 pages, 742 KiB

Open AccessArticle

Exploring Students’ Learning Experiences Under the China–Korea Cooperative Teaching Model: A Positive Psychology Perspective

by Lei Song, Zhenzhen Huang, Luhao Cao and Shanshan Yang

Behav. Sci. 2025, 15(3), 374; https://doi.org/10.3390/bs15030374 (registering DOI) - 16 Mar 2025

Abstract

Based on the theory of learning experiences and the Positive Emotion, Engagement, Relationships, Meaning, and Accomplishment (PERMA) model, this research aims to interpret the learning experiences of students majoring in Animation under the China–Korea cooperative teaching model from a perspective of positive psychology. [...] Read more.

Based on the theory of learning experiences and the Positive Emotion, Engagement, Relationships, Meaning, and Accomplishment (PERMA) model, this research aims to interpret the learning experiences of students majoring in Animation under the China–Korea cooperative teaching model from a perspective of positive psychology. Purposive sampling was conducted to carry out semi-structured interviews with 25 students and 3 teachers. In the thematic analysis, it was found that students’ learning experiences are accompanied by emotions, both positive and negative, and that emotions are correlated with engagement, relationships, meaning, and achievement, which together constitute students’ learning experiences. In addition, this research confirms that students’ learning motivation and learning experiences mutually affect each other, with learning motivation affecting students’ learning experiences on the one hand, and positive elements of learning experiences enhancing students’ learning motivation and bringing positive learning outcomes on the other. Full article

(This article belongs to the Section Educational Psychology)

► Show Figures

Figure 1

11 pages, 1869 KiB

Open AccessArticle

The Impact of a Tongue Training Device on Tongue Muscle Strength in Patients with Obstructive Sleep Apnea After Modified Uvulopalatopharyngoplasty: A Pilot Study

by Yung-An Tsou, Chien-Hao Huang, Yu-Jen Chou, Hsueh-Hsin Kao, Jui-Kun Chiang and Yee-Hsin Kao

Medicina 2025, 61(3), 511; https://doi.org/10.3390/medicina61030511 (registering DOI) - 16 Mar 2025

Abstract

Background and Objectives: Sufficient evidence supports the Iowa Oral Performance Instrument (IOPI) as a reliable tool for measuring tongue strength and endurance as well as an effective assessment instrument for intervention studies. This study aimed to investigate the impact of a tongue [...] Read more.

Background and Objectives: Sufficient evidence supports the Iowa Oral Performance Instrument (IOPI) as a reliable tool for measuring tongue strength and endurance as well as an effective assessment instrument for intervention studies. This study aimed to investigate the impact of a tongue training device, the HEAL, on tongue muscle strength in patients with obstructive sleep apnea (OSA) following modified uvulopalatopharyngoplasty (UPPP), utilizing the IOPI for evaluation. Materials and Methods: We introduced a tongue strengthener, the HEAL, made from medical-grade silicone, designed to improve tongue strength. Each patient was provided with the HEAL and instructed to begin using it one month after undergoing modified UPPP for OSA. The tongue strength of OSA patients was measured using the IOPI both before using the HEAL and approximately 6 weeks later. Results: A total of 66 participants with OSA underwent modified UPPP and were included in the final analysis. The mean age was 39.15 ± 8.84 years, and the mean BMI was 27.41 ± 4.03 kg/m². The duration between the pre- and post-assessment of tongue strength using the HEAL was 42.95 ± 17.97 days. The mean tongue strength pressure before and after using the HEAL was 32.16 ± 16.00 kilopascals (kPa) and 42.95 ± 17.97 kPa, respectively. Tongue strength increased by an average of approximately 52.8% after using the HEAL for an approximate duration of 6 weeks. Conclusions: In the current study, participants with OSA who had undergone modified UPPP and subsequently used the HEAL demonstrated an average improvement of 10.79 kPa in tongue strength—an increase of over 50%—as measured by the IOPI. The interval between the pre- and post-assessment of tongue strength was approximately six weeks. Further studies are needed to validate these findings. Full article

(This article belongs to the Section Dentistry and Oral Health)

► Show Figures

Figure 1

68 pages, 2051 KiB

Open AccessReview

Polyethylene Glycol (PEG) Additive in Polymer Membranes for Carbon Dioxide Separation: A Critical Review on Performances and Correlation with Membrane Structure

by Riccardo Checchetto

Separations 2025, 12(3), 71; https://doi.org/10.3390/separations12030071 (registering DOI) - 16 Mar 2025

Abstract

The efficient separation and removal of carbon dioxide (CO₂) from its mixtures is an important technological challenge to limit effects resulting from the increase of the carbon dioxide concentration in the atmosphere. Membrane technology is an environmentally friendly approach, highly [...] Read more.

The efficient separation and removal of carbon dioxide (CO₂) from its mixtures is an important technological challenge to limit effects resulting from the increase of the carbon dioxide concentration in the atmosphere. Membrane technology is an environmentally friendly approach, highly scalable and less energy-consuming than conventional methods such as adsorption, absorption and cryogenic separation. Hybrid membrane materials incorporating inorganic filler nanostructures in polymer matrices having polyethylene glycol (PEG) as a plasticized additive are promising membrane materials given the presence of CO₂-philic polar functional groups of PEGs and the structural refinements on the blend matrix consequent to the filler distribution. In this review, literature information on hybrid polymer/PEG membranes are critically reviewed to discuss how filler dispersion in the blend matrix gives rise to enhanced CO₂ separation performances with respect to those obtained with traditional mixed matrix membranes where filler nanostructures are dispersed in the neat polymer. The discussion will be focused on the correlation between the CO₂ transport properties, membrane structural properties and defect resulting from the polymer-filler incompatibility. It is shown that hybrid polymer/PEG membranes with dispersed filler nanostructures simultaneously offer improved CO₂ separation performances and enhanced mechanical properties compared with nanocomposite ones where filler particles are dispersed in the neat polymer matrix. PEG addition enhances the filler-matrix compatibility, delays filler aggregation and limits the formation of filler-matrix interface defects. Full article

(This article belongs to the Section Materials in Separation Science)

17 pages, 6790 KiB

Open AccessCase Report

Performance Prediction Criteria Based on Yearling Training Cycle Data for World-Class Athletes’ Tiny 1000-Meter Kayak Teams: A Case Study

by Stanislav Dadelo, Ričardas Nekriošius and Rūta Dadelienė

Life 2025, 15(3), 476; https://doi.org/10.3390/life15030476 (registering DOI) - 16 Mar 2025

Abstract

This research aimed to identify optimal performance needs based on physiological tests of kayakers, revealing body adaptations and critical training periods within a yearly training cycle. It sought to develop performance selection protocols for teams and provide evidence-based strategies for future training. Methods: [...] Read more.

This research aimed to identify optimal performance needs based on physiological tests of kayakers, revealing body adaptations and critical training periods within a yearly training cycle. It sought to develop performance selection protocols for teams and provide evidence-based strategies for future training. Methods: The male athletes underwent routine physiological testing, considering medical limitations. A preparation year plan was established: six months for preparation, one month for the first competition, two months for further preparation, one month for the second competitor, and two months for transition. The athletes faced twelve tests at the start of each month. Results: A certain intensity and duration of training effort during preparatory cycles (approximately 22–42% in the third intensity zone, 24–28% in the fourth intensity zone, and 3–4% in the fifth intensity zone) were necessary for athletes to achieve a high level of aerobic metabolism (64.00 and 69.40 mL·min⁻¹·kg⁻¹). Heart rate, work capacity at the second ventilatory threshold, the critical intensity limit, and maximum oxygen consumption were all shown to be vital indicators for predicting competition results. Conclusions: The identified indicators of physical development and functional capacity could aid in forming a team capable of reaching an elite level in the future. Full article

(This article belongs to the Special Issue Advances and Applications of Sport Physiology)

► Show Figures

Figure 1

17 pages, 701 KiB

Open AccessArticle

All-Integer Quantization for Low-Complexity Min-Sum Successive Cancellation Polar Decoder

by Wittawad Pimsri, Patinya Muangkammuen, Puripong Suthisopapan and Virasit Imtawil

Appl. Sci. 2025, 15(6), 3241; https://doi.org/10.3390/app15063241 (registering DOI) - 16 Mar 2025

Abstract

It is widely acknowledged in communication theory that polar codes have been proven to achieve channel capacity across a range of communication channels. However, their exceptional performance is usually evaluated through simulations or analyses conducted under the assumption of infinite precision, i.e., floating-point [...] Read more.

It is widely acknowledged in communication theory that polar codes have been proven to achieve channel capacity across a range of communication channels. However, their exceptional performance is usually evaluated through simulations or analyses conducted under the assumption of infinite precision, i.e., floating-point arithmetic, which represents an ideal numerical computation. To address this implementation challenge, this work proposes a min-sum successive cancellation (MS-SC) polar decoder employing all-integer quantization to improve practicality in real-world scenarios. To balance the trade-off between practicality and decoding performance, we investigate whether 5-bit all-integer quantization is the optimal choice for the MS-SC polar decoder. Moreover, the simulation results over fading channels show that the proposed decoder achieves a performance almost equivalent to the high-precision successive cancellation (SC) decoder. The integer-based calculation for the MS-SC polar decoder reduces computational complexity by

75 %

compared to the conventional SC decoding algorithm with infinite-precision computation. Full article

(This article belongs to the Special Issue Advanced Digital Signal Processing and Its Applications)

14 pages, 2207 KiB

Open AccessArticle

Serum Proteomic Markers in Patients with Systemic Sclerosis in Relation to Silica Exposure

by Mayka Freire, Bernardo Sopeña, Susana Bravo, Carlos Spuch, Ana Argibay, Melania Estévez, Carmen Pena, Martín Naya, Adela Lama and Arturo González-Quintela

J. Clin. Med. 2025, 14(6), 2019; https://doi.org/10.3390/jcm14062019 (registering DOI) - 16 Mar 2025

Abstract

Background: Systemic sclerosis (SSc) is a multisystem autoimmune disease characterised by fibrosis, vasculopathy, and immune dysfunction. Silica exposure has been associated with a more aggressive phenotype of the disease, including diffuse cutaneous involvement and interstitial lung disease. This study aims to identify proteomic [...] Read more.

Background: Systemic sclerosis (SSc) is a multisystem autoimmune disease characterised by fibrosis, vasculopathy, and immune dysfunction. Silica exposure has been associated with a more aggressive phenotype of the disease, including diffuse cutaneous involvement and interstitial lung disease. This study aims to identify proteomic differences between SSc patients exposed to silica and those not exposed to silica. Methods: An observational study of 32 SSc patients (11 silica-exposed and 21 non-exposed) was performed, with occupational history and quantitative proteomic analysis using SWATH-MS mass spectrometry. Differentially expressed proteins were analysed, and functional pathway enrichment was performed. Results: Eight proteins showed significant differences between groups, all with reduced levels in silica-exposed patients: adiponectin, immunoglobulins (IGLV3-19, IGLV2-18), complement C2, alpha-2-macroglobulin, vitronectin, cytoplasmic actin 2, and pigment epithelium-derived factor. Alterations in pathways related to fibrinolysis, complement activation, and inflammation were highlighted, suggesting that silica exposure may influence the pathogenesis of SSc and worsen its clinical course. Conclusions: This study supports the hypothesis that silica exposure is not only a triggering factor for SSc, but is also modulating its progression through inflammatory, procoagulant, and fibrotic pathways. The identification of proteomic biomarkers could contribute to the phenotypic classification of patients and the development of personalised therapies. Future studies should expand the cohort and further investigate the functional mechanisms of these proteins in SSc. Full article

(This article belongs to the Special Issue News in the Pathogenesis, Diagnosis and Treatment of Systemic Sclerosis)

► Show Figures

Figure 1

19 pages, 1428 KiB

Open AccessArticle

Allocation of Strategic Positions for Storage of Meat Products Requiring Cold Chain

by Fernando J. Olier Herrera, Carlos A. Porto Berrio, Germán Herrera-Vidal, Wilson Adarme, Rodrigo Linfati, Gustavo Gatica and Jairo R. Coronado-Hernández

Foods 2025, 14(6), 1010; https://doi.org/10.3390/foods14061010 (registering DOI) - 16 Mar 2025

Abstract

The objective of this study is to optimize the allocation of storage positions in a cold storage facility for meat products, guaranteeing compliance with the cold chain and improving logistical efficiency. To this end, a mathematical optimization model was designed and applied that [...] Read more.

The objective of this study is to optimize the allocation of storage positions in a cold storage facility for meat products, guaranteeing compliance with the cold chain and improving logistical efficiency. To this end, a mathematical optimization model was designed and applied that strategically assigns storage locations based on inventory turnover and product accessibility. Different configurations were evaluated based on space utilization criteria, access times, and operating costs. Based on the analyzed data, the findings indicate a significant improvement in storage efficiency, with utilization reaching 71.87% in U1, U2, U3, and UE units and 75% in C1 and C2 units. In addition, the new distribution minimized handling times and reduced the risk of product spoilage. Based on these findings, it is demonstrated that optimizing cold storage distribution not only improves inventory management and operational logistics but also contributes to system sustainability by reducing waste and costs associated with inefficient handling of perishable products. Full article

(This article belongs to the Section Meat)

28 pages, 1738 KiB

Open AccessArticle

Educational Transformation Through Emerging Technologies: Critical Review of Scientific Impact on Learning

by Andrés F. Mena-Guacas, Luis López-Catalán, César Bernal-Bravo and Cristóbal Ballesteros-Regaña

Educ. Sci. 2025, 15(3), 368; https://doi.org/10.3390/educsci15030368 (registering DOI) - 16 Mar 2025

Abstract

Educational transformation is increasingly influenced by emerging technologies, which offer unique opportunities to redefine learning. This study aims to critically analyze the scientific production related to the use of emerging technologies in the educational field, focusing on their impact on the teaching–learning process. [...] Read more.

Educational transformation is increasingly influenced by emerging technologies, which offer unique opportunities to redefine learning. This study aims to critically analyze the scientific production related to the use of emerging technologies in the educational field, focusing on their impact on the teaching–learning process. A systematic review of the scientific literature was carried out, analyzing a total of 1567 articles from 2000 to 2024. The results reveal that, although there is a growing interest in the integration of technologies such as artificial intelligence and augmented reality, concerns also emerge about their implementation and effectiveness. In addition, research trends are identified that suggest a multidimensional approach to the use of these technologies, highlighting the importance of teacher training and the educational context in which they are applied. The conclusions indicate that, to maximize the positive impact of these technologies, an informed pedagogical approach that considers the advantages and challenges they entail is essential. This analysis provides a foundation for future studies and guidance for educators and policy makers in effectively incorporating emerging technologies into the educational environment. Full article

(This article belongs to the Special Issue Technology-Mediated Active Learning Methods)

► Show Figures

Figure 1

40 pages, 1855 KiB

Open AccessArticle

Tripartite Evolutionary Game Analysis on the Employment of University Graduates from the Perspective of the Talent Supply Chain Based on Prospect Theory

by Lingwei Fan, Chuan Zhang, Kaiyu Lian and Jingjing Chen

Systems 2025, 13(3), 205; https://doi.org/10.3390/systems13030205 (registering DOI) - 16 Mar 2025

Abstract

From the perspective of the talent supply chain, this paper employs evolutionary game theory to study the decision-making behaviors of university graduates’ employment-related participants, establishes a tripartite evolutionary game model of enterprises, graduates, and universities based on prospect theory, and analyzes the main [...] Read more.

From the perspective of the talent supply chain, this paper employs evolutionary game theory to study the decision-making behaviors of university graduates’ employment-related participants, establishes a tripartite evolutionary game model of enterprises, graduates, and universities based on prospect theory, and analyzes the main factors affecting the system game strategy by combining numerical simulation. The evolutionary game theory is a theory that integrates game theory with the analysis of dynamic evolutionary processes, studying the strategy selection and dynamic equilibrium of bounded rational participants in complex environments. The findings are as follows: (1) The decision-makers influence and promote each other, and universities play a very important role in promoting the employment of graduates. (2) In the case of random initial probability, when the additional profit of each decision-maker is greater than their cost, enterprises, graduates, and universities can realize the ideal model of “recruitment, participation in recruitment, active employment assistance”. The higher the initial probability, the faster the system reaches a steady state. (3) Enhancing the risk perception of enterprises, graduates, and universities has a dual effect on the employment ecosystem. (4) The behavioral strategies of enterprises, graduates, and universities are affected by many factors, such as the initial probability, loss aversion degree, profit and loss sensitivity degree, talent loss risk, cost, and unemployment risk. Full article

(This article belongs to the Section Supply Chain Management)

34 pages, 7670 KiB

Open AccessArticle

A Safe and Efficient Brain–Computer Interface Using Moving Object Trajectories and LED-Controlled Activation

by Sefa Aydin, Mesut Melek and Levent Gökrem

Micromachines 2025, 16(3), 340; https://doi.org/10.3390/mi16030340 (registering DOI) - 16 Mar 2025

Abstract

Nowadays, brain–computer interface (BCI) systems are frequently used to connect individuals who have lost their mobility with the outside world. These BCI systems enable individuals to control external devices using brain signals. However, these systems have certain disadvantages for users. This paper proposes [...] Read more.

Nowadays, brain–computer interface (BCI) systems are frequently used to connect individuals who have lost their mobility with the outside world. These BCI systems enable individuals to control external devices using brain signals. However, these systems have certain disadvantages for users. This paper proposes a novel approach to minimize the disadvantages of visual stimuli on the eye health of system users in BCI systems employing visual evoked potential (VEP) and P300 methods. The approach employs moving objects with different trajectories instead of visual stimuli. It uses a light-emitting diode (LED) with a frequency of 7 Hz as a condition for the BCI system to be active. The LED is assigned to the system to prevent it from being triggered by any involuntary or independent eye movements of the user. Thus, the system user will be able to use a safe BCI system with a single visual stimulus that blinks on the side without needing to focus on any visual stimulus through moving balls. Data were recorded in two phases: when the LED was on and when the LED was off. The recorded data were processed using a Butterworth filter and the power spectral density (PSD) method. In the first classification phase, which was performed for the system to detect the LED in the background, the highest accuracy rate of 99.57% was achieved with the random forest (RF) classification algorithm. In the second classification phase, which involves classifying moving objects within the proposed approach, the highest accuracy rate of 97.89% and an information transfer rate (ITR) value of 36.75 (bits/min) were achieved using the RF classifier. Full article

(This article belongs to the Special Issue Bioelectronics and Its Limitless Possibilities)

► Show Figures

Figure 1

29 pages, 10824 KiB

Open AccessReview

A Neglected Complication of Insulin Therapy Due to Errors in Injection Technique: Skin Lipohypertrophies: A Narrative Review

by Felice Strollo, Giuseppina Guarino and Sandro Gentile

Diabetology 2025, 6(3), 22; https://doi.org/10.3390/diabetology6030022 (registering DOI) - 16 Mar 2025

Abstract

Over 100 years after its commercialization, the insulin administration method still needs elementary education. Such observation contrasts with technological progress constantly elaborating new (e.g., weekly) insulin preparations, capable of mimicking the pharmacokinetics of insulin produced by the human pancreas and exploring alternatives to [...] Read more.

Over 100 years after its commercialization, the insulin administration method still needs elementary education. Such observation contrasts with technological progress constantly elaborating new (e.g., weekly) insulin preparations, capable of mimicking the pharmacokinetics of insulin produced by the human pancreas and exploring alternatives to injection. However, insulin administration remains anchored to the subcutaneous route, thus creating the conditions for lipohypertrophies (LHs), a still too frequent and ubiquitously widespread skin complication that, despite being avoidable with an adequate educational path, affects up to 60% of patients and even more. Considering that there are approximately 580 million adult diabetic people in the world today, at least half of whom (290 million) self-inject insulin, should 50% of the latter have LH, approximately 145 million people and even more? Considering that there are approximately 580 million adult diabetic people in the world today, at least half of whom (290 million) self-inject insulin, should 50% of the latter have LH, approximately 145 million people would suffer from such a complication, thus causing a severe problem for the global health system. Indeed, besides being unsightly, LHs cause poor glycemic control, large glucose variability, and frequent unexplained hypoglycemia, and display a strong correlation with micro- and macrovascular complications, inevitably worsening the quality of life of diabetic people. In this narrative review, after a brief description of the alternative routes of administration to subcutaneous injections, we will recall the causes, consequences, and possible corrective actions of LHs, stigmatizing the fundamental role of therapeutic education and hoping that all this can interest all the actors who revolve around the management of insulin therapy, which is too often underestimated and hastily addressed by health professionals, who probably prefer to dedicate time to titration of therapy. Ultimately, our aim is to provide the reader with a practical review of injection errors resulting from incorrect insulin injection techniques, analyzing the leading causes of error and the consequences of these errors, while also providing advice and suggestions to overcome all this. Full article

(This article belongs to the Special Issue Exclusive Papers Collection of Editorial Board Members in Diabetology)

► Show Figures

Figure 1

34 pages, 4139 KiB

Open AccessReview

Mutual Interactions Between Microbiota and the Human Immune System During the First 1000 Days of Life

by Muy Heang Tang, Ishbel Ligthart, Samuel Varga, Sarah Lebeer, Frans J. van Overveld and Ger T. Rijkers

Biology 2025, 14(3), 299; https://doi.org/10.3390/biology14030299 (registering DOI) - 16 Mar 2025

Abstract

The development of the human immune system starts during the fetal period in a largely, but probably not completely, sterile environment. During and after birth, the immune system is exposed to an increasingly complex microbiota. The first microbiota encountered during passage through the [...] Read more.

The development of the human immune system starts during the fetal period in a largely, but probably not completely, sterile environment. During and after birth, the immune system is exposed to an increasingly complex microbiota. The first microbiota encountered during passage through the birth canal colonize the infant gut and induce the tolerance of the immune system. Transplacentally derived maternal IgG as well as IgA from breast milk protect the infant from infections during the first 100 days, during which the immune system further develops and immunological memory is formed. The Weaning and introduction of solid food expose the immune system to novel (food) antigens and allow for other microbiota to colonize. The cells and molecules involved in the mutual and intricate interactions between microbiota and the developing immune system are now beginning to be recognized. These include bacterial components such as polysaccharide A from Bacteroides fragilis, as well as bacterial metabolites such as the short-chain fatty acid butyrate, indole-3-aldehyde, and indole-3-propionic acid. All these, and probably more, bacterial metabolites have specific immunoregulatory functions which shape the development of the human immune system during the first 1000 days of life. Full article

(This article belongs to the Section Immunology)

► Show Figures

Graphical abstract

19 pages, 3604 KiB

Open AccessArticle

A Finite Element Analysis of Lateral Buckling of Tensile Armor Layers of Flexible Pipes Considering Machining Geometry Defects

by Yongyu Li, Qingzhen Lu, Xiufeng Yue, Hailong Lu, Qianjin Yue and Yangcheng Lu

J. Mar. Sci. Eng. 2025, 13(3), 580; https://doi.org/10.3390/jmse13030580 (registering DOI) - 16 Mar 2025

Abstract

The tensile armor layer plays a crucial role in offshore flexible pipelines, primarily bearing axial tensile loads. However, during installation and operation, it may experience compressive forces, leading to a risk of lateral buckling, which is further intensified by manufacturing deviations in the [...] Read more.

The tensile armor layer plays a crucial role in offshore flexible pipelines, primarily bearing axial tensile loads. However, during installation and operation, it may experience compressive forces, leading to a risk of lateral buckling, which is further intensified by manufacturing deviations in the steel strips. This study introduces a method to quantify these deviations based on the circumferential length change in defect segments in helically wound steel strips. A deviation model is established and analyzed using Abaqus finite element simulations to evaluate the impact of helical angles and deviation severity on the critical lateral buckling load. The results reveal that as the deviation severity increases, the critical buckling load significantly decreases, with reductions of up to 65% for small helical angles. Additionally, the rapid rise in bending moment at the defect location is identified as the primary cause of lateral buckling initiation. Full article

25 pages, 10495 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Wire Laser Additive Manufactured Deposits and Their Tungsten Inert Gas Welds

by Yeong Rae Shim, Jong Kun Kim, Deok Hyun Jo, Hee Pyeong Yang, Seung Wook Yoon, Un Yong Yu, Hyub Lee, Durim Eo, Jong Cheon Yoon, Sunmi Shin, Joong Eun Jung and Jong Bae Jeon

Materials 2025, 18(6), 1308; https://doi.org/10.3390/ma18061308 (registering DOI) - 16 Mar 2025

Abstract

Ti-6Al-4V (Ti64) alloy is widely utilized in the aerospace industry due to its high strength, fatigue resistance, corrosion resistance, and cryogenic properties. However, its high raw material costs and machining difficulties necessitate the development of efficient manufacturing processes. This study evaluates the mechanical [...] Read more.

Ti-6Al-4V (Ti64) alloy is widely utilized in the aerospace industry due to its high strength, fatigue resistance, corrosion resistance, and cryogenic properties. However, its high raw material costs and machining difficulties necessitate the development of efficient manufacturing processes. This study evaluates the mechanical reliability and microstructure of Ti64 components fabricated using wire laser additive manufacturing (WLAM) and subsequently joined via tungsten inert gas (TIG) welding. The WLAM process produces refined microstructures with superior mechanical properties by minimizing defects; however, insufficient process optimization may result in a lack of fusion (LOF) and porosity. Microstructural analysis revealed that the WLAM deposits exhibited a fine basket-weave α structure with an average α-lath width of 1.27 ± 0.69 μm, while the TIG-welded region exhibited a coarsened α-lath, reaching 3.02 ± 2.06 μm, which led to a reduction in ductility. Tensile testing demonstrated that the WLAM deposits exhibited superior mechanical properties, with a yield strength of 910 MPa, ultimate tensile strength of 1015 MPa, and elongation of 12.8%, outperforming conventional wrought Ti64 alloys. Conversely, the TIG-welded joints exhibited reduced mechanical properties, with a yield strength of 812 MPa, ultimate tensile strength of 917 MPa, and elongation of 7.5%, primarily attributed to microstructural coarsening in the weld region. The findings of this study confirm that WLAM enhances the mechanical properties of Ti64, whereas TIG welding may introduce structural weaknesses. This research provides insight into the microstructural evolution and mechanical behavior of WLAM-fabricated Ti64 components, with valuable implications for their application in aerospace structures. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys (Second Edition))

► Show Figures

Figure 1

Recent Articles

Open Access Journals

Highly Accessed Articles

Latest Books

News

Blog Posts

Topics

Selected Special Issues

Selected Collections

Journals by Subject

Further Information

Guidelines

MDPI Initiatives

Follow MDPI