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17 pages, 4364 KiB  
Article
An Investigation of the Effectiveness of Super White Cement in Improving the Engineering Properties of Organic Soils by Laboratory Tests
by Eyubhan Avci, Mehmet C. Balci, Muhammed A. Toprak, Melih Uysal, Emre Deveci, Gözde Algun Karataş and Yunus E. Dönertaş
Buildings 2025, 15(15), 2730; https://doi.org/10.3390/buildings15152730 (registering DOI) - 2 Aug 2025
Abstract
In this study, the efficacy of super white cement (SWC) to improve organic soils was researched. For stabilization, 10%, 15%, and 20% proportions of SWC were added to organic soil. After improvement with SWC, Atterberg limit testing, standard Proctor tests, triaxial compression tests, [...] Read more.
In this study, the efficacy of super white cement (SWC) to improve organic soils was researched. For stabilization, 10%, 15%, and 20% proportions of SWC were added to organic soil. After improvement with SWC, Atterberg limit testing, standard Proctor tests, triaxial compression tests, and swelling and compressibility tests were performed on the organic soil. Proctor tests showed that stabilization of organic soil with SWC increased maximum dry density (MDD) and optimum moisture content (OMC) values. After stabilization, the unconfined compressional strength values of the soil increased. This increase continued until the 28th day and had a reducing trend after improvement with SWC, linked to time. In addition to the reaction between SWC and OS, the time-dependent behavior of OS also contributed to this behavior. With the increase in SWC proportions, the cohesion intercept and internal friction angle values rapidly increased until the 56th day. This increase began to reduce after the 56th day. After stabilization, the swelling percentage and compressibility values for the soil reduced. The addition of SWC within organic soil appeared to improve the engineering properties of the soil. Full article
(This article belongs to the Section Building Materials, and Repair & Renovation)
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12 pages, 249 KiB  
Article
Efficient Implementation of a Robot-Assisted Radical Cystectomy Program in a Naïve Centre Experienced in Open Radical Cystectomy and Other Robot-Assisted Surgeries: A Comparative Analysis of Perioperative Outcomes and Complications
by Gianluca Giannarini, Gioacchino De Giorgi, Maria Abbinante, Carmine Franzese, Jeanlou Collavino, Fabio Traunero, Marco Buttazzi, Antonio Amodeo, Angelo Porreca and Alessandro Crestani
Cancers 2025, 17(15), 2532; https://doi.org/10.3390/cancers17152532 - 31 Jul 2025
Viewed by 148
Abstract
Background/Objectives: While robot-assisted radical cystectomy (RARC) has shown potential benefits over open radical cystectomy (ORC), such as reduced blood loss and quicker recovery, its adoption has been limited because of its complexity and long learning curve, especially for urinary diversion. We assessed whether [...] Read more.
Background/Objectives: While robot-assisted radical cystectomy (RARC) has shown potential benefits over open radical cystectomy (ORC), such as reduced blood loss and quicker recovery, its adoption has been limited because of its complexity and long learning curve, especially for urinary diversion. We assessed whether a RARC program with fully intracorporeal urinary diversion could be safely implemented in a hospital with no prior experience in RARC, but with expertise in ORC and other robotic surgeries. We also compared perioperative outcomes and complications between RARC and ORC during the implementation phase. Methods: This retrospective comparative study included 50 consecutive patients who underwent RARC between June 2023 and January 2025 and 50 patients previously treated with ORC. All RARC cases were performed with intracorporeal urinary diversion. A structured proctoring program guided two surgeons through a stepwise training approach by an expert RARC surgeon. Perioperative outcomes and 90-day complications were compared. Results: All RARC procedures were completed fully intracorporeally with no conversions to open surgery. Compared with ORC, RARC was associated with significantly shorter operative times (for ileal conduit diversion) and hospital stays, lower estimated blood loss, and fewer postoperative complications. There were no differences in intraoperative complications. Worst single grade ≥ 3 complications were significantly less frequent in the RARC than the ORC group (11 [11%] versus 21 [21%], p = 0.045). On multivariable analysis, the robotic approach independently predicted fewer any-grade complications (odds ratio 0.81, 95% confidence intervals 0.65–0.95, p = 0.01). Conclusions: A RARC program can be safely and effectively implemented in a previously RARC-naïve centre with existing surgical expertise. The robotic approach offers clear perioperative benefits and may represent a favourable alternative to open surgery. Full article
18 pages, 2154 KiB  
Article
Performance Limits of Hydraulic-Binder Stabilization for Dredged Sediments: Comparative Case Studies
by Abdeljalil Zri, Nor-Edine Abriak, Amine el Mahdi Safhi, Shima Pilehvar and Mahdi Kioumarsi
Buildings 2025, 15(14), 2484; https://doi.org/10.3390/buildings15142484 - 15 Jul 2025
Viewed by 373
Abstract
Maintenance dredging produces large volumes of fine sediments that are commonly discarded, despite increasing pressure for beneficial reuse. Lime–cement stabilization offers one pathway, yet field performance is highly variable. This study juxtaposes two French marine dredged sediments—DS-F (low plasticity, organic matter (OM) ≈ [...] Read more.
Maintenance dredging produces large volumes of fine sediments that are commonly discarded, despite increasing pressure for beneficial reuse. Lime–cement stabilization offers one pathway, yet field performance is highly variable. This study juxtaposes two French marine dredged sediments—DS-F (low plasticity, organic matter (OM) ≈ 2 wt.%) and DS-M (high plasticity, OM ≈ 18 wt.%)—treated with practical hydraulic road binder (HRB) dosages. This is the first French study that directly contrasts two different DS types under identical HRB treatment and proposes practical boundary thresholds. Physical indexes (particle size, methylene-blue value, Atterberg limits, OM) were measured; mixtures were compacted (Modified Proctor) and tested for immediate bearing index (IBI). IBI, unconfined compressive strength, indirect tensile strength, and elastic modulus were determined. DS-F reached IBI ≈ 90–125%, UCS ≈ 4.7–5.9 MPa, and ITS ≈ 0.40–0.47 MPa with only 6–8 wt.% HRB, satisfying LCPC-SETRA class S2–S3 requirements for road subgrades. DS-M never exceeded IBI ≈ 8%, despite 3 wt.% lime + 6 wt.% cement. A decision matrix distilled from these cases and recent literature shows that successful stabilization requires MBV < 3 g/100 g, plastic index < 25%, OM < 7 wt.%, and fine particles < 35%. These thresholds permit rapid screening of dredged lots before costly treatment. Highlighting both positive and negative evidence clarifies the realistic performance envelope of soil–cement reuse and supports circular-economy management of DS. Full article
(This article belongs to the Collection Advanced Concrete Materials in Construction)
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14 pages, 1775 KiB  
Article
Characterization of Recycled Aggregates from Building Demolition Waste for Use in Road Infrastructures
by Majid Ahmadpour, Davood Akbarimehr, Mohammad Rahai and Ali Momeni
Infrastructures 2025, 10(7), 167; https://doi.org/10.3390/infrastructures10070167 - 1 Jul 2025
Viewed by 262
Abstract
In light of rising environmental concerns, the rapid industrial recycling of building demolition waste material (BDWM) is now capable of supporting sustainable development in metropolitan regions. From this perspective, the current study investigated the geotechnical properties and applications of BDWMs as substitutes for [...] Read more.
In light of rising environmental concerns, the rapid industrial recycling of building demolition waste material (BDWM) is now capable of supporting sustainable development in metropolitan regions. From this perspective, the current study investigated the geotechnical properties and applications of BDWMs as substitutes for natural materials (NMs) in road engineering infrastructures. For this purpose, the physical and geotechnical characteristics of both types of materials were initially examined, and then compared using laboratory-scale material comprehensive assessments such as sieve analysis (SA), the flakiness index (FI), the specific gravity test (Gs), the Los Angeles abrasion test (LAAT), Atterberg limits (AL), the water absorption test (WAT), the California bearing ratio (CBR), the direct shear test (DST), and the Proctor soil compaction test (PSCT). The BDWMs were collected from two locations in Iran. According to the results, the collected samples consisted of concrete, bricks, mortar, tile materials, and others. The CBR values for the waste material from the two sites were 69 and 73%, respectively. Furthermore, the optimum water content (OWC) and maximum dry unit weight (MDD) from the two sites were reported as 9.3 and 9.9% and 20.8 and 21 kN/m3, respectively, and the hydrogen potential (pH) as 9 and 10. The shear strength and CBR values indicated that the BDWM had a suitable strength compared to the NM. In terms of road infrastructure applications, the shear strengths were adequate for the analysis of common sub-base materials used in filling and road construction. Furthermore, the study’s findings revealed that BDWMs were suitable replacements for the NM used in road engineering operations and could make a significant contribution to sustainable development. Full article
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12 pages, 743 KiB  
Article
Genetic Correlates of Synergy Mechanisms of Daptomycin Plus Fosfomycin in Daptomycin-Susceptible and -Resistant Methicillin-Resistant Staphylococcus aureus (MRSA)
by Warren E. Rose, Selvi C. Ersoy, Wessam Abdelhady, Alan R. Dominguez, Jedidiah Ndam Muyah Manna, Jorge N. Artaza, Reetakshi Mishra, Ahmed M. Elsayed, Richard A. Proctor, Sarah L. Baines, Benjamin P. Howden and Nagendra N. Mishra
Microorganisms 2025, 13(7), 1532; https://doi.org/10.3390/microorganisms13071532 - 30 Jun 2025
Viewed by 496
Abstract
This study elucidates potential genetic determinants and mechanisms involved in the synergistic effects of daptomycin (DAP) + fosfomycin (FOF) combination therapy. Among 33 clinically derived DAP-susceptible (S)/DAP-resistant (R) isogenic strain pairs, mutations in the mprF gene occurred in 30/33 DAP-R strains, including polymorphisms [...] Read more.
This study elucidates potential genetic determinants and mechanisms involved in the synergistic effects of daptomycin (DAP) + fosfomycin (FOF) combination therapy. Among 33 clinically derived DAP-susceptible (S)/DAP-resistant (R) isogenic strain pairs, mutations in the mprF gene occurred in 30/33 DAP-R strains, including polymorphisms of L826F (33%) or T345A/L/I (15%). Strain variants of DAP-S CB1483 serially passaged in vitro for 10 days in DAP +/− FOF identified a key non-synonymous mutation in mprF (L826F) only in the DAP monotherapy arm. Interestingly, passage in FOF alone or DAP + FOF prevented the emergence of this mprF mutation following 10-day passage. This L826F mprF polymorphism, associated with a “gain-in-function” phenotype, exhibited increased amounts of lysyl-phosphatidylglycerol (L-PG) in the cell membrane (CM). Transcriptomics revealed a relatively modest number (~10) of distinct genes that were significantly up- or downregulated (≥2 log fold) in both the DAP-S and DAP-R strain pairs upon DAP + FOF exposures (vs. DAP or FOF alone). Of note, DAP + FOF decreased expression of lrgAB and sdrE and increased the expression level of fosB. In a rabbit infective endocarditis (IE) model, the DAP-R CB185 strain treated with DAP +/− FOF showed significantly reduced lrgB expression in vegetations compared with DAP treatment alone. Overall, these findings indicate that DAP + FOF therapy impacts MRSA through multiple specific mechanisms, enhancing bacterial clearance. Full article
(This article belongs to the Section Antimicrobial Agents and Resistance)
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18 pages, 644 KiB  
Article
Responsible and Ethical Use of AI in Education: Are We Forcing a Square Peg into a Round Hole?
by Alexander Amigud and David J. Pell
World 2025, 6(2), 81; https://doi.org/10.3390/world6020081 - 3 Jun 2025
Viewed by 2225
Abstract
The emergence of generative AI has caused a major dilemma—as higher education institutions prepare students for the workforce, the development of digital skills must become a normative aim, while simultaneously preserving academic integrity and credibility. The challenge they face is not simply a [...] Read more.
The emergence of generative AI has caused a major dilemma—as higher education institutions prepare students for the workforce, the development of digital skills must become a normative aim, while simultaneously preserving academic integrity and credibility. The challenge they face is not simply a matter of using AI responsibly but typically of reconciling two opposing duties: (A) preparing students for the future of work, and (B) maintaining the traditional role of developing personal academic skills, such as critical thinking, the ability to acquire knowledge, and the capacity to produce original work. Higher education institutions must typically balance these objectives while addressing financial considerations, creating value for students and employers, and meeting accreditation requirements. Against this need, this multiple-case study of fifty universities across eight countries examined institutional response to generative AI. The content analysis revealed apparent confusion and a lack of established best practices, as proposed actions varied widely, from complete bans on generated content to the development of custom AI assistants for students and faculty. Oftentimes, the onus fell on individual faculty to exercise discretion in the use of AI, suggesting an inconsistent application of academic policy. We conclude by recognizing that time and innovation will be required for the apparent confusion of higher education institutions in responding to this challenge to be resolved and suggest some possible approaches to that. Our results, however, suggest that their top concern now is the potential for irresponsible use of AI by students to cheat on assessments. We, therefore, recommend that, in the short term, and likely in the long term, the credibility of awards is urgently safeguarded and argue that this could be achieved by ensuring at least some human-proctored assessments are integrated into courses, e.g., in the form of real-location examinations and viva voces. Full article
(This article belongs to the Special Issue AI-Powered Horizons: Shaping Our Future World)
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13 pages, 2603 KiB  
Article
Metabolic Imaging of Hyperpolarized [1-13C]Pyruvate in a Ferret Model of Traumatic Brain Injury
by Dirk Mayer, Abubakr Eldirdiri, Amanda L. Hrdlick, Boris Piskoun, Joshua C. Rogers, Aditya Jhajharia, Minjie Zhu, Julie L. Proctor, Ulrich H. Leiste, William L. Fourney, Jody C. Cantu, Gary Fiskum and Molly J. Goodfellow
Int. J. Mol. Sci. 2025, 26(11), 5327; https://doi.org/10.3390/ijms26115327 - 1 Jun 2025
Viewed by 568
Abstract
It is increasingly recognized that early perturbation of energy metabolism might have important implications in management and ultimately the neurological outcome in patients with traumatic brain injury (TBI). At the same time, treatments and screening tools successfully developed in preclinical TBI models have [...] Read more.
It is increasingly recognized that early perturbation of energy metabolism might have important implications in management and ultimately the neurological outcome in patients with traumatic brain injury (TBI). At the same time, treatments and screening tools successfully developed in preclinical TBI models have failed to translate to the clinic. As ferrets possess primate-like gyrencephalic brains that may better replicate the human response to neurologic injury, the goal of this study was to noninvasively measure brain energy metabolism after injury in a ferret model of TBI. To this end, metabolic imaging of hyperpolarized (HP) [1-13C]pyruvate (Pyr) and its conversion to lactate (Lac) and bicarbonate (Bic) was performed in ferrets before and after combined under-vehicle blast and controlled cortical impact injury. Reduced Bic/Pyr, reflecting reduced pyruvate dehydrogenase activity, was detected 8–10 days post-injury whereas no difference in Lac/Pyr was observed. These results demonstrate the feasibility of using metabolic imaging of HP [1-13C]Pyr to measure perturbations in brain energy metabolism in a novel highly translatable animal model of TBI. The method may contribute to both improved understanding of injury mechanisms and more effective drug development. Full article
(This article belongs to the Special Issue New Breakthroughs in Molecular Diagnostic Tools for Human Diseases)
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25 pages, 1403 KiB  
Article
A Comparative Analysis of AI Privacy Concerns in Higher Education: News Coverage in China and Western Countries
by Yujie Xue, Vinayagum Chinapah and Chang Zhu
Educ. Sci. 2025, 15(6), 650; https://doi.org/10.3390/educsci15060650 - 25 May 2025
Viewed by 1984
Abstract
This study examines how Chinese and Western news media covered artificial intelligence (AI) privacy issues in higher education from 2019 to 2024. News articles were retrieved from Nexis Uni. First, non-negative matrix factorization (NMF) was employed to identify core AI privacy topics in [...] Read more.
This study examines how Chinese and Western news media covered artificial intelligence (AI) privacy issues in higher education from 2019 to 2024. News articles were retrieved from Nexis Uni. First, non-negative matrix factorization (NMF) was employed to identify core AI privacy topics in university teaching, administration, and research. Next, a time trend analysis investigated how media attention shifted in relation to key events, including the COVID-19 pandemic and the emergence of generative AI. Finally, a sentiment analysis was conducted to compare the distribution of positive, negative, and neutral reporting. The findings indicate that AI-driven proctoring, student data security, and institutional governance are central concerns in both Chinese and English media. However, the focus and framing differ: some Western outlets highlight individual privacy rights and controversies in remote exam monitoring, while Chinese coverage more frequently addresses AI-driven educational innovation and policy support. The shift to remote education after 2020 and the rise of generative AI from 2023 onward have intensified discussions on AI privacy in higher education. The results offer a cross-cultural perspective for institutions seeking to reconcile the adoption of AI with robust privacy safeguards and provide a foundation for future data governance frameworks under diverse regulatory environments. Full article
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26 pages, 6969 KiB  
Article
Sustainable Stabilization of Soil–RAP Mixtures Using Xanthan Gum Biopolymer
by Jair Arrieta Baldovino, Andrés Pérez Durán and Yamid E. Nuñez de la Rosa
Sustainability 2025, 17(10), 4601; https://doi.org/10.3390/su17104601 - 17 May 2025
Viewed by 741
Abstract
Xanthan gum (XG) is a biopolymer primarily composed of polysaccharides that is increasingly employed to stabilize problematic soils. Although promising results have been obtained in clayey soils, its effect on other geomaterials remains underexplored. This study investigates the impact of XG on the [...] Read more.
Xanthan gum (XG) is a biopolymer primarily composed of polysaccharides that is increasingly employed to stabilize problematic soils. Although promising results have been obtained in clayey soils, its effect on other geomaterials remains underexplored. This study investigates the impact of XG on the mechanical strength (qu), stiffness (Go), and microstructure of compacted mixtures of soil and reclaimed asphalt pavement (RAP). A two-part mixing method was adopted: Initially, the XG was mixed with water to form a hydrosolution before mixing in the soil and subsequently combined with the soil–RAP mixture. Xanthan gum was incorporated at dosages of 0.5%, 1.0%, 1.5%, and 2.0% relative to the dry soil weight, while RAP contents were varied at 10%, 20%, and 30% on a dry soil basis. The compaction density was adjusted between 17 and 18 kN/m³, with an optimum moisture content of 18% as determined by the Proctor test. Specimens were cured in a humid chamber for 14 and 28 days. The experimental methodology included unconfined compression tests, ultrasonic pulse velocity measurements, and characterization using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM–EDS). The findings show that the mechanical strength of the soil–RAP mixture increased with the incorporation of up to 1% XG, which was identified as the optimal dosage. The strength values declined at higher dosages (1.5% and 2.0%). Moreover, the highest strength and stiffness were achieved with a 10% RAP content, while mixtures containing 20% and 30% RAP exhibited reduced performance. Microstructural analysis revealed that at 1% XG, there was a pronounced interaction between the XG and the soil–RAP matrix; however, as the RAP content increased, the larger voids present led only to a moderate interaction between the materials. Additionally, a correlation between the stiffness parameter (Go) and the unconfined compressive strength (qu) was established, showing that the Go/qu ratio was dependent on the percentage of XG yet remained independent of curing time—a finding that contrasts with previous correlations for this type of soil that were unaffected by other factors. Full article
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13 pages, 568 KiB  
Article
Impact of Institutional Monthly Volume of Transcatheter Edge-to-Edge Repair Procedures for Significant Mitral Regurgitation: Evidence from the GIOTTO-VAT Study
by Nicola Corcione, Paolo Ferraro, Filippo Finizio, Michele Cimmino, Michele Albanese, Alberto Morello, Giuseppe Biondi-Zoccai, Paolo Denti, Antonio Popolo Rubbio, Francesco Bedogni, Antonio L. Bartorelli, Annalisa Mongiardo, Salvatore Giordano, Francesco De Felice, Marianna Adamo, Matteo Montorfano, Francesco Maisano, Giuseppe Tarantini, Francesco Giannini, Federico Ronco, Emmanuel Villa, Maurizio Ferrario, Luigi Fiocca, Fausto Castriota, Angelo Squeri, Martino Pepe, Corrado Tamburino and Arturo Giordanoadd Show full author list remove Hide full author list
Medicina 2025, 61(5), 904; https://doi.org/10.3390/medicina61050904 - 16 May 2025
Viewed by 432
Abstract
Background and Objectives: Mitral valve transcatheter edge-to-edge repair (TEER) is a widely adopted therapeutic approach for managing significant mitral regurgitation (MR) in high-risk surgical candidates. While procedural safety and efficacy have been demonstrated, the impact of institutional expertise on outcomes remains unclear. [...] Read more.
Background and Objectives: Mitral valve transcatheter edge-to-edge repair (TEER) is a widely adopted therapeutic approach for managing significant mitral regurgitation (MR) in high-risk surgical candidates. While procedural safety and efficacy have been demonstrated, the impact of institutional expertise on outcomes remains unclear. We aimed at evaluating whether the institutional monthly volume of TEER influences short- and long-term clinical results. Materials and Methods: This analysis from the multicenter, prospective GIOTTO trial study evaluated the impact of institutional monthly volume on outcomes of TEER to remedy significant mitral regurgitation. Centers were stratified into tertiles based on monthly volumes (≤2.0 cases/month, 2.1–3.5 cases/month, >3.5 cases/month), and key clinical, echocardiographic, and procedural outcomes were analyzed. Statistical analysis was based on standard bivariate tests as well as unadjusted and multivariable adjusted Cox models. Results: A total of 2213 patients were included, stratified into tertiles based on institutional procedural volume: 645 (29.1%) patients in the first tertile, 947 (42.8%) patients in the second tertile, and 621 (28.1%) patients in the third tertile. Several baseline differences were found, with some features disfavoring less busy centers (e.g., functional class and surgical risk, both p < 0.05), and others suggesting a worse risk profile in those treated in busier institutions (e.g., frailty and history of prior mitral valve intervention, both p < 0.05). Procedural success rates were higher in busier centers (p < 0.001), and hospital stay was also shorter there (p < 0.001). Long-term follow-up (median 14 months) suggested worse outcomes in patients treated in less busy centers at unadjusted analysis (e.g., p = 0.018 for death, p = 0.015 for cardiac death, p = 0.014 for death or hospitalization for heart failure, p < 0.001 for cardiac death or hospitalization for heart failure), even if these associations proved no longer significant after multivariable adjustment, except for cardiac death or hospitalization for heart failure, which appeared significantly less common in the busiest centers (p < 0.05). Similar trends were observed when focusing on tertiles of overall center volume and when comparing for each center the first 50 cases with the following ones. Conclusions: High institutional monthly volume of TEER mitral valve repair appears to correlate with an improved procedural success rate and shorter hospitalizations. Similarly favorable results were found for long-term rates of cardiac death or hospitalization for heart failure. These findings inform on the importance of operator experience and center expertise in achieving state-of-the-art results with TEER, while confirming the usefulness of the proctoring approach when naïve centers begin a TEER program. Full article
(This article belongs to the Special Issue Transcatheter Therapies for Valvular Heart Disease)
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19 pages, 5048 KiB  
Article
Stabilization of Clay Subgrade Soil by Using Waste Foundry Sand with a Geogrid
by Qais Sahib Banyhussan, Jaafar Abdulrazzaq, Ahmed A. Hussein, Anmar Dulaimi, Jorge Miguel de Almeida Andrade and Luís Filipe Almeida Bernardo
CivilEng 2025, 6(2), 26; https://doi.org/10.3390/civileng6020026 - 10 May 2025
Viewed by 1111
Abstract
Various stabilizers, such as jute, gypsum, rice-husk ash, fly ash, cement, lime, and discarded rubber tires, are commonly used to improve the shear strength and overall characteristics of clay subgrade soil. In this study, waste foundry sand (WFS) is utilized as a stabilizing [...] Read more.
Various stabilizers, such as jute, gypsum, rice-husk ash, fly ash, cement, lime, and discarded rubber tires, are commonly used to improve the shear strength and overall characteristics of clay subgrade soil. In this study, waste foundry sand (WFS) is utilized as a stabilizing material to enhance the properties of clay subgrade soil and strengthen the bond between clay subgrade soil and subbase material. The materials employed in this study include Type B subbase granular materials, clay subgrade soil, and 1100 Biaxial Geogrid for reinforcement. The clay subgrade soil was collected from the airport area in the Al-Muthanna region of Baghdad. To evaluate the effectiveness of WFS as a stabilizer, soil specimens were prepared with varying replacement levels of 0%, 5%, 10%, and 15%. This study conducted a Modified Proctor Test, a California Bearing Ratio test, and a large-scale direct shear test to determine key parameters, including the CBR value, maximum dry density, optimum moisture content, and the compressive strength of the soil mixture. A specially designed large-scale direct shear apparatus was manufactured and utilized for testing, which comprised an upper square box measuring 20 cm × 20 cm × 10 cm and a lower rectangular box with dimensions of 200 mm × 250 mm × 100 mm. The findings indicate that the interface shear strength and overall properties of the clay subgrade soil improve as the proportion of WFS increases. Full article
(This article belongs to the Section Geotechnical, Geological and Environmental Engineering)
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21 pages, 4542 KiB  
Article
Assessing the Potential of Lateritic Clayey Soils for Road Infrastructure in Tropical Regions
by Antônio Carlos Rodrigues Guimarães, Albeds Mesquita Povuação, Gabriel de Carvalho Nascimento, Sergio Neves Monteiro and Lisley Madeira Coelho
Materials 2025, 18(8), 1804; https://doi.org/10.3390/ma18081804 - 15 Apr 2025
Viewed by 715
Abstract
Lateritic soils, characterized by complex mineralogy, a high degree of weathering, and a distinctive structure, are widely distributed in tropical regions. However, their use in pavement layers is often restricted due to conservative soil classification methods that may not fully represent their mechanical [...] Read more.
Lateritic soils, characterized by complex mineralogy, a high degree of weathering, and a distinctive structure, are widely distributed in tropical regions. However, their use in pavement layers is often restricted due to conservative soil classification methods that may not fully represent their mechanical potential. This study evaluates the geotechnical behavior of a lateritic clay from a small town in São Paulo, referred to in this article as Purple Clay, with a focus on its permanent deformation (PD) and resilient modulus (RM). Repeated load triaxial tests, along with X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), were conducted to assess the soil’s mechanical response and microscopic structure. The results indicated that the high concentration of iron oxides contributed to increased cohesion and mechanical strength. When compacted at intermediate Proctor energy, the Purple Clay exhibited RM values comparable to some granular materials reported in the literature, highlighting its potential for pavement applications. However, under higher stress levels, PD was up to 42% greater than that of reference materials, emphasizing the influence of loading conditions on its behavior. Full article
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23 pages, 9445 KiB  
Article
Developing New Geomaterials: The Case of the Natural Rubber Latex Polymers in Soil Stabilization
by Jair Arrieta Baldovino, Kevin Cardenas Diaz, Jorge Martínez Royero, Rohonal Serrano Sierra and Yamid E. Nuñez de la Rosa
Materials 2025, 18(8), 1720; https://doi.org/10.3390/ma18081720 - 9 Apr 2025
Cited by 1 | Viewed by 663
Abstract
This study explores using natural rubber latex (NRL) as a sustainable polymeric additive to improve the mechanical performance of cement-stabilized soil–crushed limestone waste (CLW) mixtures for pavement base applications. The experimental program involved varying cement contents (3%, 6%, and 9% by weight of [...] Read more.
This study explores using natural rubber latex (NRL) as a sustainable polymeric additive to improve the mechanical performance of cement-stabilized soil–crushed limestone waste (CLW) mixtures for pavement base applications. The experimental program involved varying cement contents (3%, 6%, and 9% by weight of soil) and NRL replacement levels (10%, 15%, 20%, and 25% of an 18% optimum water content, as determined by the standard Proctor test) under two target dry unit weights (16.6 and 17.6 kN/m3) and curing periods of 7 and 28 days. Unconfined compressive strength (UCS) tests and stiffness (Go) measurements were performed, while microstructural developments were examined using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The results indicate that an optimal NRL replacement exists for each cement content, enhancing interparticle bonding through the formation of polymeric films that reduce porosity and improve the ductility of the matrix. However, excessive NRL was found to retard cement hydration and ultimately decrease strength. On average, a 28-day curing period produced a 38% increase in UCS over 7-day values, independent of the NRL dosage. Comparisons with literature standards, including the ASTM D4609 threshold of 345 kPa for field strength, confirm that the optimized mixtures meet and exceed the minimum performance requirements. These findings underscore the potential of NRL as a viable alternative to conventional synthetic latexes in sustainable pavement base materials. Full article
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20 pages, 1322 KiB  
Article
The Impact of the COVID-19 Pandemic upon Mathematics Assessment in Higher Education
by Eabhnat Ní Fhloinn and Olivia Fitzmaurice
Educ. Sci. 2025, 15(4), 449; https://doi.org/10.3390/educsci15040449 - 3 Apr 2025
Viewed by 696
Abstract
Historically, the assessment of mathematics in higher education comprised closed-book, summative, proctored examinations. Related disciplines and subjects like statistics, mathematics education, and the history of mathematics lend themselves to a broader range of assessment techniques that have been reported to provide a more [...] Read more.
Historically, the assessment of mathematics in higher education comprised closed-book, summative, proctored examinations. Related disciplines and subjects like statistics, mathematics education, and the history of mathematics lend themselves to a broader range of assessment techniques that have been reported to provide a more balanced picture of students’ abilities. In 2020, an online environment for the teaching and learning of mathematics was imposed on the academic world globally as a result of the COVID-19 pandemic. In an effort to teach and assess remotely while maintaining institutional academic standards, the majority of lecturers were in a situation where closed-book, proctored assessments were not an option. As a result, other methods were adopted. This paper reports on an investigation into how mathematics lecturers worldwide assessed mathematics before the pandemic, during the initial lockdown restrictions, and in the immediate aftermath, while some restrictions were still in place, to see if any changes were sustained. There was a statistically significant difference in the proportion of respondents who used many of the assessment types investigated across the three time periods, including open-book timed, open-book untimed, closed-book, multiple-choice questions, online proctored, in-person proctored, presentations, projects, and assignments. The majority of those who favoured closed-book proctored examinations prior to the pandemic moved to timed open-book assessments. Differences between the weightings of final examinations versus continuous assessments were also statistically significant, with greater weight given to continuous assessment once the pandemic began. Respondents’ satisfaction levels with their assessments were significantly different also, with the highest satisfaction levels prior to the pandemic and the lowest during the initial lockdown restrictions. Academic integrity was a key concern of the majority of respondents when assessing the learning outcomes of their modules and played a role in the vehicle of assessment they chose. Full article
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43 pages, 3450 KiB  
Article
Analysis of Technologies for the Reclamation of Illegal Landfills: A Case Study of the Relocation and Management of Chromium and Arsenic Contamination in Łomianki (Poland)
by Janusz Sobieraj and Dominik Metelski
Sustainability 2025, 17(7), 2796; https://doi.org/10.3390/su17072796 - 21 Mar 2025
Viewed by 1230
Abstract
The reclamation of illegal landfills poses a significant threat to the environment. An example of such a case is Łomianki near Warsaw, where an illegal landfill contained alarming levels of arsenic and chromium, posing a potential risk to the health of local residents [...] Read more.
The reclamation of illegal landfills poses a significant threat to the environment. An example of such a case is Łomianki near Warsaw, where an illegal landfill contained alarming levels of arsenic and chromium, posing a potential risk to the health of local residents due to the possibility of these metals contaminating a nearby drinking water source. Initial geochemical tests revealed high concentrations of these metals, with chromium reaching up to 24,660 mg/kg and arsenic up to 10,350 mg/kg, well above international environmental standards. This study presents effective reclamation strategies that can be used in similar situations worldwide. The reclamation allowed this land to be used for the construction of the M1 shopping center while minimizing environmental hazards. The study is based on a case study of the reclamation of this illegal landfill. The methods used in this project included the relocation of approximately 130,000 m3 of hazardous waste to a nearby site previously used for sand mining. Bentonite mats and geotextiles were used to prevent the migration of contaminants into the groundwater. The waste was layered with sand to assist in the structural stabilization of the site. In addition, proper waste segregation and drainage systems were implemented to manage water and prevent contamination. Eight years after the reclamation, post-remediation soil surveys showed significant improvements in soil quality and structural stability. Specifically, the Proctor Compaction Index (IS) increased from an estimated 0.5–0.7 (for uncontrolled slope) to 0.98, indicating a high degree of compaction and soil stability, while arsenic and chromium levels were reduced by 98.4% and 98.1%, respectively. Reclamation also significantly reduced permeability and settlement rates, further improving the site’s suitability for construction. The cost-benefit analysis showed a cost saving of 37.7% through local waste relocation compared to off-site disposal, highlighting the economic efficiency and environmental benefits. The main conclusions of this study are that land reclamation effectively reduced environmental hazards; innovative solutions, such as bentonite mats, advanced waste sorting, geotextiles, and drainage systems, improved environmental quality; and the Łomianki case serves as a model for sustainable waste management practices. Full article
(This article belongs to the Section Sustainable Engineering and Science)
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