Search Results (146)

This study aimed to prepare water-based nanofluids using Al₂O₃ nanoparticles with different types of surfactants, and to investigate the colloidal and thermophysical properties of the obtained nanofluids. In this context, water-based Al₂O₃ nanofluids have been prepared using six surfactants with anionic, cationic, and nonionic characteristics SDS, CTAC, PVP, Tween 80, PVA, and Triton X-100. The electrostatic colloidal stability of the prepared samples has been determined by zeta potential and particle size measurements. To understand the interactions at the molecular level and the stabilities in terms of interaction Gibbs free energy, nanoparticle–surfactant interactions have been modeled using the DFT (Density Functional Theory) method. The overall colloidal stability rankings of nanofluids have been performed using both zeta potential measurements and DFT analysis. Furthermore, the thermophysical properties of nanofluids, which are crucial for industrial applications, have been measured. The results showed that the type of surfactant has a significant effect on the colloidal and thermophysical properties of nanofluids. It has been concluded that Al₂O₃-SDS and Al₂O₃-CTAC nanofluids can be used in cooling systems due to their high zeta potential and thermal conductivity, and low viscosity and size. Full article

The wettability differences among macroscopic coal lithotypes constitute a critical issue requiring in-depth investigation in the development of low-rank coalbed methane. To elucidate the impact of wettability variation on methane adsorption/desorption, this study employed vitrain and durain samples from Jurassic low-rank coals in the Huanglong Coalfield. We analyzed changes in adsorption/desorption characteristics before and after wettability modification and conducted coal seam desorption experiments under simulated extraction conditions to explore the influence of wettability on methane adsorption/desorption behavior. The results indicate that vitrain exhibits greater full-scale pore volume (0.04073–0.07975 cm³/g) and specific surface area (132.302–170.919 m²/g) compared to durain (0.03646–0.05187 cm³/g and 114.572–122.827 m²/g, respectively). The coal–water interface contact angles of the low-rank coals are below 90°, indicating a weakly hydrophilic nature. Both cationic (CTAC) and zwitterionic (BS-12) surfactants effectively improved coal wettability. Following wettability modification, the maximum reduction in saturated adsorption capacity reached 48.24%, while the maximum increases in desorption ratio and recovery efficiency were 35.56% and 24.39%, respectively. Durain, due to its stronger inherent hydrophilicity, exhibited greater changes than vitrain. Under simulated extraction conditions, the combined effects of pore structure and wettability differences between the lithotypes led to preferential methane production along the vitrain–durain interfaces. Full article

Reliable forecasts of dam releases are essential to anticipate downstream hydrological responses and to improve the operation of fluvial early warning systems. This study integrates an explicit release prediction module into a digital forecasting framework using the Lindoso–Touvedo hydropower cascade in northern Portugal as a case study. A data-driven approach couples short-term electricity price forecasts, obtained with a gated recurrent unit (GRU) neural network, with dam release forecasts generated by a Random Forest model and an LSTM model. The models (GRU and LSTM) were trained and validated on hourly data from November 2024 to April 2025 using a rolling 80/20 split. The GRU achieved R² = 0.93 and RMSE = 3.7 EUR/MWh for price prediction, while the resulting performance metrics confirm the high short-term skill of the LSTM model, with MAE = 4.23 m³ s⁻¹, RMSE = 9.96 m³ s⁻¹, and R² = 0.98. The surrogate Random Forest model reached R² = 0.91 and RMSE = 47 m³/s for 1 h discharge forecasts. Comparison tests confirmed the statistical advantage of the AI approach over empirical rules. Integrating the release forecasts into the Delft FEWS environment demonstrated the potential for real-time coupling between energy market information and hydrological forecasting. By improving forecast reliability and linking hydrological and energy domains, the framework supports safer communities, more efficient hydropower operation, and balanced river basin management, advancing the environmental, social, and economic pillars of sustainability and contributing to SDGs 7, 11, and 13. Full article

N-chlorotaurine (Tau-Cl) is a mild oxidizing haloamine formed from the reaction of hypochlorous acid (HOCl) with taurine (2-amino-ethanesulfonic acid). It is widely used as a topical antiseptic. In this study, we investigated haloamines derived from the neurotransmitter γ-aminobutyric acid, specifically GABA chloramine and bromamine (GABA-Cl, GABA-Br), as well as their halogenated γ-aminobutyric acid ethyl esters (GABAet-Cl, GABAet-Br). Due to their higher hydrophobicity, the esterified haloamines were more potent oxidants in the presence of lyophilic surfactant micelles, demonstrating their greater ability to access hydrophobic environments. By using fluorescent azapentalenes as molecular targets incorporated into sodium dodecyl sulfate (SDS) micelles, the second-order oxidation rate constants (k₂) resulted in 1.15 × 10² and 1.10 × 10⁴ M⁻¹min⁻¹ for GABA-Cl and GABAet-Cl, respectively. As expected, due to the presence of a bromine atom, GABAet-Br was even more reactive (4.50 × 10⁶ M⁻¹min⁻¹). The ability of GABAet-Br to access hydrophobic sites was demonstrated by comparing the reaction rate using micelles generated by different surfactants such as SDS (4.5 × 10⁶ M⁻¹min⁻¹), cetyltrimethylammonium chloride (CTAC, 2.5 × 10⁴ M⁻¹min⁻¹), and triton X-100 (TX-100, 3.9 × 10³ M⁻¹min⁻¹). GABAet-Cl and GABAet-Br exhibited higher bactericidal activity against Staphylococcus aureus and Escherichia coli, probably due to their increased lipophilicity and improved penetration into microorganisms compared to GABA-Cl and GABA-Br. The enhancement of the oxidation capacity by GABAet-Cl and GABAet-Br represents a new direction in the exploration and application of haloamines as antiseptic agents. Full article

The need to address long-term sustainability goals while ensuring short-term resilience to unexpected disruptions is placing an increasing challenge on urban mobility systems. This study organizes an analytical framework that compares and integrates the concepts of sustainability and resilience in urban mobility. A scoping review and thematic analysis were conducted to identify and compare the definitions, dimensions, and operational features of these two paradigms. The results reveal that, although they are conceptually distinct, sustainability and resilience share subjects of analysis, including multimodality and diversity of transport modes, the impacts of climate change, and social equity issues. However, they also present tensions between the dimensions of efficiency and redundancy, speed of recovery and sustainability of implemented solutions, and new vulnerabilities introduced by sustainable technologies. These synergies and trade-offs underscore the necessity of an integrated, systemic and holistic approach to urban mobility planning. The study emphasizes that building resilient and sustainable urban mobility requires coherent policies across government levels, technical capacity, public engagement, and comprehensive indicators. Recommendations for future research include developing integrated metrics and planning tools to support evidence-based decision-making. Full article

This study applies a multicriteria decision analysis to explore how experts from different backgrounds assess traditional and emerging criteria for urban cycling. A hierarchical model with 7 main criteria and 31 subcriteria was evaluated by 30 specialists from academic, technical, and user-focused groups. Using pairwise comparisons and aggregated judgments, this study reveals points of agreement and divergence among expert priorities. Safety and infrastructure were rated as the most important factors. In contrast, contextual and technological aspects, such as Multimodality, Environmental Quality, Shared Systems, and Digital Solutions, received moderate to lower weights, with differences linked to expert profiles. These results highlight how different disciplinary perspectives influence the understanding of bikeability-related factors. Conceptually, the findings support a broader view of cycling conditions that incorporates both established and emerging criteria. Methodologically, this study demonstrates the value of the Analytic Hierarchy Process (AHP) as a participatory and transparent tool to integrate diverse stakeholder opinions into a structured evaluation model. This approach can support cycling mobility planning and policymaking. Future applications may include case studies in specific cities, combining expert-based priorities with local spatial data, as well as longitudinal research to track changes in cycling conditions over time. Full article

The construction industry plays a major role in the consumption of natural resources and the generation of waste. Construction and demolition waste (CDW) is produced in substantial volumes globally and is widely available. Its accumulation poses serious challenges related to storage and disposal, highlighting the need for effective strategies to mitigate the associated environmental impacts of the sector. This investigation intends to evaluate the influence of mixed CDW on the physical, mechanical, and durability properties of mortars with CDW partially replacing Portland cement, and allow performance comparisons with mortars produced with fly ash, a commonly used supplementary binder in cement-based materials. Thus, three mortar formulations were developed (reference mortar, mortar with 25% CDW, and mortars with 25% fly ash) and several characterization tests were carried out on the CDW powder and the developed mortars. The work’s principal findings revealed that through mechanical grinding processes, it was possible to obtain a CDW powder suitable for cement replacement and with good indicators of pozzolanic activity. The physical properties of the mortars revealed a decrease of about 10% in water absorption by immersion, which resulted in improved performance regarding durability, especially with regard to the lower carbonation depth (−1.1 mm), and a decrease of 51% in the chloride diffusion coefficient, even compared to mortars incorporating fly ash. However, the mechanical performance of the mortars incorporating CDW was reduced (25% in terms of flexural strength and 58% in terms of compressive strength), but their practical applicability was never compromised and their mechanical performance proved to be superior to that of mortars incorporating fly ash. Full article

This study investigates the use of waste glass powder derived from fluorescent lamps as a partial replacement for cement in mortar production, aiming to valorize this Waste from Electrical and Electronic Equipment (WEEE) and enhance sustainability in the construction sector. Mortars were formulated by substituting 25% of cement by volume with glass powders from fluorescent lamp glass and green bottle glass. The experimental program evaluated mechanical strength, durability parameters and ecotoxicological performance. Results revealed that clean fluorescent lamp mortars showed the most promising mechanical behavior, exceeding the reference in long-term compressive (54.8 MPa) and flexural strength (10.0 MPa). All glass mortars exhibited significantly reduced chloride diffusion coefficients (85–89%) and increased electrical resistivity (almost 4 times higher), indicating improved durability. Leaching tests confirmed that the incorporation of fluorescent lamp waste did not lead to hazardous levels of heavy metals in the cured mortars, suggesting effective encapsulation. By addressing both technical (mechanical and durability) and ecotoxic performance, this research contributes in an original and relevant way to the development of more sustainable building materials. Full article

We present a simple method for customizing the optical characteristics of gold-core, silver-shell (Au@Ag) nanoparticles through controlled morphosynthesis via a seed-mediated chemical reduction approach. By systematically adjusting the concentration of cetyltrimethylammonium chloride (CTAC), we obtained precise control over both the thickness of the Ag shell and the particle shape, transitioning from spherical nanoparticles to distinctly defined nanocubes. Bright field and high-angle annular dark-field scanning transmission electron microscopy (BF-STEM and HAADF-STEM), and energy-dispersive X-ray spectroscopy (EDS) were employed to validate the structural and compositional changes. To link morphology with optical behavior, we utilized the Mie and Maxwell–Garnett theoretical models to simulate the dielectric response of the core–shell nanostructures, showing trends that align with experimental UV-visible absorption spectra. This research presents an easy and adjustable method for modifying the plasmonic properties of Ag@Au nanoparticles by varying their shape and shell, offering opportunities for advanced applications in sensing, photonics, and nanophotonics. Full article

Reducing carbon dioxide emissions is a key priority in the European Union, which aims to achieve carbon neutrality by 2050. Construction has a key role to play in this effort, as it is responsible for a significant proportion of greenhouse gas emissions, especially due to cement production. At the same time, waste reuse emerges as a key strategy within the circular economy, another pillar of European policies. By valuing byproducts and waste, such as construction and demolition waste (CDW), it is possible to reduce the extraction of natural resources, amount of waste sent to landfills, and emissions associated with the production of new materials. This study, with the main objective of evaluating the possibility of using CDW as supplementary cementitious materials, emerges as a possible solution to reduce these problems. Two CDW treatment methods were used: (i) mechanical grinding and (ii) calcination. The mechanical grinding method, even with the use of laboratory equipment, has shown that it is possible to obtain CDW particles with characteristics suitable for replacing cement. For the calcination process, temperatures between 600 °C and 800 °C were the most suitable. The results proved that the replacement of cement by CDW in pastes resulted in suitable behavior for the construction industry, having revealed an incorporation content of up to 25% CDW, a compressive strength and strength activity index higher than that found for pastes developed with fly ash. Regarding the calcination process, this revealed an improvement in the compressive strength of the developed pastes, resulting in an increase in strength activity index of between 7 and 10%. Full article

Sustainable development requires efficient planning and management of both natural and built resources. The identification of urban forms that best balance exposure to solar radiation and urban noise, ensuring compliance with residential construction regulations and European directives may be carried out through simulations. The proposed methodology involves simulating various scenarios and adjusting parameters of selected urban forms to evaluate the availability of solar radiation and the noise exposure on building façades within a specific context. In addressing the requirements for solar and noise optimization, predictive models (solar and noise) were employed, utilizing urban form indicators to relate these three variables. The case study demonstrates the inverse behavior of these variables in relation to the same urban forms. The findings highlight the optimal urban forms for each scenario. The enclosed form was identified as the most suitable for minimizing noise exposure, while the linear form is optimal for maximizing solar radiation exposure. This approach allows the designer to make informed decisions that balance these competing requirements, achieving a compromise between optimizing thermal and acoustic performance. The ultimate goal is to enhance the overall comfort of the building, reduce energy consumption, and promote a sustainable building solution. Full article

Background/Objectives: Attenuation correction (AC) is essential for achieving quantitatively accurate PET imaging. In ⁶⁸Ga-PSMA PET, however, artifacts such as respiratory motion, halo effects, and truncation errors in CT-based AC (CT-AC) images compromise image quality and impair model training for deep learning-based AC. This study proposes a novel artifact-refinement framework that filters out corrupted PET-CT images to create a clean dataset for training an image-domain AC model, eliminating the need for anatomical reference scans. Methods: A residual neural network (ResNet) was trained using paired PET non-AC and PET CT-AC images from a dataset of 828 whole-body ⁶⁸Ga-PSMA PET-CT scans. An initial model was trained using all data and employed to identify artifact-affected samples via voxel-level error metrics. These outliers were excluded, and the refined dataset was used to retrain the model with an L2 loss function. Performance was evaluated using metrics including mean error (ME), mean absolute error (MAE), relative error (RE%), RMSE, and SSIM on both internal and external test datasets. Results: The model trained with the artifact-free dataset demonstrated significantly improved performance: ME = −0.009 ± 0.43 SUV, MAE = 0.09 ± 0.41 SUV, and SSIM = 0.96 ± 0.03. Compared to the model trained on unfiltered data, the purified data model showed enhanced quantitative accuracy and robustness in external validation. Conclusions: The proposed data purification framework significantly enhances the performance of deep learning-based AC for ⁶⁸Ga-PSMA PET by mitigating artifact-induced errors. This approach facilitates reliable PET imaging in the absence of anatomical references, advancing clinical applicability and image fidelity. Full article

The use of recycled powder (RP) derived from construction and demolition waste (CDW) has several benefits, including the conservation of natural aggregate supplies, the preservation of land designated as landfills, and the promotion of a sustainable built environment. Partially substituting cement with RP generated from concrete-based waste can significantly reduce the carbon footprint of the construction industry. This comprehensive review delineates the advantages and disadvantages of mechanical, thermal, chemical, carbonation, mineral addition, and nano-activation methods for RP-based Portland cement (PC) mortars. A comprehensive examination of the parameters affecting the characteristics of RP-incorporated mortar has been presented. The mechanical properties of cement mortar formulated with RP have been examined in relation to different activation procedures. The review indicates that RP can be effectively utilized in the development of sustainable construction materials. This review article’s extensive literature survey also indicates a promising research trend and underscores the significance of thermal and combined activation methods and the utilization of concrete waste. Moreover, existing limitations in the current research and prospective future studies were identified and presented. Full article

The growing demand for sustainable energy solutions has intensified research on phase change materials (PCMs) due to their ability to efficiently store and release thermal energy. However, traditional PCMs are often made from petroleum-derived materials or rely on processes that pose environmental concerns. The aim of this work is therefore to explore the development and use of sustainable organic PCMs, in particular those based on bio-based or waste-derived materials. Bio-based PCMs, including fatty acids, natural waxes, and biopolymers, are in fact characterized by renewability and biodegradability. Waste-derived PCMs, such as those from the lost-wax casting industry and industrial by-products, offer an environmentally friendly approach to energy storage by reusing waste materials. This paper aims to analyze the thermal, mechanical, and in-service performance of these sustainable materials, highlighting their advantages and limitations compared to the most widely used commercial PCMs. Furthermore, recent progress in the integration of sustainable PCMs into building materials is illustrated to assess their practical implementation. Challenges and limitations, as well as possible solutions and future research directions, are also discussed. Full article

The high consumption of concrete makes it a priority target for environmental goals. When supplementary cementing materials were introduced, important progress was made toward achieving these goals, with fly ash (FA) making a major contribution in this regard. Given the current situation, it has become necessary to identify an alternative to this material as a result of the shutdown of coal-fired power plants across the European Union. In this sense, glass powder (GP) has shown promising results. This research focused on reducing the dosage of Portland cement (PC) as extensively as possible in concrete formulations, through high incorporations (until 70%) with different dosages of binder to evaluate various applications without compromising its strength and durability. The results obtained are encouraging. With only 150 kg/m³ of PC, 46.42 MPa was obtained, and with 250 kg/m³ of PC, 71.50 MPa was obtained, both at 90 days. Durability was not significantly compromised in the tests carried out and even obtained better results in some tests. The findings suggest that a substantial replacement of PC with GP could serve as a feasible option for lowering the PC content or even substituting FA, promoting a reduction in CO₂ emissions and energy consumption, and making concrete more sustainable. Full article