Search Results (5,064)

The mechanical properties and real-time damage evolution of sustainable concrete (SC) containing 100% recycled concrete aggregate (RCA) under the combined action of hybrid steel and polyolefin fibers were studied. Inspired by solving the massive effects on the environment from construction waste, as well as to improve the lower mechanical performance of lower-grade RCA, the effect of combining high-stiffness hooked-end steel fibers and flexible macro-polyolefin fibers within RCA was investigated. Six different mix designs were considered: plain, single-fiber (100% steel and 100% polyolefin) and three hybrid composites with varying fractions of the steel/polyolefin fibers (25/75, 50/50, and 75/25). Compressive, tensile and flexural strengths were determined by mechanical testing. During compressive testing, the damage evolution was monitored using low-cost acoustic emission (AE) as a non-destructive technique. Cumulative hits analysis, amplitude distributions, and the statistical b-value parameter were used for damage characterization. The results show that steel fiber significantly increased compressive strength (an increase of up to 13.8%), and the 50/50 hybrid mix showed a high synergistic effect, yielding the highest tensile (4.86 MPa) and flexural (25.54 MPa) strengths. AE analysis identified different damage fingerprints: Based on amplitude analysis, steel-fiber composites exhibited high-amplitude events (which may be attributable to fiber pull-out); polyolefin-fiber composites generated medium-amplitude events (may have resulted from distributed microcracking); and hybrid mixes displayed a mixed amplitude distribution. The b-value analysis provided insight into progressive damage and revealed that the hybrid fibers induce stable, diffuse damage that prevents the brittle failure of plain recycled aggregate concrete (RAC). The results show that hybrid fiber reinforcement can be a reliable approach to enhance the mechanical performance and crack resistance of RAC. Furthermore, low-cost acoustic emission (AE) serves as an effective non-destructive method for monitoring damage progression within the material. Full article

Phosphorus (P) accumulation in intensively agricultural soils represents a growing environmental concern due to its potential mobilization and contribution to eutrophication. This study investigated the mechanisms controlling P availability and redistribution in agricultural soils from the Elota–Piaxtla Irrigation District (northwestern Mexico) during cropping and non-cropping periods. Soil P fractions were determined using the Hedley sequential extraction method and related to soil physicochemical properties through a correlation analysis. During the cropping period, P in Fe/Al hydroxides dominated (45–67% of total P), indicating strong adsorption and fixation in fine-textured soils. In contrast, the non-cropping period showed a significant increase in organic P in humic substances (up to 55%), suggesting enhanced biological transformation and residue recycling. Labile P fractions decreased from 60% to 44% of total P between sampling periods, while moderately labile fractions increased, indicating seasonal redistribution of P pools. Statistical analysis revealed that P dynamics were primarily governed by mineralogical characteristics and organic matter transformations rather than by individual soil properties. The accumulation of moderately labile and organic P fractions during fallow periods highlights a latent environmental risk, particularly in irrigated systems prone to runoff and erosion. These findings emphasize the need for fraction-based nutrient management strategies that integrate both agronomic efficiency and environmental protection in intensive agricultural soil. Full article

This study investigates the valorization of construction and demolition (C&D) waste streams and an industrial by-product for sustainable concrete production. Recycled concrete aggregates (RCA) and recycled brick aggregates (RBA), derived from C&D wastes, together with pelletized recycled fly ash aggregates (FAA) produced from thermal power plant fly ash, were used as total replacements for natural coarse aggregates. Six concrete mixtures were prepared at a constant water-to-cement ratio of 0.50 using untreated and slag slurry–treated aggregates. A slag slurry-based two-stage mixing approach (TSMA), incorporating ground granulated blast furnace slag (GGBFS), was applied as a practical and potentially scalable treatment method to enhance aggregate quality and interfacial bonding. The results show that complete replacement of natural aggregates reduced fresh concrete unit weight by up to 17%, while meeting the minimum compressive strength requirements for structural applications. Slag slurry treatment led to statistically significant improvements in mechanical properties, reduced variability, and enhanced overall reliability. In addition, widely used code-based prediction models (TS500, ACI, Eurocode-2, NZS 3101-1:2006, and CSA A23.3-04), originally developed for conventional concrete, were evaluated for their applicability in estimating key mechanical properties of recycled and by-product aggregate concretes, and alternative regression-based models were developed to improve prediction accuracy. Overall, the findings demonstrate the potential for effective utilization of C&D wastes and industrial by-products in structural concrete, contributing to resource efficiency and reduced reliance on natural aggregates. Full article

Large-scale drinking water treatment plants contribute to environmental burdens through energy consumption, chemical use, and sludge generation. However, Life Cycle Assessment applications to full-scale drinking water treatment plants remain limited in Morocco and other Global South contexts, where site-specific operational data are often scarce. This study assesses the environmental performance of an existing conventional drinking water treatment plant in Al-Hoceima, northern Morocco, using full-scale operational data and a Life Cycle Assessment (LCA) approach based on the ISO 14040/14044 framework. The assessment was performed using OpenLCA v1.11 and the ReCiPe 2016 Midpoint (H) method, with a functional unit of 1 m³ of treated drinking water. The results show that the operational phase dominates the environmental impacts, mainly due to sludge generation and electricity consumption. Two improvement scenarios were therefore evaluated: sludge recycling and the integration of a hydroelectric turbine as an on-site renewable energy option. Both scenarios showed potential to reduce environmental impacts while improving resource efficiency and long-term economic performance. By integrating environmental and techno-economic analyses, this study provides a practical decision-support framework for the sustainable transformation of conventional drinking water treatment plants in Morocco and comparable developing regions. Full article

Harmonized laboratory methodologies, notably the CEPI recyclability laboratory test method (latest version 3, released February 2025) and the 4evergreen protocol (latest revision 1, released January 2025), are widely used to assess the recyclability of paper-based materials. However, the extent to which laboratory-scale results reflect pilot-scale behavior remains insufficiently documented. In this work, the recyclability of brown packaging paper was evaluated at both laboratory and pilot scales. Disintegration was performed under identical consistency, temperature, and duration, followed by screening, filtrate analysis, macro-stickies quantification, and paper sheet adhesion evaluation according to the CEPI methodology. In parallel, recycled paper prototypes were produced in a pilot paper machine and were mechanically characterized. The material was classified as technically recyclable in a conventional recycling mill at both scales, with closely aligned recyclability scores. Nevertheless, pilot-scale testing revealed higher dissolved and colloidal substances, increased macro-stickies content, and sheet adhesion phenomena not fully apparent at laboratory scale. These results demonstrate that while laboratory tests are robust for recyclability classification, pilot-scale trials provide essential insights into runnability and operational risks relevant for industrial implementation. Full article

A solar-assisted thermochemical cycle to store concentrated solar energy in solid elemental sulfur via the reversible interconversion of sulfuric acid and sulfur is being developed within the SULPHURREAL project. This process enables long-term, transportable energy storage through internal recycling of sulfur oxides. A central objective is to integrate SO₂ capture and conversion in separation-friendly steps that support closed-loop operation with minimal additives and limited downstream purification, while remaining compatible with industrial sulfuric acid and sulfur feedstocks. The method presented in this paper can also be feasible for SO₂ removal from fossil fuels and industrial emissions. With this purpose, indirect SO₂ conversion via bisulfite disproportionation was investigated using elemental sulfur as a heterogeneous auto-catalyst. Batch tests were performed in a pressurized, Teflon-lined autoclave with concentrated bisulfite solutions (3 M) at 140–180 °C for 3 h. Sodium bisulfite showed no conversions at 140–160 °C, whereas sulfur auto-catalysis was observed at T ≥ 170 °C. Ammonium bisulfite was also evaluated as a separable SO₂-capture intermediate; due to thermal instability, operation was limited to 170 °C, where sulfur formation remained detectable. For loop closure, NH₃ and H₂SO₄ must be recovered from the produced sulfate. This was addressed by reacting (NH₄)₂SO₄ with metal oxides in a tubular furnace at 500 °C. The evolved NH₃ was trapped in acid and quantified by ion chromatography. Near-quantitative NH₃ recovery (≈92–98%) was achieved with MgO and ZnO, and the corresponding metal sulfates were identified by XRD. These results support integrated process development and motivate kinetic and mass-balance studies toward continuous operation and scale-up. Full article

Mass-based circularity indicators, such as ISO 59020:2024, quantify material recovery as a share of total throughput but do not account for chemical composition or functional performance, as a consequence of their sector-agnostic design. In copper metallurgical systems, trace tramp elements (e.g., As, Sb, Bi, Fe, Sn, Ni) present in WEEE-derived scrap, anode slimes, and refinery residues can significantly reduce electrical conductivity. Even at nominal purities of ≥99.7 wt.% Cu, conductivity may drop to 85.0–88.0% IACS, as illustrated by selected reported cases—a level of functional degradation that remains undetected by mass-based accounting. Analysis of Grade A cathode standards (EN 1978:2022, LME Cu-CATH-1, ASTM B115-10:2021) shows that impurity limits as low as 2 ppm (Bi) constrain the achievable share of secondary feed in closed-loop recycling. For a specific flash-smelting–refinery configuration, modeling indicates that secondary feed shares above approximately 30% may lead to impurity accumulation beyond the stated specification constraints unless low-impurity primary copper is introduced. This study introduces the Quality-Adjusted Circularity Indicator (QACI), a conceptual, specification-constrained indicator framework that applies a dilution factor f_dil derived from a binary blending mass balance to adjust ISO 59020:2024 inflow-based circularity indicators using a feed-composition blending constraint anchored to Grade A specification limits. The QACI functions as a feed-composition screening indicator operating at the anode blending stage and does not represent a correction of the full electrorefining system. Parametric scenario analysis across six stylized impurity configurations shows that, at identical mass-based circularity (C_mass = 25%), the QACI ranges from 7.1% to 25.0%. This corresponds to a 1.3- to 3.5-fold difference between the mass-based and quality-adjusted indicator values under the stated feed-composition assumptions, illustrating the potential overestimation introduced when feed-quality constraints are not considered. This ratio quantifies the divergence between two indicator values under stylized conditions and should not be interpreted as a directly measured fold-difference in actual loop-closure performance. Positioned within the ISO 59020:2024 Annex C complementary method space, the QACI is positioned as a first-order screening approach of existing circularity metrics that may inform future research discussion of quality-differentiated approaches in EU secondary metals policy. Full article

Background: Platinum-based chemotherapy is the frontline treatment for high-grade serous ovarian cancer (HGSOC); however, the development of therapy resistance greatly limits clinical response. Increasing evidence suggests that platinum agent-driven metabolic programming, particularly within redox-associated pathways, may contribute to chemoresistance. Methods: A syngeneic pair of patient-derived HGSOC cell lines representing cisplatin-sensitive (SE) and cisplatin-resistant (CR) states were evaluated using a multi-omics approach. Differential metabolite abundance and gene expression were assessed, followed by gene set and pathway enrichment analyses to identify coordinated metabolic shifts. In silico analysis of an additional sensitive and resistant HGSOC cell line validated the glutathione pathway upregulation seen in the patient-derived model. The functional contribution of the glutathione pathway on cisplatin resistance was evaluated following glutathione inhibition. Results: Chronic cisplatin exposure induced extensive metabolic rewiring in CR cells, characterized by enrichment of glutathione metabolism at both the metabolite and gene levels. Increased reduced glutathione was observed alongside upregulation of key enzymes involved in its de novo biosynthesis, recycling, and utilization, consistent with enhanced detoxification capacity relating to cisplatin-induced oxidative stress. Additionally, taurine was highly enriched, further highlighting a metabolic shift towards enhanced antioxidant mechanisms. CR cells also demonstrated an increase in NADPH-generating pathways, including amino acid metabolism and fatty acid β oxidation, to support redox balance and biosynthetic demands of increased glutathione metabolism. Transcriptional remodeling of the γ-glutamyl cycle further indicated a shift toward increased glutathione turnover, suggesting that the coordinated changes seen may define a metabolic state enhanced in oxidative stress tolerance and therapeutic resistance. These transcriptional changes were also seen in another model of platinum sensitivity/resistance, indicating a conserved response associated with platinum-induced resistance. Finally, concurrent cisplatin treatment and glutathione inhibition significantly increased sensitivity within the CR cells. Conclusions: These findings suggest that cisplatin-resistant cells, previously exposed to a platinum-based agent, may undergo distinct metabolic rewiring towards antioxidant pathways to survive chronic chemotherapeutic stress. Targeting components of these systems may represent a viable strategy to overcome platinum resistance and improve therapeutic outcomes. Full article

The rapid emergence of SARS-CoV-2 variants underscores the need for accurate, rapid, and affordable diagnostic tools, particularly in resource-limited settings. An isothermal amplification-based assay was developed integrating reverse-transcriptase recombinase polymerase amplification (RT-RPA), T7 transcription, and duplex-specific nuclease (DSN)-mediated detection for variant discrimination. The assay targets three genomic regions: a conserved region within ORF1a and two variant regions, ORF1a (Δ3675–3677) and the S gene (Δ69–70), enabling differentiation between the Wuhan-Hu-1 reference isolate and the B.1.1.7 variant. The method demonstrated high specificity and a limit of detection of 200 copies per sample using low-cost instrumentation. DSN-mediated cleavage improved discrimination between matched and mismatched RNA targets while enabling signal amplification through target recycling. The assay requires minimal laboratory infrastructure, relying on a heat block and fluorescent plate reader. These results demonstrate a scalable and cost-effective strategy for SARS-CoV-2 variant screening with potential as a future strategy for pathogen screening and variant surveillance. Full article

Background: Digital exclusion remains a key barrier to equitable access to digital health services, particularly among individuals with visual impairment. Limited access to devices and digital literacy restricts participation in increasingly digital-first healthcare systems. This study aimed to evaluate the feasibility and exploratory service impact of a device recycling and digital inclusion pilot at a tertiary ophthalmic hospital. Materials and Methods: The six-month pilot at Moorfields Eye Hospital involved the refurbishment and distribution of donated electronic devices (laptops and mobile phones) alongside personalised digital literacy training delivered by trained volunteers. Twenty-two patients with visual impairment were enrolled; 18 completed the programme. Pre- and post-intervention questionnaires assessed digital engagement and confidence across key domains. Paired data were analysed using the Wilcoxon signed-rank test. Results: Across 216 item-level engagement responses, the number of responses indicating daily engagement increased from 31 to 49. Mean self-reported confidence scores improved from 3.1 to 5.1 out of 10 (Wilcoxon signed-rank test, V = 148, p = 0.0008; r = 0.81). Patients reported increased use of email, messaging, online forms, and General Practice (GP) appointment systems. Using secondary lifecycle data and modelled estimates, the reuse of refurbished laptops was associated with an indicative saving of approximately 5.3 tonnes of CO₂-equivalent emissions. Conclusions: This service evaluation suggests that a multi-component intervention combining device provision with tailored support may improve digital engagement and confidence among patients with visual impairment. These findings support the feasibility of integrating digital inclusion initiatives within ophthalmology services, with potential co-benefits for environmental sustainability. Full article

The wet recovery of spent lithium iron phosphate (LFP) batteries is severely hindered by the low efficiency of copper removal. Here, a new process has been developed using a copper-removing chelating resin with pyridine nitrogen, carboxyl, and hydroxyl groups for the selective separation of copper ions. This copper chelating resin achieved a copper removal efficiency of 96.99% and reduced the residual copper content to below 10 milligrams per liter, significantly outperforming the traditional iron powder method. The adsorption process is highly sensitive to pH, with the highest efficiency at pH 1.75. A concentration of 2.0 moles per liter of H₂SO₄ can achieve a desorption rate of approximately 95%. The adsorption process follows the Langmuir isothermal equation and the pseudo-second-order kinetic model, corresponding to single-layer chelated chemical adsorption. Mechanism studies have confirmed that the synergistic coordination effect of the multifunctional groups helps in the efficient capture of copper ions. This copper chelating resin exhibits excellent stability, reversibility, and reusability, providing a promising method for efficient copper removal and recovery in the wet metallurgical recycling of LFP. Full article

Driven by the global demand for sustainable construction resources, Recycled High Ductility Cementitious Composites (R-HDCC) exhibit high ductility and cracking resistance, demonstrating significant potential for enhancing structural durability. However, fire resistance remains a critical constraint on its engineering application. To investigate the performance evolution mechanism of R-HDCC after high-temperature exposure, this study examined the effects of different temperatures (200 °C, 400 °C, 600 °C, and 800 °C) and cooling regimes (self-cooling and water-cooling) on R-HDCC. The results indicate that when the temperature exceeded 200 °C, the compressive strength of R-HDCC decreased significantly. At 800 °C, the residual compressive and flexural strengths dropped to below 20% of their initial values. However, water-cooling treatment mitigated the adverse effects on compressive and flexural strength to some extent. In terms of tensile performance, R-HDCC completely lost its functionality at temperatures of 600 °C and above, and the cooling method had minimal influence on tensile behavior. Compared with natural cooling, water-cooling specimens developed fewer microcracks and less interfacial damage, indicating that water-cooling alleviates high-temperature-induced deterioration of the material’s microstructure to a certain degree. These findings provide important insights for the scientific evaluation of the fire resistance of R-HDCC and offer valuable guidance for its practical application. Full article

Existing research on the axial compressive performance and size effect of carbon fiber-reinforced polymer (CFRP)-confined recycled aggregate concrete (RAC) short columns mainly relies on macroscopic experimental analysis, lacking research methods capable of reflecting the heterogeneous characteristics of materials and mesoscopic damage evolution mechanisms. Accordingly, a three-dimensional mesoscale finite element method was adopted in this study to establish a five-phase RAC mesoscopic model, including natural aggregates, old mortar, old interfacial transition zones (ITZs), new mortar, and new interfacial transition zones. Different from existing studies, predominantly based on macroscopic experiments or empirical models, this paper focuses on revealing the coupled effects of the recycled aggregate replacement ratio, the number of CFRP confinement layers, and specimen size. A total of 48 specimens were designed, covering four specimen sizes, four recycled coarse aggregate replacement ratios, and three CFRP confinement layers. The effects of these parameters on failure modes, stress–strain relationships, and size effect were systematically analyzed. The results indicate that the peak stress decreases significantly with the increase in the recycled coarse aggregate replacement ratio; the increase in CFRP layers markedly improves both the bearing capacity and post-peak bearing capacity retention rate; the ultimate stress generally declines as the specimen size increases, which highlights the pronounced size effect of CFRP-confined RAC short columns. Based on peak parameters and normalization analysis, a simplified stress–strain model was established: the goodness of fit R² of the ascending branch is 0.98565, and the goodness of fit for the descending branch parameters are ${\mathrm{R}}_{\mathsf{\beta }}^2$= 0.9655 and ${\mathrm{R}}_{\mathsf{\gamma }}^2$= 0.9350. Compared with existing models, the proposed model achieves a low prediction error of only 1.5–6.9%, demonstrating superior prediction accuracy. It can accurately describe the complete compressive process of CFRP-confined RAC short columns and provide a mesoscopic mechanistic basis for engineering design. Full article

Platinum group metals (PGMs: Pt, Pd, Rh, Ru, Os, Ir) are critical strategic metals. Spent automotive catalysts (SACs) represent one of the most significant secondary sources of PGMs, and their recovery is essential for alleviating the supply–demand imbalance. In the recycling chain, pyrometallurgical processing of SACs generates Fe-Si-based alloy concentrates (termed Fe−Si−PGMs), serving as an important yet challenging intermediate resource for PGM recovery. This review first summarizes the pyrometallurgical and hydrometallurgical processes used for recovering PGMs from SACs, before shifting its focus to the treatment technologies for PGMs in Fe–Si–PGMs alloy. These techniques, including direct extraction, extraction following desilication (via alkaline roasting, slagging, or hydrometallurgical routes), and in situ mechanochemical extraction, are critically evaluated in terms of their advantages and limitations. Furthermore, given that the accurate quantification of trace-level yet high-value PGMs represents another key challenge in the recovery chain due to complex sample matrices, this work systematically outlines and compares the analytical methods commonly employed, such as fire assay, spectroscopic and mass spectrometric techniques, electrochemical methods, and alkali fusion. Finally, several recommendations are provided regarding PGM recovery from SACs, with emphasis on Fe−Si−PGMs alloy processing and analytical methods for PGMs. Full article

The transition towards a circular economy in architecture requires new methods for reusing construction and demolition waste as a material resource. Recycled aggregates are a promising alternative to natural aggregates, although their variable porosity and particle grading often limit practical application. This study evaluates the suitability of recycled concrete aggregate (RCA) and recycled ceramic aggregate for small-scale architectural elements such as street furniture. Three comparative mixtures were analysed using particle size distribution data, the Modified Andreasen model, and the EMMA (Elkem Materials Mix Analyzer) tool. Two mixtures contained recycled aggregates, while one reference mixture was based on natural aggregates. The assessment focused on particle packing, water demand, and binder content. The recycled concrete aggregate mixture showed results closest to the reference mix, with water content of 180 kg/m³ and a water-to-cement ratio of 0.50, compared with 170 kg/m³ and 0.50 for the natural aggregate mixture. The ceramic aggregate mixture required the highest water content (200 kg/m³) and cement dosage (380 kg/m³) due to its higher porosity (15–18%) and finer particle fraction. By adjusting aggregate proportions within the packing model, satisfactory particle structuring was still achieved in all mixtures (q = 0.31–0.35). The study shows that particle packing methods, commonly used in concrete technology, can also support early-stage architectural material selection. Recycled aggregates, particularly RCA, may therefore be considered a viable substitute for natural materials in benches, seating panels, and other small-scale circular design applications. Full article