Search Results (21,163)

This study focuses on China’s domestically developed K452 alloy. Using Si₃N₄ ceramic balls as the counterface material, the tribological properties of the K452 alloy were investigated after heat treatment over a wide temperature range (RT–800 °C), and the wear mechanisms were analyzed. The results show that the heat treatment process enhances the material hardness slightly by promoting the dissolution of the γ′-strengthening phase and the precipitation of the η phase. From RT to 600 °C, the wear rate of the K452 alloy remains at a relatively low level, on the order of 10⁻⁶ mm³·m⁻¹·N⁻¹. Compared with the as-cast condition, intermediate treatment exhibits a significant reduction in the wear rate. Compared with traditional processes, it reduces one step of heat treatment. This improvement is attributed to the precipitation of the uniformly fine η phase, along with the re-dissolution of the γ′-strengthening phase. When the testing temperature is raised to 800 °C, the tribological performance of the K452 alloy deteriorates significantly, with the wear rate increasing to the order of 10⁻⁵ mm³·m⁻¹·N⁻¹. Microstructural characterization confirms that the in situ formations of dense Cr₂O₃ and Al₂O₃ oxide films during friction are the primary mechanism for improved wear resistance from RT to 600 °C. But when the temperature rises to 800 °C, the dynamic equilibrium of the oxide layers is disrupted, leading to oxidative wear becoming the dominant mechanism. Full article

Increasing amounts of textile waste require rapid implementation of novel recycling technologies. Biocatalytic degradation via enzymatic hydrolysis can be used to separate blends, which are otherwise inaccessible. However, the complex nature of the substrate and narrow operating window of the reaction necessitates process optimization but also complicates computational approaches. The reaction is performed in aqueous suspension at ambient pressure and temperatures well below boiling. Due to the gentle process conditions, preliminary assessment of ideal stirrer geometries can be performed in water under ambient conditions, using stirrers produced from commodity plastics using material extrusion-based 3D-printing at both bench (2 L) and semi-pilot (30 L) scale. Eight geometries were assessed using suspension activity (via cloud height), mixing energy consumption, and mixing time assessment via tracer addition at the bench scale. Four of these geometries were chosen for scale-up in a 30 L conical vessel. While large, especially close-clearance mixing equipment performed well at both sizes, an increase in performance of the pitched-blade turbine was observed at 30 L. This highlights the necessity of experimental scaleup procedure as well as optimized stirrer geometries for enzymatic hydrolysis. Full article

The application of rheological modeling in polyolefin-based systems has gained increasing attention in the context of sustainable materials and circular economy strategies. In particular, the use of recycled polyolefins reinforced with lignocellulosic fillers presents significant opportunities, but also introduces challenges associated with structural heterogeneity, degradation, and variability in processing behavior. Despite rheology’s central role in linking structure, processing, and properties, its use as a predictive tool in recycled systems remains insufficiently systematized. This work presents a systematic review conducted according to PRISMA guidelines to analyze the use of rheological models in polyolefin-based systems, with particular emphasis on their applicability to recycled materials and composite formulations. We analyze 50 studies using a structured data extraction protocol. The results show that rheological modeling approaches can be organized into a hierarchical framework ranging from indirect flow parameters and generalized Newtonian fluid models to viscoelastic, structural, multiscale, and hybrid approaches. However, these approaches are not evenly distributed across system types. Advanced models are predominantly applied to compositionally controlled systems, whereas recycled and post-consumer polyolefins are mainly addressed using simplified models or experimental characterization. The analysis further indicates that rheology is primarily used for data fitting and process simulation, with limited application as a predictive tool for material formulation. Quantitative trends reported in the literature indicate that filler incorporation typically increases viscosity by approximately 20–200%, depending on filler content, dispersion quality, and interfacial interactions. However, variability in experimental conditions and material heterogeneity significantly limits cross-study comparability. From a mechanistic perspective, the main limitation lies not in the availability of rheological models but in their adaptability to heterogeneous systems characterized by variable composition, degradation, and limited experimental accessibility. This review identifies a gap between the development of rheological models and their application in recycled polyolefin systems. Future progress on eco-composite design will require further development of integrative approaches that balance physical insight, predictive capability, and experimental feasibility. In this context, rheology should be repositioned from a post-characterization technique to a central tool for the design and optimization of sustainable polymer composites. From an applied perspective, these findings support the use of rheological parameters as practical indicators for guiding formulation strategies and optimizing processing conditions in recycled polyolefin-based materials. Full article

This paper examines the technological dimension of “handwritten time” a distinctive mode of existence of the Russian Avant-garde. By the mid-1930s, the avant-garde’s stylistic confrontation with Socialist Realism had effectively expelled it from the contemporary literary process, artificially arresting its development—an instance of “unfinished modernity.” The article offers a detailed analysis of the technology of self-archiving (“lit-recycling”) developed by Aleksei Kruchyonykh: a deliberately chosen strategy of uncensored writing oriented toward an implicit reader of the future. The conscious refusal to complete the conventional publishing cycle, together with the systematic archiving of materials, generated a new pragmatics of the Russian avant-garde, enabling continued work under conditions of total censorship. The study considers both the strengths of this pragmatics of self-isolation and its unavoidable costs, above all the rupture of author–reader communication. Drawing on workbooks and diary notebooks from the 1930s, it reconstructs an archiving technology that had fully matured by that decade: the balance between draft and fair copy, as well as the mechanisms of auto-communication and self-censorship. Each stage of textual work is shown to acquire a specific function within a single technological continuum. Special attention is paid to contemporary methods for reconstructing the avant-garde’s creative records. The article reconstructs successive versions of Kruchyonykh’s poems (“Irina in the Fog,” “Trash,” “All Dead Poets…,” “Mind You!,” “Grumbling,” etc.), and cites diaries and handwritten books. It also foregrounds Kruchyonykh’s “prophetic” texts—those marked by a premonition of the coming great war—which conclude his diary and creative notebooks of the 1930s. Full article

Healthcare waste management is a growing environmental and economic challenge due to increasing waste volumes, hazardous materials, and continued reliance on linear disposal methods such as incineration and landfilling. This review aims to examine how circular economy and zero-waste approaches can be applied to healthcare waste management to improve sustainability, resource efficiency, and system performance. A structured narrative review was conducted using peer-reviewed literature obtained from prominent scientific databases, concentrating on circular strategies, zero-waste initiatives, digital technologies, and policy frameworks relevant to healthcare waste systems. The reviewed studies indicate that practices such as improved waste segregation, recycling and material recovery, reusable product design, digital waste tracking, and Extended Producer Responsibility can significantly reduce waste generation, lower environmental impacts, and achieve cost savings, while maintaining infection control and patient safety. However, the review also identifies key barriers to implementation, including regulatory complexity, limited infrastructure, financial constraints, and weak coordination among stakeholders. The novelty of this review lies in its integrated analysis of circular economy and zero-waste strategies through the lens of digital enablement, offering a systems-based framework for transforming healthcare waste management beyond incremental improvements. The findings highlight that successful circular healthcare waste management requires strong institutional leadership, supportive policies, and the integration of digital technologies to enable monitoring, traceability, and decision-making. This review enhances the comprehension of how circular economy principles can facilitate the transition from linear to sustainable healthcare waste systems and provides guidance for policymakers, healthcare managers, and researchers. Future research should focus on evaluating real-world implementation, advancing recyclable and reusable medical materials, and developing standardised indicators to measure circular performance in healthcare settings. Full article

This study investigates the 55%Al-Zn-Si coating system. Using microstructural characterization and thermodynamic simulation, we systematically analyzed its microstructure formation, solidification behavior, and the regulatory effects of Cr, Nb, and V micro-alloying elements. The results show that the typical coating consists of a primary α-Al dendritic skeleton and an interdendritic Zn-rich eutectic phase, exhibiting a characteristic spangle morphology. The addition of Si is crucial. By participating in the formation of a Fe-Al-Si ternary compound layer, it effectively suppresses the intense reaction at the Fe/Al interface, providing essential conditions for the sufficient growth of the outer Al-rich dendrites and the formation of a continuous transition layer. Thermodynamic analysis further clarifies that the coating solidification follows three distinct stages: precipitation of the primary α-Al phase, an Al-Si binary eutectic reaction, and a final Al-Zn-Si ternary eutectic transformation. Regarding micro-alloying, this study reveals the specific roles of different elements: Cr significantly refines the transition layer structure, promoting its transformation from coarse lamellae into a fine and uniform morphology; V tends to combine with Al to form high-melting-point enriched regions, inhibiting the growth of Fe-Al intermetallics and reducing the thickness of the brittle transition layer by approximately 50%; conversely, the addition of Nb disrupts the normal solidification sequence, inducing abnormal segregation of Al-rich and Si-rich phases, which compromises the homogeneity and integrity of the coating structure. Through an in-depth analysis of the fundamental solidification mechanism and micro-alloying effects, this research provides an important theoretical basis for optimizing the microstructure of hot-dip Al-Zn sheets via precise composition design and micro-alloying strategies. Full article

Interest in improved disposal pathways and proliferation-resistant systems for used nuclear fuel recycling has driven research on monoamide extractants. Existing comparisons against the industry standard, tributyl phosphate (TBP), emphasize a fundamental approach and span a wide range of test conditions. This work narrows that range and addresses process-scale considerations by presenting hydrodynamic performance results alongside extraction capacity at optimized conditions. The monoamide solvents, 1.0 M DEHiBA (N,N-di(2-ethylhexyl)isobutanamide), 1.5 M DEHBA (N,N-di(2-ethylhexyl)butanamide), and 1.5 M DEHDMPA (N,N-di(2-ethylhexyl)-2,2-dimethylpropanamide), are compared to 1.1 M TBP in bench-scale extraction tests with nitric acid (2–6 M) and uranium (∼0.8 M). Performance is assessed with distribution ratios and dispersion number ratings and supported by specific gravity and viscosity measurements. DEHBA and DEHDMPA exhibited inadequate coalescence behavior with failed or poor dispersion ratings despite uranium distribution ratios of 2.06 ± 0.03 and 0.86 ± 0.01 at O/A = 1.9, limiting suitability for process application. TBP and DEHiBA maintained adequate dispersion ratings across all conditions tested, with maximum distribution ratios of 4.37 ± 0.08 at O/A = 2.6 and 0.67 ± 0.01 at O/A = 2.9, respectively. Higher viscosity values for DEHBA (5.21 cP ± 0.3%) and DEHDMPA (6.53 cP ± 0.4%) relative to TBP (2.04 cP ± 0.4%) and DEHiBA (3.18 cP ± 0.4%) correlate with observed coalescence deficiencies. The methods presented in this work demonstrate the significance of evaluation beyond extraction capacity. Full article

Waste tire disposal and high-ground-stress soft rock roadway instability are pressing global challenges. This study develops sustainable rubber granule concrete (RGC) using waste tire rubber as a key component, aiming to realize waste valorization and floor heave control. RGC’s mechanical properties (uniaxial/triaxial compression, compressibility, ductility) were systematically tested, and its pressure relief mechanism was validated via finite element analysis (ABAQUS/FLAC) and 60-day field monitoring. Results show that RGC with optimal parameters (12% rubber content, 3–4 GPa elastic modulus, 250–350 mm thickness) achieves 64% bottom stress reduction and >40% displacement control. The material’s excellent energy absorption and flexibility address the brittleness of conventional concrete, ensuring stable support in high-stress environments. This work provides a sustainable, cost-effective concrete modification strategy, bridging waste recycling and geotechnical engineering, with broad implications for low-intensity, high-toughness material applications. Full article

The global transition toward renewable energy and decarbonization is intrinsically linked to the management of critical materials. Rare Earth Elements (REEs) are no exception, as they play a strategic role at the center of climate goals. Therefore, this review provides a comprehensive assessment of the REE landscape, explicitly addressing the proposed Demand-Sustainability-Risk Nexus (DSR-Nexus), which integrates technological demand, environmental sustainability, and geopolitical supply risks. A systematic review based on PRISMA methodology was conducted to analyze scientific contributions published between 2015 and 2026, revealing a significant research imbalance. By 2025, while 87% of works focus on resource availability, production, and recycling, only 1.4% address the global supply chain and its geopolitical implications. Key findings highlight that China’s dominance in mining, processing, and refining capacities, accounting for 69.5%, 92%, and 94%, respectively, creates structural vulnerabilities for future environmental goals. In contrast, emerging producers such as Malaysia and the United States are expected to contribute 9% and 8% of refining capacity, respectively. Furthermore, this review discusses environmental trade-offs, including high energy intensity, water consumption, and radioactive byproducts. It also examines mitigation strategies, such as recycling, urban mining, and material substitution. Ultimately, achieving a resilient energy transition requires expanding supply, strengthening circular strategies, and international cooperation. Full article

This study investigates the feasibility of incorporating high-volume municipal solid waste incineration (MSWI) fly ash into geopolymers, with a focus on its effects on mechanical performance and fragmentation behavior. A systematic experimental program was conducted in three stages. Geopolymer mixtures were first prepared with MSWI fly ash substitution rates ranging from 50% to 100% at seven distinct levels. Uniaxial compression tests were then performed to evaluate mechanical properties, followed by sieve analysis to examine fragment size distribution. The fractal dimension (D) was adopted to quantitatively characterize the degree of fragmentation. The results indicate that dry density, compressive strength, and elastic modulus all decrease progressively with increasing MSWI fly ash content. Specifically, as the fly ash content increased from 50% to 100% the compressive strength decreased from 9.57 MPa to 3.18 MPa. Notably, even at a 100% substitution rate, the compressive strength reached 3.18 MPa, which is 59% higher than the 2.0 MPa minimum requirement specified in the JTG/T F20-2015 standard. These findings demonstrate that MSWI fly ash can be effectively utilized at high replacement levels to produce sustainable geopolymers with satisfactory mechanical properties. This approach presents a viable strategy for recycling industrial solid waste into value-added construction materials. Full article

Electric two-wheelers (E2Ws) are promoted as lower-emission options in emerging economies. Their long-term cost competitiveness depends mainly on battery durability and how batteries are managed at the end of their life. This research examines Li-ion and nickel-cobalt-manganese (NCM)-type batteries versus the previously common lead-acid batteries in these markets. The study uses a 12-year total cost of ownership (TCO) framework that includes battery degradation, estimated first-life duration, and alternative lifecycle pathways. It covers three sensitivity analysis cases: conservative, base case, and optimistic. Three scenarios are evaluated: (1) no lifecycle management, (2) refurbishment for first-life extension, and (3) integrated lifecycle management with refurbishment, second-life utilisation, and recycling. Results show that managing the battery lifecycle can reduce TCO. The amount of reduction depends on first-life duration, ownership horizon, refurbishment cost, downstream residual value, and use intensity. The greatest TCO gains are found in battery categories with short first-life duration, allowing substantial residual value recovery during ownership. Batteries with first-life durations of 12 years or more provide smaller benefits. These findings support optimising lifecycle pathways for maximum residual value. Improved TCO performance, along with supportive infrastructure, policies, and market development, is critical for broader E2W adoption. Full article

Variability in life cycle assessment (LCA) results for metal recycling technologies arises from multiple sources, including allocation methods, recycling route, regionality of impacts, and type of waste treated. Among these factors, waste composition is particularly critical, as it directly influences process performance by affecting auxiliary material consumption and emissions. This work investigates four waste categories: metals from incineration bottom ash (MBA), waste-printed circuit boards (WPCBs), industrial waste from gold refining (GRA), and spent automotive and industrial catalysts (SCs). The Climate Change (CC) for 1000 kg of waste was estimated at 3251 × 10³ kg CO₂eq for WPCBs, 3923 × 10³ kg CO₂eq for MBA, 1569 × 10³ kg CO₂eq for GRA, and 2101 × 10³ kg CO₂eq for SCs. A sensitivity analysis was performed to assess the influence of allocation methods on results for 1kg of recycled metal. The highest variability in CC across waste categories was observed for gold (up to 8477%) with the black-box economic allocation method, while different allocation methods reached 21,700% for WPCBs. These results highlight the strong influence of methodological choices and waste characteristics, emphasizing the need for transparent and consistent LCA reporting. Full article

Life cycle assessment (LCA) is an important analytical method used to evaluate the environmental impacts of products, services, or processes throughout their entire life cycles—from the extraction of raw materials and production to use and end-of-life treatment. LCA enables the identification of stages with the highest environmental impact burden (hotspots) and supports strategic environmental initiatives, the circular economy, standards, and policies aimed at improving sustainability. This paper analyses the application of LCA in metallurgy, with a focus on primary aluminium production. It outlines the principles of life cycle thinking and explores decarbonisation opportunities within the aluminium industry. This study includes a life cycle impact assessment case study comparing the most significant environmental impacts of primary aluminium production in different regions of the world, including Europe and Asia. The analysis was performed using openLCA software 2.5 with the OzLCI2019 database. Environmental impacts were calculated using the ReCiPe 2016 Midpoint (H) method. The results indicate that primary aluminium production mainly affects impact categories related to high energy consumption, the use of carbon anodes, and associated emissions. The highest impacts were identified in ecotoxicity, followed by global warming, land use, ozone formation, and fossil resource scarcity. No significant regional differences were observed. Full article

This study investigates the leaching behavior of the LiNi_0.65Co_0.25Mn_0.10O₂ cathode material in a phosphoric acid medium, with metallic copper recycled from spent battery components serving as a reducing agent. The aim was to develop an efficient approach for the recovery of Li, Ni, Co, and Mn while providing a mechanistic understanding. Leaching experiments were performed by varying key parameters, including copper addition, acid concentration (0.2–0.8 mol·L⁻¹), cathode mass (0.2–1.0 g), stirring rate (0–600 rpm), and temperature (35–80 °C). Thermodynamic analysis, supported by Pourbaix and species distribution diagrams, was used to interpret metal behavior. The results show that lithium is readily dissolved, whereas the extraction of Ni, Co, and Mn depends on the presence of copper, which enables their reduction and dissolution. Optimal conditions (0.4 mol·L^‒1 H₃PO₄, 0.2 g Cu, 600 rpm, 80 °C) enabled rapid extraction, exceeding 90% within 30 min, while near-complete extraction (~100%, 99%, 99%, and 97% for Li, Ni, Co, and Mn) was achieved after 60 min. Structural analysis revealed a transformation from the layered structure to spinel-like intermediates, followed by their dissolution and formation of copper phosphate phases. The proposed system represents an efficient approach for the sustainable recycling of NMC cathodes. Full article

The synthesis of heterocyclic compounds such as pyridines, quinazolinones and coumarins is a fundamental area of organic chemistry due to their wide application in the pharmaceutical and chemical industries, agro-industry, and other fields of modern technology. As these compounds are produced in large quantities and have significant industrial importance, the development of sustainable and environmentally friendly synthetic approaches has become a key objective of green chemistry. In this context, this review examines the principles, methods and applications of the sustainable synthesis of pyridines, quinazolinones and coumarins in deep eutectic solvents (DESs), a new class of solvents characterized by low volatility, non-toxicity, ease of preparation and recyclability, often from renewable sources. Special emphasis is placed on synthetic strategies that achieve reaction efficiency while reducing environmental impact, including processes without additional catalysts or with reusable catalysts. The paper provides a comprehensive overview of recent advances and highlights the potential of DESs as a viable alternative to conventional organic solvents in the synthesis of bioactive pyridine, quinazolinone and coumarin compounds. Full article