Search Results (2,768)

A new series of polyamides (PAs) employing two phenolic natural compounds as starting materials, eugenol and chavicol, has been successfully prepared. The synthesis was carried out through a solvent-free protocol using the environmentally friendly organocatalyst 1,5,7-triazabicyclo[4.4.0]dec-3-ene (TBD). The obtained materials have been properly characterized. Moreover, the prepared materials, all of them amorphous, showed a wide range of transition temperatures (T_gs) depending on the structure of the diester counterpart used in the polymerization reaction. In addition, the influence of the methoxy group present in eugenol on the thermal properties of the resulting polyamides was studied. The synthesized polyamides demonstrated excellent thermal stability, high hydrophobicity, and great dimensional integrity. Furthermore, the obtained polymers could be depolymerized under alkaline hydrolysis conditions to yield, with good to excellent recovery ratios, the corresponding starting diamine monomer, which could eventually be used in the synthesis of new polymers. Closed-loop chemical recycling emerges as a sustainable alternative to conventional end-of-life management strategies for discarded polymers, while also constituting a promising pathway to mitigate the accumulation of polyamide (PA) waste. Full article

Synthetic microfibres released during textile drying are considered an emerging source of microplastic pollution, yet this waste stream is generally discarded without treatment. This study investigates a valorisation route by incorporating waste dryer-filter microfibres into a potassium-based/metakaolin geopolymeric coating for architectural applications, with the dual objective of preventing environmental release and enhancing material performance. Geopolymer pastes containing 0.1–0.3 wt.% of synthetic microfibres were characterised in terms of physical, mechanical and microstructural behaviour. Microfibre addition produced a marked toughening effect, with flexural strength increasing from about 3 MPa for the unreinforced matrix to 7.5 MPa for the composite containing 0.3 wt.% fibres, while compressive strength decreased moderately due to the presence of a compliant fibrous phase. Microstructural observations confirmed fibre dispersion and fibre–matrix bonding, supporting crack-bridging mechanisms. Density, porosity and water absorption measurements indicated a stable geopolymer gel structure with a connected pore network. Thin-layer applications onto clay brick exhibited satisfactory workability and adhesion, confirmed by pull-off testing (~0.12 MPa) and interfacial microscopy. The results demonstrate that textile-derived microfibres can be effectively immobilised within a potassium geopolymer matrix while improving flexural performance, offering a feasible circular strategy for microfibre waste reuse in mineral coatings. Full article

Electronic waste (e-waste) has emerged as one of the most critical environmental challenges of the twenty-first century. It encompasses a wide range of discarded electrical and electronic equipment, including information and communication technologies, household appliances, entertainment systems, and related components. While e-waste contains valuable recoverable materials, it also harbours hazardous substances such as toxic heavy metals, flame retardants, and persistent organic pollutants. Inadequate disposal practices, particularly open dumping and landfilling, result in the generation of toxic leachates that contaminate soil as well as surface and groundwater, posing severe threats to environmental integrity and public health. Evidence indicates that landfill leachates can infiltrate groundwater at considerable depths, exceeding permissible limits of heavy metals and metalloids and contributing to serious health disorders. Consequently, the implementation of effective e-waste management strategies and environmentally sound disposal practices is imperative to minimize its detrimental environmental and human health impacts. Microalgae systems can achieve up to 98% removal efficiency and up to five cycles reusability. In this paper, the drawbacks of the traditional methods for metal recovery from e-waste and the potential of microalgae were discussed. The downstream processing and metal extraction from microalgal biomass is critically discussed as well as strategies to support the circular economy. Full article

Global challenges in food security and sustainable biomass management highlight the need to diversify resource streams that can supply accessible, safe, and environmentally responsible protein. Delonix regia (flamboyant) seed germ (FG) represents an abundant but largely underutilized biomass resource in tropical and subtropical regions, where its seeds are routinely discarded as green waste. This study assesses the resource potential of FG by evaluating its nutritional composition, safety profile, and suitability for integration into sustainable protein provision strategies. The FG fraction was recovered from locally available seed residues and analyzed to determine their proximate composition, essential amino acid profile, and antinutrient content, providing insights into the qualitative attributes of this emerging resource. Safety was examined through in vivo acute toxicity assays and detailed histopathological evaluation of hepatic and renal tissues of CD1/ICR strain female mice, which revealed no morphological indicators of toxicity, inflammation, or cellular damage. The results indicate that FG contains a high protein concentration (78.35%) with a favorable essential amino acid pattern, supporting its potential as a renewable and locally accessible plant-based protein source. Beyond its nutritional value, the valorization of FG contributes to resource efficiency, waste-to-value pathways, and circular economy approaches by transforming an abundant municipal biomass residue into a functional component for sustainable food systems. Overall, the study underscores the feasibility of integrating FG into resource diversification strategies, enhancing protein availability while reducing environmental burdens associated with biomass disposal. Full article

The growing volume of waste electrical and electronic equipment presents both an environmental challenge and an opportunity for recovering critical raw materials embedded in discarded products. While recycling technologies are advancing, effective recovery remains strongly constrained by upstream collection systems, particularly in urban contexts subject to uncertainty, capacity limits, and regulatory constraints. This paper examines WEEE collection as a key lever for supporting sustainable critical-metal recovery in Europe. Methodologically, the study combines a Scopus-based bibliometric mapping and an institutional analysis of EU collection arrangements with the development of a robust multi-period mixed-integer linear programming model. After analysing organisational and regulatory arrangements in Poland and Portugal as illustrative cases, the paper introduces the Robust Multi-Period WEEE Allocation and Rare Metal Accumulation Problem (MP-WARMAP). The model integrates uncertain WEEE availability, intertemporal logistics planning, threshold-based rare-metal accumulation with endogenous sale timing, and a binding transport-related emission cap. Computational experiments show that robustness against inflow uncertainty can be achieved at a relatively low economic cost, that emission regulation exhibits a feasibility-threshold effect, and that capacity constraints may dominate price signals in determining recovery timing. The results highlight the importance of collection-system design and operational feasibility for improving the recovery of critical materials from urban WEEE streams. Full article

Sustainability is a major challenge for global food systems, particularly in the context of food loss and waste. Approximately one-third of food produced worldwide (1.3 billion tons annually) is lost or wasted, contributing to 8–10% of global greenhouse gas emissions, with a large share occurring during post-harvest handling and food processing. These stages generate by-products such as shells, skins, pulp, stems, and seeds, which can account for 30–50% of raw materials. Although often discarded, these residues are rich in valuable bioactive compounds, including phenolics, peptides, carotenoids, fibers, secondary metabolites, minerals, amino acids, and vitamins. This review emphasizes the valorization of agrifood by-products as a pathway toward sustainability and the achievement of the Sustainable Development Goals (SDGs). It encompasses extraction methods, characterization, and potential uses of such active compounds in the food, pharmaceutical, packaging, and cosmetic sectors. Moreover, it examines the interaction between valuing agrifood by-products and key SDGs like eliminating hunger (SDG 2), ensuring good health and well-being (SDG 3), promoting affordable and clean energy (SDG 7), promoting economic growth and decent work (SDG 8), ensuring responsible consumption and production (SDG 12), and tackling climate action (SDG 13). These approaches have high potential to improve food security and economic sustainability of the world’s food systems. Full article

The longest-standing international treaty for wetland and waterbird protection, the Ramsar Convention has resulted in the establishment of more than 2500 protected areas covering over 2.5 million square kilometers around the world. However, its measures are not legally binding, and its effectiveness as a tool for wildlife conservation has rarely been quantitatively assessed. In Benin, West Africa, breeding waterbirds are subjected to intense hunting and egg harvesting for both commercial and subsistence purposes. We quantified count data of waterbirds and eggs taken by local hunters and trappers to assess the effectiveness of the Ramsar Convention as a wildlife conservation tool in southeastern Benin. During the six-month period between May and October 2022, 64 people reported harvesting a total of 12,053 breeding waterbirds and 63,987 eggs, comprising eight species in three families in Ramsar site 1018. Birds most heavily targeted included Allen’s Gallinule (Porphyrio alleni), with 4187 breeding birds taken (~35% of all birds captured), and the White-faced Whistling Duck (Dendrocygna viduata), with 24,491 eggs taken (~38% of all eggs taken) over the course of a single breeding season. The Eurasian Moorhen (Gallinula chloropus) and Lesser Moorhen (Paragallinula angulata) were the third and fourth most targeted bird species, respectively, followed by the African Swamphen (Porphyrio madagascariensis), Black Crake (Zapornia flavirostra), African Jacana (Actophilornis africanus), and African Crake (Cecropsis egregia). Captured waterbirds were sold live at local markets, while eggs were eaten by hunters, except eggs containing chicks, which were discarded. Our findings show heavy persecution of waterbirds during their breeding season, when nesting birds are especially vulnerable to human predation, on a scale that is likely unprecedented and threatens to drive declines of targeted species in Benin. As local residents do not currently appear to recognize any deterrents to the uncontrolled hunting of breeding waterbirds or the collection of eggs in Ramsar site 1018, there is an urgent need to better leverage the Ramsar Convention to enforce conservation practices in this region. Full article

Rotor-induced micro-Doppler signatures are essential for radar-based characterization of rotary-wing UAVs, but practical echoes are often dominated by a strong quasi-static body return concentrated near zero Doppler. In hovering or low-speed scenarios, rotor-induced components may intermittently overlap this near-zero region, where hard DC suppression discards informative rotor content and fragments micro-Doppler structures. Data-driven decompositions such as EMD and VMD avoid fixed cutoffs, yet without explicit constraints on rotor periodicity they are vulnerable to mode mixing and residual leakage under low-SNR conditions. This paper proposes a Cyclic-Power-Guided Soft Mask (CPGSM) framework that exploits cyclostationary periodicity as a physically grounded prior for rotor–body separation. A CPS-guided soft masking procedure consisting of a DC-dominant overlap band is first identified from quasi-static dominance; within this band, cyclic power spectrum analysis yields a continuous rotor-consistency score that guides smooth time–frequency soft allocation, while deterministic assignment is applied elsewhere. Simulations demonstrate improved micro-Doppler continuity, reduced body leakage, and more stable performance from 5–30 dB SNR compared with hard DC isolation and EMD/VMD, together with consistent rotor-speed estimates across sensing configurations. Full article

Clementine, mandarin, and orange peels, which are usually discarded, can serve as promising, sustainable dietary supplements with beneficial compositions, as demonstrated in this study. Citrus peels are low in ash, fat, and protein, but high in moisture, fibre, sugar, and polyunsaturated fatty acids (PUFAs) (up to 60%). They contain high levels of omega-3 and omega-6 fatty acids, up to 30% each, making them a good health-promoting source, as shown by the values of nutritional indices as follows: PUFA/saturated fatty acid (SFA) (1.94 to 2.30), monounsaturated fatty acid (MUFA)/SFA (0.39 to 0.84), and PUFA/MUFA (2.37 to 5.82). Essential macro elements (K > Ca > Mg > S > P > Na) and trace elements (Fe > Zn > Mn > Cu > Cr > Mo > Co > Se) are unevenly distributed among the peels, along with non-essential elements, with Al (37 to 51 mg/kg) and Sr (17 to 30 mg/kg) predominating. Rare elements in food, such as V and W, are found up to 41 and 79 µg/kg respectively, followed by Nb > Ga > Y > Ge (5 to 11 µg/kg). Although citrus peels have a nutrient-dense composition, their monitoring must be ensured before inclusion in the common diet, particularly regarding non-essential elements, as for most of them the reference doses are not established and they could be harmful to human health. Full article

Saffron (Crocus sativus L.) is widely cultivated for the spice obtained from the stigmas, while the remaining floral biomass is discarded as biowaste. Accessing the phytochemical composition of these residues could enable their valorization as a low-cost and sustainable resource for nutraceutical applications. In this context, a quantitative ¹H NMR-based metabolite profiling approach, complemented by HPLC-DAD and LC-MS, was employed to comprehensively characterize saffron biowaste. A total of 40 metabolites were identified and quantified by NMR, including amino acids (611.1 ± 36.5 mg/100 g FW), carbohydrates (2801.4 ± 33.7 mg/100 g FW), lipids (702.7 ± 28.2 mg/100 g FW), and saffron-specific compounds such as crocin (596.6 ± 21.5 mg/100 g FW), picrocrocin (1126.3 ± 18.9 mg/100 g FW), safranal (398.4 ± 14.8 mg/100 g FW), and crocetin (13.4 ± 0.4 mg/100 g FW). Targeted fractionation further allowed the identification of kaempferol 3-O-sophoroside (15.44 ± 0.61% w/w in dry ethanolic extract) and 3-hydroxy-γ-butyrolactone. Overall, the results highlight the rich metabolite composition of saffron production waste and support its potential reuse as a valuable source of functional ingredients within a circular economy framework. Full article

Semi-supervised medical image segmentation has recently achieved great success, but assigning trustworthy pseudo-labels to unlabeled images has been a difficult problem in medical image processing. A common solution is to select reliable predicted pixels as the pseudo-labels. However, unreliable pixels are often concentrated in the edge areas of the foreground and background in medical tasks. Directly discarding these pixels will result in this important information never being available. The foreground of medical images is usually surrounded by the edge area. This section of pixels is a mixture of the two categories, which makes it very difficult to distinguish. To address these problems, we propose a semi-supervised medical segmentation framework that combines conformal prediction and contrastive learning. Our framework can use conformal prediction to select pseudo-labels with high confidence and preserve important boundary information. Furthermore, the segmentation performance of edge regions can be improved using contrastive learning between edge categories and non-edge categories. Extensive experiments on multiple benchmarks show that our framework consistently outperforms state-of-the-art methods. Full article

The rapid growth of textile waste generation, with more than 87% of discarded textiles worldwide being landfilled or incinerated, together with the extensive consumption of concrete in the construction industry, has intensified research into alternative materials capable of reusing waste without compromising concrete performance. In this context, this study evaluates the incorporation of recycled cotton textile fibers obtained from discarded garments into conventional non-structural concrete, focusing on its axial compressive behavior. Concrete mixtures were produced with fiber contents of 0%, 0.5%, 1.0%, and 5.0%, designed for a target compressive strength of 20.594 MPa and tested in accordance with ASTM standards. The results show that concrete containing 0.5% cotton fibers achieved 28-day compressive strength values comparable to those of the reference mix, remaining within the typical variability of concrete testing, while mixtures with fiber contents of 1.0% and 5.0% exhibited pronounced strength reductions, reaching approximately 12.494 MPa and 8.270 MPa, respectively. These findings suggest that recycled cotton fibers at low dosages (0.5%) do not significantly affect compressive strength and could be incorporated as a supplementary addition in non-structural concrete, provided that appropriate mix design and processing conditions are maintained. Full article

Oxidative stress–induced dysfunction of hair follicle dermal papilla cells (HFDPCs) is a key factor in the progression of hair loss. In this study, upcycled postbiotic cell-free supernatants (CFSs), derived from Limosilactobacillus fermentum (L. fermentum) MG901 and MG4237, which are typically discarded after fermentation, were evaluated for their protective effects in H₂O₂-damaged human dermal papilla cells. The CFS exhibited no cytotoxicity and significantly enhanced wound-healing capacity while suppressing intracellular reactive oxygen species accumulation under oxidative stress conditions. In addition, treatment with CFS restored mitochondrial function, indicating recovery from H₂O₂-induced cellular damage. Dermal papilla cell-specific functional markers, including alkaline phosphatase activity, were also significantly increased following treatment. Mechanistic analyses further revealed that these protective effects were associated with modulation of Wnt/β-catenin signaling as well as regulation of mitochondrial function. Collectively, these findings suggest that upcycled postbiotic CFS from L. fermentum MG901 and MG4237 mitigates oxidative stress-induced dermal papilla cell dysfunction, supporting its potential application as a sustainable cosmetic ingredient for alleviating hair loss. Full article

Copper and cobalt are critically important metals for the transition to renewable energy and various aspects of modern life. Their production from primary sources, ores, necessitates metallurgical separation from the unwanted host materials, resulting in the generation of a huge amount of waste. Copper smelting slag is one of these metallurgical wastes, with 39 million tonnes of slag generated and discarded globally each year. These massive amounts of slag occupy a considerable and growing land footprint, often close to residential areas, and present a hazard that potentially releases contaminants into the environment. On the other hand, they also represent a material that often contains a significant residual amount of valuable copper and cobalt. To better understand and address the challenge of reducing the adverse impacts of the waste, as well as the possible commercial opportunity the contained critical metals present, this study reviews global smelting slag production over the last 25 years, its composition, and technical reprocessing options. A summary of the chemical and mineralogical characterization of the copper slag from diverse research is thus provided, as well as a comprehensive overview of the processing strategies for metal recovery from copper slag, such as flotation, pyrometallurgy, and hydrometallurgy. The study demonstrates that a huge amount of smelting slag has been produced, with great variation and complexity, which represents a major potential resource for cobalt and copper metals. The chemical and mineralogical composition of smelting slag varies from location to location, depending on the properties of the feed concentrate, type of fluxes, furnace type, and cooling rates employed during and after the smelting processes. The overview of the production trends and reprocessing techniques shows that while some notable effective options exist or are emerging, further research is needed into the reprocessing of smelting slag waste in order to create economic value, improve energy efficiency in metal production, increase critical metal supply, and reduce negative environmental impacts. Full article

The bearded fireworm Hermodice carunculata (Polychaeta) has become increasingly problematic in Mediterranean artisanal fisheries, yet remains understudied. This study provides a detailed analysis of interactions between H. carunculata and artisanal fishers in Marsaxlokk, Malta’s largest fishing village. Combining fisher interviews (local ecological knowledge) and field data, the study reveals that fishing practices inadvertently sustain and amplify local fireworm populations by discarding worms and by-catch nearshore, thereby providing abundant food sources. The highest fisher activity correlated with significantly denser fireworm populations and smaller-sized individuals, indicating population growth driven by fisher practices. Fireworm predation significantly impacts fishers economically, causing an estimated direct loss of 52.5% of the expected profit across the five onboard sessions, due to damaged catch, along with additional indirect losses from reduced gear efficiency and increased labor. The worm’s painful sting adds further nuisance and discomfort for fishers who frequently handle infested gear. Despite awareness of fireworm behavior, fishers largely did not recognize their practices as exacerbating the issue, creating a feedback loop perpetuating the problem. Behavioral experiments suggested that modifying fishing practices and gear design might mitigate fireworm impacts. Addressing this socio-ecological challenge requires further targeted research, education, and policy support to break the cycle that benefits fireworm proliferation in the region to the detriment of fishers. Full article