Municipal wastewater treatment plants face increasing pressure to improve energy recovery while reducing sludge volumes and operational costs. In this context, low-input process intensification strategies are of growing interest. This study evaluated a continuous side-stream magnetization strategy applied during 44 days of mesophilic anaerobic digestion (37 +/- 2 degrees C) of sewage sludge, where digesting sludge was continuously recirculated through a tubular rare-earth-material magnetic polarizer generating a low-intensity static magnetic field (20 mT). The experimental results revealed a substantial increase in AD performance, with the SMF-exposed reactor achieving a 48.3% increase in specific biomethane production and a 15% higher reduction in volatile solids compared to the control reactor. Additionally, the digestate exposed to the SMF showed an improved dewaterability, evidenced by a 26.8% reduction in capillary suction time compared to the non-magnetized digestate. Microbial community analysis at the end of the AD process indicated that continuous exposure to SMF significantly enhanced the abundance of key methanogens, including Methanosarcina and Methanobacterium, which contributed to the higher biomethane production observed during AD. These findings indicate that continuous SMF exposure during AD can significantly enhance biomethane production and can be regarded as a promising approach to improve energy recovery from sewage sludge.
Surface texturing has emerged as a promising approach to improve lubrication performance and reduce energy losses in mechanical systems. However, the influence of dimple size and density on the frictional behavior of lubricated nonconformal contacts remains insufficiently explored, especially using cost-effective mechanical methods. This study aims to address this gap by investigating the effect of microindented textures, produced via Vickers microhardness indentation, on the lubricated tribological response of 100Cr6 steel spherical surfaces. Two load levels were used (0.5 N and 5 N), thus allowing us to investigate two dimple sizes (diagonal dimension of 10 and 30 & micro;m) and two void ratios (VR) (5% and 17%). The tribological performance was evaluated under various sliding speeds using a ball-on-disk setup and two lubricants with different viscosities (CADT-605 and Lubro Lam) to capture the full Stribeck curve. Results reveal that fine dimples with the highest VR (VR = 17%) significantly reduce the coefficient of friction (COF), by up to 40%, across all lubrication regimes, due to enhanced secondary lubrication. Conversely, large dimples increased the COF due to pile-up formation and lubricant vortex generation. These findings provide new insights into the role of texture geometry in optimizing lubrication performance and pave the way for scalable and economic surface functionalization techniques in tribological applications.
This study introduces the Regional Index of Looseness (RIL), a novel measure of cultural tightness-looseness computed at the NUTS-2 regional level for European countries. We distinguish between horizontal and vertical looseness, grounded respectively in interpersonal norm flexibility and attitudes toward supraordinate authority, and construct the index using dispersion in ordinal responses with data from the European Values Study. Methodologically, we employ an index of ordinal variation that avoids the limitations of the standard deviation when applied to Likert-type scales. We validate the RIL by comparing it with existing national-level tightness-looseness measures and by examining its association with other cultural constructs. Finally, we propose two exploratory applications (vaccination attitudes and compliance with non-pharmaceutical interventions during COVID-19) to illustrate how regional looseness correlates with public health behaviors. The results highlight substantial within-country heterogeneity and demonstrate the usefulness of regional cultural measures for understanding behavioral responses to collective risks.
Wood modification is a process that alters the properties of wood through chemical, thermal, or physical treatments, thereby improving its performance, including durability and dimensional stability. Steaming is a hygrothermal treatment that can modify physical properties and may affect mechanical performance depending on process severity. This study investigated the effects of low-temperature steaming on olive wood (Olea europaea L.) by applying a constant temperature (80 °C) and varying treatment duration (12, 18, and 36 h) compared with natural seasoning (control). Color and dynamic modulus of elasticity (MOEd) were measured on boards before and after treatment; after, specimens were tested for dimensional stability, bending properties (MOR and MOEs), compression strength, Janka hardness, and abrasion resistance. Steaming produced significant color changes in both heartwood and sapwood, with stronger responses in sapwood. Bending properties showed non-significant increasing trends, with mean MOR increasing from 50.21 MPa (control) to 62.24–64.71 MPa and the highest mean MOEs observed in the 12 h group (+ 13.45
Potamogeton natans L. is a widespread floating-life macrophyte of high ecological relevance in freshwater ecosystems. By contributing to oxygenation, habitat structure, water clarity and nutrient cycling, it plays a key role in ecosystem functioning, although under favourable conditions it can form dense stands that impair water flow, irrigation and navigation. This review integrates current knowledge of the species’ taxonomy, morphology, distribution and ecological impacts, with a particular focus on how its chemical traits contribute to ecological interactions such as herbivore deterrence, allelopathy and potential competitive advantages. We summarize the main classes of secondary metabolites reported in P. natans – including alkaloids, phytoecdysteroids, labdane diterpenes, phenolics and polysaccharides – and discuss their ecological functions as well as their possible use in environmentally sustainable management strategies, including natural algicidal applications. By linking ecological roles with chemical composition, this review highlights P. natans as both a structurally important component of freshwater vegetation and a promising model for understanding chemical ecology in aquatic plants. Future research should clarify metabolite functions in situ and assess their relevance for integrated and ecologically sound aquatic-weed management. The graphical abstract illustrates the multifaceted nature of Potamogeton natans L., organized into three core pillars: Ecological Role, Chemical Composition, and Bioactivity Potential. On the left, the Ecological Role highlights the plant’s dual impact. It serves as a beneficial “ecosystem engineer” by promoting water oxygenation, clarity, and habitat stability. Conversely, its invasive growth patterns can obstruct navigation and damage irrigation infrastructure, necessitating diverse management strategies such as mechanical, chemical, and biological controls. The central panel, Chemical Composition, focuses on the plant as a biological factory. Beyond its physical structure, P. natans is rich in secondary metabolites, most notably labdanes, alkaloids, phytoecdysteroids, lipids and polysaccharides. These molecules serve as the foundation for the plant’s chemical defense mechanisms and economic value. The right panel, Bioactivity Potential, connects these compounds to specific applications. The labdanes exhibit potent algicidal properties against harmful cyanobacteria, while the polysaccharide fractions demonstrate anti-inflammatory effects comparable to standard pharmaceuticals. The abstract concludes by identifying Future Research directions, specifically focusing on sustainable applications.
