Using minimax techniques from critical point theory, which consists in constructing or transforming a suitable class of mappings such that a critical value c of a functional f can be characterized as a minimax value over this class, we establish a new natural infinite-dimensional linking theorem for strongly indefinite functionals by using the tau-topology of Kryszewski and Szulkin. Our result is a generalization of the classical linking theorem [13, Theorem 2.21]. As an application, we obtain the existence of a nontrivial solution to a system of coupled Poisson equations. (c) 2026 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Abstract The long-term performance of concrete structures depends critically on their durability, governed by transport mechanisms within the matrix. This study aims to determine whether carbonate-rich calcined marl derived from Moroccan phosphate waste can enhance transport-related durability properties of concrete while maintaining long-term mechanical performance at high substitution levels. Concrete mixtures were designed with varying water–binder ratios (0.45 and 0.55) and substitution levels (up to 40% by weight) to evaluate workability, mechanical performance, and durability. Incorporating calcined marl improved electrical resistivity, reduced water absorption, and enhanced sulfate resistance due to its pozzolanic activity and pore refinement effect. Although early-age strength decreased slightly because of dilution, long-term strength development was remarkable, reaching 81% above the control mix at 365 days. The main limitation observed was reduced carbonation resistance, which requires further investigation for practical applications.
Dry reforming of methane (DRM) and autothermal dry reforming (ATDR) are promising technologies for converting methane and carbon dioxide into syngas (H2 and CO), an important feedstock for the production of fuels and value-added chemicals. However, their industrial implementation remains challenging because of the highly endothermic nature of DRM, heat management issues during autothermal operation, and catalyst deactivation caused by carbon deposition, metal sintering, oxidation, and poisoning. Although numerous studies have reported advances in catalyst development, an integrated understanding of thermodynamic constraints, catalyst stability, and emerging energy-input technologies remains limited. This review discusses the thermodynamics of DRM and ATDR, together with the catalytic aspects of DRM. Particular emphasis is given to the influence of operating conditions on equilibrium conversion, gas composition, carbon formation, and hotspot development. Recent advances in thermal catalytic systems are discussed, highlighting the roles of catalyst supports, promoters, and active metals, together with strategies for mitigating catalyst deactivation. Furthermore, photothermal and microwave-assisted dry reforming are critically evaluated as alternative energy-input technologies for overcoming the thermodynamic and kinetic limitations of conventional thermal reforming. Overall, this review provides a comprehensive framework for optimizing reaction thermodynamics, catalyst design, and reactor operation to enable efficient, stable, and sustainable syngas production.
This paper presents a comprehensive review of the existing literature on the key phenomena influencing prehospital emergency service (PES) demand, PES demand prediction, and ambulance positioning and routing. The identification and understanding of these factors are essential for the intelligent management of PES and informed decision-making. Effective management depends on the accuracy of emergency call prediction models and the strategies used to optimize emergency vehicle routing and standby locations, both of which are examined and discussed in this paper. The findings of this study could serve as a foundation for further research and practical advancements in response to the increasing demand for PES.
Biochemical Methane Potential (BMP) tests are fundamental for assessing the methane production capacity of organic substrates used for anaerobic digestion (AD). However, reproducibility of such tests still represents a significant challenge due to variations in experimental setups, the measurement techniques for biogas volume, as well as inoculum characteristics. To address these issues, standard protocols are used to ensure the reproducibility of results, but such protocols still have some gaps that can impact the test. This research aims to evaluate the impact of headspace pressure in pressurized and non-pressurized bottles, using manometric and automatic volumetric BMP systems to generate those different conditions, varying the filling volume of the bottles (from 30% to 70%) and the inoculum-to-substrate ratio (ISR) (from 2 to 6), to highlight its influence on methane yield. The results indicate that high headspace pressure, caused by a high filling volume and a low ISR, correlates with reduced methane production. The headspace composition leads to the assumption that CO2 dissolves into the liquid phase at high-pressure, leading to pH alterations that could inhibit the process. Our findings demonstrate that headspace pressure must be carefully controlled in BMP tests, especially when using manometric systems, to avoid underestimation of methane potential.
