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A comprehensive fatigue analysis of high performance polyetherimide parts fabricatedusing extrusion-based additive manufacturing
No full textThis paper investigates the fatigue behavior of high-performance polyetherimide components manufactured via MEX-AM, focusing on the influence of key process parameters. Thirty configurations were tested under four load levels, and fractographic analysis was conducted to study crack initiation and propagation. Building direction proved critical, with edge-printed specimens showing up to 2.4 times longer fatigue life under low loads than flat-printed ones. Sparse configurations, despite lower mass, achieved similar or even superior specific performance compared to solid ones. For example, X-Flat-0.25 mm doubled the fatigue life of the best solid specimen under low loads with a 24% weight reduction, while X-Flat-0.75 mm achieved a 44% mass saving with only a 15.5% reduction in fatigue life. These results demonstrate the potential of optimized sparse designs for lightweight, high-performance MEX-AM parts.info:eu-repo/semantics/acceptedVersio
Robustness of a pacemaker to control chaotic oscillations in a two-mass model of the vocal folds under turbulence and muscle twitch fluctuations and vocal tremor
No full textA pacemaker for phonation could be feasible in the near future thanks to advances in smart materials technology. However, before attempting it, much theoretical work needs to be done to figure out how it could work. Human phonation is a complex and highly non-linear fluid–structure interaction process for the onset of regular self-oscillations of the vocal folds to produce voice. Such oscillations can become chaotic for even moderate changes in the physical parameters of the folds or the subglottal pressure. Traditionally, low-dimensional biomechanical mass models have been used to understand the intricacies of both normal and abnormal phonation. In this framework, the possibility of devising a mass–spring–damper pacemaker capable of regulating chaotic oscillations of the vocal folds, which uses an altering energy feedback control strategy acting on the pacemaker damping, was recently analyzed. However, phonation can undergo several perturbations and it is necessary to test the robustness of the pacemaker against them. This is the objective of this work. Two types of disturbances are considered: random and periodic. The former are associated with glottal flow turbulence and also with muscle twitches, which are partially responsible for voice jitter. The second are related to vocal tremor and are often found in patients with paresis, Parkinson’s disease or adductor spasmodic dysphonia, among others. Using tools for the analysis of nonlinear dynamical systems, it will be demonstrated that the pacemaker can respond quite well to random and periodic perturbations, supporting its potential for partial remedy of voice pathologies.info:eu-repo/semantics/acceptedVersio
Assessing the efficiency of zeolites in BTEX adsorption: Impact of pore structure and humidity in single and multicomponent systems
No full textAmong volatile organic compounds (VOCs), benzene, toluene, ethylbenzene and o-xylene (BTEX) have attracted global attention because of their high toxicity to the environment and human health. Adsorption is considered one of the most efficient, simple and low-cost technology for VOC pollution control and zeolites have been commonly used as adsorbent for this purpose. However, the evaluation of the performance of zeolites in the adsorption of BTEX under realistic conditions such as the presence of humidity or multicomponent systems has been poorly addressed. In this study, the adsorption capacity of BTEX of seven zeolites belonging to the structural families LTA, MFI, BETA, MOR and FAU have been investigated. Zeolites have been characterized by X-ray fluorescence and nitrogen sorption measurements. The relationship between the adsorption capacity and physicochemical parameters was investigated. It was found that MFI structure was the best adsorbent for benzene and toluene reaching an adsorption capacity of 69.2 mg/g. Whereas FAU structure exhibited preference to trap ethylbenzene and o-xylene adsorbing up to 93.8 mg/g. Specific surface area and pore diameter of zeolites were found to be the most important parameter for BTEX adsorption. The properties of the adsorbate (molecular structure, polarity and boiling point) played also a key role in adsorption.
Si/Al ratio was a key factor in determining adsorption performance under humidity conditions with the best adsorption capacity reaching 16.9 mg/g. In multi-component system, the adsorption capacity of zeolites decreased more than 14 %. The results obtained may guide to select proper adsorbent for BTEX in real applications.info:eu-repo/semantics/acceptedVersio
From risk to action: how perceived risks and cultural dynamics drive surplus food purchases in China and Spain
No full textSurplus food retailing reduces waste and supports food security; however, cultural differences critically shape consumer behaviors. Combining the theory of planned behavior and risk theory, this study compares the drivers and barriers of purchase intentions for surplus food in China (n = 695) and Spain (n = 535) using multi-group analysis combined with necessary condition analysis. The results highlight that Chinese consumers’ intentions rely on perceived behavioral control (enabled by e-commerce and policies), personal norms and attitudes, whereas Spanish intentions hinge on physical, performance, and financial risk perceptions, with no significant behavioral control effects. The findings challenge one-size-fits-all approaches to food waste reduction, proposing an actionable framework in which China prioritizes digital infrastructure and norm-based campaigns, while Spain targets risk-transparent labeling and trust building. This study advances resource-efficient food systems by prioritizing contextual drivers, offering policymakers a roadmap for aligning surplus food strategies with the United Nations Sustainable Development Goals.info:eu-repo/semantics/acceptedVersio
Microstructure and mechanical properties of TiN/CrN multilayer coatings deposited in an industrial-scale HiPIMS system
No full textTiN/CrN multilayer coatings of varying bilayer period (Ʌ) were deposited in an industrial-scale deposition plant by means of reactive high power impulse magnetron sputtering. By alternately sputtering titanium and chromium targets in a nitrogen-containing atmosphere, coatings with a Ʌ between 7 and 460 nm were obtained. The influence of Ʌ was investigated in regard of chemical composition, microstructure, and mechanical properties of the coatings. All coatings appear to be smooth and compact based on scanning electron microscope observations. X-ray diffraction showed separate crystalline phases of TiN and CrN for the samples with higher Ʌ. However, for the smallest periods (Ʌ7 and Ʌ15), the position of the peaks corresponding to the TiN and CrN phases overlap, which is consistent with the coherent growth of these phases and/or the formation of a ternary TiCrN crystalline phase. Additionally, the presence of satellite peaks points to a superlattice structure comprising TiN and CrN sublayers. High resolution transmission electron microscopy analysis on the superlattice samples evidenced an epitaxial growth across the superlattice interfaces for these coatings. An average compressive stress value of 2.2 GPa was measured, falling between those of TiN and CrN single-layer coatings. The sample exhibiting the highest hardness (H) and Young's modulus (E) values, reaching 31.9 GPa and 394 GPa, respectively, corresponded to Ʌ15. Nevertheless, while the Ʌ7 sample slightly reduced the H and E values (27.7 and 335 GPa respectively), it achieved maximum H/E and H3/E2 ratios, which are of particular interest to enhance wear resistance and prevent cracking failure. In summary, this work highlights the potential of depositing nanostructured multilayer coating with engineered interfaces and periodicities, providing exceptional mechanical and tribological properties, using a HiPIMS industrial deposition system.info:eu-repo/semantics/acceptedVersio
Generation of ultrasonic and audible sound waves for the automatic classification of packaging waste in reverse vending machines
No full textReverse vending machines (RVMs) are essential for promoting waste sorting at the source by offering incentives for recycling.However, current RVMs, which primarily rely on expensive sensors such as barcode scanners and computer vision systems, face limitations including unreadable barcodes, high computational demands, and sensitivity to environmental conditions like lighting. This paper presents an alternative, cost-effective approach using acoustic sensors for waste classification, aiming to reduce the
production cost of RVMs. The proposed method consists of emitting ultrasonic and audible sound waves towards the recyclable object and, by analyzing the variations in the acoustic field, an artificial intelligence system classifies the material. For doing so, the system uses the ultrasonic and audible impulse response of each item, measured using the exponential sine sweep (ESS) technique. To validate this approach, a proof-of-concept has been developed and tested in a controlled environment using a scaled replica of
a reverberation chamber, designed to achieve ideal acoustic conditions. Acoustic impulse responses have been captured using ESS emitted by an omnidirectional parametric loudspeaker (OPL), which generates both ultrasonic and audible sound waves via the parametric acoustic array (PAA) effect. This setup allows for simultaneous collection of ultrasonic and audible impulse responses for each recyclable item. The collected acoustic data has then been used to train classical machine learning and deep learning
models to classify the introduced material, specifically plastic, glass, cardboard, and metallic cans. Initial results show promising classification accuracy, demonstrating the potential of this acoustic technology for broader application in RVMs.info:eu-repo/semantics/acceptedVersio
Highly potent dipeptidyl peptidase 8/9 (DPP8/9) inhibitors designed via relative binding free energy calculations
No full textDipeptidyl peptidases (DPP) 8 and 9 are emerging enzymatic drug targets with suggested applications in acute myeloid leukaemia and HIV infection, among others. In this work, we optimised a well-known reference DPP8/9 inhibitor named 1G244, using relative binding free energy calculations. An initial retrospective, computational analysis of experimental structure-activity data of 1G244 and close structural analogues, guided the subsequent prospective design of novel inhibitors derived from the reference scaffold. Synthesis of the proposed compounds - together with in vitro evaluation and initial pharmacokinetic and pharmacodynamic studies - are presented and discussed. As a result, we present the optimization of 1G244 in a new family of potent piperidine based DPP8/9 inhibitors. Finally, we report for lead compound 21 and reference 1G244 the cardiac channel affinity which must be carefully considered when using these molecules as a tool to further clarify the role of DPP8 and DPP9 in cellular physiology.info:eu-repo/semantics/acceptedVersio
Electrochemical response of Sr(Ce0.9Zr0.1)0.95Yb0.05O3-δ high-temperature hydrogen sensor
No full textMeasuring tritium in fusion reactors like EU-DEMO is crucial for the functioning of the reactor and the helium-cooled lithium-lead (HCLL) breeding blanket breeding blanket. Electrochemical sensors can be a great option for the measurement of hydrogen and its isotopes since they have several advantages over other analytical methods, such as sensitivity, robustness, ease of operation, short-time measurement, portability, and on-site and real-time measurement.
One of the main difficulties for hydrogen detection is to select materials that can withstand high temperatures and harsh conditions. In this situation, perovskite-type ceramics, such as Sr(Ce0.9Zr0.1)0.95Yb0.05O3-δ, show proton conductivity and remarkable stability under low-oxygen atmospheres and high temperatures. These characteristics make perovskite materials ideal candidates for the creation of high-temperature hydrogen sensors.
In the present work, the proton-conducting perovskite Sr(Ce0.9Zr0.1)0.95Yb0.05O3-δ was synthesized by the glycine method (SCZY-gly). Then, disks of Ø13 mm were obtained by uniaxial pressure, followed by a sintering process at 1300 – 12 h The powder and the pellets were characterized using XRD and SEM analysis. The proton conductivity of the sintered elements was calculated using electrochemical impedance spectroscopy (EIS). Finally, amperometric measurements were performed at 500 °C and 600 °C using different hydrogen concentrations.info:eu-repo/semantics/acceptedVersio
From Françafrique to Chinafrica? Ecologically unequal exchange, neocolonialism, and environmental conflicts in Africa
No full textAfrica stands out as the continent where the legacies of colonialism and the ongoing dynamics of neo- and post-colonialism are felt most profoundly. In its role as the primary global supplier of raw materials, and with the ongoing technological transition towards the so-called “smart” economy and “green” energy systems, the demand for minerals from Africa is anticipated to increase significantly. European imperialism and its historically embedded extractivist logic are indispensable to understand the conditions that gradually prompted many African states to seek new trading partners. But “coloniality” is not limited to historical colonialism. Over the last two decades China has gradually assumed a prominent role in African trade, becoming Africa’s first trading partner, and leading several scholars to ask whether China is developing a new kind of colonialism. The impact of extractive activities by European, American, and Chinese private and public companies on African resources has been profound, resulting in the shifting of socio-ecological costs from industrialised countries to the African extractive peripheries. In this work, we employ a political ecology approach to examine: i) the claims of lingering French imperialism and Chinese neocolonialism; and ii) the impact of projects implemented by actors from France and China in Africa. We mobilise the theory of ecologically unequal exchange and cases of environmental conflicts involving Chinese and French industries to demonstrate how these projects have resulted in damaging impacts over African territories, leading to land pollution and detrimental effects on community health. We find evidence of ecologically unequal exchange both in the Chinese and French cases, though the dynamics characterising the trading relations of these two countries with the ensemble of African countries is markedly different.info:eu-repo/semantics/acceptedVersio
Non-target metabolomic approach of the toxic effects of glyphosate in zebrafish (D. rerio)
No full textGlyphosate (GLY) is the most widely used herbicide globally and is frequently detected in aquatic environments at low concentrations, raising concerns about its potential long-term effects on non-target organisms. However, the systemic metabolic disruptions of chronic GLY exposure in aquatic vertebrates remain poorly understood, especially at environmentally relevant concentrations.
This study investigates the metabolic disruptions of GLY exposure in zebrafish (D. rerio) using a non-targeted metabolomic approach. Brain, gut, and fecal samples were analyzed after two weeks of exposure to environmentally relevant concentrations (0.3 and 3 μg L−1). Metabolic profiling was performed using LC-HRMS data processed via the Regions of Interest Multivariate Curve Resolution (ROIMCR) method, resolving up to 70 components per tissue and capturing >99 % of the experimental variance.
Direct MSident annotation revealed diverse biomolecules, including amino acids, sugars, nucleotides, and organic acids. Tentative identification yielded 92, 182, and 117 metabolites in the brain, gut, and feces, respectively, further confirmed by the KEGG database.
Statistical analysis revealed significant metabolic differences between control and GLY-treated groups, particularly at higher concentrations. Significantly altered metabolites were observed in the brain (37), gut (75), and feces (31), respectively. Fifteen overlapping metabolites between the studied brain and gut tissues suggest a GLY-induced gut-brain axis disruption.
Functional enrichment analysis showed down-regulation of pathways related to amino acid, lipid, and energy metabolism, especially in gut and brain tissues, while fecal metabolites were generally up-regulated. These results demonstrate that GLY exposure induces tissue-specific and systemic metabolic disturbances in zebrafish, potentially linked to oxidative stress and neurotoxicity, with implications for aquatic health and environmental risk assessment.info:eu-repo/semantics/acceptedVersio