Laval Mayenne Technopole

This study investigates the fatigue behaviour of hybrid PA66 composites reinforced with short and continuous fibres through fatigue testing and in-situ microtomography. Damage initiates in the PA66GF50 short-fibre composite, propagates as a macro-crack towards the UD reinforcement, and leads to fibre fracture, fibre–matrix debonding, and rapid crack growth. A strong correlation exists between cyclic creep stages, at macroscopic level, and damage: primary stage with negligible damage, secondary stage, which defines the cyclic creep strain-rate criterion, is characterised by the initiation and limited progression of micro-damage, and tertiary stage with macro-crack propagation. Weaknesses lie in the short-fibre composite and fibre–matrix interface, rather than between the two polyamides. • Fatigue mechanisms of short-and continuous-fibre reinforced PA66 composites are investigated through macroscopic and in-situ μCT tests. • Damage is initiated in the PA66GF50 matrix and is propagated as a macro-crack towards the UD reinforcement. • Final failure is driven by continuous fibre fractures and fibre–matrix debonding. • Fibre breaks, fibre-end damage, cavitation and matrix crazing all contribute to the microscopic damage mechanisms. • Cyclic creep stages are directly correlated to the initiation and growth of damage.

Purpose In the field of 4D printing, shape memory polymers are gaining more and more interest, thanks to their large deformability and ease of manufacturing, compared to their metallic alloy counterparts. However, they are still rarely adopted for industrial applications, often limited by the poor time and space accuracy of their recovery behaviour. In this paper, the aim is to use an electroconductive shape memory polymer to design a hinge for the self-deployment of space structures. Design/methodology/approach Fused filament fabrication and composite material made of bio-sourced polylactic acid filled with carbon black particles are used. First, the hinge is conceived as the answer to an inverse design problem: its geometry integrates an electrical circuit and the influence of the printing parameters is considered to perform the shape memory behaviour. The deployment of the hinge is filmed and tracked thanks to a multi-instrumented setup to calculate its recovery ratio and kinetics and evaluate its performance. One to ten deployments are considered to study their behaviour under repeated use. Furthermore, the force deployed is measured and compared between the first and the tenth cycles to evaluate its durability. Findings Results show that the hinge is able to recover up to 80% of its initial shape and deploy the same force through the cycles. Originality/value This paper highlights the ability of training the shape memory effect to obtain targeted results and the capacity of the device to maintain the force deployed throughout the cycles. A novel multi-instrumented setup is presented to measure four different properties (electrical, thermal, mechanical and force).

Purpose Hybrid entrepreneurship is the practice of individuals launching a business while simultaneously maintaining their primary job in paid employment. This study examines how cognitive multitasking impacts psychological distress among hybrid entrepreneurs using job demands-resources theory to investigate the mediating roles of stress, sleep quality and perceived health. Design/methodology/approach Data from 228 Quebec hybrid entrepreneurs were analyzed using sequential mediation modeling with Macro-Process. Findings While hybrid entrepreneurs vary in their ability to compartmentalize dual roles, cognitive multitasking is positively associated with psychological distress. While sleep quality does not directly mediate this relationship, it operates through two indirect pathways: increasing stress levels and deteriorating self-rated health. Both stress and self-rated health significantly mediate between cognitive multitasking and psychological distress. Research limitations/implications Cross-sectional design limits causal inferences. Future research should employ longitudinal designs and objective measures across diverse contexts. Practical implications Hybrid entrepreneurs should implement structured time management techniques and prioritize sleep hygiene. Organizations should offer flexible work arrangements and stress management resources, while entrepreneurship support programs should incorporate well-being components addressing dual-career challenges. Social implications Addressing the psychological and physiological costs of hybrid entrepreneurship can foster sustainable entrepreneurial activity while reducing work-related psychological distress and associated societal costs. Originality/value This study advances research on entrepreneurial well-being by examining how multitasking affects psychological health in hybrid entrepreneurs, addressing an understudied segment, highlighting cognitive and physiological costs and clarifying the complex relationships between cognitive multitasking, sleep, stress, health and psychological distress.

Copper (Cu) and zinc (Zn) are trace elements required for a multitude of physiological processes, including wound healing, and there has been a long history of including both metal ions in topical skin repair formulations. Wound healing involves complex and dynamic cellular mechanisms in the main phases of platelet hemostasis, inflammation, granulation tissue formation, re-epithelialization, and extracellular matrix remodeling. This process is influenced by the balance in the skin's commensal microbiota, and the risk of microbes becoming pathogenic through migration and colonization of the deeper tissues. We examine the antimicrobial effects of Cu/Zn versus their roles in the innate immune response that prevents the invasion and proliferation of microorganisms and in the cellular mechanisms that promote wound healing. Cu/Zn modulates macrophage polarization, promoting the transition from the pro-inflammatory M1 phenotype to the pro-healing M2 phenotype, which is critical for tissue repair. Both elements also act as cofactors that modulate the activities of important growth factors, mediators, and enzymes, including antioxidant enzymes, such as superoxide dismutase, which have a role in the innate immune response to pathogens and protect cells from oxidative damage, reducing inflammation and promoting healing. These divalent ions stimulate angiogenesis, and the Cu/Zn combination can also modulate integrin expression in keratinocytes, which are needed for re-epithelialization, supporting cellular mobility and differentiation, and enhancing the healing process. The synergistic roles of Cu/Zn in preventing infection while stimulating the skin's natural immune defenses encourage efficient tissue repair after injury. Topical Cu/Zn-containing formulations therefore hold promise for improving wound management.

ABSTRACT We assess the impact of Quebec’s 2004 activity-based funding (ABF) reform on surgical volumes using physician billing data from all Canadian provinces (1996–2014). Applying difference-in-differences and triple-differences models, we compare changes in hip, knee, and cataract surgeries in Quebec to those in other provinces, controlling for demographic and health trends. We find no significant effect for hip or knee procedures, but a notable increase in cataract surgeries, especially after 2010. These results likely reflect inpatient capacity constraints and the greater scalability of outpatient cataract surgery, underscoring the role of context in shaping ABF effectiveness.

Abstract Loss of GABAergic and glycinergic inhibitory efficacy in the spinal dorsal horn is associated with neuropathic pain and opioid-induced hyperalgesia in rodent models. Downregulation of the KCC2 chloride extrusion transporter is a key mechanism underlying this decreased inhibitory efficacy, but to-date there is no evidence supporting or opposing this hypothesis in humans. Here we demonstrate that KCC2 expression is decreased in superficial dorsal horn neurons of organ donors who died with a documented history of pain, or of long-term opioid use. We show profoundly decreased KCC2 dorsal horn membrane expression in a primary cohort associated with either chronic pain or opioid use, and in a replication cohort of mixed chronic pain and opioid use history. These results show that decreased dorsal horn inhibitory efficacy likely promotes chronic pain in humans and support the development of therapeutics augmenting KCC2 function as a treatment for chronic pain and opioid use disorders.

Swarms of UAVs offer enhanced capabilities through coordinated operations. However, effective swarm navigation in GNSS-denied indoor environments relies on robust and precise localization, which presents significant challenges due to harsh conditions. Collaborative Simultaneous Localization and Mapping (C-SLAM) algorithms offer a promising solution, but their success depends heavily on selecting an optimal combination of sensors that balances tradeoffs between accuracy, robustness, energy efficiency, and payload constraints. This paper addresses this challenge by employing the Analytical Hierarchy Process (AHP) to systematically evaluate and prioritize perception and ranging sensors for UAV swarms. Through a detailed tradeoff analysis, the study identifies the RGB-D camera, UWB module, and IMU as the most effective sensor combination, enabling enhanced performance and robustness in challenging indoor environments. The findings provide a structured decision-making framework for sensor selection, advancing the design of robust C-SLAM systems for real-world UAV swarm applications.