Institut Catholique d'Arts et Métiers

Three-dimensional bioprinting of biomaterials shows great potential for producing cell-encapsulated scaffolds to repair nerves after injury or disease. For this, preparation of biomaterials and bioprinting itself are critical to create scaffolds with both biological and mechanical properties appropriate for nerve regeneration, yet remain unachievable. This paper presents our study on bioprinting Schwann cell-encapsulated scaffolds using composite hydrogels of alginate, fibrin, hyaluronic acid, and/or RGD peptide, for nerve tissue engineering applications. For the preparation of composite hydrogels, suitable hydrogel combinations were identified and prepared by adjusting the concentration of fibrin based on the morphological spreading of Schwann cells. In bioprinting, the effects of various printing process parameters (including the air pressure for dispensing, dispensing head movement speed, and crosslinking conditions) on printed structures were investigated and, by regulating these parameters, mechanically-stable scaffolds with fully interconnected pores were printed. The performance of Schwann cells within the printed scaffolds were examined in terms of viability, proliferation, orientation, and ability to produce laminin. Our results show that the printed scaffolds can promote the alignment of Schwann cells inside scaffolds and thus provide haptotactic cues to direct the extension of dorsal root ganglion neurites along the printed strands, demonstrating their great potential for applications in the field of nerve tissue engineering.

Extrusion-based bioprinting of hydrogel scaffolds is challenging due to printing-related issues, such as the lack of capability to precisely print or deposit hydrogels onto three-dimensional (3D) scaffolds as designed. Printability is an index to measure the difference between the designed and fabricated scaffold in the printing process, which, however, is still under-explored. While studies have been reported on printing hydrogel scaffolds from one or more hydrogels, there is limited knowledge on the printability of hydrogels and their printing processes. This paper presented our study on the printability of 3D printed hydrogel scaffolds, with a focus on identifying the influence of hydrogel composition and printing parameters/conditions on printability. Using the hydrogels synthesized from pure alginate or alginate with gelatin and methyl-cellulose, we examined their flow behavior and mechanical properties, as well as their influence on printability. To characterize the printability, we examined the pore size, strand diameter, and other dimensions of the printed scaffolds. We then evaluated the printability in terms of pore/strand/angular/printability and irregularity. Our results revealed that the printability could be affected by a number of factors and among them, the most important were those related to the hydrogel composition and printing parameters. This study also presented a framework to evaluate alginate hydrogel printability in a systematic manner, which can be adopted and used in the studies of other hydrogels for bioprinting.

People across the world and throughout history have gone to great lengths to enhance their physical appearance. Evolutionary psychologists and ethologists have largely attempted to explain this phenomenon via mating preferences and strategies. Here, we test one of the most popular evolutionary hypotheses for beauty-enhancing behaviors, drawn from mating market and parasite stress perspectives, in a large cross-cultural sample. We also test hypotheses drawn from other influential and non-mutually exclusive theoretical frameworks, from biosocial role theory to a cultural media perspective. Survey data from 93,158 human participants across 93 countries provide evidence that behaviors such as applying makeup or using other cosmetics, hair grooming, clothing style, caring for body hygiene, and exercising or following a specific diet for the specific purpose of improving ones physical attractiveness, are universal. Indeed, 99% of participants reported spending >10 min a day performing beauty-enhancing behaviors. The results largely support evolutionary hypotheses: more time was spent enhancing beauty by women (almost 4 h a day, on average) than by men (3.6 h a day), by the youngest participants (and contrary to predictions, also the oldest), by those with a relatively more severe history of infectious diseases, and by participants currently dating compared to those in established relationships. The strongest predictor of attractiveness-enhancing behaviors was social media usage. Other predictors, in order of effect size, included adhering to traditional gender roles, residing in countries with less gender equality, considering oneself as highly attractive or, conversely, highly unattractive, TV watching time, higher socioeconomic status, right- wing political beliefs, a lower level of education, and personal individualistic attitudes. This study provides novel insight into universal beauty-enhancing behaviors by unifying evolutionary theory with several other complementary perspectives.

Today, in electric railways, the old dc supply systems are reaching their limits. To improve their efficiency and increase railroad traffic, a new dc electrification has recently been proposed at 9 kV. It is now necessary to prepare the migration of infrastructure and rolling stock, using power electronic transformers (PETs), for adaptation to this voltage level. For this application, high efficiency and reduced volume are essential. This article clearly demonstrates that it is now possible to achieve a compact, high-power, isolated dc-dc converters using 3.3-kV SiC-MOSFET power modules with high efficiency. After a preliminary study based on simulations, this article focuses on the characterization and implementation of elementary isolated dc-dc converters. The proposed topology is a series-resonant converter rated for a nominal power of 300 kW at 1.8 kV. First, laboratory testing using an “opposition method” is used to evaluate the elementary converters up to their nominal power using both electrical and thermal measurements to accurately determine losses and efficiency. At the nominal output power, an efficiency of 98.93% is obtained. This is quite remarkable for an isolated dc-dc converter operating under 1.8 kV with a switching frequency of 15 kHz. Finally, two elementary isolated dc/dc converters are associated with input series/output parallel (ISOP) configuration in order to achieve a 3-kV/1.5-kV PET with a nominal power of 600 kW as a prelude to the final 9-/1.5-kV power conversion.

Love is a phenomenon that occurs across the world and affects many aspects of human life, including the choice of, and process of bonding with, a romantic partner. Thus, developing a reliable and valid measure of love experiences is crucial. One of the most popular tools to quantify love is Sternberg's 45-item Triangular Love Scale (TLS-45), which measures three love components: intimacy, passion, and commitment. However, our literature review reveals that most studies (64%) use a broad variety of shortened versions of the TLS-45. Here, aiming to achieve scientific consensus and improve the reliability, comparability, and generalizability of results across studies, we developed a short version of the scale-the TLS-15-comprised of 15 items with 5-point, rather than 9-point, response scales. In Study 1 (N = 7,332), we re-analyzed secondary data from a large-scale multinational study that validated the original TLS-45 to establish whether the scale could be truncated. In Study 2 (N = 307), we provided evidence for the three-factor structure of the TLS-15 and its reliability. Study 3 (N = 413) confirmed convergent validity and test-retest stability of the TLS-15. Study 4 (N = 60,311) presented a large-scale validation across 37 linguistic versions of the TLS-15 on a cross-cultural sample spanning every continent of the globe. The overall results provide support for the reliability, validity, and cross-cultural invariance of the TLS-15, which can be used as a measure of love components-either separately or jointly as a three-factor measure.

Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e., a controlling message) compared with no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared with the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing. Controlled motivation was associated with more defiance and less long-term behavioral intention to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges.

Packed-bed thermocline tank with sensible fillers is a cost-effective option for thermal energy storage (TES). In real charging and discharging, the thermocline stability is disturbed and thermocline expansion occurs due to various factors, leading to the decreased global performances of storage tank. The purpose of this work is to experimentally and numerically study the impact of inlet configuration and insulation on the thermocline expansion in a lab-scale tank under various operating parameters. Firstly, a DC-3P model considering the wall effect and heat loss is developed and validated by experimental results, capable of precisely predicting the performance of storage tank under the tested conditions. Especially, the temperature difference between the fluid and solid filler center is detected both in experiments and in modeling, indicating the existence of temperature gradient inside large solid particles. Results also show that the injecting flow causes the radial temperature non-uniformity and thermocline expansion at the near-entrance region of the tank, but its effect on the global performance of the storage tank is rather limited. Good insulation of the tank could reduce the thermocline thickness by about 20%, and increase the energy efficiency and the capacity ratio by 5–7% and 3–5%, respectively.

During the onset of the COVID-19 pandemic, the COVIDiSTRESS Consortium launched an open-access global survey to understand and improve individuals' experiences related to the crisis. A year later, we extended this line of research by launching a new survey to address the dynamic landscape of the pandemic. This survey was released with the goal of addressing diversity, equity, and inclusion by working with over 150 researchers across the globe who collected data in 48 languages and dialects across 137 countries. The resulting cleaned dataset described here includes 15,740 of over 20,000 responses. The dataset allows cross-cultural study of psychological wellbeing and behaviours a year into the pandemic. It includes measures of stress, resilience, vaccine attitudes, trust in government and scientists, compliance, and information acquisition and misperceptions regarding COVID-19. Open-access raw and cleaned datasets with computed scores are available. Just as our initial COVIDiSTRESS dataset has facilitated government policy decisions regarding health crises, this dataset can be used by researchers and policy makers to inform research, decisions, and policy.

Background: Engineering cardiac tissue that mimics the hierarchical structure of cardiac tissue remains challenging, raising the need for developing novel methods capable of creating structures with high complexity. Three-dimensional (3D)-printing techniques are among promising methods for engineering complex tissue constructs with high precision. By means of 3D printing, this study aims to develop cardiac constructs with a novel angular structure mimicking cardiac architecture from alginate (Alg) and gelatin (Gel) composite. The 3D-printing conditions were optimized and the structures were characterized in vitro , with human umbilical vein endothelial cells (HUVECs) and cardiomyocytes (H9c2 cells), for potential cardiac tissue engineering. Methods: We synthesized the composites of Alg and Gel with varying concentrations and examined their cytotoxicity with both H9c2 cells and HUVECs, as well as their printability for creating 3D structures of varying fibre orientations (angular design). The 3D-printed structures were characterized in terms of morphology by both scanning electron microscopy (SEM) and synchrotron radiation propagation-based imaging computed tomography (SR-PBI-CT), and elastic modulus, swelling percentage, and mass loss percentage as well. The cell viability studies were conducted via measuring the metabolic activity of the live cells with MTT assay and visualizing the cells with live/dead assay kit. Results: Among the examined composite groups of Alg and Gel, two combinations with ratios of 2 to 1 and 3 to 1 (termed as Alg2Gel1 and Alg3Gel1) showed the highest cell survival; they accordingly were used to fabricate two different structures: a novel angular and a conventional lattice structure. Scaffolds made of Alg3Gel1 showed higher elastic modulus, lower swelling percentage, less mass loss, and higher cell survival compared to that of Alg2Gel1. Although the viability of H9c2 cells and HUVECs on all scaffolds composed of Alg3Gel1 was above 99%, the group of the constructs with the angular design maintained significantly more viable cells compared to other investigated groups. Conclusion: The group of angular 3D-ptinted constructs has illustrated promising properties for cardiac tissue engineering by providing high cell viability for both endothelial and cardiac cells, high mechanical strength as well as appropriate swelling, and degradation properties during 21 days of incubation. Statement of Significance: 3D-printing is an emerging method to create complex constructs with high precision in a large scale. In this study, we have demonstrated that 3D-printing can be used to create compatible constructs from the composite of Alg and Gel with endothelial cells and cardiac cells. Also, we have demonstrated that these constructs are able to enhance the viability of cardiac and endothelial cells via creating a 3D structure mimicking the alignment and orientation of the fibers in the native heart.

The purpose of this study is to evaluate and compare the ability of various composite structures to dissipate the energy generated during a crash. To this end, circular composite tubes were tested in compression in order to identify their behavior and determine their absorbing capabilities using the specific energy absorption (energy absorbed per unit weight). Several composite tubular structures with different materials and architectures were tested, including hybrid composition of carbon–aramid and hybrid configuration of 0/90 UD with woven or braided fabric. Several inventive and experimental trigger systems have been tested to try and enhance the absorption capabilities of the tested structures. Specific energy absorption values up to 140 kJ.kg −1 were obtained, achieving better than most instances from the literature, reaching around 80 kJ.kg −1 . Specimens with 0°-oriented fibers coincidental with the direction of compression reached the highest specific energy absorption values while those with no fiber oriented in this direction performed poorly. Moreover, it has consequently been established that in quasi-static loading, a unidirectional laminate oriented at 0° and stabilized by woven plies strongly meets the expectations in terms of energy dissipation. Incidentally, an inner constrained containment is more effective in most cases, reducing the initial peak load without drastically reducing the specific energy absorption value.

Over the past decade, machine learning (ML) and artificial intelligence (AI) have attracted great interest in research and various practical applications. Currently, smart, fast, and high sensitivity with excellent selectivity are becoming increasingly interesting due to the high need for environmental safety and medical applications. The main challenge is to improve sensor selectivity, which requires the combination of interdisciplinary research areas to successfully develop smart gas/chemical sensing devices with better performance. In this review, we present a few principles of gas sensing based on low-cost interdigital electrodes (IDEs), such as electrochemical, resistive, capacitive, and acoustic sensors. In addition, the most important current methods for improving gas sensing performance, the different materials, the different techniques used to fabricate IDE gas sensors, and their advantages and limitations are presented. In addition, a comparison between different ML and AI algorithms for pattern recognition and classification algorithms is also discussed. The discussion then establishes application cases of smart ML algorithms, which provide efficient data processing methods, for the design of smart gas sensors that are highly selective. In addition, the challenges and limitations of ML in gas sensor applications are critically discussed. The study shows the importance of ML with the need for structural optimization to develop and improve smart, sensitive, and selective sensors.

Microgrids technologies are seen as a cost effective and reliable solution to handle numerous challenges, mainly related to climate change and power demand increase. This is mainly due to their potential for integrating available on-site renewable energy sources and their flexibility and scalability. The particularity of microgrids is related to their capacity to operate in synchronization with the main grid or in islanded mode to secure the power supply of nearby end-users after a grid failure thanks to storage solutions and an intelligent control system. The most critical operating case occurs when a sudden transition from grid-connected (GC) to stand-alone operation (SA) happens. During the transition, the system experiences abrupt changes that can result in a malfunction of the control system and a possible failure of the power system. The transition issue attracted considerable attention from researchers. Indeed, many research works are proposed to address this issue by proposing detection and transition techniques that ensure a smooth transition at the islanding time. Although there are several approaches to dealing with this issue, a categorization of the proposed methods in the literature and their differences is useful to assist engineers and researchers working on this topic. Thus, this study proposes a comprehensive review to summarize these approaches and point out their advantages and limitations.

This paper introduces a novel energy management strategy incorporating stochastic elements designed for off-grid photovoltaic (PV) systems supplying multiple loads in environments marked by unpredictable power usage. In these PV microgrid applications, unpredictable power consumption can lead to discrepancies between energy supply and demand, compromising system reliability and efficiency. This issue is especially pertinent in providing reliable electricity to remote or rural areas where conventional grid infrastructure is not available or reliable. To overcome this challenge, this paper addresses the random variability in load consumption by modeling it as a Markov decision process (MDP). The MDP framework facilitates the development of an effective decision-making process, accounting for the probabilistic nature of energy consumption patterns. Furthermore, by integrating MDP-based load consumption prediction into the energy management system, real-time optimization of both PV power and battery charging and discharging within the microgrid is achieved. This integration balances energy production and consumption, enhancing overall system efficiency. Three scenarios were examined to evaluate the effectiveness of the suggested strategy in enhancing the real-time operation of off-grid PV systems: standard test conditions, time-varying climatic profiles, and real-time weather situations. The findings indicate that the proposed strategy can adapt to dynamic load profiles, ensuring efficient energy utilization while maintaining microgrid stability.

Abstract In this article, we are interested in analysing the stability of systems that incorporate time‐varying delays in their dynamic. The L yapunov‐ K rasovskii approach is definitely the most popular method to address this issue and many results have proposed new functionals and enhanced techniques for deriving less conservative stability conditions. In the present work, we propose an original approach: the quadratic separation. To this end, the delay operator properties are exploited to provide delay range stability conditions. In particular, L 2 ‐norm of delay‐dependent operators are computed so as to reduce the conservatism of the approach. Moreover, the main result is able to assess the stability of non‐small delay systems, i.e , it can detect a stability interval for systems that are unstable without any delay. Several examples illustrate the benefit of our methodology.

Summary In this paper, new sufficient stability conditions for the asymptotic stability of time‐delay systems are presented using the quadratic separation approach. The time‐delay system is modeled as an interconnected closed‐loop system involving a linear transformation and delay‐dependent functions, representing the uncertainties brought by the delay. Those complex‐valued functions are then embedded into adequate norm‐bounded uncertainties, which lead to several stability results. The novelty of this approach relies on the introduction of new dedicated functions that are built in accordance to the Bessel inequality. They allow us to model the system as an uncertain feedback system and to control the accuracy of the inequality. Then, a sequence of linear matrix inequality conditions is proposed, which tends to the analytical bounds for both delay‐dependent stability and delay range stability, at least on examples.

In the field of civil engineering, ground penetrating radar (GPR) is a highly efficient nondestructive testing tool for sustainable management of pavement infrastructures. GPR allows to evaluate the structure of the roadway over large distances (with contactless configurations) and to detect significant subsurface defects. This letter presents a new method to detect thin debondings within pavement structures with the step-frequency GPR. The proposed method enables us to carry out the detection with only a small number of frequency samples and A-scans. It is based on the linear prediction and support vector regression theories. Two experimental results show its effectiveness.

Given the ubiquitous nature of love, numerous theories have been proposed to explain its existence. One such theory refers to love as a commitment device, suggesting that romantic love evolved to foster commitment between partners and enhance their reproductive success. In the present study, we investigated this hypothesis using a large-scale sample of 86,310 individual responses collected across 90 countries. If romantic love is universally perceived as a force that fosters commitment between long-term partners, we expected that individuals likely to suffer greater losses from the termination of their relationships-including people of lower socioeconomic status, those with many children, and women-would place a higher value on romantic love compared to people with higher status, those with fewer children, and men. These predictions were supported. Additionally, we observed that individuals from countries with a higher (vs. lower) Human Development Index placed a greater level of importance on romantic love, suggesting that modernization might influence how romantic love is evaluated. On average, participants worldwide were unwilling to commit to a long-term romantic relationship without love, highlighting romantic love's universal importance.

Using a particular construction of generator matrices of the q-ary image of q/sup m/-ary cyclic codes, it is proved that some of these codes are invariant under the action of particular permutation groups. The equivalence of such codes with some two-dimensional (2-D) Abelian codes and cyclic codes is deduced from this property. These permutations are also used in the area of the soft-decision decoding of some expanded Reed-Solomon (RS) codes to improve the performance of generalized minimum-distance decoding.

This paper focuses on the modeling, analysis, and design of grid-forming (GFM) inverter-based microgrids (MGs). It starts with the development of a mathematical model for three-phase voltage source inverters (VSI). The voltage and current controllers consist of two feedback loops: an outer feedback loop of the capacitance-voltage and an inner feedback loop of the output inductance current. The outer voltage loop is employed to enhance the controller’s response time. The inner current loop is used to provide active damping for the resonance created by the LCL filter. A two-layer control scheme is adopted for the GFM inverter control. The primary decentralized control uses droop control and virtual impedance loops to share active and reactive power. Simultaneously, the centralized secondary control addresses frequency and amplitude deviations induced by the droop control. Additionally, a synchronization loop is proposed for seamless reconnection of GFM inverters to the MG and to connect the GFM-controlled MG to the main grid. It has the advantage that the inverter operates in GFM mode even after the synchronization has occurred. The simulation results have shown that the voltage controller ensures a 0.005 s settling time and maintains the steady-state error at its minimum value of 0.1 V. Similarly, the current controller ensures a 0.006 s settling time with a 10−5 steady-state error. The system with the designed controller has a low total harmonic distortion (THD) of 1.46% and improved power quality of the output voltage. Furthermore, a quick restoration time is observed during load steps and tripping events, with a restoration time of 1 s with 10−10 steady-state error. Synchronization is achieved within 0.8 s for the incoming inverters and requires 3 s to synchronize the MG with the main grid, maintaining a steady-state error of 10−9.

This research explores electrochemical correlations between heat‐affected zones (HAZs), produced by Gleeble © thermal simulation cycles, and their passivation behavior in bicarbonate–carbonate solutions. The investigations were carried out in comparison with the base API‐X100 steel in naturally aerated 0.5 g/L chloride solutions, containing a matrix of bicarbonate and carbonate concentrations at 298 K. The slow 0.05 mV/s potentiodynamic scans revealed that the passivation onsets earlier in proportion with the bicarbonate concentrations, possessing accordingly greater immunity against chloride ions on HAZs cooled at 10 and 60 K/s from 1223 K peak temperature. The HAZs cooled at 10 K/s, particularly in concentrated carbonate solutions, showed the most stable passivation, and the HAZs cooled at 60 K/s showed the lowest cathodic activity regardless of the chemical conditions. −0.1 V, versus saturated calomel electrode, potentiostatic currents and the open‐circuit potentials decreased and increased, respectively, with the carbonate concentration, confirming with the main potentiodynamic polarization results, and a corresponding passivation behavior of the HAZs, regardless of a bicarbonate–carbonate condition, was relatively similar. In contrary to the 60 K/s HAZs, the 10 K/s HAZs showed evidence of growing passive films with time and high charge‐transfer resistance, as measured by the EIS tests.