Laboratoire Interdisciplinaire des Énergies de Demain

Acoustic streaming in a sharp edge pattern channel provides an effective approach for particle manipulation in microfluidics. In this study, the flow dynamics of sharp edge acoustic streaming are first analyzed. Then, the forces acting on particles inside the channel are evaluated to identify the key mechanisms of particle manipulation. A periodic flow of controlled amplitude att frequency = 500 Hz is prescribed within the channel, in the longitudinal direction. Experiments with particles of three diameters (d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> = 1.1 µm, 5.0 µm and 10.1 µm) revealed that the larger particles d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> = 10.1 µm and d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> = 5.0 µm are concentrated near the sharp edge region where strong vortices are present, with faster collection for larger sizes. In contrast, smaller particles d<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</inf> = 1.1 µm could not be collected under the same conditions. These findings demonstrate the potential feasibility of low frequency sharp edge acoustic streaming for size-selective particle manipulation.

Abstract In response to the complex nonlinear characteristics of magnetorheological (MR) dampers, which make it difficult to achieve strict vibration reduction requirements in time-varying working environments due to uncertainties, this paper aims to develop a refined model for the MR damper and improve the deep reinforcement learning network based on its dynamic characteristics to optimize the control strategy. Firstly, a refined dynamic model for the MR damper is designed, and its Simulink model is established and corrected based on the characteristic data of the custom damper. Secondly, an optimization framework for suspension control is constructed, where the suspension and road surface serve as the environment, and the proximal policy optimization (PPO) algorithm is used as the agent. Next, the nonlinear relationship between the damping force of the damper and its performance indicators is explored, and a PPO-neural ordinary differential equations (NODEs) algorithm is proposed by combining NODE with PPO. This approach allows for continuous fitting of state variables, enabling high-precision nonlinear fitting between the state space and policy representation. Finally, a quarter-car test bench is set up using the custom MR damper, and the simulation and experimental results of passive suspension, fuzzy PID, original PPO, and the proposed method are compared. The experimental results show that the proposed method demonstrates significant advantages: under class C road conditions, the body acceleration in simulation and test bench experiments is reduced by 30.22% and 77.51% respectively compared to passive suspension; 20.55% and 37.82% compared to fuzzy PID; and 11.26% and 25.53% compared to the original PPO. Additionally, the simulation results on Class B random road further validate the good generalization performance of the proposed method.

The urban climatology community has been structured internationally at different levels for several years with venues such as ICUC, AGU, EGU or IC2UHI which regularly bring together different members of academia addressing urban climate-related research and engineering challenges from different disciplines, countries and perspectives. Late 2018, a series of meetings of the French community were launched. Two in-person meetings occurring in Paris, France in early and late 2019, bringing together 30-40 academics from different French research groups and universities across the country.During the COVID-19 pandemic and lockdown episodes, networking and research sharing took place in the form of a series of online webinars in 2021 offered a venue for young researchers to present their work to their peers and research community. In-person meetings took place once again starting in 2022. Building on the community’s engagement and interest, the research network began formalizing its existence and organization, currently structured into four thematic groups focused on:numerical modeling field observations knowledge transfer for operational applications teaching and public dissemination of scientific and technical information The community currently comprises around 150 members from 50+ different research institutes, as well as the public (government agencies), private (startups and SMEs) and local government (municipalities, urban planning agencies, …) sectors. These members are involved in work spanning a wide range of disciplines from the technical, natural and human and social sciences and conducted at a variety of spatial scales ranging from urban materials to the regional scale (“nano”, “indoor”, micro, local and meso-scale climates) and focusing on the study of urban climate: from fundamental science to climate change adaptation solutions.The proposed contribution will present the network, its membership as well as work undertaken by its thematic groups, including a literature review of radiation shields.

Dew Water Harvesting by Laser Micropatterning A metallic surface micropatterned with a laser achieves self-cooling capacity when it faces the night sky thanks to its enhanced infrared emissivity, which triggers water condensation similar to natural dew on leaves. The patterned microgrooves promote condensation as a continuous film rather than dispersed droplets, enabling an efficient and autonomous harvesting of dew water. More details ban be found in article number 2419472 by Pablo Pou-Álvarez and co-workers.

Abstract Recombination suppression often evolves around sex-determining loci and extends stepwise, resulting in adjacent regions with different levels of divergence between sex chromosomes, called evolutionary strata. In Ascomycota fungi, evolutionary strata have been found around the mating-type (MAT) locus only in pseudo-homothallic species,i.e., with a diploid-like lifecycle and mycelia carrying nuclei of both mating types. In contrast, no recombination suppression has been observed in fungi with a haploid-like lifecycle, such as heterothallic fungi (with mycelial colonies of a single mating type each). Here, we investigated the evolution of recombination suppression in a clade of dung fungi encompassing 16 pseudo-homothallic and three heterothallic sibling species from theSchizotheciumgenus (Ascomycota, Sordariales). The analysis of genetic divergence based on genome sequencing indicated recombination suppression around theMATlocus in all investigated 13 pseudo-homothallic species. The non-recombining region ranged from 600 kb to 1.6 Mb and harbored multiple evolutionary strata, varying in size and number among species. The separation of alleles associated with alternative mating types in gene genealogies across strains within species, the high linkage disequilibrium and an inversion in one species supported the lack of recombination in theMAT-proximal region in pseudo-homothallic species. The overall lack of trans-specific polymorphism suggested multiple independent events of recombination suppression or the occurrence of rare events of recombination or genic conversion. Progeny analyses showed the occurrence of recombination close to theMATlocus in heterothallic strains. We thus revealed here multiple and likely independent evolutionary strata, associated with an extended diploid-like stage inSchizotheciumfungi, which provides a good model for research on sex-related chromosome evolution.

Abstract. Wildfires are among the most influential disturbances affecting ecosystem structure and biogeochemical cycles in Siberia. Therefore, accurate fire modeling via dynamic global vegetation models is important for predicting greenhouse gas emissions and other biomass-burning emissions to understand changes in biogeochemical cycles. We integrated the widely used SPread and InTensity of FIRE (SPITFIRE) fire module into the spatially explicit individual-based dynamic global vegetation model (SEIB-DGVM) to improve the accuracy of fire predictions and then simulated future fire regimes to better understand their impacts. The model can reproduce the spatiotemporal variation in biomass, fire intensity, and fire-related emissions well compared to the recent satellite-based estimations: aboveground biomass (R2=0.847, RMSE =18.3 Mg ha−1), burned fraction (R2=0.75, RMSE=0.01), burned area (R2=0.609, RMSE =690 ha), dry-matter emissions (R2=0.624, RMSE =0.01 kg DM m−2; dry matter), and CO2 emissions (R2=0.705, RMSE =6.79 Tg). We then predicted that all of the 33 fire-related gas and aerosol emissions would increase in the future due to the enhanced amount of litter as fuel load from increasing forest biomass production under climate forcing of four Representative Concentration Pathways: RCP8.5, RCP6.0, RCP4.5, and RCP2.6. The simulation under RCP8.5 showed that the CO2, CO, PM2.5, total particulate matter (TPM), and total particulate carbon (TPC) emissions in Siberia in the present period (2000–2020) will increase relatively by 189.66±6.55, 15.18±0.52, 2.47±0.09, 1.87±0.06, and 1.30±0.04 Tg species yr−1, respectively, in the future period (2081–2100) and the number of burned trees will increase by 100 %, resulting in a 385.19±40.4 g C m−2 yr−1 loss of net primary production (NPP). Another key finding is that the higher litter moisture by higher precipitation would relatively suppress the increment of fire-related emissions; thus the simulation under RCP8.5 showed the lowest emissions among RCPs. Our study offers insights into future fire regimes and development strategies for enhancing regional resilience and for mitigating the broader environmental consequences of fire activity in Siberia.

Abstract Sex chromosomes and mating-type chromosomes can carry large regions with suppressed recombination. As a result of a lower efficacy of selection, recessive deleterious mutations are expected to accumulate in these non-recombining regions. Multiple genomic analyses have indirectly inferred the presence of deleterious mutations in sex and mating-type chromosomes, but direct experimental evidence remains scarce. Here, we performed fitness assays in fungi with megabase-large and young non-recombining regions around the mating-type locus, using three Sordariales species, to test whether heterokaryons (diploid-like, heterozygous at the mating-type locus) exhibited a fitness advantage over homokaryons (haploid-like, with a single mating-type allele), in terms of spore germination dynamics or mycelium growth speed, under different conditions of light and temperature. We found a faster growth of heterokaryons compared to one of the homokaryons forPodospora anserinaat 18°C and forSchizothecium tetrasporumandSchizothecium tritetrasporumat 22°C under light. These findings suggest the presence of a sheltered load, i.e., recessive deleterious mutations at the heterozygous state in or near non-recombining regions, associated to a specific mating-type allele. Genomic analyses indeed suggested that the non-recombining regions around the mating-type locus likely carries heterozygous deleterious mutations, while the rest of the genome was mostly homozygous. We also showed that the difference in growth rates did not result from different numbers or densities of nuclei between homokaryons and heterokaryons. Leveraging the experimental assets of fungi, allowing cultivating separately haploid-like and diploid-like life stages, our experiments provided one of the rare direct experimental evidence of sheltered load around mating-compatibility loci, which is crucial for our understanding of sex-related chromosome evolution.Social Media AbstractExperimental evidence for sheltered load around the mating-type locus in filamentous fungi: slower growth of haploid versus diploid-like mycelia, revealing recessive deleterious mutations, inPodospora anserinaand other Sordariales fungi.

In order to adapt to climate change, cities are studying various urban cooling techniques to improve&amp;#160;pedestrian thermal comfort of users during heatwaves including urban greening and cool materials [1,2]. On&amp;#160;technique being considered by the City of Paris is cool pavements [3] . To this aim, an experimental test site&amp;#160;has been constructed and instrumented to study the thermal and climatic behavior of candidate sidewalk&amp;#160;structures.The experimental demonstrator is located in Bonneuil-sur-Marne near Paris, France. This experimental&amp;#160;device consists of 16 samples of various sidewalk structures [4]. Each sample is approximately 4x4m across&amp;#160;by 25 cm deep and is composed of several layers following real-world conditions. The samples are&amp;#160;instrumented with temperature and heat flow sensors at several depths, with the data recorded every 5&amp;#160;minutes. Additional weather measurements are also conducted onsite to monitor air temperature and&amp;#160;humidity, global horizontal short- and longwave irradiance as well as wind speed and direction.&amp;#160;This communication is focused on data collected during the summers of 2021 and 2022, specifically&amp;#160;temperatures and heat fluxes and the derived surface heat budget of each sample. These data from each&amp;#160;strcture will be analyzed with respect to their contribution to the degradation of pedestrian thermal comfort&amp;#160;as well as to the urban heat island effect in order to inform the city services in their selection of suited&amp;#160;sidewalk materials.&amp;#160;Additional testing inside a climate chamber will supplement the demonstrator test site with complementary&amp;#160;measurements performed in the laboratory.&amp;#160;

Programmed cell death (PCD) is a fundamental process in plants, involved in plant development and mediating abiotic and biotic environmental interactions (Kacprzyk et al., 2011, Locato & De Gara, 2018). While our understanding of genetic regulation of plant PCD, and the sequence of molecular events involved, is still relatively fragmented, the potential of PCD research to inform development of future-proofed crop cultivars is increasingly recognized. This Research Topic compiles valuable contributions that highlight the increasing momentum of this research area, and reports the use of a diversity of approaches for studying cell death in plants.

Metabolism and mechanics are two key facets of structural and functional processes in cells, such as growth, proliferation, homeostasis and regeneration. Their reciprocal regulation has been increasingly acknowledged in recent years: external physical and mechanical cues entail metabolic changes, which in return regulate cell mechanosensing and mechanotransduction. Since mitochondria are pivotal regulators of metabolism, we review here the reciprocal links between mitochondrial morphodynamics, mechanics and metabolism. Mitochondria are highly dynamic organelles which sense and integrate mechanical, physical and metabolic cues to adapt their morphology, the organization of their network and their metabolic functions. While some of the links between mitochondrial morphodynamics, mechanics and metabolism are already well established, others are still poorly documented and open new fields of research. First, cell metabolism is known to correlate with mitochondrial morphodynamics. For instance, mitochondrial fission, fusion and cristae remodeling allow the cell to fine-tune its energy production through the contribution of mitochondrial oxidative phosphorylation and cytosolic glycolysis. Second, mechanical cues and alterations in mitochondrial mechanical properties reshape and reorganize the mitochondrial network. Mitochondrial membrane tension emerges as a decisive physical property which regulates mitochondrial morphodynamics. However, the converse link hypothesizing a contribution of morphodynamics to mitochondria mechanics and/or mechanosensitivity has not yet been demonstrated. Third, we highlight that mitochondrial mechanics and metabolism are reciprocally regulated, although little is known about the mechanical adaptation of mitochondria in response to metabolic cues. Deciphering the links between mitochondrial morphodynamics, mechanics and metabolism still presents significant technical and conceptual challenges but is crucial both for a better understanding of mechanobiology and for potential novel therapeutic approaches in diseases such as cancer. This article is protected by copyright. All rights reserved.