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Optimization and analytical modelling of sustainable composite materials
No full textInternational audienceThis research work aims to study the flexural and compressive behavior of esparto and jute natural fiber–reinforced composites and to investigate the influence of certain critical factors, in particular the nature, length, and ratio of fibers introduced in the cementitious matrix. The mortar matrix has a fragile character, whereas fiber-based mortar exhibits ductile behavior. The incorporation of the fibers avoids brittle breakage of the composite material and induces a more resilient behavior. The breaking energy of all fiber-reinforced mortars is significantly higher than that of non-reinforced cement mortar. This result is very interesting and clearly shows the interest of using these fibers in the new composites proposed. On the other hand, a comparison of the mechanical properties of these new formulated materials with those reinforced by glass fibers was conducted. Sustainable natural fibers outperform glass fibers in composite applications, delivering superior fracture energy absorption. Therefore, the biodegradable natural fibers employed in this study have a promising potential to replace synthetic fibers characterized by a high carbon footprint. Thus, thanks to these fibers, we can produce sustainable and eco-friendly products while ensuring very good mechanical properties. In fact, the response of fiber-reinforced mortar to compressive test reveals that for a constant fiber rate, the compressive strength increases proportionally with the fiber length, whereas, for a constant fiber length, the compressive strength increases when fiber content passes from 1 to 2% and then it decreases at 3%. The bending resistance reaches its maximum (2.83 MPa) for an esparto fiber length equal to 10 mm, while a length of 25 mm of glass fiber leads to a flexural resistance equal to 2.055 MPa. Compressive strain value is maximum (2.8 MPa) for a fiber ratio equal to 2% case of esparto fiber and decreases when fibers are added up to 3%. The same result was obtained for mortars reinforced with jute fibers. A detailed statistical investigation thanks to ANOVA tool was conducted in order to determine the effect of parameters on composite mechanical performances. This research proved that the most influencing parameters on the flexural and compressive resistance properties are nature and length of fibers. Concerning compressive modulus, it was shown that fiber ratio is the most impacting parameter. In addition, a process optimization was proposed. Moreover, laws of evolution of the physical parameters especially the elastic modulus and the strain at peak stress were suggested via an analytical model so as to simulate the response of mortars reinforced by natural reinforcements. The main result of this research showed the promising potential of using esparto and jute fibers to produce sustainable construction materials with good mechanical properties and low cost
Haptic Training Simulators in medical education
No full textInternational audienceThe use of simulators based on virtual reality and haptic techniques for training medical gestures can offer a solution for acquiring the necessary dexterity without posing any risk to patients. However, the development of such simulators necessitates a multidisciplinary approach and extensive work, spanning from analyzing practice and training gestures to technically designing the simulator and validating it from a didactic standpoint. This chapter, drawing upon the expertise of various researchers in mechatronics, computer graphics, and didactics, addresses these points to propose a global iterative process to help design Haptic Training Simulators
Physical activity, vaso‐occlusive crises and pain in patients with sickle cell anaemia in Senegal
No full textInternational audienceAcute physical exercise may trigger vaso-occlusive crises (VOC) in patients with sickle cell anaemia (SCA), creating uncertainty around physical activity (PA) recommendations. This cross-sectional study examined the relationships between PA, VOC and steady-state pain in 104 Senegalese male patients with SCA. PA was objectively measured over 5 weeks, recording daily steps and time spent in different PA intensities (expressed in metabolic equivalent of task, MET). VOC occurrence was tracked, and steady-state days excluded VOC days plus 2 days before and after. Pain frequency and intensity on steady-state days were recorded via diaries, and blood viscosity was measured. Ninety-eight patients (29 ± 8 years old) completed the study, averaging 9611 ± 4040 steps/day, with 293 ± 108, 64 ± 69 and 28 ± 32 min in ≥1.5, ≥3.0, and ≥6.0 MET PA respectively. Median daily step count and PA duration were not associated with VOC occurrence. However, higher step counts and more time in ≥1.5 and ≥6.0 MET PA correlated with lower pain frequency and intensity (on steady-state days) and lower blood viscosity. These findings suggest that PA may benefit patients with SCA, but further research is needed to establish guidelines
NanoASV: A snakemake workflow for reproducible field-based Nanopore full-length 16S metabarcoding amplicon data analysis
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/614056/)International audienceNanoASV is a conda environment and snakemake-based workflow using state-of-the-art bioinformatics software to process full-length SSU rRNA (16S/18S) amplicons acquired with Oxford Nanopore Sequencing technology. Its strength lies in reproducibility, portability, and the possibility to run offline, allowing in-field analysis. It can be installed on the Nanopore MK1C sequencing device and process data locally
Arabidopsis SGS3 is recruited to chromatin by CHR11 to select RNA that initiate siRNA production
No full textInternational audienceIn plants, aberrant RNAs produced by endogenous genes or transgenes are normally degraded by the nuclear and cytosolic RNA quality control (RQC) pathways. Under certain biotic or abiotic stresses, RQC is impaired, and aberrant RNAs are converted into siRNAs that initiate post-transcriptional gene silencing (PTGS) in the cytosol. How aberrant RNAs are selected and brought to the cytoplasm is not known. Here we show that the RNA-binding protein SUPPRESSOR OF GENE SILENCING (SGS)3 shuttles between the cytosol and the nucleus where it associates with the ISWI-like CHROMATIN REMODELER (CHR)11 and with RNAs transcribed from PTGS-sensitive transgene loci binding CHR11. Knocking down CHR11 and its paralog CHR17 strongly reduces transgene PTGS, suggesting that SGS3 recruitment by CHR11/17 facilitates PTGS initiation. CHR11 is also enriched at endogenous protein-coding genes (PCGs) producing nat-siRNAs and va-siRNAs under biotic or abiotic stresses, and this production is reduced in chr11 chr17 double mutants at genome-wide level. Moreover, impairing CHR11 and CHR17 rescues the lethal phenotype caused by the massive production of siRNAs from PCGs in RQC-deficient mutants. We propose that SGS3 recruitment by CHR11/17 allows exporting RNAs to the cytosol to initiate the production of siRNAs
Magnetotactic bacteria affiliated with diverse <i>Pseudomonadota</i> families biomineralize intracellular Ca-carbonate
No full textInternational audienceIntracellular calcium carbonate formation has long been associated with a single genus of giant Gammaproteobacteria, Achromatium. However, this biomineralization has recently received increasing attention after being observed in photosynthetic Cyanobacteriota and in two families of magnetotactic bacteria affiliated with the Alphaproteobacteria. In the latter group, bacteria form not only intracellular amorphous calcium carbonates into large inclusions that are refringent under the light microscope, but also intracellular ferrimagnetic crystals into organelles called magnetosomes. Here new observations suggest that magnetotactic bacteria previously identified in the sediments and water column of Lake Pavin (France) were only a small fraction of the diversity of bacteria producing intracellular amorphous calcium carbonates. To explore this diversity further, we conducted a comprehensive investigation of magnetotactic populations with refractive granules using a combination of environmental microbiology, genomic and mineralogy approaches on cells sorted by micromanipulation. Several species belonging to divergent genera of two Pseudomonadota classes were identified and characterized. Scanning transmission electron microscopy coupled with energy-dispersive X-ray spectrometry support that all these species indeed form intracellular amorphous calcium carbonates. Cryo soft X-ray tomography experiments conducted on ice-vitrified cells, enabled 3D investigation of inclusions volume, which was found to occupy 44-68% of the cell volume. Metabolic network modeling highlighted different metabolic abilities of Alpha-and Gammaproteobacteria, including methylotrophy and CO 2 fixation via the reverse Krebs cycle or the Calvin-Benson-Bassham cycle. Overall, this study strengthens a convergent evolution scenario for intracellular carbonatogenesis in Bacteria, and further supports that it is promoted by the fixation of CO 2 in anoxic environments.</div
Boosting photosynthesis opens new opportunities for agriculture sustainability and circular economy: The BEST ‐ CROP research and innovation action
No full textInternational audienceThere is a need for ground‐breaking technologies to boost crop yield, both grains and biomass, and their processing into economically competitive materials. Novel cereals with enhanced photosynthesis and assimilation of greenhouse gasses, such as carbon dioxide and ozone, and tailored straw suitable for industrial manufacturing, open a new perspective for the circular economy. Here we describe the vision, strategies, and objectives of BEST‐CROP, a Horizon‐Europe and United Kingdom Research and Innovation (UKRI) funded project that relies on an alliance of academic plant scientists teaming up with plant breeding companies and straw processing companies to use the major advances in photosynthetic knowledge to improve barley biomass and to exploit the variability of barley straw quality and composition. We adopt the most promising strategies to improve the photosynthetic properties and ozone assimilation capacity of barley: (i) tuning leaf chlorophyll content and modifying canopy architecture; (ii) increasing the kinetics of photosynthetic responses to changes in irradiance; (iii) introducing photorespiration bypasses; (iv) modulating stomatal opening, thus increasing the rate of carbon dioxide fixation and ozone assimilation. We expect that by improving our targeted traits we will achieve increases in aboveground total biomass production without modification of the harvest index, with added benefits in sustainability via better resource‐use efficiency of water and nitrogen. In parallel, the resulting barley straw is tailored to: (i) increase straw protein content to make it suitable for the development of alternative biolubricants and feed sources; (ii) control cellulose/lignin contents and lignin properties to develop straw‐based construction panels and polymer composites. Overall, by exploiting natural‐ and induced‐genetic variability as well as gene editing and transgenic engineering, BEST‐CROP will lead to multi‐purpose next generation barley cultivars supporting sustainable agriculture and capable of straw‐based applications
Que pensent les Françaises et les Français du cannabis ? Facteurs associés a la perception de la légalisation du cannabis: Note de synthèse sur les résultats français de l’international social survey programme sante
No full textForce vs. Illusion: Realism, Cost, and Satisfaction
No full textInternational audienceThis research investigates the realism of virtual touch through hap- tic devices, comparing high-fidelity haptic feedback (force-based) with pseudo-haptics (visual illusions of touch) in the context of training. This preliminary study involves the design and devel- opment of a virtual reality (VR) prototype, and an experimental evaluation in which participants performed an object manipulation task under two conditions (force feedback and visuo-haptics feed- back) to assess weight estimation and self-performance. Results show that haptic feedback enhances realism and presence in VR, but pseudo-haptic feedback offers a cost-effective alternative for less precision-critical tasks, with potential for refinement
Towards a Better Control of Engineered Circuit Transcription in Bacterial Genomes
No full textInternational audienceThe transcription of genes and engineered circuits can deeply vary when inserted into different genomic loci. This unpredictable performance, termed context sensitivity, complicates strain development. Although the causes and mechanisms of context sensitivity are emerging, it is poorly known how to engineer circuits and synthetic pathways isolated from it. Using tools of synthetic biology for designing and inserting various reporter cassettes in the Escherichia coli genome and RT-qPCR for directly measuring gene transcription, we first surveyed the genomic landscape for context sensitivity at 214 positions in cells grown in glucose or glycerol. The results show deep variations in cassette transcription with respect to position (up to 160-fold) and growth condition (up to a 30-fold). We then demonstrated that this position-dependent transcription variability is strongly reduced when the reporter cassette is insulated in an artificial protein-bound DNA loop. Finally, we measured the transcription of two loop-insulated genes at different genomic positions. The results show that transcription strongly depends on the relative orientation of the genes, promoter strength, and positive supercoiling. We present a model suggesting that DNA looping is an important cause of context sensitivity and can be used for better controlling the transcription of engineered circuits