On the use of the eXtended Finite Element Method with Quatree/Octree meshes

International audienceThis paper describes the use of the eXtended Finite Element Method in the context of quadtree/octree meshes. Particular attention is paid on the enrichment of hanging nodes that inevitably arise with these meshes. An approach for enforcing displacement continuity along hanging edges and faces is proposed and validated on various numerical examples (holes, material interfaces and singularities) in both 2D and 3D

Chemo-Enzymatic Synthesis and Characterization of Renewable Thermoplastic and Thermoset Isocyanate-Free Poly(hydroxy)urethanes from Ferulic Acid Derivatives

International audienc

Maillage adaptatif octree dans l'environnement X-FEM et level-sets -Application à la thermique

International audienceLa modélisation par la méthode X-Fem et level-sets permet de s'affranchir de maillages conformes, amenant à utiliser des maillages structurés (octree/quadtree), plus faciles à mettre en oeuvre. L'objet de cette étude est donc la mise en place d'un algorithme de maillage octree adaptatif, avec un raffinement de type h. Les applications concernent des modèles bidimensionnels de thermique stationnaire (problèmes de conduction). Cet algorithme s'appuie sur un indicateur d'erreur basé sur la différence entre la solution courante et celle issue d'un maillage plus fin

Ferulic acid-based renewable esters and amides-containing epoxythermosets from wheat bran and beetroot pulp: Chemo-enzymaticsynthesis and thermo-mechanical properties characterization

International audienceIn this study, ferulic acid - a natural phenolic acid present in bagasse, wheat and rice brans, and beetroot pulp - was used as renewable starting material to prepare new biobased epoxy precursors. This biobased building block was first esterified then reduced to provide ethyl dihydroferulate which was then transesterified/amidified with biobased diols, triol and diamines. Immobilized Candida antarctica (aka CAL-B or Novozyme 435 (R)) was used to perform the solvent-free-transesterification/amidation under mild conditions. The phenolic architectures synthesized were then glycidylated using a TEBAC-mediated procedure to afford four biobased epoxy precursors- with various linker structures between the ferulic units which were then cured with conventionnal and biobased diamine curing agents. The thermal and thermomechanical properties of the thermosets prepared were assessed by TGA, DSC and DMA to highlight the influence of the linker configuration (aliphatic vs cycloaliphatic), that of the epoxy functionality (di vs tri), and that of the nature of the function used for coupling ferulic units (ester vs amide) on the thermosets properties. Analyses of these thermosets revealed glass transition temperatures ranging from 32 to 85 degrees C and high thermal stabilities around 300 degrees C. The mechanical behavior of the biobased thermosets proved equivalent to that of the DGEBA-IPDA reference sytem at low temperatures (up to 40-100 degrees C depending on the epoxy precursor and diamine)

Syringaresino l: a renewable and safer alternative to bisphenol A for epoxy-amine resins

A renewable bisepoxide, SYR-EPO, was prepared from syringaresinol, a naturally occurring bisphenol deriving from sinapic acid, by using a chemo-enzymatic synthetic pathway. Estrogenic activity tests revealed no endocrine disruption for syringaresinol. Its glycidylation afforded SYR-EPO with excellent yield and purity. This biobased, safe epoxy precursor was then cured with conventional and renewable diamines for the preparation of epoxy-amine resins. The resulting thermosets were thermally and mechanically characterized. Thermal analyses of these new resins showed excellent thermal stabilities (T-d5%=279-309 degrees C) and T-g ranging from 73 to 126 degrees C, almost reaching the properties of those obtained with the diglycidylether of bisphenol A (DGEBA), extensively used in the polymer industry (T-d5%= 319 degrees C and T-g = 150 degrees C for DGEBA/isophorone diamine resins). Degradation studies in NaOH and HCl aqueous solutions also highlighted the robustness of the syringaresinol-based resins, similar to bisphenol A (BPA). All these results undoubtedly confirmed the potential of syringaresinol as a greener and safer substitute for BP

Full-field evaluation of the onset of microplasticity in a steel specimen

This work deals with the study of the local onset of microplasticity in a steel specimen under tensile test through the use of a full-field strain measurement method at the micrometric scale. The kinematic measurements were performed by the so called grid method. In order to produce the gratings, direct interferential photolithography was used. The gratings were digitized through the use of a white-light interferometric microscope. An adapted image stitching algorithm, applied to the phase maps, has been developed and implemented in order to extend the size of the region of interest. With this method, and by paying a particular attention to the conduct of the mechanical tests, the strain resolution obtained ranges from 1 to 2 × 10?3 for a spatial resolution of about 20 ?m. In this paper, the method was applied to the study of the onset of local elasto-plastic strains in a ferritic steel coupon. The results show that the method is well suited to study small localized strains, for which few alternatives exist. To the best knowledge of the authors, it is the first time that white-light interferometric microscopy is used to measure full-field strains. The technique is reasonably easy to set up although a number of limitations exist. The paper is concluded by some considerations about further work required to extend the range of applicability of the metho

Massive detection of cryptic recessive genetic defects in cattle mining millions of life histories

Abstract We present a data-mining framework designed to detect recessive defects in livestock that have been previously missed due to a lack of specific signs, incomplete penetrance, or incomplete linkage disequilibrium. This approach leverages the massive data generated by genomic selection. Its basic principle is to compare the observed and expected numbers of homozygotes for sliding haplotypes in animals with different life histories. Within three cattle breeds, we report 33 new loci responsible for increased risk of juvenile mortality and present a series of validations based on large-scale genotyping, clinical examination, and functional studies for candidate variants affecting the NOA1 , RFC5, and ITGB7 genes. In particular, we describe disorders associated with NOA1 and RFC5 mutations for the first time in vertebrates. The discovery of these many new defects will help to characterize the genetic basis of inbreeding depression, while their management will improve animal welfare and reduce losses to the industry.Nous présentons un cadre d'exploration de données conçu pour détecter les défauts récessifs chez le bétail qui n'ont pas été détectés auparavant en raison d'un manque de signes spécifiques, d'une pénétrance incomplète ou d'un déséquilibre de liaison incomplet. Cette approche tire parti des données massives générées par la sélection génomique. Son principe de base est de comparer les nombres observés et attendus d'homozygotes pour des haplotypes glissants chez des animaux ayant des histoires de vie différentes. Au sein de trois races bovines, nous rapportons 33 nouveaux loci responsables d'un risque accru de mortalité juvénile et présentons une série de validations basées sur le génotypage à grande échelle, l'examen clinique et des études fonctionnelles pour des variants candidats affectant les gènes NOA1, RFC5 et ITGB7. En particulier, nous décrivons pour la première fois chez les vertébrés des troubles associés à des mutations des gènes NOA1 et RFC5. La découverte de ces nombreux nouveaux défauts aidera à caractériser la base génétique de la dépression de consanguinité, tandis que leur gestion améliorera le bien-être des animaux et réduira les pertes pour l'industrie

Analysis of Polycerate Mutants Reveals the Evolutionary Co-option of HOXD1 for Horn Patterning in Bovidae

In the course of evolution, pecorans (i.e. higher ruminants) developed a remarkable diversity of osseous cranial appendages, collectively referred to as 'headgear', which likely share the same origin and genetic basis. However, the nature and function of the genetic determinants underlying their number and position remain elusive. Jacob and other rare populations of sheep and goats are characterized by polyceraty, the presence of more than two horns. Here, we characterize distinct POLYCERATE alleles in each species, both associated with defective HOXD1 function. We show that haploinsufficiency at this locus results in the splitting of horn bud primordia, likely following the abnormal extension of an initial morphogenetic field. These results highlight the key role played by this gene in headgear patterning and illustrate the evolutionary co-option of a gene involved in the early development of bilateria to properly fix the position and number of these distinctive organs of Bovidae