Etude expérimentale et analyse probabiliste du comportement à la rupture en traction de composites verre-perlon-acrylique à usage orthopédique

Les effets de la nature des séquences de la stratification ainsi que les influences significatives du sens de découpe des échantillons par rapport au sens du flux de moulage sur le comportement mécanique en traction d’une série de matériaux composites stratifiés sont mises en évidence à partir d’une analyse de leurs propriétés mécaniques. Ces stratifiés à usage orthopédique et à base de résine acrylique renforcée de couches de fibres de verre et de perlon sont disposées selon trois différentes architectures. Une importante dispersion est observée sur les résultats de mesure du module de Young et des contraintes à la rupture. Ces dernières montrent des valeurs supérieures dans le sens perpendiculaire à celui du flux de moulage. La mesure de la fragilité, la caractérisation du comportement à la rupture de ces stratifiés ainsi que l’aspect probabiliste de cette dernière sont décrits quantitativement à partir de l’application du modèle probabiliste à deux paramètres de Weibull. Le caractère fragile de la rupture de ces stratifiés est ainsi traduit par les faibles valeurs mesurées des modules de Weibull. Un constat des principaux mécanismes responsables de la rupture est dressé à partir des observations microscopiques des faciès de rupture des éprouvettes rompues.Mots clés: Stratification – Fibre De Verre – Perlon – Dispersion – Module De WeibullExperimental study and probabilistic analysis of the tensile fracture behavior of glass-perlon-acrylic reinforced composites for orthopedic useThe effects of the nature of the stacking sequences and the significant influences of the samples cutting direction compared with the moulding flux on the tensile mechanical behavior of a set of laminated composite materials have been evidenced through analyses of their mechanical properties. These laminated composite materials for orthopedic uses containing acrylic resin reinforced with layers of glass and perlon fibres are arranged in three differents architectures. A significant scatter is observed on the measurement results of the Young modulus and of the fracture strengths. These latters show higher values in the perpendicular direction to the moulding flux. The brittleness measurement, the characterization of the fracture behavior of these laminates and the probabilistic fracture aspect are quantitatively described through the use of the probabilistic two parameters Weibull model. The brittle fracture character of these laminates is therefore described by the small measured values of Weibull modulus. A listing of the principal mechanisms responsible of the fracture is established according to microscopic observations of the fracture facies of the fractured samples. Keywords: Laminated - Glass Fiber - Perlon - Scatter – Modulus Of Weibul

Accumulation of copy-back viral genomes during respiratory syncytial virus infection is preceded by diversification of the copy-back viral genome population followed by selection

RNA viruses generate nonstandard viral genomes during their replication, including viral genomes of the copy-back (cbVGs) type that cannot replicate in the absence of a standard virus. cbVGs play a crucial role in shaping virus infection outcomes due to their ability to interfere with virus replication and induce strong immune responses. However, despite their critical role during infection, the principles that drive the selection and evolution of cbVGs within a virus population are poorly understood. As cbVGs are dependent on the virus replication machinery to be generated and replicated, we hypothesized that host factors that affect virus replication exert selective pressure on cbVGs and drive their evolution within a virus population. To test this hypothesis, we used respiratory syncytial virus (RSV) as a model and took an experimental evolution approach by serially passaging RSV in immune-competent human lung adenocarcinoma A549 control and immune-deficient A549 Signal transducer and activator of transcription 1 (STAT1) KO cells, which allow higher levels of virus replication. As predicted, we observed that virus populations accumulated higher amounts of cbVGs in the more permissive A549 STAT1 KO cells over time; however, unexpectedly, the predominant cbVG species after passages in the two conditions were different. While A549 STAT1 KO cells accumulated relatively short cbVGs, A549 control cells mainly contained cbVGs of much longer predicted size, which have not been described previously. These long cbVGs were predominant at first in both cell line

VODKA2: A fast and accurate method to detect non-standard viral genomes from large RNA-seq data sets

During viral replication, viruses carrying an RNA genome produce non-standard viral genomes (nsVGs), including copy-back viral genomes (cbVGs) and deletion viral genomes (delVGs), that play a crucial role in regulating viral replication and pathogenesis. Because of their critical roles in determining the outcome of RNA virus infections, the study of nsVGs has flourished in recent years, exposing a need for bioinformatic tools that can accurately identify them within next-generation sequencing data obtained from infected samples. Here, we present our data analysis pipeline, Viral Opensource DVG Key Algorithm 2 (VODKA2), that is optimized to run on a parallel computing environment for fast and accurate detection of nsVGs from large data sets

OPA1 functions in mitochondria and dysfunctions in optic nerve

OPA1 is the major gene responsible for Dominant Optic Atrophy (DOA), a blinding disease that affects specifically the retinal ganglion cells (RGCs), which function consists in connecting the neuro-retina to the brain. OPA1 encodes an intra-mitochondrial dynamin, involved in inner membrane structures and ubiquitously expressed, raising the critical question of the origin of the disease pathophysiology. Here, we review the fundamental knowledge on OPA1 functions and regulations, highlighting their involvements in mitochondrial respiration, membrane dynamic and apoptosis. In light of these functions, we then describe the remarkable RGC mitochondrial network physiology and analyse data collected from animal models expressing OPA1 mutations. If, to date RGC mitochondria does not present any peculiarity at the molecular level, they represent possible targets of numerous assaults, like light, pressure, oxidative stress and energetic impairment, which jeopardize their function and survival, as observed in OPA1 mouse models. Although fascinating fields of investigation are still to be addressed on OPA1 functions and on DOA pathophysiology, we have reached a conspicuous state of knowledge with pertinent cell and animal models, from which therapeutic trials can be initiated and deeply evaluated

Structure of 13^{13}Be probed via secondary beam reactions

The low-lying level structure of the unbound neutron-rich nucleus $^{13}$Be has been investigated via breakup on a carbon target of secondary beams of $^{14,15}$B at 35 MeV/nucleon. The coincident detection of the beam velocity $^{12}$Be fragments and neutrons permitted the invariant mass of the $^{12}$Be+$n$ and $^{12}$Be+$n$+$n$ systems to be reconstructed. In the case of the breakup of $^{15}$B, a very narrow structure at threshold was observed in the $^{12}$Be+$n$ channel. Contrary to earlier stable beam fragmentation studies which identified this as a strongly interacting $s$-wave virtual state in $^{13}$Be, analysis here of the $^{12}$Be+$n$+$n$ events demonstrated that this was an artifact resulting from the sequential-decay of the $^{14}$Be(2$^+$) state. Single-proton removal from $^{14}$B was found to populate a broad low-lying structure some 0.70 MeV above the neutron-decay threshold in addition to a less prominent feature at around 2.4 MeV. Based on the selectivity of the reaction and a comparison with (0-3)$\hbar\omega$ shell-model calculations, the low-lying structure is concluded to most probably arise from closely spaced J$^\pi$=1/2$^+$ and 5/2$^+$ resonances (E$_r$=0.40$\pm$0.03 and 0.85$^{+0.15}_{-0.11}$ MeV), whilst the broad higher-lying feature is a second 5/2$^+$ level (E$_r$=2.35$\pm$0.14 MeV). Taken in conjunction with earlier studies, it would appear that the lowest 1/2$^+$ and 1/2$^-$ levels lie relatively close together below 1 MeV.Comment: 14 pages, 13 figures, 2 tables. Accepted for publication in Physical Review

Prolate-Spherical Shape Coexistence at N=28 in 44^{44}S

The structure of $^{44}$S has been studied using delayed $\gamma$ and electron spectroscopy at \textsc{ganil}. The decay rates of the 0$^+_2$ isomeric state to the 2$^+_1$ and 0$^+_1$ states have been measured for the first time, leading to a reduced transition probability B(E2~:~2$^{+}_1$$\rightarrow$0$^{+}_2)$= 8.4(26)~e$^2$fm$^4$ and a monopole strength $\rho^2$(E0~:~0$^{+}_2$$\rightarrow$0$^{+}_1)$ =~8.7(7)$\times$10$^{-3}$. Comparisons to shell model calculations point towards prolate-spherical shape coexistence and a phenomenological two level mixing model is used to extract a weak mixing between the two configurations.Comment: 5 pages, 3 figures, accepted for publication in Physical Review Letter

The beta-decay of 22Al

In an experiment performed at the LISE3 facility of GANIL, we studied the decay of 22Al produced by the fragmentation of a 36Ar primary beam. A beta-decay half-life of 91.1 +- 0.5 ms was measured. The beta-delayed one- and two-proton emission as well as beta-alpha and beta-delayed gamma decays were measured and allowed us to establish a partial decay scheme for this nucleus. New levels were determined in the daughter nucleus 22Mg. The comparison with model calculations strongly favours a spin-parity of 4+ for the ground state of 22Al

Low-lying single-particle structure of 17C and the N = 14 sub-shell closure

The first investigation of the single-particle structure of the bound states of 17C, via the d(16C, p) transfer reaction, has been undertaken. The measured angular distributions confirm the spin-parity assignments of 1/2+ and 5/2+ for the excited states located at 217 and 335 keV, respectively. The spectroscopic factors deduced for these states exhibit a marked single-particle character, in agreement with shell model and particle-core model calculations, and combined with their near degeneracy in energy provide clear evidence for the absence of the N = 14 sub-shell closure. The very small spectroscopic factor found for the 3/2+ ground state is consistent with theoretical predictions and indicates that the ν1d3/2 strength is carried by unbound states. With a dominant = 0 valence neutron configuration and a very low separation energy, the 1/2+ excited state is a one-neutron halo candidate.Consejo de Instalaciones Científicas y Tecnológicas de UKRI. Reino Unido P003885Agencia Estatal de Investigación de España. Programa Ramón y Cajal RYC-2010-06484 y RYC-2012-11585Ministerio de Economia, Industria y Competitividad (MINECO) de España No. FPA2013-46236-PMinisterio de Ciencia, Innovación y Universidades español y los fondos FEDER FIS2017-88410-P y RTI2018-098117-B-C21El programa de investigación e innovación Horizon 2020 de la Unión Europea Subvención No. 65400

Collapse of the N=28 shell closure in 42^{42}Si

The energies of the excited states in very neutron-rich $^{42}$Si and $^{41,43}$P have been measured using in-beam $\gamma$-ray spectroscopy from the fragmentation of secondary beams of $^{42,44}$S at 39 A.MeV. The low 2$^+$ energy of $^{42}$Si, 770(19) keV, together with the level schemes of $^{41,43}$P provide evidence for the disappearance of the Z=14 and N=28 spherical shell closures, which is ascribed mainly to the action of proton-neutron tensor forces. New shell model calculations indicate that $^{42}$Si is best described as a well deformed oblate rotor.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. let