Stress corrosion crack initiation of Zircaloy-4 cladding tubes in an iodine vapor environment during creep, relaxation, and constant strain rate tests

During accidental power transient conditions with Pellet Cladding Interaction (PCI), the synergistic effect of the stress and strain imposed on the cladding by thermal expansion of the fuel, and corrosion by iodine released as a fission product, may lead to cladding failure by Stress Corrosion Cracking (SCC). In this study, internal pressure tests were conducted on unirradiated cold-worked stress-relieved Zircaloy-4 cladding tubes in an iodine vapor environment. The goal was to investigate the influence of loading type (constant pressure tests, constant circumferential strain rate tests, or constant circumferential strain tests) and test temperature (320, 350, or 380 °C) on iodine-induced stress corrosion cracking (I-SCC). The experimental results obtained with different loading types were consistent with each other. The apparent threshold hoop stress for I-SCC was found to be independent of the test temperature. SEM micrographs of the tested samples showed many pits distributed over the inner surface, which tended to coalesce into large pits in which a microcrack could initiate. A model for the time-to-failure of a cladding tube was developed using finite element simulations of the viscoplastic mechanical behavior of the material and a modified Kachanov's damage growth model. The times-to-failure predicted by this model are consistent with the experimental data

Baricitinib in patients with inadequate response or intolerance to conventional synthetic DMARDs: Results from the RA-BUILD study

Background Baricitinib is an oral, reversible, selective Janus kinase 1 and 2 inhibitor. Methods In this phase III, double-blind 24-week study, 684 biologic disease-modifying antirheumatic drug (DMARD)-naïve patients with rheumatoid arthritis and inadequate response or intolerance to ≥1 conventional synthetic DMARDs were randomly assigned 1:1:1 to placebo or baricitinib (2 or 4 mg) once daily, stratified by region and the presence of joint erosions. Endpoint measures included American College of Rheumatology 20% response (ACR20, primary endpoint), Disease Activity Score (DAS28) and Simplified Disease Activity Index (SDAI) score ≤3.3. Results More patients achieved ACR20 response at week 12 with baricitinib 4 mg than with placebo (62% vs 39%, p≤0.001). Compared with placebo, statistically significant improvements in DAS28, SDAI remission, Health Assessment Questionnaire-Disability Index, morning joint stiffness, worst joint pain and worst tiredness were observed. In a supportive analysis, radiographic progression of structural joint damage at week 24 was reduced with baricitinib versus placebo. Rates of adverse events during the treatment period and serious adverse events (SAEs), including serious infections, were similar among groups (SAEs: 5% for baricitinib 4 mg and placebo). One patient had an adverse event of tuberculosis (baricitinib 4 mg); one patient had an adverse event of non-melanoma skin cancer (baricitinib 4 mg). Two deaths and three major adverse cardiovascular events occurred (placebo). Baricitinib was associated with a decrease in neutrophils and increases in low-density and high-density lipoprotein. Conclusions In patients with rheumatoid arthritis and an inadequate response or intolerance to conventional synthetic DMARDs, baricitinib was associated with clinical improvement and inhibition of progression of radiographic joint damage

Self-Assemblage and Quorum in the Earthworm Eisenia fetida (Oligochaete, Lumbricidae)

Despite their ubiquity and ecological significance in temperate ecosystems, the behavioural ecology of earthworms is not well described. This study examines the mechanisms that govern aggregation behaviour specially the tendency of individuals to leave or join groups in the compost earthworm Eisenia fetida, a species with considerable economic importance, especially in waste management applications. Through behavioural assays combined with mathematical modelling, we provide the first evidence of self-assembled social structures in earthworms and describe key mechanisms involved in cluster formation. We found that the probability of an individual joining a group increased with group size, while the probability of leaving decreased. Moreover, attraction to groups located at a distance was observed, suggesting a role for volatile cues in cluster formation. The size of earthworm clusters appears to be a key factor determining the stability of the group. These findings enhance our understanding of intra-specific interactions in earthworms and have potential implications for extraction and collection of earthworms in vermicomposting processes

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Programmable electroacoustic boundaries in acoustic waveguides : enhanced attenuation and non-reciprocal sound propagation

International audienceSound attenuation along a waveguide is a highly demanded research field, for applications ranging from heating and air-conditioning ventilation systems, to aircraft turbofan engines. Electroacoustic devices and digital control have provided the tools for crafting innovativeliners where the boundary condition can be programmed. Hence, the question about “optimal” boundary conditions for noise transmission attenuation becomes more and more urgent. The most straightforward idea is to program classical local impedance operators, as these are theones generally employed for modelling the current state-of-art of acoustic liners, especially for aeronautic applications. A strategy which has been proved to be at the same time simple and sufficiently robust, is to pilot the vibration of each speaker diaphragm based upon the sensedpressure on it (obtained by quasi-collocated microphones), in order to modify the resonator dynamics (varying its quality factor, or resonance frequency). Nevertheless, it might be worthy to navigate off the beaten track, and try to exploit the progammability of our electro-active systems, in order to target boundary operators which could never be physically produced by purely passive treatments. In this contribution, we focus the attention on a particular boundary law, called “advective”, as it possesses a convective character achieved thanks to the introduction of the first spatial derivative. We implement such boundary condition on our electroacoustic liner and demonstrate its potentialities in reducing the noise transmission and radiation in a circular waveguide. Numerical simulations and experimental implementation on a scaled turbofan mock-up show promising results

The Advection Boundary Law in presence of mean-flow and spinning modes

International audienceIn the attempt to reduce fuel consumption, a new generation of Ultra-High-By-Pass-Ratio (UHBR) turbofans have been introduced in the aeronautic industry which are structurally noisier especially at lower frequencies, because of their larger diameter, lower number of blades and rotational speed. Moreover, they present a shorter nacelle, leaving less available space for acoustic treatments. For this reason, innovation in the liner technology is highly demanded. In this contribution, we analyse the performances of an electroacoustic liner, made up of microphones (sensors) and small loudspeakers (actuators). Such array of electroacoustic resonators can feature an interesting boundary operator, called Advection Boundary Law. Such boundary law has been analysed in grazing-incident acoustic fields without air-flow and in case of plane waves. Here, we adapt such boundary condition to attenuate spinning modes. Numerical simulations in case of spinning-modes, shows the potentialityand the passivity issues of such innovative boundary law. Finally, a reproduction of a turbofan engine (scale 1:3) accomplishing real-life rotational speeds, allows to assess the performances of the Advection Boundary Law in presence of mean-flow and spinning-modes

The Advection Boundary Law in presence of mean-flow and spinning modes

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Smart Acoustic Lining for UHBR Technologies Engine Part 1: design of an electroacoustic liner and experimental characterization under flow in rectangular cross-section ducts

International audienceThe new generation of Ultra-High-By-Pass-Ratio (UHBR) turbofan engine while considerably reducing fuel consumption, threatens higher noise levels at low frequencies because of its larger diameter, lower number of blades and rotational speed. This is accompanied by a shorter nacelle, leaving less available space for acoustic treatments. In this context, a progress in the liner technology is highly demanded, prospecting alternative solutions to classic liners. The SALUTE H2020 project has taken up this challenge, proposing electro-active acoustic liners, made up of loudspeakers (actuators) and microphones (sensors). The electro-active means allow to program the surface impedance on the electroacoustic liner, but also to conceive alternative boundary laws. Test-rigs of gradually increasing complexities have allowed to raise the Technology Readiness Level (TRL) up to 3-4. In this first part, we describe the control laws employed in the experimental campaigns, and present the scattering performances in rectangular waveguides with monomodal guided propagation. These results have assessed the isolation capabilities, stability and robustness of such programmable boundary technology, allowing to gain confidence for the successive implementation in a scaled turbofan test-rig

Electroacoustic Liner for tonal and broadband noise attenuation of turbofans

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Model-inversion control to enforce tunable Duffing-like acoustical response on an Electroacoustic resonator at low excitation levels

International audienceThe electroacoustic resonator is an efficient electro-active device for noise attenuation in enclosed cavities or acoustic waveguides. It is made of a loudspeaker (the actuator) and one or more microphones (the sensors). So far, the desired acoustic behaviour, expressed in terms of a linear-time-invariant relationship between sound pressure and vibrational motion (the acoustical impedance), has been more efficiently achieved by a model-inversion strategy which is implemented by driving the electrical current in the loudspeaker coil, based upon the measured pressure. The corrector transfer function is defined in the Laplace domain and digitally executed by the classical infinite-impulse-response technique, though a state-space representation could be employed. In this work, we are interested in enforcing a nonlinear behaviour at low sound excitation levels, where the electroacoustic resonator would normally behave as a linear-timeinvariant system. Hence, in order to transform its acoustical response from linear to nonlinear, the model-inversion technique must be reformulated in time domain. The state-space representation of the relationship between the input measured pressure and the output electrical current gives the right perspective and the solution to this problem. We provide the conception of this modelinversion control algorithm capable of transforming a linear-time-invariant acoustical response to potentially any causal acoustical response of the electroacoustic resonator. Such control strategy is tested by targeting a Duffing acoustical response with tunable parameters. Both numerical simulations and experimental tests in quasi-open field validate the approach. The results provided in this contribution open the doors for conceiving non-conventional absorbers which can exploit nonlinear phenomena for noise mitigation even at low excitation amplitudes