Single QTL mapping and nucleotide-level resolution of a physiologic trait in wine Saccharomyces cerevisiae strains.

International audienceNatural Saccharomyces cerevisiae yeast strains exhibit very large genotypic and phenotypic diversity. However, the link between phenotype variation and genetic determinism is still difficult to identify, especially in wild populations. Using genome hybridization on DNA microarrays, it is now possible to identify single-feature polymorphisms among divergent yeast strains. This tool offers the possibility of applying quantitative genetics to wild yeast strains. In this instance, we studied the genetic basis for variations in acetic acid production using progeny derived from two strains from grape must isolates. The trait was quantified during alcoholic fermentation of the two strains and 108 segregants derived from their crossing. A genetic map of 2212 markers was generated using oligonucleotide microarrays, and a major quantitative trait locus (QTL) was mapped with high significance. Further investigations showed that this QTL was due to a nonsynonymous single-nucleotide polymorphism that targeted the catalytic core of asparaginase type I (ASP1) and abolished its activity. This QTL was only effective when asparagine was used as a major nitrogen source. Our results link nitrogen assimilation and CO(2) production rate to acetic acid production, as well as, on a broader scale, illustrating the specific problem of quantitative genetics when working with nonlaboratory microorganisms

Nondestructive testing of composites using a nonlinear acoustic spectroscopy method

The presented experimental work describes the nondestructive examination of polymer based composites using an acoustic method under the consideration of nonlinear effects. The technique is based on the fact that material behaves more nonlinearly in the presence of damage than in the undamaged state during dynamic load. Damaged structures show an increased nonlinear transmission behavior. Consequently, the level of nonlinearity is an indication of the damage severity. The aim is to analyze the nonlinear transfer behavior and if a quantification can be used to determine the damage severity. The focus is on the type of nonlinear acoustic spectroscopy methods that analyses the modulation spectrum. When two harmonic waves are applied with different frequencies to a damaged material, the amplitude of the high-frequency wave will be modulated by the low-frequency wave and the created spectrum manifests an intermodulation by showing new frequencies such as sidebands and higher harmonics. Samples made of glass fiber reinforced vinyl ester respectively epoxy, both taffeta woven, and pre-damaged by application of tensile tests using different levels of tension have been considered. A new experimental setup has been developed and a clearly visible increase of the intermodulation with increasing damage has been noticed for both materials. Finally, the method is proven to nondestructively evaluate the damage state of composites.OpenLab “Materials and Processes” supported by PSA Peugeot Citroë

Damage Evaluation in Woven Glass Reinforced Polyamide 6.6/6 Composites Using Ultrasound Phase-Shift Analysis and X-ray Tomography

The paper proposes a new experimental methodology, based on ultrasonic measurements, that aims at evaluating the anisotropic damage in woven semi-crystalline polymer composites through new damage indicators. Due to their microstructure, woven composite materials are characterized by an anisotropic evolution of damage induced by different damage mechanisms occurring at the micro or mesoscopic scales. In this work, these damage modes in polyamide 6.6/6-woven glass fiber reinforced composites have been investigated qualitatively and quantitatively by X-ray micro-computed tomography (mCT) analysis on composite samples cut according to two orientations with respect to the mold flow direction. Composite samples are initially damaged at different levels during preliminary interrupted tensile tests. Ultrasonic investigations using C-scan imaging have been carried out without yielding significant results. Consequently, an ultrasonic method for stiffness constants estimation based on the bulk and guided wave velocity measurements is applied. Two damage indicators are then proposed. The first consists in calculating the Frobenius norm of the obtained stiffness matrix. The second is computed using the phase shift between two ultrasonic signals respectively measured on the tested samples and an undamaged reference sample. Both X-ray mCT and ultrasonic investigations show a higher damage evolution with respect to the applied stress for the samples oriented at 45◦ from the warp direction compared to the samples in the 0◦ configuration. The evolution of the second ultrasonic damage indicator exhibits a good correlation with the void volume fraction evolution estimated by mCT as well as with the damage calculated using the measured elastic modulus reduction. The merit of this research is of importance for the automotive industry.The present work was funded by PSA Group and made in the framework of the OpenLab Materials and Processes. This OpenLab involves PSA Group, The Arts et Metiers ParisTech and Georgia Tech Lorraine

Detection and evaluation of barely visible impact damage in woven glass fabric reinforced polyamide 6.6/6 composite using ultrasonic imaging, X-ray tomography and optical profilometry

The present experimental work investigates the response of woven glass fabric reinforced polyamide 6.6/6 subjected to drop weight impact loading. The main objective is the development and the introduction of a new experimental procedure/approach, based on different complementary detection techniques, that aims at investigating the damage induced by impact loading in thermoplastic woven fabric composites. The developed approach is intended to be generalized to other types of composite materials. The main idea is to assess all the experimental results obtained through the developed procedure with a direct investigation method. The latter consists in the Permanent Indentation (PI) measurement providing an indicator of the damage criticality in the composite sample. To this end, several non-destructive testing methods are carried-out and their experimental findings are analyzed and cross-linked. The identification of the different damage mechanisms, caused by the drop weight impact, is performed using X-Ray micro-computed tomography (mCT). C-scan ultrasonic investigation is conducted according to two types: transmission and reflection for the detection of the impact damage and the identification of the induced degradation area. B-scan imaging are then obtained through specific post-processing of the impacted surface to extract the permanent indentation (PI). The latter is validated through surface flatness measurement using the highly resolved 3D optical profilometry. The correlation between the X-Ray tomography results and the permanent indentation measurement is then established. It correlates the PI level with the damage mechanisms of a barely visible impact damage (BVID) in woven glass reinforced polyamide 6.6/6 composite.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The present work is co-funded by Groupe PSA and ANRT. It is made in the framework of the OpenLab Materials and Processes involving Groupe PSA, Arts et Metiers (ENSAM) and Georgia Tech Lorraine

Front Microbiol

Brettanomyces bruxellensis is the main spoilage microbial agent in red wines. The use of fungal chitosan has been authorized since 2009 as a curative treatment to eliminate this yeast in conventional wines and in 2018 in organic wines. As this species is known to exhibit great genetic and phenotypic diversity, we examined whether all the strains responded the same way to chitosan treatment. A collection of 53 strains of was used. In the conditions of the reference test, all were at least temporarily affected by the addition of chitosan to wine, with significant decrease of cultivable population. Some (41%) were very sensitive and no cultivable yeast was detected in wine or lees after 3 days of treatment, while others (13%) were tolerant and, after a slight drop in cultivability, resumed growth between 3 and 10 days and remained able to produce spoilage compounds. There were also many strains with intermediate behavior. The strain behavior was only partially linked to the strain genetic group. This behavior was little modulated by the physiological state of the strain or the dose of chitosan used (within the limits of the authorized doses). On the other hand, for a given strain, the sensitivity to chitosan treatment was modulated by the chitosan used and by the properties of the wine in which the treatment was carried out.Recherches sur l’origine et les effets secondaires des propriétés stabilisantes du chitosane fongique dans le vi

Détection de l'endommagement dans un composite tissé PA66,6/Fibres de verre à l'aide de techniques ultrasonores en vue d'une prédiction de la durabilité de pièces automobiles

The present study is focused on the experimental study of a polyamide 66/6 based composite reinforced by a 2/2 twill weave glass fabric. The aim is to propose Non Destructive Evaluation (NDE) methods based on ultrasound that can efficiently distinguish different damage state. In order to do so, an investigation of the damage mechanisms induced by different type of mechanical solicitations. Tension along and off the axis of the fibers was considered as well as the case of drop weight impact. Those solicitations were shown to induce different damage mechanisms. The latter were characterized by means of Scanning Electronic Microscopy (SEM) and X-Ray tomography mostly. The decreasing of the elastic modulus and the void volume fraction evolution were shown to be more significant for the samples loaded in tension off-axis. During the drop weight impact tests, the energies were considered in order to remain close to the Barely Visible Impact Damage (BVID) regime in order to experience the capability of the ultrasound based NDE methods. Two NDE methods investigated during this study deserve to be highlighted. Firstly, the stiffness tensor was estimated by means of phase velocities measurements in different propagation direction. Damage indicators based on results from this method were proposed. They were found to give results similar with the one from the evaluation of damage discussed earlier on. Secondly, a study of the damage detection using guided waves was performed. No mode conversion effect was observed from this investigation. Consequently, the signal energy was proposed as damage indicator and was found to be suitable to detect damage induced by tension but not by impact. The measure of time shift allowed obtaining a localization and evaluation of the damage induced by impact.Ces travaux de thèse portent sur l'étude expérimentale approfondie d'un composite à base polyamide 66/6 renforcé par des fibres de verres tissés suivant un motif sergé 2/2. L’objectif est de proposer des solutions de Contrôle Non Destructif (CND) basées sur les ultrasons afin de détecter différents niveaux d’endommagement induis. Pour cela, une étude approfondis des mécanismes d’endommagement apparaissant lors de sollicitations en traction suivant l’axe des fibres et hors axes est réalisé. Le cas d’impact induis par poids tombant est également étudiés. En effet, ces différents cas de sollicitions entraînent l’apparition de différent mécanismes d’endommagement. Ces derniers, ainsi que leur ordre d’apparition, sont caractérisés par Microscopie Electronique à Balayage (MEB) et tomographie à rayons X principalement. L’évaluation de la réduction du module élastique pré et post chargement ainsi que la fraction volumique de vide montrent une évolution de l’endommagement plus importante lors de chargement en traction hors axes des fibres que lors de chargement suivant l’axe. Lors des essais d’impact par poids tombant différents niveaux d’énergie sont considérés en restant proche du domaine des BVID en vue d’éprouver la sensibilité des méthodes de CND. Deux méthodes de CND par ultrasons étudiées durant ce projet peuvent être mises en avant. Premièrement, par mesure de la vitesse de propagation des ondes dans plusieurs directions du composites, le tenseur de rigidité est estimé dans tous ces cas de sollicitation mécanique pour différents niveaux d’endommagement. Des indicateurs d’endommagement basés sur ces mesures montrent une évolution de l’état d’endommagement similaire à celle discutée précédemment. Deuxièmement, une étude de la détection de l’endommagement par ondes guidées est menée. Aucun changement des modes transmit n’est visible lors de l’augmentation de l’état d’endommagement. L’évolution de l’énergie du signal transmis est alors proposée et validée comme indicateur d’endommagement efficace pour des chargements en traction mais pas pour l’impact. La mesure du décalage temporel à en revanche permis une localisation et une quantification de l’endommagement induit par impact

Damage detection in a PA 66,6/Glass woven fabric composite material using ultrasonic techniques towards durability prediction of automotive parts

Ces travaux de thèse portent sur l'étude expérimentale approfondie d'un composite à base polyamide 66/6 renforcé par des fibres de verres tissés suivant un motif sergé 2/2. L’objectif est de proposer des solutions de Contrôle Non Destructif (CND) basées sur les ultrasons afin de détecter différents niveaux d’endommagement induis. Pour cela, une étude approfondis des mécanismes d’endommagement apparaissant lors de sollicitations en traction suivant l’axe des fibres et hors axes est réalisé. Le cas d’impact induis par poids tombant est également étudiés. En effet, ces différents cas de sollicitions entraînent l’apparition de différent mécanismes d’endommagement. Ces derniers, ainsi que leur ordre d’apparition, sont caractérisés par Microscopie Electronique à Balayage (MEB) et tomographie à rayons X principalement. L’évaluation de la réduction du module élastique pré et post chargement ainsi que la fraction volumique de vide montrent une évolution de l’endommagement plus importante lors de chargement en traction hors axes des fibres que lors de chargement suivant l’axe. Lors des essais d’impact par poids tombant différents niveaux d’énergie sont considérés en restant proche du domaine des BVID en vue d’éprouver la sensibilité des méthodes de CND. Deux méthodes de CND par ultrasons étudiées durant ce projet peuvent être mises en avant. Premièrement, par mesure de la vitesse de propagation des ondes dans plusieurs directions du composites, le tenseur de rigidité est estimé dans tous ces cas de sollicitation mécanique pour différents niveaux d’endommagement. Des indicateurs d’endommagement basés sur ces mesures montrent une évolution de l’état d’endommagement similaire à celle discutée précédemment. Deuxièmement, une étude de la détection de l’endommagement par ondes guidées est menée. Aucun changement des modes transmit n’est visible lors de l’augmentation de l’état d’endommagement. L’évolution de l’énergie du signal transmis est alors proposée et validée comme indicateur d’endommagement efficace pour des chargements en traction mais pas pour l’impact. La mesure du décalage temporel à en revanche permis une localisation et une quantification de l’endommagement induit par impact.The present study is focused on the experimental study of a polyamide 66/6 based composite reinforced by a 2/2 twill weave glass fabric. The aim is to propose Non Destructive Evaluation (NDE) methods based on ultrasound that can efficiently distinguish different damage state. In order to do so, an investigation of the damage mechanisms induced by different type of mechanical solicitations. Tension along and off the axis of the fibers was considered as well as the case of drop weight impact. Those solicitations were shown to induce different damage mechanisms. The latter were characterized by means of Scanning Electronic Microscopy (SEM) and X-Ray tomography mostly. The decreasing of the elastic modulus and the void volume fraction evolution were shown to be more significant for the samples loaded in tension off-axis. During the drop weight impact tests, the energies were considered in order to remain close to the Barely Visible Impact Damage (BVID) regime in order to experience the capability of the ultrasound based NDE methods. Two NDE methods investigated during this study deserve to be highlighted. Firstly, the stiffness tensor was estimated by means of phase velocities measurements in different propagation direction. Damage indicators based on results from this method were proposed. They were found to give results similar with the one from the evaluation of damage discussed earlier on. Secondly, a study of the damage detection using guided waves was performed. No mode conversion effect was observed from this investigation. Consequently, the signal energy was proposed as damage indicator and was found to be suitable to detect damage induced by tension but not by impact. The measure of time shift allowed obtaining a localization and evaluation of the damage induced by impact

Acoustic Wood Anomaly: A Unique Phenomenon of Diffraction and Surface Acoustic Wave Generation on Periodically Corrugated Surface – investigation of physical origins

International audienceWood anomaly is widely known as a fascinating optical phenomenon in which the spectrum of an incident white light reflected from a diffraction grating contains some anomalies such local intensity increases and decreases at specific frequencies. Similarly, in acoustics, sharp dips were observed in the reflection spectra of a wideband acoustic pulse perpendicularly incident onto a periodically corrugated interface, which has been called acoustic Wood anomaly. The greatest concern of this acoustic phenomenon is its physical origin. In precious studies, the sharp dips were interpreted as missing energy, which was thought to be lost in the interaction of incident waves with periodic interfaces, and correlation was found between the anomaly frequencies and the critical frequencies at which surface acoustic waves were potentially generated through diffraction. This observation suggests that the ”missing” energy ais not really missing but retarded. We also show that in pulsed acoustics the occurrence of spectral anomalies highly depends on the time-domain signal windowing, and by properly selecting the portions of signal to be analyzed we can control the occurrence of the spectral anomalies in reflection spectra. We further show that the physical processes from the incident wideband waves to the appearance of spectral anomalies are involved with generation pseudo surface acoustic waves and two-time diffraction on periodically corrugated interfaces. Moreover, we show that acoustic Wood anomalies not only exist in the reflection fields, but also in the transmission fields and diffraction fields. In this sense, these anomalies are not abnormal phenomena any more. As a fundamental study of the interaction of sound with periodic structures, this work may shed light on the further investigation on phononic crystals and acoustic metamaterials, the main structural feature of which is periodic organization of constituent components