Application of multireflection grazing incidence method for stress measurements in polished Al–Mg alloy and CrN coating

Multi-reflection grazing incidence geometry, referred to as MGIXD, characterized by a small and constant incidence angle, was applied to measure low surface stresses in very thin layers of Al–Mg alloy and CrN coating. These two materials were selected in order to deal with the low and high levels of residual stress, respectively. The influence of different mechanical treatments on residual stresses was studied for Al–Mg samples. It was found that both rolling and mechanical polishing influence the distribution and amplitude of residual stress in surface layers. In the case of CrN coating, a very high compressive stress was generated during the deposition process. The stress distributions determined by the MGIXD method is in good agreement with the classic sin2 technique results for all studied samples. In performing stress measurements for a powder sample, it was found that the application of the Göbel mirror in the incident beam strongly reduces statistical and misalignment errors. Additionally, the root mean square values of the third order lattice strain within diffracting grains were determined

Application of multireflection grazing incidence method for stress measurements in polished Al–Mg alloy and CrN coating

Multi-reflection grazing incidence geometry, referred to as MGIXD, characterized by a small and constant incidence angle, was applied to measure low surface stresses in very thin layers of Al–Mg alloy and CrN coating. These two materials were selected in order to deal with the low and high levels of residual stress, respectively. The influence of different mechanical treatments on residual stresses was studied for Al–Mg samples. It was found that both rolling and mechanical polishing influence the distribution and amplitude of residual stress in surface layers. In the case of CrN coating, a very high compressive stress was generated during the deposition process. The stress distributions determined by the MGIXD method is in good agreement with the classic sin2 technique results for all studied samples. In performing stress measurements for a powder sample, it was found that the application of the Göbel mirror in the incident beam strongly reduces statistical and misalignment errors. Additionally, the root mean square values of the third order lattice strain within diffracting grains were determined

Multireflection grazing incidence diffraction used for stress measurementsin surface layers

The geometry based on the multireflection grazing incidence X-ray diffraction can be applied to measure residual stresses. Using this method, it is possible to perform a non-destructive analysis of the heterogeneous stresses for different and well defined volumes below the surface of the sample (range of several μm). As the result, the average values of stresses weighted by absorption of X-ray radiation are measured. In this work the stress profiles as a function of penetration depth were determined for mechanically polished Al sample. Measurements and verification of the method were performed using classical X-ray diffractometer and synchrotron radiation with different wavelengths

Elastoplastic deformation and damage process in duplex stainless steels studied using synchrotron and neutron diffractions in comparison with a self-consistent model

In situ time of flight neutron diffraction and X-ray synchrotron diffraction methods were applied to measure lattice strains in duplex steels during a tensile test. The experimental results were used to study slips on crystallographic planes and the mechanical effects of damage occurring during plastic deformation. For this purpose the prediction of an elastoplastic self-consistent model was compared with the experimental data. The used methodology allowed to determine the elastic limits and parameters describing work hardening in both phases of studied polycrystalline materials. In the second part of this work the developed elastoplastic model was applied to study damage occurring in the ferritic phase. The theoretical results showed a significant reduction of stresses localized in the damaged phase (ferrite) and confirmed the evolution of the lattice strains measured in the ferritic and austenitic phases

Taming the massive genome of Scots pine with PiSy50k, a new genotyping array for conifer research

Pinus sylvestris (Scots pine) is the most widespread coniferous tree in the boreal forests of Eurasia, with major economic and ecological importance. However, its large and repetitive genome presents a challenge for conducting genome-wide analyses such as association studies, genetic mapping and genomic selection. We present a new 50K single-nucleotide polymorphism (SNP) genotyping array for Scots pine research, breeding and other applications. To select the SNP set, we first genotyped 480 Scots pine samples on a 407 540 SNP screening array and identified 47 712 high-quality SNPs for the final array (called 'PiSy50k'). Here, we provide details of the design and testing, as well as allele frequency estimates from the discovery panel, functional annotation, tissue-specific expression patterns and expression level information for the SNPs or corresponding genes, when available. We validated the performance of the PiSy50k array using samples from Finland and Scotland. Overall, 39 678 (83.2%) SNPs showed low error rates (mean = 0.9%). Relatedness estimates based on array genotypes were consistent with the expected pedigrees, and the level of Mendelian error was negligible. In addition, array genotypes successfully discriminate between Scots pine populations of Finnish and Scottish origins. The PiSy50k SNP array will be a valuable tool for a wide variety of future genetic studies and forestry applications.Peer reviewe

Cross-tolerance to abiotic stresses in halophytes: Application for phytoremediation of organic pollutants

International audienceHalopytes are plants able to tolerate high salt concentrations but no clear definition was retained for them. In literature, there are more studies that showed salt-enhanced tolerance to other abiotic stresses compared to investigations that found enhanced salt tolerance by other abiotic stresses in halophytes. The phenomenon by which a plant resistance to a stress induces resistance to another is referred to as cross-tolerance. In this work, we reviewed cross-tolerance in halophytes at the physiological, biochemical, and molecular levels. A special attention was accorded to the cross-tolerance between salinity and organic pollutants that could allow halophytes a higher potential of xenobiotic phytoremediation in comparison with glycophytes

Stress localisation in lamellar cementite and ferrite during elastoplastic deformation of pearlitic steel studied using diffraction and modelling

International audienceSynchrotron X-ray diffraction was applied to study the evolution of lattice strain and stresses in both phases of pearlitic steel during a tensile test. The advantage of the methodology used in this work is the possibility of experimental study of stress localisation, which is directly determined from measurements and can be used to study the process of strain strengthening of lamellar pearlite. It was found that in the elastic range of deformation, both cementite and ferrite are loaded similarly due to the nearly equal elastic properties of both phases, while plastic deformation leads to significant load transfer from ferrite to cementite. Due to the complexity of the lamellar microstructure of the material, the classical elastic-plastic self-consistent model does not correctly predict the partitioning of the stresses between phases during plastic deformation. Therefore, the grain-matrix interaction given by the self-consistent model was modified and successfully applied to simulate the interaction between phases. The synchrotron experiment allowed us to determine the critical resolved shear stresses of ferrite phase in the pearlitic steel subjected to different thermal treatments. The role of cementite in material strengthening was evaluated on the basis of the evolution of von Mises stress, experimentally determined in both phases. It was found that during plastic deformations, the von Mises stress does not change significantly in ferrite compared to an important increase in elastically deformed cementite. Therefore, the partitioning of stresses between phases is mainly responsible for the strain strengthening of the tested pearlitic steel exhibiting fully lamellar microstructure

Comparative analysis of two sister Erythrophleum species (Leguminosae) reveal contrasting transcriptome-wide responses to early drought stress

Abstract With the ongoing climate change, African rainforests are expected to experience severe drought events in the future. In Africa, the tropical genus Erythrophleum (Fabaceae) includes two forest sister timber tree species displaying contrasting geographical distributions. Erythrophleum ivorense is adapted to wet evergreen Guineo-Congolian forests, whereas E. suaveolens occurs in a wider range of climates, being found in moist dense forests but also in gallery forests under a relatively drier climate. This geographical distribution pattern suggests that the two species might cope differently to drought at the genomic level. Yet, the genetic basis of tolerance response to drought stress in both species is still uncharacterized. To bridge this gap, we performed an RNA-seq approach on seedlings from each species to monitor their transcriptional responses at different levels of drought stress (0, 2 and 6 weeks after stopping watering seedlings). Monitoring of wilting symptoms revealed that E. suaveolens displayed an earlier phenotypic response to drought stress than E. ivorense. At the transcriptomic level, results revealed 2020 (1204 down-regulated/816 up-regulated) and 1495 differentially expressed genes (DEGs) in response to drought stress from a total of 67,432 and 66,605 contigs assembled in E. ivorense and E. suaveolens, respectively. After identifying 30,374 orthologs between species, we found that only 7 of them were DEGs shared between species, while 587 and 458 were differentially expressed only in E. ivorense or E. suaveolens, respectively. GO and KEGG enrichment analysis revealed that the two species differ in terms of significantly regulated pathways as well as the number and expression profile of DEGs (Up/Down) associated with each pathway in the two stress stages. Our results suggested that the two studied species react differently to drought. E. suaveolens seems displaying a prompt response to drought at its early stage strengthened by the down-regulation of many DEGs encoding for signaling and metabolism-related pathways. A considerable up-regulation of these pathways was also found in E. ivorense at the late stage of drought, suggesting this species may be a late responder. Overall, our data may serve as basis for further understanding the genetic control of drought tolerance in tropical trees and favor the selection of crucial genes for genetically enhancing drought resistance