The mechanical behavior of zinc alloys drastically depends on strain rate and temperature, which are not constant during forming processes. During the production of zinc sheets, the slight variations ...of the industrial equipment parameters induce different local thermomechanical conditions. These variations could be stemming from a non-homogeneous cooling during rolling process, or local segregation of alloys and so on …. The result of these differences entails a significant scattering of material parameters as shown in (Milesi et al. J Mat Process Tech 245:134-148,
2017
). This paper tackles the scattering of material parameters through an adapted Norton-Hoff behavior law. Then, four parameters have been identified with a standard Generalized Reduced Gradient method (GRG). Moreover, an exhaustive analysis of the entire rolled coil has been carried out to differentiate the variation coming from the material from the one due to the process. This study also encompasses the influence of strain rate on the forming limit diagram and therefore on the calculation of the forming limit stress diagram.
The developing uterus is highly sensitive to a brief exposure to different substances, in particular those with endocrine-disrupting activity. Thus, exposure to environmental, nutritional, chemical, ...and other xenobiotic factors affecting signaling events during critical organizational periods can alter the normal course of uterine development with lasting consequences. In this chapter, we provide an experimental protocol to evaluate the development of the rat uterus as a toxicity biomarker at two different developmental time points: (1) the neonatal period, on postnatal day (PND) 8, and (2) the prepubertal period, on PND21. In this experimental approach, we propose to assess: (1) uterine morphology and cytodifferentiation, (2) uterine cell proliferation, and (3) the expression of proteins involved in uterine organogenetic differentiation. All these morphological and molecular markers are useful tools to determine the consequences of exposure to toxicants with the potential to disrupt the uterine development.
The aim of the present study was to compare the effect of oral and subcutaneous exposure to a glyphosate-based herbicide (GBH) on the female reproductive system, specifically in the ovaries and ...uterus of prepubertal lambs. To this end, ewe lambs were exposed to a s.c. (n: 5) or an oral (n: 5) environmentally relevant dose of GBH (2 mg/kg/day) or to vehicle (controls, n: 12), from postnatal day (PND) 1 to PND14. Serum glyphosate and aminomethylphosphonic acid (AMPA) concentrations were measured on PND15 and PND45. The ovaries and uterus were obtained and weighed on PND45. Ovarian follicular dynamics and uterine morphological features were determined by picrosirius-hematoxylin staining. The proliferation marker Ki67 was evaluated by immunohistochemistry in ovarian and uterine samples. Glyphosate but not AMPA was detected in serum of exposed lambs on PND15, whereas neither glyphosate nor AMPA were detected on PND45. Controls were negative for glyphosate and AMPA on PND15 and PND45. GBH exposure did not affect ovarian or uterine weight. However, on PND45, the ovary of GBH-exposed lambs showed altered follicular dynamics, increased proliferation of granulosa and theca cells, and decreased mRNA expression of FSHR and GDF9, whereas their uterus showed decreased cell proliferation but no alterations in the histomorphology or gene expression. In conclusion, GBH exposure altered the ovarian follicular dynamics and gene expression, and the proliferative activity of the ovaries and uterus of lambs. It is noteworthy that all the adverse effects found in the ovaries and uterus of both GBH-exposed groups were similar, independently of the administration route.
•Glyphosate-based herbicide alters follicular dynamic in prepubertal ewe lambs.•Cell proliferation is altered in ovary of Glyphosate-based herbicide exposed ewes.•Cell proliferation is altered in uterus of Glyphosate-based herbicide exposed ewes.•Glyphosate-based herbicide exposure alters ovarian FSHR and GDF9 mRNA.•The observed adverse effects were independent of the administration route.
Strongly proteolytic starters seem to improve the growth of nonstarter lactobacilli during cheese ripening, but no information is available on the impact of the nonmicrobial proteases usually active ...in cheese on their development. In the current study, the influence of chymosin- and plasmin-mediated proteolysis on the growth and biochemical activities of lactobacilli during ripening of miniature Cheddar-type cheeses, manufactured under controlled microbiological conditions, was studied. Two experiments were performed; in the first, residual chymosin activity was inhibited by the addition of pepstatin, and in the second, plasmin activity was increased by adding more enzyme, obtained in vitro through the activation of plasminogen induced by urokinase. Cheeses with or without a Lactobacillus plantarum I91 adjunct culture and with or without added pepstatin or plasmin solution were manufactured and ripened for 60 d. The addition of the adjunct culture resulted in enhancement of secondary proteolysis, evidenced by an increase in the total content of free amino acids (FAA) and modifications of the individual FAA profiles. Reduction in residual chymosin activity caused a decrease in primary and secondary proteolysis, characterized by the absence of αs1-casein hydrolysis and reduced production of peptides and FAA, respectively. The increase in plasmin activity accelerated primary proteolysis but no enhancement of secondary proteolysis was observed. Chymosin- and plasmin-mediated proteolysis did not influence the growth and biochemical activities of adventitious or adjunct lactobacilli, indicating that it is not a limiting factor for the development and proteolytic-peptidolytic activities of lactobacilli in the cheese model studied.
Zinc alloys are used in a wide range of application such as electronics, automotive and building construction. Their various shapes are generally obtained by metal forming operation such as stamping. ...Therefore, it is important to characterize the material with adequate characterization tests. Sheet Bulging Test (SBT) is well recognized in the metal forming community. Different theoretical models of the literature for the evaluation of thickness and radius of the deformed sheet in SBT have been studied in order to get the hardening curve of different materials. These theoretical models present the advantage that the experimental procedure is very simple. But Koç et al. showed their limitation, since the combination of thickness and radius evaluations depend on the material. As Zinc alloys are strongly anisotropic with a special crystalline structure, a procedure is adopted for characterizing the hardening curve of a Zinc alloy. The anisotropy is first studied with tensile test, and SBT with elliptical dies is also investigated. Parallel to this, Digital Image Correlation (DIC) measures are carried out. The results obtained from theoretical models and DIC measures are compared. Measures done on post-mortem specimens complete the comparisons. Finally, DIC measures give better results and the resulting hardening curve of the studied zinc alloy is provided.
The exposure to endocrine-disrupting compounds (EDCs), such as glyphosate-based herbicides (GBHs), during early life might alter female fertility. The aim of the present study was to evaluate the ...effects of neonatal exposure to a GBH on sheep uterine development. To achieve this, Friesian ewe lambs were exposed to GBH (2 mg/kg of body weight/day; n = 12) or vehicle (controls; n = 10) through s.c. injections, from postnatal day (PND) 1 to PND14; on PND45, the uteri were obtained to evaluate histomorphological and molecular parameters. Morphological parameters were determined by picrosirius-hematoxylin staining. Protein expression of Ki67 (as a cell proliferation marker), p27, and molecules involved in uterine organogenetic differentiation was measured by immunohistochemistry. We also determined the mRNA expression of the IGF molecular pathway by RT-PCR. Although histomorphology was not modified, the uteri of GBH-exposed ewe lambs showed lower cell proliferation, together with higher p27 protein expression. In addition, the uteri of GBH-exposed ewe lambs showed increased gene expression of insulin-like growth factor binding protein 3 (IGFBP-3), decreased expression of ERα in the luminal (LE) and glandular (GE) epithelia and in the subepithelial stroma (SS), and lower PR expression in the LE but higher in the GE and SS. In addition, GBH treatment decreased the uterine expression of Wnt5a in the GE, of Wnt7a in the SS, of β-catenin in the LE and GE, of Hoxa10 in the SS, and of Foxa2 in the GE as compared with controls. In conclusion, neonatal exposure to GBH decreased cell proliferation and altered the expression of molecules that control proliferation and development in the uterus. All these changes might have adverse consequences on uterine differentiation and functionality, affecting the female reproductive health of sheep. GBH may be responsible for uterine subfertility, acting as an EDC.
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•Uterine cell proliferation is diminished in glyphosate-based herbicide exposed ewes.•Glyphosate-based herbicide exposure increased IGFBP-3 and p27 expression.•Estrogen and progesterone receptors expression is altered in treated ewes.•The exposure decreased the Wnt5a, Wnt7a and β-catenin uterine expression.•Hoxa10 and Foxa2 were also downregulated by glyphosate-based herbicide exposure.
Forged components exhibit good mechanical strength, particularly in terms of high cycle fatigue properties. This is due to the specific microstructure resulting from large plastic deformation as in a ...forging process. The goal of this study is to account for critical phenomena such as the anisotropy of the fatigue resistance in order to perform high cycle fatigue simulations on industrial forged components. Standard high cycle fatigue criteria usually give good results for isotropic behaviors but are not suitable for components with anisotropic features. The aim is to represent explicitly this anisotropy at a lower scale compared to the process scale and determined local coefficients needed to simulate a real case. We developed a multi-scale approach by considering the statistical morphology and mechanical characteristics of the microstructure to represent explicitly each element. From stochastic experimental data, realistic microstructures were reconstructed in order to perform high cycle fatigue simulations on it with different orientations. The meshing was improved by a local refinement of each interface and simulations were performed on each representative elementary volume. The local mechanical anisotropy is taken into account through the distribution of particles. Fatigue parameters identified at the microscale can then be used at the macroscale on the forged component. The linkage of these data and the process scale is the fiber vector and the deformation state, used to calculate global mechanical anisotropy. Numerical results reveal an expected behavior compared to experimental tendencies. We proved numerically the dependence of the anisotropy direction and the deformation state on the endurance limit evolution.
► A former step is proposed in the validation of microstructural tomographic approach. ► An advanced anisotropic mesh adaptation reconstructs 3D complex inclusions. ► The proposed approach allows a ...simple and fast immersion of the inclusions. ► Parallel computing highlights the potential to handle complex tomographic probe. ► A sensitivity analysis has been then carried out to optimize the REV.
The topology of representative elementary volumes (REV) generated to model materials microstructure is getting more and more complex. This paper presents advanced mesh generation methods used to improve the description of 3D microstructural particles. The goal is to adapt easily the shape of the elements at the interface between the isotropic matrix and embedded inclusions. Two methods are described in this work to generate inclusions: an analytical method based on statistical experimental data and a reconstruction approach, based on tomographic imaging. Sensitivity analyses on meshing parameters are performed to obtain efficient data in order to reconstruct the most representative volume and to perform subsequent accurate numerical computations. As an example of calculations, fatigue tests are chosen to validate the proposed approach.
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