Commercial poultry production is associated with various stresses affecting productive and reproductive performance of birds and their health status. Recently the vitagene concept has received substantial attention. In fact, the term vitagenes refers to a group of genes that are responsible for preserving cellular homeostasis in stress conditions. These genes play a crucial role in cell and whole organism adaptation to stress by regulating additional synthesis of stress resistance proteins, including heat shock proteins, thioredoxins, sirtuins and superoxide dismutase. Among four major types of stress, nutritional stresses have a special place, being detrimental for productive and reproductive performances of poultry. In particular, mycotoxins are unavoidable contaminants of poultry feed and at molecular level they cause oxidative stress in the body. Oxidised fat and nutrient imbalances are also detrimental for gut health, immunity, growth and development of chickens. Internal stresses, including peak of egg production and vaccinations are also of great importance for poultry production. Therefore, the development of the effective antioxidant solutions to decrease negative consequences of nutritional and internal stresses is an important task for poultry scientists. One of such approaches is based on the vitagene concept which will be considered in this review.

Commercial poultry production is associated with various stresses affecting productive and reproductive performance of birds and their health status. In general, there are four major types of stress in poultry industry: technological, environmental, nutritional and internal stresses. This review considered main technological stresses: chick placement, increased stocking density, chicken weighing, grading and group formation in rearing houses, as well as bird transferring to breeder houses. The following paper analysed consequences of such environmental stresses as temperature stress and high levels of dust and ammonia in poultry houses. It has been proven that most of the aforementioned stresses suppress reproductive performance of parent birds, including reduced fertility and hatchability. Furthermore, stresses are associated with impaired feed conversion, reduced average daily weight gain, immunosuppression and increased mortality in growing birds. A growing body of evidence indicates that most of stresses in poultry production at the cellular level are associated with oxidative stress due to excess of free radical production or inadequate antioxidant protection. Therefore, the development of the effective nutritional solutions to decrease negative consequences of commercially-relevant stresses is an important task for poultry scientists. One of such approaches is based on vitagene concept which will be considered in the second part of the review.

Commercial poultry production is associated with four major types of stresses, including environmental, technological, nutritional and internal stresses, affecting productive and reproductive performance of birds and their health status. It has been suggested that at the molecular level most stresses are associated with overproduction of free radicals and oxidative stress. Therefore, the development of the effective antioxidant solutions to decrease negative consequences of commercially-relevant stresses is an important task for poultry scientists. One approach is based on possibilities of modulation of vitagenes, a family of genes responsible for animal/poultry adaptation to stress. In fact, the vitagene network includes heat shock proteins (HSPs), thioredoxin system, sirtuins and superoxide dismutases (SOD) and plays a regulatory role in most important cellular processes in stress conditions. Indeed, HSPs, including haem oxygenase-1 (HO-1) and HSP70, are responsible for protein homeostasis in stress conditions, while the thioredoxin system is the major player in maintaining redox status of the cell involved in protein and DNA synthesis and repair as well as in regulation of expression of many important genes. Furthermore, sirtuins regulate the biological functions of various molecules post-translationally by removing acetyl groups from protein substrates ranging from histones to transcription factors and orchestrate cellular stress response by maintenance of genome integrity and protein stability. Finally, SOD belong to the first level of antioxidant defence preventing lipid and protein oxidation at the very early stages. All vitagenes operate in concert building a reliable system of stress detection and adequate response and are considered to be key elements in stress adaptation. Indeed, further work is required to understand molecular mechanisms of the interactions of vitagenes with various signalling pathways and transcription factors in the cell to build an effective adaptive response to minimise the detrimental consequences of commercially-relevant stresses in poultry production.

Mechanical reliability is a critical issue in all forms of energy conversion, storage, and harvesting. In Li-ion batteries, mechanical degradation caused by the repetitive swelling and shrinking of electrodes upon lithiation cycles is now well recognized; however, the impact of mechanical stresses on Li transport and hence the capacity of batteries is less obvious and underestimated. In particular, the stress field within the heterogeneous electrodes is complex, making the characterization of the chemomechanical behaviors of electrodes a challenging task. We develop a finite element program that computes the coupled Li diffusion and stresses in three-dimensional composite electrodes. We employ the reconstructed models of both cathode and anode materials to investigate the mechanical interactions of the constituents and their influence on the accessible capacity. The state of charge in the percolated particles is highly inhomogeneous regulated by the stress field. An ample space of design is open for the optimization of the capacity and mechanical performance of electrodes by tuning the size, shape, and pattern of active particles, as well as the properties of the inactive matrix.

The biaxial stress and thermal expansion of multilayer doped-aluminosilicate environmental barrier coatings were measured in situ during cooling using microfocused high-energy X-rays in transmission. Coating stresses during cooling from 1000 °C were measured for as-sprayed and thermally cycled samples. In the as-sprayed state, tensile stresses as high as 75 MPa were measured in the doped-aluminosilicate topcoat at 375 °C, after which a drop in the stress occurred accompanied by through-thickness cracking of the two outermost layers. After thermally cycling the samples, the stress in the topcoat was reduced to approximately 50 MPa, and there was no drop in stress upon cooling. This stress reduction was attributed to a crystallographic phase transformation of the topcoat and the accompanying change in thermal expansion coefficient. The addition of a doped aluminosilicate to the mullite layer did not lower the stress in the topcoat, but may offer increased durability due to an increased compressive stress.

Ce travail présente une étude théorique du comportement mécanique des poutres sandwiches dont le cœur est en nid d'abeilles (NIDA) soumises à un essai de flexion 3 points. Les poutres étudiées sont obtenues à partir de plaques sandwiches destinées à la fabrication de bateaux de plaisance. Deux types de poutres sandwichs sont utilisés. Chaque poutre est composée de deux peaux symétriques dont les fibres sont en verres disposées en mat pour la poutre 1 et en plis croisés pour la poutre 2. L'âme est constituée de feuilles de polyéthylène dont les cellules sont de forme hexagonale. Les modules d'Young longitudinal et transversal des peaux sont obtenus expérimentalement par essai de traction, ils servent au calcul des contraintes normales et de cisaillement. L'effet de la cinématique, de l'élancement (rapport de la longueur de la poutre sandwich par son épaisseur totale), $\frac{L}{h}$, du rapport de l'épaisseur de l'âme par celle de la peau, et de l'effet du rapport du module d'Young longitudinal de la peau Ep par celui de l'âme Ea sur les contraintes normales et de cisaillement sont analysés. Les résultats des contraintes normales et de cisaillement pour trois champs de déplacement différents sont comparés. La différence des résultats justifie les conditions d'utilisation des théories simplifiées de Bernoulli et celle de Timoshenko pour ces types de poutres sandwiches.

À partir d'un modèle de transport d'eau en milieu biphasique et élastique [I. Mrani, J.-C. Bénet, G. Fras, Transport of water in a biconstituant elasticmedium, Appl. Mech. Rev., special issue on Mechanics of swelling 48 (1995) 717–721], on examine dans cette étude les risques de fissurationsinduites par la redistribution d'eau dans un échantillon de forme cylindriqueaprès séchage. La résolution numérique de l'équation de transport de l'eau et del'équation d'équilibre mécanique donnent accès à l'évolution de la teneur eneau, de la déformation et des contraintes dans le milieu. On s'intéressera àl'état du matériau pendant les phases de séchage, de refroidissement et destockage. À l'issue de cette étude, les risques de fissuration sont analyséspour différents scénarios de séchage, qui déterminent l'évolution de l'étathydrique pendant le stockage.

This study compares levels of couple agreement about positive and satisfying features of their relationship as reported by a remarried sample (n = 70) couples and a more general sample of couples largely in their first marriage or committed de facto relationship (n = 100 couples). The ENRICH inventory (Olson et al., 1982) was used with the general sample and the ENRICH-Anew inventory (Schultz & Schultz, 1987) was used for the remarried sample, thereby providing the measures of positive couple agreement, which can in turn serve as indicators for strengthening family relationships. There were no statistically significant differences between the two samples, indicating commonalities in stresses and strengths experienced by the two samples. However, there are suggestions in the data that issues related to children and parenting were subject to lower levels of agreement for the remarried couples. The comparison couples produced lower levels of agreement in the areas of conflict resolution and relating to partner's family and friends.