Function and failure of the fetal membrane : modelling the mechanics of the chorion and amnion

The fetal membrane surrounds the fetus during pregnancy and is a thin tissue composed of two layers, the chorion and the amnion. While rupture of this membrane normally occurs at term, preterm rupture can result in increased risk of fetal mortality and morbidity, as well as danger of infection in the mother. Although structural changes have been observed in the membrane in such cases, the mechanical behaviour of the human fetal membrane in vivo remains poorly understood and is challenging to investigate experimentally. Therefore, the objective of this study was to develop simplified finite element models to investigate the mechanical behaviour and rupture of the fetal membrane, particularly its constituent layers, under various physiological conditions. It was found that modelling the chorion and amnion as a single layer predicts remarkably different behaviour compared with a more anatomically-accurate bilayer, significantly underestimating stress in the amnion and under-predicting the risk of membrane rupture. Additionally, reductions in chorion-amnion interface lubrication and chorion thickness (reported in cases of preterm rupture) both resulted in increased membrane stress. Interestingly, the inclusion of a weak zone in the fetal membrane that has been observed to develop overlying the cervix would likely cause it to fail at term, during labour. Finally, these findings support the theory that the amnion is the dominant structural component of the fetal membrane and is required to maintain its integrity. The results provide a novel insight into the mechanical effect of structural changes in the chorion and amnion, in cases of both normal and preterm rupture

Влияние фосфатных связующих на физико-механические свойства периклазохромитовых огнеупоров

У данній статті наведено та порівняно фізико-механічні властивості периклазо-хромітових матеріалів в залежності від різних типів фосфатних зв’язуючих та введення різних домішок. Визначено, що найбільш раціональним є введення триполіфосфату натрію.In given clause are resulted and the physycal-mechanical properties periclase-cgromite of materials are compared depending on different of types phosphate binding and introduction of the various additives. Is determined, that most rational is the introduction treepolyphosphate sodume

A risk-based approach to drive conceptual design taking into account low-maturity products

The presence of immature concepts makes difficult decision making at upstream phase of a development project. Rework tasks in collaborative development projects dealing with immature design concepts are very frequent and are responsible of cost overruns and schedule delays. In addition, decisions taken during conceptual design stage have the most important influence on product life cycle cost. In this context, a useful practice is to develop two or more concepts in parallel and delay decision making. Even so, a first screening of concepts is usually needed because of the substantial resources and time required in development phase. In this paper, an approach of concepts screening is proposed at conceptual design phase on the basis of two metrics.The first assesses ability of concepts to meet requirements with integration of maturity. Fuzzy logic tools are used to capture and propagate imprecision in embodiment design choices and behavior models. The second metric aims to assess expected performance of novel concepts compared with an existent product. It uses generalized ordered weighted averaging (GOWA) operator. A parametric aggregation function is also proposed as a support when using the two metrics. The proposed approach was applied to the development of a solar collector

Leukocyte density and proinflammatory mediator expression in regional human fetal membranes and decidua before and during labor at term

OBJECTIVES: The region of fetal membranes overlying the cervix, known as the zone of altered morphology (ZAM), is considered to be the principle site of membrane inflammatory activity and extracellular matrix remodelling. We wished to quantify the relative contribution of each area of fetal membranes to the inflammatory process of parturition. Specifically, we aimed to quantify and compare (1) leukocyte densities in three regions of fetal membranes and decidua before and during spontaneous labor at term, and (2) mRNA expression of interleukin (IL)-1 beta, IL-6, IL-8, cyclo-oxygenase type 1 (COX-1), and COX-2 in three regions of fetal membranes and decidua before and during spontaneous labor at term. METHODS: Biopsies of fetal membranes and decidua were obtained from pregnant women delivered by cesarean section at term both before and during spontaneous labor (n = 8 both groups). Fetal membranes were sampled from three areas, the ZAM, midzone (MZ), and periplacental (PP) regions. Leukocytes were identified by immunohistochemistry and their density quantified. Inflammatory mediator expression was quantified using TaqMan technology (Applied Biosystems, Foster City, CA). RESULTS: There was a significantly greater density of leukocytes in (1) the PP region of membranes compared with the ZAM, and (2) the decidua compared with amnion, amniotic connective tissue, and chorion. IL-1 beta, IL-6, and IL-8 mRNA expression was significantly greater in all regions following spontaneous labor compared with nonlaboring tissues. There were no regional differences in cytokine expression within the fetal membranes. Choriodecidua expressed significantly more IL-1 beta mRNA than amnion. Amnion expressed more COX-2 mRNA than choriodecidua. CONCLUSIONS: All regions of fetal membranes and decidua contribute to the inflammatory process of human parturition; however, their relative contributions differ in magnitude. Although the ZAM may be specifically important for membrane rupture, it does not appear to play a key or exclusive role in the other inflammatory processes of parturition. When studying fetal membranes, it is relevant to identify and define the area sampled for consistency and comparison with other studies