Microdomain heterogeneity in 3D affects the mechanics of neonatal cardiac myocyte contraction

Abstract Cardiac muscle cells are known to adapt to their physical surroundings, optimizing intracellular organization and contractile function for a given culture environment. A previously developed in vitro model system has shown that the inclusion of discrete microscale domains (or microrods) in three dimensions (3D) can alter long-term growth responses of neonatal ventricular myocytes. The aim of this work was to understand how cellular contact with such a domain affects various mechanical changes involved in cardiac muscle cell remodeling. Myocytes were maintained in 3D gels over 5 days in the presence or absence of 100 − µm-long microrods, and the effect of this local heterogeneity on cell behavior was analyzed via several imaging techniques. Microrod abutment resulted in approximately twofold increases in the maximum displacement of spontaneously beating myocytes, as based on confocal microscopy scans of the gel xy-plane or the myocyte long axis. In addition, microrods caused significant increases in the Electronic supplementary material The online version of this articl

Calculation of the critical energy release rate Gc of the cement line in cortical bone combining experimental tests and finite element models

[EN] In this work, a procedure is proposed to estimate the critical energy release rate Gc of the so-called cement line in cortical bone tissue. Due to the difficulty of direct experimental estimations, relevant elastic and toughness material properties at bone microscale have been inferred by correlating experimental tests and finite element simulations. In particular, three-point bending tests of ovine cortical bone samples have been performed and modeled by finite elements. The initiation and growth of microcracks in the tested samples are simulated through finite elements using a damage model based on a maximum principal strain criterion, showing a good correlation with the experimental results. It is observed that microcracks evolve mainly along the cement lines and through the interstitial material but without crossing osteons. The numerical model allows the calculation of the cement line critical energy release rate Gc by approximating its definition by finite differences. This way, it is possible to estimate this property poorly documented in the literature.The authors wish to thank the Ministerio de Economia y Competitividad for the support received in the framework of the project DPI2013-46641-R and to the Generalitat Valenciana, Programme PROMETEO 2016/007. The authors also thank Dr. Jose Luis Peris, from Instituto de Biomecanica de Valencia (IBV) and Carlos Tudela Desantes for their collaboration within the context of the project.Giner Maravilla, E.; Belda, R.; Arango-Villegas, C.; Vercher Martínez, A.; Tarancón Caro, JE.; Fuenmayor Fernández, FJ. (2017). Calculation of the critical energy release rate Gc of the cement line in cortical bone combining experimental tests and finite element models. Engineering Fracture Mechanics. 184:168-182. https://doi.org/10.1016/j.engfracmech.2017.08.026S16818218

Fracture process in cortical bone: X-FEM analysis of microstructured models

This article was published in the serial International Journal of Fracture [© Springer Science and Business Media]. The definitive version is available at: http://dx.doi.org/10.1007/s10704-013-9814-7Bones tissues are heterogeneous materials that consist of various microstructural features at different length scales. The fracture process in cortical bone is affected significantly by the microstructural constituents and their heterogeneous distribution. Understanding mechanics of bone fracture is necessary for reduction and prevention of risks related to bone fracture. The aim of this study is to develop a finite-element approach to evaluate the fracture process in cortical bone at micro-scale. In this study, three microstructural models with various random distributions based on statistical realizations were constructed using the global model's framework together with a submodelling technique to investigate the effect of microstructural features on macroscopic fracture toughness and microscopic crack-propagation behaviour. Analysis of processes of crack initiation and propagation utilized the extended finite-element method using energy-based cohesive-segment scheme. The obtained results were compared with our experimental data and observations and demonstrated good agreement. Additionally, the microstructured cortical bone models adequately captured various damage and toughening mechanisms observed in experiments. The studies of crack length and fracture propagation elucidated the effect of microstructural constituents and their mechanical properties on the microscopic fracture propagation process. © 2013 Springer Science+Business Media Dordrecht

Cumulated energy consumption in the production of selected plants cultivated in Beskid Żywiecki region

Celem badań była analiza energochłonności skumulowanej w produkcji pszenicy i ziemniaków. Badania obejmowały 20 gospodarstw. Określono energię w strumieniach bezpośrednich nośników (olej napędowy, energia elektryczna), surowców i materiałów, pracy żywej i nakładów inwestycyjnych. Na podstawie przeprowadzonych badań stwierdzono, że istotnym czynnikiem mającym wpływ na nakłady energii skumulowanej w ziarnie pszenicy i plonie ziemniaków ma strumień surowców. Ponadto zaobserwowano, że energochłonność skumulowana w plonach z 1 ha badanych roślin w przeliczeniu na JZ, jest prawie dwukrotnie wyższa w bulwach ziemniaków w stosunku do ziarna pszenicy.The purpose of the research was to analyse cumulated energy consumption in wheat and potato production. The research covered 20 farms. The studies allowed to determine energy in direct carrier streams (diesel oil, electric energy), raw materials and materials, labour and investment outlays. Completed research provided grounds to state that the stream of raw materials is a significant factor affecting cumulated energy expenditure in wheat grain and potato crop. Moreover, it has been observed that cumulated energy consumption in crops from 1 ha of examined plants per JZ, is almost twice higher in potato tubers compared to that of wheat grain

The effects of porosity changes on aging cortical bone mechanics using an evolutionary Monte-Carlo Algorithm

International audienc

The impact of apple tree orchard area on cumulated energy consumption in fruit production

Celem badań była analiza wpływu powierzchni plantacji sadu jabłoniowego na energochłonność skumulowaną w produkcji jabłek. Badania obejmowały 30 plantacji. Określono energię w strumieniach bezpośrednich nośników (olej napędowy, energia elektryczna), surowców i materiałów, pracy żywej i nakładów inwestycyjnych. Na podstawie przeprowadzonych badań stwierdzono, że istotnym czynnikiem mającym wpływ na nakłady energii skumulowanej w jabłkach jest nie tylko powierzchnia plantacji, ale także obsada drzew na 1 ha. Również nie bez znaczenia na badane zależności ma plon, który jest zależny od odmiany i wieku plantacji. Zaobserwowano, że na strumień: mechanicznej pielęgnacji ugoru i drzew, nawożenia i opryskiwania, nakłady energii skumulowanej w produkcji jabłek są mniejsze na plantacjach powyżej 2 ha, w porównaniu z plantacjami mniejszymi - od 1ha.The purpose of the research was to analyse the impact of apple tree orchard plantation area on cumulated energy consumption in apple production sector. The research covered 30 plantations. Energy was determined in streams of direct carriers (diesel oil, electric energy), raw materials and materials, live labour and capital investment. Completed research allows to state that not only plantation area is an important factor affecting expenditure of energy cumulated in apples, but stock of trees per 1 ha as well. Crop has also significant impact on the examined relations, which is dependent on plantation variety and age. It has been observed that cumulated energy expenditure for apple production for the stream of: mechanical maintenance of idle land and trees, fertilisation and spraying, is smaller in case of large plantations, compared to small plantations with area under 1ha

The effects of porosity changes on aging cortical bone mechanics using an evolutionary Monte-Carlo Algorithm

International audienc

Explicit 3-Dimensional Modelling of Human Haversian Cortical Bone Failure

International audienc

Efficient sensitivity analysis of models with many model parameters to guide model personalization

Sensitivity indices obtained from a global variance-based sensitivity analysis can help by identifying which parameters need to be measured accurately and which parameters can be fixed for patientspecific applications. However, the computational cost for obtaining the sensitivity indices becomes prohibitively large with the current gold standard approach when the number of model parameters becomes too high (> 25). We propose an efficient two-step approach for model personalization. Using this approach personalization of an existing model could be performed using O(103) model runs, compared to O(105) runs had the current gold standard approach been used