mechanical tests
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A three-dimensional finite element model of a vascular smooth muscle cell is based on models published recently; it comprehends elements representing cell membrane, cytoplasm and nucleus, and a complex tensegrity structure representing the cytoskeleton. In contrast to previous models of eucaryotic cells, this tensegrity structure consists of several parts. Its external and internal parts number 30 struts, 60 cables each, and their nodes are interconnected by 30 radial members; these parts represent cortical, nuclear and deep cytoskeletons, respectively. This arrangement enables us to simulate load transmission from the extracellular space to the nucleus or centrosome via membrane receptors (focal adhesions); the ability of the model was tested by simulation of some mechanical tests with isolated vascular smooth muscle cells. Although material properties of components defined on the basis of the mechanical tests are ambiguous, modelling of different types of tests has shown the ability of the model to simulate substantial global features of cell behaviour, e.g. "action at a distance effect" or the global load-deformation response of the cell under various types of loading. Based on computational simulations, the authors offer a hypothesis explaining the scatter of experimental results of indentation tests.
- MeSH
- analýza metodou konečných prvků MeSH
- biologické modely MeSH
- buněčný převod mechanických signálů fyziologie MeSH
- cytoskelet MeSH
- lidé MeSH
- mechanický stres MeSH
- myocyty hladké svaloviny chemie cytologie fyziologie MeSH
- počítačová simulace MeSH
- svaly hladké cévní chemie cytologie fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
European Respiratory Monograph, ISSN 1025-448X vol. 6, monograph 16, August 2001
a-d, 320 s. : il., tab. ; 25 cm
- MeSH
- plicní ventilace MeSH
- respirační insuficience terapie MeSH
- umělé dýchání metody MeSH
- vysokofrekvenční ventilace metody přístrojové vybavení MeSH
- Publikační typ
- monografie MeSH
- Konspekt
- Patologie. Klinická medicína
- NLK Obory
- pneumologie a ftizeologie
This study concerns procedural aspects of planar biaxial experiments on aortic tissues that have not been exhaustively addressed in the literature. The following questions are explored. First, is there a difference in the apparent mechanical properties if the experiments are conducted in a force-controlled regime or a displacement-controlled regime. Second, does it matter whether the deformations of the surface are tracked from one side of the tissue or the other (luminal vs. abluminal surface). The study provides answers to these questions with the help of a series of experiments on porcine aortic tissue, constitutive modelling and statistical analysis. It was found that the loading protocol does not substantially affect the constitutive response, while the surface orientation does.
- MeSH
- biomechanika MeSH
- mechanické jevy * MeSH
- mechanický stres MeSH
- prasata MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Soft tissues are pseudoelastic anisotropic materials; various formulas for their strain energy density have been proposed for modelling of their constitutive behaviour. However, the individual variance of elastic parameters is often more pronounced than their anisotropy, so that their constitutive relations can be modelled as either isotropic or orthotropic. Any hyperelastic model requires more mechanical tests to be input for an identification of its parameters than mere uniaxial tension tests; especially biaxial tension tests are very important also for isotropic hyperelastic materials. A design of a testing rig produced in cooperation of our institute with some local companies is presented. It enables us to carry out not only equibiaxial tension tests, but also some other biaxial tensile tests, because displacements in both mutually perpendicular directions can be controlled independently. The proposal of various types of biaxial tests is presented in the paper, with examples of their realization with porcine aortic wall tissue. The contribution focuses on ways of evaluation of the results and on identification of parameters of various constitutive models. The use of more mechanical tests in identification of constitutive parameters can improve the predictive capability of the models substantially.
- MeSH
- arterie fyziologie MeSH
- biomechanika MeSH
- elastická tkáň fyziologie MeSH
- mechanický stres MeSH
- pevnost v tahu MeSH
- počítačová simulace MeSH
- pojivová tkáň fyziologie MeSH
- prasata MeSH
- pružnost MeSH
- statistické modely MeSH
- teoretické modely MeSH
- testování materiálů MeSH
- zobrazování trojrozměrné MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- hodnotící studie MeSH
As-cast Mg-Sn, Mg-Ga and Mg-In alloys containing 1-7 wt.% of alloying elements were studied in this work. Structural and chemical analysis of the alloys was performed by using light and scanning electron microscopy, energy dispersive spectrometry, x-ray diffraction, x-ray photoelectron spectroscopy and glow discharge spectrometry. Mechanical properties were determined by Vickers hardness measurements and tensile testing. Corrosion behavior in a simulated physiological solution (9 g/l NaCl) was studied by immersion tests and potentiodynamic measurements. The cytotoxicity effect of the alloys on human osteosarcoma cells (U-2 OS) was determined by an indirect contact assay. Structural investigation revealed the dendritic morphology of the as-cast alloys with the presence of secondary eutectic phases in the Mg-Sn and Mg-Ga alloys. All the alloying elements showed hardening and strengthening effects on magnesium. This effect was the most pronounced in the case of Ga. All the alloying elements at low concentrations of approximately 1 wt.% were also shown to positively affect the corrosion resistance of Mg. But at higher concentrations of Ga and Sn the corrosion resistance worsened due to galvanic effects of secondary phases. Cytotoxicity tests indicated that Ga had the lowest toxicity, followed by Sn. The most severe toxicity was observed in the case of In.
- MeSH
- biokompatibilní materiály chemie farmakologie MeSH
- buněčná smrt účinky léků MeSH
- fotoelektronová spektroskopie MeSH
- koroze MeSH
- kovy farmakologie MeSH
- lidé MeSH
- mechanické jevy účinky léků MeSH
- mikroskopie elektronová rastrovací MeSH
- nádorové buněčné linie MeSH
- pevnost v tahu účinky léků MeSH
- potenciometrie MeSH
- slitiny chemie farmakologie MeSH
- testování materiálů * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
