The transient relationship between pressure and volume in the pediatric pulmonary system

Kent, Richard W.; Woods, William A.; Salzar, Robert S.; Damon, Andrew; Bass, Cameron R.

doi:10.1016/j.jbiomech.2009.04.027

Cited by 9 publications

(7 citation statements)

References 24 publications

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“…After testing different candidates, we found the modified exponential function [33] gave the best fits. A single parameter curve fitting was used to fit both force versus displacement curves and stress versus stretch-change curves.…”

Section: Methodsmentioning

confidence: 99%

Hyperelastic Material Properties of Mouse Skin under Compression

et al. 2013

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The skin is a dynamic organ whose complex material properties are capable of withstanding continuous mechanical stress while accommodating insults and organism growth. Moreover, synchronized hair cycles, comprising waves of hair growth, regression and rest, are accompanied by dramatic fluctuations in skin thickness in mice. Whether such structural changes alter skin mechanics is unknown. Mouse models are extensively used to study skin biology and pathophysiology, including aging, UV-induced skin damage and somatosensory signaling. As the skin serves a pivotal role in the transfer function from sensory stimuli to neuronal signaling, we sought to define the mechanical properties of mouse skin over a range of normal physiological states. Skin thickness, stiffness and modulus were quantitatively surveyed in adult, female mice (Mus musculus). These measures were analyzed under uniaxial compression, which is relevant for touch reception and compression injuries, rather than tension, which is typically used to analyze skin mechanics. Compression tests were performed with 105 full-thickness, freshly isolated specimens from the hairy skin of the hind limb. Physiological variables included body weight, hair-cycle stage, maturity level, skin site and individual animal differences. Skin thickness and stiffness were dominated by hair-cycle stage at young (6–10 weeks) and intermediate (13–19 weeks) adult ages but by body weight in mature mice (26–34 weeks). Interestingly, stiffness varied inversely with thickness so that hyperelastic modulus was consistent across hair-cycle stages and body weights. By contrast, the mechanics of hairy skin differs markedly with anatomical location. In particular, skin containing fascial structures such as nerves and blood vessels showed significantly greater modulus than adjacent sites. Collectively, this systematic survey indicates that, although its structure changes dramatically throughout adult life, mouse skin at a given location maintains a constant elastic modulus to compression throughout normal physiological stages.

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Section: Methodsmentioning

confidence: 99%

Hyperelastic Material Properties of Mouse Skin under Compression

et al. 2013

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“…The QLV formulation makes two main assumptions: (i) the nonlinear instantaneous elastic response can be separated from the time dependent relaxation response, and (ii) the relaxation response is independent of the amount of fiber stretch. The reduced relaxation function was represented as a three term Prony series of decaying exponentials (Kent et al, 2009):

G false(t false) = \sum_{i = 1}^{n} G_{i} e^{- β_{i} t} + G_{\infty},

where β i are time constants and G ∞ is the steady state response.…”

Section: Methodsmentioning

confidence: 99%

The passive properties of muscle fibers are velocity dependent

Rehorn

Schroer

Blemker

2014

Journal of Biomechanics

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The passive properties of skeletal muscle play an important role in muscle function. While the passive quasi-static elastic properties of muscle fibers have been well characterized, the dynamic visco-elastic passive behavior of fibers has garnered less attention. In particular, it is unclear how the visco-elastic properties are influenced by lengthening velocity, in particular for the range of physiologically relevant velocities. The goals of this work were to: (i) measure the effects of lengthening velocity on the peak stresses within single muscle fibers to determine how passive behavior changes over a range of physiologically relevant lengthening rates (0.1–10 Lo/s), and (ii) develop a mathematical model of fiber viscoelasticity based on these measurements. We found that passive properties depend on strain rate, in particular at the low loading rates (0.1–3 Lo/s), and that the measured behavior can be predicted across a range of loading rates and time histories with a quasi-linear viscoelastic model. In the future, these results can be used to determine the impact of viscoelastic behavior on intramuscular stresses and forces during a variety of dynamic movements.

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“…Recently, Schumann et al [11] used a gliding-SLICE method to fit P-V curves, which is able to evaluate the local continuous nonlinear compliance of the lungs. Both the airways and lungs are viscoelastic materials, thus, Kent et al recently developed a viscoelastic mechanical model [12], in which the change of airway pressure depends on the gas velocity as follows…”

Section: Macroscopic Modelsmentioning

confidence: 99%

Recent advances in theoretical models of respiratory mechanics

Huo

2012

Acta Mech Sin

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As an important branch of biomedical engineering, respiratory mechanics helps to understand the physiology of the respiratory system and provides fundamental data for developing such clinical technologies as ventilators. To solve different clinical problems, researchers have developed numerous models at various scales that describe biological and mechanical properties of the respiratory system. During the past decade, benefiting from the continuous accumulation of clinical data and the dramatic progress of biomedical technologies (e.g. biomedical imaging), the theoretical modeling of respiratory mechanics has made remarkable progress regarding the macroscopic properties of the respiratory process, complexities of the respiratory system, gas exchange within the lungs, and the coupling interaction between lung and heart. The present paper reviews the advances in the above fields and proposes potential future projects.

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The transient relationship between pressure and volume in the pediatric pulmonary system

Cited by 9 publications

References 24 publications

Hyperelastic Material Properties of Mouse Skin under Compression

Hyperelastic Material Properties of Mouse Skin under Compression

The passive properties of muscle fibers are velocity dependent

Recent advances in theoretical models of respiratory mechanics

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