Acta Mechanica Sinica
     Acta Mechanica Sinica
  Acta Mechanica Sinica--2021, 37 (2)   Published: 25 February 2021
Preface: selected topics in Biomechanics
Jizeng Wang, Xiqiao Feng, Paolo Bisegna, Antonio DeSimone
Mechanics of tubular helical assemblies: ensemble response to axial compression and extension
Jacopo Quaglierini, Alessandro Lucantonio, Antonio DeSimone
Nature and technology often adopt structures that can be described as tubular helical assemblies. However, the role and mechanisms of these structures remain elusive. In this paper, we study the mechanical response under compression and extension of a tubular assembly composed of 8 helical Kirchhoff rods, arranged in pairs with opposite chirality and connected by pin joints, both analytically and numerically. We first focus on compression and find that, whereas a single helical rod would buckle,...
Mechanics of molecular beacons for mRNA detecting
Yulong Gong, Xinghua Shi
Decoding genetic information is crucial for gene therapy and cancer diagnosis, which has attracted growing interest in the field of clinical medicine and life science. In this study, we conducted a comprehensive exploration to obtain the detection mechanism of molecular beacons from a mechanics point of view. The potential energy function of molecular beacon/target system is established firstly, based on which the profile of molecular beacons is solved by genetic algorithm optimization. The leng...
Characterizing in situ poroelastic properties of cytoplasm by the translation of a rigid spherical inclusion
Xuechao Sun, Xin Chen, Ming Wang, Moxiao Li, Yonggang Liu, Shaobao Liu, Tian Jian Lu
Poroelasticity of cytoplasm is a rate- and size-dependent biphasic material behavior that reflects the normal activities and pathological states of cells, mainly caused by the migration of fluid molecules and the deformation of porous solid skeleton (protein scaffold). While micro/nano-indentation tests have been extensively used to characterize the poroelasticity of a cell, characterizing the in situ poroelasticity of cytoplasm remains elusive. In this study, based on the theory of the translat...
Mechanotransduction of liver sinusoidal endothelial cells under varied mechanical stimuli
Xinyu Shu, Ning Li, Yi Wu, Wang Li, Xiaoyu Zhang, Peiwen Li, Dongyuan Lü, Shouqin Lü, Mian Long
Liver sinusoidal endothelial cells (LSECs) are the gatekeeper of liver to maintain hepatic homeostasis. They are formed into the highly specialized endothelium between vascular lumen and the space of Disse and are mechanosensitive to respond varied microenvironments. Shear stress and mechanical stretch induced by blood perfusion and substrate stiffness enhancement derived from deposition of extracellular matrix (ECM) are major mechanical stimuli that surround LSECs. This review introduces how LS...
Role of endothelial cells in the regulation of mechanical microenvironment on tumor progression
Changling Wei, Mei Tang, Zhiling Xu, Li Yang, Yonggang Lv
Majority of cancer patients die from cancer metastases. The physical stimulation produced by microenvironment regulates invasive behavior of cancer cells. Blood vessel is one of the pathways?for cancer to metastasize, in which tumor cells need to cross the endothelial barrier for intravasation and extravasation. Tumor vessels are arranged in untraditional hierarchies and characterized with rupture, bend, swell and high permeability that are beneficial to intravasation of cancer cell. Abnormal ve...
Effects of domain unfolding and catch-like dissociation on the collective behavior of integrin-fibronectin bond clusters
Ji Lin, Yanzhong Wang, Jin Qian

To gain more understanding of cell-matrix adhesion, we consider an idealized theoretical model of a cluster of integrin- fibronectin bonds at the cell-matrix interface subjected to a dynamic ramping. The distributions of bond traction and interfacial deformation are assumed to obey classical elastic equations, whereas the dissociation/association of individual bonds as well as unfolding/refolding of fibronectin domains are described by stochastic equations. Through stochastic-elasticity coupl...

Lyapunov stability of competitive cells dynamics in tumor mechanobiology
Angelo Rosario Carotenuto, Arsenio Cutolo, Stefania Palumbo, Massimiliano Fraldi
Poromechanics plays a key role in modelling hard and soft tissue behaviours, by providing a thermodynamic framework in which chemo-mechanical mutual interactions among fluid and solid constituents can be consistently rooted, at different scale levels. In this context, how different biological species (including cells, extra-cellular components and chemical metabolites) interplay within complex environments is studied for characterizing the mechanobiology of tumor growth, governed by intratumoral...
On the electrophysiology of the atrial fast conduction system: an uncertain quantification study
Giulio Del Corso, Roberto Verzicco, Francesco Viola

Cardiac modeling entails the epistemic uncertainty of the input parameters, such as bundles and chambers geometry, electrical conductivities and cell parameters, thus calling for an uncertainty quantification (UQ) analysis. Since the cardiac activation and the subsequent muscular contraction is provided by a complex electrophysiology system made of interconnected conductive media, we focus here on the fast conductivity structures of the atria (internodal pathways) with the aim of identifying ...

Impact of leg bending in the patient-specific computational fluid dynamics of popliteal stenting
A. Ferrarini, A. Finotello, G. Salsano, F. Auricchio, D. Palombo, G. Spinella, B. Pane, M. Conti
Endovascular treatment of the femoro-popliteal artery has recently become a valuable therapeutic option for popliteal arterial aneurysms. However, its efficacy remains controversial due to the relatively high rate of complications, such as stent occlusion as result of intra-stent thrombosis. The elucidation of the interplay among vessel geometrical features, local hemodynamics, and leg bending seems crucial to understand onset and progression of popliteal intra-stent thrombosis. To this aim, pat...
Micro computed tomography based finite element models for elastic and strength properties of 3D printed glass scaffolds
Erica Farina, Dario Gastaldi, Francesco Baino, Enrica Vernè, Jonathan Massera, Gissur Orlygsson, Pasquale Vena
In this study, the mechanical properties of glass scaffolds manufactured by robocasting are investigated through micro computed tomography (μ-CT) based finite element modeling. The scaffolds are obtained by printing fibers along two perpendicular directions on parallel layers with a 90? tilting between two adjacent layers. A parametric study is first presented with the purpose to assess the effect of the major design parameters on the elastic and strength prope...
Biomechanical modeling of metal screw loadings on the human vertebra
Leonardo Molinaric, Cristina Falcinelli, Alessio Gizzi, Alberto Di Martino
During spinal fusion surgery screws, angled screw insertion can provide a more favorable stress distribution reducing failure events (screw breakage and loosening). Finite element (FE) analysis can be employed for identifying the optimal insertion path, preventing stress concentrations, and ensuring a lower failure incidence. In this work, a patient-specific FE model of L4 vertebra, virtually implanted with two pedicle screws, was obtained from diagnostic images and numerically investigated. Lin...
Intra- and inter-specific scaling laws of plants and animals
Jiahang Li, Hao Wu, Ghassan S. Kassab, Wenchang Tan, Yunlong Huo
The allometric scaling laws of metabolism in 447 animal and 1200 plant species showed convex and concave curvatures between mass and metabolic rate, respectively. The objective of the study is to explain the difference of curvatures between animals and plants based on fractal models. Several intraspecific scaling laws were derived from an asymmetric vascular tree with the fractal dimension (i.e., a in $k_{1}^{a}$ + $k_{2}^{a}$ +…=1, where ki refers ...
Coupled pore network model for the cathode gas diffusion layer in PEM fuel cells
Hamed Gholipour, Mohammad J. Kermani, Rahim Zamanian
A pore network model (PNM) is developed for gas diffusion layer (GDL) in the cathode side of polymer electrolyte membrane fuel cells (PEMFCs). The model is coupled to network models of reactant oxygen and electron transport inside GDL and also to simple models of catalyst layer and membrane. The coupled model captures the simultaneous effect of reactant and charge access to reaction sites and the resulting water generation, allowing it a transient nature up to reaching the steady state, which is...
Quantitative characterization of damage-aggravation effect caused by progressive damage
Qindong Lin, Shihai Li, Chun Feng, Dong Zhou
Aiming at the progressive damage phenomenon in geotechnical field, it attempts to study the effect of progressive damage on the macro-bearing capacity. Firstly, based on the theoretical analysis of a two-dimensional plane inside representative volume element, it is proposed that progressive damage will occur if the bearing capacity of microplanes is different. Besides, “damage-aggravation effect” is proposed according to the difference between the macro-bearing capacity of entire...
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