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fluid structure interaction

Jun Qiu, Fang-Fang Li
Mechanical properties of a single cell and its mechanical response under stimulation play an important role in regulating interactions between cell and extracellular matrix and affecting mechanotransduction. Osteocytes exhibit solid-like viscoelastic behavior in response to the interstitial fluid shear resulting from tissue matrix deformation. This study intends to quantitatively describe the mechanical behavior of osteocytes combining in vitro experiment and fluid-structure interaction (FSI) finite element (FE) model...
October 17, 2016: Biomechanics and Modeling in Mechanobiology
Maurice Filo, Fadi Karameh, Mariette Awad
The cochlea is an indispensable preliminary processing stage in auditory perception that employs mechanical frequency-tuning and electrical transduction of incoming sound waves. Cochlear mechanical responses are shown to exhibit active nonlinear spatiotemporal response dynamics (e.g., otoacoustic emission). To model such phenomena, it is often necessary to incorporate cochlear fluid-membrane interactions. This results in both excessively high-order model formulations and computationally intensive solutions that limit their practical use in simulating the model and analyzing its response even for simple single-tone inputs...
October 17, 2016: Biological Cybernetics
Ilaria Peluso, Mauro Serafini
Consumption of Tea (Camellia Sinensis) has been correlated with low incidence of chronic pathologies, such as cardiovascular diseases and cancers, in which oxidative stress is deeply involved. Tea catechins and theaflavins are, respectively, the bioactive phytochemicals responsible for the antioxidant activity of Green Tea (GT) and Black Tea (BT). Apart from the redox properties, tea catechins and theaflavins could have also pharmacological activities, such as lowering effects on glucose, lipid and uric acid (UA)...
October 16, 2016: British Journal of Pharmacology
Chao Tang, Haibo Huang, Peng Gao, Xi-Yun Lu
The self-propulsion of a three-dimensional flapping flexible plate near the ground is studied using an immersed boundary-lattice Boltzmann method for fluid flow and a finite-element method for plate motion. When the leading edge of the flexible plate is forced into a vertical oscillation near the ground, the entire plate moves freely due to the fluid-structure interaction. The mechanisms underlying the dynamics of the plate near the ground are elucidated. Based on the propulsive behaviors of the flapping plate, three distinct regimes due to the ground effect can be qualitatively identified...
September 2016: Physical Review. E
Stephanie Velázquez-Pérez, Gabriel Pérez-Ángel, Yuri Nahmad-Molinari
We present a numerical study of the spatial correlations of a quasi-two-dimensional granular fluid kept in a nonstatic steady state via vertical shaking. The simulations explore a wide range of vertical accelerations, restitution coefficients, and packing fractions, always staying below the crystallization limit. From the simulations we obtain the relevant pair distribution functions (PDFs), and effective potentials for the interparticle interaction are extracted from these PDFs via the Ornstein-Zernike equation with the Percus-Yevick closure...
September 2016: Physical Review. E
Jian Deng, Lubao Teng, C P Caulfield, Xuerui Mao
We propose a natural model to probe in a controlled fashion the instability of interacting vortex rings shed from the edge of an oblate spheroid disk of major diameter c, undergoing oscillations of frequency f_{0} and amplitude A. We perform a Floquet stability analysis to determine the characteristics of the instability modes, which depend strongly on the azimuthal (integer) wave number m. We vary two key control parameters, the Keulegan-Carpenter number K_{C}=2πA/c and the Stokes number β=f_{0}c^{2}/ν, where ν is the kinematic viscosity of the fluid...
September 2016: Physical Review. E
Jorge R Espinosa, Pablo Sampedro, Chantal Valeriani, Carlos Vega, Eduardo Sanz
We present a new simulation method for the calculation of crystal nucleation rates by computer simulation. The method is based on the use of molds to induce crystallization in state points where nucleation is a rare event. The mold is a cluster of potential energy wells placed in the lattice positions of the solid. The method has two distinct steps. In the first one the probability per unit volume of forming a sub-critical crystal cluster in the fluid is computed by means of thermodynamic integration. The thermodynamic route consists in gradually switching on an attractive interaction between the wells and the fluid particles...
October 11, 2016: Faraday Discussions
Xing Jiang, Hai-Bao Duan, Saeed I Khan, Miguel A Garcia-Garibay
Artificial molecular machines are expected to operate under conditions of very low Reynolds numbers with inertial forces orders of magnitude smaller than viscous forces. While these conditions are relatively well understood in bulk fluids, opportunities to assess the role of viscous forces in confined crystalline media are rare. Here we report one such example of diffusion-controlled rotation in crystals and its application as a probe for viscosity of MOF-confined solvent. We describe the preparation and characterization of three pillared paddlewheel MOFs, with 9,10-bis(4-pyridylethynyl)triptycene 3 as a pillar and molecular rotator, and three axially substituted dicarboxylate linkers with different lengths and steric bulk...
September 28, 2016: ACS Central Science
Hessam Malmir, Muhammad Sahimi, M Reza Rahimi Tabar
Understanding the properties of random packings of solid objects is of critical importance to a wide variety of fundamental scientific and practical problems. The great majority of the previous works focused, however, on packings of spherical and sphere-like particles. We report the first detailed simulation and characterization of packings of non-overlapping cubic particles. Such packings arise in a variety of problems, ranging from biological materials, to colloids and fabrication of porous scaffolds using salt powders...
October 11, 2016: Scientific Reports
José Rafael Bordin, Leandro B Krott
Confinement has been suggested as a tool to tune the self-assembly properties of nanoparticles, surfactants, polymers and colloids. In this way, we explore the phase diagram of Janus nanoparticles confined between two parallel walls using molecular dynamics simulations. A nanoparticle was modeled as a dimer made by one monomer that interacts via a standard Lennard Jones potential and another monomer that is modeled using a two-length scale shoulder potential. This specific design of the nanoparticle exhibits distinct self-assembled structures and a water-like diffusion anomaly in the bulk...
October 7, 2016: Physical Chemistry Chemical Physics: PCCP
S Voß, S Glaßer, T Hoffmann, O Beuing, S Weigand, K Jachau, B Preim, D Thévenin, G Janiga, P Berg
Computational Fluid Dynamics is intensively used to deepen the understanding of aneurysm growth and rupture in order to support physicians during therapy planning. However, numerous studies considering only the hemodynamics within the vessel lumen found no satisfactory criteria for rupture risk assessment. To improve available simulation models, the rigid vessel wall assumption has been discarded in this work and patient-specific wall thickness is considered within the simulation. For this purpose, a ruptured intracranial aneurysm was prepared ex vivo, followed by the acquisition of local wall thickness using μCT...
2016: Computational and Mathematical Methods in Medicine
Justin T Stimatze, David A Egolf, Jeffrey S Urbach
We report the results of simulations of suspensions of sheared rigid rods in the presence of strong attractive inter-particle interactions, using dissipative particle dynamics for a coarse-grained representation of the suspending fluid. We find that the combined effect of the attractive interactions and shear-induced alignment generically produces aggregates of aligned bundles when the contact points between rods are free to rotate. However, the introduction of substantial torsional stiffness to the inter-particle contacts recapitulates the disordered aggregates often observed in suspensions of high aspect ratio particles...
September 20, 2016: Soft Matter
Tino Colombi, Serge Braun, Thomas Keller, Achim Walter
The structure of compacted soils is characterised by decreased (macro-)porosity, which leads to increased mechanical impedance and decreased fluid transport rates, resulting in reduced root growth and crop productivity. Particularly in soils with high mechanical impedance, macropores can be used by roots as pathways of least resistance. This study investigated how different soil physical states relate to whole plant growth and whether roots grow towards spots with favourable soil physical conditions. Experiments were conducted under controlled and field conditions...
October 3, 2016: Science of the Total Environment
K Cao, P Sucosky
Computational characterizations of aortic valve hemodynamics have typically discarded the effects of coronary flow. The objective of this study was to complement our previous fluid-structure interaction aortic valve model with a physiologic coronary circulation model to quantify the impact of coronary flow on aortic sinus hemodynamics and leaflet wall shear stress (WSS). Coronary flow suppressed vortex development in the two coronary sinuses and altered WSS magnitude and directionality on the three leaflets, with the most substantial differences occurring in the belly and tip regions...
October 7, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Wenfen Zhang, Yanhao Zhang, Qiong Jiang, Wenjie Zhao, Ajuan Yu, Hong Chang, Ximei Lu, Fuwei Xie, Baoxian Ye, Shusheng Zhang
To satisfy the requirement of simultaneous extraction and characterization of diverse kinds of multi-target analytes, the preparation, characterization and application of a novel tetraazacalix[2]arene[2]triazine (TCT) coated magnetic nanoparticular (TCT MNP) adsorbent are presented in this paper. TCT assembles two benzene rings and two triazines with nitrogen cross-bridging links, which exhibits a unique structural framework and versatile recognition features based on the multiple recognition sites. These include π electron stacking, charge transfer, hydrogen bonding and ion-exchange...
October 7, 2016: Analytical Chemistry
Michel P Bonnin, Tom Van Hoof, Arnoud De Kok, Matthias Verstraete, Catherine Van der Straeten, Moreno Saffarini, Jan Victor
BACKGROUND: In Total Knee Arthroplasty (TKA), residual pain may be secondary to soft tissue impingements, which are difficult to visualize around chromium-cobalt implants using medical imaging, so their interactions remain poorly understood. The goal of this work was to establish a protocol for in-vitro imaging of the soft tissues around TKA, usable during throughout the range of motion (ROM). METHODS: The full size range of a commercially available TKA prosthesis was manufactured by 3D-printing in non-magnetic and non-radiopaque polymer and implanted in 12 cadaveric knees...
December 2016: Journal of Experimental Orthopaedics
Marie Portail, Karine Olu, Stanislas F Dubois, Elva Escobar-Briones, Yves Gelinas, Lénaick Menot, Jozée Sarrazin
In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB) cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA) cycles...
2016: PloS One
Olivier Gay, Marion Plaze, Catherine Oppenheim, Raphael Gaillard, Jean-Pierre Olié, Marie-Odile Krebs, Arnaud Cachia
BACKGROUND: Several clinical and radiological markers of early neurodevelopmental deviations have been independently associated with cognitive impairment in patients with schizophrenia. The aim of our study was to test the cumulative and/or interactive effects of these early neurodevelopmental factors on cognitive control (CC) deficit, a core feature of schizophrenia. METHODS: We recruited patients with first-episode schizophrenia-spectrum disorders, who underwent structural MRI...
September 23, 2016: Journal of Psychiatry & Neuroscience: JPN
M Simão, J M Ferreira, J Mora-Rodriguez, J Fragata, H M Ramos
This study explores the analysis of a new stent geometry from two typical stents used to treat the coronary artery disease. Two different finite element methods are applied with different boundary conditions to investigate the stenosis region. Computational fluid dynamics (CFD) models including fluid-structure interaction are used to assess the haemodynamic impact of two types of coronary stents implantation: (1) type 1-based on a strut-link stent geometry and (2) type 2-a continuous helical stent. Using data from a recent clinical stenosis, flow disturbances and consequent shear stress alterations introduced by the stent treatment are investigated...
September 26, 2016: Medical & Biological Engineering & Computing
Rongbao Zhao, Srinivas Aluri, I David Goldman
The proton-coupled folate transporter (PCFT-SLC46A1) is the mechanism by which folates are absorbed across the brush-border membrane of the small intestine. The transporter is also expressed in the choroid plexus and is required for transport of folates into the cerebrospinal fluid. Loss of PCFT function, as occurs in the autosomal recessive disorder "hereditary folate malabsorption" (HFM), results in a syndrome characterized by severe systemic and cerebral folate deficiency. Folate-receptor alpha (FRα) is expressed in the choroid plexus, and loss of function of this protein, as also occurs in an autosomal recessive disorder, results solely in "cerebral folate deficiency" (CFD), the designation for this disorder...
September 21, 2016: Molecular Aspects of Medicine
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