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Dynamic elastance

Floriana Burgio, Natalie Rimmer, Uwe Pieles, Johanna Buschmann, Marina Beaufils-Hugot
For the fabrication of appropriate bone tissue engineered constructs, several prerequisites should be fulfilled. It should offer long-term stability, allow proper cell attachment and proliferation, furthermore be osteoinductive and easy to be vascularized. Having these requirements as background, we fabricated a novel porous 3D-printed hydroxyapatite (HA) scaffold and treated it with oxygen plasma (OPT). MG-63 pre-osteoblast-seeded bone constructs allowed good cell attachment and proliferation, even better when cultivated in a perfusion flow bioreactor...
October 19, 2018: Biology Open
Linxiao Wu, Adrián Magaz, Tao Wang, Chaozong Liu, Arnold Darbyshire, Marilena Loizidou, Mark Emberton, Martin Birchall, Wenhui Song
This article contains data related to the research article entitled "Stiffness memory of indirectly 3D-printed elastomer nanohybrid regulates chondrogenesis and osteogenesis of human mesenchymal stem cells" [1] (Wu et al., 2018). Cells respond to the local microenvironment in a context dependent fashion and a continuous challenge is to provide a living construct that can adapt to the viscoelasticity changes of surrounding tissues. Several materials are attractive candidates to be used in tissue engineering, but conventional manufactured scaffolds are primarily static models with well-defined and stable stiffness that lack the dynamic biological nature required to undergo changes in substrate elasticity decisive in several cellular processes key during tissue development and wound healing...
December 2018: Data in Brief
Lisa Tran, Hye-Na Kim, Ningwei Li, Shu Yang, Kathleen J Stebe, Randall D Kamien, Martin F Haase
The ordering of nanoparticles into predetermined configurations is of importance to the design of advanced technologies. Here, we balance the interfacial energy of nanoparticles against the elastic energy of cholesteric liquid crystals to dynamically shape nanoparticle assemblies at a fluid interface. By adjusting the concentration of surfactant that plays the dual role of tuning the degree of nanoparticle hydrophobicity and altering the molecular anchoring of liquid crystals, we pattern nanoparticles at the interface of cholesteric liquid crystal emulsions...
October 2018: Science Advances
Nitin Kumar, Rui Zhang, Juan J de Pablo, Margaret L Gardel
Active materials are capable of converting free energy into directional motion, giving rise to notable dynamical phenomena. Developing a general understanding of their structure in relation to the underlying nonequilibrium physics would provide a route toward control of their dynamic behavior and pave the way for potential applications. The active system considered here consists of a quasi-two-dimensional sheet of short (≈1 μm) actin filaments driven by myosin II motors. By adopting a concerted theoretical and experimental strategy, new insights are gained into the nonequilibrium properties of active nematics over a wide range of internal activity levels...
October 2018: Science Advances
Lucia Carichino, Sarah D Olson
Changes in calcium concentration along the sperm flagellum regulate sperm motility and hyperactivation, characterized by an increased flagellar bend amplitude and beat asymmetry, enabling the sperm to reach and penetrate the ovum (egg). The signalling pathways by which calcium increases within the flagellum are well established. However, the exact mechanisms of how calcium regulates flagellar bending are still under investigation. We extend our previous model of planar flagellar bending by developing a fluid-structure interaction model that couples the 3D motion of the flagellum in a viscous Newtonian fluid with the evolving calcium concentration...
October 16, 2018: Mathematical Medicine and Biology: a Journal of the IMA
Toru Miyanaga, Yoshimichi Ueda, Aiko Miyanaga, Mikio Yagishita, Naoko Hama
To date, studies on mesenchymal tissue stem cells (MSCs) in the perichondrium have focused on in vitro analysis, and the dynamics of cartilage regeneration from the perichondrium in vivo remain largely unknown. We have attempted to apply cell and tissue engineering methodology for ear reconstruction using cultured chondrocytes. We hypothesized that by inducing angiogenesis with basic fibroblast growth factor (bFGF), MSCs or cartilage precursor cells would proliferate and differentiate into cartilage in vivo and that the regenerated cartilage would maintain its morphology over an extended period...
2018: Cellular & Molecular Biology Letters
Holger Flechsig, Yuichi Togashi
Recently, the design of mechanical networks with protein-inspired responses has become increasingly popular. Here, we review contributions which were motivated by studies of protein dynamics employing coarse-grained elastic network models. First, the concept of evolutionary optimization that we developed to design network structures which execute prescribed tasks is explained. We then review what presumably marks the origin of the idea to design complex functional networks which encode protein-inspired behavior, namely the design of an elastic network structure which emulates the cycles of ATP-powered conformational motion in protein machines...
October 13, 2018: International Journal of Molecular Sciences
G Y Jeong, J H Bak, B Yoo
Physical and rheological properties of agglomerated xanthan gum (XG), commonly used as a food thickener for the management of the patients with dysphagia (swallowing difficulty), were investigated at different concentrations (0, 2, 4, and 6% w/w) of hydroxypropyl methylcellulose (HPMC) as a binder in the fluidized bed agglomeration process. Flow characteristics of agglomerated XG powder were evaluated using Carr index (CI) and Hausner ratio (HR). The agglomerated XG powders obtained by HPMC binder exhibited a better flowability and higher porosity than the agglomerated powder without binder due to the size enlargement of XG powder...
October 12, 2018: International Journal of Biological Macromolecules
Giuseppe Amato, Giorgio Romano, Roberto Puleio, Antonino Agrusa, Thorsten Goetze, Eliana Gulotta, Luca Gordini, Enrico Erdas, Piergiorgio Calò
Despite undisputed improvements, prosthetics hernia repair continues to be affected by unacceptable rates of complications. Postoperative adverse events such as discomfort and chronic pain represent a subject of increasing concern among the surgical community. Poor quality biologic response, stiff scar plates, and mesh shrinkage, a typical effect of conventional static meshes and plugs, are all indicated as the main reasons for many of the complications related to inguinal hernia repair. Even the conventional concept of treatment based upon a supposed reinforcement of the groin consequent to the fibrotic incorporation of meshes, would appear to be inadequate in the light of the latest scientific evidence concerning the degenerative genesis of inguinal hernia...
October 14, 2018: Artificial Organs
Bartolomeo Coppola, Nicola Cappetti, Luciano Di Maio, Paola Scarfato, Loredana Incarnato
In this study, the possibility of using a layered silicate-reinforced polylactic acid (PLA) in additive manufacturing applications was investigated. In particular, the aim of this work was to study the influence of printing temperature in the 3D printing process of PLA/clay nanocomposites. For this reason, two PLA grades (4032D and 2003D, D-isomer content 1.5 and 4, respectively) were melt-compounded by a twin screw extruder with a layered silicate (Cloisite 30B) at 4 wt %. Then, PLA and PLA/clay feedstock filaments (diameter 1...
October 11, 2018: Materials
Yuri Lubomirsky, Chih-Hung Chen, Alain Karma, Eran Bouchbinder
The two-dimensional oscillatory crack instability, experimentally observed in a class of brittle materials under strongly dynamic conditions, has been recently reproduced by a nonlinear phase-field fracture theory. Here, we highlight the universal character of this instability by showing that it is present in materials exhibiting widely different near crack tip elastic nonlinearity, and by demonstrating that the oscillations wavelength follows a universal master curve in terms of dissipation-related and nonlinear elastic intrinsic length scales...
September 28, 2018: Physical Review Letters
M E Caplan, A S Schneider, C J Horowitz
The elastic properties of neutron star crusts are relevant for a variety of currently observable or near-future electromagnetic and gravitational wave phenomena. These phenomena may depend on the elastic properties of nuclear pasta found in the inner crust. We present large-scale classical molecular dynamics simulations where we deform nuclear pasta. We simulate idealized samples of nuclear pasta and describe their breaking mechanism. We also deform nuclear pasta that is arranged into many domains, similar to what is known for the ions in neutron star crusts...
September 28, 2018: Physical Review Letters
Tiancheng Han, Peng Yang, Ying Li, Dangyuan Lei, Baowen Li, Kedar Hippalgaonkar, Cheng-Wei Qiu
Since the advent of transformation optics and scattering cancelling technology, a plethora of unprecedented metamaterials, especially invisibility cloaks, have been successfully demonstrated in various communities, e.g., optics, acoustics, elastic mechanics, dc electric field, dc magnetic field, and thermotics. A long-held captivation is that transformation-optic metamaterials of anisotropic or noncentrosymmetric geometry (e.g., ellipsoids) commonly come along with parameter approximation/simplification or directional functions...
October 11, 2018: Advanced Materials
A Maskay, D M Hummels, M Pereira da Cunha
Surface acoustic wave resonators (SAWR) have found widespread usage in various modern consumer radiofrequency (RF) communications electronics, such as cellular phones, wireless devices, GPS devices, frequency control, and sensing applications. External mechanical vibrations modify a SAWR relative dimensions and the substrate's elastic properties, which alter the device's acoustic wave propagation velocity, and ultimately causes the SAWR RF response to change. Detecting vibrations is desirable for dynamic strain, or vibration sensing applications...
October 11, 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Arno A Veldhorst, Mauro C C Ribeiro
Molecular dynamics (MD) simulations of five ionic liquids based on 1-alkyl-3-methylimidazolium cations, [C n C1 im]+ , have been performed in order to calculate high-frequency elastic moduli and to evaluate heterogeneity of local elastic moduli. The MD simulations of [C n C1 im][NO3 ], n = 2, 4, 6, and 8, assessed the effect of domain segregation when the alkyl chain length increases, and [C8 C1 im][PF6 ] assessed the effect of strength of anion-cation interaction. Dispersion curves of excitation energies of longitudinal and transverse acoustic, LA and TA, modes were obtained from time correlation functions of mass currents at different wavevectors...
May 21, 2018: Journal of Chemical Physics
Yanchao Wang, ZhengMing Huang
Elasto-plastic models for composites can be classified into three categories in terms of a length scale, i.e., macro scale, meso scale, and micro scale (micromechanics) models. In general, a so-called multi-scale model is a combination of those at various length scales with a micromechanics one as the foundation. In this paper, a critical review is made for the elastoplastic models at the micro scale, and a comparative study is carried out on most popular analytical micromechanics models for the elastoplastic behavior of long fibrous composites subjected to a static load, meaning that creep and dynamic response are not concerned...
October 9, 2018: Materials
Saroj Kumar Nandi, N S Gov
The dynamics within active fluids, driven by internal activity of the self-propelled particles, is a subject of intense study in non-equilibrium physics. These systems have been explored using simulations, where the motion of a passive tracer particle is followed. Similar studies have been carried out for a soft glassy material that is driven by shearing its boundaries. In both types of systems the non-equilibrium motion have been quantified by defining a set of "effective temperatures", using both the tracer particle kinetic energy and the fluctuation-dissipation relation...
October 11, 2018: European Physical Journal. E, Soft Matter
Takehito Kikuchi, Yusuke Kobayashi, Mika Kawai, Tetsu Mitsumata
Magnetorheological elastomers (MREs) are stimulus-responsive soft materials that consist of polymeric matrices and magnetic particles. In this study, large-strain response of MREs with 5 vol % of carbonyl iron (CI) particles is experimentally characterized for two different conditions: (1) shear deformation in a uniform magnetic field; and (2), compression in a heterogeneous uniaxial magnetic field. For condition (1), dynamic viscoelastic measurements were performed using a rheometer with a rotor disc and an electric magnet that generated a uniform magnetic field on disc-like material samples...
October 6, 2018: International Journal of Molecular Sciences
Linxiao Wu, Adrián Magaz, Tao Wang, Chaozong Liu, Arnold Darbyshire, Marilena Loizidou, Mark Emberton, Martin Birchall, Wenhui Song
The cellular microenvironment is dynamic, remodeling tissues lifelong. The biomechanical properties of the extracellular matrix (ECM) influence the function and differentiation of stem cells. While conventional artificial matrices or scaffolds for tissue engineering are primarily static models presenting well-defined stiffness, they lack the responsive changes required in dynamic physiological settings. Engineering scaffolds with varying elastic moduli is possible, but often lead to stiffening and chemical crosslinking of the molecular structure with limited control over the scaffold architecture...
December 2018: Biomaterials
Ariela Tarnapolsky, Viatcheslav Freger
Quartz crystal microbalance with dissipation monitoring (QCM-D) is a powerful tool for studying adhesion, yet its use for analyzing depo-sition of microparticles and living cells on surfaces has been hampered by the difficulties of interpretation. Here we report a new quantita-tive model of QCM-D response, presented as an equivalent acoustic impedance circuit. As an essential feature, we propose to model the particle interaction with surrounding fluid as a freely oscillating sphere, which is a valid approximation for microparticles...
October 8, 2018: Analytical Chemistry
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