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https://www.readbyqxmd.com/read/28106451/superfluid-behavior-of-active-suspensions-from-diffusive-stretching
#1
S C Takatori, J F Brady
The current understanding is that the non-Newtonian rheology of active matter suspensions is governed by fluid-mediated hydrodynamic interactions associated with active self-propulsion. Here we discover an additional contribution to the suspension shear stress that predicts both thickening and thinning behavior, even when there is no nematic ordering of the microswimmers with the imposed flow. A simple micromechanical model of active Brownian particles in homogeneous shear flow reveals the existence of off-diagonal shear components in the swim stress tensor, which are independent of hydrodynamic interactions and fluid disturbances...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106420/long-lived-neighbors-determine-the-rheological-response-of-glasses
#2
M Laurati, P Maßhoff, K J Mutch, S U Egelhaaf, A Zaccone
Glasses exhibit a liquidlike structure but a solidlike rheological response with plastic deformations only occurring beyond yielding. Thus, predicting the rheological behavior from the microscopic structure is difficult, but important for materials science. Here, we consider colloidal suspensions and propose to supplement the static structural information with the local dynamics, namely, the rearrangement and breaking of the cage of neighbors. This is quantified by the mean squared nonaffine displacement and the number of particles that remain nearest neighbors for a long time, i...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28104528/cannabinoid-receptor-type-2-cb2-as-one-of-the-candidate-genes-in-human-carotid-plaque-imaging-evalu1ation-of-the-novel-radiotracer-11-c-rs-016-targeting-cb2-in-atherosclerosis
#3
Romana Meletta, Roger Slavik, Linjing Mu, Zoran Rancic, Nicole Borel, Roger Schibli, Simon M Ametamey, Stefanie D Krämer, Adrienne Müller Herde
INTRODUCTION: Endarterectomized human atherosclerotic plaques are a valuable basis for gene expression studies to disclose novel imaging biomarkers and therapeutic targets, such as the cannabinoid receptor type 2 (CB2). In this work, CB2 is expressed on activated immune cells, which are abundant in inflamed plaques. We evaluated the CB2-specific radiotracer [(11)C]RS-016 for imaging vascular inflammation in human and mouse atherosclerotic lesions. METHODS: The differential gene expression of microscopically classified human carotid plaques was evaluated using quantitative polymerase chain reaction...
January 8, 2017: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/28102332/dynamic-modeling-of-uteroplacental-blood-flow-in-iugr-indicates-vortices-and-elevated-pressure-in-the-intervillous-space-a-pilot-study
#4
Christian J Roth, Eva Haeussner, Tanja Ruebelmann, Franz V Koch, Christoph Schmitz, Hans-Georg Frank, Wolfgang A Wall
Ischemic placental disease is a concept that links intrauterine growth retardation (IUGR) and preeclampsia (PE) back to insufficient remodeling of uterine spiral arteries. The rheological consequences of insufficient remodeling of uterine spiral arteries were hypothesized to mediate the considerably later manifestation of obstetric disease. However, the micro-rheology in the intervillous space (IVS) cannot be examined clinically and rheological animal models of the human IVS do not exist. Thus, an in silico approach was implemented to provide in vivo inaccessible data...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28100643/fluid-shear-stress-increases-transepithelial-transport-of-ca2-in-ciliated-distal-convoluted-and-connecting-tubule-cells
#5
Sami G Mohammed, Francisco J Arjona, Femke Latta, René J M Bindels, Ronald Roepman, Joost G J Hoenderop
In kidney, transcellular transport of Ca(2+) is mediated by transient receptor potential vanilloid 5 and Na(+)-Ca(2+) exchanger 1 proteins in distal convoluted and connecting tubules (DCT and CNT, respectively). It is not yet understood how DCT/CNT cells can adapt to differences in tubular flow rate and, consequently, Ca(2+) load. This study aims to elucidate the molecular mechanisms by which DCT/CNT cells sense fluid dynamics to control transepithelial Ca(2+) reabsorption and whether their primary cilia play an active role in this process...
January 18, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28100636/centriole-splitting-caused-by-loss-of-the-centrosomal-linker-protein-c-nap1-reduces-centriolar-satellite-density-and-impedes-centrosome-amplification
#6
Anne-Marie Flanagan, Elena Stavenschi, Shivakumar Basavaraju, David Gaboriau, David A Hoey, Ciaran G Morrison
Duplication of the centrosomes is a tightly regulated process. Abnormal centrosome numbers can impair cell division and cause changes in how cells migrate. Duplicated centrosomes are held together by a proteinaceous linker made up of rootletin filaments anchored to the centrioles by C-NAP1. This linker is removed in a NEK2A kinase-dependent manner as mitosis begins. To explore C-NAP1 activities in regulating centrosome activities, we used genome editing to ablate it. C-NAP1 null cells were viable and had an increased frequency of premature centriole separation, accompanied by reduced density of the centriolar satellites, with re-expression of C-NAP1 rescuing both these phenotypes...
January 18, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28098159/fluid-shear-stress-activates-yap1-to-promote-cancer-cell-motility
#7
Hyun Jung Lee, Miguel F Diaz, Katherine M Price, Joyce A Ozuna, Songlin Zhang, Eva M Sevick-Muraca, John P Hagan, Pamela L Wenzel
Mechanical stress is pervasive in egress routes of malignancy, yet the intrinsic effects of force on tumour cells remain poorly understood. Here, we demonstrate that frictional force characteristic of flow in the lymphatics stimulates YAP1 to drive cancer cell migration; whereas intensities of fluid wall shear stress (WSS) typical of venous or arterial flow inhibit taxis. YAP1, but not TAZ, is strictly required for WSS-enhanced cell movement, as blockade of YAP1, TEAD1-4 or the YAP1-TEAD interaction reduces cellular velocity to levels observed without flow...
January 18, 2017: Nature Communications
https://www.readbyqxmd.com/read/28097631/force-dependent-calcium-signaling-and-its-pathway-of-human-neutrophils-on-p-selectin-in-flow
#8
Bing Huang, Yingchen Ling, Jiangguo Lin, Xin Du, Ying Fang, Jianhua Wu
P-selectin engagement of P-selectin glycoprotein ligand-1 (PSGL-1) causes circulating leukocytes to roll on and adhere to the vascular surface, and mediates intracellular calcium flux, a key but unclear event for subsequent arresting firmly at and migrating into the infection or injured tissue. Using a parallel plate flow chamber technique and intracellular calcium ion detector (Fluo-4 AM), the intracellular calcium flux of firmly adhered neutrophils on immobilized P-selectin in the absence of chemokines at various wall shear stresses was investigated here in real time by fluorescence microscopy...
January 18, 2017: Protein & Cell
https://www.readbyqxmd.com/read/28097479/structural-and-cooperative-length-scales-in-polymer-gels
#9
Baudouin Géraud, Loren Jørgensen, Christophe Ybert, Hélène Delanoë-Ayari, Catherine Barentin
Understanding the relationship between the material structural details, the geometrical confining constraints, the local dynamical events and the global rheological response is at the core of present investigations on complex fluid properties. In the present article, this problem is addressed on a model yield stress fluid made of highly entangled polymer gels of Carbopol which follows at the macroscopic scale the well-known Herschel-Bulkley rheological law. First, performing local rheology measurements up to high shear rates ([Formula: see text] s(-1))and under confinement, we evidence unambiguously the breakdown of bulk rheology associated with cooperative processes under flow...
January 2017: European Physical Journal. E, Soft Matter
https://www.readbyqxmd.com/read/28094392/3d-printing-of-self-assembling-thermoresponsive-nanoemulsions-into-hierarchical-mesostructured-hydrogels
#10
Lilian C Hsiao, Abu Zayed Md Badruddoza, Li-Chiun Cheng, Patrick S Doyle
Spinodal decomposition and phase transitions have emerged as viable methods to generate a variety of bicontinuous materials. Here, we show that when arrested phase separation is coupled to the time scales involved in three-dimensional (3D) printing processes, hydrogels with multiple length scales spanning nanometers to millimeters can be printed with high fidelity. We use an oil-in-water nanoemulsion-based ink with rheological and photoreactive properties that satisfy the requirements of stereolithographic 3D printing...
January 17, 2017: Soft Matter
https://www.readbyqxmd.com/read/28093887/collagen-hydrogel-scaffold-promotes-mesenchymal-stem-cell-and-endothelial-cell-coculture-for-bone-tissue-engineering
#11
Bao-Ngoc B Nguyen, Rebecca A Moriarty, Tim Kamalitdinov, Julie M Etheridge, John P Fisher
The generation of functional, vascularized tissues is a key challenge for the field of tissue engineering. Before clinical implantations of such tissue engineered bone constructs can succeed, tactics to promote neovascularization need to be strengthened. We have previously demonstrated that the tubular perfusion system (TPS) bioreactor is an effective culturing method to augment osteogenic differentiation and maintain viability of human mesenchymal stem cells (hMSC). Here, we devised a strategy to address the need for a functional microvasculature by designing an in vitro coculture system that simultaneously cultures osteogenic differentiating hMSCs with endothelial cells (ECs)...
January 17, 2017: Journal of Biomedical Materials Research. Part A
https://www.readbyqxmd.com/read/28092504/wall-shear-rate-measurement-validation-of-a-new-method-through-multiphysics-simulations
#12
Stefano Ricci, Abigail Swillens, Alessandro Ramalli, Patrick Segers, Piero Tortoli
Wall shear stress is known to affect the vessel endothelial function and to be related to important pathologies like the development of atherosclerosis. It is defined as the product of the blood viscosity by the blood velocity gradient at the wall position, i.e., the wall shear rate (WSR). The WSR measurement is particularly challenging in important cardiovascular sites, like the carotid bifurcation, because of the related complex flow configurations characterized by high spatial and temporal gradients, wall movement, and clutter noise...
January 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28091952/nanometric-cutting-of-silicon-with-an-amorphous-crystalline-layered-structure-a-molecular-dynamics-study
#13
Jinshi Wang, Fengzhou Fang, Xiaodong Zhang
Materials with specific nanometric layers are of great value in both theoretical and applied research. The nanometric layer could have a significant influence on the response to the mechanical loading. In this paper, the nanometric cutting on the layered systems of silicon has been studied by molecular dynamics. This kind of composite structure with amorphous layer and crystalline substrate is important for nanomachining. Material deformation, stress status, and chip formation, which are the key issues in nano-cutting, are analyzed...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28091803/a-study-of-hyperelastic-models-for-predicting-the-mechanical-behavior-of-extensor-apparatus
#14
Nahid Elyasi, Kimia Karimi Taheri, Keivan Narooei, Ali Karimi Taheri
In this research, the nonlinear elastic behavior of human extensor apparatus was investigated. To this goal, firstly the best material parameters of hyperelastic strain energy density functions consisting of the Mooney-Rivlin, Ogden, invariants, and general exponential models were derived for the simple tension experimental data. Due to the significance of stress response in other deformation modes of nonlinear models, the calculated parameters were used to study the pure shear and balance biaxial tension behavior of the extensor apparatus...
January 16, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28090032/the-influence-of-elastic-moduli-of-core-materials-on-shear-stress-distributions-at-the-adhesive-interface-in-resin-built-up-teeth
#15
Ayaka Chiba, Takashi Hatayama, Kimisuke Kainose, Masatoshi Nakajima, David H Pashley, Noriyuki Wakabayashi, Junji Tagami
This study aimed to investigate shear stress distributions in resin built-up teeth using resin composites of varying elastic moduli (E), with or without fiber posts. Three-dimensional mathematical models of a root-filled mandibular premolar tooth were constructed. Resin post and cores were built-up with resin composites of three different E: 12,000, 18,000 and 24,000 MPa, with or without fiber posts. Finite element linear analysis was performed to calculate shear stress distributions at bonding interface between resin core and dentin...
January 13, 2017: Dental Materials Journal
https://www.readbyqxmd.com/read/28089874/mathematical-modelling-of-cell-layer-growth-in-a-hollow-fibre-bioreactor
#16
Lloyd A C Chapman, Jonathan P Whiteley, Helen M Byrne, Sarah L Waters, Rebecca J Shipley
Generating autologous tissue grafts of a clinically useful volume requires efficient and controlled expansion of cell populations harvested from patients. Hollow fibre bioreactors show promise as cell expansion devices, owing to their potential for scale-up. However, further research is required to establish how to specify appropriate hollow fibre bioreactor operating conditions for expanding different cell types. In this study we develop a simple model for the growth of a cell layer seeded on the outer surface of a single fibre in a perfused hollow fibre bioreactor...
January 12, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28078260/rheological-and-pasting-properties-of-naked-barley-flour-as-modified-by-guar-xanthan-and-locust-bean-gums
#17
Sung-Jin Yoon, Youngseung Lee, Byoungseung Yoo
To understand the effects of adding different gums (guar, xanthan, and locust bean gums) on naked barley flour (NBF), the rheological and pasting properties of NBF-gum mixtures were measured at different gum concentrations (0, 0.3, and 0.6% w/w). Steady shear rheological properties were determined by rheological parameters for power law and Casson models. All samples showed a clear trend of shear-thinning behavior (n=0.16~0.48) and had a non-Newtonian nature with yield stress. Consistency index, apparent viscosity, and yield stress values increased with an increase in gum concentration...
December 2016: Preventive Nutrition and Food Science
https://www.readbyqxmd.com/read/28078170/computational-fluid-dynamics-assisted-characterization-of-parafoveal-hemodynamics-in-normal-and-diabetic-eyes-using-adaptive-optics-scanning-laser-ophthalmoscopy
#18
Yang Lu, Miguel O Bernabeu, Jan Lammer, Charles C Cai, Martin L Jones, Claudio A Franco, Lloyd Paul Aiello, Jennifer K Sun
Diabetic retinopathy (DR) is the leading cause of visual loss in working-age adults worldwide. Previous studies have found hemodynamic changes in the diabetic eyes, which precede clinically evident pathological alterations of the retinal microvasculature. There is a pressing need for new methods to allow greater understanding of these early hemodynamic changes that occur in DR. In this study, we propose a noninvasive method for the assessment of hemodynamics around the fovea (a region of the eye of paramount importance for vision)...
December 1, 2016: Biomedical Optics Express
https://www.readbyqxmd.com/read/28075525/dynamic-remodeling-of-arteriolar-collaterals-after-acute-occlusion-in-chick-chorioallantoic-membrane
#19
Weiwei Xiang, Bettina Reglin, Bianca Nitzsche, Martin Maibier, Wenwei Rong, Björn Hoffmann, Alfredo Ruggeri, Pedro Guimarães, Timothy W Secomb, Axel R Pries
After arteriolar occlusion, collaterals enlarge and initially elevated wall shear stress (WSS) normalizes. While most previous studies focused on endpoints of such adaptive changes in larger collaterals the present investigation aimed to continuously determine the relation between WSS and diameter in microvascular collaterals during adaptive reactions METHODS: In Hamburger-Hamilton stage 40 chick chorioallantoic membranes (CAMs), junction points between arteriolar segments were identified and the third upstream segment on one side was occluded...
January 11, 2017: Microcirculation: the Official Journal of the Microcirculatory Society, Inc
https://www.readbyqxmd.com/read/28074964/how-the-alignment-of-adsorbed-ortho-h-pairs-determines-the-onset-of-selective-carbon-nanotube-etching
#20
U Khalilov, A Bogaerts, B Xu, T Kato, T Kaneko, E C Neyts
Unlocking the enormous technological potential of carbon nanotubes strongly depends on our ability to specifically produce metallic or semiconducting tubes. While selective etching of both has already been demonstrated, the underlying reasons, however, remain elusive as yet. We here present computational and experimental evidence on the operative mechanisms at the atomic scale. We demonstrate that during the adsorption of H atoms and their coalescence, the adsorbed ortho hydrogen pairs on single-walled carbon nanotubes induce higher shear stresses than axial stresses, leading to the elongation of HC-CH bonds as a function of their alignment with the tube chirality vector, which we denote as the γ-angle...
January 11, 2017: Nanoscale
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