keyword
MENU ▼
Read by QxMD icon Read
search

Shear stress

keyword
https://www.readbyqxmd.com/read/28932856/on-the-apparent-yield-stress-in-non-brownian-magnetorheological-fluids
#1
Daniel Vågberg, Brian P Tighe
We use simulations to probe the flow properties of dense two-dimensional magnetorheological fluids. Prior results from both experiments and simulations report that the shear stress σ scales with strain rate [small gamma, Greek, dot above] as σ ∼ [small gamma, Greek, dot above](1-Δ), with values of the exponent ranging between 2/3 < Δ ≤ 1. However it remains unclear what properties of the system select the value of Δ, and in particular under what conditions the system displays a yield stress (Δ = 1)...
September 21, 2017: Soft Matter
https://www.readbyqxmd.com/read/28932763/a-co-culture-assay-to-determine-efficacy-of-tnf-%C3%AE-suppression-by-biomechanically-induced-human-bone-marrow-mesenchymal-stem-cells
#2
Miguel F Diaz, Siobahn M Evans, Scott D Olson, Charles S Cox, Pamela L Wenzel
The beneficial effects of mesenchymal stem cell (MSC)-based cellular therapies are believed to be mediated primarily by the ability odansf MSCs to suppress inflammation associated with chronic or acute injury, infection, autoimmunity, and graft-versus-host disease. To specifically address the effects of frictional force caused by blood flow, or wall shear stress (WSS), on human MSC immunomodulatory function, we have utilized microfluidics to model WSS at the luminal wall of arteries. Anti-inflammatory potency of MSCs was subsequently quantified via measurement of TNF-α production by activated murine splenocytes in co-culture assays...
August 20, 2017: Bio-protocol
https://www.readbyqxmd.com/read/28930091/proposal-to-assess-printability-of-bioinks-for-extrusion-based-bioprinting-and-evaluation-of-rheological-properties-governing-bioprintability
#3
Naomi Claire Paxton, Willi Smolan, Thomas Böck, Ferry P W Melchels, Juergen Groll, Tomasz Juengst
The development and formulation of printable inks for extrusion-based 3D bioprinting has been a major challenge in the field of biofabrication. Inks, often polymer solutions with the addition of crosslinking to form hydrogels, must not only display adequate mechanical properties for the chosen application, but also show high biocompatibility as well as printability. Here we describe a reproducible two-step method for the assessment of the printability of inks for bioprinting, focussing firstly on screening ink formulations to assess fibre formation and the ability to form 3D constructs before presenting a method for the rheological evaluation of inks to characterise the yield point, shear thinning and recovery behaviour...
September 20, 2017: Biofabrication
https://www.readbyqxmd.com/read/28929446/new-imaging-tools-in-cardiovascular-medicine-computational-fluid-dynamics-and-4d-flow-mri
#4
Keiichi Itatani, Shohei Miyazaki, Tokoki Furusawa, Satoshi Numata, Sachiko Yamazaki, Kazuki Morimoto, Rina Makino, Hiroko Morichi, Teruyasu Nishino, Hitoshi Yaku
Blood flow imaging is a novel technology in cardiovascular medicine and surgery. Today, two types of blood flow imaging tools are available: measurement-based flow visualization including 4D flow MRI (or 3D cine phase-contrast magnetic resonance imaging), or echocardiography flow visualization software, and computer flow simulation modeling based on computational fluid dynamics (CFD). MRI and echocardiography flow visualization provide measured blood flow but have limitations in temporal and spatial resolution, whereas CFD flow calculates the flow according to assumptions instead of flow measurement, and it has sufficiently fine resolution up to the computer memory limit, and it enables even virtual surgery when combined with computer graphics...
September 19, 2017: General Thoracic and Cardiovascular Surgery
https://www.readbyqxmd.com/read/28929388/fiber-reinforced-computational-model-of-the-aortic-root-incorporating-thoracic-aorta-and-coronary-structures
#5
Hossein Mohammadi, Raymond Cartier, Rosaire Mongrain
Cardiovascular diseases are still the leading causes of death in the developed world. The decline in the mortality associated with circulatory system diseases is accredited to development of new diagnostic and prognostic tools. It is well known that there is an inter relationship between the aortic valve impairment and pathologies of the aorta and coronary vessels. However, due to the limitations of the current tools, the possible link is not fully elucidated. Following our previous model of the aortic root including the coronaries, in this study, we have further developed the global aspect of the model by incorporating the anatomical structure of the thoracic aorta...
September 19, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28928371/aligning-cellulose-nanofibril-dispersions-for-tougher-fibers
#6
Pezhman Mohammadi, Matti S Toivonen, Olli Ikkala, Wolfgang Wagermaier, Markus B Linder
Nanocomposite materials made from cellulose show a great potential as future high-performance and sustainable materials. We show how high aspect ratio cellulose nanofibrils can be efficiently aligned in extrusion to fibers, leading to increased modulus of toughness (area under the stress-strain curve), Young's modulus, and yield strength by increasing the extrusion capillary length, decreasing its diameter, and increasing the flow rate. The materials showed significant property combinations, manifesting as high modulus of toughness (~28-31 MJ/m(3)) vs...
September 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28927643/a-combined-kinematic-and-kinetic-analysis-at-the-residuum-socket-interface-of-a-knee-disarticulation-amputee
#7
Jinghua Tang, Michael McGrath, Nick Hale, Liudi Jiang, Dan Bader, Piotr Laszczak, David Moser, Saeed Zahedi
The bespoke interface between a lower limb residuum and a prosthetic socket is critical for an amputee's comfort and overall rehabilitation outcomes. Analysis of interface kinematics and kinetics is important to gain full understanding of the interface biomechanics, which could aid clinical socket fit, rehabilitation and amputee care. This pilot study aims to investigate the dynamic correlation between kinematic movement and kinetic stresses at the interface during walking tests on different terrains. One male, knee disarticulation amputee participated in the study...
September 15, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28925962/strengthening-of-existing-bridge-structures-for-shear-and-bending-with-carbon-textile-reinforced-mortar
#8
Martin Herbrand, Viviane Adam, Martin Classen, Dominik Kueres, Josef Hegger
Increasing traffic loads and changes in code provisions lead to deficits in shear and flexural capacity of many existing highway bridges. Therefore, a large number of structures are expected to require refurbishment and strengthening in the future. This projection is based on the current condition of many older road bridges. Different strengthening methods for bridges exist to extend their service life, all having specific advantages and disadvantages. By applying a thin layer of carbon textile-reinforced mortar (CTRM) to bridge deck slabs and the webs of pre-stressed concrete bridges, the fatigue and ultimate strength of these members can be increased significantly...
September 19, 2017: Materials
https://www.readbyqxmd.com/read/28924611/size-effects-resolve-discrepancies-in-40-years-of-work-on-low-temperature-plasticity-in-olivine
#9
Kathryn M Kumamoto, Christopher A Thom, David Wallis, Lars N Hansen, David E J Armstrong, Jessica M Warren, David L Goldsby, Angus J Wilkinson
The strength of olivine at low temperatures and high stresses in Earth's lithospheric mantle exerts a critical control on many geodynamic processes, including lithospheric flexure and the formation of plate boundaries. Unfortunately, laboratory-derived values of the strength of olivine at lithospheric conditions are highly variable and significantly disagree with those inferred from geophysical observations. We demonstrate via nanoindentation that the strength of olivine depends on the length scale of deformation, with experiments on smaller volumes of material exhibiting larger yield stresses...
September 2017: Science Advances
https://www.readbyqxmd.com/read/28924052/role-of-the-endothelial-caveolae-microdomain-in-shear-stress-mediated-coronary-vasorelaxation
#10
Tong Lu, Xiao-Li Wang, Qiang Chai, Xiaojing Sun, Gary C Sieck, Zvonimir S Katusic, Hon-Chi Lee
In this study, we determined the role of caveolae and the ionic mechanisms that mediate shear stress-mediated vasodilation (SSD). We found that both TRPV4 and SK channels are targeted to caveolae in freshly isolated bovine coronary endothelial cells (BCECs) and that TRPV4 and KCa2.3 (SK3) channels are co-immunoprecipitated by anti-caveolin-1 antibodies. Acute exposure of BCECs seeded in a capillary tube to 10 dynes/cm2 of SS resulted in activation of TRPV4 and SK currents. However, after incubation with HC067047 (TRPV4 inhibitor) SK currents could no longer be activated by SS, suggesting SK channel activation by SS was mediated through TRPV4...
September 18, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28923973/flow-induced-gelation-of-microfiber-suspensions
#11
Antonio Perazzo, Janine K Nunes, Stefano Guido, Howard A Stone
The flow behavior of fiber suspensions has been studied extensively, especially in the limit of dilute concentrations and rigid fibers; at the other extreme, however, where the suspensions are concentrated and the fibers are highly flexible, much less is understood about the flow properties. We use a microfluidic method to produce uniform concentrated suspensions of high aspect ratio, flexible microfibers, and we demonstrate the shear thickening and gelling behavior of such microfiber suspensions, which, to the best of our knowledge, has not been reported previously...
September 18, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28923473/virtual-surgery-for-patients-with-nasal-obstruction-use-of-computational-fluid-dynamics-mecomland-%C3%A2-digbody-%C3%A2-noseland-%C3%A2-to-document-objective-flow-parameters-and-optimise-surgical-results
#12
Manuel A Burgos, Maria Agustina Sevilla García, Enrique Sanmiguel Rojas, Carlos Del Pino, Carlos Fernández Velez, Francisco Piqueras, Francisco Esteban Ortega
INTRODUCTION: Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. We present a novel CFD software package to improve results following nasal surgery for obstruction. METHODS: A group of engineers in collaboration with otolaryngologists have developed a very intuitive CFD software package called MeComLand®, which uses the patient's cross-sectional (tomographic) images, thus showing in detail results originated by CFD such as airflow distributions, velocity profiles, pressure, or wall shear stress...
September 15, 2017: Acta Otorrinolaringológica Española
https://www.readbyqxmd.com/read/28920545/median-nerve-movement-in-the-carpal-tunnel-before-and-after-carpal-tunnel-release-using-transverse-ultrasound
#13
Mitsuhiko Nanno, Norie Kodera, Yuji Tomori, Yusuke Hagiwara, Shinro Takai
PURPOSE: We aimed to compare the movement of the median nerve within the carpal tunnel during wrist and finger motions between before and after carpal tunnel release (CTR) using transverse ultrasound in carpal tunnel syndrome (CTS) patients and to evaluate the biomechanical efficacy of CTR for CTS. METHODS: Twenty-four patients with CTS were examined by transverse ultrasound. The location of the median nerve within the carpal tunnel was examined quantitatively as a coordinate at varied wrist positions with finger extension and flexion, respectively, before and after CTR...
September 2017: Journal of Orthopaedic Surgery
https://www.readbyqxmd.com/read/28918876/evaluation-of-potential-substrates-for-restenosis-and-thrombosis-in-overlapped-versus-edge-to-edge-juxtaposed-bioabsorbable-scaffolds-insights-from-a-computed-fluid-dynamic-study
#14
Gianluca Rigatelli, Marco Zuin, Fabio Dell'Avvocata, Paolo Cardaioli, Dobrin Vassiliev, Miroslaw Ferenc, Nguyen Tuan Nghia, Thach Nguyen, Nicholas Foin
BACKGROUND/PURPOSE: Multiple BRSs and specifically the Absorb scaffold (BVS) (Abbott Vascular, Santa Clara, CA USA) have been often used to treat long diffuse coronary artery lesions. We evaluate by a computational fluid dynamic(CFD) study the impact on the intravascular fluid rheology on multiple bioabsorbable scaffolds (BRS) by standard overlapping versus edge-to-edge technique. METHODS/MATERIALS: We simulated the treatment of a real long significant coronary lesion (>70% luminal narrowing) involving the left anterior descending artery (LAD) treated with a standard or edge-to-edge technique, respectively...
August 17, 2017: Cardiovascular Revascularization Medicine: Including Molecular Interventions
https://www.readbyqxmd.com/read/28917988/a-comprehensive-screening-platform-for-aerosolizable-protein-formulations-for-intranasal-and-pulmonary-drug-delivery
#15
Martina Röhm, Stefan Carle, Frank Maigler, Johannes Flamm, Viktoria Kramer, Chrystelle Mavoungou, Otmar Schmid, Katharina Schindowski
Aerosolized administration of biopharmaceuticals to the airways is a promising route for nasal and pulmonary drug delivery, but - in contrast to small molecules - little is known about the effects of aerosolization on safety and efficacy of biopharmaceuticals. Proteins are sensitive against aerosolization-associated shear stress. Tailored formulations can shield proteins and enhance permeation, but formulation development requires extensive screening approaches. Thus, the aim of this study was to develop a cell-based in vitro technology platform that includes screening of protein quality after aerosolization and transepithelial permeation...
September 13, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28917684/role-of-low-endothelial-shear-stress-and-plaque-characteristics-in-the-prediction-of-nonculprit-major-adverse-cardiac-events-the-prospect-study
#16
Peter H Stone, Akiko Maehara, Ahmet Umit Coskun, Charles C Maynard, Marina Zaromitydou, Gerasimos Siasos, Ioannis Andreou, Dimitris Fotiadis, Kostas Stefanou, Michail Papafaklis, Lampros Michalis, Alexandra J Lansky, Gary S Mintz, Patrick W Serruys, Charles L Feldman, Gregg W Stone
OBJECTIVES: This study sought to determine whether low endothelial shear stress (ESS) adds independent prognostication for future major adverse cardiac events (MACE) in coronary lesions in patients with high-risk acute coronary syndrome (ACS) from the United States and Europe. BACKGROUND: Low ESS is a proinflammatory, proatherogenic stimulus associated with coronary plaque development, progression, and destabilization in human-like animal models and in humans. Previous natural history studies including baseline ESS characterization investigated low-risk patients...
September 9, 2017: JACC. Cardiovascular Imaging
https://www.readbyqxmd.com/read/28914752/ct-attenuation-of-pericoronary-adipose-tissue-in-normal-versus-atherosclerotic-coronary-segments-as-defined-by-intravascular-ultrasound
#17
Mohamed Marwan, Michaela Hell, Annika Schuhbäck, Sören Gauss, Daniel Bittner, Tobias Pflederer, Stephan Achenbach
BACKGROUND: The factors influencing genesis of atherosclerosis at specific regions within the coronary arterial system are currently uncertain. Local mechanical factors such as shear stress as well as metabolic factors, including inflammatory mediators released from epicardial fat, have been proposed. We analyzed computed tomographic (CT) attenuation of pericoronary adipose tissue in normal versus atherosclerotic coronary segments as defined by intravascular ultrasound (IVUS). PATIENTS AND METHODS: We evaluated the data sets of 29 patients who were referred for invasive coronary angiography and in whom IVUS of 1 coronary vessel was performed for clinical reasons...
September 2017: Journal of Computer Assisted Tomography
https://www.readbyqxmd.com/read/28914135/hemodynamic-and-anatomic-predictors-of-renovisceral-stent-graft-occlusion-following-chimney-endovascular-repair-of-juxtarenal-aortic-aneurysms
#18
Rosamaria Tricarico, Yong He, Liza Laquian, Salvatore T Scali, Roger Tran-Son-Tay, Adam W Beck, Scott A Berceli
PURPOSE: To identify anatomic and hemodynamic changes associated with impending visceral chimney stent-graft occlusion after endovascular aneurysm repair (EVAR) with the chimney technique (chEVAR). METHODS: A retrospective evaluation was performed of computed tomography scans from 41 patients who underwent juxtarenal chEVAR from 2008 to 2012 to identify stent-grafts demonstrating conformational changes following initial placement. Six subjects (mean age 74 years; 3 men) were selected for detailed reconstruction and computational hemodynamic analysis; 4 had at least 1 occluded chimney stent-graft...
September 1, 2017: Journal of Endovascular Therapy
https://www.readbyqxmd.com/read/28913763/a-patient-specific-three-dimensional-hemodynamic-model-of-the-circle-of-willis
#19
Hamed Rezaie, Ali Ashrafizadeh, Afsaneh Mojra
Circle of Willis (CoW) is one of the most important cerebral arteries in the human body and various attempts have been made to study the hemodynamic of blood flow in this vital part of the brain. In the present study, blood flow in a patient specific CoW is numerically modeled to predict disease-prone regions of the CoW. Medical images and computer aided design software are used to construct a realistic three-dimensional model of the CoW for this particular case. The arteries are considered as elastic conduits and the interactions between arterial walls and the blood flow are taken into account...
September 14, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28913434/self-determined-shapes-and-velocities-of-giant-near-zero-drag-gas-cavities
#20
Ivan U Vakarelski, Evert Klaseboer, Aditya Jetly, Mohammad M Mansoor, Andres A Aguirre-Pablo, Derek Y C Chan, Sigurdur T Thoroddsen
Minimizing the retarding force on a solid moving in liquid is the canonical problem in the quest for energy saving by friction and drag reduction. For an ideal object that cannot sustain any shear stress on its surface, theory predicts that drag force will fall to zero as its speed becomes large. However, experimental verification of this prediction has been challenging. We report the construction of a class of self-determined streamlined structures with this free-slip surface, made up of a teardrop-shaped giant gas cavity that completely encloses a metal sphere...
September 2017: Science Advances
keyword
keyword
25915
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"