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Shear force

Guy Nir, Einat Chetrit, Anat Vivante, Yuval Garini, Ronen Berkovich
We utilized single-molecule tethered particle motion (TPM) tracking, optimized for studying the behavior of short (0.922 μm) dsDNA molecules under shear flow conditions, in the proximity of a wall (surface). These experiments track the individual trajectories through a gold nanobead (40 nm in radius), attached to the loose end of the DNA molecules. Under such circumstances, local interactions with the wall become more pronounced, manifested through hydrodynamic interactions. To elucidate the mechanical mechanism that affects the statistics of the molecular trajectories of the tethered molecules, we estimate the resting diffusion coefficient of our system...
February 16, 2018: Soft Matter
Heidy Cruz, Younggon Son
Since the discovery of carbon nanotubes (CNT), significant research works have focused on the application of CNT as conductive filler to polymer nanocomposites which can be used in several fields such as electrostatic dissipation (ESD), electrostatic painting and electromagnetic interference shielding (EMI-shielding). However, the main challenge in the large-scale manufacturing of this technology is the poor electrical conductivity of polymer nanocomposites produced by injection molding process. This study aims to investigate the effect of CNT aspect ratio in improving the electrical conductivity of injection molded nanocomposites...
February 1, 2018: Journal of Nanoscience and Nanotechnology
Zi-Kun He, Jing-An Li, Xiao Luo, Dan Zou, Ping Yang, An-Sha Zhao, Nan Huang
The TiO2 nanotube has been anticipated for potential application for cardiovascular implanted devices for its excellent drug loading/release function and biocompatibility. However, its mechanical behavior has rarely been studied as the cardiovascular devices. The tube length is a crucial factor which not only decides the drug loading ability but also influences the devices' mechanical behavior. Therefore, in this work, the TiO2 nanotubes with different tube length (NT2, NT4 and NT6) were fabricated, and their surface energy, residual stress, tensile tolerability and blood flow shear stress tolerability were determined, respectively...
February 1, 2018: Journal of Nanoscience and Nanotechnology
G A Basheed, Komal Jain, Saurabh Pathak, R P Pant
We investigate the effect of dilution on dipolar interaction with linear and non-linear rheological properties of kerosene based magnetic fluid. The steady-state behavior demonstrate a shear thinning behavior and corroborated with a power law, (η = c <mml:math display="block"> <mml:mover accent="true"> <mml:mi>γ</mml:mi> <mml:mo>˙</mml:mo> </mml:mover></mml:math>n + η∞) exponent, n ≤ 1. The shear-induced-breakup (separation) of nanoparticles and the yielding behavior has been explained by Bingham model...
April 1, 2018: Journal of Nanoscience and Nanotechnology
Jordan Bade-Boon, Joseph K Mathew, Mark C Fitzgerald, Biswadev Mitra
BACKGROUND: Blunt thoracic aortic injury (BTAI) is an uncommon diagnosis, usually developing as a consequence of high-impact acceleration-deceleration mechanisms. Timely diagnosis may enable early resuscitation and reduction of shear forces, essential to prevent worsening of the injury prior to definitive management. Death is commonly due to haemorrhagic shock, but clinical features may be absent until sudden and massive haemorrhage. OBJECTIVES: The aim of this systematic review was to determine the proportion of patients with BTAI who present with unstable vital signs...
February 9, 2018: Emergency Medicine Journal: EMJ
Karsten Zecher, Vishwa Prasad Aitha, Kirsten Heuer, Herbert Ahlers, Katrin Roland, Michael Fiedel, Bodo Philipp
Marine biofouling on artificial surfaces such as ship hulls or fish farming nets causes enormous economic damage. The time for the developmental process of antifouling coatings can be shortened by reliable laboratory assays. For designing such test systems, it is important that toxic effects can be excluded, that multiple parameters can be addressed simultaneously and that mechanistic aspects can be included. In this study, a multi-step approach for testing antifouling coatings was established employing photoautotrophic biofilm formation of marine microorganisms in micro- and mesoscoms...
February 10, 2018: Journal of Microbiological Methods
Wade W Sugden, Arndt F Siekmann
PURPOSE OF REVIEW: Mutations in the Endoglin (Eng) gene, an auxiliary receptor in the transforming growth factor beta (TGFβ)-superfamily signaling pathway, are responsible for the human vascular disorder hereditary hemorrhagic telangiectasia (HHT) type 1, characterized in part by blood vessel enlargement. A growing body of work has uncovered an autonomous role for Eng in endothelial cells. We will highlight the influence of Eng on distinct cellular behaviors, such as migration and shape control, which are ultimately important for the assignment of proper blood vessel diameters...
February 12, 2018: Current Opinion in Hematology
X Zhang, O Fadoul, E Lorenceau, P Coussot
So far, yielding and flow properties of soft-jammed systems have only been studied from simple shear and then extrapolated to other flow situations. In particular, simple flows such as elongations have barely been investigated experimentally or only in a nonconstant, partial volume of material. We show that using smooth tool surfaces makes it possible to obtain a prolonged elongational flow over a large range of aspect ratios in the whole volume of material. The normal force measured for various soft-jammed systems with different microstructures shows that the ratio of the elongation yield stress to the shear yield stress is larger (by a factor of around 1...
January 26, 2018: Physical Review Letters
T Kobayashi, M Sasaki, T Ido, K Kamiya, Y Miura, Y Nagashima, K Ida, S Inagaki, A Fujisawa, S-I Itoh, K Itoh
We investigate spatial structures of turbulence and turbulent transport modulated by the geodesic acoustic mode (GAM), from which the excitation mechanism of the GAM is discussed. The GAM is found to be predominantly excited through a localized Reynolds stress force, rather than the dynamic shearing force. The evaluated growth rate is larger than the linear damping coefficients and is on the same order of magnitude as the effective growth rate evaluated from time evolution in the GAM kinetic energy.
January 26, 2018: Physical Review Letters
Yuqi Guo, Fang Wei, Juan Wang, Yingxin Zhao, Shangwen Sun, Hua Zhang, Zhendong Liu
Hemodynamic has increasingly been regarded as an important factor of renal function. However, the relationship between carotid artery wall shear stress (WSS) and renal function is not clarified. To investigate the relationship between carotid WSS and renal function, we recruited 761 older subjects aged 60 years and over from community-dwelling in the Shandong area, China. Carotid WSS, endothelial function, and estimated glomerular filtration rate (eGFR) were assessed in all subjects. Subjects were grouped by the interquartile of the carotid artery mean WSS...
January 12, 2018: Oncotarget
Babatunde Agbeniga, Edward C Webb
The effects of beef carcass weight on muscle pH/temperature profile and selected meat quality attributes were evaluated. Twenty-six carcasses from light (≤260kg, n=15) and heavy (≥290kg, n=11) feedlot steers were randomly allocated and stimulated with low voltage electrical stimulation (LVES) for 30s at 7min post-mortem (pm). Quality evaluations were carried out on samples from the Longissimus et lumborum (LL) muscle from the left side of each carcass. Heavier carcasses showed faster pH decline and slower (P<0...
March 2018: Food Research International
Sudip Das, Rochish M Thaokar
The axisymmetric electrohydrodynamic deformation of an elastic capsule with a capacitive membrane obeying the Skalak law under a uniform AC electric field is investigated using analytical and boundary integral theory. The low capillary number (the ratio of destabilizing shear or electric force to the stabilizing elastic force) regime shows that time-averaged prolate and oblate spheroid deformations, and the time-periodic prolate-sphere, oblate-sphere breathing modes are commensurate with the time averaged-deformation...
February 12, 2018: Soft Matter
Yingqun Nian, Paul Allen, Sabine M Harrison, Joseph P Kerry
BACKGROUND: The use of bulls rather than steers for beef production offers some considerable advantages, however, the eating quality of bull beef is an issue of marketing concern. This study assessed the physico-chemical characteristics of young Holstein-Friesian (HF) bull and steer beef. Steer carcasses were suspended by the Achilles tendon (AS) and by Pelvic suspension (PS). RESULTS: HF Steer beef had higher redness, yellowness, and chroma values, while bulls had higher ultimate pH and darker muscle...
February 12, 2018: Journal of the Science of Food and Agriculture
B Khadhraoui, M Turk, A S Fabiano-Tixier, E Petitcolas, P Robinet, R Imbert, M El Maâtaoui, F Chemat
There are more than 1300 articles in scientific literature dealing with positive impacts of Ultrasound-Assisted Extraction (UAE) such as reduction of extraction time, diminution of solvent and energy used, enhancement in yield and even selectivity, intensification of diffusion, and eliminating wastes. This present study aims to understand what are the mechanism(s) behind these positive impacts which will help to design a decision tool for UAE of natural products. Different microscopic observations (Scanning Electron Microscopy (SEM), Environmental Scanning Electron Microscopy (e-SEM), Cyto-histochemistry) have been used for spacial and temporal localization of metabolites in rosemary leaves, which is one of the most studied and most important plant for its antioxidant metabolites used in food industry, during conventional and ultrasound extraction...
April 2018: Ultrasonics Sonochemistry
Hyun-Wook Kim, Ji-Han Kim, Jin-Kyu Seo, Derico Setyabrata, Yuan H Brad Kim
The aim of this study was to evaluate the effect of aging/freezing sequence and freezing rate on quality attributes and oxidative stability of frozen/thawed pork loins (M. longissimus lumborum, n = 6). Six treatments were prepared by combining 3 aging/freezing sequences (FT, freezing/thawing only; AFT, aging prior to freezing/thawing; and FTA, freezing/thawing and aging) with 2 freezing rates (slow- and fast-freezing). The lowest purge/thaw loss and drip loss were found for AFT, in which fast-freezing reduced total exudate loss (P < 0...
January 31, 2018: Meat Science
Stephen W Linderman, Mikhail Golman, Thomas R Gardner, Victor Birman, William N Levine, Guy M Genin, Stavros Thomopoulos
Tendon-to-bone surgical repairs have unacceptably high failure rates, possibly due to their inability to recreate the load transfer mechanisms of the native enthesis. Instead of distributing load across a wide attachment footprint area, surgical repairs concentrate shear stress on a small number of suture anchor points. This motivates development of technologies that distribute shear stresses away from suture anchors and across the enthesis footprint. Here, we present predictions and proof-of-concept experiments showing that mechanically-optimized adhesive films can mimic the natural load transfer mechanisms of the healthy attachment and increase the load tolerance of a repair...
February 7, 2018: Acta Biomaterialia
James T Waters, Ya Liu, Like Li, Anna C Balazs
Using computational modeling, we show that the dynamic interplay between a flowing fluid and the appropriately designed surface relief pattern can inhibit the fouling of the substrate. We specifically focus on surfaces that are decorated with three-dimensional chevron or sawtooth "micromixer" patterns and model the fouling agents (e.g., cells) as spherical microcapsules. The interaction between the imposed shear flow and the chevrons on the surface generates 3D vortices in the system. We pinpoint a range of shear rates where the forces from these vortices can rupture the bonds between two mobile microcapsules near the surface...
February 9, 2018: ACS Applied Materials & Interfaces
Hasan Skienhe, Roland Habchi, Hani F Ounsi, Marco Ferrari, Ziad Salameh
AIM: The aim of this study was to evaluate the effect of different surface treatments on roughness, grain size, and phase transformation of presintered zirconia. MATERIALS AND METHODS: Surface treatments included airborne particle abrasion (APA) before and after sintering with different particles shape, size, and pressure (50 μm Al2O3, 50 μm glass beads, and ceramic powder). Thirty-five square-shaped presin-tered yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic slabs (Zenostar ZR bridge, Wieland) were prepared (4 mm height × 10 mm width × 10 mm length) and polished with silicon carbide grit papers #800, 1000, 1200, 1500, and 2000 to ensure identical initial roughness...
February 1, 2018: Journal of Contemporary Dental Practice
Samantha L Lipman, Ned C Rouze, Mark L Palmeri, Kathryn R Nightingale
Shear wave elasticity imaging (SWEI) characterizes the mechanical properties of human tissues to differentiate healthy from diseased tissue. Commercial scanners tend to reconstruct shear wave speeds for a region of interest using time-of-flight methods reporting a single shear wave speed (or elastic modulus) to the end user under the assumptions that tissue is elastic and shear wave speeds are not dependent on the frequency content of the shear waves. Human tissues, however, are known to be viscoelastic, resulting in dispersion and attenuation...
February 5, 2018: Ultrasound in Medicine & Biology
Edgar G Blanco-Díaz, Erik A Vázquez-Montelongo, G Andrés Cisneros, Edgar Omar Castrejón-González
Non-covalent interactions (NCIs) play a crucial role in the behavior and properties of ionic liquids (ILs). These interactions are particularly important for non-equilibrium properties such as the change in viscosity due to shearing forces (shear viscosity). Therefore, a detailed understanding of these interactions can improve our understanding of these important classes of liquids. Here, we have employed quantum mechanical energy decomposition analysis (EDA) and NCI analysis to investigate a series of representative 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]) ion pairs extracted from classical equilibrium and non-equilibrium molecular dynamics simulations...
February 7, 2018: Journal of Chemical Physics
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