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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
Maarten van de Meent
The linear in mass ratio correction to the periapsis advance of equatorial nearly circular orbits around a spinning black hole is calculated for the first time and to a very high precision, providing a key benchmark for different approaches modeling spinning binaries. The high precision of the calculation is leveraged to discriminate between two recent incompatible derivations of the 4 post-Newtonian equations of motion. Finally, the limit of the periapsis advance near the innermost stable orbit (ISCO) allows the determination of the ISCO shift, validating previous calculations using the first law of binary mechanics...
January 6, 2017: Physical Review Letters
D Cabaleiro, L Colla, S Barison, L Lugo, L Fedele, S Bobbo
This research aims at studying the stability and thermophysical properties of nanofluids designed as dispersions of sulfonic acid-functionalized graphene nanoplatelets in an (ethylene glycol + water) mixture at (10:90)% mass ratio. Nanofluid preparation conditions were defined through a stability analysis based on zeta potential and dynamic light scattering (DLS) measurements. Thermal conductivity, dynamic viscosity, and density were experimentally measured in the temperature range from 283.15 to 343.15 K and nanoparticle mass concentrations of up to 0...
December 2017: Nanoscale Research Letters
Amer Al-Shareef, P Neogi, Baojun Bai
Polymer flooding is an important process in enhanced oil recovery. The displacement front is unstable when low viscosity brine displaces the heavy crude oil in the reservoir. Water-soluble polymers are added to the brine to increase its viscosity which stabilizes the displacement process. To analyze the displacement process at the micro-level, we have investigated the dynamic contact angles in silicone oil-polymer (polyethylene oxide) solution and for the first time. The dynamic contact angle is the apparent contact angle at the three-phase contact line which governs the capillary pressure, and thus is important for the displacement process...
January 16, 2017: Physical Chemistry Chemical Physics: PCCP
Nimrod Moiseyev
Autoionization of molecular systems occurs in diatomic molecules and in small biochemical systems. Quantum chemistry packages enable calculation of complex potential energy surfaces (CPESs). The imaginary part of the CPES is associated with the autoionization decay rate, which is a function of the molecular structure. Molecular dynamics simulations, within the framework of the Born-Oppenheimer approximation, require the definition of a force field. The ability to calculate the forces on the nuclei in bio-systems when autoionization takes place seems to rely on an understanding of radiative damages in RNA and DNA arising from the release of slow moving electrons which have long de Broglie wavelengths...
January 14, 2017: Journal of Chemical Physics
Punit Kumar, Kashyap Kumar Dubey
The present study envisages the role of different carbon sources, nitrogen sources, metals, pH, inoculum volume and agitation rate in pellet formation of S. toxytricini at shake-flask level. It was found that galactose, ammonium sulphate, sodium nitrate, Cu(2+), Zn(2+), higher inoculum volume (5% v/v) and agitation rate at 300rpm caused significant reduction in pellet size (up to the range of 30μm-0.5mm) but biomass formations was also reduced subsequently. Interestingly diffused type of morphology was obtained in Fe(2+) supplemented medium with reduced biomass (1...
January 6, 2017: Bioresource Technology
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
Eiji Nakamachi, Tomohiro Noma, Kaito Nakahara, Yoshihiro Tomita, Yusuke Morita
The articular cartilage of a knee joint has a variety of functions including dispersing stress and absorbing shock in the tissue, and lubricating the surface region of cartilage. The metabolic activity of chondrocytes under the cyclic mechanical stimulations regenerates the morphology and function of tissues. Hence, the stress evaluation of the chondrocyte is vital subject to assess the regeneration cycle in the normal walking condition, and predict the injury occurrence in the accidents. Further, the threshold determination of stress for the chondrocytes activation is valuable for development of regenerative bio-reactor of articular cartilage...
January 5, 2017: International Journal for Numerical Methods in Biomedical Engineering
Yusei Kobayashi, Noriyoshi Arai
Janus nanoparticles (JNPs) have received considerable attention because of their characteristic physical properties that are due to more than two distinct chemical or physical surfaces. We investigated the rheological properties of a JNP solution in the nanotubes using a computer simulation. Prediction and control of the self-assembly of colloidal nanoparticles is of critical importance in materials chemistry and engineering. Herein, we show computer simulation evidence of a new type of velocity profile and a hallmark shear-thinning behavior by confining a JNP solution to a nanotube with hydrophobic and hydrophilic wall surfaces...
January 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Muhammad Asim Faridi, Harisha Ramachandraiah, Indradumna Banerjee, Sahar Ardabili, Sergey Zelenin, Aman Russom
BACKGROUND: Bloodstream infections (BSI) remain a major challenge with high mortality rate, with an incidence that is increasing worldwide. Early treatment with appropriate therapy can reduce BSI-related morbidity and mortality. However, despite recent progress in molecular based assays, complex sample preparation steps have become critical roadblock for a greater expansion of molecular assays. Here, we report a size based, label-free, bacteria separation from whole blood using elasto-inertial microfluidics...
January 4, 2017: Journal of Nanobiotechnology
M M Rashidi, Z Yang, Muhammad Awais, Maria Nawaz, Tasawar Hayat
Analysis has been conducted to present the generalized magnetic field effects on the flow of a Burgers' nanofluid over an inclined wall. Mathematical modelling for hydro-magnetics reveals that the term "[Formula: see text]" is for the Newtonian model whereas the generalized magnetic field term (as mentioned in Eq 4) is for the Burgers' model which is incorporated in the current analysis to get the real insight of the problem for hydro-magnetics. Brownian motion and thermophoresis phenomenon are presented to analyze the nanofluidics for the non-Newtonian fluid...
2017: PloS One
Sasan Delfan-Hosseini, Kooshan Nayebzadeh, Leila Mirmoghtadaie, Maryam Kavosi, Seyede Marzieh Hosseini
Purslane seed oil could be considered as potential nutritious oil due to its desirable fatty acid composition and other biological active compounds. In this study the effect of three extraction procedure including solvent extraction, cold pressing and microwave pretreatment (MW) followed by cold pressing on oil yield, physicochemical properties, oxidative stability and rheological behaviors of oil was investigated. Solvent extracted oil had the highest extraction yield (72.31%). Pretreatment by microwave before cold press extraction resulted in an increase in extraction yield, total phenolic compound (TPC) and antioxidant activity...
May 1, 2017: Food Chemistry
Vikash Pandey, Sverre Holm
The characteristic time-dependent viscosity of the intergranular pore-fluid in Buckingham's grain-shearing (GS) model [Buckingham, J. Acoust. Soc. Am. 108, 2796-2815 (2000)] is identified as the property of rheopecty. The property corresponds to a rare type of a non-Newtonian fluid in rheology which has largely remained unexplored. The material impulse response function from the GS model is found to be similar to the power-law memory kernel which is inherent in the framework of fractional calculus. The compressional wave equation and the shear wave equation derived from the GS model are shown to take the form of the Kelvin-Voigt fractional-derivative wave equation and the fractional diffusion-wave equation, respectively...
December 2016: Journal of the Acoustical Society of America
J Shanthilal, Suvendu Bhattacharya
Flowable food materials express complex flow behaviour and are conventionally subjected to individual time-independent and time-dependent experiments. The present study proposes a single experiment to determine both these characteristics simultaneously in addition to determining the 'isoviscosity' to quantify and compare these properties by using a model food system like chickpea flour dispersion. The method employed here consists of the generation of five loops having increasing and decreasing shear-rates along with yield stress measurement in between them...
November 2016: Journal of Food Science and Technology
Thawatchai Phaechamud, Orn Setthajindalert
Cholesterol has been widely used in drug delivery systems including implant. Doxycycline hyclate (DH)-loaded cholesterol in situ forming gels using N-methyl pyrrolidone as a solvent were prepared and investigated for their properties including viscosity, rheology, syringeability, gel formation, drug release, degradation and antimicrobial activities. The burst drug release of a DH-loaded in situ forming gel using cholesterol as the gelling agent was minimized when the amount of benzyl benzoate was increased...
December 24, 2016: European Journal of Pharmaceutical Sciences
Malika Talantikite, Kahina Aoudia, Lazhar Benyahia, Lila Chaal, Christophe Chassenieux, Claude Deslouis, Cédric Gaillard, Boualem Saidani
Self-assembly in aqueous solutions of an amphiphilic comblike polyelectrolyte (80C12) that consists of a polystyrene (PS) backbone onto which quaternary ammonium pendant moieties have been grafted has been investigated by light scattering and cryo-transmission electron microscopy measurements in the presence of KCl and methylviologen dication (MV(2+)) under conditions mimicking those for electrochemical measurements. Polymer chains self-assemble within branched cylindrical micelles that display viscoelastic properties, characterized by a relaxation time of 4 s...
January 19, 2017: Journal of Physical Chemistry. B
Kenny Wei Quan Low, Raoul van Loon, Sam Rolland, Johann Sienz
This paper numerically investigates non-Newtonian blood flow with oxygen and carbon dioxide transport across and along an array of uniformly square and staggered arranged fibres at various porosity (e) levels, focussing on a low Reynolds number regime (Re < 10). The objective is to establish suitable mass transfer correlations, expressed in the form of Sherwood number (Sh = f (e,Re,Sc)), that identifies the link from local mass transfer investigations to full-device analyses. The development of a concentration field is initially investigated and expressions are established covering the range from a typical deoxygenated condition up to a full oxygenated condition...
December 22, 2016: Journal of Biomechanical Engineering
Jelena Dinic, Leidy Nallely Jimenez, Vivek Sharma
Liquid transfer and drop formation/deposition processes involve complex free-surface flows including the formation of columnar necks that undergo spontaneous capillary-driven instability, thinning and pinch-off. For simple (Newtonian and inelastic) fluids, a complex interplay of capillary, inertial and viscous stresses determines the nonlinear dynamics underlying finite-time singularity as well as self-similar capillary thinning and pinch-off dynamics. In rheologically complex fluids, extra elastic stresses as well as non-Newtonian shear and extensional viscosities dramatically alter the nonlinear dynamics...
December 21, 2016: Lab on a Chip
Chia-Wei Chang, Ying-Chih Liao
In this work, the long-term stability of titanium oxide nanowire suspensions was accessed by an accelerated sedimentation with centrifugal forces. Titanium oxide (TiO2) nanoparticle (NP) and nanowire (NW) dispersions were prepared, and their sizes were carefully characterized. To replace the time-consuming visual observation, sedimentation velocities of the TiO2 NP and NW suspensions were measured using an analytical centrifuge. For an aqueous TiO2 NP suspension, the measured sedimentation velocities were linearly dependent on the relative centrifugal forces (RCF), as predicted by the classical Stokes law...
December 27, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Ivan C Christov, P M Jordan
We point out, and show the implications of resolving, an apparent conceptual difficulty in a recent article by De Corato et al. [Phys. Rev. E 92, 053008 (2015)PLEEE81539-375510.1103/PhysRevE.92.053008] on the locomotion of certain microorganisms in a second-grade fluid. The difficulty arises due to the assumption that α_{1}<0, where α_{1} is the first normal stress modulus of the (non-Newtonian) liquid, was chosen for this study. In particular, this choice of sign for α_{1} is inconsistent with thermodynamics, and as such casts considerable doubt on De Corato et al...
November 2016: Physical Review. E
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