Search results for "viscosity"
showing 10 items of 542 documents
Haemorheological components in the pre-geriatric and geriatric age range in a randomly selected Western Sicily population sample (Casteldaccia study)
1993
{Received 24.8.1992; accepted 7.12.1992} On a randomly selected western Sicily population sample (Casteldac cia Study: 600 subjects; 300 males and 300 females) of an age range from 40 to 79 years, were determined: Haematocrit (Htc) , blood vi scosity, plasma viscosity, filterability of whole blood and fibrinogen. Par ticipation was 97%, being 582 subjects (M = 287, F = 295). All the parameters measured showed a progressive increase with age and si gnificant differences were found between male and female subjects: Htc and blood viscosity were higher in male subjects (p < 0.01), while plasma viscosity, whole blood filterability and fibrinogen were higher in female subjects (p < 0.05). In …
Clinical conditions responsible for hyperviscosity and skin ulcers complications
2017
In this brief review, we have examined some clinical conditions that result to be associated to an altered hemorheological profile and at times accompanied by skin ulcers. This skin condition may be observed in patients with the following condtions, such as primary polycythemic hyperviscosity (polycythemia, thrombocytemia) treated with hydroxyurea, primary plasma hyperviscosity (multiple myeloma, cryoglobulinemia, cryofibrinogenemia, dysfibrinogenemia, and connective tissue diseases), primary sclerocythemic hyperviscosity (hereditary spherocytosis, thalassemia, and sickle cell disease). In addition, it may be present in patients with secondary hyperviscosity conditions such as diabetes mell…
Communication versus waterproofing: the physics of insect cuticular hydrocarbons
2019
Understanding the evolution of complex traits is among the major challenges in biology. One such trait is the cuticular hydrocarbon (CHC) layer in insects. It protects against desiccation and provides communication signals, especially in social insects. CHC composition is highly diverse within and across species. To understand the adaptive value of this chemical diversity, we must understand how it affects biological functionality. So far, CHCs received ample research attention, but their physical properties were little studied. We argue that these properties determine their biological functionality, and are vital to understand how CHC composition affects their adaptive value. We investigat…
Using cross-modal interactions to counterbalance salt reduction in solid foods
2011
International audience; We investigated odour-induced saltiness enhancement (OISE) in a solid model cheese with the aim of evaluating the influence of cross-modal interactions (odour-texture-taste) on saltiness perception and assessing the efficacy of using OISE to counterbalance salt reduction. Four model cheeses, varying in texture, were flavoured with three commercial tasteless aromas (comte cheese, sardine and carrot) differently associated with salty and cheesy food products. Twenty-seven consumers evaluated taste intensity, aroma intensity and its congruence with the product flavour, and the overall pleasantness of 12 flavoured and four unflavoured samples. The comparison of the perce…
Polymer-polymer interaction, in the presence of a solvent as measured by viscometry
2001
Dilute solution viscometry experiments have been carried out in five ternary polymer systems solvent(1)/polymer(2)/polymer(3). Values of the specific viscosity of polymer (3) in a ‘binary solvent’ formed by polymer(2) + solvent(1) have been used to determine the compatibility of the polymer blends. Krigbaum and Wall formalism has been used to predict compatibility which relies on an interaction parameter that depends on the concentration, weight fraction and molar mass of each polymer. To reduce the dependences and to clarify the criterion of compatibility, a parameter independent of polymer (3) composition and molar mass has been deduced. This parameter shows the same behaviour with polyme…
Pressure influences on the viscosity of polymer solutions
1982
Of all physico-chemical quantities characterizing the behavior of liquids, the viscosity coefficient η is normally most sensitive to pressure. Early measurements of η(p) date back almost 100 years [1] but they were carried out with very different objectives [2]. Currently, one is particularly interested in polymer solutions, for instance because of the additives to motor oils and of oil recovery. The present paper reports on measurements with polystyrenes of high molecular uniformity in eight different solvents. It confines itself to zero-shear viscosities and discusses the possibilities of discovering the influence of pressure via the molecular structure of the solvent and via its thermody…
Micromechanics of “raspberry” morphology in PPE/SAN polymer blends compatibilized with linear ABC triblock terpolymers
2015
Abstract The effect of compatibilization with a symmetrical polystyrene- block -polybutadiene- block -poly(methyl methacrylate) (SBM) triblock terpolymer on the morphological and mechanical properties (specifically toughness) of immiscible poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene- co -acrylonitrile) (PPE/SAN) blends with different blend (w/w) ratios is investigated. We study the effect of blend viscosity on the localization of the compatibilizer at the blend interface, influencing the mechanical properties of the macroscopic material. The impact of the specific morphology of the blends, known as “raspberry morphology”, on the final material will be explained using thermomechanica…
Temperature dependence of η/s of strongly interacting matter: Effects of the equation of state and the parametric form of (η/s)(T)
2020
We investigate the temperature dependence of the shear viscosity to entropy density ratio $\ensuremath{\eta}/s$ using a piecewise linear parametrization. To determine the optimal values of the parameters and the associated uncertainties, we perform a global Bayesian model-to-data comparison on $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{\mathrm{NN}}}=200$ GeV and $\mathrm{Pb}+\mathrm{Pb}$ collisions at 2.76 TeV and 5.02 TeV, using a $2+1\mathrm{D}$ hydrodynamical model with the Eskola-Kajantie-Ruuskanen-Tuominen (EKRT) initial state. We provide three new parametrizations of the equation of state (EoS) based on contemporary lattice results and hadron resonance gas, and use them and t…
Zero viscosity limit of the Oseen equations in a channel
2001
Oseen equations in the channel are considered. We give an explicit solution formula in terms of the inverse heat operators and of projection operators. This solution formula is used for the analysis of the behavior of the Oseen equations in the zero viscosity limit. We prove that the solution of Oseen equations converges in W1,2 to the solution of the linearized Euler equations outside the boundary layer and to the solution of the linearized Prandtl equations inside the boundary layer. © 2001 Society for Industrial and Applied Mathematics.
Fibre break processes in unidirectional composites
2014
International audience; A model to predict the effects of the accumulation of fibre breakages in unidirectional carbon fibre composites has been developed that takes into account several physical phenomena controlling fibre failure, including the stochastic nature of fibre strength, stress transfer between fibres due to the shear of the matrix, interfacial debonding and viscosity of the matrix. The damage processes leading up to failure are discussed and quantified, first in terms of fibre breaks for the case of monotonically increasing tensile loading, then for sustained loading and finally the implications for more complex loads and structures are discussed. It is clearly shown that the f…