Search results for "VISCOSITY"
showing 10 items of 542 documents
Objective function design for robust optimality of linear control under state-constraints and uncertainty
2009
We consider a model for the control of a linear network flow system with unknown but bounded demand and polytopic bounds on controlled flows. We are interested in the problem of finding a suitable objective function that makes robust optimal the policy represented by the so-called linear saturated feedback control. We regard the problem as a suitable differential game with switching cost and study it in the framework of the viscosity solutions theory for Bellman and Isaacs equations. © 2009 EDP Sciences, SMAI.
Vascular atherosclerotic disease: evaluation of the whole-blood filterability and red cell membrane microrheological pattern after intravenous admini…
1990
SummaryA study was carried out in 10 patients with vascular atherosclerotic disease to investigate the effects of a single dose of 300 mg pentoxifylline, given by intravenous infusion over 30 minutes, on various macrorheological and nzicrorheological parameters. Measurements were made at baseline, at the end of the intravenous infusion and again 30 minutes later of whole-blood filterability, erythrocyte membrane fluidity (using pyrene as probe) and transverse fluidity gradient (using fluorescent fatty acids as probes). The results showed that there was a significant variation in whole-blood filterability and the red cell membrane fluidity gradient after pentoxifylline. No difference, howeve…
Green composites of organic materials and recycled post-consumer polyethylene
2004
International audience; Addition of organic fillers to post‐consumer recycled plastics can give rise to several advantages. First of all, the cost of these fillers is usually very low, the organic fillers are biodegradable contributing to an improved environmental impact and, last but not least, some mechanical and thermomechanical properties can be enhanced. Organic fillers are not widely used in the plastic industry although their use is increasing. Bad dispersion into the polymer matrix at high‐level content and poor adhesion with the matrix are the more important obstacles to this approach. In this work various organic fillers have been used with a post‐consumer plastic material origina…
A novel and simple method for the purification of extracellular levansucrase from Zymomonas mobilis.
2003
A new and simple method for the purification of extracellular levansucrase from Zymomonas mobilis from highly viscous fermentation broth was developed. After incubation of the fermentation broth with a fructose-polymer cleaving enzyme preparation (Fructozyme, Novozymes, DK) for 48 h, levansucrase precipitated as aggregates and was redissolved in a 3 M urea solution. By ongoing size-exclusion chromatography on Sephacryl S-300 the final levansucrase preparation was purified 100-fold and exhibited a specific activity of 25-35 U/mg(protein). The levansucrase was stable in 3 M urea solution for at least four months without inactivation. To maximize the enzyme yield the dynamic changes of extrace…
Gelchromatographie mit zwei Detektoren. Ein verfahren zur Korrektur von Gelchromatogrammen
1978
The relationship between the experimental function E(v) for the viscosity and the chromatogram after correction of instrumental spreading, w(v0) can be expressed by the integral equation where v0 is the elution volume under the integral sign and D(v, v0) is a function that describes the shape of the band spreading curve of a monodisperse sample. The relationship between the experimental chromatogram e(v) is given by the Tung equation. If the function D(v, v0) is independent of the molecular weight, then it is possible to solve these equations simultaneously and to calculate the functions w(v0) and D(v, v0). A mathematical method is given.
Healon®5: A New Viscoadaptive Formulation
2000
To relate the practical relevance of our study results, specific requirement profiles for individual procedures have been correlated to the desired physicochemical characteristics. Healon®5 demonstrated the statistically significant highest zero shear viscosity of all OVD and a long relaxation time (Dick et al., 2000). It therefore most effectively creates and maintains a deep anterior chamber in order to facilitate safe surgical maneuvers (e.g., in case of vitreous pressure). Additionally, the high viscosity of Healon®5 exhibits a dynamic frequency dependence, which has not been observed in any pure hyaluronic acid formulation before. Healon®5’s properties change in response to surgical ma…
Thermodynamic formalism for transport coefficients with an application to the shear modulus and shear viscosity.
2016
We discuss Onsager's thermodynamic formalism for transport coefficients and apply it to the calculation of the shear modulus and shear viscosity of a monodisperse system of repulsive particles. We focus on the concept of extensive "distance" and intensive "field" conjugated via a Fenchel-Legendre transform involving a thermodynamic(-like) potential, which allows to switch ensembles. Employing Brownian dynamics, we calculate both the shear modulus and the shear viscosity from strain fluctuations and show that they agree with direct calculations from strained and non-equilibrium simulations, respectively. We find a dependence of the fluctuations on the coupling strength to the strain reservoi…
Continuous fractionation of poly[(dimethylimino)decamethylene bromide] and molecular weight dependence of the glass transition
1995
30 g of the ionene poly[(dimethylimino)decamethylene bromide] were fractionated by a continuous counter-current extraction method (CPF) using ethylene glycol monoethyl ether as the solvent and diisopropyl ether as the non-solvent component. The efficiency of the separation was checked by viscometry and gel-permeation chromatography (GPC) measurements. Eight fractions of different molar mass were prepared for differential scanning calorimetry (DSC) experiments. With bromide as counter-ion, the glass transition temperature of the ionene increases from ca. 60 to 85°C as the intrinsic viscosity of this material (in 0,4 M aqueous solutions of KBr at 25°C) rises from ca. 14 to 22 mL/g. When bromi…
Evaluation of the Haemorheological Determinants in Coronary Heart Disease
1984
Increased blood viscosity has been described in patients with coronary artery disease (1, 2, 3, 4, 5, 6, 7, 8).
Viscosity of the elbow flexor muscles during maximal eccentric and concentric actions.
1996
The aim of the present study was to estimate the damping coefficient (B factor) of the elbow flexor muscles during both eccentric and concentric muscle actions. We used a muscle model consisting of a viscous damper associated in parallel with a contractile component, both in series with an elastic component. The viscous damper allowed the concentric loss and the eccentric gain of force to be modelled. Eight volunteer subjects performed maximal eccentric and concentric elbow movements on an isokinetic dynamometer at angular velocities of 0.52, 1.04 and 2.09 rad*s(-1). Torques at an elbow joint angle of 90 degrees were recorded. Electromyogram (EMG) signals from the belly of the right elbow f…