Search results for "Viscosity."
showing 10 items of 537 documents
Bio-predictive tablet disintegration: Effect of water diffusivity, fluid flow, food composition and test conditions
2013
Abstract Food intake may delay tablet disintegration. Current in vitro methods have little predictive potential to account for such effects. The effect of a variety of factors on the disintegration of immediate release tablets in the gastrointestinal tract has been identified. They include viscosity of the media, precipitation of food constituents on the surface of the tablet and reduction of water diffusivity in the media as well as changes in the hydrodynamics in the surrounding media of the solid dosage form. In order to improve the predictability of food affecting the disintegration of a dosage form, tablet disintegration in various types of a liquefied meal has been studied under stati…
Scale-up and viscosity effects on gas–liquid mass transfer rates in unbaffled stirred tanks
2018
Abstract The interest in the process industry on unbaffled stirred tanks has greatly expanded in the last years because they may bring about significant advantages in a number of applications, including biochemical, food and pharmaceutical processes where the presence of baffles is undesirable for several reasons. Despite their application potential, unbaffled vessels still lack fundamental information, due to the fact that only recently their capabilities have started being dug out. The lack of information on scale up effects is possibly the main reason hindering practical applications. In this work the influence of vessel size and liquid viscosity on the mass transfer performance in unbaf…
Solution properties of polyelectrolytes. III. Effect of sodium polystyrene sulfonate concentration on viscometric and size exclusion chromatographic …
1988
The effect of sodium polystyrene sulfonate concentration on the shape of its molecules in aqueous solution at different NaNO3 ionic strengths has been analyzed by viscometry and size-exclusion chromatography (s.e.c). An equation has been developed which predicts the intrinsic viscosity, [η] p.cp.cs, at finite concentration of both polyion (cp) and electrolyte (cs). The experimental results obtained by both techniques can be accounted for in terms of the theory. Several factors involved in the elution mechanism have been considered and the variation of the slopes of s.e.c. calibration curves with cp and cs has been discussed in terms of polyion conformation changes.
Solution properties of polyelectrolytes. I. Exclusion chromatography of sodium polystyrene sulphonate in salt-free water as eluent
1987
The effect of concentration of sodium polystyrene sulphonate on the elution volume in exclusion chromatography has been investigated using salt-free water as eluent. A non-linear increase in the elution volume has been observed with increasing injected sample concentration. Concentration-dependent calibrations have been obtained which approach the universal calibration for uncharged polymers (dextrans) as polyelectrolyte concentration increases. The separation mechanisms are interpreted in terms of electrostatic and hydrodynamic interactions. A semi-empirical model is proposed to predict concentration effects of linear polyions in exclusion chromatography and good agreement has been found b…
Development of injectable and durable kefiran hydro-alcoholic gels.
2020
Injectable, in-situ forming kefiran gels have been developed for potential applications as implantable drug delivery devices or scaffolds for tissue regeneration. Concentrated solutions (4, 5 and 6%w) of kefiran, extracted from kefir grains, have been assessed in term of viscosity and injectability through G26 syringe needles, and for their ability to undergo gelation upon mixing with different alcohols. Propylene glycol (PG) has been selected as gelling agent because it ensures homogenous gelation in relatively short times (from few minutes up to 6 h). The investigation of the rheological behavior of kefiran/PG gels varying polymer concentration and temperature (25 degrees C and 37 degrees…
On the use of carrageenan matrices for the development of antiviral edible coatings of interest in berries
2019
Different film-forming dispersions (FFD) based on κ−, ι− and λ− carrageenans and green tea extract (GTE) have been developed as an innovative strategy to guarantee the food safety of blueberries and raspberries. First, the FFD were characterized (surface tension and viscosity) and the physicochemical properties (water vapour permeability-WVP-, water sorption, contact angle, mechanical properties) of the stand-alone films were evaluated. Then, the FFD were applied to refrigerated-stored raspberries and blueberries, and the antiviral activity against murine norovirus (MNV), a cultivable norovirus surrogate, and hepatitis A virus (HAV) of coated fruits was determined at refrigerated (10 °C) an…
Effect of pressure and temperature on viscosity of a borosilicate glass
2018
International audience; During industrial glass production processes, the actual distribution of stress components in the glass during scribing remains, to date, poorly quantified, and thus continues to be challenging to model numerically. In this work, we experimentally quantified the effect of pressure and temperature on the viscosity of SCHOTT N-BK7 glass, by performing in situ deformation experiments at temperatures between 550 and 595 °C and confining pressures between 100 MPa and 300 MPa. Experiments were performed at constant displacement rates to produce almost constant strain rates between 9.70 × 10 −6 s-1 and 4.98 × 10-5 s-1. The resulting net axial stresses range from 81 MPa to 8…
New biodegradable hydrogels based on an acryloylated polyaspartamide cross-linked by gamma irradiation
1999
Alpha, beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA), a synthetic biocompatible macromolecule, was functionalized with glycidyl methacrylate (GMA) in order to introduce in its side chains residues having double bonds and ester groups. The copolymer (PHG), obtained from PHEA and GMA, had a degree of derivatization of 29 mol%. PHG aqueous solutions are cross-linked by gamma radiation at 0 degrees C either in the presence or absence of N,N'-methylenebisacrylamide (BIS) giving rise to new hydrogel systems. In both cases gelation occurs at quite low doses (0.26 and 0.4 kGy, respectively). The obtained networks were characterized by FT-IR spectrophotometry which confirmed that the cross-linki…
Settling of dilute and semidilute fiber suspensions at finite Re
2007
The motion of tracer fibers settling in a suspension made optically transparent using an index-of refraction matching technique is studied as a function of concentration, aspect ratio, fluid viscosity, and fiber length distribution. At Re ∼ O (1), two different regimes of sedimentation are clearly identified. For small volume fractions we find that fibers settle with their long-axis preferentially in the horizontal state. With increasing volume fraction, fibers settle preferentially with their long-axis aligned in the direction of gravity. These findings are strikingly different than for those conducted with Re → 0 and qualitatively support the numerical simulations reported by Kuusela et a…
Über eine Nebenwirkung von Herzglykosiden auf die Viskosität des Blutes
1964
Die Strukturviskositat und Thixotropie von menschlichem Blut wird durch zugesetzte Herzglykoside (k-Strophanthin, Digitoxin) erniedrigt. Dieses Phanomen unterstutzt die Wirkung der Herzglykoside am Herzen.