Chromogenesis in Staphylococcus aureus has received considerable attention, although today it is generally accepted that pigmentation in this organism is of little taxonomic value. Numerous carotenoid pigments from this organism have been characterized (B. Sobin and G. L. Stahly, J. Bacteriol. 44:265, 1942). The purpose of this investigation was to determine whether the variations in pigmentati...

The penetration ability of boar (Sus scrofa domestica) spermatozoa exposed to viscous preparations under in vivo and in vitro fertilization conditions has been examined. Experiments involving induced ovulation in prepubertal animals and surgical insemination directly into the oviduct isthmus revealed an advantage of colloidal preparations. Based on within-animal comparisons, the incidence of pe...

Turbulence is ubiquitous, from oceanic currents to small-scale biological and quantum systems. Self-sustained turbulent motion in microbial suspensions presents an intriguing example of collective dynamical behavior among the simplest forms of life and is important for fluid mixing and molecular transport on the microscale. The mathematical characterization of turbulence phenomena in active non...

Guar gum can be used to effectively improve stability and mobility of microscale zerovalent iron particles (MZVI) used in groundwater remediation. Guar gum is a food-grade, environment friendly natural polysaccharide, which is often used as thickening agent in a broad range of food, pharmaceutical and industrial applications. Guar gum solutions are non-Newtonian, shear thinning fluids, characte...

We used video microscopy and particle tracking to study the dynamics of confined hard-sphere suspensions. Our fluids consisted of 1.1-microm-diameter silica spheres suspended at volume fractions of 0.33-0.42 in water-dimethyl sulfoxide. Suspensions were confined in a quasiparallel geometry between two glass surfaces: a millimeter-sized rough sphere and a smooth flat wall. First, as the separati...

A revision of the popular equation Richardson and Zaki (1954a, Transactions Institute Chemical Engineering, 32, 35–53) for hindered settling suspensions non-cohesive particles in fluids is proposed, based on 548 data sets from a broad range scientific disciplines. The new enables predictions velocity wide particle sizes densities, liquid densities viscosities, but with focus sediment water. ana...

Stability of coarse particles against gravity is an important issue in dense suspensions (fresh concrete, foodstuff, etc.). On the one hand, it is known that they are stable at rest when the interstitial paste has a high enough yield stress; on the other hand, it is not yet possible to predict if a given material will remain homogeneous during a flow. Using MRI techniques, we study the time evo...

In this work, a modified rheometer has been used to gain information on the "start-up" of the shear flow of an electrorheological (ER) fluid consisting of hematite particles dispersed in silicone oil. The results show that unelectrified suspensions behave essentially as fluids, continuously deforming upon application of shear. However, this behavior changes in the presence of an electric field....

The microscopic dynamics of objects suspended in a fluid determines the macroscopic rheology of a suspension. For example, as shown by Danker and Misbah [Phys. Rev. Lett., 2007, 98, 088104], the viscosity of a dilute suspension of fluid-filled vesicles is a non-monotonic function of the viscosity contrast (the ratio between the viscosities of the internal encapsulated and the external suspendin...

This work reports on an evaluation of the computational fluid dynamics–discrete element method (CFD-DEM) numerical approach to study behavior polymer-filled suspensions in a parallel-plate rheometer. For this purpose, open-source CFD-DEM solver is used model such considering different particle volume fractions and types rheology. We first validate for single-phase flow continuum phase (fluid ph...