31 research outputs found
Thixotropy in macroscopic suspensions of spheres
An experimental study of the viscosity of a macroscopic suspension, i.e. a
suspension for which Brownian motion can be neglected, under steady shear is
presented. The suspension is prepared with a high packing fraction and is
density-matched in a Newtonian carrier fluid. The viscosity of the suspension
depends on the shear rate and the time of shearing. It is shown for the first
time that a macroscopic suspension shows thixotropic viscosity, i.e.
shear-thinning with a long relaxation time as a unique function of shear. The
relaxation times show a systematic decrease with increasing shear rate. These
relaxation times are larger when decreasing the shear rates, compared to those
observed after increasing the shear. The time scales involved are about 10000
times larger than the viscous time scale and about 1000 times smaller than the
thermodynamic time scale. The structure of the suspension at the outer cylinder
of a viscometer is monitored with a camera, showing the formation of a
hexagonal structure. The temporal decrease of the viscosity under shear
coincides with the formation of this hexagonal pattern
Sistema de plantio de milho em fileiras duplas e simples em consĂłrcio com o feijoeiro comum
Épocas de consórcio de alho com cenoura em três sistemas de manejo de plantas daninhas, em Caçador-SC
Yield Formation in Mediterranean durum wheats under two contrasting water regimes based on path-coefficient analysis
Ribosomally synthesized and post-translationally modified peptide natural products: Overview and recommendations for a universal nomenclature
Covering: 1988 to 2012 This review presents recommended nomenclature for the biosynthesis of ribosomally synthesized and post-translationally modified peptides (RiPPs), a rapidly growing class of natural products. The current knowledge regarding the biosynthesis of the >20 distinct compound classes is also reviewed, and commonalities are discussed