Aggregation shear-induced

In the stirred tank, the final mean size of particles was reduced by the increase of stirring rate, being consistent with increased fluid shear induced particle disruption relative to aggregation. Use of three different gas velocities in the bubble column, however, results in no significant difference in agglomerate size but since the size is relatively small, it may simply reflect an asymptotic value. 

Figure 5 Probable mechanism of shear-induced exchange reactions during melt flow process [33]. (1) Interaction of zinc stearate, (RCOO)2 Zn, with ionic aggregates before melt flow. (II) Exchange reactions during melt flow.

Ajzenberg N, Aubry R Huisse MG, et al. Enhanced shear-induced platelet aggregation in patients who experience subacute stent thrombosis a case-control study J Am Coll Cardiol 2005 45 1753-1756. 

The methods described below outline three dynamic adhesion/aggregation assays used to assess the in vitro and/or ex vivo efficacy of platelet antagonists (1) a viscometric-flow cytometric assay to measure shear-induced platelet-platelet aggregation in the bulk phase, (2) a perfusion chamber coupled with a computerized videomicroscopy system to visualize in real time and quantify (a) the adhesion and subsequent aggregation of platelets flowing over an immobilized substrate (e.g. extracellular matrix protein) and (b) free-flowing monocytic cell adhesion to immobilized platelets. 

Konstantopolous K, Kamat SG, Schafer AI et al. (1995) Shear-induced platelet aggregation is inhibited by in vivo infusion of an anti-glycoprotein Ilb/IIIa antibody fragment, c7E3 Fab, in patients undergoing coronary angioplasty. Circulation 91 1427-1431... 

Fig. 1. Quantification of shear-induced platelet aggregation by flow cytometry. Panel A corresponds to an unsheared blood specimen. Panel B corresponds to a blood specimen that has been subjected to a pathologically high level of shear stress for 30 sec. As can be seen in the figure there are three distinct cell populations. The upper population consists of platelets and platelet aggregates. The rbcs-plts population corresponds to platelets associated with erythrocytes and leukocytes. The wbcs population consists of some leukocytes that have elevated levels of FITC autofluorescence. The left vertical line separates single platelets (<4.5 xm in diameter) from platelet aggregates, whereas the right vertical line separates small from large platelet aggregates. The latter were defined to be larger than 10 xm in equivalent sphere diameter.

Oceda Y, Handa H Kamata T, Kawano K, Kawai Y, Watanabe K, Kawakami K, Sakai K, Fukuyama M, Itagaki I, Yodiioka A, Rugged ZM. Transmembrane calcium influx associated with von l ebrand factca binding to GP Ib in the initiation of shear-induced platdet aggregation. Thromb.HaemosL 1993 69 496-502. 

Capture efficiency, a, is defined as the fiaction of shear-induced collisiorrs between two platelets that result in doublets, i.e., the ratio of the rate of the measured initial aggregate formation for dilute suspensions (dN/dt) to the frequency of two-body coUisiorts in the suspension. 

Huang PY, HeUums JD. Aggregation and disaggregation kinetics of human blood platelet Part H. Shear-induced platelet aggrcgaticai. BiophysJ 1993 65 344-353. 

Jen CJ, MeIntireLV. Characteristics of shear-induced aggregation in whole blood. JLabCUuMed 1984 103 115-124. 

Exposure to a shear fleld causes more rapid crystallization as the presence of protruding crystals leads to more aggregation of crystalline droplets, similar to bulk-fat behavior. The rapid increase in the rate of droplet destabilization following crystal growth and protrusion is due to the shear induced by the less spherical... 

Oles V. Shear-induced aggregation and breakup of polystyrene latex particles. J Colloid Interface Sci 1992 154 351-358. 

Gustafsson, J., Nordenswan, E., and Rosenholm, J.B., Shear-induced aggregation of anatase dispersion investigated by oscillation and low shear rate viscometry, 7. Colloid Interf. Sci., 242, 82, 2001. 

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