Colloids particle tracking

Particle tracking also produced trajectory paths of the Pt/Au nanorods based on displacement data collected for the head and tail of each nanorod. The head is defined as the direction in which the nanorod moves. The trajectory paths clearly distinguish the motion of a Pt/Au nanorod from that of a Brownian colloidal cylinder moving under the influence of thermal energy (Fig. 3.1). In addition, the trajectory path helps visualize some of the defined physical parameters. 

Even in the absence of a colloid, an electrolyte solution will display electroosmotic flow through a chamber of small dimensions. Therefore the observed particle velocity is the sum of two superimposed effects, namely, the true electrophoretic velocity relative to the stationary liquid and the velocity of the liquid relative to the stationary chamber. Figure 12.10a shows the results of this superpositioning for particles tracked at different depths in the cell. The particles used in this study are cells of the bacterium Klebsiella aerogenes in phosphate buffer. Rather than calculated velocities or mobilities, Figure 12.10a shows the reciprocal of the time... 

Three-Dimensional Particle Tracking of Micronic Colloidal Particles... 

Single-particle tracking of colloidal particles is a direct way to obtain the size and the surface properties (roughness, zeta potential) of particles. 

Motivated by these experiments, Isa et al. conducted further studies of flows in similar geometries at the single particle level using confocal microscopy [129]. The system consisted of a hard-sphere suspension (PMMA spheres, radius 1.3 0.1 pm) at nearly random close packing, a paste , in a 20-particle-wide square capillary. The motion of individual colloids was tracked via CIT and velocity proflles were measured in channels with both smooth and rough walls. Despite the colloidal nature of the suspension, significant similarities with granular flow [164,165] were found. 

Fig. 14 Reprinted with permission from [111], copyright (2004), Institute of Physics Publishing, (a) Superposition of particle tracks in the zero-velocity plane plus one adjacent plane in a sheared colloidal crystal, showing zig-zag motion. The image size is 18.75 pm x 18.75 pm (256 x 256 pixels). The colloids have a diameter of 1.50 pm. (b) Measured shear rate vs applied shear rate for the colloidal crystal (points), the continuous line shows equahty of these two rates...

Particle tracking algorithms have also been used successfully in measurements of two- and three-dimensional diffusion [9], slip velocity [10], and colloidal electrokinetics [11]. In the context of experimental fluid mechanics studies, researchers found that the Brownian, thermal motion of sub-micron-sized particles suspended in a fluid is significant and may mask the... 

Grasselli, Y. and Bossis, G., Three-dimensional particle tracking of micronic colloidal particles, in Surface Characterization Methods, Milling, A. J. (Ed.), Surfactant Science Series, Vol. 87, Marcel Dekker, New York, 1999, pp. 269-284. 

M. T. Valentine, Z. E. Perlman, M. L. Gardel, et al. Colloid surface chemistry critically affects multiple particle tracking measurements of biomaterials. Biophys. J., 86 (2004), 4004 014. 

As mentioned in Sect. 1, particle tracking in time series of 3D images obtained using confocal microscopy is widely used in the studies of colloidal systems. The examples from fundamental research include colloids as model atoms [12, 67, 68],... 

Polyelectrolyte complex membranes are phase-inversion membranes where polymeric anions and cations react during the gelation. Inorganic ultrafiltration membranes are formed by depositing particles on a porous substrate. Dynamic membranes are concentration polarization layers formed in situ from the ultrafiltration of colloidal material analogous to a precoat in conventional filter operations. Track-etched membranes are made by exposing thin films (mica, polycarbonate, etc.) to fission fragments from a radiation source. 

In contrast to the modeling methods described above, simulation methods approach the mathematical description of colloid aggregation kinetics from a fundamentally different viewpoint these methods track particle and aggregate movement over one-, two-, or three-dimensional space. This chapter will only provide a brief introduction and overview of the types of simulation methods that have been developed, as this is a broad and growing field of research worthy of numerous volumes alone. The following discussion will proceed by defining four categories of simulations as follows, and as outlined in Table 3. 

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