Article

# Electrophoresis of concentrated colloidal dispersions in low-polar solvents.

Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
Journal of Colloid and Interface Science (Impact Factor: 3.17). 05/2011; 361(2):443-55. DOI:10.1016/j.jcis.2011.04.113
Source: PubMed

ABSTRACT We present a method to accurately measure the electrophoretic mobility of spherical colloids at high volume fractions in real space using confocal laser scanning microscopy (CLSM) and particle tracking. We show that for polymethylmethacrylate (PMMA) particles in a low-polar, density- and refractive-index-matched mixture of cyclohexylbromide and cis-decahydronaphthalene, the electrophoretic mobility decreases nonlinearly with increasing volume fraction. From the electrophoretic mobilities, we calculate the ζ-potential and the particle charge with and without correcting for volume fraction effects. For both cases, we find a decreasing particle charge as a function of volume fraction. This is in accordance with the fact that the charges originate from chemical equilibria that represent so-called weak association and/or dissociation reactions. Finally, as our methodology also provides data on particle self-diffusion in the presence of an electric field, we also analyze the diffusion at different volume fractions and identify a nonlinear decreasing trend for increasing volume fraction.

0 0
·
0 Bookmarks
·
73 Views
• ##### Article: Delayed feedback control via minimum entropy strategy in an economic model
[hide abstract]
ABSTRACT: In this paper minimum entropy (ME) algorithm for controlling chaos, is applied to the Behrens–Feichtinger model, as a discrete-time dynamic system which models a drug market. The ME control is implemented through delayed feedback. It is assumed that the dynamic equations of the system are not known, so the proper feedback gain cannot be obtained analytically from the system equations. In the ME approach the feedback gain is obtained and adapted in such a way that the entropy of the system converges to zero, hence a fixed point of the system will be stabilized. Application of the proposed method with different economic control strategies is numerically investigated. Simulation results show the effectiveness of the ME method to control chaos in economic systems with unknown dynamic equations.
Physica A-statistical Mechanics and Its Applications - PHYSICA A. 01/2008; 387(4):851-860.
• Source
##### Article: Probability Density Functions Of Some Skew Tent Maps
[hide abstract]
ABSTRACT: . We consider a family of chaotic skew tent maps. The skew tent map is a two-parameter, piecewise-linear, weakly-unimodal, map of the interval F a;b . We show that F a;b is Markov for a dense set of parameters in the chaotic region, and we exactly nd the probability density function (pdf), for any of these maps. It is well known, [1], that when a sequence of transformations has a uniform limit F , and the corresponding sequence of invariant pdf's has a weak limit, then that invariant pdf must be F invariant. However, we show in the case of a family of skew tent maps that not only does a suitable sequence of convergent sequence exist, but they can be constructed entirely within the family of skew tent maps. Furthermore, such a sequence can be found amongst the set of Markov transformations, for which pdf's are easily and exactly calculated. We then apply these results to exactly integrate Lyapunov exponents. 1. Introduction Let F a;b denote the two-parameter piecewise-linear map on ...
01/2000;
• ##### Article: Minimum entropy control of closed-loop tracking errors for dynamic stochastic systems
[hide abstract]
ABSTRACT: The entropy has been used to characterize the uncertainty of the tracking error for general nonlinear and non-Gaussian stochastic systems. A recursive optimization solution has been developed and the local stability condition of the closed-loop system has been established. The generality of this algorithm has been proved by the special case study of the minimum variance control for linear Gaussian systems.
IEEE Transactions on Automatic Control 02/2003; · 2.72 Impact Factor

17 Downloads
Available from
Nov 28, 2013