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Nanoparticle diffusion coefficient

In the context of nano-impact data such as that in Fig. 8.7a it is best expressed as a plot of the cumulative number of impacts as a function of time. This can then be compared with an integrated foim of the Shoup-Szabo expression. Fitting the latter to the former so as to determine C, the unknown concentration of nanoparticles, requires a knowledge of re (which can be found by independent electrochemical calibration) and D, the nanoparticle diffusion coefficient. Given the large size of the nanoparticles the latter can be reliably calculated from the Stokes-Einstein equation... [Pg.163]

Ferrimagnetic nanoparticles of magnetite (Fc304) in diamagnetic matrices have been studied. Nanoparticles have been obtained by alkaline precipitation of the mixture of Fe(II) and F(III) salts in a water medium [10]. Concentration of nanoparticles was 50 mg/ml (1 vol.%). The particles were stabilized by phosphate-citrate buffer (pH = 4.0) (method of electrostatic stabilization). Nanoparticle sizes have been determined by photon correlation spectrometry. Measurements were carried out at real time correlator (Photocor-SP). The viscosity of ferrofluids was 1.01 cP, and average diffusion coefficient of nanoparticles was 2.5 10 cm /s. The size distribution of nanoparticles was found to be log-normal with mean diameter of nanoparticles 17 nm and standard deviation 11 nm. [Pg.50]

Generally, mean size and size distribution of nanoparticles are evaluated by quasi-elastic light scattering also named photocorrelation spectroscopy. This method is based on the evaluation of the translation diffusion coefficient, D, characterizing the Brownian motion of the nanoparticles. The nanoparticle hydro-dynamic diameter, is then deduced from this parameter from the Stokes Einstein law. [Pg.1188]

On a large scale, particles (as well as gases) are moved through the atmosphere by advection and turbulence, i.e., horizontal and vertical winds (Wexler et al. 1994 Seinfeld and Pandis 1998). Simultaneous with these large-scale motions are the smaller-scale processes that can transport particles across surface boundary layers (e.g., at the Earth s surface) and thus remove them. As discussed earlier, diffusion is the dominant removal mechanism for small particles because of their high diffusion coefficients and low gravitational settling velocities. Because of their very small sizes, nanoparticles can slip... [Pg.325]

The recent synthesis of model PMMA-grafted SiO2 nanoparticles with the flexibility of tuning grafting density and tc/L [112] provided a means to continue the investigations of along the already discussed path of parameter space. Their dynamic response should display common and distinct features compared with the established equilibrium dynamics of hard sphere colloids. The similarities should include the three aforementioned diffusion coefficients which are, however, expected to be quantitatively different because of the significant alteration of tire interaction potential. In addition, tlie curvature-dependent brush-like nature of the polymeric shell should be manifested in the osmotic pressure of the suspension and the associated dynamics of the total density fluctuations. [Pg.29]


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