Temperature dependence of the Soret coefficient of ionic colloids

Sehnem, André Luiz; Neto, A. M. Figueiredo; Aquino, Renata; Campos, Alex Fabiano Cortez; Tourinho, F.A.; Depeyrot, J.

doi:10.1103/physreve.92.042311

Cited by 42 publications

(42 citation statements)

References 42 publications

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“…The recent interest in the study of complex systems has led to an increased focus on anomalous diffusion [4-7, 36, 42, 45], which has been described in biological systems [42][43][44], protostellar birth [47], complex fluids [48][49][50][51][52][53], electronic transportation [54][55][56][57][58][59], porous media and infiltration [60][61][62], drug delivery [63][64][65][66], fractal structures and networks [67][68][69][70][71], and in water's anomalous behavior [72][73][74], phase transitions in synchronizing oscillators [39,40,[75][76][77], to name a few.…”

Section: Breakdown Of the Normal Diffusive Regimementioning

confidence: 99%

Anomalous Diffusion: A Basic Mechanism for the Evolution of Inhomogeneous Systems

et al. 2019

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In this article we review classical and recent results in anomalous diffusion and provide mechanisms useful for the study of the fundamentals of certain processes, mainly in condensed matter physics, chemistry and biology. Emphasis will be given to some methods applied in the analysis and characterization of diffusive regimes through the memory function, the mixing condition (or irreversibility), and ergodicity. Those methods can be used in the study of small-scale systems, ranging in size from single-molecule to particle clusters and including among others polymers, proteins, ion channels and biological cells, whose diffusive properties have received much attention lately.

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Section: Breakdown Of the Normal Diffusive Regimementioning

confidence: 99%

Anomalous Diffusion: A Basic Mechanism for the Evolution of Inhomogeneous Systems

et al. 2019

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“…The influence of interfacial effects on the thermophoresis have been studied systematically using microemulsions [19], but it turned out that it was not possible to describe the experimental results by using existing theories [19,20]. The best agreement between experiment and theoretical concepts are found for charged spherical and rod-like colloids [21][22][23], but when interfacial effects like the coverage by surfactants play a role, existing theoretical concepts fail [24]. For polar liquid mixtures, such as aqueous FA solutions, there is so far no microscopic theory to describe thermophoresis.…”

Section: Introductionmentioning

confidence: 68%

Heuristic Approach to Understanding the Accumulation Process in Hydrothermal Pores

Niether

Wiegand

2017

Entropy

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Abstract:One of the central questions of humankind is: which chemical and physical conditions are necessary to make life possible? In this "origin-of-life" context, formamide plays an important role, because it has been demonstrated that prebiotic molecules can be synthesized from concentrated formamide solutions. Recently, it could be shown, using finite-element calculations combining thermophoresis and convection processes in hydrothermal pores, that sufficiently high formamide concentrations could be accumulated to form prebiotic molecules (Niether et al. (2016)). Depending on the initial formamide concentration, the aspect ratio of the pores, and the ambient temperature, formamide concentrations up to 85 wt % could be reached. The stationary calculations show an effective accumulation, only if the aspect ratio is above a certain threshold, and the corresponding transient studies display a sudden increase of the accumulation after a certain time. Neither of the observations were explained. In this work, we derive a simple heuristic model, which explains both phenomena. The physical idea of the approach is a comparison of the time to reach the top of the pore with the time to cross from the convective upstream towards the convective downstream. If the time to reach the top of the pore is shorter than the crossing time, the formamide molecules are flushed out of the pore. If the time is long enough, the formamide molecules can reach the downstream and accumulate at the bottom of the pore. Analysing the optimal aspect ratio as function of concentration, we find that, at a weight fraction of w = 0.5, a minimal pore height is required for effective accumulation. At the same concentration, the transient calculations show a maximum of the accumulation rate.

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“…The authors verified that the coupling between the core and shell structures enhances the conversion of electromagnetic energy in the heat for hyperthermia treatments [22]. In another work [23], NPs based on CoFe 2 O 4 @γ-Fe 2 O 3 were investigated to verify the time dependence of the Soret coefficient and follow the modifications on physical parameters such as ζ potential and Seebeck coefficient of the electrolytes present in magnetic fluid solutions.…”

Section: Introductionmentioning

confidence: 95%

Local Structure Investigation of Core-Shell CoFe2O4@γ-Fe2O3 Nanoparticles

et al. 2020

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We investigate the local structure of nanoparticles based on cobalt ferrite core with and without a hydrothermal surface treatment of variable duration of time that promotes a coating shell by crossing information obtained from atomic absorption spectroscopy (AAS), X-ray powder diffraction (XRD), neutron powder diffraction (NPD), and X-ray absorption spectroscopy (XAS) measurements. Chemical titration results show that the surface layer thickness increases as the duration of the surface treatment increases. The cation distribution obtained by Rietveld refinement of NPD patterns allows splitting the core and shell structural parameters obtained from Rietveld refinement of XRD data of the samples well described in a core-shell model. We follow the local structural evolution with the surface treatment time analyzing both XANES and EXAFS regions of the absorption spectrum. As a result, we observe that the surface treatment is not energetically strong enough to provoke changes on the mean oxidation states of the cations in the spinel structure; indeed, the interatomic distances are similar to those found in bulk materials and the inversion degree remains the same after the surface treatment, in good accordance with the cation distribution obtained by Rietveld refinement of NPD data.

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Temperature dependence of the Soret coefficient of ionic colloids

Cited by 42 publications

References 42 publications

Anomalous Diffusion: A Basic Mechanism for the Evolution of Inhomogeneous Systems

Anomalous Diffusion: A Basic Mechanism for the Evolution of Inhomogeneous Systems

Heuristic Approach to Understanding the Accumulation Process in Hydrothermal Pores

Local Structure Investigation of Core-Shell CoFe2O4@γ-Fe2O3 Nanoparticles

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