Statistical Modeling Applied to Deformation-Relaxation Processes in a Composite Biopolymer Network Induced by Magnetic Field

PLOS ONE, Dec 2019

This study investigated a methodology based on image processing and statistics to characterize and model the deformation upon controlled and uniform magnetic field and the relaxation under zero field of droplets observed in aqueous solutions of sodium alginate incorporating magnetic maghemite nanoparticles stabilized by adsorption of citrate ions. The changes of droplet geometry were statistically analyzed using a new approach based on the data obtained from optical microscopy, image processing, nonlinear regression, evolutionary optimization, analysis of variance and resampling. Image enhancement and then image segmentation (Gaussian mixture modeling) processes were applied to extract features with reliable information of droplets dimensions from optical micrographs. The droplets deformation and relaxation trends were accurately adjusted by the Kohlrausch-Williams-Watts (KWW) function and a mean relaxation time was obtained by fitting the time evolution of geometry parameters. It was found to be proportional to the initial radius of the spherical droplets and was associated to interfacial tension.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0169866&type=printable

Statistical Modeling Applied to Deformation-Relaxation Processes in a Composite Biopolymer Network Induced by Magnetic Field

January Statistical Modeling Applied to Deformation- Relaxation Processes in a Composite Biopolymer Network Induced by Magnetic Field Javier TarrÂõo-Saavedra 0 1 Ce cilia Galindo Gonza lez 1 Salvador Naya 0 1 Jorge Lo pez- Beceiro 1 Alain Ponton 1 0 Department of Mathematics, EPS. University of A Coruña. Avda. MendizaÂbal s/n. Ferrol. Spain , 2 Matière et Systèmes Complexes CNRS, UMR 7057, Universit e Paris Diderot-Paris 7 BaÃtiment Condorcet Case 7056, Paris, 3 Department of Industrial Engineering II, EPS. University of A Coruña. Avda. Mendiz aÂbal s/n. Ferrol. Spain 1 Editor: Jeffrey Chalmers, The Ohio State University , UNITED STATES This study investigated a methodology based on image processing and statistics to characterize and model the deformation upon controlled and uniform magnetic field and the relaxation under zero field of droplets observed in aqueous solutions of sodium alginate incorporating magnetic maghemite nanoparticles stabilized by adsorption of citrate ions. The changes of droplet geometry were statistically analyzed using a new approach based on the data obtained from optical microscopy, image processing, nonlinear regression, evolutionary optimization, analysis of variance and resampling. Image enhancement and then image segmentation (Gaussian mixture modeling) processes were applied to extract features with reliable information of droplets dimensions from optical micrographs. The droplets deformation and relaxation trends were accurately adjusted by the Kohlrausch-Williams-Watts (KWW) function and a mean relaxation time was obtained by fitting the time evolution of geometry parameters. It was found to be proportional to the initial radius of the spherical droplets and was associated to interfacial tension. - Data Availability Statement: All relevant data are within the paper. Funding: This research has been supported by the Spanish Ministry of Science and Innovation Grant MTM2014-52876-R (ERDF included). Competing Interests: The authors have declared that no competing interests exist. Introduction Nanocomposite materials composed of a polymer network in the presence of particles is nowadays a subject of intensive research due to the possibility to modulate their mechanical [ 1 ], optical, thermal [1±4], sound, magnetic, electric properties. Indeed these complex materials are potentially attractive to the development of many technologies such as electronics, optics, sensors, actuators, drug delivery and many other biotechnological areas. Nanoparticles of different nature (gold, silver, iron, cobalt, nickel, copper, alloys, metalderived quantum dots) can be incorporated into polymer network [ 5 ]. A special attention has been paid to magnetic nanoparticles to elaborate novel magnetoresponsive composites whose physical properties can be controlled by applying external magnetic field. In this case macroscopic behaviour is impacted by magnetic induced chain like or clustering structures. Thus, the study of microstructure is of decisive importance in order to get a better knowledge of these magnetoresponsive composites [ 6 ]. In this work, we propose a new methodology to study the deformation of magnetic field induced droplets and their relaxation when the magnetic field is switched off in an aqueous solution of biopolymer. For this purpose image enhancement techniques and an image segmentation procedure were applied to obtain data on size and shape changes of droplets. Then characteristic time of deformation and relaxation processes was obtained by a nonlinear parametric regression model as proposed by Kohlrausch, Willians and Watts (KKW) [7]. The experimental conditions are presented in the second section. The image processing techniques applied in the present study are introduced in the third section. In the fourth, the design of experiments is described while in the fifth one the results are shown and discussed before final conclusions in the sixth section. Experimental Materials The biopolymer was a polysaccharide extracted from marine brown algae, the alginic acid (Alginate). It is a linear copolymer containing β-1,4-D-mannuronate (M) and α-1,4-L-guluronate (G) units in various proportions and sequences depending on the season, age and the part of the plant used for extraction. With one carboxylate group in each M or G unit, alginate is a highly negatively charged polyelectrolyte at neutral or basic pH. Dissolving in water, the sodium ions and the carboxylate groups of the alginate are ionized to form the alginate polyelectrolyte and to deliver sodium ions in the medium. The used ferrofluid was an aqueous solution of ferromagnetic nanoparticles of maghemite (γ-Fe2O3) prepared by alkaline coprecipitation of ferric and ferrous salts in water [ 8 ]. Concentrated ammonium hydroxide is added to an acidic solution of iron (II) chloride and iron (III) chloride leading to the precipitation of anionic magnetite (Fe3O4) particles. After washing with distil (...truncated)


This is a preview of a remote PDF: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0169866&type=printable

Javier Tarrío-Saavedra, Cécilia Galindo González, Salvador Naya, Jorge López-Beceiro, Alain Ponton. Statistical Modeling Applied to Deformation-Relaxation Processes in a Composite Biopolymer Network Induced by Magnetic Field, PLOS ONE, 2017, Volume 12, Issue 1, DOI: 10.1371/journal.pone.0169866