Investigation of the Dynamic Properties of Magnetic Colloids PDF Download

Author: Colin S. Couper
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: María del Carmen Miguel López
Publisher:
ISBN:
Category :
Languages : en
Pages : 167

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"Our main goal is to study certain aspects of the dynamics of fluids with magnetic particles in suspension, based on their promising practical applications as new materials as welI as on its fundamental scientific interest.In the introduction we brief the reader on the most essential properties of the system. We have characterized the monodomain magnetic particles and the time scales inherent to magnetic fluids. Having introduced the rotational diffusion equation as the most convenient tool to take into account the different mechanism inftuencing the dynamics of the particles, we have also proposed a fruitful approach for solving it in any general situation. We have also highlighted the macroscopic properties of the magnetic fluid treated now as a continuous medium and showed up the different phenomena associated with the lack of stability in the system.In Chapter I we concentrate on two limit cases whose analysis is easier but very illustrative. The first part of the chapter is devoted to the study of a suspension of rigid dipoles, in which the magnetic moments are rigidly attached to the body of the particles themselves. In these conditions, if we apply an external magnetic field both the magnetic moment and the particle move together so that the magnetic torque acting upon it becomes zero. Thermal fluctuations tends to disrupt this order, and it turns out that, for instance, that the effective viscosity of the suspension depends on the dimensionless parameter comparing magnetic and thermal energies. In the second part we consider magnetic materials with finite anisotropy energy at high magnetic fields. For such monodomain particles the magnetic moments rapidly orient along the direction of the external field, and then as a second step the mechanical rotation of the particles takes place. In this case, the effective viscosity of the suspension is a function of the magnetic anisotropy constant of the material, of the volume of the particles as well as the thermal energy. Our results are compared to experimental measurements.The second chapter is concerned with the determination of the viscosity and of some magnetic and optical properties of magnetic fluids in the whole range of possible experimental situations. The magnetic moments and the particles inside the liquid reorient separately but their dynamics are coupled thus giving rise to a more intricate relaxation process. We have compared part of our results with available experimental data for different ferrofluids showing quite a good agreement.In Chapter III we joint to our discussion of magnetic fluids the presence of nonmagnetic particles of micrometer size and study their motion through the ferrofluid. The ferrofluid is considered now as a continuous medium with new transport coefficients already determined in the previous sections. Under the action of a rotating external magnetic field, we study the rotational motion of the nonmagnetic particles and compare our expressions to sorne measurements carried out in these composite systems. In this chapter we are also con cerned with the characterization of the hydrodynamic interactions among these particles in a carrier ferrofluid.Chapter IV is intended as a brief introduction to the multiple problems which arise when one handle the aggregation phenomena which may take place in these systerns. We study the kinetics of the forrnation of the aggregates by rneans of the Smoluchowski theory of coagulation in colloids. But we account for hydrodynarnic interactions which are not usually considered when studying such process and that gives rise to sorne corrections for high concentrations of particles. In addition, the rheology of the chains that are usually observed in systerns with dipolar interactions is given for a rather simplified situation in order to elucidate the effects of the dipolar magnetic interactions.Finally, we sum up our main conclusions and indicate some of the perspectives stimulated by the contents of this monograph and in which we plan to pursue work in the near future." -- TDX.

Author: Y. Iwasawa
Publisher: Elsevier
ISBN: 0080529356
Category : Science
Languages : en
Pages : 1129

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The purpose of this Conference was to discuss the results of recent developments and the future prospect in science and technology of the field. The field has been growing and flourishing, while indicating many problems to be uncovered and solved. The conference was structured to encourage interaction and to stimulate the exchange of ideas to accomplish the above purpose.Key issues and materials related to the Conference were included as follows: • Molecular Assemblies in Solutions; • Fine Particles and Colloidal Dispersions; • Supramolecular Organized Films; • Nanostructural Solid Surfaces; • Industrial Applications and Products.The Conference comprised 2 plenary lectures, 42 invited lectures, 150 oral presentations and 266 poster presentations.

Author: Nicolás O. Rojas
Publisher: BoD – Books on Demand
ISBN: 1789853796
Category : Science
Languages : en
Pages : 118

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This book presents a selection of works on pattern formation and stability of magnetic colloids. Magnetic liquids can be investigated in different scenarios. Geometry (quasi 1, 2 and 3 dimensional vessels ), scales (molecules, macroscopic particles) and the type of suspension (e.g., ferromagnetic, superparamagnetic) employed in experiments completely modify the aggregation process. The observed patterns in the fluid range from surface waves to bulk chains and bundles. The approaches presented in this book use standard statistical means such as the Gibbs free energy and chemical potential. Numerical works are implemented employing methods such as Monte Carlo or Langevin dynamics simulations. Kinetic theory is used in theoretical approaches being successfully applied to algorithms such as the Lattice-Boltzmann method.

Author:
Publisher:
ISBN:
Category : Medicine
Languages : en
Pages : 742

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Author: Xiaoting Rui
Publisher: Springer Nature
ISBN: 9819980488
Category :
Languages : en
Pages : 4383

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Author: Adarsh Sandhu
Publisher: Iph001
ISBN: 9780750315821
Category : Science
Languages : en
Pages : 0

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Magnetic Nanoparticles for Medical Diagnostics aims to encourage members of the medical profession to join experts from other fields of research in exploring the unique physical properties of magnetic nanoparticles for medical applications.

Author:
Publisher:
ISBN:
Category : Colloids
Languages : en
Pages : 850

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Author: Hiroyuki Ohshima
Publisher: Elsevier
ISBN: 0444626085
Category : Technology & Engineering
Languages : en
Pages : 533

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Colloid and Interface Science in Pharmaceutical Research and Development describes the role of colloid and surface chemistry in the pharmaceutical sciences. It gives a detailed account of colloid theory, and explains physicochemical properties of the colloidal-pharmaceutical systems, and the methods for their measurement. The book starts with fundamentals in Part I, covering fundamental aspects of colloid and interface sciences as applied to pharmaceutical sciences and thus should be suitable for teaching. Parts II and III treat applications and measurements, and they explains the application of these properties and their influence and use for the development of new drugs. - Provides a clear description of the fundamentals of colloid and interface science relevant to drug research and development - Explains the physicochemical/colloidal basis of pharmaceutical science - Lists modern experimental characterization techniques, provides analytical equations and explanations on analyzing the experimental data - Describes the most advanced techniques, AFM (Atomic Force Microscopy), SFA (Surface Force Apparatus) in detail

Author: P. Somasundaran
Publisher: CRC Press
ISBN: 9780849396083
Category : Science
Languages : en
Pages : 1152

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