The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
R Massart - One of the best experts on this subject based on the ideXlab platform.
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some biomedical applications of Ferrofluids
European Physical Journal-applied Physics, 1999Co-Authors: J Roger, R Massart, J N Pons, A Halbreich, J C BacriAbstract:Ferrofluids are colloidal solutions of iron oxide magnetic nanoparticles in either a polar or no polar liquid. We present here two biological applications using maghemite (γFe 2 O 3 ) Ferrofluids: magnetic cell sorting and magnetocytolysis. The first application employs magnetic particles binding a biological effector, which is capable to recognize the target cells specifically. These cells become magnetic and can be sorted in a gradient of magnetic field. We describe first the various steps of the synthesis of a biocompatible ferrofluid and the grafting an effector protein onto the particles. We then describe the use of particles carrying annexin V in the separation and quantification of damaged erythrocytes in blood samples. This very sensitive technique can be used to follow the erythrocytes ageing of normal blood samples during their storage under blood bank conditions or to detect the membrane modifications that are associated with some pathologies such as malaria or Alzheimer's disease. The dependence of the magnetic susceptibility versus the frequency is a way to transform magnetic energy into thermal energy. Magnetocytolysis is the destruction of cells, carrying magnetic particles, through the action of an alternating magnetic field (about 1 MHz). We present here preliminary experiments with macrophages, which demonstrate the method's feasibility and the formation of the non-specific interactions between the cells and the magnetic particles.
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Synthesis and properties of Mn-Zn ferrite Ferrofluids
Journal of Materials Science, 1999Co-Authors: E. Auzans, D. Zins, E. Blums, R MassartAbstract:A Mn-Zn ferrite ferrofluid is produced by chemical synthesis. Two different types of Ferrofluids, according to the type of carrier liquid, are synthesized: an aqueous cationic ferrofluid and a surfacted hydrocarbon-based one. Ferrite particles are characterized by using several techniques: X-ray diffraction, transmission electronic microscopy, IR-spectroscopy, thermogravimetry, magnetization measurements and chemical analysis. Particles size depends on the synthesis parameters and can be partly controlled by choosing the type of the coprecipitating base. Increasing of the Zn concentration leads to smaller size of synthesized particles, as well as effects the content of associated water. Magnetization of the ferrofluid significantly decreases when the degree of Zn substitution exceeds 0.5.
Mamdouh El Haj Assad - One of the best experts on this subject based on the ideXlab platform.
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numerical analysis of magnetic field effects on the heat transfer enhancement in Ferrofluids for a parabolic trough solar collector
Renewable Energy, 2019Co-Authors: Ali Khosravi, Mohammad Malekan, Mamdouh El Haj AssadAbstract:Abstract A parabolic trough is defined as a type of solar thermal collector that is straight in one dimension and curved as a parabola in the other two, lined with a polished metal mirror. Enhancing the thermal efficiency of this collectors is one of the major challenges of developing and growing of parabolic trough solar thermal power plants. Ferrofluids were proposed as a novel working fluid for industrial applications, due to their thermal performances. In this study, the convective heat transfer of Fe3O4-Therminol 66 ferrofluid under magnetic field (0–500 G) is evaluated using computational fluid dynamics. The ferrofluid with different volume fraction (1–4%) and the Therminol 66 (as the base fluid) are considered as the working fluids for a parabolic trough solar collector. Numerical analysis first validated using theoretical results, and then a detailed study is conducted in order to analyze the effect of the magnetic field on different parameters. The result demonstrated that using magnetic field can increase the local heat transfer coefficient of the collector tube, thermal efficiency as well as output temperature of the collector. In addition, increasing the volume fraction of nanoparticle in the base fluid and intensity of magnetic field increased the collector performance.
Stefan Odenbach - One of the best experts on this subject based on the ideXlab platform.
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Ferrofluids: Magnetically Controllable Fluids And Their Applications
2010Co-Authors: Stefan OdenbachAbstract:Synthesis and Characterization.- The Preparation of Magnetic Fluids.- Magnetic Spectroscopy as an Aide in Understanding Magnetic Fluids.- Magnetic and Crystalline Nanostructures in Ferrofluids as Probed by Small Angle Neutron Scattering.- Basic Theory.- Basic Equations for Magnetic Fluids with Internal Rotations.- Ferrohydrodynamics: Retrospective and Issues.- Ferrofluid Dynamics.- Heat and Mass Transfer Phenomena.- Rheological Properties.- Statistical Physics of Non-dilute Ferrofluids.- Magnetic Fluid as an Assembly of Flexible Chains.- Magnetoviscous Effects in Ferrofluids.- Magnetorheology: Fluids, Structures and Rheology.- Applications.- Targeted Tumor Therapy with "Magnetic Drug Targeting": Therapeutic Efficacy of Ferrofluid Bound Mitoxantrone.
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rheology of a ferrofluid based on nanodisc cobalt particles
Journal of Physics D, 2009Co-Authors: Hamid Shahnazian, D Graf, Yu D Borin, Stefan OdenbachAbstract:Rheological investigations as well as theoretical studies on Ferrofluids have shown strong field and shear dependent changes in viscosity, which are correlated with the formation of chain-like clusters of magnetic nanoparticles. Moreover, the formation of these clusters leads to the appearance of viscoelastic effects or other non-Newtonian features in Ferrofluids in the presence of a magnetic field. Previous investigations were carried out with differently composed Ferrofluids, all of them containing particles of nearly spherical shape, but differing in the size of the nanoparticles, the volume concentration and the magnetic material. In the work presented here a ferrofluid with non-spherical cobalt nanoparticles is used, to get more information about the influence of the shape of the nanoparticles on their interparticle interaction and the resulting rheological behaviour of the suspension. For the experiments an especially designed stress controlled rheometer has been used. Experiments on yield stress as well as measurements of the magnetoviscous effect have been performed for this ferrofluid with nanodisc particles for different magnetic field strengths. The results from the yield stress experiments have been compared with those achieved for a cobalt-based ferrofluid containing spherical nanoparticles.
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colloidal magnetic fluids basics development and application of Ferrofluids
LNP, 2009Co-Authors: Stefan OdenbachAbstract:Synthesis and Characterization.- Thermodynamics, Electrodynamics, and Ferrofluid Dynamics.- Surface Instabilities of Ferrofluids.- Ferrofluid Structure and Rheology.- Biomedical Applications of Magnetic Nanoparticles.- Technical Applications.
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investigation of the microscopic reason for the magnetoviscous effect in Ferrofluids studied by small angle neutron scattering
Journal of Physics: Condensed Matter, 2006Co-Authors: Loredana Mirela Pop, Stefan OdenbachAbstract:Experimental studies made on different ferrofluid samples under shear flow have shown that an increase of magnetic field strength yields an increase of the fluid's viscosity, the so-called magnetoviscous effect, while increasing shear rate leads to a decrease of the viscosity. The change of the viscosity with magnetic field strength can be theoretically explained as an effect of chain-like structure formation and therefore can be related to the modification of the microstructure of Ferrofluids. Using a specially designed rheometer, Ferrofluids having different magnitude of the magnetoviscous effect were investigated by small angle neutron scattering (SANS). Correlated to the structure formation in the fluid, the scattered intensity shows a variation with magnetic field and shear rate only for fluids with a high magnetoviscous effect. The results obtained show a good agreement with the qualitative model elaborated to explain the magnetoviscous effect, indicating a strong connection between the rheological behaviour of Ferrofluids and their microstructure.
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Microstructure and rheology of Ferrofluids
Journal of Magnetism and Magnetic Materials, 2005Co-Authors: Loredana Mirela Pop, Stefan Odenbach, A. Wiedenmann, Nina Matoussevitch, Helmut BönnemannAbstract:Abstract Experimental studies made for different ferrofluid samples under shear flow have shown that increasing the magnetic field strength yields an increase of the fluids viscosity, the so-called magnetoviscous effect, while increasing shear rate leads to a decrease of the magnitude of the viscosity (shear thinning). The change of the viscosity with magnetic field strength is theoretically explained as an effect of chain-like structure formation in Ferrofluids whereas its magnitude depends on the particle–particle interaction. Both effects, the shear thinning and the magnetoviscous effect, can therefore be related to the microstructure and microstructure dynamics of Ferrofluids. Using a specially designed rheometer, Ferrofluids having different magnitude of the magnetoviscous effect were investigated by small-angle neutron scattering. Correlated to the structure formation in the fluid, the scattered intensity shows a variation with the magnetic field and shear rate only in the case of the fluids with a high magnetoviscous effect. The presented results show that there is a strong connection between the rheological behaviour of Ferrofluids and their microstructure.
B Jeyadevan - One of the best experts on this subject based on the ideXlab platform.
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mn zn ferrite nanoparticles for ferrofluid preparation study on thermal magnetic properties
Journal of Magnetism and Magnetic Materials, 2006Co-Authors: R Arulmurugan, G Vaidyanathan, S Sendhilnathan, B JeyadevanAbstract:Abstract Mn1−xZnxFe2O4 (with x varying from 0.1 to 0.5) ferrite nanoparticles used for ferrofluid preparation have been prepared by chemical co-precipitation method and characterized. Characterization techniques like elemental analysis by atomic absorption spectroscopy and spectrophotometry, thermal analysis using simultaneous TG-DTA, XRD, TEM, VSM and Mossbauer spectroscopy have been utilized. The final cation contents estimated agree with the initial degree of substitution. The Curie temperature ( T c ) and particle size decrease with the increase in zinc substitution. In the case of particles with higher zinc concentration, both ferrimagnetic nanoparticles and particles exhibiting superparamagnetic behavior at room temperature are present. In addition, some of the results obtained by slightly altering the preparation condition are also discussed. The precipitated particles were used for ferrofluid preparation. The fine particles were suitably dispersed in heptane using oleic acid as the surfactant. The volatile nature of the carrier chosen helps in altering the number concentration of the magnetic particles in a ferrofluid. Magnetic properties of the fine particles and Ferrofluids are discussed. Ferrofluids having Mn0.5Zn0.5Fe2O4 particles can be used for the energy conversion application utilizing the magnetically induced convection for thermal dissipation.
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co zn ferrite nanoparticles for ferrofluid preparation study on magnetic properties
Physica B-condensed Matter, 2005Co-Authors: R Arulmurugan, G Vaidyanathan, S Sendhilnathan, B JeyadevanAbstract:Abstract Co–Zn substituted nanoferrites having stoichiometric composition Co1−xZnxFe2O4 with x ranging from 0.1 to 0.5 were prepared by chemical coprecipitation method. The precipitated particles were used for the preparation of ferrofluid. Ferrofluids having Co0.5Zn0.5Fe2O4 particles could be used for the energy conversion application utilizing the magnetically induced convection for thermal dissipation. The final estimated cation contents, agreed with the initial degree of substitution. The powder samples were characterized by XRD, TEM, VSM and Mossbauer studies. The precipitated particles showed single-phase fcc spinel structure for all compositions of zinc. The magnetic parameters such as Ms, Hc, Mr, Tc and particle size were found to decrease with the increase in zinc substitution. In the case of particles with higher zinc concentration, both ferrimagnetic nanoparticles and particles exhibiting superparamagnetic behavior were present. The fine particles were suitably dispersed in heptane using oleic acid as the surfactant. Volatile nature of the carrier chosen helped in altering the number concentration of the magnetic particles in a ferrofluid.
Ali Khosravi - One of the best experts on this subject based on the ideXlab platform.
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numerical analysis of magnetic field effects on the heat transfer enhancement in Ferrofluids for a parabolic trough solar collector
Renewable Energy, 2019Co-Authors: Ali Khosravi, Mohammad Malekan, Mamdouh El Haj AssadAbstract:Abstract A parabolic trough is defined as a type of solar thermal collector that is straight in one dimension and curved as a parabola in the other two, lined with a polished metal mirror. Enhancing the thermal efficiency of this collectors is one of the major challenges of developing and growing of parabolic trough solar thermal power plants. Ferrofluids were proposed as a novel working fluid for industrial applications, due to their thermal performances. In this study, the convective heat transfer of Fe3O4-Therminol 66 ferrofluid under magnetic field (0–500 G) is evaluated using computational fluid dynamics. The ferrofluid with different volume fraction (1–4%) and the Therminol 66 (as the base fluid) are considered as the working fluids for a parabolic trough solar collector. Numerical analysis first validated using theoretical results, and then a detailed study is conducted in order to analyze the effect of the magnetic field on different parameters. The result demonstrated that using magnetic field can increase the local heat transfer coefficient of the collector tube, thermal efficiency as well as output temperature of the collector. In addition, increasing the volume fraction of nanoparticle in the base fluid and intensity of magnetic field increased the collector performance.