Measurement of the Structural Unit in magnetic dispersions

Abstract

Abstract. Measurement of the Structural Unit (SU -containing both the solid phase and trappedfluid within their associated structures) in magnetic dispersions has been carried out using Hindered Settling (HS) analysis that uses scanning column magnetometry and cone & plate rheology techniques. From this, an equivalent Stokes' particle diameter, d, of (5.2 !" d !"#$%&"'()*+,-was determined that is approximately 22 times larger than the iron oxide particles of our formulation. A previous computer simulation based on HS theory produces complete concentrationheight profiles of the sedimenting system over time that compare well when using a correspondingly large trappedliquid fraction of around the #./" of the SU volume determined here, giving confidence in the result. As interest in iron oxide suspensions for potential biomedical and chemical decontamination/catalysis applications continues to grow an understanding of their structures is likely to become increasingly important.

The fabrication and characterization of stable core-shell superparamagnetic nanocomposites for potential application in drug delivery

“…This is indeed the case for the bare particle profiles of the main plot, with Stokes-like sedimentation evident in less than 1 h as indicated by the reduction in concentration throughout the top layers and with no fall of any "sludge line" as would be observed in hindered settling systems. 13 The stability measurements for the lipid-coated system are shown in the inset of Fig. 3 indicating a stable state has been achieved with no sedimentation evident at >30 h. Whilst an increase in stability to a few hours was observed in the silica-coated suspension (not shown), this will need to be increased if potential in vivo applications are to be realized.…”

The Observed Linearity and Detection Response of Magnetic Fluid Concentration Magnetometry—A Theoretical and Experimental Description

“…By scanning a column of dispersion with the coil, a complete concentration profile of the fluid as a function of height may be obtained. This provides the opportunity to go beyond simple stability studies and extend into investigations of the aggregation of particles into structural units that also contain trapped fluid [4].…”